  Substantial efforts have been devoted to the elaborate component and
microstructure design of absorbents (inclusions) in microwave absorbing (MA)
composite materials. However, mesoscopic architectures of composites also play
significant roles in prescribing their electromagnetic properties, which are
rarely explored in studies of MA materials. Herein, a composite containing
randomly distributed ZrB2 particles is fabricated to offer a mesoscopic cluster
configuration, which produces a novel dielectric resonance. The resonance
disappears and reoccurs when ZrB2 is coated with the insulating and
semiconductive ZrO2 layer respectively, suggesting that it is a plasmon
resonance excited by the electron transport between ZrB2 particles in clusters
rather than any intrinsic resonances of materials constituting the composite.
The resonance strength can be regulated by controlling the quantity of the
electron transport between particles, which is accomplished by gradually
increasing the insulating ZrO2-coated ZrB2 ratio x to disturb the electron
transport in ternary disordered composites containing ZrB2 and insulating
ZrO2-coated ZrB2. When x exceeds 0.7, the electron transport is cut off
completely and the resonance thus disappears. The resonance induces unusual
double quarter-wavelength interference cancellations or resonance absorption
coupled with quarter-wavelength interference cancellation, giving rise to
continuous dual-peak absorption. This work highlights the significance of
mesoscopic architectures of composites in MA material design, which can be
exploited to prescribe novel electromagnetic properties.
