A Eu 2+ Activated red afterglow materials, their preparation methods and applications

Abstract

This invention relates to the field of inorganic light-storing functional materials technology, specifically to a Eu... 2+ Activated red afterglow material, its preparation method, and its application. The red afterglow material is obtained by doping an activated ion source into the matrix material lattice using XZnOS in a hexagonal multi-cation coordination environment. The chemical formula of the red afterglow material is XZnOS: x M; where X is Ca 2+ 、Sr 2+ and Ba 2+ At least one of them; M is Eu 2+ Or Eu 2+ With Dy 3+ Mn 2+ Ho 3+ 、Nd 3+ Er 3+ Cu 2+ The present invention selects XZnOS, which has a multi-lattice cation and a layered structure, as the matrix material. By selecting dual dopants, it designs and synthesizes polar defect structures with lattice-induced electron-hole defect pairs, thereby realizing a bistable high-density trap, high-capacity carrier storage, and high-brightness, long-lifetime afterglow fluorescence optical functional material.

Description

Technical Field

[0001] This invention relates to the field of inorganic light-storing functional materials technology, specifically to a Eu... 2+ Activated red afterglow materials, their preparation methods, and applications. Background Technology

[0002] Red afterglow materials, as a type of multimode fluorescent material, have broad application prospects in fields such as biomedicine, food safety detection, information storage and encryption, potential fingerprint recognition, low-light illumination, signal lights, optoelectronic devices, and defense technology, making them a cutting-edge research hotspot in the field of luminescent materials. In the area of ​​red and near-infrared luminescent devices, while traditional halogen lamps and tungsten halogen lamps have played a crucial role in related fields, they still have many fundamental limitations. For example, thermal runaway leads to operational instability, electro-optical conversion efficiency is less than 5%, background fluorescence interference is severe, and their size is incompatible with miniaturized systems, limiting their further application.

[0003] With the continuous emergence of new afterglow materials, based on their natural multimode properties, afterglow materials currently have broad application prospects in fields such as fourth-generation information storage and encryption, and potential fingerprint recognition. 2+ Its 4f-5d parity-allowed transition makes it an important afterglow luminescence center. In particular, SrAl₂O₄:Eu 2+ ,Dy 3+ Following reports of its commercially viable green afterglow lasting up to 12 hours, a surge of research into long-afterglow luminescent materials was sparked. In the two decades that followed, research focused on Eu... 2+ Activated afterglow materials such as aluminates and silicates have been developed, such as those with emission wavelengths of λ. mon =440nm CaAl2O4:Eu 2+ ,Nd 3+ Emission wavelength λ mon =490nm Sr4Al 14 O 25 Eu 2+ ,Dy 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ And so on. It has also achieved great commercial success in the civilian sector, particularly in emergency signs, safety indicators, luminescent coatings, and dials. Eu 2+ Significant progress has been made in activated blue and green afterglow luminescent materials. However, regrettably, materials based on Eu... 2+ The development of long-afterglow luminescent materials that activate red and near-infrared light faces significant challenges, especially compared to Sr4Al. 14 O 25 Eu 2+ ,Dy3+ Commercial green afterglow powders suffer from the human eye's insensitivity to the 620nm–750nm red spectrum. Even at the same intensity, red afterglow powders still fail to meet application targets, and the aforementioned factors further exacerbate this challenge.

[0004] Considering 4f 7 →4f 6 5d 1 Eu transition 2+ Unlike the 4f-4f transitions of trivalent rare-earth ions, the luminescence of the luminescent center is significantly influenced by the local crystal field environment, exhibiting a broadband emission characteristic dependent on 3d splitting under varying crystal field strengths. The 5d orbital is affected by multiple factors, and the excitation and emission energies can be modulated by altering the composition and structure of the matrix crystal. Eu 2+ Emission spectral characteristics depend on the local coordination environment. Specifically, based on crystal field theory, changes in the bond length between the activator and the anion significantly affect the spectrum. For example, Eu... 2+ With O 2- Shortening the bond length enhances crystal field splitting and electron cloud rearrangement, leading to a redshift in the spectrum; conversely, lengthening the bond length causes a blueshift. However, achieving near-infrared emission requires very strong crystal field splitting and... 2+ The large center of gravity shift associated with ions makes achieving near-infrared emission a significant challenge. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides an Eu 2+ Activated red afterglow materials, their preparation methods, and applications.

[0006] Compared to the ongoing efforts to achieve Eu in aluminates, silicates and their oxides 2+ Activated afterglow material, this invention focuses on Eu 2+ Activated sulfur oxide (XZnOS) crystals, where X is at least one of Ca, Sr, and Ba. For example, CaZnOS, SrZnOS, and BaZnOS have attracted considerable attention due to their high rare-earth doping compatibility caused by their multi-cation lattice sites and layered polar compound characteristics. XZnOS possesses a wide bandgap greater than 3.3 eV, a high piezoelectric coefficient, and excellent physicochemical stability. Furthermore, unlike salts and oxides, XZnOS has two anionic lattice sites with different electronegativity, allowing for convenient tuning of its polarity and bandwidth through doping and experimental processes. Therefore, these advantages make XZnOS a promising candidate material for both traditional photoluminescence and upconversion applications, as well as for novel stress-luminescent materials.

[0007] However, although rare-earth / transition metal-doped XZnOS phosphors exhibit tunable multilevel luminescence properties under specific excitation conditions, achieving near-infrared emission requires strong crystal field splitting and interaction with Eu. 2+ A large ion-related shift in the center of gravity will increase Eu 2+ The difficulty in preparing activated red afterglow materials. Considering S 2- and O 2- Layered polar lattices, with the aim of realizing Eu in XZnOS. 2+ The preparation of activated red afterglow phosphors can be further applied to information storage and encryption, as well as potential fingerprint recognition, thereby filling the gap in Eu... 2+ Activate the blank space of the red afterglow material.

