Size-dependent properties of YBa2Cu3O6+x nanopowder



: Paturi P, Raittila J, Huhtinen H, Huhtala VP, Laiho R

Publisher: IOP PUBLISHING LTD

: 2003

Journal of Physics: Condensed Matter

JOURNAL OF PHYSICS-CONDENSED MATTER

: J PHYS-CONDENS MAT

: PII S0953-8984(03)57459-8

: 15

: 12

: 2103

: 2114

: 12

: 0953-8984

DOI: https://doi.org/10.1088/0953-8984/15/12/327


YBa2Cu3O6+x, nanopowder, prepared by the citrate sol-gel method, is segregated by sedimentation in ethanol into three size groups with average particle heights of 0.7, 1.6 and 2.3 nm. The structural properties and composition of the powders, investigated by x-ray diffraction, atomic force microscopy, Auger electron spectroscopy and EPR-spectroscopy, show no clear differences, except the size. According to investigations by magnetometry and by non-resonant microwave absorption the as-prepared powder contains weak links which, however, disappear during the segregation. The magnetic susceptibility of the samples decreases with the decreasing particle size, in agreement with the susceptibility values calculated from the London equations for cylindrical particles smaller than the London penetration depth. In all three size groups the critical temperature of superconductivity is 92 K.



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