Mechanical and thermal properties of simultaneously substituted pyrochlore compounds (Ca2Nb2O7)x(Gd2Zr2O7)1-x

A series of simultaneously substituted pyrochlore compounds, (Ca2Nb2O7)x(Gd2Zr2O7)1-x (x= 0, 0.05, 0.25, 0.50, 0.75, 1), were synthesized and investigated. Order-disorder phase transformation and Ca2Nb2O7 phase precipitation were observed with the increase of x, which lead to dramatic changes in mechanical properties, such as elastic modulus, Vickers hardness and fracture toughness. Meanwhile, the thermal conductivity abnormally increases at high temperature, especially for compounds of x > 0.25. Effect of phonon and photon transmission on the thermal conductivity are separately investigated to understand this anomaly. Experimental results indicate that simultaneously substituted pyrochlore compounds have great potential for advanced TBC application in the future. (C) 2014 Elsevier Ltd. All rights reserved.