High-temperature solid state synthesis and characterization in magnetic and transporting properties of Zn_xFe_3-xO₄ powder

Zn-doped magnetite Fe₃O₄ samples were prepared at different doped concentrations and annealed at high temperature in ambient air and N₂ respectively. X-ray diffraction (XRD) results showed that samples annealed in air were oxidized and the consequent products were partially in α-Fe₂O₃ form. While for the samples annealed in N₂, Zn_xFe_3-xO₄ products of high purity were obtained. The doping of Zn²⁺ on the tetrahedral sites (A sites) changed the valence distribution of Fe²⁺ ions on the octahedral sites (B sites). The electron transporting mechanism remained to be variable range hopping (VRH) conduction. Measurement results of magnetic properties indicated that the super exchange coupling interaction between Fe²⁺ ions was affected by the low doping concentration of Zn²⁺ ions in the crystal, and the negative magnetoresistivity of Zn_xFe_3-xO₄ was improved as well.