Undoped and (0, 0.5, 5 mol%) Lu2O3 single crystals were grown by the micro-pulling-down method. Crystals were transparent with yellowish color with 4.2 mm in diameter and 6-9 mm in length. Yb-doped Lu2O3 single crystals have a good compositional homogeneity along the growth axis. Both, thermal diffusivity and heat capacity decrease when the Yb concentration increase. As a result, the calculated thermal conductivity for 5 mol% Yb3+-doped Lu2O3 decreases from 14.32 to 12.42 Wm(-1)K(-1). We have also investigated the absorption, fluorescence spectra and measured fluorescence lifetimes as a function of the Yb content.
Keywords: Yb3+ activator; Thermal conductivity; Micro-pulling-down method; Crystal growth from the melt; Rere-earth sesquioxides