Transition-metal redistribution in GdBa sub 2 Cu sub 3 minus x M x O sub 7 minus. delta. and YBa sub 2 Cu sub 3 minus x M x O sub 7 minus. delta. ( M =Fe, Co, and Ni): Evidence for Gd-Fe(2) magnetic interactions
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
{ital G}dBa{sub 2}Cu{sub 3{minus}{ital x}}O{sub 7{minus}{delta}} and YBa{sub 2}Cu{sub 3{minus}{ital x}}M{sub {ital x}}O{sub 7{minus}{delta}} ({ital M}=Fe, Co, and Ni) high-{ital T}{sub {ital c}} superconductors were prepared by conventional ceramic-processing techniques and characterized by measuring the critical temperature as a function of later quenching from various temperatures. For the Fe-substituted compositions, the {ital T}{sub {ital c}} for the Y-based samples increase while the {ital T}{sub {ital c}} for the Gd-based samples decrease with increasing quench temperatures. Assuming that quenching from elevated temperatures retains the atomic configurations stable at high temperatures, a possible interpretation of these data can be made in terms of a redistribution of Fe from the equilibrium preferred Cu(1) chain sites to the Cu(2) plane sites. A comparison of the data for the Y- and Gd-based superconductors suggests local magnetic interactions between Gd and Fe(2) ions. The data are consistent with superconductivity localized in the Cu-O planes. Gd-based, Co-substituted compositions exhibit behavior similar to Fe-substituted compositions upon quenching treatment. Analysis of Gd-based, Ni-substituted data suggests that two independent processes---thermal disorder and loss of oxygen from the unit cell---operate at high temperatures and determine the final transition-metal distribution. With two independent processes operating at high temperatures, an intrinsic difficulty in determining the transition-metal site-preference energies in the high-{ital T}{sub {ital c}} superconductors is indicated.
- DOE Contract Number:
- FG02-84ER45174
- OSTI ID:
- 5000249
- Journal Information:
- Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 46:1; ISSN 0163-1829; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360207* -- Ceramics
Cermets
& Refractories-- Superconducting Properties-- (1992-)
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
CHALCOGENIDES
COBALT
COPPER COMPOUNDS
COPPER OXIDES
ELEMENTS
GADOLINIUM
HIGH-TC SUPERCONDUCTORS
MAGNETIC PROPERTIES
METALS
NICKEL
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTHS
SUPERCONDUCTORS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TRANSITION TEMPERATURE
YTTRIUM COMPOUNDS
YTTRIUM OXIDES