Thermochemistry and structure of glasses along the join NaAlSi sub 3 O sub 8 -NaBSi sub 3 O sub 8

Journal Article · Sat Oct 01 00:00:00 EDT 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90297-9· OSTI ID:5180600

Geisinger, K L ^[1]; Oestrike, R; Navrotsky, A ^[2]; Turner, G L; Kirkpatrick, R J ^[3]

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1. Corning Glass Works, NY (USA)
2. Princeton Univ., NJ (USA)
3. Univ. of Illinois at Urbanna-Champaign, IL (USA)

Glasses along the join NaAlSi{sub 3}-O{sub 8}-NaBiO{sub 8} and the end-member crystalline phases albite and reedmergnerite were investigated using {sup 11}B, {sup 23}Na, {sup 27}Al and {sup 29}Si MAS NMR spectroscopy and oxide-melt solution calorimetry. The glasses have substantial positive enthalpies of mixing described by the equation {Delta}H{sub mix} (kcal{center dot}mol{sup minus 1}) = 4.4({plus minus} 1.0)X(1 - X), where X is the mole fraction Rd component. {sup 11}B MAS NMR spectra show that boron occurs in both trigonal and tetrahedral coordination in the glasses, with the percentage of B in trigonal coordination decreasing from about 60% at Rd{sub 20}Ab{sub 80} to about 29% at Rd{sub 100}. Thus, the glasses are structurally more complex than the end-member crystals which are tetrahedral framework minerals. The NMR data suggest that all or most of the Si, Al and tetrahedral B occur in Q{sup 4} (framework) sites. They are also consistent with the ideas that most of the tetrahedral B does not extensively copolymerize with trigonal boron, that at least some of the non-bridging oxygens formed by the presence of trigonal boron are located on SiO{sub 4} tetrahedra, and that Si and trigonal B do not occur as next-nearest neighbors. Both the NMR and the {Delta}H{sub mix} results indicate the presence of clustering. Such clustering might involve separation into framework regions and regions dominated by trigonal boron and/or into B-rich and Al-rich framework regions.

• DOE Contract Number: FG02-85ER13437
• OSTI ID: 5180600
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:10; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ALKALI METAL COMPOUNDS
AMORPHOUS STATE
BORON COMPOUNDS
CALORIMETRY
CHEMICAL COMPOSITION
CHEMISTRY
CONFIGURATION INTERACTION
CRYSTAL STRUCTURE
CRYSTALLIZATION
ENTHALPY
FELDSPARS
GEOCHEMISTRY
GLASS
MAGIC NUCLEI
MINERALS
MOLECULAR STRUCTURE
NUCLEI
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SILICATE MINERALS
SODIUM COMPOUNDS
STRUCTURAL CHEMICAL ANALYSIS
THERMOCHEMICAL PROCESSES
THERMODYNAMIC PROPERTIES