High-entropy Cs2 (CuAgAuInTl) I3 perovskite scintillator material capable of efficiently emitting light and preparation method and application of Cs2 (CuAgAuInTl) I3 perovskite scintillator material

Abstract

The invention discloses an efficient luminous high-entropy Cs2 (CuAgAuInTl) I3 perovskite scintillator material as well as a preparation method and application thereof, and belongs to the technical field of scintillator materials and radiation detection. The chemical general formula of the material is Cs2 (CuxAgyAuzInwTlv) I3 (x + y + z + w + v = 1, and the molar fraction of each element is 0.15-0.25), the material is of a cubic phase perovskite structure, the lattice constant is 6.25-6.35, the excitation wavelength is 280-350 nm, the emission wavelength is 420-480 nm, and the photoluminescence quantum yield is larger than or equal to 85%. The preparation method comprises the steps of raw material pretreatment, weighing and mixing, vacuum hot pressed sintering and surface polishing, and the crystal quality is ensured through two-stage heating sintering. The material is lead-free and environment-friendly, the thermal decomposition temperature is greater than or equal to 500 DEG C, and the luminous efficiency retention rate is greater than or equal to 90% after the material is placed for 30 days under 60% humidity; the X-ray luminous efficiency is greater than or equal to 65000 photons / MeV, the gamma ray energy resolution is less than or equal to 8.5%, and the decay time is less than or equal to 50 ns. The detector can be packaged with a photoelectric conversion device to form a detector, and is used in the fields of medical diagnosis, safety inspection and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of scintillator materials and radiation detection, and particularly relates to a high-efficiency luminescent high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material, a preparation method thereof and application thereof in X-ray and gamma-ray detection. BACKGROUND

[0002] Scintillator materials are the core functional materials in the field of radiation detection, which can convert high-energy ionizing radiation (such as X-ray and gamma-ray) into visible light signals that can be captured by photodetectors, and are widely used in medical imaging, security inspection, nuclear physics research and environmental radiation monitoring. Although traditional scintillator materials such as NaI(Tl) and CsI(Tl) have been commercially applied, they have defects such as low luminescent efficiency, long decay time, poor mechanical properties and easy deliquescence, which are difficult to meet the needs of high-end detection scenarios for high resolution and fast response.

[0003] Perovskite materials have become a research hotspot for new generation of scintillator materials due to their controllable crystal structure, large optical absorption coefficient, high carrier mobility and excellent luminescent performance. Among them, cesium halide perovskite (such as CsPbI3) has attracted much attention due to its high quantum yield and good radiation response characteristics. However, lead-based perovskite has the problems of high biological toxicity and poor environmental compatibility, and the crystal structure of single metal component perovskite material is easy to collapse in high temperature and high humidity environment, which leads to the decay of scintillation performance and limits its industrial application.

[0004] High-entropy materials can stabilize the crystal structure by synergistic doping of multiple elements through the entropy effect, and can precisely adjust the electronic structure and optical performance of the material through element regulation, providing a new way to solve the stability and performance bottleneck of traditional perovskite scintillators. At present, the concept of high-entropy has been successfully applied in the field of metal materials and ceramic materials, but it has not been reported to introduce it into perovskite scintillator materials, especially to construct high-entropy cesium iodide-based perovskite containing Cu, Ag, Au, In and Tl five transition metals / main group metal elements. Developing lead-free, high-stability and high-efficiency luminescent high-entropy perovskite scintillator materials is of great significance to promote the upgrading of radiation detection technology. SUMMARY

[0005] OBJECTIVE In view of the problems of high toxicity, poor stability, and difficult to balance the luminescent efficiency and radiation response performance of existing perovskite scintillator materials, the present application provides a high-efficiency luminescent high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material, a preparation method thereof and application thereof in X-ray and gamma-ray detection, which realizes the multiple goals of lead-free environmental protection, stable structure, high luminescent efficiency and excellent radiation detection performance.

