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

The Na+ ions in the solid electrolyte beta '' alumina (Na+-beta ''-Al2 O3) have been exchanged with Pr3+ ions. The Pr3+ ion has been used as an optical and magnetic probe to investigate the local structure withi n the conduction planes of this oxide. With this aim, optical spectra and susceptibility measurements have been carried out. Both fluorescen ce and excitation spectra, related to the P-3(0)-->F-3(2),H-3(4) trans itions, have been recorded on single crystals. The magnetic susceptibi lity 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.