An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials, their preparation methods and applications

Abstract

This invention belongs to the field of long afterglow luminescent materials technology, and specifically discloses an ultra-broad spectrum Cs2CdCl4:xPb 2+ Long-afterglow luminescent materials, their preparation methods and applications, including Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials are based on Cs₂CdCl₄ and contain Pb 2+ It is a luminescent recombination center with the general chemical formula Cs₂CdCl₄:xPb 2+ Where 0.001 ≤ x ≤ 0.1. The Cs₂CdCl₄:xPb of this invention... 2+ The long-afterglow luminescent material exhibits high crystal chemical stability and can be effectively excited by 254nm ultraviolet light or X-rays, possessing a long-afterglow luminescence spectrum across an ultrawide wavelength range from UVB to visible light, with a long afterglow duration. It does not require harsh synthesis conditions involving high pressure and reduction; the synthesis can be carried out under ambient pressure using a solvothermal method and Cs₂CdCl₄:xPb. 2+ The required chemical raw materials can be used to synthesize Cs₂CdCl₄:xPb 2+ Long afterglow luminescent materials; Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials are simple to prepare and can be mass-produced industrially; Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials can be applied to fields such as optical anti-counterfeiting and wearable devices, and are unaffected by visible light.

Description

Technical Field

[0001] This invention belongs to the technical field of long-afterglow luminescent materials, specifically relating to an ultra-broad spectrum Cs₂CdCl₄:xPb 2 + Long-afterglow luminescent materials, their preparation methods, and applications. Background Technology

[0002] Long-afterglow luminescent materials are a class of materials that continue to emit light for a period of time after the excitation source is removed. Excited by ionizing radiation (such as X-rays or high-energy 254nm ultraviolet light), electrons in long-afterglow luminescent materials are excited to higher energy levels, typically in the excited state or conduction band. These excited electrons can directly transition or transfer via intermediate energy levels to trapped states within the material. When the external light source is removed, the electrons trapped in the traps are gradually released from the trapped states, gradually returning to lower energy levels, and eventually releasing light energy by transitioning to the ground state. This process produces the phenomenon of continuous luminescence, known as the long-afterglow effect. Long-afterglow luminescent materials are attracting increasing attention due to their potential applications in optoelectronic devices, life sciences, and wearable devices.

[0003] SrAl2O4:Dy 3+ It is a typical traditional long-afterglow luminescent material that has been applied in the lighting field. However, SrAl2O4:Dy 3+ Significant limitations remain, making it difficult to meet the diverse needs of practical applications. Firstly, SrAl2O4:Dy 3+ It primarily emits a long-lasting green glow, concentrated in the visible light range. Ambient light typically falls within the visible light spectrum, while SrAl2O4:Dy 3+ The luminescence signal of SrAl2O4:Dy is also typically located within these ranges. Therefore, in ordinary lighting environments, ambient light will affect the emission signal of SrAl2O4:Dy. 3+ The luminescent signal is interfered with by ambient light, making it impossible to clearly distinguish the optically stored signal. Therefore, how to prepare a long-afterglow luminescent material that is not interfered with by ambient light is an urgent problem to be solved. Secondly, SrAl2O4:Dy 3+ Typically, sintering at temperatures above 1200℃ is required for preparation, which significantly increases energy consumption during production. Simultaneously, the rare earth element Dy needs to be doped during the preparation process. 3+ The high price of the material keeps the cost of mass production high, thus limiting its widespread use in price-sensitive fields.

[0004] In summary, there is an urgent need to develop a new type of long-afterglow luminescent material that can avoid ambient light interference and has a low production cost. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an ultra-broad spectrum of Cs₂CdCl₄:xPb 2 + Long-afterglow luminescent materials, their preparation methods, and applications. This invention synthesizes Cs₂CdCl₄:xPb via a solvothermal method. 2+ The equipment required for the synthesis of long-afterglow luminescent materials is mature and simple, facilitating mass production. The obtained lead-doped Cs2CdCl4 long-afterglow luminescent material has high chemical stability, exhibits a long-afterglow luminescence spectrum with an ultra-wide wavelength range from UVB to visible light, and has a long afterglow luminescence time.

[0006] To achieve the above objectives, the technical solution of the present invention is: an ultra-broad spectrum Cs2CdCl4:xPb 2+ Long-afterglow luminescent materials, with Cs₂CdCl₄ as the matrix and Pb as the substrate. 2+ It is a luminescent recombination center with the general chemical formula Cs₂CdCl₄:xPb 2+ , where 0.001≤x≤0.1.

