SYNTHESIS AND PROPERTIES OF MIXED LANTHANIDE CHROMITE PEROVSKITES

Calcium-substituted lanthanum chromites were synthesized using a mixed lanthanide precursor composed primarily of La, Nd, Cc, and Pr The the rmal and electrical properties of these materials were measured and co mpared to similar chromites synthesized with lanthanum nitrate. The pr esence of Nd and Pr in the chromite resulted in a lowering of the ther mal expansion coefficient and an increase in the temperature necessary to attain full density. Arrhenius plots of electrical conductivity we re nonlinear with an inflection at temperatures between 625 and 750 de grees C, indicating an increase in the carrier concentration with temp erature. The increase in carrier concentration was consistent;with the reduction of Ce4+ to Ce3+, resulting in a corresponding increase in C r4+ in order to preserve electrical neutrality. The presence of both t ri- and tetravalent Cc was substantiated using dilatometry measurement s and X-ray photoelectron spectroscopy. The mixed lanthanide precursor is a possible low cost alternative for the synthesis of rare earth ch romites for applications such as interconnects in solid oxide fuel cel ls.