resumo
We report on the structure and crystallization behaviour of four enstatite based glasses. Two glasses with nominal compositions of Y0.125Mg0.875Si0.875B0.125O3 and Y-0.125Mg0.725Ba0.15Si0.875B0.125O3 were prepared as parent glasses while the other two glasses were derived by the addition of 8 wt.% Al2O3 to the parent glass compositions, respectively. Structural features of the glasses were accessed by Fourier transform infrared spectroscopy (FTIR). Non-isothermal crystallization kinetics and thermal stability of Al2O3-free glasses were studied using differential scanning calorimetry (DSC). It has been shown that these glasses exhibit higher activation energy of viscous flow and are prone to surface crystallization. Activation energy of crystallization decreases with the addition of BaO in the glasses. Crystallization behaviour of all the experimental glasses in the temperature range of 800-1000 degrees C was followed by X-ray diffraction (XRD) and FTIR. Clinoenstatite and orthoenstatite were the major crystalline phases in the BaO-free glass-ceramics while BaO-containing compositions featured the early formation and stabilization of protoenstatite. (C) 2008 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
palavras-chave
SB-SE GLASSES; CHALCOGENIDE GLASSES; PHASE-CHANGE; KINETICS; CERAMICS; ENSTATITE; MICROSTRUCTURE; POLYMORPHISM; TRANSITION
categoria
Materials Science
autores
Goel, A; Tulyaganov, DU; Shaaban, ER; Knee, CS; Eriksson, S; Ferreira, JMF
nossos autores
José Maria da Fonte Ferreira
Professor(a) Jubilado(a)agradecimentos
This study was financially supported by FCT, Portugal (Ashutosh Goel, Project no. SFRH/BD/37037/2007) and Swedish Institute, Sweden. Authors would also like to thank Ms. Annika. Eriksson for her assistance in performing XRD and DSC experiments.