Effect of Target Composition and Sputtering Deposition Parameters on the Functional Properties of Nitrogenized Ag-Permalloy Flexible Thin Films Deposited on Polymer Substrates

We report the first results of functional properties of nitrogenized silver-permalloy thin films deposited on polyethylene terephthalic ester {PETE (C₁₀H₈O₄)_n} flexible substrates by magnetron sputtering. These new soft magnetic thin films have magnetization that is comparable to pure Ni₈₁Fe₁₉ permalloy films. Two target compositions (Ni₇₆Fe₁₉Ag₅ and Ni₇₂Fe₁₈Ag₁₀) were used to study the effect of compositional variation and sputtering parameters, including nitrogen flow rate on the phase evolution and surface properties. Aggregate flow rate and total pressure of Ar+N₂ mixture was 60 sccm and 0.55 Pa, respectively. The distance between target and the substrate was kept at 100 mm, while using sputtering power from 100–130 W. Average film deposition rate was confirmed at around 2.05 nm/min for argon atmosphere and was reduced to 1.8 nm/min in reactive nitrogen atmosphere. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, vibrating sample magnetometer, and contact angle measurements were used to characterize the functional properties. Nano sized character of films was confirmed by XRD and SEM. It is found that the grain size was reduced by the formation of nitride phase, which in turns enhanced the magnetization and lowers the coercivity. Magnetic field coupling efficiency limit was determined from 1.6–2 GHz frequency limit. The results of comparable magnetic performance, lowest magnetic loss, and highest surface free energy, confirming that 15 sccm nitrogen flow rate at 115 W is optimal for producing Ag-doped permalloy flexible thin films having excellent magnetic field coupling efficiency.

Effect of temperature on surface characteristics of nitrogen ion implanted biocompatible titanium

It has been established that nitrogen implantation can modify metals surface properties such as corrosion, wear, friction, etc. Recent studies have shown that nitrogen implantation into titanium and its alloys leads to the formation of titanium nitride, which has interesting biological, chemical, and mechanical properties. In the present investigation, commercially pure biocompatible titanium implanted by nitrogen. Implantation of ions performed at 80 keV and a dose of 2.1 × 10¹⁸ ions/cm² at four different temperatures of 300, 473, 673 and 873 k. Phase and chemical compositions of modified surfaces after implantation obtained using grazing incidence X-ray diffraction technique (GIXRD) and Fourier transform infrared spectrum (FTIR), respectively. The roughness variations before and after ion implantation were observed by atomic force microscopy (AFM). Electrochemical behavior of the samples was investigated in Ringer solution by using electrochemical impedance spectroscopy and polarization tests. Scanning electron microscopy micrographs was used to evaluate the surface morphology of the samples. Variation of the Young's modulus and hardness of samples were examined using nano-indentation technique before and after ion implantation. Compared to nano-hardness of unimplanted sample, the maximum nano-hardness value of implanted samples is as high as 14.2 GPa, which is at least eight times larger than hardness of the unimplanted sample. The elastic modulus of unimplanted sample was obtained 106 GPa and the maximum elastic modulus value of implanted samples is as high as 178 GPa. Corrosion test results showed that implantation could increase the corrosion resistance of samples, but by increasing the implantation temperature, the corrosion resistance will decrease.

Synthesis of hexagonal Ni(3)N using high pressures and temperatures

The only known bulk ambient pressure nickel nitride phase is hexagonal Ni(3)N (space group P6(3)22). Multianvil synthesis experiments at 20 GPa and 2000 K using nickel (Ni) and sodium azide (NaN(3)) starting materials, and ex situ analysis using transmission electron microscopy and scanning electron microscopy measurements show that this phase can be recovered at ambient pressure (space group P6(3)22, a = 4.62 Å, c = 4.30 Å, Z = 2). Formation of this phase is correlated with the repulsive interactions between closely spaced nitrogen ions and with the extent of thermal stability of nickel nitride at ambient and at high densities. These two factors are also important in relating the high temperature and pressure behaviour of nickel nitride to those of several other interstitial nitrides recovered from similar pressures after heating. Further, we report formation of a sodium rhenium nitride phase by reaction of the azide with the rhenium capsule in which the reactants were contained.