Fast proton conduction in Cs3(HSO4)2(H2PO4) and Cs4(HSO4)3(H2PO4)

Crystal structure, hydrogen bonds and thermal transformations of superprotonic conductor Cs6(SO4)3(H3PO4)4

“…The superprotonic state of these crystals is a mixture of cubic and tetragonal phases in the space groups Pm3m and I4 1 /amd, respectively. Upon cooling, the combination of the two phases disappears, giving the initial monoclinic C2/c structure, as shown by synchrotron powder diffraction studies (Mikheykin et al, 2017). The transformation from the low-temperature monoclinic phase to the two-phase mixture may be one of the reasons for the appearance of granularity in the samples and that resulted in the formation of powder rings observed on the diffraction patterns of heat-treated single-crystal samples.…”

“…Structural modifications of samples can occur with increasing temperature, i.e. the formation of new superprotonic compounds (Makarova et al, 2014) or the multiphase composite state with co-existing conducting and nonconducting phases (Mikheykin et al, 2017). From the viewpoint of practical application, such as the production of various electrochemical devices, the stability of phases with high proton conductivity is a very important issue, which is debated in a number of works (see, for example, Lee, 1996;Ortiz et al, 1999;Park, 2004;Ortiz et al, 2006;Choudhury et al, 2021).…”

Features of the crystal structure and surface of superprotonic conductor caesium hydrogen sulfate phosphate

“…This work is a continuation of our studies of superprotonic crystals M m H n (AO 4 ) (m+n)/2 •yH 2 O (M = K, Rb, Cs, NH 4 ; AO 4 = SO 4 , SeO 4 , HPO 4 , HAsO 4 ) by methods of structural analysis using X-ray, synchrotron radiation and neutrons. These studies also include complex caesium hydrogen sulfate phosphates Makarova, Selezneva et al, 2016;Mikheykin et al, 2017;Makarova et al, 2021;Komornikov et al, 2023), as well as the research of the real structure of the members of this family using electron and atomic force microscopy (Gainutdinov et al, 2021(Gainutdinov et al, , 2023Selezneva et al, 2023) in order to reveal regular relationships between their composition, structure and physical properties.…”