Electrical properties of Cr2O3-Fe2O3-P2O5 glasses Part II

The electrical properties of xCr(2)O(3)-(40-x)Fe2O3-60P(2)O(5) 0 <= x <= 10 (mol%) glasses have been investigated by impedance spectroscopy In the glasses containing up to similar to 5 mol% Cr2O3 electrical conductivity increases due to the Increase in the Fe2+/Fe-tor ratio The conduction in these glasses is independent on Cr2O3 and it is controlled by the polaron hopping between iron ions The electrical conductivity of the partially crystallized sample with 10 mol% Cr2O3 slightly increases although the Fe2O3 content and the fraction of Fe2+ ions are smaller This effect is related to the formation of highly disruptive regions around the beta-CrPO4 and Fe-3(P2O7)(2) crystallites in the glass matrix of this sample These interconnected disruptive regions form the easy conductive pathways leading to a higher conductivity Changes in the dielectric permittivity in chromium Iron phosphate glasses are dependent on the Fe2+/Fe-tot ratio and therefore associated with the concentration of polarons related to Fe2+ and Fe3+ sites (C) 2010 Elsevier BV All rights reserved