Evaluation of structural, magnetic, optical, electrical, and humidity sensing properties of manganese-substituted zinc ferrite nanoparticles

Abstract

Manganese-zinc ferrite nanoparticles with composition Mn y Zn 1-y Fe 2 O 4 (0 ≤ x ≤ 1) were synthesized using the coprecipitation technique. The formation of cubic spinel structures with average crystallite sizes less than 16 nm is confirmed by X-ray diffraction. On replacing Zn 2+ ions with Mn 2+ ions, compressive lattice strain is produced which lowers the lattice parameter. Thermogravimetric analysis (TGA) demonstrates superior thermal stability of ZnFe 2 O 4 nanoparticles. The superparamagnetic nature of Mn-Zn ferrites was revealed by vibrating sample magnetometer (VSM). The specific magnetization lies between 14.6 and 21.7 emug −1 . The optical bandgap energy ranges from 2.34 to 2.84 eV. With increasing Mn 2+ ions, the dc electrical resistivity shows a preliminary increase followed by a steady decline. The exposure of ferrite pellets to humidity facilitates the conduction mechanism. Resistivity significantly decreases with increasing relative humidity. Among Mn-Zn ferrites, ZnFe 2 O 4 nanoparticles possess superior humidity sensing properties.

Elucidation of structural, electromagnetic, and optical properties of Cu–Mg ferrite nanoparticles

“…(18) , (19) , (20) , the formulae below. In these equations, Cp seems to be the capacitance of the spinel ferrite tablet placed among two circular electrodes with surface area of A, the thickness of the tablet is d, and the vacuum permittivity ε 0 is (8.85 10–12F/m) [ 26 , 50 ].…”

“…As a result, the nonlinear fluctuation in dielectric constant might be caused by the insertion of Cu 2+ ions, which lowers the quantity of Fe 3+ ions on B-sites, which is responsible for both space charge polarization and hopping interchange between two localized states. It is worth noting that the highest dielectric constant dispersion was observed for x = 1.0 and 0.75 at 4.5 MHz in Table 6 copper concentration, most likely due to the production of the presence of Fe 2+ ions on octahedral sites and results in a low resistive grain boundary phase [ 31 , 50 ].…”

“…The change in Eg is equivalent to the change in the lattice parameter. When the proportions of the lattice are lowered, electrons expand more closely coupled to atoms, demanding a high excitation energy [ 50 , 75 , 85 ]. Band gap values are well reported to be controlled by film thickness, crystallite size, lattice constant, purity, stoichiometry, charge carrier concentration, and lattice strain [ 9 , 76 ].…”