Cohesive Energies of Transition Metal Silicides and Phosphides.

Vaporization studies have been carried out by mass loss Knudsen effusion on the Ni-P and chromium-phosphorus systems and by Knudsen effusion mass spectrometry on the V-Si, Cr-Si and Ti-Si systems. The experimental data were used to calculate enthalpies of formation of the intermediate phases in these systems. The stabilities of the 11 compounds, expressed as enthalpies of atomization, have been compared with each other and with data on silicides, phosphides, and sulfides from the literature to assess factors for inclusion in a phenomenological model for stability. These factors include a the number and type of bonding electrons, b effective nuclear charges, c valence state energies, d the degree of partial electron transfer with a resulting Made lung energy, and e contributions from Lewis acid-base interactions involving back-donation of electrons. Keywords Transition metal silicides, Transition metal phosphides, Mass loss knudsen effusion, Knudsen effusion mass spectrometry, Vaporization behavior, Congruent vaporization, Thermodynamic activities, Phase equilibria, Free energy of formation, Enthalpy, Formation, Stability.