Effect of High-Energy Ball Milling on the Magnetic Properties of NiZn Ferrite Ceramics Synthesized by Spark Plasma Sintering

High-density fine-grained Ni0.5Zn0.5Fe2O4 ferrite ceramics were synthesized by spark plasma sintering (SPS) in conjunction with high energy ball milling. The precursor powders were milled for 20 h, 40 h, and 60 h, respectively, and the milled powders were all sintered for 5 min at 900 ̊C. All the samples exhibit a single spinel phase. With increasing of the ball milling time, the relative density of the samples increases (up to 97.7%), however, the grain size decreases (down to ~200 nm). At room temperature, the sample from the 40 h-milled powder has the best combination of saturation magnetization and coercivity (83 emu/g and 15 Oe). These outstanding magnetic properties may be associated with high density and uniform microstructure created by SPS on the basis of fine precursor powders produced by high-energy ball milling.