Order-disorder transition and thermal conductivity of (Yb_xNd_(1-x))_2Zr_2O_7 solid solutions

摘要

X-ray diffraction, transmission electron microscopy and a laser-flash method were used to investigate the order-disorder transition and thermal conductivity of (Yb_xNd_(1-x))_2Zr_2O_7 (0 ≤ x ≤1.00) solid solutions. The structures were found to be pyrochlore-type for 0 ≤ x ≤ 0.25, defect fluorite for 0.45 ≤ x ≤1.00 and a mixture of these at 0.30 < x < 0.40. The thermal conductivities of (Yb_xNd_(1-x))_2Zr_2O_7 first gradually decrease with increasing temperature, and then increase slightly above 800℃ due to the increased radiation contribution. YbNdZr_2O_7 has the lowest thermal conductivity due to the reduced cation mean free path at the compositional combination of equal molar Yb~(3+) and Nd~(3+) cations.