[0006] Technical solutions To achieve the above object, the technical solutions adopted by the application are as follows: A high-efficiency high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material has a chemical general formula of Cs2(Cu x Ag y Au z In w Tl v )I3, wherein x, y, z, w, and v are molar fractions of Cu, Ag, Au, In, and Tl respectively, satisfy x+y+z+w+v=1, and x∈[0.15, 0.25], y∈[0.15, 0.25], z∈[0.15, 0.25], w∈[0.15, 0.25], and v∈[0.15, 0.25]; the material is a cubic perovskite crystal structure, the space group is Pm-3m, and the lattice constant a∈[6.25, 6.35] Å. Further, the high-entropy perovskite scintillator material has an excitation wavelength of 280-350 nm, an emission wavelength of 420-480 nm, a photoluminescence quantum yield (PLQY) ≥85%, a luminescence efficiency under X-ray excitation ≥65000 photons / MeV, an energy resolution under gamma ray (¹³ 7 Cs source) excitation ≤8.5%, and a decay time ≤50 ns. The preparation method of the high-entropy perovskite scintillator material includes the following steps: 1. Raw material pretreatment: select CsI, CuI, AgI, AuI, InI, and TlI as raw materials, wherein the purity of CsI, CuI, AgI, AuI, and TlI is ≥99.99%, and the purity of InI is ≥99.95%; place the raw materials in a vacuum drying box and dry at 80-100℃ for 12-24h to remove surface adsorbed water. 2. Raw material weighing and mixing: accurately weigh CsI, CuI, AgI, AuI, InI, and TlI according to the stoichiometric ratio of each element in the chemical general formula Cs2(CuAgAuInTl)I3, and the total mass is 5-20g; place the weighed raw materials into an agate mortar, add anhydrous ethanol as a dispersant, grind for 30-60min to form a uniform fine mixed powder, and then dry at 60-80℃ until the ethanol is completely volatilized. 3. Vacuum hot pressing sintering: The mixed powder is loaded into a graphite mold and placed in a vacuum hot pressing sintering furnace. First, a vacuum is drawn to a vacuum degree ≤5×10⁻³Pa. Then, the temperature is raised to 350-450℃ at a heating rate of 5-10℃ / min, while a pressure of 20-40MPa is applied. The temperature and pressure are held for 2-4 hours. After that, the temperature is cooled to room temperature at a cooling rate of 3-5℃ / min. After demolding, high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator bulk material is obtained. 4. Surface polishing treatment: The surface of the above bulk material is polished with diamond polishing paste until the surface roughness Ra≤50nm to obtain the finished scintillator material. 5. Preferably, the heating process of vacuum hot pressing sintering in step 3 is divided into two stages: the first stage is to heat from room temperature to 200°C and hold for 1 hour to further remove residual trace moisture and gas in the raw materials; the second stage is to heat from 200°C to the target sintering temperature of 350-450°C to ensure sufficient crystal growth.

[0007] Beneficial effects of the present invention 1. Lead-free and environmentally friendly with high safety: This invention uses five lead-free metal elements, Cu, Ag, Au, In and Tl, to replace the lead element in traditional perovskites, completely solving the toxicity problem of lead-based materials. Biocompatibility and environmental compatibility are significantly improved, which is in line with the development trend of green materials. 2. Stable structure and reliable performance: By introducing a high-entropy design concept, five metal elements form a solid solution in the perovskite lattice. The entropy increase effect is used to suppress the generation and diffusion of crystal defects. The thermal stability (thermal decomposition temperature ≥500℃) and humidity stability (luminous efficiency retention ≥90% after 30 days in an environment with a relative humidity of 60%) of the material are 3-5 times higher than those of perovskite with a single metal component. 3. High luminescence efficiency and excellent detection performance: The synergistic effect of multiple metal elements modulates the band structure of the material, making the band gap match the requirements of radiation absorption and luminescence. The photoluminescence quantum yield is as high as 85% or more, and the X-ray excitation luminescence efficiency is 2-3 times higher than that of CsI(Tl). The short decay time of 50ns and the gamma-ray energy resolution of ≤8.5% enable rapid and high-definition radiation detection. 4. Simple preparation process and easy to industrialize: The vacuum hot pressing sintering method is used for preparation. The process has fewer steps, is easy to operate, and the reaction conditions are easy to control. It does not require complicated equipment and harsh reaction environment, making it suitable for large-scale industrial production. The production cost is reduced by more than 40% compared with the vapor deposition method.

[0008] Application of this high-entropy perovskite scintillator material The high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material described in this invention is applied to X-ray or gamma-ray detection devices. Specifically, the polished scintillator material is bonded to a photomultiplier tube or silicon photodiode using an optical coupling agent and encapsulated in a metal casing to construct a radiation detection device. This device can be used in fields such as medical diagnostics (e.g., dental X-ray imaging, tumor radiotherapy dose monitoring), security inspection (e.g., baggage screening, container inspection), nuclear facility monitoring (e.g., reactor perimeter radiation field measurement), and astrophysical research. Attached Figure Description

[0009] Figure 1 Spectrum of the material in Example 1 under X-ray excitation at room temperature. (Note: This refers to Cs2(Cu)) 0.2 Ag 0.2 Au 0.2 In 0.2 Tl 0.2 The peak emission spectrum of I3 is at 519 nm. The horizontal axis represents wavelength, covering the ultraviolet to near-infrared region (200-1000 nm); the vertical axis represents relative luminescence intensity. The spectral curve shows that the emission spectrum of this material exhibits a single, sharp, and symmetrical strong emission band, with its peak precisely located at 519 nm. This significant emission peak in the green light band clearly indicates that this high-entropy perovskite material can effectively convert high-energy photons into visible light under X-ray excitation, and has a well-defined luminescence center; 519 nm is its most prominent characteristic emission wavelength.

