High-temperature green long-afterglow luminescent material and preparation method thereof

Abstract

The invention discloses a high-temperature green long-afterglow luminescent material and a preparation method thereof, and belongs to the technical field of novel inorganic functional materials. The high-temperature green long-afterglow luminescent material A2-x-yGeO4: xTb < 3 + >, yLi < + > (A = Ca, Sr or Ba, x is more than 0 and less than or equal to 0.05, and y is more than 0 and less than or equal to 0.05) is prepared by taking an A2GeO4 (A = Ca, Sr or Ba) material as a matrix, trivalent rare earth ions Tb < 3 + > as an activating agent and Li < + > as a charge compensation agent, and doped Tb < 3 + > and Li < + > form a trap in the matrix so as to capture carriers; the concentration of carriers in the trap is adjusted by changing the concentrations of Tb < 3 + > and Li < + >, so that the trap has strong green afterglow and can last for a long time in a high-temperature environment. The macroscopic green afterglow of the material lays a foundation for the practical application of the material in the fields of emergency lighting, information storage and the like; and the high-temperature afterglow performance lays a foundation for application in the fields of anti-counterfeiting design, emergency distress signal display of deep mines and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of novel inorganic functional materials, and in particular relates to a high-temperature green long afterglow luminescent material and a preparation method thereof. Background Art

[0002] Long persistent luminescence is a typical optical storage material that can slowly release stored energy under thermal stimulation and keep luminescent for a period of time after the high-energy radiation is turned off. Its unique feature is that it can store some energy after being excited by the light source and slowly release this energy in the form of light after the light source disappears. This material is named for its ability to continuously glow in the dark and is widely used in night emergency instructions, decoration, and some special fields such as information processing and new energy. In 1996, Matsuzawa reported SrAl 2 O 4 :Eu 2+ ,Dy 3+ After that, the research on long afterglow luminescent materials entered a new climax. Especially in recent years, long afterglow materials have been applied to various scientific and technological fields. And because of its characteristic of not requiring continuous irradiation of light source, it has high sensitivity in biological imaging and is one of the hot research materials in medical imaging technology.

[0003] Normally, the defect levels of long afterglow materials are relatively shallow, and the trapped electrons are easily released at room temperature. However, as the external environment temperature rises, the energy stored inside the material is released faster, and the electrons captured in these shallow traps have long been emptied, making it impossible to maintain long-term afterglow emission in a high-temperature environment, resulting in a serious deterioration in the long afterglow performance, making it difficult for most long afterglow luminescent materials to be used in high-temperature environments, such as in vivo imaging, high-temperature display, information storage, and emergency distress signal display in deep mines. At present, researchers have developed some new long afterglow phosphors for use in high-temperature environments, such as CaSr 2 Al 2 O 6 :Tb 3+ , Ca 3 Ga 4 O 9 :Tb 3+ / Zn 2+ , SrGa 2 O 4 :Tb 3+ , and Sr 5 SiO 4 Cl 6 :Eu 2 + ,Cr 3+ / Sc3+ However, in high temperature environments, most of them show high initial afterglow brightness, but the afterglow duration is relatively short. For example, CaSr 2 Al 2 O 6 :Tb 3+ The LPL durations of the phosphors are 3390, 1390, and 128 s, which correspond to ambient temperatures of 323, 343, and 363 K, respectively. So far, the best material with a long decay time at high temperatures is LiGa 5 O 8 :Tb 3+ , the duration is 10h at 423K. Summary of the invention

