Transport measurement of 32K superconductivity in the Ba-K- Bi-O system.

We have successfully measured the electrical resistance of Ba-K-Bi-O as a function of temperature and magnetic field, and thus confirmed the existence of superconductivity in the compound by transport measurement. The results from dense, black-colored samples prepared from a starting composition with excess potassium ( Ba sub (0.6) K sub (1.2) BiO sub x) indicate T sub c (onset) ~ 32K and T sub c(R=O) ~ 22K with a slightly negative temperature-dependence of normal state resistance. (R(300K)/R(33K) ~ 0.8) The measurement of magnetic moment vs temperature implies that the continuous superconducting phase is most likely to be concentrated near the surface of the bulk sample.