Showing papers by "Sitaram Dash published in 2008"
TL;DR: In this paper, the energy of the ions impinging on the substrate during deposition was varied by changing the rf self bias voltage developed on a substrate, and the results obtained from different characterization techniques are correlated and explained on the basis of existing growth models for DLC films.
Abstract: DLC films were deposited on Si(111) substrates using CH 4 /Ar gas and microwave ECR plasma CVD processes. The energy of the ions impinging on the substrate during deposition was varied by changing the rf self bias voltage developed on the substrate. The bonding characteristics of the deposited films were investigated using FTIR and Raman spectroscopy, and mechanical properties were measured by nanoindentation and nanoscratch tests. The results obtained from different characterization techniques are correlated and explained on the basis of existing growth models for DLC films. Our studies indicate that the energy of the ions impinging on the substrates has a strong influence on the bonding characteristics and mechanical properties of the films.
15 citations
TL;DR: In this paper, surface modification of polycrystalline α-alumina using ion implantation is carried out using surface modification using ion augmentation, where samples were implanted at 60-keV N+ ions with different ion doses ranging from 1 × 1015 to 1 × 1 7 ǫ/cm2.
Abstract: Surface modification of polycrystalline α-alumina is carried out using ion implantation. Samples were implanted at 60 keV N+ ions with different ion doses ranging from 1 × 1015 to 1 × 1017 ions/cm2. Corrosion resistance is studied in a Ringer solution. The increase in corrosion resistance is due to the compound formation studied using Fourier transform infrared spectroscopy and glancing-angle X-ray diffraction techniques. Nanohardness is more at a lower ion dose and decreases at a higher ion dose. Microstrutural investigation shows that the decrease in corrosion resistance and nanohardness at a higher ion dose is due to the damage accumulation at the surface.
8 citations
TL;DR: In this article, a theoretical perspective involving thermal dynamics of the vaporization process and consequent non-linear multiple thermal phase transitions under the action of laser plasma is the subject matter of the present work.
Abstract: Laser material processing involving welding, ablation and cutting involves interaction of intense laser pulses of nanosecond duration with a condensed phase. Such interaction involving high brightness radiative flux causes multitude of non-linear events involving thermal phase transition at soild-liquid-gas interfaces. A theoretical perspective involving thermal dynamics of the vaporization process and consequent non-linear multiple thermal phase transitions under the action of laser plasma is the subject matter of the present work. The computational calculations were carried out where titanium (Ti) was treated as a condensed medium. The solution to the partial differential equations governing the thermal dynamics and the underlying phase transition event in the multiphase system is based on non-stationary Eulerian variables. The Mach number M depicts significant fluctuations due to thermal instabilities associated with the laser beam flux and intensity. A conclusive amalgamation has been established which relates material surface temperature profile to laser intensity, laser flux and the pressure in the plasma cloud.
5 citations
TL;DR: In this article, a soft chemical procedure at room temperature was used to synthesize semiconducting nanoparticles in the range of 6-7 nm in size, which were characterized by powder X-ray diffraction, UV-visible optical spectroscopy revealing nanocrystallization, and quantum mechanical electron confinement.
Abstract: CdSe semiconducting nanoparticles in the range of 6–7 nm in size were synthesized by a soft chemical procedure at room temperature. The particles were characterized by powder X-ray diffraction, UV–visible optical spectroscopy revealing nanocrystallization, and quantum mechanical electron confinement. Photoluminescence and Raman spectroscopy of these nanocrystalline powders indicated optical phonon confinement. Asymmetric line shapes revealed occurrence of nonzone center phonons. The particles could be successfully deposited on ITO substrate by electrophoresis to obtain self-organized quantum dot array. Scanning electron microscopy, high-resolution scanning electron microscopy, confocal fluorescence microscopy, and atomic force microscopy investigations revealed self-similar deposits.
2 citations