A type of Cr 3+ Activated β-Ga2O3 with interstitial oxygen ions and its derived near-infrared luminescent materials, their preparation methods and applications

Abstract

The present invention belongs to the technical field of luminescent materials, and specifically relates to a Cr 3+ activated near-infrared luminescent material of β-Ga2O3 with interstitial oxygen ions and derivative structures thereof, as well as a preparation method and use thereof. The chemical structural formula of the near-infrared luminescent material is A x B y Cr z O 3+a , wherein: A is one or more of trivalent cations Ga, Sc and In, A must contain Ga, B is one of tetravalent cations Ge, Sn and Ti, 0<y≤0.2, 0<z≤0.1, x+y+z=2, 0<a≤0.1. In the present invention, non-equivalent substitution of tetravalent ions Ge 4+ , Sn 4+ or Ti 4+ for trivalent ions Ga 3+ , Sc 3+ , In 3+ is carried out in the β-Ga2O3 and derivative structure near-infrared luminescent materials thereof, so as to introduce interstitial oxygen ions and maintain the charge balance of the system, thereby achieving improvement of luminescence intensity and thermal stability, and not changing the excitation and emission spectra of the luminescent material.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, specifically relating to a Cr... 3+ Activated β-Ga2O3 with interstitial oxygen ions and its derived near-infrared luminescent materials, their preparation methods, and applications. Background Technology

[0002] In recent years, with the rapid development of near-infrared spectroscopy technology in fields such as facial recognition, iris recognition, security monitoring, lidar, health detection, and 3D sensing, near-infrared LEDs have become an international research focus due to their advantages such as good directivity, deep penetration, low interference, low power consumption, and small size. Currently, the main technology for achieving near-infrared emission from LEDs is through near-infrared chips, but this technology is costly, immature, and has a narrow half-width at half-maximum (WHM) for the emission wavelength, limiting its applications to areas such as tube-to-tube emission and security. Another technology for achieving LED infrared emission is using blue light chips to excite near-infrared phosphors. This technology offers advantages such as lower cost and broad-spectrum emission, and is widely used in plant lighting, standard light sources, and health detection. Currently, the development of near-infrared LEDs is still in its early stages, and existing near-infrared luminescent materials still suffer from low efficiency and insufficient thermal stability. Furthermore, in health detection and food detection, since different substances and environments have different optimal absorption positions for near-infrared light, the development of spectrally tunable near-infrared luminescent materials is also of research value. Therefore, the development of high-performance, high-efficiency, and tunable broadband near-infrared phosphors is of great significance.

[0003] Currently, methods such as ion equivalent substitution processes and improvements in preparation techniques are used to improve Cr content. 3+ Numerous reports have documented the quantum efficiency and thermal stability of doped near-infrared luminescent materials, but performance improvements through equivalent substitution are often accompanied by changes in excitation and emission spectra, failing to address the challenge of enhancing the luminescence performance of existing near-infrared fluorescent materials. In Cr... 3+ In doped near-infrared luminescent materials, interstitial ions, such as O, are formed through non-equivalent substitution. 2- No similar methods have been reported to improve luminous efficiency and thermal stability by addressing gaps, etc. Summary of the Invention

[0004] Therefore, the present invention is based on Cr 3+ Activated β-Ga2O3 and its derived near-infrared luminescent materials provide a Cr 3+ Activated β-Ga₂O₃ with interstitial oxygen ions and its derived near-infrared luminescent materials, their preparation methods, and applications. This invention utilizes tetravalent Ge₂O₃ ions... 4+ Sn 4+ or Ti4+ For trivalent Ga ions 3+ ,Sc 3+ In 3+ Non-equivalent substitution generates interstitial oxygen ions in the structure, improving structural rigidity and suppressing Cr. 3+ The non-radiative transitions between ions significantly improve the luminescence intensity and thermal stability compared to materials without interstitial oxygen ions. The near-infrared luminescent material provided by this invention can emit near-infrared light under near-ultraviolet or blue light excitation, and a series of near-infrared luminescent materials with different emission peak positions, spectral peak shapes, and full width at half maximum (FWHM) can be obtained through compositional control.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a Cr 3+ Activated with gap O 2- Near-infrared luminescent materials of β-Ga2O3 and its derived structures, wherein the chemical structural formula of the luminescent material is A x B y Cr z O 3+a Where: A is one or more of the trivalent cations Ga, Sc, and In, and A must contain Ga; B is one of the tetravalent cations Ge, Sn, and Ti; 0 <y≤0.2,0<z≤0.1,x+y+z=2,0<a≤0.1。

[0007] In the above technical solution, the molar percentage of Ga in the luminescent material is greater than 50%.

