TW201432026A - Luminescent phosphors containing yttrium aluminate-based yellow-green to yellow - Google Patents

Abstract

Yellow-green to yellow-emitting, lutetium aluminate-based terbium (Tb) containing phosphors for use in white LEDs, general lighting, and LED and backlighting displays are disclosed herein. The phosphor may further contain gadolinium (Gd). In one embodiment of the present invention, the phosphor comprises a cerium-activated, yellow-green to yellow-emitting lutetium aluminate-based phosphor having the formula (Lu1-xAx)3Al5O12: Ce wherein A is at least one of Gd and Tb and 0.1 ≤ x ≤ 1.0, wherein the phosphor is configured to emit light having a peak emission wavelength ranging from about 550 nm to about 565 nm, and wherein the phosphor contains at least some Tb.

Description

Luminescent phosphors containing yttrium aluminate-based yellow-green to yellow

Embodiments of the present invention relate to a luminescent phosphor which is yellow-green to yellow mainly containing an aluminate of rare earth cerium (Tb). The phosphors can be applied to many different technical fields, including general lighting systems, white light illumination systems based on white LEDs, signal lights, indicator lights, etc., as well as display applications such as display backlights, plasma display panels, and LEDs. Display panel and the like.

Embodiments of the present invention relate to aluminate-based phosphors that are activated by erbium and that emit visible light in the yellow-green to yellow portion of the electromagnetic spectrum when doped with rare earth lanthanum (Tb). The phosphor may also include rare earth lanthanum (Lu) and/or lanthanum (Gd). The phrase "visible light in the yellow-green to yellow portion of the electromagnetic spectrum" is defined to mean light having a peak emission wavelength of from about 550 nm to about 600 nm. These phosphors can be used in the commercial market, where white light is produced using so-called "white LEDs". It should be noted that, as a matter of fact, the term is somewhat misrepresented because the light-emitting diode emits a specific monochromatic light instead of A combination of wavelengths of white that are considered by the human eye. But the term is still in the vocabulary of the lighting industry.

In the past, YAG:Ce (铈-activated yttrium aluminate garnet) was used to provide the yellow component of the light in the illumination system mentioned above. YAG:Ce has a relative excitation of blue light compared to other phosphor bodies, especially those based on citrate, sulphate, nitrilo ruthenate and pendant oxy-nitrilo ruthenate. Higher absorption efficiency at high temperatures and Stable in a humid environment with high quantum efficiency (QE > 95%), all whites show a broad emission spectrum.

Aside from the fact that color reproduction is insufficient in some cases, one of the disadvantages of using a YAG:Ce-based phosphor is that the peak emission of this phosphor is too long, i.e., toward orange or red light used as an illumination source in, for example, backlight applications. Too deep. The alternative to YAG:Ce is a Lu ₃ Al ₅ O ₁₂ compound (LAG:Ce) doped with yttrium, which has the same crystal structure as YAG:Ce, and similar temperature and humidity stability to ruthenium-based compounds. The same quantum efficiency. Despite these similarities, LAG:Ce exhibits a different peak emission wavelength than its YAG counterpart; in the case of erbium, this peak wavelength is about 540 nm. However, this emission wavelength is still not short enough to be ideally suited for certain applications, such as backlighting applications and general lighting applications, where appropriate.

Accordingly, there is a need in the art, particularly in the field of backlighting and general illumination, for phosphors that are comparable in temperature and humidity stability to garnet structures but have peak emission wavelengths in the range of from about 550 nm to about 600 nm. According to embodiments of the present invention, such challenges can be solved by providing a phosphor based on lanthanum aluminate (Lu) comprising rare earth lanthanum (Tb). The phosphor may also include rare earth lanthanum (Gd).

Embodiments of the present invention relate to luminescent phosphors containing yttrium (Tb)-based yttrium aluminate-based yellowish green and yellow, and in some embodiments, in addition to Tb, also contain yttrium (Gd). These phosphors can be used in white LEDs, general lighting applications, and LED and backlit displays.

In an embodiment of the present invention, the phosphor may comprise a yttrium-activated yellow-green to yellow-emitting phosphor mainly comprising yttrium (Tb), aluminum (Al), and oxygen (O), wherein the phosphorescence is phosphoric acid. The body is configured to absorb excitation radiation having a wavelength in the range of from about 380 nm to about 480 nm, and to emit light having a peak emission in the range of from about 550 nm to about 600 nm. The aluminate-based yellow-green to yellow luminescent phosphor can be excited by radiation having a wavelength in the range of from about 420 nm to about 480 nm. The phosphor may have the formula (Lu _1-x Tb _x ) ₃ Al ₅ O ₁₂ :Ce, where x is in the range of from about 0.1 to less than 1.0, and wherein the phosphor is configured to absorb wavelengths in the range of from about 380 nm to about 480 nm The excitation radiation, and the emission peak emits light having a wavelength in the range of about 550 nm to about 565 nm. The phosphor may further include a rare earth element yttrium (Gd) and have the formula (Lu _1-xy Tb _x Gd _y ) ₃ Al ₅ O ₁₂ :Ce, wherein x is in the range of about 0.1 to less than 1.0, y is greater than 0, and x+ y<1. In addition, the Tb-containing phosphor may have a CIE coordinate shift of less than 0.005 for both x and y coordinates at temperatures in the range of 20 ° C to 220 ° C - specific examples of such phosphors include (Lu _0.61 Tb _0.3 Ce _0.09 ) ₃ Al ₅ O ₁₂ , (Lu _0.41 Tb _0.5 Ce _0.09 ) ₃ Al ₅ O ₁₂ and (Lu _0.41 Gd _0.2 Tb _0.3 Ce _0.09 ) ₃ Al ₅ O ₁₂ .

In another embodiment of the present invention, the phosphor comprises a yttrium _- activated aluminate-based yellow-green to yellow having the formula (Lu _1-xy A _x Ce _y ) ₃ B _z Al ₅ O ₁₂ C _2z a luminescent phosphor; wherein A is Tb; B is at least one of Mg, Sr, Ca, and Ba; and C is at least one of F, Cl, Br, and I; x 1.0;0.001 y 0.2; and 0 z 0.5.

In another embodiment of the present invention, the phosphor comprises a yttrium-activated aluminate-based yellow-green to yellow luminescent phosphor represented by the formula (Lu _0.91-x A _x Ce _0.09 ) ₃ Al ₅ O ₁₂ . Here, A is Tb, and may further include Gd; and x is in the range of from about 0.001 to about 1.0.

According to other embodiments of the present invention, the white light illumination system may include: an excitation source having an emission wavelength in the range of 200 nm to 480 nm; at least one of a red-emitting phosphor or a green-emitting phosphor; and A yttrium aluminate-based yellow-green to yellow luminescent phosphor, wherein the phosphor is configured to emit light having a peak emission wavelength in the range of from about 550 nm to about 565 nm. The yttrium-activated yellow-green to yellow luminescent phosphor based on yttrium alumina can be configured to absorb excitation radiation having a wavelength in the range of from about 380 nm to about 480 nm. The yellow-green to yellow luminescent phosphor mainly composed of strontium aluminate activated by cerium may further contain cerium.

