A composite fluorescent ceramic material and preparation method thereof

Abstract

The present invention discloses a composite fluorescent ceramic and a preparation method thereof. The general chemical formula of the composite fluorescent ceramic is Ca 1‑x Mn x O‑(Re 1‑ y Ce y )3Al5O 12 , where 0.04≤x≤0.08, 0 <y<0.01,Re 3+ Lu 3+ 、Y 3+ or Gd 3+ One of them, Ca 1‑x Mn x O and (Re 1‑ y Ce y )3Al5O 12 The mass ratio of is 10-25:75-90, and Ca is first prepared by a high temperature solid phase method. 1‑x Mn x O powder, the obtained powder and (Re 1‑y Ce y )3Al5O 12 The raw material powders were mixed and sintered by solid phase reaction to obtain Ca 1‑x Mn x O‑(Re 1‑y Ce y )3Al5O 12 Complex phase fluorescent ceramics, due to CaO: Mn is wrapped in (Re 1‑y Ce y )3Al5O 12 The problem of CaO absorbing moisture easily can be effectively avoided inside the ceramic. The composite fluorescent ceramic of the present invention emits Ce with a main wavelength of 510-565nm at the same time under the excitation of 440-460nm blue laser. 3+ Yellow-green fluorescence and Mn dominant wavelength at 600‑630nm 2+ Orange fluorescence, thermal conductivity can reach 14-20Wm at room temperature ‑1 K ‑1 , high thermal conductivity, when the blue laser pump density is 50-80W / mm 2 When the power is increased, the relative light conversion efficiency of the composite fluorescent ceramic is 99%-99.8% of the initial efficiency, and the color rendering index is 80-95, which can achieve improved luminescence stability and light color quality under high pump power density excitation.

Description

Technical Field

[0001] The present invention belongs to the field of electrodeless luminescent materials and relates to a fluorescent ceramic material, in particular to a composite ceramic material with high color rendering index and light saturation resistance and a preparation method thereof. Background Art

[0002] Semiconductor white light laser lighting (laser dioxide, LD) is the most promising solid-state lighting technology in the 21st century. It can effectively avoid "efficiency drop" and has significant advantages such as higher brightness, smaller size, longer life, and longer illumination distance. 3+ :Re3Al5O 12 Fluorescent conversion materials are still a mature and stable technical solution for white light generation. However, Ce 3+ Doped garnet fluorescent ceramics still face the problem of lack of red light components in the spectrum, resulting in low color rendering index and poor light color quality. 2+ It is the most effective means to improve color rendering. 2+ The dd spin-forbidden transition of Mn also causes a significant loss in luminous efficiency after energy transfer. 2+ Its own absorption cross section at 450-450nm is the key to alleviating the decline in efficiency.

[0003] Luminescence saturation of fluorescent ceramics is another important indicator of high-power white light LD lighting, which mainly includes thermoluminescence saturation and photoluminescence saturation. The former can be alleviated by enhancing the thermal conductivity of the material. In addition, the non-thermal effect caused by strong excitation power can be called photoluminescence saturation. Xie and his research team pointed out that fluorescence lifetime is the key factor affecting the photoexcitation quenching rate. Due to the Mn 2+ The luminescence belongs to 4 T1→ 6 A1 radiative transition is a parity and spin doubly forbidden transition, so its fluorescence lifetime is usually in the millisecond range, making it easy for the material to reach light saturation when the light excitation density is high (Acta Mater., 209(2021)116813). Setler et al. have pointed out that Ca5(PO4)3Cl:Eu 2+ ,Mn 2+ When the phosphor is excited by a high energy density near-ultraviolet LED, it will produce excited Mn 2+ The interaction between Mn and Mg leads to energy upconversion and radiationless relaxation (Appl.Phys.Lett.,92(2008)081104). Another key to achieve high-power laser fluorescent white light is how to overcome the Mn 2+The above bottlenecks limit the application of high-quality fluorescent ceramics in high-power density laser lighting. Summary of the Invention

[0004] One of the objectives of the present invention is to provide a multiphase fluorescent ceramic with high thermal conductivity, high color rendering index and resistance to light saturation. By introducing the second phase CaO:Mn into the garnet matrix, while supplementing the red light component in the spectrum, the second phase's hygroscopic properties are avoided, and the thermal conductivity and light saturation resistance of the ceramic are improved, so that it can better meet the application of special scenarios under high-power excitation, such as underwater lighting, seabed detection and other fields.

