On the formation of UC_1-xO_x

From thermodynamical study, it was inferred that any stable ternary compound in the region U-UC-UO₂ will be in equilibrium with CO gas of 10^-3∼10^-4 mmHg at 1,600℃, if it exists. Mixed powder compact of UO₂ and UC having a ratio of 0∼3 to 1 as well as that of UO₂ and UC₂ of 1/3∼3 to 1 (ratio of UO₂ to UC₂) were heated at 1,600℃ for 4 hr in vacuum of 10^-4 mmHg. The phases after the reaction were identified and quantitatively determined by X ray diffractographic techniques, which showed that the amount of UO₂ was much decreased and that of a UC-like phase having a slightly smaller parameter than UC was increased. This latter phase was considered to be UC_1-xO_x, and the x was calculated from the ratios of UO₂ to UC_1-xO_x before and after the reaction. The values of x was also determined by chemical analysis of carbon and nitrogen, which was nearly equal to the value of x from the X ray analysis. The largest value of x was 0.83 and was obtained by the reaction of a compact of UO₂ and UC of 3 to 1 ratio. The lattice parameter of this UC_1-xO_x was measured to be 4.944 Å and its theoretical density was calculated to be 13.91. (author)