Structure and magnetic properties of Bi2O3-GeO2-Gd2O3 glasses

In this paper we present a characterisation of the local structure and magn etic properties of glasses in the xGd(2)O(3).(100 - x) [Bi2O3. GeO2] system by using infra-red (IR), electron paramagnetic resonance (EPR) and magneti c susceptibility measurements. The IR spectra indicate that the bismuth and germanium environments in the Bi2O3. GeO2 base glass are not strongly pert urbed by gadolinium incorporation up to 30 mol% Gd2O3 The EPR spectra of th e samples investigated reveal resonance sites with an unexpectedly high cry stalline field in addition to the "U" spectrum, typical for Gd3+ ions in di sordered systems. Magnetic susceptibility measurements indicate a Curie typ e behaviour for x less than or equal to 3 mol% and above this concentration a Curie-Weiss type behaviour. A model for the gadolinium distribution in b ismuth-germanate glasses is suggested, which is consistent with these resul ts. (C) 2000 Elsevier Science Ltd. All rights reserved.