Synthesis and optical properties of nanosized powders: lanthanide-doped Y2O3

Y1.8Nd0.2O3 and Y1.8Er0.2O3 powder samples were prepared by combustion synt hesis. X-ray diffraction showed that the materials are nanostructured, with average coherence length 5-10 nm. The visible and infrared luminescence sp ectra of nanometric cubic Y1.8Nd0.2O3 and Y1.8Er0.2O3 show some important d ifferences from these of the bulk materials. in the case of Y1.8Er0.2O3, fa ster relaxation of some excited states occurs, leading to changes in the re lative intensities of several optical transitions. As far as nanostructured Y1.8Nd0.2O3 is concerned, the F-4(3/2) --> I-4(9/2) transition is characte rized by a perturbed intensity pattern of the Stark components and by an an omalous integrated intensity. Possible explanations for this behaviour are proposed. (C) 1999 Elsevier Science B.V. All rights reserved.