JPH01167204A - Method for preparing metal halide product - Google Patents

Abstract

PURPOSE: To easily obtain a metal halide product useful for formation of metal halide glass, etc., by introducing specific vapor flow into a reaction zone and supplying energy, such as thermal heating or low pressure plasma discharge, thereto.

CONSTITUTION: A metal halide forming precursor substance, such as Al(hfa)₃ of the complex of hexfluoroacetyl acetone (Hhfa) which is beta diketone, is put into an evaporation chamber 40 and is heated to about 80°C. Next, Ar 8 is sent at a velocity of flow of about 400 cc/min via a feed pipe 10 to a reaction tube 15. A furnace 31 is heated to about 500°C and the feed pipe 14 to about 120°C. The flow of the Ar 8 is changed over from the pipe 10 to the pipe 11 and the Al(hfa)₃ vapor of the chamber 40 is picked up and is introduced through the pipe 14 and the reaction tube 15 into the zone 30. The Al(hfa)₃ is then pyrolyzed for about 1 to 2 hours in the zone 30 to deposit and form gray black powder on the wall of the reaction tube 15. This deposit is subjected to a recovery treatment, by which the metal halide product, such as AlF₃ is formed.

COPYRIGHT: (C)1989,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing pure metal halides useful for making metal halide glasses. More particularly, the present invention relates to methods of making metal halide precursors by vapor phase deposition and the use of the precursors to make glass articles such as glass and optical waveguide preforms.

Metal halide compositions are of current interest in developing new transparent glassy materials with unique optical properties. For example, in the field of glass optical waveguides, which are transparent glass filaments used to transmit optical signals for communication purposes, there is a constant need for glasses with improved transparency.

Commercially available glass optical fibers are currently made of oxide glass materials such as fused silica and doped fused silica glass. Such materials are constantly being improved and now have a theoretical minimum of 0.1 d at 1.6 microns.
Loss coefficients close to B/km have been achieved. However, in halide glass systems that can operate at wavelengths in the infrared region, the attenuation is likely < 0.001
It is believed that it can be reduced to about dB/kin. Halide glasses considered for producing optical waveguide fibers with very low losses include, for example, glasses based on BeFz, ZrFa and Z n CI-2.

Patents disclosing the use of metal halide glasses for infrared transmitting optical devices include, for example, US Pat.

However, these patents relate to making preforms or filaments by conventional batch melting and forming methods.

A vapor deposition method for making pure metal halides for metal halide glass optical devices is disclosed in U.S. Pat. No. 43,789.
No. 87 and Japanese Patent Publication No. 57-51146. These methods offer the possibility of providing the necessary purity for very low attenuation optical devices.

In the method of U.S. Pat. No. 4,378,987, a particulate metal halide precursor, such as a metal fluoride powder, converts a vapor metal source such as an organometallic compound (e.g., a metal alkyl or metal beta-diketonate) into a vapor such as HF. Generated by reaction with a halogen source. These reactive vapors are flowed into a reaction zone adjacent to the substrate where they react to form the precursor, which is then deposited onto the substrate to form a transparent preform or fiber. , fusion densification (c
further processed by solidification).

Although this method avoids impurities from the crucible entering the glass, it is difficult to treat halogenating agents such as HF and HCl. In particular, HF is corrosive and difficult to meter accurately, making waste disposal difficult if it is present in excess in the reaction mixture. Additionally, since the starting materials used in this method are reactive,
Separate feed lines are required for each reactant.

It is therefore an object of the present invention to provide a simplified method for producing transparent metal fluoride-containing glasses by a vapor phase process, which largely avoids the above-mentioned problems. .

The present invention does not require the use of halogenating agents such as HF, and by allowing the use of a single reagent rather than two for each metal halide precursor or product, Simplify the vapor phase deposition method. This single reagent is the source of both metal and halogen to be incorporated into the reaction product.

