Complex Electromagnetic Parameters and Microwave Absorption Properties of Iron Nanochain/Carbon Nanotube Composite Materials

The relationship between impedance matching conditions, complex electromagnetic (EM) parameters, and EM wave absorption performances of iron nanochains and two kinds of Fe-CNT composites (the mass ratio of Fe to CNTs is 1.4:1 and 10:1, respectively) has been investigated by mathematical and statistical methods. A new direction for research on EM wave absorption mechanisms was provided. It is found that the impedance matching condition is the main factor affecting the absorption performances of the three materials when the thickness is less than 2.5 mm, and it is positively correlated with the absorption performance. When the thickness of the material is greater than 2.5 mm, a better impedance matching condition cannot guarantee good EM wave absorption performances. Instead, the real parts of complex permeability and permittivity play a dominant role, and the larger the real parts are, the better the EM wave absorption performance is. At the same time, it shows that when the thickness of the material is higher than 2.55 mm, it requires a strong energy storage capacity to achieve good absorption performance. The coefficient of variation of complex EM parameters at all frequencies observed can also affect the absorbing performance from the perspective of mathematical statistics. When the thickness is less than 2.5 mm, the smaller coefficient of variation of complex permittivity’s real parts and the bigger coefficient of variation of complex permeability’s imaginary parts, the better the absorbing performance of the material. If the modulus of the complex electromagnetic parameter is large, the absorbing performances of the material tend to be weak at all thicknesses.