Large-Scale synthesis, formation mechanism, and enhanced microwave absorption of MgO-C nanochains via polarization loss optimization

Chain-like nanostructured composites have emerged as particularly attractive materials for microwave absorption applications. However, the formation of non-magnetic MgO-C nanochains remains unexplored, the important question of their formation mechanism and how to quantitatively analyze chain-like nanostructure on their microwave absorption performances are far from clear. In this work, MgO-C nanochains were synthesized on a large-scale using metal-organic chemical vapor deposition. The as-synthesized MgO-C nanochains exhibit a unique chain-like microstructure, with C linking individual MgO nanoparticles, which have an average size of ~44 nm. The formation of these nanochains was explained by a proposed mechanism in which MgO dendrites template the dynamics of C deposition, migration, and annealing. MgO-C nanochains exhibit a minimum reflection loss of −53.9 dB in epoxy coating at a thickness of 1.6 mm. Furthermore, we propose an innovative quantitative analysis method to elucidate the microwave absorption mechanism of MgO-C nanochains. By introducing two novel parameters—conduction structural loss (${\epsilon }_{\mathit{cs}}^{\prime \prime }$) and polarization structural loss (${\epsilon }_{\mathit{ps}}^{\prime \prime }$)—it achieves, for the first time, independent quantitative characterization of the influence of material microstructure, addressing the challenge of quantitatively analyzing structural effects in conventional research. The findings reveal that while the chain-like arrangement and three-dimensional network structure of MgO-C nanochains have a limited impact on conduction loss, they enhance interfacial polarization effects, thereby substantially improving polarization loss and multi-reflection absorption performance. This breakthrough not only establishes a new analytical framework for studying the structure-property relationship in absorbers but also provides critical theoretical guidance for the design and optimization of high-performance absorbers.