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 0.7BiFe1_xTexO3-0.3BaTiO3 (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 & mu;C/cm2 is ob-tained 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.