Synthesis and sintering of Sr- and Ca-doped lanthanum chromite ultrafine powder for SOFC interconnect

Abstract

In this study, ultrafine powder of mixed Sr- and Ca-doped lanthanum chromite with two different compositions (La0.7Sr0.1Ca0.2CrO3 and La0.7Sr0.2Ca0.1CrO3) and average particle size of 150 nm was successfully synthesized by the simple process of glycine nitrate. The samples were characterized by thermal analysis, X-ray diffraction, and nitrogen adsorption-desorption, scanning and transmission electron microscopy. The synthesized ultrafine powders with perovskite type crystal structure and some SrCrO4 or CaCrO4 phases were cold isostatically pressed at 200 MPa, and then sintered in air at 1400 degrees C for several time periods (1-10 h). Relative density measurements were conducted by Archimedes method. The maximum relative density for both samples obtained after sintering in air at 1400 degrees C for 10 h was 98.2 % of the theoretical density and the average grain size of the sintered pellets was about 2 mu m. In addition, the effects of composition on phase transition behavior and electrical properties were studied.