CA1281224C - Emulsions and photographic elements containing silver halide grains having trisoctahedral crystal faces - Google Patents

Abstract

EMULSIONS AND PHOTOGRAPHIC ELEMENTS CONTAINING SILVER
HALIDE GRAINS HAVING TRISOCTAHEDRAL CRYSTAL FACES
Abstract of the Disclosure Silver halide photographic emulsions are disclosed comprised of radiation sensitive silver halide grains of a cubic crystal lattice structure comprised of trisoctahedral crystal faces.

Description

EMULSIONS AN~ PHOTOGRAPEIC EL~MENTS CONTAINING SILVER
HALIDE GRAINS ~AVING TRISOCTAH~DRAL CRYSTAL FACES
Field of ~ Invention This invention relates to photography. More specifically, thiæ invention is directed to photographic emulsions containing silver halide grains and to photographic elements containing these emulsions.
Brief Description of ~ Drawings Figure 1 is an isometric view of a regular cubic silver halide grain;
Figure 2 is a schematic diagram of the atomic arrangement at a silver bromide cubic crystal surface;
Figure 3 i8 an isometric view of a regular octahedral silver halide grain;
Figure 4 is a schematic diagram of the atomic arrangement at a silver bromide octahedral crystal surface;
Figure 5 is an isometric view of a regular rhombic dodecahedron;
Figure 6 is a schematic diagram of the atomic arrangement at a silver bromide rhombic dodecahedral crystal surface;
Figure 7 is an isometric view of a regular cubic silver halide grain, a regular octahedral silver halide grain, and intermediate cubo-octahedral silver halide grains.
Figures 8 and 9 are front and rear isometric views of a regular {331} trisoctahedron;
Figure 10 is a schematic diagram of the atomic arrangement at a silver bromide {331}
trisoctahedral crystal surface;
Figures 11 through 16, l9A, 19~, 19C, 20A, 21, 22A, and 22B are electron micrographs of trisoctahedral silver halide grains;
Figures 17A, 17B, 18A, and 18B are electron micrographs of silver halide grains which exhibit A

trisoctahedral protrusions;
Figures l9D and 20B are electron micrographs of octahedral silver halide grains; and Figure 23 is an electron micrograph of rhombic dodecahedral silver halide grains.
Background of the Invention Silver halide photography has been practiced for more than a century. The radiation sensitive silver halide compositions initially employed for imaging were termed emulsions, since it was not originally appreciated that a solid phase was present. The term "photographic emulsion" has remained in use, although it has long been known that the radiation sensitive component is present in the form o$ dispersed microcrystals, typically referred to as grains.
Over the years silver halide grains have been the subject of intense investigation. Although high iodide silver halide grains, those containing at least 90 mole percent iodide, based on silver, are known and have been suggested for photographic applications, in practice photographic emulsions almost al~ays contain silver halide grains comprised of bromide, chloride, or mixtures of chloride and bromide optionally containing minor amounts of iodide. Up to about 40 mole percent iodide, based on silver, can be accommodated in a silver bromide crystal structure without observation of a separate silver iodide phase. However, in practice silver halide emulsions rarely contain more than about 15 mole percent iodide, with iodide well below 10 mole percent being most common.
All silver halide grains, except high iodide silver halide grains, exhibit cubic crystal lattice structures. However, grains of cubic crystal lattice structures can differ markedly in appearance.

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~3--In one form silver halide grains when microscopically observed are cubic in appearance. A
cubic grain 1 is shown in Figure 1. The cubic grain iB bounded by six identical crystal faces. In the photographic literature these crystal faces are usually referred to as {100} crystal faces, referring to the Miller index employed for designating crystal faces. While the {100} crystal face designation is most commonly employed in connection 10 with silver halide grains, these same crystal faces are sometimes also referred to as {200} crystal faces, the difference in designation resulting from a difference in the definition of the basic unit of the crystal structure. Although the cubic crystal shape is readily visually identified in regular grains, in irregular grains cubic crystal faces are not always square. In grains of more complex shapes the presence of cubic crystal faces can be verified by a combination of visual inspection and the 90 angle of intersection formed by adjacent cubic crystal faces.
The practical importance of the {100}
crystal faces is that they present a unique surface arrangement of silver and halide ions, which in turn influences the grain surface reactions and adsorptions typically encountered in photographic applications.
This unique surface arrangement of ions as theoreti-cally hypothesized is schematically illustrated by Figure 2, wherein the smaller spheres 2 represent silver ions while the larger spheres 3 designate bromine ions. Although on an enlarged scale, the relative size and position of the silver and bromide ions is accurately represented. When chloride ions are substituted for bromide ions, the relative arrangement would remain the same, although the chloride ions are smaller than the bromide ions. It can be seen that a plurality of parallel rows, indicated by lines 4, are present, each formed by , . :.

lx~ 4 alternating silver and bromine ions. In Figure 2 a portion of the next tier of ions lying below the surface tier is shown to illustrate their relationship to the surface tier of ions.
In another form æilver halide grains when microscopically observed are octahedral in appear-ance. An octahedral grain 5 is shown in Figure 3.
The octahedral grain is bounded by eight identical crystal faces. These crystal faces are referred to as {111} crystal faces. Although the octahedral crystal shape is readily visually identified in regular grains, in irregular grains octahedral crystal faces are not always triangular. In grains of more complex shapes the presence of octahedral crystal faces can be verified by a combination of visual inspection and the 109.5~ angle of intersection formed by adjacent octahedral crystal faces.
Ignoring possible ion adsorptions, octahedral crystal faces differ from cubic crystal ~aces in that the surface tier of ions can be theoretically hypothesized to consist entirely of silver ions or halide ions. Figure 4 is a schematic illustration of a {111} crystal face, analogous to Figure 2, wherein the smaller spheres 2 represent silver ions while the larger spheres 3 designate bromine ions.
Although silver ions are shown at the surfaGe in every available lattice position, it has been suggested that having silver ions in only every other available lattice position in the surface tier of atoms would be more compatible with surface charge neutrality.
Instead of a surface tier of silver ions, the surface tier of ions could alternatively be bromide ions. The tier of ions immediately below the surface silver ions consists of bromide ions.
In comparing Figures 1 and 2 with Figures 3 and 4 it is important to bear in mind that both the cubic and octahedral grains have exactly the same .
.: '`., cubic crystal lattice structure and thus exactly the same internal relationship of silver and halide ions.
The two grains differ only in their surface crystal faces. Note that in the cubic crystal face of Figure 2 each surface silver ion lies immediately adjacent five halide ions, whereas in Figure 4 the silv~r ions at the octahedral crystal faces each lie immediately adjacent only three halide ions.
Much less common than either cubic or octahedral silver halide grains are rhombic dodecahedral silver halide grains. A rhombic dodecahedral grain 7 is shown in Figure 5. The rhombic dodecahedral grain is bounded by twelve identical crystal faces. These crystal faces are re~erred to as {110} (or, less commonly in reference to silver halide grains, {220}~ crystal faces. Although the rhombic dodecahedral crystal shape is readily visually identified in regular grains, in irregular grains rhombic dodecahedral crystal faces can vary in shape. In grains of more complex shapes the presence of rhombic dodecahedral crystal faces can be verified by a combination of visual inspection and measurement of the angle of intersection formed by adjacent crystal faces.
Rhombic dodecahedral crystal faces can be theoretica:Lly hypothesized to consist of alternate rows of si:Lver ions and halide ions. Figure 6 is a schematic :illustration analogous to Figures 2 and 4, wherein it can be seen that the surface tier of ions is formed by repeating pairs of silver and bromide ion parallel rows, indicated by lines 8a and 8b, respectively. In Figure 6 a portion of the ne~t tier of ions lying below the surface tier is shown to illustrate their relationship to the surface tier of ions. Note that each surface silver ion lies immediately adjacent four halide ions.

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Although photographic silver halide emulsions containing cubic crystal lattice structure grains are known which contain only regular cubic grains, such as the grain shown in Figure 1, regular octahedral grains, such as the grain shown in Figure 3, or, in rare instances, regular rhombic dodecahedral grains, such as the grain shown in Figure 5, in practice many other varied grain shapes are also observed. For example, silver halide grains can be cubo-octa-hedral -that is, formed of a combination of cubic and octahedral crystal faces. This is illustrated in Figure 7, wherein cubo-octahedral grains 9 and 10 are shown along with cubic grain 1 and octahedral grain 5. The cubo-octahedral grains have fourteen crystal faces, six cubic crystal faces and eight octahedral crystal faces. ~nalogous combinations of cubic and/or octahedral crystal faces and rhombic dodecahedral crystal faces are possible, though rarely encoun-tered. Other grain shapes, such as tabular grains and rods, can be attributed to internal crystal irregularities, such as twin planes and screw dislocations. In most instances some corner or edge rounding due to solvent action is observed, and in some instances rounding is so pronounced that the grains are described as spherical.
It is known that for cubic crystal lattice structures crystal faces can take any one of seven possible distinct crystallographic forms. However, for cubic crystal lattice structure silver halides only grains having {100} (cubic), ~111}
(octahedral), or, rarely, {110} (rhombic dodecahedral) crystal faces, individually or in combination, have been identified.
It is thus apparent that the photographic art has been limited in the crystal faces presented by silver halide grains of cubic crystal lattice structure. As a result the art has been limited in modifying photographic properties to the choice of surface sensitizers and adsorbed addenda that are workable with available crystal faces, in most instances cubic and octahedral crystal faces. This has placed restrictions on the combinations of materials that can be employed for optimum photo-graphic performance or dictated accepting less than optimum performance.
Relevant Art F. C. Phillips, An Introduction ~Q
Crystallographv, 4th Ed., John Wiley & Sons, 1971, is relied upon as authority for the basic precepts and terminology of crystallography herein presented.
James, The ~h~2ry Qf the Photographic 15 Process, 4th Ed., Macmillan, New York, 1977, pp. 98 through 100, iB corroborative of the background of the invention described above. In addition, James at page 98 in reference to silver halide grains states that high Miller index faces are not found.
Berry, ~Surface Structure and Reactivity of AgBr Dodecahedra", _otographic Sçience ~B~
~n~ineering, Vol. 19, No. 3, May/June 1975, pp. 171 and 172, illustrates silver bromide emulsions containing {110} crystal faces.
Klein et al, "Formation of Twins of AgBr and AgCl Crystals in Photographic Emulsions", PlLo-~Q-~raphische Korrespondenz, Vol. 99, No. 7, pp. 99-102 (1963) desc:ribes a variety of singly and doubly twinned silver halide crystals having {100}
(cubic) and {111} (octahedral) crystal faces.
Klein et al is of interest in illustrating the variety of shapes which twinned silver halide grains can assume while still exhibiting only {111} or ~100} crystal faces.
A. P. H. Trivelli and S. E. Sheppard, The Silver Bromide Grain of Photographic Emulsions, Van Nostrand, Chapters VI and VIII, 1921, is cited for ....

historical interest. Magnifications of 2500X and lower temper the value of these observations. Much higher resolutions of grain features are obtainable with modern electron microscopy.
W. Reinders, "Studies of Photohalide Crystals", ~olloid Zeitschrift, Vol. 9, pp. 10-14 (1911); W. Reinders, "Study of Photohalides III
Absorption of Dyes, Proteins and Other Organic Compounds in Crystalline Silver Chloride", Zeitschrift fur Physikalische Chemie, Vol. 77, pp. 677-699 (1911);
Hirata et al, "Crystal Habit of Photographic Emulsion Grains", l. Photo~. Soc. of Japan, Vol. 36, pp.
359-363 (1973); Locker U.S. Patent 4,1~3,756; and Locker et al U.S. Patent 4,225,666 illustrate teachings of modifying silver halide grain shapes through the presence of various materials present during silver halide grain formation.
Wulff et al U.S. Patent 1,696,830 and Eeki et al Japanese Kokai 58[1983]-54333 describe the precipitation of silver halide in the presence of benzimidazole compounds.
Halwig U.S. Patent 3,519,426 and Oppenheimer et al, "Role of Cationic Surfactants in Recrystalliza-tion of Aqueous Silver Bromide Dispersions", Smith Particle GrQ~h .and ~ ensiQ~, Academic Press, London, 1973, pp. 159-178, disclose additions of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene to silver chloride and silver bromide emulsions, respectively Summary of the Invention In one aspect this invention is directed to a silver halide photographic emulsion comprised of radiation sensitive silver halide grains of a cubic crystal lattice structure comprised of trisoctahedral crystal faces.
In another aspect this invention is directed to a photographic element containing at least one emulsion of the type previously described.