[0004] The object of the present invention is to provide a high temperature green long afterglow luminescent material and a preparation method thereof. 2 GeO 4 (A=Ca, Sr or Ba) material as the matrix, using trivalent rare earth ion Tb 3+ As activator, Li + As a charge compensator, high-temperature green long-lasting luminescent material A was prepared 2-x-y GeO 4 :xTb 3+ ,yLi + (A = Ca, Sr or Ba, 0 < x ≤ 0.05, 0 < y ≤ 0.05), where the doped Tb 3+ With Li + Form traps in the matrix to capture carriers; by changing Tb 3+ With Li + The concentration of carriers in the trap is adjusted by adjusting the concentration of the trap, so that it has a strong green afterglow, and it can last for a long time in a high temperature environment. The green afterglow visible to the naked eye of this material lays the foundation for its practical application in emergency lighting, information storage and other fields; the high temperature afterglow performance lays the foundation for its application in many fields such as anti-counterfeiting design and emergency distress signal display in deep mines.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a high temperature green long afterglow luminescent material, the chemical expression of which is: A 2-x-y GeO 4 :xTb 3+ ,yLi + ; Wherein, A is Ca, Sr or Ba, 0<x≤0.05, 0<y≤0.05.

[0007] The second technical solution of the present invention is to provide a method for preparing the above-mentioned high-temperature green long afterglow luminescent material by a high-temperature solid phase method.

[0008] Preferably, the specific steps of the high-temperature solid phase method preparation include: weighing the carbonate of element A and Li, the oxides of Ge and Tb in proportion, adding a dispersion, grinding and mixing, and pre-sintering under aerobic conditions, grinding the pre-sintered product and continuing to calcine under aerobic conditions to obtain the X-ray fast charging induced fluorescent powder.

[0009] Preferably, the dispersion liquid is anhydrous ethanol.

[0010] Preferably, the pre-firing temperature is 800-900° C. and the time is 2-4 hours.

[0011] More preferably, the heating rate of the pre-calcination is 5-10°C / min.

[0012] Preferably, the calcination temperature is 1300-1400° C. and the calcination time is 4-6 hours.

[0013] More preferably, the heating rate of the calcination is 5-10°C / min.

[0014] The third technical solution of the present invention is to provide an application of the above-mentioned high-temperature green long afterglow luminescent material in the fields of emergency lighting, information storage, anti-counterfeiting design or emergency distress signal display.

[0015] The beneficial technical effects of the present invention are as follows:

[0016] The high-temperature green long afterglow luminescent material provided by the present invention is prepared by a traditional high-temperature solid-phase method, and has a simple preparation process, easy control of conditions, low equipment requirements, and low cost. No toxic gas is generated during the preparation process, and there is no pollution to the environment.

[0017] The high-temperature green long afterglow luminescent material provided by the present invention shows emission peaks in the green region under the excitation of ultraviolet light, and its emission wavelengths are respectively around 380, 418, 438, 488, 542, 586 and 620 nm, among which the emission peak at 542 nm is the strongest, thus showing green fluorescence.

[0018] The high-temperature green long afterglow luminescent material provided by the present invention can emit a green afterglow visible to the naked eye in a dark environment after being pre-excited by ultraviolet rays for a short time and then the excitation source is turned off, and the afterglow lasts for more than 10 hours.

[0019] After the high-temperature green long afterglow luminescent material provided by the present invention is excited by ultraviolet light in a room temperature environment for a period of time, when the external environment temperature is gradually increased to 360K, the afterglow of the material is gradually enhanced and visible to the naked eye, and after decaying for 10 hours, the green afterglow signal can still be detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The XRD spectra of the high-temperature green long afterglow luminescent powder and calcium germanate prepared in Examples 1 to 12, wherein (a) is the XRD spectrum of the high-temperature green long afterglow luminescent powder and calcium germanate prepared in Examples 1 to 7, and (b) is the XRD spectrum of the high-temperature green long afterglow luminescent powder and calcium germanate prepared in Examples 3 and 8 to 12.

[0021] Figure 2 The emission spectra of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 12 are measured after being excited by 278nm ultraviolet light, wherein (a) is the emission spectrum of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 7, (b) is the luminescence intensity at 542nm of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 7 after ultraviolet excitation, (c) is the afterglow emission spectrum of the high-temperature green long afterglow luminescent powder prepared in Examples 3 and 8 to 12, and (d) is the luminescence intensity at 542nm of the high-temperature green long afterglow luminescent powder prepared in Examples 3 and 8 to 12 after ultraviolet excitation.

