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It is shown that a small substitution of praseodymium for bismuth as in Pr0.05Bi1.95Sr2CaCu2.2O8.2+δ produces a significant increase, 13 K, in the onset temperature, 7 K in the temperature at which the whole specimen is superconducting, and 10 K in the transition-midpoint temperature relative to Bi2Sr2CaCu2.2O8.2+δ. Unfortunately the transition is broadened, 20 K versus 14 K. Doubling the amount of praseodymium substitution causes the occurrence of extraneous phase(s), the effect of which is seen only in the resistance versus temperature data, and does not indicate any additional significant increases in the aforementioned temperatures. [ABSTRACT FROM AUTHOR]

A Raman spectroscopic investigation of specimens of superconducting YBa2Cu3O7-x and of the possible impurity phases YBa2Cu3O6+x (semiconductor), Y2BaCuO5, Y2Cu2O5, BaCuO2, CuO, Y2O3, and BaCO3 indicates that in the range 100–700 cm-1, there are six characteristic lines belonging to the superconductor. At 13 K, these lines are at 150, 338, 441, 507, 590, and 644 cm-1. Comparison of the Raman spectra of the superconductor and the semiconductor indicates a mode stiffening of the pair at 338 and 441 cm-1, but a mode softening of the pair at 507 and 590 cm-1. A factor group analysis leads to a tentative assignment of the Raman and infrared allowed modes. [ABSTRACT FROM AUTHOR]