THERMODYNAMIC STUDIES OF URANIUM-GADOLINIUM-CARBON SYSTEM THROUGH THECARBOTHERMIC REDUCTION OF THE OXIDES

The formation of solid solutions of (U1-yGdy)C-2 (where 0.2 less than or equal to y less than or equal to 0.8) in the high carbon region, ha s been studied in the temperature range 1063-1673 K. The solid solutio ns were prepared by blending the stoichiometric amounts of oxides with graphite and heating the mixture in the form of a pellet to the react ion temperature in a high vacuum chamber. The effusion of CO from the pellet was monitored by means of a quadrupole mass spectrometer. The e ffusion pressures of CO in the vacuum chamber were correlated to the e quilibrium pressure of the system. according to a new method developed in our laboratory [R. Vidhya, M.P. Antony, C.K. Mathews, J. Phys. Che m. 99 (1995) 16468]. The reported solubility [T.C. Wallace, N.H. Kriko rian, P.L. Stone, J. Electrochem. Soc. 111(12) (1964) 1404] of 'GdC2' in 'UC2' was verified by XRD. The Gibbs energies of formation of the d ifferent solid solutions have been calculated. (C) 1997 Elsevier Scien ce B.V.