Eu < 2 + > activated red afterglow material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of inorganic light-storing functional materials, in particular to an Eu < 2 + > activated red afterglow material and a preparation method and application thereof. The red afterglow material is obtained by taking XZnOS in a hexagonal phase polycation coordination environment as a matrix material and doping an active ion source into a matrix material lattice; the chemical expression of the red afterglow material is XZnOS: xM, wherein X is at least one of Ca < 2 + >, Sr < 2 + > and Ba < 2 + >; m is Eu < 2 + > or a mixture of Eu < 2 + > and Dy < 3 + >, Mn < 2 + >, Ho < 3 + >, Nd < 3 + >, Er < 3 + > and Cu < XZnOS with multi-lattice cations and a layered structure is selected as a matrix material, a polar defect structure for inducing electron-hole defect pair layering in crystal lattices is designed and synthesized by selecting double dopants, bistable high-density trap and high-capacity carrier storage are realized, and an optical function material with high-brightness long-life afterglow fluorescence is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic light-storage functional materials, and in particular to a Eu 2+ Activated red afterglow material, preparation method and application thereof. Background Art

[0002] As a multi-mode fluorescent material, red afterglow materials have broad application prospects in biomedicine, food safety testing, information storage and encryption, latent fingerprint recognition, low-light lighting, signal lights, optoelectronic devices, and defense technology, making them a cutting-edge research hotspot in the field of luminescent materials. While traditional halogen and tungsten-halogen lamps have played a key role in red and near-infrared light-emitting devices, they still have many fundamental limitations. These include unstable operation due to thermal runaway, electro-optical conversion efficiencies below 5%, severe background fluorescence interference, and size incompatibility with miniaturized systems, which restrict their further application.

[0003] With the continuous emergence of new afterglow materials, based on the natural multi-mode properties of afterglow materials, afterglow materials have broad application prospects in the fields of fourth-generation information storage and encryption and latent fingerprint recognition. 2+ It has become an important afterglow luminescence center due to its 4f-5d parity-allowed transition. In particular, SrAl2O4:Eu 2+ ,Dy 3+ After the report of commercial green powder with a long and bright green afterglow of up to 12 hours, a wave of research on long afterglow luminescent materials was triggered. 2+ Activated aluminates and silicates and other afterglow materials have been developed, such as emission wavelength λ mon =440nmCaAl2O4:Eu 2+ ,Nd 3+ , emission wavelength λ mon =490nm Sr4Al 14 O 25 :Eu 2+ ,Dy 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ It has also achieved great commercial success in the civilian field, especially in emergency signs, safety instructions, luminous paint and dials. 2+ The blue and green afterglow luminescent materials based on Eu 2+ The development of long-lasting luminescent materials that activate red and near-infrared light faces great challenges. 14 O 25 :Eu 2+ ,Dy3+ Commercial green afterglow powder is not sensitive to the red region of the spectrum from 620nm to 750nm. Even at the same intensity, red afterglow powder still cannot achieve the application goal. The above factors further exacerbate this challenge.

[0004] Considering the 4f 7 →4f 6 5d 1 Eu of the Leap 2+ The luminescence center is different from the 4f-4f transition of trivalent rare earth ions. Its luminescence is greatly affected by the local crystal field environment. It shows a broadband emission characteristic that depends on the 3d splitting under the crystal field intensity. The 5d orbital is affected by many factors, and the excitation energy and emission energy can be adjusted by changing the composition and structure of the host crystal. 2+ The emission spectrum characteristics depend on the local coordination environment. Specifically, based on crystal field theory, changes in the bond length between the activator and the anion can have a significant effect on the spectrum. For example, Eu 2+ With O 2- The shortening of the bond length between them will enhance the crystal field splitting and electron cloud rearrangement effect, resulting in a red shift in the spectrum; on the contrary, the extension of the bond length will cause a blue shift. However, achieving near-infrared emission requires strong crystal field splitting and strong interaction with Eu. 2+ The large center of gravity shift associated with ions, therefore achieving near-infrared emission remains a major challenge. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a Eu 2+ Activated red afterglow material, preparation method and application thereof.

[0006] Compared with the attempts to realize Eu in aluminates, silicates and their oxides, 2+ Activated afterglow material, the present invention focuses on Eu 2+ Activated oxysulfide XZnOS crystals, where X is at least one of Ca, Sr, and Ba. Examples include CaZnOS, SrZnOS, and BaZnOS. These materials have attracted significant attention due to their multiple cation sites, layered polar compound properties, and high rare earth doping compatibility. XZnOS exhibits a wide bandgap greater than 3.3 eV, a high piezoelectric coefficient, and excellent physicochemical stability. Furthermore, unlike salts and oxides, XZnOS possesses two anion sites with different electronegativity, allowing for easy manipulation of its polarity and bandwidth through doping and experimental processing. These advantages make XZnOS a promising candidate for both traditional photoluminescence and upconversion applications, as well as for novel strain-induced luminescence materials.

[0007] However, although rare earth / transition metal doped XZnOS fluorescent materials exhibit tunable multi-level luminescence properties under specific excitation conditions, the realization of near-infrared emission requires strong crystal field splitting and interaction with Eu 2+ ion-related large center of gravity shift, which increases Eu 2+ The difficulty of preparing activated red afterglow materials. 2- and O 2- Layered polar lattices, expected to realize Eu in XZnOS 2+ The preparation of activated red afterglow phosphor is further applied to information storage and encryption and latent fingerprint recognition, thus filling the gap of Eu 2+ Activate the blank of the red afterglow material.

[0008] To achieve the above objectives, the technical solutions of the present invention are as follows.

