Shifting d‐band Center: An Overlooked Factor in Broadening Electromagnetic Wave Absorption Bandwidth

• Published in: Advanced functional materials 2025-01, Vol.35 (3), p.n/a
• Main Authors: Yao, Kai, Pan, Fei, Liang, Hongsheng, Zhang, Xiang, Li, Lixin, Song, Lixin, Yang, Yang, Yuan, Bin, Lu, Wei
• Format: Article
• Language: English
• Subjects: Absorbers; Absorption; Bandwidths; Carrier density; cation vacancy; Cations; Current carriers; d‐band center; effective bandwidth; Electromagnetic radiation; electromagnetic wave absorption; heterogeneous interfaces; Heterostructures; Performance measurement
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202413639

Absorption bandwidth is one of the key performance metrics for electromagnetic wave (EMW) absorbers. Traditional oxide absorbers, despite their merits such as abundance, long‐term stability, and low cost, have long been plagued by their inferior absorption bandwidth (typically less than 4 GHz). Herein, a novel concept is proposed: the introduction of cation vacancies and heterostructures into oxides can remarkably broaden their absorption bandwidth. A broadening value of 7.75 GHz is observed through this route, surpassing the broadening achieved by other existing engineering methods, by ≈100%. Crucially, this study discovers that a negative shift in the d‐band center, a previously overlooked factor, is responsible for this broadening phenomenon. By inducing cation vacancies and heterostructures, a negative shift in the d‐band center gives rise to an increase in carrier concentration and promotion of charge separation, resulting in higher conductive and polarization losses, ultimately leading to a broader absorption bandwidth. The applicability of this concept is validated in another distinctly different system, where the absorption bandwidth also experiences a remarkable increase (from 0 to 6.86 GHz). This study offers significant implications for designing wide bandwidth EMW absorbers and expands their applications in various scenarios such as wearable electronics and artificial intelligent devices. Oxide electromagnetic wave absorbers (EWAs) have limited absorption bandwidth despite decades of extensive research, due to incomplete identification of influential factors and underlying mechanisms. It here identifies that a negative shift in the d‐band center, a previously overlooked factor, can significantly broaden the absorption bandwidth of oxide EWAs, surpassing other known factors by ≈100%.