r .4 _9 _ The invention presents to the art for the first time the opportunity to realize the unique surface configuration of trisoctahedral crystal faces in photographic silver halide emulsions. The invention thereby renders accessible for the first time a new choice of crystal faces for modifying photographic characteristics and improving interac-tions with sensitizers and adsorbed photographic addenda.
Description of Preferred E.mbodiments The present invention relates to silver halide photographic emulsions comprised of radiation sensitive silver halide grains of a cubic crystal lattice structure comprised of trisoctahedral crystal faces and to photographic elements containing these emulsions.
In one form the silver halide grains can ta~e the form of regular trisoctahedra. A regular trisoctahedron 11 is shown in Figures 8 and 9, which are front and back views of the same regular trisoctahedron. A trisoctahedron has twenty-four identical faces. Although any grouping of faces is entirely arbitrary, the trisoctahedron can be visualized as eight separate clusters of crystal faces, each cluster containing three separate faces.
In Figure 8 faces 12a, 12b, and l~c can be visualized as members of a fir~t cluster of faces. A second cluster of faces is represented by faces 13a, 13b, and 13c. The third cluster of faces is represented by faces 14a, 14b, and 14c. Two faces 15a and 15b of a fourth cluster of faces is visible in Figure 8. One face each, 16a and 17a, of fifth and sixth clusters, respectively, are also visible in Figure 8.
In Figure 9 the third face ~5c of the fourth cluster of faces is visible as well as faces 16b and 16c of the fifth cluster of faces and faces 17b and 17c of the sixth cluster of faces. In addition, faces 18a, 18b, and 18c are shown forming a seventh ~' z~

cluster of faces and ffices l9a, 19b, and 19c forming an eighth cluster of faces.
Looking at the trisoctahedron it can be seen that there are three intersections of ad~acent f~ces within each cluster, and there is one face intersec-tion of each cluster with each of the three clusters ad~acent to it for a total of thirty-six face edge intersections. The relative &ngles formed by intersecting ~aces have only two different values.
All intersections of a face from one cluster with a face from another cluster are identical, forming a first relative angle. Looking at Figure 8, the relative ~ngle of ad~acent faces 12a and 15b, 12b and 16a, and 12c and 13c are all at the ldentical first relative angle. All ad~acent faces within each cluster intersect at the same relative angle, which is different from the relative angle of intersection of faces in different clusters. Looking at one cluster in which all faces are fully visible, the intersections between faces 12a and 12b, 12b and 12c, 12c and 12a are all at the same relative angle, referred to as a second relative angle. While the regular trisoctahedron has a distinctive appearance that can be recognized by visual inspection, it should be flppreciated that measurement of any one of the two relative angles provides a corroboration of ad~acen~ trisoctahedral crystal faces.
In crystallography measurement of relative angles of ad~acent crystal faces is employed for positive crystal face identification. Such tech-niques are described, for example, by Phillips~ cited above. These techniques can be combined with techniques for the microscopic examination of silver halide grains to identi~y positively the trisoctahe-dral crystal ~aces of silver halide grains.Techniques for preparing electron micrographs of silver halide grains are generslly well known in the art, as illustrated by B.M. Spinell and C.F. Oster, "Photographic M~terisls", The EncycloPedia of Microscopv and Microtechni~ue, P. Gray, ed., Van Nostrand, N.Y., 1973, pp.427-434, note psrticularly the section dealing with carbon replica electron microscopy on psges 429 and 430. Employing tech-niques well known in electron microscopy, carbon replicas of silver halide grains are first prepared.
The carbon replica~ reproduce the grain shape while avoiding shape altering silver print-out that is known to result from employing the silver halide grains without carbon shells. An electron scanning beam rather than light is employed for Lmaging to permit higher rsnges of msgnification to be realized than when light is employed. When the grains are sufficiently spread apart that ad~acent grains are not impinging, the grains lie flst on one crystal face rather than on a coign (i.e., a point). By tilting the sample being viewed relative to the electron beam a selected grain can be oriented so that the line of sight is substantially parallel to both the line of intersection of two ad~acent crystal faces, seen as a point, and each of the two inter-secting crystal faces, seen as edges. When the grain faces are parallel to the imaging electron beam, the two corresponding edges of the grsin which they define wil:L appear sharper than when the faces are merely close to being parallel. Once the desired grain orientation with two intersecting crystal faces presenting a parallel edge to the electron beam is obtained, the angle of intersection can be measured from an electron micrograph of the oriented grain.
In this way ad~acent trisoctahedral crystal faces can be identified. ~elative angles of trisoctahedral and ad~acent crystal faces of other Miller indices can also be determined in the same way. Again, the unique relative angle allows a positive identifica-tion of the crystal faces. While relative angle measurements chn be definitive, in many, if not most, instances vi~ual inspection of grains by electron m~croscopy allows im~ediate identification of trisoctahedral crystal faces.
Referring to the mutually perpendicular x, y, and z axes of h cubic cryst~l lattice, it is well recognized in the art that cubic crystal faces are parallel to two of the axes and intersect the third, thus the {100} Miller index assign~ent; octahe-dral crystal faces intersect each of the three axes at an equal interval, thus the {111} Miller index assignment; and rhombic dodecahedral crystal faces intersect two of the three axes at an equal interval and are parallel to the third axis, thus the {110} Miller index assignment. For a given definition of the basic crystal unit, there is one and snly one Miller index assignment for each of cubic, octahedral, and rhombic dodecahedral crystal faces.
Trisoctahedral crystal faces include a family of crystal faces that can have differing Miller index values. Trisoctahedral crystal faces are generically designated as {hhQ} crystal faces, wherein h and Q are different integers each greater than zero and h is greater than Q. The regular trisoctahedron 11 shown in Figures 8 and 9 consists of {331} crystal faces. A regular trisoctahedron having {221}, {441}, {551}, {332}, {552}, {443}, {553}, or {554} crystal faces would appear simllar to the trisoctahedron 11, but the differing Miller indices would result in changes in the angles of intersection. Although there ~s no theoretical limit on the maximum values of the integers h and Q, tri~octahedral crystal faces having a value o h of 5 or less are more easily generated. For this reason, silver halide grains having trisoctahedral crystal faces of the exemplary Miller index values identified above are preferred. ~ith practice one trisoctahedral crystal face can often be distin-guished visually from another of a different Millerindex value. Measurement of relstive angles permits positive corroboration of the specific Miller index value trisoctahedral crystal faces present.
In one form the emulsions of this invention contain silver halide grains which are bounded entirely by trisoctahedral crystal faces, thereby forming basically regular trisoctahedra. In practice although some edge rounding of the grains is usually present, the unrounded residual flat trisoctahedral faces permit po~itive identification, since a sharp intersecting edge is unnecessary to establishing the relative angle of ad~acent trisoctahedral crystal faces. Sighting to orient the grains is still possible employing the residual flat crystal face portions.
The radietion sensitive silver halide grains present in the emulsions of this invention are not confined to those in which the trisoctahedral crystal faces are the only flat crystal faces present. Just as cubo-octahedral silver halide grainq, such as 9 and 10, exhibit both cubic and octahedral crystal faces and Berry, cited above, reports grains having cubic, octahedral, and rhombic dodecahedral crystal faces in a single grain, the radiation sensitive grains herein contemplated can be formed by trisocta-hedral crystal faces in combination with any one or combination of the other types of crystal faces possible with a silver halide cubic crystal lattice structure. For example, if conventional silver halide grains having cubic, octahedral, and/or rhombic dodecahedral crystal faces are employed as host grains $or the preparation of silver halide ~ 2 ~ 2 ~

