Superconductivity in Compressed Silane - Carnegie/DOE Alliance Center

Contact
To receive regular email updates on CDAC activities, please contact: Steve Gramsch

People Highlights
CDAC high school intern Maneeshika Madduri was a semifinalist in the 2008 Siemens Competition for Math, Science, and Technology with her project on hydrogen complexation studies in crown ethers. Congratulations! ______________ Steven Jacobsen, CDAC Academic Partner from Northwestern (and former Barbara McClintock Postdoctoral Fellow at the Geophysical Laboratory) has been awarded a Packard Fellowship for Science and Engineering. Jacobsen is among 20 scientists selected nationally this year to receive this grant. The funding will support development of Jacobsen’s nano-pulsed GHz-ultrasonic method to study atomic-scale, physical properties of superhard materials targeted for future technological applications ______________ 2008 Carnegie Summer Scholar Symposium The Carnegie Institution held its annual Summer Scholars Research Symposium on Wednesday, August 6th. The ten students participating in the program this year presented the results of their work for the entire Broad Branch Road campus community. The presentations covered a wide range of topics, including mineral physics, organic geochemistry, astrobiology, petrology, seismology and astronomy. More... ______________ Hemley Elected Honoris Causa of the Russian Academy of Sciences Russell Hemley has been elected Honoris Causa Professor for Energetics, Mechanics, Machinery, and Control Systems of the Russian Academy of Sciences (RAS). The academy is the leading scientific body in Russia. Founded in 1724, it is one of the oldest such organizations in the world. The degree is awarded to the most eminent foreign scientists. ______________ CDAC Student Research Support CDAC supports graduate student research and training in the area of high pressure materials science, broadly defined. We accept proposals on a continuing basis from faculty interested in joining the CDAC team as academic partners. Student support consists of salary, tuition/fees and some travel to CDAC facilities for experiments. Please send a one-page statement of research interests and plans to Steve Gramsch, CDAC Coordinator. _________________ High School Summer Research Fellowship A summer research fellowship for a high school student is available at the Geophysical Laboratory. For more information, please follow this link. More People Highlights

People Highlights

CDAC high school intern Maneeshika Madduri was a semifinalist in the 2008 Siemens Competition for Math, Science, and Technology with her project on hydrogen complexation studies in crown ethers. Congratulations! ______________

Steven Jacobsen, CDAC Academic Partner from Northwestern (and former Barbara McClintock Postdoctoral Fellow at the Geophysical Laboratory) has been awarded a Packard Fellowship for Science and Engineering. Jacobsen is among 20 scientists selected nationally this year to receive this grant. The funding will support development of Jacobsen’s nano-pulsed GHz-ultrasonic method to study atomic-scale, physical properties of superhard materials targeted for future technological applications ______________
2008 Carnegie Summer Scholar Symposium

The Carnegie Institution held its annual Summer Scholars Research Symposium on Wednesday, August 6th. The ten students participating in the program this year presented the results of their work for the entire Broad Branch Road campus community. The presentations covered a wide range of topics, including mineral physics, organic geochemistry, astrobiology, petrology, seismology and astronomy.
More...
______________

Hemley Elected Honoris Causa of the Russian Academy of Sciences

Russell Hemley has been elected Honoris Causa Professor for Energetics, Mechanics, Machinery, and Control Systems of the Russian Academy of Sciences (RAS). The academy is the leading scientific body in Russia. Founded in 1724, it is one of the oldest such organizations in the world. The degree is awarded to the most eminent foreign scientists.
______________

CDAC Student Research Support

CDAC supports graduate student research and training in the area of high pressure materials science, broadly defined. We accept proposals on a continuing basis from faculty interested in joining the CDAC team as academic partners. Student support consists of salary, tuition/fees and some travel to CDAC facilities for experiments. Please send a one-page statement of research interests and plans to Steve Gramsch, CDAC Coordinator.
_________________
High School Summer Research Fellowship

A summer research fellowship for a high school student is available at the Geophysical Laboratory. For more information, please follow this link.

