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

Abstract

The application 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. 3+ The application takes A2GeO4 (A=Ca, Sr or Ba) material as a base body, adopts trivalent rare earth ion Tb + as an activator, and Li 2‑x‑ as a charge compensation agent to prepare the high-temperature green long-afterglow luminescent material A y GeO4:xTb 3+ ,yLi + (A=Ca, Sr or Ba, 0 3+ The application forms traps in the base body by doping Tb + and Li 3+ , captures carriers in the traps, adjusts the concentration of the carriers in the traps by changing the concentration of Tb + and Li , and makes the material have strong green afterglow and can last for a long time in a high-temperature environment. The green afterglow of the material which can be seen by naked eyes lays a foundation for practical application of the material in emergency lighting, information storage and other fields; and the high-temperature afterglow performance lays a foundation for application of the material in anti-forgery design, emergency signal display of deep mine and other fields.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of new inorganic functional materials, and particularly relates to a high-temperature green long afterglow luminescent material and a preparation method thereof. BACKGROUND

[0002] Long persistent luminescence material is a typical optical storage material, which can slowly release the stored energy under thermal stimulation and maintain luminescence for a period of time after the high-energy radiation is turned off. Its unique feature is that it can store part of the energy after being excited by light source irradiation and slowly release this part of energy in the form of light after the light source disappears. This material is named for its ability to continue to emit light in the dark and is widely used in night emergency indication, decoration and some special fields such as information processing and new energy. In 1996, Matsuzawa reported SrAl2O4:Eu 2+ ,Dy 3+ After that, the research on long afterglow luminescent material entered a new climax. In recent years, long afterglow materials have been applied to various fields of technology. And due to its characteristic of not needing continuous irradiation of light source, it has high sensitivity in biological imaging and is one of the research hotspot materials in current medical imaging technology.

[0003] Under normal circumstances, the defect level position of long afterglow material is relatively shallow, and the trapped electrons are easily released at room temperature. However, as the temperature of the external environment rises, the energy stored in the material is released at an accelerated rate, and the electrons trapped by these shallow traps have been emptied, which makes it impossible to maintain long afterglow emission in high temperature environment, resulting in serious deterioration of long afterglow performance. Therefore, most long afterglow luminescent materials are difficult to apply to high temperature environment, such as in vivo imaging, high temperature display, information storage and emergency signal display in deep mine. At present, researchers have developed some new long afterglow fluorescent powders for high temperature environment, such as CaSr2Al2O6:Tb 3+ ,Ca3Ga4O9:Tb 3+ / Zn 2+ ,SrGa2O4:Tb 3+ ,and Sr5SiO4Cl6:Eu 2 + ,Cr 3+ / Sc 3+ However, in high temperature environment, they mostly show high initial afterglow brightness, but the afterglow duration is relatively short. For example, CaSr2Al2O6:Tb 3+The LPL durations of the phosphor are 3390, 1390 and 128 s, which correspond to ambient temperatures of 323, 343 and 363 K, respectively. Up to now, the best material with long decay time at high temperature is LiGa5O8:Tb 3+ , which lasts for 10 h at 423 K. SUMMARY

[0004] The present application aims to provide a high-temperature green long afterglow luminescent material and a preparation method thereof. By taking A2GeO4 (A = Ca, Sr or Ba) material as a matrix, using trivalent rare earth ion Tb 3+ as an activator, and Li + as a charge compensation agent, a high-temperature green long afterglow luminescent material A 2-x-y GeO4:xTb 3+ ,yLi + (A = Ca, Sr or Ba, 0 < x ≤ 0.05, 0 < y ≤ 0.05) is prepared. 3+ The incorporated Tb + forms traps in the matrix to capture carriers; by changing the concentrations of Tb 3+ and Li + , the concentration of carriers inside the traps is adjusted to have strong green afterglow and can last for a long time in a high-temperature environment. The green afterglow of the material visible to the naked eye lays a foundation for its practical application in emergency lighting, information storage and other fields; and the high-temperature afterglow performance lays a foundation for its application in many fields such as anti-counterfeiting design and emergency rescue signal display in deep mines.

