Ionic Transport Number of CaS–Na2S Solid Electrolytes

To obtain highly ionic conductor of sulfides, a solid solution of 95CaS-5Na 2 S was prepared by sintering the powder mixture of CaS and Na 2 S which has the NaCl type structure and the anti-fluorite structure, respectively. Two concentration cells using the solid solution as solid electolyte were constructed as follows. Fe, FeS|95CaS-5Na 2 S|Mn, MnS Ag, Ag 2 S|95CaS-5Na 2 S|Cu, Cu 2 S The reversibility of the measured e.m.f. was confirmed. The electromotive forces of the concentration cells were measured over the temperature range 670 to 1120K. Because the measured values for the concentration cells were close to theoretical values calculated using the Nemst equation, it is concluded that the ionic transference number of the solid solution, 95CaS-5Na 2 S, is close to one.