[0005] The second object of the present invention is to provide a method for preparing a composite fluorescent ceramic having high thermal conductivity, high color rendering index and anti-light saturation properties.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows: its chemical formula is Ca 1-x Mn x O-(Re 1- y Ce y )3Al5O 12 , where 0.04≤x≤0.08, 0 <y<0.01,Re 3+ Lu 3+ 、Y 3+ or Gd 3+ One of them, Ca 1-x Mn x O and (Re 1-y Ce y )3Al5O 12 The mass ratio is 10~25:75~90.

[0007] The composite fluorescent ceramic of the present invention emits Ce with a main wavelength of 510-565nm under the excitation of 440-460nm blue laser. 3+ Yellow-green fluorescence and Mn with a dominant wavelength of 600-630nm 2+ Orange fluorescence; its thermal conductivity at room temperature can reach 16-20Wm -1 K -1 ; When the blue laser pump density is 50-80W / mm 2 When the composite fluorescent ceramic is used, the relative light conversion efficiency is 99%-99.8% of the initial efficiency, the obtained white light color temperature is 3500-5500K, and the color rendering index is 80-95.

[0008] The present invention also provides a method for preparing the above-mentioned multiphase fluorescent ceramic, which comprises the following specific steps:

[0009] Step 1: Weigh the CaCO3 and MnCO3 raw material powders in the CaO:Mn phase according to the mass ratio and stoichiometric ratio, add 0.1-0.2 mol% of a sintering aid, and add alcohol as a solvent. Use a planetary ball mill to mix at a speed of 120-180 r / min for 12-24 hours. Dry the milled slurry at a temperature of 40-60°C for 10-24 hours. Then, crush the dried raw material powder and pass it through a 100-200 mesh sieve. The resulting powder is calcined in a muffle furnace at a temperature of 900-1100°C.

[0010] Step 2: Weigh according to the stoichiometric ratio (Re 1-y Ce y )3Al5O 12 The Al2O3, Y2O3, CeO2 raw material powders and the CaO:Mn powders in step 1 are added with tetraethyl orthosilicate (TEOS) sintering aid and alcohol as a solvent; the powder raw materials are placed in a ball mill, and planetary ball milling is performed while adding grinding balls for ball milling mixing at a ball milling speed of 200-250r / min and a ball milling time of 12-24h;

[0011] Step 3: The raw material powder of step 2 is subjected to isometric biaxial pressing at a pressure of 2-5 MPa, and then subjected to cold isostatic pressing at a pressure of 200-300 MPa and a holding time of 200-400 seconds to obtain a ceramic green body.

[0012] Step 4: Sinter the green blank obtained in step 3, then anneal without annealing, and finally perform double-sided polishing to obtain Ca 1-x Mn x O-(Re 1-y Ce y )3Al5O 12 Complex phase fluorescent ceramics.

[0013] As an improvement, in step one, the sintering aid is one of Al2O3, Ga2O3 or GeO2.

[0014] As an improvement, in step 4, the sintering method is one of vacuum sintering, hot pressing sintering, and hot isostatic pressing sintering, the sintering temperature is 1500-1700° C., and the heat preservation time is 5-24 hours.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. Since the thermal conductivity of CaO ceramics is higher than that of garnet, the thermal conductivity of composite fluorescent ceramic materials can reach 14-20Wm at room temperature. -1 K -1, which is more than 10 times that of traditional "phosphor + resin" materials and significantly better than single-phase garnet ceramics. Its good thermal stability can ensure the stable output of various optoelectronic properties, and it has good prospects in the field of high-power laser lighting applications.

