CN112408455B - Calcium europium nitride solid solution powder and preparation method thereof - Google Patents
Calcium europium nitride solid solution powder and preparation method thereof Download PDFInfo
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- 239000000843 powder Substances 0.000 title claims abstract description 64
- 239000006104 solid solution Substances 0.000 title claims abstract description 41
- KPVUHKHVGKSEPB-UHFFFAOYSA-N calcium europium Chemical compound [Ca][Eu] KPVUHKHVGKSEPB-UHFFFAOYSA-N 0.000 title claims abstract description 39
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 239000011575 calcium Substances 0.000 claims abstract description 58
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 48
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 46
- 229910052751 metal Inorganic materials 0.000 claims abstract description 43
- 239000002184 metal Substances 0.000 claims abstract description 43
- 239000001257 hydrogen Substances 0.000 claims abstract description 38
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 38
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 35
- 239000000956 alloy Substances 0.000 claims abstract description 35
- 238000010438 heat treatment Methods 0.000 claims abstract description 35
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 34
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 31
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052786 argon Inorganic materials 0.000 claims abstract description 23
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 23
- 229910052693 Europium Inorganic materials 0.000 claims abstract description 20
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000003723 Smelting Methods 0.000 claims abstract description 15
- 239000007789 gas Substances 0.000 claims abstract description 14
- 238000004140 cleaning Methods 0.000 claims abstract description 9
- 238000005303 weighing Methods 0.000 claims abstract description 7
- 238000002844 melting Methods 0.000 claims abstract description 5
- 230000008018 melting Effects 0.000 claims abstract description 5
- 239000000126 substance Substances 0.000 claims abstract description 5
- 230000001681 protective effect Effects 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 25
- 230000008569 process Effects 0.000 claims description 20
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- 229910052760 oxygen Inorganic materials 0.000 claims description 14
- 239000012535 impurity Substances 0.000 claims description 11
- 239000007788 liquid Substances 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 230000008016 vaporization Effects 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 6
- 239000011362 coarse particle Substances 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 2
- 239000010419 fine particle Substances 0.000 claims description 2
- 239000002893 slag Substances 0.000 claims 1
- 150000002431 hydrogen Chemical class 0.000 abstract description 9
- -1 moisture Substances 0.000 description 16
- 238000006243 chemical reaction Methods 0.000 description 12
- 238000001816 cooling Methods 0.000 description 12
- PSBUJOCDKOWAGJ-UHFFFAOYSA-N azanylidyneeuropium Chemical compound [Eu]#N PSBUJOCDKOWAGJ-UHFFFAOYSA-N 0.000 description 10
- 239000002994 raw material Substances 0.000 description 10
- 238000002156 mixing Methods 0.000 description 8
- 238000011010 flushing procedure Methods 0.000 description 6
- 150000004767 nitrides Chemical class 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 5
- 230000008901 benefit Effects 0.000 description 5
- 238000004321 preservation Methods 0.000 description 5
- 230000004913 activation Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 238000004020 luminiscence type Methods 0.000 description 4
- 239000002052 molecular layer Substances 0.000 description 4
- 238000007873 sieving Methods 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 230000002194 synthesizing effect Effects 0.000 description 4
- 238000009834 vaporization Methods 0.000 description 4
- 229910052581 Si3N4 Inorganic materials 0.000 description 3
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 238000004886 process control Methods 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910001265 Eu alloy Inorganic materials 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000010297 mechanical methods and process Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000005121 nitriding Methods 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 238000005498 polishing Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000000295 emission spectrum Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000320 mechanical mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F17/00—Compounds of rare earth metals
- C01F17/30—Compounds containing rare earth metals and at least one element other than a rare earth metal, oxygen or hydrogen, e.g. La4S3Br6
