WO2012043879A1

WO2012043879A1 - Phosphor and method for producing same

Info

Publication number: WO2012043879A1
Application number: PCT/JP2011/073035
Authority: WO
Inventors: 義貴川上; 鉄梅田
Original assignee: 住友化学株式会社
Priority date: 2010-09-30
Filing date: 2011-09-29
Publication date: 2012-04-05
Also published as: TW201229213A; JP2012077126A

Abstract

The present invention provides a method for producing a yellow phosphor, which comprises: a step wherein a first mixture of a metal halide and an Eu-containing compound is fired, thereby producing a solid solution; and a step wherein a second mixture of the solid solution and a metal compound is fired.

Description

Phosphor and method for producing the same

The present invention relates to a method for producing a yellow phosphor and a yellow phosphor.

A white LED is a combination of an LED chip that emits light in the ultraviolet to blue region, that is, light having a wavelength of about 380 to 500 nm, and a phosphor that emits light when excited by the light emitted from the LED chip. Composed. The white LED can realize white of various color temperatures by a combination of the LED chip and the phosphor.

As a phosphor that emits light by being excited by light in the ultraviolet to blue region, that is, a phosphor that can be used for a white LED, for example, in JP-A-10-242513, it is represented by Y ₃ Al ₅ O ₁₂ : Ce ³⁺ . A phosphor represented by Li ₂ SrSiO ₄ : Eu ²⁺ is disclosed in WO 03/80763 pamphlet and JP 2006-237113 A. In Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , Y ₃ Al ₅ O ₁₂ is a host crystal of the phosphor, and Ce ³⁺ is a luminescent ion that activates the host crystal. In Li ₂ SrSiO ₄ : Eu ²⁺ , Li ₂ SrSiO ₄ is a host crystal of the phosphor, and Eu ²⁺ is a luminescent ion that activates the host crystal.

The phosphor represented by Li ₂ SrSiO ₄ : Eu ²⁺ efficiently absorbs blue light emitted from the blue LED chip, shows a broad yellow emission having an emission peak near 570 nm, and was exposed to a high temperature. It is known that it has a characteristic capable of sufficiently maintaining the emission intensity even in a state. In the present specification, yellow light emission means that the peak wavelength has an emission peak in the vicinity of 560 nm to 590 nm.

Further, as a phosphor for white LED, YAG: Ce ^{3+ and the} like are synthesized by firing at a high temperature of about 1500 ° C., whereas Li ₂ SrSiO ₄ : Eu ²⁺ is synthesized at a low temperature of 800 to 900 ° C. It can be synthesized by firing. Therefore, Li ₂ SrSiO ₄ : Eu ²⁺ is advantageous in terms of production cost.

It is known that Eu ions widely used as luminescent ions in phosphors exist stably as Eu ^{3+ in} air. When synthesizing a phosphor containing Eu ions, if firing at a high temperature of, for example, 1000 ° C. or higher in a reducing atmosphere, Eu ³⁺ is reduced to Eu ²⁺ , so that the phosphor contains Eu ²⁺ as the luminescent ions. Is obtained. However, since the phosphor represented by Li ₂ SrSiO ₄ : Eu ²⁺ is synthesized by firing at a low temperature of 800 to 900 ° C., there is a problem that the reduction from Eu ³⁺ to Eu ²⁺ does not proceed sufficiently. It was.

An object of the present invention is to provide a method for producing a yellow phosphor that can be efficiently reduced from Eu ³⁺ to Eu ²⁺ even when the firing temperature is low, and a yellow phosphor.

The present invention provides the following <1> to <17>.
<1> A method for producing a yellow phosphor comprising a step of firing a first mixture of a metal halide and an Eu-containing compound to produce a solid solution, and a step of firing a second mixture of the solid solution and the metal compound.

<2> The method according to <1>, wherein the metal halide is at least one compound selected from the group consisting of alkali metal halides, alkaline earth metal halides, and rare earth halides.

<3> The method according to <2>, wherein the metal halide is an alkali metal halide and / or an alkaline earth metal halide.

<4> The method according to <3>, wherein the metal halide is strontium halide.
<5> The method according to <4>, wherein the strontium halide is strontium chloride.

