CN114988862B - High-color-rendering-index fluorescent ceramic for laser illumination and preparation method thereof - Google Patents

Abstract

The invention discloses a high-color-rendering-index fluorescent ceramic for laser illumination and a preparation method thereof, wherein the fluorescent ceramic has the chemical formula: (Y) _1‑x Ce _x ) ₂ Mg(Sc _0.5 Al _0.5‑y Mn _y ) ₁ Al ₂ SiO ₁₂ Wherein x is Ce ³⁺ Doping Y ³⁺ Mole percent of bits, y is Mn ²⁺ Doping Al ³⁺ The mole percentage of the position is 0.002.ltoreq.x.ltoreq. 0.02,0.001.ltoreq.y.ltoreq.0.015, and the solid phase reaction sintering is adopted to prepare the catalyst. Under 460nm wavelength excitation, the fluorescent ceramic provided by the invention has an emission spectrum main peak between 566 and 585nm and a half-width between 105 and 120 nm; under the excitation of blue light LD (1-5W), warm white light emission is realized, the color temperature is 3800-4250K, and the color rendering index is 80-85; when the ambient temperature is 150 ℃, the luminous intensity of the fluorescent ceramic is kept at 80-90%, the optical performance is excellent, and the fluorescent ceramic is simple to prepare and can be used in the field of laser illumination.

Description

High color rendering index fluorescent ceramics for laser lighting and preparation method thereof

technical field

The invention relates to the technical field of fluorescent ceramics, in particular to a high color rendering index fluorescent ceramic for laser lighting and a preparation method thereof.

Background technique

As the fourth-generation lighting source, white light emitting diodes (WLEDs) have been developed and applied for a long time in the field of solid-state lighting and display. Compared with LEDs, laser lighting technology based on laser diodes (Laser diode, LD) can still maintain high luminous efficiency in the field of high-power lighting, and has higher brightness, smaller size, longer life, searchlight Significant advantages such as longer distances. Taking a single chip as an example, the brightness of blue LD is up to 1000 times that of LED, but the energy consumption is only 2/3 of that of LED. LD solid-state lighting technology has become a key development direction in the field of lighting.

At present, the mainstream implementation scheme of white light LD light source is still blue LD excitation garnet Y ₃ Al ₅ O ₁₂ :Ce(YAG:Ce) yellow fluorescent material. Compared with fluorescent powder, fluorescent ceramics have good thermal, mechanical, and physical and chemical stability, but the emission spectrum of YAG:Ce is mainly covered with yellow-green light, lacking sufficient red light components, so white LD light sources also face poor color rendering performance. (CRI～60), high color temperature (>6000K), low light and color quality.

At present, a large number of literatures have reported the modification of Ce:YAG fluorescent ceramics, in order to realize the regulation of the luminescent behavior of Ce:YAG fluorescent ceramics. The literature (Thermostability and reliability properties studies of transparent Ce: GdYAG ceramic by Gd substitution for whiteLEDs. Optical Materials, 2019, 94, 172-181) reported that the emission peak position of Ce ³⁺ ions can be red-shifted by co-doping Gd ³⁺ , However, the range of movement is very limited, and the effect of color temperature improvement is not obvious. CN110218085A discloses that through the design of composite structure fluorescent ceramics, red, green and yellow three-color coupled light emission is realized, and warm white light is obtained, but its thermal stability also gradually decreases, and the manufacturing cost is higher and the process is more complicated. CN108264899A discloses a multi-element doped transparent ceramic used for LED lighting instead of fluorescent powder, which emits white light after being excited by a blue light chip. However, the afterglow time of this ceramic is long, which greatly limits its luminous efficiency, making the device serious loss of light.

Contents of the invention

One of the objectives of the present invention is to provide a fluorescent ceramic with high color rendering index for laser lighting, which can realize the emission of warm white light, white light or light red light.

The second object of the present invention is to provide a preparation method of the high color rendering index fluorescent ceramics for laser lighting, which is easy to realize industrial production.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

In the first aspect, the present invention provides a fluorescent ceramic with a high color rendering index for laser lighting. The chemical formula of the fluorescent ceramic is:

(Y _1-x Ce _x ) ₂ Mg(Sc _0.5 Al _0.5-y Mn _y ) ₁ Al ₂ SiO ₁₂

Where x is the mole percentage of Ce ³⁺ doped Y ³⁺ sites, y is the mole percentage of Mn ²⁺ doped Al ³⁺ sites, 0.002≤x≤0.02, 0.001≤y≤0.015.

