Ultra-wide-spectrum Cs2CdCl4: xPb < 2 + > long-afterglow luminescent material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of long-afterglow luminescent materials, and particularly discloses an ultra-wide-spectrum Cs2CdCl4: xPb < 2 + > long-afterglow luminescent material and a preparation method and application thereof.The Cs2CdCl4: xPb < 2 + > long-afterglow luminescent material takes Cs2CdCl4 as a matrix and Pb < 2 + > as a luminescent composite center, the chemical general formula of the Cs2CdCl4: xPb < 2 + > is Cs2CdCl4: xPb < 2 + >, and x is larger than or equal to 0.001 and smaller than or equal to 0.1. The Cs2CdCl4: xPb < 2 + > long-afterglow luminescent material crystal disclosed by the invention is high in chemical stability, can be effectively excited by 254nm ultraviolet light or X rays, has a long-afterglow luminescent spectrum from UVB ultraviolet light to visible light ultra-wide wave band, and is long in afterglow luminescent time; the Cs2CdCl4: xPb < 2 + > long-afterglow luminescent material can be synthesized by adopting a solvothermal method and chemical raw materials required by the Cs2CdCl4: xPb < 2 + > under a normal pressure condition without adopting harsh synthesis conditions of high pressure and reducibility; the preparation conditions of the Cs2CdCl4: xPb < 2 + > long-afterglow luminescent material are simple, and batch industrial production can be realized; the Cs2CdCl4: xPb < 2 + > long-afterglow luminescent material can be applied to the fields of optical anti-counterfeiting, wearable equipment and the like, and is not influenced by visible light.

Description

Technical Field

[0001] The present invention belongs to the technical field of long afterglow luminescent materials, and specifically relates to an ultra-wide spectrum Cs2CdCl4:xPb 2 + Long afterglow luminescent material and preparation method and application thereof. Background Art

[0002] Long afterglow luminescent materials are a type of material that can continue to emit light for a period of time after the excitation light source is removed. Through excitation by ionizing rays (such as X-rays or high-energy 254nm ultraviolet light), the electrons in the long afterglow luminescent materials are excited to a higher energy state, usually in an excited state or conduction band. These excited electrons can be transferred to the trap state inside the material through direct transitions or via intermediate energy levels. When the external light source is removed, the electrons trapped in the trap will gradually be released from the trap state, gradually returning to a lower energy level, and finally releasing light energy by transitioning to the ground state. In this process, the phenomenon of continuous luminescence is produced, which is the long afterglow luminescence effect. Long afterglow luminescent materials are increasingly attracting widespread attention due to their potential application value in optoelectronic devices, life sciences, and wearable devices.

[0003] SrAl2O4:Dy 3+ It is a typical traditional long afterglow luminescent material and has been used in the lighting field. 3+ There are still significant limitations, which makes it difficult to meet the diverse needs in practical applications. 3+ It mainly emits green long afterglow, and the wavelength is concentrated in the visible light range. Ambient light is usually in the visible light spectrum, while SrAl2O4:Dy 3+ The luminescence signal of SrAl2O4:Dy is also usually within these ranges. Therefore, in normal lighting environments, ambient light will have a significant impact on SrAl2O4:Dy 3+ The luminous signal of the optical storage is interfered, making it impossible to clearly distinguish the optical storage signal. Therefore, how to prepare a long afterglow luminescent material that is not interfered by ambient light is an urgent problem to be solved. 3+ Usually, it needs to be sintered at a high temperature of more than 1200°C. This high temperature process significantly increases the energy consumption in the production process. At the same time, the rare earth element Dy required for doping in the preparation process 3+ The high price makes the mass production cost of the material remain high, thus limiting its wide application 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 interference from ambient light and has a lower production cost. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a Cs2CdCl4:xPb 2 + Long afterglow luminescent material and its preparation method and application. The present invention synthesizes Cs2CdCl4:xPb by solvent thermal method 2+ Long afterglow luminescent materials, the equipment required for synthesis is mature and simple, and is convenient for mass production; the obtained lead-doped Cs2CdCl4 long afterglow luminescent material has high chemical stability, a long afterglow luminescent spectrum with an ultra-wide band from UVB ultraviolet light to visible light, and a long afterglow luminescence time.

