CRYSTALLISATION AND THERMAL EXPANSION CHARACTERISTICS OF In2O3-CONTAINING LITHIUM IRON SILICATE-DIOPSIDE GLASSES

• Published in: Ceramics (Praha) Vol. 55; no. 2; pp. 114 - 122
• Main Authors: Salman, S M, Salama, S N
• Format: Journal Article
• Language: English
• Published: University of Chemistry and Technology, Prague 01.01.2011
• Subjects: Aluminum oxide; Crystallization; Glass; Glass ceramics; In2O3-containing glass; Iron; Lithium; Microstructure; Thermal expansion
• ISSN: 0862-5468; 1804-5847

The crystallisation characteristics of glasses based on lithium iron silicate (LiFeSi2O6)-diopside (CaMgSi2O6) composition with addition of Al2O3 at the expense of Fe2O3 are described. The effect of LiInSi2O6/CaMgSi2O6 replacements was also investigated. The thermal treatment, crystal phases, and microstructure of (LiFeSi2O6-CaMgSi2O6) glasses, replacing partial Fe2O3 with Al2O3 and partial CaMgSi2O6 with LiInSi2O6, were studied by DTA, XRD and SEM. The glasses show intense uniform bulk crystallisation with a fine grained microstructure by increasing the replacement of Al2O3/Fe2O3 and LiInSi2O6/CaMgSi2O6. The crystallising phases of Ca(Fe,Mg)(SiO3)2, alpha-LiFe5O8, Li2SiO3, alpha-SiO2 and CaMgSi2O6 are mostly formed together, in most cases, with Li0.6Al0.6Si2.4O6, beta-eucryptite solid solution, LiInSi2O6, In2Si2O7, and LiFeSi2O6. The Al2O3 partial replacement increases the transformation temperature (Tg) and softening one (Ts) for the glasses and the glass-ceramics, and decreases the thermal expansion coefficient (alpha-value) for the glasses. LiInSi2O6 partial replacement decreases Tg and Ts and increases the alpha-value for the glasses, while Al2O3 and LiInSi2O6 partial replacements decrease the alpha-value for the glass-ceramics. The crystallisation of the glasses is correlated to the internal structure, as well as the role played by the glass-forming cations.