The reagent used to provide the halide deposit according to the present invention is a halogenated beta-diketonate of the metal of the desired metal halide. Beta-diketonates are known metal complexes consisting of a metal atom surrounded by ligands that are the anions of beta-diketones. Beta diketone is RCo CHz Co R
' (where R and R' are usually alkyl or substituted alkyl groups of 1-4 carbon atoms). These complexes are generally stable in air under ambient conditions and may exhibit good volatility.

In the present invention, at least one of the R and R' groups of the ligand is a halogenated alkyl group, which provides the halogen required for metal halide formation. An example of such a ligand is beta diketone 1.1.1.5,5.5,-hexafluoro-2,4
-Pentanedione (hexafluoroacetylacetone)
An anion formed by removing a hydrogen atom from the 03 position of a diketone, which has the following structural formula:

O 11]I F:+CCCH2CCF':+ The metal halide precursor is prepared in accordance with the present invention by providing a reactant stream comprising a vapor of a selected metal halide heterdiketone to be incorporated into the metal halide precursor deposit. generated. This complex is decomposed in the reaction zone to form a gas-phase deposited product consisting essentially of the metal halide, which product is collected as particulate material or is deposited as particulate layer or integral film. Deposited directly onto the reforming substrate.

The metal halide is believed to be formed from the beta-diketonate by intramolecular halogen transfer, but it contains at most only traces of carbon or metal oxides. Liquid and/or gaseous by-products of the decomposition reaction are separated from the metal halide product by volatilization and carried away from the reaction zone away from the metal halide product. The resulting halide can be used to form the desired glass.
It is further processed to form a preform or product such as a glass optical waveguide filament.

Embodiments of the present invention will be described below with reference to the drawings.

Although it is believed that the process of the present invention may be useful for providing a variety of metal halide products, the present invention
It is particularly useful when it is desired to avoid treatment with corrosive fluorinating agents such as F.

Accordingly, although the following description is directed primarily to the preparation of metal fluoride precursors, the method of the present invention is also applicable to the preparation of metal chlorides or other halides.

Examples of known metals for forming heteradiketonate complexes with sufficient volatility to be vapor transportable include Li, Na, Be, Mg, Si, Y-CuX.
Hf, Ti, Zr, Zn, Pb, Cd.

Some of A1, Ga, Ce and other rare earth metals. Chlorides or fluorides of these and other metals are most useful in making halide materials for infrared transmission. Although metal halide glasses are relatively stable and most easily formed in eFz-based composition systems, many other glass-forming systems are known and active components of those systems include, for example: ZnC
j! 2, ZnF2, A7! F3, ZrF,, HfH,,
MgF2, PbF2, CdF2, ThF, La,...
These include fluorides of some of the rare earth metals such as Ce, Yb and Lu. Certain glassy metal bromides or iodides are also known.

Fluorinated beta-diketones that can be used to make metal beta-diketonates as described above are known. Examples of some beta diketones that can be used for metal halide production according to the invention are shown in Table 1. Table 1 contains the designation of specific diketones as ligand compounds, the common name or symbol for each compound, and typical complexes in which the ligands are designated with their corresponding symbols. .

Ligand compound 1,1. L5,5.5-hexafluoro-2,4-pentanedione 6.6,7,7,8,8,8. - Heptafluoro-2,2-dimethyl-3,5-octanedione i,i,i-trifluoro-2,4-pentanedione LLL5,5,6,6,7,7,7. -decafluoro-
2,4-Pentanedione Table I Commonly used name (symbol) 11 and 1 Hexafluoroacetyl A j! (hfa
) 3 Acetone (Hhfa) B e
(hfa)zM g (hfa) 2 Z r (hfa)4 T i (hfa)4 Z n (hfa) 2 Cd (hfa)z (Hfod) Ce (fod)4
Hf (fodL trifluoroacetyl Ga (tfa)
:+Acetone (Htfa) Cu (tf
a) z3 c (tfa): + P b (tfa) z (Hdfhd) M g (dfh
d) 2 The above examples are for illustration only; other combinations of the exemplified metals and ligands, as well as combinations of other metals and other ligands, may be used instead. good.