These and other aspects and features of the present invention will become apparent to those skilled in the <RTIgt;

Figure 1 shows the SEM topography of Lu _2.91 Ce _0.09 Al ₅ O ₁₂ with different MgF ₂ additive concentrations, illustrating that the particle size becomes larger and more uniform as the amount of MgF ₂ additive increases; Figure 2 is a series of different MgF ₂ Example of an additive concentration Y _2.91 Ce _0.09 Al ₅ O ₁₂ x-ray diffraction (XRD) pattern; Figure 3 is a series of exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphors with different MgF ₂ additive concentrations X-ray diffraction (XRD) pattern; Figure 4 is a series of x-ray diffraction (XRD) patterns of an exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor with 5 wt% MgF ₂ additive and 5 wt% SrF ₂ additive; Figure 5 is a series of emission spectra of an exemplary Y _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor having different MgF ₂ additive contents obtained by exciting a phosphor with a blue LED; Figure 6 is excited by a blue LED Lu exemplary series of examples having different additive concentrations of MgF ₂ normalized _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor emission spectrum; FIG. 7 is different additive concentrations Lu blue LED excitation at MgF _{2 2.91} Ce _0.09 Al ₅ O ₁₂ Phosphor emission spectrum; Figure 8 is excited by blue LED Lu ₂ normalized with different additive levels of MgF _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor emission spectrum; The results show the use of a certain amount of additive MgF _2, Lu _2.91 Ce _0.09 Al ₅ O ₁₂ of the emission peak shifted to a shorter The wavelength, and the larger the amount of MgF ₂ additive, the shorter the emission peak wavelength; FIG. 9 is the normalized emission spectrum of Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor with 5 wt% MgF ₂ and 5 wt% SrF ₂ additive, wherein phosphorescence The body has been excited by a blue LED; the comparison results with a control sample containing no halogenated salt additive; the results indicate that the emission peak of the MgF ₂ synthetic compound is shifted to a shorter wavelength than the emission peak of the SrF ₂ synthetic compound; FIG. 10 shows the SrF ₂ additive The concentration increases, how the emission wavelength of a series of example Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphors decreases; Figure 11 is a series of exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphors with different MgF ₂ additive concentrations. The excitation spectrum is shown to show a narrower excitation spectrum as the concentration of the MgF ₂ additive increases; Figure 12 shows an exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ containing 5 wt% MgF ₂ additive compared to a commercial Ce:YAG phosphor. phosphorus Temperature dependence of the body; Figure 13 shows the white light comprises a green-emitting aluminate phosphor of the exemplary LED-based spectrum, the green-emitting phosphor has the formula Lu _2.91 Ce _0.09 Al ₅ O ₁₂ and containing 5wt% SrF ₂ additive; the white LED also includes a red phosphor having the formula (Ca _0.2 Sr _0.8 )AlSiN ₃ :Eu ²⁺ , and when both the green light and the red phosphor are excited by the blue-emitting InGaN LED, White light has a color property CIE x = 0.24 and CIE y = 0.20; Figure 14 is a spectrum of white LEDs with the following composition: blue InGaN LED, respectively having 3 wt% or 5 wt% MgF ₂ or SrF ₂ additive and having the formula Lu _2.91 Green garnet of Ce _0.09 Al ₅ O ₁₂ , red nitriding compound of the formula (Ca _0.2 Sr _0.8 )AlSiN ₃ :Eu ²⁺ or citric acid having the formula (Sr _0.5 Ba _0.5 ) ₂ SiO ₄ :Eu ²⁺ Salt, wherein white light has a color coordinate CIE (x = 0.3, y = 0.3); Figure 15 is a spectrum of the white LED system of Figure 14, in this case measured at 3,000 K; Figure 16A-B shows the halogenation The peak emission wavelength of aluminate is generally in the range of about 550 nm to about 580 nm as the Gd content increases, wherein for the Ba series, the Ba content is stoichiometrically fixed. At 0.15, and wherein the Sr content is fixed at 0.34 by stoichiometry; FIG. 17A-B is an x-ray diffraction pattern of both Ba series and Sr series phosphors, and the luminosity data thereof are shown in FIG. 16A-B; FIG. -20 is a light emission spectrum of a representative Tb-containing and/or Gd-containing phosphor excited by a blue light source according to an embodiment of the present invention; the spectrum is plotted for photoluminescence intensity as a function of light emission wavelength; FIG. 21 is a peak emission wavelength pair a plot of Gd or Tb concentration, and thus showing the effect of the amount of Gd and/or Tb inclusions on the peak light emission wavelength; Figure 22 is for the same series of phosphors having the different Gd concentrations and Tb concentrations studied in Figure 21. , a plot of photoluminescence intensity versus peak emission wavelength; and Figure 23 is a plot of CIE y coordinates plotted against CIE x coordinates for a series of example phosphors undergoing temperature increase; data showing an increase in temperature reduces CIE y coordinates Value and increase the value of the CIE x coordinate.

The embodiments of the present invention will be described in detail by reference to the appended claims, It should be noted that the following figures and examples are not intended to limit the scope of the invention to a single embodiment, but other embodiments may be interchanged with some or all of the elements illustrated or described. In addition, some of the components of the present invention may be used to partially or fully implement some of the components of the present invention, and the other components of the known components are omitted. The detailed description is omitted to avoid obscuring the present invention. Embodiments showing singular components are not to be considered as limiting in the present specification; rather, the invention is intended to cover other embodiments including a plurality of identical components, and vice versa. . In addition, the Applicant does not intend to imply any term in the specification or the scope of the claims as uncommon or special meaning unless explicitly stated otherwise. Furthermore, the present invention encompasses both current and future known equivalents of the known components.

In the past, one of the most common choices for yttrium aluminum garnet compound (YAG:Ce) phosphor materials activated by rare earth lanthanum, YAG can be fabricated if high power LED illumination or non-specific general white light illumination is desired. :Ce. As can be expected, in the case of supplying both the LED chip of the white light blue component and the excitation radiation of the phosphor, a high efficiency component is required in general illumination, wherein the phosphor usually supplies the yellow/green component of the resulting product white light.

As discussed in the foregoing section of the disclosure, YAG:Ce demonstrates that this is expected to be highly efficient, with quantum efficiencies greater than about 95%, and thus improving this number would appear to be a daunting task. However, it is known in the art that the efficiency of an LED chip increases as the emission wavelength decreases, and therefore, in any case, theoretically, if it is emitted with a LED crystal that emits at a shorter wavelength. The paired phosphors can be excited by their shorter wavelengths, which will enhance the efficiency of the general illumination system. Unfortunately, the problem associated with this strategy is that when the wavelength of the blue excitation radiation of the YAG:Ce phosphor falls below about 460 nm, its emission efficiency is reduced.

Of course, this rebound is a case where YAG:Ce is actually only paired with an LED chip having an emission wavelength of not less than about 450 nm to 460 nm. However, it is also known in the art that the photon energy of the excitation radiation of a phosphor strongly depends on the structure of the anionic polyhedron surrounding the activator cation (in this case, an oxygen atom). It is thus concluded that the efficiency of the system can be enhanced if the excitation range of the garnet-based phosphor is extended toward a shorter wavelength relative to the YAG:Ce phosphor. Accordingly, it is an object of the present invention to modify the structure and properties of the anionic polyhedron to shift the excitation range, and the phosphor "desirably" is more visible than conventional YAG:Ce while maintaining (or even improving) the enhanced properties exhibited by many garnets. Short wavelength.

The invention will be divided into the following sections: First, a chemical description of the halogenated aluminate of the present invention (using stoichiometric formula) will be given, followed by a brief description of a possible synthetic method that can be used to produce it. The structure of the haloaluminate of the present invention, and its relationship to experimental data, including wavelength and photoluminescence changes after the incorporation of certain halogen dopants, will be discussed later. Finally, the use of exemplary data to present these yellow-green and yellow-emitting phosphors can play a role in white light illumination, general illumination, and backlight applications.

Chemical Description of Phosphors of the Invention Based on Haloaluminates

The aluminate-based yellow to green luminescent phosphor of the present invention contains both an alkaline earth and a halogen component. These dopants are used to achieve the desired photoemission intensity and spectral properties, but the fact that alkaline earth and halogen are simultaneously substituted to provide a self-contained charge balance is also accidental. In addition, there may be other advantageous compensations associated with an overall change in unit cell size: although replacing Lu (in individual or combined form) with any of Sc, La, Gd, and/or Tb may tend to enlarge or reduce the unit cell. Size, but the opposite effect can occur when replacing oxygen with halogen.

