Mechanism of ionic transport in cesium-conducting solid electrolytes based on cesium orthophosphate

The earlier obtained data on the transport properties of cesium-conducting solid electrolytes based on cesium orthophosphate in the Cs_3–2xM_x^II PO₄ (M^II = Mg, Ca, Sr, Ba), Cs_3–3x PO₄ (M_x^III = Sc, Y, La, Sm, Nd) and Cs_3–xP_1–xZ_x^VI O₄ (Z = S, Cr, Mo, W) systems are analyzed. It is shown that, in addition to the conventional jump mechanism, the “paddle wheel” mechanism can play an important role in the ionic transport. This mechanism is associated with the orientation disordering of [PO₄] tetrahedrons at the elevated temperatures, which leads to their rotation promoting “pushing” cesium ions into the accessible neighboring positions.