An oxide near-infrared luminescent glass-ceramic material and its preparation method

Abstract

This invention discloses an oxide near-infrared luminescent glass-ceramic material and its preparation method. The glass-ceramic material has the general formula A. m B n C p D5O 14 :xCr 3+ ,yLn 3+ Where A is one or more combinations of alkali metals Li, Na, K, Rb, and Cs; B is one or more combinations of elements Mg, Ca, Sr, Ba, and Zn; C is one or more combinations of elements Al, Ga, Fe, Nb, Ta, and rare earth elements; D is one or more combinations of elements Ti, Si, Ge, Zr, Sn, and Hf; and Ln is one or more rare earth ions Yb, Nd, Pr, Eu, Dy, and Sm. 0≤m≤2.5, 1≤n≤4, 0.5≤p≤1.5, 0

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, specifically relating to an oxide infrared luminescent glass-ceramic material and its preparation method. Background Technology

[0002] Near-infrared light has shown great promise in many fields, including plant growth, non-destructive testing in food analysis, night vision illumination, and bioimaging. However, existing near-infrared light sources still cannot meet practical needs in terms of luminous efficiency and emission bandwidth. Therefore, developing novel broadband near-infrared light sources has become a research focus for scholars both domestically and internationally. Among numerous design schemes, near-infrared phosphor-converted LEDs exhibit superior characteristics, including emission peak position, spectral width, luminous efficiency, and thermal stability. Furthermore, this scheme boasts advantages such as simple structure, tunable spectrum, green and safe fabrication method, low cost, and ease of miniaturization. Therefore, near-infrared phosphor-converted LEDs are considered one of the most reliable broadband near-infrared light source solutions and hold promise for use in portable devices such as mobile phones.

[0003] In recent years, a large number of active ions emitting near-infrared light have been developed, including transition metal ions (such as Mn). 2+ Ni 2+ Fe 3+ Cr 4+ and Mn 5+ ) and rare earth ions (such as Pr) 3+ 、Nd 3+ Tm 3+ Er 3+ and Yb 3+ However, most of these ions are inefficient, have weak absorption, narrow emission spectra, and cannot be excited by blue light. In several studies on near-infrared luminescent materials, Cr... 3+ The ion should be the optimal activating ion because it has a unique 3d... 3 Electronic configuration that favors spin forbidden ( 2 E→ 4 A2, 695nm) and spin-allowed ( 4 T2→ 4 The A2 (700-1100nm) transition is well-suited to low-cost silicon-based photodetectors. Furthermore, Cr... 3+ Excitation band of ions ( 4 A2→ 4 T2 (400-500nm) has a good match with the emission wavelength of low-cost commercial blue LED chips, making Cr 3+ Ions can be efficiently excited by blue light and have great application prospects.

[0004] Currently, Cr 3+The quantum efficiency of ion-doped near-infrared phosphors can reach close to 100%, but due to Cr... 3+ The parity-forbidden dd-transitions of ions generally result in absorption efficiencies below 50%. To address this issue, an effective method is to prepare glass-ceramics or transparent ceramics. This reduces the scattering of blue light in the phosphor, thereby enhancing the absorption efficiency of Cr. 3+ The absorption efficiency of ion-doped near-infrared phosphors in blue light. Meanwhile, traditional phosphor-converted LEDs (pc-LEDs) require encapsulation using a mixture of phosphor and curing colloid. Due to the low thermal conductivity of this mixture, prolonged operation not only degrades the device's luminous performance but also reduces the LED's lifespan. Therefore, directly encapsulating blue LEDs with glass-ceramic or transparent ceramics can not only improve the absorption efficiency of Cr... 3+ The absorption efficiency of ions in blue light can also improve their heat dissipation performance and lifespan. However, the existing conditions and methods for preparing glass-ceramics or transparent ceramics are demanding, and their luminescent performance is insufficient for large-scale applications. Therefore, the development of high-performance chromium-doped glass-ceramics or transparent ceramics is of great significance for near-infrared light source equipment and applications. Summary of the Invention

[0005] This invention overcomes the shortcomings of existing technologies and provides a simple and widely applicable method for preparing glass ceramics. Compared to powders and glass, glass ceramics exhibit significantly improved blue light absorption efficiency. When excited by a blue light chip, the emitted wavelength is between 650-1300nm, making it suitable for applications such as plant lighting, full-spectrum lighting, bio-imaging, and night vision.

[0006] The objective of this invention is achieved through at least one of the following technical solutions.

