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Oxidation Properties of (U, Pu)O 2 Solid Solutions
Author(s) -
TENNERY V. J.,
GODFREY T. G.
Publication year - 1973
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.1151-2916.1973.tb15427.x
Subject(s) - phase (matter) , tetragonal crystal system , solid solution , isothermal process , analytical chemistry (journal) , materials science , nucleation , homogeneous , fluorite , chemistry , kinetic energy , nuclear chemistry , crystallography , metallurgy , thermodynamics , chromatography , physics , organic chemistry , quantum mechanics
Air oxidation of (U, Pu)O 2 solid solutions having Pu/(U+Pu) ratios of 0.2 and 0.25 was studied using a recording thermal balance. For Pu/(U+Pu)=0.2, the original fluorite MO 2 phase oxidized first to tetragonal M 3 O 7 ; further oxidation at 450°C< T <600°C gave a two‐phase mixture of M' 3 O 8 and a cubic phase having a 0 ≃5.43 Å. Kinetic analysis of these oxidation stages indicated that the Erofeev nucleation model explains the data reasonably well, with Δ H ≃40 kcal/mol for the formation of M 3 O 7 and Δ H ≃40 kcal/mol for the oxidation of M 3 O 7 to M' 3 O 8 + the cubic phase. Oxidation above M 3 O 7 (O/M=2.35) resulted in mechanical disintegration of the samples because of the presence of the M' 3 O 8 phase. For Pu/(U+Pu) = 0.25, both isothermal and programed air oxidation of homogeneous samples up to 800°C led to a compound with a maximum O/M≃2.35, i.e. M 4 O 9.4 , an fcc phase having a 0 =5.428 Å; these samples were not converted to powder by the oxidation.