Under the excitation of 460nm wavelength, the fluorescent ceramic provided by the invention has the main peak of emission spectrum between 566nm and 585nm, and the half maximum width between 105nm and 120nm. Under the excitation of blue light LD (1-5W), the emission of warm white light is realized, the color temperature is 3800-4250K, and the color rendering index is between 80-85. When the ambient temperature is 150°C, the luminous intensity of the fluorescent ceramics is maintained at 80%-90%.

In the second aspect, the present invention also provides a method for preparing the above-mentioned high color rendering index fluorescent ceramics for laser lighting, which is sintered by a solid-state reaction method, and specifically includes the following steps:

(1) According to the chemical formula (Y _{1-x Cex} ) ₂ Mg(Sc _0.5 Al _0.5-y Mn _y ) ₁ Al ₂ SiO ₁₂ , 0.002≤x≤0.02, 0.001≤y≤0.015, the stoichiometric ratio of each element in Respectively weigh yttrium oxide, aluminum oxide, cerium oxide, magnesium oxide, silicon dioxide, scandium oxide, and manganese carbonate as raw material powders; mix the raw material powders and ball milling media in a certain proportion and ball mill to obtain a mixed slurry;

(2) the mixed slurry obtained in step (1) is placed in a drying box to dry, and then the dried mixed powder is sieved;

(3) putting the powder sieved in step (2) into an abrasive tool for dry pressing and forming, and then performing cold isostatic pressing to obtain a green body with a relative density of 50% to 55%;

(4) Sintering the biscuit obtained in step (3) in a vacuum furnace at a sintering temperature of 1550-1650°C, a holding time of 1-24 hours, and a sintering vacuum degree of not less than 10 ^-3 Pa to obtain fluorescent ceramics;

(5) Annealing the fluorescent ceramics obtained in the step (4) in air at an annealing temperature of 1300-1450° C. and a holding time of 8-24 hours to obtain fluorescent ceramics with a relative density of 99.5%-99.9%.

Preferably, in step (1), the ball milling speed is 180-200r/min, and the ball milling time is 15-20h.

Preferably, in step (1), the ball milling medium is absolute ethanol, and the mass volume ratio of the raw material powder to the ball milling medium is 1 g: (1.5-3.5) mL.

Preferably, in step (2), the drying time is 20-30 hours, and the drying temperature is 80-90°C.

Preferably, in step (2), the mesh size of the sieve is 50-200 mesh, and the number of sieves is 1-3 times.

Preferably, in step (3), the cold isostatic holding pressure is 150-200Mpa, and the holding time is 200-400s.

Preferably, in step (4), the temperature rise rate in the vacuum sintering stage is 1-10°C/min, and the temperature drop rate after sintering is 1-10°C/min.

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

1. The present invention obtains pure garnet-phase fluorescent ceramics by controlling the stoichiometric ratio and solid-state reaction method. Under the excitation of 460nm wavelength, the main peak of the emission spectrum of the fluorescent ceramics is between 566-585nm, and the half-maximum width is 105-120nm Under the excitation of blue light LD (1~5W), it can emit warm white light, the color temperature is 3800~4250K, and the color rendering index is between 80~85.

2. The magnesium oxide used in the present invention is not only the raw material of the fluorescent material, but also plays the role of a cosolvent, avoiding the introduction of impurity ions caused by adding a cosolvent, and also omitting the impurity removal step;

3. The present invention refers to the ion radius matching principle and the control principle of the crystal field, and uses the Mg ²⁺ -Si ⁴⁺ ion pair to non-equivalently replace the Al ³⁺ -Al ³⁺ ion pair, which increases the lattice distortion of the ion and makes the Ce The energy level splitting degree of 5d ₁ and 5d ₁ of ³⁺ ions increases, resulting in the decrease of 5d ₁ energy level of Ce ³⁺ , which makes the energy of electron transition to the ground state of Ce ³⁺ ions relatively reduced, resulting in Ce ³⁺ emission The red shift of the light, and the emission peak is effectively broadened. The prepared fluorescent ceramics have excellent optical indicators and are applied to laser lighting.

