WO2018003605A1 - Process for producing red fluorescent substance - Google Patents

Abstract

A process for producing a red fluorescent substance having an excellent luminance is provided. The process is for producing a red fluorescent substance containing strontium, and includes a burning step in which strontium nitride having a hydrogen content of 500 ppm or less is used as a starting material and a starting-material mixture containing the strontium nitride is burned. It is preferable that the production process should comprise a mixing step in which a plurality of starting materials are mixed and the burning step in which the starting-material mixture obtained in the mixing step is burned. It is preferable that the red fluorescent substance containing strontium be a red fluorescent substance comprising a base crystal phase having the same crystal phase as (Sr,Ca)AlSiN₃.

Description

Method for producing red phosphor

The present invention relates to a method for producing a red phosphor. Specifically, the present invention generally provides a SCASN phosphor that absorbs light from a light emitting element such as an LED and emits red light, wherein the base crystal has substantially the same crystal structure as (Sr, Ca) AlSiN _3. The present invention relates to a method for manufacturing a phosphor called “a”.

A white LED includes a semiconductor light-emitting element that is a light-emitting light source, and a phosphor that has a relatively high energy of the light-emitting light source and absorbs part of light with a short wavelength as excitation light and converts it to another color with a long wavelength. It is a device that emits pseudo white light by a combination, and a blue LED and a YAG (yttrium, aluminum, garnet) yellow phosphor are known as a typical example of the combination. However, the white LED by this combination is in the white region as its chromaticity coordinate value, but lacks a red light emitting component, so that the color rendering property is low for lighting use, and an image display device such as a liquid crystal backlight Then, there is a problem that color reproducibility is bad.
For this reason, Patent Document 1 proposes to use a nitride or oxynitride phosphor that emits red light together with a YAG phosphor in order to compensate for the insufficient red light-emitting component.

As a nitride phosphor that emits red light, an inorganic compound in which an optically active element is activated in a base crystal having the same crystal phase as CaAlSiN ₃ is known, and in particular, activated by Eu ²⁺ (also called activation). The CaAlSiN ₃ phosphor is said to emit light with particularly high luminance (for example, Patent Document 2).
Patent Document 2 describes that a phosphor having an emission peak wavelength shifted to the short wavelength side can be obtained by substituting part of Ca with Sr while maintaining the crystal phase. The phosphor is called, for example, a (Sr, Ca) AlSiN ₃ phosphor activated by Eu ²⁺ , and tends to increase spectral components in a region having a shorter emission wavelength and higher visibility than the CaAlSiN ₃ phosphor. Therefore, it is effective as a red phosphor for high brightness white LED.

However, CaAlSiN ₃ phosphor and (Sr, Ca) AlSiN ₃ fluorescent material CaAlSiN ₃ based nitride phosphor, such as, for containing many spectral components to long red region especially wavelengths in the red, while capable of realizing a high color rendering property However, the ratio of spectral components having low visibility is increased, and the luminance as a white LED generally tends to be low.
Therefore, in order to provide a light emitting device with high light emission luminance in the industry, it has been expected to increase the luminance of the red phosphor.

JP 2004-071726 A International Publication No. 2005/052087 Pamphlet

Therefore, the main object of the present invention is to provide a method for producing a red phosphor having excellent luminance.

The present inventors, in order to solve the above problems, the red phosphor, for example (Sr, Ca) AlSiN ₃ As a result of intensive studies for strontium nitride which is used for a part of a raw material used in manufacturing the phosphor, hydrogen content When strontium nitride having a specific value of less than a specific value is used as a raw material, it has been found that a red phosphor having high luminance can be produced, and the present invention has been completed.

