Preparation and electromagnetic properties of zinc ferrite/expanded graphite composites

Abstract

An effective process for the synthesis of nano spinel zinc ferrite/expanded graphite composites was developed in order to get an electromagnetic interference shielding material. Firstly, expandable graphite was prepared using sulfuric and nitric acid solutions. Then, the precursor of the composites was produced by chemical co-precipitation method, followed by heating treatment. The obtained composites were characterized by X-ray diffraction and scanning electron microscopy. The dielectric and magnetic properties were determined using vector network analyzer and vibrating sample magnetometry. The results showed that ferrite nanoparticles with the sizes of about 50 -150 nm were uniformly dispersed on the surface and interspace of EG. The magnetic properties of the composites changed by adjusting the ferrite/EG ratio and the composites had high dielectric constant in the range of 2 -18 GHz. These properties of the prepared composites suggest that they can be used as a promising electromagnetic interference shielding material.

Double Layer Microwave Absorption Characteristics of Barium Hexaferrite/Silica Composite for X-Band Frequencies

“…Various stable phases of hexaferrites are M-, Y-, X-, Z-and U-type, the M-type phase including the procedure for preparation of barium hexaferrite, thermal stability, crystal structure and observation of ferromagnetic properties have been studied by many investigators [6][7][8]. Few studies of barium hexaferrite have been reported on determination of its microwave absorbing properties in X-band frequencies [9][10][11][12][13]. However, all of these previous studies of barium hexaferrite were used as a single phase.…”