Electronic conductivity in Na2O-FeO-P2O5 glasses

dc and ac conductivity were studied in 50P(2)O(5)-(50-x)FeO-xNa(2)O and 50P(2)O(5)-(50-x)FeO-xCaO (7<20; in mol%) glasses. It is shown that the replacement of CaO by Na2O caused rather small increase in dc and ac conductivity. The conduction in these glasses is predominantly electronic controlled by electron hopping between Fe(II) and Fe(Ill) sites. Internal friction has been used to study the relaxation phenomena caused by electronic and ionic migration in sodium-iron phosphate glasses. Two peaks attributed to these processes were observed on internal friction spectra in the temperature range of 125-500 K at a frequency of about I Hz. (C) 2002 Elsevier Science B.V. All rights reserved.