Spherical Aerogels of Multi-Walled Carbon Nanotubes and Polarizability Models of Conducting Spheres
The polarizability of different spheres consisting of low density MWCNT aerogel, metals, and connected wires are compared in the range of 8-12 GHz. Isotropic connected wire medium (with nanosized wire diameters 5.4 nm) has the structure discreteness with very small lattice constants (near 0.0002 wavelength). This leads to a significant drop in the effective conductivity of the wire medium (6 orders) and an increase in the Maxwell charge relaxation time. Due to this, the polarizability of the spheres consist of the cubic lattice of conductors decreases relative to all-metal spheres with the same conductivity by 10 %. The Debye length also grows to macroscopic sizes (up to 0.01 mm) and the static polarizability of the spheres changes due to a change in the charge distribution of the surface. MWCNT aerogels have a structure with non-rectilinear nanowires and a chaotic distribution of contacts. Nevertheless, it can be assumed that physical processes in such a medium are analogous to processes in media formed by regular structures. Indeed, measurements of the polarizability of aerogels support this proposition.
This work is supported by the Russian Science Foundation (grant 17-73-20293).