Structure and magnetic properties of ball-mill prepared nanocrystalline Ni-Zn ferrite powders at elevated temperatures

► Lattice strain decreases and crystallite size increases with annealing temperature. ► Coercivity follows the Herzer's random anisotropy model in the temperature range 450-600 °C. ► Maximum saturation magnetization of 77.04 emu/g is obtained after heat treatment at 750 °C.