Preparation and Electrical Properties of Interconnect Material Made by Substituting Mixed Rare Earth Oxides (Sm_2O_3, Gd_2O_3, Eu_2O_3 and CeO_2) for La_2O_3 in La_(1-x)Ca_xCrO_3(0.1≤x ≤ 0.4)

摘要

La_(1-x)Ca_xCrO_3(0.1≤ x ≤ 0.4) is usually used as interconnect material for solid oxide fuel cells (SOFCs). In this paper, composite material, the two-phase mixtures of face-centered cubic fluorite structure Ca_yCe_(1-y)O_(2-y)(0 ≤y≤ 0.2) and orthorhombic perovskite structure [Sm(Eu,Gd)]_(1-z)Ca_2CrO_3(0 < z < 0.3), was prepared by an auto-ignition process in which mixed rare earth oxides (Sm_2O_3, Gd_2O_3, EU_2O_3 and CeO_2) are substituted for La_2O_3 in La_(1-x)Ca_xCrO_3. The direct current (DC) four-probe technique measurement indicated that the electrical conductivities of specimens increased along with the increase of Ca~(2+) content (x), especially when x=0.3 and 0.4. The material (x=0.4, about 94% relative density) showed excellent electrical conductivities of 48 Scm~(-1) in air and 13 Scm~(-1) in H_2 (purity 99.999%) at 700 °C respectively, which is about 3 times as high as:hat of La_(0.7)Ca_(0.3)CrO_3.