Synthesis and Characterization of Silica-Coated Cu $_{1-{\rm x}}$ Ni $_{\rm x}$ Nanoparticles

The synthesis of magnetic Cu_1-xNi_x nanoparticles was carried out in cationic water-in-oil (w/o) microemulsions of water/cetyl-trimethyl-ammonium bromide (CTAB), n-butanol/isooctane by the reduction of nickel and copper chlorides with hydrazine and NaOH. The synthesized Cu_1-xNi_x particles were heat treated to maintain their proper homogeneity and Curie temperature. Some alloy particles with the composition CU_27.5M_72.5 were coated with silica prior to the thermal homogenization in order to retain the pristine morphology. The magnetic particles were characterized using XRD, transmission electron microscopy (TEM) and magnetic measurements. The thermal demagnetization in the vicinity of the Curie temperature of the nanoparticles was studied using a modified TGA/SDTA method.