The formula of the phosphor of the present invention is illustrated in several ways. In one embodiment, the aluminosilicate-based luminescent green phosphor doped with yttrium may be of the formula Lu _1-abc Y _a Tb _b A _c ) ₃ (Al _1-d B _d ) ₅ (O _1-e C _e ) ₁₂ : Ce, Eu, wherein A is selected from the group consisting of Mg, Sr, Ca, and Ba; B is selected from the group consisting of Ga and In; and C is selected from the group consisting of F, Cl, and Br. ;0 a 1;0 b 1;0<c 0.5;0 d 1; and 0<e 0.2. The "A" element used singly or in combination may be any of the alkaline earth elements Mg, Sr, Ca, and Ba, which are extremely effective in shifting the emission wavelength to a shorter value. These compounds may be referred to as "a halogenated LAG-based" aluminate or simply "haloaluminate" in the present invention.

In an alternative embodiment, the aluminate-based yellow to green luminescent phosphor of the present invention can be illustrated by the formula (Y,A) ₃ (Al,B) ₅ (O,C) ₁₂ :Ce ³⁺ , wherein At least one of A, Tb, Gd, Sm, La, Lu, Sr, Ca, and Mg, including combinations of elements thereof, wherein the substitution amount of such elements to Y is stoichiometrically from about 0.1% to about 100%. Within the scope. At least one of B-type Si, Ge, B, P, and Ga, including combinations thereof, and the elements replace Al with an amount ranging from about 0.1 to about 100 stoichiometric percent. At least one of the C systems F, Cl, N, and S, including combinations thereof, replaces oxygen in an amount ranging from about 0.1 to about 100 stoichiometric percent.

In an alternative embodiment, the aluminate-based yellow to green luminescent phosphor of the present invention can be illustrated by the formula (Y _1-x Ba _x ) ₃ Al ₅ (O _1-y C _y ) ₁₂ :Ce ³⁺ Wherein x and y are each in the range of from about 0.001 to about 0.2.

In an alternative embodiment, the aluminosilicate-based luminescent green phosphor may be of the formula (A _1-x ³⁺ B _x ²⁺ ) _m Al ₅ (O _1-y ^2- C _y ^1- ) _n :Ce ³⁺ , wherein A is selected from the group consisting of Y, Sc, Gd, Tb, and Lu; B is selected from the group consisting of Mg, Sr, Ca, and Ba; and C is selected from the group consisting of F, Cl, and Br. ;0 x 0.5;0<y 0.5; 2 m 4; and 10 n 14. (Paragraph A)

In an alternative embodiment, the yellow-green to green luminescent phosphor based on aluminate may be of the formula (A _1-x ³⁺ B _x ²⁺ ) _m Al ₅ (O _1-y ^2- C _y ^1- ) _n :Ce ³⁺ , wherein A is selected from the group consisting of Y, Sc, Gd, Tb, and Lu; B is selected from the group consisting of Mg, Sr, Ca, and Ba; and C is selected from the group consisting of F, Cl, and Br. Group; 0 x 0.5;0 y 0.5; 2 m 4; and 10 n 14; The precondition is that m is not equal to 3.

In an alternative embodiment, the yellow-green to green luminescent phosphor based on aluminate may be of the formula (A _1-x ³⁺ B _x ²⁺ ) _m Al ₅ (O _1-y ^2- C _y ^1- ) _n :Ce ³⁺ , wherein A is selected from the group consisting of Y, Sc, Gd, Tb, and Lu; B is selected from the group consisting of Mg, Sr, Ca, and Ba; and C is selected from the group consisting of F, Cl, and Br. Group; 0 x 0.5;0 y 0.5; 2 m 4; and 10 n 14; The precondition is that n is not equal to 12.

In an alternative embodiment, the aluminate-based yellow to green luminescent phosphor can be illustrated by the formula (Lu _1-xy A _x Ce _y ) ₃ B _z Al ₅ O ₁₂ C _2z , wherein the A system is Sc, La, At least one of Gd and Tb; at least one of B alkaline earth Mg, Sr, Ca, and Ba; at least one of C halogen elements F, Cl, Br, and I; and parameters x, y, and z Value system 0 x 0.5; 0.001 y 0.2; and 0.001 z 0.5. It should be noted that for the equation in the present invention, "at least one of" means that the elements in the group may appear in the phosphor individually or in combination, wherein in the group Any combination of any of the elements is permissible, provided that the total amount of the group satisfies the requirements assigned to it in terms of the overall stoichiometric amount.

Those skilled in the art will appreciate that if the C and B components are added to the starting mixture of materials in the form of an alkaline earth salt (e.g., B ²⁺ C ₂ ), then after a processing step such as sintering, C halogen and B The relationship between the amounts of alkaline earth cannot always be present in the phosphor product at an expected ratio of 2:1 (stoichiometric). This is due to the fact that the halogen component is known to be volatile, and in some cases some C is lost relative to B such that the ratio of B to C in the final phosphor product is less than 2:1. Thus, in an alternative embodiment of the invention, the amount of C in the formula of paragraph A is less than 2z by an amount of up to 5%. In various other embodiments, the amount of C is less than 2z by stoichiometric amounts of up to 10%, 25%, and 50%.

synthesis

Any of the methods can be used to synthesize the aluminate-based yellow-green to yellow luminescent phosphors of the present invention, and the methods can involve both solid state reaction mechanisms and liquid mixing techniques. Liquid mixing includes methods such as coprecipitation and sol-gel techniques.

One embodiment of the preparation relates to a solid state reaction mechanism comprising the steps of: (a) combining a desired amount of starting materials CeO ₂ , Y ₂ O ₃ , cerium salts (including nitrates, carbonates, halides and/or cerium) Oxide), a salt of other rare earths Sc, La, Gd and Tb and M ²⁺ X ₂ (wherein M is selected from the group consisting of Mg, Sr, Ca and Ba, and the X is selected from F, a halogen of the group consisting of Cl, Br and I) to form a mixture of starting powders; (b) dry mixing of the starting powder mixture of step (a) using any conventional method (eg ball milling), and using a typical mixing time of ball milling More than about 2 hours (about 8 hours in one embodiment); (c) a step in a reducing atmosphere (the purpose of this atmosphere is to reduce ammonia-based compounds) at a temperature of from about 1400 ° C to about 1600 ° C ( b) mixing the starting powder for sintering for about 6 to about 12 hours; (d) crushing the sintered product of step (c) and washing it with water; and (e) drying the washing product of step (d), wherein drying conditions It can be at a temperature of about 150 ° C for about 12 hours.

The aluminate of the present invention can be synthesized by liquid mixing techniques. An example of synthesizing a non-halogenated LAG compound having the formula Lu _2.985 Ce _0.015 Al ₅ O ₁₂ using coprecipitation has been described by H.-L. Li et al. under the heading "Fabrication of Transparent Cerium-Doped Lutetium Aluminum Garnet Ceramics by Co-Precipitation. Routes," J. Am. Ceram. Soc. 89 [7] 2356-2358 (2006). The non-halogenated LAG compounds do not contain an alkaline earth component. The full text of this paper is incorporated herein, and as expected, a similar coprecipitation method can be used to produce the halogenated LAG of the present invention having an alkaline earth component.

An example of the synthesis of a halogenated YAG compound using a sol-gel technique is described in U. McFarland et al., Symyx Technologies, U.S. Patent 6,013,199, entitled "Phosphor materials". The (possibly) halogenated YAG compounds are free of alkaline earth components. The entire disclosure of this patent is incorporated herein by reference to a similar sol-gel process which can be used to produce the halogenated YAG compounds of the present invention having an alkaline earth component.

1 shows the SEM topography of an exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor having different MgF ₂ additive concentrations, synthesized via the solid state mechanism set forth above. The morphology revealed by scanning electron microscopy (SEM) shows an increase in particle size as the amount of MgF ₂ additive increases, and becomes more uniform. The phosphor has a particle size of from about 10 microns to 15 microns.

