Effects of dilute alloying on the elastic constants and superconducting energy gap in thallium

dc.contributor.advisorCoon, J. B.
dc.contributor.committeeMemberAllred, John C.
dc.contributor.committeeMemberCollins, R. Eugene
dc.contributor.committeeMemberFitzgerald, Jerry M.
dc.contributor.committeeMemberWalker, Robert H.
dc.creatorCrews, Ronald Milton
dc.date.accessioned2022-01-26T19:00:21Z
dc.date.available2022-01-26T19:00:21Z
dc.date.issued1973
dc.description.abstractVelocity of sound and ultrasonic attenuation measurements have been made on two pure and two doped samples of thallium. One of the pure samples was grown from the melt and the other by strain-anneal and called the unmelted sample. All samples were single crystals and all measurements were made using 15 MHz longitudinal sound pulses. The doped samples contained 1/4 At.% and 1/8 At.% tin as an impurity. The elastic constants appropriate for a longitudinal wave travelling in the c axis direction (C[lowered 33]) have been measured as a function of temperature and impurity. The measured elastic constants vary between 4.8 X 10[raised 11] dynes/cm[raised 2] for the pure unmelted sample at 500K to 6.5 X 10[raised 11] dynes/cm[raised 2] for the 1/4 At.% sample at 4.2K. The elastic constants were calculated from velocity of sound data. A simple band structure model based on the two plane wave approximation is presented and the band structure elastic constants calculated. The model gives relative changes in the elastic constants as a function of temperature and/or impurity. A term representing the electrostatic energy of the crystal is subtracted from the measured elastic constants and the result is compared to values predicted by the model. Band structure elastic constants range from -14.6 X10[raised 11] dynes/cm[raised 2] for the pure unmelted sample at 500K to -15.27 X 10[raised 11] dynes/cm[raised 2] for the 1/4 At.% sample at 4.2K. Finally, the limiting superconducting energy gap is measured as a function of sample impurity. The values obtained are 2[Delta](0) = 4.6K[lowered B]T[lowered c] 4.6 K[lowered B]T[lowered c], 4.0K[lowered B]T[lowered c], and 3.3-3.6K[lowered B]T[lowered c] for the pure melted sample, pure unmelted sample, 1/8 At.% sample, and 1/4 At.% sample respectively. The value of 2[Delta](0) is observed to approach the BCS value of 3.5K[lowered B]T[lowered c] as the doping level is increased.
dc.description.departmentPhysics, Department of
dc.format.digitalOriginreformatted digital
dc.format.mimetypeapplication/pdf
dc.identifier.other13684000
dc.identifier.urihttps://hdl.handle.net/10657/8616
dc.language.isoen
dc.rightsThis item is protected by copyright but is made available here under a claim of fair use (17 U.S.C. §107) for non-profit research and educational purposes. Users of this work assume the responsibility for determining copyright status prior to reusing, publishing, or reproducing this item for purposes other than what is allowed by fair use or other copyright exemptions. Any reuse of this item in excess of fair use or other copyright exemptions requires express permission of the copyright holder.
dc.titleEffects of dilute alloying on the elastic constants and superconducting energy gap in thallium
dc.type.dcmiText
dc.type.genreThesis
thesis.degree.collegeCollege of Arts and Sciences
thesis.degree.departmentPhysics, Department of
thesis.degree.disciplinePhysics
thesis.degree.grantorUniversity of Houston
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy

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