[0006] In order to achieve the above objectives, the technical solution of the present invention is: an ultra-wide spectrum Cs2CdCl4:xPb 2+ Long afterglow luminescent material, with Cs2CdCl4 as the matrix and Pb 2+ It is a luminescent recombination center, and its general chemical formula is 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, and the space group is I4 / mmm.

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

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

[0010] An ultra-broad spectrum Cs2CdCl4:xPb 2+ The method for preparing a long afterglow luminescent material comprises the following steps:

[0011] (1) According to Cs2CdCl4:xPb 2+ The molar ratio of Cs, Cd and Pb in the compound raw materials containing Cs, Cd and Pb elements are weighed 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, put into a reactor for high temperature treatment, cool to room temperature after high temperature treatment, and then wash and dry the reaction product to obtain Cs2CdCl4:xPb2+ Crystalline long afterglow luminescent material.

[0013] In a preferred embodiment of the present invention, the Cs-containing compound raw material in step (1) 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 relative to the total mass of the elemental compound raw materials containing Cs, Cd and Pb is 6-8 mL / g.

[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°C / h, the temperature of the high temperature treatment is 160-200°C, the insulation time is 3-12h, and the cooling rate after the high temperature treatment is 2-3°C / h.

[0016] In a preferred embodiment of the present invention, the washing solvent 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 h.

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

[0019] 1. Cs2CdCl4:xPb of the present invention 2+ The crystal chemical stability of the long afterglow luminescent material is high, and it can be effectively excited by 254nm ultraviolet light. It has a long afterglow luminescence spectrum with an ultra-wide band from UVB ultraviolet light to visible light, and the afterglow luminescence time is long.

[0020] 2. The present invention does not require the use of harsh synthesis conditions of high pressure and reduction, and adopts the solvent thermal method and Cs2CdCl4:xPb under normal pressure conditions. 2+ The required chemical raw materials can be used to synthesize Cs2CdCl4:xPb 2+ Long afterglow luminescent materials;

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

[0022] 4. Cs2CdCl4:xPb of the present invention 2+ Long afterglow luminescent materials can be used in optical anti-counterfeiting, wearable devices and other fields, and are not affected by visible light. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

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

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

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

[0031] Fig. 9 The ratio of Example 4 is Cs2CdCl4:0.1Pb 2+ X-ray diffraction patterns of long afterglow luminescent materials;

[0032] Fig.10 The ratio of Example 4 is Cs2CdCl4:0.1Pb 2+ Room temperature afterglow luminescence spectrum of long afterglow luminescent materials;

[0033] Fig.11 The ratio of Example 4 is Cs2CdCl4:0.1Pb 2+ Room temperature afterglow decay curve of long afterglow luminescent materials;

[0034] Fig.12 The ratio of Example 4 is Cs2CdCl4:0.1Pb 2+ Thermoluminescence curves of long afterglow luminescent materials;

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

[0036] Fig.14 Cs2CdCl4:0.005Pb synthesized from cesium chloride (CsCl) and cadmium chloride (CdCl2) as raw materials in the ratio of Example 5 2+ Room temperature long afterglow luminescence spectrum of long afterglow luminescent materials;

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

[0038] Fig.16 Cs2CdCl4:0.005Pb synthesized from cesium chloride (CsCl) and cadmium chloride (CdCl2) as raw materials in the ratio of Example 5 2+ Thermoluminescence curves of long afterglow luminescent materials;

[0039] Fig.17 For Example 6 based on Cs2CdCl4:0.005Pb 2+ Visual anti-counterfeiting system designed with long afterglow luminescent materials. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0041] An ultra-broad spectrum Cs2CdCl4:xPb 2+ Long afterglow luminescent material, with Cs2CdCl4 as the matrix and Pb 2+It is a luminescent recombination center, and its general chemical formula is 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, and the space group is I4 / mmm.

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

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

[0045] An ultra-broad spectrum Cs2CdCl4:xPb 2+ The method for preparing a long afterglow luminescent material comprises the following steps:

[0046] (1) According to Cs2CdCl4:xPb 2+ The molar ratio of Cs, Cd and Pb in the compound raw materials containing Cs, Cd and Pb elements are weighed 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, put into a reactor for high temperature treatment, cool to room temperature after high temperature treatment, and then wash and dry the reaction product to obtain Cs2CdCl4:xPb 2+ Crystalline long afterglow luminescent material.

