Nanocrystallization and Amorphization Induced by Reactive Nitrogen Sputtering in Iron and Permalloy

Thin films of iron and permalloy Ni80Fe20 were prepared using an Ar+N2 mixture with magnetron sputtering technique at ambient temperature. The nitrogen partial pressure, during sputtering process was varied in the range of 0 to 100%, keeping the total gas flow at constant. At lower nitrogen pressures RN2<33% both Fe and NiFe, first form a nanocrystalline structure and an increase in nitrogen partail pressure results in formation of an amorphous structure. At intermediate nitrogen partial pressures, nitrides of Fe and NiFe were obtained while at even higher nitrogen partial pressures, nitrides themselves became nanocrystalline or amorphous. The surface, structural and magnetic properties of the deposited films were studied using x-ray reflection and diffraction, transmission electron microscopy, polarized neutron reflectivity and using a DC extraction magnetometer. The growth behavior for amorphous film was found different as compared with poly or nanocrystalline films. The soft-magnetic properties of FeN were improved on nanocrystallization while those of NiFeN were degraded. A mechanism inducing nanocrystallization and amorphization in Fe and NiFe due to reactive nitrogen sputtering is discussed in the present article.Comment: 13 Pages, 15 Figure

Isotropic magnetization response of electrodeposited nanocrystalline Ni–W alloy nanowire arrays

Isotropic magnetization response was demonstrated in electrodeposited nanocrystalline Ni–15 % W alloy nanowire arrays, which can be applied to nanoscale magnetic field sensors. The Ni–W alloy nanowire arrays were electrochemically synthesized on a nanochannel template electrode from an aqueous electrolytic solution. X-ray and electron diffraction patterns revealed that Ni–15 % W alloy deposits were composed of ultrafine crystal grains with a supersaturated solid solution phase. The magnetization of the Ni–15 % W alloy thin films reached saturation at around 2.5 kOe in a perpendicular direction to the film plane, whereas the pure Ni thin films hardly magnetized in the perpendicular direction. On the contrary, Ni–15 % W alloy nanowire arrays were easily magnetized, and reach saturation at around 1.0 kOe, even in a perpendicular direction to the array film plane that corresponds to the long-axis direction of the alloy nanowires

USE OF HIGH SURFACE NANOFIBROUS MATERIALS IN MEDICINE

n/