Quantitative Raman spectroscopy: High-temperature speciation of potassium silicate melts

In situ, high-temperature Raman spectroscopy was used to study the Q(n) speciation in binary potassium silicate melts. Over 300 Raman spectra in the compositional range from 20 to 38 mol% K(2)O were collected at temperatures between 800 and 1200 K. Quantitative information on the relative abundances of species in melts was obtained from the Raman spectra through a quantification procedure that does not require any a priori assumptions about the line shapes or external calibration of the Raman scattering efficiencies for the various Q(n) species. The Delta H(0) associated with the speciation reaction 2Q(3) = Q(4) + Q(2) was found to be 33.1 +/- 7.3 kJ/mol. (c) 2007 Elsevier B.V. All rights reserved.