Vibrational spectroscopy of silicate liquids and glasses

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doi: 10.1016/0009-2541(92)90064-C
Authors:McMillan, Paul F.; Wolf, George H.; Poe, Brent T.
Author Affiliations:Primary:
Ariz. State Univ., Dep. Chem., Tempe, AZ, United States
Univ. Bayreuth, Federal Republic of Germany
Volume Title:Silicate melts
Volume Authors:Bottinga, Yan, editor; Dingwell, Donald B.; Richet, Pascal
Source:Chemical Geology, 96(3-4), p.351-366; 4th silicate melt workshop, Le Hohwald, Alsace, France, March 19-23, 1991, edited by Yan Bottinga, Donald B. Dingwell and Pascal Richet. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0009-2541
Publication Date:1992
Note:In English. 51 refs.; illus.
Summary:The application of this technique is described and new Raman data for K2Si2O5 and K2Si4O9 are presented. The timescale of the vibrational spectroscopic experiments relative to relaxation timescales in the melts is discussed. Silicate systems are usually described as 'liquid' or 'glassy' based on experimental measurements of viscosity or heat capacity. The vibrational spectroscopies are complementary to other spectroscopic methods, including NMR, for this type of study. The authors' new Raman spectroscopic results on K- disilicate and -tetrasilicate glasses and liquids show effects due to structural relaxation above the glass transition T, Tg. The spectra for K2Si2O5 show evidence for an increase in the concentration of Q2 silicate species with increasing T. The present authors have determined the enthalpy change for 2Q3 = Q2+Q4 speciation reaction in K2Si2O5 to be approx 20 kJ/mol, of the same order of magnitude as those obtained for liquids near Na2Si2O5 composition by previous workers. For K2Si4O9 glass, the Raman data show evidence for a different type of structural relaxation. The intensity of the peak near 590 cm-1 increases with increasing T above Tg, which is interpreted as an increase in the proportion of three- membered siloxane rings in the liquid. The enthalpy change for formation of these three-membered rings is also 20 kJ/mol, consistent with the results of a previous study on SiO2 glass. [P.Br.]
Subjects:Crystal structure; Experimental studies; Glasses; Igneous rocks; Liquid phase; Minerals; Raman spectra; Silicates; Spectra; Vibrational spectra; Volcanic rocks
Abstract Numbers:92M/4052
Record ID:1992033749
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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