In Situ study of Nucleation of Zirconia in an MgO-Al_2O_3-SiO_2 Glass

摘要

Crystalline nucleation is investigated during the dynamical heat treatment of a ZrO_2-MgO-Al_2O_3-SiO_2 glass by high-temperature Zr K-edge X-ray absorption near-edge spectroscopy. In the parent glass, the Zr coordination number is higher than in most glasses, explaining the structural instability of Zr during thermal treatment. The Zr local structure is modified at 30℃ above the nucleation onset. Crystalline nucleation is characterized by the formation of peculiar nano-ZrO_2 particles, which are stable until completion of the thermal treatment. These nano-ZrO_2 particles are stable during the elaboration of glass-ceramics, without any Zr~(4+) remaining in the glassy matrix of the final material.