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(Bi, Pb)‐0212, Superconductivity and Neutron Powder Diffraction
Author(s) -
Seling B.,
Ehmann A.,
KemmlerSack S.,
Linhart J.,
Reimers W.
Publication year - 1997
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(199705)201:1<213::aid-pssb213>3.0.co;2-k
Subject(s) - superconductivity , tetragonal crystal system , powder diffraction , neutron diffraction , materials science , crystallography , volume fraction , transition temperature , condensed matter physics , crystal structure , chemistry , physics , composite material
The crystal structure of (Bi, Pb)‐0212 was refined from neutron powder diffraction data at room temperature and 10 K as tetragonal (space group I/4mmm). The transition to superconductivity is not accompanied by a structural transition. Between the quadratic Cu/O double pyramides a complex charge reservoir is created via the introduction of extra oxygen (O(3) in 2b). Pb is simultaneously present in two atomic positions with CN8 and 9 and considered as Pb 4+ and Pb 2+ . In as‐prepared powdered materials the superconducting volume fraction remains low due to the formation of non‐superconducting grain boundaries. A significant improvement is obtained by use of Ca 2 PbO 4 or CaBi 2 O 4 as flux. The highest T c is situated at 86 K.