Preparation And Study On The Propties Of α"-Fe₁₆N₂/SBA-15 And Its Precursor α-Fe₂O₃/SBA-15

Nano-magnetic materials exhibit excellent excellent magnetic properties due to high specific surface area and finite-size effects.Thus nano-magnetic materials have broad application prospects in the fields of magnetic recording,permanent magnet,photocatalysis and biomedicine.α"-Fe₁₆N₂ has giant saturation magnetization,high oxidation resistance and corrosion resistance so that it has potential application in high-density magnetic storage,magnetic sensing components,and rare earth-free permanent magnets.Thus,it has attracted the attention of scholars at home and abroad.In recent years,the low temperature nitridation method ofα"-Fe₁₆N₂ nanopowder has sparked much interest among researchers due to its simple process and high product purity.It is crucial to how to inhibit the agglomeration of nano-iron source and promote the adsorption and diffusion of N atom in the process of solid phase nitriding.In this paper,the ordered mesoporous material SBA-15,which has high thermal stability,large specific surface areas and uniform pore size,was used as the hard template to synthesize α-Fe₂O₃/SBA-15 by nanocasting method.Then,α-Fe₂O₃/SBA-15 was used as raw material to carry out on the reduction-nitridation experiment to synthesize α"-Fe₁₆N₂.The reduction-nitridation experimental parameters and the structure of the raw material on the formation ofα"-Fe₁₆N₂ phase and its magnetic properties were studied.The pure phase α"-Fe₁₆N₂ was synthesized by optimizing the experimental conditions（SBA-15 was unremoved）.In addition,the photocatalytic degradation of Rhodamine B solution by the raw material α-Fe₂O₃/SBA-15 and Co doped α-Fe₂O₃/SBA-15 was investigated.The specific research contents are as follows:（1）The effects of different hydrothermal temperatures on the structure of SBA-15 template were studied.And α-Fe₂O₃/SBA-15 was prepared by template replication method under the different hydrothermal temperatures of SBA-15 as template.The results showed that all the prepared SBA-15 and α-Fe₂O₃/SBA-15 samples had an ordered pore structure and α-Fe₂O₃ was successfully loaded in the SB A-15 channel.At the same time,the specific surface area,pore volume and pore size of α-Fe₂O₃/SBA-15 synthesized by SBA-15 with the hydrothermal temperature of 130℃ were higher than α-Fe₂O₃/SBA-15 having a hydrothermal temperature of 100℃.（2）The photocatalytic activity of α-Fe₂O₃/SBA-15 as catalyst on Rhodamine B solution under the visible light（λ=400 nm）was studied.The study found that the degradation rate of Rhodamine B solution reached a maximum of 96.25%when the mass of the catalyst was 40 mg and the amount of hydrogen peroxide was 4 ml;Co doped α-Fe₂O₃/SBA-15 showed the improved efficiency of degradation at the same conditions.（3）α"-Fe₁₆N₂ was synthesized by low temperature nitridation method withα-Fe₂O₃ as precursor.The effects of the structure of precursor and nitridation parameters on the formation of α"-Fe₁₆N₂ were investigated.The results showed that there was almost no α"-Fe₁₆N₂ using α-Fe₂O₃ nanowires as raw material.When using SBA-15 with hydrothermal temperature of 130℃ as the hard template,α-Fe₂O₃/SBA-15 is used as the raw material,and the reduction temperature is 550℃,the reduction temperature is 4 h,the nitriding temperature is 160℃,and the nitriding time is 8 h,the pure phase α"-Fe₁₆N₂ can be obtained.According to magnetic performance test and energy spectrum analysis,the saturation magnetization is 223 emu/g,and the coercive force is 1666 Oe.