<6> The metal compound includes (i) a Si compound and / or Ge compound, and (ii) a metal different from at least the metal contained in the metal halide among the alkali metal compound and the alkaline earth metal compound. The method according to any one of <1> to <5>, comprising a compound.

<7> The method according to <6>, wherein the metal compound further comprises (iii) at least one compound selected from the group consisting of a rare earth element compound, a Zn compound, a Bi compound, and a Mn compound.

<8> The molar ratio of the metal element contained in the metal halide to the Eu contained in the Eu-containing compound (metal element contained in the metal halide / Eu contained in the Eu-containing compound) is 0.05 or more, 20 The method according to any one of <1> to <7>, which is as follows.

<9> A yellow phosphor produced by the method according to any one of <1> to <8>.

<10> A yellow phosphor represented by the formula M ¹ _2a (M ² _b L _c ) M ³ _d O ₄ .
In the formula, M ¹ is at least one element selected from the group consisting of alkali metals,
M ² is at least one element selected from the group consisting of alkaline earth metals and Zn,
M ³ is at least one element selected from the group consisting of Si and Ge;
L is at least one element selected from the group consisting of rare earth elements, Bi and Mn, and L includes at least Eu,
Of the Eu, the ratio of divalent Eu is 25 mol% or more and 100 mol% or less,
a is 0.9 or more and 1.1 or less,
b is 0.8 or more and 1.2 or less,
c is 0.005 or more and 0.2 or less,
d is 0.8 or more and 1.2 or less.

<11> The yellow phosphor according to <10>, wherein M ¹ is Li and M ³ is Si.

<12> a yellow phosphor according to <10> or <11>, wherein a is 0.9 or more and 1.1 or less.

<13> The yellow phosphor according to any one of <10> to <12>, wherein b, c, and d satisfy a relationship of b + c = 1 and d = 1. .

<14> Any one of <10> to <13>, wherein M ² is Ca, Ba, Mg, or Zn, or at least two elements selected from the group consisting of Ca, Sr, Ba, Mg, and Zn The yellow phosphor according to crab.

<15> The yellow phosphor according to any one of <10> to <14>, wherein the crystal system of the yellow phosphor is hexagonal.

<16> A light emitting device using the yellow phosphor according to any one of <10> to <15>.

<17> A white LED using the yellow phosphor according to any one of <10> to <15>.

<Method for producing yellow phosphor>
The method for producing a yellow phosphor according to the present invention includes a step of firing a first mixture of a metal halide and an Eu-containing compound serving as an Eu source to obtain a solid solution, and firing a second mixture of the solid solution and the metal compound. The process of carrying out. In the conventional method, the phosphor is produced by mixing the weighed raw material compounds and firing the obtained mixture so that the target phosphor has a desired composition. On the other hand, in the method of the present invention, first, a first mixture of a metal halide and an Eu-containing compound is fired to obtain a solid solution, and a second mixture of the obtained solid solution and a metal compound is further fired. A phosphor is manufactured.

The metal halide is preferably at least one selected from the group consisting of alkali metal halides, alkaline earth metal halides and rare earth halides, and may be alkali metal halides and / or alkaline earth metal halides. More preferably, it is more preferably an alkaline earth halide, particularly preferably alkaline earth chloride. Examples of the alkaline earth chloride include strontium halide, and examples of the strontium halide include strontium chloride (SrCl ₂ ).

The molar ratio between the metal halide and the Eu-containing compound (metal halide / Eu-containing compound) is preferably 0.05 or more and 20 or less, more preferably 0.1 or more and 10 or less, More preferably, it is 0.5 or more and 5 or less.
The molar ratio of the metal element contained in the metal halide to the Eu contained in the Eu-containing compound (the metal element contained in the metal halide / Eu contained in the Eu-containing compound) is 0.05 or more and 20 or less. Is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less. For example, when SrCl ₂ is used as the metal halide, the SrCl ₂ and Eu-containing compound is adjusted so that the molar ratio of Sr to Eu (Sr / Eu) is preferably 0.5 to 3, more preferably 1.0. The mixing ratio (for example, Eu ₂ O ₃ ) can be determined.