[0009] The first aspect of the present invention provides a Eu 2+ Activated red afterglow material, the Eu 2+ The chemical formula of the activated red afterglow material is XZnOS: x M; where X is Ca 2+ 、Sr 2+ and Ba 2+ At least one of; M is Eu 2+ or Eu 2+ With Dy 3+ 、Mn 2+ 、Ho 3+ 、Nd 3+ 、Er 3+ 、Cu 2+ At least one of the co-doping; and 0 < x ≤1%; the Eu 2+ The activated red afterglow material is based on XZnOS with hexagonal multi-cation coordination environment as the matrix material and M as the activation ion source. The activation ion source is doped into the lattice of the matrix material to form Eu 2+ As cathode, Dy 3+ 、Ho 3+ 、Nd 3+ 、Er 3+ 、Mn 2+ and Cu 2+ At least one of the anodes is a primary battery structure redox reaction system.

[0010] The present invention selects XZnOS with multiple cation sites and anion sites and a layered structure as the matrix material, and uses M as the activation ion source. By doping the activation ion source into the lattice of the matrix material, the invention aims to construct a structure with high defect density and the ability to achieve layered isolation of electron-hole defects, forming a primary cell structure redox reaction system with redox layered reaction, and then constructing a positive and negative electrode primary cell-electrolytic cell bistable trap structure, realizing the separate storage and excitation reaction of positive and negative charges from the source, thereby preparing Eu with high capacity light storage and energy storage characteristics. 2+ Activated red afterglow material.

[0011] Preferably, artificial ultraviolet light, artificial visible light or natural light is used as the charging light source, and the Eu 2+ The activated red afterglow material is excited to exhibit multi-mode luminescence under the irradiation of a charging light source.

[0012] Ultraviolet excitation is the standard excitation mode of afterglow. 2+ The activated red afterglow material can be excited to exhibit multi-mode luminescence under the irradiation of a charging light source, and the charging light source is an artificial ultraviolet light source, an artificial visible light source or natural light.

[0013] Preferably, artificial ultraviolet light, artificial visible light or natural light is used as the charging light source, and the Eu 2+ The activated red afterglow material stores light energy when exposed to a charging light source. After the charging light source is removed, it continues to emit red afterglow visible to the naked eye for 40 to 60 minutes.

[0014] The luminescence enhancement mechanism of the present invention originates from the microelement photochemical cell formed based on doping in the lattice, wherein Eu 2+ Acting as cathode, M except Eu 2+ Other metal ions other than the Eu act as anode. 2+ The activated red afterglow material can be excited to emit multi-mode light under the irradiation of the charging light source, showing excellent multi-mode luminescence performance. 2+ ,Dy 3+ Compared with the green afterglow phosphor, the Eu 2+ The activated red afterglow material can exhibit significantly stronger near-infrared long afterglow luminescence, and can maintain stable and strong photoluminescence performance during and after irradiation with a charging light source even at high temperatures.

[0015] Preferably, the Eu 2+ The particle size of the activated red afterglow material is ≤5μm.

[0016] The second aspect of the present invention provides a Eu 2+ The method for preparing an activated red afterglow material comprises the following steps: According to Eu 2+ Chemical expression of activated red afterglow material XZnOS: x M stoichiometric ratio, using the metal inorganic salt corresponding to the matrix material and the metal oxide corresponding to the activation ion source as raw materials, the metal inorganic salt corresponding to the matrix material and the metal oxide corresponding to the activation ion source are mixed and ground to obtain a mixed powder; the mixed powder is sintered under a protective atmosphere to allow the activation ion source to be doped into the lattice of the matrix material to form a Eu 2+ As cathode, Dy 3+ 、Ho 3+ 、Nd 3+ 、Er 3+ 、Mn 2+ and Cu 2+ At least one of the anodes in the galvanic cell structure redox reaction system is cooled to room temperature and ground to obtain Eu 2+ Activated red afterglow material.

[0017] The present invention optimizes the experimental process parameters to control the bandwidth and local lattice symmetry, and obtains Eu for the first time. 2+ Activated red afterglow material. Eu prepared by the present invention 2+ The activated red afterglow material can react with Eu 2+ Activated green SrAl2O4:Eu 2+ ,Dy 3+ and blue Sr4Al 14 O 25 :Eu 2+ ,Dy 3+ Together they form Eu 2+ It is a three-primary color afterglow material, filling Eu 2+ Activate the blank of the red afterglow material.

[0018] Preferably, the sintering temperature is 850°C to 1050°C; the metal inorganic salt corresponding to the matrix material is a carbonate, nitrate or sulfide corresponding to the metal element in the matrix material, and at least one metal inorganic salt is a sulfide; the protective atmosphere is an inert atmosphere; and the particle size of the mixed powder is ≤5μm.

[0019] The metal inorganic salt corresponding to the matrix material is the carbonate or nitrate corresponding to the X element and ZnS.

[0020] When selecting the raw materials for the activation ion source, the present invention takes into account the stability of the activation ion source and preferably selects the raw materials for the activation ion source to be oxides containing corresponding elements, such as Eu2O3, Dy2O3 or MnO.

[0021] In the present invention, the protective atmosphere is an inert atmosphere. During the preparation process, the present invention uses an inert atmosphere, such as nitrogen, to protect the M ions as defect creator ions, allowing the coexistence of variable-valence ions while effectively protecting the bistability defect density, thereby comprehensively improving the energy storage capacity and obtaining a red ultra-long and ultra-bright afterglow emission material with an effective trap density.

[0022] The third aspect of the present invention provides a Eu 2+ The activated red afterglow material is used as a light-storage and energy-storage fluorescent material for applications in high-throughput information storage and encryption. 2+ The activated red afterglow material is Eu as described in the first aspect. 2+ Activated red afterglow material.

[0023] Preferably, the specific application method is: Artificial ultraviolet light, artificial visible light or natural light is used as the charging light source, the Eu 2+ The activated red afterglow material acts as a light-storage and energy-storage fluorescent material. It stores light energy when exposed to a charging light source. After the charging light source is removed, it continuously emits a red afterglow visible to the naked eye for 40 to 60 minutes, exhibiting multi-mode luminescence.

