Complex phase fluorescent ceramic material and preparation method therefor

Abstract

Disclosed are a complex phase fluorescent ceramic and a preparation method therefor. The general chemical formula of the complex phase fluorescent ceramic is Ca1-xMnxO-(Re1-yCey)3Al5O12, 0.04≤x≤0.08, 0<y<0.01, Re3+ being one of Lu3+, Y3+ or Gd3+, and the mass ratio of Ca1-xMnxO to (Re1-yCey)3Al5O12 being 10-25:75-90. First, Ca1-xMnxO powder is prepared by a high-temperature solid-phase method; the obtained powder is mixed with (Re1-yCey)3Al5O12 raw material powder, and Ca1-xMnxO-(Re1-yCey)3Al5O12 multi-phase fluorescent ceramic is produced using a solid-state reaction sintering method. Since CaO:Mn is encapsulated within the (Re1-yCey)3Al5O12 ceramic, the problem of CaO easily absorbing moisture can be effectively avoided. Under excitation from a 440-460 nm blue laser, the complex phase fluorescent ceramic of the present invention simultaneously emits yellow-green Ce3+ fluorescence, with a dominant wavelength of 510-565 nm, and orange Mn2+ fluorescence, with a dominant wavelength of 600-630 nm. The ceramic exhibits thermal conductivity as high as 14-20 Wm-1K-1 at room temperature. When the blue laser pumping density is 50-80 W / mm2, the complex phase fluorescent ceramic exhibits a relative light conversion efficiency of 99%-99.8% of the initial efficiency and a color rendering index of 80-95, achieving enhanced luminescence stability and color quality under high pump power density excitation.

Description

A complex-phase fluorescent ceramic material and a preparation method thereof TECHNICAL FIELD

[0001] The present application belongs to the field of electrodeless luminescent materials, and relates to a fluorescent ceramic material, in particular to a complex-phase ceramic material with high color rendering index and anti-light saturation characteristics and a preparation method thereof. BACKGROUND

[0002] Semiconductor white laser dioxide (LD) lighting is the most potential solid-state lighting technology in the 21st century, which can effectively avoid "efficiency drop", and has the advantages of higher brightness, smaller size, longer life, longer range of illumination, etc. "Blue light + Ce 3+ :Re3Al5O 12 fluorescent conversion material" is still a mature and stable technical solution for white light generation. However, Ce 3+ doped garnet fluorescent ceramic still faces the problem of lack of red light component in the spectrum, resulting in low color rendering index and poor light color quality. At present, co-doping transition metal ions Mn 2+ with electronic configuration [X]3d4s is the most effective means to improve color rendering. Limited by the d-d spin-forbidden transition of Mn 2+ , the luminescence efficiency loss after energy transfer is also very obvious. Undoubtedly, improving the absorption cross section of Mn 2+ itself at 450-450nm is the key to alleviate the efficiency decline.

[0003] Luminescence saturation of fluorescent ceramic is another important indicator of high-power white light LD lighting, mainly including thermal-induced luminescence saturation and light-induced luminescence 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 light-induced luminescence saturation. Xie and his research team pointed out that the fluorescence lifetime is a key factor affecting the rate of light-induced quenching. Since the luminescence of Mn 2+ belongs to 4 T1→ 6 A1 radiation transition, it belongs to parity and spin double forbidden transition, so its fluorescence lifetime is usually in the order of milliseconds, which makes the material easy to reach light saturation when the light excitation density is large (Acta Mater., 209 (2021) 116813). Setler et al. pointed out that Ca5(PO4)3Cl:Eu 2+ , Mn 2+ fluorescent powder will produce excited-state Mn 2+ interaction under high-energy density near-ultraviolet LED excitation, followed by energy up-conversion and finally non-radiative relaxation process (Appl. Phys. Lett., 92 (2008) 081104). Another key to realizing high-power laser fluorescent white light is how to overcome the Mn2+ photoluminescence quenching. The above bottleneck limits the application of high-quality fluorescent ceramics in high-power density laser lighting.

[0004] SUMMARY

[0005] One of the purposes of the present application is to provide a kind of complex fluorescent ceramic with high thermal conductivity, high color rendering and anti-light saturation characteristics, by introducing the second phase CaO:Mn into garnet matrix, while supplementing the red component in the spectrum, avoiding the easy moisture absorption characteristics of the second phase, and improving the thermal conductivity of the ceramic, anti-light saturation characteristics, so that it can better meet the special scene application under high-power excitation, such as underwater lighting, seabed detection and other fields.