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/0612—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with alkaline-earth metals, beryllium or magnesium
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F17/00—Compounds of rare earth metals
- C01F17/10—Preparation or treatment, e.g. separation or purification
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Analytical Chemistry (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Luminescent Compositions (AREA)
Abstract
The invention discloses a calcium europium nitride solid solution powder and a preparation method thereof, wherein the calcium europium nitride solid solution powder is prepared by crushing a calcium europium nitride solid solution, the chemical general formula of the calcium europium nitride solid solution is (Ca 1‑xEux)3N2; wherein x is more than 0 and less than or equal to 0.025. The preparation method comprises the following steps of S1, weighing metal calcium Ca and metal europium Eu, vacuum smelting the calcium Ca and the metal europium Eu in a furnace, vacuumizing and cleaning the furnace, introducing argon as protective gas, melting, pouring the molten calcium Ca and the metal europium Eu in an ingot mould to obtain an alloy ingot, S2, cleaning the surface of the alloy ingot, placing the alloy ingot in a hydrogen crushing furnace, introducing hydrogen, heating to crush the alloy ingot, heating and dehydrogenating to obtain alloy coarse powder, S3, reducing the temperature of the hydrogen crushing furnace to be lower than 300 ℃, introducing nitrogen into the hydrogen crushing furnace, gradually heating to 460 ℃, preserving the temperature for 180min, and then heating to 610 ℃ and preserving the temperature for 300min to obtain the calcium europium nitride solid solution powder.
Description
Technical Field
The invention relates to the technical field of chemical industry, in particular to calcium europium nitride solid solution powder and a preparation method thereof.
Background
At present, with the development of new material technology, the calcium europium nitride solid solution powder with controllable component structure is gradually increased in the industry, and has good market prospect, and the calcium europium nitride solid solution can be used as raw materials in the fields of LED fluorescent powder, ceramic pigment and the like.
The reaction of metallic calcium with nitrogen starts at a temperature of 360 c, but the weight increase is small and the reaction is stopped until the latter stage, because the reaction is difficult to proceed even when it is kept at 650 c for more than 50 hours and a large flow of nitrogen is introduced. If a small amount of impurity gas such as: moisture, carbon dioxide, oxygen and the like are all absorbed by metals at high temperature, the oxygen content of the finally obtained product is high, and the reaction time is required to last more than 100 hours for complete reaction; therefore, the purity of the product obtained by the preparation method in the prior art is low, the time consumption is long, and meanwhile, 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 calcium europium nitride solid solution powder which has the advantages of no need of adding any additive, simple operation, higher purity, higher synthesis efficiency, less hydrogen and nitrogen consumption, 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 above object, the technical scheme of the present invention is as follows:
A calcium europium nitride solid solution powder is prepared by crushing a calcium europium nitride solid solution, wherein the chemical general formula of the calcium europium nitride solid solution is (Ca 1-xEux)3N2; wherein x is more than 0 and less than or equal to 0.025.
A preparation method of calcium europium nitride solid solution powder comprises the following steps:
S1, weighing metal calcium Ca with the purity of more than or equal to 99.99 percent and metal europium Eu with the purity of more than or equal to 99.99 percent, placing the metal calcium Ca and the metal europium Eu into a vacuum smelting furnace of an alumina crucible together, vacuumizing and washing the furnace, introducing argon as a protective gas, melting at 750-820 ℃, and pouring the molten argon into an ingot mould to obtain an alloy ingot;
s2, after surface cleaning is carried out on the alloy cast ingot obtained in the step S1, placing the alloy cast ingot into a hydrogen crushing furnace, washing the furnace with argon, introducing hydrogen with the purity of more than or equal to 99.99%, heating to 220-360 ℃ to crush the alloy cast ingot, vacuumizing, heating to 580 ℃ and dehydrogenating to obtain alloy coarse powder;
S3, reducing the temperature of the hydrogen crushing furnace to below 300 ℃, introducing nitrogen obtained by vaporizing liquid nitrogen with purity not less than 99.999% into the hydrogen crushing furnace, gradually heating to 460 ℃ for 180min, and then heating to 610 ℃ for 300min to obtain the calcium europium nitride solid solution powder.
