STRUCTURAL REFINEMENTS ON A SODIUM BETA-ALUMINOGALLATE CRYSTAL AND A PARENT ND3+-EXCHANGED CRYSTAL

X ray structural refinements are performed on a sodium β-aluminogallate single crystal and on the corresponding Nd3+-exchanged compound, which presents potential laser applications. In the hexagonal unit cells (a = b = 5.667 Å, c = 22.663 Å, Z = 2 for the Na+ compound and a = b = 5.644, c = 22.610 Å for the Nd-exchanged compound), the study of ion distribution reveals a single position for the rare-earth active ion, a highly disordered distribution of sodium ions in the mirror-planes of the structure and a nonrandom localization of gallium in the available sites. © 1991.