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Science 11 March 1994:
Vol. 263. no. 5152, pp. 1416 - 1418
DOI: 10.1126/science.263.5152.1416
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Articles

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

E. F. Skelton 1, A. R. Drews 1, M. S. Osofsky 1, S. B. Qadri 1, J. Z. Hu 2, T. A. Vanderah 3, J. L. Peng 4, and R. L. Greene 4

1 Condensed Matter and Radiation Sciences Division and Materials Science and Technology Division, Naval Research Laboratory, Washington, DC 20375-5000, USA.
2 Geophysical Laboratory and Center for High Pressure Research, Carnegie Institution of Washingto, Washington, DC 20015-1305, USA.
3 Chemistry Division, Research Department, Naval Air Warfare Center, Weapons Division, China Lake, CA 93555, USA.
4 Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, MD 20742, USA.

Evidence of structural inhomogeneities in two high—transition-temperature superconductors, YBa2Cu3O7-dgr 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.

Submitted on November 9, 1993
Accepted on January 21, 1994

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Science. ISSN 0036-8075 (print), 1095-9203 (online)