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The electromagnetic interference shielding effectiveness (EMI SE) of amorphous and annealed melt-spun ribbons having typical composition of Co72.5Si12.5B15, (Fe0.65Co0.35)83Si1.3B11.7Nb3Cu1, Fe80Si8B12 and Fe83Si2B13Nb2 were studied in the 0.2–8.5 GHz microwave range. The amorphous nature of the as-quenched ribbons was confirmed by X-ray diffraction patterns and differential scanning calorimetry (DSC). The flexible electromagnetic wave absorber ribbons of CoSiB, FeSiB, and FeCoSiBNbCu based alloys exhibit ∼99.99% attenuation of electromagnetic waves in the entire 0.2–8.5 GHz (L, S and C-band) range. Both as-quenched and annealed amorphous ribbons of Co72.5Si12.5B15 and Fe80Si8B12 are electromagnetically active and total electromagnetic shielding effectiveness (SET) of ribbons found to be ∼36 dB, ∼34 dB throughout the test range. The EMI shielding properties deteriorates for FeCoSiBNbCu and FeSiBNb based nanocomposite ribbons achieved by in-situ crystallization annealing. The electromagnetic shielding of magnetic ribbons is effected mainly by absorption mechanism due to high electrical resistivity and magnetic permeability. The CoSiB and FeSiB melt-spun ribbons can be a potential magnetic filler for military and stealth applications in L, S and C-band range.

To understand the effect of nitrogen doping in hard carbon as anode for sodium ion battery, experimental and theoretical study have been done. To also see the size effect along with nitrogen doping, four varieties of carbon spheres are synthesized of two different size ranges viz. micron and nano-sized. Two of these spheres are nitrogen-doped, while the other two are un-doped. Nitrogen doping enhances the electrochemical performance of carbon spheres and increases the active storage sites by enhancing the number of defects and porosity. It further improves electrochemical performance by increasing electrical conductivity and controlling volume expansion. The density functional theory (DFT) study shows significant reduction in expansion associated with sodiation, i.e., from 21.7% to 7.9% because of nitrogen doping. After nitrogen doping, micron and nano-sized carbon spheres show an increase in capacity by 38.6% and 39.5%, respectively. Among these four electrodes, nitrogen-doped nano carbon spheres (NNCS) give the best performance. NNCS shows first reversible capacity of 286 mAh g−1, retains 85% of the capacity till 200 cycles at a current density of 30 mAg−1. This increase in electrical conductivity, defects, porosity, and reduction in volume expansion in nitrogen-doped carbon samples makes them an excellent material for sodium ion batteries.

Herein, Fe3O4 nano-particles are anchored over nitrogen doped reduced graphene oxide (Fe3O4@N-rGO) structure to accommodate electric and magnetic components, so that it could match both the conduction and polarization loss to augment the attenuation of electromagnetic radiation. The formation of condensed heteroaromatic structure and decoration of Fe3O4 particles on r-GO structure are confirmed by photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD). The Fe3O4@N-rGO hybrid is subsequently dispersed in epoxy matrix, which result in significantly higher electrical conductivity (1.31 s/m) and electromagnetic interference (EMI) shielding efficiency (−26 dB at 1 mm thickness). It was assumed that presence of electric-magnetic integrated Fe3O4@N-rGO hybrid in epoxy matrix significantly improved the interfacial polarization and anisotropy energy, which was reflected in absorption loss value of −27 dB. The composites also exhibited enhanced mechanical and thermo-mechanical properties coupled with improved thermal stability.

Boron based solid fuels have remained attractive for solid fuel ducted rocket (SFDR) applications since long due to their potential to release high energy on combustion. However, boron's energetic potential has not been successfully harnessed even till date in any practical combustion system. In view of this, present investigation is focused on utilizing boron nanoparticles embedded in paraffin-wax in various proportions (5–20% by weight) as solid fuel. To evaluate its performance an opposed flow burner (OFB) is used in presence of gaseous oxygen (GOX) and the oxidizer mass flux (Gox) varies from 5 to 30 kg/m2 s to estimate its regression rates relative to paraffin-wax. Burning process of boron loaded samples was captured using a high-speed camera to understand the ejection trajectory of the particles/agglomerates. Further, different material characterization techniques were employed on the pre- and post-burnt samples to understand the chemical and morphological changes and interlink that with overall burning characteristics. The active boron content determined from thermogravimetric analysis of pre-burnt sample, ejected agglomerates and post-burnt residue were 78.8, 34 and 18.7% respectively which confirm the combustion of boron nanoparticles up to a significant extent in the present OFB configuration. The present study may be helpful in futuristic application of hybrid propellant-based gas generator for SFDR systems.

We report a study on the competition between soft ferromagnetism (FM) and enhanced Pauli paramagnetism (PM) in Ce(Fe 1− x Ni x ) 2 ( x =0.0, 0.5, 0.8) compounds under doping. We provide convincing experimental evidence for the occurrence of a ferromagnetic (FM) phase and a paramagnetic (PM) phase at different concentrations. The quality of the samples was established by X-ray diffraction and X-ray photoelectron spectroscopy. Quantification of f - d hybridization was made from high-resolution X-ray photoelectron spectroscopy. A proportionality was found between ‘ x ' dependencies of fall of f - d hybridization strength and magnetic order. A prediction that a quantum critical point may exist at a nickel concentration x close to 0.69 can be made from the extrapolation of x dependent Curie temperature (T c ) plot.

First-principles density functional theory computations of electronic structure and local magnetic properties of the non-fluctuating ground state of Ni x Pd 1 − x alloy system around its quantum critical point xc=0.026 have been performed. The density of states at the Fermi energy and certain other parameters characterizing the Ni 3 d − Pd 4 d hybridization apparently follow power-laws with x similar to that obeyed by the reported ferromagnetic to paramagnetic transition temperature. The width of Pd 4 d density of states (DOS) and centroid of Ni 3 d DOS show peak-like anomalies in the neighbourhood of xc, and so indicate a possible scenario of the existence of a definite relation between the orbital hybridization and the emergence of quantum fluctuations in the system.

Inspired by hazardous effects of electromagnetic waves on human health related to increasing exposure to electronic devices in day-to-day life we have developed a low cost, light weight and flexible EMI shielding material based on exfoliated graphite nanoplatelets (xGnP) filled ethylene vinyl acetate (EVA)/Ethylene-octene copolymer (EOC) blend composite by melt mixing method. X-ray diffraction revel that inclusion of xGnP affect the crystallinity of EVA/EOC blend which has also been seconded by differential scanning calorimetry (DSC) analysis. Electromagnetic interference (EMI) shielding effectiveness of the nanocomposites and electromagnetic properties were conducted over microwave frequency range of 1.5–8 GHz. It has been observed that with inclusion of xGnP into EVA/EOC matrix there is significantly improvement of EMI SE values in S- band (2–4 GHz) region and highest total EMI SE value of −67.63 dB at 30 wt% of xGnP loading was achieved mainly due to absorption mechanism. The composite exhibit ac conductivity of 455.8 S/m which is much higher than that of neat EVA/EOC blends. The dc conductivity 5.3 × 10−8 S/m was obtained for 30 wt% xGnP EVA/EOC blend. To our belief, this EVA/EOC/xGnP composite can be utilized as an efficient EMI shielding material in S-band.

MoS 2 -reduced graphene oxide (MoS 2 -rGO: where rGO = 0, 1, 3, 5, 7 and 10 wt%) hybrids have been fabricated using (NH 4 ) 2 MoS 4 and graphite oxide as single source precursors of MoS 2 and thermally exfoliated reduced graphene oxide respectively. These individual precursors were initially subjected to grinding for 30 min followed by heating at 1200 °C for 15 min and characterized. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM) confirmed co-dispersion of MoS 2 on thermally exfoliated graphite oxide. Electrochemical studies of these hybrids as anode materials showed that MoS 2 -rGO (7 wt%) exhibited superior reversible capacity, cycling stability, enhanced rate performance (780 mAhg −1 ) and rate capability (880 mAhg −1 ) over pristine MoS 2 and other hybrids.

W–Mo nanoalloys of variable compositions with average sizes ~ 40 nm were synthesized using a single step soft chemical approach in presence of l -cysteine. FTIR study reveals that l -cysteine binds to the surface of W–Mo nanoalloys via a thiolate linkage, which renders stability with respect to aggregation and growth. As-synthesized W–Mo alloys are found to be amorphous and bcc crystalline peaks developed on annealing at 600 °C. In addition, the effect of nanoscale particles on densification behavior of W–Mo alloy has also been investigated. The relative density of W–19.9 wt.% Mo, W–30.4 wt.% Mo and W–40.2 wt.% Mo alloy compacts sintered at 1600 °C is maximum achieved corresponding to 97.5, 98.1 and 98.9 % respectively. Further, superior Vickers hardness has been achieved in the sintered specimens compared to those obtained from microcrystalline or mechanically alloyed powders.