The mixing of the metal halide and the Eu-containing compound may be performed wet or dry. For mixing, a normal apparatus such as a ball mill, a V-type mixer, or a stirrer can be used.

The firing of the first mixture (hereinafter also referred to as “first firing”) is preferably performed in a reducing atmosphere.
The atmosphere, temperature, and time of the first firing can be appropriately changed according to the composition of the metal halide, the mixing ratio of the metal halide and the Eu-containing compound, and the like.
The atmosphere of the first firing can be a reducing gas atmosphere, and examples thereof include an inert gas (nitrogen, argon, etc.) containing 0.1 to 10% by volume of hydrogen, and ammonia. The first firing atmosphere is preferably an N ₂ atmosphere containing 5% by volume of H ₂ . The firing temperature for the first firing can be, for example, 500 to 700 ° C., and the firing time for the first firing can be, for example, 1 to 24 hours.

Next, the second mixture of the solid solution and the metal compound is fired (hereinafter also referred to as “second firing”).
Examples of the metal compound include oxides, hydroxides, carbonates, nitrates, halides, oxalates, and the like that can be decomposed and / or oxidized at high temperatures to become oxides. In the present specification, the “metal compound” refers to a compound containing a metal element as a constituent element.
The metal compound includes (i) a Si compound and / or a Ge compound, and (ii) a compound containing at least a metal different from a metal contained in the metal halide among the alkali metal and alkaline earth metal compounds. It is preferable to include.
In the present specification, “metal” includes semimetals such as Si and Ge.
Regarding (ii), for example, when an alkali metal halide is used as the metal halide, the metal compound may include at least an alkaline earth metal compound among an alkali metal compound and an alkaline earth metal compound. Preferably, when an alkaline earth metal halide is used as the metal halide, the metal compound preferably contains at least an alkali metal compound among the alkali metal compound and the alkaline earth metal compound. More preferably, the metal compound further includes (iii) at least one compound selected from the group consisting of rare earth element compounds, Zn compounds, Bi compounds, and Mn compounds.

The mixing of the metal compound and the mixing of the metal compound and the solid solution may be performed by a wet method or a dry method. For mixing, a normal apparatus such as a ball mill, a V-type mixer, or a stirrer can be used.

The atmosphere, temperature, and time of the second firing can be appropriately changed depending on the composition of the solid solution, the composition of the metal compound, the mixing ratio of the solid solution and the metal compound, and the like.
The firing atmosphere of the second firing may be any of an inert gas atmosphere, an oxidizing gas atmosphere, and a reducing gas atmosphere. Examples of the inert gas include nitrogen and argon. Examples of the oxidizing gas include air, oxygen, and an inert gas (nitrogen, argon, etc.) containing more than 0% by volume and less than 100% by volume. Examples of the reducing gas include an inert gas (nitrogen, argon, etc.) containing 0.1 to 10% by volume of hydrogen, and ammonia. The firing atmosphere is preferably an N ₂ atmosphere containing 5% by volume of H ₂ . When firing in a strong reducing atmosphere, an appropriate amount of carbon may be added to the metal compound and fired.
The firing temperature for the second firing can be, for example, 700 to 1000 ° C., and the firing time for the second firing can be, for example, 1 to 100 hours. If the second mixture contains a compound such as hydroxide, carbonate, nitrate, halide, oxalate, etc. that decomposes and / or oxidizes at high temperature to an oxide, after the first calcination, Before firing, the second mixture is calcined by holding at a temperature lower than the second firing temperature (for example, 500 to 800 ° C.) for a predetermined time (for example, 1 to 100 hours). It is also possible to remove crystal water from these compounds. Moreover, you may grind | pulverize after calcination.

The yellow phosphor obtained by the method of the present invention contains Eu as an activator. Eu contained in the yellow phosphor obtained by the method of the present invention is derived from an Eu-containing compound. When Eu halide is used as the metal halide and / or when Eu compound is used as the metal compound, Eu contained in the yellow phosphor obtained by the method of the present invention includes Eu-containing compound and Eu halogen. Derived from compounds and / or Eu compounds.
In addition to Eu as an activator, the yellow phosphor obtained by the method of the present invention is at least one element selected from the group consisting of rare earth elements, Mn and Bi (hereinafter also referred to as other activator elements). It is preferable to contain. In this case, the metal halide and / or metal compound contains other activator elements.

