Reactions at the liquid silicon/silica glass interface

Thermodynamics and phase stability in the Si–O system

“…The formation of cristobalite must eventually occur at this interface because the liquid composition along the dotted line lies in the two-phase field (Si) + cristobalite. This corrosion process of the silica crucible can be detrimental [176]. The metastable eutectic, L ¼ (Si) + SiO 2 (L), is calculated at x SiO data discussed with Eq.…”

“…12. The claimed formation of the phases SiO(am) or even ÔSiO(cr)' at the interface liquid silicon/silica glass [112,113] will be dealt with in a separate paper [176].…”

Alkaline oxide interface modifiers for silicon fiber production

“…Benchtop fibers of silicon with cores down to 10 microns have been demonstrated using a powder-in tube method [6], but lengths have been limited to a few cm [9]. Gas production due to the reaction of silicon with silicon oxide [10], stress due to thermal mismatch with the glass sheath [11], and discontinuous cores can all contribute to poor performance. Significant progress has been made in assessing and improving the crystallographic quality [12] and impurity content [13] of these fibers, and in understanding the mechanisms responsible for optical losses [14].…”

Reactions between Si melt and various ceramics

“…Figure 3a and 3b show the SEM backscattered electron image (BEI) of the Si-SiO 2 dissolution couple after annealing at 1450°C for 30 min, indicating that no reactional phase appeared at the interface and the interfacial profile not being smooth. An Si inclusion (shown in light contrast) and a worm-like SiO 2 (shown in dark contrast), were clearly seen at the silica-silicon interface, which is supported by the solution-precipitation growth mechanism [8]. The original metastable SiO 2 dissolved in the Si melt to form a saturated reaction zone at the interface.…”

“…Quartz is a mineral comprising of silicon and oxygen atoms in a continuous silicon-oxygen (SiO 4 ) tetrahedral framework, with each oxygen being shared between two tetrahedra, which represents an overall chemical formula of SiO 2 . The microstructure of the Si-SiO 2 inter-face was previously characterized using scanning electron microscopy (SEM) and it was found that the solutionprecipitation mechanism causes Si inclusions and wormlike cristobalite SiO 2 to appear locally at the interface [8]. Local cristobalite SiO 2 formation can easily result in a crack formation at the surface of Si.…”