Structure and Thermal Properties of the Nonlinear Optical Crystal BaTeMo2O9

Nonlinear optical (NLO) crystals BaTeMo2O9 (BTM) with large size and good quality have been grown by the flux method. The connections of the Mo-O octahedral group are presented, and the relationship between the structure and the thermal properties has also been discussed. The specific heat, anisotropic thermal expansion and thermal conductivity have been carefully measured. The principal thermal expansion and thermal conductivity coefficients have been determined at different temperatures. Thermal expansion of BTM exhibits weak anisotropy though it belongs to low symmetry system. Interestingly, the thermal conductivity of BTM ascends as the temperature is increased.