Investigation of the electrical conductivity of sintered monoclinic zirconia (ZrO 2 )

Abstract High-density monoclinic ZrO 2 was manufactured through sintering at ~1200 °C by using nanosized powders. Then, the electrical conductivity was measured at a range of high temperatures (700–900 °C) by electrical impedance spectroscopy (EIS). For the as-sintered monoclinic ZrO 2 , the measured electrical conductivity was 3.2×10 −5 s/cm (for 80% TD) and 4.4×10 −5 s/cm (for 89% TD) at 900 °C. After aging at 900 °C for 100 h, the electrical conductivity of the monoclinic ZrO 2 of 80%-TD decreased by more than 50%. However, after reheating at 1200 °C for 1 h, approximately 80% of the conductivity was recovered compared to the value of the as-sintered monoclinic ZrO 2 . The pure monoclinic crystal structure was retained despite the aging and reheating treatment. Based on microstructural observations of the aged and reheated monoclinic ZrO 2 , the changes in electrical conductivity after aging and reheating were explained by the formation and recovery of micro-cracks, respectively.