Structure and vibrational properties of sodium disilicate glass from ab initio molecular orbital calculations

Article Abstract:

The structure and vibration of sodium disilicate glass has been studied by performing ab initio molecular orbital calculations on a cluster of atoms having five SiO3/2O-Na+ units connected to siloxane bonds. The calculated photoionization energies and harmonic vibrational frequencies are used in investigating the x-ray photoelectron and vibrational spectra. Results show multiple coordination of Na+ ions when the geometry of the cluster is completely optimized at the HF/6-31G(d) level. It has also been observed that Na-Onb bonds are shorter than Na-Ob bonds. This indicates that there is strong covalent and Coulomb interaction in the former.

Analysis, Glass, Atomic structure, Molecular orbitals

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Sodium and lithium environments in single- and mixed-alkali silicate glasses. An ab initio molecular orbital study

Article Abstract:

Cluster model calculations at the Hartree-Fock/6-31G(d) level were carried out to study the local coordination environments of Li+ and Na+ ions in single- and mixed-alkali silicate glasses. Results indicated that the average coordination number of alkali cations increases from Li to Na and each alkali cation is located in individual sites in the single- and mixed-alkali clusters. There is also significant site mismatch during the hopping of the alkali cations.

Research, Molecular structure, Sodium, Sodium (Chemical element), Silicates, Lithium, Lithium (Metal), Ionic equilibrium

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Effects of organic groups on structure and viscoelastic properties of organic-inorganic polysiloxane hybrid system

Article Abstract:

The structure and viscoelastic properties of an organic-inorganic hybrid system composed of an organically modified polysiloxane network are investigated, and the effect of organic groups on elastic-modulus variation by heat treatment studied. It is found that an increase in phenyl-group numbers per silicon decelerated the increase in the elastic modulus by heat treatment while the substitution of the Ph group for a methyl group accelerates it.

All Other Basic Inorganic Chemical Manufacturing, Silicon & Inorganic Compounds, Electric properties, Polysilicon, Silicon compounds, Structure

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