The yellow phosphor obtained by the method of the present invention preferably has a single crystal phase. Therefore, it is preferable to add a reaction accelerator to the second mixture at the time of calcination or second baking. By adding a reaction accelerator, the emission intensity of the resulting yellow phosphor can be further increased. Examples of the reaction accelerator include alkali metal halides such as LiF, NaF, KF, LiCl, NaCl, and KCl, alkali metal carbonates such as Li ₂ CO ₃ , Na ₂ CO ₃ , and K ₂ CO ₃ , and alkalis such as NaHCO _3. Examples thereof include metal hydrogen carbonates, ammonium halides such as NH ₄ Cl and NH ₄ I, oxides of earth metals such as B ₂ O _3, and oxo acids of earth metals such as H ₃ BO ₃ .

The yellow phosphor obtained by the method of the present invention contains a halogen element derived from a raw material such as a metal halide or a reaction accelerator, that is, at least one element selected from the group consisting of F, Cl, Br and I. You may go out. The total content of halogen elements contained in the yellow phosphor obtained by the method of the present invention may be equal to or less than the total amount of halogen elements contained in the raw material, preferably 50% or less, more preferably Is 25% or less.

The second mixture after calcination and / or the yellow phosphor of the present invention may be pulverized, washed, or classified using, for example, a ball mill, a jet mill or the like.

By the method of the present invention, the yellow phosphor of the present invention represented by the formula M ¹ _2a (M ² _b L _c ) M ³ _d O ₄ can be produced.

<Yellow phosphor>
The yellow phosphor of the present invention is represented by the formula M ¹ _2a (M ² _b L _c ) M ³ _d O ₄ .

In the formula, M ¹ is at least one element selected from the group consisting of alkali metals, M ² is at least one element selected from the group consisting of alkaline earth metals and Zn, and M ³ is Si And at least one element selected from the group consisting of Ge. M ¹ is preferably at least one element selected from the group consisting of Li, Na and K, and more preferably Li. M ³ is preferably Si. M ² is preferably not only Sr. That is, M ² is preferably Ca, Ba, Mg or Zn, or preferably at least two elements selected from the group consisting of Mg, Ca, Sr, Ba and Zn, and is Ca and Sr. It is more preferable.
L is a luminescent ion that activates the host crystal. L contains at least Eu, and may further contain at least one element selected from the group consisting of rare earth elements, Bi and Mn.
Of the Eu contained in L, the proportion of divalent Eu is 25 mol% or more and 100 mol% or less. The ratio of divalent Eu is preferably 30 mol% or more, more preferably 40 mol% or more, and further preferably 50 mol% or more.

a is 0.1 or more and 1.5 or less, b is 0.8 or more and 1.2 or less, c is 0.005 or more and 0.2 or less, d is 0.8 or more, 1 or less .2 or less. a is preferably 0.8 or more and 1.2 or less, and more preferably 0.9 or more and 1.1 or less. Both b and d are preferably 0.8 or more and 1.0 or less, and more preferably 0.9 or more and 1.0 or less. c is preferably 0.01 or more and 0.1 or less.
It is preferable that b, c, and d satisfy the relationship of b + c = 1 and d = 1. The crystal system of the yellow phosphor of the present invention is preferably hexagonal.

In order to produce the yellow phosphor of the present invention represented by the formula M ¹ _2a (M ² _b L _c ) M ³ _d O ₄ , in the method of the present invention, the mixing ratio of the solid solution and the metal compound is ( M ¹ element) :( ^{M 2} element) :( Eu and other activator elements) :( ^{M 3} ratios of the elements) is 2a: b: c: is defined so as d. That is, for example, in order to obtain a phosphor represented by the formula Li _1.96 Sr _0.98 Eu _0.02 SiO ₄ , which is one of the preferred compositions of the yellow phosphor of the present invention, for example, as a metal halide When SrCl ₂ is used, Eu ₂ O ₃ is used as the Eu-containing compound, a solid solution containing SrCl ₂ and Eu ₂ O ₃ is obtained, and SrCO ₃ , Li ₂ CO ₃ , SiO ₂ and Eu ₂ O ₃ are used as the metal compound The mixing ratio of the solid solution and the metal compound may be determined so that the molar ratio of Li: Sr: Eu: Si is 1.96: 0.98: 0.02: 1.0.

The yellow phosphor of the present invention can be suitably used for a light emitting device.

<Light emitting device>
The light emitting device of the present invention includes the yellow phosphor of the present invention. A white LED is mentioned as a light-emitting device.

A white LED can be generally manufactured by a method disclosed in, for example, Japanese Patent Application Laid-Open Nos. 11-31845 and 2002-226846. That is, by sealing a light-emitting element that emits light having a wavelength of 200 nm or more and 550 nm or less with a light-transmitting resin such as an epoxy resin or a silicone resin, and arranging the phosphor so as to cover the surface of the sealing body A white LED can be manufactured. What is necessary is just to set the quantity of fluorescent substance suitably so that white LED can light-emit desired white.

In the light emitting device of the present invention, as the phosphor, the yellow phosphor of the present invention may be used alone, or the yellow phosphor of the present invention and another phosphor may be used in combination. Other phosphors include BaMgAl ₁₀ O ₁₇ : Eu, (Ba, Sr, Ca) (Al, Ga) ₂ S ₄ : Eu, BaMgAl ₁₀ O ₁₇ : (Eu, Mn), BaAl ₁₂ O ₁₉ : (Eu , Mn), (Ba, Sr, Ca) S: (Eu, Mn), YBO ₃ : (Ce, Tb), Y ₂ O ₃ : Eu, Y ₂ O ₂ S: Eu, YVO ₄ : Eu, (Ca Sr) S: Eu, SrY ₂ O ₄ : Eu, Ca—Al—Si—O—N: Eu, Li— (Ca, Mg) —Ln—Al—O—N: Eu, (Ba, Sr, Ca ) Si ₂ O ₂ N ₂ : Eu, β-sialon, CaSc ₂ O ₄ : Ce (where Ln represents a rare earth metal element other than Eu).

Examples of the light emitting element that emits light having a wavelength of 200 nm or more and 550 nm or less include an ultraviolet LED and a blue LED. In the ultraviolet LED and the blue LED, GaN, In _i Ga _1-i N (0 <i <1), In _i Al _j Ga _1-jj N (0 <i <1, 0 <j <) are used as the light emitting layer. A semiconductor having a layer such as 1, i + j <1) is used. The emission wavelength can be changed by changing the composition of the light emitting layer.

In addition to the white LED, the light emitting device of the present invention is a light emitting device in which the phosphor excitation source such as PDP is a vacuum ultraviolet ray, a backlight for a liquid crystal display, a phosphor excitation source such as a three-wavelength fluorescent lamp, and the like. A light emitting device in which the phosphor excitation source is an electron beam, such as a device, a CRT, or an FED.

Hereinafter, the present invention will be described more specifically with reference to examples. The present invention is not limited to the following examples.

The measurement of the emission intensity of the phosphor was performed using a fluorescence spectrometer (FP-6500 manufactured by JASCO Corporation). X-ray diffraction (XRD) measurement of the phosphor was performed using an X-ray diffractometer (RINT2000 manufactured by Rigaku). Evaluation of the valence ratio of Eu in the phosphor was performed by X-ray absorption fine structure (XAFS) measurement.

XAFS measurement was performed by the transmission method using the beam line BL14B2 in SPring-8. Measurement was carried out as a 6650-7600 eV measurement region which is the Eu-L3 absorption edge. BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (BAM) was used as a standard sample for Eu ²⁺ (6972 eV), and europium oxide (manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.99%) was used as a standard sample for Eu ³⁺ (6980 eV). .

