Na-Ion conduction in the solid solutions of Na3PO4/Na2SO4 and Na3AlF6/Na2SO4

The ionic conductivity of the solid solutions Na 3 PO 4 /Na 2 SO 4 and Na 3 AlF 6 /Na 2 SO 4 has been measured. The sodium ion conduction is enhanced and the activation energy is lowered on doping. There is indirect evidence that in the mixed crystals with high temperature Na 3 PO 4 structure the rotational motion of the complex anions contributes to the Na-ion mobility.