That is, the present invention is as follows.
(1) The present invention is a method for producing a red phosphor containing strontium, which has a firing step of firing a raw material mixture containing strontium nitride using strontium nitride having a hydrogen content of 500 ppm or less as a raw material.
(2) The present invention uses strontium nitride having a hydrogen content of 500 ppm or less as a raw material, and includes a mixing step of mixing a plurality of raw materials, and a baking step of firing the raw material mixture after the mixing step, and a red color containing strontium It is a manufacturing method of fluorescent substance.
(3) The above (1) or (2), wherein the strontium nitride having a hydrogen content of 500 ppm or less is obtained by reacting strontium hydride obtained by reacting metal strontium with hydrogen and nitrogen. This is a method for producing a red phosphor.
(4) The method for producing a red phosphor according to any one of (1) to (3) above, wherein the hydrogen content of strontium nitride is 15 ppm or more.
(5) The red phosphor containing strontium is a red phosphor having the same crystal phase as (Sr, Ca) AlSiN ₃ as a host crystal phase, described in any one of (1) to (4) above This is a method for producing a red phosphor.
(6) The raw material mixture contains at least strontium nitride and calcium nitride, and Sr / (Ca + Sr) = 0.35 to 0.95 (molar ratio) in the raw material mixture. (5) The method for producing a red phosphor according to any one of (5).

ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing red fluorescent substance excellent in the brightness | luminance can be provided.
According to the present invention, a high red phosphor luminance, for example (Sr, Ca) AlSiN ₃ the same crystal phase as a host crystal phase, the red phosphor comprising strontium, it is possible to provide a manufacturing method. A high-luminance light emitting element can be provided by combining the red phosphor and a light emitting light source such as an LED.
Note that the effects described here are not necessarily limited, and may be any of the effects described in the present specification.

Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, embodiment described below shows an example of embodiment of this invention, and, thereby, the range of this invention is not interpreted narrowly.

What is manufactured by carrying out the present invention is a red phosphor, and the main crystal phase of the red phosphor is, for example, the same crystal phase as (Sr, Ca) AlSiN ₃ as a base crystal phase.
In this specification, for convenience, it is described that the composition of the main crystal phase of the phosphor is represented by the general formula (Sr, Ca) AlSiN ₃ , but the raw materials may be blended so as to obtain the phosphor having such a composition. The composition of the phosphor may fluctuate during firing. The composition of the red phosphor according to the present specification is an expression including such variation.
Whether or not the main crystal phase of the red phosphor is the same crystal phase as, for example, (Sr, Ca) AlSiN ₃ can be confirmed by powder X-ray diffraction measurement.
The main crystal phase, for example (Sr, Ca) crystal structure of the red phosphor prepared to have the same crystalline phase and AlSiN ₃ is (Sr, Ca) if different from the AlSiN _3, the light emitting color This is not preferable because it is no longer red or the fluorescence intensity is greatly reduced.
The main crystal phase is preferably the same as the (Sr, Ca) AlSiN ₃ and a single-phase crystal, but may contain a different phase as long as the phosphor characteristics are not greatly affected. The presence or absence of a heterogeneous phase can be determined by the presence or absence of a peak other than that due to the target crystal phase, for example, by powder X-ray diffraction.

The crystal structure of, for example, (Sr, Ca) AlSiN ₃ which is a red phosphor is a structure in which (Si, Al) -N4 tetrahedrons are bonded, and a crystal structure in which Sr atoms and Ca atoms are located in the gaps. Have
In this (Sr, Ca) AlSiN ₃ , when a part of Sr ²⁺ or Ca ²⁺ located in the gap of the crystal structure is replaced with Eu ²⁺ acting as a luminescence center, a red phosphor called a so-called SCASN phosphor is obtained.

When the red phosphor of the present invention is a phosphor having the same crystal phase as, for example, (Sr, Ca) AlSiN ₃ as a host crystal phase, the ratio of Sr and Ca is not particularly defined, but expresses high luminance. From the viewpoint of a preferable range, it is preferably Sr / (Ca + Sr) = 0.35 to 0.95 (molar ratio), more preferably Sr / (Ca + Sr) = 0.40 to 0.90 (molar ratio). ).

If the Eu content is too small, the contribution to light emission tends to be small. If the Eu content is too large, a phenomenon generally called concentration quenching due to energy transfer between Eu ²⁺ tends to occur. The rate is preferably 0.01 to 0.4 atomic%.
A more preferable range of the Eu content in the raw material is 0.01 to 0.3 atom%, more preferably 0.04 to 0.2 atom%, and still more preferably 0.06 to 0.15 atom. %.