[0024] In the present invention, the charging light source is an artificial ultraviolet light source, an artificial visible light source or natural light; for example, natural light is sunlight; the artificial ultraviolet light source is an ultraviolet lamp; the artificial visible light source is a mobile phone light, etc.

[0025] The present invention uses Eu 2+ The activated red afterglow material is used as a light-storage material for photon information storage and encryption, which can realize multi-mode information storage and encryption.

[0026] A fourth aspect of the present invention provides a Eu 2+ The activated red afterglow material is used as a light-storage energy storage fluorescent material for the application of latent fingerprint recognition. 2+ The activated red afterglow material is Eu as described in the first aspect. 2+ Activated red afterglow material.

[0027] Preferably, the specific application method is: Artificial ultraviolet light, artificial visible light or natural light is used as the charging light source, the Eu 2+ The activated red afterglow material acts as a light-storing and energy-storing fluorescent material. It stores light energy when exposed to a charging light source. After the charging light source is removed, it continuously emits red afterglow imaging visible to the naked eye for 40 to 60 minutes, revealing latent fingerprints.

[0028] The present invention uses Eu 2+The activated red afterglow material is used as a light-storing material in latent fingerprint recognition, and can present latent fingerprints with high resolution.

[0029] Beneficial effects of the present invention: 1. The present invention selects XZnOS with multiple cation sites and anion sites and a layered structure as the matrix material, and uses M as the activation ion source. By doping the activation ion source into the lattice of the matrix material, the invention aims to construct a structure with a high defect density and the ability to achieve layered isolation of electron-hole defects, forming a primary cell structure redox reaction system with redox layered reactions, realizing the separate storage and excitation reaction of positive and negative charges from the source, thereby preparing a red afterglow material with high-capacity light storage and energy storage characteristics.

[0030] 2. The luminescence enhancement mechanism of the present invention originates from the microelement photochemical cell formed by doping in the lattice, wherein Eu 2+ Acting as cathode, M except Eu 2+ Other metal ions other than the Eu act as anode. 2+ The activated red afterglow material not only exhibits excellent multi-mode luminescence performance, but also exhibits significantly stronger near-infrared long afterglow luminescence, and can maintain stable and strong photoluminescence performance during and after irradiation with the charging light source.

[0031] 3. Eu of the present invention 2+ The activated XZnOS red afterglow material can be used as a light-storage fluorescent material to store light energy using artificial ultraviolet light, artificial visible light or natural light as a charging light source.

[0032] 4. Eu of the present invention 2+ The activated red afterglow material has the characteristics of high brightness and long life. After the charging light source is removed, it can continue to emit red afterglow visible to the naked eye for more than 40 minutes. It can be conveniently used in high-throughput information storage and encryption or latent fingerprint recognition.

[0033] 5. The red afterglow material of the present invention is prepared by a traditional high-temperature solid-phase method, which has a simple preparation process, high output and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The X-ray diffraction patterns of the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2 are shown.

[0035] Figure 2 Scanning electron micrographs and energy-dispersive X-ray spectroscopy elemental distribution patterns of the sample from Example 2. (a) and (b) are scanning electron micrographs at different magnifications; (c) to (h) are energy-dispersive X-ray spectroscopy elemental distribution patterns.

[0036] Figure 3 1 is the afterglow emission spectrum of the samples of Examples 1 to 3.

[0037] Figure 4 1 is the afterglow decay curve of the samples of Examples 1 to 3.

[0038] Figure 5 These are the thermal release curves of the samples of Examples 1 to 3.

[0039] Figure 6 This is the afterglow emission spectrum of the samples of Examples 4 to 6.

[0040] Figure 7 1 and 2 are afterglow decay curves of the samples of Examples 4 to 6.

[0041] Figure 8 These are the thermal release curves of the samples of Examples 4 to 6.

[0042] Figure 9 The energy band structure and state density distribution diagram of SrZnOS crystal material. Among them, (a) is the energy band structure; (b) is the state density distribution diagram.

[0043] Figure 10 These are the photoluminescence emission spectra and photoluminescence excitation spectra of the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2.

[0044] Figure 11 The afterglow emission spectra of the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2 are shown.

[0045] Figure 12 These are the afterglow decay curves of the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2.

[0046] Figure 13 These are the thermal release curves of the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2.

[0047] Figure 14 These are the thermal release curves of the samples of Example 2, Examples 7 to 9, and Comparative Example 3.

[0048] Figure 15 These are the photoluminescence emission spectra and photoluminescence excitation spectra of the samples of Example 2, Comparative Example 4 and Comparative Example 5.

[0049] Figure 16 2 are the afterglow emission spectra of the samples of Example 2, Comparative Example 4 and Comparative Example 5.

[0050] Figure 17 These are the afterglow decay curves of the samples of Example 2, Comparative Example 4, and Comparative Example 5.

[0051] Figure 18 The thermograms of the samples of Example 2, Comparative Example 4 and Comparative Example 5 are shown.

[0052] Figure 19 This is the afterglow emission spectrum of the sample of Example 2 depending on different charging light sources.

[0053] Figure 20 The afterglow emission spectra of the sample in Example 2 and commercial SrAl2O4:0.5%Eu,0.5%Dy green afterglow powder.

[0054] Figure 21 The diagram shows the mechanism of photoluminescence, afterglow luminescence, thermally stimulated luminescence, and mechanoluminescence in the sample of Example 2. The inset within the band gap shows the defect structure.

[0055] Figure 22 Figure 2 shows a multimodal optical information encryption pattern using the sample from Example 2 and a commercial SrAl2O4:0.5%Eu,0.5%Dy phosphor film. (a) shows the design structure of the "Mermaid Offering Pearls" pattern. The red fish is printed with SrZnOS:0.5%Eu,0.5%Dy; the green pearl is printed with SrAl2O4:0.5%Eu,0.5%Dy. (b) shows photoluminescence images under 254nm UV, 365nm UV, 395nm near-UV, 468nm blue visible, and 500nm blue-green visible light. (c) shows the afterglow pattern image after 3 minutes of UV excitation. (d) shows the afterglow pattern images recorded at 5s, 1min, and 5min after exposure to mobile phone light. (e) shows the afterglow pattern images recorded at 5s, 1min, and 5min after pre-exposure to sunlight.

