Thermal properties of Sr3Ga2Ge4O14 single crystals grown by the vertical Bridgman method

Sr3Ga2Ge4O14 (SGG) has been grown by the vertical Bridgman method. The dielectric constants ε11T and ε33T at room temperature is 13.61 and 18.18, respectively. The dielectric measurements show that SGG crystals display relative high temperature stability and high frequency stability. Thermal properties including specific heat, thermal diffusivity, thermal conductivity and thermal expansion have been investigated as a function of temperature for the first time. The specific heat of the SGG crystals has been measured to be 0.459 J/(g K) at 298 K. The thermal diffusivity and the thermal conductivity for SGG crystals are about 0.540 mm2/s and 1.243 W/(m K) at 298 K, respectively. The average thermal expansion coefficients along the a- and c-directions of SGG crystals, are calculated from 298 to 973 K as α11 = 6.5 × 10−6 K−1 and α33 = 5.8 × 10−6 K−1, respectively.