EPR and magnetic susceptibility studies of B 2O 3–Bi 2O 3–Gd 2O 3 glasses

Abstract

Glasses of the xGd 2O 3 · (100 − x)[B 2O 3 · Bi 2O 3] system with 0.5 ⩽ x ⩽ 10 mol% were studied by electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. Data obtained show that for low gadolinium oxide contents of the samples ( x ⩽ 3 mol%) the Gd 3+ ions are randomly distributed in the host glass matrix and are present as isolated and dipole–dipole coupled species. For higher gadolinium oxide contents of the samples ( x > 3 mol%) the Gd 3+ ions appear as both isolated and antiferromagnetically coupled species. The EPR spectra of the glasses reveal resonance sites with an unexpected high crystalline field in addition to the ‘U’ spectrum, typical for Gd 3+ ions in disordered systems. This absorption line is due to Gd 3+ ions that replace Bi 3+ ions from the host glass matrix and could play the network unconventional former role in the studied glasses.