Conductivity of Grains and Grain Boundaries in Polycrystalline Heteropoly Acid Salts
In our previous work we investigated the conductivity and dielectric relaxation phenomena in heteropoly acids and their salts. In this work, we have studied the conductivity of grains and grain boundaries in compressed powders of 12-tungstophosphoric acid (WPA) salts with univalent and bivalent ions. The method of impedance spectroscopy has been employed in the frequency range from 5 Hz to 500 kHz. We obtained grains and grain boundaries conductivities as well as corresponding activation energies. Grain conductivity in all investigated salts is always higher than the grain boundary conductivity.
Dragan P. Uskokovic, Slobodan K. Milonjic, Djan I. Rakovic
B. Škipina et al., "Conductivity of Grains and Grain Boundaries in Polycrystalline Heteropoly Acid Salts", Materials Science Forum, Vol. 494, pp. 101-106, 2005