Table 1 reports the formula for the complex without indicating the adduct. That is, these complexes are beta-diketonate adduct complexes, i.e., the metal beta-diketonate is a Lewis base (L) (where L is, for example, an ether, dioxin, tetrahydrofuron, H,01NH3, pyridine, dimethylformamide, etc.). It is further complexed by Many of these adducts are sufficiently volatile for use, and some are sufficiently volatile and stable to be desirable.

Transport of the beta-diketonate reactant into the reaction zone is carried out by an inert carrier gas such as argon, nitrogen, etc. to avoid oxidation or other side reactions that may involve the metal or halogen components of the complex. is preferred. Since it is desirable to carry out the decomposition reaction in a controlled environment, the preferred method is to use a hollow tubular substrate as the deposition substrate for the precursor (II) and to carry out the analytical reaction inside this tubular substrate. In this way, the tubular substrate serves as a substrate for collecting precursors deposited as particulate material or as a smooth film on the inner surface of its walls, and as a substrate for moisture,
It acts as a closed environment from which oxygen and undesirable contaminants can be eliminated.

Controlling the environment of the reaction zone if it is desired to deposit the metal halide precursor on the external surface of the solid preform or to collect the product for later processing outside the reaction zone. A protective enclosure may be provided to do so. This enclosure can function as a controlled pressure chamber if the decomposition reaction is to be carried out under pressure conditions other than atmospheric pressure.

It is of course also possible to use sources of halogen in addition to the beta-diketonate source compounds when providing metal halide deposits according to the invention, which means, for example, that optical or other It may even be desirable if the metal halide deposit is doped with excess halogen to modify its properties. However, the main source of metal and halogen for the metal halide to be deposited according to the invention is obtained by decomposing the halogenated beta-diketonate complex.

The intramolecular fluorine transfer reaction in which metal fluorides are formed from beta-diketonate complexes requires energy to be supplied to the complexes at the reaction site to produce metal halide products. The energy source for the reaction is not critical and can be an electric furnace, flame, laser or other heating device. Other suitable energy supply means include plasmas, such as plasma discharges at radio or microwave frequencies.

- For boat fishing, energy supply techniques are preferred that provide uniform thermal conditions throughout the reaction zone and minimize heating of the reactants beyond that necessary to initiate the decomposition reaction. Condensation within the reaction zone can cause carbonization of decomposition by-products and create carbon deposits in the metal halide product.

Processing of the particulate precursors resulting from the decomposition reaction may be carried out in a known manner to provide optical waveguide fibers or other infrared transmitting optical devices. Fusion densification of such precursors into a transparent glass can be accomplished, in the case of stable glass-forming compositions, simply by heating the precursors to the fusion densification temperature; This may be done simultaneously with the particulate deposition if desired. If the precursor is deposited as a smooth film, a fusion densification step is generally not necessary.

Fluoride glass products produced according to the techniques described above are essentially free of oxygen and metal oxides, despite the presence of metal-oxygen coordination bonds in the beta-diketonate starting material. . The most common contaminant of the product is carbon, but the presence of this impurity can be minimized by avoiding excessive temperatures in the reaction zone that can carbonize the organic substituents of the organometallic molecules.

Alternatively, it is useful to use carbon getters such as 0□, F2, CF4, etc. to avoid carbon in the product.

The invention may be better understood by reference to the following examples of making metal halides by vapor deposition in accordance with the invention.

Example 1 Pure metal halide, AlF2, is present in a carrier gas stream passed through a heated reaction zone. Aluminum beta-diketonate Aβ(hfa): + (
It is produced by thermally decomposing aluminum (hexafluoroacetylacetonate). A suitable apparatus for carrying out this technique is shown schematically in FIG.

