MATERIALS SEMINAR
Friday, November 22, 2013
622 Min Kao Building
2:30 – 3:20
Ho-Kwang (David) MAO
Carnegie Institution of Washington
High Pressure: A New
Dimension in the 21st
Century Physical Sciences
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 newgeneration 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.
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 highpressure 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).
Contact Kurt Sickfus – kurt@utk.edu