Germanate-based long-afterglow luminescent material, preparation method and use thereof

Abstract

This invention belongs to the field of inorganic luminescent materials technology, and discloses a germanate-based long afterglow luminescent material, its preparation method, and its uses. This luminescent material uses MReGeO4 (M = Li or Na, Re = Y, Lu or Gd) as a matrix, and introduces Bi dopant ions. 3+ and Ln 3+ Obtained; and the chemical formula of the luminescent material is M 1‑x Re 1‑y GeO4:xBi 3+ ,yLn 3+ Where x is the dopant ion Bi 3+ The proportion of alkali metal ions Li in the matrix + Or Na + The molar doping concentration is given by , and 0 < x ≤ 0.010; y is the molar doping concentration of Ln. 3+ The proportion of ions (Ln = one of Eu, Tb, Pr or Yb) in the Re content of the matrix 3+ The molar doping concentration is such that 0 ≤ y ≤ 0.001. Based on trap engineering and bandgap engineering, this invention achieves the modulation of multimode fluorescence properties such as photoluminescence, afterglow, and photo / thermal excited fluorescence. In particular, it realizes dynamic information storage and encryption of multicolor multimode fluorescent printing, providing a material basis and physical prototype for next-generation fluorescent printing information storage and anti-counterfeiting technology.

Description

Technical Field

[0001] This invention belongs to the field of inorganic luminescent materials technology, specifically relating to a deep-trap germanate-based long-afterglow luminescent material for information storage and encryption, its preparation method, and its uses. Background Technology

[0002] According to the "DATA.AGE 2025" report, global data is projected to reach 163 ZB by 2025, exceeding 20,000 GB per capita. However, traditional hybrid hard drive storage technologies face an information storage crisis due to their limitations in two-dimensional spatial resolution and high energy consumption. Therefore, there is an urgent need for new storage materials and technologies with high capacity and non-volatile storage capabilities. Storage phosphors with photo / thermal excited fluorescence (PSL / TSL) are considered the most promising fourth-generation optical information storage materials due to their ultra-fast speed and low energy consumption. Information can be rapidly written under high-energy radiation (such as X-rays or ultraviolet light) and then retrieved under thermal / optical excitation, completing the information storage and retrieval process. As a representative example, BaFBr:Eu 2+ Photoexcited phosphors have been successfully used as imaging plates in computed tomography (CT) X-rays. Furthermore, to further improve the optical information storage capacity of afterglow materials, researchers have developed several typical strategies based on photon multiplexing technology, such as wavelength multiplexing, intensity multiplexing, polarization multiplexing, and spacer and multilayer multiplexing techniques. Although some progress has been made, the excitation fluorescence intensity has not yet reached the threshold for information storage applications. In particular, the stored energy dissipates naturally over time in the form of afterglow, directly affecting the signal storage lifetime and the resolution of the extracted signal. The key reason is the lack of control over the trapped states. The development of new long-afterglow materials with new properties is still ongoing through trial and error.

[0003] To date, co-doping is widely recognized as the most effective method for improving trap density and distribution. A landmark work is the development of a schematic model based on vacuum or matrix binding energy (VRBE) to predict the trap depth of lanthanide dopant ions in the matrix, used to explain the positions of luminescent and trap centers within the band gap in lanthanide-doped inorganic compounds. This model allows for comparison of defect energy levels within the matrix band gap in different matrices at the same reference energy. This model can guide the selection of the type and nature of dopant ions as defects in the matrix.

[0004] Having (Xe)4f 14 5d 10 6s 2 6p 1 Bi configuration 3+Bismuth ions are excellent activators and sensitizers for luminescent materials. Reports on the afterglow luminescence phenomenon of bismuth are scarce; to date, only a few Bi... 3+ Doped afterglow phosphors have been discovered. Few reports discuss Bi. 3+ The mechanism of charge carrier capture and release in doped phosphors has remained an open question, directly hindering the development of highly efficient afterglow materials. It has been reported that in the green long afterglow material Y3Al... 5-x Ga x O 12 0.005Ce 3+ 0.005Bi 3+ Medium, Bi 3+ As an electronic trap. And in recent research reports, Bi... 3+ In NaLuGeO4:0.05Bi 3+ 0.005Cr 3+ In long afterglow materials, Bi 3+ As the center of a hole trap. Therefore, it can be inferred that Bi 3+ As electron or hole traps are related to the localized matrix environment, this provides a new approach for trap modulation. Based on this, in order to further increase trap density and distribution, and thus increase the storage capacity of multicolor and multimode fluorescence information, this invention aims to provide a novel long-afterglow luminescent material. Summary of the Invention

[0005] Addressing the problem of insufficient information storage capacity in afterglow materials, this invention designs and constructs a Bi based on trap engineering and bandgap engineering. 3+ and Ln 3+ This invention utilizes an electron-hole pair trap structure to enrich and deepen the traps, providing a high-density deep-trap germanate-based long-afterglow luminescent material for information storage and encryption, along with its preparation method. By regulating the energy storage traps in the long-afterglow material and enabling both the conduction and valence bands to participate in long-range carrier transport, this invention significantly improves the storage capacity of encrypted information, possessing not only theoretical significance but also economic and social value.

[0006] To achieve the above-mentioned technical objectives, the specific technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a germanate-based long afterglow luminescent material, wherein the luminescent material is based on MReGeO4 and doped with Bi ions. 3+ and Ln 3+ The luminescent material was obtained, and the chemical formula of the luminescent material is M. 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ ;

[0008] Where M is Li or Na, Re is Y, Lu or Gd, and Ln is one of Eu, Tb, Pr or Yb; 0 < x ≤ 0.010, 0 ≤ y ≤ 0.001.