[0007] In a preferred embodiment of the present invention, the Cs2CdCl4:xPb 2+ The crystal structure of the long afterglow luminescent material is tetragonal, with a space group of I4 / mmm.

[0008] In a preferred embodiment of the present invention, the Cs2CdCl4:xPb 2+ Long-afterglow luminescent materials can be excited by 254nm ultraviolet light or X-rays and produce room-temperature long-afterglow luminescence in the UVB band (280-320nm).

[0009] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ Applications of long-afterglow luminescent materials in optical anti-counterfeiting and wearable devices.

[0010] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ The preparation method of long-afterglow luminescent materials includes the following steps:

[0011] (1) According to Cs2CdCl4:xPb 2+ Weigh out the raw materials containing Cs, Cd, and Pb in the molar ratios of Cs, Cd, and Pb, respectively.

[0012] (2) Add hydrochloric acid and N,N-dimethylformamide (C3H7NO) to the compound raw material containing Cs, Cd and Pb elements weighed in step (1), mix and stir evenly, and then put it into a reaction vessel for high-temperature treatment. After high-temperature treatment, cool it to room temperature, and then wash and dry the reaction product to obtain Cs2CdCl4:xPb.2+ Crystalline long afterglow luminescent materials.

[0013] In a preferred embodiment of the present invention, in step (1), the Cs-containing compound raw material is at least one of cesium carbonate or cesium chloride, the Cd-containing compound raw material is at least one of cadmium carbonate or cadmium chloride, and the Pb-containing compound raw material is at least one of lead bromide, lead iodide, or lead oxide.

[0014] In a preferred embodiment of the present invention, the volume ratio of hydrochloric acid to N,N-dimethylformamide in step (2) is 1:1, and the total amount of hydrochloric acid and N,N-dimethylformamide (C3H7NO) added is 6-8 mL / g relative to the total mass of the elemental compound raw materials containing Cs, Cd and Pb.

[0015] In a preferred embodiment of the present invention, the heating rate of the high-temperature treatment in step (2) is 2.5-3.5℃ / h, the temperature of the high-temperature treatment is 160-200℃, the holding time is 3-12h, and the cooling rate after the high-temperature treatment is 2-3℃ / h.

[0016] In a preferred embodiment of the present invention, the solvent for washing in step (2) is ethanol.

[0017] In a preferred embodiment of the present invention, the drying temperature in step (2) is 60-70°C and the drying time is 10-12 hours.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The Cs2CdCl4:xPb of the present invention 2+ Long-afterglow luminescent materials have high crystal chemical stability, can be effectively excited by 254nm ultraviolet light, and have a long-afterglow luminescence spectrum with an ultrawide wavelength range from UVB to visible light, and a long afterglow luminescence time.

[0020] 2. This invention does not require harsh synthesis conditions involving high pressure and reducing properties; it employs a solvothermal method and Cs₂CdCl₄:xPb under ambient pressure. 2+ The required chemical raw materials can be used to synthesize Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials;

[0021] 3. The Cs2CdCl4:xPb of the present invention 2+ Long-afterglow luminescent materials have simple preparation conditions and can be mass-produced industrially.

[0022] 4. The Cs2CdCl4:xPb of the present invention 2+ Long-afterglow luminescent materials can be applied to fields such as optical anti-counterfeiting and wearable devices, and are unaffected by visible light. Attached Figure Description

[0023] Figure 1 The ratio of Cs2CdCl4:xPb in Example 1 is as follows. 2+ (x = 0.001, 0.005, 0.1) X-ray diffraction patterns of long-afterglow luminescent materials;

[0024] Figure 2 The ratio of Cs2CdCl4:xPb in Examples 1-3 is [missing information]. 2+ (x = 0.001, 0.005, 0.1) Thermoluminescence spectra of long afterglow materials;

[0025] Figure 3 The ratio of Cs₂CdCl₄: 0.001Pb in Example 1 is [missing information]. 2+ Room temperature afterglow emission spectrum of long afterglow luminescent materials;

[0026] Figure 4 The ratio of Cs₂CdCl₄: 0.001Pb in Example 1 is [missing information]. 2+ Room temperature afterglow decay curve of long afterglow luminescent materials;

[0027] Figure 5 The ratio of Cs₂CdCl₄: 0.005Pb in Example 2 is [missing information]. 2+ Room temperature afterglow emission spectrum of long afterglow luminescent materials;

