Structural and electrical properties of magnetic ceramics of Co_1−xCu_xFe₂O₄ spinel nanoferrites

Abstract

Magnetic ceramics of the type of spinel nanoferrites of Co_1−xCu_xFe₂O₄ with Cu concentrations of x = 0·00, 0·25, 0·50, 0·75 and 1·00 were prepared by chemical co-precipitation method. X-ray diffraction results confirmed the formation of a single spinel ferrite structure with crystallite size in the range of 20–63 nm. Scanning electron microscopy and EDS were used to study the morphological and compositional changes taking place with varying Cu concentration. DC electrical resistivity, activation energy and drift mobility are strongly influenced by both Cu concentration and temperature. Resistivities of the prepared magnetic ceramics were found to decrease with the increase in Cu concentration to follow Verwey mechanism. The semiconductor behaviour of the prepared nanoparticles was confirmed from the standard Arrhenius relation of resistivity versus temperature. The dielectric constants were measured in the frequency range of 100 Hz–3·0 MHz and are explained by the Maxwell–Wagner interfacial type of polarisation.

Keywords:

• Co_1−xCu_xFe₂O₄
• Electrical resistivity
• Ferrites
• Magnetic ceramics
• Nanoparticles
• Spinel

The authors are thankful to Mr K. Akbar, Mr Z. Iqbal, Mr S. Ameer, Mr N. Ahmed and Mr Shmasudin from NUST for their support to carry out characterisation of the samples using XRD, SEM, EDS and DTA-TGA. The financial support of the Pakistan Science Foundation (PSF) through project no. 147 is also acknowledged.