Metal halide with high-temperature luminescence characteristic and preparation method and application thereof

Abstract

The invention provides a metal halide with a high-temperature luminescence characteristic, the chemical general formula of the metal halide is AX: Mn, AX is alkali metal halide, and Mn is doped manganese ions existing in the alkali metal halide; the metal halide shows a red light emitting characteristic at a low temperature and shows a yellow light emitting characteristic at a high temperature; the low temperature ranges from room temperature to 120 DEG C; the high temperature ranges from 330 DEG C to 450 DEG C. According to the preparation method, the metal halide with the high-temperature luminescence characteristic is formed by doping Mn < 2 + > into an alkali metal halide matrix, the preparation method can change the luminescence color at the high temperature, red light is converted into yellow light, and the metal halide can still keep the luminescence capacity at the high temperature of 450 DEG C, so that the metal halide has the high-temperature luminescence characteristic. Therefore, the light-emitting limitation of the traditional metal halide at high temperature is broken through.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature luminescent fluorescent materials, and in particular relates to a metal halide with high-temperature luminescent properties and a preparation method and application thereof. Background Art

[0002] Metal halides, including copper-based halides (Cs3Cu2I5, CsCu2I3), silver-based halides (AgBr, AgI), manganese-based halides (MnCl2, MnBr2), lead-based and tin-based halides (PbI2, SnI2), etc., have shown wide application potential in the field of luminescent materials due to their rich chemical composition and excellent luminescent properties. They have adjustable spectral absorption and emission ranges, high charge carrier mobility, and high luminescence quantum yields. At the same time, they are low-cost and easy to synthesize. These characteristics make metal halides ideal for optical devices and high-speed optoelectronic devices.

[0003] However, the luminescence intensity of metal halides is thermally quenched in high-temperature environments. For example, although Cs3Cu2I5 has efficient blue light emission, its luminescence intensity decreases when the temperature rises, and thermal quenching occurs. PbI2 exhibits thermal quenching in high-temperature environments. MnCl2 also exhibits thermal quenching in high-temperature environments, and the luminescence intensity decreases with increasing temperature; this is because the increase in temperature causes the excitation energy of the luminescence center to be consumed in the form of lattice vibration, and the luminescence efficiency decreases. The thermal quenching phenomenon greatly limits its application in high-temperature environments. Therefore, it is crucial to develop a new type of metal halide with high-temperature luminescence characteristics, so it needs to be improved. Summary of the invention

[0004] The purpose of the present invention is to provide a metal halide with high temperature luminescence characteristics and a preparation method and application thereof, by doping Mn in an alkali metal halide matrix. 2+ A preparation method for forming a metal halide with high-temperature luminescence characteristics. This preparation method can not only change the luminescence color at high temperature, from red light to yellow light, but also the metal halide can still maintain its luminescence ability at a high temperature of 450°C, thus breaking through the luminescence limitation of traditional metal halides at high temperatures.

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

[0006] A metal halide with high temperature luminescence characteristics, wherein the general chemical formula of the metal halide is AX:Mn, wherein AX is an alkali metal halide, and Mn is a doped manganese ion present in the alkali metal halide;

[0007] The metal halide exhibits red light emitting characteristics at low temperatures and yellow light emitting characteristics at high temperatures;

[0008] The low temperature ranges from room temperature to 120°C;

[0009] The high temperature ranges from 330°C to 450°C.

[0010] In the present invention, the emission wavelength of yellow light is in the range of 565nm-590nm.

[0011] In the present invention, the wavelength range of red light is 600nm-750nm. That is to say, the red light of the present application includes orange-red light, orange light, red light and the like.

[0012] Furthermore, the doping concentration of the manganese ions is 1% to 20%.

[0013] As a further preference, the doping concentration of the manganese ions is 5% to 20%.

[0014] Furthermore, the red light emitting characteristics and the yellow light emitting characteristics of the metal halide can be reversibly transformed to each other, and can spontaneously recover from yellow light to red light when the temperature decreases, showing a thermal recovery characteristic.