[0022] Figure 3 The afterglow emission spectra of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 12 are measured after being excited by 254nm ultraviolet light for 3 minutes, wherein (a) is the afterglow emission spectrum of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 7, (b) is the afterglow emission intensity at 542nm of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 7, (c) is the afterglow emission spectrum of the high-temperature green long afterglow luminescent powder prepared in Examples 3 and 8 to 12, and (d) is the afterglow emission intensity at 542nm of the high-temperature green long afterglow luminescent powder prepared in Examples 3 and 8 to 12.

[0023] Figure 4 The afterglow decay curve of the high-temperature green long afterglow luminescent powder prepared in Example 10 at 542 nm was measured at 300K after being excited by 254 nm ultraviolet light for 3 minutes.

[0024] Figure 5 The afterglow emission spectra (a) at different temperatures, the afterglow emission intensity at 542 nm (b) and the afterglow decay curve (c) at 542 nm at 360 K of the high-temperature green long afterglow luminescent powder prepared in Example 10 after being excited by 254 nm ultraviolet light for 3 minutes. DETAILED DESCRIPTION

[0025] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0026] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0027] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0028] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0029] Unless otherwise specified, the "room temperature" in the embodiments of the present invention refers to a temperature of 20±10°C.

[0030] Example 1

[0031] Preparation of high temperature green long afterglow luminescent powder:

[0032] According to the molar ratio of metal elements in Table 1, analytically pure CaCO 3 ,GeO 2 , Tb 4 O 7 and Li 2 CO 3 (Example 1 does not add CaCO 3 and Li 2 CO 3 , Examples 2 to 7 do not add Li 2 CO 3 ), add 5 mL of anhydrous ethanol, grind it thoroughly, transfer it to a crucible and put it into a muffle furnace, heat it to 800°C at 5°C / min in an air environment, pre-sinter it for 2 hours and then cool it naturally to room temperature with the furnace; take out the powder in the crucible, grind it thoroughly in an agate mortar, transfer it to a crucible, put it into a muffle furnace, heat it to 1400°C at 5°C / min in an air environment, calcine it for 4 hours and then cool it naturally to room temperature with the furnace, take out the powder in the crucible, grind it thoroughly in an agate mortar to obtain a high-temperature green long afterglow luminescent powder.

[0033] Table 1

[0034]

[0035]

[0036] The XRD spectra of the high temperature green long afterglow luminescent powder and calcium germanate prepared in Examples 1 to 12 are shown in Figure 1 , wherein (a) is the XRD spectrum of the high-temperature green long afterglow luminescent powder and calcium germanate prepared in Examples 1 to 7, and (b) is the XRD spectrum of the high-temperature green long afterglow luminescent powder and calcium germanate prepared in Examples 3, 8 to 12. Figure 1 It shows that the high-temperature green long afterglow luminescent powder prepared by the present invention is pure phase, and the doped ions do not disturb the crystal structure.

[0037] Figure 1 Chinese CGO:Tb 3+ Samples from Example 3 are also shown.

[0038] The emission spectra of the high temperature green long afterglow luminescent powder prepared in Examples 2 to 12 after being excited by 278nm ultraviolet light are shown in FIG. Figure 2 , wherein (a) is the emission spectrum of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 7, (b) is the luminescence intensity at 542 nm of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 7 after ultraviolet excitation, (c) is the afterglow emission spectrum of the high-temperature green long afterglow luminescent powder prepared in Examples 3 and 8 to 12, and (d) is the luminescence intensity at 542 nm of the high-temperature green long afterglow luminescent powder prepared in Examples 3 and 8 to 12 after ultraviolet excitation. Figure 2 It is shown that the emission peaks of the material emission spectrum after ultraviolet excitation are around 380, 418, 438, 488, 542, 586 and 620nm, showing green, which is Tb 3+ characteristic transition.

