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Local ordering and charge transfer during room-temperature annealing of quenched tetragonal YBa[sub 2]Cu[sub 3]O[sub 6. 25]

Journal Article · · Physical Review, B: Condensed Matter; (United States)
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  1. Materials Science Division and Science and Technology Center for Superconductivity, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
Neutron powder diffraction was used to study the crystallographic structure of a quenched tetragonal sample of YBa[sub 2]Cu[sub 3]O[sub 6.25] during room-temperature annealing. It is found that the lattice parameters decrease with anneal time. The time dependence of the two lattice parameters is characterized by a single relaxation time [similar to]760 min. Similar relaxation times were recently found for the electrical resistances [ital R][sub [ital a][ital b]], [ital R][sub [ital c]], in tetragonal single crystals of YBa[sub 2]Cu[sub 3]O[sub 6.25]. These results are interpreted in terms of local ordering of the oxygen ions in the basal CuO[sub [ital x]] plane, leading to a charge transfer between the CuO[sub [ital x]] and CuO[sub 2] planes. It is the same effect that leads to the rise in [ital T][sub [ital c]] observed earlier in orthorhombic YBa[sub 2]Cu[sub 3]O[sub 6+[ital x]] ([ital x][gt]0.35). The mechanism of the local ordering and the concept of oxygen ions ordering in a structure with tetragonal symmetry are discussed.
DOE Contract Number:
W-31109-ENG-38
OSTI ID:
7085510
Journal Information:
Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 51:1; ISSN PRBMDO; ISSN 0163-1829
Country of Publication:
United States
Language:
English