More People Highlights

Meetings & Symposia
Workshop on Advances in High-Pressure Science using Synchrotron X-rays NSLS, Brookhaven National Laboratory Upton, NY October 4, 2008 4th Asian Conference on High Pressure Research 4th AHP Seoul, Korea October 14-17, 2008 More Meetings & Symposia

Superconductivity in Compressed Silane

Xiao-Jia Chen and colleagues from the Geophysical Laboratory, in collaboration with scientists from the Chinese University of Hong Kong and South China University of Technology, have predicted from first principles the superconducting properties of the hydrogen-rich molecular compound silane (SiH₄). A gas at ambient conditions, solid silane adopts a structure with the SiH₄ molecules oriented so as to produce layers of hydrogen and silicon atoms. This newly-discovered superconducting phase, which forms at 60GPa, has a structure belonging to the orthorhombic space group Cmca. With this layered structure, compressed SiH₄ at this pressure resembles a silicon-hydrogen alloy, and provides some insight into the long-predicted existence of metallization and superconductivity in dense hydrogen, a problem that has been an important driving force in the development of condensed matter physics and astrophysics for nearly a century.

The research, published in Physical Review Letters [X. J. Chen, et al., Phys. Rev. Lett., 101, 077002 (2008)], suggests that the layered motif observed in the Cmca phase could be essential for superconductivity in other hydrogen-rich compounds.

This theoretical study confirms the experimental finding of pressure-induced metallization in SiH₄, which was reported the team in January 2008 [X. J. Chen, et al., Proc. Nat. Acad. Sci., 105, 20-23 (2008)]. At 60 GPa, silane has a superconducting transition temperature between 20 and 75 K in the layered metallic phase, demonstrating the potential to observe metallization and superconductivity in hydrogen within a potential silicon-hydrogen alloy at higher pressures, but still much lower than would be necessary for solid hydrogen, due to chemical precompression by the silicon. After submission of this work, evidence for superconductivity in metallic silane was reported in the March issue of Science by an international team led by M. I. Eremets, formerly of the Geophysical Laboratory [Eremets et al., Science, 319, 1506-1509 (2008)].


Lashley, J. C., S. M. Shapiro, B. L. Winn, C. P. Opeil, M. E. Manley, A. Atlas, W. Ratcliff, T. Park, R. A. Fisher, B. Mihaila, P. Riseborough, E. K. H. Salje, and J. L. Smith, Observation of a continuous phase transition in a shape-memory alloy, Phys. Rev. Lett, 135703 (2008). Hazen, R. M., D. Papineau, W. Bleeker, R. T. Downs, J. M. Ferry, T. J. McCoy, D. A. Sverjensky, and H. Yang, Mineral evloution, Am. Mineral., 93, 1693-1720 (2008).

Lashley, J. C., S. M. Shapiro, B. L. Winn, C. P. Opeil, M. E. Manley, A. Atlas, W. Ratcliff, T. Park, R. A. Fisher, B. Mihaila, P. Riseborough, E. K. H. Salje, and J. L. Smith, Observation of a continuous phase transition in a shape-memory alloy, Phys. Rev. Lett, 135703 (2008).
Hazen, R. M., D. Papineau, W. Bleeker, R. T. Downs, J. M. Ferry, T. J. McCoy, D. A. Sverjensky, and H. Yang, Mineral evloution, Am. Mineral., 93, 1693-1720 (2008).

More Research Highlights
Anomalous High-Pressure Behavior of Selenium The Surprising Stability of Molecular Nitrogen at High P and T Symposium in Honor of Two NSLS Beamline Scientists Weird Bonds of Oxygen Superconductivity in Compressed Silane Workshop on Understanding Condensed Matter Dynamics at the Microscopic Level CDAC Welcomes Eight New Academic Partners Superconductors Get a Boost from Pressure Novelty in the Noble Metal Nitrides Carnegie Hosts 4th Annual SSAAP Symposium CDAC Papers in Nature, Science, and Physical Review Letters Spins under Pressure More...

More Research Highlights

More...

Welcome
CDAC is an interdisciplinary center headquartered at the Geophysical Laboratory of the Carnegie Institution of Washington. Our goals are to advance and perfect an extensive set of high P-T techniques and unique facilities, to perform key studies on a broad range of important materials in newly-accessible P-T regimes, and to integrate and coordinate static, dynamic and theoretical results for Stewardship Science applications.

Welcome

CDAC is an interdisciplinary center headquartered at the Geophysical Laboratory of the Carnegie Institution of Washington. Our goals are to advance and perfect an extensive set of high P-T techniques and unique facilities, to perform key studies on a broad range of important materials in newly-accessible P-T regimes, and to integrate and coordinate static, dynamic and theoretical results for Stewardship Science applications.