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

Abstract
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 (Ba0.6K1.2BiOx) indicate Tc (onset)∼32 K and Tc (R=0)∼22 K with a slightly negative temperature dependence of normal state resistance [R(300 K)/R(33 K)∼0.8]. The strong field dependence of the superconducting transition (500–1000 Oe/K) indicates the likelihood of a relatively low Hc in Ba‐K‐Bi‐O.