[0005] To achieve the above object, the present application provides the following technical scheme:

[0006] One of the technical schemes of the present application provides a high-temperature green long afterglow luminescent material, which has a chemical formula of A 2-x-y GeO4:xTb 3+ ,yLi + ; wherein A is Ca, Sr or Ba, 0 < x ≤ 0.05, and 0 < y ≤ 0.05.

[0007] The second technical scheme of the present application provides a preparation method of the above high-temperature green long afterglow luminescent material, which is prepared by a high-temperature solid-phase method.

[0008] Preferably, the specific steps of the high-temperature solid-phase method include: weighing carbonates of A elements and Li, oxides of Ge and Tb according to proportions, adding a dispersing liquid, grinding and mixing, pre-sintering under an oxygen condition, continuing to calcine the pre-sintering product under an oxygen condition after grinding, and obtaining the X-ray rapid charging ability fluorescent powder.

[0009] Preferably, the dispersion is anhydrous ethanol.

[0010] Preferably, the pre-sintering temperature is 800-900℃, and the time is 2-4h.

[0011] More preferably, the pre-sintering temperature is 800-900℃, and the time is 2-4h.

[0012] Preferably, the calcination temperature is 1300-1400℃, and the time is 4-6h.

[0013] More preferably, the calcination temperature is 1300-1400℃, and the time is 4-6h.

[0014] The third aspect of the present application provides an application of the high-temperature green long-afterglow luminescent material in the field of emergency lighting, information storage, anti-counterfeiting design or emergency signal display.

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

[0016] The high-temperature green long-afterglow luminescent material provided by the present application is prepared by a traditional high-temperature solid-phase method, and has the advantages of simple preparation process, easy control of conditions, low equipment requirement, low cost, no generation of toxic gas in the preparation process, and no pollution to the environment.

[0017] The high-temperature green long-afterglow luminescent material provided by the present application shows a green emission peak under the excitation of ultraviolet light, and the emission wavelengths are about 380nm, 418nm, 438nm, 488nm, 542nm, 586nm and 620nm, among which the emission peak at 542nm is the strongest, so the material shows green fluorescence.

[0018] The high-temperature green long-afterglow luminescent material provided by the present application can emit green afterglow visible to the naked eye in a dark environment after a short time of pre-excitation by ultraviolet light, and the afterglow time lasts for more than 10 hours.

[0019] The high-temperature green long-afterglow luminescent material provided by the present application can emit green afterglow visible to the naked eye in a dark environment after a short time of pre-excitation by ultraviolet light, and the afterglow time lasts for more than 10 hours. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

[0023] Figure 4 The afterglow decay curve at 542 nm of the high-temperature green long-persistence phosphor powders prepared in Example 10 measured at 300 K after excitation by 254 nm ultraviolet light for 3 minutes.

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

[0025] Various illustrative embodiments of the present application are now described in detail. While these embodiments are described in sufficient detail to enable one skilled in the art to practice the application, it should be understood that other embodiments can be employed and that logical, mechanical, electrical, and other changes can be made without departing from the scope of the present application. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present application is defined only by the appended claims.

[0026] Additionally, for numerical ranges that either are explicitly disclosed herein as being crucial to the invention or are implicit to the invention by virtue of the monomer units, oligomers, polymers, or compositions disclosed herein, it is intended that each intervening value, to the upper or lower limit of the range, is also specifically disclosed. In other words, each integer between the two endpoints, as well as each smaller range created by rounding up or down each end point individually to the

[0027] Unless otherwise indicated, all technical and scientific terms have the same meaning as those one of ordinary skill in the art of the application would understand. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described.

[0028] As used herein, the terms "comprise", "comprising", "include", "including", "have" and "having" and the like are open-ended, that is, meaning "including but not limited to".

[0029] The "room temperature" in the embodiments of the present application means 20±10℃, unless otherwise specified.

[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, analytical pure CaCO3, GeO2, Tb4O7 and Li2CO3 (CaCO3 and Li2CO3 are not added in Example 1, and Li2CO3 is not added in Examples 2-7) were weighed, 5 mL of anhydrous ethanol was added, and after grinding, the mixture was transferred to a crucible and placed in a muffle furnace. The temperature was raised to 800℃ at a rate of 5℃ / min under air, and after pre-burning for 2h, the furnace was naturally cooled to room temperature. The powder in the crucible was taken out, ground in an agate mortar, and then transferred to a crucible. The crucible was placed in a muffle furnace, and the temperature was raised to 1400℃ at a rate of 5℃ / min under air. After calcination for 4h, the furnace was naturally cooled to room temperature, and the powder in the crucible was taken out and ground in an agate mortar to obtain high-temperature green long-afterglow luminescent powder.

