Silicon-germanium fluorescent powder prepared from germanium tetrafluoride and application of silicon-germanium fluorescent powder in LED (light-emitting diode)

Abstract

The invention discloses silicon-germanium fluorescent powder prepared from germanium tetrafluoride and application of the silicon-germanium fluorescent powder in an LED (light-emitting diode), and relates to the technical field of luminescent materials. The general chemical formula of the silicon-germanium fluorescent powder is Ca2 (Si < 0.6 > Ge < 0.4 >) O4: xLa < 3 + >, yEr < 3 + >, zYb < 3 + > (at) ZrO2-TiO2, wherein x is in the range of 0.015 to 0.017; y is in the range of 0.003 to 0.005; and z ranges from 0.025 to 0.03. By introducing ytterbium ions, lanthanum ions and other ions and the ZrO2-TiO2 coating layer, the fluorescence lifetime, the thermal stability and the chroma stability of the silicon-germanium fluorescent powder are effectively improved; and the silane coupling agent KH-570 is used for surface modification and fluidized bed grading treatment, so that the fluorescence lifetime, the thermal stability, the chroma stability and the moisture resistance of the silicon-germanium fluorescent powder are further improved. Therefore, the silicon-germanium fluorescent powder disclosed by the invention has a wider application prospect in the LED.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to a silicon-germanium phosphor prepared using germanium tetrafluoride and its application in LEDs. Background Technology

[0002] White light-emitting diodes (LEDs), as a new generation of lighting source, are widely used in general lighting, automotive headlights, indicator displays, and other fields due to their advantages such as long lifespan, environmental friendliness, and high luminous efficiency. Among these, phosphors, as key components in LED lighting systems, play an indispensable role in achieving efficient white light emission, optimizing spectral distribution, and improving light quality. However, currently widely used LED phosphor systems, such as yttrium aluminum garnet (YAG:Ce),... 3+ Although phosphors based on light have been successfully applied to commercial white LEDs, they mainly emit light in the yellow region, resulting in problems such as high color temperature and low color rendering index in the white light produced, which cannot meet the growing demand for high-quality lighting.

[0003] To address the aforementioned issues, existing technologies propose Dy... 3+ Doping and other methods have effectively improved the color rendering index of phosphors. However, phosphors still suffer from short fluorescence lifetimes and a significant decrease in emission frequency with increasing temperature in practical applications. Therefore, the fluorescence lifetime, thermal stability, and chromaticity stability of phosphors need further improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a silicon-germanium phosphor prepared using germanium tetrafluoride and its application in LEDs, thereby solving the following technical problems: Existing phosphors still suffer from short fluorescence lifetime and poor thermal and color stability.

[0005] The objective of this invention can be achieved through the following technical solutions: A silicon-germanium phosphor prepared using germanium tetrafluoride, the general chemical formula of which is Ca2(Si) fluoride. 0.6 Ge 0.4 O4: xLa 3+ yEr 3+ zYb 3+ @ZrO2-TiO2.

[0006] Preferably, x is 0.015-0.017; The value of y is 0.003-0.005; The value of z is 0.025-0.03.

[0007] Preferably, the silicon-germanium phosphor is prepared as follows: S1: Add anhydrous ethanol to a reactor equipped with a hydrofluoric acid absorption device at 0℃, then slowly introduce germanium tetrafluoride and stir for 30-50 min to obtain a mixed solution. S2: Add nano-silica, lanthanum oxide, polyvinylpyrrolidone, and mixed solution sequentially to a ball mill jar and stir for 10-20 min. Then add calcium carbonate and zirconium oxide balls, seal immediately, and purge with nitrogen. Then ball mill at 390-410 r / min at 0-5℃ for 7.8-8.2 h. After drying and grinding, pass through a 200-mesh sieve to obtain a mixed powder. S3: The mixed powder is heated to 300-320℃ and held for 30-40 min in a mixed atmosphere of oxygen and argon, then heated to 800-850℃ and held for 2-2.2 h. After cooling, the lanthanum-doped silica-germanate precursor is obtained. S4: Add erbium nitrate pentahydrate, ytterbium nitrate hexahydrate, and lanthanum-doped silica-germanate precursor to deionized water and ultrasonically disperse for 30-40 minutes. Then stir and evaporate to dryness at 80-100℃, and then sinter. After grinding and sieving, co-doped particles are obtained. S5: Add zirconium nitrate and acetylacetone to anhydrous ethanol and stir at 38-42℃ for 30-50 min. Then add tetrabutyl titanate and stir for 2-2.5 h. Add co-doped particles and ultrasonically disperse for 1-1.5 h. Then rotary evaporate and dry. Finally, heat to 500-520℃ and keep warm for 2-2.5 h. After cooling and sieving, the coated particles are obtained. S6: Add silane coupling agent KH-570, deionized water, and coated particles to anhydrous ethanol and ultrasonically disperse for 30-40 minutes. Then, vacuum dry and fluidized bed classify to obtain silicon germanium phosphor with a particle size D50=7-9μm.

