A rare earth doped silicate system high crystallinity transparent glass ceramic and a preparation method thereof

Abstract

This invention belongs to the field of microcrystalline glass material technology, specifically disclosing a rare-earth-doped silicate system with high crystallinity and a method for its preparation. This microcrystalline glass is prepared from various raw materials including black talc powder, CaO, AlF3, YF3, rare-earth ions, graphite powder, Si3N4, clarifying agent, and micron-sized seed crystals through a high-temperature melting process and controlled nucleation-crystallization. The raw materials used are abundant, the preparation process is simple, and the resulting high-crystallinity transparent microcrystalline glass can be effectively excited by 420 nm violet light, exhibiting high crystallinity, high transmittance, high luminous efficiency, and excellent resistance to thermal quenching. The main crystalline phase is CaAl2Si2O8 with a small amount of YF3, with a crystallinity ≥70 vol.%, a transmittance ≥80% for a 1 mm sample, an adjustable emission peak value between 480 nm and 520 nm, an internal quantum efficiency ≥80%, and a luminous intensity at 150℃ that is more than 85% of the luminous intensity at room temperature. It can be widely used in white light illumination and screen displays.

Description

Technical Field

[0001] This invention belongs to the field of microcrystalline glass material technology, specifically relating to a rare earth-doped silicate system with high crystallinity and a method for preparing the same. Background Technology

[0002] In recent years, with the popularization of the concept of healthy lighting, traditional lighting sources such as incandescent and fluorescent lamps are gradually being replaced by white light-emitting diodes (W-LEDs). Among them, phosphor-converted LEDs (pc-LEDs) have become the mainstream lighting technology due to their advantages such as high luminous efficiency, adjustable color temperature, long lifespan, and energy saving and environmental protection. However, current technologies based on blue LED chips and YAG:Ce... 3+ Phosphor-encapsulated W-LED devices still have significant drawbacks, such as a low color rendering index (CRI < 80) and a high color temperature (CCT > 4500K), making it difficult to meet the demands of high-quality lighting. To address this, the academic community has proposed a technique using violet-based chips to excite multi-color phosphors, which can achieve full-spectrum white light output through composite spectral synthesis. Significant progress has been made in blue, green, yellow, and red phosphors, but the "cyan gap" in the 480 nm–520 nm wavelength range remains a core bottleneck restricting the generation of high-quality white light. In recent years, Ce... 3+ Eu 2+ and Bi 3+ Various cyan phosphors, such as Ca2LuZr2(AlO4)3:Ce, have been successfully synthesized using ions as luminescent centers. 3+ (Journal of Materials Chemistry C 8 (2020) 1095-1103), Y3Sc2Ga3O 12 :Ce 3+ (Advanced Optical Materials 12 (2024) 2400374), ScCaO(BO3): Ce 3+ (MaterialsToday Chemistry 26 (2022) 101030), (Ba 1-x Sr x )9Lu2Si6O 24 Eu 2+ (Inorganic Chemistry61 (2022) 1805-1815), Rb2KNa(Li3SiO4)4: Eu 2+ (Optical Materials 146 (2023)114529), SrBaGdGaO5: Bi 3+(Journal of Molecular Structure 1295 (2024) 136814) and SrLaGaO4: Bi 3+ (Materials Today Chemistry 23 (2022) 100754), etc. Although these phosphors can achieve ideal emission spectra by adjusting their composition, their insufficient thermal stability severely restricts their practical application in W-LED devices, failing to meet the stringent requirements of purple-driven full-spectrum W-LED lighting. Against this backdrop, microcrystalline glass material systems that combine high thermal stability with tunable optical properties show great application potential.

[0003] As a luminescent matrix material, glass-ceramics possess the core advantage of combining the high transparency of glass with the mechanical strength and chemical stability of ceramics. By controlling the ratio of crystalline to glassy phases, the physicochemical properties of this material can approach those of single-crystal or transparent ceramics. Highly crystalline transparent glass-ceramics, in particular, not only inherit the high-temperature resistance, corrosion resistance, and high insulation properties of transparent ceramics but also offer superior ease of fabrication compared to crystalline materials: enabling large-scale molding while reducing impurity sensitivity. Furthermore, doping glass-ceramics with rare-earth ions can further endow them with specific optical functions (such as fluorescence emission or laser gain). However, the generally low crystallinity of existing glass-ceramics limits the luminescence efficiency of rare-earth-doped systems, becoming a key bottleneck restricting their practical application.

