CN111995397A - A kind of fluorescent ceramic and its preparation method and application - Google Patents

Abstract

The present application discloses a fluorescent ceramic and a preparation method and application thereof, wherein the fluorescent ceramic is selected from at least one of substances having the general formula shown in formula I; Lu _3‑x‑y C _{x My} Al _{5‑ y} Q _y O ₁₂ Formula I; wherein, M represents a first co-doping element, the first co-doping element is selected from at least one of alkaline earth metal elements; Q represents a second co-doping element, the second co-doping element The element is selected from at least one of Si element and Ge element; the value range of x is 0.0001≤x≤0.3; the value range of y is 0≤y≤2. The present application achieves charge balance by doping M ²⁺ and Q ⁴⁺ ions in equal amounts to achieve charge balance, so that the variable valence Ce ³⁺ ions in the fluorescent ceramic are inhibited from being converted into Ce ⁴⁺ , so the fluorescent ceramic has a medium and large composition. Part of it is Ce ³⁺ emitting ions. The fluorescent ceramic has the characteristics of high density, good laser saturation performance and high luminous efficiency, can be used as a key material for color converters, and has great application potential in the field of high-power laser lighting.

Description

A kind of fluorescent ceramic and its preparation method and application

technical field

The application relates to a fluorescent ceramic, a preparation method and application thereof, and belongs to the field of fluorescent ceramic materials.

Background technique

With the maturity of blue light LD technology, the concept of laser lighting has also been proposed. In 2012, OSRAM and BMW first installed laser lighting in BMW i8 cars. The popularity of laser lighting research has also increased. Laser white light source has the advantages of high brightness, fast response speed and long transmission distance, and has been widely used in remote lighting fields such as automotive lighting, display, industrial lighting and high-speed rail ships.

However, with the ever-increasing lumen density, higher requirements are placed on light conversion materials. At present, the requirements of laser lighting for fluorescent materials mainly include high quantum efficiency, high thermal conductivity, good thermal shock resistance, and good temperature quenching characteristics. At present, the materials selected in the market are mainly two kinds of phosphors and resins or YAG:Ce ceramics used in white LEDs. However, phosphors and resins are easy to age under blue laser irradiation, which is not conducive to white light emitting. Fluorescent ceramics have the advantages of simple preparation process, low cost, the ability to produce large-size samples, high-concentration uniform doping, and mass production. However, YAG:Ce ceramics lack green and red components, resulting in low color rendering index, poor temperature quenching properties, and low luminous efficiency at high temperatures.

In response to this problem, LuAG:Ce fluorescent ceramics have high thermal conductivity, good thermal shock resistance, and quantum efficiency comparable to YAG:Ce, which has good radiation damage resistance under blue laser irradiation. At the same time, it can supplement the green spectral components of YAG:Ce to achieve spectral expansion.

