Fabrication and Microstructure of Y3+ :CaF2 Transparent Ceramics.

Y3+ : CaF2 powders were synthesized by chemical coprecipitation method, and transparent ceramics were fabricated by vacuum hot pressing sintering method. Characteristics of the as-synthesized powders were investigated by XRD, SEM and TEM techniques, the relationship between microstructure and transmittance of transparent ceramics were also analyzed. Crystal structures of as-synthesized Y3+ : CaF2 powders belong to single fluorite phase. With the Y3+ doping content increases, the average particles sizes decrease and the lattice constants increase from 5.452 1 Å to 5.465 5 Å. The 5% Y3+ :CaF2 transparent ceramics sintered at 900 °C for 3 h exhibits the highest transmittance, and the transmittance at 500 and 1 500 nm are 73. 1% and 86.4%, respectively. Microstructure of ceramics are modified by the Y3+ doping content and sintering temperatures. For a low growth velocity, it is not easy to eliminate the residual pores, while for a higher growth velocity, residual pores are easily embedded within grains. Both cases will reduce the transmittance of transparent ceramics. This work provides a reference for the preparation of high-quality composite CaF2 transparent ceramics. [ABSTRACT FROM AUTHOR]