Vibrational spectroscopic study of alkaline earth aluminosilicate glasses

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6317115

Merzbacher, C I; White, W B

The structures of glasses in the CaO-Al/sub 2/O/sub 3/-SiO/sub 2/ and MgO-Al/sub 2/O/sub 3/-SiO/sub 2/ ternary systems have been investigated using Fourier transform infrared and Raman spectroscopy. The Kramers-Kronig transformation of the specular reflectance infrared spectra separated observed reflectance modes into transverse and longitudinal optic modes. In many cases, better resolution is observed in the transformed functions, thus aiding in structural interpretation. Results suggest that Ca and Mg play strikingly different structural roles in silicate melts. Bands in the high-frequency infrared region (900-1200 cm/sup -1/) associated with T-O stretching vibrations (T=tetra-hedrally-coordinated cations, Si and Al) are sensitive to alkaline earth species and content. Increasing CaAl/sub 2/Si/sub 2/O/sub 8/ across the CaAl/sub 2/Si/sub 2/O/sub 8/-CaSiO/sub 3/ join leads to the merging of the two distinct bands to a single band. In the compositions between MgAl/sub 2/Si/sub 2/O/sub 8/ and MgSiO/sub 3/, however, the opposite is observed; the high-frequency band splits with increasing MgAl/sub 2/Si/sub 2/O/sub 8/. The TO/sub 4/ stretching vibrations in the Raman spectra are insensitive to compositional changes. Far-infrared spectra give information on the vibrations of network-modifying cations. A band near 200 cm/sup -1/ is assigned to the vibration of the Ca ions in large network-modifying sites. No analogous band is observed in the MgO-Al/sub 2/O/sub 3/-SiO/sub 2/ glasses, indicating that the small Mg ions are not acting as loosely bound network modifiers. These trends are evidence of clustering and incipient phase separation.

• Research Organization: Pennsylvania State Univ., University Park (USA)
• OSTI ID: 6317115
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580300 -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
580400* -- Geochemistry-- (-1989)
AMORPHOUS STATE
CALCIUM IONS
CATIONS
CHARGED PARTICLES
CHEMISTRY
CRYSTAL STRUCTURE
CRYSTALLOGRAPHY
EMISSION SPECTROSCOPY
ENERGY LEVELS
EXCITED STATES
GEOCHEMISTRY
GLASS
INFRARED SPECTRA
IONS
LASER SPECTROSCOPY
MAGMA
MAGNESIUM IONS
MINERALIZATION
MINERALS
MOLECULAR STRUCTURE
OXYGEN COMPOUNDS
RAMAN SPECTROSCOPY
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SPECTRA
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
VIBRATIONAL STATES