The lattice parameter of Ba0.6K0.4BiO3, which is a well-studied conventional superconductor, was measured by the X-ray Rietveld method between 10 K and room temperature. A very small change in the lattice parameter could be detected in the superconducting phase. The change could be attributed to a spontaneous strain generated in the superconducting phase by the coupling between a superconducting order parameter and the strain. It was concluded that this coupling phenomenon is common to all superconductors.
- Crystal structure and symmetry
- Phase transitions