The present work reports a soft chemical approach for synthesis of nanostructured W 10–20 wt.% Ti alloys and its characterization. Though, the as-prepared products are amorphous, they developed crystalline phases when annealed at 600 °C due to the presence of bcc and hcp structure of W and Ti respectively. ESEM and TEM studies show that the sizes of as-synthesized powders ranged between 30 and 50 nm. W-10–20 wt.% Ti alloys, when sintered at 1400 °C for 1 h, exhibit relative density, Vickers hardness and electrical resistivity varying between 98.4–99.1%, 506–595 Hv and 6.28–7.43 μΩ-cm respectively.

Single-walled carbon nanotubes (SWCNTs) have been synthesized by electric arc discharge method using annealed coal electrode in the presence of Fe as well as Ni–Y as catalysts. Multi-walled carbon nanotubes (MWCNTs) have been synthesized without using any catalysts. The efforts have also been made to synthesized graphene like nanosheets from bituminous coal. The as-synthesized samples have been characterized through scanning and transmission electron microscopy, Raman and Fourier transform infrared spectroscopy. The formation of SWCNTs which holds nearly perfect one dimensional structure is confirmed by the presence of radial breathing mode. A feasible mechanism of CNTs formation from coal described here with the help of Fourier transform infrared spectroscopy.

The present study is focused on synthesis of polyaniline hollow microspheres (PnHM) nanocomposites of silver (Ag) i.e., PnHMAg by emulsion polymerization of aniline and Tollen’s reagent as a source for Ag nanoparticles. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis of PnHMAg indicated presence of silver nanoparticles dispersed on polyaniline surface. The electrical conductivity of PnHMAg is increased by ∼6 times compared to PnHM. Cyclic voltammogram of PnHM in sugar sensing exhibits characteristics redox peaks at ∼0.09 (sugar) and ∼0.53 V (polyaniline). Interestingly, PnHMAg showed a single peak at ∼−0.18 V with increased intensity (∼5 times) indicating its high sugar sensing ability. PnHMAg also exhibits high shielding efficiency of 19.5 dB (11.2 GHz) due to the presence of highly conducting Ag nanoparticles. TEM studies confirmed that Ag nanoparticles are well distributed on PnHM. As a result, a continuous electronic path is developed due to enhanced interconnectivity of PnHM.

Two simple fluorescent chemosensors ( CS1 & CS2 ) based upon salicylideneimine derivatives were evaluated for their selective fluorescent sensing of Al 3+ . An attractive glowing green/blue colour was observed in the presence of Al 3+ with dual channel emissions for CS1 ( λ em 499 & 535 nm) and CS2 ( λ em 485 & 515 nm) both. The inhibition of PET and C N isomerization after Al 3+ binding was responsible for the turn ‘ on ’ fluorescence response while the dual emissions were well justified in terms of ESIPT and ICT. The binding stochiometries between CS1 / CS2 and Al 3+ were found to be 1:1 and 2:1 respectively while the limit of detection (LOD) of Al 3+ by CS1 was found to be ∼10 times lower than that of CS2 .

Green reduction of graphene oxide (GO) using drained water from soaked mung beans ( Phaseolus aureus L.) has been demonstrated. In comparison to the toxic and hazardous reducing chemicals, the drained water from soaked mung beans ( P. aureus L.) is completely green reducing agent, the reduction process is very simple and cost effective. The removal of oxygen containing functional groups of GO has been confirmed by UV–vis, Fourier transform infrared and X-ray photoelectron spectroscopy analysis. Morphological characterization of rGO has been performed by atomic force and transmission electron microscopy analysis. Electrochemical performances of rGO have been evaluated by cyclic voltammetry (CV), charge–discharge and electrochemical impedance spectroscopy techniques. The specific capacitance (SC) of rGO has been found to be 137 F g −1 at a current density of 1.3 A g −1 . The retention in SC is more than 98% after 1000 charge–discharge cycles suggesting long-term electrochemical cyclic stability as supercapacitor electrode materials.

The dispersion of filler and filler–matrix interfacial interaction are crucial factors to improve the properties of nanocomposites. In the present work, the dry grinding of 1D multiwalled carbon nanotube (MWCNT) and 2D layered double hydroxides (Li–Al-LDH, Mg–Al-LDH and Co–Al-LDH) have been used to prepare the corresponding 3D Li–Al-LDH/MWCNT, Mg–Al-LDH/MWCNT and Co–Al-LDH/MWCNT hybrids and characterized. Subsequently, these 3D hybrids are used as nanofiller in the development of silicone rubber (SR) nanocomposites. Tensile strength is found to be significantly improved by 134%, 100% and 125% compared to neat SR in 1 wt.% Mg–Al-LDH/MWCNT, Li–Al-LDH/MWCNT and Co–Al-LDH/MWCNT hybrids filled SR nanocomposites respectively. It is also noted that Mg–Al-LDH/MWCNT/SR nanocomposites exhibit superior thermal stability and swelling behavior. The best effect of Mg–Al-LDH/MWCNT on SR compared to other hybrids is related to the highest surface area which contributes to nanolevel dispersion and strong interfacial interaction between Mg–Al-LDH/MWCNT and SR matrix.