[0008] Preferably, the mass ratio of anhydrous ethanol to germanium tetrafluoride in S1 is 200-220:28.5.

[0009] Preferably, the mass ratio of nano-silica, lanthanum oxide, polyvinylpyrrolidone, mixed solution, calcium carbonate, and zirconium oxide spheres in S2 is 16.8:1.15-1.31:0.6-1:228.5-248.5:94.3:1800-2200.

[0010] Preferably, in S3, the volume ratio of oxygen in the oxygen-argon mixture is 4%-6%, and the gas flow rate of the oxygen-argon mixture is 200-300 sccm.

[0011] Preferably, the mass ratio of deionized water, erbium nitrate pentahydrate, ytterbium nitrate hexahydrate, and lanthanum-doped silica-germanate precursor in S4 is 50-60:0.64-1.05:5.23-6.37:50; The sintering process described in S4 is as follows: first, under a nitrogen atmosphere, the temperature is raised to 600-650℃ at a rate of 5-10℃ / min and held for sintering for 1-1.5h; then, under an argon atmosphere, the temperature is raised to 1200-1250℃ at a rate of 5-10℃ / min and held for sintering for 1-1.5h; finally, under an argon atmosphere, the temperature is lowered to 25-35℃ at a rate of 10℃ / min.

[0012] Preferably, the mass ratio of anhydrous ethanol, zirconium nitrate, tetrabutyl titanate, acetylacetone, and co-doped particles in S5 is 100-110:20.3-22.3:4.8-5.3:2-3:50.

[0013] Preferably, the mass ratio of anhydrous ethanol, silane coupling agent KH-570, deionized water, and coated particles in S6 is 99.5-119.4:0.5-0.6:0.8-1:70-72.

[0014] An application of silicon-germanium phosphor prepared using germanium tetrafluoride in LEDs is described. The application method is as follows: the silicon-germanium phosphor is mixed with a transparent binder to form a phosphor slurry, and then the slurry is uniformly coated on the surface of the LED chip to obtain the LED.

[0015] The beneficial effects of this invention are: This invention provides a silicon-germanium phosphor prepared using germanium tetrafluoride and its application in LEDs. The invention effectively improves the fluorescence lifetime, thermal stability, and color stability of the phosphor through the following methods.

[0016] (1) The lanthanum ions introduced by adding lanthanum oxide in this invention stabilize the crystal lattice through a charge compensation mechanism, inhibit abnormal grain growth during high-temperature sintering, and improve thermal stability. During high-temperature sintering, lanthanum ion doping can improve the sintering activity of the matrix, reduce the crystallization temperature, and inhibit the decomposition of the matrix at high temperatures, thereby maintaining the purity of the target phase and ensuring the color stability of the phosphor. Although the 4f electron configuration of lanthanum ions does not emit light directly, it can serve as an energy transfer bridge: under ultraviolet / blue light excitation, the 5d energy level of lanthanum ions absorbs energy and transfers it to neighboring erbium ions, ytterbium ions, and other activating ions, optimizing the energy transfer path, reducing non-radiative transitions, extending fluorescence lifetime, and enhancing its luminous efficiency. Lanthanum ion doping can also fine-tune the band structure of the matrix, change the absorption range and intensity of the excitation light, make the emission spectrum of the phosphor more compatible with the requirements of LED chips, improve color stability, and avoid color coordinate drift caused by temperature changes. Lattice distortion and the coordination environment of lanthanum ions can reduce phonon scattering in the matrix and lower the non-radiative relaxation rate of activated ions at high temperatures, thereby increasing the thermal quenching threshold of the phosphor and slowing down the decline in luminescence efficiency at high temperatures. The strong Lewis acidity of lanthanum ions can improve the chemical inertness of the matrix surface, reduce the corrosion of phosphor by moisture and oxygen, and extend its lifespan.

