GROWTH OF CDSE MICROCRYSTALLITES IN A BOROSILICATE GLASS MATRIX .1. PREPARATION AND X-RAY-ANALYSIS

CdSe microcrystals were grown at 580 and 600-degrees-C for 10-240 h from a K2O-ZnO-B2O3-SiO2 glass containing Cd2+ and Se2- ions. Size distribution of the microcrystals was qualitatively characterized by linear absorption measurements: a uniform size of CdSe microcrystals is indicated by a symmetric and well developed absorption band which becomes more narrow and intense with decreasing temperature of measurement. These results were confirmed by small angle X-ray scattering (SAXS) with Cu K(alpha) radiation of a SAXS device of Kratky-type. At 580-degrees-C, increasing heat treatment duration resulted in an increase of the amount of the precipitated CdSe microcrystals. A nearly complete precipitation of uniform microcrystals with radii of 1.6+/-0.2 nm was achieved after 80 h. Increasing treatment temperatures and/or periods caused a coarsening of the microcrystals. The size distribution became more asymmetric (Ostwald ripening).