[0015] Furthermore, the metal halide has a regular octahedral coordination structure at low temperatures, and the metal halide has a regular tetrahedral coordination structure at high temperatures.

[0016] Furthermore, the regular octahedral coordination structure and the regular tetrahedral coordination structure can be reversibly transformed into each other, and can spontaneously recover from the regular tetrahedral coordination structure to the regular octahedral coordination structure when the temperature is lowered.

[0017] Furthermore, when the ambient temperature changes from low temperature to high temperature, the lattice tensile stress induced by manganese ions in the metal halide increases, and the increase in lattice tensile stress is determined by X-ray diffraction or electron diffraction.

[0018] Furthermore, in the AX, the alkali metal A is one or more of Li, Na, K, Rb, and Cs, and X is one or more of F, Cl, Br, and I.

[0019] A method for preparing a metal halide having high temperature luminescence characteristics comprises the following steps:

[0020] Step S1: AX and MnX2 are mixed to obtain a mixture A, and the mixture A is placed in a quartz tube and sealed under vacuum;

[0021] Step S2: The highest melting point of AX and MnX2 is recorded as B, and the mixture A encapsulated in the quartz tube in step S1 is calcined at a temperature higher than B, and then cooled to room temperature to obtain a metal halide with high-temperature luminescence characteristics.

[0022] Further, the halogen in AX is the same as or different from the halogen in MnX2. For example, NaBr and MnBr2, or NaBr and MnCl2. It is understood that whether the halogen in AX is the same as or different from the halogen in MnX2, it does not affect the 2+ The present invention should also include the doping of alkali metal halides.

[0023] Furthermore, the molar ratio of AX to MnX2 is (5-100):1.

[0024] As a further preference, the molar ratio of AX to MnX2 is (5-20):1.

[0025] An application, using the above-mentioned metal halide with high temperature luminescence characteristics, in one of the following fields:

[0026] Temperature-sensitive sensors (such as temperature sensors), temperature-sensitive optoelectronic devices, optical anti-counterfeiting materials, high-temperature lighting equipment (for applications such as metallurgy and chemical industry), environmental adaptive display (adaptive display from room temperature to 450°C), high-temperature environment monitoring and display equipment in extreme environments (industrial furnaces, high-temperature laboratories, etc.).

[0027] The above application scenarios are only examples. Any application that can achieve luminescent color changes under different temperature conditions and can maintain luminescent characteristics under high temperature conditions of 450°C belongs to the application scope of the metal halide with high-temperature luminescent characteristics described in the present invention and should be included.

[0028] The beneficial effects of the present invention are mainly reflected in: the present invention dopes Mn into the alkali metal halide matrix 2+ Forming metal halides with high temperature luminescence properties. 2+ Enter AX crystals to replace part of Na + Location, Mn 2+ As a high-temperature luminescence center, it presents a regular octahedral coordination structure and exhibits red light luminescence characteristics. 2+ When the doped AX metal halide is heated to 450°C, a unique phase transition occurs. Although the AX matrix itself does not undergo a phase transition at this temperature, the Mn 2+ The doped metal halide changes from the original octahedral coordination to tetrahedral coordination, showing yellow light emitting characteristics.

[0029] Therefore, the preparation method of the present invention not only changes the luminescent color from red light to yellow light, but also the metal halide can still maintain the luminescent ability at a high temperature of 450°C, thus breaking through the luminescent limitation of traditional metal halides at high temperatures. It should be emphasized that the present invention solves the thermal quenching phenomenon of the luminescent intensity of metal halides in a high temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a high-temperature in-situ PL image of the sample obtained in Example 1 of the present invention;

[0031] Figure 2 The in-situ PL images of the sample obtained in Example 1 of the present invention at 30°C and 450°C respectively;

[0032] Figure 3 The XRD test pattern of the sample obtained in Example 1 of the present invention;

[0033] Figure 4 for Figure 3 A partial enlarged schematic diagram of

[0034] Figure 5 This is a comparison chart of the fluorescence color changes of the samples and their raw materials obtained in Example 2 of the present invention as the temperature increases. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific implementation methods described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] Embodiment 1:

[0037] This embodiment provides a metal halide having high temperature luminescence characteristics, comprising the following steps:

[0038] Weigh 0.6174 g of NaBr and 0.1289 g of MnBr2 (molar ratio of 10:1) into a vacuum quartz tube and seal the tube (sealing pressure is 6E-4 Pa), then transfer it into a tube furnace for calcination at a temperature of 780 ° C and a calcination time of 30 min, and then gradually cool to room temperature.