γ-MnS nanocrystalline materials have been prepared by reaction of Na 2 [Mn(HL) 2 (H 2 O) 2 ]; 1:2 (M:L) chelate complex with alkaline solution of thiocarbamide in aqueous solution phase. Effect of metal chelate complex, reaction time and surfactant sodium dodecyl sulfate; SDS on phase, morphology and size of the products have been investigated. The metal chelate complex was synthesized by reacting Mn(II) ions with eriochrome black T (NaH 2 L) in alkaline medium. γ-MnS crystals were formed when metal complex was used as metal source whereas Mn 3 O 4 was the dominant product when MnSO 4 ·H 2 O was used as metal source. Materials thus formed having various morphologies were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) to determine the crystallinity, phase, structure and morphology. The optical properties of the thus prepared samples were determined by UV–vis absorption spectra and photoluminescence spectra. A possible formation mechanism of crystals has been discussed in this article.

Helical waveguide, a different type of waveguide structure, has been considered for analysis of modal dispersion characteristics. This paper deals with the study of a new type of annular waveguide, in which the inner cladding is made by the helical windings i.e. sheath helix and the outer cladding is as usual simple step-index cladding. Using vector approach, the general characteristic equation for the proposed waveguide has been derived. The modal dispersion characteristics for the lowest order modes for different pitch angles and thickness are determined and analyzed. We have found that there is an existence of the negative dispersion curve in the helically inner cladded annular circular waveguide. It means that the inner cladding is responsible for the negative dispersion which is generally obtained in a photonic band gap.

In the present investigation, W 20–40wt.% Cu nanocomposite powders with average sizes ranging between 25 and 30 nm were synthesized by a soft chemical approach using tungsten hexacarbonyl [W(CO) 6 ] and copper acetonyl acetonate [Cu(acac) 2 ] as metal precursors. Particle size, morphology and distribution were measured using transmission electron microscope (TEM) and small angle X-ray scattering (SAXS). Surfactant coating on W Cu composite powders was removed on heat treatment of powders at 450 °C in hydrogen atmosphere for 1 h. Elemental analyses of as-synthesized and annealed (at 450 °C) W Cu nanocomposite powders were carried out using inductively coupled plasma-optical emission spectrometer (ICP-OES) and Leco gas analyzers. X-ray diffraction studies showed that the tungsten phase is amorphous while the crystal structure of copper phase is fcc in as-synthesized W Cu nanocomposite powders. After annealing at 700 °C peaks corresponding to bcc tungsten are observed and peaks corresponding to fcc copper become sharper. Relative densities of 98.2%, 98.8% and 99.2% were achieved for W 20wt.% Cu, W 30wt.% Cu, and W 40wt.% Cu composite powders respectively when sintered at 1000 °C.

High purity single crystalline trigonal selenium (t-Se) with different morphologies (wires, rods, flowerlike, and hollow spheres) have been synthesized under hydrothermal conditions through simple one-step at lower temperature (120 °C) using in situ generated sulphurous acid as a new reducing agent. It is noted that the experimental parameters such as reaction duration, temperature and surfactants have an effective and important influence on the formation of different morphologies. The phase analysis, purity, morphology and optical properties of the as obtained products have been characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis spectroscopy, respectively. A possible reaction scheme as well as growth mechanism has been proposed for the formation of t-Se nanowires.

The present work aims at the formation of good quality nanorods of Sb 2 Se 3 by using alkaline selenium solution and SbCl 3 in presence of hydrazine hydrate as reducing agent and carrying out reaction under hydrothermal conditions at 150 °C for 12 h. X-ray diffractogram of the product could be indexed on the basis of the pure orthorhombic phase. The nanorods formed are of diameter around 40–100 nm and length could be of several micrometers. The band gap of the nanorods is found to be 1.78 eV. Photoluminescence of the Sb 2 Se 3 nanorods excited at 450 nm showed emission peak at 587 nm.

We present the first ever experimental Compton profiles of molybdenum dichalcogenides (MoX 2 ; X=S and Te) using 20 Ci 137 Cs Compton spectrometer. To interpret our experimental data, we have computed the theoretical profiles, energy bands and density of states using linear combination of atomic orbitals method in the framework of density functional theory and its hybridisation with Hartree Fock. The energy bands and density of states using full potential linearised augmented plane wave method have also been computed. Both theories show the existence of the indirect band gap. In addition, the relative nature of bonding is explained in terms of equal-valence-electron-density profiles and valence band charge densities.

