Impact of aluminium doping on structural, magnetic and dielectric properties of magnetite nanoparticles

Abstract

Abstract Aluminium substituted nanoferrites Fe(3−x)AlxO4 with (x = 0.0, 0.1, 0.5, 1.0) samples were routed through auto-combustion. X-ray diffraction established the spinel cubic structure with no marking of impurities and the lattice constant were in between 8.398 Å to 8.359 Å. Crystallite size specifies the nano size formation and it varies from 32.15 nm to 21.38 nm with aluminium substitution. The field emission scanning electron microscope images shown the particles are in nano sized with uniform distribution. The energy dispersive X-ray analysis established the all basic elemental composition. FTIR spectra remarked two basic characteristic absorption bands, ν1 and ν2 between 600 cm− 1 and 404 cm− 1. VSM studies at room temperature remarked that the saturation magnetization (Ms), coercivity (Hc) and remanent magnetization (Mr) was decreased with aluminium substitution. Impedance spectroscopy studies were analysed with applied frequency and temperature to explore the dielectric nature of samples and evidenced that grain boundaries have more influence on the resistivity than grains. A clear deviation was observed in dielectric loss, dielectric permittivity and AC conductivity with temperature and frequency. This elucidated by the Maxwell-Wagner polarization and supports the hopping of Fe3+ and Fe2+ ions at the B-sites.