Sintering and cooling atmosphere effects on the microstructure, magnetic properties and DC superposition behavior of NiCuZn ferrites

This study investigated the sintering and cooling atmosphere effects on the microstructure and magnetic properties of NiCuZn ferrites. The copper-rich phase segregated during sintering near the grain boundaries. The sample sintered in N-2 and cooled in air (N-2 -Air)exhibited the highest amount of segregated copper-rich second phase, followed by the sample sintered and cooled both in air (Air -Air). However, no precipitate was observed for the sample sintered and cooled both in N-2 (N-2-N-2). This can be explained by the fact that Cu2+ was reduced into Cu+, promoting Cu2O phase precipitation and then reacting with CuO to form a liquid phase. The Air -Air sample exhibited the highest initial permeability (mu(I) approximate to 250) and saturation magnetization (B-s approximate to 88 emu/g), followed by N-2-N-2 (mu(j) approximate to 180, B-s approximate to 82) and N-2-Air (mu(j) approximate to 150,B-s approximate to 80). The highest DC superposition behavior was obtained for N-2 -Air sample due to the highest nonmagnetic copper-rich precipitate thickness at the grain boundaries. (C) 2017 Elsevier Ltd. All rights reserved.