Heat Capacity and Thermodynamic Functions of La2Sn2O7.

Lanthanum stannate with the pyrochlore structure and a crystallite size in the range 100–400 nm has been prepared by solid-state synthesis. We have optimized synthesis parameters for obtaining a ceramic material. The heat capacity of La2Sn2O7 has been determined for the first time using adiabatic and differential scanning calorimetry techniques in the range 19–1300 K, and the stannate has been shown to undergo no structural transitions in this range. We have calculated temperature-dependent standard thermodynamic functions of La2Sn2O7 and evaluated the standard Gibbs energy of formation of this compound from its constituent elements at 298.15 K. [ABSTRACT FROM AUTHOR]