Influences of Na_2O, K_2O and Li_2O Additions on Electrical Conductivity of CaO-SiO_2-(Al_2O_3) Melts

摘要

The influences of Na_2O, K_2O and Li_2O additions on the electrical conductivity of CaO-SiO_2-(Al_2O_3) melts are investigated by the four-electrode method. It is concluded that the electrical conductivity monotonously increases as increasing R_2O (R = Li, Na, K) content at a fixed CaO/SiO_2 ratio of 1.1. As gradually substituting Na_2O or K_2O for Li_2O, respectively, the mixed alkali effect occurs, and there is a minimum value of electrical conductivity. Furthermore, the presence of Al_2O_3 promotes the mixed alkali effect. Raman spectroscopy is used to illustrate the relationship between electrical conductivity and melt structure. The electrical conductivity decreased with the increase of the degree of polymerization of melt.