Interface–geometry modulated thermal instability of five-fold twinned Ag nanodecahedra

In situ TEM reveals anisotropic thermal instability dynamics in five-fold twinned Ag nanodecahedra. • Interfacial adhesion of supporting membranes governs the orientation of the instability front. • Geometric thickness at first burst determines burst–gradual or continuous kinetic mode. • Twin boundaries act as both preferential sublimation sites and sublimation barriers to front propagation. Thermal structural evolution of metal nanomaterials is critical to their service reliability. Five-fold twinned decahedral nanoparticles sustain an intrinsic competition between surface energy minimization and strain energy accumulation, yet how intrinsic geometric and extrinsic interfacial constraints jointly govern the thermal instability pathway remains an open question. Using in situ transmission electron microscopy (TEM), we identify two synergistic factors governing the thermal instability dynamics of five-fold twinned Ag nanodecahedra. Interfacial adhesion of the supporting membrane determines the orientation of the instability front: strong adhesion on SiN membranes pins the contact line, aligning the front with the {1 0 0} lateral facets, whereas weak van der Waals interaction on carbon membranes allows the intrinsic strain field to dominate, leaving the front nearly perpendicular to the twin boundaries. The geometric thickness at first burst instability determines the subsequent kinetic mode: the thick particles undergo the burst–gradual mode, while the thin particles follow continuous propagation. Twin boundaries serve as preferential sublimation sites at free-surface intersections while their coherent interfaces constitute barriers to front propagation. These findings provide mechanistic insights into the non-equilibrium thermal evolution of multiply twinned nanostructures, with implications for thermal stability assessment and structural design. Download: Download high-res image (183KB) Download: Download full-size image