Direct nanoimprinting provides a simple and high-throughput route forproducing uniform nanopatterns at great precision and at low costs. However,applying this technique to crystalline metals has been considered as impossibledue to intrinsic limitation from grain size effect. Here we demonstrate directsuperplastic nanoimprinting (SPNI) of crystalline metals well below theirmelting temperatures (Tm), generating ordered nanowire arrays with aspect ratioup to ~2000. Our investigations of replicating metal hierarchicalnanostructures show the capability of imprinting features as small as 8 nm, farsmaller than the grain size of bulk metals. Most surprisingly, the preparedmetal hierarchical nanostructures were found possessing perfect monocrystallinestructures. These findings indicate that nanoimprinting of crystalline metalsbelow Tm might be from lattice diffusion. SPNI as a one-step and highlycontrolled high-throughput fabrication method, could facilitate theapplications of metal nanostructures in bio-sensing, diagnostic imaging,catalysis, food industry and environmental conservation.
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