IUCr Congress,
Geneva, 9. 8. 2002, High-Pressure Open Commission Meeting
Experimental Challenges at High Pressure
(Martin Kunz, Nancy Ross, Chairs)
This open commission meeting of the high-pressure commission dealt with the
fundamental quest of high-pressure science to combine various experimental
techniques with high-pressure ancillary equipment. In four different talks
, four different aspects were picked out of this vast field of scientific
and technological development.
Günter Krauss from the ETH in Zürich reported about his first attempts
to investigate diffuse scattering from a single-crystal quasicrystal in a
diamond anvil cell. His data showed that careful operation of a DAC at moderate
pressure combined with appropriate software, can not only resolve the extremely
densely spaced reciprocal space of a quasi crystal, but also quantitatively
extract diffuse scattering of the quasi crystals.
Victor Struzhkins (Geophysical Lab, Washington) presented in his talk yet
another technique, which only recently has been applied to samples at high-pressure,
namely nuclear resonant inelastic scattering. This is a promising exploitation
of the specific properties of synchrotron radiation to extract information
on elastic properties of materials at conditions of high-pressure and high-temperature.
The never ending challenge to create conditions of simultaneous pressure
and temperature in a controlled way was the content of Prof. Yamanaka (Osaka
University) contribution. He presented a heatable diamond anvil cell with
a double staged resistance heater combined with a single crystal diamond
backing plate. This device has been tested and its first results of experiments
on CaO yielded interesting evidence for a possible decomposition of CaSiO3
perovskite at lower mantle conditions.
That the combination of high-pressure devices with neutron radiation is in
a constant stage of development and improvement was impressively demonstrated
by Yann LeGodec (Paris University). Their development not only allow to perform
elastic neutron diffraction at conditions up to 8 GPa and 2000 K, but also
introduced a new, non-invasive neutron radiographic method to accurately
measure temperature.
All in all, the session gave a very nice account on how actively technical
developments are pushed in high-pressure science and how these efforts contribute
to significant and spectacular advances in a variety of scientific disciplines.