阅读说明：本技术 一种锶铕氮化物固溶体粉末及其制备方法 (Strontium-europium nitride solid solution powder and preparation method thereof ) 是由 张尚虎 申晋陇 周宏亮 张轩荣 于 2020-11-24 设计创作，主要内容包括：本发明公开了一种锶铕氮化物固溶体粉末及其制备方法,所述锶铕氮化物固溶体粉末由锶铕氮化物固溶体粉碎制成,所述锶铕氮化物固溶体的化学通式为(Sr-(1-x)Eu-x)-2N；其中,0＜x≤0.02。其制备方法包括以下步骤：S1、称取金属锶Sr、金属铕Eu,将其真空熔炼炉内,抽真空洗炉后通入氩气作为保护气体,熔融后浇筑于铸锭模具中,获得合金铸锭；S2、将合金铸锭进行表面清理后,置于氢破碎炉中,通入氢气并加热,使合金铸锭破碎,然后加热脱氢,获得合金粗粉末；S3、将氢破碎炉的温度降低至150℃以下,在氢破碎炉中通入氮气并逐步升温至450℃保温5小时,获得锶铕氮化物固溶体粉末。(The invention discloses strontium-europium nitride solid solution powder and a preparation method thereof, wherein the strontium-europium nitride solid solution powder is prepared by crushing strontium-europium nitride solid solution, and the chemical general formula of the strontium-europium nitride solid solution is (Sr) 1‑x Eu x ) 2 N; wherein x is more than 0 and less than or equal to 0.02. The preparation method comprises the following steps: s1, weighing strontium metal Sr and europium metal Eu, placing the strontium metal Sr and the europium metal Eu in a vacuum smelting furnace, vacuumizing and washing the furnace, introducing argon as protective gas, and pouring the argon into a casting mold after melting to obtain an alloy ingot; s2, cleaning the surface of the alloy ingot, placing the alloy ingot in a hydrogen crushing furnace, introducing hydrogen and heating to crush the alloy ingot, and then heating and dehydrogenating to obtain alloy coarse powder; s3, reducing the temperature of the hydrogen crushing furnace to be below 150 ℃, introducing nitrogen into the hydrogen crushing furnace and gradually heating to 450 DEG CKeeping the temperature for 5 hours to obtain the strontium-europium nitride solid solution powder.)

1. A strontium europium nitride solid solution powder, which is characterized in that: the strontium europium nitride solid solution powder is prepared by crushing strontium europium nitride solid solution, and the strontium europium nitride solid solution is prepared by crushing strontium europium nitride solid solutionThe chemical general formula of the solution is (Sr)_1-xEu_x)₂N; wherein x is more than 0 and less than or equal to 0.02.

2. A method for producing the strontium europium nitride solid solution powder according to claim 1, characterized in that: the method comprises the following steps:

s1, weighing strontium metal Sr with the purity of more than or equal to 99.99% and europium metal Eu with the purity of more than or equal to 99.99%, placing the strontium metal Sr and the europium metal Eu into a vacuum smelting furnace of an alumina crucible, vacuumizing, washing the furnace, introducing argon as protective gas, melting at 700-800 ℃, and pouring into a casting mold to obtain an alloy cast ingot;

s2, cleaning the surface of the alloy ingot obtained in the step S1, placing the alloy ingot in a hydrogen crushing furnace, washing the furnace with argon, introducing hydrogen with the purity of more than or equal to 99.99%, heating to 200-300 ℃ to crush the alloy ingot, vacuumizing, heating to 550 ℃ to dehydrogenate to obtain alloy coarse powder;

s3, reducing the temperature of the hydrogen crushing furnace to be below 150 ℃, introducing nitrogen obtained by vaporizing liquid nitrogen with the purity of more than or equal to 99.999 percent into the hydrogen crushing furnace, gradually heating to 450 ℃, and keeping the temperature for 5 hours to obtain the strontium-europium nitride solid solution powder.