[0009] In a second aspect, the present invention provides a method for preparing the luminescent material, comprising the following steps:

[0010] According to the chemical formula M of the luminescent material 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ In accordance with stoichiometry, M source, Re source, Ge source, O source, Bi source, and Ln source are weighed, mixed, and calcined to obtain the luminescent material. The M source is either Na or Li, and the Re source is one of Lu, Y, or Gd.

[0011] Preferably, the M source, Re source, Ge source, Bi source, and Ln source are all oxygen-containing compounds containing the corresponding elements;

[0012] The O source is provided by the oxygen-containing compounds.

[0013] Preferably, the oxygen-containing compound is any one or more of an oxide or a nitrate.

[0014] Preferably, the calcination is carried out in an air atmosphere, with the temperature increased to 1300-1400°C at a heating rate of 2-4°C / min, and calcined for 8-10 hours. Preferably, the raw materials are ground for 0.5-1 hours during mixing.

[0015] In a third aspect, the present invention provides the use of the luminescent material as a material for information storage or encryption.

[0016] Preferably, the luminescent material is used for multidimensional visualization information storage or encryption.

[0017] Preferably, the information storage or encryption is achieved by writing information through ultraviolet light irradiation.

[0018] Preferably, the information storage or encryption is achieved by controlling the exposure to light or heat again at a specific time frame after ultraviolet pre-irradiation.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. This invention selects germanate as the matrix, which can provide three different cation sites, Bi 3+ Having the same properties as Na + Similar radii and Lu 3+ Similar valence states allow it to function as both a luminescent center and an electron / hole defect center. A typical Ln... 3+(Ln = Eu, Tb, Pr, or Yb) as Bi 3+ A series of electron-hole defect pairs M0 with enhanced trap density and controllable afterglow emission were successfully synthesized by pairing electron / hole defects with hole / electron defects. 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ Afterglow phosphor. This invention is based on the construction of Bi... 3+ -Ln 3+ Electron-hole defect pairs enable both the conduction band and valence band to participate simultaneously in long-range carrier transport processes, improving M... 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ The effective trap density and afterglow properties of the afterglow phosphor successfully enabled storage and encryption.

[0021] 2. This invention is based on the afterglow fluorescence mechanism of carrier capture and release mediated by electron-hole defects, utilizing Bi 3+ and Ln 3+ Simultaneously serving as a trap maker and fluorescence center, the synthesized long-afterglow luminescent material exhibits tunable afterglow emission, excellent multicolor and multimode afterglow, and can meet specific requirements.

[0022] 3. The Ln provided by this invention 3+ Co-doped M 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ The phosphor not only significantly increased the trap density but also modulated the trap distribution, making M... 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ Phosphors are more suitable for information storage and encryption. Furthermore, by controlling the UV pre-irradiation temperature, multi-dimensional visual information storage was achieved on a single-layer phosphor film.

[0023] 4. This invention proposes a multi-level trap multiplexing storage for different optical data recording and encryption. By storing multiple individual seekable addresses in the same fluorescent recording layer, a dynamic encryption pattern provides a new idea and technical prototype for the design and preparation of next-generation optical information storage and encryption materials. Attached Figure Description

[0024] Figure 1 The XRD patterns and standard data of the phosphors in Examples 1 and 5 are shown in PDF#02-3479.

[0025] Figure 2This is a schematic diagram of the [MO6] and [LuO6] octahedrons in Comparative Example 1;

[0026] Figure 3 These are SEM images and elemental mapping diagrams of the phosphor in Example 1, the crystal structure of the unit cell, and Bi. 3+ Ions and Ln 3+ Comparison of ion substitution coordination environments;

[0027] Figure 4 This is a comparison of the thermoelectric spectra of the phosphors in Examples 1-5;

[0028] Figure 5 The pyroelectric spectra (A) of the phosphors in Examples 9-11 and the pyroelectric curves (B) of the phosphors in Examples 12-14 are shown.

[0029] Figure 6 These are the phosphor pyrolysis spectra of Examples 6-8;

[0030] Figure 7 The photoluminescence excitation spectrum (A), emission spectrum (B), afterglow emission spectrum (C), and afterglow decay curve (D) of the phosphors in Examples 1-5 are shown.

[0031] Figure 8 This is the temperature-dependent afterglow emission spectrum of the phosphor in Example 1;

[0032] Figure 9 This is the temperature-dependent pyrolysis curve of the phosphor in Example 1;

[0033] Figure 10 This is the time-delayed pyrolysis curve of the phosphor in Example 1;

[0034] Figure 11 These are the temperature-dependent pyrolysis curves of the phosphors in Examples 2(A), 3(B), and 4(C);

[0035] Figure 12 The natural decay curves of the phosphors in Examples 1, 2(A), 3(B), and 4(C) show the alternating excitation fluorescence and excitation afterglow fluorescence under pulsed infrared laser excitation.

[0036] Figure 13 These are the photoluminescence excitation spectrum and afterglow excitation spectrum of the phosphor in Example 1;

[0037] Figure 14 Bi is the phosphor of Examples 1(A) and 5(B). 3+ :4f high-resolution XPS spectrum;

[0038] Figure 15 The PL, PersL, TSL, and PSL mechanisms of Bi-Ln electron-hole pair trapping materials under ultraviolet light irradiation;

[0039] Figure 16 The "Butterfly and Flower" pattern printed with phosphors from Examples 1-4 is used for information storage and encryption. a) Structural diagram of the phosphor "Butterfly and Flower" pattern; b) Photoluminescent multicolor pattern under selective excitation from ultraviolet to blue light sources; c) Dynamic encryption pattern with afterglow after charging with 254nm ultraviolet light for different delay times; d) Photoexcitation pattern information extracted under 980nm or 808nm near-infrared laser excitation within a certain time frame after the afterglow disappears after ultraviolet light charging; e) Thermally excited multicolor fluorescent pattern information extracted under different thermal assistance; f) Accessing different information by switching different depth traps through temperature control. The specific access process is described as follows: under thermal assistance at 130℃, only deep traps are selected for filling; under thermal assistance at 100℃, deep traps and intermediate depth traps are selected for filling; and all traps are filled at room temperature. By combining the different trap distributions of four phosphor materials, butterflies were read out at room temperature, butterflies and leaves were read out under temperature excitation at 80℃ (353K), and finally, butterflies, leaves, and roses were read out at 150℃ (423K), realizing the storage of multidimensional information in a single physical phosphor recording layer. The butterfly was charged at T... charge =RT, leaves at T charge =353K, Rose T charge =423K.