grains having trisoctahedral crystal faces, stopping silver halide deposition onto the host grains before the original crystal faces have been entirely overgrown by silver halide under conditions ~avoring S trisoctahedral crystal face formation results in both trisoctahedral crystal faces and residual crystal faces corresponding to those of the original host grain being present.
In another variant form deposition of silver halide onto host grains under conditions which favor trisoctahedral crystal faces can initially result in ruffling of the grain surfaces. Under close examination it has been observed that the ruffles are provided by protrusions from the host grain surface.
Protrusions in the form of ridges have been observed, but protrusions, when present, are more typically in the form of pyramids. Pyramids presenting trisocta-hedral crystal faces on host grains initially presenting {lll} crystal faces have three surface faces. These correspond to the three faces of any one of the 12, 13, 14, lS, 16, 17, 18, or 19 series clusters described above in connection with the trisoctahedron 11. When the host grains initially present {100} crystal faces, pyramids bounded by eight surface faces are formed. Turning to Figure 8, the apex of the pyramid corresponds to the coign formed faces 12a, 12c, 13b, 13c, 14a, 14b, 15a, and 15b. The protrusions, whether in the form of ridges or pyramids, can within a short time of initiating precipitation onto the host grains substantially cover the original host grain surfece. If silver halide deposition iC3 continued after the entire grain surface is bounded by trisoctshedral crystal faces, the protrusions become progressively l~rger and eventually the grains lose their ruffled appearance as they present larger and larger trisoctahedral crystal faces. It is possible to grow a regular ~8~LZ24 -lS-trisoctahedron from a ruffled grain by continuing silver halide depositlon.
Even when the grains are not ruffled and bounded entirely by trisoctahedrsl crystal faces, the grains can ta~e overall shapes differing from regular trisoctahedrons. This can result, for example, from irregularities, such as twin planes, present in the host grains prior to growth of the trisoctahedral crystal faces or introduced during growth of the trisoctahedral crystal faces.
The important feature to note is that if any crystal face of a silver halide grain is a trisocta-hedral crystal face, the resulting grain presents a unique arrangement of surface silver and halide ions that differs from that presented by all other poqslble crystal faces for cubic crystal lattice structure silver halides. This unique surface arrangement of ions as theoretically hypothesized is schematically illustrsted by Figure lO, wherein a {331~ trisoctahedral crystal face i5 shown formed by s7lver lons 2 and bromide ions 3. Comparing Figure 10 with Figures 2, 4, and 6, it is apparent that the surface positioning of silver and bromide ions in each figure is distinctive. The {331) trisoctahedral crystal face presents an ordered, but more varied arrangement of surface silver and bromide ions than 'Ls presented flt the cubic, octahedral, or rhombic dodecahedral ~ilver bromide crystal faces.
This is the re~ult of the tiering that occurs at the {331} trisoctahedral crystal face. Trisoctahe-dral cry~tal faces with differing Miller indices also exhibit tiering. The differin8 Miller indices result in analogous, but nevertheless unique surface arrangements of silver and halide ions.
It is to be noted that the arrangement of surface ions shown in Figure lO is not directly observable and is one of alternative surface ion ~B~ZZ4 arrangements that can be postulated. For example, inqtead of showing two rows of silver ions and one row of bromide ions in a tier, two rows of bromide ions and one row of silver ions per tier is equally plausible. Further, for simplicity the cry~tal surfaces have been shown At their highest possible level of regularity, whereas irregularities at cry~tal surfaces are generally accepted in silver halide crystallography.
While Figures 2, 4, 6, and 10 all contain bromide ionq as the sole halide ions, it is appre-ciated that the same observations as to differences in the crystal faces obtain when each wholly or partially contains chloride ions instead. Although chloride ions are substantially smaller in effective diameter than bromide ions, a trisoctahedral crystal surface presented by silver chloride ions would be similar to the corresponding silver and bromide ion surfaces.
The cubic crystal lattice structure silver halide grains containing trisoctahedral crystal faces can contain minor amounts of iodide ions, similarly aq conventional silver halide grains. Iodide ions have an effective diameter substantially larger than that of bromide ions. As i9 well known in silver halide crystRllography, this has A somewhat disrup-tive effect on the order of the crystal structure, which can be accommodated and actually employed photographically to advsntage, provided the iodide ions are limited in concentration. Preferably iodide ion concentrations below 15 mole percent and optimally below 10 mole percent, based on silver, are employed in the practice of this invention. Iodide ion concentrstions of up to 40 mole percent, based on silver, can be present in silver bromide crystals.
Since iodide ions as the sole halide ions in silver halide do not form a cubic crystal lattice structure, ~8~ 4 their use alone has no applicsbility to this invention.
It i5 appreciated that the larger the proportion of the total silver halide grain surface sreA accounted for by trlsoctahedral crystal faces the more distinctive the silver halide grains become. In most instsnces the trisoctahedrAl crystal faces account for at least 50 percent of the total ~urface area of the silver halide grains. Where the grain5 are regular, the trisoctahedral crystal faces can account for all of the flat crystal faces observable, the only remaining grain surfaces being attributable to edge rounding. In other words, silver halide grains having trisoctahedral crystal faces accounting for st least 90 percent of the total grain surface Area are contempl~ted.
It is, however, appreciated that distinctive photographic effects may be realized even when the trisoctahedral crystal faces are limited in areal extent. For example, where in an emulsion containing the silver halide grains a photographic addendum is present that shows a marked adsorptiGn preference for a trisoctahedral crystal face, only a limited percentage of the total gra~n surface may be required to produce a distinctive photographic effect.
Generally, if any trisoctahedral crystal face is observable on a silver halide grain, it accounts for a sufficient proportion of the total surface area of the 3ilver halide grain to be capable of influencing photographic performance. Stated another way, by the time a tri~octahedral crystal fsce becomes l~rge enough to be identified by its relfltive angle to ad~acent crystsl faces, it is slresdy large enough to be capable of lnfluencing photographic performance.
Thus, the minimum proportion of total grain surface srea accounted for by trisoctahedrsl crystal faces is limited only by the observer'~ sbility to detect the ~Z8~Z24 presence of tri~octahedral crystal faces.
The Quccessful formation of trisoctahedral crystal faces on silver halide grains of a cubic crystal lattice structure depends on identifying silver halide grain growth conditions that retard the surface growth rate on trisoctahedral crystal planes. It is generally recognized in silver halide crystallography that the predominant crystal faces of a silver halide grain are determined by choosing grain growth conditions that are least favorabls for the growth of thst crystal face. For example, regular cubic silver halide grains, such as grain 1, are produced under grain growth conditions that favor more rapid deposition of silver and halide ions on all other available crystal faces than on the cubic crystal faces. Referring to Figure 7, if an octahedral grain, such as regular octahedral gr~in 5 is sub~ected to growth under conditions that least favor deposition of silver and halide ions onto cubic crystal faces, grain 5 during continued silver halide precipitation will progress through the intermediate cubo-octahedral grain forms 9 and 10 before reaching the final cubic grain configuration 1. Once only cubic crystal faces remain, then silver and hallde ion5 deposit i~otropically on these surfaces. In other words, the grain shape remalns cubic, and the cubic grains merely grow larger as additional silver and halide ions are precipitated~
By analogy, grains having trisoctahedral crystal faces have been prepared by introducing into a silver halide precipitation reaction vessel host grains of conventional crystal faces, such as cubic or octahedral grains, while maintaining growth conditions to favor retarding silver halide deposi-tion along trisoctahedral crystal faces. As silverhalide precipitation continues trisoctahedral crystal faces first become identifiable and then expand in 12B~2z4 srea until eventually, if precipitation is continued, they account for all of the crystal faces of the silver halide grains being grown. Since trisoctahe-dral crystal faces accept addition~l silver halide deposition at 8 slow rate, renucleation can occur, creating a second grain population. Precipitaticn conditions can be ad~usted by techniques generally known in the art to favor either continued grain growth or renucleation.
Failure of the art to observe trisoctahedral crystal faces for silver halide grains over decades of intense investigation as evidenced by published silver halide cry~tallographic studies suggests th~t there is not an extensive range of conditions that favor the celective retarding of silver halide deposition along trisoctahedral crystal faces. It has been discovered that growth modifiers can be employed to retard silver halide deposit~on selec-tively ~t trisoctahedral cryst~l faces, thereby producing these trisoctahedral crystal faces as the external surfaces of the -~ilver h~lide grains being formed. The growth modifiers which have been identified are organic compounds. They are believed to be effective by reason of showing an sd~orption preference for a trisoctahedral crystal face by reason of it~ unique arrangement of silver and halide ions. Growth modifiers that have been empirically proven to be effective in producing triYoctahedral crystal faces are described in the examples, below.
The~e growth modifiers are effective under the conditions of their use in the examples. From empirical screening of a variety of candidate growth modifiers under differing conditions of silver halide pre~ipitation it has been concluded that multiple parameters must be satisfied to achieve trisoctahe-dral crystal f~ces, including not only the proper choice of a growth modifier, but also proper choice ~28~2Z4 of other precipitation parameters identified in the examples. Failures to achieve trisoctahedral crystal faces with compounds shown to be effective as growth modifiers for producing trisoctahedral crystal faces have been observed when accompanying conditions for silver halide precipitation heve been varied.
However, it is appreciated that having demonstrated success in the preparations of silver halide emulsions containing grains with trisoctahedral crystal faces, routine empirical studies systematlcslly varying parameters are likely to lead to additional useful preparation techniques.
Once silver hslide grain growth conditions are satisfied that ~electively retard silver halide depositlon at trisoctahedral crystal faces, continued grain growth usually results in trisoctahedral crystal faces appearing on all the grains present in the silver halide precipitation reaction vessel. It does not follow, however, that all of the radiation sensitive silver halide grains in the emulslons of the present invention must hsve trisoctahedral crystal faces. For example, silver halide grains having trisoctahedral crystal faces can be blended with any other conventional silver halide grain population to produce the final emul~ion. While silver halide emulsionq contalning any identiflable tri~octahedral crystal face grain surface are considered within the scope of this invention, in most applications the grains having at least one identifiable trisoctahedral crystal face account for at least 10 percent of the total grain population and usually these grains will account for greater than 50 percent of the total grain population.
The emulsions of this invention can be substituted for conventional emulsions to satisfy known photographic applications. In addition, the emulsions of this invention can lead to unexpected ~ 2~ Z4 photographic advantages.
For example, when a growth modifier is present adsorbed to the trisoctahedral cry~tal faces of the grsins and has a known photographic utility that is enhanced by sdsorption to a grain surface, either becsuse of the more intimate association with the grain surface or because of the r~duced mobility of the growth modifier, improved photogrsphic performsnce can be expected. The resson for this is that for the growth modifier to produce a trisoctahe-dral crystsl face it must exhibit an adsorption preference for the trisoctshedrsl crystal face that is greater than that exhibited for any other possible crystal fsce. This csn be apprecisted by considering growth in the presence of sn sdsorbed growth modifier of a silver halide grain having both cubic and trisoctahedral crystal faces. If the growth modifier shows an adsorption preference for the trisoctahedral crystal faces over the cubic crystal faces, deposi-tion of silver ~nd halide ions onto the trisoctahe-dral crystal faces is retsrded to a greater extent than along the cubic cryst~l fsces, and grain growth results in the eliminstion of the cubic crystsl faces in f~vor of trisoctahedral crystal faces. From the foregoing it is appflrent that gro~th modifiers which produce trisoctshedrsl crystsl faces sre more tlghtly ~dsorbed to these grsin surfaces than to other silver h~lide grsin surfsces during grain growth, snd this enhsnced sdsorption csrries over to the completed emulsion.
To provide an exemplsry photogrsphic sppl$cation, Locker U.S. Patent 3,g89,527 describes improving the speed of a photogrsphic element by employing sn emulsion contsining rsdistion sensitive silver hslide grsins having a spectral sensitlzing dye adsorbed to the grsin surfaces in combination with silver halide grsins free of spectrsl sensitiz-ing dye having an average diameter chosen to maximizelight SCAttering, typically in the 0.15 to 0.8 ~m range. Upon imagewise exposure radistion triking the undyed grains is scattered rather than being absorbed. This results in sn increased amount of exposing radiation striking the radiation sensitive imaging grains having a spectral sensitizing dye adsorbed to their surfaces.
A disadvantage encountered with th~s approach has been that spectral sensitizing dyes can migrate in the emulsion, 30 that to some extent the initially undyed grains adsorb spectral sensitizing dye which has migrated from the initially spectrally sensitized grains. To the extent that the initially spectrally sensitized grains were optimally sensi-tized, dye migration away from their surfaces reduces sensitization. At the same time, adsorption of dye on the grains intended to ~catter imaging radiation reduces their scattering efficiency.
In the examples below it is to be noted that a specific spectral sensitizing dye has been identified as a growth modifier useful in forming silver halide grains having trisoctahedral crystal faces. When radiation sensitive silver halide grains having trisoctahedral crystal faces and a growthmodifier spectral sensltizlng dye adsorbed to the trisocthhedral cryst~l faces are substituted for the spectrally sensitized silver halide grains employed by Locker, the disadvantageous migration of dye from the trisoctahedrhl crystal faces to the silver halide grains intended to scatter light is reduced or eliminAted. Thus, an improvement in photographic efficiency can be realized.
To illustrate another advantageous photo-graphic application, the layer structure of a multicolor photographic element which introduces dye image providing materials, such as couplers, during ~Z~ 4 processing can be simpllfied. An emulsion intended to record green exposures can be prepared using a growth modifier that is a green spectral sensitizing dye while an emulsion intended to record red S exposures can be prepared using a growth modifier that is a red spectrsl sensitizing dye. Since the growth modifiers are tightly fldsorbed to the grains and non-wandering~ instead of coating the green and red emulsions in separate color forming layer units, as is conventional practice, the two emulsions can be blended and coated as 8 single color forming layer unit. The blue recording layer can take any conventional form, and a conventional yellow filter layer can be employed to protect the blended green and red recording emulsions from blue light expo-sure. Except for blending the green and red recording emulsions in a single layer or group of layers differing in speed in a single color forming layer unit, the structur~ and processing of the photographic element is unaltered. If silver chloride emulsions are employed, the approach described above can be extended to blending in a single color forming layer unit blue, green, and red recording emulsions, and the yellow filter lAyer can be eliminated. The advantage in either case is a reduction in the number of emulsion layer~ required as compared to a corre~ponding conventional multi-color photographic element.
In more general applications, the substitu-tion of an emulsion according to the invention containing a growth modifier spectral sensitizing dye should produce a more invariant emulsion in terms of spectral propertie~ than a corresponding emulsion cont~ining ~ilver halide grains lacking trisoctahe-dral crystal faces. Where the growth modifier iscapable of inhibiting fog, such as the tetraaza-indenes shown to be effective growth modifiers in the 1~2~ 4 examples, more effective fog inhibition at lower concentrations may be expected. It is recognized that a variety of photographic effects, such as photographic sensitivityl minimum background density levels, latent image stability, nucleation, ~evelop-ability, image tone, absorption, and reflectivity, are influenced by grain surface interactions with other components. By employing components, such as peptizers, silver halide solvents, sensitizers or desensitizers, supersensitizers, halogen accepto.s, dyes, antifoggants, stabilizers, latent image keeping agents, nucleating agents, tone modifiers, develop-ment accelerators or inhibitors, development restrainers, developing agents, and other addenda that are uniquely matched to the trisoctahedral crystal surface, distinct advantages in photographic performance over that which can be realized with silver halide grains of differing crystal faces are possible.
The silver halide grains having trisoctahe-dral crystal faces can be varied in their properties to satisfy varied known photographic applications as desired. Generally the techniques for producing surface latent ima~e forming grains, internal latent image forming grains, internally fogged grains, surface fogged grains, and blends of differing grains described in ~search Disclosure, Vol. 176, December 1978, Item 17643, Section I, can be applied to the preparation of emulsions according to this inven-tion. Resear~h Disclo~e is published by KennethMason Publications, Ltd., Emsworth, Hampshire P010 7DD, England. The silver halide grains having trisoctahedral crystal faces can have silver salt deposits on their surfaces, if desired. Selective site silver salt deposits on host silver halide grains are taught by Maskasky U.S. Patents 4,463,087 and 4,471,050.

..