Tungsten nanoparticles were prepared by thermal decomposition of tungsten hexacarbonyl [W(CO) 6 ] (2 mmol) at 160 °C in presence of a mixture of (1:1) surfactants, oleic acid (6 mmol) and trioctyl phosphine oxide (TOPO) (6 mmol) under a blanket of Ar gas. The synthesized tungsten nanoparticles without surfactant are flocculated. With increase in concentration of surfactant mixture to 12 mmol each, agglomeration of several tungsten nanoparticles are observed. Characterization of surfactant coated tungsten nanoparticles were carried out using Fourier transform infrared spectroscopy (FTIR). Chemical characterizations of synthesized tungsten nanoparticles were done using X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectrometry (ICP-OES) and LECO gas analyzers. XPS study shows the W 0 oxidation state of tungsten nanopowders. Structural characterization of synthesized tungsten nanoparticles were conducted by X-ray diffraction (XRD), which shows that the as-synthesized tungsten nanoparticles are amorphous in nature and they become body centered cubic crystalline after annealing. Particle size, shape and distribution were characterized using small-angle X-ray scattering (SAXS), environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM).

In this paper, we report the first ever experimental Compton profile study of WS 2 and WSe 2 employing 20 Ci 137 Cs Compton spectrometer. To interpret our experimental data, the electronic properties of these compounds have been determined by linear combination of atomic orbitals, full potential linearised augmented plane-wave and spin polarised relativistic Korringa–Kohn–Rostoker (SPR-KKR) schemes. The band structure calculations show that both the WS 2 and WSe 2 are indirect-gap semiconductors. The SPR-KKR calculations are found to be relatively in poor agreement with the experimental electron momentum densities. The relative nature of bonding in both the dichalcogenides is explained in terms of equal-valence-electron-density profiles, Mulliken's population and valence band charge densities.

Layered double hydroxides (LDHs) are a new class of promising nanomaterials which improve the physicochemical properties of the polymer matrix. The present work deals with the preparation of nanocomposites of ethylene vinyl acetate (EVA-28)/low density polyethylene (LDPE) blend (1:1 by wt.) with varying amounts of organomodified layered double hydroxide (DS-LDH) by solution blending. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) have been used to find out the dispersion of Mg–Al nanolayers in EVA/LDPE blend. This confirms complete exfoliation of Mg–Al nanolayers in EVA-28/LDPE/DS-LDH nanocomposites. The measurements of mechanical properties of these nanocomposites show maximum tensile strength for 3 wt.% of DS-LDH content. However, elongation at break for the nanocomposites remains lower for entire filler loading with respect to neat EVA/LDPE blend. Thermogravimetric analysis shows successive improvement in the thermal stability behavior of the nanocomposites with increasing the concentration of DS-LDH. The limiting oxygen index values are also improved with increasing DS-LDH concentration. Swelling property measurement shows that solvent resistance properties of the nanocomposites are better at low filler loading.

The present work was aimed on utilizing the solid state microwave synthetic method for the growth of molybdenum disulphide (MoS2) and tungsten disulphide (WS2) in powder as well as in the form of thin films. It was observed that the microwave exposure of simple powder mixture of Mo (or W) and S could not lead to the formation of MoS2 (or WS2). Therefore the work was pursued by the study of the possibility to use this technique to grow thin films. Either Mo or W in the form of thin foils or Mo layers deposited by sputtering onto glass substrates was used as metal source. These metal samples were introduced with some sulphur into a Pyrex tube and sealed under vacuum. After microwave oven exposure the formation of polycrystalline 2H-WS2 with well-defined grains was confirmed by X-ray diffraction and scanning electron microscopy, respectively. Mo foil as well as Mo layers deposited on glass showed formation of MoS2 under the limit of our experimental conditions that is to say homogeneous thin films can be achieved only as small surface films.

Partially exfoliated ethylene propylene diene terpolymer (EPDM)/Mg–Al layered double hydroxide (LDH) nanocomposites have been synthesized by solution intercalation using organically modified LDH (DS-LDH) as nanofiller obtained by reconstruction method using sodium dodecyl sulfate and LDH. The nanocomposite structure has been elucidated by the X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The molecular level dispersion of LDH nanolayers has been verified by the disappearance of basal XRD peak of DS-LDH in the composites and studied by TEM and AFM. The mechanical properties showed significant improvement of EPDM/DS-LDH nanocomposites (2–8 wt.%) with respect to neat EPDM. Thermogravimetric analysis (TGA) shows thermal stability of nanocomposites containing 3 wt.% DS-LDH improved by ≈40 °C when 10% weight loss was selected as point of comparison. The first step in the decomposition process induces the charring and can account for better fire safety of the nanocomposites. Optical studies showed better clarity at lower DS-LDH loading in EPDM/LDH nanocomposites.

