Synthesis of perovskite-type (La1−xCax)FeO3 (0 ≤ x ≤ 0.2) at low temperature

Gel formation was realized by adding citric acid to a solution of La(NO3)3·5H2O, Ca(NO3)2·4H2O, and Fe(NO3)2·9H2O. Perovskite-type (La1−xCax)FeO3 (0 ≤ x ≤ 0.2) was synthesized by firing the gel at 500 °C in air for 1 h. The crystallite size (D1 2 1) decreased with increasing x, while the specific surface area was 6.8-9.4 m2/g and independent of x. The XPS measurement of the (La1−xCax)FeO3 surface indicated that the Ca2+ ion content increased with increasing x, while the Fe ion content was independent of x. Catalytic activity for CO oxidation increased with increasing x.