[0040] Figure 17 The multimodal images of the "flower" pattern printed using the phosphor in Example 6 are used for information storage and encryption; a) Flower pattern under sunlight; b) PL image obtained under 236nm ultraviolet light irradiation, with pure blue and pure red images obtained with the assistance of filters; c) PersL images after charging with 236nm ultraviolet light for different delay times; d) PSL images under irradiation with 980nm or 808nm near-infrared laser (0.6W); e) TSL image under pre-irradiation at 236nm; f) Multidimensional information stored in a single recording layer by temperature control; the above information was written under 236nm ultraviolet lamp irradiation at different temperatures, wherein the leaf at T charge =RT, Little Flower in T charge =353K, big spend in T charge =423K. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0042] This invention provides a deep-trap long-afterglow luminescent material, which uses MReGeO4 as a matrix and introduces doped ions Bi and Ln. 3+ The luminescent material was obtained, and its chemical formula is M. 1-x Re 1-y GeO4:xBi3+ ,yLn 3+ ;

[0043] Where M is Li or Na, Re is Y, Lu or Gd, and Ln is one of Eu, Tb, Pr or Yb;

[0044] x represents the doped ion Bi. 3+ M 1-x Re 1-y The molar doping concentration of Na in GeO4, where 0 < x ≤ 0.010; y is the molar doping concentration of the dopant ion Ln. 3+ Occupy that 1-x Lu 1-y The molar doping concentration of Re in GeO4, where 0 ≤ y ≤ 0.001.

[0045] The method for preparing the luminescent material provided by this invention is as follows:

[0046] According to the chemical formula M of the luminescent material 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ The stoichiometric ratios are used to weigh out the corresponding masses of each preparation raw material, namely Na / Li source, Re source, Ge source, O source, Bi source, and Ln source; the Re source is one of Lu source, Y source, or Gd source;

[0047] After weighing out the Na / Li source, Re source, Ge source, O source and doped ion Bi source and Ln source, mix them thoroughly and grind them evenly to obtain a mixed powder.

[0048] The mixed powder is calcined in air at 1000–1300°C and then ground into powder to obtain a luminescent material.

[0049] It should be noted that, in order to avoid introducing other elements and impurities, the preferred Na / Li source, Re source, Ge source, and doped ion Bi source and Ln source are all oxygen-containing compounds containing the corresponding elements; the O source is provided by various oxygen-containing compounds containing the corresponding elements. The oxygen-containing compounds are any one or more of oxides, carbonates, and nitrates.

[0050] Taking into account factors such as minimizing the introduction of impurities, good chemical stability, and moderate price, this invention more preferably uses Na2CO3 as the Na source, rare earth oxides as the Re source, and GeO2 as the Ge source.

[0051] This invention achieves the regulation of fluorescence properties of luminescent materials by controlling the type of dopant ion Ln and the molar doping concentration of Ln ion relative to Re in the germanic acid matrix. It realizes the regulation of fluorescence properties such as photoluminescence, afterglow, and thermally excited fluorescence. In particular, it realizes the anomalous thermal quenching phenomenon and thermal compressibility trap filling phenomenon of the prepared phosphor, realizing high-capacity information writing and multi-level information reading, providing a material basis and technical solution for fourth-generation optical information storage.

[0052] In order to ensure that the raw materials are fully mixed, the present invention preferably uses ball milling or hand milling to mix the raw materials, and the milling time is about 0.5 to 1 hour. The resulting mixed powder is fine and has a size of 1 to 2 μm.

[0053] The present invention employs direct calcination to calcine the above-mentioned mixed powder, and calcining it in an air atmosphere at 1000-1300℃ for 4-8 hours, with a heating rate of 2-4℃ / min during calcination to ensure that the material is fully and uniformly heated, thereby achieving the optimal degree of crystallinity.

[0054] Example 1

[0055] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Lu, Ln is Eu, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Eu 3+ And its preparation method is as follows:

[0056] Weigh out 0.0732g Li₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Eu₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Eu 3+ Luminescent materials.

[0057] Example 2

[0058] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Lu, Ln is Tb, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Tb 3+ And its preparation method is as follows:

[0059] Weigh out 0.0732g Li₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Tb₄O₇ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Tb 3+ Luminescent materials.

[0060] Example 3

[0061] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Lu, Ln is Pr, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Pr 3+ And its preparation method is as follows:

[0062] Weigh out 0.0732g Li₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Pr₆O₃ according to the molar mass ratios of the above chemical formulas. 11 The solid mixture was thoroughly ground in an agate mortar for 1 hour to obtain a mixed powder. The mixed powder was then placed in a crucible and heated to 1250°C in air at a rate of 2°C / min. After calcination at 1250°C for 6 hours, it was thoroughly ground again to obtain the product with the molecular formula Li. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Pr 3+ Luminescent materials.

[0063] Example 4

[0064] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Lu, Ln is Yb, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Yb 3+ And its preparation method is as follows:

[0065] Weigh out 0.0732g Li₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Yb₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Yb 3+ Luminescent materials.

