Thermodynamic stability of gaseous scandium silicides and germanides

Abstract

The equilibria involving the gaseous species above the Sc/Si and Sc/Ge alloy systems have been experimentally investigated by high-temperature mass spectrometry. The previously unknown gaseous molecules ScGe and ScSi were identified, and the respective dissociation enthalpies (in kJ mol^–1) were evaluated as D^°₀= 266.2 ± 11 for ScGe and D^°₀= 223.5 ± 14 for ScSi. The corresponding standard heats of formation, ΔH^°_f,298, are 482 ± 11 and 614 ± 14 kJ mol^–1. Also determined were upper limits for the atomization energies of the molecules ScGe₂ and ScSi₂.