Synthesis of M-type hexaferrite reinforced graphene oxide composites for electromagnetic interference shielding

Abstract

This study focused on addressing the increasing demand for materials that can effectively shield against electromagnetic interference. In particular, Ba0.7Mn0.3Nd0.1Fe11.9O19 M-type hexaferrite was synthesized using the sol–gel auto-combustion method and sintered at 1050 °C. The modified Hummer process was used to prepare graphene oxide (GO), and three composites were then synthesized with the ultrasonication method, which were denoted as C-1 (90 % M-ferrite + 10 % GO), C-2 (80 % M-ferrite + 20 % GO), and C-3 (70 % M-ferrite + 30 % GO). X-ray diffraction (XRD) analysis confirmed the formation of the hexagonal phase of the M-type barium hexaferrite and GO. A prominent peak at an angle of 8.82° corresponding to the (001) reflection was observed by XRD analysis for the GO sample and it confirmed the effective oxidation of graphite and formation of GO. Scanning electron micrographs of M-type hexaferrite demonstrated the formation of platelet-like grains with hexagonal shapes, which were suitable for microwave absorption. The direct current electrical resistivity at room temperature was determined as 2.08 × 10−8 Ω-cm for the M-type ferrite, and the resistivity of the composites decreased as the concentration of GO increased due to the superior conductivity of GO compared with the ferrite. The dielectric properties of all samples followed the Maxwell–Wagner model. The dielectric characteristics increased in magnitude as the GO content increased. The AC magnetic susceptibility decreased for the M-type ferrite and three composites as the temperature increased to eventually reach a steady state at a specific temperature known as the Curie temperature. Except for GO, the Curie temperatures of all samples were within the range of 348 K–450 K. Coupling magnetic ferrite with GO allows the magneto-electrical characteristics to be tuned, with possible uses in electronic devices, electromagnetic shielding, supercapacitors, and water purification.