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

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

[0010] This invention selects XZnOS, which has multiple cation and anion lattice sites and exhibits a layered structure, as the matrix material. Using M as the activation ion source, by doping the activation ion source into the matrix material's lattice, the aim is to construct a structure with high defect density and the ability to achieve layered isolation of electron-hole defects. This forms a redox reaction system with a galvanic cell structure for redox layered reactions, thereby constructing a bistable trap structure for positive and negative electrodes—a galvanic cell-electrolyte cell. This achieves separate storage and activation of positive and negative charges from the source, enabling the preparation of Eu with high-capacity photoluminescence 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, wherein the Eu... 2+ The activated red afterglow material exhibits multimode luminescence when excited by a charging light source.

[0012] Ultraviolet excitation is the standard excitation mode for afterglow. The Eu of this invention... 2+ The activated red afterglow material can be excited to exhibit multimode luminescence under the illumination of a charging light source, which can be 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, wherein the Eu... 2+ The activated red afterglow material stores light energy when irradiated by a charging light source, and continues to emit a visible red afterglow for 40 to 60 minutes after the charging light source is removed.

[0014] The luminescence enhancement mechanism of this invention originates from a micro-elemental photochemical cell formed within the crystal lattice based on doping, wherein Eu 2+ In addition to Eu, M acts as the cathode. 2+ Other metal ions besides those used in this invention act as the anode. 2+ The activated red afterglow material can be excited to exhibit multimode luminescence under the illumination of a charging light source, demonstrating excellent multimode luminescence performance. This is comparable to commercially available SrAl2O4:Eu... 2+ ,Dy 3+ Compared to green afterglow phosphors, the Eu of this invention 2+ The activated red afterglow material exhibits significantly stronger near-infrared long afterglow luminescence, and maintains stable and strong photoluminescence performance even at high temperatures during and after irradiation by a charging light source.

[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 an Eu 2+ The preparation method of activated red afterglow material includes the following steps:

[0017] According to Eu 2+ The chemical formula for activated red afterglow material is XZnOS: x The stoichiometry of M is determined by using the inorganic metal salt corresponding to the matrix material and the metal oxide corresponding to the activated ion source as raw materials. The inorganic metal salt corresponding to the matrix material and the metal oxide corresponding to the activated ion source are mixed and then ground to obtain a mixed powder. The mixed powder is then sintered under a protective atmosphere to dope the activated ion source into the lattice of the matrix material, constructing a structure based on Eu. 2+ As the cathode, Dy 3+ Ho 3+ 、Nd 3+ Er 3+ Mn 2+ and Cu 2+ A redox reaction system with at least one of the following as the anode in a galvanic cell structure is cooled to room temperature and then ground to obtain Eu. 2+ Activated red afterglow material.

[0018] This invention, by optimizing experimental process parameters to control bandwidth and local lattice symmetry, achieves for the first time Eu... 2+ Activated red afterglow material. Eu prepared in this invention. 2+ The activated red afterglow material can interact with Eu 2+ Activated green SrAl2O4:Eu 2+ ,Dy 3+ And blue Sr4Al 14 O 25 Eu 2+ ,Dy 3+ Together they constitute Eu 2+ It is a three-primary-color afterglow material, filling Eu 2+ Activate the blank space of the red afterglow material.

[0019] Preferably, the sintering temperature is 850℃~1050℃; the inorganic metal salt corresponding to the matrix material is the carbonate, nitrate or sulfide corresponding to the metal element in the matrix material, and at least one inorganic metal salt is a sulfide; the protective atmosphere is an inert atmosphere; the particle size of the mixed powder is ≤5μm.

[0020] The inorganic metal salts corresponding to the matrix material are the carbonates or nitrates of element X and ZnS.

[0021] When selecting the raw materials for the preparation of the activation ion source, this invention takes into account the stability of the activation ion source and preferably selects oxides containing the corresponding elements, such as Eu2O3, Dy2O3 or MnO.

[0022] In this invention, the protective atmosphere is an inert atmosphere. During the preparation process, this invention uses an inert atmosphere, such as nitrogen, to protect the M ions, which act as defect-creating ions, allowing their variable valence ions to coexist. This effectively protects the bistable defect density, thereby comprehensively improving the energy storage capacity and obtaining a red, ultra-long, ultra-bright afterglow emitting material with an effective trap density.

[0023] The third aspect of the present invention provides an Eu 2+ Activated red afterglow material is used as a photoluminescent material for high-throughput information storage and encryption applications. 2+ The activated red afterglow material is Eu as described in the first aspect. 2+ Activated red afterglow material.

[0024] Preferred, specific application method:

[0025] Using artificial ultraviolet light, artificial visible light, or natural light as the charging light source, the Eu 2+ The activated red afterglow material, as a light-storing fluorescent material, stores light energy under the illumination of a charging light source. After the charging light source is removed, it continues to emit a visible red afterglow for 40 to 60 minutes, exhibiting multimode luminescence.

[0026] In this 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; artificial ultraviolet light source is an ultraviolet lamp; artificial visible light source is a mobile phone light, etc.

[0027] This invention will Eu 2+ Activated red afterglow material is used as a photoluminescence material for photonic information storage and encryption, enabling multi-mode information storage and encryption.

[0028] The fourth aspect of the present invention provides an Eu 2+ The activated red afterglow material is used as a phosphorescent material for potential fingerprint recognition applications. 2+ The activated red afterglow material is Eu as described in the first aspect. 2+ Activated red afterglow material.