In the process of ceramic preparation, sintering aids are added to prepare transparent ceramics with high optical quality. Due to the difference in ionic radius and valence between sintering aid ions and matrix ions, lattice defects such as lattice distortion are easily introduced after addition. Therefore, there are certain limitations in the performance of the prepared Lutetium Aluminum Garnet transparent ceramics. A translucent ceramic was synthesized by spark plasma sintering of commercial LuAG:Ce powders and used LiF as an additive. The sintering process was carried out at a soaking temperature of 1450 °C with a pressure of 16 kn, a heating rate of 100 °C/min and a peak current of 1750 A. Sintering was carried out at 575°C with a pressure of 5kn; at 1000°C, the pressure was increased to 10kn; at 1450°C, the pressure was increased to 16kn; when the temperature dropped to 1000°C, the pressure was released. In addition, the pulse on/off ratio of the SPS device is 6/4, and the pulse frequency is 30-40KHz. The as-prepared ceramics were used in prototype lamps of 450nm laser diodes, showing increased luminous flux (238-472lm) and stable luminous efficiency (54.3-56.6lm/W) with increasing driving power (up to 8.7W) (Investigation of an LuAG: Ce translucent ceramic synthesized via spark plasma sintering: Towards afacile synthetic route, robust thermal performance, and high-power solid statelaser lighting, Journal of the European Ceramic Society, 2018, 38, 343-347). Li et al. reported a LuAG:Ce transparent ceramic plate with TEOS and MgO used as sintering aids at 0.8 wt% and 0.08 wt%, respectively. The raw materials were mixed by high-energy ball milling for 12 h using alcohol as the medium. The powder compacts were vacuum sintered at 1850 °C for 10–30 h and then air annealed at 1450 °C for 20 h. The optical conversion efficiency is 101.3lm/W, and the output luminous flux is 1540lm (Low Etendue Yellow-Green Solid-State Light Generation by Laser-pumped LuAG: Ce Ceramic, IEEE Photonics Technology Letters, 2018, 30(10), 939-942). Zhang et al. fabricated LuAG:Ce ceramic green converters with different pore properties under vacuum by adjusting the sintering temperature by a solid-state reaction method. 0.5 wt% of tetraethyl orthosilicate (TEOS) and 0.1 wt% of MgO were added as sintering aids. The green body was first pre-sintered in a muffle furnace at 800 °C for 6 h, and then sintered under vacuum at different temperatures (1600 °C to 1750 °C) for 3 h. Annealed at 1400 °C for 3 h in air to eliminate oxygen vacancies. Under the excitation of blue laser (450nm), the optimized sample showed high luminous efficiency above 200lm/W and high thermal stability of luminescence (Pore-existingLu ₃ Al ₅ O ₁₂ : Ce ceramic phosphor: An efficient green color converter for laserlight source , Journal of Luminescence, 2018, 197, 331-334). Xu et al. of Xiamen University used 0.5 wt% TEOS as a sintering additive in ethanol for ball milling and mixing for 28 h. The powder compacts were vacuum sintered at 1720-1780°C at 10 ^-3 Pa for 5h, and then annealed at 1450°C in air for 10h. The thermal saturation performance of LuAG:Ce ceramics was studied, with a flux of 3967.3lm at a high power density of 49W/mm ² , and the calculated lumen efficiency was 161.9lm/W (A search forextra-high brightness laser-driven color converters by investigating thermally induced luminance saturation, Journal of Materials Chemistry C, 2019, 7, 11449-11456).

So far, no major breakthroughs have been made in the study of the laser properties of LuAG:Ce fluorescent ceramics. It is of great significance to develop a LuAG:Ce fluorescent ceramic with remarkable economic benefits and broad application prospects with high luminescence performance.

SUMMARY OF THE INVENTION

According to one aspect of the present application, a fluorescent ceramic is provided, which has the characteristics of high density, good laser saturation performance, and high luminous efficiency, can be used as a key material for color converters, and has huge potential in the field of high-power laser lighting. application potential.

The fluorescent ceramic is characterized in that:

The fluorescent ceramic is at least one selected from the substances with the general formula shown in formula I;

Lu _3-xy Ce _{x My} Al _5-y Q _y O ₁₂ Formula I

Wherein, M represents a first co-doping element, and the first co-doping element is selected from at least one of alkaline earth metal elements;

Q represents a second co-doping element, and the second co-doping element is selected from at least one of Si element and Ge element;

The value range of x is 0.0001≤x≤0.3;

Optionally, the upper limit of x is selected from 0.001, 0.005, 0.01, 0.015, 0.15, and 0.3.

Optionally, the lower limit of x is selected from 0.0001, 0.001, 0.005, 0.01, 0.015, and 0.15.

The value range of y is 0≤y≤2.

Optionally, the upper limit of y is selected from 0.02, 1, and 2.

Optionally, the lower limit of y is 0.01, 0.02, or 1.

Optionally, the M element is selected from one or a combination of Mg element, Ca element, Sr element, and Ba element.

Optionally, the M element is a combination of Mg element and Sr element.

Optionally, the M element is a combination of Mg element and Ba element.

Optionally, the M element is a Ba element.

Optionally, the M element is Mg element.

Optionally, the fluorescent ceramics are Lu _2.975 Ce _0.005 Ba _0.02 Al _4.98 Si _0.02 O ₁₂ , Lu _2.989 Ce _0.001 Ba _0.01 Al _{4.9 9} Si _0.01 O ₁₂ , Lu _2.975 Ce _0.015 Ba _0.005 Mg _0.005 Al _4.99 Si _0.01 O ₁₂ , Lu _2.965 Ce _0.015 Mg _0.02 Al _4.98 Ge _0.02 O ₁₂ , Ce _0.01 Mg ₂ Lu _0.99 Al ₃ Si ₂ O ₁₂ , Lu _1.7 Ce _0.3 Sr _0.4 Mg _0.6 Al ₄ Si _0.5 Ge _0.5 O ₁₂ .

