Fast ionic conductivity of ternary iodides in the systems LiIMIII2 (MIIMn, Cd, Pb)

Abstract The phase relationships and electric conductivities of the ternary iodide systems LiIM II I 2 (M II Mn, Cd, Pb) have been studied by high-temperature X-ray measurements and impedance spectroscopy methods. Whereas mutual solubility of LiI and MnI 2 is negligible at any temperature deficient NaCl-type mixed crystals Li 1− x M 0.5 x II I (M II Mn, Cd, Pb) are formed at temperature above 540 K, which, however, cannot be quenched to ambient temperature. The solid solutions obtained exhibit high ionic conductivity, e.g. 1×10 −1 , 3×10 −2 and 7×10 −2 Ω −1 cm −1 at 570K for materials like Li 2 CdI 4 , Li 2 PbI 4 , and Li 4 PbI 6 , respectively.