Heat-capacity measurement on ( Zr1− ySny) Ox from 325 to 905 K

Abstract

Heat capacities of ( Zr 1− y Sn y ) O 0.17 and ( Zr 1− y Sn y ) O 0.28 ( y = 0−0.07) having α''-ZrO ~ 1 6 and α''- ZrO x type crystal structures, respectively, were measured from 325 to 905 K by using an adiabatic scanning calorimeter. Two kinds of heat capacity anomalies were observed for all samples. The anomaly at lower temperatures is attributed to a nonequilibrium phenomenon. Another anomaly at higher temperatures is assigned to an order-disorder rearrangement of oxygen atoms. The transition temperature, transition enthalpy and entropy changes due to the order-disorder transition decreased with increasing tin content, indicating that arrangement of oxygen atoms in the lower temperature phase may be partially disordered by substituting tin for zirconium. The entropy change due to the order-disorder transition for ( Zr 1− y Sn y ) O 0.17 and ( Zr 1− y Sn y ) O 0.28 solid solutions is compared with the theoretical value. The solubility limits of ( Zr 1− y Sn y ) O 0.17 and ( Zr 1− y Sn y ) O 0.28 were determined from the variation of lattice constants, transition temperature, transition enthalpy and entropy changes against tin content.