Having used ultrahigh pressures and critically low temperatures, scientists at the Institute of High Pressures of the USSR Academy of Sciences have managed to cffcct such a unique transformation as converting a sulphur insulator into a superconductor...
Superconductivity, at which a conductor completely lacks resistance to elcctric currcnt, was discovered more than 70 years ago. This phenomenon occurs at temperatures around -273°C.
Present-day clcctronic, clcctrotcchnical apparatuses, instruments and machines have been developed, operating on superconductors under
conditions of low temperatures. Among Uicm are radio-receiving devices for dctccting weak signals arriving from the depths of outer space, highly efficient powerful, and yet small, current generators, transformers and cables.
The equipment that uses superconductors is expensive and is not available for users at large. That is why scientists are looking for materials which would bccomc superconducting at a temperature of, for example, liquid hydrogen, which is -252°C, or liquid nitrogen, which is -196°C. Sulphur has been quite unexpectedly found among the superconducting materials.
The main unit of this installation is a high-pressure chambcr. It contains two anvils of synthetic polycrystallinc diamond, "carbonado" or black diamond. The surfacc of one anvil is flat, whereas the other one is shaped as a cone. When compressed, the anvil point develops a pressure of half a million atmospheres! Under such conditions sulphur converts to a "metallic" formation. "Metallic sulphur", coolcd by liquid helium, acquires superconducting properties at a temperature of-269°C.
Experiments arc being continued and have so far yielded interesting results. Sulphur has increased the temperature of covcrsion into a superconducting material to -242°C.
Up to now a champion in high temperature superconductivity has been a niobium-to-germanium compound. Its conversion temperature into a superconducting state was -2S0°C. Now the leadership has passed over to sulphur.