Microstructure and Magnetic Properties of Sn<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ni<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2</Subscript> Thin Films Prepared by Flash Evaporation Technique

An effort was made to develop semiconductor oxide-based room temperature dilute magnetic semiconductor (DMS) thin films based on wide band gap and transparent host lattice with transition metal substitution. The Sn\(_{\mathrm {1}-x}\)Ni\(_{x}\textit {O}_{\mathrm {2}}\) (\(x\,= \mathrm {0.00, 0.03, 0.05, 0.07, 0.10, and \,0.15}\)) thin film samples were prepared on glass substrates by flash evaporation technique. All the samples were shown single phase crystalline rutile structure of host SnO\(_{\mathrm {2}}\) with dominant (110) orientation. The Ni substitution promotes reduction of average crystallite size in SnO\(_{\mathrm {2}}\) as evidenced from the reduction of crystallite size from 40 (SnO\(_{\mathrm {2}}\)) to 20 nm (Sn\(_{\mathrm {0.85}}\)Ni\(_{\mathrm {0.15}}\textit {O}_{\mathrm {2}}\)). In the energy dispersive spectra as well as X-ray photoelectron spectra of all the samples show, the chemical compositions are close to stoichiometric with noticeable oxygen deficiency. The crystalline films were formed by coalescence of oval-shaped polycrystalline particles of 100 nm size as evidenced from the electron micrographs. The energy band gap of DMS films decreases from 4 (SnO\(_{\mathrm {2}}\)) to 3.8 eV (x \(=\) 0.05) with increase of Ni content. The magnetic hysteresis loops of all the samples at room temperature show soft ferromagnetic nature except for SnO\(_{\mathrm {2}}\) film. The SnO\(_{\mathrm {2}}\) films show diamagnetic nature and it converts into ferromagnetic upon substitution of 3 % Sn\(^{\mathrm {4+}}\) by Ni\(^{\mathrm {2+}}\). The robust intrinsic ferromagnetism (saturation magnetization, 21 emu/cm\(^{\mathrm {3}}\)). Further increase of Ni content weakens ferromagnetic strength due to Ni-O antiferromagnetic interactions among the nearest neighbour Ni ions via O\(^{\mathrm {2-}}\) ions. The observed magnetic properties were best described by bound magnetic polarons model.     

A simple boundary extraction technique for irregular pupil localization with orthogonal polynomials

A simple boundary extraction technique for irregular pupil boundary localization is proposed in this paper by designing a new Where-to-go approach that extracts the irregular pupil boundary points from the edge map. Initially, the input eye image is subjected to the orthogonal polynomials model and then Hartley’s statistical hypothesis testing is employed to separate out the responses towards noise from those towards strong edges in the eye image. Then the proposed boundary extraction technique is employed to extract the pupil boundary points perfectly and it is independent of the specific eye image characteristics such as pupil deformation, poor contrast, poor brightness, etc. The proposed approach is adaptable to all monochrome databases and exhibits encouraging results when compared with the existing techniques.     

Synthesis,characterization of β-CD based novel hydrogels with dual objectives of drug release and dye removal

Iranian Polymer Journal - In our recent work, we have reported on hydrogels devoid of cross-linkers. After observing the successful swelling and water retention properties, we have introduced...     

Diffusion bonding of SU 263

Using a specially constructed apparatus, diffusion bonding of SU 263 alloy was studied in the temperature range of 1123–1323 K and compressive stress of 90% of its yield strength at the corresponding temperatures to determine the relative importance of the process parameters, the mechanism(s) responsible for bonding and the joint characteristics. Bond quality was assessed by optical metallography and lap shear testing. The mechanism of bonding was evaluated by grain growth equation. The experimental results were compared with a model developed by Pilling [Pilling, J., 1988. The kinetics of isostatic diffusion bonding in superplastic materials. Mater. Sci. Eng. 100, 137–144] in which the void closure by creep flow and diffusion are considered. Quantified EPMA line scan analysis was carried out to confirm the bonding mechanism and to determine the composition at the interface.     

Energy Sensitive Cluster Level Security Selection Scheme for MANET

Wireless Personal Communications - Most of the current Mobile Ad hoc Network (MANET) nodes are battery powered devices with different processing and data handling capacities. The ratio of sensitive...     