[0056] Figure 23 These are fluorescence photographs of fingerprints used in latent fingerprint recognition using the sample of Example 2. (b) to (f) are enlarged views of the sections marked 1 to 5 in (a); (g) to (j) are further enlarged views of the sections marked 2 and 3. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0058] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0059] Figures 1 to 23In the above, the intensity is the fluorescence intensity and the wavelength is the light wavelength. Before measuring the afterglow emission spectrum, afterglow decay curve and thermal release curve, the sample has been pre-irradiated with a charging light source of the corresponding wavelength for 3 minutes or 5 minutes. mon Indicates the monitoring wavelength. charge Indicates the charging wavelength. λ ex represents the excitation wavelength.

[0060] It should be noted that in the matrix material of the present invention, X is Ca 2+ 、Sr 2+ and Ba 2+ At least one of the following; The present invention is based on valence band engineering and designs a strategy of isovalent ion substitution to achieve the regulation of band gap structure. XZnOS can be regarded as CaZnOS, or on the basis of CaZnOS, Sr 2+ Or Ba 2+ Complete replacement of Ca 2+ In addition, the present invention can effectively control the obtained traps by adjusting the doping of M, thereby achieving the Eu 2+ Adjusts the persistence properties of the activated red afterglow material.

[0061] In the present invention, taking into account factors such as lattice structure and optimal electronic structure, the matrix material is preferably SrZnOS. The chemical formula of the ultra-long red afterglow material is SrZnOS: x M. Where M is Eu 2+ , or co-doped with at least one of the rare earth ions; x is the molar percentage of M in SrZnOS, and x =0.5%. In order to ensure that the trap characteristics can be controlled, the present invention preferably uses Eu 2+ Dopant acts as a doping activated luminescent center ion source, Dy 3+ As Eu 2+ of auxiliary dopants to introduce defects.

[0062] In order to fully grind and mix the components, the present invention preferably adopts manual / ball milling to grind until all chemicals are completely mixed. For example, the grinding time is 0.5h to 1h to obtain a mixed powder with a particle size of ≤5μm.

[0063] In order to ensure that the doped ions of each component can maintain appropriate valence during the sintering process, the present invention preferably performs the sintering process in an inert atmosphere, and the preferred sintering temperature is 950°C, which is lower than the sublimation temperature of the precursor raw materials. The preferred sintering time is 6 hours to achieve the purpose of sufficient reaction of each component.

[0064] This study compared products produced under different atmospheres by controlling the atmosphere, replacing an inert atmosphere with either a reducing atmosphere or air. The key objective was to control the type and valence of the traps. Results showed that an inert atmosphere was optimal, preventing the reduction of high-valence traps and suppressing oxygen vacancies, a key step in achieving trap control in this invention. Nitrogen was the preferred inert atmosphere.

[0065] The present invention takes into account the particle size factor of the prepared sample and further grinds the product obtained by sintering treatment. The grinding can be performed by manual or mechanical ball milling, and the sample particles are ground to fineness, which takes about 0.5h to 1.0h to obtain a particle size of the obtained product ≤5μm.

[0066] The technical solution of the present invention is further described below through specific embodiments.

[0067] In the following examples, the methods described are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0068] Example 1 A kind of Eu 2+ The activated red afterglow material has the chemical formula of CaZnOS: 0.5%Eu, 0.5%Dy. Example 1 uses CaZnOS as the matrix material and introduces Eu 2+ and Dy 3+ Obtained. The specific preparation method is as follows: According to the stoichiometric ratio of CaZnOS: 0.5% Eu, 0.5% Dy, weigh 0.1964g CaCO3, 0.3899g ZnS, 0.0035g Eu2O3, and 0.0037g Dy2O3 respectively. Mix the weighed CaCO3, ZnS, Eu2O3, and Dy2O3, and grind them for 0.5h to obtain a mixed powder. Sinter the mixed powder at 950℃ for 6h under N2 atmosphere. After cooling to room temperature, grind the sintered product for 0.5h. The powder obtained is Eu 2+ Activated red afterglow material.

[0069] Example 2 A kind of Eu 2+ The activated red afterglow material has a chemical formula of SrZnOS: 0.5% Eu, 0.5% Dy. The difference between Example 2 and Example 1 is that Example 2 uses Sr 2+ Completely replaces Ca 2+ , that is, weigh 0.5905g SrCO3 to replace 0.1964g CaCO3 in Example 1.

[0070] Example 3 A kind of Eu 2+The activated red afterglow material has a chemical formula of BaZnOS: 0.5% Eu, 0.5% Dy. The difference between Example 3 and Example 1 is that the BaZnOS used in Example 3 is 2+ Completely replaces Ca 2+ , weigh 0.3909 g of BaCO3 instead of weighing 0.1964 g of CaCO3 in Example 1.

[0071] Example 4 A kind of Eu 2+ The activated red afterglow material has a chemical formula of CaZnOS: 0.5% Eu, 0.5% Mn. The only difference between Example 4 and Example 1 is that Example 4 uses Mn 2+ Completely replace Dy 3+ , 0.0007 g of MnO was used to replace 0.0037 g of Dy2O3 in Example 1.

[0072] Example 5 A kind of Eu 2+ The activated red afterglow material has a chemical formula of SrZnOS: 0.5% Eu, 0.5% Mn. The only difference between Example 5 and Example 2 is that the Mn used in Example 5 is 2+ Completely replace Dy 3+ , 0.0007 g of MnO was used to replace 0.0037 g of Dy2O3 in Example 1.

[0073] Example 6 A kind of Eu 2+ The activated red afterglow material has a chemical formula of BaZnOS: 0.5% Eu, 0.5% Mn. The only difference between Example 6 and Example 3 is that the Mn used in Example 6 is 2+ Completely replace Dy 3+ , 0.0007 g of MnO was used to replace 0.0037 g of Dy2O3 in Example 1.

