Major Milestones in Oxide Superconductivity Research

At this point, it may be informative to present a chronological listing of the different discoveries in oxide superconductors reported prior to 1975. In this listing, Table 5, we present the year that the oxide compound was first reported, then the year in which superconductivity was first observed in the system and the group credited for the discovery. Of particular interest is the compound Ba(Pb1 xBix)Os discovered by Sleight at du Pont in 1975. This oxide material adopts the perovskite-type structure and contains no transition metals. 

TABLE 5 Milestones in Binary and Multinary Superconducting Oxides to 1975. 

After the initial attempt to prepare alloy and interstitial superconductors, several ceramists, chemists, and materials scientists joined the group of physicists and metallurgists in search of other superconducting materials. These scientists turned to ternary compounds and to more complex systems. From the mid-60 s to the mid-70 s, several new inorganic materials were found to exhibit the superconducting phenomenon. 

MxMo0S8 (M = Pb or Ln x = 1) Chevrel phases, distorted cubic structure. Isolated MoeSg clusters. (Tc = 15 K for M = Pb) 

MxMoS2 (M = Sr x = 0.2) Intercalation-type compound, layer structure. Tc = 5.6 K for the composition above. 

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