Growth and thermal properties of tetragonal double tungstate KLa(WO4)2 crystal

An uncracked single crystal of double tungstate KLa(WO4)2 with the tetragonal scheelite structure has been successfully grown by the modified Czochralski method. For the first time, the thermal properties of this crystal, including the specific heat, thermal expansion, and thermal conductivity, were systematically investigated. The specific heat of the KLa(WO4)2 crystal changes slightly from 0.333 J g−1 K−1 to 0.394 J g−1 K−1 over the temperature range from 25 °C to 500 °C. The average linear expansion coefficients are α1 = 14.3 × 10−6 K−1 and α3 = 29.3 × 10−6 K−1. The anisotropy of the thermal expansion is explained from the point of view of crystal structure. The calculated thermal conductivities are 1.056 W m−1 K−1 and 1.174 W m−1 K−1 along the a- and c-axes, respectively. Compared with other double tungstate crystals, the KLa(WO4)2 crystal has a relatively low anisotropy of thermal expansion, as well as good thermal characteristics, and is suitable as a promising disordered laser host.