Magnetic Studies Of Nonmagnetic Ions Substituted MnZn Ferrites

MnZn ferrites are one of the soft magnetic materials that are widely used, bucause of its high initial permeability, elcetrical resistivity, saturation magnetization, as well as relatively lower coercivity and power losses, which had been widely used in electronics, communication, office automation and other fields. However, different synthesizing methods make a different to structures and magnetic properties of Mn-Zn ferrites, such as synthesizing methods, different ratio of ions, solution pH value, complexing agent, calcining heat and the doping of different metal ions. In this paper, manganese-zine ferrites powders were obtained by the sol-gel auto-combustion method, and to dope modification research,different cation(Li+ ions and Al3+ inos) were selected. Structures and magnetic properties of all samples were characterized by X-Ray Diffractometer(XRD), Scanning Electron Microscope (SEM), Mossbauer Spectrometer, Superconducting Quantum Interference Device (SQUID) and Vibrating Sample Magnetometer(VSM). The main research work is as follows:1. The Zn1-xMnxFe2O4 (x=0,0.15,0.25,0.35,0.45,0.55,0.75,0.85) ferrites nanopowders were synthesized by the sol-gel auto-combustion method using citric acid as complexing agent, and mole ratio of metal ions and citric acid is 1:1. All samples were sintered at 550 ℃. The XRD analysis shows that the structure of samples are cubic spinel ferrite. The SEM analysis shows the samples particles are sphere and agglomeration. The Mossbauer Spectrum analysis shows that the paramagnetic double lines spectra gradually change zeeman six lines spectra. The VSM analysis shows the saturation magnetization, the coercive force and remanent magnetization of the samples increased with Mn2+ ions concentration increasing.2. Non-magnetic Li+ ions substituted Mno.4Zno.6Fe2O4 ferrites were studied. The XRD analysis shows that the samples are single cubic spinel phase, and the lattice parameter decreased with Li+ ions concentration increasing. The SEM analysis shows that particle size increased and aggregated. The Mossbauer Spectrum analysis shows that with Li+ ions concentration increasing paramagnetic phase gradually transformed into a ferromagnetic phase. The SQUID analysis shows that the saturation magnetization and remanent magnetization of the samples increased with Li2+ ions concentration increasing.3. Non-magnetic Al3+ ions substituted Mn0.6Zn0.4Fe2O4 ferrites were studied. The XRD analysis shows that the structure of samples are cubic spinel ferrite, and the lattice parameter decreased with Al3+ ions concentration increasing. The SEM analysis shows that particle size is uniform and good dispersion. The Mossbauer Spectrum analysis shows that ferromagnetic phase completely transformed into paramagnetic phase with Al3+ ions concentration increasing. The SQUID analysis shows the saturation magnetization, coercive force and remanent magnetization of the samples decreased with Al3+ ions concentration increasing.