~81~

The ~rowth modlfier used to form the trlsoctahed~al crystal faces of the silver halide grsins can be retalned in the emulsion, Adsorbed to the 8raln faces, di~placed from the grain faces or destroyed entirely. For example, where, as noted above, the growth modlfler is also capable of ffcting as 8 ~pectrsl sen~Ltizlng dye or performing some other useful function, 1t is advantageou~ to retain the growth modifLer in the emulsion. Where the growth modlfier is not relied upon to perform an sdditional useful photographic function, its presence in the emulsion can be reduced or eliminated, if desired, once ltQ intended function i~ performed.
Th.Ls approach 19 advantageous where the growth modifier is at a1.1 di.sadvantageouQ in the environment of use. The growth modlfier can itself be modified by chemlcal i.nteractions, such as oxidation, hydrolysis, or addltion reactions, accomplished with reagents such as bromine water, ba~e, or acid-e.g., nltric, hydrochlorLc, or ~ulfuric acid.
Apart from the novel Brain structures :Identifled above, the rad.Lation sensitive sllver hallde emul~l.ons and the photogrsphic element3 in wh1ch tlley are lncorporated o~ this invention can take any convenlent conventional form. The emulsions can be washed as described ln Research Disclosure, Item 17643, clted above, Section II.
The radiation sensi.tlve silver halide grains of the emulslons can be surface chemically sensi-tized. Nobl.e metal (e.~ old), middle chalcogen(e.p,., sulfur, selenium, or tell.urium), and reducticn sensitizers, empl.oyed individually or in combination are specifical.l.y contempl.ated. Typical chemical sensltlzers are listed in Research Disclosure, Item __ _ l7643, clted above, Sectlon III. From comparison~ of surf~ce hallde and silver ion arran~ements in general the chemlcs1. sensltization response of silver halide lZ~ Z4 grQIns havlng trisoctahedral crystsl faces should be HnsloRous, but not iden~ic~l, to that of cubic and octahedral. silver halide grainq. That observation can be extended to emulqion addenda generally which adsorb to grain surfaces.
The ~llver halide emulsions can be spec-trally sensit.i7.ed with dyes from A vsriety of clss~es, lncludln~ the polymethine dye c18ss, which lncludes the cyanine~, merocyanines, complex cyanine~
and merocyanlnes (i~e., tri-, tetrs-, and polynuclear cyan:lnes ~nd merocyanines), oxonols, hemioxonol~, styryls, merosty~ylA, and ~treptocyanines. Illu~tra-tive spectra]. sensitizing dyes ~re di~closed in Research D:lscloqure, Item lt643, cited above, Section lS IV.
The silver halide emul~ion~ as well as other l~yers of the photographic etements of this invention can contain ~A vehicles hydrophilic colloids, employed alone or ln combination with other polymeric msterlals (e.~., latlceA). Suitable hydrophilic materia].s lnclude both natural.ly occurring ~ubstances such 8S proteins, proteLn derivatives, cellulose derivatlves -e.g., cell.ulose ester~, gelatin- e.g., alkall treated eel.stln (cattle, bone, or hide gelat:Ln) or acid t~eated gelatin (pigskin gelatin), eelQtln derJ.vatl.ves -e.e., acetylated gelatin, p~lthalsted gel.atln, and the like, polysaccharides such as dextran, gum arablc, zein, casein, pectin, col.lsgen der~vatlves, collodion, agQr-ag~r, arrow-root, and albumin. It is specifically contemplatedto employ hydrophilic col.lolds which contain a low proportion div~lent sulfur atom~. The proportion of dlvalent ~ulfur atoms can be reduced by treating the hydrophil~c colloid with a strong oxidizing agent, such aA hydroeen peroxide. Among preferred hydro-phil.ic col.l oi ds for use as peptizers for the emul.sions of th:ls invention are eelatino-peptizer~

1;~8~ 4 whlch contain les~ thsn 30 micromoles of methionine per gr~m. The vehicles ~-an be hardened by conven-tLonal procedures. Further det~lls of the vehicle~
snd hardeners sre provided in Research Disclosure, Item 17643, clted ~bove, Sections IX and X.
The silver halide photographic elemsnt3 of thls lnvention csn contaIn other addende conventionsl in the photogrsphic srt. Useful addenda sre descrlbed, l`or exsmple, Ln Research Disclosure, Item 176~3, cited above. Other conventional useful sddenda include sntifoggant~ and stabilizers, couplers (such ss dye forming couplerq, mssking couplers snd DIR couplers) DIR compounds, snti-stsin sgents, ~msge dye stabillzers, absorbing materials such ss fLlter dyes snd UV sbsorbers, light scatter-in~ msterlal~, sntistatlc sgents, coating aids, and plssticizers snd lubricants.
The photographic elements of the present .I.nvention can be simple black-and-white or monochrome elements comprisJ.nE, a support bearing a lsyer of the sLlver hsllde emulslon, or they csn be multilsyer snd/or multLcolor elements. The photogrsphic elements produce .Lmsges rsnging from low contrast to very h~ h contrast, such ss those employed for produc:lng half tone .Lmsges In graphic srts. They can be desiened lor processlnp, wlth sepsrste solutions or tor ln-csmera process:Lng. In the lstter instsnce the photo~raphic el.ements can include conventional image transfer features, such as those illustrated by Resesrch Disclosure, Item 1~643, cited above, Section XXIII. Multi.color elements contain dye ima8e forming uni.ts sensitive to esch of the three primsry regions of the spectrum. Each unit csn be compri~ed of a qingle emulsion lsyer or of multiple emulsion layers sens:LtiYe to 8 given region of the spectrum. The layer~ of the element, incl.uding the lsyers of the imap~e forming unLts, can be srrsnged in various ~lZ~ 24 orders as ~nown ln the art. In an alternative format, the emulsion or emul~ions can be disposed a9 one or more ~egmented l&yers, e.g., 8S by the use of microvessel~ or microcells, 8S descrLbed in Whitmore U.S. Patent 4,387,154.
A preferred ~ulticolor photographic element accordLng to thls invention containing incorporated dye image prov:l.dlng mater-Lals comprises a support bearlng at least one btue sen4itive silver halide emul.slon layer havlng associated therewith a yellow dye t`ormLng coupler, at least one green sen~itive sllver halide emul.sion layer having associated therewith a map,enta dye formin~ coupler, and at least one red sensitive silver halide emulsion layer hsving associated therewith a cyan dye forming coupler, at l.east one of the si.lver halide emulsion layers contsinln~, grains having trisoctahedral crystal faces as previously described.
The elements of the present invention can contain additi.onal layers conventional in photo-graphi.c el.ements, such as overcoat layers, spacer layers, filter layer~, antihal.stion lsyers, and scavenge~ layers. The support can be any suitable support u~ed wlth photographic elements. Typical supports include polymerLc fllms, paper (including polymer-coated paper), glass, and metal supports.
Deta:Lls re~,arding supports and other layers of the photographlc elements of thls Lnvention are contained Ln Research DJ.sclosurP, Item 17643, cited above, Section XVII.
The photographi.c elements can be imagewise expose~ wLth vQrious forms of energy, which encompass the ultraviolet, vlsible, and infrared regions of the electromagnetic spectrum as well as electron beam and beta radiatLon, eamma ray, X ray, alpha particle, neutron radiatLon, and other forms o corpuscular and wave-l.lke radiant energy in either noncoherent ~X8~'~Z4 (random phase) forms or coherent (in phase) forms, as produced by lasers. When the photogrsphic elements are intended to be exposed by X rays, they csn include festures found in conventional radiographic elements, such as those illustrated by Research Dlsclosure, Vol. 184, August 1979, Item 18431.
Processing of the im~gewise exposed photographic elements can be accomplished in any convenlent conventlonal msnner. Processing proced-ures, developlng agents, and development modifiersare illustrated by Research Dlsclosure, Item 17643, clted above, Sectlons XIX, XX, and XXI, respec~ively.
ExamPle~
The inventlon can be better appreciated by reference to the following specific examples. In each of the examples the term "percent" means percent by welght, unless otherwise indicated, ~nd all solutlons, unless otherwise indicsted, are aqueous solutlons. Dilute nitric acid or dilute sodium hydroxide was employed for pH adJustment, as required.
ExamPle 1 This example illustrates the prepar~tion of a trisoctahedral silver bromide emulsion having crystal faces of the Mlller index 1331}.
beginnlng wLth an octahedral host emulsion and using as growth modlfler Compound I, 4-hydroxy-6-methyl-1,3,8a,7-tetraazaindene, sodium salt.
To a reactLon vessel supplied with a ~tirrer was ~dded 0.05 mole of an octahedral silver bromide emulslon of mean graln size 1.3 ~m, containing 40 g/Ap, mole of gelatln. Water was ~dded to mske the total weight 50 g. To the emulsion at 40C was added 6.0 mllllmole/lnitlal Ag mole of Compound I dlssolved in 3 mL of wa~er. The emulsion was then held for 15 minutes at 40C. The pH was adJusted to 6.0 at 40C. The tempersture was raised to 60C, and the pAg adJusted to 8.5 at 60C with KBr and maintained ~Z81Z~4 st that value duri.ng the precipitation. A 2.0 M
solution of AgN03 was introduced at a constant rate over a perl.od of 40 minuteq, while a 2.0M solution of KBr was added as needed to hold the pAg constant. A
total o~ 0.016 mole Ag was added.
A carbon replica electron micrograph of the resultine trisoctahedral emulsion grains i~ shown in Fi~ure 11. The Mlller Index of the trlsoctahedral faces wa~ determLned by measurement of the relative angle between two adJacent trisoctahedral crystal faces. From this an~le, the supplement of the relative angle, whlch is the angle between their respectIve crystallographic vectors, ~, could be obtalned, and the Mil.ler index of the ad~acent trJ.soctahedral crystal faces was identified by comparison of thls anele ~ with the theoreticsl intersecting angle ~ between [hlhlQl] and [h2h2Q2] vector~. The angle e was calculated as descr~bed by Phillips, cited above, at pages 218 and 219.
To obtaln the angle ~, a carbon replica of the crystal. sampl.e was rotated on the ~tage of ~n electron microscope until, for a chosen crystal, the anele of observatIon was directly along the line of lntersection of the two ad~acent crystal fsces of interest. An electron m~cro~raph was then made, snd the relatIve anele was measured on the micrograph with a protractor. The supplement of the measured relative angle W2S the angle ~ between vectors.
Comparl.~on of ~ wi.th 0 enabled the crystal faces to be assi.gned. It` the experimentally determined an~le was nearly m.Id-wRy between two theoretical sngles, the one assoclated with the lower Miller lndex was used ~or the assignment.
~he angle measu~ement data for Examples 1 through 6 are listed ln Table I. The number of measurements made Is glven ln parentheses. Mea~ure-1'~8~ 4 ment lndlcated thst the trisoctahedra prepfired in thl~ exsmple were of Mi.l.ler index {331}. Miller lndices a~ high ~s [554} were considered.
Example 2 This example illustrstes the preparation of a ~risoctahedra]. s~lver bromide emulsion having cry~tal faces of the M~.ller i.ndex {331}, beginnin~ with a cubic ho t emulsion and us~ng as growth modifier Compound II, 5-bromo-4-hydroxy-6-methyl-1,3,3s,7-tetraazaindene.
To a reaction vessel supplied with a ~tirrer was added ?9 e of water snd 21.6 g (0.05 mole) of a cubic ~llver bromlde emulsi.on of mean grain size 0.8 ~m, contalnlng about 10 g/Ag mole of gelatin. To the emulslon at 40C were added 6.0 millimole/inltial Ag mole o~ Compound II dLssolved in 3 mL water and 3 drops of trlethylsmi.ne. The emulsion was then held for 15 minutes at 40~C. The pH w2s ad~usted to 6.0 et 40C. The temperature was raised to 60C, and the pAg ad~usted to 8.5 at 60C with KBr and m~intained at that value during the precipitation. A 2.5M
sol.ution of AgN03 was introduced at a constant rate over a perlod of 175 minutes while a 2.5M solution of KBr wa~ added as needed to hold the pAg constant. A
total of 0.0875 mole Ag was added.
A carbon repli.ca el.ectron mlcrograph of the resultlne trlsoctahedral emulslon erains ls shown in Fi.~ure l2. The Mill.er index was determlned to be {331} by the measurements listed in Table I, uslng the method described for Example 1.
ExamPle 3 Thls example il.l.ustrates the preparation of a trlsoctahedral silver bromide emulsion having the Miller l.ndex {331~, beglnning wi.th a cubic host emulsicn and using Compound III, 4-hydroxy-2-methyl-thlo-1,3,3a,7-tetraaz~indene, a~ growth modifier.

