Solid solutions with the fluorite structure in Ln2O3-Sb2O5(Ln=Nd-Lu and Y) systems

Interaction in the systems Ln2O3-Sb2O5(Ln=Nd-Lu,Y) has been studied in air; the solid solutions formed have been characterized. It has been established that all Ln2O3 and Y2O3 studied at 950 deg C form with antimony pentoxide solid solutions Lnsub(2-x)Sbsub(x)Osub(3+x) with disordered fluorite structure. All the phases are characterized by some homogeneity region which grows when passing from lighter Ln(for Nd 0.5 (<=)x(<=) 0.6) to heavier ( for Lu o.38 (<=)x(<=) 0.80). The lattice parameters ''a'' of monophase samples Lnsub(2-x)Sbsub(x)Osub(3+x) decrease with increasing x which agrees with a replacement of greater cation Ln with smaller Sb in the crystal structure. For the samples Lnsub(2-x)Sbsub(x)Osub(3+x) annealed at 1200 deg C destruction of fluorite-like structure is observed and the formation of ordered phases takes place when Ln=Nd; for the rest Ln and Y the character of the structure, lattice parameters, and x values are practically the same as for annealed at 950 deg C samples