抄録
Although some of the R2O3-MoO3 (R= rare earth) phase equilibria have been studied, little is known about their crystal structures, except for R2(MoO4)3 which have been well investigated due to interesting physical properties. Recently there is an increasing interest on this phase because fast oxide ion conduction, trivalent R ion conduction, and unusual negative thermal expansion have been discovered. We have developed the preparation procedures of the R2O3-MoO3 phases via thermal decomposition of polyoxomolybdates [R2(H2O)12Mo8O27]•xH2O as the precursors. This method, a kind of self-flux method, gives well-formed single crystals of completely new and/or structurally undetermined R2O3-MoO3 compounds in relatively short reaction time. Interestingly, some new phases obtained in this method do not exist in the known R2O3-MoO3 phase diagram, and can not be obtained in the solid state reaction. Some new structures determined by X-ray structural analysis are described in the presentation.
