Structural phase evolution in Bi7/8Ln1/8FeO3 (Ln = La-Dy) series

Regularities of the structural phase evolution associated with changing ionic radius of the A-site dopants in Bi(7/8)Ln(1/8)FeO(3) (Ln = La-Dy) series were investigated by X-ray diffraction technique at room temperature. A strong tendency to the structural phase separation was found. Initial polar rhombohedral R3c structure characteristic of pure bismuth ferrite is retained only for La-doped compound. For most other samples, intrinsic polar-antipolar R3c + Pnam (Ln = Pr, Nd, Sm), antipolar-nonpolar Pnam + Pnma (Ln = Gd), or polar-nonpolar R3c + Prima (Ln = Tb, Dy) phase coexistence was revealed. Investigation of temperature evolution of crystal structure of La-doped compound performed with a neutron powder diffraction technique found that its high-temperature paraelectric phase had the orthorhombic Pnma symmetry. (C) 2011 Elsevier B.V. All rights reserved.