Further, in the step S1, the furnace is washed three times during the vacuum furnace washing.
Further, in the step S2, the surface cleaning of the alloy ingot is mainly used for removing the oxide layer on the surface of the alloy ingot and slag-forming impurities generated in the smelting process, and then the surface of the alloy ingot is polished to thoroughly remove the residual oxide layer on the surface of the alloy ingot.
Further, in the step S2, the furnace is flushed with argon three times.
Further, in the step S3, the pressure in the hydrogen crushing furnace is kept at 0.5 to 0.6MPa.
Further, the solid solution powder of the calcium europium nitride obtained in the step S3 is coarse particle powder, the coarse particle powder is moved into a glove box with water and oxygen content of less than 1ppm, and the fine particle powder with different meshes is obtained through crushing by a crusher.
Compared with the prior art, the invention has the advantages and positive effects that:
1. The purity of the calcium europium nitride solid solution powder prepared by the invention is higher, and the main reason is that:
(1) The raw materials used in the invention have high purity, the purity of metal calcium is 99.99%, the purity of metal europium is 99.99%, the purity of argon gas is over 99.999% by liquid argon vaporization, the purity of nitrogen gas is over 99.999% by liquid nitrogen vaporization, and the purity of hydrogen gas is up to 99.99%;
(2) The process control is strict, the invention firstly melts metal calcium and metal europium into cast ingot to form calcium europium alloy, removes oxide layer on the metal surface of the cast ingot in the smelting process and slag-forming impurities generated in the smelting process, and then continues polishing the metal surface before entering a hydrogen breaking furnace to thoroughly remove the oxide layer remained on the surface;
(3) The hydrogen crushing process is introduced, so that the massive products can be prevented from contacting gases such as oxygen, moisture and the like in the later period, and the hydrogen can reduce partial incompletely oxidized metals, so that the oxygen content is further reduced;
(4) The post-treatment process of the coarse powder is carried out in a glove box with water and oxygen content less than 1ppm, and is finished by using a pulverizer 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 the smelting process, various raw materials are uniformly distributed in a molten state, namely, are mixed from an atomic layer, and then are subjected to the processes of hydrogen breaking, nitriding and the like, so that the uniformity and consistency of the product obtained in the whole process are higher.
3. The method adopts a static high-pressure method to prepare the nitride solid solution powder, does not need a large amount of nitrogen flow, and can avoid the occurrence of uncontrollable impurity in the product caused by accumulation of a small amount of impurity gas mixed in the nitrogen.
4. The calcium europium nitride solid solution powder is subjected to a hydrogen crushing link, cracks with more or less sizes exist on the surface and inside of metal, the cracks form channels for nitrogen to enter the metal in the later process of synthesizing the nitride solid solution, so that the reaction is easier to carry out, and in addition, the tiny cracks also promote the powder arches with different mesh numbers obtained by later mechanical crushing.
5. The solid solution powder of calcium europium nitride of the present invention (Ca 0.98Eu0.02)AlSiN3: eu red phosphor, which has higher emission intensity than phosphor obtained directly from calcium nitride, europium nitride, silicon nitride, aluminum nitride, for three reasons:
(1) In the raw materials for synthesizing the fluorescent powder, calcium and europium are uniformly distributed on an atomic layer, because Eu occupies the position of Ca in the CaAlSiN 3 fluorescent powder, compared with the preparation scheme of calcium nitride and europium nitride which is only mixed on a molecular layer, the mixing of Ca and Eu from a small particle molecular layer is improved to the mixing on the atomic layer, the diffusion distance of Eu for replacing Ca atoms during sintering is greatly shortened, the Eu 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 crushed to a very small size by a mechanical method, so that Eu ions can be segregated at different positions of single particles of fluorescent powder or more or less on different particles, and the luminous brightness cannot be exerted to the optimal intensity.