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

[0049] In the 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 relative to the total mass of the elemental compound raw materials containing Cs, Cd and Pb is 6-8 mL / g.

[0050] The heating rate of the high temperature treatment in step (2) is 3°C / h, the temperature of the high temperature treatment is 160-200°C, the insulation time is 3-12h, and the cooling rate after the high temperature treatment is 2-3°C / h.

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

[0052] In the step (2), the drying temperature is 60-70° C. and the drying time is 10-12 h.

[0053] Example 1

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

[0055] Cesium carbonate (Cs2CO3), cadmium carbonate (CdCO3) and lead bromide (PbBr2) are used as raw materials. Based on Cs2CdCl4:0.001Pb 2+ The molar ratio of Cs, Cd and Pb in the formula is used to weigh the required compound raw materials. The mass of cesium carbonate (Cs2CO3) is 0.6536 g, the mass of cadmium carbonate (CdCO3) is 0.3453 g, and the mass of lead bromide (PbBr2) is 0.00073 g. After mixing together, put them into a polytetrafluoroethylene liner; add 3mL hydrochloric acid and 3mL N,N-dimethylformamide (C3H7NO), stir and mix well, and then put them into the reactor. The reactor is placed in an oven, heated from 25℃ to 180℃ at a heating rate of 3℃ / min, and kept at 180℃ for 12h. The sample is then cooled from 180℃ to room temperature at a cooling rate of 2.5℃ / h. After the crystal block sample is washed with ethanol several times, it is placed in a vacuum oven at 60℃ for drying. After drying, grind it into powder to synthesize the crystalline compound Cs2CdCl4:0.001Pb 2 Long afterglow luminescent material.

[0056] Figure 1 The Cs2CdCl4:0.001Pb of Example 1 is given 2+ X-ray diffraction spectrum. The spectrum was collected using a German Bruker D8 Advance X-ray diffractometer. During spectrum collection, the X-ray tube operating voltage was set to 40 kV and 40 mA. Figure 1 The X-ray diffraction pattern of Example 1 shows that Cs2CdCl4:0.001Pb 2+ The diffraction peaks are consistent 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 system, space group I4 / mmm).2+ The doping does not introduce any impurities.

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

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

[0059] Figure 4 The ratio of Example 1 is Cs2CdCl4:0.001Pb 2+ Afterglow decay curve of long afterglow luminescent material. The excitation light source is a 245nm xenon lamp. As can be seen from the figure, in Cs2CdCl4:0.001Pb 2+ In the experiment, Pb was observed for more than 600 seconds. 2+ Long afterglow glow.

[0060] Example 2

[0061] An ultra-broad spectrum Cs2CdCl4:xPb 2+ Long afterglow luminescent material, with Cs2CdCl4 as the matrix and Pb 2+ It is the luminescent recombination center, and its chemical formula is Cs2CdCl4:0.005Pb 2+ , prepared by the following method:

[0062] Cesium carbonate (Cs2CO3), cadmium carbonate (CdCO3) and lead bromide (PbBr2) are used as raw materials. 2+The molar ratio of the elements of Cs, Cd, and Pb in the chemical formula Weigh the required compound raw materials, the mass of cesium carbonate (Cs2CO3) is 0.6525g, the mass of cadmium carbonate (CdCO3) is 0.3440g, and the mass of lead bromide (PbBr2) is 0.00371g, and put them together in a polytetrafluoroethylene liner; add 3mL hydrochloric acid and 3mL N,N-dimethylformamide (C3H7NO), stir and mix well, and then put them into the reactor. The reactor is placed in an oven, heated from 25℃ to 180℃ at a heating rate of 3℃ / min, and kept at 180℃ for 12h. The sample is then cooled from 180℃ to room temperature at a cooling rate of 2.5℃ / h. After the block crystal sample is washed with ethanol several times, it is placed in a vacuum oven at 60℃ for drying. After drying, it is ground into powder to synthesize the crystalline compound Cs2CdCl4:0.005Pb 2+ Long afterglow luminescent material.

[0063] Figure 1 The Cs2CdCl4:0.005Pb of Example 2 is given 2+ X-ray diffraction pattern of the crystal. It can be seen from the figure that the Cs2CdCl4:0.005Pb synthesized in Example 2 2+ The X-ray diffraction pattern of the crystal is consistent with the diffraction spectrum 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), which indicates that Cs2CdCl4:0.005Pb 2+ Crystal. Pb 2+ The doping does not introduce any impurities.

