CN115259852A - A kind of green light conversion material with high light efficiency and preparation method thereof - Google Patents

Abstract

A green light conversion material with high light efficiency, the general chemical formula is: yLu ₃ Al ₅ O ₁₂ –(1‑y)(Cex Lu _{1‑x ) 3} Al ₅ O ₁₂ , wherein x is Ce ³⁺ doping The atomic percentage of Lu ³⁺ positions, y is the mass ratio of LuAG to replace Ce:LuAG, 0<x≤0.01, 0<y<1. Preparation method: Weigh Lu ₂ O ₃ powder, Al ₂ O ₃ powder and CeO ₂ powder respectively according to the stoichiometric ratio in the general chemical formula as ceramic powder; use solvent as ball milling medium, and sinter the ceramic powder and sintered powder together. The additives are placed in a ball-milling jar and ball-milled, followed by drying, sieving, cooling, etc., forming and calcining to obtain a ceramic green body; the ceramic green body is sequentially sintered, annealed, and double-sided polished to obtain a high-efficiency green light conversion material. The preparation method is simple, and the prepared conversion material can improve the light conversion efficiency and the transmittance in the visible light region, thereby obtaining green light with high lumen density.

Description

A kind of high light efficiency green light conversion material and preparation method thereof

technical field

The invention belongs to the technical field of inorganic luminescent materials, and in particular relates to a fluorescent transparent ceramic material and a preparation method thereof, in particular to a green light conversion material with high light efficiency and a preparation method thereof.

Background technique

Laser display technology (Laser display technique, LDT) has the advantages of rich colors, high saturation, and strong contrast. This technology is widely regarded as the mainstream technology for future high-end displays such as large-screen projection, laser TV, digital cinema, and mobile phone projection. However, the current development of "high-brightness" and "high-efficiency" green light sources is still unsatisfactory.

At present, there are three main high-brightness green light synthesis schemes: (1) Green lasers: high-power, high-stability green lasers have been industrialized and widely used in the market; however, due to the large size of green lasers, they cannot Miniaturization and low operating efficiency have hindered its application in the projection industry; (2) Using multiple green LEDs: the luminous efficiency achieved by this method is still not high, similar to green LDs, this gallium nitride The phenomenon that the efficiency of the main LED is not high is called "green light gap"; (3) Fluorescence conversion method: the light conversion material is pumped by blue LED or LD, and the light conversion material absorbs energy in the blue light range and emits green light. Light. The green light source obtained by fluorescent conversion has the advantages of small size, high efficiency, stable luminescence, and small chromaticity drift. It only needs to increase the input power of the pumping process to obtain higher brightness, and it will not exist for a long time. drop in efficiency. Therefore, the way of high-efficiency fluorescent conversion is the best way to obtain high lumen density green light source.

Light conversion materials include phosphors, single crystals, glass, and fluorescent ceramics. Comprehensive thermal stability, quantum efficiency, thermal quenching and other aspects of performance, among them, ceramics with high thermal conductivity have gradually become a research hotspot. Among fluorescent ceramics, Ce ³⁺ doped lutetium aluminum garnet LuAG (Ce:LuAG) with high luminous efficiency is a typical representative. Ce ³⁺ in LuAG matrix can emit light with a central wavelength band at 520nm. Compared with LuAG ceramic powder, this ceramic has higher thermal conductivity, stronger thermal quenching resistance and higher quantum efficiency, and the quantum efficiency can reach more than 90%. It is a kind of ceramic that can withstand high power density Excited yellow-green light conversion material.

At present, lithium fluoride has been used as a sintering aid to prepare Ce:LuAG powder into fluorescent ceramics with a dense structure. However, due to the characteristics of the LuAG matrix itself, the transmittance of green light ceramics can reach 83%. Although it is conducive to the passage of blue light, the utilization rate of blue light is low, and it is difficult to achieve high-efficiency green light conversion. Publication No. CN110903088A discloses a porous fluorescent ceramic and its preparation method, light-emitting device and projection device. The preparation method improves the utilization rate of blue light by introducing pores, but the introduction of pores will greatly reduce the thermal conductivity of ceramics; Publication No. CN109896852A Disclosed is a composite fluorescent ceramic for white light illumination excited by blue light, a preparation method, and a light source device. This patent improves the utilization rate of blue light while ensuring high thermal conductivity by introducing Al ₂ O ₃ as a scattering center. However, LuAG The difference in refractive index with Al ₂ O ₃ is too large, resulting in a significant decrease in the transmittance of ceramics in the visible light region.

