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

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−xCa_xZr₂O_7−δ, impairing ion transport at high doping levels. Despite this, Sm_1.95Ca_0.05Zr₂O_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.

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