Secondary and tertiary ordering in non-stoichiometric YBa2Cu3O6+δ

1 September 1992

journal article
research article
Published by Taylor & Francis in Philosophical Magazine Letters

Vol. 66 (3) , 105-114
https://doi.org/10.1080/09500839208229272

Abstract

The kinetics of the secondary and tertiary oxygen ordering in non-stoichiometric YBa₂Cu₃O₆+δ are studied by the computer simulation method. The effect of long-range interactions between O atoms, the Coulomb repulsion and the strain-induced interaction, on the kinetics is investigated in terms of the crystal lattice site diffusion theory. A previous computer simulation by Semenovskaya and Khachaturyan in 1991 predicted the formation of (110) twins of the primary O(I) ordered phase. It is shown in the present work that the nanoscale O(I) twins strongly effect the path of the secondary and tertiary ordering reactions. Secondary ordering within the twins results in the formation of the metastable 2a ₀ × 2a ₀ phase prior to the occurrence of the stable 2a ₀ × a ₀ (or O(II)) ordered phase. Twin boundaries also promote the appearance of the tertiary ordered O’ phase with 2√2a ₀ × 2√2a ₀ × 3a ₀ unit cell.

Keywords

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