Transport and structural properties of (1 − x)CsHSO4–xKH2PO4 mixed compounds

Proton conductivity, thermal and structural properties of (1 − x)CsHSO4–xKH2PO4 mixed salts in a wide range of compositions (x = 0.05–0.95) has been studied. Two new phases with different crystalline structures, transport and thermal properties have been found in the system. New highly conductive phase with a Cs3(HSO4)2(H2PO4) (C2/c) structure is formed at x = 0.05–0.5 with the conductivity at low-temperatures more than two orders of magnitude higher than that of the source salts. At higher x (x = 0.6–0.9) another phase with the CsH5(PO4)2 (P21/c) crystalline structure is formed. This phase has lower thermal stability, relatively low proton conductivity and high activation energy.