Crystal Structure and Physical Properties of the New Antimonide Hf₃Cu₂Ge_3.58Sb_1.42

Abstract

The antimonide Hf 3 Cu 2 Ge 3.58 Sb 1.42 was obtained via a two-step synthesis: arc-melting of hafnium, copper, and germanium under argon was followed by a reaction of the thus obtained ingot with antimony under a vacuum in a silica ampule. This compound adopts a new structure type, space group P4/nmm, with lattice dimensions of a= 3.8023(6) A ˚, c=24.575(4) A ˚, V=355.29(10) A ˚3. The structure of Hf 3 Cu 2 Ge 3.58 Sb 1.42 comprises puckered double layers of the Hf and Ge/Sb atoms as well as ¥ 2 [Cu] and ¥ 2 [Ge/Sb] planar square nets, representing a new intergrowth structure of ZrSiS-and NdTe 3 -like slabs. The ¥ 2 [Ge/Sb] square nets are composed of one disordered site that is statistically mixed occupied by 88% Ge and 12% Sb atoms. Electronic structure calculations predicted metallic properties, subsequently confirmed by an Seebeck and an electrical resistivity measurement.

Quaternary Germanide Arsenides ZrCuGeAs and HfCuGeAs

“…Nearest‐neighbor coordination environments are square antiprismatic (4 Ge + 4 As) around zirconium or hafnium, tetrahedral (4 As) around copper, square planar (4 Ge) around germanium, and square antiprismatic (4 Zr + 4 Cu) around As atoms. This theme of stacking square nets persists in many related tetrelide pnictides, such as Hf 3 Cu 2 Ge 3.6 Sb 1.4 , which can be regarded as an intergrowth of PbFCl‐ and NdTe 3 ‐type fragments 11…”

“…Interestingly, an investigation of the analogous germanium system Zr(Ge x As 1– x )As did not show evidence for a PbFCl‐type phase 10. The recently discovered antimonide Hf 3 Cu 2 Ge 3.6 Sb 1.4 contains HfGeSb fragments of the PbFCl‐type,11 but a quaternary germanide antimonide with the ZrCuSiAs‐type structure is still unknown. From this backdrop, it is unclear whether the quaternary germanide arsenides have not been reported simply for lack of trying or because they violate some principles of structural chemistry.…”

New compounds and structures in the solid state

“…A new structure has been identified in an antimonide, Hf 3 Cu 2 Ge 3.58 Sb 1.42 , produced by heating an ingot of hafnium, copper and germanium under vacuum with antimony. 39 The structure can be considered to be built up from layers of structure types ZrSiS and NdTe 3 . It appears that the occupational disorder between Ge and Sb is a key component in stabilising this structure as it provides an entropic term that is otherwise absent.…”

HfSb2–xTex: The Second New Compound on the Quasi‐Binary Section HfSb2‐HfTe2 with Different Sb–Sb Interactions

“…Different structures were obtained when replacing part of the antimony atoms with tellurium and with E = Si, Ge, Sn, namely ZrSbTe and HfSbTe21 with planar rectangular antimony layers (NbPS type), Zr E x Sb 2– x and Hf E x Sb 2– x 22 (Co 2 Si type), and ZrSi 0.7 Sb 1.3 , ZrGeSb23 and HfGeSb24 (with square planar layers formed by the Si/Ge atoms with some antimony content (ZrSiS type)). Square nets of > 80 % antimony atoms were observed in the structure of Hf 3 Cu 2 Ge 3.58 Sb 1.42 25. Our attempts to cause a further distortion of the T‐net 26 of Hf 5 Sb 9 by increasing its valence electron concentration via tellurium doping led to the formation of a new variant, namely HfSb 2– x Te x with 0.4 ≤ x ≤ 0.7, which will be introduced with this contribution.…”