WO2023120038A1

WO2023120038A1 - Phosphor

Info

Publication number: WO2023120038A1
Application number: PCT/JP2022/043640
Authority: WO
Inventors: 良々歌中嶋; 広樹坂野
Original assignee: デンカ株式会社
Priority date: 2021-12-21
Filing date: 2022-11-25
Publication date: 2023-06-29
Also published as: TW202332753A

Abstract

One aspect of the present disclosure provides a phosphor wherein the main crystal phase has the same structure as an Li2MgGeO4 crystal phase, the phosphor includes tetravalent chromium as an activation element, and in a diffuse absorption spectrum, when X is the integrated value of the diffuse absorption spectrum over wavelengths of 330-430 nm and Y is the integrated value of the diffuse absorption spectrum over wavelengths of 600-800 nm, the value of Y/X is 3.8 or greater.

Description

Phosphor

The present disclosure relates to phosphors.

Light-emitting devices having light-emitting elements such as light-emitting diodes are used for general lighting, backlights for liquid crystal displays, LED displays, and light-emitting devices for quality inspection. An LED display uses, for example, a light-emitting element that emits blue light and a wavelength converter that absorbs primary light from the light-emitting element and emits light of a different wavelength. Various phosphors such as a red phosphor and a green phosphor are used as the wavelength converter.

Since near-infrared light can also be used as a heat source, studies are underway on phosphors that emit light in the near-infrared region. As a phosphor that emits light in the near-infrared region, a phosphor having chromium as a luminescence center is proposed as a candidate. For example, in Patent Document 1, in a chemical composition of 1 mol, the molar ratio of the total of Gd and Cr is 1, and the molar ratio of Cr is 0.0085 or more and 0.05 or less, Gd, Cr, and Al and is excited by light having an emission peak wavelength in the range of 380 nm or more and 480 nm or less, and having an emission peak wavelength in the range of 690 nm or more and 790 nm or less.

Further, Patent Document 2 discloses a light-emitting device comprising a light-emitting source and a phosphor, wherein the phosphor contains at least a near-infrared light-emitting phosphor that emits near-infrared light when excited. It is

JP 2020-041135 A JP 2020-188044 A

A phosphor that emits near-infrared light and has excellent emission intensity is useful.

An object of the present disclosure is to provide a phosphor with excellent emission intensity.

The present disclosure provides the following [1] to [7].

[1] the main crystal phase has the same structure as _the _Li2MgGeO4 crystal phase,
Containing tetravalent chromium as an activating element,
In the diffuse absorption spectrum, the value of Y/X is 3.8 or more, where X is the integrated value of the diffuse absorption spectrum with a wavelength of 330 to 430 nm and Y is the integrated value of the diffuse absorption spectrum with a wavelength of 600 to 800 nm. There is phosphor.
[2] the main crystal phase is represented by the general formula: A ₂ B(C _1-x Cr _x )O ₄ (wherein A, B and C represent mutually different metal elements);
The phosphor according to [1], wherein the Cr content is 8 mol % or less based on the total amount of C and Cr.
[3] The phosphor according to [2], wherein the Cr content is 6 mol % or less.
[4] The phosphor according to [2] or [3], wherein A in the general formula contains Li, and the content of Li in A is 90 mol % or more.
[5] The phosphor according to any one of [2] to [4], wherein B in the general formula contains Mg, and the content of Mg in B is 90 mol % or more.
[6] The phosphor according to any one of [2] to [5], wherein C in the general formula contains Ge, and the content of Ge in C is 90 mol % or more.
[7] In the powder X-ray diffraction pattern, α is the maximum value of the peak intensity in the region where the diffraction angle (2θ) is 17.0 to 19.5 °, and the diffraction angle is 20.5 to 23.5 ° The phosphor according to any one of [1] to [6], wherein the value of α/β is 0.047 or less, where β is the maximum value of peak intensity in the region.

One aspect of the present disclosure is that the main crystalline phase has the same structure as the Li ₂ MgGeO ₄ crystalline phase, contains tetravalent chromium as an activating element, and has a diffuse absorption spectrum with a wavelength of 330 to 430 nm. Provided is a phosphor having a Y/X value of 3.8 or more, where X is the integrated value and Y is the integrated value of a diffuse absorption spectrum with a wavelength of 600 to 800 nm.

