Effect of Gadolinium on the Structure and Magnetic Properties of Glass and Glass-Ceramic Sillenites

Glass samples belonging to xGd(2)O(3)center dot(1-x)[0.857Bi(2)O(3)center dot 0.143GeO(2)] system, with 0.005 < x < 0.1, have been prepared by the rapid quenching method. Glass-ceramics were obtained after heat treatment of the as-prepared glasses at 600 degrees C for 24 h. All samples have been structurally characterized by X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy. All as-prepared samples are noncrystalline. The glass-ceramics contain different bismuthate crystalline phases, Bi12GeO20, BiLa type, and Bi24GeO38, depending on the gadolinium content in the glassy sample. The magnetic properties have been investigated by EPR and magnetic susceptibility measurements. The EPR and magnetic susceptibility data suggest that besides homogeneously distributed Gd3+ ions, both in the glass and glass-ceramic samples, there are clustered Gd3+ ions experiencing antiferromagnetic interactions.