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

Abstract

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 0.50Pd 0.50 and chemically ordered CoPt). The size of the bimetallic particles varied from 5 to 20 nm. Order–disorder structural transformations in Co 0.50Pt 0.50 nanoalloys were studied. The magnetic properties of both chemically disordered Co 0.50Pd 0.50 and ordered CoPt clusters have also been measured.