SINGLE-CRYSTAL X-RAY-ANALYSIS OF BA3CE(IV )RU2(IV)O9, BA(3)LN(III)RU(2)(IV V)O(9) (LN=SM,DY,ER) AND BA3TI2.4RU0.6O9/

Single crystals of (I) Ba3CeRu2O9, (II) Ba3SmRu2O9, (III) Ba3DyRu2O9, (IV) Ba3ErRu2O9 and (V) Ba3Ti2,(4)RU(0,6)O(9) have been prepared by hi gh temperature solid state reactions. The compounds were examined by X -ray techniques. They crystallize with hexagonal symmetry, space group D-6h(4)-P6(3)/mmc with (I): a = 5.8738(7), c = 14.585(4); (II): a = 5 .9137(5), c = 14.651(2); (III): a = 5.8305(5), c = 14.50(1); (IV): a = 5.8737(9), c = 14.470(3); (V): a = 5.7265(6), c = 14.006(2) Angstrom, Z = 2. The crystal structures belong to the 6L-perovskite type. Calcu lations of the Coulomb terms of the lattice energy led to the valence states (I): Ce-IV/Ru-IV and (II)-(IV): Ln(III)/RU(IV/V). (V) shows a p artial statistic distribution of Ti-IV and Ru-IV.