Study On Fabrication And Performance Of Cerium Doped Calcium/Barium Fluoride Transparent Ceramic

Cerium doped calcium fluoride nanoparticles were synthesized by co-precipitation method using Ca(N03)2, KF and Ce(NO3)3as raw materials in deionzed water. Nanoparticles were characterized on their lattice structure, morphology and optical properties by means of X-ray diffraction, TEM, SEM, fluorescence spectrometer, respectively. The results indicated that the lattice parameter changed with Ce3+doped. The appearance of (200) peak in XRD diagram is a signature of Ce3+incorporation in CaF2host. The solid solution of CaF2-CeF3can be stated in CexCa1-xF2+x composition, which maintain fluorite structure with the doping content up to10%. Nanoparticles were spherical monodispersed and an average diameter of25nm. UV-Vis absorption spectra reveals that the peak located in206nm,264nm and290nm, among them the peak206nm can be ascribe to the absorption of the base CaF2and Ce3+ions, the peak290nm was due to the characteristics absorption of Ce3+ions. The excited peak was located in307nm, the emission of319nm and336nm were originated from the outermost electron of the Ce3+ions5d1â†'2F7/2and5d1â†'2F5/2energy level transition respectively. The photoluminescence intensity reached a maximum when the doping content was5mol%, and then was weakened due to the Concentration quenching. The process of calcination could also improve the optical properties, which the temperature200℃was the best.In order to prepare the Ce3+:BaF2transparent ceramic of high quality without the crystal powder, Ce3+:BaF2nano-particles prepared via co-precipitation have been investigated for reaction sequence and concentration of reactants. Nano-particles were characterized by means of X-ray diffraction, SEM, TEM, DSC-TG, ICP and FTIR respectively. The result indicated that the powder which synthesized by the condition of reverse reaction was crystalline precipitates in single phase, XRD peaks shifts to low angle. Grain size decreases with the higher F-concentration. The grain morphology from a long strip gradually transformed into the cubic flake. When the Ce3+doping content above a4mol, there were second-phase of BaCeOF3dispersed in the powder. ICP test results show that actual doping value was close to the theoretical value. The absorption peak was due to the characteristics absorption of Ce3+ions. The transparent ceramic was prepared by hot-prssing way inT2,30Mpa using the powder synthesized ahead. It can be seen that some closed pores existed in the grains from the picture of cross section. After superficial corrosion, grain boundary could be clearly seen from the microscope images, No second phase particles existd in the grain boundary.When the sintering temperature was inT1, pores were always located inside the grain, meanwhile the temperature above T3, the pores located in the corner of grain boundary. The X-ray induced luminescence (XLE) intensity reached a maximum when the doping content was0.1mol%, lower than in the ceramic prepared by powder crystal. The light yield of0.1mol%Ce3+:BaF2was1.5times than the sample without Ce3+doped. The emission spectrum which was under ultraviolet excitation was similar to the luminescence spectra of X-ray induced emission, the fluorescence decay time descend with the increasing Ce3+content.