Co-doped Y2O3 optical functional nanoparticles and novel self-assembly squama-like aggregates

Co-doped Y2O3 optical functional nanoparticles with size of 4-10 nm have been synthesized by the plasma arc-discharge method. Meanwhile, novel three-dimensional squama-like macro-aggregates were self-assembled by disordered nanoparticles synthesized simultaneously in the arcdischarge process. The formation mechanism of the aggregates is ascribed to the periodic coagulation of Y nanoparticles. The valence states of Co in Y2O3 lattice can be determined as +2 from XPS spectrum with an etching depth of 6 nm. For Co-doped Y2O3 nanoparticles, upon excitation with 426 nm, a red emission (620 nm) has been observed which originates from (4)A(2) (F-4) -> T-4(1) (P-4) d-d transitions of Co2+ ions in tetrahedral co-ordination. (C) 2007 Elsevier B.V. All rights reserved.