[0017] (2) In this invention, germanium tetrafluoride, compared to germanium oxide, releases fluoride ions during ball milling and sintering to replace oxygen ions in the crystal lattice or form fluorine-containing defects, thereby changing the lattice parameters and crystal structure of the main phase Ca2(Si,Ge)O4, and thus regulating the energy level splitting and transition efficiency of the luminescent centers. Fluoride ions can form weak coordination complexes with lanthanum ions, promoting their uniform dispersion in the precursor, improving doping uniformity, forming stable luminescent centers, and reducing concentration quenching. The fluorine environment can also change the energy transfer efficiency of the matrix to the activated ions, reducing non-radiative transitions and improving luminescence efficiency. The high hardness of germanium tetrafluoride can also affect the particle dispersion after ball milling, promote the tight bonding of the coating layer, and improve its resistance to deliquescence and thermal stability.

[0018] (3) The 4f electron layer of erbium ions introduced by adding erbium pentahydrate in this invention has abundant energy levels. Its 4f energy level can act as an "energy buffer layer". When the main luminescent center in the matrix is ​​excited, some energy will be lost through non-radiative transitions. The intermediate energy level of erbium ions can capture this part of energy and release it again through the characteristic transitions of erbium ions, reducing non-radiative transition paths and thus prolonging fluorescence lifetime. The ionic radius of erbium ions is different from that of calcium ions or germanium ions in the matrix. After doping, it will cause lattice distortion, form a local stress field, suppress the thermal vibration amplitude of germanium-oxygen bonds at high temperature, and thus increase the thermal quenching temperature.

[0019] (4) The ytterbium ions introduced by adding ytterbium hexahydrate in this invention can act as an "energy bridge" to efficiently transfer the energy absorbed by the matrix to erbium ions, thereby improving the excitation efficiency of erbium ions, reducing energy loss, further extending fluorescence lifetime and improving quantum efficiency. The ionic radius of ytterbium ions is close to that of erbium ions. When co-doped, it can fill the lattice gaps caused by erbium ion doping, reduce defects such as oxygen vacancies or cation vacancies in the matrix, reduce the probability of nonradiative transitions, and suppress the thermal activation of defect states at high temperatures, thereby improving thermal stability and color stability. In the silicate germanate matrix, the substitution of calcium ions by lanthanum ions introduces a +1 charge, while the doping of ytterbium ions and erbium ions can balance the lattice charge through charge compensation, reduce lattice distortion caused by charge imbalance, and further stabilize the matrix structure. After the matrix absorbs energy, part of the energy directly excites the main luminescent center, and the other part is transferred to erbium ions through ytterbium ions, and then transferred to the main luminescent center by erbium ions, forming a cascaded energy transfer path from the matrix to the main luminescent center, which significantly improves energy utilization. The difference in ionic radii between erbium and ytterbium ions creates opposing stress fields in the crystal lattice, which partially cancel out thermal stress and suppress grain coarsening and structural distortion at high temperatures.

[0020] (5) In the preparation process of co-doped particles of the present invention, the initial low-temperature sintering under a nitrogen atmosphere can completely decompose residual anhydrous ethanol and other organic matter into volatile gases, avoiding particle agglomeration and coating layer defects caused by organic matter carbonization during subsequent high-temperature sintering, and preventing the generation of carbon-containing impurities by reaction with ammonia during the ammonia sintering stage, which would affect the chemical purity and luminescence purity of the phosphor. The lanthanum-doped silicate germanate precursor is amorphous or low-crystallinity. Nitrogen sintering can promote the initial formation of crystal nuclei, reduce lattice defects, and provide channels for the deep diffusion of erbium ions and ytterbium ions. This effectively prevents the increase in ion diffusion resistance during ammonia sintering due to insufficient pre-crystallization, resulting in surface-enriched doping, thereby improving the quantum efficiency and fluorescence lifetime of the phosphor. The specific heating rate and holding time of the present invention can suppress excessive particle growth, keeping the precursor in a nanoscale dispersed state to ensure the continuity and density of the subsequent coating layer, thereby improving the thermal stability of the phosphor.

