The oxygen potentials of AmO2−x were measured in the x range of 0.01–0.5 and the temperature range of 1000–1333 K by the electromotive force method. The oxygen potentials at 1333 K were −19.83 kJ/mol for x=0.019 and −319.1 kJ/mol for x=0.485, which were higher than those of CeO2−x by approximately 200 kJ/mol for the corresponding x values. From the dependence of the oxygen potentials on x and temperature, a tentative phase diagram of Am–O system was proposed, which suggested the presence of the intermediate phases of Am7O12 and Am9O16 in the Am–O system.

No abstract

No abstract

The lattice stability and structure of delta -UZr2 were studied by thermal analysis and high-resolution neutron diffraction techniques. The delta structure was confirmed to be the modified C32 (AlB2-type) structure as in the omega phase of Zr. The temperature dependence of the lattice parameters in the delta phase was determined between room temperature and 880 K. The heat effects at the phase transition from delta to BCC solid solutions were determined to be 5.6-4.4 kJ g-atom-1 for XZr=0.67-0.81. From the composition dependence, the transition enthalpy from omega to beta (BCC) phase in pure Zr was estimated to be 2.8 kJ g-atom-1.

No abstract