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Phonon anharmonicity in silicon from 100 to 1500 K [electronic resource].

Published:
Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2015.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description:
Article numbers 014,307 : digital, PDF file
Additional Creators:
Oak Ridge National Laboratory, United States. Department of Energy. Office of Basic Energy Sciences, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary:
Inelastic neutron scattering was performed on silicon powder to measure the phonon density of states (DOS) from 100 to 1500 K. The mean fractional energy shifts with temperature of the modes were $\langle$Δεi/εiΔT$\rangle$=−0.07, giving a mean isobaric Grüneisen parameter of +6.95±0.67, which is significantly different from the isothermal parameter of +0.98. These large effects are beyond the predictions from quasiharmonic models using density functional theory or experimental data, demonstrating large effects from phonon anharmonicity. At 1500 K the anharmonicity contributes 0.15kB/atom to the vibrational entropy, compared to 0.03kB/atom from quasiharmonicity. Lastly, excellent agreement was found between the entropy from phonon DOS measurements and the reference NIST-JANAF thermodynamic entropy from calorimetric measurements.
Report Numbers:
E 1.99:1185765
Subject(s):
Note:
Published through SciTech Connect.
01/21/2015.
Physical Review. B, Condensed Matter and Materials Physics 91 1 ISSN 1098-0121 AM
D. S. Kim; Hillary L. Smith; Jennifer L. Niedziela; Chen W. Li; Douglas L. Abernathy; B. Fultz.
Funding Information:
AC05-00OR22725
FG02-03ER46055
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