Effects of oxygen and strontium vacancies on the superconductivity of single crystals of Bi sub 2 Sr sub 2 minus x CuO sub 6 minus y
- Oak Ridge National Laboratory, Solid State Division, Oak Ridge, Tennessee (US) Oak Ridge National Laboratory, Solid State Division, Oak Ridge, Tennessee 37831-6056
Single crystals of Bi{sub 2}Sr{sub 2{minus}{ital x}}CuO{sub 6{minus}{ital y}} (2201 phase) were grown from CuO-rich melts. The Sr concentration in the crystals was varied from {ital x}=0.1 to 0.5 by adjusting the starting composition of the melt, and the oxygen content of the crystals was reversibly adjusted between {ital y}=0 and 0.5 by an appropriate heat treatment of the crystals in a thermogravimetric system. With decreasing Sr content the superconducting transition temperature, {ital T}{sub {ital c}}, of the crystals decreased rapidly from 9 K to below 4.2 K, and the resistivity in the {ital a}-{ital b} plane changed from metallic (linear in {ital T} from 30 to 300 K) to semiconducting. Reducing the oxygen content in the crystals had a similar effect on the resistivity. Only crystals with close to the maximum oxygen content ({ital y}=0) were superconducting, and removal of oxygen from previously superconducting crystals resulted in a rapid decrease of {ital T}{sub {ital c}} and the eventual loss of superconductivity ({ital T}{sub {ital c}}{lt}4.2 K). A bond-valence sum analysis suggests that oxygen is removed from the Bi{sub 2}O{sub 2} layers.
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5486704
- Journal Information:
- Physical Review (Section) B: Condensed Matter; (USA), Journal Name: Physical Review (Section) B: Condensed Matter; (USA) Vol. 40:10; ISSN PRBMD; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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656100 -- Condensed Matter Physics-- Superconductivity
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
BISMUTH COMPOUNDS
BISMUTH OXIDES
CHALCOGENIDES
CHEMICAL ANALYSIS
COPPER COMPOUNDS
COPPER OXIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CRYSTALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
GRAVIMETRIC ANALYSIS
HEAT TREATMENTS
LOW TEMPERATURE
MAGNETIC PROPERTIES
MAGNETIC SUSCEPTIBILITY
METALS
MONOCRYSTALS
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POINT DEFECTS
QUANTITATIVE CHEMICAL ANALYSIS
STRONTIUM
STRONTIUM COMPOUNDS
STRONTIUM OXIDES
SUPERCONDUCTIVITY
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
ULTRALOW TEMPERATURE
VACANCIES
VERY LOW TEMPERATURE