Publication
Title
2√2 $a_{p}$ x 2√ $a_{p}$ phase in superconducting ceramics
Author
Abstract
 By means of electron diffraction the 2 root 2 a(p) x 2 root 2 a(p) phase, well-known in YBa2Cu3O7-delta was observed in two other perovskite-based materials (Y0.75Ce0.25)(2)(Sr0.85Y0.15)(2)AlCU2O9 and Bi1.8Pb0.4Sr2Ca2Cu3O10+x. Highly correlated ordering is observed in the ab-plane, the correlation along the c-direction being weak. The plane group of the superstructure symmetry elements was determined on the basis of observed reflection conditions in diffraction patterns. Our results unambiguously rule out oxygen ordering as a possible origin of the superstructure. Experimental evidence points out that the superstructure is associated with the CuO2 layers, that are the only structural elements common to the three compounds studied. A model is proposed where the CuO2 sheet is displacively modulated. Experimental evidence suggests a correlation between adjacent CuO2 sheets. Comparison of simulated and experimental [001] zone diffraction patterns strongly supports our model.
Language
English
Source (journal)
Physica: C: superconductivity. - Amsterdam
Publication
Amsterdam : 1995
ISSN
0921-4534
Volume/pages
248:3/4(1995), p. 317-327
ISI
A1995RJ45000012
Full text (Publisher's DOI)
Full text (publisher's version - intranet only)
UAntwerpen
 Faculty/Department Research group Publication type Subject Affiliation Publications with a UAntwerp address