Nanostructure designed powders of optical active materials MexSiOy obtained by ultrasonic spray pyrolysis

A new approach to the two-level design and self-assembling of MexSiOy (Me = Gd, Y and Ca or their mixtures) nano-powders from SiO2 sols is described. The nanostructure design of various optical active materials based on different compounds of Me(x)Sio(y) is discussed. These particles were formed by the combination of hydrothermal synthesis and ultrasound spray pyrolysis. The morphology and structural design of the particles and sub-particles are defined by their synthesis procedure and processing parameters. The mean particle size and size distribution of all the MexSiOy based compounds were determined by SEM analysis. These results were compared with the particle diameter evaluated from the theoretical model of the breaking-up of capillary waves. For all the synthesized powders, the obtained results indicate the possibility of a rigorous design of the structure of the particles throughout their entire hierarchy. (c) 2007 Elsevier B.V. All rights reserved.