Research On Preparation, Characterization Of Cobalt-doped Nano-γ-Co_xFe_2-xO₃ Through Ambient Temperature Solid-state Reactions

In this paper, the precursors of nano-γ-Co_xFe_2-xO₃(x = 0 0.3)powders are synthesized with FeSO₄·7H₂O (AR), CoSO₄·7H₂O (AR) and H₂C₂O₄·2H₂O (AR) through solid state reaction at ambient temperature. XRD, ICP and FTIR analysis results show that the atomic-scale cobalt doped (Co_xFe_2-x)_1/2C₂O₄·2H₂O precursors can be obtained by the technology of solid-state reaction at ambient temperature. Through appropriate calcination temperature, single-phase nano-γ-Co_xFe_2-xO₃ which have good magnetic properties and high thermal stability are obtained. The grain sizes of these nano-γ-Co_xFe_2-xO₃ are about 20nm-30nm and have more uniform sizes.Technologies such as the use of XRD quantitatively evaluate of the content of cobalt-doped with nano-γ-Co_xFe_2-xO₃ grain growth activation energy relationship. Relationships between the content of cobalt-doped and phase composition of precursors when calcinated and nano-γ-Co_xFe_2-xO₃ lattice distortion and thermal stability are also discussed. Research shows that when the content of cobalt-doped (x) is greater than 0.1, the nano-γ-Co_xFe_2-xO₃ grain growth activation energy (Ea) descends sharply from 18.97kJ/mol to 9.30kJ/mol. The research also indicates that increase the content of cobalt-doped of nano-γ-Co_xFe_2-xO₃ can improve its thermal stability, the single-phase nano-γ-Co0.214Fe1.786O3 is obtained through calcining the precursor at 500℃for 3 hours.X -ray diffraction (XRD) and FTIR analysis show that with increase of cobalt-doped, Co-doping lead to a (Co_xFe_2-x)_1/2C₂O₄·2H₂O lattice contraction distortion and blue shift of infrared absorption bands and nano-γ-Co_xFe_2-xO₃ exhibit a lattice contraction distortion. Vibration sample magnetometer (VSM) analysis studies have shown that with the increase of cobalt content, the saturation magnetization, residual magnetization and coercivity of nano-γ-Co_xFe_2-xO₃ are all show the same changes law: first increase and then reduce and finally increase again . Under the condition of calcining at 450℃for 3h ,the nano-γ-Co_0.182Fe_1.818O₃ has obtained the highest saturation magnetization (39.7emu / g), residual magnetization (23.1emu / g) and coercivity (1790.3Oe).