[0039] The afterglow emission spectra of the high temperature green long afterglow luminescent powder prepared in Examples 2 to 12 after being excited by 254nm ultraviolet light for 3 minutes are shown in FIG. Figure 3 , wherein (a) is the afterglow emission spectrum of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 7, (b) is the afterglow emission intensity at 542 nm of the high-temperature green long afterglow luminescent powder prepared in Examples 2 to 7, (c) is the afterglow emission spectrum of the high-temperature green long afterglow luminescent powder prepared in Examples 3 and 8 to 12, and (d) is the afterglow emission intensity at 542 nm of the high-temperature green long afterglow luminescent powder prepared in Examples 3 and 8 to 12. Figure 3The emission peaks of the afterglow spectrum are around 380, 418, 438, 488, 542, 586 and 620 nm, which is consistent with the emission spectrum and is displayed in green, indicating that Tb 3+ The characteristic transition of the ionization reaction is characterized by strong afterglow emission intensity.

[0040] Figure 2 and Figure 3 Medium + The sample of Example 3 is shown.

[0041] The afterglow attenuation curve of the high-temperature green long afterglow luminescent powder prepared in Example 10 at 542 nm measured at 300K after being excited by ultraviolet light for 3 minutes is shown in FIG. Figure 4 . Figure 4 It shows that the afterglow decay time of the high-temperature green long afterglow luminescent powder prepared in Example 10 can last for more than 10 hours after being excited by ultraviolet light for 3 minutes.

[0042] The afterglow emission spectra (a), afterglow emission intensity at 542 nm (b), and afterglow decay curve (c) at 542 nm at 360 K of the high temperature green long afterglow luminescent powder prepared in Example 10 after being excited by 254 nm ultraviolet light for 3 min at different temperatures are shown in Figure 10. Figure 5 . Figure 5 It shows that 3 minutes after ultraviolet excitation, when the external environment temperature reaches 360K, the afterglow emission is strongest and the afterglow decay time can last for more than 10 hours.

[0043] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A high-temperature green long afterglow luminescent material, characterized in that: The chemical expression of the high temperature green long afterglow luminescent material is: 2-x-y GeO4:xTb 3+ ,yLi + ; Wherein, A is Ca, Sr or Ba, 0<x≤0.05, 0<y≤0.

05.

2. A method for preparing the high-temperature green long afterglow luminescent material according to claim 1, characterized in that: Prepared by high temperature solid phase method.

3. The method for preparing a high temperature green long afterglow luminescent material according to claim 2, characterized in that: The specific steps of the high-temperature solid phase method preparation include: weighing the carbonate of element A and Li, the oxides of Ge and Tb in proportion, adding the dispersion, grinding and mixing, and pre-sintering under aerobic conditions, grinding the pre-sintered product and continuing to calcine under aerobic conditions to obtain the X-ray fast charging ability-induced fluorescent powder.

4. The method for preparing a high temperature green long afterglow luminescent material according to claim 3, characterized in that: The dispersion liquid is anhydrous ethanol.

5. The method for preparing a high temperature green long afterglow luminescent material according to claim 3, characterized in that: The pre-sintering temperature is 800-900° C. and the time is 2-4 hours.

6. The method for preparing a high temperature green long afterglow luminescent material according to claim 5, characterized in that: The heating rate of the pre-calcination is 5-10°C / min.

7. The method for preparing a high-temperature green long afterglow luminescent material according to claim 3, characterized in that: The calcination temperature is 1300-1400° C. and the calcination time is 4-6 hours.

8. The method for preparing a high temperature green long afterglow luminescent material according to claim 7, characterized in that: The heating rate of the calcination is 5-10°C / min.

9. Application of the high-temperature green long afterglow luminescent material according to claim 1 in the fields of emergency lighting, information storage, anti-counterfeiting design or emergency distress signal display.

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