Kinetics and mechanism of periodic structure formation at SiO2/Mg interface

The interaction between SiO2 (vitreous/fused silica and quartz) and Mg powder at 450–640 °C was investigated employing a combination of X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. The interaction resulted in the formation of a periodic layered structure, consisting of alternating MgO and Mg2Si-rich layers, with typical thickness of 0.5–3 μm. The reaction zone was found to grow by a parabolic law with activation energy of about 76 and 90 kJ/mol for fused silica/Mg and quartz/Mg interactions, respectively. The growth process is controlled by Mg diffusion to SiO2 substrate. A qualitative model describing the formation of such a layered structure in the SiO2/Mg system is presented.