Untersuchungen zum Existenzgebiet des CaAl2Si2-Strukturtyps bei ternären Siliciden

Investigations about the Stability Range of the CaAl₂Si₂ Type Structure in the Case of Ternary Silicides Five compounds LnAl₂Si₂ (Ln: trivalent rare-earth metal, Y) were synthesized by heating the elements at 800°–1000 °C. They are isotypic and crystallize in the CaAl₂Si₂ type structure (P 3 m1; Z = 1) (lattice constants see “Inhaltsübersicht”). The electronic structures (LMTO band structure calculations) of CaAl₂Si₂ and YAl₂Si₂, the latter one is in accordance to Ln³⁺(Al³⁺)₂(Si^4–)₂ not electrovalent, are discussed with regard to the bondings and the electrical conductivity respectively. Investigations of GdAl_2–xMn_xSi₂ mixed crystals showed, that the structure type already at low Mn content (x ≈ 0,3) changes from CaAl₂Si₂ (GdAl₂Si₂) to ThCr₂Si₂ type structure (GdMn₂Si₂).