The phosphor obtained by the manufacturing method of the present embodiment contains a trace amount of oxygen (O) as an inevitable component. Then, the occupancy ratio of Ca and Sr, the Si / Al ratio, and the N / O ratio, which are the composition parameters of the phosphor, are adjusted so that the electrical neutrality is maintained as a whole while maintaining the crystal structure. .

In the method for producing a red phosphor according to this embodiment, the hydrogen content of strontium nitride used as a raw material is 500 ppm or less.
When the hydrogen content of the strontium nitride exceeds 500 ppm, the luminance of the phosphor tends to decrease. The fact that the hydrogen content of such strontium nitride is related to the luminance of the phosphor is a finding newly found by the inventors focusing on the hydrogen content of strontium nitride.
A more preferable range of the hydrogen content of strontium nitride is 15 ppm or more and 500 ppm or less, and further preferably a range of 30 ppm or more and 480 ppm or less. Furthermore, the range of the hydrogen content of strontium nitride is more preferably 30 ppm or more and 380 ppm or less, and particularly preferably 30 ppm or more and 160 ppm, from the viewpoint of improving the emission intensity.

In the method for producing a red phosphor according to the present embodiment, hydrogen contained in strontium nitride used as a raw material may be, for example, in a Sr—H state or an O—H state bonded to surface oxygen. As good, the state contained in strontium nitride does not matter.
In addition, in the manufacturing method of the red phosphor according to the present embodiment, inevitable hydrogen content in the strontium nitride used as the raw material may not be denied, but the upper limit value of the hydrogen content of the strontium nitride used as the raw material (that is, 500 ppm) can be preferably applied to hydrogen contained in strontium nitride obtained by reacting strontium metal obtained by reacting strontium metal with hydrogen and nitrogen. However, the method for producing a red phosphor containing strontium of the present invention does not particularly limit the origin until hydrogen is contained in strontium nitride and the method for producing strontium nitride.
Therefore, in the present embodiment, the hydrogen contained in the strontium nitride is derived from, for example, a process for producing strontium nitride by reacting strontium hydride obtained by reacting metal strontium and hydrogen with nitrogen. Hydrogen derived from OH groups generated by surface alteration of strontium nitride may also be used.

The strontium hydride is, for example, metal strontium in a hydrogen atmosphere at 100 ° C. to 200 ° C. (preferably 130 ° C. to 180 ° C.) for 6 hours to 24 hours (preferably 8 hours to 16 hours). It can be manufactured by heating and hydrotreating.
The nitrogen strontium is, for example, strontium hydride at 500 ° C. to 1500 ° C. (preferably 500 ° C. to 1000 ° C.) in a nitrogen gas atmosphere for 0.5 to 12 hours (preferably 1 to 5 hours). ) It can be manufactured by heating and nitriding. Preferably, nitriding is performed if nitrogen gas is allowed to flow into the tubular furnace.
Furthermore, it is preferable to collect strontium nitrogen after nitriding treatment to obtain strontium nitride used as a raw material in the method for producing a red phosphor of the present invention.
After collection, it is preferable to classify and select only those that have passed through a sieve having an opening of 290 μm. Thereby, strontium nitride of 290 μm or less can be obtained.

In the method for producing a red phosphor containing strontium according to the present invention, strontium nitride used as a raw material of the phosphor is another embodiment of the present invention, and the identification of the strontium nitride is based on the X-ray diffraction of the strontium nitride. The pattern can be compared with a JCPDS (Joint Committee on Power Diffraction Standards) card which is a database of X-ray diffraction patterns in crystal structure analysis. In this JCPDS card, Sr ₂ N, SrN, SrN ₂ and Sr ₄ N ₃ are listed as strontium nitride. Among various strontium nitrides, SrN, Sr ₂ N or a mixture thereof having excellent stability Preferred is strontium nitride (Sr ₃ N ₂ ) having a main crystal phase.

