Magnetic susceptibility study of CoO-Bi2O3-PbO glasses

The X -1 - f(T) of xCoO.(1-x)[Bi 2 O 3 .PbO] glass system (0 < x ≤0.4) are investigated. The μ eff values for x ≤0.01 suggest that Co 2+ ions predominantly octahedrally coordinated, whereas for x ≥ 0.03 the Co 2+ ions are located in tetrahedral sites. For 0.01 < x ≤ 0.03 these two types of coordination simultaneously exist. The paramagnetic Curie temperature indicates negative superexchange interactions between Co 2 + ions for x≥ 0.1.