[0074] Example 7 A kind of Eu 2+ The activated red afterglow material has a chemical formula of SrZnOS: 0.5% Eu, 0.5% Ho. The only difference between Example 7 and Example 2 is that the Ho used in Example 7 is 3+ Completely replace Dy 3+ , 0.0037 g of Ho2O3 was used to replace 0.0037 g of Dy2O3 in Example 2.

[0075] Example 8 A kind of Eu 2+The activated red afterglow material has a chemical formula of SrZnOS: 0.5% Eu, 0.5% Nd. The only difference between Example 8 and Example 2 is that the Nd used in Example 8 is 3+ Completely replace Dy 3+ , 0.0033 g Nd2O3 was used instead of 0.0037 g Dy2O3 in Example 2.

[0076] Example 9 A kind of Eu 2+ The activated red afterglow material has a chemical formula of SrZnOS: 0.5% Eu, 0.5% Er. The difference between Example 9 and Example 2 is that the Er used in Example 9 is 3+ Completely replace Dy 3+ , 0.0038 g of Er2O3 was used to replace 0.0037 g of Dy2O3 in Example 2.

[0077] Comparative Example 1 A kind of Eu 2+ The activated red afterglow material has a chemical formula of SrZnOS:0.5%Eu. Comparative Example 1 is based on SrZnOS and introduced Eu 2+ The specific preparation method is as follows: according to the stoichiometric ratio of SrZnOS:0.5%Eu, weigh 0.5905g SrCO3, 0.3899g ZnS, and 0.0035g Eu2O3 respectively. After the weighed SrCO3, ZnS, and Eu2O3 are mixed, grind for 0.5h to obtain a mixed powder. The mixed powder is sintered at 950℃ for 6h under N2 atmosphere. After cooling to room temperature, the sintered product is grinded for 0.5h to obtain a powder, which is Eu 2+ Activated red afterglow material.

[0078] Comparative Example 2 A kind of Eu 2+ The activated red afterglow material has the chemical formula of SrZnOS: 0.5%Eu, 0.5%Dy, 0.5%Mn. Comparative Example 2 is based on SrZnOS and introduced Eu 2+ 、Mn 2+ and Dy 3+The specific preparation method is as follows: according to the stoichiometric ratio of SrZnOS: 0.5%Eu, 0.5%Dy 0.5%Mn, weigh 0.5875g SrCO3, 0.3899g ZnS, 0.0035g Eu2O3, 0.0007g MnO, and 0.0037g Dy2O3 respectively. After mixing the weighed SrCO3, ZnS, Eu2O3, MnO, and Dy2O3, grind them for 0.5h to obtain a mixed powder. Sinter the mixed powder at 950°C for 6h under N2 atmosphere. After cooling to room temperature, grind the sintered product for 0.5h. The powder obtained is Eu 2+ Activated red afterglow material.

[0079] Comparative Example 3 A kind of Eu 2+ The activated red afterglow material has the chemical formula of SrZnOS: 0.1%Eu, 0.5%Dy, 0.5%Cu. Comparative Example 3 is based on SrZnOS and introduces Eu 2+ 、Dy 3+ and Cu 2+ The specific preparation method is as follows: according to the stoichiometric ratio of SrZnOS: 0.1% Eu, 0.5% Dy, 0.5% Cu, weigh 0.2950g SrCO3, 0.1949g ZnS, 0.0035g Eu2O3, 0.0037g Dy2O3, and 0.0033g CuCl2·2H2O respectively. After mixing the weighed SrCO3, ZnS, Eu2O3, Dy2O3, and CuCl2·2H2O, grind them for 0.5h to obtain a mixed powder. Sinter the mixed powder at 950℃ for 6h under N2 atmosphere. After cooling to room temperature, grind the sintered product for 0.5h. The powder obtained is Eu. 2+ Activated red afterglow material.

[0080] Comparative Example 4 A kind of Eu 2+ The activated red afterglow material has a chemical formula of SrZnOS: 0.5% Eu, 0.5% Dy. The only difference between Comparative Example 4 and Example 2 is that the nitrogen atmosphere in Example 2 is replaced by an air atmosphere in Comparative Example 4.

[0081] Comparative Example 5 A kind of Eu 2+ The activated red afterglow material has a chemical formula of SrZnOS:0.5% Eu, 0.5% Dy. Comparative Example 4 differs from Example 2 only in that the nitrogen atmosphere in Example 2 is replaced with a reducing atmosphere. The reducing atmosphere is a mixture of nitrogen and hydrogen, with a volume ratio of N2 to H2 of 95:5 (denoted as an N2&H2 mixture).

[0082] Eu prepared in Examples 1 to 9 and Comparative Examples 1 to 5 2+ The activated red afterglow material is a sample, and the structure and fluorescence performance of the sample are tested as follows: Test 1: Structural analysis. Taking the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2 as examples, X-ray diffraction test was performed. The test results are as follows: Figure 1 shown. Figure 1 In the figure, compared with the standard hexagonal SrZnOS with ICSD number 431819, the X-ray diffraction patterns of the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2 all show hexagonal SrZnOS, indicating that the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2 were successfully synthesized and no second phase was produced.

[0083] Taking the sample of Example 2 as an example, the morphology and element distribution test were carried out, and the results were as follows: Figure 2 shown. Figure 2 The results of Figure (a) show that the sample of Example 2 has an irregular polyhedral structure with an average particle size of about 5 μm. Figure 2 Figures (b) to (h) confirm that Sr, Zn, O, and S are uniformly distributed in the crystal. Due to the low doping levels of Eu and Dy, they cannot be clearly identified in the mapping.

