PSynthesis, characterization and electromagnetic properties of Zn-substituted CoFe2O4 via sucrose assisted combustion route

Nanocrystalline Co(1-x)ZnxFe(2)O(4) ferrites (0.0 <= x <= 0.1) were synthesized via simple, economic and environmentally friend sucrose auto-combustion method. An appropriate mechanism for complexation process as well as ferrites formation was suggested and discussed. The detailed structural studies were estimated through X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) measurements. The results confirmed the formation of mixed spinel phase with cubic structure and exhibited a gradual decrease in the crystal size from 58 nm to 20 nm by the addition of zinc. Based on the obtained structural parameters, an appropriate cation distribution was suggested and reinforced via electrical and magnetic properties measurements. Hysteresis loops measurements, indicated ferromagnetic characteristics, with hard magnetic properties, for the samples with 0.0 <= x <= 0.6. The samples with higher Zn-content exhibited paramagnetic properties. The changes in the magnetization and coercivity by the addition of zinc can be discussed in the view of the influence of cationic stoichiometry and magneto-crystalline anisotropy, respectively. The huge decrease in the magnetization value at x >= 0.8 suggested a shift from ferromagnetic to paramagnetic characteristics. Ac-conductivity as well as dielectric constant behaviors reinforced this magnetic transition. The obtained Curie transition temperatures (T-C) were gradually shifted to lower temperatures by the addition of zinc. The addition of zinc results in the substitution of Co2+ ions in the octahedral sites thus, decreases B-B hopping probability, decreases conductivity and consequently increases activation energy. The most predominant conduction mechanisms in the ferromagnetic and paramagnetic regions are expected to be due to electron hoppings between different valence state ions and small positive polaron migration, respectively.