[0039] Experimental analysis: Take the powder obtained after calcination as above and conduct the test. Figure 1-5 It can be seen that in the temperature range from room temperature to 120℃, Mn 2+ Enter NaBr crystal to replace part of Na + position, presenting a regular octahedral coordination structure, showing red light emission characteristics. In the temperature range of 120℃ to 330℃, some Mn 2+ Entering the lattice gap, Mn 2+The coordination environment is constantly changing, and Mn 2 + That is, it presents a regular octahedral coordination structure and a regular tetrahedral coordination structure. When the temperature is 330℃ to 450℃, Mn 2+ It changes to regular tetrahedral coordination, showing yellow light emission characteristics, and can still maintain luminescence ability at a high temperature of 450°C. In the cooling stage, when the yellow light is converted into red light, it changes from regular tetrahedral coordination to regular octahedral coordination.

[0040] And by Figure 1 It can be seen that in the temperature range of 120℃ to 330℃, the luminescence intensity of metal halide in the cooling stage is greater than the luminescence intensity of metal halide in the heating stage, resulting in significantly different luminescence characteristics in the heating stage and the cooling stage. This is because the heating stage is equivalent to a thermal annealing process to repair lattice defects, so the luminescence intensity in the cooling stage is stronger than that in the heating stage.

[0041] It should be pointed out that the metal halide of the present application also exhibits luminescence characteristics in the temperature range of 120° C. to 330° C. during the heating stage, but the luminescence is weaker rather than completely non-luminescent.

[0042] Depend on Figure 3 and Figure 4 It can be seen that as the temperature of the metal halide of the present invention increases (30°C to 450°C), Mn 2+ The coordination environment changes from regular octahedral coordination to regular tetrahedral coordination, the lattice stress increases, and the peak shifts to a smaller angle.

[0043] Embodiment 2:

[0044] The difference from Example 1 is that the components of the raw materials are adjusted as follows:

[0045] Weigh 0.1286 g of NaBr and 0.0537 g of MnBr2 (molar ratio of 5:1).

[0046] Experimental analysis: Figure 5 It can be seen that the NaBr matrix itself is non-luminescent, and MnBr2 also undergoes fluorescence thermal quenching when the temperature gradually rises to above 300°C. 2+ Enter NaBr crystal to replace part of Na + The metal halide of the present invention emits red light. And the luminescence ability is still maintained at a high temperature of 450°C, thereby solving the thermal quenching technical problem of the luminescence intensity of the metal halide in a high temperature environment.

[0047] Embodiment 3:

[0048] The difference from Example 1 is that the components of the raw materials are adjusted as follows:

[0049] Weigh 6.174g of NaBr and 0.1289g of MnBr2 (molar ratio is 100:1)

[0050] Embodiment 4:

[0051] The difference from Example 1 is that NaBr is replaced by NaF having the same molar amount.

[0052] Embodiment 5:

[0053] The difference from Example 1 is that NaBr is replaced by NaCl having the same molar amount.

[0054] Embodiment 6:

[0055] The difference from Example 1 is that NaBr is replaced by NaI having the same molar amount.

[0056] Embodiment 7:

[0057] The difference from Example 1 is that NaBr is replaced by KBr having the same molar amount.

[0058] Embodiment 8:

[0059] The difference from Example 1 is that NaBr is replaced by RbCl having the same molar amount.

[0060] Embodiment 9:

[0061] The difference from Example 1 is that NaBr is replaced by LiCl having the same molar amount.

[0062] Embodiment 10:

[0063] The difference from Example 1 is that NaBr is replaced by CsBr having the same molar amount.