[0008] Furthermore, in the above technical solution, the near-infrared luminescent material belongs to the monoclinic crystal system and has a space group of C2 / m.

[0009] Another aspect of the present invention provides a method for preparing the above-mentioned near-infrared luminescent material, the method comprising the following steps:

[0010] Step 1: According to chemical structural formula A x B y Cr z O 3+a Weigh out source A, source B, and source Cr according to their stoichiometric ratios; Step 2: Grind and mix the raw materials to obtain a mixture;

[0011] Step 3: The mixture obtained in Step 2 is sintered in a muffle furnace in stages, and then cooled to room temperature to obtain the sintered product;

[0012] Step 4: Crush the sintered material obtained in Step 3 into powder to obtain near-infrared luminescent material.

[0013] In the above technical solution, the A source is one or more of the oxides, carbonates, and nitrates of metal A; the B source is one or more of the oxides, carbonates, and nitrates of metal B; and the Cr source is one or more of chromium oxide, chromium carbonate, and chromium nitrate.

[0014] In the above technical solution, further, in step 3, the segmented sintering is as follows: first, the temperature is raised to 600-800℃ at a heating rate of 5℃ / min and held for 0.5-1h, and then the temperature is raised to 1200-1500℃ at a heating rate of 5℃ / min and held for 4-8 hours.

[0015] The present invention also provides a near-infrared LED device, comprising an LED chip, wherein the LED chip is coated with the near-infrared luminescent material according to any one of claims 1-3.

[0016] In the above technical solution, the light emission wavelength of the LED chip is further 300nm-600nm.

[0017] The beneficial effects of this invention are as follows:

[0018] 1) This invention involves the induction of tetravalent Ge ions in near-infrared luminescent materials of β-Ga2O3 and its derived structures. 4+ Sn 4+ or Ti 4+ For trivalent Ga ions 3+ ,Sc 3+ In 3+ Non-equivalent substitution is used to introduce interstitial oxygen ions and maintain the charge balance of the system, thereby improving the luminescence intensity and thermal stability without changing the excitation and emission spectra of the luminescent material.

[0019] 2) In Cr 3+ In activated β-Ga2O3 and its derived structures (Ga,Sc,In)2O3, compared with luminescent materials without interstitial oxygen structures, the introduction of interstitial oxygen structures can improve luminescence intensity and thermal stability. In different materials, by introducing suitable tetravalent cations to construct interstitial oxygen structures, the luminescence intensity can reach up to 1.8 times that of the original luminescent materials, and the luminescence thermal stability (the ratio of luminescence intensity at 150℃ to luminescence intensity at room temperature) can be improved by about 40%.

[0020] 3) The near-infrared luminescent material with interstitial oxygen structure of the present invention has a wide excitation band (250nm-600nm), which can be effectively excited by ultraviolet light and near-ultraviolet light. Its emission spectrum is near-infrared emission in the range of 600nm-950nm, and its emission peak can be adjusted in the range of 680nm-850nm, and its full width at half maximum (FWHM) can be adjusted in the range of 25nm-170nm.

[0021] 4) The near-infrared phosphor with interstitial oxygen structure of the present invention has excellent luminescence intensity. For different wavelength emission embodiments, the external quantum efficiency of 40%-53% can be achieved through the design of the interstitial oxygen structure.

[0022] 5) The green phosphor of this invention is prepared by a high-temperature solid-state method. The reactants are uniformly mixed and in close contact with each other. At high temperature, the ions near the contact surface have enough energy to break free from the constraints of their inherent lattice points and diffuse. Through the mutual diffusion of different atoms and the formation and enlargement of crystal nuclei, a luminescent material is formed. The preparation process is simple and easy, low in cost, non-toxic, non-polluting, and can be industrially produced. Attached Figure Description

[0023] Figure 1 The XRD spectra of the near-infrared luminescent materials prepared in Example 5 and Comparative Example 2 are shown below.

[0024] Figure 2 This is a comparison of the emission spectra of the near-infrared luminescent materials prepared in Example 5 and Comparative Example 2 under 450 nm excitation.

