TY - JOUR
T1 - A thermochemical study of glasses and crystals along the joins silica-calcium aluminate and silica-sodium aluminate
AU - Navrotsky, Alexandra
AU - Peraudeau, Gilles
AU - McMillan, Paul
AU - Coutures, Jean Pierre
N1 - Funding Information:
Acknowledgements-Thiws ork was supportedb y the U.S. NationalS cienceF oundation( Grant INT8006965a) nd the French C.N.R.S. The calorimetryf acility for work on sili-categ lassesre ceiveds upportf rom the U.S. Departmento f Enerav (Contract DE-ACU2-80ER10765)W. e thank Jim Clarcadd the Electron Microprobe Facihty for help with the analysesa nd Cohn Grahama nd Chris Capobiancof or technicala ssistancea nd stimulatingd iscussion.W e thank 0. J. Kleppa and J. Stebbinsf or helpful reviews.
PY - 1982/11
Y1 - 1982/11
N2 - Enthalpies of solution in molten 2PbO · B2O3 at 985 K are reported for series of glasses xCa0.5AlO2-(1-x)SiO2 (O ≤ x ≤ 0.99) and xNaAlO2-(1-x)SiO2 (0 ≤ x ≤ 0.56). The data are compared to values for the corresponding crystalline aluminosilicates and to preliminary data for systems containing KAlO2 and Mg0.5AlO2. The enthalpies of mixing of glasses become more exothermic with increasing basicity of the mono- or divalent oxide. The tendency toward immiscibility on the silica-rich side, indicated by the shape of the heat of mixing curve between x = 0 and x = 0.4, is pronounced in the calcium aluminate system, but not in the sodium aluminate system. The shape of the heat of mixing curve, which is roughly symmetrical about x = 0.5, can be rationalized in terms of glass structure by considering essentially random substitution of Si and Al on a continuous three dimensional tetrahedral framework, with stabilization arising from electrostatic interactions between aluminum and the nonframework cation balancing the destabilizing effects arising from perturbation of the aluminosilicate framework by the nonframework cation. These trends are consistent with the variation of physical properties of aluminosilicate melts.
AB - Enthalpies of solution in molten 2PbO · B2O3 at 985 K are reported for series of glasses xCa0.5AlO2-(1-x)SiO2 (O ≤ x ≤ 0.99) and xNaAlO2-(1-x)SiO2 (0 ≤ x ≤ 0.56). The data are compared to values for the corresponding crystalline aluminosilicates and to preliminary data for systems containing KAlO2 and Mg0.5AlO2. The enthalpies of mixing of glasses become more exothermic with increasing basicity of the mono- or divalent oxide. The tendency toward immiscibility on the silica-rich side, indicated by the shape of the heat of mixing curve between x = 0 and x = 0.4, is pronounced in the calcium aluminate system, but not in the sodium aluminate system. The shape of the heat of mixing curve, which is roughly symmetrical about x = 0.5, can be rationalized in terms of glass structure by considering essentially random substitution of Si and Al on a continuous three dimensional tetrahedral framework, with stabilization arising from electrostatic interactions between aluminum and the nonframework cation balancing the destabilizing effects arising from perturbation of the aluminosilicate framework by the nonframework cation. These trends are consistent with the variation of physical properties of aluminosilicate melts.
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U2 - 10.1016/0016-7037(82)90183-1
DO - 10.1016/0016-7037(82)90183-1
M3 - Article
AN - SCOPUS:0019923370
SN - 0016-7037
VL - 46
SP - 2039
EP - 2047
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 11
ER -