Effects of Nb <sup>5+</sup> doping on thermal properties of Gd <sub>2</sub> (Zr <sub> 1− <i>x</i> </sub> Nb <i> <sub>x</sub> </i> ) <sub>2</sub> O <sub> 7+ <i>x</i> </sub> ceramics
Tao Jiang, Min Xie, Xuanli Wang, Xiwen Song
Abstract
Pyrochlore Gd2(Zr1−xNbx)2O7+x (x = 0, 0.05, 0.1, 0.15) ceramic materials were synthesised using a high-temperature solid-state reaction method. The phase structure, thermal expansion coefficient and thermal conductivity of Gd2(Zr1−xNbx)2O7+x were investigated in this work. The results show that with the introduction of Nb2O5, Gd2(Zr1−xNbx)2O7+x ceramic materials present a cubic pyrochlore structure. Meanwhile, Gd2(Zr1−xNbx)2O7+x ceramics have clear grain boundaries. The thermal expansion coefficient of Gd2(Zr1−xNbx)2O7+x ceramic materials reduces from 11.4576 × 10−6 to 10.7919 × 10−6 K−1 (larger than 10 × 10−6 K−1), while its thermal conductivity gradually increases with the doping of Nb5+ ions. Considering their comprehensive properties, Gd2(Zr1−xNbx)2O7+x compounds may be considered as promising thermal barrier coatings materials.