[0004] From the perspective of luminescence mechanism, rare earth ions can be divided into two typical systems: the first type is based on Eu. 3+ As the representative f - f The transition luminescent center is characterized by 4 f n Transitions within the electronic configuration exhibit sharp-line emission spectra due to the shielding effect of the outer electrons; the second type, denoted by Eu... 2+ As the representative f - d The transition system, its light source is 4 f -5 d Electronic configurational transition. Eu 2+ The ions exhibit broad-spectrum emission characteristics (covering the blue to near-infrared band) and significant Stokes shift, but their luminescence lifetime is short due to lattice vibrations. Studies have shown that Eu... 2+While doped glasses can achieve cyan emission (as in patents with application numbers CN202310767105.9, CN200910111233.8, and CN201911295194.1), their emission intensity still needs improvement. Of particular interest is the ability to effectively regulate Eu by controlling the crystallization process of the glass matrix and forming a composite structure containing nanocrystals within the glass-ceramic. 2+ The crystal field environment surrounding the ions. This localized structural optimization can significantly enhance the luminescence efficiency of glass-ceramics, but ordinary glass-ceramics have low crystallinity, making Eu... 2+ The luminescence efficiency of doped glass-ceramics also needs further improvement (e.g., the patent application number CN202311801180.9). Therefore, Eu... 2+ Highly crystalline transparent microcrystalline glass has become an ideal choice for achieving high-performance cyan luminescence. Summary of the Invention

[0005] The purpose of this invention is to provide a rare-earth-doped silicate system with high crystallinity and transparent microcrystalline glass and its preparation method. The raw materials are abundant, inexpensive, simple to process, and easy to industrialize. The main crystalline phase of the obtained high crystallinity and transparent microcrystalline glass is CaAl2Si2O8 and a small amount of YF3. It can be effectively excited by 420 nm violet light and has the characteristics of high crystallinity, high transmittance, adjustable emission peak value between 480 nm and 520 nm, high luminous efficiency, and excellent resistance to thermal quenching.

[0006] This invention provides a rare-earth-doped silicate system with high crystallinity and transparency. The main crystalline phases of this microcrystalline glass are CaAl₂Si₂O₈ and a small amount of YF₃. The crystallinity is ≥ 70 vol.%, the transmittance of a 1 mm sample is ≥ 80%, the emission peak value is tunable between 480 nm and 520 nm, the internal quantum efficiency is ≥ 80%, and the luminescence intensity at 150℃ is ≥ 85% of the luminescence intensity at room temperature. The mass percentage composition of the main raw materials in the base glass is as follows: black talc powder: 45–65 wt.%; CaO: 10–20 wt.%; AlF₃: 15–30 wt.%; YF₃: 5–15 wt.%; 2–15 wt.% of the total mass of graphite powder as the main raw material (black talc powder + CaO + AlF₃ + YF₃); and 2–15 wt.% of the total mass of Si₃N₄ as the main raw material (black talc powder + CaO + AlF₃ + YF₃). The content of external rare earth compounds is 0.1–5 wt.% of the total mass of the main raw materials (black talc powder + CaO + AlF3 + YF3); the content of external clarifying agent is 0.1–2 wt.% of the total mass of the main raw materials (black talc powder + CaO + AlF3 + YF3); and the content of micron-sized seed crystals (CaAl2Si2O8) is 0.01–0.1 wt.% of the total mass of the main raw materials (black talc powder + CaO + AlF3 + YF3).

[0007] As some embodiments of the microcrystalline glass of the present invention, the black talc powder in the raw material has a particle size of 50-150 μm.

[0008] In some embodiments of the microcrystalline glass of the present invention, the externally doped rare earth compound is europium chloride (EuCl2) or europium fluoride (EuF2), that is, the externally doped rare earth ion is Eu. 2+ .

[0009] As some embodiments of the microcrystalline glass of the present invention, the clarifying agent is one or a combination of two of Sb2O3 or NaSbO3.

