Thermophysical properties of pyrochlore and fluorite phases in the Ln2Zr2O7-Y2O3 systems (Ln = La, Nd, Sm): 1. Pure pyrochlores and phases in the La2Zr2O7-Y2O3 system

Thermal diffusivity was measured by the laser flash method for pyrochlores La2Zr2O7, Nd2Zr2O7, Sm2Zr2O7 synthesized by co-precipitation method and then sintered by conventional sintering at 1600 °C and by spark plasma sintering/field assisted sintering technique (SPS/FAST). Thermal conductivity was calculated using heat capacity data available in literature and the results of the present study on thermal diffusivity measurements together with densities determined by Archimedes method. It was demonstrated that samples sintered using the SPS have substantially higher thermal diffusivities and conductivities. It was shown that both thermal diffusivity and conductivity decreases with ionic radius decrease based on the results obtained for SPS prepared samples of Ln2Zr2O7 (Ln = La, Nd, Sm). Heat capacity, thermal diffusivity and Archimedes density were measured for phases with pyrochlore and fluorite structure in the La2Zr2O7-Y2O3 system for the first time. It was shown that heat capacity increased while thermal diffusivity and thermal conductivity decreased with increase of Y2O3 content.