The influence of monovalent and bivalent cations on the electrical properties of 12-Tungstophosphoric acid salts

摘要

The effect of monovalent and bivalent cations on some electrical properties of 12-tungstophosphoric acid (WPA) salts were studied. The charge carriers in this acid are protonic entities such as H+, OH- and various forms of hydrated proton H(H2O)(n)(+). Conductivity, dielectric relaxations and activation energies of WPA were investigated. Permittivity measurements were performed on pressed polycrystalline pellets at lower frequencies (5 Hz-500 kHz) and in the X-band microwave range (8-12 GHz); the temperature interval was from room temperature to 360 K. In the microwave region, WPA hexahydrate (WPA-6) and some IATA salts exhibit one, two or three relaxations of the Debye type. Their relaxation times of the order of 10(-11) s are attributed to the fast reorientation of water molecules and/or fast reorientation of oxonium ions (H3O+). In the lower frequency interval, dielectric relaxations of WPA-6 and some IATA salts with longer relaxation times of the order of 10(-7)-10(-5) s were registered and assigned to ion (H+ and/or H3O+) and cation jumps. (c) 2005 Elsevier B.V. All rights reserved.