EPR and magnetic susceptibility studies of manganese ions in Bi 2O 3GeO 2 glasses

Abstract

EPR and magnetic susceptibility measurements performed on xMnO · (1 − x)[Bi 2O 3·GeO 2] glasses with 0 < x ≤ 50 mol.% are reported. The EPR spectra are modified with the increase of manganese ions content. In the concentration range 0 < x ≤ 30 mol.% the spectra are characterized by the appearance of two resonance lines at g ≅ 4.3 having a resolved hyperfine structure for 0 < x ≤ 1 mol.%, characteristic for isolated Mn 2+ ions in low-symmetric sites and g ≅ 2.0 without hyperfine structure characteristic to clustered Mn 2+ ions. The ΔB values of g ≅ 2.0 resonance lines and magnetic susceptibility data suggest the appearance of superexchange interactions for x ≥ 30 mol.%. From the Curie constant values we have established that in these glasses both Mn 2+ and Mn 3+ ions are present, determining their magnetic behaviour.