Investigation of the influence of zirconium substitution on the properties of neodymium-doped barium cerates

摘要

Preparation, electrical conductivity and stability are discussed for Nd-doped barium cerate with partial substitution of zirconium for cerium. BaCe_(0.9-x)Zr_xNd_(0.1)O_(2.95) with 0.1 ≤ x≤ 0.9 was prepared by direct reaction of mixtures of barium carbonate and the corresponding metal oxides. Structural properties of BaCe_(0.9-x)Zr_xNd_(0.1)O_(2.95) were investigated by X-ray diffraction and raman scattering. Single phases were obtained over the entire range of x-values, if reaction temperatures above 1500℃ were applied. The total conductivity was measured as a function of temperature and for different conditions of p(H_2O), p(O_2) in N_2. Only a slight decrease in the total conductivity was found up to 60%-zirconium substitution. In addition, the oxygen ion conductivity was determined for 600℃-800℃ using an ion conducting microelectrode made from stabilized zirconia. The oxygen ion conductivity was lower than the total conductivity by about two orders of magnitude. The observed total conductivity is therefore attributed primarily to proton conductivity.