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 298–433K 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 336/319K on heating/cooling) the crystal arrangement appears to be within the triclinic symmetry with P-1 space group. During heating in the 336–339K region (and 319–337K on cooling) the crystal exists in the phase II, characterized by monoclinic symmetry with P21/c space group. Consequently, above 339K (during heating, and 337K 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 0.23eV 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).