[0017] 2. Compared with Ce 3+ and Mn 2+ Co-doped garnet matrix solution, the present invention uses Mn 2+ Designed to enter the CaO matrix and occupy the octahedral lattice, and form Mn 2+ -Mn 2+ Dimers can break Mn 2+ The spin-forbidden transition of Mn 2+ The absorption cross section and anti-light saturation characteristics of the blue laser pump density are 50-80W / mm 2 When the composite fluorescent ceramic is used, the relative light conversion efficiency is 99%-99.8% of the initial efficiency, the obtained white light color temperature is 3500-5500K, and the color rendering index is 80-95.

[0018] 3. Since CaO:Mn is encapsulated inside garnet ceramics, it can effectively avoid the problem of CaO easily absorbing moisture, and improve the stability of use in underwater lighting, seabed detection and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of the composite fluorescent ceramic in the present invention;

[0020] Figure 2 The crystal structure of CaO:Mn and Mn in the composite ceramic of the present invention 2+ Energy level transition diagram. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] To prepare 60 g of the target product, the raw material powders were weighed and the ingredients were shown in Table 1.

[0023] Table 1 Ingredients of Example

[0024]

[0025]

[0026] Example 1

[0027] Step 1: Weigh the CaCO3 and MnCO3 raw material powders in the CaO:Mn phase according to the mass ratio and chemical ratio shown in 1# in Table 1, add 0.1 mol% Al2O3 sintering aid, and add alcohol as a solvent. Mill the mixture using a planetary ball mill at a speed of 120 r / min for 12 hours. Dry the milled slurry at 40°C for 10 hours. Then, crush the dried raw material powders and pass them through a 100-mesh sieve. Calcinate the resulting powder in a muffle furnace at 900°C.

[0028] Step 2: Weigh Ce:Re3Al5O according to the stoichiometric ratio 12 The Al2O3, Lu2O3, CeO2 raw material powders and the CaO:Mn powders in step 1 are added with tetraethyl orthosilicate (TEOS) sintering aid and alcohol as solvent; the powder raw materials are placed in a ball mill, and planetary ball milling is performed while adding grinding balls for ball milling mixing at a ball milling speed of 200 r / min and a ball milling time of 12 h;

[0029] Step 3: The raw material powder of step 2 is subjected to isometric biaxial pressing at a pressure of 2 MPa, and then subjected to cold isostatic pressing at a pressure of 200 MPa and a holding time of 200 s to obtain a ceramic green body.

[0030] Step 4: Sinter the green blank obtained in step 3 under vacuum at 1500℃ for 5 hours, then anneal without annealing, and finally perform double-sided polishing to obtain 10% Ca 0.96 Mn 0.04 O-90% (Lu 0.998 Ce 0.002 )3Al5O 12 Complex phase fluorescent ceramics.

[0031] like Figure 1 In the composite fluorescent ceramic prepared in this embodiment, since CaO:Mn is encapsulated inside the garnet ceramic, the problem of CaO easily absorbing moisture can be effectively avoided. The thermal conductivity of the composite fluorescent ceramic prepared at room temperature is 16.0W / m·K as measured by a flash thermal conductivity meter. Figure 2 , due to Mn 2+ Entering into the CaO matrix and occupying adjacent octahedral sites, Mn 2+ -Mn 2+ Dimers, thus breaking up the Mn 2+ The spin-forbidden transition of Mn 2+ The absorption cross section and anti-light saturation characteristics of the reflective laser illumination device are based on the 445nm blue laser pump density of 50W / mm 2When the light is converted into luminescent light, the relative light conversion efficiency of the composite fluorescent ceramic is 99.8% of the initial efficiency, the obtained white light color temperature is 3500K, and the color rendering index is 80.

