Morphologies and Crystal Phase Control of Calcium Carbonate Using “Crew-Cut” Micelles of Poly (styrene)-b-Poly (acrylic acid) as a Crystal Growth Modifier at Room Temperature

Cubic layer-structured calcite and spherical vaterite were successfully prepared in the present of PS-b-PAA at room temperature. The products were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and flourier transform infrared spectrum (FI-IR). The characterized results revealed that the PS-b-PAA concentration had a considerable influence on the morphologies and crystal phase transformation. With the PS-b-PAA concentration increasing, the crystal phase of CaCO3particles would have a significant transition from calcite to vaterite, and the morphologies also showed remarkable changes from cubic layer-superstructure to spherical shape. Furthermore, cubic structured CaCO3 particles with a larger size of ca. 100 μm in side length could be prepared by gas diffusion method, indicating that the “crew-cut” micelles are able to result in long-live crystal active sites so that novel large-scale inorganic materials might be prepared.

Luminescence and Absorption of Hybrid Xerogels Doped with PbS Nanoparticles Prepared by Gas Diffusion Method

Transparent hybrid organic-inorganic ureasil xerogels with embedded PbS nanoparticles were prepared by exposing the xerogels doped with lead (II) nitrate to hydrogen sulphide atmosphere. Absorbance spectrum of the nonocomposites showed well defined peaks at 560 nm and 370 nm attributed to 1s(v) - 1s(c) and 1s(v) - 2p(c) exciton transitions, respectively. After four days of thermal treatment at 50 °C under argon atmosphere the obtained materials showed enhanced photoluminescence response in the near infra-red region.