A chloride ultraviolet afterglow material

Abstract

The present invention provides a chloride ultraviolet afterglow material. The structural formula of the material is Cs2NaScCl6:xPb, where 0.005≤x≤0.1. The preparation method comprises weighing and mixing a Cs-containing compound, a Na-containing compound, a Sc-containing compound, and a Pb-containing compound, followed by adding concentrated hydrochloric acid; and then sealing and reacting to obtain a target product. The resulting material, upon irradiation with a deep ultraviolet light source (254nm), can continuously emit a 380-390nm ultraviolet afterglow, with a decay time of more than 1 hour.

Description

Technical Field

[0001] The invention relates to the technical field of materials, in particular to a chloride ultraviolet afterglow material. Background Art

[0002] Afterglow materials can store external excitation light energy and continue to emit light for a period of time after the excitation light source is turned off, with the light intensity gradually decaying. They are widely used in optical storage, night guidance, multi-mode anti-counterfeiting, and bio-imaging. Among them, ultraviolet light has higher photon energy than visible light and near-infrared light, showing special application value, such as acting as a material excitation medium, sterilization, and promoting vitamin synthesis. Therefore, ultraviolet afterglow materials have gradually received attention and research and development, such as: Ca2Al2SiO7:Pr 3+ ,LiScGeO4:Bi 3+ ,YBO3:Pr 3+ However, the lattice energy of oxide materials is relatively high (~3000 kJ mol -1 ), which requires long-term high-temperature sintering (generally above 1300°C) and is therefore heavily dependent on electric thermal energy.

[0003] In comparison, chloride materials based on ionic bonding have lower lattice energy (generally less than 1000 kJ mol -1 ), so it supports the liquid phase synthesis strategy under low temperature environment. In recent years, chloride afterglow materials have been gradually explored, such as Cs2Na 1-x Ag x InCl6:Mn 2+ 、Cs2NaScCl6:Tb 3+ 、Cs2NaInCl6:Ag,Bi、Cs2(Na 0.9 Ag 0.1 In) 1-x Zr x Cl6, etc. However, compared with oxides, chloride materials have a smaller band gap and are more difficult to design for UV emission. Therefore, UV afterglow materials based on chloride systems have not yet been deeply explored.

[0004] The present invention proposes a novel method based on Cs2NaScCl6:Pb 2+ The chloride ultraviolet afterglow material can continuously emit ultraviolet afterglow with a peak position near 385nm after being irradiated by a deep ultraviolet light source (254nm), and its decay time can be maintained for more than 1h. Summary of the Invention

[0005] The purpose of the present invention is to provide a chloride ultraviolet afterglow material (Cs2NaScCl6:xPb2+ , 0.005≤x≤0.1). Upon irradiation with deep ultraviolet light, such as 254nm, the material produces ultraviolet afterglow emission with a peak near 385nm, specifically covering a range of approximately 320-450nm. After 5 minutes of 254nm deep ultraviolet irradiation, the ultraviolet afterglow decays for more than 1 hour.

[0006] The technical solution of the present invention is:

[0007] A chloride ultraviolet afterglow material has a structural formula of Cs2NaScCl6:xPb, 0.005≤x≤0.1.

[0008] After being energized by 254nm deep ultraviolet light, the material produces ultraviolet afterglow emission with a peak position near 385nm, and the specific emission peak covers the range of 320-450nm.

[0009] The preparation method of the chloride ultraviolet afterglow material comprises the following steps:

[0010] (1) Weighing and mixing a Cs-containing compound, a Na-containing compound, a Sc-containing compound, and a Pb-containing compound in a polytetrafluoroethylene-lined reactor;

[0011] Wherein, the Cs-containing compound is a chloride or carbonate of Cs; the Na-containing compound is a chloride or carbonate of Na; the Sc-containing compound is a chloride or oxide of Sc; the Pb-containing compound is a chloride or oxide of Pb;

[0012] The proportions of the above salts are based on the corresponding molar ratios of Cs2NaScCl6:xPb, i.e., Cs:Na:Sc:Pb=2:1:1:x; 0.005≤x≤0.1;

[0013] (2) Add concentrated hydrochloric acid to the reactor; add 4-12 mL of concentrated hydrochloric acid for every 2 mmol of CsCl;

[0014] The concentration of the concentrated hydrochloric acid is 30-38wt%.

