Elasticity Grand Challenge

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Elasticity Grand Challenge

• COMPRES Annual Meeting
• June, 2004

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What is the Elasticity Grand Challenge?

• Collaborative proposal, separate from COMPRES but
  on related theme.
• Participants UIUC, Stony Brook, Geophysical Lab,
  Delaware St., Minnesota Michigan, Colorado,
  Washington, GSECARS-APS

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Activities of EGC Members

• U Illinois Brillouin Scattering, XRD P-V using
  multiple techniques for elasticity, Brillouin
  synchrotron XRD, Nuclear Resonant Scattering
• Stony Brook Delaware State Ultrasonics in the
  multi-anvil press, Sample synthesis
• U Minnesota U Michigan Theory - elasticity,
  phase stability
• Carnegie Inst. Washington GHz ultrasonics

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Objectives of EGC

• Push forward technology
• Extend P-T range of measurements
• New experimental facilities (e.g., Brillouin with
  synchrotron)
• Characterize materials with multiple techniques
• Experiment and theory
• ?, ?, ? (Mg,Fe)2SiO4, perovskites
• Standards for high P-T experiments
  MgO, NaCl, Au, Pt
• Improve precision and accuracy of techniques
  through collaborative efforts

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Objectives of EGC 2

• Advance technology of high pressure experimental
  geophysics
• Improve our understanding of Earths interior
• Achieve this through collaborative efforts

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EGC WorkshopMay 8, 2004, UIUC

• Inform each other on our individual efforts to
  date
• Identify future directions
• Identify fruitful collaborations

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U Illinois Brillouin at the APS

• Community Facility
• Sound velocities and density simultaneously
• Absolute pressure scale
• Installation at 13BM-D at GSECARS, APS
• Set for September 2004

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Illinois Brillouin scattering on polycrystals
Silicate perovskites

• Results on MgSiO3 and Al-MgSiO3 perovskites
  (Sinogeikin et al 2004 Jackson et al. GRL 2004)
• Excellent agreement between single and
  polycrystal MgSiO3
• Samples made for EGC at Stony Brook, used for
  experiments by multiple techniques.

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Illinois P-V EOS of Al-MgSiO3 perovskite by
synchrotron XRD

• Synchrotron XRD in DAC at ESRF (Daniel et al, GRL
  in press)
• KT in excellent agreement with Brillouin of
  Jackson et al. (2004, GRL)
• No softening due to Al
• Multiple techniques same sample give same
  results.

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Stony Brook B. Li, Weidner, Liebermann, Kung,
Liu, Woody

• Deformation Dia (D-Dia) to control stress
• Obtain hydrostatic or controlled stress state
• Velocities by ultrasonics XRD X-ray Imaging
• High P-T measurements

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Stony Brook Velocity and X-ray measurements in
the D-Dia

• NaCl MgO P-T Standards
• X-rays Velocities ? Absolute P scale

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Stony Brook Elasticity of MgSiO3-perovskite

• Velocities to 25 GPa by ultrasonics (B. Li et
  al.)
• Agreement with Brillouin scattering studies by
  Sinogeikin et al. (2004, GRL)

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Delaware State Ultrasonics in the Multi-Anvil
Press and Sample Synthesis for Collaborative Work
(G. Gwanmesia)

• Synthesis of high-quality Pyrope50-Majorite50
  for elasticity studies by ultrasonics and
  Brillouin scattering.
• Measured the elasticity of Py50-Mj50 to 9 GPa and
  1000K by ultrasonics with x-rays. Samples will be
  measured by Brillouin. Good agreement thus far.
• Measured the elasticity of pyrope 1000K at 1
  atm.
• Thermal conductivity and vibrational spectrocopy
  studies on pyrope-majorite garnets (Hofmeister et
  al. Giesting et al. (2004).

