Coefficients of Thermal Expansion in La 3 Ga 5 SiO 14 and Ca 3 TaGa 3 Si 2 O 14 Crystals.

The ordered Ca 3 TaGa 3 Si 2 O 14 and disordered La 3 Ga 5 SiO 14 crystals of the lantangallium silicate family were grown via the Czochralski method. The independent coefficients of thermal expansion of crystals αc and αa were determined using X-ray powder diffraction based on the analysis of X-ray diffraction spectra measured in the temperature range of 25~1000 °C. It is shown that, in the temperature range of 25~800 °C, the thermal expansion coefficients are linear. At temperatures above 800 °C, there is a nonlinear character of the thermal expansion coefficients, associated with a decrease in the Ga content in the crystal lattice.