Structural transformation and multiferroic properties in Gd-doped Bi7Fe3Ti3O21 ceramics

Abstract

Bismuth layer-structured Bi_7−xGd_xFe₃Ti₃O₂₁ (0.00 ≤ x ≤ 1.50) ceramics were synthesized by Pechini's method, in which gadolinium doping was used with a goal to enhance the magnetic response of the material. With increase in the Gd content of x, an obvious structural transformation, changing gradually from the originally designed six-layer structure to five-layers, was initially shown by X-ray diffraction patterns, and then by Raman scattering spectra and high-resolution transmission electron microscopy images. Substituting Bi sites with Gd³⁺ ions was found to be able to effectively suppress the leakage current, and its resistivity was found to be about two orders of magnitude higher than that of the un-doped sample. Improved magnetic properties and a clear magnetic anomaly were observed in the sample with a composition of x = 1.00, indicating the behaviour of transforming from anti-ferromagnetism with weak ferromagnetism at the room temperature into a complex magnetism at low temperature.