1979/05/15 by S. Geller, James R. Akridge, S. A. Wilber · 2 citations
Chemical Engineering · Chemistry · Engineering · Materials Science · #Advanced Battery Materials and Technologies #Chemistry #Crystal structure #Crystallography #Ion #Ionic liquids properties and applications #Isostructural #Materials science #Omega #Physics #Quantum mechanics #Thermal Expansion and Ionic Conductivity
paper · doi:10.1103/physrevb.19.5396
openalex publication_date 1979/05/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/26
Crystals of the solid electrolyte RbCu4Cl3I2 are isostructural with RbAg4I5. The crystal of RbCu4Cl3I2 on which the structure analysis was done belongs to space group P4332 (O6) with lattice constant 10.032\ifmmode±\else\textpm\fi0.003 \AA. As in RbAg4I5, there are three sets of tetrahedral sites for the charge carriers with a total of 56 sites. In RbCu4Cl3I2, all the tetrahedra have both Cl^\ensuremath- and I^\ensuremath- ions at apices, but the coordination polyhedron about the Rb+ ions contain only Cl^\ensuremath- ions. The room-temperature distribution of charge carriers differs from that in RbAg4I5. Although the occupancies of the two sets of 24-fold sites are almost equal, that of the eightfold sites is still very low and thus overall the distribution is nonuniform. Room-temperature conductivities as high as 0.44 \mathrm\ensuremathΩ^\ensuremath-1 cm^\ensuremath-1 have been measured directly on a specimen having only 94% of theoretical density. Thus it is probable that the true electrolytic conductivity exceeds at least 0.47 \mathrm\ensuremathΩ^\ensuremath-1 cm^\ensuremath-1. At the temperature of the transition of AgI to \ensuremathα-AgI, 419 K, the minimum value of the conductivity of RbCu4Cl3I2 is 1.53 \mathrm\ensuremathΩ^\ensuremath-1 cm^\ensuremath-1, about 17% higher than that of \ensuremathα-AgI at the transition. Thus RbCu4Cl3I2 has the highest conductivity of any solid electrolyte over a wide temperature range in the lower-temperature regions. Conductivity measurements between 130 and 383 K indicate that the \ensuremathα\ensuremath-\ensuremathβ transition occurs at 221 K and a \ensuremathβ\ensuremath-\ensuremathγ transition at 170 K; the nature of the latter differs from that of the RbAg4I5 \ensuremathβ\ensuremath-\ensuremathγ transition. There is evidence that the average mobility of the Cu+ ion is higher than that of the Ag+ ion.