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Ultrasonic field (USF) is widely used to regulate the intrinsic properties of materials that are not applied in electromagnetic wave (EMW) absorption. One reason is that the lack of a response mechanism for the materials to USF hinders the expansion of their EMW absorption performance. Therefore, to address this issue, a series of CuS nanoparticles with diverse anions are constructed in the presence or absence of USF. The ultrasonic-induced cavitation effect can significantly promote CuS crystallization and lead to the accumulation of S defects at the grain boundaries (GBs). Furthermore, the S defects at the GBs are easily oriented and arranged, allowing the polarization relaxation retention to be maintained at 10 wt%. Consequently, the CuS with a nitrate precursor under USF shows an optimum effective absorption bandwidth (EAB) of 10.24 GHz at a thickness of 3.5 mm, which is 228.6% more than that without the USF. CuS with a chloride precursor also achieves an EAB of 3.92 GHz, even at a considerably low filler ratio. Thus, this study demonstrates the response mechanism of diverse anions to the USF for the first time and provides a novel technique to optimize the EMW absorption performance of semiconductors.
Chen et al. (Fri,) studied this question.