[0029] Preferred, specific application method:

[0030] Using artificial ultraviolet light, artificial visible light, or natural light as the charging light source, the Eu 2+ The activated red afterglow material, as a light-storing fluorescent material, stores light energy under the illumination of a charging light source. After the charging light source is removed, it continuously emits naked-eye visible red afterglow imaging for 40 to 60 minutes, revealing potential fingerprints.

[0031] This invention will Eu 2+The activated red afterglow material is used as a light-emitting material for latent fingerprint recognition, which can present latent fingerprints with high resolution.

[0032] The beneficial effects of this invention are:

[0033] 1. This invention selects XZnOS, which has multiple cation and anion lattice sites and a layered structure, as the matrix material and M as the activation ion source. By doping the activation ion source into the lattice of the matrix material, the aim is to construct a structure with high defect density and the ability to achieve layered isolation of electron-hole defects, forming a redox reaction system with a redox layered reaction structure, thereby achieving separate storage and activation of positive and negative charges from the source, and thus preparing a red afterglow material with high capacity light storage characteristics.

[0034] 2. The luminescence enhancement mechanism of this invention originates from a micro-elemental photochemical cell formed within the crystal lattice based on doping, wherein Eu 2+ In addition to Eu, M acts as the cathode. 2+ Other metal ions besides those used in this invention act as the anode. 2+ The activated red afterglow material not only exhibits excellent multimode luminescence performance, but also shows significantly stronger near-infrared long afterglow luminescence. It can still maintain stable and strong photoluminescence performance during and after irradiation by a charging light source.

[0035] 3. The Eu of the present invention 2+ Activated XZnOS red afterglow material can be used as a light-storing fluorescent material to store light energy from artificial ultraviolet light sources, artificial visible light sources, or natural light sources.

[0036] 4. The 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 a red afterglow visible to the naked eye for more than 40 minutes, which can be conveniently applied to high-throughput information storage and encryption or potential fingerprint recognition.

[0037] 5. The red afterglow material of the present invention is prepared by the traditional high-temperature solid-state method, which is simple to prepare, has a large output, and low cost. Attached Figure Description

[0038] Figure 1 The X-ray diffraction patterns are those of the samples from Examples 2, 5, Comparative Example 1, and Comparative Example 2.

[0039] Figure 2 The images shown are scanning electron microscope (SEM) images and energy-dispersive X-ray spectroscopy (EDX-ray spectroscopy) elemental distribution maps of the sample from Example 2. (a) and (b) are SEM images at different magnifications, respectively; (c) to (h) are the elemental distribution maps of the EDX spectra.

[0040] Figure 3 The afterglow emission spectra of the samples from Examples 1 to 3 are shown.

[0041] Figure 4 The afterglow decay curves are for the samples from Examples 1 to 3.

[0042] Figure 5 The pyrolysis curves are for the samples from Examples 1 to 3.

[0043] Figure 6 The afterglow emission spectra of the samples from Examples 4 to 6 are shown.

[0044] Figure 7 The afterglow decay curves are for the samples from Examples 4 to 6.

[0045] Figure 8 The pyrolysis curves are for the samples from Examples 4 to 6.

[0046] Figure 9 The diagram shows the band structure and density of states of the SrZnOS crystal material. (a) shows the band structure; (b) shows the density of states.

[0047] Figure 10 The photoluminescence emission spectrum and photoluminescence excitation spectrum of the samples from Examples 2, 5, Comparative Example 1 and Comparative Example 2 are shown.

[0048] Figure 11 The afterglow emission spectra of the samples from Examples 2, 5, Comparative Example 1, and Comparative Example 2 are shown.

[0049] Figure 12 The afterglow decay curves are for the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2.

[0050] Figure 13 The pyrolysis curves are for the samples of Example 2, Example 5, Comparative Example 1 and Comparative Example 2.

[0051] Figure 14 The pyrolysis curves are for the samples of Example 2, Examples 7 to 9, and Comparative Example 3.

[0052] Figure 15 The photoluminescence emission spectrum and photoluminescence excitation spectrum of the samples from Example 2, Comparative Example 4, and Comparative Example 5 are shown.

[0053] Figure 16 The afterglow emission spectra of the samples from Example 2, Comparative Example 4, and Comparative Example 5 are shown.

[0054] Figure 17The afterglow decay curves are for the samples of Example 2, Comparative Example 4, and Comparative Example 5.

[0055] Figure 18 The pyroelectric spectra are those of the samples from Example 2, Comparative Example 4, and Comparative Example 5.

[0056] Figure 19 The afterglow emission spectra of the samples from Example 2 are dependent on different charging light sources.

[0057] Figure 20 The afterglow emission spectra of the sample from Example 2 and commercial SrAl2O4:0.5%Eu,0.5%Dy green afterglow powder are shown.

[0058] Figure 21 This is a diagram illustrating the mechanisms of photoluminescence, afterglow luminescence, thermally excited luminescence, and mechanoluminescence in the sample of Example 2. The inset within the bandgap shows the defect structure.

[0059] Figure 22 The images show the multimodal optical information encryption patterns of the samples from Example 2 and commercial SrAl2O4:0.5%Eu,0.5%Dy phosphor films. (a) is the design structure of the "Mermaid Offering Pearls" pattern, with the red fish printed using SrZnOS:0.5%Eu,0.5%Dy and the green pearl printed using SrAl2O4:0.5%Eu,0.5%Dy; (b) are photoluminescence images under 254nm ultraviolet light, 365nm ultraviolet light, 395nm near-ultraviolet light, 468nm blue visible light, and 500nm blue-green visible light; (c) is the afterglow pattern image after 3 minutes of ultraviolet light excitation; (d) is the afterglow pattern image recorded at 5s, 1min, and 5min after illumination with a mobile phone light; and (e) is the afterglow pattern image recorded at 5s, 1min, and 5min after pre-illumination with sunlight.