[0015] (3) Seal the reactor and heat it at 150-200 ℃ Keep warm for 3-12 hours, and then cool naturally to room temperature;

[0016] (4) washing the crystal product with anhydrous ethanol;

[0017] (5) Dry the product at 40-80°C for about 1-5 hours and grind it to obtain the target product in powder form.

[0018] The essential features of the present invention are:

[0019] From the above similar literature, we can see that different luminescence properties can be obtained by doping different ions based on the Cs2NaScCl6 matrix. The band gap of this matrix is ​​relatively wide (>4.0eV), which is suitable for ultraviolet luminescence design. The present invention prepares a new material Cs2NaScCl6:Pb 2+ , by doping Pb 2+ Introducing luminescence energy levels to induce ultraviolet luminescence properties. Due to different valence states, Pb 2+ After the addition, lattice defects are caused, which can capture and store electrons. After the excitation light is turned off, the captured electrons can be gradually released and stored in Pb 2+ The luminescence process is completed at the point where the ultraviolet afterglow phenomenon occurs.

[0020] The beneficial effects of the present invention are:

[0021] (1) The present invention realizes ultraviolet afterglow emission based on the chloride system, fills the gap in the academic community, and promotes the development of the afterglow field.

[0022] (2) The material of the present invention can be excited by deep ultraviolet light such as 254 nm, avoiding the use of dangerous light sources such as X or gamma rays.

[0023] (3) Oxides usually require a solid phase environment of >1300°C. The hydrothermal synthesis temperature of the present invention is 180°C, which greatly reduces the reaction temperature compared to oxides and reduces the consumption of electric thermal energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the XRD spectrum of Cs2NaScCl6:0.03Pb obtained in Example 1;

[0025] Figure 2 is the fluorescence emission spectrum of Cs2NaScCl6:0.03Pb obtained in Example 1, with an excitation wavelength of 295 nm;

[0026] Figure 3 The fluorescence excitation spectrum of Cs2NaScCl6:0.03Pb obtained in Example 1, with a monitoring wavelength of 385 nm;

[0027] Figure 4 is the fluorescence emission spectrum of Cs2NaScCl6:0.03Pb obtained in Example 1, with an excitation wavelength of 265 nm;

[0028] Figure 5 The fluorescence excitation spectrum of Cs2NaScCl6:0.03Pb obtained in Example 1 is monitored at a wavelength of 500 nm;

[0029] Figure 6The afterglow emission spectrum of Cs2NaScCl6:0.03Pb obtained in Example 1, the charging light source is 254nm, and the charging time is 5min;

[0030] Figure 7 This is the afterglow decay spectrum of Cs2NaScCl6:0.03Pb obtained in Example 1, the charging light source is 254nm, the charging time is 5min, and the monitoring wavelength is 385nm;

[0031] Figure 8 is the XRD spectrum of Cs2NaScCl6:0.005Pb obtained in Example 2;

[0032] Figure 9 This is the afterglow emission spectrum of Cs2NaScCl6:0.005Pb obtained in Example 2, the charging light source is 254nm, and the charging time is 5min;

[0033] Figure 10 This is the afterglow decay spectrum of Cs2NaScCl6:0.005Pb obtained in Example 2, the charging light source is 254nm, the charging time is 5min, and the monitoring wavelength is 380nm;

[0034] Figure 11 is the XRD spectrum of Cs2NaScCl6:0.1Pb obtained in Example 3;

[0035] Figure 12 This is the afterglow emission spectrum of Cs2NaScCl6:0.1Pb obtained in Example 3, the charging light source is 254nm, and the charging time is 5min;

[0036] Figure 13 This is the afterglow decay spectrum of Cs2NaScCl6:0.1Pb obtained in Example 3, the charging light source is 254nm, the charging time is 5min, and the monitoring wavelength is 390nm;

[0037] Figure 14 This is a comparison chart of the afterglow decay of Cs2NaScCl6:0.005Pb, Cs2NaScCl6:0.03Pb and Cs2NaScCl6:0.1Pb obtained in Examples 1-3;

[0038] Figure 15 This is a graph showing the dependence of the afterglow intensity of Cs2NaScCl6:xPb (x=0.005, 0.01, 0.03, 0.05, 0.07, 0.1) obtained in Example 4 on the Pb doping concentration 60 seconds after turning off the 254nm charging light source, and the charging time is 5 minutes. DETAILED DESCRIPTION

