Microwave absorption design of water by the combination of dipole polarization and interfacial polarization

In this work, the microwave absorbing materials by the combination of water and bentonite were prepared, in which the water was used as microwave absorbent. The bond angle of water molecule is 104.5°, which is a typical dipole molecule. It is difficult to achieve the full frequency absorption in the X-band by dipole polarization alone. The bentonite particles are nano-layered structure, which can provide a large amount of interfaces and bring rich interfacial polarization. Meanwhile, a large amount of soluble cations is present in the bentonite, which brings in conductive loss when dissolved in water. The prepared water-bentonite composite can realize the full X-band absorption by the synergism effect of dipole polarization, interfacial polarization and conductive loss. The minimum relfection coefficient (RC_min) can reach − 59.8 dB, and the minimum thickness is 2.00 mm to achieve the full-frequency absorption. Due to the network distribution of water in the transparent bentonite matrix, the prepared water-bentonite composite has a low ratio of conductive loss and polarization loss, which is different from the conventional solid absorbents.