Magnetic susceptibility investigation of CoO-Bi2O3-GeO2 glasses

The results obtained from the temperature dependence of the magnetic susceptibility for xCoO(100-x)[Bi2O3. GeO2] glasses with 0 <x less than or equal to 40 mol% are investigated. The atomic magnetic moment values for x less than or equal to5 mol% suggest that the Co2+ ions are predominantly octahedral coordinated, whereas for x greater than or equal to 20 mol% they are located in tetrahedral coordinated sites. The values obtained for the magnetic moment of the samples with 5 <x < 20 mol% may be explained assuming a statistical average distribution of Co2+ ions in these two types of coordination. The paramagnetic Curie temperature values indicate that the Co2+ ions participate at the negative magnetic superexchange interaction for x >5 mol%. (C) 2001 Elsevier Science B.V. All rights reserved.