Optionally, the fluorescent ceramic is a single LuAG cubic phase.

According to another aspect of the present application, a method for preparing fluorescent ceramics is provided. The method has the advantages of simple process and low production cost, and the prepared fluorescent ceramics have higher saturation threshold and higher saturation threshold under excitation by high-power blue light laser. Strong luminous flux, and its stimulated emission wavelength can supplement the missing green components in lighting, which has great application potential in the field of high-power laser lighting.

A method for preparing fluorescent ceramics, comprising the following steps:

1) Preparation of precursor powder;

2) forming the precursor powder to obtain a ceramic green body;

3) Sintering and machining the ceramic green body to obtain fluorescent ceramics.

Optionally, the step 1) is specifically: weighing Lu source, Ce source, Al source and co-doped ion M source according to the stoichiometric ratio Lu _3-xy C _x M _y Al _5-y Q _y O ₁₂ and Q source powder are mixed uniformly by wet ball milling to obtain precursor powder.

Optionally, 0.0001≤x≤0.3.

Optionally, the upper limit of x is selected from 0.001, 0.005, 0.01, 0.015, 0.15, 0.3.

Optionally, the lower limit of x is selected from 0.0001, 0.001, 0.005, 0.01, 0.015, and 0.15.

Optionally, 0≤y≤2.

Optionally, the upper limit of y is selected from 0.02, 1, and 2.

Optionally, the lower limit of y is 0.01, 0.02, or 1.

Optionally, the Lu source is one or a combination of Lu oxides or salts.

Optionally, the Lu source is Lu ₂ O ₃ .

Optionally, the Ce source is one or a combination of Ce oxides or salts.

Optionally, the Ce source is CeO ₂ or Ce ₂ (CO ₃ ) ₂ .

Optionally, the Al source is one or a combination of Al oxides or salts.

Optionally, the Al source is Al ₂ O ₃ .

Optionally, the M source is one or a combination of oxides or salts of Mg, Ca, Sr, and Ba.

Optionally, the M source is one or a combination of MgCO ₃ , CaCO ₃ , SrCO ₃ , BaCO ₃ , MgO, CaO, BaO, and SrO.

Optionally, the Q source is one or a combination of oxides or salts of Si and Ge.

Optionally, the Q source is SiO ₂ and/or GeO ₂ .

Optionally, the ball milling medium is absolute ethanol.

Optionally, the rotational speed of the ball mill is 60-300 rpm/min.

Optionally, the upper limit of the rotation speed of the ball mill is 100, 120, 200, 200, and 300 rpm/min.

Optionally, the lower limit of the rotation speed of the ball mill is 60, 100, 120, and 200 rpm/min.

Optionally, the ball milling time is 5-30h.

Optionally, the upper limit of the ball milling time is 10, 15, 20, and 30 h.

Optionally, the lower limit of the ball milling time is 5, 10, 15, and 20 h.

Optionally, in the step 2), the method for forming the precursor powder is selected from one or more combinations of dry pressing plus cold isostatic pressing, grouting, colloidal molding or gel injection molding. .

Optionally, in the step 2), the precursor powder is dried and sieved before the precursor powder is formed.

Optionally, the sintering method of the ceramic green body in the step 3) is selected from any one of vacuum sintering, oxygen sintering followed by hot isostatic pressing sintering, and hot pressing sintering.

Optionally, the sintering temperature of the vacuum sintering is 1500-1800°C.

Optionally, the upper limit of the sintering temperature of the vacuum sintering is selected from 1750°C and 1800°C.

Optionally, the lower limit of the sintering temperature of the vacuum sintering is selected from 1500 and 1750°C.

Optionally, the sintering holding time of the vacuum sintering is 5-20 h.

Optionally, the oxygen sintering temperature is 1500-1800°C.

Optionally, the oxygen sintering temperature is 1650°C.

Optionally, the oxygen sintering holding time is 5-30h.

Optionally, the oxygen sintering holding time is 20h.

Optionally, the hot isostatic pressing sintering temperature is 1500-1750°C.

Optionally, the hot isostatic pressing sintering temperature is 1600°C.

