Existence of Superconducting States Above 30 K in Sr-V-O Systems Doped with Various Elements

Abstract

Electrical properties of the Sr-V-O systems doped with Tl, La, and Ce were extensively studied. The Sr-V-O system was prepared in the reduced form, for example, SrVO 3-δ , and was doped with Tl. In the Tl-Sr-V-O system a sharp drop in the resistivity was observed at around 30 and 130 K in several samples. A diamagnetic signal was clearly observed below 30 K. The superconducting states of the Tl-Sr-V-O system are found to be metastable in the ambient atmosphere. It is suggested that there are at least two superconducting phases or crystal structures giving rise to the T c 's. The highest onset temperature observed for the sharp resistivity drop was 160 K.