Crystal structure of yellow-green to yellow light-emitting aluminate of the invention

The crystal structure of the yellow-green to yellow aluminate of the present invention is similar to that of the yttrium aluminum garnet Y ₃ Al ₅ O ₁₂ , and like the fully studied YAG compound, the aluminate of the present invention may belong to the Ia3d space group (No. 230). . This space group for YAG has been discussed by Y. Kuru et al. in the paper entitled "Yttrium Aluminum Garnet as a Scavenger for Ca and Si," J. Am. Ceram. Soc. 91 [11] 3663-3667 (2008) in. As illustrated by Y. Kuru et al., YAG has a complex crystal composed of 160 atoms (8 units) per unit cell, where Y ³⁺ occupies a multiplicity of 24, the Wyckoff letter "c" and The site is symmetrically located at 2.22, and the O2 ^- atom occupies a multiplicity of 96, a Wyckoff letter "h", and a position symmetry 1. Two Al ³⁺ ions are located at the octahedron 16 (a) position, while the remaining three Al ³⁺ ions are located at the tetrahedral 24 (d) site.

The lattice parameter of the YAG unit cell is a = b = c = 1.2008 nm and α = β = γ = 90 °. It is desirable to replace the germanium with germanium to expand the size of the unit cell, and it is not desirable to change the angle between the unit cell axes, and the material will retain its cubic features.

Figure 2 shows a series of x-ray diffraction (XRD) patterns of an exemplary Y _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor with different MgF ₂ additive concentrations, showing how the addition of alkaline earth metal and halogen (MgF ₂ ) components makes The high angle diffraction peak shifts to a higher 2θ value. This means that the lattice constant becomes smaller with respect to the alkaline earth/halogen-free YAG component, and further indicates that Mg ²⁺ is incorporated into the crystal lattice, occupying the Y ³⁺ position.

Figure 3 shows an x-ray diffraction (XRD) pattern of a series of exemplary phosphors in a manner similar to Figure 2, except that the compound series is a Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor having different MgF ₂ additive concentrations, Among them, compounds based on ruthenium are studied instead of compounds based on ruthenium.

4 shows an x-ray diffraction (XRD) pattern of an exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor with 5 wt% MgF ₂ and 5 wt% SrF ₂ additive: This experiment shows a comparison of the Mg component versus the Sr component. The data shows that in the case of a MgF ₂ additive in the Lu _2.91 Ce _0.09 Al ₅ O ₁₂ lattice, the high angle diffraction peak shifts to a larger 2θ value, which means that the lattice constant becomes smaller. Alternatively, with the SrF ₂ additive, the high angle diffraction peak moves to a smaller 2θ value, which means that the lattice constant increases. Those skilled in the art should understand that both Mg ²⁺ and Sr ²⁺ are incorporated into the Lu _2.91 Ce _0.09 Al ₅ O ₁₂ lattice and occupy the Lu ³⁺ position. These peaks are shifted because Mg ²⁺ with an ionic radius of 0.72 Å is smaller than Lu ³⁺ (0.86 Å), and Sr ²⁺ (1.18 Å) is larger than Lu ³⁺ .

Mechanism of the influence of alkaline earth and halogen on optical properties

In one embodiment of the invention, Ce ³⁺ is a luminescence activator in an aluminate-based phosphor. The transition between the 4f and 5d energy levels of the Ce ³⁺ ion corresponds to the excitation of the phosphor with blue light; the result of the same electronic transition from the green light emission of the phosphor. In the aluminate structure, Ce ³⁺ is located at the center of the octahedral site formed by the polyanion structure of six oxygen ions. Those skilled in the art will appreciate that, depending on the crystal field theory, the surrounding anion (which may also be described as a ligand) causes an electrostatic potential on the 5d electron of the central cation. The 5d energy cascade system 10Dq, where Dq is known to depend on the particular ligand species. It can be observed from the series of spectrochemical chemistry that the Dq of the halide is less than the Dq of oxygen, and therefore it is concluded that when the oxygen ion is replaced by a halide ion, Dq will correspondingly decrease.

This implies that the band gap energy (i.e., the energy difference between the 4f and 5d electron energy levels) will increase as the oxygen ions are replaced by halide ions in the polyanion cage surrounding the activator ions. This is why the emission peak shifts to a shorter wavelength with halogen substitution. At the same time, in the case of introducing a halogen ion into the oxygen polyanion structure forming the octahedral site, the corresponding cation may also replace one The content of Lu (and / or Sc, La, Gd and Tb). If the cation of Lu (and/or other rare earths) is substituted for a smaller cation, the result is that the emission peak shifts towards the blue end of the spectrum. The emitted fluoresce has a wavelength that is shorter than the wavelength that would otherwise occur. Conversely, if the cation replacing Lu is a larger cation (such as Sr or Ba), the result is that the emission peak shifts toward the red end of the spectrum. In this case, the emitted fluorescent light has a longer wavelength.

In combination with the effect of the halide, if blue shift is desired, Mg as an alkaline earth substitute is a better choice than Sr, and this will be experimentally shown in the following section of the invention. It is also known that the LAG emission peak is coupled to a double peak due to spin-orbital coupling. When a blue shift occurs, the emission shift with a shorter wavelength and its intensity increases accordingly. This trend not only contributes to the blue shift of the emission, but also enhances the photoluminescence.

Figure 5 is a series of emission spectra of an exemplary Y _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor having different MgF ₂ additive contents obtained by exciting a phosphor with a blue LED. This data shows that as the amount of MgF2 increases, the photoluminescence intensity increases and the peak emission wavelength shifts to a shorter value. Although not shown in Figure 5, the inventors have data for the addition of 5 wt% BaF _{2 to} the starting powder: this phosphor exhibits a significant increase in photoluminescence intensity relative to the three magnesium-containing phosphors, and peak emission The wavelength is approximately the same as the peak emission wavelength of the 1 wt% sample.

The normalized version of the Figure 5 data is shown in Figure 6. Figure 6 is a normalized emission spectrum of an exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor of the same series with different MgF ₂ additive concentrations excited by a blue LED, but where the photoluminescence intensity is normalized to a single value to highlight The emission peak of Y _2.91 Ce _0.09 Al ₅ O ₁₂ shifts to a short wavelength as the amount of the MgF ₂ additive increases. The larger the amount of the MgF ₂ additive, the shorter the emission peak wavelength. This is the same trend as confirmed by the Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor, as will be confirmed later.

Figure 7 is a series of emission spectra of an exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphor having different MgF ₂ additive contents obtained by exciting a phosphor with a blue LED. This data is similar to the data in Figure 5, except that compounds based on sputum rather than sputum are studied. As with the 钇 data, this data shows a similar trend in the shift of the emission wavelength, but the trends in photoluminescence intensity may not be similar.

The Lu _2.91 Ce _0.09 Al ₅ O ₁₂ emission spectrum of Figure 7 has been normalized to emphasize the effect of the addition of a halogen salt on the peak emission wavelength; a normalized version of the data is shown in Figure 8. As in the case of ruthenium, as the amount of MgF ₂ additive increases, the peak emission shifts to a shorter wavelength; that is, the larger the amount of the MgF ₂ additive, the shorter the emission peak wavelength. When the amount of MgF2 additive was increased from 0 (no additive) to about 5 wt% additive, the amount of wavelength shift was observed to be about 40 nm; shifting from about 550 nm to about 510 nm.

Each of Figures 5 through 8 plots their respective spectra as a series of phosphor compositions with increasing additive concentrations (starting with no additives and ending at the highest concentration of the 5 wt% series). To emphasize the comparison of SrF ₂ additive with MgF ₂ additive; in other words, phosphor with Sr alkaline earth and fluorine content and phosphor with Mg alkaline earth and fluorine content, the phosphor has been drawn together in Figure 9: additive-free phosphor, A phosphor having 5 wt% SrF ₂ and a phosphor having 5 wt% MgF ₂ . The phosphorescence system was dominated by the sample Lu _2.91 Ce _0.09 Al ₅ O ₁₂ .

The emission spectral data in Figure 9 has been normalized to better emphasize the effects on the optical properties produced by the inclusion of halogens and alkaline earths. When excited with a blue LED, the results illustrate that the emission peak shifts to a shorter wavelength with the addition of MgF ₂ and SrF ₂ . The additive-free Lu _2.91 Ce _0.09 Al ₅ O ₁₂ sample exhibited a peak emission wavelength at about 550 nm; the peak emission wavelength with a 5 wt% SrF ₂ additive shifted to about 535 nm, and the wavelength with 5 wt% MgF ₂ additive was even further shifted Up to about 510 nm.