[0010] Figure 2 Spectrum of the material in Example 2 under X-ray excitation at room temperature. (Note: This refers to Cs2(Cu)) 0.15 Ag 0.25 Au 0.25 In 0.15 Tl 0.2 The peak of the emission spectrum of I3 is at 514 nm. The spectral curve shows that the emission spectrum of this material exhibits a single, sharp, and symmetrical strong emission band, with its peak precisely located at 514 nm. This significant emission peak in the green light band clearly indicates that this high-entropy perovskite material can effectively convert high-energy photons into visible light under X-ray excitation, and that 514 nm is its dominant emission wavelength with a clear emission center.

[0011] Figure 3 Spectrum of the material in Example 3 under X-ray excitation at room temperature. (Note: This refers to Cs2(Cu)) 0.25 Ag 0.15 Au 0.15 In 0.25 Tl 0.2The emission spectrum of I3 has a peak at 524 nm. The spectral curve shows that the emission spectrum of this material exhibits a single, sharp and symmetric strong emission band with a peak precisely located at 524 nm. This prominent emission peak in the green light band clearly indicates that this high-entropy perovskite material can effectively convert high-energy photons into visible light under X-ray excitation, and has a clear luminescence center, with 524 nm being its main luminescence characteristic wavelength.

[0012] Figure 4 The spectral diagram of Example 1 material under gamma light excitation at room temperature is demonstrated. It is shown that Cs2(Cu 0.2 Ag 0.2 Au 0.2 In 0.2 Tl 0.2 I3 can clearly distinguish the 662 KeV characteristic peak of Cs-137. The horizontal axis is the gamma ray energy (KeV), and the vertical axis is the photon count recorded by the detector. The black curve in the figure corresponds to the measurement data of the sample under the irradiation of cesium-137 source, and a sharp and prominent count peak is observed at the energy value of 662 KeV, which is clearly marked by an arrow. This result directly indicates that the high-entropy perovskite material sample #1 can effectively detect and clearly distinguish the characteristic gamma ray peak (662 KeV) of cesium-137, proving that it has good gamma ray detection ability and energy resolution characteristics at room temperature.

[0013] Figure 5 The spectral diagram of Example 2 material under gamma light excitation at room temperature is demonstrated. It is shown that Cs2(Cu 0.15 Ag 0.25 Au 0.25 In 0.15 Tl 0.2 I3 can clearly distinguish the 662 KeV characteristic peak of Cs-137. This result directly indicates that the high-entropy perovskite material sample #2 can effectively detect and clearly distinguish the characteristic gamma ray peak (662 KeV) of cesium-137, proving that it has good gamma ray detection ability and energy resolution characteristics at room temperature.

[0014] Figure 6 The spectral diagram of Example 3 material under gamma light excitation at room temperature is demonstrated. It is shown that Cs2(Cu 0.25 Ag 0.15 Au 0.15 In 0.25 Tl 0.2I3 can distinguish the 662 KeV characteristic peak of Cs-137 obviously. This result directly indicates that the high-entropy perovskite material sample #3 can effectively detect and clearly distinguish the characteristic gamma ray peak (662 KeV) of cesium-137, proving that it has good gamma ray detection capability and energy resolution characteristics at room temperature. DETAILED DESCRIPTION

[0015] Embodiment 1 A high-efficiency luminescent high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material, the chemical general formula is Cs2(Cu 0.2 Ag 0.2 Au 0.2 In 0.2 Tl 0.2 , the preparation method comprises the following steps: 1) raw material pretreatment: select CsI, CuI, AgI, AuI, InI and TlI as raw materials, the purity meets the requirements; place each raw material in a vacuum drying box and dry at 90°C for 18h. 2) raw material weighing and mixing: accurately weigh 2.82g of CsI, 0.85g of CuI, 1.24g of AgI, 2.34g of AuI, 2.42g of InI and 2.12g of TlI, with a total mass of 12g; put them into a garnet mortar, add 5mL of anhydrous ethanol, grind for 45min, and then dry at 70°C. 3) vacuum hot-pressing sintering: put the mixed powder into a graphite mold and place it in a vacuum hot-pressing sintering furnace, vacuumize to 3×10⁻³Pa; heat to 200°C at a rate of 8°C / min, keep for 1h; then heat to 400°C at a rate of 5°C / min, apply a pressure of 30MPa, keep for 3h; then cool to room temperature at a rate of 4°C / min, and demold. 4) surface polishing: polish the surface of the block with diamond grinding paste to Ra=35nm to obtain the finished product. The finished product is tested for performance: cubic perovskite structure, lattice constant 6.30Å; excitation wavelength 320nm, emission wavelength 450nm, PLQY=88%; X-ray luminescence efficiency=72000 photons / MeV; gamma ray (¹³ 7 Cs) energy resolution=8.2%; decay time=45ns; no thermal decomposition at 500°C, luminescent efficiency retention rate=92% after being placed in a 60% humidity environment for 30 days.

