The optical properties of soda-lime-silica glasses doped with eggshell powder were investigated using UV-visible and the Fourier transform infrared spectroscopies. Pure soda-lime-silica glass, which is colorless and transparent, turned dark green after the addition of the eggshell powder. When the eggshell powder content was ≥ 3 wt%, the glass became translucent. The maximum wavelengths in the UV spectra of the soda-lime-silica glasses doped with 0.5, 1, 3, and 5 wt% eggshell powder were observed at 300.20, 277.40, 284.40, and 312.40 nm, respectively. The Fourier transform infrared spectra of the eggshell-doped soda-lime-silica glass samples were very similar to that of the base undoped glass. The bands at approximately 770-820 cm¯¹ could be attributed to the Si-O-Si symmetric stretching of the bridging oxygen between the tetrahedra, while the bands at approximately 970 cm¯¹ were related to the Si-O-Si antisymmetric stretching of the bridging oxygen within the tetrahedra.
We first focus on the kinetics of nanoparticle growth in a microemulsion synthesis of CdSe semiconductor nanocrystals. The process consists of a fast initial stage of typical time constant of the order of 103 s followed by a slow stage of time constant of the order of 104s. Growth proceeds similarly to that described for the hot-matrix synthesis of CdSe, underlining the generality of the two-stage growth mechanism, irrespective of the matrix type and synthesis conditions. However, the time constant of each stage in the microemulsion synthesis is much larger than in the hot-matrix one. Also, the ratio between the fast and slow time constant is appreciably bigger. We also prove that larger size reverse micelles, obtained by increasing the water:surfactant ratio, generally lead to larger CdSe nanoparticles. Bis(trimethylsilyl) selenium is the crucial precursor for the CdSe nanoparticle synthesis. An intermediate stage of the chemical reaction limiting the bis(trimethylsilyl) selenium production is described theoretically. [...]
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