Figure 10 shows how the emission wavelength of a series of exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphors decreases as the concentration of the SrF ₂ additive increases. Has a peak emission wavelength is plotted with SrF ₂ additive amount of change; test having 1wt%, 2wt%, Sample _2, and the additive content of 5wt% 3wt% of SrF. The results are shown for samples 1wt% and 2wt%, about the same emission peak wavelength, a wavelength of 535 nm is about; SrF ₂ increased with additives to 3wt%, a peak wavelength of emission is reduced to about 533nm. At a further increase of SrF ₂ additive to 5 wt%, the peak wavelength drops sharply to about 524 nm.

Excitation spectrum and temperature dependence

Figure 11 is a normalized excitation spectrum of a series of exemplary Lu _2.91 Ce _0.09 Al ₅ O ₁₂ phosphors having different MgF ₂ additive concentrations, showing a narrow change in excitation spectrum as the concentration of MgF ₂ additive increases. The data demonstrates that the aluminate-based green luminescent phosphor of the present invention exhibits a broad wavelength band in the range of from about 380 nm to about 480 nm, within which the phosphor can be excited.

The thermal stability of the garnet phosphor of the present invention is exemplified by the cerium-containing compound Lu _2.91 Ce _0.09 Al ₅ O ₁₂ having 5 wt% MgF ₂ additive; compared with the commercially available phosphor Ce ³⁺ : Y ₃ Al in Fig. 12 ₅ O ₁₂ thermal stability. It can be observed that the thermal stability of the Lu _2.91 Ce _0.09 Al ₅ O ₁₂ compound is even better than YAG.

Backlight and white lighting system applications

In accordance with other embodiments of the present invention, the aluminate-based green-emitting phosphors of the present invention can be used in white light illumination systems (commonly referred to as "white LEDs") and backlight configurations for display applications. The white light illumination system includes: a radiation source configured to emit radiation having a wavelength greater than about 280 nm; and a green an aluminate phosphor doped with a halide anion configured to absorb at least a portion of the source from the radiation source It emits light having a peak wavelength in the range of 480 nm to about 650 nm.

Figure 13 shows a spectrum of a white LED comprising an exemplary aluminate-based green-emitting phosphor having the formula Lu _2.91 Ce _0.09 Al ₅ O ₁₂ and having a 5 wt% SrF ₂ additive. The white LED further includes a red phosphor having the formula (Ca _0.2 Sr _0.8 )AlSiN ₃ :Eu ²⁺ . When both the green aluminate and the red nitride phosphor were excited with a blue-emitting InGaN LED, the resulting white light exhibited a color coordinate CIE x = 0.24 and CIE y = 0.20.

Figure 14 is a spectrum of white LEDs having the following composition: blue InGaN LED, green garnet with 3 wt% or 5 wt% additive and having the formula Lu _2.91 Ce _0.09 Al ₅ O ₁₂ , having the formula (Ca _0.2 Sr _0.8 ) AlSiN ₃ : red photonitride of Eu ²⁺ or a bismuth salt of the formula (Sr _0.5 Ba _0.5 ) ₂ SiO ₄ :Eu ²⁺ , wherein the white light has a color coordinate CIE (x=0.3, y=0.3). The sample showing the most obvious double peak is labeled "EG3261+R640", wherein the EG3261 mark indicates that it is combined with red light R640 (Ca _0.2 Sr _0.8 ) AlSiN ₃ :Eu ²⁺ phosphor emitted at about 640 nm (Sr _0.5 Ba _{0.5 2} SiO ₄ :Eu ²⁺ phosphor. Two peaks labeled LAG (3 wt% MgF ₂ ) + R640 and LAG (5 wt % SrF ₂ ) + R640 demonstrate a more uniform emission of perceived white light in the wavelength range from 500 nm to 650 nm, which is a desirable property in the industry.

Figure 15 is a spectrum of the white LED system of Figure 14, in this case measured at 3,000K.

In an embodiment of the present invention, the red photonitride which may be used in combination with the green aluminate may have the general formula (Ca,Sr)AlSiN ₃ :Eu ²⁺ , wherein the red photonitride may further comprise an optional halogen. And wherein the content of oxygen impurities in the red photonitride phosphor may be less than or equal to about 2% by weight. The yellow green citrate may have the general formula (Mg, Sr, Ca, Ba) ₂ SiO ₄ :Eu ²⁺ , wherein the alkaline earth may be present in the compound individually or in any combination, and wherein the phosphor may pass F, Cl , Br or I (again, individually or in any combination) is halogenated.

Optical and physical data in tabular form

An overview of the example data is tabulated in Tables 1 and 2. Table 1 shows the test results of phosphors based on Lu _2.91 Ce _0.09 Al ₅ O ₁₂ having three different MgF ₂ additive contents. Table 2 summarizes the test results for compounds based on Lu _2.91 Ce _0.09 Al ₅ O ₁₂ with four different SrF ₂ additives. These results summarize and confirm that the MgF ₂ and SrF ₂ additives in Lu _2.91 Ce _0.09 Al ₅ O ₁₂ shift the emission peak wavelength to shorter wavelengths, where the emission intensity increases as the concentration of MgF ₂ and SrF ₂ increases. The particle size also increases as the concentration of the MgF ₂ and SrF ₂ additives increases.

Yellow-green to yellow luminescent phosphor doped with rare earths and doped with rare earth

The inventors tested the rare earth doping of a specific series of yellow-green to yellow-emitting halogenated aluminates having a general formula (Lu _1-xy A _x Ce _y ) ₃ B _z Al ₅ O ₁₂ C _2z . As disclosed above, A is at least one of Sc, La, Gd, and Tb; B is at least one of alkaline earth Mg, Sr, Ca, and Ba; and at least one of C-based halogen elements F, Cl, Br, and I One; and the values of the parameters x, y, z are 0 x 0.5; 0.001 y 0.2; and 0.001 z 0.5. In this series of phosphors, the rare earth dopant is Gd, and the alkaline earth is Ba or Sr. The halogens in all compounds tested in this series of experiments were F. The formula for the specific aluminate tested is shown in Table 3.

Table 3. Test results of B=Ba and B=Sr and different values of x, y and z (Lu _1-xy Gd _x Ce _y ) ₃ B _z Al ₅ O ₁₂ F _2z

For the purposes of the present invention, green light is defined as having a peak emission wavelength of from about 500 nm to about 550 nm. The emission extending from about 550 nm to about 600 nm can be stated as having a wavelength that changes from yellow-green to yellow. In the experiments described, the addition of Gd doping converts the phosphor from a substantially green-emitting sample to a substantially yellow-light sample; although not shown, it increases the Gd concentration (from about 0.33 for Ba samples and from Sr samples for Sr samples). Approximately 0.13) even further shifts the emission towards the yellow region of the electromagnetic spectrum and shifts it into the yellow region. It is more difficult to generalize it because the peak emission wavelength depends not only on the choice and content of rare earth dopants (such as Gd other than Lu), but also on the alkaline earth and The choice and amount of halogen. In the present invention, an aluminum halide is defined as being emitted in the yellow-green to yellow region of the electromagnetic spectrum at a wavelength of from about 550 nm to about 600 nm. The green-emitting haloaluminate is emitted at a peak wavelength substantially in the range of from about 500 nm to about 550 nm. For the luminescent green aluminate, reference is made to U.S. Patent Application Serial No. 13/181,226, filed on Jan. 12, 2011, which is hereby incorporated by reference.

