Low dielectric loss of Mg doped Ni-Cu-Zn nano-ferrites for power applications

Magnesium substituted nickel copper zinc nano-ferrite having the general formulae Ni0.5-xCu0.2Zn0.3MgxFe2O4 (0.0 <= x <= 0.4) were prepared at relatively lower temperature (900 degrees C) by sol-gel technique. Thermal gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy were used for the characterization of as-synthesized samples. It has been observed that the value of permittivity increases to a maximum value of similar to 8 x 10(2) for x =0 .4 sample. A remarkable decrease in power loss and loss tangent has been observed with the increase in Mg concentration. The Cole-Cole diagrams were investigated in which a single semi-circle is obtained for all the samples except for the sample with x = 0.4. The presence of two semi-circles for the sample with x = 0.4 indicates that the conduction is due to the grain and grain boundary, while for the rest of the samples the conduction due to the grain boundary is predominant. An improvement in magnetic properties has also observed in the magnesium substituted nickel copper zinc nano-ferrite. Also coercivity was found to decrease with Mg concentration which is useful for power applications. (C) 2012 Elsevier B. V. All rights reserved.