[0006] The second purpose of the present application is to provide a kind of complex fluorescent ceramic with high thermal conductivity, high color rendering and anti-light saturation characteristics.

[0007] To achieve the above purpose, the technical scheme adopted by the present application is as follows: its chemical formula is Ca 1-x Mn x O-(Re 1-y Ce y )3Al5O 12 , wherein 0.04≤x≤0.08, 0<y<0.01, Re 3+ is one of Lu 3+ , Y 3+ or Gd 3+ , the mass ratio of Ca 1-x Mn x O and (Re 1-y Ce y )3Al5O 12 is 10-25:75-90.

[0008] In the present application, the complex fluorescent ceramic emits Ce 3+ yellow-green fluorescence with main wavelength of 510-565nm and Mn 2+ orange fluorescence with main wavelength of 600-630nm under 440-460nm blue laser excitation; its thermal conductivity at room temperature can reach 16-20Wm -1 K -1 ; when the blue laser pump density is 50-80W / mm 2 , the relative light conversion efficiency of the complex fluorescent ceramic is 99%-99.8% of the initial efficiency, and the white light color temperature obtained is 3500-5500K, and the color rendering index is 80-95.

[0009] The present application also provides a preparation method of the above-mentioned complex fluorescent ceramic, and the specific steps are as follows:

[0010] Step one: according to the mass ratio and stoichiometric ratio, CaCO3, MnCO3 raw material powder in Mn phase is weighed, 0.1-0.2 mol% sintering aid is added, and alcohol is added as a solvent, and the method of planetary ball milling is used for ball milling mixing, the ball milling speed is 120-180 r / min, and the ball milling time is 12-24 h; the slurry after ball milling is dried, the drying temperature is 40-60 DEG C, and the time is 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, and the calcination temperature is 900-1100 DEG C;

[0011] Step two: according to the stoichiometric ratio, (Re 1-y Ce y )3Al5O 12 , Y2O3, CeO2 raw material powder and CaO:Mn powder in step one are weighed, tetraethyl orthosilicate (TEOS) sintering aid is added, and alcohol is added as a solvent; the powder raw material is placed in a ball mill tank, planetary ball milling is carried out, and grinding balls are added for ball milling mixing, the ball milling speed is 200-250 r / min, and the ball milling time is 12-24 h;

[0012] Step three: the raw material powder of step two is isometric bidirectional pressure formed, the pressure is 2-5 MPa, and then cold isostatic pressing is carried out, the pressure is 200-300 MPa, and the pressure holding time is 200-400 s, so that the ceramic body is obtained.

[0013] Step four: the body obtained in step three is sintered, then annealed, and finally polished on both sides, so that the Ca 1-x Mn x O-(Re 1-y Ce y )3Al5O 12 complex phase fluorescent ceramic is obtained.

[0014] As an improvement, in step one, the sintering aid is one of Al2O3, Ga2O3 or GeO2.

[0015] As an improvement, in step four, the sintering method is one of vacuum sintering, hot pressing sintering, and hot isostatic pressing sintering, the sintering temperature is 1500-1700 DEG C, and the holding time is 5-24 h.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] 1. Since the thermal conductivity of CaO ceramic is higher than that of garnet, the thermal conductivity of the complex phase fluorescent ceramic material at room temperature can reach 14-20 Wm -1 K -1The relative light conversion efficiency of the composite fluorescent ceramic is 99-99.8% of the initial efficiency, and the white light color temperature is 3500-5500K, and the color rendering index is 80-95.

[0018] 2. Compared with Ce 3+ and Mn 2+ co-doped garnet matrix scheme, the application designs Mn 2+ into the CaO matrix and occupies the octahedral site, and forms Mn 2+ -Mn 2+ dimer, which can break the spin-forbidden transition of Mn 2+ , improve the absorption cross section and anti-light saturation characteristics of Mn 2+ , and when the blue light laser pumping density is 50-80W / mm 2 , the relative light conversion efficiency of the composite fluorescent ceramic is 99-99.8% of the initial efficiency, and the white light color temperature is 3500-5500K, and the color rendering index is 80-95.

[0019] 3. Since CaO:Mn is wrapped inside the garnet ceramic, the problem of CaO being easily hygroscopic can be effectively avoided, and the use stability in underwater lighting, seabed detection and other fields is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of the structure of the composite fluorescent ceramic in the application;

[0021] Figure 2 is a crystal structure of CaO:Mn in the composite ceramic of the application and a Mn 2+ energy level transition diagram. DETAILED DESCRIPTION

[0022] The application will be further described in detail below in combination with the drawings and specific examples.

[0023] In order to prepare 60g of target product, the raw material powders are weighed according to the ingredient table shown in Table 1.