[0028] Figure 6 The ratio of Cs₂CdCl₄: 0.005Pb in Example 2 is [missing information]. 2+ Room temperature afterglow decay curve of long afterglow luminescent materials;

[0029] Figure 7 The ratio of Cs₂CdCl₄:0.1Pb in Example 3 is [missing information]. 2+ Room temperature afterglow emission spectrum of long afterglow luminescent materials;

[0030] Figure 8 The ratio of Cs₂CdCl₄:0.1Pb in Example 3 is [missing information]. 2+ Room temperature afterglow decay curve of long afterglow luminescent materials;

[0031] Figure 9 The ratio used in Example 4 was Cs₂CdCl₄ synthesized using lead iodide (PbI₂) as the raw material: 0.1Pb 2+ X-ray diffraction patterns of long-afterglow luminescent materials;

[0032] Figure 10 The ratio used in Example 4 was Cs₂CdCl₄ synthesized using lead iodide (PbI₂) as the raw material: 0.1Pb 2+ Room temperature afterglow emission spectrum of long afterglow luminescent materials;

[0033] Figure 11 The ratio used in Example 4 was Cs₂CdCl₄ synthesized using lead iodide (PbI₂) as the raw material: 0.1Pb 2+ Room temperature afterglow decay curve of long afterglow luminescent materials;

[0034] Figure 12 The ratio used in Example 4 was Cs₂CdCl₄ synthesized using lead iodide (PbI₂) as the raw material: 0.1Pb 2+ Thermoluminescence curves of long-afterglow luminescent materials;

[0035] Figure 13 The formulation used in Example 5 was Cs₂CdCl₄ synthesized from cesium chloride (CsCl) and cadmium chloride (CdCl₂) as raw materials: 0.005Pb. 2+ X-ray diffraction patterns of long-afterglow luminescent materials;

[0036] Figure 14 The formulation used in Example 5 was Cs₂CdCl₄ synthesized from cesium chloride (CsCl) and cadmium chloride (CdCl₂) as raw materials: 0.005Pb. 2+ Room temperature long-afterglow emission spectrum of long-afterglow luminescent materials;

[0037] Figure 15 The formulation used in Example 5 was Cs₂CdCl₄ synthesized from cesium chloride (CsCl) and cadmium chloride (CdCl₂) as raw materials: 0.005Pb. 2+ Room temperature long-afterglow decay curve of long-afterglow luminescent materials;

[0038] Figure 16 The formulation used in Example 5 was Cs₂CdCl₄ synthesized from cesium chloride (CsCl) and cadmium chloride (CdCl₂) as raw materials: 0.005Pb. 2+ Thermoluminescence curves of long-afterglow luminescent materials;

[0039] Figure 17 Example 6 uses Cs₂CdCl₄:0.005Pb. 2+ A visual anti-counterfeiting system designed with long afterglow luminescent materials. Detailed Implementation

[0040] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0041] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials, with Cs₂CdCl₄ as the matrix and Pb as the substrate. 2+It is a luminescent recombination center with the general chemical formula Cs₂CdCl₄:xPb 2+ , where 0.001≤x≤0.1.

[0042] The Cs2CdCl4:xPb 2+ The crystal structure of the long afterglow luminescent material is tetragonal, with a space group of I4 / mmm.

[0043] The Cs2CdCl4:xPb 2+ Long-afterglow luminescent materials can be excited by 254nm ultraviolet light or X-rays and produce room-temperature long-afterglow luminescence in the UVB band (280-320nm).

[0044] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ Applications of long-afterglow luminescent materials in optical anti-counterfeiting and wearable devices.

[0045] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ The preparation method of long-afterglow luminescent materials includes the following steps:

[0046] (1) According to Cs2CdCl4:xPb 2+ Weigh out the raw materials containing Cs, Cd, and Pb in the molar ratios of Cs, Cd, and Pb, respectively.

[0047] (2) Add hydrochloric acid and N,N-dimethylformamide (C3H7NO) to the compound raw material containing Cs, Cd and Pb elements weighed in step (1), mix and stir evenly, and then put it into a reaction vessel for high-temperature treatment. After high-temperature treatment, cool it to room temperature, and then wash and dry the reaction product to obtain Cs2CdCl4:xPb. 2+ Crystalline long afterglow luminescent materials.

