No abstract

In this study we have synthesized Y 2 O 3 (yttria) nanopowders with 1 % Nd 3+ concentration by using a thermal decomposition method and investigated the effect of annealing temperature on the particle sizes and the effect of particle sizes on the spectroscopic properties of these systems. The particle sizes were effectively controlled by synthesis and annealing temperatures; the sizes were found to vary in the 15-290 nm range. The particle sizes and cubic phase of the yttria were determined by using XRD patterns and confirmed by SEM and TEM measurements. We note that the particle sizes increase by increasing the synthesis and annealing temperatures. Temperature dependence of the width and position of a selected spectral line were successfully fitted with the theoretical expressions. We studied thoroughly the behavior of the samples under pulsed excitation and give plausible explanations of the measured effects.

We report the production of a broad band (ranging from 400 to 900 nm) white light following the monochromatic infrared light (803.5 and 975 nm) excitation of both nominally un-doped and Nd 3þ -doped Y 2 O 3 nano-powders, even up to 20% of Nd 3þ content. Experimental results indicate that such emission feature is a nano-scale phenomenon, cannot be ascribed to an overlap of sharp emission bands in the un-doped case and, even if assisted by the Nd 34 presence, is a host matrix-related process. The measured white light emission is strongly dependent on either environment pressure (a pressure threshold occurs) or pumping power. The rising patterns of the white light emission were found to increase faster for either increasing Nd 3þ content and pumping power or decreasing particle size. Notably, high correlated color temperature (2756 K), color rendering index (99), and efficiency (864 lx/W) values were measured for the un-doped sample under 803.5 nm exciting wavelength.