Contents of the invention

The object of the present invention is to provide a high-efficiency green light conversion material and a preparation method thereof. The preparation method has a simple process, and the green light conversion material prepared by this method can improve the light conversion efficiency and the transmittance in the visible light region, thereby Get high lumen density green light.

In order to achieve the above purpose, the technical solution adopted by the present invention is: a high-efficiency green light conversion material whose general chemical formula is: yLu ₃ Al ₅ O ₁₂ –(1-y)(Cex Lu _{1-x ) 3} Al ₅ O ₁₂ , where x is the atomic percentage of Ce ³⁺ doped Lu ³⁺ sites, y is the mass ratio of LuAG doped Ce:LuAG, 0<x≤0.01, 0<y<1.

Preferably, the green light conversion material emits a waveband in the range of 490-580nm when excited by a blue LED chip with an emission wavelength of 400-480nm, the light conversion efficiency is 220-250lm/W, and the lumen density is 2000-2500lm/mm.

Another technical solution adopted by the present invention is: the preparation method of the above-mentioned high light efficiency green light conversion material, the specific steps are as follows:

(1) According to the stoichiometric ratio of yLu ₃ Al ₅ O ₁₂ –(1-y)(Cex Lu _{1-x ) 3} Al ₅ O ₁₂ , weigh Lu ₂ O ₃ powder, Al ₂ O ₃ powder and CeO respectively ₂ The powder is used as a ceramic powder, where x is the atomic percentage of Ce ³⁺ doped with Lu ³⁺ sites, y is the mass ratio of LuAG doped with Ce:LuAG, 0<x≤0.01, 0<y<1;

(2) Using the solvent as the ball milling medium, put the accurately weighed ceramic powder and sintering aid in the ball mill pot for ball milling, and then successively undergo drying, sieving, cold forming, etc., and then place them in the muffle furnace for calcination to obtain ceramic elements. Blank;

(3) Sintering, annealing, and double-sided polishing of the ceramic green body in sequence to obtain a green light conversion material with high light efficiency.

Preferably, in step (2), the sintering aid is one or both of MgO, CaO, and TEOS, the amount of MgO or CaO added is 0.06-0.5wt.% of the total mass of the raw material powder, and the amount of TEOS added It is 0.31-0.78wt.% of the total mass of raw material powder.

Preferably, in step (2), the drying temperature is 60-100°C, the drying time is 10-15h, the calcination temperature is 400-900°C, and the calcination time is 5-8h.

Preferably, in step (2), the cold molding pressure is 150-300 MPa, and the holding time is 200-400s.

Preferably, in step (3), the sintering method is vacuum sintering, hot pressing sintering and reducing atmosphere sintering; the sintering temperature is 1650-1850° C., kept for 6-20 hours, and then cooled to room temperature.

Preferably, the annealing atmosphere is oxygen or air, the annealing temperature is 1300-1500° C., and the temperature is kept for 6-15 hours.

Preferably, in step (2), the ball milling parameters are: the ball milling medium is ultrapure water or absolute ethanol, and the ball milling is performed at 120-200 r/min for 12-15 hours.

Compared with prior art solutions, the present invention has the following advantages:

(1) The present invention improves the utilization rate of blue light by introducing pure LuAG and utilizes the smaller difference in the refractive index of pure LuAG and Ce:LuAG to realize high fluorescence conversion efficiency;

(2) The green light ceramics prepared by the present invention ensure good transmittance (80%@800nm) and good thermal performance of the ceramic while realizing high fluorescence conversion rate;

(3) The green light ceramics prepared by the present invention can realize high-efficiency green light conversion, the light-to-light conversion efficiency is 220-250lm/W, the electro-optic conversion efficiency is 50-75lm/W, and the high lumen density can realize 2000-2500lm/W mm.

Description of drawings

Fig. 1 is the emission spectrogram of the sample transparent ceramic prepared in Example 2 of the present invention;

Fig. 2 is the transmittance spectrum of the Ce:LuAG sample prepared in Example 2 of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment one

Preparation of 0.3Lu ₃ Al ₅ O ₁₂ –0.7(Ce _0.003 Lu _0.997 ) ₃ Al ₅ O ₁₂

(1) According to the stoichiometric ratio of each element in the chemical formula 0.3Lu ₃ Al ₅ O ₁₂ –0.7(Ce _0.003 Lu _0.997 ) ₃ Al ₅ O ₁₂ , weigh Lu ₂ O ₃ 41.967g, Al ₂ O ₃ 17.960g and CeO ₂ 0.076g is used as ceramic raw material powder, 60g in total, where x is the atomic percentage of Ce ³⁺ doped with Lu ³⁺ sites, y is the mass ratio of LuAG doped Ce:LuAG, 0<x≤0.01, 0<y <1;