[0010] As a preferred embodiment of the microcrystalline glass of the present invention, the total content of reducing components (graphite powder, Si3N4) incorporated into the raw materials is ≥ 5 wt.%.

[0011] This invention also provides a method for preparing the above-mentioned rare-earth-doped silicate system with high crystallinity and transparent microcrystalline glass, the specific steps of which are as follows:

[0012] (a) Weigh each raw material precisely according to the predetermined mass percentage, put them into an agate mortar and grind for 0.2 h to 4 h to obtain a uniform mixture;

[0013] (b) The obtained mixture is loaded into a corundum crucible and placed into a graphite crucible in an electromagnetic induction melting furnace. The mixture is heated from room temperature to 1500-1600 °C and held for 0.2-3 h to obtain a uniformly molten glass liquid.

[0014] (c) Quickly remove the molten glass from the melting furnace, pour it onto a mold preheated to 550-650 °C and press it into shape. Then quickly transfer the formed block glass into an annealing furnace at the same temperature and keep it for 5-30 h. After annealing, the annealing furnace is cooled to room temperature to obtain a uniformly molten base glass.

[0015] (d) The obtained base glass is cut into regular blocks and polished. Then the glass is placed in a heating furnace for heat treatment. The base glass is nucleated and crystallized near the glass nucleation temperature and crystallization temperature using the "field-induced dynamic nucleation-gradient modulation crystallization" process and the "heterogeneous lattice epitaxial template crystallization" process.

[0016] (e) After the heat treatment is completed, the heating furnace is cooled to room temperature to obtain a highly crystalline transparent microcrystalline glass based on rare earth doped silicate system.

[0017] As some embodiments of the preparation method of the present invention, mechanical stirring is performed after the powder raw material inside the crucible in the electromagnetic induction melting furnace in step (b) becomes glass liquid, and the stirring rate is 5 to 60 r / min.

[0018] As some embodiments of the preparation method of the present invention, the heating rate of the electromagnetic induction melting furnace in step (b) is 10-100 ℃ / min; the heating and cooling rates of the annealing furnace and the heating furnace in steps (c), (d) and (e) are all 5-30 ℃ / min.

[0019] As some embodiments of the preparation method of the present invention, the "field-induced dynamic nucleation-gradient modulation crystallization" process in step (d) refers to applying non-equilibrium dynamic perturbation to the glass system through an external field (electric field) to induce internal concentration fluctuation regulation and effectively reduce the nucleation activation energy barrier; in the crystallization stage, the dynamic competition between crystal nucleus development and crystal growth is precisely controlled by a gradient variable speed heating strategy to achieve synergistic optimization of high crystallinity and uniform grain size, and solve the contradiction between crystallinity and light transmittance in the preparation of transparent microcrystalline glass.

[0020] As some embodiments of the preparation method of the present invention, the "heterogeneous lattice epitaxial template crystallization" process in step (d) refers to the process of introducing a preset micron-scale lattice template into the glass matrix, utilizing the difference in interfacial energy between the template and the glass network and the lattice matching characteristics to significantly reduce the energy barrier for heterogeneous nucleation. During the heat treatment process, local activation sites are formed on the surface of the seed crystal, which preferentially adsorb free ions in the glass, guide the crystal to grow along the template lattice direction, and achieve efficient and selective precipitation of specific crystal phases.

[0021] As some embodiments of the preparation method of the present invention, the nucleation temperature in step (d) is within 30 °C above and below the glass transition temperature, the holding time is 6 h to 72 h, and an alternating electric field with a frequency of 50 Hz is applied throughout the process.

[0022] As some embodiments of the preparation method of the present invention, the crystallization temperature in step (d) is within the range of the glass’s crystallization start temperature to crystallization end temperature, the holding time is 0.2 h to 10 h, and an alternating electric field with a frequency of 50 Hz is applied throughout the process.

[0023] As a preferred embodiment of the preparation method of the present invention, the stirring rate of the glass melt in step (b) is 10-20 r / min.

[0024] As a preferred embodiment of the preparation method of the present invention, the heat preservation time at 1500-1600 °C in step (b) is 0.5 h to 1.0 h.

[0025] As a preferred embodiment of the preparation method of the present invention, the heating rate of the electromagnetic induction melting furnace in step (b) is 20-80 °C / min.

