The ESRF tests the hardest and least compressive material in the world

September 13, 2005

Nanorods of many materials are proving very successful, and their properties often exceed that of nanotubes, making them excellent candidates for industrial applications. Theoretical calculations predicted that diamond nanorods too would have properties superior to that of carbon nanotubes. But, so far, nobody had been able to actually synthesize diamond nanorods. This is no longer true. A team from the Bayerisches Geoinstitut (Universität Bayreuth) has just reported the synthesis of these aggregated diamond nanorods (ADNR) and their remarkable properties, after having measured them at the ESRF.

The Bayreuth team tested the compressibility and density of this new material. Experiments conducted at the ESRF on the High-Pressure beamline confirmed that the X-ray density of the ADNR material is higher than that of diamond by 0.2 -0.4%; thus making it the densest form of carbon. Subsequent experiments, carried out by loading a diamond anvil cell with both single crystal diamond and ADNR material, in order to directly compare their behaviour under static load, identifies that ADNR is also 11% less compressible than diamond.

The combination of the hardness of the ADNR and its chemical stability makes it a potentially excellent material for machining ferrous materials. "The fact that diamond nanorods are very dense and non-compressible has not only strengthened theoretical predictions, but also given a positive sign that they have very interesting unique properties", explains Leonid Dubrovinsky, one of the authors of the paper.

At the ESRF, researchers tested the "Vickers microhardness", using a diamond indenter. They showed directly that the probe tip failed to make an indentation on the surface of the ADNR. Moreover ADNR can scratch (111) faces of type-IIa natural diamonds, thus ADNR is harder than natural diamond and consequently more resistant against abrasion. The random arrangement of the nanorods most probably gives rise to the increased hardness of ADNR and the reduction in C-C bond length in outer layers of nanorods gives rise to the increased density.

Mechanical testing has also shown that under the same conditions, due to the increased resistance against graphitisation, ADNR material is a much more effective grinding piece than synthetic or natural diamond. This makes it a potentially valuable material in machining ferrous metals and ceramics and, due to its nanocrystalline nature, for precision machining and polishing.

The invention of the team (Natalia Dubrovinskaia, Leonid Dubrovinsky, and Falko Langenhorst) describing the method of synthesis of superhard, wear resistant, and thermally stable aggregated diamond nanorods and their applications has been patented.
(Ref. 1) Natalia Dubrovinskaia, Leonid Dubrovinsky, Wilson Crichton, Falko Langenhorst, Asta Richter. Aggregated diamond nanorods, the densest and least compressible form of carbon. Applied Physics Letters, 22 August 2005.
(Ref. 2) N.A. Dubrovinskaia, L.S. Dubrovinsky, F. Langenhorst. Verfahren zur Herstellung von nanokristallinem stäbchenförmigem Diamant und Anwendungen dafür. Deutsche Patentanmeldung: 10 2004 026 976.9, 2. Juni 2004.

European Synchrotron Radiation Facility

Related Carbon Articles from Brightsurf:

The biggest trees capture the most carbon: Large trees dominate carbon storage in forests
A recent study examining carbon storage in Pacific Northwest forests demonstrated that although large-diameter trees (21 inches) only comprised 3% of total stems, they accounted for 42% of the total aboveground carbon storage.

Carbon storage from the lab
Researchers at the University of Freiburg established the world's largest collection of moss species for the peat industry and science

Carbon-carbon covalent bonds far more flexible than presumed
A Hokkaido University research group has successfully demonstrated that carbon-carbon (C-C) covalent bonds expand and contract flexibly in response to light and heat.

Metal wires of carbon complete toolbox for carbon-based computers
Carbon-based computers have the potential to be a lot faster and much more energy efficient than silicon-based computers, but 2D graphene and carbon nanotubes have proved challenging to turn into the elements needed to construct transistor circuits.

Cascades with carbon dioxide
Carbon dioxide (CO(2)) is not just an undesirable greenhouse gas, it is also an interesting source of raw materials that are valuable and can be recycled sustainably.

Two-dimensional carbon networks
Lithium-ion batteries usually contain graphitic carbons as anode materials. Scientists have investigated the carbonic nanoweb graphdiyne as a novel two-dimensional carbon network for its suitability in battery applications.

Can wood construction transform cities from carbon source to carbon vault?
A new study by researchers and architects at Yale and the Potsdam Institute for Climate Impact Research predicts that a transition to timber-based wood products in the construction of new housing, buildings, and infrastructure would not only offset enormous amounts of carbon emissions related to concrete and steel production -- it could turn the world's cities into a vast carbon sink.

Investigation of oceanic 'black carbon' uncovers mystery in global carbon cycle
An unexpected finding published today in Nature Communications challenges a long-held assumption about the origin of oceanic black coal, and introduces a tantalizing new mystery: If oceanic black carbon is significantly different from the black carbon found in rivers, where did it come from?

First fully rechargeable carbon dioxide battery with carbon neutrality
Researchers at the University of Illinois at Chicago are the first to show that lithium-carbon dioxide batteries can be designed to operate in a fully rechargeable manner, and they have successfully tested a lithium-carbon dioxide battery prototype running up to 500 consecutive cycles of charge/recharge processes.

How and when was carbon distributed in the Earth?
A magma ocean existing during the core formation is thought to have been highly depleted in carbon due to its high-siderophile (iron loving) behavior.

Read More: Carbon News and Carbon Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to