The phosphor can exhibit excellent emission intensity by having the ratio of the integrated intensity of the specific wavelength region in the diffuse absorption spectrum within a predetermined range. In the diffuse absorption spectrum, the peak observed in the wavelength range of 330 to 430 nm corresponds to the absorption of hexavalent chromium, and the peak observed in the wavelength range of 600 to 800 nm corresponds to the absorption of tetravalent chromium. When the value of Y/X is equal to or greater than a predetermined value, it means that the proportion of tetravalent chromium in the phosphor is high.

The main crystal phase is represented by the general formula: A ₂ B(C _1-x Cr _x ) O ₄ (wherein A, B, and C represent different metal elements), and the Cr content is C and Cr, it may be 8 mol % or less (corresponding to x being 0.08 or less in the above general formula), or 6 mol % or less.

A in the above general formula may contain Li, and the content of Li in A may be 90 mol% or more. Further, B in the above general formula may contain Mg, and the content of Mg in B may be 90 mol % or more. Further, C in the above general formula may contain Ge, and the content of Ge in C may be 90 mol % or more.

In the powder X-ray diffraction pattern of the phosphor, the maximum value of the peak intensity in the region where the diffraction angle (2θ) is 17.0 to 19.5 ° is α, and the diffraction angle is 20.5 to 23.5 °. The value of α/β may be 0.047 or less, where β is the maximum value of the peak intensity in the region.

According to the present disclosure, a phosphor with excellent emission intensity can be provided.

FIG. 1 is a diagram showing diffuse absorption spectra of phosphors prepared in Examples. FIG. 2 is a diagram showing powder X-ray diffraction spectra of phosphors prepared in Examples. FIG. 3 is a diagram showing the measurement results of the emission intensity of the phosphors prepared in Examples.

The embodiments of the present disclosure will be described below. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents.

The materials exemplified in this specification can be used singly or in combination of two or more unless otherwise specified. The content of each component in the composition means the total amount of the multiple substances present in the composition unless otherwise specified when there are multiple substances corresponding to each component in the composition. . The “steps” used herein may be independent steps or steps performed simultaneously.

One embodiment of the phosphor has the same _structure as the _Li2MgGeO4 crystal phase in the main crystal phase and contains tetravalent chromium as an activating element. The main crystal phase may be represented by the general formula: A ₂ B(C _1-x Cr _x )O ₄ . In the above general formula, A, B, and C represent metal elements different from each other. In the above general formula, A, B, and C are mainly intended to represent one type of element, respectively, but may be partially substituted to represent two or more types of elements. In the above general formula, A is preferably lithium (Li), B is magnesium (Mg), and C is germanium (Ge), and some of the respective elements are shown below. and a candidate element for C.

In the above general formula, A may be, for example, lithium (Li), sodium (Na), potassium (K), etc., preferably contains Li, more preferably contains 90 mol% or more of Li, and Li is particularly preferred. In the above general formula, B may be, for example, magnesium (Mg), zinc (Zn), and calcium (Ca), preferably containing Mg, more preferably containing 90 mol% or more of Mg, is particularly preferred. In the above general formula, C may be, for example, germanium (Ge), silicon (Si), tin (Sn), etc., preferably contains Ge, more preferably contains 90 mol% or more of Ge, and Ge is particularly preferred. The notation (C _1-x Cr _x ) in the above general formula means that both C and Cr are included, and that Cr is included in a form substituting part of the C site. In the phosphor, more specifically, when C is Ge, chromium (Cr) may be introduced into germanium (Ge) sites. In this case, the phosphor may be represented by, for example, the general formula: Li ₂ Mg(Ge _1-x Cr _x )O ₄ , where x is, for example, greater than 0 and 0.1 or less, 0.005 may be ~0.1, 0.005-0.08, 0.005-0.06, 0.005-0.03, or 0.005-0.02. In the above phosphor, the main crystal phase has the same crystal structure as the _Li2MgGeO4 crystal phase, but _its space group may be, for example, _Pmn21 .

