A Survey of Superconducting Materials

Abstract

This paper provides an overview of superconducting materials for nonspecialists in this currently very active field of research. Several new classes of materials have emerged in the past two or three years, and some of them offer promise of higher critical temperatures—although new records have not yet been achieved. Several of the hydrides of the transition metals have recently been found to be superconducting, for example, thorium hydride, Th₄H ₁₅, discovered by Satterthwaite and co-workers¹ at the University of Illinois. Hydrogen has also been introduced into palladium by ion implantation; the system becomes superconducting close to 10°K.² Another interesting class of superconductors involves layer compounds, such as tantalum disulfide, which were shown to have very interesting asymmetric superconducting characteristics by Geballe and co-workers at Stanford.³ Recently Matthias and coworkers⁴ have discovered a new ternary group, typified by LiTiS₂, in which critical temperatures as high as 17°K have already been achieved. All these materials are discussed elsewhere in this volume and we shall not elaborate on them here.