4. The present invention introduces transition metal Mn ²⁺ ions, successfully replaces octahedral Al ³⁺ ions to emit red light at 580nm, increases red light emission, and significantly improves the color rendering index of fluorescent materials.

5. The Sc ³⁺ introduced by the present invention, as the ion with the smallest ionic radius and the largest electronegativity among the transition ions, successfully occupies the octahedral Al ³⁺ position, avoiding excessive lattice distortion caused by Mg-Si co-substitution , making it possible to incorporate Mn ²⁺ at a high concentration; at the same time, the introduction of Sc ³⁺ relaxes the covalent bond tension of the nearest neighbor bond (Ce-O bond), increasing the dodecahedral concentration of Ce ^{3 +} ions. The local symmetry of the ceramic structure is conducive to enhancing the rigidity of the ceramic structure and significantly improving the thermal stability of the fluorescent ceramics. At 150°C, the luminous intensity attenuates by 10% to 20%, and the thermal stability is good.

Description of drawings

Fig. 1 is the XRD figure of the fluorescent ceramics that the embodiment of the present invention 1-3 makes;

Fig. 2 is the emission spectrogram of the fluorescent ceramics prepared by the embodiment of the present invention 1-3 under the excitation of 460nm wavelength;

Fig. 3 is the emission spectrum Gaussian peak diagram of the fluorescent ceramic sample that the embodiment 1 of the present invention makes;

4 is a surface SEM image and an EDS spectrum of a fluorescent ceramic sample prepared in Example 1 of the present invention;

Fig. 5 is a fluorescence temperature-varying spectrum of a fluorescent ceramic sample prepared in Example 1 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.

The raw material powders used in the following examples are commercially available, and the purity is greater than 99.9%.

Example 1: Preparation of fluorescent ceramics with chemical formula (Y _0.998 Ce _0.002 ) ₃ Mg(Sc _0.5 Al _0.498 Mn _0.002 ) ₁ Al ₂ SiO ₁₂ .

(1) _{Set the} target product _{mass to 60.011g ,} weigh _yttrium oxide _{( 33.725g} ), aluminum oxide (12.705g), cerium oxide (0.103g), magnesium oxide (4.021g), silicon dioxide (5.994g), scandium oxide (3.440g), manganese carbonate (0.023g) as raw material powder. The raw material powder was mixed with 100 mL of absolute ethanol, and ball milled in a ball mill tank at a speed of 180 r/min and a milling time of 15 hours.

(2) Put the mixed slurry after ball milling in step (1) into an air-blast drying oven at 80°C for 20 hours, and pass the dried mixed powder through a 50-mesh sieve, and sieve twice.

(3) putting the powder calcined in step (2) into a mold for dry pressing and then performing cold isostatic pressing, and the relative density of the green body after forming is 50%.

(4) Put the ceramic green body obtained in step (4) into a vacuum furnace for sintering, the sintering temperature is 1650°C, the holding time is 1h, the heating rate is 1°C/min, and the cooling rate after sintering is 1°C/min; The relative density of ceramics is 99.9%.

(5) Polishing the sintered fluorescent ceramics on both sides until the thickness of the ceramics is 1.0 mm to obtain fluorescent ceramics.

The XRD test of the (Y _0.998 Ce _0.002 ) ₃ Mg(Sc _0.5 Al _0.498 Mn _0.002 ) ₁ Al ₂ SiO ₁₂ fluorescent ceramic obtained in this example shows that the prepared material is a pure garnet phase, as shown in FIG. 1 .

The main peak of the emission spectrum of the (Y _0.998 Ce _0.002 ) ₃ Mg(Sc _0.5 Al _0.498 Mn _0.002 ) ₁ Al ₂ SiO ₁₂ fluorescent ceramics obtained in this example is 566 nm and the full width at half maximum is 105 nm when excited at a wavelength of 460 nm, as shown in Figure 2 It can be seen that the emission spectrum is divided into peaks, the emission main peak of the fluorescent ceramics at 566nm is composed of the emission of Ce ³⁺ at 452nm and the emission of Mn ²⁺ at 580nm, as shown in Figure 3; The boundary is clear, and the EDS spectrum shows that the element ions are successfully incorporated into the garnet structure, as shown in Figure 4; under the excitation of high-power blue light LD (1W), the ceramic emits from warm white light, with a color temperature of 3800K and a color rendering index of 82. When the ambient temperature is 150° C., the luminous intensity of the fluorescent ceramic remains at 85%, as shown in FIG. 5 .