[0048] In step (1), the Cs-containing compound raw material is at least one of cesium carbonate or cesium chloride, the Cd-containing compound raw material is at least one of cadmium carbonate or cadmium chloride, and the Pb-containing compound raw material is at least one of lead bromide, lead iodide, or lead oxide.

[0049] In step (2), the volume ratio of hydrochloric acid to N,N-dimethylformamide (C3H7NO) is 1:1, and the total amount of hydrochloric acid and N,N-dimethylformamide (C3H7NO) added is 6-8 mL / g relative to the total mass of the raw materials containing Cs, Cd and Pb.

[0050] In step (2), the heating rate of the high-temperature treatment is 3℃ / h, the temperature of the high-temperature treatment is 160-200℃, the holding time is 3-12h, and the cooling rate after the high-temperature treatment is 2-3℃ / h.

[0051] The solvent used for washing in step (2) is ethanol.

[0052] The drying temperature in step (2) is 60-70℃ and the drying time is 10-12h.

[0053] Example 1

[0054] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials, with Cs₂CdCl₄ as the matrix and Pb as the substrate. 2+ It serves as a luminescent recombination center, with the general chemical formula Cs₂CdCl₄:0.001Pb. 2+ It is prepared by the following method:

[0055] Cesium carbonate (Cs₂CO₃), cadmium carbonate (CdCO₃), and lead bromide (PbBr₂) were used as raw materials. The formula is based on Cs₂CdCl₄:0.001Pb. 2+ The required compound raw materials were weighed according to the molar ratio of Cs, Cd, and Pb in the formula. The mass of cesium carbonate (Cs₂CO₃) was 0.6536 g, the mass of cadmium carbonate (CdCO₃) was 0.3453 g, and the mass of lead bromide (PbBr₂) was 0.00073 g. These were mixed together and placed in a polytetrafluoroethylene liner. 3 mL of hydrochloric acid and 3 mL of N,N-dimethylformamide (C₃H₇NO) were added, and the mixture was stirred until homogeneous before being placed in a reaction vessel. The reaction vessel was placed in an oven, and the temperature was increased from 25°C to 180°C at a rate of 3°C / min, and maintained at 180°C for 12 h. Subsequently, the sample was cooled from 180°C to room temperature at a rate of 2.5°C / h. The crystalline block sample was washed several times with ethanol and then dried in a vacuum oven at 60°C. After drying, it was ground into powder to synthesize the crystalline compound Cs₂CdCl₄:0.001Pb. 2 Long-afterglow luminescent materials.

[0056] Figure 1 The Cs₂CdCl₄:0.001Pb of Example 1 is given. 2+ The X-ray diffraction patterns were obtained. The patterns were acquired using a Bruker D8 Advance X-ray diffractometer (Germany). During pattern acquisition, the X-ray tube operating voltage was set to 40 kV and 40 mA. Figure 1 The X-ray diffraction pattern shows that the Cs₂CdCl₄ of Example 1 has a density of 0.001Pb. 2+ The diffraction peaks match well with those of the standard substance Cs₂CdCl₄ (PDF#72-1094), indicating that the synthesized long-afterglow luminescent material has the crystal structure of Cs₂CdCl₄ (PDF#72-1094) (tetragonal crystal system, space group I₄ / mmm).2+ The doping did not introduce any impurity phases.

[0057] Figure 2 The Cs₂CdCl₄:0.001Pb of Example 1 is given. 2+ Thermoluminescence curve after excitation with 254 nm light. The heating rate of the thermoluminescence curve is 1 K / s. Two thermoluminescent bands were observed, with peaks at 320 K and 395 K, respectively.

[0058] Figure 3 The Cs₂CdCl₄:0.001Pb from Example 1 is shown. 2+ Afterglow emission spectrum of long-afterglow luminescent materials. The excitation source was a 254 nm mercury lamp. As can be seen from the figure, Pb... 2+ The emission is band-shaped, with a peak at approximately 314 nm, ranging from 290 nm to 350 nm. Pb 2+ The luminescence intensity of the light source is stronger than that of the matrix. The afterglow luminescence originates from Pb. 2+ of 3 P1→ 1 S0 characteristic emission.

[0059] Figure 4 The ratio of Cs₂CdCl₄: 0.001Pb in Example 1 is [missing information]. 2+ Afterglow decay curves of long-afterglow luminescent materials. The excitation source is a 245nm xenon lamp. The figure shows that in Cs₂CdCl₄: 0.001Pb... 2+ In the middle, Pb can be observed for more than 600 seconds. 2+ The long afterglow shines.