[0026] In some preferred embodiments of the preparation method of the present invention, the heating rate of the annealing furnace and the heating furnace in steps (c), (d) and (e) is 5-15 °C / min, and the cooling rate is 10-20 °C / min.

[0027] As a preferred embodiment of the preparation method of the present invention, the holding time of the bulk glass in the annealing furnace in step (c) is 10 h to 24 h.

[0028] As a preferred embodiment of the preparation method of the present invention, the holding time in step (d) is 12 h to 48 h at the nucleation temperature stage and 0.5 h to 3 h at the crystallization temperature stage.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) This invention has low investment, abundant raw materials, simple production process, and unstrict process conditions, making it suitable for industrial production.

[0031] (2) The microcrystalline glass prepared by the present invention has the characteristics of high crystallinity, high transmittance, adjustable emission peak value between 480 nm and 520 nm, high luminous efficiency and excellent resistance to thermal quenching.

[0032] (3) This invention uses black talc powder as the main raw material and uses the "field-induced dynamic nucleation-gradient modulation crystallization" process and the "heterogeneous lattice epitaxial template crystallization" process to prepare rare earth doped silicate system high crystallinity transparent microcrystalline glass. This not only enhances the potential value of black talc in the field of optoelectronic materials, but also provides an innovative path for realizing high-efficiency light emission of high crystallinity transparent microcrystalline glass through the proposed nucleation and crystallization process. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 The image shows the XRD pattern of the highly crystalline transparent microcrystalline glass with rare earth doped silicate system obtained in Example 1 of this invention.

[0035] Figure 2 The transmission spectrum is that of the highly crystalline transparent microcrystalline glass with rare earth doped silicate system obtained in Example 1 of the present invention.

[0036] Figure 3 The emission spectrum is that of the rare earth-doped silicate system highly crystalline transparent microcrystalline glass obtained in Example 1 of this invention.

[0037] Figure 4 The temperature-dependent emission spectrum of the rare-earth-doped silicate system highly crystalline transparent microcrystalline glass obtained in Example 1 of this invention. Detailed Implementation

[0038] To make the technical means, creative features, objectives and effects of this invention easier to understand, the technical solutions in the specific embodiments of this invention are described clearly and completely below to further illustrate this invention. Obviously, the specific embodiments described are only a part of the embodiments of this invention, and not all of them.

[0039] Example 1

[0040] This embodiment discloses a highly crystalline transparent glass-ceramic based on a rare-earth-doped silicate system. The preparation method and process of this glass-ceramic are as follows:

[0041] (a) Weigh the raw materials according to the predetermined mass percentages: black talc powder: 13.5000 g; CaO: 4.5918 g; AlF3: 9.1837 g; YF3: 3.0612 g; graphite powder: 0.9091 g; Si3N4: 1.2012 g; EuCl2: 0.2400 g; Sb2O3: 0.2412 g; CaAl2Si2O8: 0.0060 g; mix the above raw materials together and grind them in an agate mortar for 1.0 h to obtain a uniformly mixed material.

[0042] (b) The obtained mixture is loaded into a corundum crucible and placed into a graphite crucible in an electromagnetic induction melting furnace. The melting furnace is heated from room temperature to 1520 °C at a heating rate of 40 °C / min and held for 25 min to obtain a uniformly molten glass liquid. During the melting process, the molten liquid is stirred at a stirring rate of 15 r / min.

[0043] (c) Quickly remove the molten glass from the melting furnace and pour it onto a mold that is preheated to 580 °C at a heating rate of 8 °C / min. Press it into shape and then quickly transfer the formed block glass into an annealing furnace at the same temperature and hold it for 12 h. After annealing, cool the annealing furnace to room temperature at a cooling rate of 15 °C / min to obtain a uniformly molten base glass.

[0044] (d) The obtained base glass is cut into regular blocks and polished. Then the glass is placed in a heating furnace for heat treatment. The base glass is nucleated and crystallized using the "field-induced dynamic nucleation-gradient modulation crystallization" process and the "heterogeneous lattice epitaxial template crystallization" process: the temperature is raised to the glass nucleation temperature of 750 ℃ ​​at a heating rate of 8 ℃ / min and held for 15 h. Then the temperature is raised to the glass crystallization temperature of 830 ℃ at a heating rate of 10 ℃ / min and held for 1 h. An alternating electric field with a frequency of 50 Hz is applied throughout the heat treatment process.