[0066] Example 5

[0067] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Lu, and x is 1.0%. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 LuGeO4: 1.0% Bi 3+ And its preparation method is as follows:

[0068] Weigh out 0.0732g Li₂CO₃, 0.3979g Lu₂O₃, 0.2133g GeO₂, and 0.0047g Bi₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 LuGeO4: 1.0% Bi 3+ Luminescent materials.

[0069] Example 6

[0070] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Na, Re is Lu, Ln is Eu, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Na. 0.99 Lu 0.999GeO4: 1.0% Bi 3+ 0.1% Eu 3+ And its preparation method is as follows:

[0071] Weigh out 0.1049g Na₂CO₃, 0.3979g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Eu₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250°C in air at a heating rate of 2°C / min. Firing it at 1250°C for 6 hours and then thoroughly grinding it yields the product with the molecular formula Na. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Eu 3+ Luminescent materials.

[0072] Example 7

[0073] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Na, Re is Lu, Ln is Tb, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Na. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Tb 3+ And its preparation method is as follows:

[0074] Weigh out 0.1049g Na₂CO₃, 0.3979g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Tb₄O₇ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250°C in air at a heating rate of 2°C / min. Firing it at 1250°C for 6 hours and then thoroughly grinding it yields the product with the molecular formula Na. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Tb 3+ Luminescent materials.

[0075] Example 8

[0076] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Na, Re is Lu, and x is 1.0%. Therefore, the molecular formula of the luminescent material in this embodiment is Na. 0.99 LuGeO4: 1.0% Bi 3+ And its preparation method is as follows:

[0077] According to the molar mass ratio of the above chemical formulas, 0.1049 g of Na₂CO₃, 0.3979 g of Lu₂O₃, 0.2133 g of GeO₂, and 0.0047 g of Bi₂O₃ solids were weighed and mixed. The mixture was then ground in an agate mortar for 1 hour to obtain a mixed powder. This mixed powder was placed in a crucible and heated to 1250 °C in air at a heating rate of 2 °C / min. After calcining at 1250 °C for 6 hours, it was ground into powder to obtain Na₂CO₃. 0.99 LuGeO4: 1.0% Bi 3+ Luminescent materials.

[0078] Example 9

[0079] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Y, Ln is Eu, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 Y 0.999 GeO4: 1.0% Bi 3 + 0.1% Eu 3+ And its preparation method is as follows:

[0080] Weigh out 0.0732g Li₂CO₃, 0.2256g Y₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Eu₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 Y 0.999 GeO4: 1.0% Bi 3+ 0.1% Eu 3+ Luminescent materials.

[0081] Example 10

[0082] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Y, Ln is Tb, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 Y 0.999 GeO4: 1.0% Bi 3 + 0.1% Tb 3+ And its preparation method is as follows:

[0083] Weigh out 0.0732g Li₂CO₃, 0.2256g Y₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Tb₄O₇ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 Y 0.999 GeO4: 1.0% Bi 3+ 0.1% Tb 3+ Luminescent materials.

[0084] Example 11

[0085] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Y, and x is 1.0%. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 YGeO4: 1.0% Bi 3+ And its preparation method is as follows:

[0086] Weigh out 0.0732g Li₂CO₃, 0.2258g Y₂O₃, 0.2133g GeO₂, and 0.0047g Bi₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 YGeO4: 1.0% Bi 3+ Luminescent materials.

[0087] Example 12

[0088] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Gd, Ln is Eu, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 Gd 0.999 GeO4: 1.0% Bi 3+ 0.1% Eu 3+ And its preparation method is as follows:

[0089] Weigh out 0.0732g Li₂CO₃, 0.3623g Gd₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Eu₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 Gd 0.999 GeO4: 1.0% Bi 3+ 0.1% Eu 3+ Luminescent materials.

[0090] Example 13

[0091] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Gd, Ln is Tb, and x and y are 1.0% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 Gd 0.999 GeO4: 1.0% Bi 3+ 0.1% Tb 3+ And its preparation method is as follows:

[0092] Weigh out 0.0732g Li₂CO₃, 0.3623g Gd₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Tb₄O₇ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 Gd 0.999 GeO4: 1.0% Bi 3+ 0.1% Tb 3+ Luminescent materials.

[0093] Example 14

[0094] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Gd, and x is 1.0%. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 GdGeO4:1.0%Bi 3+ And its preparation method is as follows:

[0095] Weigh out 0.0732g Li₂CO₃, 0.3626g Gd₂O₃, 0.2133g GeO₂, and 0.0047g Bi₂O₃ solids according to the molar mass ratio of the above chemical formula, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 GdGeO4:1.0%Bi 3+ Luminescent materials.

[0096] Example 15

[0097] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Lu, Ln is Eu, and x and y are 0.1% and 0.1%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.999 Lu 0.999 GeO4: 0.1% Bi 3+ 0.1% Eu 3+ And its preparation method is as follows:

[0098] Weigh out 0.0732g Li₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Eu₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.999 Lu 0.999 GeO4: 0.1% Bi 3+ 0.1% Eu 3+ Luminescent materials.

[0099] Example 16

[0100] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Lu, Ln is Eu, and x and y are 0.1% and 0.01%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.999 Lu 0.9999 GeO4: 0.1% Bi 3+ 0.01% Eu 3+ And its preparation method is as follows:

[0101] Weigh out 0.0732g Li₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Eu₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.999 Lu 0.9999 GeO4: 0.1% Bi 3+ 0.01% Eu 3+ Luminescent materials.

