Synthesis and electrical conductivity of perovskite Gd 1− x Ca x CrO 3 (0⩽ x⩽0.3) by auto-ignition process

• Published in: Solid state ionics Vol. 176; no. 11; pp. 1057 - 1061
• Main Authors: Zhong, Hong-Hai, Zhou, Xiao-Liang, Liu, Xing-Qin, Meng, Guang-Yao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2005
• Subjects: Auto-ignition process; Electrical conductivity; Gd 1− xCa xCrO 3; Interconnect; SOFC; Interconnect; Gd 1− x Ca x CrO 3; Electrical conductivity; 82.45.Aa; 81.20.-n; Auto-ignition process; SOFC
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/j.ssi.2004.12.008

In order to develop interconnect ceramics for intermediate temperature solid oxide fuel cells (IT-SOFCs), perovskite compounds, Gd 1− x Ca x CrO 3 ( x=0∼0.3), were prepared by an auto-ignition process and characterized. XRD analysis indicated that a single perovskite phase was obtained as Ca 2+ content ( x value) was lower than 0.3, while a second phase appeared at x=0.4. The lattice parameters of the unit cell decrease with increasing the substitution Ca 2+ for Gd 3+. The particle sizes of Gd 0.7Ca 0.3CrO 3 powders are in the range of 20∼50 nm observed by TEM. The powders exhibited better sintering ability and could reach 94.8% relative density at 1400 °C for 4 h in air. The DC four probe technique measurement indicated that the electrical conductivities of the specimens increased with increasing Ca 2+ content as x⩽0.3 but remarkably dropped when x=0.4, which might be attributed to the formation of the second phase with lower conductivity in the materials. Gd 0.7Ca 0.3CrO 3 with a density of 94% showed an electrical conductivity of 24 Scm -1 in air and 7.5 Scm -1 in H 2 (99.999%) at 700 °C respectively, which is about 50% more than that of the commonly used lanthanum chromite (La 0.7Ca 0.3CrO 3). It will be suitable to be interconnect material for IT-SOFCs.