TY - RPRT TI - Phonon Anharmonicity of Germanium in the Temperature Range 80-880 K AB - 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 AU - "Nelin, G" AU - "Nilsson, G" KW - "75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY" KW - "PHONONS" KW - "GERMANIUM" KW - "TEMPERATURE RANGE 0400-1000 K" KW - "THERMAL NEUTRONS" KW - "DISPERSION RELATIONS" KW - "ANHARMONIC CRYSTALS" KW - "MONOCRYSTALS" DO - https://doi.org/ UR - https://www.osti.gov/etdeweb/servlets/purl/922507 PB - CY - Sweden PY - 1974 DA - 1974-06-15 LA - English J2 - [] VL - C1 - AB Atomenergi, Nykoeping (Sweden) C2 - C3 - AE-491 C4 - C5 - L3 - Other Information: 36 refs., 4 figs., 2 tabs. ER -