Using an analysis program (Rigaku REX2000), the XAFS data of each sample was processed based on the background to obtain an X-ray absorption near edge structure (XANES) spectrum, and then Eu ⁺ standard sample and Eu ^{3 +} standard sample XANES Using the spectrum, pattern fitting of the XANES spectrum of each sample was performed, and the ratio of Eu ^{2+ in} the sample was calculated from the ratio of Eu ²⁺ peaks.

Comparative Example 1
Lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), europium oxide (manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.99%), and dioxide Each raw material of silicon (manufactured by Nippon Aerosil Co., Ltd .: purity 99.99%) is weighed so that the molar ratio of Li: Sr: Eu: Si is 1.96: 0.98: 0.02: 1.0. These were mixed by a dry ball mill for 6 hours to obtain a metal compound mixture.

The metal compound mixture was calcined by holding at a temperature of 800 ° C. for 24 hours in an N ₂ atmosphere containing 5% by volume of H ₂ , and then gradually cooled to room temperature to obtain the formula Li _1.96 (Sr _0. A phosphor containing a compound represented by ₉₈ Eu _0.02 ) SiO ₄ was obtained.

The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 14 mol%.

Comparative Example 2
Lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), europium oxide (manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.99%), and dioxide Each raw material of silicon (manufactured by Nippon Aerosil Co., Ltd .: purity 99.99%) is weighed so that the molar ratio of Li: Sr: Eu: Si is 1.96: 0.98: 0.02: 1.0. These were mixed by a dry ball mill for 6 hours to obtain a metal compound mixture.

The metal compound mixture was fired in an N ₂ atmosphere containing 5% by volume of H ₂ at a temperature of 800 ° C. for 24 hours and then gradually cooled to room temperature to obtain a fired product. The fired product obtained was pulverized, and the pulverized product was further refired by holding it at a temperature of 800 ° C. for 24 hours in an N ₂ atmosphere containing 5% by volume of H ₂ , and then cooled to room temperature. A phosphor containing a compound represented by Li _1.96 (Sr _0.98 Eu _0.02 ) SiO ₄ was obtained.

The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 17 mol%.

Example 1
Strontium chloride (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more) and europium oxide (manufactured by Shin-Etsu Chemical Co., Ltd., purity 99.99%) were weighed so that the molar ratio of Sr / Eu was 1. (Molar ratio of SrCl ₂ / Eu ₂ O ₃ = 2), and the obtained first mixture was baked at 650 ° C. for 12 hours in an N ₂ atmosphere containing 5% by volume of H ₂ to obtain a solid solution. Obtained.

The obtained solid solution, lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), and silicon dioxide (manufactured by Nippon Aerosil Co., Ltd .: purity 99.000). 99%) to a Li: Sr: Eu: Si molar ratio of 1.96: 0.98: 0.02: 1.0, and these are mixed for 6 hours by a dry ball mill. A mixture was obtained.

The obtained second mixture was calcined by holding at a temperature of 800 ° C. for 24 hours in an N ₂ atmosphere containing 5% by volume of H ₂ , and then gradually cooled to room temperature to obtain the formula Li _1.96 (Sr _{0 .98} Eu _0.02 ) A phosphor containing a compound represented by SiO ₄ was obtained.

It was confirmed that the obtained phosphor had an emission peak at 571 nm. The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 25 mol%.

Example 2
Solid solution obtained in Example 1, lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), and silicon dioxide (manufactured by Nippon Aerosil Co., Ltd.) : 99.99% purity) was measured so that the molar ratio of Li: Sr: Eu: Si was 1.96: 0.98: 0.02: 1.0, and these were mixed for 6 hours by a dry ball mill. A second mixture was obtained.

Second mixture of N ₂ atmosphere containing 5 vol% H ₂ obtained, calcined by holding at a temperature of 800 ° C. 24 hours, then gradually cooled to room temperature to obtain a calcined product. The fired product obtained was pulverized, re-fired by holding at a temperature of 800 ° C. for 24 hours in an N ₂ atmosphere containing 5% by volume of H ₂ , gradually cooled to room temperature, and then expressed by the formula Li _1.96. A phosphor containing a compound represented by (Sr _0.98 Eu _0.02 ) SiO ₄ was obtained.

