Neutron Diffraction Studies on Chemical and Magnetic Structure of Multiferroic PbFe0.67W0.33O3

We report on the single phase synthesis and room temperature structural characterization of PbFe0.67W0.33O3 (PFW) multiferroic. The PFW was synthesized by low temperature sintering, Columbite method. Analysis of powder XRD pattern exhibits single phase formation of PFW with no traces of pyrochlore phase. Detailed analysis of room temperature neutron diffraction (ND) reveals cubic phase at room temperature, space group Pm-3m. The ND pattern clearly reveals magnetic Bragg peak at 2theeta = 18.51 (Q = 1.36{\AA}-1). The refinement of magnetic structure reveals G-type antiferromagnetic structure in PFW at room temperature. The dielectric constant and loss tangent decreases with increasing frequency. The room temperature P-E measurements shows a non-linear slim hysteresis, typical nature of relaxor multiferroics, with saturation and remnant polarizations of Ps = 1.50 microC/cm2 and Pr = 0.40 microC/cm2, respectively.Comment: 3 pages, 5 figures, conferenc

K-Means and Fuzzy based Hybrid Clustering Algorithm for WSN

Wireless Sensor Networks (WSN) acquired a lotof attention due to their widespread use in monitoring hostileenvironments, critical surveillance and security applications. Inthese applications, usage of wireless terminals also has grownsignificantly. Grouping of Sensor Nodes (SN) is called clusteringand these sensor nodes are burdened by the exchange of messagescaused due to successive and recurring re-clustering, whichresults in power loss. Since most of the SNs are fitted with nonrechargeablebatteries, currently researchers have been concentratingtheir efforts on enhancing the longevity of these nodes. Forbattery constrained WSN concerns, the clustering mechanism hasemerged as a desirable subject since it is predominantly good atconserving the resources especially energy for network activities.This proposed work addresses the problem of load balancingand Cluster Head (CH) selection in cluster with minimum energyexpenditure. So here, we propose hybrid method in which clusterformation is done using unsupervised machine learning based kmeansalgorithm and Fuzzy-logic approach for CH selection

Impedance studies on high energy Li3+ irradiated PZT thin films

The ferroelectric Pb(Zr0.48Ti0.52)O3 (PZT) thin films prepared by the pulsed laser deposition technique were studied for their response to high energy lithium ion irradiation through impedance spectroscopy. The Debye peaks, observed in the impedance and modulus plots of irradiated films, shifts towards higher frequencies compared to those of unirradiated films. This is equivalent to the trend observed with increase in temperature in the unirradiated films due to the dielectric relaxation. The irradiated films showed a decrease in the grain resistance compared to the unirradiated films. The activation energy of dielectric relaxation increases from 1.25 eV of unirradiated film to 1.62 eV of irradiated film. The observed modifications in the irradiated film were ascribed to the modifications in the grain structure due to the high value of electronic energy loss. © 2009 Elsevier B.V. All rights reserved

Single Phase Synthesis; Neutron Diffraction and Dielectric Studies on 0.6PbFe0.5Nb0.5O3-0.4BiFeO3 Multiferroic

0.6Pb(Fe0.5Nb0.5)O3-0.4BiFeO3 (0.6PFN-0.4BFO) multiferroic solid solution was synthesized by single step solid state reaction method. The optimized synthesis parameters for 0.6PFN-0.4BFO multiferroic was calcination at 700 °C /2 hr and sintering at 800 °C /3 hr. Single phase was confirmed though room temperature X-ray Diffraction (XRD) and room temperature Neutron Diffraction (ND). XRD and ND data were well fitted with monoclinic structure with Cm space group. The magnetic structure was refined using the propagation vector k = (0.5; 0.5; 0.5) and the structure was found to be G-type antiferromagnetic. The dielectric constant and loss tangent of 0.6PFN-0.4BFO shows the frequency and temperature dependent nature. Loss tangent exhibits the thermally dependent relaxation peaks. 0.6PFN-0.4BFO is a potential candidate for above room temperature applications

Evaluation of clopidogrel on acute and sub-acute models of inflammation in male Wistar rats

Background: Atherosclerosis and its complications remain the major cause of death and premature disability. Atherogenesis involves elements of inflammation, a process that now provides a unifying theme in the pathogenesis of the disease. Anti-platelet drugs are currently used in the treatment of atherosclerosis and its complications. Our study evaluated the influence of clopidogrel on acute and sub-acute models of inflammation in male Wistar rats.Methods: Male Wistar rats (150-200 g) were divided into three groups, i.e. control, aspirin and clopidogrel (n=6 animals in each group). The effect of clopidogrel administered orally on inflammation was studied using acute (carrageenan-induced rat paw edema) and sub-acute (cotton pellet granuloma and histopathological examination of grass piths) models. Experiment was conducted according to the Committee for the Purpose of Control and Supervision on Experiments on Animals guidelines. Analysis was done using one-way ANOVA followed by post-hoc test of Dunnets. p<0.05 was considered as statistically significant.Results: Clopidogrel showed significant inhibition of rat paw edema in acute model (p<0.01) and granuloma dry weight, in sub-acute model of inflammation when compared to control (p<0.01). Histopathological examination of grass pith revealed markedly reduced fibroblasts, granulation tissue, fibrous tissue and collagen in clopidogrel group when compared to control.Conclusion: Clopidogrel exhibited a significant anti-inflammatory activity in acute and sub-acute models of inflammation