[0007] An oxide near-infrared luminescent glass-ceramic material comprising an inorganic compound, wherein the chemical formula of the inorganic compound is A. m B n C p D5O 14 :xCr 3+ ,yLn 3+ ;

[0008] A is one or more of the alkali metals Li, Na, K, Rb and Cs;

[0009] B is one or more of the elements Mg, Ca, Sr, Ba and Zn;

[0010] C is one or more of Al, Ga, In, Fe, Nb, Ta and rare earth elements;

[0011] D is one or more of the elements Ti, Si, Ge, Zr, Sn and Hf;

[0012] O represents oxygen.

[0013] Ln is one or more of the rare earth elements Yb, Nd, Pr, Eu, Dy, and Sm.

[0014] Cr 3+ Ln is the luminescent central ion. 3+ The sensitizing ion is defined as follows: 0 ≤ m ≤ 2.5, 1 ≤ n ≤ 4, 0 ≤ p ≤ 1.5, 0% <x≤100%,0%≤y≤20%;

[0015] Preferably, the luminescent glass-ceramic material emits wavelengths ranging from 650 to 1300 nm under blue light excitation at 430-470 nm, with a peak value around 680-100 nm and a half-peak width of 100-300 nm.

[0016] Preferably, by changing the annealing time and temperature of the material, the blue light absorption efficiency of the material can be increased from 20.1% to 43.4%.

[0017] The preparation method of the above-mentioned oxide near-infrared glass ceramic includes the following steps:

[0018] 1) According to the general chemical formula A m B n C p D5O 14 :xCr 3+ ,yLn 3+ Weigh out the compound raw materials containing each element according to the stoichiometric ratio, and grind and mix them to obtain a raw material mixture;

[0019] 2) The mixture obtained in step 1) is calcined at high temperature, cooled to room temperature, and then ground and sieved to obtain powder material;

[0020] 3) The powder material obtained in step 2) is subjected to high-temperature melting, cooling and annealing to obtain a glass precursor;

[0021] 4) The glass precursor obtained in step 3) is crystallized in air using an amorphous crystallization method. The crystallized material is then post-processed to obtain the oxide near-infrared glass ceramic.

[0022] Preferably, in step 1), the raw materials are elemental, oxide, halide, sulfide, carbonate, borate, sulfate, phosphate or nitrate of calcium, strontium, barium, lanthanum, neodymium, praseodymium, gallium, aluminum, titanium, tin, germanium, niobium, tantalum and chromium.

[0023] Preferably, in step 1), the grinding time is 5-60 minutes.

[0024] Preferably, in step 2), the high-temperature calcination is carried out in air or an inert atmosphere, the calcination temperature is 1000-1400℃, and the calcination time is 1-24h.

[0025] Preferably, in step 3), the melting temperature is 1300-1600℃ and the melting time is 0.2-4h; the annealing temperature is 450-600℃ and the annealing time is 3-10h.

[0026] Preferably, in step 4), the amorphous crystallization method is thermal crystallization, with a crystallization temperature of 650-1000℃ and a crystallization time of 1-24h; the post-treatment includes polishing with 180-grit, 400-grit, 800-grit, 1000-grit, 1500-grit and 2000-grit sandpaper respectively, followed by polishing with polishing powder, washing and drying.

[0027] The present invention has the following beneficial effects:

[0028] Compared to phosphors, glass ceramics increase the absorption efficiency of blue light from 20.1% to 43.1%, thereby improving the near-infrared emission efficiency.

[0029] Resin encapsulation was avoided when packaging the device, thus changing the LED packaging method and preventing excessive heat buildup that could lead to a decrease in luminous performance.

[0030] The method for fabricating fluorescent glass ceramics is simple, highly reproducible, and suitable for large-scale, batch industrial production. Furthermore, its chemical stability, density, thermal conductivity, and luminous efficiency are superior to those of traditional phosphors, resulting in significant improvements in device lifespan and emission power. Attached Figure Description

[0031] Figure 1 These are the XRD patterns of the near-infrared glass ceramics prepared in Examples 1-5;

[0032] Figure 2 The excitation and emission spectra of the near-infrared glass ceramic of Example 1 are shown.

[0033] Figure 3 This is the quantum yield test spectrum of the near-infrared glass ceramic of Example 1 and the phosphor of Comparative Example 1;

[0034] Figure 4 The excitation and emission spectra of the near-infrared glass ceramic of Example 7 and Comparative Example 3 are shown.

