X-ray absorption near-edge studies of substitution for Cu in YBa sub 2 (Cu sub 1 minus x M x ) sub 3 O sub 7 minus. delta. ( M =Fe, Co, Ni, and Zn)

Journal Article · Wed Aug 01 00:00:00 EDT 1990 · Physical Review, B: Condensed Matter; (USA)

DOI:https://doi.org/10.1103/PhysRevB.42.2231· OSTI ID:6387183

Yang, C Y; Moodenbaugh, A R; Wang, Y L; Xu, Y; Heald, S M; Welch, D O; Suenaga, M ^[1]; Fischer, D A ^[2]; Penner-Hahn, J E ^[3]

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1. Materials Science Division, Brookhaven National Laboratory, Upton, NY (USA)
2. EXXON PRT, Brookhaven National Laboratory, Upton, NY (USA)
3. Department of Chemistry, University of Michigan, Ann Arbor, MI (USA)

We report x-ray absorption near-edge measurements of YBa{sub 2}(Cu{sub 1{minus}{ital x}M{ital x}}){sub 3}O{sub 7{minus}{delta}} ({ital M}=Fe, Co, Ni, and Zn). Our study is primarily to determine several important material parameters, i.e., the location of dopants, the valence of dopants, structural changes, modifications of electronic densities of states, and the distribution of holes, which are thought to be key factors for understanding mechanisms causing the suppression of superconductivity via metal doping. Our results indicate that each metal substituent has a preference for a specific Cu site or combination of sites. We find that Fe and Co preferentially substitute for the Cu(1) atom at the linear-chain site; Ni resides in both Cu(1) and Cu(2) (the plane site); Zn occupies only the plane position Cu(2). In all cases, the metal-oxygen bond lengths (Fe-O, Co-O, Ni-O, and Zn-O) and valence states of dopant (mainly Fe{sup 3+}, Co{sup 3+}, Ni{sup 2+}, and Zn{sup 2+}) show little dependence on dopant concentration. Metal doping also has little effect on the valence of copper. However, each dopant affects to a different degree the oxygen 2{ital p} states. The changes of the oxygen 2{ital p} states for Fe-, Co-, and Ni-doped samples may be related to a reduction of some oxygen hole states. This reduction is attributed to a redistribution of charge carriers in the chain layer and possibly an inhibition of charge transfer from the chains to the planes. However, Zn substitutions show no observable change in its valence and oxygen hole states, indicating a different mechanism for suppression of superconductivity. Several possible explanations are offered that may elucidate the large suppression of {ital T}{sub {ital c}} in the Zn-doped case.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 6387183
• Journal Information: Physical Review, B: Condensed Matter; (USA), Vol. 42:4; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
ELECTRONIC STRUCTURE
SUPERCONDUCTIVITY
X-RAY SPECTRA
COPPER OXIDES
YTTRIUM OXIDES
ABSORPTION SPECTRA
COBALT ADDITIONS
DOPED MATERIALS
ENERGY-LEVEL DENSITY
FINE STRUCTURE
HOLES
IRON ADDITIONS
NICKEL ADDITIONS
ZINC ADDITIONS
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
BARIUM COMPOUNDS
CHALCOGENIDES
COBALT ALLOYS
COPPER COMPOUNDS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
IRON ALLOYS
MATERIALS
NICKEL ALLOYS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SPECTRA
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
ZINC ALLOYS
360204* - Ceramics
Cermets
& Refractories- Physical Properties