In the present specification, the main crystalline phase means the phase with the largest proportion of the produced phase calculated by the powder X-ray diffraction method. The phosphor may contain, in addition to the main crystal phase, a heterophase within the scope of the present disclosure. Heterogeneous phases include, for example, phases having the same crystal composition but different space groups (for example, a crystal structure whose space group is Pnma), or phases having different crystal compositions (for example, MgCr ₂ O ₄ and the like).

The crystal structure of the phosphor can be confirmed by the powder X-ray diffraction method. In addition, the content of lithium (Li), magnesium (Mg), germanium (Ge), and chromium (Cr) in the composition of the phosphor was determined by subjecting the object to be measured to acid decomposition under pressure to prepare a sample solution. can be determined by quantitative analysis using an ICP emission spectrometer. The oxygen (O) content can be estimated based on the charge balance from the elemental content of the ICP. Since the elemental composition in the phosphor corresponds to the ratio of each element charged when the phosphor is produced, the elemental composition of the phosphor can also be estimated from the raw material composition.

The content of chromium in the main crystal phase can be adjusted according to the emission characteristics required for the phosphor. When the main crystal phase is represented by the general formula: A ₂ B(C _1-x Cr _x ) O ₄ (wherein A, B, and C represent mutually different metal elements), the Cr content is , based on the total amount of C and Cr, for example, 10 mol% or less, 8 mol% or less (corresponding to x being 0.08 or less in the above general formula), 7 mol% or less, 6 mol% or less, 5 mol% or less, It may be 2 mol % or less, or 1.5 mol % or less. When the chromium content is increased, a heterophase may occur during the manufacturing process. Therefore, if the upper limit of the chromium content is within the above range, the ratio of the heterophase is reduced, and the resulting phosphor optical Properties can be improved. When the main crystal phase is represented by the general formula A ₂ B(C _1-x Cr _x )O ₄ (A, B, and C represent different metal elements), the Cr content is Based on the total amount, it may be, for example, 0.3 mol % or more, 0.5 mol % or more, or 0.7 mol % or more. Of the chromium dissolved in the main crystal phase, tetravalent Cr (Cr ⁴⁺ ) is an element that becomes the center of light emission, and the lower limit of the chromium content is within the above range. The amount can be improved, and the emission intensity of the obtained phosphor can be improved more fully. The content of chromium in the main crystal phase may be adjusted within the range described above, and the main crystal phase has the general formula: A ₂ B(C _1-x Cr _x )O ₄ (in the general formula, A, B, C represents a metal element different from each other), the content of Cr is, for example, 0.3 to 10 mol%, or 0.5 to 1.5 mol%, based on the total amount of C and Cr. It's okay.

In the diffuse absorption spectrum of the phosphor, the integrated value of the diffuse absorption spectrum with a wavelength of 330 to 430 nm is X, and the integrated value of the diffuse absorption spectrum with a wavelength of 600 to 800 nm is Y. The value of Y / X is 3.8 or more.

The lower limit of the value of Y/X may be, for example, 3.9 or more, 4.0 or more, or 4.5 or more. When the lower limit of the value of Y/X is within the above range, the ratio of tetravalent chromium (Cr ⁴⁺ ) is higher, and the emission intensity can be further improved. The upper limit of the Y/X value is, for example, 8.0 or less, 7.5 or less, 7.0 or less, 6.5 or less, 6.0 or less, 5.5 or less, 5.3 or less, or 5 .0 or less. A large Y/X value means that the ratio of tetravalent chromium is high. The incidence rate of Therefore, by setting the upper limit of the value of Y/X within the above range, it is possible to suppress an increase in the proportion of heterogeneous phases during the manufacturing process, and to obtain a phosphor with better optical properties. The value of Y/X may be adjusted within the ranges described above, and may be, for example, 3.8 to 8.0, or 4.5 to 5.3.

The integrated values X and Y of the peaks of the diffuse absorption spectrum in this specification are the pseudo absorption spectrum calculated from the diffuse spectrum measured using an ultraviolet-visible spectrophotometer for the phosphor, that is, the diffuse absorption spectrum. value. The diffuse absorption spectrum is specifically measured and obtained by the operation described in the examples of this specification. As the ultraviolet-visible spectrophotometer, for example, "V-550" (product name) manufactured by JASCO Corporation can be used.

It is desirable that the hetero-phase content in the phosphor is low. Of the different phases, MgCr ₂ O ₄ is generally black and can absorb the excitation light applied to the phosphor and emitted fluorescence, so it is particularly desirable to reduce it. MgCr ₂ O ₄ shows a peak in the region where the diffraction angle (2θ) is 17.0 to 19.5° in the powder X-ray diffraction pattern, and Li ₂ MgGeO ₄ shows a diffraction angle has a peak in the region of 20.5 to 23.5°. Therefore, in the powder X-ray diffraction pattern of the phosphor, the maximum value of the peak intensity in the region where the diffraction angle (2θ) is 17.0 to 19.5° is α, and the diffraction angle is 20.5 to 23.5°. The value of α/β, where β is the maximum value of the peak intensity in the 5° region, can be adjusted to be low. The upper limit of the α/β value may be, for example, 0.047 or less, 0.045 or less, 0.040 or less, 0.038 or less, or 0.035 or less. By setting the upper limit of the α/β value within the above range, the emission intensity of the phosphor can be further improved. The lower limit of the value of α/β is not particularly limited, and may be 0 (meaning that MgCr ₂ O ₄ is not included). or more, or 0.032 or more. When the lower limit of the α/β value is within the above range, more excellent emission intensity can be expected. The value of α/β may be adjusted within the ranges described above, and may be, for example, 0.020-0.047, 0.032-0.038, or 0.030-0.035.

The maximum values α and β of peak intensity in this specification mean values determined by powder X-ray diffraction analysis for the phosphor. The powder X-ray diffraction pattern is specifically measured and determined by the procedure described in the Examples of this specification.

The above phosphors may be used alone or in combination with other phosphors. Since the phosphor according to the present disclosure has excellent emission intensity, it can be suitably used for light emitting devices such as LEDs, display devices, and the like. For example, the phosphor may be dispersed in a cured resin and used. The cured resin in this case is not particularly limited, and for example, a resin used as a sealing resin for light emitting devices or the like can be used.

An example of a light-emitting device is a light-emitting device that includes a light-emitting element that emits primary light, and a wavelength converter that absorbs part of the primary light and emits secondary light having a longer wavelength than the primary light. be. The wavelength converting body includes the above phosphor according to the present disclosure. A light-emitting element that emits primary light may be, for example, an InGaN blue LED or the like. The light emitting element and the wavelength converter may be dispersed in a sealing resin or the like.

The phosphor described above can be produced, for example, by the following method. An example of a method for producing a phosphor is a compound containing lithium as a constituent element, a compound having magnesium as a constituent element, a compound having germanium as a constituent element, and a compound having chromium as a constituent element. a step of obtaining a fired product (hereinafter also referred to as a firing step); and a step of reducing at least part of chromium in the fired product by heat-treating the fired product in a reducing atmosphere containing ammonia. (hereinafter also referred to as a reduction step).

The composition contains a compound that serves as a source of constituent elements of the phosphor, and includes a compound having lithium as a constituent element, a compound having magnesium as a constituent element, a compound having germanium as a constituent element, and chromium as a constituent element. Contains compounds.

Compounds containing lithium (Li) as a constituent element may be, for example, carbonates, oxides, fluorides, oxyfluorides, chlorides, nitrides, metals, and the like. Among the above compounds, it is preferable to contain a carbonate from the viewpoint of the stability of the raw material and promotion of the reaction. The compound containing lithium (Li) as a constituent element may be lithium carbonate.

Compounds having magnesium (Mg) as a constituent element may be, for example, oxides, fluorides, oxyfluorides, chlorides, nitrides, and metals. Among the above compounds, oxides are preferably contained from the viewpoint of stability of raw materials and reaction promotion. A compound containing magnesium (Mg) as a constituent element may be magnesium oxide.

Compounds containing germanium (Ge) as a constituent element may be, for example, oxides, fluorides, oxyfluorides, chlorides, nitrides, and metals. Among the above compounds, oxides are preferably contained from the viewpoint of stability of raw materials and reaction promotion. A compound containing germanium (Ge) as a constituent element may be germanium oxide.

Compounds containing chromium (Cr) as a constituent element may be, for example, oxides, fluorides, oxyfluorides, chlorides, nitrides, and metals. Among the above compounds, oxides are preferably contained from the viewpoint of stability of raw materials and reaction promotion. The compound containing chromium (Cr) as a constituent element may be chromium oxide.

The content of chromium is 8 mol% or less with respect to the total amount of germanium and chromium in the composition. The chromium content is, for example, 0.3 to 8 mol%, 0.5 to 5 mol%, 0.5 to 2 mol%, or 0.7 to 1 mol% relative to the total amount of germanium and chromium in the composition. .5 mol %. When the upper limit of the content of chromium is within the above range, it is possible to suppress the generation of heterogeneous phases and improve the optical properties of the resulting phosphor. Moreover, since the lower limit of the content of chromium is within the above range, the abundance of tetravalent chromium can be increased, and the emission intensity of the resulting phosphor can be sufficiently improved.

The above composition may contain other components in addition to the compound having lithium as a constituent element, the compound having magnesium as a constituent element, the compound having germanium as a constituent element, and the compound having chromium as a constituent element. Other components include, for example, a compound having sodium (Na) as a constituent element, a compound having zinc (Zn) as a constituent element, a compound having calcium (Ca) as a constituent element, and a compound having strontium (Sr) as a constituent element. Compounds, compounds containing silicon (Si) as a constituent element, and the like.

The above composition can be prepared by weighing and mixing each compound. Dry mixing or wet mixing may be used for mixing. The dry mixing method may be, for example, a method of mixing each component using a V-type mixer or the like. The wet mixing method may be, for example, a method of adding a solvent such as water or a dispersion medium to prepare a solution or slurry, mixing the components, and then removing the solvent or dispersion medium.

The heating temperature (firing temperature) in the firing step may be, for example, 800-1600°C, 900-1500°C, 1000-1400°C, or 1100-1300°C. Reaction can be accelerated because the lower limit of the heating temperature is within the above range. Moreover, volatilization of a raw material component can be suppressed because the upper limit of the heating temperature is within the above range.

The heating time (firing time) in the firing step may be, for example, 3 to 11 hours, 4 to 10 hours, 5 to 9 hours, or 6 to 8 hours. When the lower limit of the heating time is within the above range, the reaction can be promoted. When the upper limit of the heating time is within the above range, volatilization of raw material components can be suppressed.

Note that the firing time, heating time, and the like in this specification mean the time (holding time) for maintaining the temperature after the temperature of the surrounding environment of the object reaches a predetermined temperature. The rate of temperature increase when the temperature is increased to a predetermined temperature and the rate of temperature decrease when the temperature is decreased to room temperature can be adjusted as appropriate. The rate of temperature increase in the firing step may be, for example, 2 to 15°C/min, 5 to 12°C/min, or 8 to 10°C/min. The temperature drop rate in the firing step may be, for example, 2 to 15°C/min, 5 to 12°C/min, or 8 to 10°C/min.

　The firing process is carried out in the atmosphere.

The number of times of heat treatment in the firing step may be one time, but may be, for example, two times or more, and may be two to five times, or two to four times.

In the firing process, when the heat treatment is performed multiple times, it is called the first heat treatment, the second heat treatment, etc., and the steps of performing each heat treatment are sequentially called the first heat treatment, the second heat treatment, etc. you can When two or more heat treatments are performed in the firing step, the heating temperature, heating time, atmosphere during heating, and pressure during heating in the first firing step are the same as the heating temperature, heating time, and heating time in the above-described heating step. atmosphere and pressure during heating can be applied. The heating temperature, heating time, atmosphere during heating, and pressure during heating in and after the second firing step may be the same as or different from those in the first firing step. However, even if the heating temperature, heating time, atmosphere during heating, and pressure during heating in the second and subsequent firing steps are different from those in the first firing step, within the conditions shown for the above heating step. Assume that there is

In the reduction process, the fired product prepared in the firing process described above is heat-treated in a reducing atmosphere. By performing the reduction treatment, at least part of the chromium whose valence increased during the process of obtaining the fired product can be reduced, and the ratio of tetravalent chromium that contributes to light emission can be increased.

