THERMODYNAMICS OF RARE-EARTH-CARBON SYSTEMS .I. CERIUM-CARBON SYSTEM

The gaseous phase in thermodynamic equilibrium with the condensed cerium-carbon system has been investigated by means of the combined Knudsen-cell-mass-spectrometric technique in the temperature range 1990°-2300°K. In addition to cerium atoms, the gaseous carbide molecules CeC2 and CeC4 were identified and their partial pressures measured. Using this information, the following dissociation and atomization energies were derived: D0°= 162±2 kcal/mole for the Ce-C2 bond energy in CeC2; ΔH0° = 304.S±1.5 kcal/mole for the atomization energy of CeC2; ΔH0°=609±5 kcal/mole for the atomization energy of CeC4.