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 НO2O3 and Y2O3 raise the stability of the electrical characteristics of the solid electrolytes.