[0060] Example 2

[0061] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials, with Cs₂CdCl₄ as the matrix and Pb as the substrate. 2+ It serves as a luminescent recombination center, with the general chemical formula Cs₂CdCl₄:0.005Pb. 2+ It is prepared by the following method:

[0062] Cesium carbonate (Cs₂CO₃), cadmium carbonate (CdCO₃), and lead bromide (PbBr₂) were used as raw materials. The ratio of Cs₂CdCl₄ to 0.005Pb was calculated. 2+The required compound raw materials, including cesium carbonate (Cs₂CO₃) (0.6525 g), cadmium carbonate (CdCO₃) (0.3440 g), and lead bromide (PbBr₂) (0.00371 g), were weighed according to the molar ratio of Cs, Cd, and Pb in the chemical formula. These were placed together in a polytetrafluoroethylene liner. 3 mL of hydrochloric acid and 3 mL of N,N-dimethylformamide (C₃H₇NO) were added, and the mixture was stirred until homogeneous before being placed in a reaction vessel. The reaction vessel was placed in an oven, and the temperature was increased from 25°C to 180°C at a rate of 3°C / min, and maintained at 180°C for 12 hours. Subsequently, the sample was cooled from 180°C to room temperature at a rate of 2.5°C / h. The bulk crystalline sample was washed several times with ethanol and then dried in a vacuum oven at 60°C. After drying, it was ground into powder to synthesize the crystalline compound Cs₂CdCl₄:0.005Pb. 2+ Long-afterglow luminescent materials.

[0063] Figure 1 Example 2 provides Cs₂CdCl₄:0.005Pb 2+ X-ray diffraction pattern of the crystal. As can be seen from the figure, the Cs₂CdCl₄:0.005Pb synthesized in Example 2... 2+ The X-ray diffraction pattern of the crystal is consistent with that of the standard Cs₂CdCl₄ (PDF#72-1094) crystal. The synthesized long-afterglow luminescent material has the crystal structure of Cs₂CdCl₄ (PDF#72-1094) (tetragonal system, space group I₄ / mmm), indicating the successful synthesis of Cs₂CdCl₄:0.005Pb. 2+ Crystal. Pb 2+ The doping did not introduce any impurity phases.

[0064] Figure 2 Example 2 provides Cs₂CdCl₄:0.005Pb 2+ Thermoluminescence curve of the crystal after excitation with 254 nm light. The heating rate of the thermoluminescence curve is 1 K / s. Two thermoluminescent bands were observed, with peaks at 330 K and 395 K, respectively.

[0065] Figure 5 Example 2 provides Cs₂CdCl₄:0.005Pb 2+ The room-temperature afterglow emission spectrum of the crystal. The excitation source was a 254 nm mercury lamp. The figure shows that Pb... 2+ The main emission peak is at 314 nm. Afterglow emission originates from Pb. 2+ of 3 P1→ 1 S0 transition. In addition, broadband visible long-afterglow luminescence with a peak at 450 nm was also observed.

[0066] Figure 6 Example 2 provides Cs₂CdCl₄:0.005Pb 2+ Room temperature afterglow decay curves of long-afterglow luminescent materials. The excitation source is a 245nm xenon lamp. The figure shows that in Cs₂CdCl₄: 0.005Pb... 2+ In the study, a long afterglow emission at room temperature lasting over 600 seconds can be observed.

[0067] Example 3

[0068] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials, with Cs₂CdCl₄ as the matrix and Pb as the substrate. 2+ It serves as a luminescent recombination center, with the general chemical formula Cs₂CdCl₄:0.1Pb. 2+ It is prepared by the following method:

[0069] Cesium carbonate (Cs₂CO₃), cadmium carbonate (CdCO₃), and lead bromide (PbBr₂) were used as raw materials. The ratio of Cs₂CdCl₄ to 0.1Pb was calculated. 2+ The required compound raw materials were weighed according to the molar ratio of Cs, Cd, and Pb in the formula. The mass of cesium carbonate (Cs₂CO₃) was 0.6294 g, the mass of cadmium carbonate (CdCO₃) was 0.2997 g, and the mass of lead bromide (PbBr₂) was 0.0708 g. These were placed together in a polytetrafluoroethylene liner. 3 mL of hydrochloric acid and 3 mL of N,N-dimethylformamide (C₃H₇NO) were added, and the mixture was stirred thoroughly before being placed in a reaction vessel. The reaction vessel was placed in an oven, and the temperature was increased from 25°C to 180°C at a rate of 3°C / min, and maintained at 180°C for 12 h. Subsequently, the sample was cooled from 180°C to room temperature at a rate of 2.5°C / h. The bulk crystalline sample was washed several times with ethanol and then dried in a vacuum oven at 60°C. After drying, it was ground into powder to synthesize the crystalline compound Cs₂CdCl₄:0.1Pb. 2+ Long-afterglow luminescent materials.

