Superconductivity milestones

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

From today s perspective, there are perhaps three major milestones in the search for superconductivity in the organics and the search for high-temperature superconductivity based on these ideas that are worthy of special comment. The first was the discovery of superconductivity in the polymer (SN) by Greene et al. [30] in our laboratory in 1975. This was a remarkable discovery even though the superconductivity occurred only at temperatures well below 1 K. The compound (SN)X is not an organic, of course, as it has no carbon in it nor is the superconductivity believed to be of a nonphonon variety and the band structure is not even truly one-dimensional. Nevertheless, the occurrence of superconductivity in such a polymer provided a tremendous boost to the field and provided positive proof that superconductivity could occur in systems of limited dimensionality. 

The second milestone was the discovery of the first organic superconductor, (TMTSF)2PF6, by Jerome et al. [33] in 1980 with a transition temperature of 0.9 K at a pressure of 12 kbar. This opened the door to the discovery of other charge-transfer superconductors that were found to superconduct at ambient pressure and with higher transition temperatures. Today more than 30 such superconductors have been synthesized and characterized, and the highest transition temperature among this class is now in excess of 12 K. 

Soon after, Bernd Matthias, then with Bell Laboratories, concocted something called niobium-3 tin, which handled superconductivity at 18° K, a milestone of sorts but still enormously cold when one considers the temperature is equal to -427° F. It s difficult not to compare these early efforts—indeed, the current-day ones as well—to those of medieval alchemists searching for the lapis philosopho-rum, the philosopher s stone, that ill-defined soluble substance endowed with the power to change base metals into gold and silver, a stone capable of purging a metal of its impurities so that it could be turned into some precious substance, or one with some useful purpose. It was all a matter of try it and hope. 

Here we have presented a review of selected investigations of the fiillerene species where computational methods were especially productive and have attempted to elucidate prospective directions for fiiture researches. Interestingly, when the interest in fiillerenes seems to decrease, there always appear new topics which maintain the continuing interests of scientists. Such milestones have been the discovery of superconductivity, carbon nanotubes, and recent advances in applications of fiillerene-based materials in nanotechnology. 

---