Example 2: Preparation of fluorescent ceramics with chemical formula (Y _0.99 Ce _0.01 ) ₃ Mg(Sc _0.5 Al _0.492 Mn _0.008 ) ₁ Al ₂ SiO ₁₂ .

( ₁ ) _{Set the} target _{product mass to 60.053g , weigh} yttrium oxide (33.377g ), alumina (12.645g), cerium oxide (0.514g), magnesium oxide (4.012g), silicon dioxide (5.981g), scandium oxide (3.432g), manganese carbonate (0.092g) as raw material powder. The raw material powder was mixed with 150 mL of absolute ethanol, and ball milled in a ball mill tank at a speed of 190 r/min and a milling time of 15 hours.

(2) Put the mixed slurry after ball milling in step (1) into a blast drying oven at 90°C for 20 hours, and pass the dried mixed powder through a 100-mesh sieve, and sieve twice.

(3) putting the powder calcined in step (2) into a mold for dry pressing and then performing cold isostatic pressing, and the relative density of the green body after forming is 50%.

(4) Put the ceramic green body obtained in step (4) into a vacuum furnace for sintering, the sintering temperature is 1600°C, the holding time is 8h, the heating rate is 5°C/min, and the cooling rate after sintering is 5°C/min; The relative density of ceramics is 99.8%.

(5) Polishing the sintered fluorescent ceramics on both sides until the thickness of the ceramics is 1.0 mm to obtain fluorescent ceramics.

The XRD test of the (Y _0.99 Ce _0.01 ) ₃ Mg(Sc _0.5 Al _0.492 Mn _0.008 ) ₁ Al ₂ SiO ₁₂ fluorescent ceramics obtained in this example shows that the prepared material is a pure garnet phase, as shown in FIG. 1 .

The main peak of the emission spectrum of the (Y _0.99 Ce _0.01 ) ₃ Mg(Sc _0.5 Al _0.492 Mn _0.008 ) ₁ Al ₂ SiO ₁₂ fluorescent ceramics obtained in this example is 578 nm and the full width at half maximum is 110 nm when excited at a wavelength of 460 nm, as shown in Figure 2 . Under the excitation of high-power blue light LD (5W), the pottery can realize white light emission with a color temperature of 4060K and a color rendering index of 85. When the ambient temperature is 150° C., the luminous intensity of the fluorescent ceramic remains at 83%.

Example 3: Preparation of fluorescent ceramics with chemical formula (Y _0.98 Ce _0.02 ) ₃ Mg(Sc _0.5 Al _0.485 Mn _0.015 ) ₁ Al ₂ SiO ₁₂ .

( ₁ ) Set _{the target product} mass _{to 60.101g , weigh} yttrium oxide ( _32.946g ), alumina (12.574g), cerium oxide (1.025g), magnesium oxide (4.000g), silicon dioxide (5.963g), scandium oxide (3.422g), manganese carbonate (0.171g) as raw material powder. The raw material powder was mixed with 200mL of absolute ethanol, and ball milled in a ball mill jar with a ball milling speed of 200r/min and a ball milling time of 20h.

(2) Dry the mixed slurry after ball milling in step (1) in a blast drying oven at 90°C for 30 hours, and pass the dried mixed powder through a 200-mesh sieve, and sieve once.

(3) Put the calcined powder in the step (2) into an abrasive tool for dry pressing and then carry out cold isostatic pressing, and the relative density of the green body after forming is 55%.

(4) Put the ceramic green body obtained in step (4) into a vacuum furnace for sintering, the sintering temperature is 1550°C, the holding time is 24h, the heating rate is 10°C/min, and the cooling rate after sintering is 10°C/min; The relative density of ceramics is 99.5%.

(5) Polishing the sintered fluorescent ceramics on both sides until the thickness of the ceramics is 1.0 mm to obtain fluorescent ceramics.

The XRD test of the (Y _0.98 Ce _0.02 ) ₃ Mg(Sc _0.5 Al _0.485 Mn _0.015 ) ₁ Al ₂ SiO ₁₂ fluorescent ceramic obtained in this example shows that the prepared material is a pure garnet phase, as shown in FIG. 1 .

