Evaluation of Rare Earth-Doped Cerium-Based Oxide Powders Synthesized by a New Coprecipitation Method as an Electrolyte in Intermediate-Temperature Solid Oxide Fuel Cells

Abstract

Zr-doped ceria powders, Ce 0.9-x Zr x Gd 0.1 O 1.95 (0 ≤ x ≤ 0.2) have been synthesized by a new coprecipitation method, and their sintering and thermal properties have been examined as electrolytes in intermediate-temperature solid oxide fuel cells. A very small amount of Zr-doping causes a dramatic lowering of sintering characteristics. It was found that Zr doping promoted formation of oxygen vacancy in the fluorite structure under a reducing atmosphere. After thermal expansion measurement in the temperature range from room temperature to 700°C was made in the H 2 atmosphere, it was observed for the samples with Zr content of 0.025 ≤ x ≤ 0.2 that many cracks occurred along the grain boundaries and in the grains. From the results of the scanning electron microscope and energy dispersive X-ray analysis, Zr components in the reduced samples were segregated at the grain boundary.