High-pressure offers a potential strategy to the synthesis of nanocrystals (NCs) with new phases, and provide new insights into the phase stability in metastable nanocrystals. Also, high pressure enables new phase transition routines and desirable properties of functional nanocrystals. In this regard, a new structure of B31 phase MnS NCs was successfully synthesized from rocksalt MnS NCs via pressure processing treatment. It is particularly worth noting that the generated new structured MnS NCs were captured as expected by quenching the high-pressure phase to the ambient conditions at room temperature. In addition, the metastable phases of both zinc blende and wurtzite MnS NCs would convert to the stable rock salts MnS under high pressure, and phase transition is reversible. We also observed different phase transition routines in WZ-CuGaS2 NCs, YPO4 NCs and YV1−xPxO4 NCs. Likewise, obtaining improved performance from nanomaterials at high pressure is important over a wide range of applications. We here demonstrate a pressure-induced emission enhancement (PIEE) of oleic acid capped CdSe NCs. First-principles calculations indicate that the increased Hirshfeld charge transferred from the OA molecule to CdSe NCs, accompanied by the disappearance of surface-related trap states at high pressure, is highly responsible for the marked PIEE.

High-pressure nanocrystals: New structures and new optical properties

2019 Spring National Meeting

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