The high temperature heat capacity of NpO2

The enthalpy increments of pure NpO2 have been measured using drop calorimetry in the temperature range from (376 to 1770) K. The heat capacity was derived using the obtained data constrained to 66.20 J · K−1 · mol−1 at 298.15 K taken from published low temperature measurements. The heat capacity of NpO2 determined in this study is given by the following equation:Cp,m0/(J·K-1·mol-1)=71.608+0.015845·(T/K)-900648·(T/K)-2.

► A drop calorimeter has been installed in an alpha-tight glove box and first tested with active actinide containing samples. ► The heat capacity of NpO2 has been measured. ► The temperature range of the measurement was extended by more than 600 K compared to previous experimental studies.