Vibrational study, phase transitions and electrical properties of 4-benzylpyridinium monohydrogenselenate

Abstract The title compound C 6 H 5 CH 2 C 5 H 4 NH + ·HSeO 4 − crystallizes in the orthorhombic system with the space group Pbca and the following unit cell dimensions: a =27.449(5) A; b =10.821(6) A and c =8.830(1) A. The structure consists of infinite parallel two-dimensional planes built of HSeO 4 − anions and C 6 H 5 CH 2 C 5 H 4 NH + cations mutually. Differential scanning calorimetry study on 4-benzylpyridinium monohydrogen-selenate was carried out. A high temperature second order phase transition at 363 K was found and characterized by electric measurements. The Raman of polycrystalline sample has been recorded at different temperature between 297 and 373 K. The conductivity relaxation parameters associated with some H + conduction have been determined from an analysis of the M′′/M′′ max spectrum measured in a wide temperature range. An appearance of the superionic phase transition in 4-BSe is closely related to a liberation or even a rotation increase of HSeO 4 − groups with heating.