Stability of the structural and electrical characteristics of solid electrolytes in the system ZrO2 – Sc2O3 – rare-earth oxide

The stability of the structural and electric characteristics of solid electrolytes in the system ZrO₂ – Sc₂O₂ – rare-earth oxide was investigated by the method of cyclic resource tests with a delay at 900°C. the specimens were prepeaied by means of mechanical mixing, milling and 3-stage annealing at the following temperatures: 1300 (an), 1920 (vacuum), 1300°C (air).
X-ray analysis, Raman spectroscopy and the temperature dependence of conductivity showed, that aging is caused by the formation of a tetragonal phase with a small content of the stabilizing oxide. This phase is metastable and evidently disintegrates in the process of tests with the evolution of a monoclinic phase.
The aging degree in the cut 0.92 ZrO₂+ 0.06 Sc₂O₃ + 0.02 rare-earth oxide rises in the Yb₂O₃, Но₂O₃, Y₂O₂, Sm₂O₃ series.
The stability of the solid electrolyte characteristics rises with increasing the content of Sc₂O₂. With 1-2 mot % of rare earth oxides added to the composition containing 10-11 mol % of Sc203, the high-temperature cubic structure of the solid solutions remains after their synthesis at lower temperatures, as well including the room temperature. As a result, this electrical conductivity rises in this region. This effect remains after tests in this case. Additions of Н_O2O₃ and Y₂O₃ raise the stability of the electrical characteristics of the solid electrolytes.