Direct Observation of Microscopic Inhomogeneities with Energy-Dispersive Diffraction of Synchrotron-Produced X-rays

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Science  11 Mar 1994:
Vol. 263, Issue 5152, pp. 1416-1418
DOI: 10.1126/science.263.5152.1416


Evidence of structural inhomogeneities in two high—transition-temperature superconductors, YBa2Cu3O7-δ and Nd2-xCexCuO4-y, is presented. When samples were illuminated by highly collimated x-rays produced on a synchrotron wiggler, small changes in the lattice were detected over a spatial scale of 10 micrometers. These changes are interpreted as evidence of variations in the oxygen content in one case and in the cerium content in the other; both affect the superconducting properties. The existence of such structural inhomogeneities brings into question whether exotic experimental results obtained from superconducting materials with high transition temperatures actually reflect intrinsic properties.