Large remnant polarization and improved dielectric, magnetic properties of Te-modified 0.7BiFeO₃–0.3BaTiO₃ ceramics

BiFeO₃–BaTiO₃ (BF–BT) ceramics, as a kind of binary ferroelectric material with excellent properties, have a wide range of applications. A novel Te-doped 0.7BiFe_1−xTe_xO₃–0.3BaTiO₃ (x = 0–0.07) ceramics with enhanced ferroelectric properties were designed and synthesized via a solid-phase reaction. Results of X-ray diffraction and Rietveld refinement revealed a phase transition from the rhombohedra and tetragonal phases to a single tetragonal phase with increasing Te content, indicating the formation of a morphotropic phase boundary (MPB) in samples with x = 0–0.03. The fitting results of the X-ray photoelectron spectra showed that the Te introduction reduced the Fe²⁺ concentration and improved the insulating performance. Due to the Te-induced structure distortion of the rhombohedral phase and tetragonal phase, a large remnant polarization of 51 μC/cm² is obtained at x = 0.01, which is superior to those reported in many studies on BF–BT bulk materials. The dielectric properties revealed that Te addition effectively adjusted the relaxation degree of the ceramics, showing an ideal relaxor ferroelectric behavior in samples with x = 0.05 and 0.07. Additionally, Te substitution reduced the Fe–O–Fe bond angle and the grain size, achieving enhanced ferromagnetism and affording the largest remnant magnetization in the case of x = 0.03, which is around six times that of the pure BF–BT ceramic.