[0045] (e) After the heat treatment is completed, the heating furnace is cooled to room temperature at a cooling rate of 15 °C / min to obtain a highly crystalline transparent microcrystalline glass based on rare earth doped silicate system.

[0046] The highly crystalline transparent microcrystalline glass of the rare earth-doped silicate system obtained in this embodiment was tested, such as... Figures 1-4 As shown, its main crystalline phase is CaAl2Si2O8 and a small amount of YF3. Under 420 nm violet light excitation, the emission peak is located between 430 and 700 nm, with a peak value of 490 nm. The crystallinity is 75.0 vol.%, the transmittance of 1 mm sample is 85%, the luminescence intensity at 150 °C is 86.2% of the luminescence intensity at room temperature, and the internal quantum efficiency is 83.3%.

[0047] Example 2

[0048] This embodiment discloses a highly crystalline transparent glass-ceramic based on a rare-earth-doped silicate system. The preparation method and process of this glass-ceramic are as follows:

[0049] (a) Weigh the raw materials according to the predetermined mass percentages: black talc powder: 14.4000 g; CaO: 4.5918 g; AlF3: 7.5758 g; YF3: 7.2072 g; graphite powder: 1.2121 g; Si3N4: 1.5015 g; EuCl2: 0.4500 g; Sb2O3: 0.2412 g; NaSbO3: 0.1531 g; CaAl2Si2O8: 0.0120 g; mix the above raw materials together and grind them in an agate mortar for 1.5 h to obtain a uniformly mixed material.

[0050] (b) The obtained mixture is loaded into a corundum crucible and placed into a graphite crucible in an electromagnetic induction melting furnace. The furnace is heated from room temperature to 1540 ℃ at a heating rate of 50 ℃ / min and held for 30 min to obtain a uniformly molten glass liquid. During the melting process, the molten liquid is stirred at a stirring rate of 18 r / min.

[0051] (c) Quickly remove the molten glass from the melting furnace and pour it onto a mold that is preheated to 600 ℃ at a heating rate of 10 ℃ / min. Press it into shape and then quickly transfer the formed block glass into an annealing furnace at the same temperature and keep it for 15 h. After annealing, cool the annealing furnace to room temperature at a cooling rate of 15 ℃ / min to obtain a uniformly molten base glass.

[0052] (d) The obtained base glass is cut into regular blocks and polished. Then the glass is placed in a heating furnace for heat treatment. The base glass is nucleated and crystallized using the "field-induced dynamic nucleation-gradient modulation crystallization" process and the "heterogeneous lattice epitaxial template crystallization" process: the temperature is raised to the glass nucleation temperature of 760 ℃ at a heating rate of 10 ℃ / min and held for 18 h. Then the temperature is raised to the crystallization temperature of 840 ℃ at a heating rate of 12 ℃ / min and held for 1.5 h. An alternating electric field with a frequency of 50 Hz is applied throughout the heat treatment process.

[0053] (e) After the heat treatment is completed, the heating furnace is cooled to room temperature at a cooling rate of 15 °C / min to obtain a highly crystalline transparent microcrystalline glass based on rare earth doped silicate system.

[0054] The highly crystalline transparent microcrystalline glass of rare earth doped silicate system obtained in this embodiment was tested. Its main crystalline phase is CaAl2Si2O8 and a small amount of YF3. Under 420 nm violet light excitation, the emission peak is located between 430 and 700 nm, the peak value of the emission peak is 495 nm, the crystallinity is 78.5 vol.%, the transmittance of 1 mm sample is 84%, the luminescence intensity at 150 °C is 88.2% of the luminescence intensity at room temperature, and the internal quantum efficiency is 84.5%.

[0055] Example 3

[0056] This embodiment discloses a highly crystalline transparent glass-ceramic based on a rare-earth-doped silicate system. The preparation method and process of this glass-ceramic are as follows:

[0057] (a) Weigh the raw materials according to the predetermined mass percentages: black talc powder: 15.0000 g; CaO: 4.2857 g; AlF3: 8.4848 g; YF3: 4.8048 g; graphite powder: 0.9091 g; Si3N4: 1.5015 g; EuF2: 0.6001 g; Sb2O3: 0.1206 g; NaSbO3: 0.2755 g; CaAl2Si2O8: 0.0240 g; mix the above raw materials together and grind them in an agate mortar for 2 hours to obtain a uniformly mixed material.

