49 research outputs found
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CALCULATED THERMODYNAMIC DATA ANDMETASTABLE IMMISCIBILITY IN THE SiO -Al 0 SYSTEM
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DEPENDENCE OF PHASE COMPOSITION OF NUCLEI AVAILABILITY IN SiO2-Al2O3 MIXTURES
Synthesis and Luminescence of Silicon Remnants Formed by Truncated GlassmeltâParticle Reaction
[[abstract]]We have obtained nanometer sized silicon remnants sequestered in glass matrices by terminating the reaction of pure silicon powders dispersed in the viscous melt at a temperature of 1400â°C. Repeated use of this truncated meltâparticle reaction process dilutes the amount and size of silicon remnants, and bulk samples containing nanosize silicon crystallites embedded in a glass matrix were eventually obtained. These quantum dot sized siliconâinâglass materials emit greenish luminescence with peak wavelengths from â480 to 530 nm, considerably shorter than the reddish luminescence (at about 700â850 nm) observed in porous silicon structures prepared by electrochemical etching techniques; upon complete digestion of Si particles by the melt, the luminescence peaks disappear. Since our siliconâinâglass preparation method does not involve etching, the origin of the luminescence is not likely to be due to SiâOâH compounds (e.g., siloxene) postulated recently. The location of the luminescence peaks and the observed silicon crystallite size suggest quantum confinement leading to a widened silicon band gap arising from remnants in the glass matrix smaller than the exciton diameter of bulk silicon (10 nm)