TY - JOUR
T1 - Single-crystal elastic constants of magnesium difluoride (MgF2) to 7.4 GPa
AU - Zouboulis, Ilias S.
AU - Jiang, Fuming
AU - Wang, Jue
AU - Duffy, Thomas S.
N1 - Funding Information:
This work was supported by the National Science Foundation and the Carnegie-DOE Alliance Center . I.S.Z. acknowledges financial support from the National Technical University of Athens during his sabbatical stay at Princeton University.
Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2014/1
Y1 - 2014/1
N2 - The six independent elastic constants (C11, C12, C13, C33, C44, and C66) of single-crystal MgF2 in the rutile structure have been measured by Brillouin spectroscopy at room temperature from ambient conditions to 7.4 GPa. Measurements were performed on two monocrystals with perpendicular faces, (001) and (100). A quasi-linear fit from finite strain theory was applied to the experimental data revealing the pressure dependence of the six elastic constants of MgF2. The shear modulus CS=1/2(C11-C 12), and the aggregate shear (Voigt-Reuss-Hill) modulus G show a softening with increasing pressure, indicating the approach of the rutile-to-CaCl2-type structural phase transition at P∼9 GPa. The adiabatic bulk modulus (Reuss average) and its pressure derivative have been determined: K0S=105.1±0.3 GPa, (∂K0S/∂P) T=4.14±0.05. The pressure-volume equation of state of MgF 2 was computed self-consistently from the Brillouin data. Our results are in good agreement with X-ray diffraction data. As the phase transition is approached, MgF2 becomes strongly anisotropic and develops partially auxetic behavior (a negative Poisson's ratio in certain directions).
AB - The six independent elastic constants (C11, C12, C13, C33, C44, and C66) of single-crystal MgF2 in the rutile structure have been measured by Brillouin spectroscopy at room temperature from ambient conditions to 7.4 GPa. Measurements were performed on two monocrystals with perpendicular faces, (001) and (100). A quasi-linear fit from finite strain theory was applied to the experimental data revealing the pressure dependence of the six elastic constants of MgF2. The shear modulus CS=1/2(C11-C 12), and the aggregate shear (Voigt-Reuss-Hill) modulus G show a softening with increasing pressure, indicating the approach of the rutile-to-CaCl2-type structural phase transition at P∼9 GPa. The adiabatic bulk modulus (Reuss average) and its pressure derivative have been determined: K0S=105.1±0.3 GPa, (∂K0S/∂P) T=4.14±0.05. The pressure-volume equation of state of MgF 2 was computed self-consistently from the Brillouin data. Our results are in good agreement with X-ray diffraction data. As the phase transition is approached, MgF2 becomes strongly anisotropic and develops partially auxetic behavior (a negative Poisson's ratio in certain directions).
KW - C. High pressure
KW - D. Electrical properties
KW - D. Equations-of-state
KW - D. Phase transition
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U2 - 10.1016/j.jpcs.2013.09.014
DO - 10.1016/j.jpcs.2013.09.014
M3 - Article
AN - SCOPUS:84886724930
SN - 0022-3697
VL - 75
SP - 136
EP - 141
JO - Journal of Physics and Chemistry of Solids
JF - Journal of Physics and Chemistry of Solids
IS - 1
ER -