Grouping trends of magnetic permeability components in their parallel evolution with microstructure in Ni0.3Zn0.7Fe2O4

Ni-Zn ferrite, Ni0.3Zn0.7Fe2O4, with a wide variation of grain sizes has been prepared via high energy ball milling through two different sintering routes: multi sample sintering and single sample sintering. The parallel relationships between evolving rnicrostructural properties and AC magnetic response parameters were investigated using a FEI Nova NanoSEM 50 series and an Agilent Model HP4291B Impedance/Material Analyzer respectively. SEM micrographs showed larger grain size as the sintering temperature increased, consequently increasing the number of multi-domain grains. The AC magnetic response parameters belong to three groups with strongly, moderately and weakly ferromagnetic behavior respectively. Single-sample sintering and multi-sample sintering evolution yield quite similar permeability-grain size relationship trends. The permeability from both sintering routes is influenced by several factors which are degree of crystallinity, dominant magnetization process (ease of domain walls movement in multi-domain grains or spin rotation in single-domain grains) and large enough grain size which surpasses the critical grain size for transition from single-domain to multi-domain grains. (C) 2013 Elsevier B.V. All rights reserved.