[0021] (6) The zirconium dioxide-titanium dioxide composite oxide layer coated on the surface of co-doped particles by the sol-gel method in this invention can effectively block the heat generated by the LED chip from being directly transferred to the matrix at high temperatures, reducing coordination distortion of germanium-oxygen bonds caused by thermal vibration. The thermal expansion coefficient of the zirconium dioxide and titanium dioxide composite layer is close to that of the silica-germanate matrix, which can alleviate the thermal stress between the matrix and the coating layer and avoid microcracks or coating layer delamination caused by thermal mismatch at high temperatures. Uncoordinated dangling bonds on the surface of co-doped particles will shorten the fluorescence lifetime, while the zirconium dioxide-titanium dioxide coating layer can passivate surface defects through chemical bonding and suppress nonradiative recombination of electron-hole pairs. The dense coating layer can prevent water vapor, oxygen and other molecules in the LED working environment from directly contacting the matrix and reducing the influence of external quenching agents; it can also limit the ion diffusion path, maintain the uniform distribution of doped ions inside the matrix, and avoid color drift caused by the migration of doped ions from the matrix to the surface.

[0022] (7) When the silane coupling agent is used to modify the surface of the coated particles in this invention, the methoxy group of KH-570 will hydrolyze to generate silanol groups, which will form covalent bonds with the hydroxyl groups on the surface of the coating layer through a condensation reaction, thus fixing the coupling agent on the phosphor surface. At the same time, the vinyl group of the coupling agent will undergo a cross-linking reaction with the silicone commonly used in LED packaging to form chemical bonds, reducing the peeling of phosphor from the encapsulating adhesive, avoiding "black cavity" or light decay caused by thermal stress, and improving the long-term reliability of LED devices. The organic segments of KH-570 will also cover the phosphor surface to form a steric hindrance layer, inhibiting van der Waals aggregation between particles, reducing light scattering loss, improving the luminous efficiency of LEDs, and avoiding light spot and color spot problems caused by particle aggregation. The organic groups of KH-570 replace the polar hydroxyl groups on the phosphor surface, which will change the particles from hydrophilic to hydrophobic, inhibiting the phosphor from absorbing moisture in high temperature and high humidity environments, and avoiding lattice distortion or fluorescence quenching caused by moisture penetration. The fluidized bed classification process of this invention can improve the coating uniformity of phosphor, enhance the uniform transmission of LED chip excitation light through the phosphor layer, and reduce color drift.

[0023] Therefore, the silicon-germanium phosphor prepared by this invention has excellent fluorescence lifetime, thermal stability, color stability, and has a wider range of application prospects in LEDs. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise specified, the following information pertains to some of the raw materials used in the following embodiments and comparative examples of this invention: Polyvinylpyrrolidone was purchased from Beijing Bailingwei Technology Co., Ltd., item number: 902615.

[0026] Example 1: A method for preparing silicon-germanium phosphor using germanium tetrafluoride is as follows: S1: Add 200g of anhydrous ethanol to a reactor equipped with a hydrofluoric acid absorption device at 0℃, then slowly introduce 28.5g of germanium tetrafluoride and stir for 30min to obtain a mixed solution. S2: Add 16.8g of nano-silica, 1.15g of lanthanum oxide, 0.6g of polyvinylpyrrolidone, and 228.5g of mixed solution to the ball mill jar in sequence and stir for 10min. Then add 94.3g of calcium carbonate and 1800g of zirconia balls with a diameter of 3mm and immediately seal the jar. Purge with nitrogen (pressure maintained at 0.12MPa) and then ball mill at 390r / min for 7.8h at 0℃. Finally, dry the mixture at 30℃ under nitrogen purging for 10h and then at 65℃ for 3h. After grinding, pass the mixture through a 200-mesh sieve to obtain a mixed powder. S3: 80g of mixed powder was heated to 300℃ at 2℃ / min and held for 30min in an atmosphere of mixed oxygen and argon, then heated to 800℃ at 5℃ / min and held for 2h, and finally cooled to 25℃ at 2℃ / min to obtain lanthanum-doped silica germanate precursor. The volume ratio of oxygen in the above oxygen and argon mixture is 4%, and the gas flow rate of the oxygen and argon mixture is 200 sccm. S4: Add 0.64g of erbium nitrate pentahydrate, 5.23g of ytterbium nitrate hexahydrate, and 50g of lanthanum-doped silica-germanate precursor to 50mL of deionized water and perform ultrasonic dispersion at 200W and 38kHz for 30min. Then, stir and evaporate to dryness at 80℃. Then, heat to 600℃ at 5℃ / min under nitrogen atmosphere and sinter for 1h. Then, heat to 1200℃ at 5℃ / min under argon atmosphere and sinter for 1h. Finally, cool to 25℃ at 10℃ / min under argon atmosphere, grind, and pass through a 300-mesh sieve to obtain co-doped particles. S5: Add 20.3g zirconium nitrate and 2g acetylacetone to 100g anhydrous ethanol and stir at 300r / min for 30min at 38℃. Then add 4.8g tetrabutyl titanate and stir at 38-40℃ for 2h. Then add 50g co-doped particles and perform ultrasonic dispersion at 200W power and 40kHz frequency for 1h. Then rotary evaporate at 100r / min at 58℃ for 30min. Then dry at 115℃ for 4h. Finally, heat to 500℃ at 5℃ / min and hold for 2h. After cooling and passing through a 400-mesh sieve, the coated particles are obtained. S6: 0.5g of silane coupling agent KH-570, 0.8mL of deionized water, and 70g of coated particles were added to 99.5g of anhydrous ethanol and ultrasonically dispersed at 200W and 38kHz for 30min. Then, the particles were vacuum dried at 60℃ and -0.1MPa for 12h. Finally, the particles were subjected to fluidized bed classification at an airflow velocity of 9m / s and a classifier wheel speed of 7000r / min to obtain silicon germanium phosphor with a particle size D50=7μm. The chemical formula of the aforementioned silicon-germanium phosphor is Ca2(Si) 0.6 Ge 0.4 O4: 0.015La 3+ 0.003Er 3+ 0.025Yb 3+ @ZrO2-TiO2.

