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Diffraction studies of the structural phase transition in the high temperature superconductor YBCO

Khoshnevisan, B 2002, Diffraction studies of the structural phase transition in the high temperature superconductor YBCO , PhD thesis, University of Salford.

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    Abstract

    In-situ x-ray and neutron, diffraction combined with computation modelling have been used to elucidate the details of the structural phase transitions in TBa2Cu3O, 6+, c for )f 0<, X<I. in this study it is found that in the elevated temperature range [200 - 306P C], with increasing oVgen content, the structure changesfrom the weff known tetragonaf (Tet. ) to the orthorhom6ic Il (01I) superfattice phase (under thermodynamical equi(Wrium condition) 9fii; transition is found to 6e first order (a matter of considera6fe controversy) with the eApectedlinear change in the volume action ofeach phase across fir the corresponding two phase mked rcgion (Gi66s phase rure) qfie possi6ifilty of the e*tence of a sta6re entirery Oll phase region at 30OPC arvundxý-, a 7 is perhaps the most nota6fe resuft of this study, which this resuft implies a substantialcorrection on the TBCO's structura[phase diqrnn Trom thefuff anafyses of the data, the possi6ifity of theformation of a superstructure arong the 'c' direction under the aforementioned conditions cannot 6e ruledout -At hýqher temperature [500 - 600*Cj the measurements rer4te to the secondorder Tet. to otthorhom6ic 1 (01) phase transidom qfie interesting issue here is the nature of the twining mirrostructure thatformsJust after the transition. -2'fie computation modeling and peak 6roadening anafyses of the data, reveafs the interference effect on the dif'fracted peak shapes from the thin stripe twinned sampfe at the eady stages of transitionfrom the Tet. to OIphase

    Item Type: Thesis (PhD)
    Contributors: Ross, DK(Supervisor)
    Themes: Subjects outside of the University Themes
    Schools: Colleges and Schools > College of Science & Technology
    Colleges and Schools > College of Science & Technology > School of Computing, Science and Engineering > Materials & Physics Research Centre
    Colleges and Schools > College of Science & Technology > School of Computing, Science and Engineering
    Depositing User: Institutional Repository
    Date Deposited: 22 Sep 2011 16:23
    Last Modified: 17 Feb 2014 14:28
    URI: http://usir.salford.ac.uk/id/eprint/14732

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