[0060] Figure 23 The images show the fingerprint fluorescence of the sample used in Example 2 in potential fingerprint recognition. Among them, (b) to (f) are magnified views of marks 1 to 5 in (a); (g) to (j) are further magnified views of marks 2 and 3. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0062] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0063] Figures 1 to 23 In this context, the intensity refers to fluorescence intensity, and the wavelength refers to light wavelength. Before measuring the afterglow emission spectrum, afterglow decay curve, and pyroelectric curve, the sample was pre-irradiated with a charging light source of the corresponding wavelength for 3 or 5 minutes. mon Indicates the monitoring wavelength. λ charge Indicates the charging wavelength. λ ex Indicates the excitation wavelength.

[0064] It should be noted that in the matrix material of this invention, X is Ca. 2+ 、Sr 2+ and Ba 2+ At least one of the following; this invention is based on valence band engineering and achieves control over the band gap structure by designing isovalent ion substitution strategies. XZnOS can be viewed as CaZnOS, or based on CaZnOS, through Sr... 2+ Or Ba 2+ Replace all Ca 2+ This invention yields a series of matrix materials with different band gaps. Furthermore, by adjusting the doping of M, the obtained traps can be effectively controlled, thereby achieving control over Eu... 2+ The afterglow properties of the activated red afterglow material are adjusted.

[0065] This invention considers factors such as crystal structure and optimal electronic structure, and preferably uses SrZnOS as the matrix material. The chemical formula of the ultralong red afterglow material is SrZnOS: x M. Where M is Eu 2+ , or co-doped with at least one of rare earth ions; x The percentage of M in SrZnOS, and x =0.5%. Furthermore, to ensure the achievement of the control trap characteristic, this invention preferably uses Eu. 2+ The dopant acts as an ion source for doping-activated luminescence centers, Dy 3+ As Eu 2+ The auxiliary dopant is used to introduce defects.

[0066] To ensure that all components are thoroughly ground and mixed, the present invention preferably uses manual / ball milling for grinding, and grinds until all chemicals are completely and evenly mixed, for example, grinding time of 0.5h to 1h, to obtain mixed powder with a particle size ≤5μm.

[0067] To ensure that the doped ions maintain appropriate valence during the sintering process, this invention preferably performs sintering in an inert atmosphere, with a preferred sintering temperature of 950°C, lower than the sublimation temperature of the precursor raw materials, and a preferred sintering time of 6 hours, in order to achieve sufficient reaction of all components.

[0068] This invention compares products under different atmospheres by controlling the atmosphere, specifically by using a reducing atmosphere or air instead of an inert atmosphere. The core objective is to control the type and valence of traps. Results show that an inert atmosphere is optimal, preventing the reduction of high-valence traps and suppressing oxygen vacancies. This is a key step in controlling traps in this invention. Nitrogen is preferred as the inert atmosphere.

[0069] Taking into account the particle size factor of the prepared sample, the present invention further grinds the product obtained by sintering treatment. The grinding can be carried out by manual or mechanical ball milling, and the grinding is carried out until the sample particles are fine, about 0.5h to 1.0h, so that the particle size of the obtained product is ≤5μm.

[0070] The technical solution of the present invention will be further described below through specific embodiments.

[0071] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available.

[0072] Example 1

[0073] A Eu 2+ The activated red afterglow material has the chemical formula CaZnOS:0.5%Eu,0.5%Dy. Example 1 uses CaZnOS as the matrix material and introduces Eu... 2+ and Dy 3+ The specific preparation method is as follows: According to the stoichiometric ratio of CaZnO3:0.5%Eu,0.5%Dy, weigh out 0.1964g CaCO3, 0.3899g ZnS, 0.0035g Eu2O3, and 0.0037g Dy2O3, respectively. Mix the weighed CaCO3, ZnS, Eu2O3, and Dy2O3 thoroughly and grind 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 to obtain the Eu2O3 powder. 2+ Activated red afterglow material.

[0074] Example 2

[0075] A Eu 2+ The activated red afterglow material has the chemical formula SrZnOS:0.5%Eu,0.5%Dy. The only difference between Example 2 and Example 1 is that Example 2 uses Sr... 2+ Completely replace Ca 2+ That is, 0.5905g of SrCO3 was weighed out to replace 0.1964g of CaCO3 in Example 1.

[0076] Example 3

[0077] A Eu 2+ The activated red afterglow material has the chemical formula BaZnOS:0.5%Eu,0.5%Dy. The only difference between Example 3 and Example 1 is that Example 3 uses Ba... 2+ Completely replace Ca 2+ Weigh 0.3909g of BaCO3 instead of 0.1964g of CaCO3 from Example 1.

[0078] Example 4

[0079] A Eu 2+ The activated red afterglow material has the chemical formula 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+ 0.0007g MnO was used instead of 0.0037g Dy2O3 in Example 1.

[0080] Example 5

[0081] A Eu 2+ The activated red afterglow material has the chemical formula SrZnOS:0.5%Eu,0.5%Mn. The only difference between Example 5 and Example 2 is that Example 5 uses Mn... 2+ Completely replace Dy 3+ 0.0007g MnO was used instead of 0.0037g Dy2O3 in Example 1.