(2) Using anhydrous ethanol as the ball milling medium, put the accurately weighed ceramic powder and sintering aid in the ball milling tank for ball milling, mill at 120r/min for 15h, then dry, pass through a 100-mesh sieve, cool, etc. After molding, it is placed in a muffle furnace and calcined to obtain a ceramic green body; the sintering aid is 0.036g of MgO and 0.2ml (0.187g) of TEOS; the drying temperature is 60°C, and the drying time is 15h; the cold molding pressure is 150MPa, The holding time is 400s; the calcination temperature is 400℃, and the calcination time is 8h;

(3) sequentially sintering, annealing, and double-sided polishing of the ceramic green body to obtain a high-efficiency green light conversion material; the sintering method is vacuum sintering, hot-pressing sintering, and reducing atmosphere sintering; the sintering temperature is 1780° C. Then cool to room temperature; the annealing atmosphere is oxygen or air, the annealing temperature is 1300° C., and the temperature is kept for 15 hours.

The green light conversion material prepared in this example emits a wavelength band at 521nm under the excitation of a blue LED chip with a light emission wavelength of 460nm. 2000lm/mm.

Embodiment two

Preparation of 0.5Lu ₃ Al ₅ O ₁₂ –0.5(Ce _0.003 Lu _0.997 ) ₃ Al ₅ O ₁₂

(1) According to the stoichiometric ratio of each element in the chemical formula 0.5Lu ₃ Al ₅ O ₁₂ –0.5(Ce _0.003 Lu _0.997 ) ₃ Al ₅ O ₁₂ , weigh Lu ₂ O ₃ 41.990 g, Al ₂ O ₃ 17.958 g and CeO ₂ 0.055g is used as ceramic raw material powder, 60g in total, where x is the atomic percentage of Ce ³⁺ doped with Lu ³⁺ sites, y is the mass ratio of LuAG doped Ce:LuAG, 0<x≤0.01, 0<y <1;

(2) Using absolute ethanol as the ball milling medium, put the accurately weighed ceramic powder and sintering aid in the ball milling tank for ball milling, and mill at 180r/min for 13h, then dry, pass through a 100-mesh sieve, cool, etc. After molding, it is placed in a muffle furnace and calcined to obtain a ceramic green body; the sintering aid is 0.06g of MgO and 0.33ml (0.308g) of TEOS; the drying temperature is 70°C, and the drying time is 12h; the cold molding pressure is 200MPa, The holding time is 300s; the calcination temperature is 800℃, and the calcination time is 6h;

(3) sequentially sintering, annealing, and double-sided polishing of the ceramic green body to obtain a high-efficiency green light conversion material; the sintering method is vacuum sintering, hot-pressing sintering, and reducing atmosphere sintering; the sintering temperature is 1650° C. Then cool to room temperature; the annealing atmosphere is oxygen or air, the annealing temperature is 1450° C., and the temperature is kept for 10 hours.

Fig. 1 is the emission spectrum diagram of the transparent ceramic prepared in this embodiment. It can be seen from the figure that the green light conversion material prepared in this embodiment emits a wave band at 520 nm under the excitation of a blue LED chip with an emission wavelength of 460 nm. The light-to-light conversion efficiency is 250lm/W, the electro-optic conversion efficiency is 75lm/W, and the lumen density is 2500lm/mm.

FIG. 2 is the optical transmittance diagram of the sample transparent ceramic prepared in this embodiment. It can be seen from the figure that the transmittance of the green light conversion material prepared in this embodiment can reach 80% at 800 nm.

Embodiment three

Preparation of 0.7Lu ₃ Al ₅ O ₁₂ –0.3(Ce _0.003 Lu _0.997 ) ₃ Al ₅ O ₁₂

(1) According to the stoichiometric ratio of each element in the chemical formula 0.7Lu ₃ Al ₅ O ₁₂ –0.3(Ce _0.003 Lu _0.997 ) ₃ Al ₅ O ₁₂ , weigh Lu ₂ O ₃ 42.01g, Al ₂ O ₃ 17.96g and CeO ₂ 0.03g is used as ceramic raw material powder, 60g in total, where x is the atomic percentage of Ce ³⁺ doped with Lu ³⁺ sites, y is the mass ratio of LuAG doped Ce:LuAG, 0<x≤0.01, 0<y <1;