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Gigahertz-Ultrasonic Interferometry in the
Diamond-Anvil Cell for single-crystal elasticity
measurements at high P-T
Steve Jacobsen, Russell Hemley, Ho-kwang Mao
(Geophysical Laboratory, Carnegie Institution of
Washington) Hans J. Reichmann (GFZ-Potsdam) Anas
tasia Kantor (Ph.D. student) (Bayerisches
Geoinstitut, Bayreuth) Hartmut Spetzler, Joseph
R. Smyth (CIRES and Dept. Geological Sci.,
University of Colorado)
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Accomplishments made possible through the
Elasticity Grand Challenge
In 2004, the GHz-team added shear-wave
capabilities to the diamond-anvil cell
A P-to-S conversion inside this single-crystal
YAG buffer rod (left) generates shear waves at
0.5-2.0 GHz for transmission into the DAC
(right). These purely-polarized S-waves have
1-10 mm wavelengths for single-crystal elasticity
experiments. (Jacobsen et al. 2004, PNAS 101,
5867)
The GHz-ultrasonic technique is being used to
determine the elastic tensor of opaque minerals
and high-pressure phases
We are working towards interfacing GHz-frequency
ultrasonics to the next generation of
gas-loading, large-volume, gem-anvil cells (e.g.
CVD diamond) for ultrasonics at gt10 GPa
pressures and high temperature.
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GHz-ultrasonic interferometer with in-situ Raman
spectrometer now under construction at the
Geophysical Laboratory for high P-T elasticity
experiments
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Application of GHz-ultrasonics to opaque
iron-oxides
(c44)
Jacobsen et al. (2004) PNAS 101
Reichmann and Jacobsen (2004) Am Min 89, in press
Kantor et al. (2004) submitted
Ultrasonic interferometry in the DAC has been
used to identify pressure-induced soft modes
(c44) in all these oxides, well ahead of known
structural and magnetic phase transitions.
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Application of GHz-ultrasonics to high-pressure
phases
Single-crystal velocities in hydrous ringwoodite
40 mm thick
180 mm
g-(Mg1.7Fe0.22)H0.16SiO4
Jacobsen et al. (2004) PEPI 143-144 Smyth and
Jacobsen, submitted
The aim is to quantify the effects of hydration
(i.e. defects) on the elastic properties of
nominally anhydrous mantle minerals like olivine,
wadsleyite, and ringwoodite. It appears that
hydration of Fo90-ringwoodite to 1 wt H2O has a
similar effect as raising the temperature by
about 600 ºC for P-waves and 1000 ºC for S-waves
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Synthesis of gem-quality mantle phases is central
to the Elasticity Grand Challenge
In collaboration with our COMPRES partners at
Bayerisches Geoinstitut, large single crystals of
various mantle phases for elasticity experiments
have been synthesized using new flux methods
wadsleyite
magnesiowüstite
mm
1 mm
Jacobsen et al. (2004) Am Min 89, in press
Jacobsen et al. (2004) PNAS 101, 5867-5871
silicate perovskite
Fo90-ringwoodite
5000-ton large-volume press in Bayreuth
0.5 mm
Dobson and Jacobsen (2004) Am Min 89, 807-811
Jacobsen et al. (2004) PEPI Vol 143-144, 47-56
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Michigan Theoretical Calculations of Mineral
Properties (L. Stixrude, W. Panero)

• First principles calculations
• Thermodynamics, crystal chemistry, and elasticity
  of hydrogen incorporation in stishovite
• SiAlH substitution predicts several weight
  percent H2O in stishovite at shallow lower mantle
  conditions.
• Predict symmetric H- bonding in the end member
  (ALOOH) at upper mantle conditions.
• Hydrogen softens stishovite, but at deep lower
  mantle conditions hydrogen incorporation may
  stiffen the structure. (Panero and Stixrude,
  EPSL, 221, 2004).

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U Minnesota Theoretical Studies of Stability and
Elasticity (R. Wentzcovitch, T Tsuchiya J
Tsuchiya, K Umemoto)

• MgSiO3 with the Ilmenite, perovskite (Pbnm), and
  Post-perovskite structure
• Akimotoite-perovskite transition in MgSiO3
• CaSiO3 - perovskite
• CaO
• FeSi and core-mantle reactions

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MgSiO3 Perovskite
----- Most abundant constituent ( 70 ) in the
Earths lower mantle ----- Orthorhombic distorted
perovskite structure (Pbnm, Z4) ----- Its
stability is important for understanding deep
mantle (D layer)
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Drastic change in X-ray diffraction pattern
around 125 GPa and 2500 K
UNKNOWN PHASE
Pbnm Perovskite
(M. Murakami and K. Hirose, private communication)
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Ab initio exploration of post-perovskite phase in
MgSiO3
- Reasonable polyhedra type and connectivity
under ultra high pressure -
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Crystal structure of post-perovskite
Lattice system Bace-centered orthorhombic Space
group Cmcm Formula unit Z 4 (4) Lattice
parameters Å a 2.462 (4.286) 120 GPa b
8.053 (4.575) c 6.108 (6.286) Volume
120 GPa Å3 121.1 (123.3) ( )perovskite
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A structure has lower energy than Pbnm perovskite
under high pressure!
Pt 98 GPa
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Structural relation between Pv and Post-pv
Perovskite
Deformation of perovskite under shear strain e6
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Thermodynamic properties
( )Pv
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High-PT phase diagram
Core-mantle boundary
D layer
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Research Emphasis for coming year.

• Increasing P-T range of elasticity measurements
  in all hi-P devices
• Better control of stress state.
• Coordinated experimental-theoretical effort on
  standard materials (MgO, NaCl, Au, Pt, YAG)
• Characterization of hi-P phases by multiple
  techniques complex perovskites (Fe-Al-Mg)SiO3,
  transition-zone phases, hydrous phases

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Activities of EGC Members

• U Illinois Brillouin Scattering, XRD P-V using
  multiple techniques for elasticity, Brillouin
  synchrotron XRD
• Stony Brook Delaware State Ultrasonics in the
  multi-anvil press, Sample synthesis
• U Minnesota U Michigan Theory - elasticity,
  phase stability
• Carnegie Inst. Washington GHz ultrasonics

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Open Discussion Priorities for the Future

• Technical Developments Which technologies are
  ripe for development?
• Samples for characterization by multiple
  techniques
• Is this an important thing to do? (this is not a
  trick question..)
• Olivine polymorphs Si-perovskites? Others?

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Open Discussion Priorities for the Future

• Which standard materials are most important to
  work on?
• What are the most important collaborations for
  advancing technology and understanding Earth
  interior
• How can we coordinate efforts to improve the
  accuracy precision of measurements?