Effect of Nb5+ and Cu2+ codoping on thermal properties of Gd2Zr2O7 ceramic

In this work, Nb5+ and Cu2+ were selected to partially substitute Zr4+ in Gd2Zr2O7 for studying the phase structure, microscopic morphology and thermal properties. Gd2(Zr1-3x/2NbxCux/2)2O7 (x = 0, 0.05, 0.1, 0.15, 0.2, 0.25) ceramic materials were synthesized by high-temperature solid-state reaction method. The results show that the Gd2(Zr1-3x/2NbxCux/2)2O7 ceramics present cubic pyrochlore structure with clear grain boundaries and dense cell structure. And the thermal expansion coefficient of Gd2(Zr1-3x/2NbxCux/2)2O7 ceramics gradually decreases because of the incorporation of Nb5+ and Cu2+ into Zr-site in Gd2Zr2O7. Meanwhile, its thermal conductivity decreases firstly and then increases with the doping of Nb5+ and Cu2+, which reaches the lowest value for the composition of Gd2(Zr0.85Nb0.1Cu0.05)2O7.