Microwave Electromagnetic and Absorption Properties of AFe2O4(A=Ni,Mn,Zn) Ferrites

The spinel ferrite (AFe(2)O(4), A=Ni, Zn, Mn) were prepared under the same condition via sol-gel method. The structure and electromagnetic properties of the powders were characterized by X-ray diffractometer, scanning electron microscope, and vector network analyzer, respectively. These materials were found to be very good catalysts for the oxidation of styrene to benzaldehyde in the presence of hydrogen peroxide. Because of the difference in radius and electrical of these ions (Ni2+, Zn2+ and Mn2+), the ion distribution of ferrites were diverse, so that the electromagnetic parameters and absorbing properties varied. After analyze the contour map of the attenuation constant a and reflectivity R, it shows that the absorbing weak point of NiFe2O4 lies in the high frequency range 8-14GHz, the absorbing properties of MnFe2O4 is relatively balanced, and the absorbing capacity of ZnFe2O4 in the high-frequency part is poor. NiFe2O4, MnFe2O4 and ZnFe2O4 in absorbing band complement each other very well. By preparing an appropriate proportion of Ni-Mn-Zn composite spinel ferrite, an excellent absorbing agents will be expected.