[0027] Example 2: A method for preparing silicon-germanium phosphor using germanium tetrafluoride is as follows: S1: Add 210g of anhydrous ethanol to a reaction vessel at 0℃, then slowly introduce 28.5g of germanium tetrafluoride and stir for 40min to obtain a mixed solution; S2: Add 16.8g of nano-silica, 1.23g of lanthanum oxide, 0.8g of polyvinylpyrrolidone, and 238.5g of mixed solution to a ball mill jar in sequence and stir for 15min. Then add 94.3g of calcium carbonate and 2000g of zirconia balls with a diameter of 3mm, seal immediately, and purge with nitrogen (pressure maintained at 0.12MPa). Then ball mill at 3℃ and 400r / min for 8h. Finally, dry at 30℃ and under nitrogen purging for 12h, and then dry at 65℃ for 3.5h. After grinding, pass through a 200-mesh sieve to obtain a mixed powder. S3: 80g of mixed powder was heated to 310℃ at 4℃ / min and held for 35min in an atmosphere of mixed oxygen and argon, then heated to 830℃ at 5℃ / min and held for 2.1h, and finally cooled to 30℃ at 3℃ / min to obtain lanthanum-doped silica-germanate precursor. The volume ratio of oxygen in the above oxygen and argon mixture is 5%, and the gas flow rate of the oxygen and argon mixture is 250 sccm. S4: Add 0.84g of erbium nitrate pentahydrate, 5.8g of ytterbium nitrate hexahydrate, and 50g of lanthanum-doped silica-germanate precursor to 55mL of deionized water and perform ultrasonic dispersion at 210W and 39kHz for 35min. Then, stir and evaporate to dryness at 90℃. Then, heat to 630℃ at 8℃ / min under nitrogen atmosphere and sinter for 1.2h. Then, heat to 1230℃ at 8℃ / min under argon atmosphere and sinter for 1.3h. Finally, cool to 30℃ at 10℃ / min under argon atmosphere. Grind and pass through a 300-mesh sieve to obtain co-doped particles. S5: Add 21.3g zirconium nitrate and 2.5g acetylacetone to 105g anhydrous ethanol and stir at 330r / min for 40min at 40℃. Then add 5.1g tetrabutyl titanate and stir at 40℃ for 2.2h. Then add 50g co-doped particles and perform ultrasonic dispersion at 210W and 40kHz for 1.2h. Then rotary evaporate at 110r / min for 35min at 60℃, and dry at 120℃ for 4.3h. Finally, heat to 510℃ at 5℃ / min and hold for 2.3h. After cooling and passing through a 400-mesh sieve, the coated particles are obtained. S6: 0.55g of silane coupling agent KH-570, 0.9mL of deionized water, and 71g of coated particles were added to 109.45g of anhydrous ethanol and ultrasonically dispersed at 210W and 39kHz for 35min. Then, the particles were vacuum dried at 63℃ and -0.1MPa for 13h. Finally, the particles were subjected to fluidized bed classification at an airflow velocity of 10m / s and a classifier wheel speed of 7100r / min to obtain silicon germanium phosphor with a particle size D50=8μm. The chemical formula of the aforementioned silicon-germanium phosphor is Ca2(Si) 0.6 Ge 0.4 O4: 0.016La 3+ 0.004Er 3+ 0.027Yb 3+ @ZrO2-TiO2.

