Investigation on growth mechanism and gyromagnetic properties of low-sintered Li0.43Zn0.27Ti0.13Fe2.17O4 ferrite doped with Nb2O5 and glass sintering additives

Abstract

Interest in improving the magnetic properties by co-doping has thrived since it is demonstrated that such co-doping can be used to control the microstructure of ferrites at a low sintering temperature. Usually this process involves grain growth and densification by liquid phase sintering or, in some cases, abnormal growth of grain. Here, we study the growth mechanism of the low-sintered LiZnTi ferrites doped with additions of Nb2O5 and Li2CO3-MgO-ZnO-B2O3-SiO2 (LMZBS) glass through characterization of microstructure and magnetic properties. SEM results show that along with the increase of LMZBS glass contents, the change of ferrite grain presents three different stages. At the initial stage, densification of grain is dominant and grain growth is unconspicuous. Due to the increase of LMZBS glass content, the main process at the second stage is grain growth. At the last stage, however, grain growth starts to be suppressed and pores appear again because of competition between the two additives. Corresponding to each stage, the magnetic parameters of the LiZnTi ferrites, including 4πMs, Hci, Bs, Br/Bs and ΔH, have different trends. Moreover, XRD patterns show that all samples have a pure spinel phase, which means influence of the two additives on crystal structure is negligible. All in all, we obtain a LiZnTi ferrite with uniform and compact microstructure, high saturation flux density (Bs=294.2mT), remanence ratio (Br/Bs=0.87), saturation magnetization (4πMs=3700.1 G) and low ferromagnetic resonance linewidth (ΔH=253) at 900 °C.