OPTICAL AND MAGNETIC INVESTIGATIONS OF NA+/PR3+-BETA''-AL2O3

The Na+ ions in the solid electrolyte beta '' alumina (Na+-beta ''-Al2O3) have been exchanged with Pr3+ ions. The Pr3+ ion has been used as an optical and magnetic probe to investigate the local structure within the conduction planes of this oxide. With this aim, optical spectra and susceptibility measurements have been carried out. Both fluorescence and excitation spectra, related to the P-3(0)-->F-3(2),H-3(4) transitions, have been recorded on single crystals. The magnetic susceptibility shows temperature-independent paramagnetism at low temperatures. The physical properties have been interpreted with the help of ligand-field calculations by applying the angular overlap model. It has been deduced that the Pr3+ ions occupy mostly the eightfold-coordinated mid-oxygen (mO) sites.