Powder X-ray diffraction and Rietveld analysis of La _{1− <i>x</i>} Ba _<i>x</i> CoO ₃ (0&lt; <i>x</i> ≤0.5)

Abstract

Detailed structural properties of La 1− x Ba x CoO 3 (LBCO) have been investigated by means of X-ray powder diffraction and Rietveld analysis. A structural phase transformation from R 3 c to P m 3 m at x =0.30–0.35 has been detected based on a comparison between the refinements of R 3 c and P m 3 m . The Co–O bond length of the CoO 6 octahedron expanded rapidly with increasing Ba content when x &lt;0.1, and then it leveled off and kept constant at 0.1⩽ x ⩾0.35, where the Co–O–Co bond angle reaches 180°. The Co–O bond length expansion resumed with increasing Ba content beyond x =0.35.