Growth and thermal properties of SrWO4 single crystal

Abstract

A strontium tungstate (SrWO4) single crystal with dimensions of Φ 25×40mm2 has been grown by the Czochralski method using an iridium crucible. X-ray powder diffraction results show that as grown the SrWO4 crystal belongs to the tetragonal system in the scheelite structure. The effective segregation coefficients of elemental W and Sr in the crystal growth are measured by x-ray fluorescence, and the respective values are close to 1. The thermal properties of the SrWO4 crystal were systemically studied by measuring the thermal expansion, specific heat, and thermal diffusion coefficient. These results show that the crystal possesses a large anisotropic thermal expansion with thermal-expansion coefficients αa=8.61×10−6∕K, αb=8.74×10−6∕K, αc=18.78×10−6∕K over the temperature range of 303.15–773.15K. The measured value of the specific heat is 0.30–0.34Jg−1K−1 when the temperature is increased from 323.15to1073.15K. The thermal diffusion coefficient was measured over the temperature range of 303.15–543.15K. The thermal conductivities of the SrWO4 crystal along the [100] and [001] directions are calculated to be 3.1326Wm−1K−1 and 2.9477Wm−1K−1, respectively, at 303.15K. Then the thermal properties of some other Raman crystals were compared with these data, and the thermal focal lengths for these crystals were also estimated.