3. The method for producing a strontium europium nitride solid solution powder according to claim 2, wherein: in the step S1, the furnace is washed three times during the vacuuming and furnace washing.

4. The method for producing a strontium europium nitride solid solution powder according to claim 2, wherein: in the step S2, the surface cleaning of the alloy ingot is mainly used to remove an oxide layer on the surface of the alloy ingot and slag-making impurities generated in the melting process, and then the surface of the alloy ingot is polished to completely remove the oxide layer remaining on the surface.

5. The method for producing a strontium europium nitride solid solution powder according to claim 2, wherein: in the step S2, the furnace is washed three times with argon gas.

6. The method for producing a strontium europium nitride solid solution powder according to claim 2, wherein: in the step S3, the pressure in the hydrogen crushing furnace is maintained at 0.3 to 0.5 MPa.

7. The method for producing a strontium europium nitride solid solution powder according to claim 2, wherein: the strontium europium nitride solid solution powder obtained in the step S3 is coarse particle powder, and the coarse particle powder is transferred into a glove box with water and oxygen content less than 1ppm, and is crushed by a crusher to obtain fine particle powder with different mesh numbers.

Technical Field

The invention relates to the technical field of chemical industry, in particular to strontium-europium nitride solid solution powder and a preparation method thereof.

Background

At present, with the development of new material technology, strontium europium nitride solid solution powder with controllable component structure is flourishing in the industry gradually, and shows good market prospect, and the strontium europium nitride solid solution can be used as a raw material in the fields of LED fluorescent powder, ceramic pigment and the like.

The reaction of metallic strontium with nitrogen started at a temperature of 200 c, but the weight increase was slight, and the reaction was stopped until the latter, because the reaction was difficult to proceed due to the formation of an N-Sr film, and the reaction was difficult to proceed even if the temperature was maintained at 650 c for 50 hours or more, and a large flow of nitrogen gas was introduced. At this time, if a small amount of impurity gas such as: moisture, carbon dioxide, oxygen and the like can be completely absorbed by metal at high temperature, the oxygen content of the finally obtained product is also very high, and the reaction time needs to last for more than 100 hours when the reaction is complete; therefore, the product obtained by the preparation method in the prior art has low purity and long time consumption, and simultaneously, a large amount of nitrogen is consumed, so that the production requirement cannot be met.

Disclosure of Invention

Aiming at the problems, the invention provides the strontium-europium nitride solid solution powder which has the advantages of no need of adding any additive, simple and convenient operation, higher purity, higher synthesis efficiency, less consumption of hydrogen and nitrogen, higher production efficiency, simpler process control, short hydrogenation and nitridation time, less energy consumption and short production period, and the preparation method thereof.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the strontium-europium nitride solid solution powder is prepared by crushing a strontium-europium nitride solid solution, wherein the chemical general formula of the strontium-europium nitride solid solution is (Sr)_1-xEu_x)₂N; wherein x is more than 0 and less than or equal to 0.02.

A preparation method of strontium-europium nitride solid solution powder comprises the following steps:

s1, weighing strontium metal Sr with the purity of more than or equal to 99.99% and europium metal Eu with the purity of more than or equal to 99.99%, placing the strontium metal Sr and the europium metal Eu into a vacuum smelting furnace of an alumina crucible, vacuumizing, washing the furnace, introducing argon as protective gas, melting at 700-800 ℃, and pouring into a casting mold to obtain an alloy cast ingot;

s2, cleaning the surface of the alloy ingot obtained in the step S1, placing the alloy ingot in a hydrogen crushing furnace, washing the furnace with argon, introducing hydrogen with the purity of more than or equal to 99.99%, heating to 200-300 ℃ to crush the alloy ingot, vacuumizing, heating to 550 ℃ to dehydrogenate to obtain alloy coarse powder;

s3, reducing the temperature of the hydrogen crushing furnace to be below 150 ℃, introducing nitrogen obtained by vaporizing liquid nitrogen with the purity of more than or equal to 99.999 percent into the hydrogen crushing furnace, gradually heating to 450 ℃, and keeping the temperature for 5 hours to obtain the strontium-europium nitride solid solution powder.