[0032] Example 2

[0033] Step 1: Weigh the CaCO3 and MnCO3 raw material powders in the CaO:Mn phase according to the mass ratio and chemical ratio shown in 2# in Table 1, add 0.2 mol% Al2O3 sintering aid, and add alcohol as a solvent. Use planetary ball milling to mix at a speed of 155 r / min for 12 hours. Dry the milled slurry at 45°C for 12 hours. Then, crush the dried raw material powders and pass them through a 100-mesh sieve. Calcinate the resulting powder in a muffle furnace at a temperature of 1000°C.

[0034] Step 2: Weigh Ce:Re3Al5O according to the stoichiometric ratio 12 The Al2O3, Lu2O3, CeO2 raw material powders and the CaO:Mn powders in step 1 are added with tetraethyl orthosilicate (TEOS) sintering aid and alcohol as solvent; the powder raw materials are placed in a ball mill, and planetary ball milling is performed while adding grinding balls for ball milling mixing at a ball milling speed of 220 r / min and a ball milling time of 15 h;

[0035] Step 3: The raw material powder of step 2 is subjected to isometric biaxial pressing at a pressure of 3 MPa, and then subjected to cold isostatic pressing at a pressure of 220 MPa and a holding time of 220 s to obtain a ceramic green body.

[0036] Step 4: Sinter the green blank obtained in step 3 under vacuum at 1600℃ for 10 hours, then anneal without annealing, and finally perform double-sided polishing to obtain 12% Ca 0.95 Mn 0.05 O-88% (Lu 0.996 Ce 0.004 )3Al5O 12 Complex phase fluorescent ceramics.

[0037] The thermal conductivity of the composite fluorescent ceramic prepared in this embodiment is 17.1W / m·K. When the 440nm blue laser pump density is 58W / mm 2 When the light is converted into electricity, the relative light conversion efficiency of the composite fluorescent ceramic is 99.6% of the initial efficiency, the obtained white light color temperature is 4323K, and the color rendering index is 84.

[0038] Example 3

[0039] Step 1: Weigh the CaCO3 and MnCO3 raw material powders in the CaO:Mn phase according to the mass ratio and chemical ratio shown in 3# in Table 1, add 0.15 mol% Ga2O3 as a sintering aid, and add alcohol as a solvent. Use a planetary ball mill to mix at a speed of 160 r / min for 18 hours. Dry the milled slurry at 50°C for 15 hours. Then, crush the dried raw material powders and pass them through a 150-mesh sieve. Calcinate the resulting powder in a muffle furnace at a temperature of 1050°C.

[0040] Step 2: Weigh Ce:Re3Al5O according to the stoichiometric ratio 12 The Al2O3, Y2O3, and CeO2 raw material powders and the CaO:Mn powders in step 1 are added with tetraethyl orthosilicate (TEOS) as a sintering aid and alcohol as a solvent; the powder raw materials are placed in a ball mill, and planetary ball milling is performed while adding grinding balls for ball milling mixing at a ball milling speed of 230 r / min and a ball milling time of 18 h;

[0041] Step 3: The raw material powder of step 2 is subjected to isometric biaxial pressing at a pressure of 4 MPa, and then subjected to cold isostatic pressing at a pressure of 250 MPa and a holding time of 240 s to obtain a ceramic green body.

[0042] Step 4: hot press sinter the green blank obtained in step 3 at 1500℃, keep warm for 5 hours, then do not anneal, and finally perform double-sided polishing to obtain 17% Ca 0.96 Mn 0.04 O-83% (Lu 0.995 Ce 0.005 )3Al5O 12 Complex phase fluorescent ceramics.

[0043] The thermal conductivity of the composite fluorescent ceramic prepared in this embodiment is 18.2W / m·K. The pumping density of the 450nm blue laser is 63W / mm 2 When the light is converted into electricity, the relative light conversion efficiency of the composite fluorescent ceramic is 99.4% of the initial efficiency, the obtained white light color temperature is 4945K, and the color rendering index is 88.

