Synthesis and properties of europium-based phosphors on the manometer scale:: Eu2O3, Gd2O3:Eu, and Y2O3:Eu

Nanocrystals of oxides containing europium as the main constituent or as a doping element in RE2O3 (RE = Y, Gd) have been prepared by direct oxide precipitation in high-boiling polyalcohol solutions and characterized by high-resolution TEM, absorption spectroscopy, and luminescence spectroscopy. The samples obtained consisted of concentrated and colloidally stable suspensions of luminescent oxide nanoparticles with an average grain diameter in the range 2-5 nm. The nanoparticles were found to be highly crystalline despite their ultrasmall size and the low temperature of 180 C applied during the synthesis. Upon UV excitation, the red luminescence relative to the D-5(0) --> F-7(n) transition within the cubic form of RE2O3 exhibits some important differences from that usually found in bulk materials. (C) 2003 Elsevier Inc. All rights reserved.