Abstract
Nanodiamonds (ND) with 1-5 nm dimensions found in meteorites or produced by chemical vapour deposition (CVD) and detonation synthesis are typically described in terms of an sp3-bonded carbon network. However, ultra-high-resolution transmission electron microscopy (uHRTEM) combined with density functional theory (DFT) modelling leads to a different structural interpretation. uHRTEM imaging and nanodiffraction studies of many NDs show six-fold symmetry features whose identity has long been controversial. We also observe diffraction patterns with twelve equally-spaced and symmetrically but unequally arranged reflections, indicating structures with crystallographically-forbidden ideal and distorted twelve-fold symmetry. Structural models based on our DFT calculations lead to an interpretation of these unusual features found throughout the meteoritic and CVD samples in terms of sp3 domains arranged around and coherently bonded to graphitic domains embedded within the diamond matrix. The bonding at the sp2-sp3 interface can explain the unusual features observed in electron energy-loss spectra (EELS) below the onset of the main diamond C1s core-loss edge leading to predictions of low-dimensional conductivity behaviour. The presence of sp2- as well as sp3-bonded regions allows us to interpret previously unexplained features of the Raman spectra and EELS data of ND materials.
Original language | English |
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Article number | 108573 |
Journal | Diamond and Related Materials |
Volume | 119 |
Early online date | 20 Aug 2021 |
DOIs | |
Publication status | Published - 30 Nov 2021 |
Bibliographical note
Funding Information:We are grateful to the staff and for use of the facilities in the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University (USA). P.N. acknowledges financial support from the Hungarian National Research, Development and Innovation Office project NKFIH_KH126502 , the János Bolyai Research Scholarship and the ÚNKP-20-5-PE-7 New National Excellence Program of the Ministry for Innovation and Technology . L.A.J.G. was supported by a NASA Emerging Worlds grant NNX17AE56G. P.F.M., C.A.H. and F.C. received funding from the EU Graphene Flagship under Horizon 2020 Research and Innovation program grant agreement nos. 785219-GrapheneCore2 and 881603-GrapheneCore3 . R.L.S. received a DTP studentship from the UCL department of Chemistry. This work made use of the ARCHER UK National Supercomputing Service ( http://www.archer.ac.uk ) via K.M. and F.C.'s membership of the UK's HEC Materials Chemistry Consortium, which is funded by EPSRC ( EP/L000202 ). K.M. and F.C. gratefully acknowledge HPC resources provided by the UK Materials and Molecular Modelling Hub, which is partially funded by EPSRC ( EP/P020194/1 ), and UCL Grace and Kathleen HPC Facilities and associated support services, in completion of this work. C.J.P. is supported by the EPSRC through Grant No. EP/P022596/1 . The authors acknowledge the European Synchrotron Radiation Facility for provision of synchrotron beamtime at the beamline ID27.
Funding Information:
We are grateful to the staff and for use of the facilities in the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University (USA). P.N. acknowledges financial support from the Hungarian National Research, Development and Innovation Office project NKFIH_KH126502, the J?nos Bolyai Research Scholarship and the ?NKP-20-5-PE-7 New National Excellence Program of the Ministry for Innovation and Technology. L.A.J.G. was supported by a NASA Emerging Worlds grant NNX17AE56G. P.F.M. C.A.H. and F.C. received funding from the EU Graphene Flagship under Horizon 2020 Research and Innovation program grant agreement nos. 785219-GrapheneCore2 and 881603-GrapheneCore3. R.L.S. received a DTP studentship from the UCL department of Chemistry. This work made use of the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk) via K.M. and F.C.'s membership of the UK's HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202). K.M. and F.C. gratefully acknowledge HPC resources provided by the UK Materials and Molecular Modelling Hub, which is partially funded by EPSRC (EP/P020194/1), and UCL Grace and Kathleen HPC Facilities and associated support services, in completion of this work. C.J.P. is supported by the EPSRC through Grant No. EP/P022596/1. The authors acknowledge the European Synchrotron Radiation Facility for provision of synchrotron beamtime at the beamline ID27.
Keywords
- Density functional calculations
- Diaphite
- Nanodiamonds
- Six - and twelve-fold symmetries
- sp- and sp- bonded nanomaterials
- Ultra-high-resolution TEM
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- General Chemistry
- Mechanical Engineering
- Materials Chemistry
- Electrical and Electronic Engineering
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