Gigahertz Dielectric Polarization of Single-atom Niobium Substituted in Graphitic layers

TL;DR

This study demonstrates that single-atom niobium in graphitic layers exhibits a dielectric resonance at ~16 GHz, revealing the physical limit of electromagnetic response and offering new insights for designing wave absorption materials.

Contribution

It provides experimental and theoretical evidence linking single-atom Nb sites to dielectric resonance, advancing understanding of atomic-scale origins of dielectric properties.

Findings

Single-atom Nb sites cause dielectric resonance at ~16 GHz

Density functional theory confirms the polarization origin

Potential for designing new electromagnetic materials

Abstract

We have synthesized two Nb@C composites with an order of magnitude difference in the density of single-atom niobium substituted into graphitic layers. The concentration and sites of single-atom Nb are identified using aberration-corrected scanning transmission electron microscopy and density functional theory. Comparing the complex permittivity spectra show that the representative dielectric resonance at ~16 GHz originates from the intrinsic polarization of single-atom Nb sites, confirmed by theoretical simulations. The single-atom dielectric resonance represents the physical limit of the electromagnetic response of condensed matter, and thus might open up a new avenue for designing electromagnetic wave absorption materials. Single-atom resonance also has important implications in understanding the correlation between the macroscopic dielectric behaviors and the atomic-scale structural origin.