X-ray diffraction anomalies and random intercalation in H-loaded Y-Ba-Cu-O films

• Published in: IEEE transactions on applied superconductivity 2005-06, Vol.15 (2), p.2993-2996
• Main Authors: Ariosa, D., Tsaneva, V.N., Barber, Z.H.
• Format: Article
• Language: English
• Subjects: Applied sciences; Atmosphere; Atmospheric modeling; BRONZES; DEPOSITION; Deviation; Diffraction; Disorder; Electrical engineering. Electrical power engineering; Elongation; Exact sciences and technology; high-temperature superconductors; Hydrogen; Intercalation; LATTICE PARAMETERS; Lattices; Materials; Optical films; Optical reflection; OXIDES; Sputtering; SUPERCONDUCTIVITY; thin films; X RAY DIFFRACTION; X RAYS; x-ray measurements; X-ray scattering; Yttrium barium copper oxide; YTTRIUM OXIDE
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2005.848698

A model has been developed to account for the structural peculiarities observed by X-ray diffraction of hydrogen-loaded Y123 films deposited in an O/sub 2//Ar+H/sub 2/O atmosphere. The model considers the random inter-growth of two very similar structures with slightly different c-axis or, equivalently, the random intercalation of a small spacer in the Y123 matrix causing displacement disorder along the c-axis direction. It quantitatively reproduces both the nonmonotonous deviations of Bragg-peaks and their progressive weakening and broadening for higher diffraction orders. The model offers the possibility to evaluate both the fraction of secondary phase and its c-axis lattice parameter. In the example given, we have been able to identify 28% of intercalated hydrogen bronze H/sub 0.66/[Y123] with 4% elongated c-axis. A simplified procedure for the diagnosis and characterization of random intercalates is extracted from the model. Similar structures observed in other perovskite-based layered oxides are discussed within this framework.