Title page for etd-0811103-005822


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URN etd-0811103-005822
Author Ching-Ying Chen
Author's Email Address No Public.
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Department Materials Science and Engineering
Year 2002
Semester 2
Degree Master
Type of Document
Language English
Title An Analysis of Dislocation Loops in Tetragonal BaTiO3 Ceramics
Date of Defense 2003-07-23
Page Count 105
Keyword
  • dislocation loop
  • barium titanate
  • Abstract Dislocation loops in pressureless-sintered undoped BaTiO3 ceramics have been analysed via transmission electron microscopy (TEM). The Burgers vector b = [100] of the loops was initially determined by the contrast analysis of the g•b = 0 criteria combining with the inside-outside contrast method by which the sense of the Burgers vector was concluded. The vacancy nature were determined by adopting the inside-outside contrast analysis using the criteria of (g•b)sg being positive or negative when the loops were imaged under kinematical diffraction conditions of sg ≠ 0. High-resolution imaging of such loops has enabled us to confirm its vacancy nature, consistent with the contrast analysis. Further, the loops’ Burgers vector was determined to be b = 1/2[100] and the loops were therefore negative partial dislocation loops lying in {200} where part of the TiO2-deficiency existed locally in the grains of sintered BaTiO3 ceramics was accommodated by the presence of vacancy loops. It is suggested that the extrinsic defects of both titanium and oxygen vacancies ( and ,) generated by the non-stoichiometry which gave clustered during sintering in air are responsible for the formation of the dislocation loops.
    Advisory Committee
  • Tzu-Chien Hsu - chair
  • Bing-Hwait Hwang - co-chair
  • Hong-Yang Lu - advisor
  • Files
  • etd-0811103-005822.pdf
  • indicate accessible in a year
    Date of Submission 2003-08-11

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