Optionally, the hot isostatic pressing sintering pressure is 100-200Mpa.

Optionally, the hot isostatic pressing sintering pressure is 200Mpa.

Optionally, the hot isostatic pressing sintering holding time is 1-4h.

Optionally, the hot isostatic pressing sintering holding time is 4h.

Optionally, the hot pressing sintering temperature is 1500-1750°C.

Optionally, the hot pressing sintering pressure is 20-100MPa.

Optionally, the upper limit of the hot pressing sintering pressure is selected from 50 and 100 MPa.

Optionally, the upper limit of the hot pressing sintering pressure is selected from 20 and 50 MPa.

Optionally, the hot pressing sintering holding time is 1-8h

Optionally, the hot-pressing sintering holding time is 4-5h.

Optionally, in the step 3), after the ceramic green body is sintered, it further includes: annealing treatment.

Optionally, the annealing treatment atmosphere is one or a combination of air or reducing atmosphere.

Optionally, the reducing atmosphere is carbon monoxide and/or hydrogen.

Optionally, the annealing temperature in step 3) is 1200-1500°C.

Optionally, in the step 3), the upper limit of the annealing temperature is selected from 1450°C and 1500°C.

Optionally, the lower limit of the annealing temperature in the step 3) is selected from 1200 and 1450°C.

Optionally, in the step 3), the annealing treatment holding time is 5-50h.

Optionally, in the step 3), the upper limit of the holding time of the annealing treatment is selected from 8, 10, and 50h.

Optionally, in the step 3), the lower limit of the holding time of the annealing treatment is selected from 5, 8, and 10 h.

Optionally, the specific steps of machining in the step 3) are: mechanical thinning and polishing.

According to yet another aspect of the present invention, there is provided an application of the fluorescent ceramic according to any one of the above technical solutions or the fluorescent ceramic prepared by the preparation method according to any one of the above technical solutions in high-power laser lighting .

The beneficial effects that this application can produce include:

1) In a fluorescent ceramic provided by the present application, due to the co-doping effect of the doped M ²⁺ and Q ⁴⁺ ions to achieve charge balance, the variable valence Ce ³⁺ ions in the ceramic are inhibited from being transformed into Ce ⁴⁺ , so most of the fluorescent ceramics are composed of Ce ³⁺ luminescent ions. The fluorescent ceramic has the characteristics of high density, good laser saturation performance and high luminous efficiency, can be used as a key material for color converters, and has great application potential in the field of laser lighting.

2) For a fluorescent ceramic provided by the present application, the preparation process adopts an annealing process in air or a reducing atmosphere for a long time, so that Ce ³⁺ ions are inhibited from being oxidized to Ce ⁴⁺ ions, and the relative concentration of Ce ³⁺ is increased. , and finally obtained fluorescent ceramics containing Ce ³⁺ with better luminescence performance.

3) The preparation method of a fluorescent ceramic provided by the present application, the method adopts the high-purity raw materials selected by the present application and the provided process conditions, and through the charge compensation mechanism, equal amounts of co-doping M ²⁺ and Q ⁴⁺ ions to The charge balance is maintained, combined with the deep annealing process in a reducing atmosphere after sintering, so as to obtain high-performance fluorescent ceramics containing Ce ³⁺ luminescent ions, and at the same time, it has the advantages of simple process and low production cost.

4) The present application provides an application of fluorescent ceramics in high-power laser lighting, and the fluorescent ceramics of the present application have a high saturation threshold (power density over 19.75W/mm ² ) and a relatively high saturation threshold under high-power blue laser excitation. The luminous flux (up to 2899.5lm), and its stimulated emission wavelength can supplement the missing green component in lighting, and has great application potential in the field of high-power laser lighting.

Description of drawings

1 is the XRD pattern of alkaline earth metal Ba ²⁺ ions and Si ⁴⁺ doped LuAG: 0.5% Ce, 2% Ba, 2% Si fluorescent ceramics prepared in Example 1 with a diameter of 15 mm and a thickness of 1 mm.

2 is the excitation spectrum (λ _em =520 nm) and emission spectrum (λ _ex =450 nm) of the LuAG: 0.1% Ce, 1% Ba, 1% Si fluorescent ceramics prepared in Example 2.

FIG. 3 is the device spectrum of the LuAG: 0.5% Ce, 2% Ba, 2% Si fluorescent ceramic prepared in Example 1 under the irradiation of a 9.5W blue laser.

