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In an effort to interlink the thermo chemical and thermo physical properties of slags, the present work was undertaken to derive the molar volumes of complex slags from the enthalpies of mixing of the corresponding slags. As a first step, binary systems of the following oxides were investigated; Al2O3, CaO, FeO, MgO, MnO, and SiO2. An empirical correlation was derived between the enthalpies of mixing and molar volumes. A comparison of the computed results on the basis of the above relationship with the experimental data on molar volumes available in literature shows that the agreement between the calculated results and measured densities is satisfactory in the case of most of the binary systems, within the limits of experimentally uncertainties. The advantage of the present approach is that it would enable prediction of molar volumes of slags that are compatible with the thermodynamic data available., QC 20100525

The structure of sodium tetrasilicate (Na2Si4O9) glass and melt was studied in the range from 300 to 950 K by neutron diffraction. Increasing temperature leads to gradual decrease of the peak intensities in the static structure factors possibly with a change in the slope at the glass transition temperature (T g≅773 K), but no shift and broadening of the peaks is observed. Especially, the position of the first sharp diffraction peak (FSDP) at 1.6 Å–1 remains constant in the whole temperature range studied. The corresponding pair correlation functions g(r) are very similar at all temperatures. Only a slight broadening of the Si-O and O-O first nearest-neighbour peaks with temperature is observed, which can be attributed to temperature enhanced dynamic distortions of the SiO4 tetrahedra. All these results suggest that there is little change not only in the short- but also in the medium-range order of the sodium tetrasilicate glass and melt around the glass-liquid transition.