Thermal diffusivity and thermal conductivity of thoria-lanthana solid solutions up to 10Â mol.% LaO1.5

A series of thorium oxide-lanthanum oxide solid solutions has been prepared by solid-state reaction. The phase behavior of thoria doped lanthanum oxide has been ascertained by X-ray diffraction technique. A complete solid solubility of LaO1.5 up to 30 mol.% has been observed. Thermal diffusivity of a range of thoria-lanthana solid solutions has been measured in the compositional range from pure thoria to 10 mol.% LaO1.5 by the laser flash method covering a temperature range from 373 to 1773 K. Thermal conductivity values have been calculated from measured diffusivity, density and specific heats of these solid solutions. An attempt has also been made to delineate a suitable mechanism for heat conduction in these solid solutions with the help of the standard phonon conduction equation for dielectric materials.