Enhancement of conductivity in phase pure and doped ceria for fuel cell applications

Solid oxide fuel cells (SOFCs) have gained much attention because of their many advantages including high efficiency and an environmentally friendly nature. Flexibility in fuel choice for both small power units and large-scale power plants is another plus. The main component determining the performance of fuel cells is the electrolyte material. For the electrolyte application, lower-valency cation-doped CeO2 materials have attracted tremendous research interest in SOFCs operating in the intermediate temperature range (500–700°C). Ce0.75−xBixGd0.25O2 (x = 0.0, 0.05, 0.10) was prepared by a sol-gel method in which bismuth was added as a dopant. The material was sintered at 550°C for 2 h. To analyze the structural properties of the sample, x-ray diffraction (XRD) technique was used, which confirmed the cubic fluorite structure. A precision component analyzer was used for dielectric study of the samples in the frequency range of 20 Hz to 3 MHz at different temperatures (30–400°C). DC resistance was measured using a two-probe method that showed a decreasing trend with increasing temperature. The doped samples demonstrated highly improved structural and electrical properties as compared to those of the undoped sample. The increased conductivity and improved stability of the samples make them a potential candidate for the electrolytes of SOFCs.