Co-cation conduction in solid solutions (K1-xRbx)(4)P2O7 (M = Ca, Sr, Cd, Ba): Dependence on the nature and concentration of cations M2+

Solid solutions of the structure gamma -K4P2O7, which have the composition (K1-xRbx)(3.8)M0.1P2O7 (M = Ca, Sr, Cd, Ba) and (K1-xRbx)(4-2y)CayP2O7 (y = 0.025-0.20), are synthesized. The solutions' electroconductivity is studie d in the temperature range 400-600 degreesC. The concentration dependences of the conductivity and the activation energy for conduction have extremums at x = 0.6, which points to the polyalkaline effect. The effect increases with decreasing radius of cation M2+ and with increasing concentration of c alcium cations, which is explained by an increased energy nonequivalence of positions in the cation sublattice accessible to alkali ions.