Electronic and Ionic Conduction in (AgxCu1-x)2Se

The phase diagram is studied by X-ray and thermal analyses. The high temperature phase (α) is the solid solution of b.c.c. or f.c.c. in which Ag + , Cu + and electron are mobile. The galvanic cell Ag|AgI|specimen|Pt is available to controle the excess or deficit Ag density and to detect the electrochemical potential of Ag + , since the interdiffusion of Cu + into AgI is nearly forbidden except near Cu 2 Se. With the help of the cell and utilizing the weight-difference between Ag and Cu, the polarization and the interdiffusion are measured and interpreted with the diffusion theory. The electronic and ionic conductivities are measured with varying temperature and x . Further the various properties of α(Ag, Cu) 2 Se such as the conductivity, Hall coefficient, thermoelectric power, thermal conductivity etc. are measured and compared with the theory, indicating that the energy gap decreases with increasing x .