Fabrication, microstructure, mechanical and luminescence properties of transparent Yb3+-doped Sr5(PO4)3F nanostructured ceramics

The Sr-5(PO4)(3)F (S-FAP) crystal material is regarded as one of the most ideal optical materials for diode pumping owing to its huge absorption and emission cross sections and long fluorescence lifespan. In this investigation, S-FAP powders with varying Yb concentrations (0.1-5%) were produced using the coprecipitation method. Then a variety of S-FAP transparent ceramics with varying Yb content were fabricated using hot-pressing sintering. The crystalline phase structure of hexagonal Sr-5(PO4)(3)F was verified by XRD analysis of the precursor powder and the final ceramics. According to the powder SEM, the average grain size and the long axial-radial ratio of powders are decreasing as the Yb3+ concentration increases. Thermal-etched surface SEM reveals nanostructured S-FAP transparent ceramics with an average grain size of less than 200 nm were synthesized. The highest transmittances of the 3% ceramics at 500 and 1100 nm wavelengths are 51% and 79.78%, respectively. The ceramic cross-sectional SEM demonstrated that porosity is the primary scattering source influencing the enhancement of optical characteristics. The absorption, emission, and fluorescence lifetimes of S-FAP transparent ceramics with varying Yb concentrations were tested and discussed, and the absorption and emission cross sections corresponding to the major peak were reported. Some physical parameters of this set of ceramic samples were shown, including thermal diffusivity, specific heat capacity, and thermal diffusivity data, as well as micro-hardness.