posted on 2024-02-21, 16:05authored byWei Liu, Ronggan Cao, Pengtao Duan, Yue Ding, Hailin Su, Xuebin Zhang, Zhongqiu Zou
Conductive
carbon networks and multicomponent interfaces have been
constructed in Fe3O4/TiO2/C or Fe2TiO4/FeTiO3/C composites by pyrolyzing
core–shell structured Fe-bdc@TiO2 nanorods at different
temperatures. When the temperature rises to 700 °C, the growth
of internal Fe3O4 nanoparticles, the gradual
damage of TiO2 shells, and the maintenance of a one-dimensional
structure promote the formation of continuous conductive carbon networks
in paraffin, thereby increasing complex permittivity and dielectric
loss. With a further increase in temperature, phase conversion from
ferromagnetic Fe3O4 to antiferromagnetic Fe2TiO4 and FeTiO3 would result in the
depletion of TiO2 and C, generation of multiple interfaces,
and collapse of the one-dimensional structure, causing a slight reduction
in complex permittivity and dielectric loss. S-700 has a wide effective
absorption bandwidth (EAB) of 6.84 GHz at 2.2 mm (covering the entire
Ku band), and S-800 has a large EAB of 4.16 GHz at 2.8 mm, covering
the entire X band. We can deduce that conductive carbon networks mainly
composed of surface carbon and multiple interfaces between carbon
and titanates with defects contribute significantly to conduction
loss, dipole polarization, and interfacial polarization, both of which
shape RL curves under the influence of interference cancellation.
This work provides a feasible strategy based on the construction of
conductive networks and multicomponent interfaces in metal–organic
framework-derived carbon composites for broadened microwave absorption
bandwidth.