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A thermodynamic assessment of the liquid immiscibility in the BaO-TiO2-SiO2 system using the Ionic Two Sublattice model

par Boulay, Emilie ;Nakano, Jinichiro;Idrissi, H.;Schryvers, Dominick;Godet, Stéphane
Référence CALPAHD (2013: San Sebastian, Spain)
Publication Non publié, 2013

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Résumé :

Glass-ceramics in the BaO-TiO2-SiO2 system exhibit strong photoluminescence properties due to the fresnoite phase formation. This effect can be enhanced by controlling a prior amorphous phase separation, which promotes the formation of multiple interfaces [1]. The thermodynamic stability and metastability of the liquid phase in this system are critical information in order to design optimal compositions and processes of the glass exhibiting the maximum photoluminescence effect. However, the liquid phase in the BaO-TiO2-SiO2 system has never been assessed in the past and there is a lack of experimental data. Corresponding sub-binaries BaO-SiO2 and TiO2-SiO2 systems were evaluated using the Ionic Two Sublattice model. The assessments were conducted using the PARROT module of the Thermo-Calc software. Available experimental data from literature were evaluated to assess the thermodynamic parameters of these liquid phases by the CALPHAD method. A set of optimized parameters was obtained and calculated phase diagrams related to the stable and metastable liquid miscibility gaps as well as end-members in the BaO-SiO2 and TiO2-SiO2 are consistent with experimental data [2,3,4,5,6]. The BaO-TiO2 system has already been assessed using this model by Lu et al. [7]. Those assessments were then used in this present work to construct a ternary description of the BaO-TiO2-SiO2 system. The validity of liquidus projection interpolations into the ternary system by Muggianu’s model was investigated. It is shown that ternary interaction parameters are required to fit accurately ternary experimental data. Those data were obtained by using Electron Energy Loss Spectroscopy (EELS) in a TEM for some specific glass compositions in order to determine experimentally tie-lines in the miscibility gap. [1] H. Hijiya, T. Kishi and A. Yasumori, J.of the Ceram. Soc.of Japan. 116, 255-1259 (2008).[2] P. James and A. Ramsden. J. of Materials Science. 19, 1406-1419 (1984).[3] A. Romero-Serrano, A. Cruz-Ramirez, B. Zeifert, M. Hallen-Lopez and A. Hernandez-Ramirez. Glass Phys. and Chem. 36, 171-178 (2010).[6] Z.Tyurnina, S. Lopatin and V.Stolyarova. Russian J.of Gen. Chemistry. 76, 1522-1530 (2006).[5] M. Kirschen and C. DeCapitani. Eur.J.Mineral. 11, 427-440 (1999).[6] R. DeVries, R. Roy and E. Osborn. Trans. Br. Ceram. Soc. 53, 525-540 (1954).[7] X. Lu and Z. Jin. Calphad. 24, 319-338 (2000).