Gel synthesis of an albite (NaAlSi[sub 3]O[sub 8]) glass: An NMR analysis

Journal Article · Sun Aug 01 00:00:00 EDT 1993 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(93)90345-W· OSTI ID:5578571

Schmelz, C E; Stebbins, J F ^[1]

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1. Stanford Univ., CA (United States)

The authors have extended the range and complexity of glasses formed by the combination of metal-alkoxides by synthesizing a clear, homogeneous gel of albite (NaAlSi[sub 3]O[sub 8]) composition and heat-treating it to make a densified glass. Systematic changes in [sup 29]Si, [sup 27]Al, and [sup 23]Na NMR spectra of gels with heat treatment are similar to differences in published spectra of hydrated albite glasses with varying water contents. The [sup 29]Si spectra showed one peak; if Q[sup 3](OH) species are present in the samples, it is not obvious in the spectra. Analysis of the rate of spin transfer in CPMAS experiments suggests a Si-H distance [approximately]15% shorter than that seen in Q[sup 3](OH) species in silica gel. Both the [sup 27]Al and [sup 23]Na peaks show an increase in quadrupolar broadening with heat treatment of the gel. Two peaks are present in the [sup 23]Na spectra for gels heat-treated to 300 and 500[degrees]C, possibly due to sites with different sodium coordination. It is proposed that the differences in spectra can be explained by the differences in volatile content of the samples (including water as either H[sub 2]O or OH[sup [minus]], and organic species such as ethanol). In the fresh gels with high contents of these polar species, the sodium is fully coordinated by polar molecules, with hydrogens bonding to the bridging oxygens. The volatiles are removed with heating, allowing the structure to relax to a point closer to that of an anhydrous albite glass made from a quenched melt. 83 refs., 5 figs., 3 tabs.

• OSTI ID: 5578571
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 57:16; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALBITE
CHEMICAL REACTIONS
GLASS
PRODUCTION
ALKOXIDES
ALUMINIUM 27
ALUMINIUM SILICATES
MOLECULAR STRUCTURE
NMR SPECTRA
SILICON 29
SODIUM 23
SODIUM SILICATES
SOL-GEL PROCESS
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ALUMINIUM COMPOUNDS
ALUMINIUM ISOTOPES
EVEN-ODD NUCLEI
FELDSPARS
ISOTOPES
LIGHT NUCLEI
MINERALS
NUCLEI
ODD-EVEN NUCLEI
OXYGEN COMPOUNDS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON ISOTOPES
SODIUM COMPOUNDS
SODIUM ISOTOPES
SPECTRA
STABLE ISOTOPES
360601* - Other Materials- Preparation & Manufacture
400201 - Chemical & Physicochemical Properties