[0058] (b) The obtained mixture is loaded into a corundum crucible and placed into a graphite crucible in an electromagnetic induction melting furnace. The furnace is heated from room temperature to 1540 ℃ at a heating rate of 60 ℃ / min and held for 35 min to obtain a uniformly molten glass liquid. During the melting process, the molten liquid is stirred at a stirring rate of 18 r / min.

[0059] (c) Quickly remove the molten glass from the melting furnace and pour it onto a mold that is preheated to 600 ℃ at a heating rate of 10 ℃ / min. Press it into shape and then quickly transfer the formed block glass into an annealing furnace at the same temperature and keep it for 16 h. After annealing, cool the annealing furnace to room temperature at a cooling rate of 16 ℃ / min to obtain a uniformly molten base glass.

[0060] (d) The obtained base glass is cut into regular blocks and polished. Then the glass is placed in a heating furnace for heat treatment. The base glass is nucleated and crystallized using the "field-induced dynamic nucleation-gradient modulation crystallization" process and the "heterogeneous lattice epitaxial template crystallization" process: the temperature is raised to the glass nucleation temperature of 755 ℃ at a heating rate of 8 ℃ / min and held for 24 h. Then the temperature is raised to the glass crystallization temperature of 840 ℃ at a heating rate of 12 ℃ / min and held for 1.5 h. An alternating electric field with a frequency of 50 Hz is applied throughout the heat treatment process.

[0061] (e) After the heat treatment is completed, the heating furnace is cooled to room temperature at a cooling rate of 18 °C / min to obtain a highly crystalline transparent microcrystalline glass based on rare earth doped silicate system.

[0062] The highly crystalline transparent microcrystalline glass of rare earth doped silicate system obtained in this embodiment was tested. Its main crystalline phase is CaAl2Si2O8 and a small amount of YF3. Under 420 nm violet light excitation, the emission peak is located between 430 and 700 nm, the peak value of the emission peak is 495 nm, the crystallinity is 76.0 vol.%, the transmittance of 1 mm sample is 84.6%, the luminescence intensity at 150 °C is 89.8% of the luminescence intensity at room temperature, and the internal quantum efficiency is 84.2%.

[0063] Example 4

[0064] This embodiment discloses a highly crystalline transparent glass-ceramic based on a rare-earth-doped silicate system. The preparation method and process of this glass-ceramic are as follows:

[0065] (a) Weigh the raw materials according to the predetermined mass percentages: black talc powder: 15.9000 g; CaO: 3.6735 g; AlF3: 7.2727 g; YF3: 6.6066 g; graphite powder: 1.8182 g; Si3N4: 1.2012 g; EuF2: 0.7501 g; Sb2O3: 0.1508 g; NaSbO3: 0.2143 g; CaAl2Si2O8: 0.0060 g; mix the above raw materials together and grind them in an agate mortar for 1.5 h to obtain a uniformly mixed material.

[0066] (b) The obtained mixture is loaded into a corundum crucible and placed into a graphite crucible in an electromagnetic induction melting furnace. The furnace is heated from room temperature to 1550 °C at a heating rate of 65 °C / min and held for 40 min to obtain a uniformly molten glass liquid. During the melting process, the molten liquid is stirred at a stirring rate of 15 r / min.

[0067] (c) Quickly remove the molten glass from the melting furnace and pour it onto a mold that is preheated to 610 °C at a heating rate of 8 °C / min. Press it into shape and then quickly transfer the formed block glass into an annealing furnace at the same temperature and hold it for 18 h. After annealing, cool the annealing furnace to room temperature at a cooling rate of 15 °C / min to obtain a uniformly molten base glass.