Further, in the step S1, the furnace is washed three times during the vacuuming and furnace washing.

Further, in the step S2, the cleaning of the surface of the alloy ingot is mainly used to remove an oxide layer on the surface of the alloy ingot and slag-forming impurities generated in the melting process, and then the surface of the alloy ingot is polished to completely remove the oxide layer remaining on the surface.

Further, in the step S2, the furnace is washed three times with argon gas.

Further, in the step S3, the pressure in the hydrogen decrepitation furnace is maintained at 0.3 to 0.5 Mpa.

Further, the strontium europium nitride solid solution powder obtained in step S3 is coarse-grained powder, and the coarse-grained powder is transferred into a glove box with water and an oxygen content of less than 1ppm, and is pulverized by a pulverizer to obtain fine-grained powder with different mesh numbers.

Compared with the prior art, the invention has the advantages and positive effects that:

1. the strontium-europium nitride solid solution powder prepared by the invention has higher purity, and the main reasons are as follows:

(1) the purity of the raw materials is high, in the raw materials used by the invention, the purity of metal strontium is 99.99 percent, the purity of metal europium is 99.99 percent, argon is vaporized by liquid argon to be used as shielding gas, the purity reaches more than 99.999 percent, nitrogen is vaporized by liquid nitrogen, the purity is more than 99.999 percent, and the purity of hydrogen reaches 99.99 percent;

(2) the process is strictly controlled, the invention firstly melts and casts the metal strontium and the metal europium into the alloy of strontium europium, removes the oxide layer on the metal surface of the ingot and the slag-making impurities generated in the smelting process, and then continues to polish the metal surface before entering the hydrogen furnace to completely remove the oxide layer remained on the surface;

(3) the introduction of a hydrogen crushing process can avoid the contact of large products with gases such as oxygen, moisture and the like in the later process, and the hydrogen can reduce part of incompletely oxidized metals to further reduce the oxygen content;

(4) the coarse powder is treated in a glove box with water and oxygen content less than 1ppm in the post-treatment process, and is crushed by a crusher coated with a high-hardness wear-resistant tungsten carbide coating, so that the introduction of mechanical impurities is further avoided in the process.

2. After various metals are smelted, various raw materials are uniformly distributed in a molten state, namely, the raw materials are mixed from the atom level, and then the molten raw materials are subjected to hydrogen cracking, nitriding and other processes, so that the uniformity and consistency of the products obtained in the whole process are high.

3. The invention uses a static high-pressure method to prepare the nitride solid solution powder, does not need a large amount of nitrogen gas flow, and can avoid the situation that impurities in the product are uncontrollable due to accumulation of a small amount of impurity gas mixed in the nitrogen.

4. The strontium-europium nitride solid solution powder is subjected to a hydrogen crushing link, large and small or more or less cracks are arranged on the surface and inside of the metal, and the cracks form a channel for nitrogen to enter the metal when the nitride solid solution is synthesized in the later period, so that the reaction is easier to carry out, and the small cracks provide assistance for obtaining powder with different meshes by mechanical crushing in the later period.

5. The temperature required by the final synthesis is lower, the highest temperature only needs 450 ℃, and compared with other preparation methods, the preparation method is simpler and faster in preparation operation.

