Distorted local environment around Zn on Cu(2) sites in YBa[sub 2]Cu[sub 3]O[sub 7]: An x-ray-absorption study

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.48.1266· OSTI ID:5429634

Bridges, F; Li, G ^[1]; Boyce, J B ^[2]; Claeson, T ^[3]

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1. Physics Department, University of California, Santa Cruz, Santa Cruz, California 95064 (United States)
2. Xerox Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, California 94304 (United States)
3. Chalmers Institute of Technology, Gothenburg (Sweden)

The substitution of Zn for Cu in YBa[sub 2]Cu[sub 3]O[sub 7[minus][delta]] (YBCO) causes a surprisingly large suppression of the superconducting transition temperature. However, there has been some controversy as to whether Zn replaces Cu in the CuO[sub 2] plane sites, Cu(2), in the CuO chain sites, Cu(1), or in both sites. We present x-ray-absorption fine-structure (XAFS) data for samples from four different sources with several concentrations of Zn. Our data indicate that, in many samples, much of the Zn resides in ZnO (or ZnO-like) clusters; for some of these samples we have estimated the amount of ZnO present from our XAFS data. One group of samples showed no evidence for ZnO-like precipitates, indicating that in this case, most of the Zn is in solution, or in a YBCO-like environment. For this data Zn has about five nearest O neighbors at approximately equal distances of 2.03 A. Furthermore, the distances to the Zn further neighbors are well defined, with little broadening. Our analysis indicates that Zn primarily occupies the Cu(2) plane sites, in contrast to Co and Fe, which reside in the chain sites. However, its local environment is significantly distorted; the Zn(2) atoms are displaced along the [ital c] axis toward the Cu(1) sites by about 0.2 A. It is not clear whether the Zn atoms are uniformly distributed, or whether the observed distortion signifies some type of clustering; however, the sharpness of the transition supports a uniform distribution. Our work illustrates further the general tendency of YBa[sub 2]Cu[sub 3]O[sub 7] to distort easily when slightly modified.

• OSTI ID: 5429634
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 48:2; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
CRYSTAL STRUCTURE
COPPER OXIDES
HIGH-TC SUPERCONDUCTORS
YTTRIUM OXIDES
TRANSITION TEMPERATURE
ZINC ADDITIONS
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
ZINC ALLOYS
360207* - Ceramics
Cermets
& Refractories- Superconducting Properties- (1992-)
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies