Fabrication and Physical Characterization of Ni1-xZnxFe2O4 and Cu1-xZnxFe2O4 Ferrites

Abstract

The effects of zinc substitution on the nickel based and copper based spinel ferrites have been investigated. Three series of spinel ferrites with nominal compositions Ni1-xZnxFe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0), Cu1-xZnxFe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0), and Ni0.8-xCuxZn0.2Fe2O4 (x = 0.0, 0.2, 0.4, 0.6, 0.8), were prepared by the conventional solid state reaction technique. The samples were characterized by SEM, X- ray diffraction, DC electrical resistivity, dielectric properties and magnetic properties measurements. Grain size was measured from the scanning electron micrographs. The average grain size of sintered ferrites was within the range of 2.36-6.16 μm, 26.75-3.25 μm, and 3.15-26.75 μm, for Ni-Zn, Cu-Zn and Ni-Cu-Zn ferrites respectively. The X-rays diffraction was done through PANalytical diffractometer using Cu Kα radiations (λ = 1.054Å). Lattice constant increased with the increase in zinc concentration in case of Ni1- xZnxFe2O4 and Cu1-xZnxFe2O4 ferrites, whereas it increased with the increase in copper concentration in case of Ni0.8-xCuxZn0.2Fe2O4 ferrites. Sintered density increased with the increase in zinc concentration in case of Ni1-xZnxFe2O4 and Cu1-xZnxFe2O4 ferrites whereas it increased with the increase in copper concentration in case of Ni0.8-xCuxZn0.2Fe2O4 ferrites. X-ray density decreased with the increase in zinc concentration in case of Ni1-xZnxFe2O4 and Cu1-xZnxFe2O4 ferrites whereas it decreased with the increase in copper concentration in case of Ni0.8-xCuxZn0.2Fe2O4 ferrites. Porosity decreased with the increase in zinc concentration in case of Ni1-xZnxFe2O4 and Cu1- xZnxFe2O4 ferrites whereas it decreased with the increase in copper concentration in case of Ni0.8-xCuxZn0.2Fe2O4 ferrites. DC electrical resistivity measurements were carried out by two-probe method from 300 K to 540 K in case of Ni-Zn ferrites, 320 K to 520 K in case of Cu-Zn ferrites and 305 K to 603 K in case of Ni-Cu-Zn ferrites. Activation energy and drift mobility were also calculated from the measured resistivity. The dielectric constant was measured as a function of Zn substitution in Ni-Zn ferrites as well as a function of Cu concentration in Ni-Cu-Zn ferrites. The dielectric constant and dielectric loss factors were measured as a function of frequency for all the samples in the range of 80 Hz to 1 MHz at room temperature. The ac conductivity σac in case of Ni-Zn ferrites was also measured. To measure the magnetic properties of the prepared materials, the M-H loop of the specimen were drawn. From the M-H loop of the sintered materials, we measured saturation magnetization. Magnetic moment, coercivity and Yafet-Kittel angles were also calculated. Saturation magnetization increased up to x = 0.4 and then decreased with the further increase in Zn concentration in case of Ni-Zn and Cu-Zn ferrites whereas it decreased with the increase in Cu concentration in case of Ni-Cu-Zn ferrites. The magnetic moment also had the similar trend. Coercivity decreased with the increase in Zn concentration in case of Ni-Zn and Cu-Zn ferrites. The Yafet-Kittel (Y-K) angles initially had zero value and then increased with the rise in Zn concentration for x > 0.2, x > 0.4, x > 0 in case of Ni-Zn, Cu-Zn and Ni-Cu-Zn ferrites respectively.