Electrical properties of grain boundaries in Ba sub 1 minus x K sub x BiO sub 3 polycrystalline thin films

Journal Article · Sat Dec 01 04:00:00 EST 1990 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.346968· OSTI ID:6193519

Enomoto, Y; Moriwaki, K; Tanabe, K ^[1]

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1. NTT Applied Electronics Laboratories, Tokai-Mura, Naka-Gun, Ibaraki-Ken 319-11, Japan (JP)

Ba{sub 1}{sub {minus}{ital x}}K{sub {ital x}}BiO{sub 3} polycrystalline thin films are prepared on sapphire substrates by evaporation. In these films, grain boundaries affect the film resistivity in the normal state and {ital I}-{ital V} characteristics in the superconducting state. The temperature dependence of the resistivity is metallic for low-resistivity samples. On the other hand, that for high-resistivity is semiconductive and a bend is observed near 100 K. The {ital I}-{ital V} characteristics show series-connected tunneling Josephson junctions formed along a grain boundary. The ratio between the superconducting energy gap and {ital T}{sub {ital c}} is estimated to be 3.5, equal to that of BaPb{sub 1}{sub {minus}{ital x}}Bi{sub {ital x}}O{sub 3}. Using the resistively shunted junction model and Ambegaokar and Baratoff's theory (Phys. Rev. Lett. {bold 10}, 486 (1963)), the tunneling resistance in a superconducting state is derived from the Josephson critical current densities and the hysteresis of the {ital I}-{ital V} curves. It increases with decreasing temperature at low temperatures and changes the junctions from weak link to tunneling.

• OSTI ID: 6193519
• Journal Information: Journal of Applied Physics; (USA), Journal Name: Journal of Applied Physics; (USA) Vol. 68:11; ISSN 0021-8979; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
& Refractories-- Physical Properties
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM OXIDES
BISMUTH COMPOUNDS
BISMUTH OXIDES
CHALCOGENIDES
COATINGS
CRYSTAL STRUCTURE
CRYSTALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FILMS
GRAIN BOUNDARIES
HIGH-TC SUPERCONDUCTORS
HYSTERESIS
JOSEPHSON JUNCTIONS
JUNCTIONS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POLYCRYSTALS
POTASSIUM COMPOUNDS
POTASSIUM OXIDES
SUPERCONDUCTING FILMS
SUPERCONDUCTING JUNCTIONS
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
VAPOR DEPOSITED COATINGS