Structural disorder in the Pb{sub 2}Sr{sub 2}Y{sub 1{minus}x}Ca{sub x}Cu{sub 3}O{sub 8+{delta}} cuprates
- Swiss Light Source Project, Paul Scherrer Institute, CH-5232Villigen PSI (Switzerland)
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
- Institut de Crystallographie, Universite de Lausanne, CH-1015 Lausanne (Switzerland)
- Laboratorium fuer Festkoerperphysik, Eidgenoessische Technische Hochschule, CH-8093 Zuerich (Switzerland)
High-resolution powder x-ray-diffraction results on Pb{sub 2}Sr{sub 2}Y{sub 1{minus}x}Ca{sub x}Cu{sub 3}O{sub 8+{delta}} are presented. Assuming an orthorhombic cell with Cmmm symmetry, the reflections that index with h and l simultaneous nonzero are observed to be distinctly broader than the other reflections. A model is presented that is able to explain quantitatively and qualitatively the relative widths of the different hkl reflections. The widths of the reflections are found to be independent of the doping level. The model employed is based on anisotropic distributions of the d spacings within the (a,c) plane, corresponding to a fluctuation of the {beta} angle around 90{degree} that occurs as a result of oxygen nonstoichiometry. The distortions may be related to the incommensurable modulation along the b direction in the structurally similar (Bi/Pb){sub 2}Sr{sub 2}(Ca/Y)Cu{sub 2}O{sub 8+{delta}} compounds. At elevated temperatures, a disorder-order phase transition (T{sub do}=240{degree}C) is observed. At temperatures above T{sub do}, the structure relaxes to the undistorted average orthorhombic structure. This order-disorder transition results from oxygen diffusion, which sets in at the transition temperature. {copyright} {ital 1998} {ital The American Physical Society}
- OSTI ID:
- 580046
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 57, Issue 9; Other Information: PBD: Mar 1998
- Country of Publication:
- United States
- Language:
- English
Similar Records
I. Synthesis, modification and characterization of BiSr-CaCuO[sub x] single crystal superconductors. II. Synthesis and characterization of one dimensional rutheniumtetrammine-pyrazine polymers
The 1212 superconductive lead cuprates: HREM study