Bimetallic Cu–Ni nanoparticles of varying composition (CuNi3, CuNi, Cu3Ni)

Cu–Ni (1:3, 1:1, 3:1) bimetallic nanoparticles have been synthesized by a microemulsion route using CTAB (cetyltrimethyl ammoniumbromide) as the surfactant and hydrazine/NaOH as the precipitating agent followed by reduction in hydrogen atmosphere. This is the first report of the synthesis of CuNi3 and Cu3Ni nanoparticles. Transmission electron microscopy (TEM) studies show nearly monodisperse and uniform nanoparticles of average grain size of 7 nm for the 1:1 alloy nanoparticles while the 1:3 and 3:1 compositions show uniform nanoparticles with the grain size in the range of 20–30 nm. X-ray photoelectron spectroscopy (XPS) studies confirm the expected Cu/Ni ratios in these alloys. These bimetallic nanoparticles show ferromagnetic behavior and the magnetization decreases with increase in concentration of copper. The specific surface area of these alloy nanoparticles was found to be in the range of 6–9.42 m2/g.