(3) In the calcium europium nitride solid solution powder, eu ions are firstly dissolved in a divalent form at the position of Ca, and the luminescence of the CaAlSiN 3 fluorescent powder is that of Eu 2+, so that the condition that the luminescence brightness is reduced due to the fact that the reduction is incomplete in the preparation process of the fluorescent powder and Eu 3+ exists can be eliminated.
6. In the invention, the metal calcium and the nitride formed by the calcium are divalent ion compounds, the divalent ion compounds exist in the valence state of Ca 2+, the trivalent ion compounds exist in the europium nitride, and Eu 3+ exists.
7. The invention has the advantages that the temperature required during the final synthesis is lower, the highest temperature only needs 610 ℃, and compared with other preparation methods, the preparation operation is simpler and faster.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is an XRD pattern of the calcium europium nitride powders prepared in examples 1-4;
FIG. 2 is a graph showing emission spectra of two phosphor samples of comparative examples 1-2.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, modifications, equivalents, improvements, etc., which are apparent to those skilled in the art without the benefit of this disclosure, are intended to be included within the scope of this invention.
The metal calcium used in the embodiment and the comparative example of the invention has the purity of 99.99 percent, the metal europium has the purity of 99.99 percent, the silicon nitride is UBE, E10 products, the aluminum nitride, the calcium nitride and the calcium nitride are sigma raw materials, the nitrogen is vaporized by liquid nitrogen with the purity of 99.999 percent, the argon is vaporized by liquid argon with the purity of 99.999 percent, and the hydrogen has the purity of 99.99 percent.
Example 1: preparation (Ca 0.995Eu0.005)3N2;
Weighing 981.3g of calcium metal and 1.87g of europium metal, flushing the furnace with argon for three times in a vacuum smelting furnace, flushing the argon to 80KPa, heating to 780 ℃ to be molten into a slurry state, pouring and cooling to obtain an alloy cast ingot. Cleaning the surface of an alloy cast ingot, then placing the alloy cast ingot into a hydrogen breaking furnace, vacuumizing for three times, heating to 220 ℃ for activation, introducing hydrogen, heating to 360 ℃ for heat preservation for 4 hours, vacuumizing for removing hydrogen, heating to 580 ℃, cooling to below 300 ℃ after the vacuum degree is less than 40pa (displayed by an instrument), starting to introduce nitrogen to 0.5MPa, gradually heating to 460 ℃, maintaining the gas pressure to 0.5MPa, preserving heat for 3 hours, then heating to 610 ℃ for heat preservation for 5 hours, and displaying that the pressure meter is not falling within 5 minutes, wherein the reaction is finished. Then cooling to room temperature, charging with a stainless steel tank, transferring into a glove box with water and oxygen content less than 1ppm, crushing with a crusher, sieving to obtain 1-150 mesh powder sample, and performing XRD detection with the number S-1.
Example 2: preparation (Ca 0.985Eu0.015)3N2;
Weighing 945.3g of calcium metal and 54.7g of europium metal, flushing the furnace with argon three times in a vacuum smelting furnace, flushing the argon to 80KPa, heating to 800 ℃ to be molten into a slurry state, pouring and cooling to obtain an alloy cast ingot. Cleaning the surface of an alloy cast ingot, then placing the alloy cast ingot into a hydrogen breaking furnace, vacuumizing for three times, heating to 220 ℃ for activation, introducing hydrogen, heating to 360 ℃ for heat preservation for 4 hours, vacuumizing for removing hydrogen, heating to 580 ℃, cooling to below 300 ℃ after the vacuum degree is less than 40pa (shown by an instrument), starting to introduce nitrogen to 0.55MPa, gradually heating to 460 ℃, maintaining the gas pressure to 0.5MPa, preserving heat for 4 hours, then heating to 610 ℃ for 5 hours, and displaying that the pressure meter is not falling within 5 minutes, wherein the reaction is finished. Then cooling to room temperature, charging with a stainless steel tank, transferring into a glove box with water and oxygen content less than 1ppm, crushing with a crusher, sieving to obtain 1-150 mesh powder sample, and performing XRD detection with the number S-2.