[0068] (d) The obtained base glass is cut into regular blocks and polished. Then the glass is placed in a heating furnace for heat treatment. The base glass is nucleated and crystallized using the "field-induced dynamic nucleation-gradient modulation crystallization" process and the "heterogeneous lattice epitaxial template crystallization" process: the temperature is raised to the glass nucleation temperature of 750 ℃ ​​at a heating rate of 12 ℃ / min and held for 26 h. Then the temperature is raised to the glass crystallization temperature of 845 ℃ at a heating rate of 8 ℃ / min and held for 2 h. An alternating electric field with a frequency of 50 Hz is applied throughout the heat treatment process.

[0069] (e) After the heat treatment is completed, the heating furnace is cooled to room temperature at a cooling rate of 15 °C / min to obtain a highly crystalline transparent microcrystalline glass based on rare earth doped silicate system.

[0070] The rare-earth-doped silicate system highly crystalline transparent microcrystalline glass obtained in this embodiment was tested. Its main crystalline phase is CaAl2Si2O8 and a small amount of YF3. Under 420 nm violet light excitation, the emission peak is located between 430 and 700 nm, the peak value of the emission peak is 500 nm, the crystallinity is 79.5 vol.%, the transmittance of 1 mm sample is 83.6%, the luminescence intensity at 150 °C is 89.5% of the luminescence intensity at room temperature, and the internal quantum efficiency is 85.8%.

[0071] Example 5

[0072] This embodiment discloses a highly crystalline transparent glass-ceramic based on a rare-earth-doped silicate system. The preparation method and process of this glass-ceramic are as follows:

[0073] (a) Weigh the raw materials according to the predetermined mass percentages: black talc powder: 16.5000 g; CaO: 3.6735 g; AlF3: 6.9697 g; YF3: 6.0060 g; graphite powder: 1.5152 g; Si3N4: 0.9009 g; EuCl2: 1.0501 g; NaSbO3: 0.3980 g; CaAl2Si2O8: 0.0090 g; mix the above raw materials together and grind them in an agate mortar for 1.0 h to obtain a uniformly mixed material.

[0074] (b) The obtained mixture is loaded into a corundum crucible and placed into a graphite crucible in an electromagnetic induction melting furnace. The furnace is heated from room temperature to 1580 ℃ at a heating rate of 70 ℃ / min and held at that temperature for 45 min to obtain a uniformly molten glass liquid. During the melting process, the molten liquid is stirred at a stirring rate of 18 r / min.

[0075] (c) Quickly remove the molten glass from the melting furnace and pour it onto a mold that is preheated to 600 ℃ at a heating rate of 12 ℃ / min. Press it into shape and then quickly transfer the formed block glass into an annealing furnace at the same temperature and hold it for 16 h. After annealing, cool the annealing furnace to room temperature at a cooling rate of 18 ℃ / min to obtain a uniformly molten base glass.

[0076] (d) The obtained base glass is cut into regular blocks and polished. Then the glass is placed in a heating furnace for heat treatment. The base glass is nucleated and crystallized using the "field-induced dynamic nucleation-gradient modulation crystallization" process and the "heterogeneous lattice epitaxial template crystallization" process: the temperature is raised to the glass nucleation temperature of 755 ℃ at a heating rate of 10 ℃ / min and held for 24 h. Then the temperature is raised to the glass crystallization temperature of 860 ℃ at a heating rate of 14 ℃ / min and held for 1.5 h. An alternating electric field with a frequency of 50 Hz is applied throughout the heat treatment process.

[0077] (e) After the heat treatment is completed, the heating furnace is cooled to room temperature at a cooling rate of 18 °C / min to obtain a highly crystalline transparent microcrystalline glass based on rare earth doped silicate system.

[0078] The highly crystalline transparent microcrystalline glass of rare earth doped silicate system obtained in this embodiment was tested. Its main crystalline phase is CaAl2Si2O8 and a small amount of YF3. Under 420 nm violet light excitation, the emission peak is located between 430 and 700 nm, the peak value of the emission peak is 510 nm, the crystallinity is 80.5 vol.%, the transmittance of 1 mm sample is 85.6%, the luminescence intensity at 150 °C is 88.6% of the luminescence intensity at room temperature, and the internal quantum efficiency is 87.8%.

