Investigation of the Effect of pH in the Sol-Gel Process on Physical, Magnetic and Microwave Absorption Characteristics of Barium Hexaferrite Nanostructure

In this study, barium hexaferrite nano particles were synthesized with different size distribution via sol-gel combustion method under different pH of 7, 9 and 11.  Phase behavior, morphology and magnetic properties of final product were investigated respectively using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). Also electromagnetic parameters of synthesized samples were evaluated using vector network analyzer (VNA) in the X and Ku bands. The XRD results showed the formation of pure single phase of barium hexaferrite with average crystallite size of about 70 nm while pH value was 11. The SEM micrographs showed no significant influence of pH on the crystal morphology. However, at the higher the pH value, the particle size was lowered. According to VSM results, all magnetic parameters increase with pH. The maximum value of saturation magnetization and coercivity force were obtained as 55.61emu/g and 2805 Oe respectively for the synthesized sample at pH 11. Also, this sample had maximum reflection loss of about -6.7 dB and -9.8 dB at matching frequency of 11.6 GHz and 14.6 GHz in X and ku bands respectively.