Structural, Dielectric, Magnetic And Magnetoelectric Characterization Of Co0.5Ni0.5Fe2O4 - Bi0.9La0.1FeO3 Composite

Smart Materials Research Laboratory, Department of Physics, Indian Institute of Technology, Roorkee 247667, Roorkee, India

Adv. Mater. Lett., 2015, 6 (10), pp 853-861

DOI: 10.5185/amlett.2015.5856

Publication Date (Web): Sep 18, 2015

Copyright © IAAM-VBRI Press

E-mail: klyadav35@yahoo.com

Abstract

Mixed spinel -perovskite composites of (x) Co_0.5Ni_0.5Fe₂O_4-(1−x) Bi_0.9La_0.1FeO₃(x = 0, 0.25, 0.40, 0.55, 1.0) have been synthesized by conventional solid state reaction method and annealed at 850 ºC. The X-ray diffraction (XRD) pattern shows that the composites consisted of spinel Co_0.5Ni_0.5Fe2O₄ and rhombohedral perovskite Bi_0.9La_0.1FeO₃ ceramics. FESEM micrographs show closely packed microstructure with grain size in the range 503 nm - 960 nm. Variation of dielectric constant and dielectric loss with temperature at two fixed frequencies (500 kHz and 1 MHz) was studied. The composite with composition x = 0.55/sintered at 850 ºC exhibits the largest coercitivity (Hc) of 883 Oe. The saturation magnetization (Ms) and magnetic moment (µ_B) increase with an increase of Co_0.5Ni_0.5Fe₂O₄ concentration in the composites. From ferroelectric hysteresis loop analysis the values of remnant polarization (Pr) and coercive field (Ec) was found to lie in the range of 0.018-0.745 µC/cm² and 3.89-6.06 kV/cm. The relative change of magnetocapacitance was found to be 6.6% at a magnetic field of 8 kOe for x = 0.55 composition. Impedance analysis suggests the presence of a temperature dependent electrical relaxation in the material having a typical negative temperature coefficient of the resistance (NTCR) behavior analogous to a semiconductor.

Keywords

Composites, XRD, dielectric, ferroelectric, hysteresis loop.