Structure and formation of twins in the orthorhombic YBa2Cu3O7-x

Mehmet Sarikaya, Ryoichi Kikuchi, Ilhan A. Aksay

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Structure and formation of twins in the orthorhombic phase of YBa2Cu3O7-x samples, exhibiting bulk superconductivity at 90 K, are studied by transmission electron microscopy and modeling. Twinned domains with {110} twin boundaries form with separation λ which is dictated by energetic and geometrical requirements. Both of these requirements are related to Δa=b-a, where b and a are lattice parameters of the orthorhombic phase. Geometrical requirement leads to the estimate that the stable values of λ are integer multiples of d=ab/(√2Δa). In some samples λ's are regular, in others not. Deviation of λ from theoretically expected stable separations is interpreted as due to local variation of oxygen ordering and/or local elastic strain. The twin boundary has a structure different from the bulk orthorhombic phase and electron micrographs suggest that it has a width of 30-50 Å. In bulk samples twinned domains can be present at different stages of the growth process. These substructural variations suggest that samples are at metastable equilibrium and are consistent with samples being in the superconducting glassy state.

Original languageEnglish (US)
Pages (from-to)161-170
Number of pages10
JournalPhysica C: Superconductivity and its applications
Issue number2
StatePublished - Apr 1 1988

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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