[0070] Figure 1 Example 3 provides Cs₂CdCl₄:0.1Pb 2+ The X-ray diffraction pattern of the crystal shows good agreement with the diffraction peaks of the standard Cs₂CdCl₄ crystal (PDF#72-1094). The synthesized long-afterglow luminescent material possesses the crystal structure of Cs₂CdCl₄ (PDF#72-1094) (tetragonal system, space group I₄ / mmm), indicating the successful synthesis of Cs₂CdCl₄:0.1Pb. 2+ Crystal. Pb 2+ The doping did not introduce any impurity phases.

[0071] Figure 2 Example 3 provides Cs₂CdCl₄:0.1Pb 2+ Thermoluminescence spectrum of the crystal. The excitation source for the sample was a mercury lamp. The sample was excited by the mercury lamp at a temperature of 300 K. The thermoluminescence peaks of the sample cover a temperature range from 303 K to 400 K.

[0072] Figure 7 Example 3 provides Cs₂CdCl₄:0.1Pb 2+ The room-temperature long-afterglow emission spectrum of the crystal. The excitation source was a 254 nm mercury lamp. The graph shows that Pb... 2+ The dominant emission peak is at 314 nm. The remaining glow emission originates from Pb. 2 + of 3 P1→ 1 S0 transition. In addition, a weak long-afterglow emission peak with a peak at 450 nm was also observed.

[0073] Figure 8 Example 3 provides Cs₂CdCl₄:0.1Pb 2+ The room-temperature afterglow decay curve of the crystal. The excitation source was a 245nm xenon lamp. The figure shows that Cs₂CdCl₄:0.1Pb 2+ The room temperature long afterglow emission lasted for more than 120 seconds.

[0074] Example 4

[0075] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials, with Cs₂CdCl₄ as the matrix and Pb as the substrate. 2+ It serves as a luminescent recombination center, with the general chemical formula Cs₂CdCl₄:0.1Pb. 2+ It is prepared by the following method:

[0076] Cesium carbonate (Cs₂CO₃), cadmium carbonate (CdCO₃), and lead iodide (PbI₂) were used as raw materials. The formula is based on Cs₂CdCl₄:0.1Pb. 2+The required compound raw materials were weighed according to the molar ratio of Cs, Cd, and Pb in the formula. Cesium carbonate (Cs₂CO₃) weighed 0.6181 g, cadmium carbonate (CdCO₃) weighed 0.2944 g, and lead iodide (PbI₂) weighed 0.08746 g. These were placed together in a polytetrafluoroethylene liner. 3 mL of hydrochloric acid and 3 mL of N,N-dimethylformamide (C₃H₇NO) were added, and the mixture was stirred thoroughly before being placed in a reaction vessel. The reaction vessel was placed in an oven, and the temperature was increased from 25°C to 180°C at a rate of 3°C / min, and maintained at 180°C for 12 h. Subsequently, the sample was cooled from 180°C to room temperature at a rate of 2.5°C / h. The block sample was washed several times with ethanol and then dried in a vacuum oven at 60°C. After drying, it was ground into powder to synthesize the crystalline compound Cs₂CdCl₄:0.1Pb. 2+ Long-afterglow luminescent materials.

[0077] Figure 9 Example 4 shows Cs₂CdCl₄:0.1Pb. 2+ X-ray diffraction pattern of a crystal. Figure 9 The X-ray diffraction pattern shows that the Cs₂CdCl₄:0.1Pb synthesized in Example 4 using lead iodide (PbI₂) as a raw material is... 2+ It has a (PDF#72-1094) Cs₂CdCl₄ crystal structure (tetragonal system, space group I₄ / mmm). Pb 2+ The doping did not introduce any impurity phases.

[0078] Figure 10 The ratio used in Example 4 was Cs₂CdCl₄ synthesized using lead iodide (PbI₂) as the raw material: 0.1Pb 2+ Room temperature afterglow emission spectrum of long-afterglow luminescent materials. The excitation source was a 254 nm mercury lamp. The figure shows that Pb... 2+ A strong UVB long afterglow emission peak is shown, with a peak value at 314 nm. The afterglow emission originates from Pb. 2+ of 3 P1→ 1 S0 transition.

