Ceramics-Silikáty 55 (2) 114-122 (2011)

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

S.M. Salman, S.N. Salama

The crystallization characteristics of glasses based on lithium iron silicate (LiFeSi₂O₆)-diopside (CaMgSi₂O₆) composition with addition of Al₂O₃ at the expense of Fe₂O₃ were described. The effect of LiInSi₂O₆/CaMgSi₂O₆ replacements was also investigated. The thermal treatment, the crystal phases, and the micro-structural properties of (LiFeSi₂O₆–CaMgSi₂O₆) glasses, replacing partial Fe₂O₃ with Al₂O₃ and partial CaMgSi₂O₆ with LiInSi₂O₆, have been studied by a differential thermal analysis, an X-ray diffraction, and a scanning electron microscopy. The glasses show the intense uniform bulkcrystallization with the fine grained microstructure by increasing the replacement of Al₂O₃/Fe₂O₃ and LiInSi₂O₆/CaMgSi₂O₆. The crystallizing phases of Ca(Fe,Mg)(SiO₃)₂, a-LiFe5O8, Li₂SiO₃, a-SiO₂ and CaMgSi₂O₆ are mostly formed together, in most case, with Li_0.6Al_0.6Si_2.4O₆, β-eucryptite solid solution, LiInSi₂O₆, In₂Si₂O₇, and LiFeSi₂O₆. The Al₂O₃ partial replacement increases the transformation temperature (T_g) and softening one (T_s) for the glasses and the glass-ceramics, and decreases the thermal expansion coefficient (a-value) for the glasses. The LiInSi₂O₆ partial replacement decreases T_g and T_s and increases the a-value for the glasses, while the Al₂O₃ and LiInSi₂O₆ partial replacements decrease the a-value for the glassceramics. The crystallization characters of the glasses are correlated to the internal structure, as well as role played by the glass-forming cations. However, the one of the glass-ceramics are mainly attributed to the crystalline phases formed in the material.

Keywords: In₂O₃-containing glass, Crystallization, Thermal expansion