Abstract:
We study ionic conductivity of heavily doped ceria, doping level close to 50mol% with multiple lanthanides in the temperature range of 200 degrees C-500 degrees C. The doped ceria is found to be single fluorite phase, where unit cell is dilated to 0.5527nm, compared with pure ceria (0.5422nm). Electrical characterization by impedance spectroscopy reveals that sample sintered at lower temperature (1400 degrees C) has consistently higher bulk conductivity compared to sample sintered at higher (1600 degrees C) temperature, throughout the temperature range studied. Activation energy for oxygen vacancy diffusion is close to 1eV, indicating lesser association of defects with the dopants compared with other heavily doped ceria reported in literature (activation energy similar to 1.4eV). The best ionic conductivity is found to be 1.58x10-3S/cm at 500 degrees C, which is much higher compared with heavily doped ceria reported in literature.