Bi_2O_3 liquid phase assisted and Mn substituted permeability and magnetic properties of Ni-Cu-Zn ferrite for multilayer chip inductor application

摘要

In the present work, low-temperature fired Mn_xNi_(0.5-x)Cu_(0.25)Zn_(0.25)Fe_2O_4 + Bi_2O_3 (x = 0.0 to 0.45) was synthesized by the sol-gel auto combustion technique at a temperature of 1073 K. Bi_2O_3 (with 2 wt. %) was used as a sintering aid for improving the density, microstructure and lowering the sintering temperature of Mn-Ni-Cu-Zn ferrites. Synthesized samples were investigated for their structural, magnetic, and electrical properties such as density, porosity, saturation magnetization, and permeability as a function of Mn~(2+) substitution. Permeability and saturation magnetization were found to increase with the replacement of Ni~(2+) with Mn~(2+). Bulk density of 4.5 g/cm~3 was observed for Mn-Ni-Cu-Zn ferrite with Bi_2O_3 additives which is greater than that of pure Mn-Ni-Cu-Zn ferrite (4.1 g/cm~3). Saturation magnetization of NiCuZn ferrite increased from 37 to 63 emu/g with increase in Mn~(2+) substitution. Mn substituted NiCuZn ferrite shows higher complex permeability (μ′=672) than that of the pure NiCuZn ferrite (μ′ = 433). Curie temperature determined from temperature dependent permeability data shows that Tc attains maximum value of 707 K.