CuS nanorods of length 60–100 nm and 15 nm in diameter have been synthesized by simple wet chemical method at 105 °C using CuCl 2 ·2H 2 O as Cu-precursor, CS 2 as S-source and ethylenediamine as the attacking reagent. The plausible reaction mechanism has been proposed and the effect of reaction temperature on morphology has been discussed. X-ray diffraction (XRD) pattern suggests the formation of hexagonal phase CuS. The morphology of the products has been studied by transmission electron microscope (TEM) analysis. A detailed optical study has also been done.

A new composite polymer electrolyte (CPE) based on polyethylene oxide (PEO) and LaMnO3 as nano filler has been prepared by solution casting technique. SEM analysis clearly shows that the large spherulites in the crystalline domain of PEO disappear in the plasticized (PEO)–NaClO4–LaMnO3 composites and the surface morphology of SPE on plasticization becomes smoother. XRD and DSC data indicates that the amorphous nature of solid polymer electrolyte (SPE) increases with plasticizer concentration and is maximum for 30 wt% poly ethylene glycol (PEG). Impedance spectra of SPEs have also been made to provide an idea about the grain boundary resistance of the polymer electrolytes. Room temperature ionic conductivity of PEO–NaClO4 increases substantially from 1.05 × 10−6 to 5.30 × 10−6 S cm−1 for PEO–NaClO4–(10 wt%) LaMnO3. It further increases with increasing PEG content in PEO–NaClO4–(10 wt%) LaMnO3 and attains a maximum value of 2.60 × 10−4 S cm−1 for 30 wt% PEG based CPE. Arrhenius plot between log σ versus 1000/T of CPE suggests that temperature dependent conductivity is a thermally activated process.

ZnS thin films have been deposited by chemical bath deposition method using tartaric acid as a complexing agent. The structural and morphological characteristics of films have been investigated by X-ray diffraction (XRD), scanning electron microscope and atomic force microscope analysis. XRD shows development of well-crystallized film with pure-wurtzite structure after annealing. The films show good optical properties with high transmittance in the visible region and the band gap value was estimated to be 3.69 eV. The photoluminescence spectrum of films has also been studied.

Molybdenum disulphide, MoS2, thin films have been deposited by chemical bath deposition method on glass and quartz substrate using ammonium tetrathiomolybdate as a single source precursor for Mo and S and subjected to vacuum heat treatment at different temperatures. X-ray diffraction of as-deposited film indicated its amorphous character and showed the development of poorly crystalline MoS2 thin film on increasing annealing temperature. The film has been characterized by energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, scanning electron micrograph and the optical properties also have been studied.

Cadmium sulphide thin films were deposited by the chemical bath deposition method using tartaric acid as a complexing agent and annealed at different temperature in nitrogen atmosphere and characterized. The crystallographic structure and the crystallite size were studied by the X-ray diffraction (XRD) pattern. Transmittance of the deposited film is significantly higher in the visible region. The optical band-gap of deposited film is 2.4 eV and it decreases with increase in annealing temperature. Temperature dependence of resistivity confirmed the semiconducting behaviour of the film. Scanning electron micrographs (SEM) showed the presence of grain particles of size

Layer type tungsten mixed molybdenum sulphoselenide, Mo 0.5 W 0.5 S x Se 2− x (0≤ x ≤2) starting from ternary Mo 0.5 W 0.5 Se 2 compound and by substituting selenium with sulphur ended with Mo 0.5 W 0.5 S 2 which is also a ternary compound, have been prepared and characterized. X-ray diffraction studies showed that all the compounds possess 2H–MoS 2 structure with a small change in a - and c -parameters. X-ray line profile analysis has been used to calculate the microstructural defect parameters of all these compounds. It showed that sulphur and selenium rich compounds possess relatively small crystallite size ( P ), high r.m.s. strain (〈 e 2 〉) 1/2 and dislocation density ( ρ dis ). However, Mo 0.5 W 0.5 SSe has large P , low (〈 e 2 〉) 1/2 and ( ρ ). Fractional change in interlayer spacing and proportion of the planes affected by defects increased with increasing sulphur contents in Mo 0.5 W 0.5 Se 2 and it was maximum in case of Mo 0.5 W 0.5 S 2 . Radial distribution function (RDF) analysis showed that interatomic distances, 2.80, 3.40 and 3.86 A corresponds to metal–chalcogen, for intra and interlayer chalcogen–chalcogen bonding, respectively. The coupling constants corresponding to these and other higher pair of atoms have also been calculated. Room temperature thermoelectric power experiments temperature variation of conductivity confirmed their p-type semiconducting behaviour. Attempts have also been made to correlate the conductivity of these compounds with their size of the crystallites. The band gaps of these compounds are in the range of 1.20 eV for Mo 0.5 W 0.5 S 2 to 1.07 eV for Mo 0.5 W 0.5 Se 2 , respectively.