[0039] Example 1: Cs2NaScCl6:0.03Pb sample

[0040] The preparation method of the present invention comprises the following steps: weighing 2 mmol CsCl (0.3367 g) powder, 1 mmol NaCl (0.0584 g) powder, 1 mmol ScCl3 (0.1513 g) powder and 0.03 mmol PbCl2 (0.0083 g) powder into a polytetrafluoroethylene-lined reactor, adding 4 mL of concentrated hydrochloric acid (30 wt%), placing the mixture into the reactor and sealing the reactor, keeping the mixture at 200° C. for 12 hours, and cooling the mixture naturally to room temperature. The obtained product is washed three times with ethanol, dried at 40° C. for about 5 hours, and then taken out and crushed to obtain the final product.

[0041] Test conditions: The crystal structure of the samples was determined using a Rigaku X-ray diffractometer, using a Cu target as the radiation source, a tube voltage of 40 kV, a tube current of 40 mA, a scan step of 0.02°, a scan speed of 15° / min, and a scan range of 10°-60°. The emission spectra, excitation spectra, afterglow emission spectra, and afterglow decay spectra of the samples were obtained using an FS-5 spectrometer.

[0042] Experimental results: Figure 1 The XRD spectrum of Cs2NaScCl6:0.03Pb is given. It can be seen that a crystalline product has been obtained through this experimental scheme;

[0043] Figure 2 The fluorescence emission spectrum of Cs2NaScCl6:0.03Pb under 295nm excitation is given. The emission peak is at 385nm, corresponding to Pb 2+ Ultraviolet luminescence band;

[0044] Figure 3 The fluorescence excitation spectrum of Cs2NaScCl6:0.03Pb when monitoring the emission at 385nm is given, which shows two effective excitation peaks at 265 and 295nm, corresponding to the band gap transition and Pb 2+ absorption;

[0045] Figure 4 The fluorescence emission spectrum of Cs2NaScCl6:0.03Pb under 265nm excitation is given, which shows two effective emission peaks at 385 and 500nm, corresponding to Pb 2+ and self-trapped state emission of the matrix;

[0046] Figure 5 The fluorescence excitation spectrum of Cs2NaScCl6:0.03Pb when monitoring the emission at 500 nm is given. The excitation peak is located at 265 nm, corresponding to the band gap transition;

[0047] Figure 6 The afterglow emission spectrum of Cs2NaScCl6:0.03Pb after 5 minutes of pre-charging at 254nm is shown. 2+ The ultraviolet afterglow emission has a peak at 385nm, indicating that the sample has ultraviolet afterglow emission characteristics;

[0048] Figure 7 The afterglow decay spectrum of Cs2NaScCl6:0.03Pb after 5 minutes of pre-charging at 254nm is given. The monitoring wavelength is 385nm. It can be seen that after 60 minutes of decay, the afterglow signal is still higher than the background noise, indicating that the ultraviolet afterglow decay time of the sample is greater than 1h.

[0049] Example 2: Cs2NaScCl6:0.005Pb sample

[0050] The preparation method of the present invention is as follows: 1 mmol Cs2CO3 (0.3258 g) powder, 0.5 mmol Na2CO3 (0.0530 g) powder, 0.5 mmol Sc2O3 (0.0690 g) powder and 0.005 mmol PbO (0.0011 g) powder are weighed in a polytetrafluoroethylene liner, 12 mL concentrated hydrochloric acid (36 wt%) is added, and the mixture is placed in a reactor, kept warm at 180°C for 6 hours, and naturally cooled to room temperature. The obtained product is washed with ethanol 3 times and dried at 60°C for about 3 hours to obtain the final product.

[0051] Test conditions: the same as in Example 1.

[0052] Experimental results: Figure 8 The XRD spectrum of Cs2NaScCl6:0.005Pb is given. It can be seen that a crystalline powder product has been obtained through this experimental scheme;

[0053] Figure 9 The afterglow emission spectrum of Cs2NaScCl6:0.005Pb is given, with the emission peak at 380nm;

[0054] Figure 10 Given is the afterglow decay spectrum of Cs2NaScCl6:0.005Pb after 5 minutes of pre-charging at 254nm, with the monitoring wavelength being 380nm.