The reducing atmosphere in the reduction step may contain, for example, hydrocarbons, carbon monoxide, and hydrogen in addition to ammoniania. Reduction of chromium can be promoted more by setting the reducing atmosphere as described above. From the viewpoint of suppressing the presence of hexavalent chromium due to insufficient reduction of chromium in the reduction step, the reducing atmosphere is preferably an ammonia atmosphere.

The flow rate of the atmosphere in the reduction process is, for example, 0.001 to 2.5 mL/min, 0.1 to 2.0 mL/min, 0.5 to 1.5 mL/min when using a furnace core tube with an inner diameter of 70 mm, Or it may be 0.8-1.2 mL/min.

The heating temperature in the reduction step may be, for example, 300-1100°C, 400-1000°C, 500-900°C, or 600-800°C. When the lower limit of the heating temperature is within the above range, the ratio of pentavalent chromium and hexavalent chromium can be reduced. Further, by setting the upper limit of the heating temperature within the above range, the proportion of trivalent chromium can be reduced.

The heating time in the reduction step may be, for example, 2-11 hours, 3-10 hours, 4-9 hours, or 6-7 hours. When the lower limit of the heating time is within the above range, the proportions of pentavalent chromium and hexavalent chromium can be reduced. Further, by setting the upper limit of the heating time within the above range, the proportion of trivalent chromium can be reduced.

The rate of temperature increase in the reduction step may be, for example, 2-15°C/min, 5-12°C/min, or 8-10°C/min. The temperature drop rate in the reduction step may be, for example, 2 to 15°C/min, 5 to 12°C/min, or 8 to 10°C/min.

The manufacturing method described above may have other steps in addition to the firing step and the reduction step. Other steps include, for example, a pulverization step, a classification step, an acid treatment step, and the like.

The pulverization step may be, for example, a step of pulverizing the fired product obtained in the firing step or the heat-treated product obtained in the reduction step. For example, by pulverizing the fired product obtained in the firing step before sending it to the reduction step to adjust the particle size, the surface area of the fired product can be increased and the efficiency of reduction in the subsequent reduction step can be improved. . Further, by pulverizing the heat-treated material obtained in the reduction step, the particle size of the phosphor can be adjusted according to the application.

A general crusher or crusher can be used in the crushing process. For example, a mortar, ball mill, vibration mill, jet mill, and the like can be used. In addition, "pulverization" in this specification includes "crushing".

Although several embodiments have been described above, the present disclosure is not limited to the above embodiments. Also, the descriptions of the above-described embodiments can be applied to each other.

Hereinafter, the contents of the present disclosure will be described in more detail with reference to examples and comparative examples. However, the present disclosure is not limited to the following examples.

(Example 1)
<Manufacturing method of phosphor>
Lithium carbonate (Li ₂ CO ₃ , manufactured by Kojundo Chemical Laboratory Co., Ltd.), magnesium oxide (MgO, manufactured by Kanto Chemical Co., Ltd.), germanium oxide (GeO ₂ , manufactured by Kojundo Chemical Laboratory Co., Ltd.), and Chromium oxide (Cr ₂ O ₃ , manufactured by Kojundo Chemical Laboratory Co., Ltd.) was measured so that the molar ratio of Li: Mg: Ge: Cr was 2: 1: 0.995: 0.005, A composition (raw material powder) was obtained by dry mixing.

6.0 g of the above composition was weighed out on an alumina board and placed in a vertical furnace. Next, in the atmosphere, the temperature inside the vertical furnace is raised from room temperature at a rate of 10°C/min until it reaches 1200°C, and after reaching 1200°C, the temperature is maintained for 7 hours. was heat-treated (firing step). Heating was then terminated and the mixture was allowed to cool to room temperature. After cooling to room temperature, the lump was collected from the container. The collected lumps were pulverized and pulverized with an alumina mortar and sieved through a sieve with an opening of 150 μm to obtain a powdery fired product as a sieved product.