(2) Using ultra-pure water as the ball milling medium, put the accurately weighed ceramic powder and sintering aid in the ball milling tank for ball milling, and mill at 200r/min for 12h, then dry, pass through a 100-mesh sieve, cool, etc. After molding, it is placed in a muffle furnace and calcined to obtain a ceramic green body; the sintering aid is 0.3g of CaO and 0.5ml (0.467g) of TEOS; the drying temperature is 100°C, and the drying time is 10h; the cold forming pressure is 300MPa, The holding time is 200s; the calcination temperature is 900℃, and the calcination time is 5h;

(3) Sintering, annealing, and double-sided polishing of the ceramic green body in sequence to obtain a high-efficiency green light conversion material; the sintering method is vacuum sintering, hot-pressing sintering, and reducing atmosphere sintering; the sintering temperature is 1850° C. Then cool to room temperature; the annealing atmosphere is oxygen or air, the annealing temperature is 1500° C., and the temperature is kept for 6 hours.

The green light conversion material prepared in this example emits a wavelength band at 520nm under the excitation of a blue LED chip with a light emission wavelength of 460nm, the light-to-light conversion efficiency is 220lm/W, the electro-optic conversion efficiency is 68lm/W, and the lumen density is 2400lm /mm.

Claims (9)

1. A green light conversion material with high luminous efficiency is characterized in that the chemical general formula is as follows: yLu₃Al₅O₁₂–(1-y)(Ce_xLu_1-x)₃Al₅O₁₂Wherein x is Ce³⁺Doped Lu³⁺The atomic percentage of the site, y is the mass ratio of LuAG substituted Ce to LuAG, 0<x≤0.01，0<y<1。

2. The high-luminous-efficiency green light conversion material as claimed in claim 1, wherein the green light conversion material emits a wave band in a range of 490-580nm under excitation of a blue LED chip with a light-emitting wavelength of 400-480nm, the light conversion efficiency is 220-250lm/W, and the lumen density is 2000-2500lm/mm.

3. The preparation method of the high-luminous-efficiency green light conversion material of claim 1 or 2 is characterized by comprising the following specific steps of:

(1) According to yLu₃Al₅O₁₂–(1-y)(Ce_xLu_1-x)₃Al₅O₁₂Stoichiometric ratio Lu₂O₃Powder of Al₂O₃Powder and CeO₂The powder is used as ceramic powder, wherein x is Ce³⁺Doped Lu³⁺The atomic percent of the sites, y is the mass ratio of LuAG doped Ce to LuAG, 0<x≤0.01，0<y<1；

(2) Taking a solvent as a ball milling medium, placing ceramic powder and a sintering aid which are accurately weighed into a ball milling tank for ball milling, sequentially drying, sieving, cooling and the like, and then placing into a muffle furnace for calcining to obtain a ceramic biscuit;

(3) And sequentially sintering, annealing and double-side polishing the ceramic biscuit to obtain the high-luminous-efficiency green light conversion material.

4. The method according to claim 3, wherein in the step (2), the sintering aid is one or two of MgO, caO and TEOS, the addition amount of MgO or CaO is 0.06-0.5wt.% of the total mass of the raw material powder, and the addition amount of TEOS is 0.31-0.78wt.% of the total mass of the raw material powder.

5. The method according to claim 3 or 4, wherein in the step (2), the drying temperature is 60-100 ℃, the drying time is 10-15h, the calcining temperature is 400-900 ℃, and the calcining time is 5-8h.

6. The method according to claim 3 or 4, wherein in the step (2), the cold isostatic pressing pressure is 150-300MPa, and the dwell time is 200-400s.

7. The method for preparing a high light efficiency green light conversion material according to claim 3 or 4, wherein in the step (3), the sintering manner is vacuum sintering, hot press sintering and reducing atmosphere sintering; the sintering temperature is 1650-1850 ℃, the temperature is kept for 6-20h, and then the temperature is cooled to the room temperature.

8. The method for preparing a green light conversion material with high luminous efficiency according to claim 3 or 4, wherein the sintering and annealing atmosphere is oxygen or air, the annealing temperature is 1300-1500 ℃, and the temperature is kept for 6-15h.

9. The method for preparing a green light conversion material with high luminous efficiency according to claim 3 or 4, wherein in the step (2), the ball milling parameters are as follows: the ball milling medium is ultrapure water or absolute ethyl alcohol, and the ball milling is carried out for 12-15h at the speed of 120-200 r/min.

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