Structural, electrical and magnetic properties of some Li-substituted Ni(0.7-2x)LixZn0.3Fe2+xO4 ferrites

Samples of Ni(0.7-2x)LixZn0.3Fe2+xO4 ferrites (x = 0, 0.15, 0.25 and 0.35) were prepared by a conventional sintering method. X-ray diffraction confirmed the formation of a single-phase cubic spinel structure where the lattice constant (a) decreases with lithium substitution. The decrease in d.c. resistivity with x is discussed as due to the increase in the bulk experimental density (σ) and the concentration of Fe2+ ions at the octahedral (B) sites. The substitution of 2xNi2+ ions with xLi+ and xFe2+ ions at the B sites naturally increase the Fe2+ ions at the sites. The saturation magnetisation (4πΜs), initial permeability (μi), remnant magnetization (Μτ) and coercivity (Hc) as a function of lithium content were measured at room temperature (TR). The results show that 4πΜs and μi increase, while Μτ and Hc decrease with increasing x. The relative complex magnetic permeabilities (Μτ* Μτ' - jΜτ'') in the frequency range of 100 kHz - 100 MHz were measured at room temperature. The result indicate that Μi, Μτ' and Μτ'' increase with increasing lithium content. The values of magnetic parameters indicate that the softness of the ferrites increases with x. (Author)