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Volatility of UO 2±x and Phase Relations in the System Uranium—Oxygen
Author(s) -
CHAPMAN A. T.,
MEADOWS R. E.
Publication year - 1964
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1964.tb13117.x
Subject(s) - uranium , uranium dioxide , oxygen , volatilisation , stoichiometry , uranium oxide , volatility (finance) , partial pressure , analytical chemistry (journal) , chemistry , materials science , inorganic chemistry , metallurgy , organic chemistry , economics , chromatography , financial economics
The volatility of UO 2±x and the phase relations in the system uranium‐oxygen were studied using thermogravimetric techniques. Chemical reactions describing the loss of uranium from UO 2±x at temperatures between 1100° and 2200°C in oxygen pressures between approximately 10 2 and 10 −6 torr are proposed. Results were obtained requiring the consideration of UO 4 (g) as the uranium‐bearing vapor species above UO 2±x . Evidence supporting the existence of UO 4 (g) included the volatilization of material with an oxygen‐to‐uranium ratio of 4 during the decomposition of UO 2+x (0.Z > × > 0) to near‐stoichiometric UO 2 in vacuum above 1500°C and the dependence of the evaporation rate of the uranium dioxide on the oxygen pressure between 1200° and 1500°C. The equilibrium oxygen pressures over compositions between UO 2.02 and UO 2.63 in the UO 2+x and U 3 O 8‐y regions and over the boundary between these phases were measured between 1000° and 1600°C. The equilibrium oxygen‐to‐uranium ratio of UO 2±x was less than 2 above 1700°C in vacuum.