High-entropy structure design of transition metal dichalcogenides for improved electromagnetic wave absorption performance

Abstract

Transition metal dichalcogenides (TMDs) have attracted great interests due to their unique properties and wide range of applications. The versatile composition and tunable phase structure provide larger potential to explore TMDs with unprecedented properties. In the present work, a simple model based on the Hume-Rothery rules is proposed to predict the formation possibility of TMDs containing multiple transition metal elements. Several predicted high-entropy TMDs, e.g. (Ti0.25V0.25Cr0.25Nb0.25)S2 and (Ti0.2V0.2Cr0.2Nb0.2Ta0.2)S2 are synthesized through a solid-phase reaction route. The high-entropy solid solution of the M-site element results in an atomic-scale ordered/disordered stacking structure of the TMDs crystal, which enhances the dipole polarization. The multiple M-site elements induce 1T/2H phase transition within the TMDs sheets, which enhances the interfacial polarization. These two factors significantly enhance the dielectric loss of high-entropy TMDs, particularly endowing (Ti0.25V0.25Cr0.25Nb0.25)S2 with exceptional electromagnetic wave absorption capabilities. The maximum reflection loss of (Ti0.25V0.25Cr0.25Nb0.25)S2 reaches -60.31 dB and the effective absorption bandwidth is 2.31 GHz at 8.2-12.4 GHz band. This study demonstrates the great potential for tuning the properties and broaden the applications of TMDs through high-entropy structure design.