4 is the luminous flux curve of LuAG: 0.1% Ce, 1% Ba, 1% Si fluorescent ceramics prepared in Example 2 and LuAG: 0.5% Ce fluorescent ceramics prepared in Comparative Example 1.

Detailed ways

The present application will be described in detail below with reference to the examples, but the present application is not limited to these examples.

Unless otherwise specified, the raw materials in the examples of this application are all purchased through commercial channels.

In the process of preparing alkaline earth metal ion-doped fluorescent ceramics, the preferred raw materials are:

Raw materials of matrix and activated ions: commercial high-purity (more than 99.9% purity) ɑ-Al ₂ O ₃ or γ-Al ₂ O ₃ , Lu ₂ O ₃ , CeO ₂ or Ce ₂ (CO ₃ ) ₂ for solid-phase method , or its corresponding nitrate hydrate;

Doping ion raw material: commercial high-purity (above 99.9% purity) MgCO ₃ , CaCO ₃ , SrCO ₃ , BaCO ₃ , MgO, CaO, BaO, SrO or the corresponding nitrate crystalline hydrate, commercial high-purity (purity 99.9%) % or more) SiO ₂ , GeO ₂ .

Example 1

Lu _2.975 Ce _0.005 Ba _0.02 Al _4.98 Si _0.02 O ₁₂ (x=0.005, y=0.02) and preparation method thereof

The concentration of active ion Ce ³⁺ is 0.5 at. %, and the doping concentration of Ba ²⁺ and Si ⁴⁺ is 2 at. %. The commercially available raw material powders of Lu ₂ O ₃ , Al ₂ O ₃ , CeO ₂ , BaCO ₃ and SiO ₂ with a purity of 99.99% were weighed according to the stoichiometric ratio of Lu _2.975 Ce _0.005 Ba _0.02 Al _4.98 Si _0.02 O ₁₂ . Anhydrous ethanol was used as the ball-milling medium, and the ball-milling speed was 60rpm/min on a high-energy ball mill for 30h. After the ball-milled slurry is dried and sieved, the ceramic green body is obtained by dry pressing and cold isostatic pressing in sequence. The green body is sintered in a hot-pressing furnace at a sintering temperature of 1750°C, a pressure of 50MPa, and a time of 5h. The sintered ceramic samples were annealed in a carbon monoxide atmosphere at 1450°C for 10 h, then mechanically thinned and polished to obtain LuAG: 0.5% Ce, 2% Ba, 2% Si fluorescent transparent ceramics with a diameter of 15mm and a thickness of 1mm.

Example 2

Lu _2.989 Ce _0.001 Ba _0.01 Al _4.99 Si _0.01 O ₁₂ (x=0.001, y=0.01) and preparation method thereof

The concentration of active ion Ce ³⁺ is 0.1 at. %, and the doping concentration of Ba ²⁺ and Si ⁴⁺ is 1 at. %. The commercially available raw material powders of Lu ₂ O ₃ , Al ₂ O ₃ , CeO ₂ , BaCO ₃ and SiO ₂ with a purity of 99.99% were weighed according to the stoichiometric ratio of Lu _2.989 Ce _0.001 Ba _0.01 Al _4.99 Si _0.01 O ₁₂ . Anhydrous ethanol was used as the ball milling medium, and the ball milling speed was 120rpm/min for 15h. After the ball-milled slurry is dried and sieved, the ceramic green body is obtained by dry pressing and cold isostatic pressing in sequence. The green body is sintered in a vacuum furnace at a sintering temperature of 1800 °C and a time of 5 hours. The ceramic samples obtained by vacuum sintering were annealed at 1500 ℃ in air atmosphere for 8 hours, then mechanically thinned and polished to obtain LuAG: 0.1% Ce, 1% Ba, 1% Si fluorescent transparent ceramics with a diameter of 15mm and a thickness of 1mm.

