Study of phonon-dislocation interaction in LiF and KCl crystals
Yang, In-Sang
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/23927
Description
Title
Study of phonon-dislocation interaction in LiF and KCl crystals
Author(s)
Yang, In-Sang
Issue Date
1988
Doctoral Committee Chair(s)
Anderson, A.C.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
phonon-dislocation interaction
LiF crystals
KCl crystals
low-temperature thermal conductivity
electrically insulating crystals
lattice thermal conductivity
Language
en
Abstract
A knowledge of dislocations is essential for an understanding of many of the
physical and mechanical properties of crystalline solids. The low-temperature thermal
conductivity of electrically insulating crystals is strongly influenced by dislocations.
Measurement of the lattice thermal conductivity, therefore, provides a useful
tool for the study of phonon-dislocation interaction.
In this thesis, thermal conductivity measurements on plastically deformed LiF
and KCl crystals are discussed. LiF crystals were deformed in such a way that
four slip systems were activated, in a hope to better understand the frequencydependence
of the phonon-dislocation interaction. The results of measurements
on LiF samples support the conclusion that phonons are scattered by dislocations
through dynamic processes, in agreement with previous measurements. Yet, some
fraction of phonons still have long mean-free-paths. Numerical calculations for
the mean-free-paths assuming dynamic scattering processes and including phonon
focusing effects are in fair agreement with experiments made at low temperatures.
Our thermal conductivity measurements on KCl crystals indicate that , at temperatures
below 2.0 K, all phonon modes are strongly scattered by dislocations.
Heat-pulse measurements on KCl samples support this interpretation. 1-irradiation
restores the thermal conductivity of the deformed KCl samples, suggesting that the
phonon-dislocation interaction in KCl also is dynamic in nature. The experimental
results are compared with numerical calculations assuming dynamic scattering
processes. For small dislocation densities, there is reasonable agreement. However,
the agreement is poor for heavily deformed samples.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