[0035] Figure 5 The excitation and emission spectra of the near-infrared glass ceramic of Example 8 and Comparative Example 4 are shown.

[0036] Figure 6 The excitation and emission spectra of the near-infrared glass ceramic of Example 9 and Comparative Example 5 are shown.

[0037] Figure 7 The excitation and emission spectra of the near-infrared glass ceramic of Example 10 and Comparative Example 6 are shown.

[0038] Figure 8 The excitation and emission spectra of the near-infrared glass ceramic of Example 11 and Comparative Example 8 are shown. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments and accompanying drawings to help understand the content of the present invention.

[0040] Example 1: Sr3MgGe5O 14 0.01Cr 3+ Preparation of fluorescent glass ceramics

[0041] The near-infrared glass ceramic of this embodiment has the chemical formula Sr3MgGe5O. 14 0.01Cr 3+ According to the stoichiometric ratio of each element in the chemical formula, high-purity powder raw materials of SrCO3, MgO, GeO2, and Cr2O3 were accurately weighed and ground in an agate mortar for about 30 minutes to ensure thorough and uniform mixing. The mixture was then transferred to an alumina crucible and sintered at 1150℃ for 6 hours in a high-temperature furnace under air atmosphere. After natural cooling, the near-infrared phosphor Sr3MgGe5O was obtained. 14 0.01Cr 3+ The prepared phosphor was transferred to an alumina crucible and melted in an air-atmosphere high-temperature reactor at 1350°C for 30 minutes. The melt was then quickly removed at this high temperature and poured onto a graphite mold preheated to 600°C. It was then pressed into shape using a steel plate and rapidly transferred to an annealing furnace at 600°C for approximately 4 hours. After natural cooling, the resulting glass was annealed in a 920°C high-temperature reactor for 8 hours to allow crystallization, followed by natural cooling to obtain Sr3MgGe5O. 14 0.01Cr 3+ Glass ceramics. The XRD and fluorescence spectra of its precursor glass and glass ceramics are as follows: Figure 1 and Figure 2 As shown. From Figure 1 It can be seen that this glass-ceramic is similar to Sr3MgGe5O 14 The standard card matches perfectly, with almost no excess crystalline phase.

[0042] Examples 2-5: Sr3MgGe5O 14 :xCr 3+ Preparation of fluorescent glass ceramics

[0043] The preparation methods for Examples 2-5 are the same as in Example 1, with the melting temperature and time of the glass precursor being identical. Their chemical composition, annealing crystallization temperature, annealing crystallization time, blue light absorption efficiency, and internal quantum efficiency are shown in Table 1. XRD comparison images of the near-infrared fluorescent glass-ceramics prepared in Examples 1-6 with standard cards are shown below. Figure 1 As can be seen from the figure, the main crystalline phase of the prepared glass-ceramic is similar to Sr3MgGe5O. 14 Isomorphism. The Sr3MgGe5O prepared in Examples 1-6 14 :xCr 3+ The quantum yield test results of glass ceramics (x = 0.01, 0.02, 0.03) are shown in Table 1.

[0044] Example 6: Sr3ZnGe5O 14 0.01Cr 3+ Preparation of fluorescent glass ceramics

[0045] The preparation method of Example 6 is the same as that of Example 1, with the melting temperature and time of the glass precursor being identical. Its annealing crystallization temperature, annealing crystallization time, blue light absorption efficiency, internal quantum efficiency, and luminescence thermal stability are shown in Table 1.

[0046] Examples 7-10: NaSr2CGe5O 14 0.07Cr 3+ Preparation of (C=Al,Ga,Sc,In) fluorescent glass ceramics

[0047] The preparation methods of Examples 7-10 are the same as those in Example 1, with the melting temperature and time of the glass precursor being identical. Their chemical composition, annealing crystallization temperature, annealing crystallization time, blue light absorption efficiency, internal quantum efficiency, and luminescence thermal stability are shown in Table 1.

[0048] Examples 11-12: NaB2ScGe5O 14 0.07Cr 3+ 0.05Yb 3+ Preparation of (B=Sr,Ca) fluorescent glass ceramics

[0049] The preparation methods for Examples 12-13 are the same as those for Example 1, with the melting temperature and time of the glass precursor being identical. Their chemical composition, annealing crystallization temperature, annealing crystallization time, blue light absorption efficiency, internal quantum efficiency, and luminescence thermal stability are shown in Table 1.

