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Title:Study of phonon-dislocation interaction in LiF and KCl crystals
Author(s):Yang, In-Sang
Doctoral Committee Chair(s):Anderson, A.C.
Department / Program:Physics
Discipline:Physics
Degree:Ph.D.
Genre:Dissertation
Subject(s):phonon-dislocation interaction
LiF crystals
KCl crystals
low-temperature thermal conductivity
electrically insulating crystals
lattice thermal conductivity
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.
Issue Date:1988
Genre:Dissertation / Thesis
Type:Text
Language:English
URI:http://hdl.handle.net/2142/23927
Rights Information:Copyright 1988 In-Sang Yang
Date Available in IDEALS:2011-05-17
Identifier in Online Catalog:3473897


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