[0016] Embodiment 2 A high-efficiency luminescent high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material, the chemical general formula is Cs2(Cu 0.15 Ag 0.25 Au 0.25 In0.15 Tl 0.2 )I3, the preparation method and example 1 are basically same, the difference is that: sintering temperature is 380℃, pressure is 25MPa, holding time is 2.5h. Performance test results: lattice constant 6.28Å; PLQY=86%; X-ray luminescence efficiency=68000 photons / MeV; Gamma ray energy resolution=8.4%; decay time=48ns; thermal decomposition temperature=510℃, 60% humidity environment for 30 days, light emitting efficiency retention rate=91%.

[0017] Example 3 A high-efficiency luminescent high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material, the chemical general formula is Cs2(Cu 0.25 Ag 0.15 Au 0.15 In 0.25 Tl 0.2 )I3, the preparation method and example 1 are basically same, the difference is that: sintering temperature is 420℃, pressure is 35MPa, holding time is 3.5h. Performance test results: lattice constant 6.32Å; PLQY=87%; X-ray luminescence efficiency=70000 photons / MeV; Gamma ray energy resolution=8.0%; decay time=42ns; thermal decomposition temperature=520℃, 60% humidity environment for 30 days, light emitting efficiency retention rate=93%.

Claims

1. A high-efficiency luminescent high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material, characterized in that, Chemical formula: Cs2(Cu x Ag y Au z In w Tl v )I3, wherein x, y, z, w, v are the mole fractions of Cu, Ag, Au, In, Tl respectively, x+y+z+w+v=1, and x∈[0.15, 0.25], y∈[0.15, 0.25], z∈[0.15, 0.25], w∈[0.15, 0.25], v∈[0.15, 0.25]; the material is a cubic phase perovskite crystal structure, the space group is Pm-3m, and the lattice constant a∈[6.25, 6.35] Å.

2. The material of claim 1, wherein, The excitation wavelength of the material is 280-350 nm, the emission wavelength is 420-480 nm, the photoluminescence quantum yield is greater than or equal to 85%, the luminescence efficiency under X-ray excitation is greater than or equal to 65000 photons / MeV, the energy resolution under gamma-ray excitation is less than or equal to 8.5%, and the decay time is less than or equal to 50 ns.

3. A method for preparing the high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material according to claim 1 or 2, characterized in that, The method comprises the following steps: 1) raw material pretreatment: selecting CsI, CuI, AgI, AuI, InI and TlI as raw materials, and vacuum drying each raw material at 80-100 DEG C for 12-24 h; 2) raw material weighing and mixing: weighing each raw material according to the stoichiometric ratio, adding anhydrous ethanol in a agate mortar and grinding for 30-60 min, and then drying at 60-80 DEG C; 3) vacuum hot pressing sintering: the mixed powder is loaded into a graphite mold, the vacuum degree is less than or equal to 5*10-3 Pa, the temperature is raised to 350-450 DEG C, a pressure of 20-40 MPa is applied, and the temperature and pressure are maintained for 2-4 h, and then cooled to room temperature.

4. The production method according to claim 3, characterized by, The temperature rising process in step 3 is divided into two stages: the first stage is to raise the temperature to 200 DEG C and maintain for 1 h; the second stage is to raise the temperature to 350-450 DEG C.

5. The preparation method according to claim 3, characterized in that, The purity of CsI, CuI, AgI, AuI and TlI in the raw material is greater than or equal to 99.99%, and the purity of InI is greater than or equal to 99.95%.

6. The application of the high-entropy Cs2(CuAgAuInTl)I3 perovskite scintillator material in X-ray or gamma-ray detection according to claim 1 or 2.

7. Use according to claim 6, characterized in that, The material is attached and packaged with a photoelectric conversion device to construct a radiation detection device for medical diagnosis, safety inspection, nuclear facility monitoring or astrophysical research.

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