Open AccessLattice softening in superconducting compositions of Ba(K)BiO 3
Author(s) -
Menushenkov A. P.,
Klementev K. V.,
Cortes R.,
Purans J.
Publication year - 2001
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049501000115
Subject(s) - debye–waller factor , superconductivity , anharmonicity , condensed matter physics , softening , materials science , chemistry , physics , diffraction , optics , composite material
Temperature dependent X‐ray absorption spectra investigation were measured for Ba 1− x K x BiO 3 (Bi L 3 ‐edge) with x = 0.0, 0.25, 0.4, 0.5 and for BaPbO 3 (Pb L 3 edge). It was found that at low temperatures the Debye‐Waller factor of the square diagonal Bi‐Bi bond has the maximum value near the insulator‐metal phase transition for the compound with x = 0.25 and x = 0.4. Temperature dependence of Debye‐Waller factor of Bi‐Bi bomnd strongly differs from the Einstein model curve that well describes the harmonic systems (for example BaPbO 3 ). This behaviour is consistent with the strong anharmonicity of the Bi‐O shell due to the double‐well vibration potential reported by us earlier. Presented results point to the essential lattice softening of the superconducting compositions, which is important for the understanding of superconductivity mechanism in perovskite type oxides.