Nanodiamonds with defect centers formed using a doped carbon aerogel
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Nanodiamonds with defect centers formed using a doped carbon aerogel
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he creation of defects in diamond by doping the lattice with foreign atoms can give rise to new properties that can be exploited in a wide range of applications. A team of researchers from the University of Washington, US Naval Research Laboratory, and Pacific Northwest National Laboratory has created various defect centers in nanodiamonds by exposing a doped carbon-based aerogel to high pressures and temperatures in a diamond anvil cell. Using their method, published recently in Scientific Advances (doi:10.1126/sciadv.aau6073), scientists may be able to create new, polyatomic defect centers in nanodiamonds using targeted molecular precursors. Because diamond is hard and inert, doped nanodiamonds could also be used for applications such as tracking the delivery of targeted drugs in the body. Defects in nanodiamond are typically created by replacing carbon atoms in the diamond lattice with silicon or nitrogen atoms. One of the most important and well-studied defects is the negatively charged nitrogen vacancy (NV–) center. “This defect has a long electron spin coherence time at room temperature,
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making it useful for a range of quantum sensing, quantum communication, and quantum computation applications,” says Peter Pauzauskie of the University of Washington, who led the research study. In common with bulk diamond, nanodiamond fabrication requires simultaneous high pressures and temperatures where fabrication methods include chemical vapor deposition, high explosive detonation, or the milling of bulk diamond. Dopants are introduced through these processes or after sysnthesis using ion implantation. The synthesis conditions required for these methods, however, can often lead to significant damage of the nanodiamond crystal lattice because of the energies of the impinging ions, and offer little control over defect site formation. “[This] most recent work incorporates silicon-vacancy defects and trapped argon into nanodiamonds without ion implantation and its associated lattice damage,” says Jagdish Narayan of North Carolina State University, who was not involved in the study. To accomplish this, Pauzauskie’s team incorporated tetraethylorthosilicate (TEOS) molecules into a carbon-based aerogel. During processing, the doped aerogel was also exposed to nitrogen gas and nitrogen-based solvents. The team compressed the doped aerogel in an
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30 nm
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(a) Wide-area high-angle annular dark-field scanning transmission electron microscope image and (b) corresponding scanning transmission electron microscopy energy-dispersive x-ray spectroscopy elemental mapping of argon (red) and silicon (blue) of the recovered tetraethylorthosilicatedoped carbon aerogel. The green squares correspond to the field of view in image (a). Credit: Scientific Advances.
argon-filled diamond anvil cell while being heated by a laser. After being subjected to pressure over 20 GPa and temperatures greater than 2000 K, the aerogel transformed into nanodiamonds with silicon, n
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