The data in Table 3 and Figures 16A-B show that the peak emission wavelength of the aluminophosphates is generally in the range of about 550 nm to about 580 nm as the Gd content increases, wherein for the Ba series, the Ba content is stoichiometrically fixed at 0.15. And wherein for the Sr series, the Sr content is fixed stoichiometrically at 0.34 (this concentration is stoichiometric, or numerical, not by weight). For all samples, the Ce activator content was also fixed at 0.03 stoichiometrically. Specifically, for the Ba sample, the amount of Gd increased from 0.07 to 0.17 to 0.33 as the stoichiometric amount, and the peak emission wavelength increased from 554 nm to 565 nm to 576 nm, respectively. For the Sr sample, the amount of Gd increased from 0.03 to 0.07 to 0.13 with stoichiometry, and the peak emission wavelength increased from 551 nm to 555 nm to 558 nm, respectively.

The actual compounds in the Ba series are (Lu _0.90 Gd _0.07 Ce _0.03 ) ₃ Ba _0.15 Al ₅ O ₁₂ F _0.30 , (Lu _0.80 Gd _0.17 Ce _0.03 ) ₃ Ba _0.15 Al ₅ O ₁₂ F _0.30 and (Lu _0.64 Gd _0.33 Ce _0.03 ) ₃ Ba _0.15 Al ₅ O ₁₂ F _0.30 . The actual compounds tested in the Sr series were (Lu _0.94 Gd _0.03 Ce _0.03 ) ₃ Sr _0.34 Al ₅ O ₁₂ F _0.68 , (Lu _0.90 Gd _0.07 Ce _0.03 ) ₃ Sr _0.34 Al ₅ O ₁₂ F _0.68 and (Lu _0.84 Gd _0.13 Ce _0.03 ) ₃ Sr _0.34 Al ₅ O ₁₂ F _0.68 .

It should be noted that the Sr series emits relatively high photoluminescence intensity when compared to the Ba series, but those skilled in the art understand that caution should be drawn to the conclusion that several other variables (eg, Gd content, alkaline earth amount, and halogen concentration) are simultaneously Variety.

The x-ray diffraction pattern of both the Ba series and Sr series phosphors is shown in Figures 17A-B, and the luminosity data is shown in Figures 16A-B.

Aluminate-based yellow-emitting phosphor characterized by strontium (Tb) and/or strontium (Gd)

According to an embodiment of the invention, in certain compositions, the yellow-green to yellow-emitting halogenated aluminate is characterized by the rare earth element cerium (Tb). The inventors have performed an experimental comparison of the relative effects of ruthenium and osmium in a composition (Lu _0.91-x A _x Ce _0.09 ) ₃ Al ₅ O ₁₂ , wherein A represents at least one of Gd and Tb in individual or combined form. The 鋱 is adjacent to the 周期 in the periodic table: the former (Tb) has an atomic sequence 65 and an electronic structure [Xe] 4f ⁹ 6s ² , while the latter (Gd) has an atomic sequence 64 and an electronic structure [Xe] 4f ⁷ 5d6s ² . Formula (Lu _0.91-x A _x Ce _0.09 ) ₃ Al ₅ O ₁₂ shows the replacement of the rare earth lanthanum (Lu) having an atomic sequence 71 and an electronic structure [Xe] 4f ¹⁴ 5d6s ² with both lanthanum and cerium.

In addition to using the methods described above to produce aluminophosphate-based phosphors, the following methods can also be used. The method of making the aluminate-based novel phosphor disclosed herein is not limited to any of the fabrication methods, but can be synthesized, for example, by a three-step process of: 1) blending the starting material, 2) calcining The starting material mixture, and 3) performing a plurality of processes on the calcined material, including grinding and drying. In some embodiments, the starting material can comprise a plurality of powders, such as alkaline earth metal compounds, aluminum compounds, and cerium compounds. Examples of the alkaline earth metal compound include alkaline earth metal carbonates, nitrates, hydroxides, oxides, oxalates, halides and the like. Examples of the aluminum-containing compound include nitrates, fluorides, and oxides. Examples of the cerium compound include cerium oxide, cerium fluoride, and cerium chloride. The starting material is blended in such a way as to achieve the desired final composition. In some embodiments, the alkaline earth, the aluminum-containing compound, and the cerium compound are blended in a suitable ratio and then calcined to achieve the desired composition. The blended starting material can be calcined in a second step, and a flux can be used to enhance the reactivity of the blended material (at any or various stages of calcination). The flux may contain a plurality of halides and boron compounds, and examples thereof include cesium fluoride, cesium fluoride, cesium chloride, cesium chloride, and combinations thereof. Examples of the boron-containing flux compound include boric acid, boron oxide, barium borate, barium borate, and calcium borate.

In some embodiments, the fluxing compound is used in an amount ranging from about 0.01 mole percent to about 0.2 mole percent, with values generally ranging from about 0.01 mole percent to 0.1 mole percent and Includes 0.01% by mole and 0.1% by mole.

Various techniques for mixing starting materials (with or without flux) include, but are not limited to, using a mortar, mixing with a ball mill, mixing with a V-shaped mixer, mixing with a quadrature rotary mixer, using a jet mill Mix and mix with a blender. The starting materials may be dry mixed or wet mixed, wherein dry mixing refers to mixing without using a solvent. Solvents which can be used in the wet mixing process include water or an organic solvent, wherein the organic solvent may be methanol or ethanol. Mixtures of starting materials can be calcined by a variety of techniques known in the art. A heater such as an electric furnace or a gas furnace can be used for baking. The heater is not limited to any particular type as long as the starting material mixture is fired at the desired temperature for a desired length of time. In some embodiments, the firing temperature can range from about 800 °C to 1600 °C. In other embodiments, the firing time can range from about 10 minutes to 1000 hours. The firing atmosphere may especially be selected from the group consisting of air, a low pressure atmosphere, a vacuum, an inert gas atmosphere, a nitrogen atmosphere, an oxygen atmosphere, and an oxidizing atmosphere. In some embodiments, the composition can be calcined in a reducing atmosphere between about 100 ° C to about 1600 ° C for about 2 hours to about 10 hours. The phosphors disclosed herein can be prepared using a sol-gel process or a solid reaction process. In some embodiments, a metal nitrate is used to provide a divalent metal component of the phosphor and an aluminum component of the aluminate-based phosphor. In some embodiments, the metal nitrate supplying the divalent metal component may be Ba(NO ₃ ) ₂ , Mg(NO ₃ ) ₂ or Sr(NO ₃ ) ₂ , and the metal nitrate providing the aluminum may be Al ( NO ₃ ) ₃ .

The method can further comprise the step of using a metal oxide to provide an oxygen component of the aluminate-based phosphor. Examples of the method include the steps of: a) providing a raw material selected from the group consisting of Ba(NO ₃ ) ₂ , Mg(NO ₃ ) ₂ , Ca(NO ₃ ) ₂ , Sr(N0 ₃ ) ₂ , Al ( NO ₃ ) ₃ and Lu ₂ O ₃ ; b) dissolving Lu ₂ O ₃ in a nitric acid solution, and then mixing a desired amount of metal nitrate to form a water-based nitrate solution; c) heating step b) Solution to form a gel; d) heating the gel of step c) to between about 500 ° C and about 1000 ° C to decompose the nitrate mixture into an oxide mixture; and e) in a reducing atmosphere The powder of step d) is sintered at a temperature between about 1000 ° C and about 1500 ° C.

Referring to Table 4, those skilled in the art will recognize that all of the compositions in the table emit light having a peak emission wavelength in the range of from about 550 nm to about 560 nm. The two entities labeled T1 and T2 do not contain Gd, respectively, and have Tb concentrations of x = 0.3 and 0.5, respectively. Therefore, the composition is (Lu _0.61 Tb _0.3 Ce _0.09 ) ₃ Al ₅ O ₁₂ and (Lu _0.41 Tb _0.5 Ce _0.09 ) ₃ Al ₅ O _{12 , respectively} . It emits at the highest relative photoluminescence intensity of the compound other than YAG1 and YAG2.