[0050] Examples 13-14: ASr2ScGe5O 14 0.07Cr 3+ 0.05Yb 3+Preparation of (A=Li,K) fluorescent glass ceramics

[0051] The preparation methods for Examples 13-14 are the same as those for Example 1, with the melting temperature and time of the glass precursor being identical. Their chemical composition, annealing crystallization temperature, annealing crystallization time, blue light absorption efficiency, internal quantum efficiency, and luminescence thermal stability are shown in Table 1.

[0052] Comparative Example 1: Sr3MgGe5O 14 0.01Cr 3+ Preparation of phosphors

[0053] The chemical formula of the near-infrared phosphor in this comparative example is Sr3MgGe5O. 14 0.01Cr 3+ According to the stoichiometric ratio of each element in the chemical formula, high-purity powder raw materials of SrCO3, MgO, GeO2, and Cr2O3 were accurately weighed and ground in an agate mortar for about 30 minutes to ensure thorough and uniform mixing. The mixture was then transferred to an alumina crucible and reacted in a high-temperature furnace under air atmosphere at 1150℃ for 6 hours. After natural cooling, the near-infrared phosphor Sr3MgGe5O was obtained. 14 0.01Cr 3+ Its blue light absorption efficiency, internal quantum efficiency, and luminescence thermal stability are shown in Table 2.

[0054] Comparative Example 2: Sr3ZnGe5O 14 0.01Cr 3+ Preparation of phosphors

[0055] The chemical formula of the near-infrared phosphor in this comparative example is Sr3MgGe5O. 14 0.01Cr 3+ According to the stoichiometric ratio of each element in the chemical formula, high-purity powder raw materials of SrCO3, ZnO, GeO2, and Cr2O3 were accurately weighed and ground in an agate mortar for about 30 minutes to ensure thorough and uniform mixing. The mixture was then transferred to an alumina crucible and reacted in a high-temperature furnace under air atmosphere at 1150℃ for 6 hours. After natural cooling, the near-infrared phosphor Sr3MgGe5O was obtained. 14 0.01Cr 3+ Its blue light absorption efficiency, internal and external quantum efficiency, and luminescence thermal stability are shown in Table 2.

[0056] Comparative Examples 3-6: NaSr2CGe5O 14 0.07Cr 3+ Preparation of (C=Al,Ga,Sc,In) phosphors

[0057] According to the stoichiometric ratio of each element in the chemical formula, high-purity powder raw materials of Na₂CO₃, SrCO₃, Al₂O₃, Ga₂O₃, Sc₂O₃, In₂O₃, GeO₂, and Cr₂O₃ were accurately weighed and ground in an agate mortar for about 30 minutes to ensure thorough and uniform mixing. The mixture was then transferred to an alumina crucible and reacted in a high-temperature furnace under air atmosphere at 1200℃ for 6 hours. After natural cooling, the near-infrared fluorescent powder NaSr₂CGe₅O₃ was obtained. 14 0.07Cr 3+ (C=Al,Ga,Sc,In) phosphor. Its blue light absorption efficiency, internal and external quantum efficiency, and luminescence thermal stability are shown in Table 2. Comparative Examples 7-8: NaB₂ScGe₅O 14 0.07Cr 3+ ,Yb 3+ Preparation of (B=Ca,Sr) phosphor

[0058] According to the stoichiometric ratio of each element in the chemical formula, high-purity powder raw materials of Na₂CO₃, CaCO₃, SrCO₃, Sc₂O₃, GeO₂, Yb₂O₃, and Cr₂O₃ were accurately weighed and ground in an agate mortar for about 30 minutes to ensure thorough and uniform mixing. The mixture was then transferred to an alumina crucible and reacted in a high-temperature furnace under air atmosphere at 1200℃ for 6 hours. After natural cooling, the near-infrared fluorescent powder NaCa₂ScGe₅O₃ was obtained. 14 0.07Cr 3+ Phosphor. Its blue light absorption efficiency, internal and external quantum efficiency, and luminescence thermal stability are shown in Table 2.

[0059] Comparative Examples 9-10: ASr2ScGe5O 14 0.07Cr 3+ Preparation of (A=Li,K) phosphor

[0060] According to the stoichiometric ratio of each element in the chemical formula, high-purity powder raw materials of Li₂CO₃, K₂CO₃, SrCO₃, Sc₂O₃, GeO₂, and Cr₂O₃ were accurately weighed and ground in an agate mortar for about 30 minutes to ensure thorough and uniform mixing. The mixture was then transferred to an alumina crucible and reacted in a high-temperature furnace under air atmosphere at 1200℃ for 6 hours. After natural cooling, the near-infrared phosphor ASr₂ScGe₅O₃ was obtained. 14 0.07Cr 3+ (A=Li,K) phosphor. Its blue light absorption efficiency, internal and external quantum efficiency, and luminescence thermal stability are shown in Table 2.

