Determination of the Partial Contributions to the Electrical Conductivity of TiO2-SiO2-Al2O3-MgO-CaO Slags: Role of the Experimental Processing Conditions
Samuel Martín-Treceño, Antoine Allanore, Catherine M. Bishop, Matthew J. Watson, Aaron T. Marshall
Abstract
Abstract The electrical transport properties of molten TiO 2 –SiO 2 –Al 2 O 3 –MgO–CaO slags were determined as a function of temperature and oxygen partial pressure. To avoid the corrosion of crucible materials by this slag at ultra high temperatures, the pendant droplet technique was used inside a modified floating zone furnace. Electronic and ionic transference numbers were estimated using stepped-potential chronoamperometry experiments to quantify the contribution of the electronic/ionic conductivity to the total electric conductivity. The results show that these slags are mixed conductors, where current is carried by ionic and electronic carriers. The oxygen partial pressure dependence of the electronic transference numbers, $$t_e$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>t</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> , indicated a semiconducting mechanism in the molten slag. The ratio of the different valences of the transition metal ions had a predominant effect on the $$t_e$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>t</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:math> . The $${{\text{TiO}}_{2}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>TiO</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:math> content also favoured electronic conduction, while the effect of temperature and structure was less noticeable within the temperature and composition range studied.