Structural, Electrical, and Dielectric Properties of Multiferroic-Spinel Ferrite Composites

摘要

The present work reports development towards magnetoelectric ceramic composites, i.e., (1-x)Bi0.7Al0.3Mn0.3Fe0.7O3-xLi(0.3)Zn(0.4)Fe(2.3)O(4) with x = 0.0, 0.25, 0.35, 0.45, and 1.0. Al- and Mn-doped bismuth multiferroic Bi0.7Al0.3Mn0.3Fe0.7O3 (AMBFO) and Zn-doped lithium ferrite Li0.3Zn0.4 Fe2.3O4 (LZF) were synthesized by the coprecipitation and sol gel method, respectively. The composite system was synthesized by the conventional solid-state reaction technique followed by heat treatment at 700 degrees C for 6 h. X-ray diffraction (XRD) analysis confirmed the formation of orthorhombic and face centered cubic phase structure in AMBFO and LZF, respectively. The presence of peaks from both systems in the XRD pattern confirmed composite formation. The metal-to-semiconductor transition temperature decreased from 340 K to 330 K with increase in the LZF content, being mainly due to spin canting and phase structure conversion. The direct-current (DC) electrical resistivity was found to be highest for pure AMBFO and then started to decrease with increase in the Li-Zn ferrite (LZF) content in the composites. The dielectric constant decreased with increase in frequency for all samples, in accordance with Koop's phenomenological theory and the Debye relaxation model. However, the alternating-current (AC) conductivity increased with increase in frequency for all samples, which can be attributed to the conduction mechanism of polaron hopping. These composites open a new approach towards magnetoelectric applications, high-frequency devices, and semiconductor-based solar energy conversion systems.