As a method for producing a red phosphor containing strontium according to the present invention, for example, a production method similar to a conventional (Sr, Ca) AlSiN ₃ phosphor can be used. The present invention is preferably a method for producing a red phosphor containing europium, and more preferably a method for producing a (Sr, Ca) AlSiN ₃ phosphor containing strontium and europium.
In the production method of the present invention, it is preferable to use at least strontium nitride having a hydrogen content of 500 ppm or less as a raw material.

Furthermore, it is a step of mixing a plurality of raw materials, and includes a mixing step in which the raw material contains strontium nitride having a hydrogen content of 500 ppm or less, and a firing step in which the raw material mixture after the mixing step is fired. Is preferred. The plurality of raw materials preferably include at least a strontium compound, a calcium compound, an aluminum compound, and a silicon compound, and more preferably include a europium compound. These raw materials can be used alone or in combination.
Each raw material is preferably a powder, and preferably passes through a sieve having an opening of 75 μm. Thereby, powder with a particle size of 75 μm or less can be obtained.
As for the oxygen content rate of each raw material to be used, 1.0 mass% or less is preferable.

Further, when a red phosphor having the same crystal phase as (Sr, Ca) AlSiN ₃ as a base crystal phase is produced, the raw material is set to have a molar ratio of Sr / (Ca + Sr) of the red phosphor of the present invention described above. It is preferable to adjust the mixture. Specifically, the Sr / (Ca + Sr) molar ratio of the raw material mixture in the mixing step is preferably Sr / (Ca + Sr) = 0.35 to 0.95 (molar ratio), more preferably Sr / (Ca + Sr). = 0.40-0.90 (molar ratio) is preferred.

Here, as one embodiment of the present invention, a method for producing the (Sr, Ca) AlSiN ₃ phosphor by firing a raw material mixed powder that can be formed by firing in a predetermined temperature range in a nitrogen atmosphere. Illustrate.

In this manufacturing method, it is preferable to use a nitride of an element constituting the red phosphor as a raw material, but it is also possible to use an oxide.
For example, when the red phosphor has the same crystal phase as (Sr, Ca) AlSiN ₃ as a base crystal phase, that is, strontium nitride, calcium nitride, silicon nitride, aluminum nitride, and europium nitride are preferably used. It is also possible to use these oxides (for example, europium oxide, etc.). In addition, it is preferable to use α-type silicon nitride. These can be used alone or in combination.
For example, europium oxide, which is easily available, may be used as a europium source with a very small addition amount because it acts as a luminescent center. When europium is included in the raw material mixture, the europium content in the raw material mixture is preferably within the preferable range of the Eu content in the raw material described above.

The method for mixing the above-mentioned raw materials is not particularly limited. For example, when a compound that reacts violently with moisture and oxygen in the air (for example, calcium nitride, strontium nitride, europium nitride, etc.) is used, it is replaced with an inert atmosphere. It is appropriate to handle in the glove box. One or two or more of these can be selected and used.

Furthermore, it is preferable to use an intermediate raw material mixture of a silicon compound, an aluminum compound and a europium compound in the mixing step. This intermediate raw material mixture can be obtained by ball-mixing a silicon compound, an aluminum compound and a europium compound in advance using a solvent and passing through a sieve having an opening of 75 μm after drying. The silicon compound is preferably α-type silicon nitride powder. The aluminum compound is preferably aluminum nitride powder. The europium compound is preferably europium oxide powder. The solvent is preferably an alcohol having 1 to 3 carbon atoms such as ethanol.

In the mixing step, it is preferable that the intermediate raw material mixture, the raw material strontium nitride, and the calcium compound are pulverized and mixed to obtain a final raw material mixture. The calcium compound is preferably calcium nitride. The blending ratio of (intermediate raw material mixture) :( raw material strontium nitride and calcium nitride) is preferably 45 to 55 mass%: 55 to 45 mass%.

The firing container is preferably made of a material that is chemically stable in a high-temperature nitrogen atmosphere and hardly reacts with the raw material mixed powder and its reaction product, and examples thereof include containers made of boron nitride, carbon, and the like. It is done.