Referring to FIG. 1, after a carrier gas such as argon from source 8 is metered by flow controller 9,
It can be fed for reaction through either glass feed tube 10 or 11. For approaches where a getter gas (eg 0□ as shown) is to be used, an optional other gas source 12 is provided along with a flow meter 13.

Argon carrier gas is supplied by glass feed tube 11 or 1
2 can be used to feed into the device.

If a feed tube 11 is used, the argon carrier gas is transferred to an evaporation chamber 40 which can be heated by an oil bath 42.
sent inside. Argon introduced into this chamber 40 picks up vapors of heated organometallic compounds, such as Al(hfa) 3 , and transports the vapors through glass feed tube 14 to glass reaction tube 15 . The feed tube 14 is optionally provided with heating means, such as electrical heating tape, for use if the compound 45 tends to condense within the tube.

The organometallic vapor entering the feed tube 15 was conveyed through a reaction zone 30, which is the part of the tube 15 within the real zone of the electrically heated furnace 31.

The vertical walls of the furnace 31 can be moved horizontally to adjust the length of the reaction zone.

The metal halide produced by intramolecular halogen migration during decomposition of the organometallic compound in the furnace is non-volatile and is deposited on the wall of the tube 15 in or outside the reaction zone 30.

Volatile by-products of the decomposition are carried out of the reaction zone and may be condensed in an optional trap 18 or removed by washing. If desired, a porous plug may be provided in the outlet or reaction zone 30 to trap metal halides carried by the vapor stream. The pressure within the reaction zone can be monitored by gauge 21 and controlled by needle valve 22.

In operation of this apparatus to produce pure AlIF5, which is used, for example, in making infrared transparent halide glasses, pure Aj!, a white crystalline compound that melts at 73°C, is produced. (hfa) is placed in an evaporation chamber and heated to about 80°C.

Next, argon was applied to the feed tube 10 at a flow rate of about 400 cc/min.
The temperature of the furnace is 500°C while being sent to the reaction tube 15 through
Then, the feed pipe 14 is heated to 120°C. The device pressure is approximately 10 (
In(Hg) is maintained.

The reaction tube is formed of Corning Code 7740 glass, a high-temperature borosilicate glass with a coefficient of thermal expansion of about 33 x 10-77"c and good chemical resistance. The reaction tube has an inner diameter of about 22 The length within the hot zone of the furnace is approximately 12 inches.

After the conditions described above have been established, a flow of argon is applied to tube 1.
0 to tube 11, and A7! (hfal+
Vapor is picked up and passed through chamber 40 where it is transported through tube 14 and into reaction tube 15 and zone 30. Aj in the reaction zone! When the thermal decomposition of (hfa)3 begins, a gray-black powder forms on the walls of the reaction tube and a yellow liquid is collected in the cold trap. After 1-2 hours of operation, the apparatus is shut down and the solid reaction product on the reaction tube wall is collected for analysis.

The above gray-black powder was examined by X-ray diffraction and chemical analysis, and it is AlF3. Carbon trace (0
, 2% by weight). In this way, under the above conditions, Aj! (hfa)3 is decomposed into A#F3 and A
7! Instead of a mixture of z O:l, AffF3 is obtained. The yellow liquid byproduct captured is 2,2-difluoro-2,3-dihydro-5-trifluoromethylfuran-3-one, which has the following structural formula.

F3Co F O Example 2 In another approach, the steps of Example 1 are repeated, except that a getter gas for the carbon consisting essentially of pure oxygen is introduced into the reaction zone during the decomposition reaction. Referring to FIG. 1, this oxygen is provided to an oxygen source 12 and metered by a flow meter with a valve to control the flow of acid into the reaction tube.

The vapor flow introduced into the reaction tube 15 contains a carrier gas consisting of 50% by weight of 0□ and 50% by weight of Ar;
This mixture passes through the reaction tube at a flow rate of 40 cc/min.