[0084] Test 2: Fluorescence performance analysis. Comparative analysis of the afterglow characteristics of the samples from Examples 1 to 3 was performed. Figures 3 to 5 The samples of Example 1 and Example 3 use ultraviolet light with a charging wavelength of 274 nm, and the sample of Example 2 uses blue light with a charging wavelength of 468 nm.

[0085] The sample of Example 2 shows about 3 times and 7 times the afterglow enhancement relative to the samples of Example 1 and Example 3, as shown in FIG. Figure 3 ; Example 2 sample shows the longest afterglow duration, greater than 40 minutes, such as Figure 4 In addition to the enhanced afterglow intensity and extended life, by comparing the afterglow emission spectrum test results of the samples of Examples 1 to 3, it can be seen that the afterglow emission spectrum of the sample of Example 2 shows a broadband with a peak at 620nm, resulting in an afterglow output color of red. The afterglow emission spectra of the samples of Examples 1 and 3 also show a broadband, but the peak is at 530nm, and the afterglow output color is green. Figure 3 In order to reveal the trap characteristics and mechanism of the samples of Examples 1 to 3 controlling the afterglow characteristics, Figure 5 The thermoelectric curves of the samples of Examples 1 to 3 are shown. Before testing the thermoelectric curves, the samples were pre-irradiated with UV light for 5 minutes, and then the thermoelectric curves of the samples were measured after waiting for 1 minute. Figure 5As shown, the sample of Example 2 has the highest trap density and deeper trap distribution, which explains why the sample of Example 2 obtains the strongest and brightest afterglow.

[0086] The afterglow emission spectra, afterglow decay curves and thermal release curves of the samples of Examples 4 to 6 are compared respectively. Figures 6 to 8 The samples of Examples 4 to 6 were all pre-irradiated with 365nm ultraviolet light. The afterglow characteristics of the samples were studied, and the results showed that, in the samples of Examples 4 to 6, the SrZnOS matrix material exhibited the best afterglow performance within the studied doping ion range, i.e., the afterglow intensity was the highest and the duration was the longest. Furthermore, red afterglow can be easily obtained in the SrZnOS matrix material through doping.

[0087] Table 1 Afterglow performance of samples of Examples 1 to 6

[0088] Through the Eu in Examples 4 to 6 2+ and Mn 2+ The afterglow performance comparison of the three co-doped samples shows that the long afterglow luminescence intensity of SrZnOS: 0.5% Eu, 0.5% Mn in Example 5 is 4 times higher than that in Example 4 and Example 6. Figure 6 ; and the long afterglow lasts longer, such as Figure 7 This long afterglow is attributed to the parity-allowed Eu 2+ 5d→4f transition, rather than the spin-forbidden Mn 2+ By comparing the spectra of the samples of Examples 4 to 6, it can be inferred that Eu with an ionization energy of 24.1 eV 2+ Acts as a luminescence center, and Mn with an ionization energy of 33.7 eV 2+ Acts as a defect generator. Figure 8 Compared with the samples of Examples 4 and 6, the trap density in the sample of Example 5 is enhanced, which further illustrates that Eu 2+ and Mn 2+ synergistic effect in promoting efficient charge carrier capture-release cycles.

[0089] The present invention uses HSE06 hybrid functional calculation to determine the band structure and state density distribution diagram of the SrZnOS matrix material, such as Figure 9 As shown. Hexagonal SrZnOS is a direct band gap material. Figure 9 Figure (a) shows that the band gap is 3.58eV, which is a typical wide band gap material. Figure 9Density of states analysis (b) of SrZnOS reveals that the orbital composition of the density of states indicates that the valence band maximum is composed of S-3p and O-2p states, while the conduction band minimum is composed of Zn-4s states. Furthermore, the conduction band minimum and valence band maximum in SrZnOS exhibit an energy window of approximately 1 eV. This result indicates that both electrons and holes have small effective masses and large ionic mobility, explaining the rapid transport of charge carriers, such as electrons and holes, during thermally or photoluminescent luminescence, supporting its potential as a luminescent host material.

[0090] The photoluminescence spectra, afterglow emission spectra, afterglow decay curves and thermal release curves of the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2 are compared respectively. The test results are shown in Figures 10 to 13 The results of the photoluminescence and afterglow properties of the samples show that the sample of Example 2 exhibits the best photoluminescence and afterglow performance compared to the samples of Example 5, Comparative Examples 1, and Comparative Examples 2. Specifically, the afterglow intensity is the highest and the duration is the longest, exceeding 40 minutes. Furthermore, the integrated intensity of the pyrolysis curve of the sample of Example 2 is approximately five times higher than that of the other three samples, indicating a significant increase in trap density.

[0091] Table 2 Comparison of fluorescence properties of samples

[0092] Note: “-” indicates no relevant data.

[0093] Figure 14 The thermoelectric curves of the samples of Example 2, Example 7 to Example 9 and Comparative Example 3 at 620nm are shown. 2+ In the sample, Ln 3+, Ln = dual-doping and tri-doping of Dy, Ho, Nd, or Er, and Cu is added to modulate defects. The sample in Comparative Example 3 exhibits a distinct broadband region of traps in its pyrolysis curve, but its trap density remains very weak compared to that of the sample in Example 2, further highlighting the advantages of the sample in Example 2, which possesses the highest trap density and deeper trap distribution. A quantitative comparison of the pyrolysis intensity of Example 2 with that of Examples 7 to 9 and Comparative Example 3 reveals that the overall pyrolysis intensity of Example 2 is approximately five times higher, indicating a significant enhancement in trap density. The trap depths of Trap I, Trap II, and Trap III, i.e., the three peak temperatures in the pyrolysis curve, reflect the trap depths of released carriers. Using the equation E = (0.94lnβ + 30.09) × kTm, the trap depths are estimated to be 0.77 eV, 0.89 eV, and 1.03 eV, respectively. Here, E represents the trap depth, lnβ represents the natural logarithm, β represents the frequency factor, k represents the Boltzmann constant, and Tm represents the peak temperature. In summary, it can be concluded that the sample of Example 2 has the best energy storage and the strongest thermal stimulation signal, suggesting that it is suitable as a multimodal medium material for information encryption.

