Synthesis of perovskite-type (La_(1-x)Ca_x)FeO_3 (0 ≤ x ≤ 0.2) at low temperature

摘要

Gel formation was realized by adding citric acid to a solution of La(NO_3)_3 · 5H_2O, Ca(NO_3)_2 · 4H_2O, and Fe(NO_3)_2 · 9H_2O. Perovskite-type (La_(1-x)Ca_x)FeO_3 (0 ≤ x ≤ 0.2) was synthesized by firing the gel at 500℃ in air for 1 h. The crystallite size (D_(1 2 1)) decreased with increasing x, while the specific surface area was 6.8-9.4 m~2/g and independent of x. The XPS measurement of the (La_(1-x)Ca_x)FeO_3 surface indicated that the Ca~(2+) ion content increased with increasing x, while the Fe ion content was independent of x. Catalytic activity for CO oxidation increased with increasing x.