6. Sr prepared from strontium europium nitride solid solution powder in the invention_0.94Ca_0.045Eu_0.015AlSiN₃Eu red phosphor, the emission intensity ratio of which is directly strontium nitride, europium nitride and nitrogenThe phosphor intensity obtained by silicon and aluminum nitride is higher, and the reason is from three aspects:

(1) in the raw material for synthesizing the fluorescent powder, strontium and europium are uniformly distributed on the atomic layer surface because MAlSiN₃(M ═ Ca, Sr) phosphor in which Eu occupies M²⁺Compared with the preparation scheme of strontium nitride, calcium nitride and europium nitride, the preparation method only mixes at the molecular level, so that the mixing of Sr and Eu from the small particle molecular level is improved to the mixing at the atomic level, the diffusion distance of Eu replacing Sr atoms during sintering is greatly shortened, the Eu replacing Sr atoms can be uniformly distributed in the whole crystal, the reaction time can be reduced, and the brightness of the product is higher;

(2) europium nitride cannot be mechanically ground to a very fine size, which causes Eu ions to segregate more or less at different parts of a single particle of the phosphor, or on different particles, resulting in failure to exert optimum intensity of light emission.

(3) In the strontium europium nitride solid solution powder of the present invention, Eu ions are first solid-dissolved in divalent form at the position of M, and MAlSiN₃The luminescence of the phosphor is Eu²⁺Can eliminate the existence of Eu due to incomplete reduction in the preparation process of the fluorescent powder³⁺Leading to a case where the light emission luminance is weakened.

7. The nitride formed by the metal strontium and the strontium in the invention is a divalent ion compound, and M is used²⁺And europium nitride forms a trivalent ionic compound, in the form of Eu³⁺Because Eu ions enter Sr positions in the strontium europium nitride solid solution powder, the strontium europium nitride solid solution powder becomes a strontium-based solid solution, and the stability of the strontium europium nitride solid solution powder is better.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is an XRD pattern of strontium europium nitride powders obtained in examples 1-5;

FIG. 2 is a graph showing emission spectra of three phosphor samples in comparative examples 1 to 3.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived from the embodiments of the present invention by a person skilled in the art without any creative effort, should be included in the protection scope of the present invention.

The strontium metal used in the examples and the comparative examples of the present invention has a purity of 99.99%, the europium metal has a purity of 99.99%, the silicon nitride is UBE, the product of E10, the aluminum nitride, the strontium nitride and the strontium nitride are sigma raw materials, nitrogen is vaporized by liquid nitrogen of 99.999%, argon is vaporized by liquid argon of 99.999%, and hydrogen is hydrogen of 99.99% purity.

Example 1: preparation of (Sr)_0.995Eu_0.005)₂N；

991.4g of metal strontium and 8.6g of metal europium are weighed, the furnace is washed three times by argon in a vacuum melting furnace, argon is flushed to 80KPa, the mixture is heated to 700 ℃ to be melted into a slurry state, and an alloy ingot is obtained by pouring and cooling. Cleaning the surface of an alloy ingot, putting the alloy ingot into a hydrogen breaking furnace, vacuumizing for three times, heating to 200 ℃ for activation, introducing hydrogen, heating to 300 ℃, keeping the temperature for 4 hours, heating to 550 ℃, vacuumizing to remove the hydrogen, cooling to below 150 ℃ after the vacuum degree is less than 40pa (shown by a meter), introducing nitrogen to 0.3MPa, gradually heating to 450 ℃, maintaining the gas pressure at 0.5MPa, keeping the temperature for 4 hours, and showing that the pressure in 5min is not reduced, thus finishing the reaction. And then cooling to a room temperature state, charging the materials by using a stainless steel tank, moving the materials into a glove box with water and oxygen content less than 1ppm, crushing the materials by using a crusher, and sieving the materials to obtain a powder sample with the granularity of 1-150 meshes, wherein the sample with the serial number S-01 is used for XRD detection.