It was confirmed that the obtained phosphor had an emission peak at 571 nm. The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 46.3 mol%.

Example 3
Solid solution obtained in Example 1, lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), and silicon dioxide (manufactured by Nippon Aerosil Co., Ltd.) : 99.99% purity) was measured so that the molar ratio of Li: Sr: Eu: Si was 1.96: 0.98: 0.02: 1.0, and these were mixed for 6 hours by a dry ball mill. A second mixture was obtained.

The obtained second mixture was calcined by holding at a temperature of 800 ° C. for 24 hours in an N ₂ atmosphere containing 5% by volume of H ₂ , and then gradually cooled to room temperature to obtain the formula Li _0.96 (Sr A phosphor containing a compound represented by _0.98 Eu _0.02 ) SiO ₄ was obtained.

It was confirmed that the obtained phosphor had an emission peak at 571 nm. The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 54.1 mol%.

Example 4
Solid solution obtained in Example 1, lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), and silicon dioxide (manufactured by Nippon Aerosil Co., Ltd.) : 99.99% purity) and the molar ratio of Li: Sr: Eu: Si is 1.96: 0.97: 0.03: 1.0, and these are mixed for 6 hours by a dry ball mill. To obtain a second mixture.

The resulting second mixture was calcined by holding in a N ₂ atmosphere containing 5% by volume of H ₂ at a temperature of 800 ° C. for 24 hours and then gradually cooled to room temperature to obtain the formula Li _1.96 (Sr A phosphor containing a compound represented by _0.98 Eu _0.02 ) SiO ₄ was obtained.

It was confirmed that the obtained phosphor had an emission peak at 571 nm. The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 54.0 mol%.

Example 5
Solid solution obtained in Example 1, lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), and silicon dioxide (manufactured by Nippon Aerosil Co., Ltd.) : 99.99% purity) was measured so that the molar ratio of Li: Sr: Eu: Si was 1.96: 0.95: 0.05: 1.0, and these were mixed by a dry ball mill for 6 hours. A second mixture was obtained.

The resulting second mixture was calcined by holding in a N ₂ atmosphere containing 5% by volume of H ₂ at a temperature of 800 ° C. for 24 hours and then gradually cooled to room temperature to obtain the formula Li _1.96 (Sr _0.95 Eu _0.05 ) A phosphor containing a compound represented by SiO ₄ was obtained.

It was confirmed that the obtained phosphor had an emission peak at 571 nm. The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 28.0 mol%.

Example 6
Solid solution obtained in Example 1, lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), and silicon dioxide (manufactured by Nippon Aerosil Co., Ltd.) : Purity 99.99%) was measured so that the molar ratio of Li: Sr: Eu: Si was 1.96: 0.97: 0.03: 1.0, and these were mixed by a dry ball mill for 6 hours. A second mixture was obtained.

The resulting second mixture was calcined by holding in a N ₂ atmosphere containing 5% by volume of H ₂ at a temperature of 800 ° C. for 24 hours and then gradually cooled to room temperature to obtain the formula Li _1.96 (Sr A phosphor containing a compound represented by _0.97 Eu _0.03 ) SiO ₄ was obtained.

It was confirmed that the obtained phosphor had an emission peak at 571 nm. The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 64.3 mol%.

Example 7
Solid solution obtained in Example 1, lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), and silicon dioxide (manufactured by Nippon Aerosil Co., Ltd.) : 99.99% purity) was measured so that the molar ratio of Li: Sr: Eu: Si was 1.96: 0.95: 0.05: 1.0, and these were mixed by a dry ball mill for 6 hours. A second mixture was obtained.

It was confirmed that the obtained phosphor had an emission peak at 571 nm. The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 56.0 mol%.

Example 8
Solid solution obtained in Example 1, lithium carbonate (manufactured by Kanto Chemical Co., Ltd., purity 99%), strontium carbonate (manufactured by Sakai Chemical Industry Co., Ltd., purity 99% or more), and silicon dioxide (manufactured by Nippon Aerosil Co., Ltd.) : Purity 99.99%) was measured so that the molar ratio of Li: Sr: Eu: Si was 1.96: 0.93: 0.07: 1.0, and these were mixed for 6 hours by a dry ball mill. A second mixture was obtained.