~ 8 This emulsion w~s prepared ~Q described in Example 2, except thst the growth modifier wss 6 m.i1.1imole/initihl Ag mole of Compound III. The preclpit~tion was carried out for 125 minutes, con~uming 0.0625 mole Ag.
An electron mlcrograph of the re~ultlng trisoctahedral emuJ.~lon erain~ is ~hown in Figure 13 The Miller index wss determined ~o be ~331}
by the measurement3 llated in Tsble I, using the method descrtbed for Example 1.
Exsmple 4 This ex~mple i1.1ustr~tes the preparstion of & trisoctahedrs1. sl.lver bromide emulsion hsving crystal. fsces of the Miller index ~331}, beg:lnnlng with an octahedrsl host emulsion snd using ss a growt}l modifier Compound IV, 4-smino-6-methyl-1,3,3a,'~-tetraazsindene.
To a react.lon vessel supplied with a qtirrer wa~ added 0.05 mole of an octahedral Yilver bromide emulsion of mean grsl.n size 0.8 ~m, contsining sbout 10 g/Ag mole of gelatln. Wster was sdded to mske the total welght 50 e To the emulsion ~t 40C
was sdded 6.0 mil.1.lmole/initial Ag mole of Compound IV, disso1.ved ln 2 mL of methanol. The emulsion wss then held for 15 mtnutes ~t 40C. The pH WAS
sd3usted to 6.0 st 40C. The temperature was rsised to 60C, and the pAg was sd~usted to 8.5 at 60C with KBr and malntained st thst vslue durin~ the precipi-tstion. A ~,5M solution of AgN03 wss introduced st a constant rate over a perlod of 100 minutes while a 2.5M soJ.utlon of KBr was sdded ss needed to hold the pAg constant. A tot~l o~ 0.050 mole A8 W8S Added.
An electron microgrsph of the resultlng tri~octshedral emulsion gr~ins ls shown in Figure ].4, The Mil.ler index wss determined to be {331}
by the messurements ll~ted in Tsble I, using the method de~crlbed for Example 1.

~L~8~ 4 Example 5 Emul.sion Example 5 illustrate-q the prepara-tion of a trisoctahedrRI. sIlver bromide emul~ion having crystsl faces of the Miller index {441}, beginning wlth a cubic host emulsion and using Compound V, 2-lm.Ldazolidinethione, 8S a growth modifier.
To a reaction vessel qupplied with a stirrer wss sdded O.OS moles of a cubic silver bromide emulsion of mean grain slze 0.8 ~m, containing about 10 g/AF, mole of ~elatin. Wster was added to make the total weLght 50 g. To the emulsion at 40~C
wa~ added 6.0 millimole/initIal Ag mole of Compound V, dissolved in 3 mL of methanol. The emulsion was then held for 15 mlnutes at 40C. The pH was adJusted to 6.0 at 40C and maintained constant durinp, the precipitatlon (pH 5.94 at 60C). The temperature was rai.sed to 60~C, and the pAg ad~usted to 8.$ at 60C w-J.th KBr and maintained at thst value dur:Lng the precip:Ltstion. A 2.5M solution of AgNO3 was introduced at a con tant rate over a period of ~5 minutes whlle a ~.SM solution of KBr wa~ added 8S
needed to hold the pAg constant. A total of 0~0125 mole Ag was added.
An electron microp,raph of the resulting trisoctahedral erains is shown ln Figure 15. The Mlller .Index was determlned to be ~441} by the measurement~ listed ln Table I, using the method described for Example 1.
ExamPle 6 Thls example lllustrates the preparstion of a trisoctahedrsl silver chloride emulsion having {331} Mi1.ler Index crystal faces, using a cubic s.Ilver chloride host emul.si.on and Compound IV a~ a growth modifier.
To a reactlon ve~el supplied with a stirrer was added 0.05 mole of a cubic silver chloride emulslon oi` mean graln Rize 0.65 ~m and containing 40 g/Ap~ mole gelati.n. Water was sdded to make the total we:Lght 42 g, then 7 mL (0.0245 mole) of a 3.5M
NaCl solution. To the reRulti.ng mixture were dded 3.0 mlll:Lmole/lnltia]. A~ mole of Compound IV, dissolved :In 2 mL of methanol. The emulsion was held 15 minutes at 40C. The temperature W8~ then raised to 50C. The pH was ad~u~ted to 6.0 at 50C, &nd malntained at thLs value durLng the precipitation.
The P~e was fletermined to be 8.5 and was maintsined during the precipitation. A 2.5M solution o$ AgNO3 was Lntroduced st a constant rste over a period of 100 minute.~, while a 3.5M solution of NsCl WP5 added as needed to hold the PAe con~tant. A total of 0.050 lS mole Ag was added.
An electron m~.crograph of the resulting trisoct~hedral emulsion ~rains is ~hown in Figure 16. The Mll.ler Lndex wa~ determlned to be t331}
by the measurements llsted in Table I, using the 0 method descrlbed for Example 1.
Table I
Anp~le Mea~urement Data An~le Ml.ller Growth Between Vectors Index Hallde Modlfier TheoretLcal l221} 38.9 27.3 ~3~ 26.5 37.9 {332~ 50.5 17.3 " {441} _ 20.1 43.3 ll {443} 55.9 12.7 " {551} - - 16.1 46.7 " ~552l - 31.6 33.6 " {553} - 50.0 21.2 " {55~t} - 59.0 10.0 ~'~ 8 Table I (cont'd) Angle Mea~urement_Data Mlller Growth Angle Between Vector~
ExamPle Index Hallde Modifier 1 l331~ AgBr I 27.8~1.0(4) 39.4+2,6(8) 2 ~331~ AgBr II 26.8~1.4(8) 39.0+1.4(5) 3 l331~ AgBr III 28.5(l) 4 1331} AgBr IV 29.5~0,7(13) [441~ AgBr V 43,4~0.8(7) 6 {331} AgCl IV 26.7+0.6(3) Example 7 ThLs example il.lustrstes additional investigatlons of potentisl growth modifier~ and l,ists potent:lal p,rowth modifiers investigated, but not observed to produce trisoctahedral crystQl faces.
The g~ai.n growth procedures employed were of three dlfferent type~:
A. The first grain growth procedure was as follows: To a reaction vessel supplied with a stirrer was added 0.5 e of bone gelatin di~olved in 28.5 g of wster. To this was added 0.05 mole of sllver bromide ho~t graln emulsion of mean grain ~ize 0.8~m, contalnlng about lOg/Ag mole gelstin, and having a total weieht of 21.6 g. The emulsion wa~
heated to 40C, and 6.0 mi~.l.lmoleq/Ag mole of dlssolved growth modifler were added. The mixture was held for 15 min. st 40C. The pH was ad~usted to 6.0 at 40C. The emulsion was then hested to 60C, and the pAg was adJusted to 8.5 at 60C with KBr snd maint~i.ned at that val.ue during the precipi-tatlon. The pH, whLch ~hlfted to 5.52 at 60C, W8S
held at that value therea~ter. A 2.5M solution of AgN03 Qnd a 2.5M sol.ution of KBr were then introduced with a constan~ sllver addition rate over a perlod of 125 min., consuming 0.0625 mole Ag.
B. The second grain growth procedure was as follows: To a reaction vessel supplied with a ~LZ~lr~ ~ 4 ~tirrer wa~ sdded 27.5 mL of wster. To this was added 0.05 mole of ~ ~ilver bromide host gr~in emulsion of mean grain ~ize 0.8 ~m, containing sbout 10 g/Ag mole of gelatin ~nd having a totsl weLght of 21.6 g. The emulsion w~ heated to 40C, snd 3.0 mlllimoletinltlsl Ae mole of dissolved growth modlfier was added. The mixture was held st 40C for 15 mln. Just prLor to beginning the precipitstion 3.4 mill.lmoles ot an aqueous (NH4)2SO4 go'ution (1.0 mL), cont~lnLng also 0.25 millimole of KBr, wss ~dded, followed by 25.9 millimoles of smmonium hydroxlde (2.0 m~.). The pAg wss me~sured 89 9 . 3 at 40C and was maintained st th~t level throughout the precipitatLon. At 40C ~ 2.5M solution of AgNO3 wss added at a con~tant flow rate slonQ with a 2.5M
solutlon of KBr, the latter being added st the rste necess~ry to m~i.nts.ln the pAg. The precipitation consumed 0.05 mole Ae over A period of 100 min. The pH was then slowly ad~usted to 5.5.
In the fi.rst snd 3econd procedures cubic or octahedrsl. host Krsins were employed ~5 noted in Table I Small ssmples of emul~Lon were withdrawn at lntervals during the preclpltation for electron mlcroscope examLnation, any trisoctahedrsl crystal faces reve~led ln such ssmples Are reported in Table II.
C. The thlrd gr~in growth procedure employed ~.5 mll.l.imoles of a freshly prepsred very flne grAln (spproxlmstely 0.02 ~m) AgBr emulsion to which w~s ~dded 0.09 millLmole of growth modifier.
In this procPss the~e very fine AgBr gr~ins were dissolved snd repreclpitated onto the host grsin3.
The host 8rain emul.~ion contsined 0.8 ~m AgBr gra:Lns. A ~.5 mil.lLmole portlon of the host grain emulsion was sdded to the very fine grain emulsion.
A pH of 6.0 snd pAg of 9.3 st 40 C wss employed.
The mlxture was stirred ~t 60 C for sbout 19 hours.

~za~ 4 The crystsl f~ces presented by the host ~r~ins sre ~s noted in Tsble II. Where both octahedrsl and cublc host grains are noted using the ssme growth modifier, 8 mixture of 5.0 millimoles cubic gralns of 0.8 ~m and 2.5 millimoles of octahedrs~ ~rsins of 0.8 ~m w~s employed giving approxi.mately the same number of cublc and octahedral host gr~ins. In looklng ~t the grains produced by ri.penlng, tho~e produced by ripenLng onto the cubic ~ralns were readlly vi4uslly di~tinguished, sLnce they were l.arger. Thus, lt wss possible in onP
rlpen.Lng process to determine the crystal faces produced uslne both cubic and octshedral host greins.
D:Lfferences in .Lndividual precipitetion~ sre 1nd5Lcgted by footnote. The {hhQ} surface column 5.n Tsb1.e II refers to those surfaces which sstisfy the deflnition above for tri.soctahedr~l crystel fsces.

~L281~24 T A B L E II
~hhQ} Host Growth Modifier Surfaces Grains Method 1 5-Nitro-o-phenylene-gusnidine nitrate None cubic C
2 Citric acid, tri-sodium ~alt None cubic C
3 5-Nitroindazole None cubic C
None octahedral C
10 4 1-Phenyl-5-mercapto- None octahedral tetrazole (1)(2) A
5 5-Bromo-1,2,3-benzo- None cubic A
triazole None octahedral C

6 6-Chloro-4-nitroben- None cubic C
zo-1,2,3-triazole None octahedral C

7 5-Chloro-1,2,3-ben- None cubic C
zotriazole None octahedral C

8 5-Chloro-6-nitro-1,2,3-benzo-triazole None cubic C

9 3-Methyl-1,3-benzo-thiazolium None cubic C
P-toluenesulfonate None octahedral C

10 4-Hydroxy-6-methyl-1,3,3a,7-tetra-azaindene, sodlum ~alt ~331} octahedral C

11 4-Hydroxy-6-methyl-2-methylmercapto-1,3,3a~7-tetraaza-indene None cubic A

12 2,6,8-Trichloro- None cubic C
purine None octahedral C

13 2-Mercapto-l-phenyl- None cubic C
benzimidazole None octahedral C

~2 ~ 2 T A B L E II (Continued) {hhQ~ Host ~rowth ModifierSur~aces Grains Method 14 3,6-Dimethyl-4-hy-droxy-l 9 2,3a,7- None cubic C
tetraazaindene None octahedral C

15 5-Carboxy-4-hydroxy-1,3,3a,7-tetraaza- None cubic C
indene None octahedral C

16 5-Carbethoxy-4-hy-droxy-1,3,3a,7-tetraazaindene None cubic A

17 5-Imino-3-thioura- None cubic C
zole None octahedrsl C

18 2-Formamidinothio-methyl-4-hydroxy-6-methyl-1,3,3a,7- None cubic C
tetraazaindene None octahedral C

19 4-Hydroxy-2-~-hy-20droxyethyl-6-methyl-1,3,3a,7- None cubic C
tetraaza~ndene None octahedral C

20 6-Methyl-4-phenyl-mercapto-1,3,3a,7- None cublc C
25tetraazaindene None octahedral C

21 2-Mercapto-5-phenyl- None cubic C
1,3,4-oxadiazole None octahedral C

22 l,10-Dithia-4,7,13,16-tetra- None cubic C
30oxacyclooctadecane None octahedral C