Example 2: preparation of (Sr)_0.99Eu_0.01)₂N；

982.8g and 17.2g of metal strontium are weighed, the furnace is washed by argon gas for three times in a vacuum smelting furnace, argon gas is filled to 80KPa, the mixture is heated to 750 ℃ and melted into a slurry state, and an alloy ingot is obtained by pouring and cooling. Cleaning the surface of an alloy ingot, putting the alloy ingot into a hydrogen breaking furnace, vacuumizing for three times, heating to 220 ℃ for activation, introducing hydrogen, heating to 300 ℃ for heat preservation for 4 hours, heating to 550 ℃, vacuumizing for removing hydrogen, cooling to below 150 ℃ after the vacuum degree is less than 40pa (shown by an instrument), introducing nitrogen to 0.4MPa, gradually heating to 450 ℃, maintaining the gas pressure at 0.5MPa, preserving the heat for 4 hours, and indicating that the pressure in 5min is not reduced, thus finishing the reaction. And then cooling to a room temperature state, charging by using a stainless steel tank, transferring into a glove box with water and oxygen content less than 1ppm, crushing by using a crusher, sieving to obtain a powder sample with the granularity of 1-150 meshes, and performing XRD detection by using a serial number S-02.

Example 3: preparation of (Sr)_0.985Eu_0.015)₂N；

974.3g of metal strontium and 25.7g of metal europium are weighed, the furnace is washed by argon for three times in a vacuum melting furnace, argon is filled to 80KPa, the mixture is heated to 780 ℃ and melted into a slurry state, and an alloy ingot is obtained by pouring and cooling. Cleaning the surface of an alloy ingot, putting the alloy ingot into a hydrogen breaking furnace, vacuumizing for three times, heating to 220 ℃ for activation, introducing hydrogen, heating to 300 ℃ for heat preservation for 4 hours, heating to 550 ℃, vacuumizing for removing hydrogen, cooling to below 150 ℃ after the vacuum degree is less than 40pa (shown by an instrument), introducing nitrogen to 0.4MPa, gradually heating to 450 ℃, maintaining the gas pressure at 0.5MPa, preserving the heat for 4 hours, and indicating that the pressure in 5min is not reduced, thus finishing the reaction. And then cooling to a room temperature state, charging by using a stainless steel tank, transferring into a glove box with water and oxygen content less than 1ppm, crushing by using a crusher, sieving to obtain a powder sample with the granularity of 1-150 meshes, and performing XRD detection on the powder sample with the serial number S-03.

Example 4: preparation of (Sr)_0.984Eu_0.016)₂N；

972.6g of metal strontium and 27.4g of metal europium are weighed, the furnace is washed three times by argon in a vacuum melting furnace, argon is flushed to 80KPa, the mixture is heated to 780 ℃ and melted into a slurry state, and an alloy ingot is obtained by pouring and cooling. Cleaning the surface of an alloy ingot, putting the alloy ingot into a hydrogen breaking furnace, vacuumizing for three times, heating to 220 ℃ for activation, introducing hydrogen, heating to 300 ℃ for heat preservation for 4 hours, heating to 550 ℃, vacuumizing for removing hydrogen, cooling to below 150 ℃ after the vacuum degree is less than 40pa (shown by an instrument), introducing nitrogen to 0.4MPa, gradually heating to 450 ℃, maintaining the gas pressure at 0.5MPa, preserving the heat for 4 hours, and indicating that the pressure in 5min is not reduced, thus finishing the reaction. And then cooling to a room temperature state, charging by using a stainless steel tank, transferring into a glove box with water and oxygen content less than 1ppm, crushing by using a crusher, sieving to obtain a powder sample with the granularity of 1-150 meshes, and performing XRD detection on the powder sample with the serial number S-04.

