The new intermetallic compound Ga5Pt:Structure from a twinned crystal

As intermetallic Pt–Ga alloys may form at the metal-semiconductor interfaces (Pt/GaAs) in electronic devices, their crystal structures are of interest. Ga7Pt3 has been prepared and its structure confirmed from single crystal X-ray diffraction in the Im 3 ¯ m cubic space group with a cell parameter of 8.78604(8) Å. For the new Ga-richer compound Ga5Pt, the crystal structure has been solved from a twinned crystal in the monoclinic P21/m space group, a = 6.3977(3), b = 15.8823(5), c = 8.8326(4) Å, β = 110.198(5)°, Z = 16. Bonding in Ga5Pt proceeds through Ga–Ga and Ga–Pt bonds while Pt dumbbells (Pt–Pt = 2.776 Å) are found in Ga7Pt3. The electronic structures calculated by DFT methods indicate metallic properties for both compounds.