Size and Purity Control of HPHT Nanodiamonds down to 1 nm

Stepan Stehlik, Marian Varga, Martin Ledinsky, Vit Jirasek, Anna Artemenko, Halyna Kozak, Lukas Ondic, Viera Skakalova, Giacomo Argentero, Timothy Pennycook, Jannik C. Meyer, Antonin Fejfar, Alexander Kromka, Bohuslav Rezek

High-pressure high-temperature (HPHT) nanodiamonds originate from grinding of diamond microcrystals obtained by HPHT synthesis. Here we report on a simple two-step approach to obtain as small as 1.1 nm HPHT nanodiamonds of excellent purity and crystallinity, which are among the smallest artificially prepared nanodiamonds ever shown and characterized. Moreover we provide experimental evidence of diamond stability down to 1 nm. Controlled annealing at 450 °C in air leads to efficient purification from the nondiamond carbon (shells and dots), as evidenced by X-ray photoelectron spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, and scanning transmission electron microscopy. Annealing at 500 °C promotes, besides of purification, also size reduction of nanodiamonds down to ∼1 nm. Comparably short (1 h) centrifugation of the nanodiamonds aqueous colloidal solution ensures separation of the sub-10 nm fraction. Calculations show that an asymmetry of Raman diamond peak of sub-10 nm HPHT nanodiamonds can be well explained by modified phonon confinement model when the actual particle size distribution is taken into account. In contrast, larger Raman peak asymmetry commonly observed in Raman spectra of detonation nanodiamonds is mainly attributed to defects rather than to the phonon confinement. Thus, the obtained characteristics reflect high material quality including nanoscale effects in sub-10 nm HPHT nanodiamonds prepared by the presented method.

Physics of Nanostructured Materials
External organisation(s)
Czech Academy of Sciences, Slovak University of Technology in Bratislava, Czech Technical University in Prague (CTU)
The Journal of Physical Chemistry Part C (Nanomaterials and Interfaces)
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
103018 Materials physics, 210004 Nanomaterials
ASJC Scopus subject areas
Electronic, Optical and Magnetic Materials, Energy(all), Surfaces, Coatings and Films, Physical and Theoretical Chemistry
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