Impact of the Bi substitution on the structural and charge density distribution of Ca_0.7La_0.3-xBi_xMnO₃ (x = 0, 0.1)

The Bi substitution effect on the structure of La_0.3-xBi_xCa_0.7MnO₃ (x = 0, 0.1) is observed through the X-ray powder diffraction pattern. The effect of Bi substitution does not significantly change the unit cell size itself. This is due to the size of the Bi³⁺ ionic radius which is relatively almost the same as the ionic radius of La³⁺. Through Rietveld refinement, it is confirmed that the samples have the orthorhombic structure with Pnma space group. Changes of the charge density distribution between the atoms of bonds with the Bi substitution are investigated using maximum entropy method (MEM). MEM which is based on the refined structure factors extracted from the Rietveld method provide the information of charge ordering with respect to stronger regularity pattern of charge density distribution.