Recent thermophysical developments on nuclear materials

Abstract

The current status of chemical thermodynamics of the actinide and lanthanide chalcogenides including high-temperature adiabatic calorimetry of these important compounds (with stress on their electronic, magnetic, order-disorder, disproportionation transitions), as well as the spin-wave magnetic contributions, is reviewed. Schottky anomalies (and the information they yield on crystal-field level splitting), definitive resolution of lattice and magnetic contributions for both first- and second-order phase transitions, and other unusual aspects of phase behavior are considered. Unpublished work on the uranium trioxides, the non-stoichiometric and metastable tetrauranium octaoxides, the uranates, etc. is included. The close parallel between actinide and lanthanide behavior evidenced by our recent unpublished thermal studies on the actinide and lanthanide trichlorides, and hexaborides is emphasized.