Vaporization Thermodynamics of Chromium Silicides.
STATE UNIV OF NEW YORK AT BINGHAMTON DEPT OF CHEMISTRY
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The vaporization thermodynamics of the chromium-silicon system have been investigated in the temperature range 1300-1600K by Knudsen cell mass spectrometry. Both magnetic sector and quadrupole instruments were employed. Thermodynamic activities were obtained by direct comparison with the elements. Standard free energies of formation at 1500K, Delta G deg sub fR kilokelvins are 13 CrSi2, -3.07 12 CrSi, -3.62 18 Cr5Si3, -3.73 14 Cr3Si, -3.28. These data, when combined with heat capacity and entropy data from the literature, give standard enthalpies of formation at 298.15K, Delta H deg sub fR kilokelvins 13 CrSi2, -3.36 12 CrSi, -3.20 18 Cr5Si3, -3.38 14 Cr3Si, -3.39. The CrSi2 phase was found to contain the congruently vaporizing composition. Keywords Chromium silicides, vaporization thermodynamics, free energy of formation, enthalpy of formation, congruent vaporization, Knudsen effusion, mass spectrometry.
- Inorganic Chemistry
- Atomic and Molecular Physics and Spectroscopy