Example 3: preparation (Ca 0.98Eu0.02)3N2;
728g of calcium metal and 72g of europium metal are weighed, the furnace is washed three times by argon in a vacuum smelting furnace, the argon is filled to 80KPa and heated to 810 ℃, the mixture is melted into a slurry state, and the alloy cast ingot is obtained through casting and cooling. Cleaning the surface of an alloy cast ingot, then placing the alloy cast ingot into a hydrogen breaking furnace, vacuumizing for three times, heating to 220 ℃ for activation, introducing hydrogen, heating to 360 ℃ for heat preservation for 4 hours, vacuumizing for removing hydrogen, heating to 580 ℃, cooling to below 300 ℃ after the vacuum degree is less than 40pa (shown by an instrument), starting to introduce nitrogen to 0.6MPa, gradually heating to 460 ℃, maintaining the gas pressure to 0.6MPa, preserving heat for 4 hours, then heating to 610 ℃ for 5 hours, and displaying that the pressure meter is not falling within 5 minutes, wherein the reaction is finished. Then cooling to room temperature, charging with a stainless steel tank, transferring into a glove box with water and oxygen content less than 1ppm, crushing with a crusher, sieving to obtain 1-150 mesh powder sample, and performing XRD detection with number S-3.
Example 4: preparation (Ca 0.975Eu0.035)3N2;
Weighing 911.2g of calcium metal and 88.8g of europium metal, flushing the furnace with argon for three times in a vacuum smelting furnace, flushing the argon to 80KPa, heating to 820 ℃, melting into a slurry state, pouring and cooling to obtain an alloy cast ingot. Cleaning the surface of an alloy cast ingot, then placing the alloy cast ingot into a hydrogen breaking furnace, vacuumizing for three times, heating to 220 ℃ for activation, introducing hydrogen, heating to 360 ℃ for heat preservation for 4 hours, vacuumizing for removing hydrogen, heating to 580 ℃, cooling to below 300 ℃ after the vacuum degree is less than 40pa (shown by an instrument), starting to introduce nitrogen to 0.6MPa, gradually heating to 460 ℃, maintaining the gas pressure to 0.6MPa, preserving heat for 4 hours, then heating to 610 ℃ for 5 hours, and displaying that the pressure meter is not falling within 5 minutes, wherein the reaction is finished. Then cooling to room temperature, charging with a stainless steel tank, transferring into a glove box with water and oxygen content less than 1ppm, crushing with a crusher, sieving to obtain 1-150 mesh powder sample, and performing XRD detection with number S-4.
The high-purity calcium europium nitride synthesized by the present invention is a solid solution pure substance, not two mechanical mixtures of calcium nitride and europium nitride, and as seen in FIG. 1, the diffraction peak of the solid solution of the present invention is similar to that of standard card pure calcium nitride, and moves to a small angle with increasing Eu amount, due to the larger ionic radius of Eu 2+.
Comparative example 1:
Weighing 153.04g of the high-purity calcium europium nitride solid solution powder of example 2 in a glove box, adding 140.28gSi 3N4 and 122.96gAlN, uniformly mixing by using a special mixing bag, filling into a molybdenum crucible, and preserving heat for 4 hours in a carbon tube furnace at 1760 ℃ under nitrogen atmosphere and under the pressure of 0.6MPa to obtain a fluorescent powder sample, numbering D-1, and testing spectral properties.
