Low temperature heat capacity study of Ba2TiSi2O8 and Sr2TiSi2O8

Abstract

The heat capacities of powdered Ba2TiSi2O8 and Sr2TiSi2O8 have been measured over the temperature range from (2 to 300)K using a Quantum Design Physical Property Measurement System (PPMS). These two compounds have similar heat capacity values over the experimental temperature range because of their analogous structures. However, the heat capacities do display a crossover at T=112.6K, below which the heat capacity of Ba2TiSi2O8 becomes larger than that of Sr2TiSi2O8. The experimental data have been fitted to a series of theoretical functions from which the thermodynamic functions have been calculated. The standard molar entropies at T=298.15K have been determined to be (254.67±2.55) and (252.61±2.78)J·K−1·mol−1 for Ba2TiSi2O8 and Sr2TiSi2O8, respectively.