The thermochemistry of uranium and cerium in native britholite

This work deals with the reduction–oxidation processes that occur in natural britholite Ca5(PO4)3(OH,Cl,F) when it is subjected to temperatures between 20 °C and 900 °C. Uranium and cerium, present in britholite as isomorphic impurities, served as chemical “sensing elements”. Several stages of redox processes were identified, alternating back and forth within the temperature range that was examined. Assumptions were made about the types of radiation-induced defects responsible for the thermochemical transformations of uranium and cerium that were observed. Activation energy values for the corresponding redox processes were estimated.