Study On The Mechanism Of Synergistic Effect Of High Energy Ball Milling And Microwave On Mineral Phase Reconstruction And Properties Of Barium Ferrite

Barium ferrite is a typical ferromagnetic material,because of its high saturation magnetization strength and large coercive force,it is often used in the production of permanent magnet materials,sensors,recording media,microwave absorption materials,etc.In this paper,ferric oxide and barium carbonate were used as the raw materials to prepare barium ferrite by high-energy ball milling and microwave sintering.By detection methods of X-ray diffractometer(XRD),scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR)and vibrating sample magnetometer(VSM),the changes of phase,microstructure,functional groups and magnetic properties of barium ferrite precursors were investigated under different high-energy ball milling time and different microwave sintering conditions.And the barium ferrite prepared by microwave sintering compared with that prepared by conventional sintering.Moreover,the phase change rule of barium ferrite precursor in high-energy ball milling process was elucidated from the point of view of quantitative analysis by infrared second derivative spectrum and fitting smoothing spectrum calculation method.The results of XRD and SEM showed that the diffraction peak width of each phase of barium ferrite precursor became wider,and the grain size was finer with the increase of milling time,the crystal lattice was gradually distorted to produce crystal vacancy defects,so that Ba was dissolved into the lattice of Fe₂O₃to produce the solid solution of Ba _XFe_2-XO₃,and the adsorption"agglomeration"phenomenon occurred.When the milling time was longer than 40h,the"nano-size effect"occurred,and magnetic Fe₃O₄and Ba _XFe_3-XO₄solid solutions were generated.The results of infrared spectrum analysis showed that the characteristic peaks of Ba CO₃and?-Fe₂O₃decreased and shifted significantly with the increase of ball milling time,indicating that the particle size of decreased and chemical reactions occurred with the increase of ball milling time.The smooth fitting spectrum and the second derivative spectrum of the infrared spectrum showed that the area of each absorption peak decreased obviously with the increase of the milling time.Compared with that of ball milling under 0h,the vibration absorption peak area of Fe-O bond at 473cm^-1decreased by 48.84%,65.97%and 93.54%,respectively,and at 540cm^-1,the absorption peak area of Fe-O bond decreased by 37.11%,51.76%and 82.85%,respectively.Similarly,the absorption peak area of in-plane bending vibration of O-C-O bond at 856cm^-1was 30.62%,44.71%and 67.10%,respectively,and the peak area of C-O bond asymmetric stretching vibration at the wave number of 1446cm^-1decreased by 0.03%,27.63%and 57.90%,respectively.The results of microwave sintering experiments showed that at the optimal sintering temperature(1000?),the magnetic energy of barium ferrite was as follows:saturation magnetization of 68.27 emu/g,residual magnetization of 32.36 emu/g and coercivity of3415.41 Oe.Under the optimal sintering temperature(900?),the magnetic energy of barium ferrite was as follows:the saturation magnetization of 53.67 emu/g,the residual magnetization of 26.34 emu/g and the coercivity of 5617.88 Oe.Compared with the barium ferrite prepared only by mixing sintering without high-energy ball milling,the coercivity was much higher and the sintering temperature was much lower.Also compared with conventional sintering,the magnetic properties of barium ferrite prepared by microwave sintering were similar,but the roasting temperature was reduced by 100?,and the particle size of the sample was uniform,and the sintering time was greatly shortened.