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From Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
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Bureau Seminar, January 28, 2011

High Pressure: A New Dimension in the 21st Century Physical Sciences

Link to streaming video TBA: available 01.28.2011 at 8:55am

Dr. Ho-kwang MaoDr. Ho-kwang Mao
Dr. Ho-kwang Mao
Carnegie Institution of Washington

Carnegie Institution of Washington

Pressure has long been recognized as a fundamental thermodynamic variable but was previously limited by the available pressure vessels and probes. The development of megabar diamond-anvil cells and a battery of associated in-laboratory and synchrotron techniques at the turn of the millennium have opened a vast new window. With the addition of the pressure dimension, we are facing a brave new world with an order of magnitude more materials to be discovered than all that have been explored at ambient pressure.

Pressure drastically and categorically alters all elastic, electronic, magnetic, structural and chemical properties, and pushes materials across conventional barriers between insulators and superconductors, amorphous and crystalline solids, ionic and covalent compounds, vigorously reactive and inert chemicals, etc. In the process, it reveals surprising high-pressure physics and chemistry and create novel materials. Exciting examples of pressure-induced phenomena include intermetallic compound-alloy transitions due to 4f electron delocalization, magnetic collapse in 3d transition elements, complication of “simple electron gas” metals, and synthesis of superhard amorphous carbon allotrope.  They illustrate the high-pressure research as a new dimension in basic science as well as materials applications.

In nature, high pressures are generated inside the Earth and celestial bodies; their interior processes, dynamics and formation are dictated by pressures. Investigations with new-generation high-pressure probes are still at the reconnaissance stage, but they have already shown profound impact on our understanding the geochemistry of the deep mantle, the geodynamics at the core-mantle boundary, the whole Earth water cycle, and the physics and chemistry of planetary ices and gases.

Colloquium Vitae

Ho-kwang Mao was born in China, received his B.S. from the National Taiwan University in Taiwan, and M.S. and Ph.D. from the University of Rochester in USA.  He has been working as a Scientific Staff at the Geophysical Laboratory, Carnegie Institution of Washington from 1968 to present.  His current visiting professorships include James Franck Institute at the University of Chicago, Department of Physics at Jilin University (China), and Advanced Materials Center at Zhejiang University (China).

He has led numerous breakthroughs in experimental high-pressure science. In the 1970-80’s, he advanced the static high-pressure capabilities beyond 300 GPa which was an order of magnitude higher than the previous record, thus greatly expanding the field.  Subsequently, he and his group pioneered the integration of pressure with high-temperature and cryogenic conditions and optical, electromagnetic, and synchrotron x-ray probes that enable a full range of in-situ, high P-T, condensed-matter investigations.  The results have made major impacts on fundamental physics, as well as applications in geophysics and astrophysics. 

Ho-kwang Mao is a Member of the National Academy of Sciences (USA) and Academia Sinica (Taiwan), a Foreign Member of Chinese Academy of Sciences (China) and Royal Society of London (UK), and Fellow of the American Physical Society, American Geophysical Union, Geochemical Society, and European Association for Geochemistry.  Among his prizes and distinction are the Balzan Prize (Balzan Foundation), Inge Lehmann Medal (American Geophysical Union), Gregori Aminoff Prize (Royal Swedish Academy of Sciences), Roebling Medal (Mineralogical Society of America), Arthur L. Day Prize (National Academy of Sciences, USA) and P. W. Bridgman Gold Medal (AIRAPT).

 

 

 
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