Heat capacities and thermal conductivities of AmO_2 and AmO _(1.5)

摘要

The thermal diffusivity of AmO_2 was measured from 473 to 773 K and that of AmO_(1.5) between 473 and 1373 K using a laser flash method. The enthalpy increment of AmO_2 was measured from 335 to 1081 K and that of AmO_(1.5) between 335 and 1086 K using drop calorimetry. The heat capacities of AmO_2 and AmO_(1.5) were derived from the enthalpy increment measurements. The thermal conductivity was determined from the measured thermal diffusivity, heat capacity and bulk density. The heat capacities of AmO_2 was found larger than that of AmO_(1.5). The thermal conductivities of AmO_2 and AmO_(1.5) were found to decrease with increasing temperature in the investigated temperature range. The thermal conductivity of AmO_(1.5) with A-type hexagonal structure was smaller than that of AmO_2 with C-type fluorite structure but larger than that of sub-stoichiometric AmO_(1.73).