The third composition from the top of Table 4 contained Gd and Tb at concentrations of 0.2 and 0.3, respectively, and thus its stoichiometry was (Lu _0.41 Gd _0.2 Tb _0.3 Ce _0.09 ) ₃ Al ₅ O ₁₂ . The compound having the designation TG1 emits at a peak emission wavelength (555.4 nm vs. 555.8 nm, respectively) which is almost as high as (Lu _0.41 Tb _0.5 Ce _0.09 ) ₃ Al ₅ O ₁₂ , but its photoluminescence intensity is not as good as Tb alone. The two compounds without Gd are high. The latter two compounds (Lu _0.61 Tb _0.3 Ce _0.09 ) ₃ Al ₅ O ₁₂ and (Lu _0.41 Tb _0.5 Ce _0.09 ) ₃ Al ₅ O ₁₂ show a color smaller than (Lu _0.41 Gd _0.2 Tb _0.3 Ce _0.09 ) ₃ Al ₅ O ₁₂ Degree coordinate CIE x and larger CIE y chromaticity coordinates.

The data for the compound named G1 (Lu _0.71 Gd _0.2 Ce _0.09 ) ₃ Al ₅ O ₁₂ is shown in the fourth populated row of Table 4. This compound emits light having a peak wavelength of about 550 nm, which is the shortest wavelength of the group of compounds listed in Table 4 except for YAG1. It also shows the lowest chromaticity coordinate CIE x in the group. The CIE y coordinates of this compound are highest in this group. A similar compound named G3 containing Gd and having no Tb but a higher Gd content has an emission peak wavelength of the highest light in the group. This compound has the formula (Lu _0.41 Gd _0.5 Ce _0.09 ) ₃ Al ₅ O ₁₂ . Comparison of (Lu _0.41 Gd _0.5 Ce _0.09 ) ₃ Al ₅ O ₁₂ with the previously discussed (Lu _0.41 Tb _0.5 Ce _0.09 ) ₃ Al ₅ O ₁₂ compound shows that the Gd-containing compound emits longer than the wavelength of the Tb-containing compound, but contains The Tb compound emits at a higher photoluminescence intensity.

The two compositions labeled "YAG1" and "YAG2" in Table 4 are dominated by yttrium (Y) rather than lanthanum (Lu), including such Y-based compositions for comparison. They each have the appropriate formula (Y _0.91 Ce _0.09 ) ₃ Al ₅ O ₁₂ . These compounds are also emitted in the range of 550 nm to 560 nm.

The data in Table 4 can be shown graphically as shown in Figures 18-20, and the Figures 18-20 also show the phosphor composition used to excite the phosphor composition of the present invention (blue light source and yellow light source providing a "white light" source) A blue light source (such as a GaN LED). Figure 18 shows the photoluminescence intensity of two compounds labeled "G1" and "T1". The former has a Gd concentration of x = 0.2 so that the formula is (Lu _0.71 Gd _0.2 Ce _0.09 ) ₃ Al ₅ O ₁₂ . The peak emission wavelength is about 550 nm. Here, the Gd-containing compound (x = 0.2, upper curve) has a photoluminescence intensity and a peak emission wavelength which are almost identical to the sample of the mark "T1" (lower curve).

The two compounds in Fig. 19 have substantially the same photoluminescence intensity as the compound of Fig. 18, but the peak emission wavelength in Fig. 19 is slightly shifted to a longer wavelength. The upper graph in Fig. 19 is "T2", and it has a Tb concentration of x = 0.5 to have a composition of (Lu _0.41 Tb _0.5 Ce _0.09 ) ₃ Al ₅ O ₁₂ . The lower graph in Fig. 19 is the sample "G2", and it has a Gd concentration of x = 0.3 to have a composition of (Lu _0.61 Gd _0.3 Ce _0.09 ) ₃ Al ₅ O ₁₂ . When the two compounds were compared, it was observed that the Tb-containing compound (x = 0.5) had a slightly higher photoluminescence intensity and a very short peak emission wavelength than the "G2" compound.

A compound having an emission wavelength slightly longer than that of Figs. 19 and 18 is shown in Fig. 20. Referring to Fig. 20, the upper curve in the graph corresponds to the sample of the mark "TG1" in which the Gd concentration is 0.2 and the Tb concentration is 0.3, so that the phosphor has the formula (Lu _0.41 Gd _0.2 Tb _0.3 Ce _0.09 ) ₃ Al ₅ O ₁₂ . The lower curve in the graph corresponds to the sample labeled "G3" with a Gd concentration of 0.5. This compound does not contain Tb and is therefore of the formula (Lu _0.41 Gd _0.5 Ce _0.09 ) ₃ Al ₅ O ₁₂ . Here, the compound containing both Gd and Tb exhibits a photoluminescence intensity higher than that of a compound containing an equivalent amount of rare earth (x=0.5) only in Gd form; the compound containing Tb and Gd emits slightly shorter than only The wavelength of the compound of Gd.

The effect of changing the Gd concentration or the Tb concentration in the compound having the general formula (Lu _0.91-x A _x Ce _0.09 ) ₃ Al ₅ O ₁₂ is shown in Fig. 21. (In this experiment, A is Gd or Tb, but it is emphasized that Gd and Tb may exist individually or in combination according to an embodiment of the present invention). Referring to Figure 21, one skilled in the art can observe that increasing the Gd concentration from x = 0 to x = 0.5 causes the peak emission wavelength to increase from a peak of the Tb concentration from about x = 0 to about x = 1.0. The emission wavelength increases faster. In other words, in order to increase the emission wavelength from about 542 nm (wherein the phosphor contains only Lu at x = 0) to about 562 nm, it is necessary to completely replace all Lu with Tb (for Tb, x = 1), and this wavelength increase is This value is achieved by half the Gd concentration (x = 0.5, so that only half of the Lu in the Gd series is replaced).

Photoluminescence intensity and peak of Gb-containing compounds for Tb-containing compounds The relationship between the emission wavelengths is shown in Figure 22. In this graph, the relative photoluminescence intensity on the ordinate (y-axis) is plotted for the peak emission wavelength (in nm, on the x-axis). For the two series of compounds, the relative photoluminescence intensity decreases as the concentration of Gd or Tb increases (and at the same time increases with the peak emission wavelength), and the photoluminescence intensity decreases in the Gd-containing sample more than in the Tb-containing sample. fast.

The specific data used to construct the curves in Figs. 21 and 22 are provided in Table 5 above and Table 6 above.

The thermal stability of Tb containing and exemplary compounds containing Tb and Gd is shown in Figure 23. Gd-containing phosphor compounds containing Gd but no Tb are also shown for comparison. Referring to Figure 23, the CIE y chromaticity coordinates on the y-axis are plotted for CIE x chromaticity coordinates on the x-axis. Data points were collected at 20 degree temperature intervals from 20 ° C to 220 ° C, including the temperature range of the operating temperature of the phosphor material for most applications. The data is shown in Table 7(i) and Table 7(ii). A CIE coordinate shift of less than 0.005 is preferred over the temperature range tested, and it is worth noting that the material containing only Tb exhibits a CIE coordinate shift for the x and y coordinates within this range. Specifically, only T1, T2, and TG1 exhibited better temperature stability. The preferred temperature stability of the ruthenium containing phosphor material is an unexpected result compared to a ruthenium-free and ruthenium-free phosphor material.

It should be noted that the principles, embodiments, and concepts discussed in the present invention are applicable to this portion of 鋱(Tb) and 釓(Gd). For example, in one embodiment of the present invention, the phosphor may comprise a yttrium _- activated aluminate-based yellow-green having the formula (Lu _1-xy A _x Ce _y ) ₃ B _z Al ₅ O ₁₂ C _2z a yellow-emitting phosphor; wherein at least one of A, Sc, La, Gd, and Tb; B is at least one of Mg, Sr, Ca, and Ba; and at least one of C, F, Cl, Br, and I 0.001 x 1.0;0.001 y 0.2; and 0 z 0.5, and the phosphor in this embodiment contains at least some Tb.

In another embodiment of the present invention, the phosphor comprises a yttrium-activated aluminate-based yellow-green to yellow luminescent phosphor having the formula (Lu _1-x A _x ) ₃ Al ₅ O ₁₂ :Ce. Wherein A is at least one rare earth selected from the group consisting of Gd and Tb in individual or combined form; x is in the range of from about 0.001 to about 1.0; and the phosphor contains at least some Tb.

