On ion transport mechanism in K+-conducting solid electrolytes based on K3PO4

Data on transport properties of potassium conducting solid electrolytes based on K3PO4 in the systems K3 − 2xMxPO4 (M = Mg, Ca, Sr, Ba, Zn, Cd, Pb) and K3 − xP1 − xExO4 (E = S, Cr, Mo, W) have been analyzed. The results indicate that, in addition to the usual hopping mechanism, a substantial significance for ion transport in similar phases belongs to the “paddle wheel” mechanism. This mechanism is due to orientation disorder of the PO4 tetrahedra at elevated temperatures, which promotes moving K+ ions to the neighboring vacant positions.