[0044] Example 4

[0045] Step 1: Weigh the CaCO3 and MnCO3 raw material powders in the CaO:Mn phase according to the mass ratio and chemical ratio shown in Table 1#4, add 0.2 mol% Ga2O3 sintering aid, and add alcohol as a solvent. Use planetary ball milling to mix at a speed of 170 r / min for 20 hours. Dry the milled slurry at 50°C for 20 hours. Then, crush the dried raw material powders and pass them through a 200-mesh sieve. Calcinate the resulting powder in a muffle furnace at a temperature of 1080°C.

[0046] Step 2: Weigh Ce:Re3Al5O according to the stoichiometric ratio 12 The Al2O3, Y2O3, and CeO2 raw material powders and the CaO:Mn powders in step 1 are added with tetraethyl orthosilicate (TEOS) as a sintering aid and alcohol as a solvent; the powder raw materials are placed in a ball mill and subjected to planetary ball milling while adding grinding balls for ball milling mixing at a ball milling speed of 240 r / min and a ball milling time of 22 h;

[0047] Step 3: The raw material powder of step 2 is subjected to isometric biaxial pressing at a pressure of 5 MPa, and then subjected to cold isostatic pressing at a pressure of 300 MPa and a holding time of 300 s to obtain a ceramic green body.

[0048] Step 4: The green blank obtained in step 3 is subjected to hot isostatic pressing sintering at 1700℃ and kept at this temperature for 3 hours. Then, no annealing is required and double-sided polishing is performed to obtain 20% Ca 0.93 Mn 0.07 O-80% (Lu 0.994 Ce 0.006 )3Al5O 12 Complex phase fluorescent ceramics.

[0049] The thermal conductivity of the composite fluorescent ceramic prepared in this embodiment is 18.8W / m·K. When the blue laser pump density is 74W / mm 2 When the light is converted into electricity, the relative light conversion efficiency of the composite fluorescent ceramic is 99.2% of the initial efficiency, the obtained white light color temperature is 5230K, and the color rendering index is 91.

[0050] Example 5

[0051] Step 1: Weigh the CaCO3 and MnCO3 raw material powders in the CaO:Mn phase according to the mass ratio and chemical ratio shown in #5 in Table 1, add 0.2 mol% GeO2 as a sintering aid, and add alcohol as a solvent. Mill the mixture using a planetary ball mill at a speed of 170 r / min for 20 hours. Dry the milled slurry at 60°C for 24 hours. Then, crush the dried raw material powders and pass them through a 200-mesh sieve. Calcinate the resulting powder in a muffle furnace at 1100°C.

[0052] Step 2: Weigh Ce:Re3Al5O according to the stoichiometric ratio 12 The Al2O3, Gd2O3, CeO2 raw material powders and the CaO:Mn powders in step 1 are added with tetraethyl orthosilicate (TEOS) sintering aid and alcohol as solvent; the powder raw materials are placed in a ball mill, and planetary ball milling is performed while adding grinding balls for ball milling mixing at a ball milling speed of 250 r / min and a ball milling time of 24 h;

[0053] Step 3: The raw material powder of step 2 is subjected to isometric biaxial pressing at a pressure of 5 MPa, and then subjected to cold isostatic pressing at a pressure of 300 MPa and a holding time of 400 s to obtain a ceramic green body.

[0054] Step 4: Sinter the green blank obtained in step 3 under vacuum at 1700℃ for 24 hours, then anneal without annealing, and finally perform double-sided polishing to obtain 25% Ca 0.92 Mn 0.08 O-75% (Lu 0.991 Ce 0.009 )3Al5O 12 Complex phase fluorescent ceramics.

[0055] The thermal conductivity of the composite fluorescent ceramic prepared in this embodiment is 20.0W / m·K. When the blue laser pump density is 80W / mm 2 When the light is converted into electricity, the relative light conversion efficiency of the composite fluorescent ceramic is 99% of the initial efficiency, the obtained white light color temperature is 5500K, and the color rendering index is 95.

