DEPENDENCE OF STRUCTURE AND IONIC-CONDUCTIVITY ON THE COMPOSITION OF NA+ PR3+-BETA''-ALUMINA/

The structure of completely exchanged Na+/Pr3+-beta ''-alumina crystal s have been investigated by single crystal X-ray diffraction methods a t room temperature. Ionic distributions within the conduction planes a re correlated with the crystal composition. Up to 52% of the lanthanid e ions are found to occupy BR positions. The conduction behaviour of N a+/Pr3+-beta ''-Al2O3 crystals with varying degree of exchange were de termined by impedance spectroscopy in a temperature range of 300-1000 K. With growing Pr3+ content the ionic conductivity (sigma) is lowered connected with an increasing activation energy E(a). For a given degr ee of exchange sigma scatters of about 1-2 orders of magnitude and E(a ) within 0.15-0.2 eV. These deviations can be understood by the differ ent crystal compositions influencing the thickness of the conduction s labs and the ionic distributions.