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

[0065] Figure 5 The Cs2CdCl4:0.005Pb of Example 2 is given 2+ Room temperature afterglow luminescence spectrum of the crystal. The excitation light source is a 254nm mercury lamp. It can be seen from the figure that Pb 2+ The main emission peak is at 314nm. The afterglow luminescence comes from Pb 2+ of 3 P1→ 1 In addition, a broadband visible light long afterglow luminescence with a peak at 450nm was also observed.

[0066] Figure 6 The Cs2CdCl4:0.005Pb of Example 2 is given 2+ The room temperature afterglow decay curve of the long afterglow luminescent material. The excitation light source is a 245nm xenon lamp. It can be seen from the figure that in Cs2CdCl4:0.005Pb 2+ In the experiment, long afterglow luminescence at room temperature exceeding 600 seconds can be observed.

[0067] Example 3

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

[0069] Cesium carbonate (Cs2CO3), cadmium carbonate (CdCO3) and lead bromide (PbBr2) are used as raw materials. 2+ The molar ratio of the elements of Cs, Cd, and Pb in the formula Weigh the required compound raw materials, the mass of cesium carbonate (Cs2CO3) is 0.6294g, the mass of cadmium carbonate (CdCO3) is 0.2997g, and the mass of lead bromide (PbBr2) is 0.0708g, and put them together in a polytetrafluoroethylene liner; add 3mL hydrochloric acid and 3mL N, N-dimethylformamide (C3H7NO), mix and stir evenly, and then put them into the reactor. The reactor is placed in an oven, heated from 25℃ to 180℃ at a heating rate of 3℃ / min, and kept at 180℃ for 12h. The sample is then cooled from 180℃ to room temperature at a cooling rate of 2.5℃ / h. After the block crystal sample is washed with ethanol several times, it is placed in a vacuum oven at 60℃ for drying. After drying, it is ground into powder to synthesize the crystalline compound Cs2CdCl4:0.1Pb 2+ Long afterglow luminescent material.

[0070] Figure 1 The Cs2CdCl4:0.1Pb of Example 3 is given 2+ The X-ray diffraction pattern of the crystal is consistent with the diffraction peak of the standard Cs2CdCl4 crystal (PDF#72-1094). The synthesized long afterglow luminescent material has the crystal structure of Cs2CdCl4 (PDF#72-1094) (tetragonal system, space group I4 / mmm), which indicates that Cs2CdCl4:0.1Pb was successfully synthesized. 2+ Crystal. Pb 2+ The doping does not introduce any impurities.

[0071] Figure 2 The Cs2CdCl4:0.1Pb of Example 3 is given 2+ Thermoluminescence spectrum of the crystal. The excitation light source of the sample is a mercury lamp. The temperature of the sample excited by the mercury lamp is 300K. The thermoluminescence peak of the sample covers the temperature range from 303K to 400K.

[0072] Figure 7 The Cs2CdCl4:0.1Pb of Example 3 is given 2+ The room temperature long afterglow luminescence spectrum of the crystal. The excitation light source is a 254nm mercury lamp. It can be seen from the figure that Pb 2+ The main emission peak is at 314nm. The afterglow luminescence comes from Pb 2 + of 3 P1→ 1 In addition, a weaker long afterglow luminescence peak with a peak at 450nm was also observed.

[0073] Figure 8 The Cs2CdCl4:0.1Pb of Example 3 is given 2+ The room temperature afterglow decay curve of the crystal. The excitation light source is a 245nm xenon lamp. As can be seen from the figure, Cs2CdCl4:0.1Pb 2+ The room temperature long afterglow luminescence exceeds 120 seconds.

