The new binary intermetallic YbGe2.83

The new compound YbGe2.83 was obtained from the reaction of Yb and Ge in liquid indium. The crystal structure of YbGe2.83 adopts the trigonal, P3̄m1 space group with a=b=8.3657(12) Å and c=7.0469(14) Å. The structure of YbGe2.83 is a variant of the CaAl2Si2 structure type with ordered vacancies. Germanium atoms form double layers of puckered hexagons creating slabs that sandwich the Yb atoms. YbGe2.83 can be classified as a Zintl compound with the formula Yb(2+x)+(Ge2.83)(2+x)−. The deficiencies at the Ge sites cause a mixed/intermediate valent state of ytterbium (Yb2.35+). Valence bond sum calculations suggest an average valence of Yb ions in YbGe2.83 of 2.51 consistent with an intermediate valence compound.