CRYSTAL-STRUCTURE AND PROPERTIES OF YBAG2IN4 AND CAAG2IN4 COMPOUNDS

The crystal structures of the YbAg2In4 and CaAg2In4 compounds have bee n determined by means of the single crystal method (DARTCH-1 automatic diffractometer, graphite-monochromalized Mo K alpha radiation, theta- 2 theta scan mode). They belong to a new structure type (space group I m3, Z=24, a=1.5362(3) and 1.5454(4) nm, respectively). Peculiarities o f the defects on the silver atom positions in the structures and their relations to the YCd6 and YbCd6 structures are discussed. The magneti c susceptibility of the YbAg2In4 compound follows the Curie-Weiss law in the temperature range 78-293 K. The ytterbium atoms in this compoun d have an intermediate valence state (mu(eff)=2.3 mu(B)). The CaAg2In4 compound is a Pauli paramagnet. The electrical resistivity of the stu died compounds, measured between 78 and 360 K, is characteristic of a metallic material. (C) 1998 Elsevier Science S.A.