Growth of single-crystalline nickel silicide nanowires with excellent physical properties

High quality single- crystalline NiSi2, Ni-2 Si and Ni31Si12 nanowire arrays coated with amorphous silicon dioxide were synthesized in high quantity by a nickel transport chemical vapor deposition (CVD) method. The morphological changes with various reaction temperatures, ambient pressures and reaction times, were observed and studied. At 750 degrees C and 850 degrees C, cone- shaped nanowire arrays were formed, composed of dense and oriented Ni31Si12 and Ni2Si nanowires with lengths of over 60 mu m. The growth mechanisms of the nickel silicide nanowires have been proposed and identified with microscopy studies. Field emission measurements show that the as- grown NiSi2, Ni2Si and Ni31Si12 nanowires were of remarkable field enhancement factors, 2532, 4822 and 4099, respectively, and magnetic property measurements show ferromagnetic characteristics for the Ni2Si and Ni31Si12 nanowires, demonstrating promising potential applications for field emitters, magnetic storage, and biological cell separation.