Face-Centered Cubic Refractory Alloys Prepared from Single-Source Precursors

Three binary fcc-structured alloys (fcc–Ir(0.50)Pt(0.50), fcc–Rh(0.66)Pt(0.33) and fcc–Rh(0.50)Pd(0.50)) were prepared from [Ir(NH(3))(5)Cl][PtCl(6)], [Ir(NH(3))(5)Cl][PtBr(6)], [Rh(NH(3))(5)Cl](2)[PtCl(6)]Cl(2) and [Rh(NH(3))(5)Cl][PdCl(4)]·H(2)O, respectively, as single-source precursors. All alloys were prepared by thermal decomposition in gaseous hydrogen flow below 800 °C. Fcc–Ir(0.50)Pt(0.50) and fcc–Rh(0.50)Pd(0.50) correspond to miscibility gaps on binary metallic phase diagrams and can be considered as metastable alloys. Detailed comparison of [Ir(NH(3))(5)Cl][PtCl(6)] and [Ir(NH(3))(5)Cl][PtBr(6)] crystal structures suggests that two isoformular salts are not isostructural. In [Ir(NH(3))(5)Cl][PtBr(6)], specific Br…Br interactions are responsible for a crystal structure arrangement. Room temperature compressibility of fcc–Ir(0.50)Pt(0.50), fcc–Rh(0.66)Pt(0.33) and fcc–Rh(0.50)Pd(0.50) has been investigated up to 50 GPa in diamond anvil cells. All investigated fcc-structured binary alloys are stable under compression. Atomic volumes and bulk moduli show good agreement with ideal solutions model. For fcc–Ir(0.50)Pt(0.50), V(0)/Z = 14.597(6) Å(3)·atom(−1), B(0) = 321(6) GPa and B(0)’ = 6(1); for fcc–Rh(0.66)Pt(0.33), V(0)/Z = 14.211(3) Å(3)·atom(−1), B(0) =259(1) GPa and B(0)’ = 6.66(9) and for fcc–Rh(0.50)Pd(0.50), V(0)/Z = 14.18(2) Å(3)·atom(−1), B(0) =223(4) GPa and B(0)’ = 5.0(3).