Phase relations, lattice thermal expansion in Ce1-x,EuxO2-x/2 and Ce1-xSmxO2-x/2 systems and stabilization of cubic RE2O3 (RE: Eu, Sm)

The phase relations in CeO2-Eu2O3 and CeO2-Sm2O3 systems have been established under slow-cooled conditions from 1400 degrees C. The two-phase relations differ as the CeO2-Eu2O3 system showed only two monophasic phase fields, namely F-type cubic and C-type cubic, whereas CeO2-Sm2O3 system showed three phase fields namely F-type cubic, C-type cubic and a biphasic field comprising of C-type cubic and monoclinic phase. An interesting observation of this investigation is the stabilization of C-type rare-earth oxide after Ce4+ substitution, which is attributed to decrease in average cationic size on Ce4+ substitution at RE 31 site. The lattice thermal expansion behavior of F-type solid solution and C-type solid solution in CeO2-Eu2O3 system was investigated by high-temperature XRD. (c) 2006 Elsevier B.V. All rights reserved.