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Disorder of the sublattice of terminal groups and phase transition in octa(vinylsilsequioxane) (in Russian)

Journal Article · · J. Struct. Chem. (Engl. Transl.); (United States)
OSTI ID:6424106
; ; ;
Octa(vinylsilsesquioxane) is one of the members of a series of materials which are important for microelectronics, viz., the organylsilsesquioxanes with the general formula (RSiO/sub 1.5/)/sub n/, where R is an organic substituent, and exists in the form of a molecular crystal consisting of (C2H3SiO/sub 1.5)9 molecules. The almost cubic silicon-oxygen skeleton is slightly extended along the C3 axis. According to the data from x-ray diffraction analysis, at room temperature there is disordering of the terminal C/sub US / carbon atoms of the substituent in the compound: among three positions for substituents lying on the third-order axis and among two positions for those in positions which are not symmetry centers. However, the question of the nature of the disordering (whether it is static or dynamic) remained open. In the present work the authors used the method of proton NMR (PMR), NMR relaxation, and precision calorimetry to establish that dynamic disordering appears in octa(vinylsilsesquioxane) at T = 230K in the sublattice of the terminal groups of atoms and that it is accompanied by a phase transition in the system.
OSTI ID:
6424106
Journal Information:
J. Struct. Chem. (Engl. Transl.); (United States), Journal Name: J. Struct. Chem. (Engl. Transl.); (United States) Vol. 26:4; ISSN JSTCA
Country of Publication:
United States
Language:
Russian

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Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
640302 -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ARRHENIUS EQUATION
BARYONS
CALORIMETRY
COHERENT SCATTERING
COMPLEXES
CONFIGURATION INTERACTION
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
DIFFRACTION
DIPOLE MOMENTS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
FINE STRUCTURE
HADRONS
LATTICE PARAMETERS
MAGNETIC DIPOLE MOMENTS
MAGNETIC MOMENTS
MAGNETIC RESONANCE
MOLECULAR STRUCTURE
MONOMERS
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
ORDER PARAMETERS
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PROTONS
RELAXATION
RELAXATION TIME
RESONANCE
SCATTERING
SILICON COMPLEXES
SILOXANES
SPECIFIC HEAT
SPECTRA
SPIN-LATTICE RELAXATION
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
VINYL MONOMERS
X-RAY DIFFRACTION