Investigation on structural, Mossbauer and ferroelectric properties of (1-​x)​PbFe0.5Nb0.5O3-​(x)​BiFeO3 solid solution

(1-​X)​PbFe0.5Nb0.5O3(PFN)​-​(x)​BiFeO3(BFO) multiferroic solid solns. with x = 0.0, 0.1, 0.2, 0.3 and 0.4 were synthesized through single step solid state reaction method and characterized thoroughly through x-​ray Diffraction (XRD)​, SEM, Fourier Transform Infra-​Red (FTIR)​, Raman, Mossbauer spectroscopy and ferroelec. studies. The room temp. (RT) XRD studies confirmed the formation of single phase with negligible amt. of secondary phases (x = 0.2 and 0.4)​. The zoomed XRD patterns of (1-​x)​PFN-​(x)​BFO solid solns. showed the clear structural phase transition from monoclinic (Cm) to rhombohedral (R3c) at x = 0.4. The Raman spectra of the (1-​x)​PFN-​(x)​BFO solid solns. showed the compn. dependent phase transition from monoclinic (Cm) to rhombohedral (R3c)​. With increasing x in PFN, the modes related monoclinic symmetry changes to those of rhombohedral symmetry. The RT Mossbauer spectroscopy results evidenced the existence of compn. dependent phase transition from paramagnetic to weak antiferromagnetic ordering and weak antiferromagnetic to antiferromagnetic ordering. The Mossbauer spectroscopy showed paramagnetic behavior with a doublet for x = 0.0, 0.1 and 0.2 are shows the weak antiferromagnetic with paramagnetic ordering. For x = 0.3 and 0.4 shows the sextet pattern and it is a clear evidence of antiferromagnetism. The ferroelec. (P-​E) loops at RT indicate small polarization, as the x concn. increases in PFN, the remnant polarization and coercive field were decreased, which may due to the increase in the cond. and leaky behavior of the samples

Carrier transport mechanisms of hybrid ZnO nanorod-polymer LEDs

A hybrid polymer-nanorod (NR) light-emitting diode (LED), consisting of a hole-conducting polymer poly (9-vinyl carbazole) (PVK) and ZnO nanorod (NR) composite, with the device structure of glass/indium-tin-oxide (ITO)/PEDOT:PSS/(PVK + ZnO nanorods)/Al is fabricated through a simple spin coating technique. TEM images shows inhomogeneous deposition and the agglomeration of ZnO NRs, which is explained through their low probability of adsorption on PVK due to two-dimensional structural property. In the current-voltage characteristics, negative differential resistance (NDR) phenomenon is observed corresponding to device structure without ZnO NRs. The carrier transport behavior in the LED device is well described by both ohmic and space-chargelimited-current (SCLC) mechanisms. Broad blue electroluminescence (EL) consisting of two sub peaks, are centered at 441 nm and the other at 495 nm, is observed, which indicates that the ZnO nanorod play a role as a recombination center for excitons. The red shift in the position of the EL compared to that photoluminescence is well explained through band offsets at the heterojunction between the PVK and ZnO NRs

Fabrication and surface plasmon coupling studies on the dielectric/Ag structure for transparent conducting electrode applications

The dielectric/Ag structures were fabricated on glass substrates using various metal oxides as dielectrics and their optical properties were studied through transmittance and ellipsometry measurements. The structures with 10 nm Ag film deposited on various metal oxides (Al2O3, ZrO2, SrTiO3, TiO2, CaCu3Ti4O12, WO3 and HfO2) of 30 nm showed enhancement in transmittance compared to bare Ag film in the visible region. This enhancement in transmittance was explained through suppression of surface plasmon coupling at the dielectric/Ag interface. The surface plasmon wave-vector (k(SP)) was calculated using the measured dielectric constants for the dielectric and Ag through ellipsometry and employed to analyze the transmittance data. The k(SP)/k(0) and delta(SP) values were estimated and used to interpret the enhanced visible transmittance for different dielectric/Ag structures. (C) 2014 Optical Society of Americ

Effect of RF power on the structural, optical and gas sensing properties of RF-​sputtered Al doped ZnO thin films

The effect of Radio Frequency (RF) power on the properties of magnetron sputtered Al doped ZnO thin films and the related sensor properties are investigated. A series of 2 wt​% Al doped ZnO; Zn0.98Al0.02O (AZO) thin films prepd. with magnetron sputtering at different RF powers, are examd. The structural results reveal a good adhesive nature of thin films with quartz substrates as well as increasing thickness of the films with increasing RF power. Besides, the increasing RF power is found to improve the crystallinity and grain growth as confirmed by X-​ray diffraction. On the other hand, the optical transmittance is significantly influenced by the RF power, where the transparency values achieved are higher than 82​% for all the AZO thin films and the estd. optical band gap energy is found to decrease with RF power due to an increase in the crystallite size as well as the film thickness. In addn., the defect induced luminescence at low temp. (77 K) and room temp. (300 K) was studied through photoluminescence spectroscopy, it is found that the defect d. of electronic states of the Al3+ ion increases with an increase of RF power due to the increase in the thickness of the film and the crystallite size. The gas sensing behavior of AZO films was studied for NO2 at 350 °C. The AZO film shows a good response towards NO2 gas and also a good relationship between the response and the NO2 concn., which is modeled using an empirical formula. The sensing mechanism of NO2 is discussed