High pressure induces dramatic changes and novel phenomena in materials that are usually not preservable after pressure release. We proposed an approach to preserving high-pressure materials using nanostructured diamond capsules (NDCs)[1]. As a demonstration, we pressurized argon into enclosed nano-pores of glassy carbon precursors, then converted the glassy carbon into nanocrystalline diamond by heating, and eventually synthesized NDCs capable of permanently preserving high-pressure argon even after release back to ambient conditions (see Fig.1). With NDCs, various vacuum-based diagnostic probes, including electron microscopy, can be employed to characterize high-pressure argon directly. Synchrotron X-ray and high-resolution transmission electron microscopy-based diagnostic techniques show nm-sized argon crystals at ~22.0 GPa embedded in the nanocrystalline diamond matrix. Moreover, the preserved pressure of the argon sample inside NDCs can be readily tuned by controlling the NDCs synthesis pressure. To test the general applicability of the NDC process, we show high-pressure neon can also be trapped in NDCs as well. In principle, the NDC strategy can be applied to liquid and solid samples as well. Therefore, it could provide a unique approach to retaining high-pressure materials and their novel properties for ambient applications.

diamond,high temperature and high pressure,electron microscope