[0074] Example 4

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

[0076] Cesium carbonate (Cs2CO3), cadmium carbonate (CdCO3) and lead iodide (PbI2) are used as raw materials. Based on Cs2CdCl4:0.1Pb 2+The molar ratio of the elements of Cs, Cd, and Pb in the formula is used to weigh the required compound raw materials. The mass of cesium carbonate (Cs2CO3) is 0.6181 grams. The mass of cadmium carbonate (CdCO3) is 0.2944 grams, and the mass of lead iodide (PbI2) is 0.08746 grams. They are placed together in a polytetrafluoroethylene liner; 3mL of hydrochloric acid and 3mL of N,N-dimethylformamide (C3H7NO) are added, mixed and stirred evenly, and then placed in a reactor. The reactor is placed in an oven, heated from 25°C to 180°C at a heating rate of 3°C / min, and maintained at 180°C for 12 hours. The sample is then cooled from 180°C to room temperature at a cooling rate of 2.5°C / h. After the block sample is washed with ethanol several times, it is placed in a vacuum oven at 60°C for drying. After drying, it is ground into powder to synthesize the crystalline compound Cs2CdCl4:0.1Pb 2+ Long afterglow luminescent material.

[0077] Fig. 9 The Cs2CdCl4:0.1Pb of Example 4 is given 2+ X-ray diffraction pattern of the crystal. Fig. 9 The X-ray diffraction pattern shows that the Cs2CdCl4:0.1Pb 2+ It has the (PDF#72-1094) Cs2CdCl4 crystal structure (tetragonal system, space group I4 / mmm). Pb 2+ The doping does not introduce any impurities.

[0078] Fig.10 The ratio of Example 4 is Cs2CdCl4:0.1Pb 2+ Room temperature afterglow luminescence spectrum of long afterglow luminescent materials. The excitation light source is a 254nm mercury lamp. It can be seen from the figure that Pb 2+ A strong UVB long afterglow emission peak is given, with a peak at 314nm. The afterglow luminescence comes from Pb 2+ of 3 P1→ 1 S0 transition.

[0079] Fig.11 The ratio of Example 4 is given, which uses lead iodide (PbI2) as the raw material to synthesize Cs2CdCl4:0.1Pb 2+ The room temperature afterglow decay curve of the long afterglow luminescent material. The excitation light source is a 245nm xenon lamp. As can be seen from the figure, Cs2CdCl4:0.1Pb 2+ The room temperature long afterglow luminescence exceeds 600 seconds.

[0080] Fig.12 The Cs2CdCl4:0.1Pb of Example 4 is given2+ Thermoluminescence curve of the crystal. The excitation light source of the sample is a mercury lamp. The temperature of the sample excited by the mercury lamp is 300K. The heating rate of the sample is 1K / s. It can be seen from the figure that Cs2CdCl4:0.1Pb synthesized using lead iodide (PbI2) as raw material 2+ A strong thermoluminescence band appeared with a peak at 328K.

[0081] Example 5

[0082] An ultra-broad spectrum Cs2CdCl4:xPb 2+ Long afterglow luminescent material, with Cs2CdCl4 as the matrix and Pb 2+ It is the luminescent recombination center, and its chemical formula is Cs2CdCl4:0.005Pb 2+ , prepared by the following method:

[0083] Cesium carbonate (CsCl), cadmium carbonate (CdCl2) and lead bromide (PbBr2) are used as raw materials. Based on Cs2CdCl4:0.005Pb 2+ The molar ratio of the elements of Cs, Cd, and Pb in the formula is as follows: weigh the required compound raw materials, the mass of cesium carbonate (CsCl) is 0.6499 g, the mass of cadmium carbonate (CdCl2) is 0.3469 g, and the mass of lead bromide (PbBr2) is 0.00354 g, and put them together in a polytetrafluoroethylene liner; add 3mL hydrochloric acid and 3mL N,N-dimethylformamide (C3H7NO), mix and stir evenly, and then put them into the reactor. The reactor is placed in an oven, heated from 25℃ to 180℃ at a heating rate of 3℃ / h, and kept at 180℃ for 12h. Then the sample is cooled from 180℃ to room temperature at a cooling rate of 2.5℃ / h. After the block sample is washed with ethanol several times, it is placed in a vacuum oven at 60℃ for drying. After drying, it is ground into powder to synthesize the crystalline compound long afterglow luminescent material.

[0084] Fig.13 The Cs2CdCl4:0.005Pb of Example 5 is given 2+ The X-ray diffraction pattern of the crystal is consistent with the X-ray peak of Cs2CdCl4 crystal (PDF#72-1094). The synthesized long afterglow luminescent material has the crystal structure of Cs2CdCl4 (PDF#72-1094) (tetragonal system, space group I4 / mmm), which indicates that Cs2CdCl4:0.005Pb 2+ Crystal. Pb 2+ The doping does not introduce any impurities.

