Premium
The inelastic nature of diffuse X‐Ray scattering near the α‐β transition in quartz
Author(s) -
Bauer K. H. W.,
Jagodzinski H.,
Dorner B.,
Grimm H.
Publication year - 1971
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220480143
Subject(s) - phonon , scattering , inelastic scattering , condensed matter physics , anisotropy , inelastic neutron scattering , perpendicular , dispersion (optics) , quasielastic scattering , physics , phonon scattering , materials science , atomic physics , optics , geometry , mathematics
By inelastic scattering of neutrons, the origin of diffuse X‐ray scattering along [ζ00] directions has been investigated. Phonon frequencies are found to be anisotropic and especially low for the [ζ00] direction. Phonons with low frequencies cause enhanced X‐ray scattering in pronounced diffuse streaks. It is probable that this occurs because a soft optic phonon, which drives the α‐β transition and which has been investigated at q = 0 by other authors, becomes soft very predominantly for the [ζ00] direction and forces down an acoustic dispersion branch. The measured phonons are strongly damped at 560 °C (13° below the transition) so that there is a remarkable tail at zero energy transfer, but elastic scattering as expected from static disorder was not observed. The dispersion for deviations from the [ζ00] direction shows a steep valley, which explains the width of the diffuse scattering perpendicular to the [ζ00] direction.