Example 3

Lu _2.975 Ce _0.015 Ba _0.005 Mg _0.005 Al _4.99 Si _0.01 O ₁₂ (x=0.015, y=0.01) and preparation method thereof

The concentration of active ion Ce ³⁺ is 1.5 at.%, the combined doping concentration of Ba ²⁺ and Mg ²⁺ is 0.5 at. % and 0.5 at. %, respectively, and the doping concentration of Si ⁴⁺ is 1 at. %. The commercially available raw material powders of Lu ₂ O ₃ , Al ₂ O ₃ , Ce ₂ (CO ₃ ) ₃ , BaCO ₃ , MgO and SiO ₂ with a purity of 99.99% were prepared as Lu _2.975 Ce _0.015 Ba _0.005 Mg _0.005 Al _4.99 Si _0.01 The chemical formula of O ₁₂ was weighed, and absolute ethanol was used as the ball-milling medium, and the ball-milling speed was 300rpm/min on a high-energy ball mill for 5h. After the ball-milled slurry is dried and sieved, the ceramic green body is obtained by dry pressing and cold isostatic pressing in sequence. The ceramic samples obtained by vacuum sintering were annealed in hydrogen for 5 hours, and the annealing temperature was 1500 °C. Finally, they were mechanically thinned and polished to obtain LuAG with a diameter of 15 mm and a thickness of 1 mm: 1.5% Ce, 0.5% Ba, 0.5% Mg, 1% Si fluorescent ceramic.

Example 4

Lu _2.965 Ce _0.015 Mg _0.02 Al _4.98 Ge _0.02 O ₁₂ (x=0.015, y=0.02) and preparation method thereof

The concentration of activating ions Ce ³⁺ is 1.5 at. %, and the doping concentration of Mg ²⁺ and Ge ⁴⁺ is 2 at. %. Weigh commercially available raw material powders of Lu ₂ O ₃ , Al ₂ O ₃ , CeO ₂ , GeO ₂ and MgO with a purity of 99.99% according to the stoichiometric ratio Lu _2.965 Ce _0.015 Mg _0.02 Al _4.98 Ge _{0.0 2} O ₁₂ , using absolute ethanol as the ball milling medium, and ball milling at 100rpm/min for 20h. The ball-milled slurry was gel-injected to obtain a ceramic green body, and the green body was sintered in oxygen at 1650°C for a holding time of 20h. Then hot isostatic pressing sintering was carried out at 1600°C, pressure 200MPa, and holding time was 4h. The obtained ceramic sample was annealed in a carbon monoxide atmosphere at 1200°C for 50 hours, and then mechanically thinned and polished to obtain a dense and transparent LuAG: 1.5%Ce, 2%Mg, 2%Ge fluorescent ceramic with a diameter of 15mm and a thickness of 1mm.

Example 5

Ce _0.01 Mg ₂ Lu _0.99 Al ₃ Si ₂ O ₁₂ (x=0.01, y=2) and its preparation method

The concentration of activating ion Ce ³⁺ is 1.0 at. %, and Mg ²⁺ replaces Lu ³⁺ . The commercially available raw material powders of Lu ₂ O ₃ , Al ₂ O ₃ , CeO ₂ , SiO ₂ and MgO with a purity of 99.99% were weighed according to the stoichiometric ratio of Ce _0.01 Mg ₂ Lu _0.99 Al ₃ Si ₂ O ₁₂ , and the Water ethanol was used as the ball-milling medium, and the ball-milling speed was 200rpm/min for 10h. After the ball-milled slurry is dried and sieved, a ceramic china is obtained through colloidal molding, and the china is sintered in a vacuum at 1500°C for a holding time of 20h. The obtained ceramic sample was annealed in a hydrogen atmosphere at 1200°C for 50 hours, and then mechanically thinned and polished to obtain a dense and transparent Ce _0.01 Mg ₂ Lu _0.99 Al ₃ Si ₂ O ₁₂ fluorescent ceramic with a diameter of 15 mm and a thickness of 1 mm.

Example 6

Lu _1.7 Ce _0.3 Sr _0.4 Mg _0.6 Al ₄ Si _0.5 Ge _0.5 O ₁₂ (x=0.3, y=1) and preparation method thereof

The commercially available raw material powders of Lu ₂ O ₃ , SrCO ₃ , MgO, Al ₂ O ₃ , CeO ₂ , SiO ₂ and GeO ₂ with a purity of 99.99% were prepared according to the stoichiometric ratio Lu _1.7 Ce _0.3 Sr _0.4 Mg _0.6 Al ₄ Si _0.5 Ge _0.5 O ₁₂ was weighed, and absolute ethanol was used as the ball milling medium, and the ball was milled at a ball milling speed of 200 rpm/min for 10 h. After the ball-milled slurry is dried and sieved, the ceramic green body is obtained by colloidal molding, and the green body is sintered at 1500°C under hot pressing, pressure 100Mpa, and holding time 4h. The obtained ceramic samples were annealed in a hydrogen atmosphere at 1200 °C for 50 h, then mechanically thinned and polished to obtain dense and transparent Lu _1.7 Ce _0.3 Sr _0.4 Mg _{0.6 Al4} Si _0.5 Ge _0.5 O ₁₂ with a diameter of 15 mm and a thickness of 1 mm. Fluorescent ceramics.

