We report some research findings on the parallel evolutions of microstructural properties and magnetic hysteresis-loop properties; we attempt to elucidate their relationships. The Ni0.3Zn0.7Fe2O4 toroidal samples were prepared via high-energy ball milling and subsequent moulding; the samples with nanometer/submicron sized compacted powder were sintered from 600 degrees C to 1400 degrees C using 100 degrees C increments. An integrated analysis of phase, microstructural and hysteresis data would point to the existence of three distinct shape-differentiated groups of B-H hysteresis loops which belong to samples with weak, moderate and strong magnetism. The observed grain size with respect to the magnetic-hysteresis behaviour varied from 0.19 mu m to 0.23 mu m, 0.24 mu m to 0.43 mu m and 1.07 mu m to 4.98 mu m for weak, moderate and strong ferromagnetic behaviour respectively. The first occurrence of a strikingly erect and well-defined sigmoid-shape was observable only when sufficient single-phase purity and crystallinity and a sufficiently high volume fraction of multi-domain grains (>0.25 mu m) were attained. (C) 2012 Elsevier Ltd. All rights reserved.