The reaction tube has a diameter of 310 mm and the reaction zone has a length of 15 mm.
．． It is 24 cm (6 inches). The system pressure during operation is maintained at 200 m (Hg).

If the furnace is operating at 500°C, the argon portion of the carrier stream is switched from tube 10 to tube 11 and passed through evaporation chamber 40, which is maintained at 80°C. Heated Aj! (hfa)3i gas is picked up by the argon and pumped into the reaction zone along with oxygen getter gas from source 12.

Under the conditions described above, a white deposit forms on the walls of the tube 15 in the reaction zone. After one hour of operation, argon is switched again from tube 11 (and the steam generator) to tube 10, and after flushing the reaction tube with an argon carrier gas mixture, the gas flow is shut off and reaction tube 1
5 is removed from the device. Analysis of the deposited product shows it to be AffF3, which is essentially free of co-deposited carbon.

As mentioned above, the reaction to form metal fluorides from fluorinated beta-diketonates can be carried out by a variety of methods, including techniques such as laser heating and energy supply with plasma or ultraviolet light, in addition to the direct heating method described above. Can be promoted. A particularly promising technique for minimizing excessive heating of the reaction zone is non-isothermal plasma vapor deposition, such as deposition using low pressure radio frequency or microwave plasmas. These techniques are of particular interest for depositing very soft (low melting point) glasses that can be liquid at the temperatures required for pyrolysis. The following example illustrates such a technique.

Example 3 A steam delivery and reaction apparatus similar to that of Example 1 above, except that the furnace in the reaction zone is replaced with a microwave plasma generator to drive the steam deposition reaction.
As mentioned above, AI (hfa):+ A7 from the starting member!
Used to produce the F3 reaction product. The microwave plasma generator comprises a cylindrical resonant microwave cavity surrounding the reaction tube, which is connected to a variable power 2.45 GHz microwave generator.

A steam delivery and reaction apparatus of this type with a microwave cavity at the reaction location for carrying out the decomposition reaction is shown in FIGS. 2 and 3. Referring to FIG. 2, a carrier gas, such as argon, may be supplied from a source 8 and directed into either glass feed tube 10 or 11, with flow rate controlled by a mass flow meter. An optional gas supply 12, including a carbon getter, such as CH, is provided, along with a flow meter 13 for metering this gas. A steam generator 40, 42, 45 is provided as shown in FIG. However, in this device, when the organometallic vapor is fed into the reaction tube 15, the microwave discharge region 3 maintained in the reaction tube by the microwave cavity
Enters 0. Microwave power is provided by a conventional microwave generator (not shown) connected to the cavity by a coaxial cable.

The microwave cavity 31 is arranged on a conveying structure that reciprocates the cavity along the reaction tube 15, so that the microwave discharge region 30 moves in the longitudinal direction inside the reaction tube. There is. The reaction tube 15 and microwave cavity 31 are housed in a heated enclosure 34 with a view boat 35 shown in phantom. The enclosure is maintained at a temperature sufficient to prevent unreacted output material from condensing on the interior walls of the reaction tube.

Referring to FIG. 3, which is a schematic cross-sectional view of the apparatus of FIG. 2 taken along line 3--3, enclosure 34 includes a cavity 31 supported on a transport structure 32. Cavity 31
includes conventional tuning means 36 used to adjust the cavity properties to obtain effective coupling of microwave energy to the plasma. The chamber 34 has a door 37 to be able to adjust its tuning means.

In operation of the illustrated apparatus, a predetermined amount of solid A
An evaporation chamber 40 (FIG. 2) containing 12 (hfa)i 45 is heated by an oil bath 42 to a temperature of approximately 40°C. At the same time, a flow of argon from tank 8 is started and is pumped through feed tube 10 directly into the reaction zone in reaction tube 15 . The initial flow through the 1° tube is approximately 2
, Occ/min flow rate of argon, and the system pressure is approximately 1 m (Hg) by vacuum source 20 and needle valve 22.
and is measured by a gauge 21. A microwave discharge 30 is started in the reaction tube section surrounded by the microwave cavity 31 and the discharge lasts approximately 100
It is regulated at an input power level of Watts.