[0033] Table 1

[0034]

[0035]

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

[0037] Figure 1 CGO:Tb 3+ Also indicates the sample of Example 3.

[0038] The emission spectra of the high-temperature green long-afterglow luminescent powders prepared in Examples 2-12 after excitation with 278 nm ultraviolet light are shown in the figure. Figure 2 In the above, (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 of the high-temperature green long-afterglow luminescent powder prepared in Examples 2 to 7 at 542 nm after ultraviolet excitation, (c) is the afterglow emission spectrum of the high-temperature green long-afterglow luminescent powder prepared in Examples 3, 8 to 12, and (d) is the luminescence intensity of the high-temperature green long-afterglow luminescent powder prepared in Examples 3, 8 to 12 at 542 nm after ultraviolet excitation. Figure 2 The emission peaks of the material's emission spectrum after ultraviolet excitation are approximately at 380, 418, 438, 488, 542, 586, and 620 nm, appearing in green, representing Tb. 3+ The characteristic transition.

[0039] The afterglow emission spectra of the high-temperature green long-afterglow luminescent powders prepared in Examples 2-12, after being excited by 254nm ultraviolet light for 3 minutes, are shown in the figures. 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, 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, 8 to 12. Figure 3 The emission peaks of the afterglow spectrum are around 380, 418, 438, 488, 542, 586, and 620 nm, consistent with the emission spectrum, and are displayed in green, representing Tb. 3+ It exhibits characteristic transitions and strong afterglow emission intensity.

[0040] Figure 2 and Figure 3 0Li + This refers to the sample from Example 3.

[0041] The afterglow decay curve of the high-temperature green long-afterglow luminescent powder prepared in Example 10, after being excited by ultraviolet light for 3 min, was measured at 542 nm at 300 K. Figure 4 . Figure 4 The results show that the high-temperature green long afterglow luminescent powder prepared in Example 10 can maintain its afterglow decay time for more than 10 hours after being excited by ultraviolet light for 3 minutes.

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

[0043] The above-described examples only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art shall fall within the protection scope defined by the claims of the present application.

Claims

1. Application of a high-temperature green long-afterglow luminescent material in the field of long-afterglow luminescence, characterized in that, The chemical formula of the high-temperature green long-afterglow luminescent material is A 2-x-y GeO4:xTb 3+ ,yLi + ; wherein A is Ca, 0 2. The use of the high-temperature green long-afterglow luminescent material according to claim 1 in the field of long-afterglow luminescence, characterized in that, The high-temperature green long-afterglow luminescent material is prepared by a high-temperature solid-phase method.

3. The use of the high-temperature green long-afterglow luminescent material according to claim 2 in the field of long-afterglow luminescence, characterized in that, The specific steps of the high-temperature solid-phase method include: weighing A element and carbonates of Li, oxides of Ge and Tb according to proportions, adding a dispersion liquid, grinding and mixing, pre-sintering under an oxygen condition, continuing calcining the pre-sintered product under the oxygen condition after grinding, and obtaining the high-temperature green long-afterglow luminescent material.

4. The use of the high-temperature green long-afterglow luminescent material according to claim 3 in the field of long-afterglow luminescence, characterized in that, The dispersion liquid is anhydrous ethanol.

5. The use of the high-temperature green long-afterglow luminescent material according to claim 3 in the field of long-afterglow luminescence, characterized in that, The pre-sintering temperature is 800-900 DEG C, and the time is 2-4 h.

6. The use of the high-temperature green long-afterglow luminescent material according to claim 5 in the field of long-afterglow luminescence, characterized in that, The pre-sintering temperature increasing rate is 5-10 DEG C / min.

7. The use of the high-temperature green long-afterglow luminescent material according to claim 3 in the field of long-afterglow luminescence, characterized in that, The calcining temperature is 1300-1400 DEG C, and the time is 4-6 h.

8. The use of the high-temperature green long-afterglow luminescent material according to claim 7 in the field of long-afterglow luminescence, characterized in that, The calcining temperature increasing rate is 5-10 DEG C / min.

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