[0024] Table 1: Example ingredient table

[0025] Example 1

[0026] Step one: according to the mass ratio and chemical ratio shown in Table 1, 1# CaCO3, MnCO3 raw material powder in Mn phase is weighed, 0.1 mol% Al2O3 sintering aid is added, and alcohol is added as a solvent, and a planetary ball mill method is used for ball milling mixing, the ball milling speed is 120 r / min, and the ball milling time is 12 h; the slurry after ball milling is dried, the drying temperature is 40℃, and the time is 10 h. Then the dried raw material powder is crushed and passed through a 100 mesh sieve; the obtained powder is calcined in a muffle furnace, and the calcination temperature is 900℃;

[0027] Step two: according to the stoichiometric ratio, Ce:Re3Al5O 12 Al2O3, Lu2O3, CeO2 raw powder and CaO:Mn powder in step one are weighed, tetraethyl orthosilicate (TEOS) sintering aid is added, and alcohol is added as a solvent; the powder raw material is placed in a ball mill tank, and planetary ball milling is carried out while adding grinding balls for ball milling mixing, the ball milling speed is 200 r / min, and the ball milling time is 12 h;

[0028] Step three: the raw material powder of step two is isometrically bidirectionally pressed, the pressure is 2 MPa, and then cold isostatic pressing is carried out, the pressure is 200 MPa, and the pressure holding time is 200 s, to obtain a ceramic body.

[0029] Step four: the body obtained in step three is vacuum sintered at 1500℃ for 5 h, without annealing, and finally double-sided polishing treatment is carried out, to obtain a 10% Ca 0.96 Mn 0.04 O-90% (Lu 0.998 Ce 0.002 )3Al5O 12 complex phase fluorescent ceramic.

[0030] As shown in Figure 1, in the complex phase fluorescent ceramic prepared in this embodiment, CaO:Mn is wrapped inside the garnet ceramic, which can effectively avoid the problem of CaO easy to absorb moisture. The thermal conductivity of the prepared complex phase fluorescent ceramic is 16.0 W / m·K at room temperature, which is tested by a flash method heat conduction instrument. As shown in Figure 2, since Mn 2+ enters the CaO matrix and occupies adjacent octahedral sites, forming Mn 2+ -Mn 2+ dimers, thereby breaking the spin-forbidden transition of Mn 2+ , improving the absorption cross section and anti-light saturation properties of Mn 2+ , and based on a "reflective" laser illumination device, when the blue light laser pump density at 445 nm is 50 W / mm 2The relative light conversion efficiency of the multiphase fluorescent ceramic is 99.8% of the initial efficiency, the white light color temperature obtained is 3500K, and the color rendering index is 80.

[0031] Example 2

[0032] Step one: according to the mass ratio and chemical ratio shown in Table 1 2#, CaCO3 and MnCO3 raw material powders in CaO:Mn phase are weighed, 0.2 mol% of Al2O3 sintering aid is added, and alcohol is added as a solvent, and a planetary ball mill is used for ball milling mixing, the ball milling speed is 155 r / min, and the ball milling time is 12 h; the slurry after ball milling is dried, the drying temperature is 45℃, and the drying time is 12 h. Then the dried raw material powder is crushed and passed through a 100 mesh sieve; the obtained powder is calcined in a muffle furnace, and the calcination temperature is 1000℃;

[0033] Step two: according to the stoichiometric ratio, Ce:Re3Al5O 12 , Al2O3, Lu2O3, CeO2 raw material powders and CaO:Mn powder in step one are weighed, tetraethyl orthosilicate (TEOS) sintering aid is added, and alcohol is added as a solvent; the powder raw materials are placed in a ball mill tank, planetary ball milling is carried out while adding grinding balls for ball milling mixing, the ball milling speed is 220 r / min, and the ball milling time is 15 h;

[0034] Step three: the raw material powder of step two is isometrically bidirectionally pressed, the pressure is 3 MPa, and then cold isostatic pressing is carried out, the pressure is 220 MPa, and the pressure holding time is 220 s, to obtain a ceramic green body.

[0035] Step four: the green body obtained in step three is vacuum sintered at 1600℃ for 10 h, without annealing, and finally double-sided polishing treatment is carried out, to obtain a 12% Ca 0.95 Mn 0.05 O-88% (Lu 0.996 Ce 0.004 )3Al5O 12 multiphase fluorescent ceramic.

