Photoluminescence/radioluminescence Properties And Stability Of Mn²⁺ Doped Cs₃Cu₂I₅ Powder

Fluorescent nuclear cell（NB）consisting of scintillator and photovoltaic device（PVD）has been widely concerned due to the relatively high conversion efficiency,small size and high reliability.In view of device structure,the radiation conversion efficiency and stability of scintillator determine the performance of the device.In order to achieve high efficiency,scintillation materials are required to feature with high radioluminescence efficiency and matched emission peak with the response of PVDs.However,the present scintillators still have some problems,such as low light yield,poor stability,inconsistent response with photovoltaic device,etc.Obviously,the performance of these scintillators can’t meet the above requirements by now.Therefore,it is urgent to develop novel scintillators with high radioluminescence intensity and proper emission wavelength.In this thesis,we mainly developed an efficient and stable Mn²⁺doped Cs₃Cu₂I₅scintillator,studied its photoluminescence/radioluminescence mechanism,and finally fabricated an efficient and stable nuclear battery based on as-prepared Cs₃Cu₂I₅:Mn and Gallium arsenide PVD.The main contents and experimental results of this thesis are as follows:（1）Preparation,structure characterization and property regulation of Cs₃Cu₂I₅ and Cs₃Cu₂I₅:Mn scintillators.A series of Cs₃Cu₂I₅:Mn phosphors with different doping concentrations of Mn²⁺were prepared by mechanical-grinding vacuum sintering method.The characterization of the phase and microstructure of the materials confirmed that Mn²⁺was successfully introduced into the lattice and occupied Cu⁺sites.The properties of the scintillator were optimized by changing the type of precursors,the ratios of raw materials and the synthetic conditions（sintering time,sintering temperature,etc.）.In addition,the effects of precursors on the radioluminescence intensity of the material was preliminarily explored.Through inspecting the evolution of the radioluminescence properties,the optimized chemical composition and preparation conditions were selected.At last,we obtained a scintillator with an ultra-high light yield of～67000 ph/Me V at the emission wavelength of 564 nm,which is the highest value of rare-earth-free materials at present.（2）Photoluminescence and radioluminescence properties of Cs₃Cu₂I₅ and Cs₃Cu₂I₅:Mn scintillators.The luminescence properties of Cs₃Cu₂I₅ and Cs₃Cu₂I₅:Mn scintillators were measured,including photoluminescence intensity,quantum yield,lifetime,radioluminescence intensity,etc.The photoexcitation spectrum of Cs₃Cu₂I₅:Mn is composed of intrinsic strong absorption band with emission center located at 300nm and weak absorption band located at 384 nm（⁶A₁（6S）（1）⁴T₂（4D））and 485 nm（⁶A₁（6S）（1）⁴T₂（4G））,respectively.Detailed investigation was carried out to find out why the luminescence properties of STEs were different under the excitation of UV light or X-ray.The photoluminescence and radioluminescence mechanisms of pure Cs₃Cu₂I₅ and Cs₃Cu₂I₅:Mn were revealed by fluorescence lifetime and fluorescence spectrum tests.（3）Stability of Cs₃Cu₂I₅ and Cs₃Cu₂I₅:Mn scintillators and their application in nuclear Batteries.By changing the environment conditions（such as,temperature,humidity,irradiation dose,etc.）of Cs₃Cu₂I₅ and Cs₃Cu₂I₅:Mn scintillator,the moisture resistance,anti-irradiation damage ability and thermal stability of scintillator were studied to evaluate application potential of scintillator materials.All of the experimental results demonstrate that Cs₃Cu₂I₅:Mn scintillator processes excellent stability.For the sake of further improving the long-term air stability of the material,we proposed a purification strategy using n-butanol to purify the sample.The irradiation stability of purified Cs₃Cu₂I₅:Mn has been greatly improved.The radioluminescence intensity of Cs₃Cu₂I₅:Mn can maintain 95%of its initial value after the irradiation dose of 2590 Gy at 333 K.Finally,an efficient and stable nuclear battery based on Cs₃Cu₂I₅:Mn and Gallium arsenide PVD was prepared,and its output power increased by 237%compared with that without scintillator.