Formation of a zirconium oxide crystal nucleus in the initial nucleation stage in aluminosilicate glass investigated by X-ray multiscale analysis
Yohei Onodera, Yasuyuki Takimoto, Hiroyuki Hijiya, Qing Li, Hiroo Tajiri, Toshiaki Ina, Shinji Kohara
Abstract
Abstract Understanding the nucleation mechanism in glass is crucial for the development of new glass-ceramic materials. Herein, we report the structure of a commercially important glass-ceramic ZrO 2 -doped lithium aluminosilicate system during its initial nucleation stage. We conducted an X-ray multiscale analysis, and this analysis was used to observe the structure from the atomic to the nanometer scale by using diffraction, small-angle scattering, absorption, and anomalous scattering techniques. The inherent phase separation between the Zr-rich and Zr-poor regions in the pristine glass was enhanced by thermal treatment without changing the spatial geometry at the nanoscale. Element-specific pair distribution function analysis using anomalous X-ray scattering data showed the formation of a liquid ZrO 2 -like local structural motif and edge sharing between the ZrO x polyhedra and (Si/Al)O 4 tetrahedra during the initial nucleation stage. Furthermore, the local structure of the Zr 4+ ions resembled a cubic or tetragonal ZrO 2 crystalline phase and formed after 2 h of annealing the pristine glass. Therefore, the Zr-centric periodic structure formed in the early stage of nucleation was potentially the initial crystal nucleus for the Zr-doped lithium aluminosilicate glass-ceramic.