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High‐temperature mass spectrometric study of the vaporization processes and thermodynamic properties of melts in the PbO‐B 2 O 3 ‐SiO 2 system
Author(s) -
Stolyarova V. L.,
Lopatin S. I.,
Shilov A. L.,
Shugurov S. M.
Publication year - 2013
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.6606
Subject(s) - vaporization , chemistry , mass spectrometry , analytical chemistry (journal) , atmospheric temperature range , gibbs free energy , knudsen number , ion , evaporation , vapor pressure , thermodynamics , chromatography , organic chemistry , physics
RATIONALE The unique properties of the PbO‐B 2 O 3 ‐SiO 2 system, especially its extensive range of glass‐forming compositions, make it valuable for various practical applications. The thermodynamic properties and vaporization of PbO‐B 2 O 3 ‐SiO 2 melts are not well established so far and the data obtained on these will be useful for optimization of technology and thermodynamic modeling of glasses. METHODS High‐temperature Knudsen effusion mass spectrometry was used to study vaporization processes and to determine the partial pressures of components of the PbO‐B 2 O 3 ‐SiO 2 melts. Measurements were performed with a MS‐1301 mass spectrometer. Vaporization was carried out using two quartz effusion cells containing the sample under study and pure PbO (reference substance). Ions were produced by electron ionization at an energy of 25 eV. To facilitate interpretation of the mass spectra, the appearance energies of ions were also measured. RESULTS Pb, PbO and O 2 were found to be the main vapor species over the samples studied at 1100 K. The PbO activities as a function of the composition of the system were derived from the measured PbO partial pressures. The B 2 O 3 and SiO 2 activities, the Gibbs energy of formation, the excess Gibbs energy of formation and mass losses in the samples studied were calculated. CONCLUSIONS Partial pressures of the vapor species over PbO‐B 2 O 3 ‐SiO 2 melts were measured at 1100 K in the wide range of compositions using the Knudsen mass spectrometric method. The data enabled the PbO, B 2 O 3 , and SiO 2 activities in these melts to be derived and provided evidence of their negative deviations from ideal behavior. Copyright © 2013 John Wiley & Sons, Ltd.