For firing, for example, a firing container filled with the raw material mixed powder is taken out from the glove box, and immediately set in a firing furnace, and the firing temperature is 1600 ° C. to 1950 ° C. (preferably 1600 ° C. to 1900 ° C.) in a nitrogen atmosphere. The temperature is preferably 1700 ° C. or higher and 1900 ° C. or lower. When the firing temperature is lower than 1600 ° C., the amount of unreacted residue increases. When the firing temperature is higher than 1950 ° C., the main crystal phase is decomposed.

There is no particular limitation on the firing time, but there are disadvantages that there are many unreacted raw materials, the growth of the main crystal phase of the red phosphor is insufficient, or the productivity of the red phosphor is significantly reduced. No firing time range is selected. In a preferred embodiment of the present invention, the firing time is generally set in the range of 2 hours to 24 hours (preferably 2 hours to 12 hours, more preferably 2 hours to 6 hours).

The pressure of the firing atmosphere is selected according to the firing temperature. When the red phosphor obtained by the production method of the present invention is a phosphor having the same crystal phase as (Sr, Ca) AlSiN ₃ as a host crystal phase, for example, the fluorescence is up to about 1800 ° C. under atmospheric pressure. Although the body can exist stably, it is preferable to set it in a pressurized atmosphere in order to suppress decomposition of the phosphor at a temperature higher than this. The higher the atmospheric pressure (MPaG; hereinafter referred to as “MPa”), the higher the decomposition temperature of the phosphor. However, considering industrial productivity, it is less than 1 MPa (preferably 0.1 MPa or more, more preferably 0). 0.5 MPa or more and 0.9 MPa or less).

The state of the fired product including the red phosphor after the firing step obtained by the method for producing the red phosphor of the present invention varies depending on the raw material composition and firing conditions, such as powder, lump, and sintered body. . When used as a phosphor, the fired product obtained by combining crushing, grinding and / or classification operations is made into a powder of a predetermined size. For example, it is preferable to classify and select only those that have passed through a sieve having an opening of 45 μm.
When suitably used as an LED phosphor, it is preferable to adjust the average particle size of the fired product to 5 to 30 μm.

For the purpose of removing impurities contained in the fired product containing the red phosphor, the fired product may be subjected to an acid treatment, or an annealing treatment may be further performed to improve the crystallinity of the red phosphor. good.

When the red phosphor obtained by the production method of the present invention is irradiated with light from a light source that emits ultraviolet light or visible light having a wavelength of 350 nm or more and 500 nm or less, the red phosphor has a wavelength of 610 nm to around 650 nm. Emits red light with a fluorescent peak. In particular, a light emitting element that easily emits white light by combining a light emitting light source such as an ultraviolet LED or a blue LED and the red phosphor, and further combining a green to yellow phosphor and / or a blue phosphor as necessary. Obtainable.

Hereinafter, a method for producing a red phosphor containing strontium according to the present invention will be described with reference to Examples and Comparative Examples. In addition, the Example described below shows an example of a typical example of the present technology, and the scope of the present technology is not interpreted narrowly.
This explanation is also an explanation of the method for producing red phosphors of Examples and Comparative Examples using strontium nitride having different hydrogen content as a raw material, and the hydrogen content is determined by the characteristic evaluation of the obtained red phosphors. This is an evaluation of a method for producing a red phosphor using strontium nitride of 500 ppm or less, and at the same time, an evaluation of strontium nitride which is a raw material for a red phosphor having a hydrogen content of 500 ppm or less.

Example 1
<Manufacture of strontium nitride>
Metal strontium (made by Strem Chemicals Inc., 38-0074 grade, purity 99.9%) was placed in a pressure vessel, evacuated, filled with hydrogen, and heated at 150 ° C. for 12 hours for hydrogenation. . The obtained strontium hydride was set in a tubular furnace, and further heated at 700 ° C. for 3 hours while flowing nitrogen gas into the tubular furnace to nitride the strontium hydride. The obtained nitrogen strontium is recovered, and only those that have passed through a sieve having a mesh opening of 290 μm are classified and selected, and used as the red phosphor raw material. Obtained strontium nitride).

