ON A BARIUM RARE-EARTH ALUMINATE ZINCATE - BALUALZN3O7 WITH A NOTE ONBA2ER2ZN8O13

Reactions of BaCO3, ZnO, Lu2O3 and Al2O3 mixtures at temperatures up t o 1500 degrees C led to small and colourless rods of BaLuAlZn3O7. The new compound crystallizes with hexagonal symmetry, space group C-6v(4) , P6(3)mc, a = 6.273, c = 10.161 Angstrom Z = 2. In spite of small dif ferences in the oxygen content BaLuAlZn3O7 is isotypic to Ba(2)Ln(2)Zn (8)O(13). The crystal structure shows Zn2+ with tetrahedral, Lu3+ with octahedral and Ba2+ with anticuboctahedral coordination by O2-. It ha s been shown that parts of the [Zn3AlO7](5-) network are fragments of the ZnO structure. In consequence one oxygen atom is fourfold coordina ted by zinc/aluminium. The space group of Ba(2)Ln(2)Zn(8)O(13) must be corrected to C-6v(4)-P6(3)mc.