[0028] Example 3: A method for preparing silicon-germanium phosphor using germanium tetrafluoride is as follows: S1: Add 220g of anhydrous ethanol to a reaction vessel at 0℃, then slowly introduce 28.5g of germanium tetrafluoride and stir for 50min to obtain a mixed solution; S2: Add 16.8g of nano-silica, 1.31g of lanthanum oxide, 1g of polyvinylpyrrolidone, and 248.5g of mixed solution to the ball mill jar in sequence and stir for 20min. Then add 94.3g of calcium carbonate and 2200g of zirconia balls with a diameter of 3mm and immediately seal the jar. Purge with nitrogen (pressure maintained at 0.12MPa) and then ball mill at 410r / min for 8.2h at 5℃. Finally, dry the mixture at 30℃ under nitrogen purging for 12h and then at 65℃ for 4h. After grinding, pass the mixture through a 200-mesh sieve to obtain a mixed powder. S3: 80g of mixed powder was heated to 320℃ at 5℃ / min and held for 40min in a mixed atmosphere of oxygen and argon, then heated to 850℃ at 5℃ / min and held for 2.2h, and finally cooled to 35℃ at 5℃ / min to obtain lanthanum-doped silica germanate precursor. The volume ratio of oxygen in the above oxygen and argon mixture is 6%, and the gas flow rate of the oxygen and argon mixture is 300 sccm. S4: Add 1.05g of erbium nitrate pentahydrate, 6.37g of ytterbium nitrate hexahydrate, and 50g of lanthanum-doped silica-germanate precursor to 60mL of deionized water and perform ultrasonic dispersion at 220W and 40kHz for 40min. Then, stir and evaporate to dryness at 100℃. First, heat to 650℃ at 10℃ / min under nitrogen atmosphere and sinter for 1.5h. Then, heat to 1250℃ at 10℃ / min under argon atmosphere and sinter for 1.5h. Finally, cool to 35℃ at 10℃ / min under argon atmosphere, grind, and pass through a 300-mesh sieve to obtain co-doped particles. S5: Add 22.3g zirconium nitrate and 3g acetylacetone to 110g anhydrous ethanol and stir at 350r / min for 50min at 42℃. Then add 5.3g tetrabutyl titanate and stir at 42℃ for 2.5h. Add 50g co-doped particles and perform ultrasonic dispersion at 220W and 40kHz for 1.5h. Then rotary evaporate at 120r / min for 40min at 62℃. Then dry at 125℃ for 4.5h. Finally, heat to 520℃ at 5℃ / min and hold for 2.5h. After cooling and passing through a 400-mesh sieve, the coated particles are obtained. S6: 0.6g of silane coupling agent KH-570, 1mL of deionized water, and 72g of coated particles were added to 119.4g of anhydrous ethanol and ultrasonically dispersed at 220W and 40kHz for 40min. Then, the particles were vacuum dried at 65℃ and -0.1MPa for 15h. Finally, the particles were subjected to fluidized bed classification at an airflow velocity of 11m / s and a classifier wheel speed of 7200r / min to obtain silicon germanium phosphor with a particle size of 9μm. The chemical formula of the aforementioned silicon-germanium phosphor is Ca2(Si) 0.6 Ge0.4 O4: 0.017La 3+ 0.005Er 3+ 0.03Yb 3+ @ZrO2-TiO2.

[0029] Comparative Example 1: Compared with Example 1, this comparative example only did not add "lanthanum oxide" in the preparation of the mixed powder in S2. All other steps and parameters were the same, and will not be repeated here. The final product was silicon-germanium phosphor.

[0030] Comparative Example 2: Compared with Example 1, this comparative example only replaces "28.5g germanium tetrafluoride" added during the preparation of the mixed powder in S1 with "19.93g germanium oxide". All other steps and parameters are the same, and will not be repeated in this comparative example. The final silicon-germanium phosphor is obtained.

[0031] Comparative Example 3: Compared with Example 1, this comparative example only omits the addition of "erbium nitrate pentahydrate" during the preparation of co-doped particles in S4. All other steps and parameters are the same, and will not be repeated here. The final product is silicon-germanium phosphor.

[0032] Comparative Example 4: Compared with Example 1, this comparative example only did not add "ytterbium nitrate hexahydrate" in the preparation process of co-doped particles in S4. All other steps and parameters were the same, and will not be repeated here. The final silicon-germanium phosphor was obtained.

