Trans. Nonferrous Met. Soc. China 24(2014) 1467−1473 Structure and magnetic properties of Cu−Ni alloy nanoparticles prepared by rapid microwave combustion method J. ARUL MARY 1 , A. MANIKANDAN 1 , L. JOHN KENNEDY 2 , M. BOUOUDINA 3,4 , R. SUNDARAM 5 , J. JUDITH VIJAYA 1 1. Catalysis and Nanomaterials Research Laboratory, Department of Chemistry Loyola College, Chennai 600034, India; 2. Materials Division, School of Advanced Sciences, Vellore Institute of Technology (VIT) University, Chennai Campus, Chennai 600127, India; 3. Department of Physics, College of Science, University of Bahrain, PO Box 32038, Kingdom of Bahrain; 4. Nanotechnology Centre, University of Bahrain, PO Box 32038, Kingdom of Bahrain; 5. Department of Chemistry, Presidency College, Chennai 600005, India Received 26 August 2013; accepted 7 January 2014 Abstract: Cu−Ni alloy nanoparticles were prepared by a microwave combustion method with the molar ratios of Cu 2+ to Ni 2+ as 3:7, 4:6, 5:5, 6:4 and 7:3. The as-prepared samples were characterized by XRD, HR-SEM, EDX and VSM. XRD and EDX analyses suggest the formation of pure alloy powders. The average crystallite sizes were found to be in the range of 21.56−33.25 nm. HR-SEM images show the clustered/agglomerated particle-like morphology structure. VSM results reveal that for low Ni content (Cu 5 Ni 5 , Cu 6 Ni 4 and Cu 7 Ni 3 ), the system shows paramagnetic behaviors, whereas for high Ni content (Cu 3 Ni 7 and Cu 4 Ni 6 ), it becomes ferromagnetic. Key words: microwave combustion; nanoparticles; Cu−Ni alloys; magnetization property 1 Introduction The preparation of nanostructures with controlled size, morphology and composition of the materials are of great interest, because of their unique physical and chemical properties. Also, nanomaterials are of vast scientific and technological importance, due to their more potential applications than bulk materials. Recently, bimetallic nanoalloys are mainly attractive, due to their unusual magnetic [1−4], electronic [1], biological [5] and catalytic properties [6], their size and pure elemental cluster. Alloy magnetic particles with size in the nanometer range exhibit features quite different from those of the corresponding bulk counterparts [7]. Among the various alloys, the copper−nickel (Cu−Ni) alloy nanoparticles show good catalytic properties that depend on the mole ratio of Cu to Ni of precursors. Copper−nickel alloys are widely studied because they possess good catalytic, electronic and magnetic properties. Also, they are widely used for industry applications, due to their excellent resistance to corrosion, high inherent resistance to biofouling and good fabricability [8]. This is the case for Ni-based bimetallic particles containing copper, which exhibit better catalytic activity [9] and selectivity than monometallic nickel. It was found that the magnetic properties of Cu−Ni alloy nanostructures depend on the amount of Ni or the Ni-rich regions in the sample [10]. The copper−nickel alloys are known for the capable assembly of such materials. This well-considered alloy material is chemically stable and biocompatible and exhibits appropriate magnetic properties. Various techniques have been used to produce the bimetallic nanoalloys including the sol−gel [3], solvothermal [11], polyol process [12], sonochemical [13] and microemulsion method [14]. But the above methods are always high-energy consuming and require rather long reaction time, complex, low-yield and high cost. In this present study, Cu−Ni bimetallic nanoalloys were synthesized by a microwave combustion method. However, microwave combustion method has more Corresponding author: J. JUDITH VIJAYA; Tel: +91-44-28178200, Fax: +91-44-28175566; E-mail: jjvijayaloyola@yahoo.co.in; jjvijaya78@gmail.com DOI: 10.1016/S1003-6326(14)63214-3