<Analysis of crystal phase>
The raw material strontium nitride was subjected to powder X-ray diffraction using CuKα rays using an X-ray diffractometer (Ultima IV manufactured by Rigaku Corporation). The obtained X-ray diffraction pattern is shown in FIG. When the X-ray diffraction pattern shown in FIG. 1 was collated with a JCPDS card, it was confirmed that strontium nitride (Sr ₃ N ₂ ) was generated.

<Analysis of hydrogen content>
For the raw material strontium nitride, the hydrogen content was measured using an inorganic element analyzer (TCH-600 manufactured by LECO). As a result, 480 ppm of hydrogen was contained. The results are shown in Table 1.

(Examples 2 to 4, Comparative Examples 1 to 3)
The raw material strontium nitride of Examples 2 to 4 and Comparative Examples 1 to 3 was obtained in the same manner as in Example 1 except that the heating temperature and heating time of the nitriding treatment were changed. The results of these hydrogen contents are shown in Table 1 together with Example 1.

(Example 5)
<Manufacture of red phosphor>
Α-type silicon nitride powder (SN-E10 grade, Ube Industries, Ltd., oxygen content 1.0 mass%) 52.2 mass%, aluminum nitride powder (E grade, Tokuyama Corp., oxygen content) 0.8 mass%) 45.8 mass%, europium oxide (RU grade made by Shin-Etsu Chemical Co., Ltd.) 2.0 mass%, using a nylon pot and silicon nitride balls, and ethanol as a solvent, mixing the ball mill went. After removing the solvent by drying, it was classified and sorted only through a sieve having an opening of 75 μm to obtain an intermediate raw material mixture from which aggregates had been removed.

The intermediate raw material mixture, the raw material strontium nitride having a hydrogen content of 480 ppm shown above, and calcium nitride powder (manufactured by Materion, purity 99%, particle size of 75 μm or less, oxygen content 0.6 mass%) are added to the atmosphere. It is carried into a nitrogen-substituted glove box, and the intermediate raw material mixture: raw material strontium nitride: calcium nitride = 49.5 mass%: 48.3 mass%: 2.2 mass% so that the Sr / (Sr + Ca) ratio is 0.90. The final raw material mixture was obtained by further mixing with a mortar.

The raw material mixture is filled in a cylindrical boron nitride container (N-1 grade, manufactured by Denki Kagaku Kogyo Co., Ltd.) with a lid in the glove box, taken out from the glove box, and immediately set in the electric furnace of the carbon heater. The inside of the electric furnace was sufficiently evacuated to 0.1 Pa or less. Heating was started with evacuation, and after reaching 600 ° C., nitrogen gas was introduced into the electric furnace, and the atmospheric pressure in the furnace was set to 0.9 MPa. After the introduction of nitrogen gas, the temperature was raised to 1800 ° C. as it was, and firing was performed at 1800 ° C. for 4 hours.

After stopping energization of the electric furnace and cooling to room temperature, the fired product was crushed using a ball mill and further classified with a vibrating sieve having an opening of 45 μm.

The fired product after classification was subjected to powder X-ray diffraction using CuKα rays using an X-ray diffractometer (Uriga IV manufactured by Rigaku Corporation). The resulting X-ray diffraction pattern, (Sr, Ca) AlSiN ₃ have the same crystalline phase same diffraction as pattern and, therefore, the main crystal phase of the baked product (Sr, Ca) AlSiN ₃ identical crystal and It was confirmed that the phase was a host crystal phase, and the fired product was a red phosphor containing strontium.

The amount of Ca and Sr contained in the obtained red phosphor is measured using an ICP emission spectroscopic analyzer (CIROS-120, manufactured by Rigaku Corporation) after dissolving the fired product by a pressure acid decomposition method. did. As a result, Sr / (Ca + Sr) in the fired product was 0.90 (molar ratio).

(Phosphor properties)
The fluorescence spectrum of the red phosphor obtained in Example 1 was measured using a spectrofluorometer (F-7000, manufactured by Hitachi High-Technologies Corporation) corrected with rhodamine B and a sub-standard light source. For the measurement, a solid sample holder attached to the photometer was used, and a fluorescence spectrum at an excitation wavelength of 455 nm was obtained. The peak wavelength of the fluorescence spectrum was 630 nm. The results are shown in Table 2. The emission intensity in Table 2 was measured using the peak intensity of the fluorescence spectrum as an index. In the following examples and comparative examples, the peak intensity was measured using the same sampling method and conditions as in Example 5, and Example 5 was set to 100. % As a relative value, and when it was 100% or more, it was determined that the product had good luminance.

