Neutrons

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Neutrons Coordinator Nancy Ross, VT
2004 COMPRES Annual Meeting
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Goals of COMPRES Neutrons

• Identify and broaden the EAR neutron scattering
  community in the U.S.
• Stimulate and promote the use of neutron
  scattering in the Earth Sciences.
• Support educational activities
• Identify needs of the community, including future
  requirements for instrumentation and sources

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COMPRES Budget for Neutrons

• Year 1 70,000
• Year 2 70,000
• Year 3 70,000
• Virginia Tech
• Webpage(www.crystal.vt.edu/compres)

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Convenors N L Ross, Virginia Polytechnic
Institute and State University J Parise, Stony
Brook
Special Session Applications of Neutron
Scattering in Earth Sciences

• Invited lectures S. Redfern, R. Wenk, H-K Mao,
  B. Winkler, M. Welch
• Poster Session
• Wendy Mao (Univ. Chicago) Hydrogen Storage in
  Clathrate Hydrate.

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Neutrons In solid state Chemistry and the Earth
SciencesToday and tomorrow (March 1216,
2003)Co-chairs A. Wilkinson (Georgia Tech), N.
Ross (Virginia Tech)

• Christopher Holl, Univ. Colorado
• Wendy Mao, Univ. Chicago
• Philip Neuhoff, Univ. Florida
• Kim Tait, Univ. of Arizona
• Charles Martin, SUNY Stony Brook
• Meghan Kamp, Ohio State Univ.
• Yang Ding, Geophysical Laboartory
• Darren Locke, Arizona State Univ.

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COMPRES Neutrons

• Ross Angel (Virginia Tech) High-pressure phase
  transition in lead phosphate(ISIS)
• Peter Chupas (Stony Brook) The local structure
  of amorphous FeS (LANSCE)
• Aaron Celestian (Stony Brook) Origin of ionic
  conductivity in complex structures (LANSCE)
• Julien Breger (Stony Brook) (LANSCE)
• Steve Jacobsen (Geophysical Lab) Hydrogen in
  wadsleyite (ISIS)
• Chris Holl (Univ. Colorado) Hydrogen in
  ringwoodite (ISIS)

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High-pressure Neutron Powder Diffraction at ISIS

• Ferroelastic phase transition
• Paris-Edinburgh cell
• New gasket design that extends hydrostatic
  pressure range to 9 GPa (Marshall and Francis,
  2002 J Appl. Cryst. 35, 122-125)
• 2 samples to 6 GPa, 48 hours

Ross Angel 2004
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Ferroelastic phase transition in lead phosphate

• Neutron powder diffraction showed
• High pressure phase has same symmetry as high
  temperature (R-3m)
• High pressure phase has disordered atoms above
  the phase transition
• This static disorder is suppressed at higher
  pressures
• Model system for perovskites, garnets, feldspars
  and titanites.

Ross Angel 2004
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Size of high P-T mantle minerals
and neutron fluxes are merging . . .
A collaboration between COMPRES
participants Steve Jacobsen (Geophysical
Laboratory) Daniel Frost (Bayerisches
Geoinstitut) Joseph Smyth (University of Colorado)
e.g. hydrous wadsleyite (containing 1 wt H2O)
5000-ton large-volume press in Bayreuth
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Measurements on hydrous wadsleyite and
ringwoodite are being carried out on the SXD
instrument at ISIS
S. Jacobsen 2004
11-bank scintillating ZnS detector array
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mounting the wadsleyite crystal onto the SXD
sample holder at ISIS
Neutron diffraction from single-crystal
wadsleyite!
S. Jacobsen 2004
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Location of hydrogen atoms . . .
H
H
Location of hydrogen even in un-deuterated
samples is possible (from, Two proton positions
in the very strong hydrogen bond of serandite,
NaMn2Si3O8(OH) Jacobsen et al. (2000) Am Min,
85, 745-752). Measured at LANSCE
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COMPRES Neutrons Postdoc

• High-pressure neutron experiments (LANSCE, IPNS,
  ISIS)
• Test/design high P/T cells
• Communicate results to community (conferences,
  website, workshop)
• Help community with experiments

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A High Pressure Diffractometer for the Spallation
Neutron Source

• John B. Parise, Geosciences/Chemistry Center
  for High Pressure Research, State University of
  New York, Stony Brook
• Russell J. Hemley, H.-K Mao, Geophysical
  Laboratory Center for High-Pressure Research,
  Carnegie Institution, Washington, D.C.
• Chris Tulk, Instrument Scientist, Experimental
  Facilities Division, Spallation Neutron Source,
  Oak Ridge National Lab

Fast track on line in 2007
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Financial Assistance

• To carry out neutron scattering experiments
  and/or to participate in workshops and
  conferences on neutron scattering
• See www.crystal.vt.edu for details

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