Conductivity and dielectric behaviour of iron sodium phosphate glasses

Glasses of the composition (Na2P2O6)(100-x) (Fe2O3)(x), with x = 5, 10, 20 and 25 mol%, have been prepared. The alternating current conductivity, the dielectric permittivity and the loss were measured in the frequency range 0.12-10(2) kHz and in the temperature range 323-623 K. The results show that the contribution of the electronic conduction to the conductivity decreases with decreasing iron concentration. The electronic conduction is possibly due to hopping of an electron from the lower valance state of Fe2+ to the higher valance state of Fe3+ ions. The results of the dielectric permittivity show that no maximum was observed in the temperature and frequency range studied. This absence is an indication of non ferroelectric behaviour of all the samples. However, the thermal activated relaxation mechanism dominates the observed relaxation behaviour. The distribution of the relaxation processes was also studied, and three processes were adequate to describe the present results. (C) 2001 Published by Elsevier Science B.V.