Electron diffraction studies of supersonic jets. V: Low temperature crystalline forms of SF\u3csub\u3e6\u3c/sub\u3e, SeF\u3csub\u3e6\u3c/sub\u3e, TeF\u3csub\u3e6\u3c/sub\u3e

Condensation of SF6, SeF6, and TeF6 in nozzle flows with inert carrier gases produces microcrystals of these materials. All form the higher temperature body‐centered cubic structure at higher partial pressures of hexafluoride. At lower partial pressures and colder nucleation conditions a lower symmetry form of each has been produced. Electron diffraction powder patterns are consistent with the space group Pnma to which metal hexafluorides of UF6 type belong. Low temperature phases of the present materials differ from those of the metal compounds, however, in being less dense than the cubic forms. Aspects of the gas dynamics affording a control over nucleated species are briefly discussed