Tuning Physical Properties of NiFe2O4 and NiFe2O4@SiO2 Nanoferrites by Thermal Treatment

Abstract The comparison between NiFe 2 O 4 (co-precipitation) and @SiO (co-precipitation microemulsion) ferrite nanoparticles in their as-received annealed form is presented. structural characterization revealed the gradual crystallization of samples induced by thermal treatment. existence cubic inverse spinel structure with tetrahedral octahedral iron occupancy confirmed all comprehensive study. Fourier-transform infrared (FTIR) spectroscopy typical other Fe-based states, whereas presence nonstoichiometric hematite detected sample. In case embedded into silica matrix, initially amorphous microstructural characterization. As shown FTIR, applied treatment reduces water molecules hydroxyl units compared to initial material. separation rhombohedral ? -Fe 3 phase evidenced during annealing process demonstrated magnetic studies. analysis saturation magnetization pointed spin canting phenomenon surface layer a slight change so-called dead upon heating. room temperature superparamagnetic state (SPM) modified sample across as an effect grain growth well separation. For , decrease, blocking preceded freezing observed. shell recognized sustaining cover for SPM state. electronic studies complex nature states.