Eur. Phys. J. Plus (2018) 133: 410
https://doi.org/10.1140/epjp/i2018-12209-5

Regular Article

Polarization and Ni content effects on structural properties, electrical conductivity, complex impedance and dielectric constant of Co-Mg-ferrites

¹ Laboratoire de Physique des Matériaux et des Nanomatériaux appliquée àl’Environnement, Faculté des Sciences de Gabes cite Erriadh, Université de Gabes, 6079, Gabes, Tunisia
² Unité de recherche Matériaux Avancés et Nanotechnologies, Institut Supérieur des Sciences Appliquées et de Technologie de Kasserine, Université de Kairouan, BP 471, 1200, Kasserine, Tunisia
³ Research unit of valorization and optimization of exploitation of resources, Faculty of Science and Technology of SidiBouzid, University of Kairouan, 9100, SidiBouzid, Tunisia

^* e-mail: rahmounihedi@yahoo.fr

Received: 7 March 2018
Accepted: 21 August 2018
Published online: 11 October 2018

Abstract

Pechini sol-gel technique was used to prepare Mg_0.6-x Ni _x Co_0.4Fe₂O₄ (x = 0 , 0.2, 0.4 and 0.6)-ferrite materials. Then, X-ray diffraction (XRD), scanning electron microscopy (SEM) and impedance spectroscopy techniques are used to investigate the structural, morphological, electrical and dielectric properties. The X-ray diffraction patterns show that the prepared samples have a single phase. The SEM micrograph shows that the particle has an unchanging grain size distribution. Electrical measurements show that the DC conductivity is sensitive to temperature. Then, it is well noticed that the Mott and Davis law is governed by the small polaron hopping model. Also, impedance measurements show that the real part of impedance is extensively reduced when applying a voltage bias of V. Such behavior can be related to the reduction of the available density of trapped charge. The results of Nyquist fitting are coherent with the electrical measurements according to which the sample with the highest DC conductivity possesses the lowest grain boundary resistance. Dielectric measurements confirm that the thermal evolution of the dielectric constant of the samples containing intermediary amounts of Ni (x = 0.2 and x = 0.4 is classical and show that the dielectric transition temperature is affected by polarization.