News Column

Reports from University of Chicago Add New Data to Findings in Science (Nanotwinned diamond with unprecedented hardness and stability)

July 11, 2014

By a News Reporter-Staff News Editor at Science Letter -- Data detailed on Science have been presented. According to news reporting out of Chicago, Illinois, by NewsRx editors, research stated, "Although diamond is the hardest material for cutting tools, poor thermal stability has limited its applications, especially at high temperatures. Simultaneous improvement of the hardness and thermal stability of diamond has long been desirable."

Our news journalists obtained a quote from the research from the University of Chicago, "According to the Hall-Petch effect(1,2), the hardness of diamond can be enhanced by nanostructuring (by means of nanograined and nanotwinned microstructures), as shown in previous studies(3-7). However, for well-sintered nanograined diamonds, the grain sizes are technically limited to 10-30 nm (ref. 3), with degraded thermal stability(4) compared with that of natural diamond. Recent success in synthesizing nanotwinned cubic boron nitride (nt-cBN) with a twin thickness down to similar to 3.8 nm makes it feasible to simultaneously achieve smaller nanosize, ultrahardness and superior thermal stability(5). At present, nanotwinned diamond (nt-diamond) has not been fabricated successfully through direct conversions of various carbon precursors(3,6,7) (such as graphite, amorphous carbon, glassy carbon and C-60). Here we report the direct synthesis of nt-diamond with an average twin thickness of similar to 5 nm, using a precursor of onion carbon nanoparticles at high pressure and high temperature, and the observation of a new monoclinic crystalline form of diamond coexisting with nt-diamond. The pure synthetic bulk nt-diamond material shows unprecedented hardness and thermal stability, with Vickers hardness up to similar to 200 GPa and an in-air oxidization temperature more than 200 degrees C higher than that of natural diamond."

According to the news editors, the research concluded: "The creation of nanotwinned microstructures offers a general pathway for manufacturing new advanced carbon-based materials with exceptional thermal stability and mechanical properties."

For more information on this research see: Nanotwinned diamond with unprecedented hardness and stability. Nature, 2014;510(7504):250-253,370-379. Nature can be contacted at: Nature Publishing Group, Macmillan Building, 4 Crinan St, London N1 9XW, England. (Nature Publishing Group -; Nature -

Our news journalists report that additional information may be obtained by contacting Q. Huang, University Chicago, Center Adv Radiat Sources, Chicago, IL 60439, United States. Additional authors for this research include D.L. Yu, B. Xu, W.T. Hu, Y.M. Ma, Y.B. Wang, Z.S. Zhao, B. Wen, J.L. He, Z.Y. Liu and Y.J. Tian (see also Science).

Keywords for this news article include: Chicago, Science, Illinois, United States, North and Central America

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Source: Science Letter

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