Structure and magnetic properties of Bi2O3–GeO2–Gd2O3 glasses

In this paper we present a characterisation of the local structure and magnetic properties of glasses in the xGd2O3·(100−x)[Bi2O3·GeO2] system by using infra-red (IR), electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. The IR spectra indicate that the bismuth and germanium environments in the Bi2O3·GeO2 base glass are not strongly perturbed by gadolinium incorporation up to 30 mol% Gd2O3. The EPR spectra of the samples investigated reveal resonance sites with an unexpectedly high crystalline field in addition to the “U” spectrum, typical for Gd3+ ions in disordered systems. Magnetic susceptibility measurements indicate a Curie type behaviour for x≤3 mol% and above this concentration a Curie–Weiss type behaviour. A model for the gadolinium distribution in bismuth–germanate glasses is suggested, which is consistent with these results.