Beginning with homogeneous samples of the superconducting phase Y 1 Ba2 Cu3 O7-x (Y123), we examined changes in structure and composition under a strong gravitational field and temperatures remarkably lower than the Y123 melting point. We observed essentially two-layers with different compositions caused by sedimentation of atoms. The layer exposed to the stronger gravitational field is composed of an Y123 phase that has a smaller unit cell volume compared with the initial sample, green, transparent, large single crystals of Y211, and a BaCuO2 phase. Despite the remarkably lower temperature, compositional and structural changes in addition to decomposition were found. The unit cell volume of the Y211 phase was larger than previously indicated by synchrotron x-ray diffraction (XRD) analysis. Refinement of the Y211 structure from the XRD data also showed that these crystals are very perfect due to a very high extinction coefficient 0.7 (9) × 10-6 and symmetrical arrangement compared with the superconducting phase Y123 crystal structure. The study provides evidence that strong gravitational fields can be applied to produce new materials at temperatures much below their melting points.
ASJC Scopus subject areas
- Physics and Astronomy(all)