Chapter 6 - Microwave absorption of ferrite/carbon nanocomposites

Abstract

This chapter introduces ferrite-carbon nanocomposites with various compositional and morphological characteristics for use in microwave absorption media. The basic definition of shielding effectiveness is first explained based on mathematical relations, followed by an introduction to absorbing media, carbon materials, and supporting matrices. The roles of permittivity and permeability in the absorption mechanism are investigated. Hard ferrite-carbon nanotube nanocomposites are then introduced, and their magnetic and structural features along with variations in reflection loss versus frequency are evaluated. The effects of various carbon nanotubes, including those that are multiwalled and single-walled, on the absorption feature are considered. The impact of carbon nanotubes on the reflection loss characteristics of different spinel ferrites is also studied. New carbon nanocomposites, such as ferrite-graphene, are proposed as microwave absorbers, and the effects of structural defects and dielectric loss on the corresponding reflection loss are investigated. Other types of ferrite-carbon composites, including ferrite-graphite oxide, ferrite-carbon black, ferrite-carbon fiber, ferrite-amorphous carbon, ferrite-graphite nanosheet, and ferrite-MoS2 coupled with a nitrogen-doped carbon hybrid structure are also studied. The addition of carbon materials to balance permeability and permittivity is investigated within a wide frequency range to achieve the highest reflection loss values.