Structural Study of Tl2Ba2Can-1CunO4+2n (n=1, 2 and 3) by Powder X-Ray Diffraction
Crystal structures of Tl2Ba2Can-1CunCO4+2n (n = 1, 2 and 3) determined by powder X-ray diffraction were refined using Rietveld analysis. The results of the Rietveld analysis revealed that as n increased the lattice parameter, a, and the interatomic distance Cu(1)-O(2) became shorter, and the Tl-0 and Ba-0 layers showed a tendency to become flatter. Possible substitution of about 10% of the Ca-sites with Tl ions in the 2212 and 2223 phases was also suggested. In our experiments, some samples with similar diffraction patterns showed different Tc–s. In particular, in the Tl-Ba-Cu-O system, a wide range of behaviors varying between non-superconductivity and a Tc of 80K was observed. These difference in Tc–s may be related to substitution effects, modulated structures, and intergrowth structures.
KeywordsInteratomic Distance Rietveld Refinement Substitution Effect Rietveld Analysis Occupation Factor
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