[0102] Example 17

[0103] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Lu, Ln is Eu, and x and y are 1.0% and 0.01%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.99 Lu 0.9999 GeO4: 1.0% Bi 3+ 0.01% Eu 3+ And its preparation method is as follows:

[0104] Weigh out 0.0732g Li₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Eu₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.99 Lu 0.9999 GeO4: 1.0% Bi 3+ 0.01% Eu 3+ Luminescent materials.

[0105] Example 18

[0106] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Li, Re is Lu, Ln is Eu, and x and y are 0.5% and 0.05%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Li. 0.995 Lu 0.9995 GeO4: 0.5% Bi 3+ 0.05% Eu 3+ And its preparation method is as follows:

[0107] Weigh out 0.0732g Li₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Eu₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250℃ in air at a heating rate of 2℃ / min. Firing it at 1250℃ for 6 hours and then thoroughly grinding it yields the product with the molecular formula Li. 0.995 Lu 0.9995 GeO4: 0.5% Bi 3+ 0.05% Eu 3+ Luminescent materials.

[0108] Example 19

[0109] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Na, Re is Lu, Ln is Eu, and x and y are 0.5% and 0.05%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Na. 0.995 Lu 0.9995 GeO4: 0.5% Bi 3+ 0.05% Eu 3+ And its preparation method is as follows:

[0110] Weigh out 0.0732g Na₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Eu₂O₃ solids according to the molar mass ratio of the above chemical formulas, mix them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250°C in air at a heating rate of 2°C / min. Firing it at 1250°C for 6 hours and then thoroughly grinding it yields the product with the molecular formula Na. 0.995 Lu 0.9995 GeO4: 0.5% Bi 3+ 0.05% Eu 3+ Luminescent materials.

[0111] Example 20

[0112] This embodiment provides a germanate-based long afterglow luminescent material. In this embodiment, M is Na, Re is Lu, Ln is Pr, and x and y are 0.5% and 0.05%, respectively. Therefore, the molecular formula of the luminescent material in this embodiment is Na. 0.995 Lu 0.9995 GeO4: 0.5% Bi 3+ 0.05% Pr 3+ And its preparation method is as follows:

[0113] Weigh out 0.0732g Na₂CO₃, 0.3975g Lu₂O₃, 0.2133g GeO₂, 0.0047g Bi₂O₃, and 0.0004g Pr₆O₃ according to the molar mass ratios of the above chemical formulas. 11 The solid mixture was thoroughly ground in an agate mortar for 1 hour to obtain a mixed powder. The mixed powder was then placed in a crucible and heated to 1250°C in air at a rate of 2°C / min. After calcination at 1250°C for 6 hours, it was thoroughly ground again to obtain the product with the molecular formula Na. 0.995 Lu 0.9995 GeO4: 0.5% Bi 3+ 0.05% Pr 3+ Luminescent materials.

[0114] Comparative Example 1

[0115] A luminescent material for information storage, wherein M is Li, Re is Lu, and the molecular formula of the luminescent material is LiLuGeO4. Its preparation method is as follows:

[0116] Weigh 0.0739g of Li2CO3, 0.3979g of Lu2O3, and 0.2133g of GeO2 solids according to the molar mass ratio of the above chemical formula, mix them, and grind them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250°C in air at a heating rate of 2°C / min. After calcining at 1250°C for 6 hours, grind it thoroughly to obtain a luminescent material with the molecular formula LiLuGeO4.

[0117] Comparative Example 2

[0118] A luminescent material for information storage, using Na as M and Lu as Re, has the molecular formula NaLuGeO4. Its preparation method is as follows:

[0119] According to the above chemical formula, 0.1061g of Na2CO3, 0.3979g of Lu2O3 and 0.2133g of GeO2 solids were weighed and mixed. The mixture was then ground in an agate mortar for 1 hour to obtain a mixed powder. The mixed powder was placed in a crucible and heated to 1250°C in air at a heating rate of 2°C / min. After calcining at 1250°C for 6 hours, it was ground into powder to obtain NaLuGeO4 luminescent material.

[0120] Comparative Example 3

[0121] A luminescent material for information storage, wherein M is Li, Re is Y, and the molecular formula of the luminescent material is LiYGeO4. Its preparation method is as follows:

[0122] Weigh 0.0739g of Li2CO3, 0.2258g of Y2O3, and 0.2133g of GeO2 solids according to the above chemical formula molar mass ratio, mix them, and grind them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250°C in air at a heating rate of 2°C / min. After calcining at 1250°C for 6 hours, grind it thoroughly to obtain a luminescent material with the molecular formula LiYGeO4.

[0123] Comparative Example 4

[0124] A luminescent material for information storage, wherein M is Li, Re is Gd, and the molecular formula of the luminescent material is LiGdGeO4. Its preparation method is as follows:

[0125] Weigh 0.0739g of Li2CO3, 0.3626g of Gd2O3, and 0.2133g of GeO2 solids according to the above chemical formula molar mass ratio, mix them, and grind them thoroughly in an agate mortar for 1 hour to obtain a mixed powder. Place the mixed powder in a crucible and heat it to 1250°C in air at a heating rate of 2°C / min. After calcining at 1250°C for 6 hours, grind it thoroughly to obtain a luminescent material with the molecular formula LiGdGeO4.

[0126] Since the performance of the phosphors prepared in Examples 15-20 is similar to that in Examples 1-14, such as the performance of the phosphors prepared in Examples 15-18 being similar to that of the phosphors provided in Example 1, and the performance of the phosphors prepared in Examples 19-20 being similar to that of the phosphors prepared in Example 6, the following description will only use the phosphors provided in Examples 1-14 as examples.

