Reshaping Strategy at Ultrahigh Strain Rates Enables Large-Scale Fabrication of Sharp Nanostructures

Metal nanostructures are the primary component of metamaterials and plasmonics, whereas the high-throughput production of high-resolution nanostructures has always been a challenge. Inspired by the special hardening behavior of nanometals at ultrahigh strain rates, a reshaping strategy of hardened structures for large-scale fabrication of ultra-sharp nanostructures is proposed in this study. At ultrahigh strain rates, the extreme shear deformation-induced solid state amorphization and grain-refining effects of nanometals are first revealed, which provide the required mechanical properties and structural stability for the reshaping of primary structures. The experimental results demonstrate that nanostructures with sub-10 nm resolution are formed using the reshaping strategy. Additionally, the pressure dependence of deformation behavior of the hardened structures in the ultrahigh-strain-rate reshaping process is further explored to guide the nanofabrication process. The results demonstrate that the reshaping strategy at ultrahigh strain rates allows the ultrafine shaping of nanostructures with sub-10 nm resolution on low-pressure and submicron-sized molds, compared with conventional imprinting processes. The generated nanostructures using reshaping process exhibit excellent surface Raman enhancement, enabling high-sensitivity molecular detection. The reshaping strategy provides a novel strategy for the rapid, repeatable, and economical manufacturing of sharp nanostructures, which has broad application prospects in the fields of plasmonics and photonics.