[0025] Figure 3 This is a comparison graph showing the change in luminescence intensity as a function of temperature for the near-infrared luminescent materials prepared in Example 5 and Comparative Example 2 under 450 nm excitation.

[0026] Figure 4 The results show the quantum efficiency test results of the near-infrared luminescent materials prepared in Example 5 and Comparative Example 2. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments and accompanying drawings. These descriptions are for illustrative purposes only and are not intended to limit the scope of the invention.

[0028] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained commercially or prepared according to conventional methods known to those skilled in the art.

[0029] Example 1

[0030] Ga2O3, GeO2, and Cr2O3 were weighed according to a molar ratio of Ga, Ge, and Cr of 1.965:0.03:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1400℃ at a heating rate of 5℃ / min and held for 6 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0031] Example 2

[0032] Ga2O3, GeO2, and Cr2O3 were weighed according to a molar ratio of Ga, Ge, and Cr of 1.935:0.06:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1400℃ at a heating rate of 5℃ / min and held for 6 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0033] Example 3

[0034] Ga2O3, TiO2, and Cr2O3 were weighed according to a molar ratio of Ga, Ti, and Cr of 1.935:0.06:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1400℃ at a heating rate of 5℃ / min and held for 6 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0035] Example 4

[0036] Ga2O3, Sc2O3, GeO2, and Cr2O3 were weighed according to a molar ratio of Ga, Sc, Ge, and Cr of 1.565:0.4:0.03:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1500℃ at a heating rate of 5℃ / min and held for 8 hours. The mixture was then naturally cooled to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0037] Example 5

[0038] Ga2O3, Sc2O3, GeO2, and Cr2O3 were weighed according to a molar ratio of Ga, Sc, Ge, and Cr of 1.535:0.4:0.06:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1500℃ at a heating rate of 5℃ / min and held for 8 hours. The mixture was then naturally cooled to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0039] Example 6

[0040] Ga2O3, Sc2O3, GeO2, and Cr2O3 were weighed according to a molar ratio of Ga, Sc, Ge, and Cr of 1.395:0.4:0.2:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1500℃ at a heating rate of 5℃ / min and held for 8 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0041] Example 7

[0042] Ga2O3, In2O3, SnO2, and Cr2O3 were weighed according to a molar ratio of Ga, In, Sn, and Cr of 1.565:0.4:0.03:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1500℃ at a heating rate of 5℃ / min and held for 8 hours. The mixture was then naturally cooled to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0043] Example 8

[0044] Ga2O3, In2O3, SnO2, and Cr2O3 were weighed according to a molar ratio of Ga, In, Ti, and Cr of 1.535:0.4:0.06:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1500℃ at a heating rate of 5℃ / min and held for 8 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0045] Example 9

[0046] Ga₂O₃, Sc₂(CO₃)₃, GeO₂, and Cr₂(CO₃)₃ were weighed according to a molar ratio of Ga, Sc, Ge, and Cr of 1.3:0.4:0.2:0.1. The raw materials were then thoroughly ground and mixed to obtain a homogeneous mixture. This mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H₂ and 95% N₂ by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1200℃ at a heating rate of 5℃ / min and held for 4 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered product. The sintered product was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0047] Example 10

[0048] Ga2O3, Sc2(CO3)3, TiO2, and Cr2(CO3)3 were weighed according to a molar ratio of Ga, Sc, Ge, and Cr of 1.44:0.4:0.06:0.1. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1200℃ at a heating rate of 5℃ / min and held for 4 hours. The mixture was then naturally cooled to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0049] Comparative Example 1

[0050] Ga2O3 and Cr2O3 were weighed according to a molar ratio of Ga to Cr of 1.995:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1400℃ at a heating rate of 5℃ / min and held for 6 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0051] Comparative Example 2

[0052] Ga2O3, Sc2O3, and Cr2O3 were weighed according to a molar ratio of Ga, Sc, and Cr of 1.595:0.4:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1500℃ at a heating rate of 5℃ / min and held for 8 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0053] Comparative Example 3

[0054] Ga2O3, In2O3, and Cr2O3 were weighed according to a molar ratio of Ga, In, and Cr of 1.595:0.4:0.005. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1500℃ at a heating rate of 5℃ / min and held for 8 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0055] Comparative Example 4