[0036] The thermal conductivity of the multiphase fluorescent ceramic prepared in this example is 17.1 W / m·K. When the blue light laser pumping density is 58 W / mm 2 , the relative light conversion efficiency of the multiphase fluorescent ceramic is 99.6% of the initial efficiency, the white light color temperature obtained is 4323K, and the color rendering index is 84.

[0037] Example 3

[0038] Step one: according to the mass ratio and the chemical ratio shown in Table 1 3#, CaCO3 and MnCO3 raw material powders in CaO:Mn phase are weighed, 0.15 mol% of Ga2O3 sintering aid is added, and alcohol is added as a solvent, planetary ball milling is used for ball milling mixing, the ball milling speed is 160 r / min, and the ball milling time is 18 h; the slurry after ball milling is dried, the drying temperature is 50℃, and the drying time is 15 h. Then the dried raw material powder is crushed and passed through a 150 mesh sieve; the obtained powder is calcined in a muffle furnace, and the calcination temperature is 1050℃;

[0039] Step two: according to the stoichiometric ratio, Ce:Re3Al5O 12 , Al2O3, Y2O3, and CeO2 raw material powders and CaO:Mn powders in step one are weighed, tetraethyl orthosilicate (TEOS) sintering aid is added, and alcohol is added as a solvent; the powder raw materials are placed in a ball mill tank, planetary ball milling is carried out while adding grinding balls for ball milling mixing, the ball milling speed is 230 r / min, and the ball milling time is 18 h;

[0040] Step three: the raw material powder of step two is subjected to isometric bidirectional pressure forming, the pressure is 4 MPa, and then cold isostatic pressing forming is carried out, the pressure is 250 MPa, and the pressure holding time is 240 s, to obtain a ceramic green body.

[0041] Step four: the green body obtained in step three is subjected to hot-pressing sintering at 1500℃, and the holding time is 5 h, then annealing is not required, and finally double-sided polishing treatment is carried out, to obtain a 17% Ca 0.96 Mn 0.04 O-83% (Lu 0.995 Ce 0.005 )3Al5O 12 phosphor ceramic.

[0042] The thermal conductivity of the phosphor ceramic prepared in this example is 18.2 W / m·K. When the blue light laser pump density at 450 nm is 63 W / mm 2 , the relative light conversion efficiency of the phosphor ceramic is 99.4% of the initial efficiency, the obtained white light color temperature is 4945 K, and the color rendering index is 88.

[0043] Example 4

[0044] Step one: according to the mass ratio and the chemical ratio shown in Table 1 4#, CaCO3 and MnCO3 raw material powders in CaO:Mn phase are weighed, 0.2 mol% of Ga2O3 sintering aid is added, and alcohol is added as a solvent, planetary ball milling is used for ball milling mixing, the ball milling speed is 170 r / min, and the ball milling time is 20 h; the slurry after ball milling is dried, the drying temperature is 50℃, and the drying time is 20 h. Then the dried raw material powder is crushed and passed through a 200 mesh sieve; the obtained powder is calcined in a muffle furnace, and the calcination temperature is 1080℃;

[0045] Step two: according to the stoichiometric ratio, Ce:Re3Al5O 12 , Al2O3, Y2O3, and CeO2 raw material powders and the CaO:Mn powder in step one are weighed, tetraethyl orthosilicate (TEOS) sintering aid is added, and alcohol is added as a solvent; the powder raw materials are placed in a ball mill tank, planetary ball milling is carried out while adding grinding balls for ball milling mixing, the ball milling speed is 240 r / min, and the ball milling time is 22 h;

[0046] Step three: the raw material powder in step two is subjected to isometric two-way press forming, the pressure is 5 MPa, and then cold isostatic pressing forming is carried out, the pressure is 300 MPa, and the pressure holding time is 300 s, to obtain a ceramic green body.

[0047] Step four: the green body obtained in step three is subjected to hot isostatic pressing sintering at 1700℃, and the holding time is 3 h, then annealing is not required, and finally double-sided polishing treatment is carried out, to obtain a 20% Ca 0.93 Mn 0.07 O-80% (Lu 0.994 Ce 0.006 )3Al5O 12 phosphor ceramic.

[0048] The thermal conductivity of the phosphor ceramic prepared in this example is 18.8 W / m·K. When the blue light laser pumping density is 74 W / mm 2 , the relative light conversion efficiency of the phosphor ceramic is 99.2% of the initial efficiency, the obtained white light color temperature is 5230K, and the color rendering index is 91.

