Structural fluctuations and role of Ti as nucleating agent in an aluminosilicate glass

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• 作者：Marie Guignard ; Laurent Cormier ; Valé ; rie Montouillout ; Nicolas Menguy ; Dominique Massiot
• 关键词：Aluminosilicates A165 ; Atomic structure A247 ; Crystal nucleation C2865
• 刊名：Journal of Non-Crystalline Solids
• 出版年：2010
• 出版时间：1 June 2010
• 年：2010
• 卷：356
• 期：25-27
• 页码：1368-1373
• 全文大小：1022 K

文摘

Nucleation is the initiating event for the formation of any crystal from undercooled melt. Although the classical nucleation theory describes qualitatively many aspects of the crystallization process, the mechanisms favoring the first steps of nucleation are still unknown and required the full identification of the catalytic sites. In this work, we report a structural investigation of the system 2MgO–2Al₂O₃–5SiO₂ + TiO₂, a major glass–ceramic for scientific and industrial interest, in order to understand the structural influence of Ti as a nucleating agent. X-ray scattering and ²⁷Al Nuclear Magnetic Resonance studies were carried out on 2MgO–2Al₂O₃–5SiO₂ + xTiO₂ glasses, with 0 mol %  ≤ x ≤ 15.5 mol % .

No evidence of phase separation can be detected in the initial glasses by Transmission Electron Microscopy at nanoscale and Ti atoms appear to be homogeneously distributed within the glassy structure. We explain that the presence of TiO₂ favors nucleation by the formation in the initial glass of high-coordinated Al species and the presence of structural fluctuations that mimic the initial crystalline phase precipitating in the glass. The understanding of the parent glass structure appears as a critical constraint to understand the pathways promoting nucleation.