23 2-Mercapto-1,3-ben- None cubic C
zothiazole None octahedral C

24 6-Nitrobenzimidazole None cubic (3) A

25 5-Methyl-1,2,3-ben- None cubic C
zotriszole None octahedral C

~8~ 4 -4o-T A B L E II (Continued) {hhQ} Ho t Growth ModifierSurfaces Zrains Method 26 Urazole None cubic C
None octahedral C

27 4,5-Dicarboxy-1,2,3-triazole, monopo- None cubic C
tassium salt Yes octahedral C

28 3-Mercapto-1,2,4- None cubic C
triszole None octahedral C

29 2-Mercspto-1,3-benz- None cubic C
oxazole None octahedr&l C

30 6,7-Dihydro-4-meth-yl-6-oxo-1,3,3a,7- None cubic C
tetraazaindene None octahedral C

31 1,8-Dihydroxy 3,6- Ncne cubic C
dithiaoctane None octahedral C

32 5-Ethyl-5-methyl-4-thiohydantoin None cubic A

33 Ethylenethiourea {441} cubic A
None octahedral A

34 2-Carboxy-4-hydroxy-6-methyl-1,3,3a,7- None cubic C
tetraazaindene None octahedral C
25 35 Dithiourazole None cubic C
None octahedral C
36 2-Merc:aptoimidazole None cubic A
37 5-Cart>ethoxy-3-(3-carboxypropyl)-4-methyl-4-thiazo- None cubic C
line-2-thione None octahedral C
3B Dithiourazolemethyl vinyl ketone mono- None cubic C
adduct None octahedral C
3S 39 1,3,4-Thiadiazoli- None cubic C
dine-2,5-dithione None octahedral C

~X8~L~Z4 T A B L E iI (Continued) {hh~ Host Growth ModifierSurfaces Grains Method 40 4-Carboxymethyl-4-thiazoline-2- None cubic C
thione None octahedral C
41 1-Phenyl-5-selenol-tetrazole, octahedral potassium salt None (1)(~) A
10 42 1-Carboxymethyl-5H-4-thiocyclopenta- None octahedral C
(d)uracil None cubic C
43 5-Bromo-4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene ~331} cubic A
44 2-Carboxymethylthio-4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene None cubic C
1-(3-Acetamidophen yl)-5-mercapto-tetrazole, sodium salt None oct~hedral C
46 5-CarbDxy-6-hydroxy-4-methyl-2-methyl-thio-1,3,3a,7-tetr~azaindene {331~ octahedral C
47 5-Carboxy-4-hydroxy-6-methyl-2-methyl-thlo-1,3,3a,7-tetraazaindene None cubic A
48 -Thiocaprolactam None cubic (1) A
49 4--Hydroxy-2-methyl--thio-1,3,3a,7-tetraazaindene {331} cubic A

~L2~ Z4 T A B L E II (Continued) {hhQ} Host Growth ModifierSurfsces Grains Method 50 4-Hydroxy-2,6-di-methyl-1,3,3a,7-octahedral tetraazaindene None (4) A
51 Pyridine-2-thiol None octahedral (8) A
52 4-Hydroxy-6-methyl-1,2,3a,7-tetraaza- Noneoctahedrsl indene (4) A
53 7-Ethoxycarbonyl-6-methyl-2-methyl-thio-4-oxo-1,3,3a,7-tetra-azaindene None cubic C
54 l-(4-Nitrophenyl)-5- octahedral mercaptotetrazole None(1)~2) A
55 4-Hydroxy-1,3,3a,7- None octahedral tetraazaindene (4) A
56 2-Methyl-5-nitro-1-H-benzimidazole None octahedral A
57 Benzenethiol None octahedral (1)(8) A
25 58 Melamine None cubic C
None octahedrfll C
59 l-(3-Nitrophenyl)-5- Yes cubic C
mercaptotetrazole None octahedral C
60 Pyridine-4-thiol None octahedral (1) A
61 4-Hydroxy-6-methyl-3-methyl-thlo-1,2,3a,7-tetraaza-indene None cubic A
62 4-Methoxy-6-methyl-1,3,3a,7-tetraaza-indene None octahedral A

T A B L E II (Continued) {hhQ} Host Growth ModifierSurfaces Grains Method 63 4-Amino-6-methyl-1,3,3a,7-tetraaza-indene {331~ octahedral A
64 4-Methoxy-6-methyl-2-methylthio-1,3,3a,7-tetraazs-indene None cubic A
6S 4-Hydroxy-6-methyl-1,2,3,3a,7-penta-azaindene None octahedral A
66 3--Carboxymethylrho-danine None cubic (1) A
67 lH-Benzimidazole None octahedr~l A
68 4-Nitro-lH-benzimid-azole None octahedral A
69 3-Ethyl-5-[(3-ethyl-2-benzoxazolinyl-idene)ethylidene]-4-phenyl-2-thioxo-3-thiazolinium None cubic C
iodide None octahedral C
i it \-=CH-CH= / ~ I~
~-/ \N/ \S/ ~S
Et ~ 8~2~ ~

T A B L E_ II (Continued) {hhQ3 Host Growth Modifier Surfaces Grains Method 70 3-Ethyl-5-(4-methyl-2-thioxo-3-thiazo-lin-5-ylidenemeth- None cubic C
yl)rhodanine None oct~hedrsl C
0 Me Et- ~\ S/ C \S- ~

71 3-Isopropyl-[~3-eth-yl-2-benzothiazo-lidinylidene)-ethylidene]rho-dsnine None cubic B
o 20 ~ =CH-CH=~ C~
Et 72 3,3'-Diethylthia-cyanine ~-toluene-~ulfonate None cubic (5) A

~-\ /s\ /s\ /-~
I ll ~ -CH=-\ i! ~! H

Et Et pt~

T A B L E II (Continued) {hhQ} Host Growth Modi~ier Surfaces Grains Method 73 3-Ethyl-5-~3-ethyl-52-benzothiazolin-ylidene)rhodanine None cubic (5) A
o i ll \.=./ ~-Et ~-/ \N/ \S/ ~S
Et 74 3-Ethyl-5-(3-ethyl-2-benzothiszolin-ylidene)-2-2,4-thio-oxazolldine--dione None cubic (5) A
-, /s l!
I 1, \.=./ \~-Et ~./ \ ~ ~ ~S
Et 5-(3-Ethyl-2-benzo-thiazolinylidene)-1,3-diphenyl-2- None cubic C
thiohydsntoin None octahedrsl C

I~ \li/\ ~ '=

Et 'Z24 T A B L E II (Continued) {hhQ} Host Gr_wth ModifierSurfaces Gr~ins Method 76 3-Ethyl-5-(3-ethyl-2-benzoxazolinyl-idene)rhod~nine None cubic (5) A
O
\ /o l!
il \.=./ '~--Et ~-/ \N/ \S/ ~S
Et 77 3-Methyl-4-[(1,3,3-trimethyl-l(H)-2-indolylidene)eth--ylidene]-l-phenyl- None cubic C
2-pyr~zolin-5-one None oct~hedr~l C
~ ~ e O

20 1 li ~ =CH-CH=-/ ;

Me Me 78 5-(1,3-Dithiol~n-2-25 ylidene)-3-ethyl-rhod~nine ~one cubic (5) A
o HH2-T \-=-/ ~ Et ~ 8 T ~ B L E II (Continued) {hhQ} Host Growth ModifierSurfaces Grains Method 79 5-(5-Methyl-3-pro-pyl-2--thiazolinyl-idene)-3-propyl-rhodanine None cubic (5) A
o li \ = / ~ 2 CH2 Me \N/ S/ ~S

Me 3-Carboxymethyl-5-([3-ethyl-2-benz-ox~zolinylldene)-ethylidene]rhoda- None cubic C
nine None octahedral C
o t 1l \-=CH-CH=- / ~- CH2-C02H
~-/ \N/ \S/ ;~S

Et 81 5-(3-EIhyl-2-benzo-thiazolinylidene)-3-B-sulfoethylrho-danine None cubic (5) A
o s l!
il ~ CH2--CH2--S03H
~-/ \N/ ~S~ ~S
Et ~ 4 T A B L E II (Continued) {hhQ} Host Growth Modifier SurE~ce Grsin~ Method 82 5-Anilinomethylene-3-(2- 5ul foethyl)-rhodanine None cubic (6) A
1!

HSO3-CH2-CH2 ~ \-=GH-S~ \S/
83 3-(1-~Carbo-yethyl)-5-[(3-ethyl-2-ben-zoxazolinylidene)-ethylidene]rhoda-nine None cubic B
o If \li/ \-=CH-CH= \ ~ CO2H

It 84 3-(1-C~rboxyethyl)-5-[(3-ethyl-2-ben-zothiazolinyli-dene)ethylidene]-rhodanine None cubic B
o Il CH-Me ll \ =CH-CH=-/ ~ CO2H
30 ~ / \ ~ \ S~ ~S
I

Et -4~-T A B L E II (Continued) {hhQ} Host Growth Modifier Surfaces Grains Method 85 3-(3-Carboxypropyl)-55-[(3-ethyl-2-ben-zoxazolinylidene)-ethylidene]rhoda-nine None cubic B
o / \N/ \5/ ~S
Et 86 3-(2-Carboxyethyl)-5-[(3-ethyl-2-ben-zothiazolinyli-dene)ethylidene]- None cubic C
rhodanine None octahedral C

il =CH-CH= / ~-CH2-CHzCO2H
~-/ \N/ \ S/ ~S
Et 87 3-Carboxymethyl-5-[(3-methyl-2-thia-zolidinylidene)-isopropylidene]-rhodanine None cubic B
o ,s\ I!

~ Me S S
Me .~8~ZZ4 _ A B L E II (Continued) {hhQ} Host Growth Modi~ierSurfaces Grain~ Method 88 3-Carboxymethyl-5-[(3-methyl-2-thia-zolidinylidene)-ethylidene]rhods-nine None cubic B

It H22_¦\ ~ =CH-CH= /\ ~-CH2c2H

Me 89 3-Carboxymethyl-5-{[3-(2-carboxy-ethyl)-2-thiAzoli-dinylidene]ethyl-idene}-rhodanine None cubic B
O

H2_1\ ~ =CH-cH=./ ~- CH2C2H

(CH2)2c2H
90 3-(a-Carboxybenz-yl)-5-[(3-ethyl-2-benzoxazolinyli-dene)ethylidene]-rhoctAnine None cubic B
O ~p T i1 ~ =CH-CH=.~ ~-CHC02H
~-/ \N/ \S/ ~S

Et ~ 4 T A B L E II (Continued) {hhQ} Host Growth ModifierSurfaces Grains Method 91 3-~a-Carboxybenz-yl)-5-[(3-methyl-2-thiszolidinyli-dene)ethylidene]-rhodanine None cubic B
'1>
H2_i ~ =CH-C=- \ ~ -CHC02H

Me 92 1-Ethyl-4-(1-ethyl-4-pyridinylidene)-3-phenyl-2-thiohy- None cubic C
dantoin None oct~hedral C
o Et- ~ Et I

93 Anhydro-3-ethyl-9-methyl--3'-(3-~ul-fobutyl)thiAcarbo-- None cubic C
cyanine hydroxide None octahedral C

30 ~ \ -CH=C-CH=-/ \il/ ~1 Et ClH22 C~-S03 Me ~Z 8 T A B E E II (Continued) {hhQ~ Host Growth Modifier Surfaces Grains Method 94 3-Ethyl-5-[1-(4-sul-5f obutyl)-4-pyri-dinylidene~rhoda~
nine, piperidine None cubic C
~alt None octahedral C
o ~O3s-(cH2)4- ~ \.=,/ \~-Et I~,i n n 95 5-(3-Ethyl-2-benzo-thiazolinylidene)-l-methoxycarbonyl-methyl-3-phenyl- None cubic C
2-thiohydantoin Yes octahedral C
o t~ \tl/ \-=-/
~-/-\~ \N/-~S

Et CH2 C=O

~2~3i'22 T A S L E ll (Continued) {hhQ} Host Growth Modif~erSurfaces Grains Method 96 1,1',3,3'-Tetraeth-ylimidazo(4,5-b)-quinoxalinocarbo-cyanine ~-toluene-sulfonate None cubic (l) B
Et Et 10 . ~ N\ /-~
t 1l i =CH-CH=CH-- I ll e Et pts Et 15 97 3-(2-Carboxyethyl)-5-(1-ethyl-4-pyri-dinylidene)rhoda-nine None cubic (1)(2) A
o .=. /!
~ CH -CH CO H

