Solubility of chromium oxide in binary soda-silicate melts

The total chromium oxide (Cr2O3) solubility is measured in the liquids belonging to the Na2O–SiO2 system using a thermochemical reactor which allows the independent control of temperature (1125 °C < T < 1250 °C), glass composition (1.5 < x < 3) and oxygen fugacity (−15 < log fO2 < −0.61). The contribution of each chromium species (Cr(II), Cr(III) and Cr(VI)) and the total Cr content dissolved in the melt are determined using a model describing the chromium chemistry in melts involving dissolution, redox and oxo-complex reactions. A manipulation of the obtained results allows the determination of the physicochemical properties of chromium species in melts (chromium complex formulas) as well as thermodynamic properties (entropies and enthalpies) related to the dissolution, reduction and oxidation processes of chromium oxide in binary melts.