Crystal Structure, Electronic Structure, and Physical Properties of Two New Antimonide−Tellurides: ZrSbTe and HfSbTe

Abstract

The isostructural title compounds were prepared from the elements in the stoichiometric ratio at 700 °C under exclusion of air. ZrSbTe and HfSbTe crystallize in the orthorhombic space group Immm, NbPS type, Z = 4, with a = 3.91171(6) Å, b = 5.80593(8) Å, c = 13.4630(3) Å, V = 305.760(6) Å3 for ZrSbTe, and a = 3.86757(8) Å, b = 5.75115(9) Å, c = 13.4422(3) Å, V = 298.995(6) Å3 for HfSbTe. The transition metal atoms are surrounded by four Sb and four Te atoms in the form of a bicapped trigonal prism. Two such prisms are joined via the third rectangular face, yielding a metal−metal bond across this face. The structures bestow with their unusual rectangular planar Sb layers exhibiting nonclassical Sb−Sb bonding. The distortion within the layers, reflected in the formation of alternating Sb−Sb distances along the b-axis, occurs with the formation of a band gap within the Sb bands. However, both compounds are metallic conductors with a small Seebeck coefficient, a consequence of a partial overlap of metal and Te states caused by the metal−metal bond.