Solid solutions and intermetallic compounds containing platinum metals are shown to possess the greatest electrocatalytic and magnetic characteristics. The double complex salts (DCS) containing both a platinum group metal and a transition metal are attracting to researchers as precursors of bimetallic materials of various composition and structure [1, 2].
Bimetallic phase Co_0.50Ir_0.50 was prepared by the thermal decomposition of [Ir(NH₃)₆][Co(C₂O₄)₃]•H₂O and [Co(NH₃)₆][Ir(C₂O₄)₃]. The processes of the thermal decomposition in helium and hydrogen atmospheres were studied in details.
Decomposition of these complex salts in hydrogen atmosphere was investigated by XRD and thermal analysis. Relatively fast (0.5 hour) rise of the temperature to 550 °C and exposure of thermolysis products at this temperature during one hour results in formation of nanocrystalline bimetallic phase. The developed phase is represented by close packing crystal structure with planar defects – stacking faults. Diffraction patterns of the products can be interpreted as alloys of iridium with cobalt based on FCC structure with coherent insertion of the HCP fragments. Crystalline size of the particles is 4-5 nm.
Father rise of the temperature diminishes the number of packing defects. During the annealing the positions of the reflections of the FCC lattice remains constant, while relative intensity of the peak 002 increases, and the ratio I₀₀₂/I₁₁₁ approaches 0.5 (see figure). Final product is a powder of disordered solid solution Ir_0.50Co_0.50 (sp. gr. Fm-3m, a = 3.710(3) Å, 20-30 nm crystalline size). Size distribution and morphology of the particles were investigated by scanning electron microscopy. The composition of the all samples was confirmed by energy dispersive X-ray spectroscopy (EDS).
This work was supported by the RFBR grants 07-03-01038-a, 08-03-00603-а.
1. A.V. Zadesenets, E.Yu. Filatov, K.V. Yusenko et al., Inorg. Chim. Acta 361 (2008) 199.
2. K.V. Yusenko, E.Yu. Filatov, D.B. Vasil’chenko et al., Z. für Krist. Suppl. 26 (2007) 289.

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