Business analytics and business value: A comparative case study

With growing adoption of business analytics, it is important for investing firms to understand how business value is created from investments. Studies in IT domain have highlighted how higher investment in technology may not bring more returns, rather how IT as an organizational capability acts as a key mediator in value creation. This research extends the model to business analytics, to identify elements of analytics technology assets and business analytics capability and to understand the mechanism of business value creation using multiple case studies. We capture how analytics resources contribute to business performance by developing operational and organizational performance measures.     

Characterization and solution properties of a partially hydrolyzed graft copolymer of polyacrylamide and dextran

Graft copolymers of dextran (Dx) and polyacrylamide (PAM) were synthesized through the grafting of PAM chains onto a Dx backbone with a ceric‐ion‐induced solution polymerization technique. By the variation of the amount of the initiator (ceric ammonium nitrate), four different grades of graft copolymers were synthesized. The partial alkaline hydrolysis of Dx‐g‐PAM was carried out in an alkaline medium. Three grades of partially hydrolyzed products were synthesized through the variation of the amount of alkali. These hydrolyzed graft copolymers were characterized with elemental analysis, infrared spectroscopy, neutralization equivalent measurements, a rheological technique, scanning electron microscopy, thermal analysis, viscometry, and X‐ray diffraction. The flocculation efficiency and viscosifying characteristics of the graft copolymers were enhanced upon their alkaline hydrolysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Carbothermal synthesis, spectral and magnetic characterization and Li-cyclability of the Mo-cluster compounds, LiYMo3O8 and Mn2Mo3O8

The molybdenum cluster compounds, LiYMo₃O₈ and Mn₂Mo₃O₈ are prepared by the carbothermal reduction method and characterized by various techniques. The FT-IR at ambient temperature (RT), and Raman spectra at various temperatures (78-450 K) are reported for the first time and results are interpreted. Magnetic studies on Mn₂Mo₃O₈ in the temperature range, 10-350 K confirm that it is ferrimagnetic, with T_C = 39 K. Magnetic hysteresis and magnetization data at various fields and temperatures are presented. The Li-cyclability is investigated by galvanostatic cycling in the voltage range, 0.005-3.0 V vs. Li at 30 mA/g (0.08 C). LiYMo₃O₈ shows a total first-discharge capacity of 305 ±5 mAh/g whereas the first-charge capacity is only 180 mAh/g at RT. However, both values increased systematically with an increase in the cycle number and yielded a reversible capacity of 385 ±5 mAh/g at the end of 120th cycle. At 50 °C, the reversible capacity is 418 ±5 mAh/g at the 60th cycle. The coulombic efficiency ranges from 94% to 98%. The Li-cyclability behavior of Mn₂Mo₃O₈ is entirely different from that of LiYMo₃O₈. The total first-discharge and charge capacities are 710 ± 5 and 565 ±5 mAh/g, but drastic capacity-fading occurs during cycling. The reversible capacity at the end of 50th cycle is only 205 ±5 mAh/g. Plausible reaction mechanisms are proposed and discussed based on the galavanostatic cycling, cyclic voltammetry, ex situ XRD, ex situ TEM and impedance spectral data.     

Synthesis,characterization, and ion exchange voltammetry study on 2‐acrylamido‐2‐methylpropane sulphonic acid and N‐(hydroxymethyl) acrylamide‐based copolymer

A random copolymer of 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) and N‐hydroxymethyl acrylamide (NHMA) was prepared by solution polymerization using ceric ammonium nitrate as an initiator. A grade of poly(AMPS)‐co‐poly(NHMA) (PAMPS‐co‐PNHMA) random copolymer was synthesized with AMPS and NHMA. The homopolymerization of AMPS and NHMA was also carried out by the same way as that of random copolymer. PAMPS‐co‐PNHMA and homopolymers of AMPS and NHMA were characterized by FTIR, rheology, FT‐NMR, scanning electron microscope, thermal analysis, and X‐ray diffaractometry. Cyclic voltammetry is used to explain the ion exchange properties of PAMPS‐co‐PNHMA and its possible application in the trace analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011