Equilibrium of intrinsic and impurity point defects in Ca-doped Sm2Zr2O7

Abstract

In this work, a doping strategy was used to achieve a good conductivity in samarium zirconate which crystallizes in the pyrochlore. The production of nanopowders made it possible to form high-density ceramics with an optimal microstructure.It is shown that intrinsic and impurity defects coexist in Sm 2−x Ca x Zr 2 O 7−δ , impairing ion transport at high doping levels. Despite this, Sm 1.95 Ca 0.05 Zr 2 O 7−δ maintains low activation energy of the parent and has good ionic conductivity (10 −3 S•cm −1 at 600 • C) which is one of the largest among oxide pyrochlores. It has been shown to have a good chemical stability. The material has a thermal expansion coefficient (TEC) of 12 ppm K −1 which is higher than YSZ and provides better compatibility with electrode materials. The above makes it possible to successfully use it as a highly stable oxygen electrolyte or an intermediate thin layer at the electrolyte-electrode interface in electrochemical devices.