[0082] Example 6

[0083] A Eu 2+ The activated red afterglow material has the chemical formula BaZnOS:0.5%Eu,0.5%Mn. The only difference between Example 6 and Example 3 is that Example 6 uses Mn... 2+ Completely replace Dy 3+ 0.0007g MnO was used instead of 0.0037g Dy2O3 in Example 1.

[0084] Example 7

[0085] A Eu 2+ The activated red afterglow material has the chemical formula SrZnOS:0.5%Eu,0.5%Ho. The difference between Example 7 and Example 2 is only that Example 7 uses Ho... 3+ Completely replace Dy 3+ 0.0037g Ho2O3 was used instead of 0.0037g Dy2O3 in Example 2.

[0086] Example 8

[0087] A Eu 2+ The activated red afterglow material has the chemical formula SrZnOS:0.5%Eu,0.5%Nd. The only difference between Example 8 and Example 2 is that Example 8 uses Nd... 3+ Completely replace Dy 3+ 0.0033g Nd2O3 was used instead of 0.0037g Dy2O3 in Example 2.

[0088] Example 9

[0089] A Eu 2+ The activated red afterglow material has the chemical formula SrZnOS:0.5%Eu,0.5%Er. The difference between Example 9 and Example 2 is only that Example 9 uses Er... 3+ Completely replace Dy 3+ 0.0038g Er2O3 was used instead of 0.0037g Dy2O3 in Example 2.

[0090] Comparative Example 1

[0091] A Eu 2+ The activated red afterglow material has the chemical formula SrZnOS:0.5%Eu. Comparative Example 1 uses SrZnOS as a matrix and introduces Eu... 2+ Single doping was used to obtain the product. The specific preparation method is as follows: According to the stoichiometric ratio of SrZnSO3:0.5%Eu, 0.5905g SrCO3, 0.3899g ZnS, and 0.0035g Eu2O3 were weighed out. The weighed SrCO3, ZnS, and Eu2O3 were mixed and ground for 0.5h to obtain a mixed powder. The mixed powder was sintered at 950℃ for 6h under a N2 atmosphere. After cooling to room temperature, the sintered product was ground for 0.5h to obtain the Eu powder. 2+ Activated red afterglow material.

[0092] Comparative Example 2

[0093] A Eu 2+ The activated red afterglow material has the chemical formula SrZnOS:0.5%Eu,0.5%Dy,0.5%Mn. Comparative Example 2 uses SrZnOS as a matrix and introduces Eu... 2+ Mn 2+ and Dy 3+Triple doping was used to obtain the product. The specific preparation method is as follows: According to the stoichiometric ratio of SrZnO3:0.5%Eu, 0.5%Dy, and 0.5%Mn, 0.5875g SrCO3, 0.3899g ZnS, 0.0035g Eu2O3, 0.0007g MnO, and 0.0037g Dy2O3 were weighed out. The weighed SrCO3, ZnS, Eu2O3, MnO, and Dy2O3 were mixed thoroughly and ground for 0.5h to obtain a mixed powder. The mixed powder was sintered at 950℃ for 6h under a N2 atmosphere. After cooling to room temperature, the sintered product was ground for 0.5h to obtain the Eu powder. 2+ Activated red afterglow material.

[0094] Comparative Example 3

[0095] A Eu 2+ The activated red afterglow material has the chemical formula SrZnOS:0.1%Eu,0.5%Dy,0.5%Cu. Comparative Example 3 uses SrZnOS as a matrix and introduces Eu... 2+ Dy 3+ and Cu 2+ Triple doping was used to obtain the product. The specific preparation method is as follows: According to the stoichiometric ratio of SrZnOS:0.1%Eu,0.5%Dy,0.5%Cu, 0.2950g SrCO3, 0.1949g ZnS, 0.0035g Eu2O3, 0.0037g Dy2O3, and 0.0033g CuCl2·2H2O were weighed out. The weighed SrCO3, ZnS, Eu2O3, Dy2O3, and CuCl2·2H2O were mixed thoroughly and ground for 0.5h to obtain a mixed powder. The mixed powder was sintered at 950℃ for 6h under a N2 atmosphere. After cooling to room temperature, the sintered product was ground for 0.5h to obtain the Eu powder. 2+ Activated red afterglow material.

[0096] Comparative Example 4

[0097] A Eu 2+ The activated red afterglow material has the chemical formula SrZnOS:0.5%Eu,0.5%Dy. The only difference between Comparative Example 4 and Example 2 is that the nitrogen atmosphere in Comparative Example 4 is replaced with an air atmosphere in Example 2.

[0098] Comparative Example 5

[0099] A Eu 2+The activated red afterglow material has the chemical formula SrZnOS:0.5%Eu,0.5%Dy. The only difference between Comparative Example 4 and Example 2 is that the nitrogen atmosphere in Comparative Example 4 is replaced with a reducing atmosphere, which is a mixture of nitrogen and hydrogen, with a volume ratio of N2 to H2 of 95:5, denoted as N2&H2 mixture.

[0100] Eu prepared according to Examples 1 to 9 and Comparative Examples 1 to 5 2+ The activated red afterglow material was used as the sample, and the sample's structure and fluorescence properties were tested as follows:

[0101] Test 1: Structural Analysis. X-ray diffraction tests were performed on samples from Examples 2, 5, Comparative Example 1, and Comparative Example 2. The test results are as follows: Figure 1 As shown. Figure 1 In comparison with the standard hexagonal SrZnOS with ICSD number 431819, the X-ray diffraction patterns of the samples in Example 2, Example 5, Comparative Example 1 and Comparative Example 2 all show hexagonal SrZnOS, indicating that the samples in Example 2, Example 5, Comparative Example 1 and Comparative Example 2 were successfully synthesized and no second phase was generated.