[0079] Figure 11 Example 4 provides the ratio for synthesizing Cs₂CdCl₄ using lead iodide (PbI₂) as a raw material: 0.1Pb 2+ Room temperature afterglow decay curves of long-afterglow luminescent materials. The excitation source is a 245nm xenon lamp. The figure shows that Cs₂CdCl₄:0.1Pb 2+ The room temperature afterglow emission lasted for more than 600 seconds.

[0080] Figure 12 Example 4 shows Cs₂CdCl₄:0.1Pb.2+ Thermoluminescence curve of the crystal. The excitation source for the sample was a mercury lamp. The temperature at which the sample was excited by the mercury lamp was 300 K. The heating rate of the sample was 1 K / s. As can be seen from the figure, Cs₂CdCl₄:0.1Pb synthesized using lead iodide (PbI₂) as a raw material... 2+ A strong thermoluminescent band with a peak at 328K was observed.

[0081] Example 5

[0082] An ultra-broad spectrum of Cs₂CdCl₄:xPb 2+ Long-afterglow luminescent materials, with Cs₂CdCl₄ as the matrix and Pb as the substrate. 2+ It serves as a luminescent recombination center, with the general chemical formula Cs₂CdCl₄:0.005Pb. 2+ It is prepared by the following method:

[0083] Cesium carbonate (CsCl), cadmium carbonate (CdCl2), and lead bromide (PbBr2) were used as raw materials. The formula is based on Cs2CdCl4:0.005Pb. 2+ The required compound raw materials, including cesium carbonate (CsCl) (0.6499 g), cadmium carbonate (CdCl2) (0.3469 g), and lead bromide (PbBr2) (0.00354 g), were weighed according to the molar ratio of Cs, Cd, and Pb in the formulation. These were placed together in a polytetrafluoroethylene liner. 3 mL of hydrochloric acid and 3 mL of N,N-dimethylformamide (C3H7NO) were added, and the mixture was stirred thoroughly before being placed in a reaction vessel. The reaction vessel was placed in an oven, and the temperature was increased from 25°C to 180°C at a rate of 3°C / h, and maintained at 180°C for 12 h. Subsequently, the sample was cooled from 180°C to room temperature at a rate of 2.5°C / h. After washing the block sample several times with ethanol, it was dried in a vacuum oven at 60°C. After drying, it was ground into powder to synthesize the crystalline compound long-afterglow luminescent material.

[0084] Figure 13 Example 5 provides Cs₂CdCl₄:0.005Pb 2+ The X-ray diffraction pattern of the crystal matches the X-ray peaks of Cs₂CdCl₄ crystal (PDF#72-1094). The synthesized long-afterglow luminescent material has the crystal structure of Cs₂CdCl₄ (PDF#72-1094) (tetragonal crystal system, space group I₄ / mmm), indicating the successful synthesis of Cs₂CdCl₄:0.005Pb. 2+ Crystal. Pb 2+ The doping did not introduce any impurity phases.

[0085] Figure 14 Example 5 provides Cs₂CdCl₄:0.005Pb 2+The room-temperature afterglow emission spectrum of the crystal. The excitation source was a 254 nm mercury lamp. The figure shows that Pb... 2+ The main emission peak is at 314 nm. (Pb) 2+ The long afterglow luminescence at room temperature originates from Pb 2+ of 3 P1→ 1 S0 transition.

[0086] Figure 15 Example 5 provides Cs₂CdCl₄:0.005Pb 2+ Afterglow decay curve of the crystal at room temperature. The excitation source was a 245nm xenon lamp. (Cs₂CdCl₄: 0.005Pb) 2+ In the middle, room temperature Pb can be observed for more than 80 seconds. 2+ The afterglow shines brightly.

[0087] Figure 16 Example 5 provides Cs₂CdCl₄:0.005Pb 2+ Thermoluminescence curve of the crystal. The excitation source for the sample was a mercury lamp. The sample was excited at a temperature of 300 K. The heating rate of the sample was 1 K / s. As can be seen from the figure, two thermoluminescence peaks were observed, with peak values ​​at 324 K and 394 K, respectively.

