Single crystal solid state electrolytes based on yttria, ytterbia and gadolinia doped zirconia

Abstract

The effect of stabilizing oxide cation radius on the phase composition and transport properties of single crystal solid state ZrO2 electrolytes doped with Yb2O3, Y2O3 or Gd2O3 have been studied. The solid solution single crystals have been grown by directional melt crystallization in a cold crucible. The structure of the single crystals has been studied using X-ray diffraction, Raman scattering and transmission electron microscopy. We show that the formation of the cubic solid solution depends on the concentration of stabilizing oxide and the ionic radius of stabilizing cation. The smaller the ionic radius of the stabilizing cation, the lower the stabilizing oxide concentration at which the forming cubic phase is stable. Study of the high-temperature conductivity of the (ZrO2)1-х(R2O3)х solid solution crystals where R–Y, Yb and Gd has shown that an increase in the ionic radius of the stabilizing oxide reduces the conductivity of the crystals. The conductivity vs. concentration dependences of the crystals stabilized with Yb2O3, Y2O3 and Gd2O3 have maxima at stabilizing oxide concentrations of 8, 9 and 10 mol.%, respectively.