Structural, elastic, thermal and soft magnetic properties of Ni-Zn-Li ferrites

The Ni0.6-xLi0.5xZn0.4Fe2-0.5xO4 (x = 0.0, 0.2, 0.4, 0.6) ferrites prepared by the sol-gel auto-combustion method have been characterized by XRD, XPS, SEM, FTIR, VSM, impedance analyzer for various physical properties. The analysis of Fe 2p photoelectron spectra reveals that the valence state of iron ion is only trivalent. The cation distributions obtained from Rietveld refinement of XRD data show that Li+ ions occupy only octahedral sites, while Ni2+ Zn2+ and Fe3+ ions are distributed in both tetrahedral and octahedral sites. The increase in bond angles and (theta(1) and theta(2)) suggests the enhancement of A-B super exchange interaction which is further confirmed by the decreased alpha(gamma-K) angles and increased Curie temperature (T-c). All observed absorption bands in the FTIR spectrum have been explained by the vibrations of tetrahedra and octahedra. The Debye temperature (theta(D)) and the elastic moduli (bulk modulus B, rigidity modulus G and Young's modulus E) evaluated through FTIR spectroscopy decrease with the increase of Li+ and Fe(3+ )ions contents. The saturation magnetization (M-s) decreases firstly and then increases with x increasing. The initial permeability (mu(i)) increases monotonically with x. The value of dielectric constant (epsilon') sharply decreases at lower frequency and become almost stable at higher frequency for all samples, indicating the semiconductor behavior of the ferrites. Compared with the Li-Zn ferrite, the Ni-Zn ferrites has lower dielectric loss tangent (tan delta) and magnetic loss tangent (tan delta(m)) at higher frequency. This work represents the first exploration of the correlation of structure with elastic, thermal and magnetic and electrical properties of Ni-Zn-Li ferrites. (C) 2018 Published by Elsevier B.V.