In another embodiment of the present invention, the phosphor comprises a yttrium-activated aluminate-based yellow-green to yellow luminescent phosphor represented by the formula (Lu _0.91-x A _x Ce _0.09 ) ₃ Al ₅ O ₁₂ . Here, A is at least one rare earth selected from the group consisting of Gd and Tb; and x is in the range of from about 0.001 to about 1.0. As with the embodiments discussed in the previous paragraph, the phosphor also contains at least some Tb.

Although the invention has been specifically described with reference to an aluminate-based yellow-green to yellow luminescent phosphor, the teachings and principles of the present invention are also applicable to phosphors in which Al is completely or partially replaced by Ga, Si or Ge, for example Phosphorus based on citrate, gallate and citrate.

Embodiments of the halogen-containing phosphor material may have the following halogens: (1) contained in the crystal in a substituted manner; (2) contained in the interstices of the crystal; and/or (3) contained in the separated crystal grains, crystalline regions, and / or within the grain boundary of the crystal phase.

In accordance with other embodiments of the invention, the Lu aluminate materials of Table 8 were fabricated and tested as described above. An example of a representative procedure for making a compound having the formula (Lu _1-y Ce _y ) ₃ Al ₅ O ₁₂ is provided. Lu ₂ O ₃ (272.664 g), CeO ₂ (7.295 g), Al ₂ O ₃ (120.041 g), and a flux (20.000 g) were mixed using a mixer for 4 hours to 20 hours and then added to the crucible. The crucible is placed in a continuous furnace and sintered between 1500 ° C and 1700 ° C for 2 hours to 10 hours under a reducing atmosphere. The sintered material is converted into a powder using a crusher. The powder is washed with acid and deionized water and then dried in an oven at 120 ° C and 180 ° C for 12 hours to 24 hours. Finally, the powder was sieved through a 20 μm mesh to provide Lu _2.945 Ce _0.055 Al ₅ O ₁₂ and characterized (ie, emission wavelength, intensity and CIE value, particle size distribution, etc.).

According to other aspects of the present invention, a white light illumination system can include: an excitation source having an emission wavelength in the range of 200 nm to 480 nm; at least one of a red-emitting phosphor or a green-emitting phosphor; and A yellow-green to yellow luminescent phosphor based on yttrium aluminate, wherein the phosphor is configured to emit light having a peak emission wavelength in the range of from about 550 nm to about 565 nm. (See also examples of specific compounds that satisfy this requirement above and examples that further satisfy the following requirements). In addition, the yttrium-activated yellow-green to yellow luminescent phosphor based on yttrium alumina can be configured to absorb excitation radiation having a wavelength in the range of from about 380 nm to about 480 nm. Further, the red-emitting phosphor may have an emission wavelength in the range of 600 nm to 660 nm. Further, the green-emitting phosphor may have an emission wavelength in the range of 500 nm to 545 nm. Further, the red-emitting phosphor may be a nitride. Further, the nitride may be at least one of (Ca, Sr)AlSiN ₃ :Eu ²⁺ , (Ca,Sr) ₂ N ₅ N ₈ :Eu ²⁺ and (Ca,Sr)AlSi ₄ N ₇ :Eu ²⁺ By. Further, the green-emitting phosphor may be a citrate. Further, the citrate may have the formula (Sr, Ba, Mg) ₂ SiO ₄ :Eu ²⁺ .

While the invention has been particularly shown and described with reference to the embodiments of the present invention, it will be understood that various modifications and changes in the form and details may be made without departing from the spirit and scope of the invention.

Claims (22)

A yttrium-activated yellow-green to yellow luminescent phosphor based on yttrium aluminate having the formula (Lu _1-x Tb _x ) ₃ Al ₅ O ₁₂ :Ce, wherein x is in the range of about 0.1 to less than 1.0, And wherein the phosphor is configured to absorb excitation radiation having a wavelength in the range of from about 380 nm to about 480 nm, and to emit light having a peak emission wavelength in the range of from about 550 nm to about 565 nm. A yellow-green to yellow-emitting phosphor mainly comprising barium aluminate as claimed in claim 1, wherein x is in the range of from about 0.3 to less than 1.0. A yellow-green to yellow-emitting phosphor mainly comprising barium aluminate as claimed in claim 1, wherein the wavelength of the excitation radiation is in the range of from about 420 nm to about 480 nm. A yellow-green to yellow-emitting phosphor mainly comprising barium aluminate as claimed in claim 1, wherein the formula is (Lu _0.91-x Tb _x Ce _0.09 ) ₃ Al ₅ O ₁₂ . A yellow-green to yellow-emitting phosphor mainly comprising yttrium aluminate as claimed in claim 3, wherein x is in the range of from about 0.3 to less than 0.5 and comprises an endpoint. The yellow-green to yellow luminescent phosphor mainly comprising yttrium aluminate according to claim 1 further comprising a rare earth element lanthanum (Gd). A yellow-green to yellow luminescent phosphor mainly comprising yttrium aluminate according to claim 6, wherein the formula is (Lu _1-xy Tb _x Gd _y ) ₃ Al ₅ O ₁₂ :Ce, and wherein x is from about 0.1 to less than In the range of 1.0, y is greater than 0, and x+y<1. The yellow-green to yellow luminescent phosphor based on yttrium aluminate of claim 6 wherein the formula is (Lu _0.91-xy Tb _x Gd _y Ce _0.09 ) ₃ Al ₅ O ₁₂ , and wherein y is greater than 0, and x +y<1. A yellow-green to yellow luminescent phosphor based on yttrium aluminate of claim 8 wherein x = 0.3 and y = 0.2. A yellow-green to yellow-emitting phosphor mainly comprising barium aluminate as claimed in claim 1, which further comprises a halogen. A yellow-green to yellow-emitting phosphor mainly comprising barium aluminate as claimed in claim 10, wherein the halogen is contained in the crystal in a substituted manner. A yellow-green to yellow-emitting phosphor mainly comprising barium aluminate as claimed in claim 10, wherein the halogen is contained in the intercrystalline space. A yttrium-activated yellow-green to yellow luminescent phosphor based on yttrium aluminate having the formula (Lu _1-x Tb _x ) ₃ A _z Al ₅ O ₁₂ C _2z :Ce, and wherein: A is Mg, At least one of Sr, Ca, and Ba; at least one of B, F, Cl, Br, and I; 0.001 x<1.0; and 0<z 0.5. A yellow-green to yellow luminescent phosphor mainly comprising yttrium aluminate according to claim 13 further comprising a rare earth element lanthanum (Gd). A white light illumination system comprising: an excitation source having an emission wavelength in a range of 200 nm to 480 nm; at least one of a red-emitting phosphor or a green-emitting phosphor; and a strontium aluminate containing strontium activated by strontium A primary yellow-green to yellow luminescent phosphor, wherein the phosphor is configured to emit light having a peak emission wavelength in the range of from about 550 nm to about 565 nm. The white light illumination system of claim 15, wherein the strontium-activated yellow-green to yellow luminescent phosphor based on yttrium aluminate is configured to absorb excitation radiation having a wavelength in the range of from about 380 nm to about 480 nm. A white light illumination system as claimed in claim 15 wherein the red-emitting phosphor has an emission wavelength in the range of from 600 nm to 660 nm. The white light illumination system of claim 15, wherein the green-emitting phosphor has an emission wavelength in the range of 500 nm to 545 nm. A white light illumination system according to claim 15 wherein the red-emitting phosphor is a nitride. A white light illumination system according to claim 19, wherein the nitride system (Ca, Sr)AlSiN ₃ :Eu ²⁺ , (Ca,Sr) ₂ N ₅ N ₈ :Eu ²⁺ and (Ca,Sr)AlSi ₄ N ₇ : at least one of Eu ²⁺ . A white light illumination system according to claim 15 wherein the green light phosphor is a niobate. A white light illumination system according to claim 21, wherein the silicate has the formula (Sr, Ba, Mg) ₂ SiO ₄ :Eu ²⁺ .