Structural role of Zr4+ as a nucleating agent in a MgO–Al2O3–SiO2 glass-ceramics: A combined XAS and HRTEM approach - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Non-Crystalline Solids Année : 2010

Structural role of Zr4+ as a nucleating agent in a MgO–Al2O3–SiO2 glass-ceramics: A combined XAS and HRTEM approach

Résumé

The environment around Zr4+ is studied at the Zr K-edge in a MgO–Al2O3–SiO2 glass-ceramics heat treated along its very first crystallization steps. The heat treatments were calibrated by differential scanning calorimetry. ZrO2 acts as a nucleating agent, adding a nucleation/crystallization event around 920 °C, less than 100 °C above the glass transition temperature (830 °C) and below the massive crystallization of the parent-glass (~1015 °C). It also lowers crystallization temperatures of the matrix as compared with a Zr-free sample. High-resolution transmission electron microscopy imaging allows an unambiguous attribution to tetragonal ZrO2 for, at least, some of the very first detectable crystallites. Zr K-edge extended X ray absorption fine structure analysis shows a peculiar surrounding around Zr4+ in the parent glass, composed of Si (Mg,Al) and Zr sites linked by edge sharing. This indicates direct linkages between Zr sites, pre-existing in the glass structure that play a key role for promoting nucleation. This analysis is in agreement with only a small part of Zr4+ evolving during the first steps of nucleation toward the formation of few nano-crystals of tetragonal (ZrO2).

Domaines

Minéralogie
Fichier non déposé

Dates et versions

hal-00568835 , version 1 (23-02-2011)

Identifiants

  • HAL Id : hal-00568835 , version 1

Citer

Olivier Dargaud, Laurent Cormier, N. Menguy, Laurence Galoisy, Georges Calas, et al.. Structural role of Zr4+ as a nucleating agent in a MgO–Al2O3–SiO2 glass-ceramics: A combined XAS and HRTEM approach. Journal of Non-Crystalline Solids, 2010, 356, pp.2928-2934. ⟨hal-00568835⟩
106 Consultations
0 Téléchargements

Partager

Gmail Facebook X LinkedIn More