Influences of sintering temperature on the electrical conductivity of GDC-50vol%MgO composite ceramics: the role of the GDC/MgO heterogeneous interface

Magnesium oxide can be added into Gd-doped CeO 2 (GDC) as a suitable sintering additive, and the continuous GDC/MgO heterogeneous interface will contribute to the promotion of the oxygen ion transmission. GDC-50vol%MgO composite ceramics were sintered at different temperatures (1350~1500 °C). The phase composition, micromorphology, and electrical conductivity of GDC-50vol%MgO were analyzed by XRD, SEM, TEM, and electrochemical impedance, respectively. There are only GDC and MgO phases in the ceramics sintered at 1350 °C, 1400 °C, 1450 °C, and 1500 °C. As the sintering temperature rises from 1350 to 1500 °C, the average grain size of GDC and MgO increases from 239/274 to 680/651 nm, respectively. The GDC/MgO heterogeneous interface is clear, and many edge dislocations form there. The grain boundary and total conductivities decrease significantly with the rising sintering temperature, and the GDC/MgO heterogeneous interface possesses a higher electrical conductivity than the GDC/GDC homogeneous interface.