[0055] Example 3: Cs2NaScCl6:0.1Pb sample

[0056] The preparation method of the present invention comprises the following steps: weighing 2 mmol CsCl (0.3367 g) powder, 1 mmol NaCl (0.0584 g) powder, 0.5 mmol Sc2O3 (0.0690 g) powder and 0.1 mmol PbCl2 (0.0278 g) powder into a polytetrafluoroethylene liner, adding 8 mL concentrated hydrochloric acid (36 wt%), charging the mixture into a reactor, keeping the mixture at 150° C. for 3 hours, cooling the mixture naturally to room temperature, washing the obtained product with ethanol three times, and drying the mixture at 80° C. for about 1 hour to obtain the final product.

[0057] Test conditions: the same as in Example 1.

[0058] Experimental results: Figure 11 The XRD spectrum of Cs2NaScCl6:0.1Pb is given. It can be seen that a crystalline product has been obtained through this experimental scheme;

[0059] Figure 12 The afterglow emission spectrum of Cs2NaScCl6:0.1Pb is given, with the emission peak at 390nm;

[0060] Figure 13 Given is the afterglow decay spectrum of Cs2NaScCl6:0.1Pb after 5 minutes of pre-charging at 254nm, with the monitoring wavelength being 390nm.

[0061] Figure 14 This is a comparison chart of the afterglow decay of Cs2NaScCl6:0.005Pb, Cs2NaScCl6:0.03Pb and Cs2NaScCl6:0.1Pb obtained in Examples 1-3. The sample doped with 0.03Pb has stronger afterglow intensity and longer decay time.

[0062] Example 4: Cs2NaScCl6:xPb (x=0.005, 0.01, 0.03, 0.05, 0.07, 0.1) samples

[0063] The preparation method of the present invention comprises the following steps: weighing 2 mmol CsCl (0.3367 g) powder, 1 mmol NaCl (0.0584 g) powder, 1 mmol ScCl3 (0.1468 g) powder and x mmol PbCl2 (0.28711*x g) powder into a polytetrafluoroethylene liner, adding 12 mL of concentrated hydrochloric acid (38 wt%), charging the mixture into a reactor, keeping the mixture at 180° C. for 3 hours, cooling the mixture naturally to room temperature, washing the obtained product with ethanol three times, and drying the mixture at 70° C. for about 3 hours to obtain the final product.

[0064] Test conditions: the same as in Example 1.

[0065] Experimental results: Figure 15 The graph shows the dependence of the afterglow intensity of Cs2NaScCl6:xPb (x=0.005, 0.01, 0.03, 0.05, 0.07, 0.1) on the Pb doping concentration 60s after turning off the 254nm charging light source. It can be seen that the sample has better ultraviolet afterglow performance when doped with 0.03Pb.

[0066] Matters not covered by the present invention are known technologies.

Claims

1. A chloride ultraviolet afterglow material, characterized by The structural formula of the material is Cs2NaScCl6:xPb, 0.005≤x≤0.

1.

2. The chloride ultraviolet afterglow material according to claim 1, wherein the material generates ultraviolet afterglow emission with a peak position near 385 nm after irradiation with 254 nm deep ultraviolet light for 5 minutes.

3. The method for preparing the chloride ultraviolet afterglow material according to claim 1, wherein the method comprises the steps of: (1) Weighing and mixing a Cs-containing compound, a Na-containing compound, a Sc-containing compound, and a Pb-containing compound in a polytetrafluoroethylene-lined reactor; in, The Cs-containing compound is a chloride or carbonate of Cs; the Na-containing compound is a chloride or carbonate of Na; the Sc-containing compound is a chloride or oxide of Sc; the Pb-containing compound is a chloride or oxide of Pb; The ratio of the above salts is based on the corresponding amount of substance in Cs2NaScCl6:xPb, that is, Cs: Na: Sc: Pb = 2: 1: 1: x; 0.005≤x≤0.1; (2) Add concentrated hydrochloric acid to the reactor; add 4-12 mL of concentrated hydrochloric acid for every 2 mmol of CsCl; (3) Seal the reactor and keep it at 150-200°C for 3-12 hours. After the end of the heat preservation, cool it naturally to room temperature. (4) washing the crystal product with anhydrous ethanol; (5) Dry the product at 40-80°C for 1-5 hours to obtain the desired product in powder form.

4. The method for preparing a chloride ultraviolet afterglow material according to claim 3, wherein the concentration of the concentrated hydrochloric acid is 30-38 wt%.

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