In situ high-temperature X-ray powder diffraction study of the synthetic Ca2Sb2O7 weberite-type compound

The crystal structure of synthetic Ca2Sb2O7 has been investigated by in situ X-ray powder diffraction methods within the temperature range 298-1273 K. Ca2Sb2O7 is orthorhombic, space group Imma, over the entire temperature range and shows only general thermal expansion. The unit-cell parameters show a monotonous increase as a function of temperature. Only slight changes occur in the individual bond distances without evidence of abrupt structural changes. The mean coefficients of thermal expansion along the various axes are: alpha(a) = 9.49 x 10(-6)K(-1), alpha(b) = 10.11 x 10(-6) K-1, alpha(c) = 7.56 x 10(-6) K-1 and the bulk thermal expansion coefficient alpha(v) = 27.20 x 10(-6) K-1.