Increased T/sub c/ of bismuth strontium calcium copper oxide superconductor by praseodymium substitution

It is shown that a small substitution of praseodymium for bismuth as in Pr/sub 0.05/Bi/sub 1.95/Sr2CaCu/sub 2.2/O/sub 8.2+//sub 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 Bi2Sr2CaCu/sub 2.2/O/sub 8.2+//sub 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