Enhanced dielectric, ferroelectric and magnetodielectric properties in three phase 0.45Bi_0.9La_0.1FeO₃–0.55Co_0.5Ni_0.5Fe₂O₄–BaTiO₃ composite

The piezomagnetic–piezoelectric composites of (1 − x) (0.45Bi_0.9La_0.1FeO₃–0.55Co_0.5Ni_0.5Fe₂O₄)–(x) BaTiO₃, with the compositions x = 0, 0.10, 0.15, 0.20 and 1.0, equivalently denoted as (0.45BLFO–0.55CNFO)/BT, were prepared by solid state reaction method. The presence of constituent phases, spinel phase of Co_0.5Ni_0.5Fe₂O₄, orthorhombic phase of Bi_0.9La_0.1FeO₃ and perovskite phase of BaTiO₃, were confirmed by X-ray diffraction analysis. FESEM micrographs show grain size variations from 530 to 670 nm. The temperature-dependent dielectric constant at various frequencies (50, 100, and 500 kHz, and 1 MHz) has been studied, and the dielectric study reveals the increase of dielectric constant and decrease of dielectric loss of composites with incorporation of BT content. Magnetic hysteresis loop was measured at low temperature (5 K) using superconducting quantum interference device and the variation of magnetization with temperature indicates the presence of spin glass behavior in the composite. The values of remnant polarization (2P_r) and the coercive field (2E_c) increase monotonously with an increase in BT content. The highest values of 2P_r (1.4 µC/cm²) and 2E_c (11.9 kV/cm) were obtained for 20 mol% BT addition. The presence of magnetocapacitance depicts the magnetoelectric coupling at room temperature. The highest value of the magnetocapacitance (3.4 %) has been observed for 20 mol% addition of BT. The value of magnetoelectric (ME) voltage coefficient (α) for composition x = 0.10 was found to be 2.3 mV/cm-Oe at 4000 Gauss, indicating the presence of ME coupling in the composites.