Raman Spectroscopy of Oxide Glasses at High Pressure and High Temperature

Sharma, Shiv K.; Wang, Zifu; Laan, Sieger van der

doi:10.1002/(sici)1097-4555(199610)27:10<739::aid-jrs30>3.0.co;2-2

Cited by 17 publications

(10 citation statements)

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“…Several workers (Peercy and Morosin 1973;Zallen and Slade 1978;Sharma et al 1996) have introduced the anharmonic parameter, (∂ ln ν/∂T) V , to describe crystal anharmonicity in terms of the pure temperature contribution. Several workers (Peercy and Morosin 1973;Zallen and Slade 1978;Sharma et al 1996) have introduced the anharmonic parameter, (∂ ln ν/∂T) V , to describe crystal anharmonicity in terms of the pure temperature contribution.…”

Section: Resultsmentioning

confidence: 99%

Micro-Raman studies of gypsum in the temperature range between 9 K and 373 K

Chio

Sharma

Muenow

2004

American Mineralogist

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Raman spectra were collected for synthetic gypsum (CaSO 4 ⋅2H 2 O) powder between 9 and 373 K under atmospheric pressure with special emphasis on the temperature dependence of the OH-stretching modes. The stretching bands of the water molecules in gypsum were found to shift in opposite directions as a result of the different degree of intermolecular hydrogen-bonding between nonequivalent water H atoms and the O atoms of nearby SO 4 ions. The anharmonic parameters of the OH-stretching modes are calculated using the temperature derivatives measured from the present investigation and existing pressure derivatives. These parameters are -4.7 × 10 -6 K -1 and -0.6 × 10 -6 K -1 for the 3407 and 3494 cm -1 bands, respectively. The dehydration of gypsum into γ-CaSO 4 and the subsequent rehydration of γ-CaSO 4 into hemihydrate are clearly identified in the Raman spectra by the observed variation in Raman shifts of the OH and ν 1 (SO 4 ) bands. The latter increases as the mineral becomes increasingly anhydrous (1007 cm -1 in gypsum; 1014 cm -1 in hemihydrate; 1026 cm -1 in γ-CaSO 4 ), which can be used as a fingerprint for the remote detection of these minerals on planetary surfaces.

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Section: Resultsmentioning

confidence: 99%

Micro-Raman studies of gypsum in the temperature range between 9 K and 373 K

Chio

Sharma

Muenow

2004

American Mineralogist

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“…Kohn et al (1992) suggested that the 900 cm 1 band may be related to some sort of vibration of Si-O-Al modi ed by the presence of H on the bridging oxygen and recently new high pressure Raman data have been published which support the interpretation of the band as a vibration of the silicate framework (Sharma et al, 1996(Sharma et al, , 1997. Sharma et al (1996Sharma et al ( , 1997 suggest that the band at 900 cm 1 is due to an asymmetric mode of a T O T group.…”

Section: Naalsi 3 O 8 and Other Tectosilicate Glasses Containing Alummentioning

confidence: 97%

“…Nowak and Keppler (1998) interpreted these data in terms of forming a complete hydration shell around Ni. An alternative explanation, however, is that the Ab component has a higher af nity for dissolved (Sharma et al, 1996).…”

Section: A Hierarchy Of Dissolution Mechanisms?mentioning

confidence: 99%

The dissolution mechanisms of water in silicate melts; a synthesis of recent data

Kohn

2000

Mineral. mag.

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Dissolved water has significant effects on the physical and chemical properties of silicate melts. Some of the different approaches towards understanding these effects are reviewed here. Spectroscopic measurements on hydrous glasses quenched from melts provide good models for the structure of the melts at the glass transition temperature (T g ). Such measurements suggest that the mechanism of dissolution of water in silicate melts varies strongly with the bulk composition. In particular framework aluminosilicate compositions seem to have very different dissolution mechanisms from Al-free compositions. The water speciation reactions are temperature dependent, with some of the molecular water which is present in glasses at room temperature being converted to hydroxyl at high temperatures. This conversion probably occurs only above T g . Data on the kinetics of the speciation reaction and the dynamics of microscopic processes in hydrous silicate melts are also discussed. Finally some important aims of future work on hydrous silicate melts are suggested.KEY WORDS: dissolution mechanism, silicate melt, glass transition temperature.

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“…The confocal micro-Raman system used here was described in detail by Sharma et al (1996). Raman spectra were obtained from selected ~1 µm spots and with axial resolution of 2 µm using a modified Leitz Ortholux I petrographic microscope, coupled to a Spex Triplemate grating spectrometer outfitted with a multichannel photo-detector (either a Photometrics or Princeton Instruments liquid-nitrogen-cooled CCD).…”

Section: Raman Spectramentioning

confidence: 99%