[0056] Ga2O3, Sc2(CO3)3, and Cr2(CO3)3 were weighed according to a molar ratio of Ga, Sc, and Cr of 1.5:0.4:0.1. The raw materials were then thoroughly ground and mixed to obtain a mixture. The mixture was placed in a corundum crucible and then placed in a tube furnace. Under a reducing atmosphere consisting of 5% H2 and 95% N2 by volume, the temperature was first raised to 800℃ at a heating rate of 5℃ / min and held for 1 hour. Then, the temperature was raised to 1200℃ at a heating rate of 5℃ / min and held for 4 hours. The mixture was then allowed to cool naturally to room temperature to obtain a sintered material. The sintered material was crushed into powder and passed through a 300-mesh sieve to obtain near-infrared phosphor.

[0057] The near-infrared luminescent materials prepared in Examples 1-10 and Comparative Examples 1-4 were tested for photoluminescence properties. Their relative luminescence intensity and thermal stability under excitation at a wavelength of 450 nm were measured. The results are shown in Table 1 below.

[0058] Table 1. Emission intensity and thermal stability test results of Examples 1-10 and Comparative Examples 1-4

[0059]

[0060]

[0061] Figure 1 The XRD patterns of the near-infrared luminescent materials prepared in Example 5 and Comparative Example 2 are shown below. Figure 1 As can be seen from the comparison with the standard Ga2O3 card, when a small amount of tetravalent ions are doped, its crystal structure is not changed and no other impurity phases are generated.

[0062] Figure 2 This is a comparison diagram of the emission spectra of the near-infrared luminescent materials prepared in Example 5 and Comparative Example 2. Figure 2As can be seen, the intensity is significantly improved by doping with Ge, and the shape of its emission spectrum does not change significantly.

[0063] Figure 3 The curves showing the luminescence intensity of the near-infrared luminescent materials prepared in Example 5 and Comparative Example 2 as a function of temperature are shown. When the temperature increases from room temperature (25°C) to 225°C, it can be seen that the thermal stability is significantly improved by doping with Ge.

[0064] Figure 4 The quantum efficiency test results of the near-infrared luminescent materials prepared in Example 5 and Comparative Example 2 are as follows: Figure 4 As can be seen, the quantum efficiency is significantly improved by doping with Ge.

[0065] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A type of Cr 3+ Activated with gap O 2- The near-infrared luminescent material with a β-Ga2O3 structure is characterized by, The chemical structural formula of the luminescent material is A. x B y Cr z O 3+a Where: A is one or more of the trivalent cations Ga, Sc, and In, and A must contain Ga; B is one of the tetravalent cations Ge and Ti; 0 <y≤0.2,0<z≤0.1,x+y+z=2,0<a≤0.1; The molar percentage of Ga in the luminescent material is >50%.

2. The near-infrared luminescent material according to claim 1, characterized in that, The near-infrared luminescent material belongs to the monoclinic crystal system and has a space group of C2 / m.

3. A method for preparing the near-infrared luminescent material according to any one of claims 1-2, characterized in that, The method includes the following steps: Step 1: According to chemical structural formula A x B y Cr z O 3+a The stoichiometric ratios of the chemical components in the sample are determined by weighing source A, source B, and Cr source. Step 2: Grind and mix the raw materials to obtain a mixture; Step 3: The mixture obtained in Step 2 is sintered in a muffle furnace in stages, and then cooled to room temperature to obtain the sintered product; Step 4: Crush the sintered material obtained in Step 3 into powder to obtain near-infrared luminescent material.

4. The preparation method according to claim 3, characterized in that, The A source is one or more of the following: oxides, carbonates, and nitrates of metallic A; The B source is one or more of the following: oxides, carbonates, and nitrates of metallic B; The Cr source is one or more of chromium oxide, chromium carbonate, and chromium nitrate.

5. The preparation method according to claim 3, characterized in that, In step 3, the segmented sintering is as follows: first, the temperature is raised to 600-800℃ at a heating rate of 5℃ / min and held for 0.5-1h; then, the temperature is raised to 1200-1500℃ at a heating rate of 5℃ / min and held for 4-8 hours.

6. A near-infrared LED device, characterized in that, It includes an LED chip, wherein the LED chip is coated with the near-infrared luminescent material according to any one of claims 1-2.

7. The near-infrared LED device according to claim 6, characterized in that, The LED chip emits light at a wavelength of 300nm-600nm.

Images