Magnetic and microwave attenuation behavior of Al-substituted Co2W hexaferrites synthesized by sol-gel autocombustion process

A series of Al-substituted Co₂W hexaferrites BaCo₂Al_xFe_16 ? xO₂₇ (x = 0, 0.2, 0.4, 0.6, 0.8, 1) synthesized by sol-gel autocombustion method have been investigated. The samples were characterized by DTA/TGA analysis, FTIR spectroscopy, X-ray Diffractometer and field emission gun scanning electron microscopy (FEGSEM). Magnetic behavior of a selected sample was examined up to a magnetic field of 9T between a temperature range of 4.2 K–400 K. The values of saturation magnetization were calculated by the law of approach to saturation. The coercivity of the investigated sample has a value of about hundred oersteds at room temperature which is favorable for EM materials. The complex permittivity and complex permeability of a composite sample have been measured in the frequency range of 0.5–13 GHz. Based on the theoretical calculation of re?ection loss; the microwave absorption properties have been investigated. The results indicate that the attenuation peak frequency of these compounds can be tuned for the desired frequency by varying the thickness of the absorber.