Silicate glass, matrix

FORMATION OF THE PbS QUANTUM DOTS IN BORON-SILICATE GLASS MATRIX... 

PbS nanoparticles with features of quantum dots (QDs) have been fabricated in boron-silicate glass matrix. Their mean diameter was found to be in the range of 3.4-8.2 nm from the optical spectroscopy data due to their explicit quantum confinement effect. The particle size and position of the absorption bands can be controlled through the regimes of thermal treatment of the glasses. SAXS technique showed near to monodispetse size-distribution of QDs and possible ordering within the glass matrix. 

The fabrication of PbS QDs in the boron-silicate glass matrix has been elaborated. Particle size, and correspondingly, optical absorption was shown to be controlled through the different combinations of the heat treatment. The presence of the heterogeneity areas within the glass structure has been detected with SAXS. The features in size distribution and ordering of particles have been suggested on the basis of SAXS data. 

Formation of the PbS quantum dots in boron-silicate glass matrix. 136... 

CdSe Tei-x nanoparticles were fabricated within the silicate glass matrix and studied with TEM and optical spectroscopy both for as-prepared and heat-treated samples at temperatures lower than the glass softening. Appearance of spectral features in CdTe- and other Te-containing nanoparticles is explained as the phase transformation between wurtzite and sphalerite lattices in the CdSe-CdTe system. 

R. L. McGee and S. Yalvac, Random Stainless Steel Fibre Reinforced Magnesia-Alumina-Silicate Glass Matrix Composites, in Int. SAMPE Symp. Exhib. (1990) 520 32. 

E. Bernardo, G. Scarinci, S. Hreglich, Mechanical Properties of Metal-Particulate Lead-Silicate Glass Matrix Composites Obtained by Means of Powder Technology, J. Europ. Ceram. Soc. 23, 1819-1827 (2003). 

Considering the S emission line, in a graphite matrix, the emission is detectable from a depth of 116 pm in the sample, but that depth is reduced to 14.8 pm in a silicate glass matrix and reduced even more in the dense matrices of iron and lead. This means that if the sulfur in the glass sample... 

Figure 6.8 Comparison of particle deposition around the laser crater of silicate glass matrix (NIST SRM 612) using a 193 nm laser system in argon and helium, respectively. (Reproduced from reference 16, with permission of the Royal Society of Chemistry.)...

The ratio Db/Da is a so-called relative sensitivity factor D. This ratio is mostly determined by one element, e. g. the element for insulating samples, silicon, which is one of the main components of glasses. By use of the equation that the sum of the concentrations of all elements is equal to unity, the bulk concentrations can be determined directly from the measured intensities and the known D-factors, if all components of the sample are known. The linearity of the detected intensity and the flux of the sputtered neutrals in IBSCA and SNMS has been demonstrated for silicate glasses [4.253]. For SNMS the lower matrix dependence has been shown for a variety of samples [4.263]. Comparison of normalized SNMS and IBSCA signals for Na and Pb as prominent components of optical glasses shows that a fairly good linear dependence exists (Fig. 4.49). 

The activation energies calculated for Rb, Cs and Sr in the present study (Table III and Figure 8) are considerably lower than those calculated for high temperature diffusion in both crystalline and glass silicates. This discrepancy in the latter case implies that the glass matrix may be significantly different in high and low temperature diffusion studies. 

From a theoretical point of view, the gel layer is a barrier that reduces further hydrolysis of the silicate network, and is supposed to be more stable than the glass matrix, thus reducing the overall rate of corrosion. However, gel exfoliation may momentarily re-activate corrosion, at least locally. No clear trend was observed for the presence of the crystalline secondary phases identified at the surface of the corroded HT samples. The most abundant minerals are aluminosilicates, calcium phosphates, Fe- and Mg-rich minerals, and zeolites their role in the scavenging or release of metals remains ambiguous, although many mineral phases identified bear traces of metals. 

Fig. 8.3 Phase-contrast TEM image of SiC whiskers in an alumina matrix after initial stage of oxidation in which graphitic carbon (C) and silicate glass (G) are formed at the interface.

Fig. 8.4 Phase-contrast TEM image of SiC whisker in alumina matrix that has undergone oxidation. The silicate glass (G) has begun to react with alumina to form a mullite nucleus (M), and graphitic carbon (C) surrounds the crystallite.14...

---