[0102] Taking the sample from Example 2 as an example, morphology and elemental distribution tests were performed, and the results are as follows: Figure 2 As shown. Figure 2 Figure (a) shows that the sample from Example 2 has an irregular polyhedral structure with an average particle size of approximately 5 μm. Figure 2 Figures (b) to (h) confirm that Sr, Zn, O, and S are uniformly distributed in the crystal. Eu and Dy doping levels were not clearly identified in the mapping.

[0103] Test 2: Fluorescence Performance Analysis. The afterglow characteristics of the samples from Examples 1 to 3 were compared and analyzed, such as... Figures 3-5 In Example 1 and Example 3, the samples were charged with ultraviolet light at a wavelength of 274 nm, while the sample in Example 2 was charged with blue light at a wavelength of 468 nm.

[0104] The sample of Example 2, compared to the samples of Example 1 and Example 3, showed approximately 3-fold and 7-fold enhancement in afterglow, respectively. Figure 3 Example 2 shows the longest afterglow duration, greater than 40 minutes, such as... Figure 4 Besides the enhanced afterglow intensity and extended lifespan, a comparison of the afterglow emission spectrum test results of samples from Examples 1 to 3 shows that the afterglow emission spectrum of sample 2 exhibits a broadband pattern with a peak at 620 nm, resulting in a red afterglow output color. Samples from Examples 1 and 3 also exhibit a broadband pattern in their afterglow emission spectra, but with a peak at 530 nm, resulting in a green afterglow output color. Figure 3 To reveal the trapping characteristics and mechanism of the controlled afterglow properties of the samples in Examples 1 to 3, Figure 5 The pyroelectric curves of the samples from Examples 1 to 3 are shown. Before testing the pyroelectric curves, the samples were pre-irradiated with ultraviolet light for 5 minutes, and then the pyroelectric curves were measured after a 1-minute wait. Figure 5 As shown, the sample of Example 2 has the highest trap density and the deepest trap distribution. This explains why the sample of Example 2 obtained the strongest and brightest afterglow.

[0105] The afterglow emission spectra, afterglow decay curves, and pyroelectric curves of the samples from Examples 4 to 6 were compared respectively. The test results are as follows: Figures 6-8 The samples in 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, within the range of doping ions studied, the SrZnOS matrix material exhibited the best afterglow performance, i.e., the highest afterglow intensity and the longest duration. Furthermore, red afterglow was easily obtained by doping the SrZnOS matrix material.

[0106] Table 1. Afterglow performance of samples from Examples 1 to 6

[0107]

[0108] Through Eu in Examples 4 to 6 2+ and Mn 2+ A comparison of the afterglow performance of the three co-doped samples revealed that the long afterglow luminescence intensity of SrZnOS:0.5%Eu,0.5%Mn in Example 5 was 4 times higher than that in Examples 4 and 6. Figure 6 Furthermore, the afterglow lasts longer, such as... Figure 7 This long afterglow luminescence is attributed to parity-allowed Eu. 2+ The 5d→4f transition, rather than the spin-forbidden Mn 2+ Transition. Through systematic spectral comparison of the samples from Examples 4 to 6, the Eu ionization energy of 24.1 eV can be deduced. 2+ Mn acts as a luminescent center, with an ionization energy of 33.7 eV. 2+ It acts as a defect-inducing agent. And... Figure 8 In comparison with the samples of Examples 4 and 6, the enhanced trap density observed in the sample of Example 5 further illustrates the influence of Eu. 2+ and Mn 2+ It has a synergistic effect in promoting efficient charge carrier capture-release cycles.

[0109] This invention uses HSE06 mixed functional calculations to determine the band structure and density of states distribution of the SrZnOS matrix material, such as... Figure 9 As shown. Hexagonal SrZnOS is a direct bandgap material. Figure 9 Figure (a) shows a band gap of 3.58 eV, which is typical of a wide band gap material. Through analysis of... Figure 9 Analysis of the density of states in diagram (b) reveals that the orbital composition of SrZnOS shows that the valence band maxima are composed of S-3p and O-2p states, while the conduction band minimums are composed of Zn-4s states. Furthermore, the conduction band minimums and valence band maxima in SrZnOS exhibit an energy window of approximately 1 eV. This result indicates that both electrons and holes possess relatively small effective masses and large ion mobilities, explaining the rapid transport capabilities of charge carriers, such as electrons or holes, during thermally or photoluminescent processes, thus supporting its potential application as a luminescent matrix material.

[0110] The photoluminescence spectra, afterglow emission spectra, afterglow decay curves, and pyroelectric curves of the samples from Examples 2, 5, 1, and 2 are compared respectively. The test results are presented in [the table / document / etc.]. Figures 10-13 The results of the photoluminescence and afterglow characteristics studies 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 Example 1, and Comparative Example 2, i.e., the highest afterglow intensity and the longest duration, exceeding 40 minutes. Furthermore, the integrated intensity of the pyroluminescence curve of the sample of Example 2 is approximately 5 times higher than that of the other three samples, indicating a significantly enhanced trap density.

[0111] Table 2 Comparison of fluorescence properties of samples

[0112]

[0113] Note: "-" indicates no relevant data.

