2008 APS April Meeting and HEDP/HEDLA Meeting
Volume 53, Number 5
Friday–Tuesday, April 11–15, 2008;
St. Louis, Missouri
Session 12HE: Laboratory Studies of Dense Matter I
4:25 PM–5:15 PM,
Sunday, April 13, 2008
Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel),
Room: Promenade F
Sponsoring
Units:
HEDP HEDLA
Chair: Michel Koenig, Ecole Polytechnique
Abstract ID: BAPS.2008.APR.12HE.1
Abstract: 12HE.00001 : X-ray diffraction from shocked materials: investigating solid-solid phase transitions
4:25 PM–4:50 PM
Preview Abstract
Abstract
Author:
Justin Wark
(University of Oxford)
X-ray diffraction on nanosecond and sub-nanosecond time-scales
has proven to be a useful tool in investigating the transient
response of shocked crystals. Perhaps the most notable success
in this area has been the direct observation of the $\alpha -
\epsilon$ transition in laser-shocked single crystals of [001]
iron. [1,2] The information extracted from the diffraction
patterns has been shown to be in remarkable agreement with
multi-million atom molecular dynamics calculations. [3]
Having successfully observed the transition in single crystals
shocked along the principal axis, several further challenges
remain. Amongst these are the exploration of the response of
single crystals to shocks propagating along other
crystallographic directions (where significantly different
response is predicted [4]) the role of pre-existing defects in
the time-scale of the elastic/plastic response of the material,
and any differences that may occur in polycrystalline compared
with single crystal samples.[5] A further challenge will be the
development of rapid compression techniques that take samples to
off-Hugoniot states (for example so-called quasi-isentropic
compression). If such states can be produced in a controlled
way, much could potentially be learnt about the state of certain
planetary cores, including our own.
[1] D.H. Kalantar, J.F. Belak, G.W. Collins, J.D. Colvin, H.M.
Davies, J.H. Eggert, T.C. Germann, J. Hawreliak, B.L. Holian, K.
Kadau, P.S. Lomdahl, H.E. Lorenzana, M.A. Meyers, K. Rosolankova,
M.S. Schneider, J. Sheppard, J.S. Stolken and J.S. Wark, Phys.
Rev. Lett., {\bf 95} 075502, 2005
[2] J. Hawreliak, J.D. Colvin, J.H.Eggert, D. Kalantar, H.E.
Lorenzana, J.S. St\"olken, H.M. Davies, T.C. Germann, B.L.
Holian, K. Kadau, P.S. Lomdahl, A. Higginbotham, K. Rosolankova,
J. Sheppard, and J.S. Wark, Phys. Rev. B, {\bf 74}, 184107, 2006
[3] K. Kadau, Timothy C. Germann, Peter S. Lomdahl, and Brad Lee
Holian, Science, {\bf {296}}, 1681, 2002
[4] Kai Kadau, Timothy C. Germann, Peter S. Lomdahl, and Brad Lee
Holian, Phys. Rev. B, {\bf {72}}, 064120, 2005
[5] K. Kadau, T.C. Germann, P.S. Lomdahl, R.C. Albers, R.C. J.S.
Wark, A. Higginbotham, and B.L. Holian, Phys. Rev. Lett. Phys.
Rev. Lett. {\bf{98}}, 135701 (2007)
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.APR.12HE.1