Comparative example 2:
146.2g of calcium nitride and 7.47g of europium nitride are weighed in a glove box, 140.28gSi 3N4 and 122.96gAlN are added, and after uniform mixing, the mixture is kept in a carbon tube furnace for 4 hours under the nitrogen atmosphere at the temperature of 1760 ℃ and the pressure of 0.6MPa, so as to obtain a fluorescent powder sample, the number is D-2, and the spectral performance is tested.
As can be seen from FIG. 2, the emission intensity of the fluorescent powder synthesized by using the calcium europium solid solution powder as a raw material is higher than that of the fluorescent powder synthesized by directly using a single raw material, which fully demonstrates that the mixing uniformity of the calcium europium solid solution powder prepared by the invention is better.
The beneficial effects of the invention are as follows:
1. The purity of the calcium europium nitride solid solution powder prepared by the invention is higher, and the main reason is that:
(1) The raw materials used in the invention have high purity, the purity of metal calcium is 99.99%, the purity of metal europium is 99.99%, the purity of argon gas is over 99.999% by liquid argon vaporization, the purity of nitrogen gas is over 99.999% by liquid nitrogen vaporization, and the purity of hydrogen gas is up to 99.99%;
(2) The process control is strict, the invention firstly melts metal calcium and metal europium into cast ingot to form calcium europium alloy, removes oxide layer on the metal surface of the cast ingot in the smelting process and slag-forming impurities generated in the smelting process, and then continues polishing the metal surface before entering a hydrogen breaking furnace to thoroughly remove the oxide layer remained on the surface;
(3) The hydrogen crushing process is introduced, so that the massive products can be prevented from contacting gases such as oxygen, moisture and the like in the later period, and the hydrogen can reduce partial incompletely oxidized metals, so that the oxygen content is further reduced;
(4) The post-treatment process of the coarse powder is carried out in a glove box with water and oxygen content less than 1ppm, and is finished by using a pulverizer 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 the smelting process, various raw materials are uniformly distributed in a molten state, namely, are mixed from an atomic layer, and then are subjected to the processes of hydrogen breaking, nitriding and the like, so that the uniformity and consistency of the product obtained in the whole process are higher.
3. The method adopts a static high-pressure method to prepare the nitride solid solution powder, does not need a large amount of nitrogen flow, and can avoid the occurrence of uncontrollable impurity in the product caused by accumulation of a small amount of impurity gas mixed in the nitrogen.
4. The calcium europium nitride solid solution powder is subjected to a hydrogen crushing link, cracks with more or less sizes exist on the surface and inside of metal, the cracks form channels for nitrogen to enter the metal in the later process of synthesizing the nitride solid solution, so that the reaction is easier to carry out, and in addition, the tiny cracks also promote the powder arches with different mesh numbers obtained by later mechanical crushing.
5. The solid solution powder of calcium europium nitride of the present invention (Ca 0.98Eu0.02)AlSiN3: eu red phosphor, which has higher emission intensity than phosphor obtained directly from calcium nitride, europium nitride, silicon nitride, aluminum nitride, for three reasons:
(1) In the raw materials for synthesizing the fluorescent powder, calcium and europium are uniformly distributed on an atomic layer, because Eu occupies the position of Ca in the CaAlSiN 3 fluorescent powder, compared with the preparation scheme of calcium nitride and europium nitride which is only mixed on a molecular layer, the mixing of Ca and Eu from a small particle molecular layer is improved to the mixing on the atomic layer, the diffusion distance of Eu for replacing Ca atoms during sintering is greatly shortened, the Eu 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 crushed to a very small size by a mechanical method, so that Eu ions can be segregated at different positions of single particles of fluorescent powder or more or less on different particles, and the luminous brightness cannot be exerted to the optimal intensity.
(3) In the calcium europium nitride solid solution powder, eu ions are firstly dissolved in a divalent form at the position of Ca, and the luminescence of the CaAlSiN 3 fluorescent powder is that of Eu 2+, so that the condition that the luminescence brightness is reduced due to the fact that the reduction is incomplete in the preparation process of the fluorescent powder and Eu 3+ exists can be eliminated.
