Crystal structure and physical properties of the new silicideHf4CuSi4 with planar CuSi4 rectangles

Abstract

The new compound Hf₄CuSi₄ was prepared via a high-temperature reaction in a resistance furnace. Hf₄CuSi₄ adopts the Y₄GaCo₄ structure type in the space group C2/m, with cell dimensions of a = 9.6945(8) Å, b = 3.7498(3) Å, c = 8.6531(7) Å, β = 109.912(1)° and V = 295.76(4) ų. Parts of its structure are reminiscent of HfSi, e.g. its six-membered Hf-channels running along the [100] direction. The hexagonal channels are interconnected via Hf–Hf bonds to a three-dimensional network of Hf atoms. Each channel contains CuSi_4/2 strips interconnected via Si atoms to form infinite layers. The Cu atoms are coordinated by four Si atoms in form of a planar rectangle. This material is metallic with a distinct pseudo-gap at 0.45 eV above the Fermi level.