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Keywords:

  • Bismuthides;
  • Zintl phases;
  • Laves phases;
  • Electronic structure

Abstract

Die Zintlphasen ABi (A = K/Rb/Cs; monoklin, Raumgruppe P21/c, a = 1422.3(2)/1474.2(2)/1523.7(3), b = 724.8(1)/750.2(1)/773.7(1), c = 1342.0(2)/1392.1(2)/1439.9(2) pm und β = 113.030(3)/113.033(2)/112.722(3)°, Z = 16) kristallisieren im β-CsSb Strukturtyp und enthalten Ketten zweibindiger Bi-Atome. Es handelt sich damit und nach den berechneten elektronischen Strukturen um Halbleiter mit kleinen Bandlücken von ca. 0.5 eV. Dagegen sind die Phasen ABi2 (A = K/Rb/Cs; kubisch, Raumgruppe Fd3¯m, a = 952.1(2)/962.4(8)/972.0(3) pm, Z = 8) Laves-Phasen und zeigen entsprechend typische metallische elektronische Leitfähigkeiten und keine Bandlücken.

Alkali Metal Bismuthides ABi and ABi2 — Synthesis, Crystal Structure, Properties

The Zintl phases ABi (A = K/Rb/Cs; monoclinic, space group, P21/c, a = 1422.3(2)/1474.2(2)/1523.7(3), b = 724.8(1)/750.2(1)/773.7(1), c = 1342.0(2)/1392.1(2)/1439.9(2) pm and β = 113.030(3)/113.033(2)/112.722(3)°, Z = 16) crystallize with the β-CsSb structure type containing chains of two-connected Bi atoms. Hence, and according to calculated electronic structures, they are semiconductors with small band gaps of approx. 0.5 eV. In contrast, the compounds ABi2 (A = K/Rb/Cs; cubic, space group Fd3¯m, a = 952.1(2)/962.4(8)/972.0(3) pm, Z = 8) belong to the Laves phases, showing a typical metallic electrical conductivity and no band gaps.