Summary The article presents a design of an optical filter using Photonic Band Gap (PBG) materials in the visible and infrared region of the electromagnetic spectrum. This idea is based on the famous Kronig-Penny model in the band theory of solids. The suggested filter may work at any range of the wavelength that can be achieved by choosing the appropriate values of the controlling parameters. This structure is also able to pass the light emitted by the Ruby laser and this acts as a monochromator. Also, we have studied the anomalous behavior of refractive index for the structure having alternate layers of air and GaAs.

Some organophilic montmorillonites (OPMNTs) have been synthesized from Na-montmorillonite (Na-MNT) using ammonium salts of methyl, propyl, butyl, and dodecyl amine. Thermogravimetric (TG), infrared (IR), and X-ray analyses of the compounds were carried out. Microstructural parameters such as crystallite size and root mean square strain (rms) ( 1/2) have been calculated by X-ray line profiles analysis. TG analysis in the temperature range 20–100°C show a weight loss for pure Na-MNT and OPMNTs of about 11% and 2.8%, respectively, indicating the organophilic properties of the OPMNTs. IR and X-ray analyses confirm the formation of OPMNTs by an ion exchange reaction. It is also observed that the crystallite size and rms strain increase with increase carbon number (nc) in the amines.

Selenium substituted indium intercalation compounds of tungsten disulphide, In 1/3 WS 2− x Se x (0≤ x ≤2) have been studied for microstructural characterization using X-ray line profile analysis to find out information about crystallite size, r.m.s. strain, dislocation density, variability of interlayer spacing, fraction of planes affected by such defects, stacking fault probability, crystallite size anisotropy etc. Scanning electron microscopic (SEM) and scanning tunneling microscopic (STM) studies are also reported herewith. These results have also been compared with respect to the pure WS 2− x Se x (0≤ x ≤2).

In this report we give a brief account of the various processes of the formation of thin films. This is followed by a description of the influence of various deposition parameters on the characteristic properties of thin films. The electrical and structural characterization of vapour deposited cadmium sulphide films grown under the influence of electric fields is discussed. This article is a compilation of the previous reported results. Various observations (viz. conductivity measurement, thermoelectric power measurement X-ray observation and crossover voltage measurement) suggest that there is an increase in disorderliness (as a result of freezing in action) due to application of a dc electric field at the time of growth of the film.

The present paper deals with the preparation of tungsten-substituted molybdenum disulfide, Mo 1− x W x S 2 (0≤ x ≤1) compounds and their characterization by various physicochemical methods. X-ray studies confirmed that these compounds crystallized in a layer type of hexagonal structure. X-ray line profile analysis techniques such as the method of variance and Fourier analysis have been used for microstructural characterization of these compounds to find out information about particle size, r.m.s. strain, variability of interlayer spacing, fraction of planes affected by such defects, dislocation density, stacking fault probability and radial distribution function analysis for calculating coupling constants and mean-square displacements, etc. Room-temperature magnetic susceptibility measurements and thermoelectric power experiments and temperature variation of conductivity (25–350°C) confirmed, respectively, diamagnetic n- and p-type semiconducting behaviour for Mo 1− x W x S 2 . Thermal stability behaviour of these compounds in air and inert atmosphere has also been carried out up to 1000°C. These studies indicated that the compounds are nearly stable up to 1000°C in inert atmosphere, whereas, in air, oxidative degradation of these compounds started at 400°C. The nature of the oxidized products has also been studied by X-ray analysis. Scanning electron micrograph studies are also reported here.

