DEPENDENCE OF PR3-BETA''-ALUMINA( DISTRIBUTIONS ON THE COMPOSITION OFPR3+)

The structures of completely exchanged Na+/Pr3+-beta ''-Al2O3 crystals have been investigated by single crystal X-ray diffraction methods at room temperature, The ionic distributions within the conduction layer s are correlated with the crystal compositions. A decreasing cation co ntent in the layers increases the lattice parameter c connected with a n expansion of the conduction slabs resulting in an increased Beevers- Ross (BR) site occupancy by Pr3+ ions, Up to 52% of the lanthanide ion s are found to occupy the lower coordinated BR positions. (C) 1996 Aca demic Press, Inc.