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JAPAN NANONET BULLETIN
-- 24th Issue -- August 5, 2004
Nanotechnology Researchers Network Center of Japan
Ministry of Education, Culture, Sports, Science and Technology (MEXT)
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IN THIS ISSUE
Nanonet Interview:
Akira SAWAOKA, President, Daido Institute of Technology and Project
Leader, Japan Aerospace Exploration Agency (JAXA)
Young Researchers' Introduction:
Takashi MIZOKAWA, Associate Professor, Graduate School of Frontier
Sciences, The University of Tokyo
-- NANO CALENDAR --
For information on nanotechnology related symposiums and conferences
held in the world,
http://www.nanonet.go.jp/english/calendar/
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NANONET INTERVIEW
Inspiration from outer space
--Synthesizing artificial diamonds using shock pressure--
(Issued in Japanese: July 22, 2003)
Akira SAWAOKA, President, Daido Institute of Technology and Project
Leader, Japan Aerospace Exploration Agency (JAXA)
Since ancient times, man has imagined an unknown world when looking up
at the starlit sky. As observational technologies developed, however,
space went from being an imagined world to a scientific one, as well
as a source of discoveries and new ideas.
The universe has also provided a reason for Prof. Sawaoka to become
enthusiastic about researching diamonds when he was studying the
synthesizing of substances by using shock pressure. Hexagonally
structured diamonds made from graphite under high pressure generated
by a meteorite impact were found in a meteor crater. He had another
inspiration from space, specifically Jupiter, the huge planet made of
hydrogen and helium gases. Theoretical physics predicts that hydrogen
is in the metallic state at the core of the planet under several tens
of millions of atmospheric pressure. All substances including diamonds
can be metallized under such high pressure, according to calculations
based on theoretical physics. If it is realized, novel properties may
be discovered.
Prof. Sawaoka says, "When it was said in 1969 that one would win a
Nobel Prize if one could create metal diamonds, I decided to make the
idea come true." His goal was to create metal diamonds by using shock
pressure. All he succeeded in doing in his laboratory, however, was to
create very small diamond particles with 50 to 100 nm in diameter. He
said, "I didn't think these small diamonds could be used in actual
applications." He tried to use them as industrial materials by
consolidating them. Ordinary diamonds are very hard but tend to cleave
when force is applied to them in a certain direction. But carbonade,
a type of natural diamond mined mainly in Brazil, is a tough aggregate
composed of very small diamond crystals and thus it is more suitable
for machine tools. He came up with the idea of consolidating powdered
diamonds with shock pressure to produce golf ball-sized diamond
aggregates. He expected that these could be used as rock drills for
digging oil wells and tunnels. But this was not an easy task. Diamond
powder cannot be consolidated easily and becomes graphite again with
increasing its temperature to consolidate. His attempt failed although
he tried various methods including changing temperature, pressure,
shock pressure and other conditions. Whenever he tried to enlarge the
aggregates to a certain size, they cracked.
But his research on synthesizing diamonds with shock pressure led to
the production of fine diamond powder called "SCM Diamond," made from
graphite. He succeeded in producing diamond powder by using only 30 to
50 kg of explosives, compared with 1,000 to 2,000 kg of explosives
used in other methods. In his method, the volume of explosive used can
be reduced by maintaining high pressure longer through reflecting
shock waves of the explosion. In 2000, half of all diamonds produced
globally with shock pressure were synthesized using his method.
Prof. Sawaoka has been involved in experimental projects of the
National Space Development Agency of Japan (now the Japan Aerospace
Exploration Agency) since 1979. He is now the leader of the agency's
applied research project being conducted in the International Space
Station. He says, "Space development is a history of failures and
delays. It has never moved forward as planned. The development
involves long-term efforts by people involved in it, who come and go.
A senior person who has been participating in space development for
many years and who has much knowledge about the history of this
development is needed." He has also been saying openly that he will
become an astronaut. He says, "I want to be rewarded for working
behind the scenes for many years. My goal is not just a dream; it
will come true." It may not be long before we will see the Japan's
oldest astronaut travel to space.
(Interviewer: Yu Tatsukawa, Cosmopia Inc.)
For more information,
http://www.nanonet.go.jp/english/mailmag/2004/024a.html
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YOUNG RESEARCHERS' INTRODUCTION
Development of photoemission and inverse-photoemission spectroscopy,
electronic structure of transition-metal compounds
(Issued in Japanese: July 22, 2003)
Takashi MIZOKAWA, Associate Professor, Graduate School of Frontier
Sciences, The University of Tokyo
Photoelectrons are emitted from solid surfaces on which ultraviolet or
x-ray light is shone. By measuring the energy and momentum of these
photoelectrons, we can study occupied states of the solid
(photoemission spectroscopy). On the other hand, we can study
unoccupied states of the solid by detecting light emitted from
surfaces of the solid on which electrons are shone (inverse-
photoemission spectroscopy).
We are developing a high-energy-resolution inverse-photoemission
system based on dispersion matching. Using photoemission and inverse-
photoemission spectroscopy, we are studying the electronic structure
of bulk and surface of various solids. In particular, we are
interested in transition-metal compounds that show rich physical
properties such as ferromagnetism, superconductivity, and metal-
insulator transition. In transition-metal compounds, d-electrons with
spin, charge and orbital degrees of freedom are affected by
complicated lattice distortions, and display interesting electric and
magnetic properties.
We are studying the relationship between the physical properties and
electronic structure of transition-metal compounds using experimental
methods such as photoemission and inverse-photoemission spectroscopy
and theoretical methods such as model Hartree-Fock calculation. Here,
an interesting question is which kind of electronic states are
realized when d-electrons are confined at solid surface/interface.
Another interesting question is how confined d-electrons behave when
perturbed by photons. We are trying to answer these questions about
d-electrons in various transition-metal compounds.
For more information,
http://www.nanonet.go.jp/english/mailmag/2004/024b.html
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Nanotechnology Researchers Network Center of Japan
Ministry of Education, Culture, Sports, Science and Technology (MEXT)
Our website: http://www.nanonet.go.jp/english/
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Copyright(c) 2003-2004, Nanotechnology Researchers Network Center of
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