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Phonon Anharmonicity of Germanium in the Temperature Range 80-880 K

Abstract

Phonon frequency shifts and line widths in germanium have been studied in the temperature range 80 - 880 K by means of thermal neutron spectrometry. The results cannot be described in terms of the quasiharmonic approximation in which phonon frequencies are solely volume dependent. Theoretical calculations are found to be more satisfactory for the Raman frequency than for most other modes. A good account of the observed shifts is given by a proposal due to Barron according to which the relative frequency renormalization of a crystal is proportional to the total harmonic vibrational energy. An analysis of the gradients of measured dispersion relations in the principal symmetry directions at 80 K is presented. It is shown that accidental degeneracies may influence the dispersion
Publication Date:
Jun 15, 1974
Product Type:
Technical Report
Report Number:
AE-491
Resource Relation:
Other Information: 36 refs., 4 figs., 2 tabs.
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; PHONONS; GERMANIUM; TEMPERATURE RANGE 0400-1000 K; THERMAL NEUTRONS; DISPERSION RELATIONS; ANHARMONIC CRYSTALS; MONOCRYSTALS
OSTI ID:
922507
Research Organizations:
AB Atomenergi, Nykoeping (Sweden)
Country of Origin:
Sweden
Language:
English
Other Identifying Numbers:
TRN: SE0808052
Submitting Site:
SWDN
Size:
32 p.
Announcement Date:
Jan 28, 2008

Citation Formats

Nelin, G, and Nilsson, G. Phonon Anharmonicity of Germanium in the Temperature Range 80-880 K. Sweden: N. p., 1974. Web.
Nelin, G, & Nilsson, G. Phonon Anharmonicity of Germanium in the Temperature Range 80-880 K. Sweden.
Nelin, G, and Nilsson, G. 1974. "Phonon Anharmonicity of Germanium in the Temperature Range 80-880 K." Sweden.
@misc{etde_922507,
title = {Phonon Anharmonicity of Germanium in the Temperature Range 80-880 K}
author = {Nelin, G, and Nilsson, G}
abstractNote = {Phonon frequency shifts and line widths in germanium have been studied in the temperature range 80 - 880 K by means of thermal neutron spectrometry. The results cannot be described in terms of the quasiharmonic approximation in which phonon frequencies are solely volume dependent. Theoretical calculations are found to be more satisfactory for the Raman frequency than for most other modes. A good account of the observed shifts is given by a proposal due to Barron according to which the relative frequency renormalization of a crystal is proportional to the total harmonic vibrational energy. An analysis of the gradients of measured dispersion relations in the principal symmetry directions at 80 K is presented. It is shown that accidental degeneracies may influence the dispersion}
place = {Sweden}
year = {1974}
month = {Jun}
}