[0094] The effect of annealing atmosphere on the afterglow characteristics of the sample of Example 2 was further studied. The samples of Example 2, Comparative Example 4 and Comparative Example 5 were prepared under nitrogen atmosphere, reducing atmosphere and air atmosphere respectively to obtain samples with the same chemical formula SrZnOS: 0.5% Eu, 0.5% Dy. The photoluminescence spectrum, photoluminescence excitation spectrum, afterglow emission spectrum, afterglow decay curve and thermal release curve were characterized. Figures 15 to 18 .exist Figures 16 to 18 In the embodiment 2 and the comparative example 5, the samples adopt the blue light with the charging wavelength of 468nm, and the sample of the comparative example 4 adopts the violet light with the charging wavelength of 274nm.

[0095] Figure 15 and Figure 16 showed that the two samples treated under nitrogen and reducing atmospheres showed almost the same 2+ 4f 6 5d 1 →4f 7 In sharp contrast to the above, Eu after air annealing 3+ It shows a parity-forbidden 4f-4f weak transition with peaks at 590nm and 615nm, such as Figure 15 Obviously, in Figure 16 In the afterglow emission spectrum, the sample of Example 2 under nitrogen atmosphere has the strongest luminescence, and the afterglow luminescence intensity is almost 5 times or 10 times that of the samples of Comparative Examples 4 and 5.

[0096] Figure 17 and Figure 18Among them, the sample of Example 2 has the longest afterglow duration, which can reach more than 40 minutes, and the highest thermal release curve integrated intensity. Figure 18 It shows that under reducing conditions, the trap density reaches a maximum value at around 399K, while the sample under nitrogen atmosphere is dominated by traps centered at 374K. Only a weak trap density can be observed under air atmosphere. These results indicate that there is a deeper trap density in the samples treated under nitrogen atmosphere. This explains why the luminescence performance and afterglow characteristics of SrZnOS:0.5%Eu,0.5%Dy in nitrogen atmosphere are much better than those in reducing atmosphere and air atmosphere. Moreover, the sample of Example 2 is charged with sunlight and common visible light sources such as mobile phone flash, LED light and computer screen light. When the charging light source is turned off, a strong red afterglow can be observed, as shown in the figure below. Figure 19 .

[0097] The sample of Example 2 and commercial SrAl2O4:0.5%Eu,0.5%Dy green afterglow phosphor were pre-irradiated at 254nm, 365nm and 468nm respectively. Compared with the well-known commercial SrAl2O4:0.5%Eu,0.5%Dy green afterglow phosphor, the sample of Example 2 produced red fluorescence characteristics with the same intensity as the commercial afterglow blue-green phosphor at the excitation wavelengths of 254nm, 356nm and 468nm, as shown in FIG. Figure 20 , with a comparable afterglow duration of more than 40 minutes. In particular, the red afterglow intensity of the sample in Example 2 under 468nm blue light excitation is 1.5 times higher than that of the blue-green emitting commercial SrAl2O4:0.5%Eu,0.5%Dy phosphor, suggesting the commercial value of SrZnOS:0.5%Eu,0.5%Dy.

[0098] Combined with the above analysis, the photoluminescence, afterglow luminescence, thermally stimulated luminescence and mechanical luminescence mechanisms in the sample of Example 2 can be explained based on the energy level structure diagram, as shown in FIG. Figure 21 When Eu 2+ When the ground state 4f electrons are excited to the 5d state under 485nm blue light, some of the electrons directly jump back to the 4f ground state and emit photoluminescence, which is recorded as process 1; while the other part of the electrons are thermally ionized to the conduction band under the environmental thermal disturbance, resulting in Eu 3+ Formation; the electrons to the conduction band migrate within the conduction band until they are 3+ The trap capture, recorded as process 2, completes the trap energy storage, resulting in Dy 3+ Transition to Dy 2+ , Dy 2+ The ground state of Eu is located 0.9 eV below the bottom of the conduction band, which agrees well with the experimentally determined trap depth of about 0.89 eV to 1.03 eV. 3+ The holes in the valence band can also be absorbed by Sr 2+The valence band of the vacancy is captured, which is process 2. Under appropriate thermal or mechanical stimulation, the trapped energy level carriers overcome the potential barrier and re-participate in conduction and recombination luminescence, which is recorded as process 3, resulting in 620nm orange-red afterglow luminescence, thermally stimulated luminescence or mechanical luminescence, which is recorded as process 4. The afterglow enhancement mechanism of SrZnOS:0.5%Eu,0.5%Dy can be understood as: by doping Eu with different electronegativity 2+ and Dy 3+ The layered electron-hole trap structure, Dy Sr • and V Sr / V Zn , which serve as the positive and negative electrodes of the original battery respectively to form a bistable microelement battery trap structure, greatly enhancing the trap density and charge carrier capacity of the material.

[0099] Based on the excellent excitation fluorescence properties of the sample in Example 2 and commercial SrAl2O4: 0.5% Eu, 0.5% Dy, it is used as an optical information encryption medium to simulate the fluorescence photos of optical information encryption writing and multi-mode reading, as shown in the figure. Figure 22 shown.

[0100] Figure 22 Figure (a) shows the structure of the design of the "Mermaid Offering Pearls" pattern. The red mermaid is SrZnOS:0.5%Eu,0.5%Dy, and the green pearl is SrAl2O4:0.5%Eu,0.5%Dy. Figure 22 (b) shows that by adjusting the wavelength of light, the wavelength range is 200-550nm, and the pattern responds at 254, 365, 395, 468 and 500nm. Under the irradiation of ultraviolet to blue-green light, the pattern shows bright red fluorescent mermaid and green pearl. In addition to seeing the photoluminescent pattern, Figure 22 In (c) to (e), the red mermaid and green pearl afterglow patterns can be easily observed with the naked eye, but compared Figure 22 (d) and (e) afterglow duration, Figure 22 The afterglow in (c) can still be seen clearly after 40 minutes. The reason is that the charging light source is different. Figure 22 The afterglow photo of (c) is charged with UV light, while Figure 22 (d) is the mobile phone light charging, Figure 22 (e) is sunlight charging. This shows that by changing the wavelength, from UV to blue-green light or different visible light sources, such as mobile phone lights or sunlight as charging sources, multimodal optical information encryption can be achieved.