[0114] Figure 14 The image shows the pyroelectric curves at 620 nm for samples from Examples 2, 7-9, and Comparative Example 3. This was achieved using SrZnOS:Eu 2+ In the sample, Ln is co-doped 3+The samples were double-doped and triple-doped with Ln = Dy, Ho, Nd, or Er, and Cu was added to modulate defects. The pyroelectric curve of Comparative Example 3 showed a significant broadband region of traps, but its trap density was still very weak compared to the sample of Example 2. This further highlights the advantage of Example 2, which has the highest trap density and deeper trap distribution. A quantitative comparison of the pyroelectric intensity of Example 2 with Examples 7-9 and Comparative Example 3 showed that the overall pyroelectric intensity of Example 2 was increased by approximately 5 times, indicating a significantly enhanced trap density. The trap depths of traps I, II, and III, i.e., the three peak temperatures of the pyroelectric curves, reflect the trap depths releasing charge carriers. These depths were estimated using the equation E = (0.94lnβ + 30.09) × kTm, and were 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, the sample in Example 2 exhibits the best energy storage and the strongest thermal stimulation signal, suggesting its suitability as a multimodal medium material for information encryption.

[0115] The effect of the annealing atmosphere on the afterglow characteristics of the sample from Example 2 was further investigated. Samples from Example 2, Comparative Example 4, and Comparative Example 5 were prepared under nitrogen, reducing, and air atmospheres, respectively, yielding samples with the same chemical formula: SrZnOS:0.5%Eu,0.5%Dy. Their photoluminescence spectra, photoluminescence excitation spectra, afterglow emission spectra, afterglow decay curves, and pyroluminescence curves were characterized. Figures 15-18 .exist Figures 16-18 In the examples, the samples of Example 2 and Comparative Example 5 were charged with blue light at a wavelength of 468 nm, while the sample of Comparative Example 4 was charged with violet light at a wavelength of 274 nm.

[0116] Figure 15 and Figure 16 This indicates that the two samples treated under nitrogen and reducing atmospheres exhibited almost identical characteristics attributable to Eu. 2+ 4f 6 5d 1 →4f 7 The transitions in photoluminescence, photoluminescence excitation, and afterglow emission. In stark contrast, Eu after air annealing... 3+ This shows a parity-forbidden 4f-4f weak transition, with peak values ​​at 590nm and 615nm, such as... Figure 15 Obviously, in Figure 16 In the afterglow emission spectrum, the sample of Example 2 under a nitrogen atmosphere showed the strongest luminescence, with an afterglow emission intensity that was almost 5 or 10 times that of the samples of Comparative Example 4 and Comparative Example 5.

[0117] 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 pyrolysis curve integral intensity. Figure 18 The results show that under reducing conditions, the trap density reaches its maximum at around 399 K, while the samples under nitrogen atmosphere are dominated by traps centered at 374 K. Only a weak trap density was observed under air atmosphere. These results indicate that samples treated under nitrogen atmosphere have a deeper trap density. This explains why the luminescence performance and afterglow characteristics of SrZnOS:0.5%Eu,0.5%Dy are superior in nitrogen atmosphere compared to reducing and air atmospheres. Furthermore, when the samples of Example 2 are charged under sunlight and common visible light sources such as mobile phone flashlights, LED lights, and computer screen light, a strong red afterglow can be observed when the charging light source is turned off. Figure 19 .

[0118] The sample from Example 2 was pre-irradiated with commercial SrAl₂O₄:0.5%Eu,0.5%Dy green afterglow phosphor at 254 nm, 365 nm, and 468 nm, respectively. Compared with the well-known commercial SrAl₂O₄:0.5%Eu,0.5%Dy green afterglow phosphor, the sample from Example 2 exhibited the same intensity of red fluorescence characteristics as the commercial afterglow blue-green phosphor at excitation wavelengths of 254 nm, 356 nm, and 468 nm. Figure 20 The comparable afterglow duration is greater than 40 minutes. In particular, the red afterglow intensity of the sample in Example 2 under 468 nm 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.

[0119] Based on the above analysis, the mechanisms of photoluminescence, afterglow luminescence, thermally excited luminescence, and mechanoluminescence in the sample of Example 2 can be explained based on the energy level structure diagram, such as... Figure 21 When Eu 2+ When the ground-state 4f electrons are excited to the 5d state under 485nm blue light irradiation, some electrons directly transition back to the 4f ground state, emitting photoluminescence, denoted as process 1; while the other part of the electrons are thermally ionized to the conduction band under ambient thermal disturbance, resulting in Eu... 3+ Formation; electrons migrate within the conduction band until they are ionized by Dy. 3+ Traps are captured, denoted as process 2, and trap energy storage is completed, leading to Dy 3+ The transition to Dy 2+ Dy 2+ The ground state is located 0.9 eV below the bottom of the conduction band, which matches well with the experimentally determined trap depth of approximately 0.89 eV to 1.03 eV. Furthermore, some Eu... 3+ Holes can also be blocked by Sr through the valence band. 2+Vacancy band trapping, i.e., process 2. Under suitable thermal or mechanical stimulation, the trapped energy level carriers overcome the potential barrier and re-participate in conduction and recombination luminescence, denoted as process 3, resulting in 620nm orange-red afterglow luminescence, thermally excited luminescence, or mechanoluminescence, denoted 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+ A layered electron-hole trap structure, namely Dy, is introduced into the layered SrZnOS matrix lattice. Sr • and V Sr / V Zn These elements, acting as the positive and negative electrodes of the primary cell respectively, constitute a bistable micro-element battery trap structure, which greatly enhances the trap density and charging carrier capacity of the material.

[0120] Based on the excellent excitation fluorescence properties of the sample from Example 2 and commercially available SrAl2O4:0.5%Eu,0.5%Dy, it was used as an optical information encryption medium to simulate fluorescence images of optical information encryption writing and multi-mode readout, such as... Figure 22 As shown.

