Optical properties of neodymium oxides at the nanometer scale

The polyol method has been recently developed for preparing concentrated and stable colloids of highly crystallized colloids. Already applied to europium oxide it is used here for synthesizing particles of neodymium oxide as the main constituent or as a 10 mol% doping element in RE2O3 (RE=Y, Gd). High-resolution transmission electron microscopy has identified particles with an average grain diameter in the range 3-5 nm crystallized in the cubic phase. The absorption spectra were recorded, from which the Judd-Ofelt analysis was performed. The calculated radiative lifetime of the 4F3/2 Nd3+ energy level was found to be 144 μs in the Nd2O3 nanoparticles, that is to say much longer than the measured lifetime (70 ns), indicating a strong luminescence quenching attributed to nonradiative losses.