Bimetallic single-source precursors [M(NH_3)_4] [Co(C_2O_4)_2(H_2O)_2] ·2H_2O (M = Pd, Pt) for the one run synthesis of CoPd and CoPt magnetic nanoalloys

摘要

All the steps of the proposed technique, from the synthesis of single-source precursors to the preparation of CoPd and CoPt nanoalloys, are described. The double complex salts (DCS) [M(NH_3)_4] [Co(C_2O_4)_2(H_2O)_2] ·2H_2O (M = Pd, Pt), which were synthesized by mixing solutions containing [M(NH_3)_4]~(2+) cations and [Co(C _2O_4)_2(H_2O)_2] ~(2-) anions, have been used as precursors. The salts obtained were characterized by IR spectroscopy, thermal analysis, XRD and single crystal X-ray diffraction. The prepared compounds crystallize in the monoclinic (space group I2/m, M = Pd) and orthorhombic (space group I222, M = Pt) crystal systems. Thermal decomposition of the salts in helium or hydrogen atmosphere at 200-600 °C results in the formation of nanoalloys powders (random solid solution Co_(0.50)Pd_(0.50) and chemically ordered CoPt). The size of the bimetallic particles varied from 5 to 20 nm. Order-disorder structural transformations in Co_(0.50)Pt_(0.50) nanoalloys were studied. The magnetic properties of both chemically disordered Co_(0.50)Pd _(0.50) and ordered CoPt clusters have also been measured.