https://doi.org/10.1140/epjb/e2006-00018-0
Boson peak measurements in neutron-irradiated quartz crystals
1
Department of Physics, Katholieke Universiteit Leuven,
Celestijnenlaan 200D, 3001 Leuven, Belgium
2
A.F. Ioffe Physical Technical Institute,
Politechnicheskaya 26, St.-Petersburg, 194021, Russia
Corresponding author: a christiane.Laermans@fys.kuleuven.ac.be
Received:
23
September
2004
Revised:
11
March
2005
Published online:
31
January
2006
We have measured
the low-frequency Raman scattering in neutron-irradiated quartz
crystals with four different irradiation doses from n/cm2
to
n/cm2 and for 2 different crystallographic directions.
For the used doses the range of density change of the investigated
samples was 12% (the maximum change during amorphization is 14%)
and the amorphous fraction varied from 35% to 100%.
The same measurement was done in neutron-irradiated
amorphous silica with a maximal dose
n/cm2.
In all cases we observed the boson peak in the Raman spectra.
The position of the peak, at
cm-1,
was found to be the same for all the investigated samples
independent of the dose. The shape of the peak for doses
n/cm2 and higher was also found to be the same for 5
investigated samples (including irradiated vitreous silica). We
found that the position of the boson peak in neutron-irradiated quartz
crystals and vitreous silica corresponds to the Ioffe-Regel
crossover frequency for phonons.
The origin of the boson peak in neutron-irradiated quartz and
vitreous silica can be attributed to local soft optic modes, which are
analogous to the soft optic mode that drives the α–
transition in quartz.
PACS: 61.43.Fs – Glasses / 63.50+x – Vibrational states in disordered systems / 78.30.Ly – Disordered solids
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2006