Co-cation conduction of the (Na1-xKx)(3.8)M0.1P2O7 (M = Ca, Sr, Cd) solid solutions

Samples of systems (Na1-xKx)(3.8)M0.1P2O7 (M = Ca, Sr, Cd; 0 less than or e qual to n less than or equal to 1) are synthesized It is established that s olid solutions with the structure of gamma-K4P2O7 form in these systems. At room temperature, the solutions exist at x greater than or equal to 0.7. I n the calcium-containing system, they form a continuous series at temperatu res exceeding similar to 500 degrees C. The co-cation character of conducti on of the solutions is confirmed by measured transport numbers. The concent ration dependences of the electroconductivity and its activation energy poi nt to a polyalkali effect, which decreases with an increase in the M2+ ion radius. Partial conductivities of sodium and potassium cations in the (Na1- xKx)(3.8)Ca0.1P2O7 system are calculated and their dependences on the balan ce between alkali cations in the solid solution are discussed.