[0061] The phase composition of the samples in the examples and comparative examples was analyzed using X-ray powder diffraction (D8 advanced, Germany).

[0062] The excitation and emission spectra of the samples were measured using an FLS980 (Edinburgh Instruments) fluorescence spectrometer. Combined with a variable temperature stage of 77-600K, the variable temperature emission spectra of the materials were tested to evaluate the thermal stability of the materials.

[0063] The luminescence quantum yield of the material was tested using a fiber optic spectrometer (ATP5020R) connected to an integrating sphere via fiber optic coupling.

[0064] The sample synthesized by solid-state reaction method showed a homogeneous phase according to XRD analysis. The fluorescent glass-ceramic obtained after high-temperature melting and crystallization treatment contained some impurities, but these did not affect its luminescence properties. For example, the XRD diffraction pattern of the near-infrared fluorescent glass-ceramic prepared in Example 1 is shown below. Figure 1 As shown.

[0065] The excitation and emission spectra of the samples were measured using an FLS980 (Edinburgh Instruments) fluorescence spectrometer. The excitation and emission spectra of the luminescent material in Example 1 are as follows: Figure 2 As shown, the excitation spectrum of this luminescent material contains three effective excitation bands, namely 250-350nm, 420-580nm and 600-800nm; it can be seen that the emission spectrum of this luminescent material covers 700-1500nm, that is, it has near-infrared broadband emission performance. Figure 3 The excitation and emission spectra of Example 1 and Comparative Example 1 of this invention show that the luminescence intensity of the glass-ceramic material is significantly stronger than that of the powder material. The absorption efficiency and external quantum efficiency of the examples and comparative examples are shown in Table 1. The glass-ceramic material with the same chemical structure exhibits superior blue light absorption efficiency, external quantum efficiency, and thermal stability compared to the powder material.

[0066]

[0067] Table 2

[0068]

[0069]

[0070] It should be understood that the above detailed description of the technical solutions of the present invention with reference to optimized embodiments is illustrative and not restrictive. It should not be considered that the specific implementation of the present invention is limited to this. For those skilled in the art, any modifications to the technical solutions described in the embodiments or equivalent substitutions of some technical features without departing from the concept of the present invention should be considered as falling within the scope of patent protection defined by the claims submitted by the present invention.

[0071] The above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An oxide near-infrared luminescent glass-ceramic material, characterized in that, The chemical formula of the material is Sr3MgGe5O 14 :xCr 3+ , of which Cr 3+ It is a luminescent central ion, 0% <x≤3%。 2. The method for preparing near-infrared luminescent glass-ceramic materials according to claim 1, characterized in that, The preparation method includes the following steps: 1) According to the general chemical formula Sr3MgGe5O 14 :xCr 3+ Weigh out the compound raw materials containing each element according to the stoichiometric ratio, grind and mix them to obtain a raw material mixture; 2) The mixture obtained in step 1) is calcined at high temperature, cooled to room temperature, and then ground and sieved to obtain powder material; 3) The powder material obtained in step 2) is subjected to high-temperature melting, cooling and annealing to obtain a glass precursor; 4) The glass precursor obtained in step 3) is crystallized in air using an amorphous crystallization method. The crystallized material is then post-processed to obtain the oxide near-infrared glass ceramic.

3. The preparation method according to claim 2, characterized in that, In step 1), the grinding time is 5-60 minutes.

4. The preparation method according to claim 2, characterized in that, In step 2), the high-temperature calcination is carried out in air or an inert atmosphere, with a calcination temperature of 1000-1400℃ and a calcination time of 1-24h.

5. The preparation method according to claim 2, characterized in that, In step 3), the melting temperature is 1300-1600℃ and the melting time is 0.2-4h; the annealing temperature is 450-600℃ and the annealing time is 3-10h.

6. The preparation method according to claim 2, characterized in that, In step 4), the amorphous crystallization method is thermal crystallization, with a crystallization temperature of 650-1000℃ and a crystallization time of 1-24h; the post-treatment includes polishing with 180-grit, 400-grit, 800-grit, 1000-grit, 1500-grit and 2000-grit sandpaper respectively, followed by polishing with polishing powder, washing and drying.

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