(Examples 6 to 8, Comparative Examples 4 to 6)
The red fluorescence of Examples 6 to 8 and Comparative Examples 4 to 6 was the same as that of Example 5 except that the raw material strontium nitride was changed to strontium nitride produced in Examples 2 to 4 and Comparative Examples 1 to 3, respectively. The body was made. Further, the red phosphors of Examples 6 to 8 and Comparative Examples 4 to 6 were measured by the same method as that of Example 5, and are shown in Table 2 together with the results of Example 5.

Example 9
A red phosphor of Example 9 was produced in the same manner as in Example 5 except that the raw material ratio was changed so that the Sr / (Sr + Ca) ratio was 0.75. The emission intensity was a relative value when Example 5 was taken as 100%. The results are shown in Table 3.

(Example 10, Comparative Examples 7 and 8)
The red phosphors of Example 10 and Comparative Examples 7 and 8 were produced in the same manner as Example 9 except that the strontium nitride was changed to the raw material strontium nitride prepared in Example 3 and Comparative Examples 1 and 2, respectively. The emission intensity was a relative value when Example 9 was 100%. The results are shown in Table 3 together with the results of Example 9.

(Example 11)
A red phosphor of Example 11 was produced in the same manner as in Example 5 except that the raw material ratio was changed so that the Sr / (Sr + Ca) ratio was 0.40.

(Example 12, Comparative Examples 9, 10)
The phosphor powders of Example 12 and Comparative Examples 9 and 10 were produced in the same manner as Example 11 except that the raw material strontium was changed to the raw material strontium nitride prepared in Example 3 and Comparative Examples 1 and 2, respectively. . The emission intensity was a relative value when Example 11 was 100%. The results are shown in Table 4 together with the results of Example 11.

As shown in Tables 2 to 4, when the hydrogen content in the raw material strontium nitride was 500 ppm or more, the emission intensity was greatly reduced. From this, it was found that the brightness of the red phosphor containing strontium was improved by setting the hydrogen content of the red phosphor containing strontium to 500 ppm or less in the raw material strontium nitride.

In the above, this invention was demonstrated based on the Example. It is to be understood by those skilled in the art that this embodiment is merely an example, and that various modifications are possible and that such modifications are within the scope of the present invention.

A red phosphor obtained by the method for producing a red phosphor containing strontium according to the present invention, for example, a phosphor having the same crystal phase as (Sr, Ca) AlSiN ₃ as a host crystal, is excited by blue light and has a high luminance. Since it emits red light, it can be suitably used as a phosphor for white LEDs using blue light as a light source, and can be suitably used for light-emitting devices such as lighting fixtures and image display devices.

Claims (6)

1. A method for producing a red phosphor containing strontium, comprising using a strontium nitride having a hydrogen content of 500 ppm or less as a raw material and firing a raw material mixture containing the strontium nitride.
2. The method for producing a red phosphor according to claim 1, comprising: a mixing step of mixing a plurality of raw materials using a strontium nitride having a hydrogen content of 500 ppm or less as a raw material; .
3. The red phosphor according to claim 1 or 2, wherein the strontium nitride having a hydrogen content of 500 ppm or less is obtained by reacting strontium hydride obtained by reacting metal strontium with hydrogen and nitrogen. Method.
4. The method for producing a red phosphor according to any one of claims 1 to 3, wherein the hydrogen content of strontium nitride is 15 ppm or more.
5. 5. The method for producing a red phosphor according to claim 1, wherein the red phosphor containing strontium is a red phosphor having the same crystal phase as (Sr, Ca) AlSiN ₃ as a host crystal phase.
6. The raw material mixture contains at least strontium nitride and calcium nitride, and Sr / (Ca + Sr) = 0.35 to 0.95 (molar ratio) in the raw material mixture. The manufacturing method of the red fluorescent substance of description.