A New High-Pressure Form of Sulfur Derived from the Decomposition of S4N4.

A new phase of sulfur is formed from S(4)N(4) held at pressure-temperature conditions in the vicinity of the boundary representing the decomposition of S(4)N(4) to fibrous sulfur, S(x). The new phase is gray-black, is persistently metastable at room conditions, and is insoluble in carbon disulfide. The phase is apparently formed from a stage of decomposition during which high-conductance transients are observed in in situ electrical experiments. The sulfur phase appears to form upon the release of the nitrogen from a sulfur-nitrogen chain that is produced from the scission of an S(4)N(4) ring.