[0101] In addition, based on the excellent optical properties of the sample of Example 2, the powdering method can be used to facilitate the development of latent fingerprints. The red fingerprint afterglow fluorescence pattern obtained under 365nm ultraviolet light is as follows: Figure 23 , by magnifying it with an optical microscope Figure 23 The fingerprint afterglow pattern in (a) can distinguish five fingerprint microstructure features: bucket pattern 1, ridge 2, pore 3, lake 4, and bifurcation 5. Figure 23 (b) to (f). And by further magnifying the fingerprint scale of ridges 2 and pores 3, with a scale of 20μm to 500μm, the width, boundary and spacing of the ridges can be intuitively displayed with higher resolution, such as Figure 23 The above results show that the advanced fingerprint recognition technology of the present invention can more deeply understand and recognize fingerprints and can be applied to latent fingerprint recognition.

[0102] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A kind of Eu 2+ Activated red afterglow material, characterized in that The Eu 2+ The chemical formula of the activated red afterglow material is XZnOS: x M; where X is Ca 2+ 、Sr 2+ and Ba 2+ At least one of; M is Eu 2+ or Eu 2+ With Dy 3+ 、Mn 2+ 、Ho 3+ 、Nd 3+ 、Er 3+ 、Cu 2+ A mixture of; and 0< x ≤1%; The Eu 2+ The activated red afterglow material is based on XZnOS with hexagonal multi-cation coordination environment as the matrix material, M as the activation ion source, and by selectively doping the activation ion source into the lattice of the matrix material, a red afterglow material is formed with Eu 2+ As cathode, Dy 3+ 、Ho 3+ 、Nd 3+ 、Er 3+ 、Mn 2+ and Cu 2+ At least one of the anodes is a primary battery structure redox reaction system.

2. Eu according to claim 1 2+ Activated red afterglow material, characterized in that Artificial ultraviolet light, artificial visible light or natural light is used as the charging light source, the Eu 2+ The activated red afterglow material is excited to exhibit multi-mode luminescence under the irradiation of a charging light source.

3. Eu according to claim 1 2+ Activated red afterglow material, characterized in that Artificial ultraviolet light, artificial visible light or natural light is used as the charging light source, the Eu 2+ The activated red afterglow material stores light energy when exposed to a charging light source. After the charging light source is removed, it continues to emit red afterglow visible to the naked eye for 40 to 60 minutes.

4. Eu according to claim 1 2+ Activated red afterglow material, characterized in that The Eu 2+ The particle size of the activated red afterglow material is ≤5μm.

5. A kind of Eu 2+ The method for preparing an activated red afterglow material is characterized in that: The following steps are involved: Eu according to any one of claims 1 to 4 2+ Chemical expression of activated red afterglow material XZnOS: x The stoichiometric ratio of M is such that the metal inorganic salt corresponding to the matrix material and the metal oxide corresponding to the activation ion source are used as raw materials, the metal inorganic salt corresponding to the matrix material and the metal oxide corresponding to the activation ion source are mixed, and then ground to obtain a mixed powder; The mixed powder is sintered under a protective atmosphere to allow the activated ion source to be doped into the lattice of the matrix material to form a Eu 2+ As cathode, Dy 3+ 、Ho 3+ 、Nd 3+ 、Er 3+ 、Mn 2+ and Cu 2+ At least one of the anodes in the galvanic cell structure redox reaction system is cooled to room temperature and ground to obtain Eu 2+ Activated red afterglow material.

6. Eu according to claim 5 2+ The method for preparing an activated red afterglow material is characterized in that: The sintering treatment temperature is 850°C to 1050°C; the metal inorganic salt corresponding to the matrix material is a carbonate, nitrate or sulfide corresponding to the metal element in the matrix material, and at least one metal inorganic salt is a sulfide; the protective atmosphere is an inert atmosphere; and the particle size of the mixed powder is ≤5μm.

7. A kind of Eu 2+ The activated red afterglow material is used as a light-storage and energy-storage fluorescent material for applications in high-throughput information storage and encryption, and is characterized in that: The Eu 2+ The activated red afterglow material is Eu as described in any one of claims 1 to 4 2+ Activated red afterglow material.

8. Eu according to claim 7 2+ The activated red afterglow material is used as a light-storage and energy-storage fluorescent material for applications in high-throughput information storage and encryption, and is characterized in that: The specific application method is: Artificial ultraviolet light, artificial visible light or natural light is used as the charging light source, the Eu 2+ The activated red afterglow material acts as a light-storage and energy-storage fluorescent material. It stores light energy when exposed to a charging light source. After the charging light source is removed, it continuously emits a red afterglow visible to the naked eye for 40 to 60 minutes, exhibiting multi-mode luminescence.

9. A kind of Eu 2+ The activated red afterglow material is used as a light-storage energy-storage fluorescent material for latent fingerprint recognition, characterized in that: The Eu 2+ The activated red afterglow material is Eu as described in any one of claims 1 to 4 2+ Activated red afterglow material.

10. Eu according to claim 9 2+ The activated red afterglow material is used as a light-storage energy-storage fluorescent material for latent fingerprint recognition, characterized in that: The specific application method is: Artificial ultraviolet light, artificial visible light or natural light is used as the charging light source, the Eu 2+ The activated red afterglow material acts as a light-storing and energy-storing fluorescent material. It stores light energy when exposed to a charging light source. After the charging light source is removed, it continuously emits red afterglow imaging visible to the naked eye for 40 to 60 minutes, revealing latent fingerprints.

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