Dielectric investigation of electrical conductivity in the copper salt of the 12-tungstophosphoric acid hydrate

The electrical and dielectric properties of the copper salt of 12-tungstophosphoric acid (WPA) hydrate have been investigated by broadband dielectric relaxation spectroscopy (DRS). This work is a continuation of our previous investigations on the influence of monovalent and bivalent cations on the dielectric properties of WPA hydrates salts. Measurements were made in the frequency range 10 mHz-1 MHz in order to explore the long-range dynamics, following recent microwave measurements aiming at the local dynamics properties. Experiments were done in the temperature interval 293-350 K. Data treatment included complex permittivity epsilon*, complex electric modulus M* and complex impedance Z* formalism, Arrhenius diagram and Cole-Cole diagrams. The results are discussed in terms of conductivity relaxation and conductivity current relaxation. Rather long conductivity relaxation times measured seem to correspond to ion jumping processes. A phase transition was observed at 323 K. (C) 2003 Elsevier B.V. All rights reserved.