Next, 2.5 g of the above-described powdery fired product was weighed out on an alumina board and placed in a tubular furnace. Next, in an ammonia atmosphere, the temperature inside the tubular furnace is raised from room temperature at a heating rate of 10°C/min until it reaches 700°C, and after reaching 700°C, the temperature is maintained for 6 hours. (reduction step). Heating was then terminated and the mixture was allowed to cool to room temperature. After cooling to room temperature, the lump was collected from the vessel. The collected lumps were pulverized and pulverized with an alumina mortar and sieved through a sieve with an opening of 150 μm to obtain a powdery heat-treated product as a sieve product. The heat-treated product was used as the phosphor of Example 1. The obtained phosphor is represented by the general formula: Li ₂ Mg(Ge _1-x Cr _x )O ₄ (x is 0.005), and the main crystal phase has the same structure as the Li ₂ MgGeO ₄ crystal phase. was confirmed.

(Example 2)
A phosphor was prepared in the same manner as in Example 1, except that the mixing ratio in the composition was changed so that the molar ratio of Li:Mg:Ge:Cr was 2:1:0.99:0.01. Obtained.

(Example 3)
A phosphor was prepared in the same manner as in Example 1, except that the mixing ratio in the composition was changed so that the molar ratio of Li:Mg:Ge:Cr was 2:1:0.98:0.02. Obtained.

(Example 4)
A phosphor was prepared in the same manner as in Example 1, except that the mixing ratio in the composition was changed so that the molar ratio of Li:Mg:Ge:Cr was 2:1:0.96:0.04. Obtained.

(Example 5)
A phosphor was prepared in the same manner as in Example 1, except that the mixing ratio in the composition was changed so that the molar ratio of Li:Mg:Ge:Cr was 2:1:0.95:0.05. Obtained.

(Comparative example 1)
A phosphor was prepared in the same manner as in Example 1, except that the mixing ratio in the composition was changed so that the molar ratio of Li:Mg:Ge:Cr was 2:1:0.92:0.08. Obtained.

(Comparative example 2)
A phosphor was prepared in the same manner as in Example 1, except that the mixing ratio in the composition was changed so that the molar ratio of Li:Mg:Ge:Cr was 2:1:0.9:0.1. Obtained.

(Comparative Examples 3-9)
The powdery fired products (products before the reduction step) obtained in Examples 1 to 5 and Comparative Examples 1 to 2 were used as phosphors in Comparative Examples 3 to 9, respectively.

(Comparative Example 10)
The reduction step is performed in a high-temperature atmosphere furnace in an atmosphere of a mixed gas of nitrogen and hydrogen (a mixed gas in which nitrogen and hydrogen are mixed at a volume ratio of 96:4 in a standard state, a non-reducing atmosphere containing hydrogen). A phosphor was obtained in the same manner as in Example 1, except that the procedure was changed to .

<Measurement of Cr content in phosphor>
The phosphors obtained in Examples 1 to 5 and Comparative Examples 1 to 10 were quantitatively analyzed by an ICP emission spectrometer according to the method described later, and based on the total amount of Ge and Cr, Cr content It was determined. Table 1 shows the results.

[ICP emission spectroscopic analysis method]
The composition was analyzed using a multi-type ICP emission spectrometer (Agilent's device, model number: 5110VDV type). 10 mg of phosphor was placed in a platinum crucible, 2 g of an alkaline flux was added, and the mixture was melted in an electric furnace. After standing to cool, 20 mL of hydrochloric acid (HCl) was added to the platinum crucible and dissolved by heating in a hot bath to obtain a solution. The resulting solution was then made up to 100 mL. This 100 mL solution was diluted 10-fold with pure water to prepare a test solution, which was set in the above apparatus and analyzed for its composition.