[0049] Example 5

[0050] Step one: according to the mass ratio and the chemical ratio shown in Table 1 5#, CaCO3, MnCO3 raw material powder in Mn phase is weighed, 0.2 mol% of GeO2 sintering aid is added, and alcohol is added as a solvent, planetary ball milling method is used for ball milling mixing, the ball milling speed is 170 r / min, the ball milling time is 20 h; the slurry after ball milling is dried, the drying temperature is 60℃, the time is 24 h. Then the dried raw material powder is crushed and passed through a 200 mesh sieve; the obtained powder is calcined in a muffle furnace, the calcination temperature is 1100℃;

[0051] Step two: according to the stoichiometric ratio, Ce:Re3Al5O 12 , Gd2O3, CeO2 raw material powder and CaO:Mn powder in step one are weighed, tetraethyl orthosilicate (TEOS) sintering aid is added, and alcohol is added as a solvent; the powder raw material is placed in a ball mill tank, planetary ball milling is carried out while adding grinding balls for ball milling mixing, the ball milling speed is 250 r / min, the ball milling time is 24 h;

[0052] Step three: the raw material powder of step two is isometric bidirectional pressure forming, the pressure is 5 MPa, then cold isostatic pressing forming is carried out, the pressure is 300 MPa, the pressure holding time is 400 s, and the ceramic green body is obtained.

[0053] Step four: the green body obtained in step three is vacuum sintered at 1700℃ for 24 h, without annealing, and finally double-sided polishing treatment is carried out, and the 25% Ca 0.92 Mn 0.08 O-75% (Lu 0.991 Ce 0.009 )3Al5O 12 complex phase fluorescent ceramic is obtained.

[0054] The thermal conductivity of the complex phase fluorescent ceramic prepared in this example is 20.0 W / m·K. When the blue light laser pumping density is 80 W / mm 2 , the relative light conversion efficiency of the complex phase fluorescent ceramic is 99% of the initial efficiency, the white light color temperature is 5500K, and the color rendering index is 95.

Claims

1. A method for preparing a multiphase 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+ For 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 multiphase 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, when excited by a 440-460nm blue laser, simultaneously emits Ce with a dominant wavelength of 510-565nm. 3+ Yellow-green fluorescence and Mn with a dominant wavelength of 600-630nm 2+ Orange fluorescence.

4. The multiphase fluorescent ceramic material according to claim 1, characterized in that, Thermal conductivity at room temperature can reach 14-20 W / m -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 At that time, the relative light conversion efficiency of the multiphase fluorescent ceramic was 99%-99.8% of the initial efficiency, and the resulting white light color temperature was 3500-5500K with a color rendering index of 80-95.

6. A multiphase fluorescent ceramic material as described in claim 1, characterized in that, The specific steps are as follows: Step 1: Weigh the CaCO3, MnCO3 raw material powder and solvent in the CaO:Mn phase according to the mass ratio and stoichiometric ratio, obtain a slurry by planetary ball milling and dry it; sieve the dried powder and then calcine it to obtain CaO:Mn powder. Step 2: Weigh according to the stoichiometric ratio (Re) 1-y Ce y )3Al5O 12 The raw material powders of Al2O3, Re2O3, and CeO2 and the CaO:Mn powder from step one are mixed with sintering aids and alcohol as a solvent; the raw materials are then subjected to planetary ball milling. Step 3: The raw material powder from Step 2 is subjected to equiaxed biaxial pressure molding 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 the ceramic green body. Step 4: Sinter the green blank obtained in Step 3, then anneal without further annealing, and finally polish it on both sides to obtain Ca. 1-x Mn x O-(Re 1-y Ce y )3Al5O 12 Multiphase fluorescent ceramics.

7. The method for preparing multiphase fluorescent ceramics according to claim 6, characterized in that, Step one is as follows: Weigh the CaCO3 and MnCO3 raw material powders and solvents in the CaO:Mn phase according to the mass ratio and stoichiometric ratio, add 0.1-0.2 mol% of sintering aid, and add alcohol as a solvent. Mix the materials by ball milling using a planetary ball mill at a speed of 120-180 r / min for 12-24 h. Dry the ball-milled slurry at a temperature of 40-60℃ for 10-24 h. Then, pulverize the dried raw material powder and pass it through a 100-200 mesh sieve. Calcine the obtained powder in a muffle furnace at a temperature of 900-1100℃.

8. The method for preparing multiphase fluorescent ceramics according to claim 6, characterized in that, In step four, the sintering aid is one of Al2O3, Ga2O3, or GeO2.

9. The method for preparing multiphase fluorescent ceramics according to claim 6, characterized in that, In step four, the sintering method is one of vacuum sintering, hot pressing sintering, or hot isostatic pressing sintering, with a sintering temperature of 1500-1700℃ and a holding time of 5-24 hours.

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