[0121] Figure 22 Figure (a) is a structural diagram of the design of the "Mermaid Offering Pearl" pattern. The red mermaid is made of SrZnOS:0.5%Eu,0.5%Dy and the green pearl is made of SrAl2O4:0.5%Eu,0.5%Dy. Figure 22 Figure (b) shows how, by adjusting the wavelength of light (ranging from 200 to 550 nm), the pattern responds at 254, 365, 395, 468, and 500 nm, from ultraviolet to blue-green light, resulting in a bright red fluorescent mermaid and a green pearl pattern. Besides the photoluminescent patterns, the pattern also exhibits... Figure 22 The red mermaid and green pearl glowing patterns in (c) to (e) are also easily visible to the naked eye, but compared to Figure 22 The duration of afterglow in (d) and (e), Figure 22 The afterglow photo in (c) is still clearly visible after 40 minutes. This is because the charging light source is different. Figure 22 The afterglow photograph in (c) was taken using a UV lamp, while Figure 22 (d) refers to charging the phone's light. Figure 22 (e) refers to solar charging. This illustrates that by changing the wavelength, from UV to blue-green light or different visible light sources, such as cell phone lights or sunlight, as the charging source, multimodal optical information encryption can be achieved.

[0122] Furthermore, based on the excellent optical properties of the sample in Example 2, latent fingerprint development can be conveniently performed using the powder-sprinkling method. The red fingerprint afterglow fluorescence pattern obtained under 365nm ultraviolet light irradiation, such as... Figure 23 Magnified using an optical microscope Figure 23 The fingerprint afterglow pattern in (a) reveals five fingerprint microstructural features: whorl 1, ridge 2, pore 3, lake 4, and bifurcation 5. Figure 23 (b) to (f). Furthermore, by enlarging the fingerprint scale of ridges 2 and pores 3, with a scale bar of 20μm to 500μm, the width, boundaries, and spacing of the ridges can be displayed intuitively at a higher resolution, such as... Figure 23 (g) to (j). The above results show that the advanced fingerprint recognition technology of the present invention can gain a deeper understanding and recognition of fingerprints, enabling its application to potential fingerprint recognition.

[0123] The above are merely 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 within the protection scope of the present invention.

Claims

1. A Eu 2+ The activated red afterglow material is characterized by, The Eu 2+ The chemical formula for the activated red afterglow material is XZnOS: x M; where X is Sr 2+ M is Dy 3+ and Ho 3+ At least one of them with Eu 2+ The mixture; and 0 < x ≤1%; The Eu 2+ The activated red afterglow material uses XZnOS with a hexagonal multi-cation coordination environment as the matrix material and M as the activation ion source. By selectively doping the activation ion source into the lattice of the matrix material, a Eu-based structure is constructed. 2+ As the cathode, Dy 3+ and Ho 3+ At least one of them is a galvanic cell structure redox reaction system with the anode.

2. The Eu according to claim 1 2+ The activated red afterglow material is characterized by, Using artificial ultraviolet light, artificial visible light, or natural light as the charging light source, the Eu 2+ The activated red afterglow material exhibits multimode luminescence when excited by a charging light source.

3. The Eu according to claim 1 2+ The activated red afterglow material is characterized by, Using artificial ultraviolet light, artificial visible light, or natural light as the charging light source, the Eu 2+ The activated red afterglow material stores light energy when irradiated by a charging light source, and continues to emit a visible red afterglow for 40 to 60 minutes after the charging light source is removed.

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

5. A Eu 2+ The method for preparing activated red afterglow material is characterized by, Includes the following steps: Eu according to any one of claims 1 to 4 2+ The chemical formula for activated red afterglow material is XZnOS: x The stoichiometric ratio of M is determined by using the inorganic metal salt corresponding to the matrix material and the metal oxide corresponding to the activated ion source as raw materials. The inorganic metal salt corresponding to the matrix material and the metal oxide corresponding to the activated ion source are mixed and then ground to obtain a mixed powder. The inorganic metal 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 inorganic metal salt is a sulfide. The particle size of the mixed powder is ≤5 μm. The mixed powder was sintered under a protective atmosphere to allow the activated ion source to be doped into the lattice of the matrix material, thus constructing a structure based on Eu. 2+ As the cathode, Dy 3+ and Ho 3+ A redox reaction system with at least one of the following as the anode in a galvanic cell structure is cooled to room temperature and then ground to obtain Eu. 2+ Activated red afterglow material; The sintering temperature is 850℃~1050℃; the protective atmosphere is an inert atmosphere.

6. A Eu 2+ The activated red afterglow material, used as a photoluminescent material for high-throughput information storage and encryption, is characterized by... 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.

7. The Eu according to claim 6 2+ The activated red afterglow material, used as a photoluminescent material for high-throughput information storage and encryption, is characterized by... The specific application method is as follows: Using artificial ultraviolet light, artificial visible light, or natural light as the charging light source, the Eu 2+ The activated red afterglow material, as a light-storing fluorescent material, stores light energy under the illumination of a charging light source. After the charging light source is removed, it continues to emit a visible red afterglow for 40 to 60 minutes, exhibiting multimode luminescence.

8. A Eu 2+ The activated red afterglow material, used as a phosphorescent material for potential fingerprint recognition applications, is characterized by... 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.

9. The Eu according to claim 8 2+ The activated red afterglow material, used as a phosphorescent material for potential fingerprint recognition applications, is characterized by... The specific application method is as follows: Using artificial ultraviolet light, artificial visible light, or natural light as the charging light source, the Eu 2+ The activated red afterglow material, as a light-storing fluorescent material, stores light energy under the illumination of a charging light source. After the charging light source is removed, it continuously emits naked-eye visible red afterglow imaging for 40 to 60 minutes, revealing potential fingerprints.

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