Search

We have grown a single crystal of Ascorbic acid (a drug) containing Potassium nitrate as an additive by aqueous solution method. Good semi transparent, semi organic nonlinear optical crystals were obtained in a period of 3 weeks. The cell parameters of the grown crystals were estimated by single crystal X-ray diffraction analysis. The X-ray powder diffraction further confirms the crystalline properties of the grown crystals. Thermal analysis was performed to study the thermal stability of the grown crystals. The presence of functional groups and mode of vibrations were identified from the FTIR spectrum. The powder second harmonic generation (SHG) of the grown crystal was measured by Kurtz technique using Nd: YAG laser. Scanning Electron Microscopic (SEM) studies reveals the morphology of the crystals. [ABSTRACT FROM AUTHOR]

The pressure dependences of 35Cl nuclear quadrupole resonance (NQR) frequency, temperature and pressure variation of spin lattice relaxation time ( T1) were investigated in 3,4-dichlorophenol. T1 was measured in the temperature range 77-300 K. Furthermore, the NQR frequency and T1 for these compounds were measured as a function of pressure up to 5 kbar at 300 K. The temperature dependence of the average torsional lifetimes of the molecules and the transition probabilities W1 and W2 for the Δ m = ±1 and Δ m = ±2 transitions were also obtained. A nonlinear variation of NQR frequency with pressure has been observed and the pressure coefficients were observed to be positive. A thermodynamic analysis of the data was carried out to determine the constant volume temperature coefficients of the NQR frequency. An attempt is made to compare the torsional frequencies evaluated from NQR data with those obtained by IR spectra. On selecting the appropriate mode from IR spectra, a good agreement with torsional frequency obtained from NQR data is observed. The previously mentioned approach is a good illustration of the supplementary nature of the data from IR studies, in relation to NQR studies of compounds in solid state. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In VLSI, metallisation plays an important role to control the speed of the circuit, by virtue of resistance of the interconnection runners and also it controls flat band voltage between the substrate and multi metal layers. To minimize interconnection resistance and to save valuable chip area, multilevel metallization schemes have been proposed. The monolayer Al-Cu, barrier layer Al-Cu/Ti- W and multilevel layers Al-Cu/Ti-W/Pt were deposited on Si using High Rate Magnetron Sputtering. In order to find the significance of the thin Pt layer, complete electrical, mechanical and micro structural analysis have been carried out for all the three samples. From XRD, the phase of the samples remains the same as orthorhombic, but the grain size has drastically reduced from 80 nm (Al-Cu /Ti-W) to 26.76 nm in Al-Cu/Ti-W/Pt. Reduction in grain size due to the Pt layer enhances the mechanical stability in the substrate. For a given load, the Hardness value has increased and material has become tough. Constant resistivity value over a temperature range (room temperature to 200°C) reveals the reduction of scattering center, voids and dislocation. This Pt/PtSi multi level matellisation, which enhances the stability with low resistivity value is more appropriate for VLSI to reduce chip area significantly. [ABSTRACT FROM AUTHOR]

PVA and doped PVA films were prepared by solution casting. The Change in electrical conductivity of pure PVA and transition elements FeCl3 and NiCl2∙6H2O doped PVA films with and without γ-irradiation in the temperature range 50-130 C has been investigated using four point probe technique. The dc electrical conductivity increases with increase in dopant concentration, with temperature and γ-irradiation. The results revealed that γ-irradiation enhances the electrical conductivity. The variation of electrical conductivity σ with temperature, before and after irradiation is due to the intermolecular hydrogen bonding between Fe3+ with OH group of PVA and Ni2+ with OH group of PVA.We found that Fe3+ doped PVA films show higher conductivity than Ni2+ doped PVA films. [ABSTRACT FROM AUTHOR]

This paper presents the characterization of the integrated passive components (resistor) into a thin film multi layer system or integrated passive device (IPD). To realise integrated resistor for adjusting the sheet resistance, good pattern properties as well as low temperature coefficient, two metal layers are required. Hence, Ni-Cr and Pt are chosen in the present study. Al-Cu/Ni-Cr/Pt is deposited on Al2O3 and Si substrate using High Rate Magnetron (HRM) sputtering. To find the suitability of substrates, the electrical and mechanical characterizations for pure and thermally annealed (in argon atmosphere) samples have been studied. Micro hardness studies of films on Oxide substrate show regular square indentation up to 500 gms. There is no deformation, no diffusion for both the pure and the annealed samples. But multi layer on Si substrate has answered for noticeable inter diffusion above 475°C annealing as well as variation in H factor after 200 gm. At 500 gm load, the thin film started peeling off. The pure and the annealed samples on oxide substrate have shown very less variation of resistivity ρ with temperature in the range RT to 200°C. But variation of ρ on Si substrate was faster and more for different annealed temperatures. This is due to the mobility variation, development of voids (as confirmed by SEM) and/or inter diffusion of Si with the other metals. The investigations confirm that resistive layers on Oxide substrate are more stable with less loss. [ABSTRACT FROM AUTHOR]