Influence of Ti substitution on structural and magnetic properties of Ni-Zn ferrites

Abstract

microscopy, respectively. The AC magnetic properties of these ferrites were characterized with high frequency (100 Hz-120 MHz) complex initial permeability and temperature dependent permeability measurements. The influence of microstructure, various cation substitution and sintering temperatures on the complex permeability of the samples are discussed. A possible correlation among sintering temperature, average grain size and density are also discussed. X-ray diffraction pattern shows the formation of spinel crystal structure of the ferrites. Lattice parameters are calculated using Nelson Riley function. A compression of unit cell dimension is observed, depending on various cation substitutions in these compositions. This result is explained with the help of ionic radii of substituted cations. The microstructural study shows that both sintering temperatures and cations substitutions have great influence on the average grain size. As the sintering temperatures increases bulk density increases, therefore, porosity decreases for all ferrites. The grain size, density, and lattice parameter of Ni0.5Zn0.38Ti0.060.06Fe2O4 ferrites are found to have the highest values. The real part of initial permeability, μi /, value decreases with increasing Ti substitutions for all compositions. It is also observed that μi / increases with sintering temperatures for all ferrites because high sintering temperature results uniform grain growth. The μi / remains fairly constant in the frequency range up to some critical frequency which is called resonance frequency. The high resonance frequency (15.2 MHz) is found for Ni0.5Zn0.38Ti0.060.06Fe2O4. The relative quality factor is found to be maximum for Ni0.50Zn0.44Ti0.03 0.03Fe2O4 ferrite sintered at 1300°C. The Néel temperature increases as a result of Ti substitutions. These results are helpful for practical applications.