High-temperature electrical properties of polycrystalline MgO-doped ZrO2

The cubic solid solution with dispersed tetragonal precipitates formed in all the investigated Zr 1-x Mg x O 2-x (0.06≤x≤0.2) samples. Upon heating, the Arrhenius curves are broken into three parts, the degradation of cubic solid solution gives rise to a decline in ionic conductivity for MgO partially stabilized ZrO 2 (Mg-PSZ) samples at 1000–1200 °C, whereas a sharp rise at 1400°C suggests the phase transition from a tetragonal to a cubic phase. On cooling, the phase conversion is reflected by a bend in the Arrhenius curve at 1400°C or lower temperatures due to the slow decomposition of the cubic phase. The high activation energies in a low-temperature region are mainly due to the formation of defect complexes, and the partial dissociation of which leads to the low activation energies in a high-temperature region. Additionally, no apparent breaks in the Arrhenius curves for 8mol%Y 2 O 3 -ZrO 2 (8YSZ) are observed at 1000–1600 °C and the ionic conductivities increase monotonically with increasing temperature.