Comparative Example 1

Lu _2.995 Ce _0.005 Al ₅ O ₁₂ (x=0.005, y=0.000) and preparation method thereof

The concentration of active ion Ce ³⁺ is 0.5 at. %, and the doping concentration of M ²⁺ and Q ⁴⁺ is 0 at. %. The commercially available raw material powders of Lu ₂ O ₃ , Al ₂ O ₃ and CeO ₂ with a purity of 99.99% were weighed according to the stoichiometric ratio of Lu _2.995 Ce _0.005 Al ₅ O ₁₂ , and absolute ethanol was used as the ball milling medium at 140 rpm/min. The ball milling speed was ball milled on a high-energy ball mill for 8h. After the ball-milled slurry is dried and sieved, the ceramic green body is obtained by dry pressing and cold isostatic pressing in sequence. The green body is sintered in a vacuum furnace at a sintering temperature of 1800 °C and a time of 5 hours. The ceramic samples obtained by vacuum sintering were annealed at 1450 ℃ in air atmosphere for 10 h, then mechanically thinned and polished to obtain dense and transparent LuAG:0.5%Ce fluorescent ceramics (LuAG:Ce) with a diameter of 15 mm and a thickness of 1 mm.

Performance test of fluorescent ceramics in Example 1, Example 2 and Comparative Example 1

扫描电压40kV、扫描电流40mA、扫描步长为0.02°、扫描角度范围10-90°、扫描速度为10°/min。激发、发射光谱通过日本日立公司生产的F4600光谱仪测试获得，氙灯为激发光源。激光性能通过日本大冢生产的QE2100光谱仪系统和美国蓝菲公司生产的积分球系统测试获得。The phase structure test was carried out using the D8 Advance automatic X-ray diffractometer from Bruker AXS, Germany, and the test conditions were copper target K _ɑ rays

The scanning voltage is 40kV, the scanning current is 40mA, the scanning step is 0.02°, the scanning angle range is 10-90°, and the scanning speed is 10°/min. The excitation and emission spectra were obtained by the F4600 spectrometer produced by Hitachi, Japan, and the xenon lamp was used as the excitation light source. The laser performance is obtained by testing the QE2100 spectrometer system produced by Japan's Otsuka and the integrating sphere system produced by the American Bluefield Company.

Figure 1 is the XRD pattern of LuAG: 0.5%Ce, 2%Ba, 2%Si fluorescent ceramics prepared according to Example 1, indicating that the prepared ceramics is a single LuAG cubic phase, light-emitting ions Ce ³⁺ and doping ions Ba ^{2 +} , Si ⁴⁺ can be well dissolved into the lattice.

Figure 2 is the excitation spectrum ( _{λ em} ^{= 520nm} ) and emission spectrum ( λ _ex =450 nm). The abscissa is the wavelength, and the ordinate is the luminous intensity. The optimal excitation peak is located around 450 nm, which matches well with the emission spectrum of commercial blue light LDs. The luminescence peak of the prepared sample is at 520 nm, which is located in the green emission region.

FIG. 3 is the device spectral laser emission spectrum of LuAG: 0.5% Ce, 2% Ba, 2% Si fluorescent ceramics prepared according to Example 1 under the irradiation of 9.5W blue laser. The abscissa is the wavelength, and the ordinate is the spectral power. The luminescence peak with a wavelength of 450nm is the luminescence of 9.5W blue laser, and the luminescence peak in the range of 460-800nm is the luminescence of the prepared ceramics under the excitation of 9.5W blue laser, and the luminescence peak is in the green light region. It is indicated that the prepared fluorescent ceramic is a promising green conversion material for laser illumination, thereby accelerating the rapid development of laser-driven illumination.