[0033] Comparative Example 5: Compared with Example 1, this comparative example only replaces the process of preparing the co-doped particles of S4 by "first heating to 600°C at 5°C / min under nitrogen atmosphere and holding for sintering for 1 hour, then heating to 1200°C at 60°C / min under argon atmosphere and holding for sintering for 30 minutes, and finally cooling to 25°C at 10°C / min under argon atmosphere" with "heating to 1200°C at 60°C / min under ammonia atmosphere and holding for sintering for 60 minutes, and finally cooling to 25°C at 10°C / min under argon atmosphere". All other steps and parameters are the same, and will not be repeated in this comparative example. The silicon-germanium phosphor is finally obtained.

[0034] Comparative Example 6: Compared with Example 1, this comparative example only replaces the "coated particles" added during the preparation of silicon-germanium phosphor in S6 with the "co-doped particles" prepared in S4. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, silicon-germanium phosphor is obtained.

[0035] Comparative Example 7: Compared with Example 1, this comparative example only did not perform the S6 treatment on the "coated particles" prepared in S5. All other steps and parameters were the same, and will not be repeated here. The final product was silicon-germanium phosphor (originally called: coated particles).

[0036] Performance testing: Determination of fluorescence lifetime: The fluorescence lifetime (ms) of the silicon-germanium phosphors prepared in Examples 1-3 and Comparative Examples 1-7 of this invention was measured using an FLS 980 fluorescence spectrometer with a xenon flash lamp as the excitation source. The measurement results are shown in Table 1.

[0037] Determination of thermal quenching temperature: The emission spectrum of the phosphor at 450 nm as a function of temperature was measured using an MCPD7000 multichannel spectrometer. The test temperature range was 25-250℃, with a step size of 20℃ and a heating rate of 10℃ / min (during which the temperature was paused and stabilized for 10 min after every 20℃ increase). The relative luminescence intensity (Ig) of the phosphor was also measured. T The temperature corresponding to a / I0) of 0.9 is denoted as the thermal quenching temperature. The thermal quenching temperatures (°C) of the silicon-germanium phosphors prepared in Examples 1-3 and Comparative Examples 1-7 of this invention were determined according to the above method, and the results are shown in Table 1.

[0038] Measurement of colorimetric shift: A FLS 980 fluorescence spectrometer with a xenon flash lamp as the excitation source was connected to a Linkam THMS600 hot and cold stage. A chromaticity-temperature curve for the temperature range of 25-250℃ was plotted at a heating rate of 5℃ / min (with a pause and stabilization period of 5 min after every 10℃ increase). The drift value at 250℃ compared to 25℃ was calculated as the chromaticity drift of the phosphor. The thermal quenching temperature and chromaticity drift of the silicon-germanium phosphors prepared in Examples 1-3 and Comparative Examples 1-7 of this invention were measured using the above method. The results are shown in Table 1.

[0039] Measurement of quantum efficiency: The quantum efficiency (%) of the silicon-germanium phosphors prepared in Examples 1-3 and Comparative Examples 1-7 of this invention was determined using an FLS 980 fluorescence spectrometer with a xenon flash lamp as the excitation source. The results are shown in Table 1.

[0040] Determination of moisture resistance: The fluorescence intensity decay rate (%) of the silicon-germanium phosphors prepared in Examples 1-3 and Comparative Examples 1-7 of this invention after 1000 hours of exposure at 85°C and 85%RH was measured using an FLS 980 fluorescence spectrometer with a xenon flash lamp as the excitation source. This was used to reflect the moisture resistance of the phosphors (the smaller the decay rate, the better the moisture resistance). The measurement results are shown in Table 1.

[0041] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-7

[0042] Data Analysis: As can be seen from Table 1, the silicon-germanium phosphor prepared in the embodiments of the present invention has excellent fluorescence lifetime, thermal stability, color stability, quantum efficiency and moisture resistance.

[0043] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A silicon-germanium phosphor prepared using germanium tetrafluoride, characterized in that, The general chemical formula of silicon-germanium phosphor is Ca2(Si) 0.6 Ge 0.4 O4: xLa 3+ yEr 3+ zYb 3+ @ZrO2-TiO2.

2. The silicon-germanium phosphor prepared using germanium tetrafluoride according to claim 1, characterized in that, The value of x is 0.015-0.017; The value of y is 0.003-0.005; The value of z is 0.025-0.

03.

