Thermal conductivity of BaWO 4 single crystal

Abstract

Barium tungstate (BaWO 4) single crystal has been grown using Czochralski technique. It belongs to the scheelite structure, forming the space group I4 1/ a at room temperature and the primitive cell contains two formular units. The thermal expansion, specific heat and thermal diffusivity were measured, and then the thermal conductivity was calculated. These results show that BaWO 4 possesses large anisotropic thermal expansion and its thermal expansion coefficients are α a = 1.10 × 10 −5/K, α b = 1.08 × 10 −5/K, and α c = 3.51 × 10 −5/K in the temperature range from 303 to 1423 K. However, its thermal conductivity shows small anisotropic in the temperature range from 297 to 563 K and even displays isotropic at about 428 K. The calculated thermal conductivities are 2.59 and 2.73 W m −1 K −1 at room temperature, along [1 0 0] and [0 0 1] directions, respectively.