Claims

1. A complex phase fluorescent ceramic material, characterized in that: Its general chemical formula is Ca 1-x Mn x O-(Re 1-y Ce y )3Al5O 12 , where 0.04≤x≤0.08, 0 <y<0.01,Re 3+ Lu 3+ 、Y 3+ or Gd 3+ One of them, Ca 1-x Mn x O and (Re 1-y Ce y )3Al5O 12 The mass ratio is 10~25:75~90.

2. The complex phase fluorescent ceramic material according to claim 1, characterized in that: Preferably, 0.05≤x≤0.06, 0.004≤y≤0.005, and the mass ratio is 12~17:83~88.

3. The multiphase fluorescent ceramic material according to claim 1, characterized in that: The composite fluorescent ceramic emits Ce with a main wavelength of 510-565 nm under the excitation of 440-460 nm blue laser. 3+ Yellow-green fluorescence and Mn with a dominant wavelength of 600-630 nm 2+ Orange fluorescence.

4. The complex phase fluorescent ceramic material according to claim 1, characterized in that: Thermal conductivity at room temperature can reach 14-20 Wm -1 K -1 .

5. The multiphase fluorescent ceramic material according to claim 1, characterized in that: When the blue laser pump density is 50-80 W / mm 2 When the light is converted into electricity, the relative light conversion efficiency of the composite fluorescent ceramic is 99%-99.8% of the initial efficiency, the obtained white light color temperature is 3500-5500 K, and the color rendering index is 80-95.

6. A method for preparing a complex fluorescent ceramic material according to claim 1, characterized in that: The specific steps are as follows: Step 1: Weighing CaCO3, MnCO3 raw material powders and solvent in the CaO:Mn phase according to the mass ratio and stoichiometric ratio, obtaining a slurry by planetary ball milling and drying; sieving the dried powder and then calcining it to obtain CaO:Mn powder; Step 2: Weigh according to the stoichiometric ratio (Re 1-y Ce y )3Al5O 12 The Al2O3, Re2O3, CeO2 raw material powders and the CaO:Mn powders in step 1 are added with a sintering aid and alcohol as a solvent; the powder raw materials are subjected to planetary ball milling; Step 3: The raw material powder of step 2 is subjected to isometric biaxial pressing at a pressure of 2-5 MPa, followed by cold isostatic pressing at a pressure of 200-300 MPa and a holding time of 200-400 s to obtain a ceramic green body; Step 4: Sinter the green blank obtained in step 3, then anneal without annealing, and finally perform double-sided polishing to obtain Ca 1-x Mn x O-(Re 1-y Ce y )3Al5O 12 Complex phase fluorescent ceramics.

7. The method for preparing the complex fluorescent ceramic according to claim 6, characterized in that: Step one is specifically: weighing the CaCO3, MnCO3 raw material powders and solvent in the CaO:Mn phase according to the mass ratio and the stoichiometric ratio, adding 0.1-0.2 mol% of a sintering aid, and adding alcohol as a solvent, and using a planetary ball milling method to perform ball milling mixing, the ball milling speed is 120-180 r / min, and the ball milling time is 12-24 h; the ball-milled slurry is dried at a drying temperature of 40-60°C for 10-24 h; then the dried raw material powder is crushed and passed through a 100-200 mesh sieve; the obtained powder is calcined in a muffle furnace at a calcination temperature of 900-1100°C.

8. The method for preparing the complex fluorescent ceramic according to claim 6, characterized in that: In step 4, the sintering aid is one of Al2O3, Ga2O3 or GeO2.

9. The method for preparing the complex fluorescent ceramic according to claim 6, characterized in that: In step 4, the sintering method is one of vacuum sintering, hot pressing sintering, and hot isostatic pressing sintering, the sintering temperature is 1500-1700 ° C, and the insulation time is 5-24 h.

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