Structure, dielectric and electric properties of diisobutylammonium hydrogen sulfate crystal

Abstract Diisobutylammonium hydrogen sulfate, a new organic-inorganic hybrid compound, was successfully synthesized and three structural phases in 298–433 K temperature range were revealed by differential scanning calorimetry and X-ray powder diffraction studies. Single crystal X-ray diffraction data were used to describe the crystal structures in each particular case. In phase III (below 336/319 K on heating/cooling) the crystal arrangement appears to be within the triclinic symmetry with P -1 space group. During heating in the 336–339 K region (and 319–337 K on cooling) the crystal exists in the phase II , characterized by monoclinic symmetry with P 2 1 / c space group. Consequently, above 339 K (during heating, and 337 K during cooling temperature sequences), i.e. in phase I the crystal exhibits orthorhombic symmetry ( Cmce space group). Ferroelastic domain structure was observed in phase III . These phase boundaries ( III → II and II → I ) were accompanied by the presence of small anomalies, apparent in the dielectric permittivity and electric conductivity experimental data. Fast proton transport with activation energy of 0.23 eV was observed in the high temperature phase I and related to phonon assisted proton diffusion conditioned by disorder of diisobutylammonium ( diba ) cations, as well as by high thermal displacements of oxygen and sulfur atoms of hydrogen sulfate anion ( hs ).