Example 5: preparation of (Sr)_0.98Eu_0.02)₂N；

858.7g of metal strontium and 41.3g of metal europium are weighed, the furnace is washed three times by argon in a vacuum smelting furnace, argon is flushed to 80KPa, the mixture is heated to 800 ℃ to be melted into a slurry state, and an alloy ingot is obtained by pouring and cooling. Cleaning the surface of an alloy ingot, putting the alloy ingot into a hydrogen breaking furnace, vacuumizing for three times, heating to 220 ℃ for activation, introducing hydrogen, heating to 300 ℃ for heat preservation for 4 hours, heating to 550 ℃, vacuumizing for removing hydrogen, cooling to below 150 ℃ after the vacuum degree is less than 40pa (shown by an instrument), introducing nitrogen to 0.4MPa, gradually heating to 450 ℃, maintaining the gas pressure at 0.5MPa, preserving the heat for 4 hours, and indicating that the pressure in 5min is not reduced, thus finishing the reaction. And then cooling to a room temperature state, charging by using a stainless steel tank, transferring into a glove box with water and oxygen content less than 1ppm, crushing by using a crusher, sieving to obtain a powder sample with the granularity of 1-150 meshes, and performing XRD detection by using a serial number S-05.

The high-purity strontium europium nitride synthesized by the invention is a pure solid solution and is not three mechanical mixtures of strontium nitride, calcium nitride and europium nitride, and as seen from figure 1, the diffraction peak of the solid solution of the invention is similar to that of standard card pure strontium nitride and can move to a large angle along with the increase of the Eu amount, because the Eu is increased²⁺The ion radius of (2) is large.

Comparative example 1:

the synthetic ingredient is Sr_0.94Ca_0.045Eu_0.015AlSiN₃Eu phosphor. Weighing implementation169.28g of high-purity strontium-europium nitride solid solution powder of example 3 was added with 4.44gCa g₃N₄，93.52gSi₃N₄81.98g AlN, and then put into a molybdenum crucible after being mixed uniformly, and the mixture is kept for 4 hours under the nitrogen atmosphere in a carbon tube furnace, the temperature of 1850 ℃ and the pressure of 1MPa to obtain a fluorescent powder sample, the number of which is D-01.

Comparative example 2:

the synthetic ingredient is Sr_0.94Ca_0.044Eu_0.016AlSiN₃Eu phosphor. 169.59g of the high-purity strontium-europium nitride solid solution powder obtained in example 4 was weighed and added to 4.34gCa₃N₄，93.52gSi₃N₄81.98g AlN, and then put into a molybdenum crucible after being mixed evenly, and the mixture is kept for 4 hours under the nitrogen atmosphere in a carbon tube furnace, the temperature of 1850 ℃ and the pressure of 1MPa, and a fluorescent powder sample is obtained, and is numbered D-02.

Comparative example 3:

the synthetic ingredient is Sr_0.94Ca_0.045Eu_0.015AlSiN₃Eu phosphor. Weighing 164.73gSr₂N，4.44gCa₃N₄，4.98gEuN，93.52gSi₃N₄81.98g AlN, and then put into a molybdenum crucible after being mixed uniformly, and the mixture is kept for 4 hours under the nitrogen atmosphere in a carbon tube furnace, the temperature of 1850 ℃ and the pressure of 1MPa to obtain a fluorescent powder sample, and the number is D-03.

It can be seen from fig. 2 that the emission intensity of the phosphor powder synthesized by using the strontium-europium solid solution powder as a raw material is higher than that of the phosphor powder synthesized by directly using a plurality of single raw materials, which fully illustrates that the strontium-europium solid solution powder prepared by the invention has better mixing uniformity.

The invention has the following beneficial effects:

1. the strontium-europium nitride solid solution powder prepared by the invention has higher purity, and the main reasons are as follows:

(1) the purity of the raw materials is high, in the raw materials used by the invention, the purity of metal strontium is 99.99 percent, the purity of metal europium is 99.99 percent, argon is vaporized by liquid argon to be used as shielding gas, the purity reaches more than 99.999 percent, nitrogen is vaporized by liquid nitrogen, the purity is more than 99.999 percent, and the purity of hydrogen reaches 99.99 percent;

