It is hard to imagine that graphite, the soft "lead" of pencils, can be transformed into a form that competes in strength with its molecular cousin diamond. Using a diamond anvil to produce extreme pressures and the ultra-brilliant X-ray beams at the Advanced Photon Source in Illinois, scientists with the High-Pressure Collaborative Access Team (HPCAT)* have surmounted experimental obstacles to probe the changes that graphite undergoes to produce this unique, super-hard substance. The study is reported in the October 17, issue of Science.
"Researchers have speculated for years on the extreme conditions that might change the molecular structure of graphite into a super-hard form that rivals diamond," said Wendy Mao, the studys lead author from the Carnegie Institutions Geophysical Laboratory in Washington, D.C., and the University of Chicago. "This experiment is the first to determine quantitatively how the bonding in graphite changes under high-pressure conditions. Conventional methods limited our observations to surface studies of the material," she stated. "Now, with the super high-intensity X-rays of the Argonne facility and with our teams technology to focus the entire beam to a small spot, weve been able to look at the material in the diamond-anvil cell while under high pressure. Weve overcome the obstacles of the past," she concluded.
Graphite and diamond are both made of carbon. The geometric arrangement and spacing of the carbon atoms is what makes the materials differ in appearance and strength. The atoms in graphite are arranged in layers that are widely spaced. The atoms in diamond, on the other hand, are tightly linked producing a strongly bonded structure. The HPCAT scientists subjected graphite to pressures that are equivalent to 170,000 times the pressure at sea level ( 17 gigapascals). "We were able to see how the structure changed at the atomic level when the graphite was squeezed into the super-hard form," remarked co-author Dave Mao of Carnegies Geophysical Laboratory. "The graphite that resulted from our experiment was so hard that when we released the pressure we saw that it had actually cracked the diamond anvil."
Wendy Mao | EurekAlert!
Hidden talents: Converting heat into electricity with pencil and paper
20.02.2018 | Helmholtz-Zentrum Berlin für Materialien und Energie
Contacting the molecular world through graphene nanoribbons
19.02.2018 | Elhuyar Fundazioa
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
20.02.2018 | Life Sciences
20.02.2018 | Medical Engineering
20.02.2018 | Physics and Astronomy