Microstructure and magnetic properties of porous NiCuZn ferrite ceramic

Abstract

In the present work, this paper demonstrated that pore is an alternative additive for obtaining a substrate material with equivalent permeability and permittivity by decreasing permeability of NiCuZn ferrite ceramic. Firstly, the (Ni 0.2 Cu 0.2 Zn 0.6 O) 1.03 (Fe 2 O 3 ) 0.97 ferrite ceramic with 0.25 wt.% Nb 2 O 5 and 0.50 wt.% Bi 2 O 3 additives was synthesized by a solid phase method at O 2 atmosphere. Results showed that the compact NiCuZn ferrite (c-NiCuZn) sintered at 900 °C possess a high permeability (μ r ’=427.6) and low magnetic loss (tanδ μ =0.016) at 1MHz. Also, the SEM image showed that the ferrite possess uniform and compact microstructures. As a reference, the NiCuZn ferrite without any additives (named n-NiCuZn) was obtained by same method. Results indicated the permeability of the n-NiCuZn ferrite ceramic with few pores obviously reduced (μ r ’=151.4) at 1MHz due to low sintering temperature and inadequate reaction. Meanwhile, the magnetic loss (tanδ μ ) is 0.029 at 1MHz. To obtain porous NiCuZn (p-NiCuZn) ferrite ceramic, we added 10.0 wt.% g-C 3 N 4 into the pure NiCuZn ferrites. Due to remove of g-C 3 N 4 powders (high temperature sintering), there are more pore between grains of the NiCuZn ferrite. Thus, the permeability and magnetic loss of the p-NiCuZn are 53.7 and 0.041, respectively. More importantly, the cutoff of the p-NiCuZn ferrite ceramic can increase from 10.8 MHz to 63.1 MHz when more pores were introduced. Thus, the pores are an alternative additive to reduce permeability of magnetic ferrite ceramics to meet application requirements.