Abstract
High temperature heat capacity of fluorite compounds has been reviewed. The lambda-type peak originating from the order-disorder transition of an anion sublattice has been found in many fluorite compounds at high temperatures. By doping, two different changes of the transition temperature and/or the peak shape of the heat capacity were observed in the phase transition of fluorite halides. The onset temperature of UO2, at which heat capacity started to increase rapidly, was observed to increase with dopant content.
