In situ analysis on the electrical conductivity degradation of NiO doped yttria stabilized zirconia electrolyte by micro-Raman spectroscopy

► Progression of phase transformation of NiO doped YSZ from cubic phase to tetragonal phase is evidently observed by in situ micro-Raman spectroscopy analysis. ► Conductivity degradation related to phase transformation progress is also evidently observed. ► Phase transformation ratio gradually decreased with increasing depth from the reduced surface towards the electrolyte.