Synthesis, crystal structure, relative content of the Mn4+ ion, tolerance factor and catalytic property of La1−xCaxMnO3 (x = 0.0-1.0)

The series compounds La1−xCaxMnO3 (x = 0.0-1.0) are synthesized by the wet chemical method. When x < 0.5, the crystal structure of La1−xCaxMnO3 belongs to cubic system, when x ≥ 0.5, that of La1−xCaxMnO3 belongs to orthorhornbic system. The relative contents of the Mn4+ ion in the series compounds are determined by the chemical analysis methods. The relative content of the Mn4+ ion in La1−xCaxMnO3 increases gradually with increasing the calcium ion content. When x ≥ 0.5, there is neither the oxygen excess nor the lanthanum deficiency in the compound. The tolerance factor of La1−xCaxMnO3 is calculated and no anomaly in the variation of tolerance factor of La1−xCaxMnO3 with x is found. The catalysis activity of La1−xCaxMnO3 for NOy reduction by C3H6 varies with x and there is a minimum in the variation of the largest conversion efficiency for NOy reduction with the composition of La1−xCaxMnO3.