Ternary K2Zn5As4‐type pnictides Rb2Cd5As4 and Rb2Zn5Sb4, and the solid solution Rb2Cd5(As,Sb)4
Dirubidium pentacadmium tetraarsenide, Rb2Cd5As4, dirubidium pentazinc tetraantimonide, Rb2Zn5Sb4, and the solid‐solution phase dirubidium pentacadmium tetra(arsenide/antimonide), Rb2Cd5(As,Sb)4 [or Rb2Cd5As3.00(1)Sb1.00(1)], have been prepared by direct reaction of the component elements at high temperature. These compounds are charge‐balanced Zintl phases and adopt the orthorhombic K2Zn5As4‐type structure (Pearson symbol oC44), featuring a three‐dimensional [M 5 Pn 4]2− framework [M = Zn or Cd; Pn is a pnicogen or Group 15 (Group V) element] built of linked MPn 4 tetrahedra, and large channels extending along the b axis which host Rb+ cations. The As and Sb atoms in Rb2Cd5(As,Sb)4 are randomly disordered over the two available pnicogen sites. Band‐structure calculations predict that Rb2Cd5As4 is a small‐band‐gap semiconductor and Rb2Zn5Sb4 is a semimetal.
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Document Type: Research Article
Publication date: May 15, 2013