Influence of LZN nanoparticles on microstructure and magnetic properties of bi-substituted LiZnTi low-sintering temperature ferrites

Abstract

Microstructural changes including grain growth and densification in ferrite ceramic materials, either through liquid phase sintering or by lowering reaction energy, have a profound effect on the material properties. In this work, Li0.365Zn0.27Fe2.365O4 (LZN) nanoparticles were prepared by sol-gel method. HRTEM image of the LZN nanoparticles showed that the spinel structure nanoparticles with ~26 nm average particle size were obtained at 500 °C. As a reaction additive, the LZN nanoparticles were introduced into a Bi-substituted Li0.43Zn0.27Ti0.13Fe2.17O4 (LiZnTiBi) ferrite ceramic to control abnormal grain growth and enhance magnetic properties. XRD patterns demonstrated that a pure spinel phase structure composite ceramics were synthesized. This indicated the LZN nanoparticles can further react with LiZnTiBi ferrite ceramics. Also, SEM images showed that adding LZN nanoparticles can obviously control abnormal grain growth and reduce pores between grains. More importantly, results of ferromagnetic resonance (FMR) linewidth (ΔH) showed that optimized LZN nanoparticles additives can reduce ΔH of the LiZnTiBi ceramics (reduced to ~185.53 Oe). Meanwhile, saturation magnetization (4πMs) of the ceramics can be improved (up to 4504.96 gauss) by adding 2.00 wt% LZN nanoparticles. The doping method reported in this study also provides a referential experience for other low temperature sintering ceramics.