After the discharge has stabilized, the argon flow from tank 8 is gradually switched from feed tube 10 to feed tube 11 and passes through chamber 40, where the heated A7! (hfa). Evaporated Aj pink-amplified by argon! (hfa)3 is fed into the reaction tube 15 through the heated feed tube 14. At the same time, CF, which is a carbon getter gas, is supplied from the tank 12 to the reaction tube through the feed pipe 10 at a flow rate of 10 cc/min. The heated feed pipe 14 and the enclosure are A Il (h fa
): maintained at approximately 120°C to prevent condensation before entering the reaction zone.

A j! The (h fa) z reactants decompose as they pass through the microwave discharge reaction zone 30 within the reaction tube to produce solid and scum-like products. Gaseous by-products from the decomposition of Al(hfa)i are discharged from the apparatus consisting of the reaction zone. The white powdery solid product is retained and deposited on the walls of reaction tube 15 and is subsequently found to be /lF3 by chemical and X-ray analysis.

An optional trap 18 may be provided to condense by-products and untreated materials present in the effluent, if desired.

Analysis of the AlF2 produced by this plasma deposition indicates a carbon contamination level of about 0.03% by weight. This low carbon content is due in part to the relatively uniform and controlled thermal conditions that exist in the plasma reaction zone. 02 or F2 as required
The carbon content can be further reduced by using other getter gases such as CF4 alone or in combination with CF4 or each other.

Examples of metal halide compositions that can be used to make glasses by controlled decomposition of halogenated beta-diketonate complexes in accordance with the present invention are shown in Table 1. Table 1 lists candidate compositions known to form metal halide glasses and those compositions that are sufficient to be considered promising starting compounds for making vapor deposited glasses. Metal heteral diketonate compounds that exhibit volatility are exemplified.

Table ■ Composition Candidate Glass Raw Material No. 1 Composition (Mole 2) - Chemical L compound - 1100% Be
Fz B e (hfa)z2 92.
5% B e F 2, B e (hfa) 2.
7.5%A RF 3 A 7! (hfa)+
3 70% pbF2, P b (tfa)
2.30% A 12 F 3 A A (h
fa):+ For example, in order to produce an optical waveguide preform by the method of the present invention using the typical composition shown in Table 1 above, a raw material compound or a mixture of raw material compounds in a suitable carrier gas is used. Multiple layers of halide glass can be formed on the inner walls of the tube, which is decomposed in a reaction tube that is a bait tube for the preform, and which ultimately forms the core and cladding layers of the optical waveguide. Equipment that can be used to make the preforms includes, for example, equipment designed to make metal halide preforms as disclosed in US Pat. No. 4,378,987. The apparatus includes a number of steam generators, means for rotating a reaction tube in a heated environment, and relative movement between the reaction tube and a heating source for sintering the metal halide deposit into glass. It is equipped with a means for causing this. However, since a fluorinating agent such as HF does not need to be used, the device of the above US patent
It may be simplified in that a simple feed tube or other intake tube may be used to convey the vapor into the bait tube. A theoretical example of creating a waveguide preform according to the present invention will be described.

A reaction tube made of Corning Code 7073 glass is selected for use as a bait tube for the preform. The glass forming this tube has a diameter of about 53 x 10 It is a borosilicate glass with a coefficient of thermal expansion of c.

To form a glass cladding layer on the inner wall of this tube, an argon carrier containing vapor of B e (hfa)z (beryllium hexafluoroacetylacetonate), a white crystalline organometallic compound that melts at 70 °C A gas stream is passed through the tube. B e (hf
The aL steam is produced by a steam generator such as that shown in FIG. 1 or FIG. If necessary, carbon getters such as oxygen, fluorine, CF4 and oxygen can be included in the vapor stream to minimize carbon deposition.

