| Origin of the incommensurate phase of quartz : II. Interpretation of inelastic neutron scattering data (1992) | |||||||||||||||
Abstract | |||||||||||||||
| The results of an inelastic neutron scattering investigation of the low-frequency modes of β quartz, described in the preceding paper [1], are interpreted using two different approaches : i) a phenomenological model directly derived from a Landau-Ginzburg type expansion of the free energy ; this model is only relevant for the long-wavelength part of the phonon spectrum but it allows an easy connection with thermodynamical data ; ii) a microscopic lattice dynamical model, which is an extension of the Grimm-Dorner model ; it is shown that the main properties of the low-frequency phonon spectrum and, in particular, the softening of a Σ2 mode at an incommensurate wave vector close to the zone-center, can be underdtood by analysing the motions of nearly rigid SiO4 tetrahedra. | |||||||||||||||
Details der Publikation | |||||||||||||||
| |||||||||||||||