[0064] Experimental analysis: The product of Example 2-10 exhibits red light emission characteristics in the range of room temperature to 120°C; and exhibits yellow light emission characteristics in the range of 330°C to 450°C. The red light emission characteristics and yellow light emission characteristics of the metal halide (product of Example 2-10) can be reversibly transformed to each other, and can spontaneously recover from yellow light to red light when the temperature is lowered, exhibiting thermal recovery characteristics.

[0065] Comparative Example 1:

[0066] This comparative example provides a metal halide having high temperature luminescence characteristics, comprising the following steps:

[0067] Weigh 0.6174 g of NaBr and 0.1289 g of MnBr2 (molar ratio of 10:1), mix and place in a tube furnace for calcination at a temperature of 780°C for 30 min, and then gradually cool to room temperature.

[0068] Experimental analysis: The powder obtained after the above calcination was tested and it was found that it did not have the ability to change the luminescent color with different temperatures, and the product could not continue to glow at a high temperature of 450°C.

[0069] The present invention illustrates the detailed preparation method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed preparation method, that is, it does not mean that the present invention must rely on the above-mentioned products and detailed preparation methods to be implemented. It should be clear to those skilled in the art that any improvement of the present invention, the combination or equivalent replacement of the raw materials of the product of the present invention, all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A metal halide having high temperature luminescence characteristics, characterized in that: The chemical formula of the metal halide is AX:Mn, wherein AX is an alkali metal halide, and Mn is a doped manganese ion present in the alkali metal halide; The metal halide exhibits red light emitting characteristics at low temperatures and yellow light emitting characteristics at high temperatures; The low temperature ranges from room temperature to 120°C; The high temperature ranges from 330°C to 450°C.

2. The metal halide with high temperature luminescence property according to claim 1, characterized in that: The doping concentration of the manganese ions is 1% to 20%.

3. The metal halide with high temperature luminescence property according to claim 1, characterized in that: The red light emitting characteristics and the yellow light emitting characteristics of the metal halide can be reversibly transformed to each other, and can spontaneously recover from yellow light to red light when the temperature decreases, showing a thermal recovery characteristic.

4. The metal halide with high temperature luminescence property according to claim 3, characterized in that: The metal halide has a regular octahedral coordination structure at a low temperature, and the metal halide has a regular tetrahedral coordination structure at a high temperature.

5. The metal halide with high temperature luminescence property according to claim 4, characterized in that: The regular octahedral coordination structure and the regular tetrahedral coordination structure can be reversibly transformed to each other, and can spontaneously recover from the regular tetrahedral coordination structure to the regular octahedral coordination structure when the temperature is lowered.

6. The metal halide with high temperature luminescence property according to claim 5, characterized in that: When the ambient temperature changes from low temperature to high temperature, the lattice tensile stress induced by manganese ions in the metal halide increases, and the increase in lattice tensile stress is determined by X-ray diffraction or electron diffraction.

7. The metal halide with high temperature luminescence property according to claim 1, characterized in that: In the AX, the alkali metal A is one or more of Li, Na, K, Rb, and Cs, and X is one or more of F, Cl, Br, and I.

8. A method for preparing a metal halide having high temperature luminescence characteristics according to any one of claims 1 to 7, characterized in that: The steps include: Step S1: AX and MnX2 are mixed to obtain a mixture A, and the mixture A is placed in a quartz tube and sealed under vacuum; Step S2: The highest melting point of AX and MnX2 is recorded as B, and the mixture A encapsulated in the quartz tube in step S1 is calcined at a temperature higher than B, and then cooled to room temperature to obtain a metal halide with high-temperature luminescence characteristics.

9. The metal halide with high temperature luminescence property according to claim 8, characterized in that: The halogen in AX is the same as or different from the halogen in MnX2; The molar ratio of AX to MnX2 is (5-100):

1.

10. An application, characterized in that: The metal halide with high temperature luminescence characteristics as claimed in any one of claims 1 to 7 is used in one of the following fields: Temperature-sensitive sensors, temperature-sensitive optoelectronic devices, optical anti-counterfeiting materials, high-temperature lighting equipment, environmentally adaptive displays, high-temperature environmental monitoring and display equipment for extreme environments.

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