CRYSTAL-STRUCTURE OF YBMN-SIMILAR-TO-SI-0.17-SIMILAR-TO(1.83) - A NEWALB2-BAAL4 INTERGROWTH COMPOUND

We report on the crystal structure of YbMn0.17Si1.83, a new type struc ture based on an intergrowth of three AlB2 blocks and one BaAl4 block. In the BaAl4 block, the manganese atoms occupy one third of the pyram idal sites as observed in many non-stoichiometric CeNiSi2-type compoun ds. The inner AlB2 block is only 2/3 occupied by the silicon atoms as observed in the related Ho3Si4 and ErGe1.83 compounds. Isotypic and re lated compounds are found in other R-Mn-Si systems (R=Ho-Lu). The stru ctural relationships with other binary and ternary compounds are exami ned and the common structural features are discussed. (C) 1998 Elsevie r Science S.A. All rights reserved.