Electron diffraction studies of supersonic jets. 8. Nucleation of various phases of SF/sub 6/, SeF/sub 6/, and TeF/sub 6/

Journal Article · Thu May 07 04:00:00 EDT 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100294a012· OSTI ID:6803193

Bartell, L S; Valente, E J; Caillat, J C

Old microcrystals of SF/sub 6/, SeF/sub 6/, and TeF/sup 6/ are condensed when the gaseous hexafluorides in monatomic carriers flow supersonically through aminiature Laval nozzle. Electron diffraction records of the condensates display strong Debye-Scherrer rings. The diffraction patterns depend markedly upon the carrier gas and expansion conditions. For the hexafluorides of sulfur and selenium the well-known body-centered plastic cubic phase forms if the molecular weight of the carrier gas is low and the subject mole fraction exceeds several percent. A phase II of low symmetry begins to appear only at low mole fractions of SF/sub 6/ and requires a carrier at least has heavy as argon. Phase II appears for SeF/sub 6/ with argon carrier under all conditions examined and with neon under extreme conditions. It appears readily even with helium in the case of TeF/sub 6/, provided the subject mole fraction is comparatively high. At lower mole fractions and total pressures another, as yet unidentified, phase III of TeF/sub 6/ is produced. Patterns of phase II are well accounted for by the triclinic lattice P1, Z = 3. Refinements based on this space group, for the two compounds yielding nearly pure phase II, led to the following cell constants (3sigma): SeF/sub 6/ (T < 140 K), a = 14.51 (8) A, b = 8.22 (3) A, c = 4.92 (3) A, ..cap alpha.. = 85.6 (3)/sup 0/; ..beta.. = 93.7 (4)/sup 0/, ..gamma.. = 88.14 (4)/sup 0/; TeF/sub 6/ (T < 160 K.), a = 14.99 (7) A, b = 8.53 (3) A, c = 5.06 (3) A, ..cap alpha.. = 85.6 (3)/sup 0/, ..beta.. = 93.5 (3)/sup 0/ = 88.9 (3)/sup 0/.

• Research Organization: Univ. of Michigan, Ann Arbor
• OSTI ID: 6803193
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:10; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
ARGON
COHERENT SCATTERING
CRYSTAL STRUCTURE
CRYSTALLIZATION
CRYSTALLOGRAPHY
DATA
DIFFRACTION
ELECTRON DIFFRACTION
ELEMENTS
EXPERIMENTAL DATA
FLUID FLOW
FLUIDS
FLUORIDES
FLUORINE COMPOUNDS
GASES
HALIDES
HALOGEN COMPOUNDS
HELIUM
INFORMATION
JETS
KRYPTON
NEON
NONMETALS
NUMERICAL DATA
PHASE TRANSFORMATIONS
PRECIPITATION
RARE GASES
SCATTERING
SELENIUM COMPOUNDS
SELENIUM FLUORIDES
SEPARATION PROCESSES
SULFUR COMPOUNDS
SULFUR FLUORIDES
SUPERSONIC FLOW
TELLURIUM COMPOUNDS
TELLURIUM FLUORIDES
TELLURIUM HALIDES