Structural, electrical and magnetic properties of cobalt ferrite with Nd3+ doping

Abstract

A systematic study on the influence of Nd3+ substitution on structural, magnetic and electrical properties of cobalt ferrite nanopowders obtained by sol–gel auto-combustion route was reported. The formation of spinel phase was confirmed by X-ray diffraction (XRD) data, and percolation limit of Nd3+ into the spinel lattice was also observed. Fourier transform infrared spectroscopy (FTIR) bands observed ≈ 580 and ≈ 390 cm−1 support the presence of Fe3+ at A and B sites in the spinel lattice. The variation in microstructure was investigated by scanning electron microscopy (SEM), and the average grain size varies from 5.3 to 3.3 µm. The substitution of Nd3+ significantly affects the formation of pores and grain size of cobalt ferrite. Room-temperature saturation magnetization and coercivity decrease from 60 to 30 mA·m2·g−1 and 19.9–17.8 mT, respectively, with Nd3+ substitution increasing. These decreases in magnetic properties are explained based on the presence of non-magnetic nature of Nd3+ concentration and the dilution of super-exchange interaction in the spinel lattice. The room-temperature direct-current electrical resistivity increases with Nd3+ concentration increasing, which is due to the unavailability of Fe2+ at octahedral B sites.