Enhancement of structure, dielectric and magnetic properties of nanocrystalline Mn–Zn ferrites using Ni–Ti ions

The present work concerned with the effect of substitution of Fe3+ magnetic ion by magnetic and nonmagnetic ions together, Ni2+–Ti4+ ions. Ferrite samples with general formula Mn0.9Zn0.1NiyTiyFe2-2yO4 (0.0 < y ≤ 0.25) were prepared using conventional ceramic technique. Single phase cubic spinel structure of the studied samples was confirmed using X-ray diffraction pattern. The surface morphology and compositional features of the prepared samples were studied using scanning electron microscope (SEM) and EDAX measurements. The porosity and lattice parameter of the samples are calculated as a function of Ni–Ti concentration. Temperature, frequency and compositional dependence of the dielectric constant (e`), ac resistivity (ρ) and dielectric loss tangent (tan δ) were studied. All the samples give the normal dielectric behavior of ferrites with temperature and frequency. The experimental results indicate that e`, tan δ and ρ decrease as the frequency increase. This behavior was discussed on the basis of Maxwell–Wagner model and Koops theory. The imaginary part of dielectric modulus (M``) was calculated and plotted as a function of temperature. The hysteresis loop parameters were measured as a function of Ni–Ti content using VSM. The obtained results revealed that the dielectric properties of Mn–Zn ferrites enhanced by increasing Ni–Ti concentration where the ac resistivity increased 7 times and the dielectrics loss tangent reduced by 95% of un-substituted Mn–Zn ferrite. The present work indicates also that the sample Mn0.9Zn0.1Ni0.1Ti0.1Fe1.8O4 shows high ac resistivity, low dielectric loss and high magnetization and most suitable for microwave applications