Atomic Distributions in Liquid, Plastic, and Crystalline Sulfur

Abstract

X-ray diffraction patterns were obtained, using improved technique, for liquid sulfur at 80°C (supercooled), 120°C, 165°C, 200°C, 240°C, and 300°C; and for amorphous sulfur at 4°C and for powdered crystalline orthorhombic sulfur at 23°C, confirming reported new details at small angles and extending observations to nearly twice the range of (sinθ)/λ heretofore reported. Atomic distribution curves are presented for all these cases. Nearest neighbor distances and numbers remain constant throughout at 2.07 A and 2 atoms, respectively, but other features of the distribution curves change with temperature. New results with neutron diffraction at 120°C are compared with these x-ray results.

Solid Allotropes of Sulfur

“…The X-ray diagram (293,297,298) of SM looks very similar to that of Sa. «-Impurities have therefore been held responsible for the observed patterns, since the X-ray method does not strongly discriminate against different components or contaminations.…”

“…The viscosity, for example, is changed by very small amounts of trivalent elements and by the electrical conductivity, which is the sum of two terms, these being the electronic conductivity of the liquid element and the electrophoretic conductivity caused by (sulfide) impurities. The structure of the liquid has been studied by several investigators (137, 175, 232, 234, 260, 293).…”

Structure of Molten Iron Sulfide under Pressure.

“…There is no significant difference between the structures of molten FeS up to 5.3 GFa (see Fig. 3 [8,9] are also shown in Fig. 4 for a…”

Diffraction Studies of the Structure of Liquids.

“…In an attempt to resolve conflicting findings Gingrich (137) had made photographic measurements over the range 124-300°, and found an apparent shift near 160°, the temperature above which sudden cooling yields plastic or amorphous sulfur. On re-examination, however, with improved collimation and counting techniques, he and Tompson (374) discovered that this effect was due actually to the varying relative contributions of two maxima (at s = 1.23 and 1.72 Á.-1), the positions of which are insensitive to temperature.…”