Impact of non-magnetic BaTiO3 substitution on structure, magnetic, thermal and ferroelectric properties of BiFeO3 ceramics at morphotropic phase boundary

Abstract

Narrow compositions of (1-x) BiFeO3 - x BaTiO3 (x = 0.23, 0.25, 0.27 and 0.30) ceramics close to morphotropic phase boundary (MPB) are investigated to understand the interplay among structural phase percentage, bond length, bond angle, net remnant magnetization Néel temperature and remnant polarisation. Phase pure samples of MPB compositions synthesized by a solid-state reaction method. Rietveld refinement yields the phase percentage of MPB compositions for R3c (83.1%, 79%) and Pm3‾m (16.9%, 21%) phases of x = 0.27 and 0.30 respectively. SAED patterns confirmed the structural coexistence of rhombohedral and cubic phases along with defect-free in x = 0.27 and 0.30. The net remnant magnetization of the ferromagnetic phase found to have an inverse relation with the Néel temperature of the antiferromagnetic phase. Breaking of the cycloidal arrangement of dipole moment by Ti-ion substitution promotes the ferromagnetic phase. Saturated ferroelectric loops with a field asymmetry are due to strong Bi–O hybridization inferred by the decreased Bi–O bond length. Magnetic and ferroelectric properties are enhanced in the phase pure MPB compositions (x = 0.27 and 0.30).