Investigation on thermo-physical and mechanical properties of Dy3(Ta1-xNbx)O7 ceramics with order-disorder transition

Rare earth tantalate and niobate have attracted much attention due to their excellent thermo-physical properties and are considered as potential thermal barrier coating (TBC) materials. The bulk specimens of Dy-3(Ta1-xNbx)O-7 (x = 0, 1/6, 2/6, 3/6, 4/6, 5/6, and 6/6) ceramics are synthesized by high-temperature solid-state reaction in this work, and the results of the phase structure identification show that the Dy-3(Ta1-xNbx)O-7 ceramics vary from ordered weberite structure to disordered defect fluorite structure with the increase of component parameters x. Interestingly, the thermo-physical properties and mechanical properties of Dy-3(Ta1-xNbx)O-7 ceramics are closely related to the order-disorder transformation process. Furthermore, the Dy-3(Ta1-xNbx)O-7 ceramics possess low thermal conductivity and high thermal expansion coefficients, which suggests that Dy-3(Ta1-xNbx)O-7 ceramics can be candidates as TBC materials.