During this period of steam flow, the tube is rotated about its axis and the B e present in the steam flow is
(hfa)z is shuttled through an energy source such as a furnace or flame to convert it to BeFz. If thermal heating is used, the bait tube is heated in order to decompose the Be(hfa)2 and sinter the deposited BeF2 formed by the decomposition to form a glass layer on the tube wall. A temperature of about 500° C. is sufficient.

During this BeF2 production step, the minimum temperature in the vicinity of the tube wall is maintained at a value high enough, for example 120° C., to prevent unreacted 13 e (hfa)z from condensing on the tube wall soil.

After a layer of sintered BeFz thick enough to form the cladding layer of the waveguide is deposited on the tube wall.
B e (hfaL steam and the carrier gas, i.e., A j!
By adding (hfa) 3 vapor, the composition of the vapor stream is changed. B e (hfa)2 in the vapor flow:
A1. The ratio of (hfa)+ is 12.33:1, about 92.5 mol% BeF2 and about 7.5% /lF3.
A BeFz-AβF3 soot mixture consisting of 5 mol % is obtained and sintered as this soot mixture is deposited on the BeF2 layer of the tube wall clay.

A j! thick enough to form the core element of the waveguide!
F3 layer e After F2 layer is deposited on the tube wall soil,
The steam flow is stopped and the tube is heated to about 710° C. to collapse it into a solid rondo. When viewed in cross section, this waveguide preform contains approximately 7.5 mol% of AAFI and has a refractive index (n
d) is about 1.31 A j! F 3 B e F
A solid core member made of 2 glass, a cladding layer of BeFz having a refractive index (n, ) of about 1628, and a cladding layer of BeFz having a refractive index (n, ) of about 1.5
It consists of an outer layer of borosilicate glass with a refractive index on the order of . When drawn into a glass fiber, an optical waveguide with a step index distribution and a numerical aperture of approximately 0.28 is obtained from this preform.

In addition to making optical waveguide fibers for infrared transmission, the invention can also be applied to making other metal halide products for optical or other applications. Their products are amorphous, highly transparent metal halide glasses, free of undesirable metal contaminants,
It can therefore range from pure but opaque polycrystalline metal fluorides that can be applied in a variety of other technical applications.

These products are halogenated to generate oxygen-free metal halide products without the need to use HF or other additional halogen sources of the type used in the prior art, as described above. It is easily obtained by controlled gas-phase decomposition of heta diketonate.

[Brief explanation of the drawing]

FIG. 1 schematically shows an apparatus for producing metal halides by thermal decomposition treatment, and FIGS. 2 and 3 schematically show apparatuses for producing metal halides by plasma reaction treatment. Same. In the drawing, 8 is a carrier gas supply source, 9 is a flow rate controller, 10.11 is a glass feed tube, 15 is a glass reaction tube,
30 is a reaction zone, 31 is a microwave cavity, 32 is a transport structure, and 40 is an evaporation chamber.

Claims (1)

Claims: 1. A method of making a metal halide product comprising: (a) a vapor of a halogenated metal beta-diketonate containing a metal and a halogen to be incorporated into a metal halide precursor; (b) sufficient to cause the decomposition of said metal beta-diketonate and the formation of a vapor deposition product consisting essentially of the metal and halogen to be incorporated into said precursor; a method of making a metal halide product comprising supplying energy to said reactant vapor stream at a rate of 2. The method according to claim 1, wherein the metal halide is Be, Mg, Pb, Zn, Al, Z
said method, said method comprising at least one metal selected from the group consisting of r, Hf and Ce, and said halogen being selected from the group consisting of Cl and F. 3. The method of claim 2, wherein the beta-diketonate is a fluorinated beta-diketonate and the metal halide precursor is a metal fluoride. 4. The method of claim 3, wherein said energy is provided by thermally heating said reactant vapor stream. 5. The method of claim 3, wherein said energy is provided to said reactant vapor stream by a low pressure plasma discharge.