Effect of Dopants Mn2+ and Cd2+ Concentration on Electrical and Magnetic Properties of Li-Mixed Spinel Nanoferrites

Abstract

Spinel mixed Li-ferrites with incorporation of various dopants (Cd 2+ and Ni 2+ ) concentration in ranges 0.00 ≤ x ≤ 0.80 are prepared using sol-gel technique. The various phases, lattice constant/parameter, X-ray density and crystallite size are confirmed using X-ray diffraction (XRD). The particle size and lattice parameters are found in the range 15-33 nm and 8.35-8.66 Å. This confirmed that incorporating dopant strongly influences the material structure and an increase is observed in lattice parameter and particle size with increase in dopant concentration. The structure is influenced by the dopant position, at the octahedral (B) and tetrahedral (A) sites. The decrease in activation energy (E) is observed with increase in dopant concentration. Furthermore, analysis of the crystallite size and morphology is done using scanning electron microscopy (SEM), which confirmed that the observed particle size is comparable with the X-ray diffraction (XRD) results. The dopant affects electrical properties such as dc electrical resistivity and drift mobility. The observed trend for drift mobility and dc electrical resistivity confirmed the semiconducting behavior of the synthesized material. The magnetic parameters saturation magnetization (M s ), remanence (M r ) and coercivity (H c ) are strongly affected by dopant concentration. A sudden increase in magnetic parameters M r and M s is observed A. Faraz ( ) Thermal Transport Laboratory (TTL), School of chemical and materials Engineering (by incorporating a small amount of dopant up to x = 0.40 and with further incorporation cause a decrease in the values of these parameters due to the non-magnetic behavior of incorporating dopant Cd 2+ ions. These decreases in values can be explained using the spin canted model and cations positioning at tetrahedral (A) and octahedral (B) sites. The decrease in Curie temperature, observed with increase in dopant incorporation, is due to the decrease/weakening interaction between tetrahedral (A) and octahedral (B) sites.