[0079] The main technical features, basic principles, and related advantages of the present invention have been described above. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the concept or basic characteristics of the invention. Therefore, the above-described embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

[0080] Furthermore, it should be understood that although this specification describes various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A highly crystalline transparent microcrystalline glass based on a rare-earth-doped silicate system, characterized in that, The main crystalline phase in this microcrystalline glass is CaAl2Si2O8 and a small amount of YF3. The crystallinity is ≥ 70 vol.%, the transmittance of a 1 mm sample is ≥ 80%, the emission peak value is adjustable between 480 nm and 520 nm, the internal quantum efficiency is ≥ 80%, the luminescence intensity at 150℃ is ≥ 85%, and the luminescence intensity at room temperature is ≥ 85%. The main raw materials in the base glass by weight percentage are: black talc powder: 45-65 wt.%; CaO: 10-20 wt.%; AlF3: 15-30 wt.%; YF3: 5-15 wt.%; The external additives are: graphite powder as 2–15 wt.% of the total mass of the main raw materials; Si3N4 as 2–15 wt.% of the total mass of the main raw materials; rare earth compounds as 0.1–5 wt.% of the total mass of the main raw materials; and clarifying agents as 0.1–2 wt.% of the total mass of the main raw materials. The content of micron-sized seed crystals CaAl2Si2O8 is 0.01–0.1 wt.% of the total mass of the main raw materials. The rare earth compound used for external doping is EuCl2 or EuF2.

2. The rare-earth-doped silicate system highly crystalline transparent microcrystalline glass according to claim 1, characterized in that, The black talc powder in the raw material has a particle size of 50–150 μm.

3. The rare-earth-doped silicate system highly crystalline transparent microcrystalline glass according to claim 1, characterized in that, The clarifying agent is one or a combination of two of Sb2O3 or NaSbO3; the total content of graphite powder and Si3N4 in the external additive is ≥ 5 wt.%.

4. A method for preparing a highly crystalline transparent microcrystalline glass based on a rare earth-doped silicate system as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (a) Weigh each raw material precisely according to a predetermined mass percentage, put them into an agate mortar and grind for 0.2 h to 4 h to obtain a uniform mixture; (b) The obtained mixture is loaded into a corundum crucible and placed into a graphite crucible in an electromagnetic induction melting furnace. The mixture is heated from room temperature to 1500-1600 °C and held for 0.2-3 h to obtain a uniformly molten glass liquid. (c) Quickly remove the molten glass from the melting furnace, pour it onto a mold preheated to 550-650 °C and press it into shape. Then quickly transfer the formed block glass into an annealing furnace at the same temperature and keep it for 5-30 h. After annealing, the annealing furnace is cooled to room temperature to obtain a uniformly molten base glass. (d) The obtained base glass is cut into regular blocks and polished. Then the glass is placed in a heating furnace for heat treatment. The base glass is nucleated and crystallized by electric field dynamic nucleation process near the glass nucleation temperature and crystallization temperature. (e) After the heat treatment is completed, the heating furnace is cooled to room temperature to obtain a highly crystalline transparent microcrystalline glass based on rare earth doped silicate system.

5. The method for preparing a highly crystalline transparent microcrystalline glass based on a rare earth-doped silicate system according to claim 4, characterized in that, Once the powdered raw material inside the crucible in the electromagnetic induction melting furnace in step (b) has turned into molten glass, mechanical stirring is performed at a stirring rate of 5 to 60 r / min.

6. The method for preparing a highly crystalline transparent microcrystalline glass based on a rare earth-doped silicate system according to claim 4, characterized in that, In step (b), the heating rate of the electromagnetic induction melting furnace is 10–120 °C / min; in steps (c), (d), and (e), the heating and cooling rates of the annealing furnace and the heating furnace are 5–30 °C / min.

7. The method for preparing a highly crystalline transparent microcrystalline glass based on a rare earth-doped silicate system according to claim 4, characterized in that, In step (d), the nucleation temperature is within 30°C above and below the glass transition temperature, and the holding time is 6h to 72h. An alternating electric field with a frequency of 50 Hz is applied throughout the process.

8. The method for preparing a highly crystalline transparent microcrystalline glass based on a rare earth-doped silicate system according to claim 4, characterized in that, In step (d), the crystallization temperature is within the range of the glass’s crystallization start temperature to crystallization end temperature, and the holding time is 0.2 h to 10 h. An alternating electric field with a frequency of 50 Hz is applied throughout the process.

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