ausblenden:
Schlagwörter:
-
Zusammenfassung:
The semiconducting compound BaRh2Si9 is a new kind of intermetallic
clathrate. It was obtained by reacting BaSi, Rh and Si at 950 degrees C.
The crystal structure (space group C2/c; Pearson symbol mC48, a =
6.2221(5) angstrom, b = 21.399(2) angstrom, c = 6.2272(5) angstrom, beta
= 90.306(7)degrees) displays a covalently bonded Rh-Si framework, in
which four-connected Si atoms partly show unusually small bond angles.
The Ba atoms are encapsulated in large polyhedral cages formed by 18 Si
and 4 Rh atoms. The compound is a diamagnetic p-type semiconductor,
which is in agreement with band structure calculations resulting in a
band gap of 0.12 eV. Quantum chemical calculations reveal positively
charged Ba atoms (Ba+1.3) and negatively charged Rh atoms (Rh-1). Si
atoms with neighboring Rh atoms are positively charged, while those
connected only with Si atoms are negatively charged.
