Effects of the addition of transition metal ions on some physical properties of lithium niobium borate glasses

Glasses with composition 90 mol% Li2B4O7-10 mol% Nb2O5 doped with TM (where TM=V2O5, MnO2, Co3O4 and CuO) have been prepared using the normal melt quench technique. We have used DTA and XRD and studied density, magnetic susceptibility and optical absorption to explore the influence of transition metal (TM) oxide valance state and coordination with oxygen on the glass properties. The quenched sample was heat treated at 620 degrees C for 5 h. In the sample free from transition metal lithium niobate (LiNbO3) and lithium tetraborate (Li2B4O7) were the main phases in addition to traces of LiNb3O8. With TM additions to the glasses, LiNb3O8 increases and LiNbO3 decreases. DTA indicated that the activation energy of crystallization increases with increasing atomic number but reaches a minimum value at manganese. The activation energy of glass samples containing manganese has a minimum value due to this sample containing a lower quantity of Li2B4O7 and LiNb3O8. The analysis of the results of magnetic susceptibility chi studies has shown that the chi increases with increasing atomic number and reaches maximum at cobalt and then decreases.