resumo
This article aims to shed some light on the structure and thermo-physical properties of lithium disilicate glasses in the system Li2O-SiO2-Al2O3-K2O. A glass with nominal composition 23Li(2)O-77SiO(2) (mol%) (labelled as L23S77) and glasses containing Al2O3 and K2O with SiO2/Li2O molar ratios (3.13-4.88) were produced by conventional melt-quenching technique in bulk and frit forms. The glass-ceramics (GCs) were obtained from nucleation and crystallisation of monolithic bulk glasses as well as via sintering and crystallisation of glass powder compacts. The structure of glasses as investigated by magic angle spinning-nuclear magnetic resonance (MAS-NMR) depict the role of Al2O3 as glass network former with four-fold coordination, i.e., Al(IV) species while silicon exists predominantly as a mixture of Q (3) and Q (4) (Si) structural units. The qualitative as well as quantitative crystalline phase evolution in glasses was followed by differential thermal analysis (DTA), X-ray diffraction (XRD) adjoined with Rietveld-reference intensity ratio (R.I.R.) method, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The possible correlation amongst structural features of glasses, phase composition and thermo-physical properties of GCs has been discussed.
palavras-chave
ALUMINOSILICATE; NMR
categoria
Thermodynamics; Chemistry
autores
Fernandes, HR; Tulyaganov, DU; Goel, A; Ferreira, JMF
nossos autores
Hugo Alexandre Gonçalves da Rocha Fernandes
Investigador
José Maria da Fonte Ferreira
Professor Associado com Agregaçãoagradecimentos
Hugo R. Fernandes is grateful for the financial support of CICECO and for the PhD grant (SFRH/BD/41307/2007) from the FCT, Portugal. Ashutosh Goel is thankful to CICECO and FCT, Portugal (SFRH/BPD/65901/2009) for the post-doctoral research grant.