TY - JOUR
T1 - Elasticity of stishovite and acoustic mode softening under high pressure by Brillouin scattering
AU - Jiang, Fuming
AU - Gwanmesia, Gabriel D.
AU - Dyuzheva, Tatiyana I.
AU - Duffy, Thomas S.
N1 - Funding Information:
We thank Yingwei Fei of the Geophysical Laboratory, Carnegie Institution of Washington, for access to his high-pressure multi-anvil apparatus for sample synthesis. V.V. Brazhkin also provided additional stishovite single crystalline samples, fabricated by the N.A. Bendeliani group, that were used to confirm results in specific directions at 1 bar. J. Hu is acknowledged for her assistance with X-ray diffraction measurement at X17C, National Synchrotron Light Source, Brookhaven National Laboratory. This work was support by NSF and C-DAC (Carnegie DOE Alliance Center). Use of X17C at NSLS is supported by DOE (US-DOE contract DE-AC02-10866) and COMPRES (NSF Cooperative Agreement EAR 06-49658).
PY - 2009/2
Y1 - 2009/2
N2 - Brillouin scattering measurements on single-crystal stishovite, a high-pressure polymorph of SiO2, were carried out to 22 GPa. Acoustic velocities in three 30-μm thick crystal platelets of synthetic stishovite were measured in a forward symmetric scattering geometry, and the full set of elastic constants were retrieved to 12 GPa. The measured velocity data were fit to Christoffel's equation, yielding ambient-pressure elastic constants of C11 = 455(1) GPa, C33 = 762(2) GPa, C12 = 199(2) GPa, C13 = 192(2) GPa, C44 = 258(1) GPa, and C66 = 321(1) GPa. The elastic modulus (C11 - C12)/2 was observed to decrease with pressure, indicating acoustic mode softening, consistent with theoretical predications for the behavior of stishovite as it approaches the transition to the CaCl2-type phase. The bounds on the aggregate adiabatic bulk and shear moduli are KS0 = 315(1) GPa, G0 = 240(1) GPa for the Voigt bound, KS0 = 301(1) GPa, G0 = 216(1) GPa for the Reuss bound. Pressure derivatives of aggregate bulk and shear moduli were constrained to be (∂KS/∂P)T0 = 4.34(16) and (∂G/∂P)0 = 0.7(1) for the Reuss bound, and (∂KS/∂P)T0 = 4.0(1) and (∂G/∂P)0 = 1.1(1) for the Voigt-Reuss-Hill (VRH) average, respectively, by fitting the data to Eulerian finite strain equations. The volume compression curve obtained from our Brillouin measurement is in very good agreement with previous compression studies up to 50 GPa.
AB - Brillouin scattering measurements on single-crystal stishovite, a high-pressure polymorph of SiO2, were carried out to 22 GPa. Acoustic velocities in three 30-μm thick crystal platelets of synthetic stishovite were measured in a forward symmetric scattering geometry, and the full set of elastic constants were retrieved to 12 GPa. The measured velocity data were fit to Christoffel's equation, yielding ambient-pressure elastic constants of C11 = 455(1) GPa, C33 = 762(2) GPa, C12 = 199(2) GPa, C13 = 192(2) GPa, C44 = 258(1) GPa, and C66 = 321(1) GPa. The elastic modulus (C11 - C12)/2 was observed to decrease with pressure, indicating acoustic mode softening, consistent with theoretical predications for the behavior of stishovite as it approaches the transition to the CaCl2-type phase. The bounds on the aggregate adiabatic bulk and shear moduli are KS0 = 315(1) GPa, G0 = 240(1) GPa for the Voigt bound, KS0 = 301(1) GPa, G0 = 216(1) GPa for the Reuss bound. Pressure derivatives of aggregate bulk and shear moduli were constrained to be (∂KS/∂P)T0 = 4.34(16) and (∂G/∂P)0 = 0.7(1) for the Reuss bound, and (∂KS/∂P)T0 = 4.0(1) and (∂G/∂P)0 = 1.1(1) for the Voigt-Reuss-Hill (VRH) average, respectively, by fitting the data to Eulerian finite strain equations. The volume compression curve obtained from our Brillouin measurement is in very good agreement with previous compression studies up to 50 GPa.
KW - Elasticity
KW - High-pressure
KW - Silica
KW - Stishovite
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U2 - 10.1016/j.pepi.2008.09.017
DO - 10.1016/j.pepi.2008.09.017
M3 - Article
AN - SCOPUS:57749121864
SN - 0031-9201
VL - 172
SP - 235
EP - 240
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
IS - 3-4
ER -