Entropy-driven dual-phase engineering in sulfides via synergizing metallic conduction and disorder-interface polarization for microwave absorption

Polymetallic sulfides have emerged promising in modulating dielectric response, while their phase complexity obscures the contribution of specific elements on them, hindering dielectric optimization. Herein, we report the entropy-driven engineering that controllably synthesizes the consistent MS- and M 9 S 8 -type dual-phase (M = Fe, Co, Ni, Cr, Cu, Al) structures in medium/high-entropy sulfides, which pinpoint the role of specific metals. Entropy-driven (Cu/Al) doping optimizes metallic electron transport via filling the valley regions near the Fermi level in the density of states (DOS) to boost electron mobility, and promotes S deficiency degree, culminating in a 450% conduction loss enhancement. Concurrently, it promotes charge separation in lattice disorder areas and MS/M 9 S 8 phase interfaces charge transfer capacities, boosting the disorder-interface polarization loss by 7.86 times. Therefore, the senary high-entropy sulfide (6-HES) achieves an improved effective absorption bandwidth (EAB) of 4.96 GHz. Particularly, it demonstrates practical potential through a genetic-algorithm-optimized metamaterial with an ultra-wide EAB of 11.06 GHz. This work deciphers the specific roles of entropy-driven (Cu/Al) doping in modulating electron structure, and establishes a general paradigm for designing programming dielectric properties in high-entropy systems.