[0127] (I) Structural Analysis

[0128] Example 1: Standard X-ray diffraction (XRD) data of the phosphor (marked as PDF#02-3479) are shown in... Figure 1 In the middle. All diffraction peaks of the luminescent materials provided in Examples 1 and 5 (synthesized in the middle). Figure 1 This is consistent with the standard data in PDF#02-3479, indicating that Bi 3+ and Ln 3+ When doped into the matrix, it has no significant impact on the matrix structure. Figure 2 The crystal structure of Comparative Example 1 is given. LiLuGeO4 belongs to the orthorhombic crystal system with space group Pnma(62), and M is clearly present. + and Re 3+ Two six-coordinate sites ( Figure 2 As is well known, ionic radius and valence play a very important role in para-substitution. In this case, The ionic radius of CN=6 is closer to that of rare earth ions than the doping element in the example. The radius of CN=6). Therefore, the dopant element Bi in Examples 1-20 3+ Occupy M + Grid. According to the Hume-Rother rule, Ln 3+ and Bi 3+ The difference in ionic radii between them exceeds a threshold of 15%. Therefore, we prefer Bi. 3+ Ions occupy M + Site. However, considering valence, Bi cannot be ruled out. 3+ For Lu 3+ The replacement of Ln 3+ Ions undoubtedly occupy Re 3+ The lattice of a polyhedron.

[0129] The surface morphology and size of the particles can affect the afterglow performance of the luminescent material to some extent. The SEM and elemental mapping of Example 1 are shown in... Figure 3 The elemental mapping diagram shows that Li, Lu, Ge, O, Bi, and Eu elements are uniformly distributed in the sample.

[0130] (II) Fluorescence Performance Analysis

[0131] Based on trap engineering, we first consider two typical Ln 3+ Ions, including Eu, which often acts as an electron trap 3+ Yb 3+ And Tb, which often acts as a hole trap 3+ Pr 3+ Introduced into M 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ In luminescent materials, this is used to adjust the trap distribution and fluorescence properties. Figure 4 The pyroelectric curves of the phosphor samples from Examples 1–5 are shown. Among these phosphors, Example 1 exhibits the largest pyroelectric peak intensity, and the integral intensity (representing trap density) is 2–20 times that of the other samples, suggesting that the phosphor of Example 1 has the largest information storage capacity. (Except for Eu...) 3+ Doping greatly increases the trap density and depth, Yb 3+ Doping also increases the trap density. However, doping with Tb and Pr decreases the trap density. These experimental results suggest that Bi... 3+ Perhaps more preferred as a hole trap and Eu 3+ / Yb 3+ As an electron trap, it forms a deep electron-hole pair trap, which increases the trap density and deepens the trap.

[0132] To further control the trap density and depth, M 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ Li, a medium-alkali metal ion, is represented by Na. + Replacement was performed to obtain the phosphors in Examples 6-8. Figure 5 The pyrolysis curves of the phosphors in Examples 6-8 are shown, relative to Bi. 3+ Single-doped sample, Eu 3+ The doping of Tb significantly increases the trap density, but the trap depth appears to tend to become shallower. 3+ The doping completely quenched Bi 3+ The afterglow of the setting sun shone brightly.

[0133] Similarly, M 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ Zhong Lu 3+ By substituting Y or Gd ions, the phosphors of Examples 9-14 were obtained. As... Figure 6 As shown, Eu 3+ Doped germanate phosphors all increase trap density, while Tb 3+ Doping does not produce the same effect. Based on the pyroelectric curve, the formula E = T can be used. max / 500(K) is used to estimate the depth of the electron trap, where E and T max The values ​​represent the average trap depth and peak temperature of the pyrolysis curves, respectively. The trap depths of all sample examples are in the range of 0.5–1.1 eV. Previous studies have shown that trap depths of 0.5–0.7 eV are suitable for afterglow display applications, while trap depths of 0.7–1.0 eV are particularly suitable for information storage.

[0134] In Examples 1 and 6, Eu doping deepens the traps, making them more suitable for information storage and controllable excitation fluorescence. To further describe the fluorescence properties of these phosphors, the Li in Example 1 is used as an example. 0.99 Lu 0.999 GeO4: 1.0% Bi 3+ 0.1% Eu 3+ Taking fluorescent powder as an example, Figure 7 The photoluminescence emission spectrum, excitation spectrum, afterglow emission spectrum, and afterglow decay curves of Examples 1-5 are shown. Figure 7 As shown in Figure A, under 312 nm ultraviolet light excitation, all samples exhibit similar blue light emission bands in the 330–500 nm range, which is attributed to Bi. 3+ of 3 P 1，0 → 1 S0 transition. Except for Bi...3+ In addition to the blue light emission, Eu in Example 1 can also be observed. 3+ of 5 D0→ 7 F2, Tb in Example 2 3+ of 5 D4→ 7 F0 etc. Ln 3+ The characteristic transition.

[0135] Figure 7 In B, the PLE spectrum obtained by monitoring at 370 nm showed Bi splitting due to the Jahn-Teller effect observed against a broadband background at 312 nm and 356 nm. 3+ of 1 S0→ 3 P 1,0 The large double peaks produced by the transition, with a weak absorption peak at the left shoulder (236 nm), are attributed to the transition from the matrix valence band (VB) to the conduction band (CB). Figure 7 C shows the afterglow phenomenon of the phosphors in Examples 1-5 after charging under 236 nm ultraviolet light. All afterglow spectra are similar to their PL spectra, both denoted by Bi. 3+ It is dominated by blue light emission bands, accompanied by a weak Ln. 3+ Typical emission. These spectroscopic results indicate that the afterglow and photoluminescence originate from the same luminescent center. Among them, the phosphors of Examples 4 and 5 have better room temperature afterglow performance, while Example 1 has almost no room temperature afterglow, which is consistent with its deep trapping characteristics. Figure 7 D indicates that, except for Examples 2 and 1, Examples 3 through 5 all showed shorter afterglow durations.

