Study On The Preparation And Properties Of Rare Earth Doped KCl_1-xBr_x Mixed Crystal

In recent years,alkali metal halide crystals and rare earth materials have become the research hotspots of materials science at home and abroad due to their excellent properties.Alkali metal halide crystals and rare earth materials have broad application prospects in optoelectronic devices,infrared windows,solid-state lighting,tunable lasers,thermoluminescence dosimeters,food detection,optical communication systems,and luminescent probes.However,the shortcomings of alkali metal halide single crystals,such as low hardness,easy deliquescence,and weak luminescence,limit their practical application.Therefore,the mechanical,thermal and optical properties of conventional alkali metal halide single crystals can be improved by preparing alkali metal halide mixed crystals or doping ions.Therefore,in this paper,the properties of rare earth element Ce and Pr doped alkali metal halide single crystal and mixed crystal were studied.Ce and Pr single or double doped KCl,KBr single crystal and binary mixed crystal were prepared,and the crystal structure,optical and mechanical properties were systematically studied,the influence of rare earth ions on crystal structure,morphology,hardness and luminescence properties was discussed.The following are considered as the important aspects of this research work.A series of crystals of KCl:Ce,KBr:Ce,KCl:Pr,KBr:Pr,KCl_1-xBr_x:Ce,KCl_1-xBr_x:Pr and KCl_1-xBr_x:Ce,Pr were prepared by using the resistance heating Czochralski（Cz）method.Through XRD,IP,SEM,UV-VIS and PL characterization tests of the prepared samples.XRD,IP and SEM analysis show that the rare earth ions Ce and Pr have been successfully incorporated into the crystal lattice,mainly exist as Ce³⁺and Pr³⁺ions,and the crystal particle size ranges from 3 to 12μm.The mechanical and optical properties of the studied crystals have been found to be improved by Ce or Pr doping.Rare earth-doped alkali metal halide single crystals and mixed crystals show obvious absorption in the absorption spectrum.The KCl:Ce,KBr:Ce and KCl_1-xBr_x:Ce crystals have emission peaks within 350-400 nm,which corresponds to the 5d→4f transition of Ce ions,KCl:Pr,KBr:Pr and KCl_1-xBr_x:Pr crystals have emission peaks of different intensities in the range of 500-600 nm,corresponding to the ³H₄→³P₂,³H₄→³P₁,³H₄→³P₀,³P₂→³H₆ and ³P₀→³H₆transition of Pr ions.Energy transfer occurs between Ce³⁺and Pr³⁺in KCl_1-xBr_x:Ce,Pr crystal,an excitation peak was found at 275 nm,corresponding to the4f→5d transition of Ce³⁺and Pr³⁺,and an emission peak caused by the 5d→4f transition of Ce³⁺ions was found at 360 nm,a few weak emission peaks observed at 457 nm,478 nm,504 nm and576 nm are related to the ³P₁→³H₄,³P₀→³H₄,³P₂→³H₆ and ³P₀→³H₆ transitions of Pr³⁺ions.The luminescence intensity of KCl_1-xBr_x:Ce,Pr crystal is higher than KCl_1-xBr_x:Ce or KCl_1-xBr_x:Pr crystal,and the crystal of KCl_0.5Br_0.5:0.01Ce,0.006Pr has the strongest emission peak.The hardness of the crystal is found to increase with the increase of Ce,Pr ion concentration and the crystal composition.When x=0.5,the hardness of KCl_1-xBr_x:Ce,Pr crystal reaches the maximum value,the crystal hardness of KCl_0.5Br_0.5:0.01Ce,0.006Pr crystal is 30.6 kg/mm².