Structure and properties of the crystals of solid electrolytes (ZrO2)1 – x – y(Sc2O3)x(Y2O3)y (x = 0.035–0.11, y = 0–0.02) prepared by selective melt crystallization

Abstract

Single crystals of solid electrolytes of the (ZrO₂)_1–x–y(Sc₂O₃)_x(Y₂O₃)_y (x = 0.035–0.11, y = 0‒0.02) system were grown by selective melt crystallization. Stabilization of ZrO₂ only with Sc₂O₃ in the concentration range 9–11 mol % Sc₂O₃ did not afford crystals with a cubic structure, and only the introduction of additional Y₂O₃ stabilizers afforded uniform transparent single-phase cubic crystals. All the crystals under study had high microhardness, but low crack resistance. The ion conductivity of crystals with 6 and 9 mol % Sc₂O₃ (6ScZr and 9ScZr, respectively) is comparable to that of 8 mol % Y₂O₃-stabilized ZrO₂ (8YSZ), which is the most suitable electrolyte in the ZrO₂–Y₂O₃ binary system. The specific conductivity of crystals containing 8–10 mol % Sc₂O₃ and 1–2 mol % Y₂O₃ exceeds that of other materials including 8YSZ. The maximum conductivity in the given range of compositions is inherent in the cubic phase with 10 mol % Sc₂O₃ and 1 mol % Y₂O₃ (10Sc1YZr).