SUPERCONDUCTIVITY AT 10-17 K IN COMPRESSED SULFUR

Recent high-pressure studies of condensed matter at extreme densities have uncovered various new phenomena in simple molecular and elemental substances(1). One of the most significant pressure-induced changes i n materials properties is the transformation of insulators into metals and superconductors. Previous studies of compressed sulphur indicated transitions to metallic phases at 90 GPa (ref. 2) and 162 GPa (ref. 3 ). Here we demonstrate that at 93 GPa, elemental sulphur transforms no t only to a metal, but also to a superconductor with a transition temp erature, T-c, of 10.1 K. Using a highly sensitive magnetic susceptibil ity technique adapted for megabar-pressure diamond anvil cells, we fin d that T-c increases linearly with pressure up to 157 GPa. This contra sts with the negative dT(c)/dP observed(4) (at much lower pressures) i n the heavier superconducting chalcogenides Se and Te. Moreover, at th e transformation in sulphur to a higher pressure metallic phase near 1 60 GPa, T-c increases from 14 to 17 K. These are the highest reported transition temperatures for an elemental solid. As such, these results may provide crucial tests of mechanisms of superconductivity.