3. The silicon-germanium phosphor prepared using germanium tetrafluoride according to claim 1, characterized in that, The preparation method of the silicon-germanium phosphor is as follows: S1: Add anhydrous ethanol to a reaction vessel equipped with a hydrofluoric acid absorption device at 0℃, then introduce germanium tetrafluoride and stir for 30-50 min to obtain a mixed solution. S2: Add nano-silica, lanthanum oxide, polyvinylpyrrolidone, and mixed solution sequentially to a ball mill jar and stir for 10-20 min. Then add calcium carbonate and zirconium oxide balls, seal immediately, and purge with nitrogen. Then ball mill at 390-410 r / min at 0-5℃ for 7.8-8.2 h. After drying and grinding, pass through a 200-mesh sieve to obtain a mixed powder. S3: The mixed powder is heated to 300-320℃ and held for 30-40 min in a mixed atmosphere of oxygen and argon, then heated to 800-850℃ and held for 2-2.2 h. After cooling, the lanthanum-doped silica-germanate precursor is obtained. S4: Add erbium nitrate pentahydrate, ytterbium nitrate hexahydrate, and lanthanum-doped silica-germanate precursor to deionized water and ultrasonically disperse for 30-40 minutes. Then stir and evaporate to dryness at 80-100℃, and then sinter. After grinding and sieving, co-doped particles are obtained. S5: Add zirconium nitrate and acetylacetone to anhydrous ethanol and stir at 38-42℃ for 30-50 min. Then add tetrabutyl titanate and stir for 2-2.5 h. Add co-doped particles and ultrasonically disperse for 1-1.5 h. Then rotary evaporate and dry. Finally, heat to 500-520℃ and keep warm for 2-2.5 h. After cooling and sieving, the coated particles are obtained. S6: Add silane coupling agent KH-570, deionized water, and coated particles to anhydrous ethanol and ultrasonically disperse for 30-40 minutes. Then, vacuum dry and fluidized bed classify to obtain silicon germanium phosphor with a particle size D50=7-9μm.

4. The silicon-germanium phosphor prepared using germanium tetrafluoride according to claim 3, characterized in that, The mass ratio of anhydrous ethanol to germanium tetrafluoride in S1 is 200-220:28.

5.

5. The silicon-germanium phosphor prepared using germanium tetrafluoride according to claim 3, characterized in that, The mass ratio of nano-silica, lanthanum oxide, polyvinylpyrrolidone, mixed solution, calcium carbonate, and zirconium oxide spheres in S2 is 16.8:1.15-1.31:0.6-1:228.5-248.5:94.3:1800-2200.

6. The silicon-germanium phosphor prepared using germanium tetrafluoride according to claim 3, characterized in that, The oxygen volume ratio in the oxygen-argon mixture described in S3 is 4%-6%, and the gas flow rate of the oxygen-argon mixture is 200-300 sccm.

7. The silicon-germanium phosphor prepared using germanium tetrafluoride according to claim 3, characterized in that, The mass ratio of deionized water, erbium nitrate pentahydrate, ytterbium nitrate hexahydrate, and lanthanum-doped silicate germanate precursor in S4 is 50-60: 0.64-1.05：5.23-6.37：50； The sintering process described in S4 is as follows: first, under a nitrogen atmosphere, the temperature is raised to 600-650℃ at a rate of 5-10℃ / min and held for sintering for 1-1.5h; then, under an argon atmosphere, the temperature is raised to 1200-1250℃ at a rate of 5-10℃ / min and held for sintering for 1-1.5h; finally, under an argon atmosphere, the temperature is lowered to 25-35℃ at a rate of 10℃ / min.

8. The silicon-germanium phosphor prepared using germanium tetrafluoride according to claim 3, characterized in that, The mass ratio of anhydrous ethanol, zirconium nitrate, tetrabutyl titanate, acetylacetone, and co-doped particles in S5 is 100-110:20.3-22.3:4.8-5.3:2-3:

50.

9. The silicon-germanium phosphor prepared using germanium tetrafluoride according to claim 3, characterized in that, The mass ratio of anhydrous ethanol, silane coupling agent KH-570, deionized water, and coated particles in S6 is 99.5-119.4:0.5-0.6:0.8-1:70-72.

10. The application of a silicon-germanium phosphor prepared using germanium tetrafluoride according to any one of claims 1-9 in an LED, characterized in that, The application method is as follows: mix silicon germanium phosphor with a transparent binder to make a phosphor slurry, and then coat the slurry evenly on the surface of the LED chip to obtain an LED.

Images