6. In the invention, the metal calcium and the nitride formed by the calcium are divalent ion compounds, the divalent ion compounds exist in the valence state of Ca 2+, the trivalent ion compounds exist in the europium nitride, and Eu 3+ exists.
7. The invention has the advantages that the required temperature is lower in the final synthesis, the highest temperature is only 610 ℃, the reaction pressure is larger, the product can react incompletely when the pressure is lower than 0.5MPa, and the reaction speed is too high when the pressure is higher than 0.6MPa, and the local temperature is too high to generate melting, so that the reaction is not easy to carry out, so that the preferable synthesis pressure of the invention is 0.5-0.6 MPa.
Claims (4)
1. A preparation method of calcium europium nitride solid solution powder is characterized by comprising the following steps of: the method comprises the following steps:
S1, weighing metal calcium Ca with the purity of more than or equal to 99.99 percent and metal europium Eu with the purity of more than or equal to 99.99 percent, placing the metal calcium Ca and the metal europium Eu into a vacuum smelting furnace of an alumina crucible together, vacuumizing and washing the furnace, introducing argon as a protective gas, melting at 750-820 ℃, and pouring the molten argon into an ingot mould to obtain an alloy ingot;
s2, after surface cleaning is carried out on the alloy cast ingot obtained in the step S1, placing the alloy cast ingot into a hydrogen crushing furnace, washing the furnace with argon, introducing hydrogen with the purity of more than or equal to 99.99%, heating to 220-360 ℃ to crush the alloy cast ingot, vacuumizing, heating to 580 ℃ and dehydrogenating to obtain alloy coarse powder;
S3, reducing the temperature of the hydrogen crushing furnace to be lower than 300 ℃, introducing nitrogen obtained by vaporizing liquid nitrogen with the purity of more than or equal to 99.999% into the hydrogen crushing furnace, gradually heating to 460 ℃ for 180min, and then heating to 610 ℃ for 300min to obtain calcium europium nitride solid solution powder;
The calcium europium nitride solid solution powder obtained in the step S3 is coarse particle powder, the coarse particle powder is moved into a glove box with water and oxygen content less than 1ppm, and fine particle powder with different meshes is obtained through crushing by a crusher, wherein the chemical general formula of the calcium europium nitride solid solution is (Ca 1-xEux)3N2; wherein x is more than 0 and less than or equal to 0.025;
In the step S3, the pressure in the hydrogen crushing furnace is kept at 0.5-0.6 Mpa.
2. The method for producing a solid solution powder of calcium europium nitride according to claim 1, wherein: in the step S1, the furnace is washed three times during the vacuumizing furnace washing.
3. The method for producing a solid solution powder of calcium europium nitride according to claim 1, wherein: in the step S2, the surface of the alloy ingot is cleaned, which is mainly used for removing the oxide layer on the surface of the alloy ingot and slag forming impurities generated in the smelting process, and then the surface of the alloy ingot is polished to thoroughly remove the residual oxide layer on the surface of the alloy ingot.
4. The method for producing a solid solution powder of calcium europium nitride according to claim 1, wherein: in the step S2, the furnace is washed three times by argon.
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Non-Patent Citations (3)
| Title |
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| HDDR处理的不同钐含量Sm_2Fe_(17)型合金及氮化物的研究;孙继兵等;《稀有金属材料与工程》(第07期);第1061-1064页 * |
| 熔炼结合常压退火制备Ca-Al-Si-N:Eu荧光粉的研究;阿木古楞等;《内蒙古师范大学学报(自然科学汉文版)》(第02期);第206-209, 213页 * |
| 阿木古楞等.熔炼结合常压退火制备Ca-Al-Si-N:Eu荧光粉的研究.《内蒙古师范大学学报(自然科学汉文版)》 .2015,(第02期),第206-209,213页. * |
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