Co cluster formation at reduced temperatures in microdoped Y sub 1 minus z Ca sub z Ba sub 2 Cu sub 3 O sub 6+y ( sub 57 Co)

Journal Article · Wed Jul 01 00:00:00 EDT 1992 · Journal of Solid State Chemistry; (United States)

DOI:https://doi.org/10.1016/0022-4596(92)90298-A· OSTI ID:7039107

Smith, M G; Goodenough, J B; Manthiram, A ^[1]; Taylor, R D ^[2]; Oesterreicher, H ^[3]

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1. Univ. of Texas, Austin (United States)
2. Los Alamos National Lab., NM (United States)
3. Univ. of California, San Diego (United States)

An investigation of the Co distribution in microdoped {sup 57}Co (ppm) Y{sub 1{minus}z}Ca{sub z}Ba{sub 2}Cu{sub 3}O{sub 6+y}, z = 0.00 and z = 0.05, for different annealing treatments at reduced temperatures has been made with {sup 57}Co-emission Moessbauer spectroscopy. {sup 57}Co was first diffused into the lattice in oxygen at 650C for 9 hr, 800C for 0.5 hr, and 400C for 3 hr (treatment (O)). This treatment resulted in Co substitution principally on the Cu(1) site in four-, five-, and sixfold coordination (denoted (1)4, (1)5, and (1)6, respectively). The (1)5 and (1)6 coordinations indicate cobalt atoms can cluster even at the ppm level of doping. Samples were next annealed at 700C in N{sub 2} (treatment (N)); they were finally annealed at 350C in O{sub 2} for 4 hr (treatment (NO)). Cobalt atoms migrate to Cu(1) from Cu(2) during treatment (N), and the Co in Cu(1) sites retain at least a (1)4 configuration even though most of the oxygen is lost from the Cu(1)O{sub y} planes. An analysis of the data allows the drawing of a number of conclusions about the oxygen coordination at Co atoms and the Co-atom mobility within the Cu(1)O{sub y} planes as a function of temperature and atmosphere. The authors conclude that suitable heat treatment should allow the formation of flux-pinning centers at Co-atom clusters without serious degradation of T{sub c}, especially for z {gt} 0.05.

• OSTI ID: 7039107
• Journal Information: Journal of Solid State Chemistry; (United States), Vol. 99:1; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
EMISSION SPECTROSCOPY
CALCIUM OXIDES
COBALT OXIDES
COPPER OXIDES
YTTRIUM OXIDES
ANNEALING
COBALT 57
CRYSTAL STRUCTURE
EXPERIMENTAL DATA
MOESSBAUER EFFECT
STOICHIOMETRY
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BETA DECAY RADIOISOTOPES
CALCIUM COMPOUNDS
CHALCOGENIDES
COBALT COMPOUNDS
COBALT ISOTOPES
COPPER COMPOUNDS
DATA
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HEAT TREATMENTS
INFORMATION
INTERMEDIATE MASS NUCLEI
ISOTOPES
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
OXIDES
OXYGEN COMPOUNDS
RADIOISOTOPES
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies