Published online by Cambridge University Press: 31 January 2011
X-ray single crystal diffraction data were used for structural refinement of the title compounds with different x (0.15, 0.27, 0.49, and 0.89). Crystals were grown in alumina crucibles using the self-flux method. Aluminum, which originates from the crucibles, substitutes only Cu(1), and thus induces tetragonal symmetry which was observed in all four crystals. The main structural effect of praseodymium is an increased separation of superconducting layers. Substituent concentrations (x and y in the formula) have been refined and compared with the values obtained by EDX (energy dispersive x-ray analysis) in an electron microscope. It was indicated that the refined values of Y: Pr ratio and the oxygen content are more reliable than those obtained by EDX while the refinement is less sensitive for Cu(1): Al ratio, and this value is more uncertain. This is in accordance with the result of wet chemical analysis.