(2) the process is strictly controlled, the invention firstly melts and casts the metal strontium and the metal europium into the alloy of strontium europium, removes the oxide layer on the metal surface of the ingot and the slag-making impurities generated in the smelting process, and then continues to polish the metal surface before entering the hydrogen furnace to completely remove the oxide layer remained on the surface;

(3) the introduction of a hydrogen crushing process can avoid the contact of large products with gases such as oxygen, moisture and the like in the later process, and the hydrogen can reduce part of incompletely oxidized metals to further reduce the oxygen content;

(4) the coarse powder is treated in a glove box with water and oxygen content less than 1ppm in the post-treatment process, and is crushed by a crusher coated with a high-hardness wear-resistant tungsten carbide coating, so that the introduction of mechanical impurities is further avoided in the process.

2. After various metals are smelted, various raw materials are uniformly distributed in a molten state, namely, the raw materials are mixed from the atom level, and then the molten raw materials are subjected to hydrogen cracking, nitriding and other processes, so that the uniformity and consistency of the products obtained in the whole process are high.

3. The invention uses a static high-pressure method to prepare the nitride solid solution powder, does not need a large amount of nitrogen gas flow, and can avoid the situation that impurities in the product are uncontrollable due to accumulation of a small amount of impurity gas mixed in the nitrogen.

4. The strontium-europium nitride solid solution powder is subjected to a hydrogen crushing link, large and small or more or less cracks are arranged on the surface and inside of the metal, and the cracks form a channel for nitrogen to enter the metal when the nitride solid solution is synthesized in the later period, so that the reaction is easier to carry out, and the small cracks provide assistance for obtaining powder with different meshes by mechanical crushing in the later period.

5. The temperature required by the final synthesis is lower, the highest temperature only needs 450 ℃, but the reaction pressure is higher, the product can have incomplete reaction when the pressure is lower than 0.3MPa, and when the pressure is higher than 0.5MPa, the local temperature is too high to generate melting due to too high reaction speed, so that the reaction is not facilitated, and the preferable synthesis pressure is 0.3-0.5 MPa.

6. Sr prepared from strontium europium nitride solid solution powder in the invention_0.94Ca_0.045Eu_0.015AlSiN₃Eu red phosphor, whose emission intensity is higher than that obtained directly with strontium nitride, europium nitride, silicon nitride, aluminum nitride, for reasons derived from three aspects:

(1) in the raw material for synthesizing the fluorescent powder, strontium and europium are uniformly distributed on the atomic layer surface because MAlSiN₃(M ═ Ca, Sr) phosphor in which Eu occupies M²⁺Compared with the preparation scheme of strontium nitride, calcium nitride and europium nitride, the preparation method only mixes at the molecular level, so that the mixing of Sr and Eu from the small particle molecular level is improved to the mixing at the atomic level, the diffusion distance of Eu replacing Sr atoms during sintering is greatly shortened, the Eu replacing Sr atoms can be uniformly distributed in the whole crystal, the reaction time can be reduced, and the brightness of the product is higher;

(2) europium nitride cannot be mechanically ground to a very fine size, which causes Eu ions to segregate more or less at different parts of a single particle of the phosphor, or on different particles, resulting in failure to exert optimum intensity of light emission.

(3) In the strontium europium nitride solid solution powder of the present invention, Eu ions are first solid-dissolved in divalent form at the position of M, and MAlSiN₃The luminescence of the phosphor is Eu²⁺Can eliminate the existence of Eu due to incomplete reduction in the preparation process of the fluorescent powder³⁺Leading to a case where the light emission luminance is weakened.

7. The nitride formed by the metal strontium and the strontium in the invention is a divalent ion compound, and M is used²⁺And europium nitride forms a trivalent ionic compound, in the form of Eu³⁺Because Eu ions enter Sr positions in the strontium europium nitride solid solution powder, the strontium europium nitride solid solution powder becomes a strontium-based solid solution, and the stability of the strontium europium nitride solid solution powder is better.