The main peak of the emission spectrum of the (Y _0.98 Ce _0.02 ) ₃ Mg(Sc _0.5 Al _0.485 Mn _0.015 ) ₁ Al ₂ SiO ₁₂ fluorescent ceramics obtained in this example is 585 nm and the full width at half maximum is 120 nm when excited at a wavelength of 460 nm, as shown in Figure 2 ; Under the excitation of high-power blue light LD (3W), the ceramic can realize light red light emission, the color temperature is 4250K, and the color rendering index is 80. When the ambient temperature is 150° C., the luminous intensity of the fluorescent ceramic remains at 80%.

The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Anyone familiar with the technical field within the technical scope disclosed in the present invention, whoever is within the spirit and principles of the present invention Any modifications, equivalent replacements and improvements made within shall fall within the protection scope of the present invention.

Claims (8)

1. The high-color-rendering-index fluorescent ceramic for laser illumination is characterized by comprising the following chemical formula:

(Y _1-x Ce _x ) ₂ Mg(Sc _0.5 Al _0.5-y Mn _y ) ₁ Al ₂ SiO ₁₂

wherein x is Ce ³⁺ Doping Y ³⁺ Mole percent of bits, y is Mn ²⁺ Doping Al ³⁺ The mole percentage of the position is more than or equal to 0.002 and less than or equal to 0.02,0.001 and less than or equal to 0.015.

2. A method for preparing the fluorescent ceramic with high color rendering index for laser illumination according to claim 1, which is characterized by adopting a solid phase reaction method for sintering, and specifically comprising the following steps:

(1) According to the chemical formula (Y) _1-x Ce _x ) ₂ Mg(Sc _0.5 Al _0.5-y Mn _y ) ₁ Al ₂ SiO ₁₂ The stoichiometric ratio of each element in the powder is more than or equal to 0.002 and less than or equal to 0.02,0.001 and less than or equal to 0.015, and yttrium oxide, aluminum oxide, cerium oxide, magnesium oxide, silicon dioxide, scandium oxide and manganese carbonate are respectively weighed as raw material powder; mixing and ball milling raw material powder and a ball milling medium according to a certain proportion to obtain mixed slurry;

(2) Drying the mixed slurry obtained in the step (1) in a drying oven, and sieving the dried mixed powder;

(3) Putting the powder sieved in the step (2) into a grinding tool for dry press molding, and then performing cold isostatic pressing molding to obtain a biscuit with the relative density of 50-55%;

(4) Sintering the biscuit obtained in the step (3) in a vacuum furnace at 1550-1650 ℃ for 1-24 h, wherein the sintering vacuum degree is not lower than 10 ^-3 Pa, obtaining fluorescent ceramics;

(5) And (3) annealing the fluorescent ceramic obtained in the step (4) in air at 1300-1450 ℃ for 8-24 h to obtain the fluorescent ceramic with the relative density of 99.5-99.9%.

3. The method for preparing high color rendering index fluorescent ceramic for laser illumination according to claim 2, wherein in the step (1), the ball milling rotation speed is 180-200 r/min, and the ball milling time is 15-20 h.

4. The method for preparing the fluorescent ceramic with high color rendering index for laser illumination according to claim 2, wherein in the step (1), the ball milling medium is absolute ethyl alcohol, and the mass volume ratio of the raw material powder to the ball milling medium is 1g: 1.5-3.5 mL.

5. The method for producing a fluorescent ceramic with a high color rendering index for laser illumination according to claim 2, wherein in the step (2), the drying time is 20 to 30 hours and the drying temperature is 80 to 90 ℃.

6. The method for producing a fluorescent ceramic with a high color rendering index for laser illumination according to claim 2, wherein in the step (2), the number of the sieves is 50 to 200 meshes, and the number of the sieves is 1 to 3.

7. The method of producing a fluorescent ceramic with a high color rendering index for laser illumination according to claim 2, wherein in the step (3), the cold isostatic pressing holding pressure is 150 to 200Mpa and the holding time is 200 to 400s.

8. The method for producing a fluorescent ceramic with a high color rendering index for laser illumination according to claim 2, wherein in the step (4), the temperature rising rate in the vacuum sintering stage is 1 to 10 ℃/min, and the temperature lowering rate after the completion of sintering is 1 to 10 ℃/min.

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