High temperature heat capacity of Nd2Zr2O7 and La2Zr2O7 pyrochlores

The enthalpy increment measurements were performed using drop calorimetry on two lanthanide zirconates Ln2Zr2O7, Ln = La, Nd, with pyrochlore structure. The temperature dependence of heat capacity in the range (298 to 1550) K was derived by simultaneous linear regression of the measured enthalpies combined with the heat capacity data around ambient temperature. The obtained heat capacity Cp∘(T) is compared to the limit of constant volume lattice Cv calculated from the analysis of low temperature specific heat data using a combined Debye-Einstein harmonic approximation model.