[0136] Figure 8 The temperature-dependent afterglow characteristics of the phosphor in Example 1 are demonstrated. We can clearly see that as the temperature increases from room temperature to 110°C, the excitation fluorescence intensity reaches its peak, and then slowly decreases as the temperature continues to increase, suggesting that the afterglow intensity is temperature-dependent. Figure 9 This demonstrates the change in blue and red excitation fluorescence intensity of the phosphor in Example 1 as the charging temperature increases. Clearly, this is due to the Bi... 3+ The information capacity of the blue excitation phosphor increases with increasing temperature, reaching its optimal charging state in the range of 50–80°C, forming an anomalous thermal capacitance phenomenon. Conversely, the red excitation phosphor shows a slight decreasing trend in intensity as the temperature rises, with deeper trap filling. Particularly interestingly, the phosphor in Example 1, after charging, exhibits information that appears to condense at room temperature; the pyroelectric curve was measured after 5 days. Figure 10 The trap filling capacity has almost no room temperature dissipation, suggesting that it does not easily lose information and retains its properties.

[0137] The variable-temperature pyrolysis curves of Examples 2-4 are shown in... Figure 11 In the middle. Among them, Example 2 ( Figure 11 A) and Example 4 Figure 11 B) both showed a certain high-temperature information storage capacity, while Example 3 ( Figure 11 C) Only the ability to write room temperature information was demonstrated.

[0138] Figure 12 The photoexcitation fluorescence properties of the phosphors in Examples 1-4 were confirmed. Under near-infrared laser excitation, all samples exhibited good photoexcitation fluorescence properties, suggesting that the written information can be read out by photoexcitation. Figure 13 The photoluminescence excitation spectrum and afterglow excitation spectrum of the phosphor in Example 1 are shown. The maximum excitation peaks of the two do not overlap. The maximum position of the afterglow excitation spectrum is at the valence band to conduction band transition peak. The photoluminescence excitation peak is mainly due to the electronic transitions of energy levels within the dopant ions. Therefore, we can control the energy consumed to suppress photoluminescence by appropriately selecting the charging wavelength. Figure 14 Bi is shown in Examples 1 and 5. 3+ The 4f high-resolution photoelectron spectrum, compared with Figure 14 A and B, it is not difficult to see that Eu 3+ After doping, Bi was induced 3+ Changes in oxidation states may lead to an increase in trap density and distribution.

[0139] Considering the experimental results above, we propose possible schematic diagrams of photoluminescence, afterglow, photo / thermal excited fluorescence, and photo-excited afterglow fluorescence for examples 1–14 of hole-electron pair deep trap structure maneuvering, and in… Figure 15 As shown in the diagram, when the sample is irradiated with ultraviolet light, electrons are excited from the ground state to the conduction band (CB), leaving holes in the ground state. Holes and some electrons are trapped by hole / electron traps via the VB / CB, while the remaining electrons are released as blue light. They then return to the ground state after rapid energy transfer and non-radiative relaxation to the red fluorescence level, producing Bi. 3+ Photoluminescence and Ln 3+ Typical fluorescence emission. The released electrons / holes, upon external stimulation, cross the conduction band and interact with Bi. 3+ / Yb 3+ / Eu 3+ / Tb 3+ When electrons from the luminescent centers combine, afterglow and thermally / optically excited fluorescence are produced, and most of the electrons in the traps are released to the blue light state by the CB. A 980nm laser accelerates energy transfer and non-radiative relaxation or multiphonon relaxation, resulting in bright red excited fluorescence. In Bi... 3+ During the luminescence process, Bi 3+ To Ln 3+ Energy transfer is efficient. Under photothermal induction, charge carriers are converted by Bi.3+ and Ln 3+ Once the trap is captured and released, accompanied by Bi 3+ and Ln 3+ Changes in ion valence states. For example, under 236 nm ultraviolet light irradiation, through Bi... 3+ Conduction band electrons generated by the photoionization process of the charge transfer band can be converted into Eu. 3+ Capture and form Eu 2+ And leaving Bi 3+ The hole can be Bi 2+ Capture and form Bi 3+ Under light / thermal excitation, electrons from Eu... 2+ Gradually released into the conduction band, then with Bi 3+ + Hole recombination ultimately produces Bi with a peak value at 408nm. 3+3 P0- 1 S0 launch.

[0140] (III) Application in Anti-counterfeiting and Storage of Optical Information

[0141] Considering the excellent performance of the phosphors in Examples 1-4, dynamic luminescent patterns for multidimensional information storage and encryption were designed, such as... Figure 16 As shown.

[0142] Figure 16 a is a structural diagram of the fluorescent "butterfly and flower" pattern, with each part composed of different phosphors from Examples 1 to 4. Under selective excitation from ultraviolet to visible light, Bi... 3+ Blue glow and Ln 3+ The mixing of characteristic emissions causes individual phosphors to exhibit a variety of colorful variations, such as Figure 16 As shown in b, after being charged with 254nm ultraviolet light, the afterglow pattern of the colorful butterfly and flower was visible to the naked eye. As time progressed, the various parts gradually disappeared, until after 20 minutes, the green leaves completely disappeared. Figure 16 c). After the afterglow pattern disappears, the latent pattern can be recovered and extracted again using an 808 / 980nm laser diode or thermally assisted illumination. Figure 16 d~e).

