Nickel-substituted manganese spinel ferrite nanoparticles for high-frequency applications

Nickel-substituted manganese spinel ferrite Ni x Mn 1− x Fe 2 O 4 ( x = 0.1, 0.2, 0.3, 0.4 and 0.5) nanoparticles have been prepared by sol–gel auto-combustion method. X-ray diffraction analysis reveals that prepared nanomaterials are spinel ferrite due to existence of secondary phase. The synthesis parameters such as molarity of reactants, magnetic stirring speed, temperature, amount of citric acid and annealing in ambient atmosphere have been optimized to control the crystallite size from 14 to 16 nm. The nickel substitution significantly affects the structural parameters such as lattice strain, micro-train, stacking fault and dislocation density. Dielectric properties were analyzed through impedance analyzer (LCR meter) for frequencies ranging from 1 kHz to 20 MHz and results depicted that synthesized nanoparticles respond to the electromagnetic radiations in terms of variation in tangent loss and dielectric constant as a function of Ni 2+ content. This behavior is related to the microstructural differences among conducting grains and resistive grain boundaries that contribute to the dielectric relaxation in these nanoparticles. The structural, dielectric and impedance analysis suggested that these nickels incorporated manganese spinel ferrite nanoparticles would have potential applications in high-frequency applications.