[0088] Example 6

[0089] Based on the Cs2CdCl4:0.005Pb developed in Example 2 2+ Long afterglow luminescent materials were designed Figure 17 A visual anti-counterfeiting system. Based on ASCII codes, information can be written into an 8×5 matrix. Cs₂CdCl₄:0.005Pb was not placed in water. 2+ It exhibits blue photoluminescence and long-afterglow luminescence. Cs₂CdCl₄: 0.005Pb 2+ When placed in water and excited by 254nm ultraviolet light, it exhibits green photoluminescence and long-afterglow luminescence. Figure 17 In the visual anti-counterfeiting system, the code for green light emitted under 254nm mercury lamp excitation is 1, and the code for blue light emitted is 0. After the mercury lamp is turned off, the code for having afterglow is 1, and the code for not having afterglow is 0. Figure 17 As we can see, the real information is only displayed 0.5 seconds after the mercury lamp is turned off. The information displayed when the mercury lamp is illuminating the lamp and 2 seconds after the lamp stops igniting is false information.

[0090] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ultra-broad spectral Cs₂CdCl₄:xPb 2+ Long afterglow luminescent material, characterized in that, Using Cs₂CdCl₄ as the matrix and Pb as the substrate 2+ It is a luminescent recombination center with the general chemical formula Cs₂CdCl₄:xPb 2+ , where 0.001≤x≤0.

1.

2. The ultra-broad spectrum Cs₂CdCl₄:xPb as described in claim 1 2+ Long afterglow luminescent material, characterized in that, The Cs2CdCl4:xPb 2+ The crystal structure of the long afterglow luminescent material is tetragonal, with a space group of I4 / mm.

3. The ultra-broad spectrum Cs₂CdCl₄:xPb as described in claim 1 2+ Long afterglow luminescent material, characterized in that, The Cs2CdCl4:xPb 2+ Long-afterglow luminescent materials can be excited by 254 nm ultraviolet light or X-rays and produce room-temperature long-afterglow luminescence in the UVB band.

4. A Cs₂CdCl₄:xPb with an ultrabroad spectral density as described in any one of claims 1-3 2+ Applications of long-afterglow luminescent materials in optical anti-counterfeiting and wearable devices.

5. A Cs₂CdCl₄:xPb with an ultrabroad spectrum as described in any one of claims 1-3 2+ The method for preparing long-afterglow luminescent materials is characterized by, Includes the following steps: (1) According to Cs2CdCl4:xPb 2+ Weigh out the raw materials containing Cs, Cd, and Pb in the molar ratios of Cs, Cd, and Pb, respectively. (2) Add hydrochloric acid and N,N-dimethylformamide to the compound raw material containing Cs, Cd and Pb elements weighed in step (1), mix and stir evenly, and then put it into a reaction vessel for high-temperature treatment. After high-temperature treatment, cool it to room temperature, and then wash and dry the reaction product to obtain Cs2CdCl4:xPb. 2+ Crystalline long afterglow luminescent material; high temperature treatment temperature is 160-200 ℃, and the holding time is 3-12 h.

6. The ultra-broad spectrum Cs₂CdCl₄:xPb as described in claim 5 2+ The method for preparing long-afterglow luminescent materials is characterized by, In step (1), the Cs-containing compound raw material is at least one of cesium carbonate or cesium chloride, the Cd-containing compound raw material is at least one of cadmium carbonate or cadmium chloride, and the Pb-containing compound raw material is at least one of lead bromide, lead iodide, or lead oxide.

7. The ultra-broad spectrum Cs₂CdCl₄:xPb as described in claim 5 2+ The method for preparing long-afterglow luminescent materials is characterized by, In step (2), the volume ratio of hydrochloric acid to N,N-dimethylformamide is 1:1, and the total amount of hydrochloric acid and N,N-dimethylformamide added is 6-8 mL / g relative to the total mass of the raw materials containing Cs, Cd and Pb.

8. The ultra-broad spectrum Cs₂CdCl₄:xPb as described in claim 5 2+ The method for preparing long-afterglow luminescent materials is characterized by, The heating rate in step (2) is 2.5-3.5 ℃ / h, and the cooling rate after the high-temperature treatment is 2-3 ℃ / h.

9. The ultra-broad spectrum Cs₂CdCl₄:xPb as described in claim 5 2+ The method for preparing long-afterglow luminescent materials is characterized by, The solvent used for washing in step (2) is ethanol.

10. The ultrabroad spectral Cs₂CdCl₄:xPb as described in claim 5 2+ The method for preparing long-afterglow luminescent materials is characterized by, In step (2), the drying temperature is 60-70 ℃ and the drying time is 10-12 h.

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