The phonon density-of-states of the ceramic superconductors Ba0.6K0.4BiO3, BaPb0.75Bi0.2O3 and BaPb0.75Sb0.25O3 has been measured by the neutron time-of-flight technique to very low energy transfer. Measurements on metallic BaPbO3 and semiconducting BaBiO3 are also reported. Phonon anomalies, associated with high-frequency oxygen breathing modes are observed. The low-frequency region also reveals additional features that vary across the series. The results are consistent with phonon-mediated mechanisms for superconductivity.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering