Studies on magnetoelectric coupling and magnetic properties of (1 - x)BiFeO_3-xBaTiO_3 solid solutions

摘要

Structure, magnetization and magnetoelectric coupling of (1 - x)BiFeO_3-xBaTiO_3 (BFO-BT) solid solutions have been studied as a function of BT content (x = 0.10, 0.15,0.20,0.25 and 0.30).The phase purity and crystal lattice symmetry were estimated from X-ray diffraction studies, which undergo gradual, well-controlled structural transformations from rhombohedral to cubic structure with morpho-tropic phase boundary (MPB). The micro-structural features, observed by scanning electron microscopy, demonstrate that the ceramic has highly compact and uniform microstructure having average grain size ～(3 ± 1) μm. The room-temperature magnetization studies exhibit hysteretic behavior with remnant magnetization values of m_r ≤ 0.407 emu/gm and low coercivity H_c ≈ (196 - 1,989) Oe indicating that the latent magnetization locked within the toroidal spin structure of BFO has been released and low loss is achieved. An observation on low coercivity, magnetoelectric (ME) coupling coefficient α ≈ 11.6 mV/cm/Oe at 5,000 Oe, effective high magnetic susceptibility χ_(eff) ≈ 118 × 10~(-4) or 1.47 × 10~(-5) emu/gm Oe and pronounced anomaly in the dielectric constant near the magnetic transition temperature suggests quantitative as well as qualitative magnetoelectric coupling in BFO-BT solid solutions.