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The unusual physical properties and formation conditions attributed to h-, i-, m-, and n-nanodiamond polymorphs has resulted in their receiving much attention in the materials and planetary science literature. Their identification is based on diffraction features that are absent in

The unusual physical properties and formation conditions attributed to h-, i-, m-, and n-nanodiamond polymorphs has resulted in their receiving much attention in the materials and planetary science literature. Their identification is based on diffraction features that are absent in ordinary cubic (c-) diamond (space group: Fd-3m). We show, using ultra-high-resolution transmission electron microscope (HRTEM) images of natural and synthetic nanodiamonds, that the diffraction features attributed to the reported polymorphs are consistent with c-diamond containing abundant defects. Combinations of {113} reflection and <011> rotation twins produce HRTEM images and d-spacings that match those attributed to h-, i-, and m-diamond. The diagnostic features of n-diamond in TEM images can arise from thickness effects of c-diamonds. Our data and interpretations strongly suggest that the reported nanodiamond polymorphs are in fact twinned c-diamond. We also report a new type of twin (<121> rotational), which can give rise to grains with dodecagonal symmetry. Our results show that twins are widespread in diamond nanocrystals. A high density of twins could strongly influence their applications.
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    Title
    • Twinning of cubic diamond explains reported nanodiamond polymorphs
    Date Created
    2015-12-16
    Resource Type
  • Text
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    Identifier
    • Digital object identifier: 10.1038/srep18381
    • Identifier Type
      International standard serial number
      Identifier Value
      2045-2322
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    • The final version of this article, as published in Scientific Reports, can be viewed online at: https://www.nature.com/articles/srep18381

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    Németh, P., Garvie, L. A., & Buseck, P. R. (2015). Twinning of cubic diamond explains reported nanodiamond polymorphs. Scientific Reports, 5(1). doi:10.1038/srep18381

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