98 3-Carhoxymethyl-5-{[3-(3-sulfopro-pyl)-2-thiazoli-dinylidene]ethyli-dene~rhodanine, sodium salt None cubic (1) A
o H22-i\ ~ =CH-CH=. \ y -CH2-C02H
+
(CH2)3so3 N~

3L213~2Z4 T A R L E II (Continued) ~hhQ} Host Growth ModifierSurfaces Grains Method 99 3-(l-Carboxyethyl)-5-{[3-(3-sulfo~
propyl)-2-thiazol-idinylidene]ethyl-idene}rhodanine, sodium salt None cubic (l) B

H2_l~ ~ .=CH-CH=. \ ~- CH-C02H

(CH2)3S03 Na 100 3-(3-Carboxypropyl)-5-{[3-(3-~ulfo-propyl)-2-thiazol-idinylidene]eth-ylidene}rhoda-nine, sodium salt None cubic (7) A
o H2~ =CH-cH=.\ ~ tCH2)3C02H

( 2)3S03 Na ~ ~ 8~ 4 T A B L E II ~Continued) [hhQ} Host Growth Modifier urfsces Grains Method 101 3-(2-Carboxyethyl)-S 5-1[3-(3-sulfo-propyl)-2-thiazo-lidinylidene]eth-ylidene}rhoda- None cubic C
nine, sodium salt None octahedral C

H22-l\ ~ =CH-cH=. \ ~- CH2-CH2C02H

(CH2)3S03 Na 102 3-Carboxymethyl-5-(2-pyrrolino-1-cyclopenten-l-yl-methylene)rhoda-nine, sodium salt None octahedral A
\.
~3 \N/
02C-CH2 ll \ ~ \ =CH-~ \
+ S~ "S / 1 / -103 3-Ethyl-5-(3-methyl-2-thiazolidinyli-dene~rhodanine None cubic (5) A
O

~2_1 \.=./ ~- Et Me ~ 4 T A B L E II (Continued) {hhQ} Host Growth ModifierSurfaces Grain~ Method 104 5-(4-Sulfophenyl-azo)-2-thiob~r-bituric acid, None cubic C
sodium salt None octahedral C
o 3 \ _ / i y + 0~ S
N~ H
105 3-Carboxymethyl-5-(2.6-dimethyl-4(H)-pyr~n-4-yli-dene)rhodanine None cubic (5) A
o M~ 11 .
~-=- \S/ ~S

106 Anhydro-1,3'-bis(3-sulfopropyl)naph-tho[l,2-d]-thiazo-lothiacyanine hy-droxide, triethyl-amine salt None cubic (5) A

~-\ /s\ /s\ /-~
!~ ,i!,~, ~ ~ U !, (C~2)3 (CH2)3 S03e S03e HNEt3 ~ 4 T A B L E II (Continued) {hhQ} Host Growth ModifierSurfaces Grains Method 107 3-Ethyl-5-[3-(3-sul--fopropyl)-2-benzo-thiazolinylidene]-rhodanine, tri-ethylamine salt None cubic (5~ A
o i~ \~l/ \.=./ \~- Et N/ \S/ ~S

(CH2)3 S0~ HNEt4+
108 3-Ethyl-5-[3-(3-sul-fopropyl)-2-benz-oxazolinylidene]-rhodanine, potas- None cubic C
sium salt None octahedral C
o o l!
j~ \~l/ ~.=. / \~ -Et ~-/ \N~/ \S/ ~S
251 e (CH2)3s3 K
(1) 3 mmoles of growth modifier/Ag mole of host grain emulsion was employed (2) a pBr of 1.6 was employed 30(3) 9 mmoles of growth modifier/Ag mole of host grain emulsion was employed, added in two portions (4) 50DC was employed instead of 60~C
~5) 2 mmoles of growth modifier/Ag mole 35of host grain emulsion was employed (6) 1.5 mmoles of growth modifier/Ag mole of host grain emulsion was employed 1281~ V~4 -5~-(7) 4 mmoles of growth modifier/Ag mole of host grain emul~ion W~5 employed (8) a pBr of 2.3 w~s employed Comp~rstive Exsmple 8 The purpose of this comparative exsmple is to report the re~ult of sdding 6-nitrobenzimidazole to a resctIon ve3~el prior to the precipitstion of ~ilver bromLde, ss suggested by Wulff et al V.S.
Pstent 1,696,830.
A resctLon vessel equipped with a stirrer W8S charged with 0.75 p~ of deionized bone gelatln msde up to 50 g with wster. 6-Nitrobenzimidazole, 16.2 mg (0.3 weieht % bssed on the Ag u3ed~, dls~olved In lml. of methsnol, wss added, followed by O.OSS mole ot~ KBr. At 70C 0.05 mole of a 2M
solutLon of AeN03 ws~ sdded ~t a uniform rste over a perlod of 25 min. The grsins formed were relative-ly thick tsblets showing {111} crystsl faces.
There W8S no indlcstion of the novel trisoctshedrsl crystsl tsce~ of the invention.
Comparative ExsmPle 9 The purpose of this comparative example is to report the result of employing 4-hydroxy-6-methyl-1,3,3a,7-tetrsszsindene, sodium salt during erain preclpttstion, ss su~ested by Smith Psrticle Growth snd usPenSion, cited sbove.
To lOO mL of A 3% bone gelstin solution were sdded simultsneously lO mL of 1.96 M A~N03 snd lOmL
of 1.96 M KBr st 50C wlth stirrlng over a period of About 20 9ec. The Ap,Br dispersion was sged for 1 min st 50~C, then dlluted to 500 mL. The dispersion wss adjusted to pBr 3 with KBr.
SsmPles 9a, 9b.
"
To ~OmL of lX10 M KBr containing 0.4 mmole/Q of 4-hydroxy-6-methyl-1,3,3a,7-tetraaza-indene, sodLum s~lt snd 0.6 mmole/Q of l-dodecyl-quinolinium bromide wa~ sdded 20 mL of the sbove -5g-dLspersion, which was then ~tirred ~t 23C. Samples were removed after 15 min (Sample 9ff) and 60 min (Sample 9b).
Samples 9c, 9d Ssmples 9c and 9d were prepsred similarly as Samples 9a and 9b, respectively, except that 0.8 mmole/Q of 4-hydroxy-6-methyl-1,3,3a,7-tetraaza-lndene snd 0.6 mmole/Q of l-dodecylquinollnium bromide were u~ed.
Exam~nQtion of the ~rains of esch of the samples reve~led rounded cubic grains. No trisocts-hedral crystQl faces were observed.
ExamPle 10 Emulslon Example 10 illustrstes the prepsrQtLon of a octahedrsl sLlver bromide emulsion havlng trLsoctQhedrel protrusions on the initially octahedral p,ralns u~lng Compound 10, 4-hydroxy-6-methyl-1,3,3a,7-tetraazalndene, sodium salt, a Xnown ~ntlfog~ant and stsbillzer, as growth modifier. A~
t}le precipitation continued, the formation of trlsoctahedra bec&me evldent.
To a rQsctLon vessel ~upplied with a stirrer was added 0.05 mole of an octahedral regul~r grain sllver bromide emul~Lon of mean grain size 1.35 ~m contsinin~ 40 g/Ae mole gelatln. Water was added to make the total welght 50 g. To the emulsion at 40C
was Qdded 6.D ml111mole/lnitial Ag mole of Compound 10 dissolved ln 3mT~ of water. The emulsion wss then held for 15 mln at 40C. The pH was ad~usted to 6.0 at 40C. The temperature wQs rQised to 60C snd the pAg adJusted to 8.5 at 60C with KBr and maintained at thQt vslue durlng the precipitation. A 2.5M
solutJon ot` AgNO3 was lntroduced at a constant rste. For Example lOA the precipit~tion time was 15 min, uslng 0.00~5 mole Ag. For Example lOB the precipltatLon time was 30 mLn, using 0.015 mole Ag.

F:Lgures l7A snd l7B ~re electron micrographs showing the resulting emul~lGn erain~ of Exsmple lOA
snd lOB, respectively. In Exsmple lOA uniform ruffles formed over the octshedral fsces, while new trLsoctahedral fsces formed along the edges between the or1R1nal f~ces. ln Example lOB the process of formlne {331} tri.soctahedra ls ~lmost complete.
ExamPle ll Emulsion Example ll illustrateq the formation of tri~octRhedrsl rid~es on octshedral si1ver bromide host grain~.
The host emulsion and procedure was the ~Rme as in Ex~mple lO. The growth modifier was 2.0 m11.1.imole/initlsl. Ae mole of Compound 98, 3-csrboxy-lS methyl-5-{[3-(3-sul.fopropyl)-2-thiszolidinylidene]-ethylidene}rhodsnlne, sodlum sal.t, a known green ~pectral ~ens:lt1zlng dye, dts~olved in 3mL methanol, 2mL wster and 3 drop~ of trlethylamine. The precLpLtation solutions were 2.OM rather than 2.5M
AgN03 snd ICBr.
For Example llA the preclpitation time was 200 min, u31ne 0.04 mole Ag. For Ex~mple llB the tl.me was 350 mi.n, using 0.07 mole Ag.
FLF,ures l~A and ].8~ are electron micrographs of the result.tn~ emul~ion ~rain~ produced by Examples J.lA and llB, respect.lvely. The fsces are uniformly covered with rld~es running in 8 direction perpen-dicul.ar to the (l.lO) Ag rows of the lsttice.
Trtsoctahedral. faces h~ve begun to form. In Example l1~ t~le ridges remai.n evident, while the macro habit hss become {33l~ trisoctahedral.
ExRmple 12 The emulsLons of Ex8mple 12 descr~be the effect of preclpitation p~ on the preparation of {331~ trisoctahedral silver bromide emulsion using 85 growth modl.fier Compound I.

~ 8 ~X2 Emulsion 12A
To a reaction vessel supplied with 9 stirrer was added O.OS mole o~ an octahedral silver bromide emulslon of mean grain s~ze 0.8 ~m, containing about 10 g/Ae mole of gelatin. An sdditional 0.5 g of deLonlzed bone gelat~n was ~dded, and water to make the total welght 50 g. To the emulsion at 40C
was added 6.Q mlllimole~lnltlal Ag mole of Compound I
dlssolved ln 3mL of water. The emulsion was then held for 15 min at 40C. The pH was ad~usted to 7.0 at 40C. The temperature was raised to 60C, and the pH W8S noted to be 6.84, at which value it wa~
mQlntalned durin~ the precipitation. The pAg was adjusted to 8.5 at 60C with KBr and maintained at that value during the precipitation. A 2.5 M
solutlon of AgN03 was lntroduced at a con~tflnt rate over a perlod of S0 mln while a 2.5 M solution of KBr was added as needed to hold the pAg constant. A
total of 0.025 mole Ag was added.
Emulsions 12B, 12C, and 12D
These emulslons were prepared as described t`or EmulsLon 12A, except ~or different values of pH
lnltlally adjusted at 40C and maintained during the preclpitation as l$sted in Table III.
Flgures 19A, 19B, l9C, and l9D are carbon repl~ca electron microp,raphs of the resulting Emulsions 12A, 12B, 12C, and 12D, respectively. As shown by the data ln Table III, the pH range of from 5.0 to 6.0 produced the best {331~ trisoctahe-~ra. ~t pH 7.0 the trlsoctahedra were not as well formed. At pH 4.0 octahedrs were formed.

