Tunable Magnetic and Dielectric Properties of BaMg0.4Al0.4Fe11.2O19 and SiO2 Composites for High-Frequency Applications

This study focuses on the synthesis and characterization of Mg and Al co-doped M-type Barium hexaferrite (BaMg0.4Al0.4Fe11.2O19) powder via the sol-gel method. Structural analysis using X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR) confirmed the single-phase structure of the synthesized powder. Morphological properties were examined through field emission scanning electron microscopy (FESEM), revealing hexagonal particle morphology with an average size of approximately 60 nm for BaMg0.4Al0.4Fe11.2O19. To fabricate composites, commercially purchased SiO2 was used to prepare the composites of (1–x) BaMg0.4Al0.4Fe11.2O19+ (x) SiO2 {where x = 0.0, 0.1, 0.3, 0.5 and 0.7). The composites were prepared using the mixing method followed by microwave sintered at 1000 °C/90 min. FESEM and energy-dispersive X-ray spectroscopy (EDS) were employed to analyze the morphology and elemental composition of the composites. The composites ‘ frequency-dependent complex permittivity was measured over 300 kHz to 3 GHz. Magnetic hysteresis (M-H) loops were used to analyze the magnetic properties of composite samples. A reduction in magnetic saturation was observed with increasing SiO2 concentration, while there was a slight increase in coercivity for the composite samples compared to pure hexaferrite. Coercivity remained relatively unchanged with varying SiO2 concentrations in the composites. A possible relation between the magnetic and dielectric properties and the microstructure of the sintered composites with the composition variation was investigated.