LANTHANIDE ION-EXCHANGE IN SODIUM BETA-ALUMINOGALLATE NA1+X(AL1-YGAY)11O17+X/2 SINGLE-CRYSTALS

Large single crystals (5×5×1.5 mm3) of sodium ß-aluminogallate, with compositions Na1+x(Al1-yGay)11 O17+ x 2 (0.25 < y < 0.6) have been prepared at 1450-1600°C using a flux evaporation method. NaF flux was employed. Ga3+ ions substitute for Al3+ ions in the spinel blocks and the lattice parameters are found to be larger than those of ß-alumina. Several lanthanide ions have been partially exchanged for sodium ions in these crystals using molten rare-earth salts while such an exchange does not occur in ß-alumina. The distribution of these ions can be either homogeneous (Eu2+/Eu3+ mixture) or inhomogeneous (Ce3+, Nd3+). These materials could present interesting optical properties. © 1990.