Molar heat capacity and thermodynamic functions for CaTiO3

Calcium titanate, CaTiO3, has appeared as a significant impurity in the synthesis of several ceramic host materials for the disposal of excess weapons grade plutonium and uranium. Previously reported heat capacities on CaTiO3 extend only to T = 50 K. Also, the agreement of the low-temperature heat capacity results with those used to calculate the currently accepted values of the thermodynamic functions at elevated temperatures is poor near their intersection. To resolve these problems, the heat capacity of CaTiO3 was measured from T approximate to 14 K to T approximate to 400 K using an adiabatic calorimeter. A nine-term fitting equation was found to represent adequately the low-temperature experimental heat capacities from this study and high-temperature results from the literature. It is used to extrapolate the thermodynamic data for CaTiO3 to T = 1900 K. New values for Delta(f)G(m)(o) and Delta(f)H(m)(o) as a function of temperature are also tabulated. (C) 1999 Academic Press.