La sub 2 MO sub 4+. delta. (M = Cu, Ni, Co): Phase separation and superconductivity resulting from excess oxygen defects

Conference · Sun Jan 01 00:00:00 EST 1989

OSTI ID:5524931

Dabrowski, B; Jorgensen, J D; Hinks, D G; Pei, Shiyou; Richards, D R; Vandervoort, K G; Crabtree, G W; Vanfleet, H B; Decker, D L ^[1]

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1. Argonne National Lab., IL (USA)

The structural, superconducting and normal-state properties of La{sub 2}MO{sub 4+{delta}} (M = Cu, Ni, Co) were studied by neutron powder diffraction, thermogravimetric analysis and resistivity measurements. La{sub 2}CuO{sub 4+{delta}} was found to undergo phase separation near room temperature into antiferromagnetic La{sub 2}CuO{sub 4} and superconducting La{sub 2}CuO{sub 4.08}. Single-phase, metallic, superconducting La{sub 2}CuO{sub 4.08} was prepared under 25 kbar of O{sub 2} at 500{degree}C. The excess oxygen present as O{sup =} ions provides a doping mechanism analogous to alkaline-earth metal ion substitution. La{sub 2}NiO{sub 4+{delta}} and La{sub 2}CoO{sub 4+{delta}} undergo a similar phase separation for 0.02<{delta}<0.12 and 0<{delta}<0.16, respectively. The structure of the interstitial excess oxygen defect was determined for a single-phase La{sub 2}NiO{sub 4.18} sample. A different excess oxygen defect forms for material with 0{le}{delta}{le}0.02. All stoichiometric ({delta}=0) compounds have the same Cmca orthorhombic structure and are semiconducting and antiferromagnetic. 17 refs., 6 figs.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: DOE/ER; National Science Foundation (NSF)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5524931
• Report Number(s): CONF-890971-4; ON: DE90001988; CNN: STC-8809854
• Resource Relation: Conference: Conference on superconductivity and applications, Buffalo, NY (USA), 19-21 Sep 1989
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COBALT OXIDES
SUPERCONDUCTIVITY
COPPER OXIDES
LANTHANUM COMPOUNDS
NICKEL OXIDES
CHARGE TRANSPORT
CRYSTAL STRUCTURE
DEFECTS
ELECTRIC CONDUCTIVITY
NEUTRON DIFFRACTION
OXYGEN
PHASE STUDIES
STOICHIOMETRY
TEMPERATURE DEPENDENCE
CHALCOGENIDES
COBALT COMPOUNDS
COHERENT SCATTERING
COPPER COMPOUNDS
DIFFRACTION
ELECTRICAL PROPERTIES
ELEMENTS
NICKEL COMPOUNDS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RARE EARTH COMPOUNDS
SCATTERING
TRANSITION ELEMENT COMPOUNDS
360204* - Ceramics
Cermets
&amp; Refractories- Physical Properties
360202 - Ceramics
Cermets
&amp; Refractories- Structure &amp; Phase Studies