The resulting second mixture was calcined by holding in a N ₂ atmosphere containing 5% by volume of H ₂ at a temperature of 800 ° C. for 24 hours and then gradually cooled to room temperature to obtain the formula Li _1.96 (Sr _0.93 Eu _0.07 ) A phosphor containing a compound represented by SiO ₄ was obtained.

It was confirmed that the obtained phosphor had an emission peak at 571 nm. The ratio of divalent Eu (Eu ²⁺ ) in the total Eu of the obtained phosphor was 50.0 mol%.

As a result of XRD measurement, it was confirmed that all the phosphors obtained in Examples 1 to 8 were hexagonal.

According to the method of the present invention, the first mixture of the metal halide and the Eu-containing compound is fired to produce a solid solution, and then the second mixture of the solid solution and the metal compound is fired. Eu ²⁺ can be stably generated. Therefore, a yellow phosphor having a high Eu ²⁺ content ratio can be obtained.
That is, according to the method of the present invention, even when the firing temperature is low, the Eu raw material can be efficiently reduced, and the ratio of Eu ^{2+ in} the total Eu of the obtained phosphor can be improved. A phosphor can be manufactured at low cost.

Claims

A method for producing a yellow phosphor, comprising: firing a first mixture of a metal halide and an Eu-containing compound to produce a solid solution; and firing a second mixture of the solid solution and the metal compound.
The method according to claim 1, wherein the metal halide is at least one compound selected from the group consisting of alkali metal halides, alkaline earth metal halides, and rare earth halides.
The method according to claim 2, wherein the metal halide is an alkali metal halide and / or an alkaline earth metal halide.
4. The method of claim 3, wherein the metal halide is strontium halide.
The method of claim 4, wherein the strontium halide is strontium chloride.
The metal compound includes (i) a Si compound and / or a Ge compound, and (ii) a compound containing at least a metal different from a metal contained in the metal halide among the alkali metal compound and the alkaline earth metal compound. 6. The method according to claim 1, further comprising:
The method according to claim 6, wherein the metal compound further comprises (iii) at least one compound selected from the group consisting of a rare earth element compound, a Zn compound, a Bi compound, and a Mn compound.
The molar ratio of the metal element contained in the metal halide to the Eu contained in the Eu-containing compound (metal element contained in the metal halide / Eu contained in the Eu-containing compound) is 0.05 or more and 20 or less. The method according to any one of claims 1 to 7.
A yellow phosphor produced by the method according to any one of claims 1 to 8.
A yellow phosphor represented by the formula M 1 2a (M 2 b L c ) M 3 d O 4 .
In the formula, M 1 is at least one element selected from the group consisting of alkali metals,
M 2 is at least one element selected from the group consisting of alkaline earth metals and Zn,
M 3 is at least one element selected from the group consisting of Si and Ge;
L is at least one element selected from the group consisting of rare earth elements, Bi and Mn, and L includes at least Eu,
Of the Eu, the ratio of divalent Eu is 25 mol% or more and 100 mol% or less,
a is 0.9 or more and 1.1 or less,
b is 0.8 or more and 1.2 or less,
c is 0.005 or more and 0.2 or less,
d is 0.8 or more and 1.2 or less.
The yellow phosphor according to claim 10, wherein M 1 is Li and M 3 is Si.
The yellow phosphor according to claim 10 or 11, wherein a is 0.9 or more and 1.1 or less.
The yellow phosphor according to any one of claims 10 to 12, wherein b, c, and d satisfy a relationship of b + c = 1 and d = 1.
The yellow color according to any one of claims 10 to 13, wherein M 2 is Ca, Ba, Mg or Zn, or at least two elements selected from the group consisting of Ca, Sr, Ba, Mg and Zn. Phosphor.
15. The yellow phosphor according to claim 10, wherein the crystal system of the yellow phosphor is hexagonal.
16. A light emitting device using the yellow phosphor according to claim 10.
A white LED using the yellow phosphor according to any one of claims 10 to 15.