[0143] Even more interestingly, by consciously controlling the temperature of ultraviolet pre-irradiation, multidimensional information can be recorded and stored on a single-layer luminescent material film. For example, Figure 16 The rose pattern in f was written using a hollow rose mask at 423K under 254nm UV light. Subsequently, a leaf pattern was created by UV polishing and stored at 353K. Finally, a butterfly pattern was written at room temperature using a UV mask pattern under 254nm light. Thus, three different patterns were stored in traps at different depths. Figure 16As shown in f, the pre-stored 'roses' are stored only in deep traps, 'leaves' are stored in medium-deep traps, and 'butterflies' are stored in traps of various depths. Different patterns can be visualized through temperature management. For example, by reading the above information using temperature sequences of RT, 353, and 423 K, dynamic pattern information can be read out in the spatial domain. Figure 16 f). For example Figure 16 As shown in f, the recorded 'butterfly' is read out separately and clearly in RT. When the temperature is raised to 353K, the 'butterfly' and 'leaf' can be clearly identified. Further raising the temperature to 423K, the entire pattern, including the 'butterfly,' 'leaf,' and 'rose,' can be observed. In this way, multidimensional information can be stored and retrieved, increasing the information storage capacity.

[0144] Figure 17 The image is a 'flower' stored based on Example 6 as a fluorescent medium material. Figure 17 a) Under 236nm ultraviolet light irradiation, Bi 3+ blue glow and Eu 3+ The mixture of red light makes the 'flower' appear purplish-red, and with the help of filters, pure blue and red 'flower' photos can be obtained. Figure 17 b). After the 236nm ultraviolet light irradiation was stopped, the flowers emitted a purplish-red afterglow that lasted for more than 30 minutes. Figure 17 c). As time progresses further, the flower pattern disappears first. After the afterglow pattern fades, the latent pattern can be recovered and extracted again by illuminating or heating the pattern with an 808 / 980nm laser. Figure 17 (d~e). Similarly, by controlling the temperature of ultraviolet pre-irradiation, multidimensional information can be recorded and stored on a single-layer luminescent material film. For example, Figure 17 The large flower pattern in f was written using a hollow large flower photomask at 423K under 236nm ultraviolet light. Subsequently, the small flower pattern was stored at 353K by covering the entire printed pattern with a perforated small flower photomask. Finally, the leaf pattern was written at room temperature using a hollow leaf photomask pattern under 236nm light. Therefore, three different patterns are stored in traps at different depths. Figure 17 As shown in f, the pre-stored 'leaves' are stored in shallow traps, 'small flowers' are stored in medium-deep traps, and 'large flowers' are stored only in locally deep traps, which can be visualized through temperature management. Then, by reading the above information through temperature sequences of RT, 353, and 423K, dynamic pattern information can be read out in the spatial domain. Figure 17 f). For example Figure 17As shown in f, the recorded leaf shapes are read out individually and clearly in RT. When the temperature is raised to 353K, the leaves and florets can be clearly identified. Further raising the temperature to 423K reveals the entire pattern, including the 'leaf', 'florets', and 'large flowers'. This allows for the storage and retrieval of multidimensional information, increasing storage capacity.

[0145] To address the needs of potential multifunctional applications, this invention, based on luminescence mechanisms, defect engineering, bandgap engineering, and site occupancy principles, successfully designed a variety of long-afterglow luminescent materials with multicolor emission. Experimental results confirm that Bi... 3+ Ln 3+ Co-doped germanate-based luminescent materials exhibit excellent multicolor and multimode fluorescence properties, meeting specific requirements. Through temperature-dependent thermoluminescence analysis, the trapping properties were extensively investigated, the fluorescence mechanism was elucidated, and the role of Ln was emphasized. 3+ The key role of co-doping. In these luminescent materials, MReGeO4:Bi 3+ ,Ln 3+ It exhibits superior fluorescence performance. This work not only validates the utility of deep-trapped afterglow in potential multifunctional applications, but also establishes design concepts suitable for novel afterglow materials.

[0146] Finally, it should be noted that the above examples are merely some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A germanate-based long afterglow luminescent material, characterized in that, The luminescent material is based on MReGeO4 and doped with Bi and Ln ions. 3+ The luminescent material was obtained, and the chemical formula of the luminescent material is M. 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ ; Where M is Li or Na, Re is Y, Lu or Gd, and Ln is one of Eu, Tb or Yb; 0 < x ≤0.010, 0<y≤0.001; The luminescent material is prepared according to the following steps: According to the chemical formula M of the luminescent material 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ According to the stoichiometric ratio in the mixture, the M source, Re source, Ge source, O source, Bi source and Ln source are weighed, mixed, and heated to 1000~1300℃ in air at a heating rate of 2~4℃ / min, and calcined for 4~8h to obtain the luminescent material.

2. A method for preparing the luminescent material according to claim 1, characterized in that, Includes the following steps: According to the chemical formula M of the luminescent material 1-x Re 1-y GeO4:xBi 3+ ,yLn 3+ According to the stoichiometric ratio in the formula, the M source, Re source, Ge source, O source, Bi source and Ln source are weighed, mixed and calcined to obtain the luminescent material; the calcination is carried out in an air atmosphere, the temperature is raised to 1000~1300℃ at a heating rate of 2~4℃ / min and calcined for 4~8h.

3. The preparation method according to claim 2, characterized in that, The M source, Re source, Ge source, Bi source and Ln source are all oxygen-containing compounds containing the corresponding elements; The O source is provided by the oxygen-containing compounds.

4. The preparation method according to claim 3, characterized in that, The oxygen-containing compound is any one or more of oxides, carbonates, or nitrates.

5. The preparation method according to claim 2, characterized in that, During mixing, grind the raw materials for 0.5 to 1 hour.

6. Use of the luminescent material of claim 1 as a material for information storage or encryption.

7. The use according to claim 6, characterized in that, The luminescent material is used for multidimensional visualization information storage and encryption.

8. The use according to claim 6, characterized in that, The information storage or encryption is achieved with the assistance of ultraviolet light irradiation.

9. The use according to claim 6, characterized in that, The information storage or encryption is achieved by controlling the exposure to light or heat again at a specific time frame after ultraviolet pre-irradiation.

Images