ISSN:
1600-5775
Quelle:
Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Thema:
Geologie und Paläontologie
,
Physik
Notizen:
Temperature dependent X-ray absorption spectra investigation were measured for Ba1−xKxBiO3 (Bi L3-edge) with x = 0.0, 0.25, 0.4, 0.5 and for BaPbO3 (Pb L3 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 BaPbO3). 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.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1107/S0909049501000115
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