<Measurement of diffuse absorption spectrum of phosphor>
Diffuse absorption spectra were measured for the phosphors obtained in Examples 1 to 5 and Comparative Examples 1 to 10 according to the method described later. Using the integrated value X of the diffuse absorption spectrum with a wavelength of 330 to 430 nm and the integrated value Y of the diffuse absorption spectrum with a wavelength of 600 to 800 nm obtained by the measurement, the value of Y/X was determined. The results are shown in Table 1 and FIG. In addition, in FIG. 1, only some results were shown for reference.

[Diffuse absorption spectrum measurement method]
Using ABSORBANCE mode of an ultraviolet-visible spectrophotometer (manufactured by JASCO Corporation, product name: V-550), a pseudo absorption spectrum calculated from the diffusion spectrum of the sample packed in a quartz cell was obtained.

<Measurement of powder X-ray diffraction spectrum of phosphor>
The phosphors obtained in Examples 1 to 5 were further subjected to powder X-ray diffraction measurement according to the method described later. The maximum value α of the peak intensity in the region where the diffraction angle (2θ) is 17.0 to 19.5° and the peak intensity in the region where the diffraction angle is 20.5 to 23.5° obtained by the measurement was used to determine the value of α/β. The results are shown in Table 1 and FIG. In addition, in FIG. 2, only a part of result was shown for reference.

[Measurement of powder X-ray diffraction]
An X-ray diffraction pattern of the sample was obtained using an X-ray diffractometer (manufactured by Rigaku Corporation, product name: UltimaIV). CuKα rays (characteristic X-rays) were used for the measurement.

<Evaluation of Phosphor>
The emission intensity of the phosphors obtained in Examples 1 to 5 and Comparative Examples 1 to 10 was measured according to the method described later. The results are shown in Table 1 and FIG. FIG. 3 shows only some of the results for reference. The emission intensity was evaluated as a relative value based on the emission intensity of the phosphor of Example 1.

[Measurement of luminescence intensity]
First, the fluorescent material to be measured was filled in a quartz cell and attached to the opening of the integrating sphere. Monochromatic light with a wavelength of 676 nm from a xenon lamp as a light emission source was introduced into the integrating sphere as excitation light for the phosphor using an optical fiber. The fluorescent substance to be measured was irradiated with the monochromatic light, which is the excitation light, and the fluorescence spectrum was measured. A spectrophotometer (trade name: Fluorolog-3-iHR-NIR, manufactured by HORIBA, Ltd.) was used for the measurement. From the obtained fluorescence spectrum data, the intensity ratio when the emission intensity of Example 1 was set to 1.0 was determined.

According to the present disclosure, it is possible to provide a phosphor with excellent emission intensity.

Claims

the main crystal phase has the same structure as the Li2MgGeO4 crystal phase,
Containing tetravalent chromium as an activating element,
In the diffuse absorption spectrum, the value of Y/X is 3.8 or more, where X is the integrated value of the diffuse absorption spectrum with a wavelength of 330 to 430 nm and Y is the integrated value of the diffuse absorption spectrum with a wavelength of 600 to 800 nm. There is phosphor.
The main crystal phase is represented by the general formula: A 2 B(C 1-x Cr x ) O 4 (wherein A, B, and C represent mutually different metal elements),
2. The phosphor according to claim 1, wherein the Cr content is 8 mol % or less based on the total amount of C and Cr.
The phosphor according to claim 2, wherein the Cr content is 6 mol% or less.
The phosphor according to claim 2 or 3, wherein A in the general formula contains Li, and the content of Li in A is 90 mol% or more.
The phosphor according to claim 2 or 3, wherein B in the general formula contains Mg, and the content of Mg in B is 90 mol% or more.
The phosphor according to claim 2 or 3, wherein C in the general formula contains Ge, and the content of Ge in C is 90 mol% or more.
In the powder X-ray diffraction pattern, the maximum value of the peak intensity in the region where the diffraction angle (2θ) is 17.0 to 19.5 ° is α, and the peak in the region where the diffraction angle is 20.5 to 23.5 ° 3. The phosphor according to claim 1, wherein the value of α/β is 0.047 or less, where β is the maximum intensity.