Studies on dielectric and magnetic properties of barium hexaferrite and bio-waste derived activated carbon composites for X-band microwave absorption

Abstract

The effect of the addition of bio-waste derived activated carbon (AC) on magnetic and dielectric properties of barium hexaferrite (BaFe12O19) has been investigated for microwave absorption application. Activated carbon was synthesized from banana peel while the low-density barium hexaferrite was fabricated by using the auto-combustion method. The composites consisting of highly conducting activated carbon and magnetic barium hexaferrite were prepared by using the low-cost ball-milling method. The addition of activated carbon in the ferrite matrix resulted in increased reflection loss due to interfacial polarization. The dielectric permittivity and dielectric loss tangent of BaFe12O19 showed a gradual increase with addition of AC. The magneto-crystalline anisotropy is however reduced with AC addition which resulted in decreasing values of saturation magnetization and magnetic loss tangent. The impedance matching, attenuation constant and reflection loss of the composites were calculated to determine their microwave absorption. The composite comprising of 40% BaFe12O19 and 60% AC showed the maximum reflection loss of −35.5 dB in X-band for coating thickness 1.3 mm. The 90% microwave absorption of the composite was achieved in the frequency range from 9.8 to 11.8 GHz. The results showed that the microwave absorption property of BaFe12O19 can be tuned in X-band by the addition of activated carbon.