~X81Z;~4 TABLE III
Effect of` pH on Trisoctahedr~ Formation PrecIpita-Emul.sion F:Lguretion pH Fin~l No. No. (40C~ MorPholo~y 12A 19A ~.0 Fair Trisoctshedra l~.B 19B 6.0 Trisoctahedra 12C 19C 5.0 Trisoctahedrs 12D 19D 4.0 Octahedr~
Example 13 - Exsmple 13 illustrates the effect of precipitation tempersture on the prepsrstion of [3311 trisoctahedral sllver bromide emulsions usinR the ssme growt,h modifler as in Example 12.
Emu1sions 13~, 13B, and 13C
~ mulsions 13A ~nd 13B were prepared ~s descrlbed for Example Emulsion 12B above, i.e, pH of 6.0 st 40UC, pAg 8,5 at precipitation temperature, but in thls csse with variation of preclpitation temperature as liAted ln Table IV. Figures l9B, 20A, and 20B are electron mlcrographs of the Emulsions l~B, 13A, and 13B, respectlvely. As shown in the data of Table IV, trisoctshedra were formed at 60C
and ~0C, but octahedra were formed st 85C.
TABLE IV
Effect of Temperature on Trisoctahedrs Formation Precipita-Emulslon Figuretion pH Fln~l No. No, ~40C) MorPholo~Y
12B 19B 60C Trisoctahedra 13A 20A '/0C Tri~octshedra 13B 20B 85C Octahedrs Example 14 Exampl.e 14 illustrates the effect of preclpLtQtion pA~ on the preparation of {331}
trlsoctahedrsl silver bromide emulsions using the ssme growth modifler as in Examples 12 and 13.
Emulsion 14 Emulsion 14 was prepared a~ described for Example J.2B above, i.e. 8t a 40C pH of 6.0 and a preclp.LtatLon temperature of 60C, but with variation of the preclpi.tation pAg as listed in Tsble V.
Figures l9B and 21 are electron microgrsphs of Emulslons 19B and 14, respectively. As shown in the d~ta of Tsbl.e V, trisoctahedra were formed ~t pAg 8.5, but poorly formed trisoctahedra resulted at pAg 8Ø
TABLE V
Effect of PAR on Trisoctshedrs Formation Prec~pita-15 Emul.sion Flp,ure tion pH Fin~l No. No. (40C)MorPhologY

12B 19B 8.5Trisoctahedra - 14 21 8.0Poorly Formed Trisoctahedrs ExamPleA15 Example 15 i.llu.Qtrates the effect of level f growth modlfler on the preparation of 13313 trisoctahedral sl.l.ver broml.de emulslons using Compound I as a ~rowth modtfler, as in Ex~mples 12 through 14, but :Ln thls case introduced in the free ac.Ld form, 4-hydroxy-6-methyl-1,3,3a,7-tetraaza-indene, rather th~n as the sodium salt.
Emulslon 15A
. . . _ . . . _ _ To a reaction vessel. equipped with a stirrer was added 0.05 mole of the same octahedrel silver bromide emulsion as used in Example 12A above, made up to 50 g with water. The free acid form of Compound I, 0.52 mil.llmole/initial Ag mole, dissolved in 0.75mL water, was added. The pH W8S ad~usted to 7.0 at 40C and the pAg to 8.0 st 40C. These values were held constant during the precipitetion. At ~81'~Z~

40~C, a 2.0 M solution of AgNO3 was added at a constsnt rate over A period of 80 min, while a 2.0 M
solution of KBr W8S added 8S needed to hold the pAg constsnt. A total of 0.016 mole Ag wss ~dded.
Emulsion 15B
Emulsion 15~ W8S prepared 8S described for Emulsion l5A, except thst the amount of growth modifler w~s lncressed to 0.70 mil.li.mole/initial Ag mole.
F:lgures 22A and 22B are electron micrographs of Emulsions 15A and lSB, respectively. As tabulated In Tab].e VI, ~ncomplete trisoct~hedrs resulted at the 0.52 mlllimol.e level of growth modifier under these precipltstion conditlons, while complete trisoctahe-dra resulted when the level was rsised to 0.70 millimole.
TABLE Vl Effect of Growth Modifier Level on Trisoctahedrs Formation Growth Emulsion FleureModlfier Final No. No. mmole/Ag mole MorPhology l5A 22A 0.52 Incomplete Trisoctahedra l5B 22~ 0./0 Complete Trisoctshedrs C mParative ExamPle 16 Slnce trlsoct~hedrs most closely resemble rhombic dodec~hedra ln oversll appearance, this comparative example is included to provide an el.ectron micrograph of rhombic dodecshedral grains.
~y comparing electron microgrsphs of previous exRmpl.es o~ trisoctshedrs it i3 appsrent thst the grsins identlfied as trisoctahedrR ~re indeed of that cryst~llogrsphic form.
To R reaction vessel supplied with e stirrer was added 0.05 mol.e of a cubic silver bromide ~281224 -~ 5 emul4Lon of mean grain ~ize 0.8~m, containlng sbout 10 g/Ag mole of g21atin. Water W8S &dded to make the total welght 50 g. A solution was prepared of 20 milllmoles of Compound 47, 5-csrboxy-4-hydroxy-6-methyl-2-methylthio-1,3,3R,7-tetrasz3indene, in a solvent containing 10 drop~ of triethylsmine, 0.5 mL
ot` N,N-di-methylformamide, and water to make 8 total vol.ume o~ 10 mL. Of the ~olution, 3 mL. (6.0 mlllimole~ Compound 47/lnitial Ag mole of emulsion) was sdded to the emul~ton st 40~C and the pH w~s ad~usted to 6Ø The tempersture was rsised to 60C, and the pAg ad~usted to 8.5 at 60C with KBr and malntained at that vslue durlng the precipitation. A
2.5M solutlon of AgN03 W85 i.ntroduced st 8 constant rate over a perlod of 150 min. while a 2.5M ~olution o~ KBr wa3 sdded as needed to hold the pAg constant.
A total. of 0.075 mole Ag was added.
A carbon replics electron micrograph of the re~ultlng rhomblc dodecahedral emul~ion grains i9 ~0 shown in Figure 23.
ExamPle 17 Thls example lllustrates that a trl~octa-hedrsl emul.sion exhLbltn sn increase in photogrsphic speed at ~ p,iven fog level a~ compared to an octahedrsl emulsi.on of the same halide composition and 8rain volume.
Ex~mPle Trl.-40ctahedral Emulsion (A) To a react:l.on ves~eJ. ~upplied with a stirrer was added 0.5 moles of an 0.7~m AgBr octahedral emulnlon conta~nlng e20g of bone gelstin and dl.stilled wflter. The contents of the kettle weighed 500~. The emulsion WRS heated to 40C, and 1.5 mmol.e/Ag mole of 4-hydroxy-6-methyl-1,3,3s,7-tetr~-azaindene sod.Lum sRlt dlssolved ln 45ml of distilled wster, wa~ added. The pH was ad~usted to 7.0 at 40C
wl.th ~od~um hydroxide solution and the pAg was ad~usted to 8.0 at 40~C wi.th NaBr ~olution. At 40C

~X~ 24 a 2.OM sol.ution of AeN03 w~s introduced ~t a conqtant rate over ~ period of 100 min, while a 2.0M
solutlon of Na8r was &dded aS needed to hold the PA8 constant. The pli was slso held cons~ant by adding S NaOH or HN03 solutions ss needed. A total of 0.2 moles Ag was edded. Csrbon replics electron micrographs showed thst the emulsion consisted of mostly tr:Lsoctahedral crystals.
Control. Emulsion (B~
This control emulsion was precipitated ldenti.call.y to the above trisoctahedral grain emulsLon, except the 4-hydroxy-6-methyl-1,3,3a,7-tetras7slndene w~s added a~ter the precipitation was complete. The resultlne F,rsins were octahedral in shape.
Sensitizstion Emulsions A ~nd B were chemicslly sensitized ss l.isted below, snd then coated on acet~te support st 1.08g Ag/m , 4.31g bone ~elstin/m , 0.81g of a dispers.ion of the coupler 2-benzsmido-5-[2-4-but~ne--sulfonylami.dophenoxy)tetrsdecsnsmido-4-chloro-phenol/m , 0.14~ .4aponin/m as spreading agent, and 18mg bi.s(vinyl.sulfonyl-methyl) ether/g gelatin ss hardener.
Coatlnp, _ Emu].slon 1 B hested 15 min st 70C with 2.4mg/Ag mole sodlum thiosul.fste & 0.8mg/Ag mole potassium chloroaurste 2 B hested 15 min st 70C wi.th 3.6mg/Ag mole sodl.um thlosult`ste & 1.2mg/Ag mole potassium chlorosurste B heated 15 mln st 70C with 4.8mg/Ag mole sodium thiosul.fate & 1.6mg/Ag mole pot~ssium chlorosurste 4 A he~ted 15 mLn at 70C with 2.4mg/Ag mole sodlum thlosulfate & 0.8mg/Ag mole potassium chloroaurste lZ8~ 4 A heated 15 min at 70C with 3.6mg/Ag mole sodium thiosulfate & 1.2mg/Ag mole potassium chloroaurate 6 A heated 15 min at 70C with 4.8mg/Ag mole sodium thiosulfate & 1.6mg/Ag mole potassium chloroaurate These coatings were exposed for 0.1 s to a 2850K tungsten light source through a variable density tablet. These coatings were then processed for 2 min, 3 min, 4 min, 5 min, or 6 min in Kodak C-41TM Color Negative developer at 38C. The results are summarized below in Table VII.
Table VII
Development Relative Coating__ Timç (min.~ Fog Speed 1 ~Control) 2 0.12 100 3 0.17 132 4 0.23 148 0.34 182 6 0.38 195 2 (Control~ 2 0.18 155 3 O.Z8 191 4 0.37 219 0.58 251 6 0.70 288 3 (Control) 2 0.25 182 3 0.37 219 4 0.55 234 0.89 282 6 0.99 288 4 (Example) 2 0.15 138 3 0.17 178 4 0.24 204 0.41 229 6 0.48 234 -6~-Tabl.e VII Continued Deve~.opment Re1stive co~tinF~- Time (mi.n.~ Fog Speed 2 (Examp1e) 2 0.21 251 3 0.44 309 4 0.66 331 1.12 331 6 1.33 372 3 (Control) 2 0.25 263 3 0.37 275 4 0.55 30g 0.89 295 6 0.99 288 From Table VII lt is app~rent that the example emulslon satlsfyi.n~ the requirement~ of this lnve,ntlon exhi.bi.ts higher photographic speed~ than the contro1 octahedral emulsion. Further, this increaqed speed ls real.ized even when the chemical sensit:l7.ers are doubled in concentr~tion in the control. emu~slon. Whether compsred at the same devel.opment times or st the sAme fog 1eve1s, the example emu~.sion of the lnvention is in all instances superi.or in photogrAphic performsnce.
The lnventlon ha~ been described in det~il wlth particul.sr reference to preferred embodiments thereof, but lt wlll be understood that variations and modlflcatlons can be effected within the spirit and 4cope of the invention.

Claims (11)

1. A silver halide photographic emulsion comprised of radiation sensitive silver halide grains of a cubic crystal lattice structure comprised of trisoctahedral crystal faces.

2. A silver halide photographic emulsion according to claim 1 wherein said silver halide grains comprised of trisoctahedral crystal faces are silver bromide grains.

3. A silver halide photographic emulsion according to claim 1 wherein said silver halide grains comprised of trisoctahedral crystal faces are silver chloride grains.

4. A silver halide photographic emulsion according, to claim 1 wherein said silver halide grains comprised of trisoctahedral crystal faces contain at least one of bromide and chloride ions and optionally contain a minor proportion of iodide ions based on total silver.

5. A silver halide photographic emulsion according to claim 1 wherein said silver halide grains are additionally comprised of at least one of cubic and octahedral crystal faces.

6. A silver halide photographic emulsion according claim 1 wherein said silver halide grains are regular trisoctahedral grains.

7. A silver halide photographic emulsion according to claim 1 wherein a grain growth modifier is adsorbed to said trisoctahedral crystal faces.

8. A silver halide photographic emulsion according to claim 1 wherein said trisoctahedral crystal faces satisfy the Miller index assignment {hh?}, wherein h and ? are integers greater than 0 and h is greater than ?, but no greater than 5.

9. A silver halide photographic emulsion according to claim 8 wherein said trisoctahedral crystal faces exhibit 8 {331} or {441} Miller index.

10. A silver halide photographic emulsion according to claim 9 wherein a grain growth modifier is present in said emulsion chosen from the class consisting of 4-hydroxy-6-methyl-1,3,3a,7-tetraaza-lndene, 5-bromo-4-hydroxy-6-methyl-1,3,3a,7-tetra-azaindene, 4-amino-6-methyl-1,3,3a,7-tetraazaindene, 2-imidazolidinethione, ethylenethiourea, 5-carboxy-6-hydroxy-4-methyl-2-methylthio-1,3,3a,7-tetraazain-dene, 4-hydroxy-2-methylthio-1,3,3a,7-tetraazaindene, and 5-(3-ethyl-2-benzothiazolinylidene)-1-methoxy-carbonylmethyl-3-phenyl-2-thiohydantoin.

11. A photographic element containing an emulsion according to claim 1.