[0085] Fig.14 The Cs2CdCl4:0.005Pb of Example 5 is given 2+Room temperature afterglow luminescence spectrum of the crystal. The excitation light source is a 254nm mercury lamp. It can be seen from the figure that Pb 2+ It is the main emission peak, with a peak value at 314nm. Pb 2+ Room temperature long afterglow luminescence comes from Pb 2+ of 3 P1→ 1 S0 transition.

[0086] Fig.15 The Cs2CdCl4:0.005Pb of Example 5 is given 2+ The room temperature afterglow decay curve of the crystal. The excitation light source is a 245nm xenon lamp. In Cs2CdCl4:0.005Pb 2+ In the experiment, room temperature Pb was observed for more than 80 seconds. 2+ Long afterglow.

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

[0088] Example 6

[0089] Based on Cs2CdCl4:0.005Pb developed in Example 2 2+ Long afterglow luminescent materials, designed Fig.17 Visual anti-counterfeiting system. Based on ASCII code, information can be written into an 8×5 matrix. Cs2CdCl4:0.005Pb not placed in water 2+ It exhibits blue photoluminescence and long afterglow. Cs2CdCl4:0.005Pb 2+ After being placed in water, it has green photoluminescence and long afterglow luminescence under 254nm ultraviolet light excitation. Fig.17 In the visual anti-counterfeiting system, the code for green light under the excitation of a 254nm mercury lamp is 1, the code for blue light is 0, and the code for afterglow after the mercury lamp is turned off is 1, and the code for no afterglow is 0. Fig.17 We can see that the real information can only be displayed 0.5s after the mercury lamp is turned off. The information displayed when the mercury lamp is irradiated and 2s after the mercury lamp stops irradiating is false information.

[0090] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

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

1.

2. The ultra-wide spectrum Cs2CdCl4:xPb as claimed in claim 1 2+ The long afterglow luminescent material is characterized in that: The Cs2CdCl4:xPb 2+ The crystal structure of the long afterglow luminescent material is tetragonal and the space group is I4 / mmm.

3. The ultra-wide spectrum Cs2CdCl4:xPb as claimed in claim 1 2+ The long afterglow luminescent material is characterized in that: The Cs2CdCl4:xPb 2+ The long afterglow luminescent material can be excited by 254nm ultraviolet light or X-rays and produces long afterglow luminescence in the UVB band at room temperature.

4. An ultra-wide spectrum Cs2CdCl4:xPb as claimed in any one of claims 1 to 3 2+ Application of long afterglow luminescent materials in optical anti-counterfeiting and wearable devices.

5. An ultra-wide spectrum Cs2CdCl4:xPb as claimed in any one of claims 1 to 3 2+ The method for preparing a long afterglow luminescent material is characterized in that: The following steps are involved: (1) According to Cs2CdCl4:xPb 2+ The molar ratio of Cs, Cd and Pb in the compound raw materials containing Cs, Cd and Pb elements are weighed 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, put into a reactor for high temperature treatment, cool to room temperature after high temperature treatment, and then wash and dry the reaction product to obtain Cs2CdCl4:xPb 2+ Crystalline long afterglow luminescent material.

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

7. The ultra-wide spectrum Cs2CdCl4:xPb as claimed in claim 5 2+ The method for preparing a long afterglow luminescent material is characterized in that: In the 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 relative to the total mass of the element compound raw materials containing Cs, Cd and Pb is 6-8 mL / g.

8. The ultra-broad spectrum Cs2CdCl4:xPb as claimed in claim 5 2+ The method for preparing a long afterglow luminescent material is characterized in that: In the step (2), the heating rate of the high temperature treatment is 2.5-3.5°C / h, the temperature of the high temperature treatment is 160-200°C, the insulation time is 3-12h, and the cooling rate after the high temperature treatment is 2-3°C / h.

9. The ultra-wide spectrum Cs2CdCl4:xPb as claimed in claim 5 2+ The method for preparing a long afterglow luminescent material is characterized in that: The washing solvent in step (2) is ethanol.

10. The ultra-broad spectrum Cs2CdCl4:xPb as claimed in claim 5 2+ The method for preparing a long afterglow luminescent material is characterized in that: In the step (2), the drying temperature is 60-70° C. and the drying time is 10-12 h.

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