Determination of thermal, elastic, optical and lattice parameters of GdCOB single crystals doped with Nd3+ and Yb3+ ions

The aim of this work is the determination of thermal, elastic, optical and lattice parameters of gadolinium calcium oxoborate GdCa4O(BO3)(3) (GdCOB) single crystals. The thermal diffusivity was measured by the thermal wave method using a signal detection based on the mirage effect. This experiment was completed with ultrasonic velocity measurements performed by the pulse echo method. The absorption coefficient was acquired from the classical transmission and reflection spectroscopy, while the lattice parameters were measured using the Bond's method. Three GdCOB single crystals were investigated, a pure single crystal, the one doped with 4 at.% of Nd and single crystal doped with 7 at.% of Yb. The samples were grown by the Czochralski technique. Experimental results revealed a clear anisotropy of either thermal or elastic properties of the crystals conforming their monoclinic structure. Doping led to decrease in the thermal diffusivity, while the ultrasound velocity remained practically unchanged. Both Nd and Yb dopants caused also the increase of lattice parameters. (C) 2009 Elsevier B.V. All rights reserved.