FIG. 4 shows the luminous flux curves of LuAG: 0.1% Ce, 1% Ba, 1% Si fluorescent ceramics prepared according to Example 2 and LuAG: 0.5% Ce prepared in Comparative Example 1. The abscissa is the laser power density, and the ordinate is the luminous flux. The ceramic prepared in Comparative Example 1 exhibited luminescence saturation at a power density of 10.83W/mm ² , the luminous flux at this time was 1203.6lm, and the lumen efficiency was 141.6lm/W. The maximum lumen efficiency of the ceramic of Comparative Example 1 is 167.3lm/W, the corresponding optical power density at this time is 5.73W/mm ² , and the luminous flux is 753.0lm. The ceramic prepared in Example 2 did not appear saturated at power density exceeding 19.75W/mm ² , the luminous flux at this time was 2899.5lm, and the lumen efficiency was 187.1lm/W. The maximum lumen efficiency of the ceramic prepared in Example 2 is 213.7lm/W, the corresponding optical power density is 9.55W/mm ² at this time, and the luminous flux is 1603.1lm. Compared with Comparative Example 1, Example 2 has a 58% increase in luminous flux and a 24% increase in lumen efficiency. In the current report, 213.7lm/W is the highest known efficiency value, indicating that the ceramic of the present invention has more excellent performance under the application of high-power blue laser.

The above are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Without departing from the scope of the technical solutions of the present application, any changes or modifications made by using the technical contents disclosed above are equivalent to equivalent implementation cases and fall within the scope of the technical solutions.

Claims (10)

1. The fluorescent ceramic is characterized by comprising at least one selected from substances with a composition general formula shown as a formula I;

Lu_3-x-yCe_xM_yAl_5-yQ_yO₁₂formula I

Wherein M represents a first co-doping element selected from at least one of alkaline earth metal elements;

q represents a second co-doping element, and the second co-doping element is at least one selected from Si element and Ge element;

the value range of x is more than or equal to 0.0001 and less than or equal to 0.3;

the value range of y is more than or equal to 0 and less than or equal to 2.

2. The fluorescent ceramic of claim 1,

0.0001≤x≤0.15，0.01≤y≤1。

3. the fluorescent ceramic of claim 1, wherein the M element is selected from one or more of Mg element, Ca element, Sr element and Ba element.

4. The fluorescent ceramic of claim 1, wherein the M element is:

a combination of Mg and Sr;

or a combination of Mg and Ba elements;

or Ba element;

or an Mg element.

5. A method of making the fluorescent ceramic of claim 1, comprising the steps of:

1) preparing precursor powder;

2) forming the precursor powder to obtain a ceramic biscuit;

3) and sintering and machining the ceramic biscuit to obtain the fluorescent ceramic.

6. The preparation method according to claim 5, wherein the precursor powder in step 2) is formed by one or more methods selected from dry pressing and cold isostatic pressing, slip casting, colloidal molding or gel casting.

7. The production method according to claim 5, wherein in the step 3), the sintering includes any one of vacuum sintering, oxygen sintering followed by hot isostatic pressing sintering, and hot press sintering;

preferably, the process parameters of the vacuum sintering are as follows: the sintering temperature is 1500-1800 ℃, and the heat preservation time is 5-20 h;

preferably, the process parameters of the oxygen sintering are as follows: the sintering temperature is 1500-1800 ℃, and the heat preservation time is 5-30 h;

the hot isostatic pressing sintering process parameters are as follows: the sintering temperature is 1500-1750 ℃, the sintering pressure is 100-200MPa, and the heat preservation time is 1-4 h;

preferably, the process parameters of the hot-pressing sintering are as follows: the sintering temperature is 1500-1750 ℃, the sintering pressure is 20-100MPa, and the heat preservation time is 1-8 h.

8. The method according to claim 5, wherein the step 3) further comprises, after sintering the ceramic green body: annealing treatment;

the annealing treatment atmosphere is one or a combination of air and reducing atmosphere;

preferably, the reducing atmosphere is carbon monoxide and/or hydrogen.

9. The method according to claim 8, wherein the annealing treatment is carried out for a holding time of 5 to 50 hours.

10. Use of the fluorescent ceramic according to any one of claims 1 to 4 or the fluorescent ceramic prepared by the preparation method according to any one of claims 5 to 9 in high-power laser illumination.

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