The present work deals with preparation and studies on structure determination, layer disorder, microstructural parameter and a few other properties of tantalum substituted W0.65Mo0.35−xTaxSe2, viz. W0.65Mo0.35−xTaxSe2 (0≤x≤0.35). X-ray analysis shows that all these compounds possess MoS2 type structure. The particle size, r.m.s. strain, dislocation density, variability of interlayer spacing and fraction of planes affected by such defects have also been calculated for all compounds. It has been observed that W0.65Mo0.20Ta0.15Se2 compounds possess small size and high values for other parameters. Room temperature magnetic susceptibility, thermoelectric power experiments and two probe electrical conductivity measurements confirmed that all these compounds are diamagnetic p-type metals except the parent compound W0.65Mo0.35Se2, which is a p-type semiconductor. Thermal stability behavior of these compounds in air atmosphere has also been studied and based on weight loss in TG and X-ray data of the oxidized products, formation of the respective oxidized products has been proposed. Scanning electron microscopy studies of these compounds have also been made.

The present paper deals with the preparation of indium intercalated compounds of tungsten sulphoselenide, In1/3WSxSe2−x (0 ≤x≤ 2) and their characterization by various physicochemical methods. The X-ray studies confirmed that all these compounds possess hexagonal symmetry and there exist no anisotropy towards the crystallite size. Room temperature magnetic susceptibility, thermoelectric power experiments and electrical conductivity measurements in the temperature range 25–350°C indicated that In1/3WS2 and In1/3WSxSe2 − x (0 ≤x≤ 2) compounds exhibit p- and n-type diamagnetic semiconducting behaviour respectively and results are explained on the basis of existing band model. Thermal stability of these compounds in air and nitrogen has also been studied and formation of tungsten bronze based on X-ray data of oxidized products has been proposed.

This paper deals with the performance studies of a photovoltaic panel under shadow conditions. The conventional solar array design approach has been modified using a bypass diode across each cell, and the performance of the modified panel has been evaluated experimentally. The observed experimental results have been compared to those obtained theoretically, taking account of the effect of additional series resistance due to the shadowed area. Excellent agreement, both qualitatively and quantitatively, between experiment and theory has been obtained.

A detailed discussion on crystal structure of indium intercalated compounds of molybdenum disulphide, In x MoS 2 (0⩽x⩽1) based on x-ray studies is reported. It shows that intercalated compounds, like the host 2HMoS 2 also possess hexagonal symmetry with a small but continuous increase in c-parameter, unlike their alkali and alkaline earth metals analogs. This has been explained on the basis of the fact that there may be no increase in c-parameter at all in a given intercalation process and that this does not have purely geometric origin but also comes from electronic effects. Results of SEM study are also reported.

A theoretical analysis is presented of an n-channel MAGFET with a non-uniform (displaced Gaussian function) and a uniform impurity profile for the detection of magnetic fields. Consideration of a non-uniform impurity profile in the channel region of a MAGFET is closer to the practical situation. The Hall voltage and sensitivity of the MAGFET for different magnetic fields, source-drain and gate voltages have been evaluated and compared. The results reveal higher sensitivity of the MAGFET in the triode region of operation when calculated using a non-uniform impurity profile compared to a MAGFET with a uniform impurity profile. The present analysis also includes the effect of the location of the Hall contacts on the MAGFET performance. It indicates that the dependence of the sensitivity on the uniformity of the impurity profile and the effective gate voltage is a minimum when the Hall contact lies at a distance of 0.6 L from the source.

Direct current motors are employed in photovoltaic water pumping systems; therefore, the understanding of the system operation and the matching of the system components (arrays and dc motor type) are important factors of the system design. The present study deals with the performance analysis of dc motors (series and shunt motors) powered by a solar cell array (without bypass and with bypass diode) under different shadowing conditions. The result shows that the shunt motor gives good matching to the solar cell array under shadow conditions and it has better shadow tolerance.

© 2011, INASL 1 VIRAL HEPATITIS Seroepidemiology of Hepatitis B Virus in a Tibetan Population in India F Ahmad, V Mittal, V Chauhan, A Wani, S Malhotra, S Srivastava, Y Batra, RK Himthani Department of Gastroenterology, Batra Hospital, New Delh

The present work deals with an investigation on synthesis, structure and properties of indium intercalation compounds of tungsten diselenide ; InxWSe2 (0⩽x⩽1). X-ray analysis shows that these intercalated compounds like the host 2HWSe2 also possess hexagonal symmetry with a small but continuous increase in c-parameter. However, a new phase appeared in In 2 3 WSe 2 and InWSe2 diffractograms due to In2Se3. Room temperature magnetic susceptibility, thermoelectric power experiments and two-probe conductivity measurements in the temperature range 25 −225°C indicated that intercalated compounds also exhibit n-type semiconducting behaviour similar to the host WSe2 and results are explained on the basis of existing band model. Thermal stability behaviour of these compound in atmosphere has also been studied and based on X-ray data of oxidized product formation of tungsten bronzes has been proposed.

The present work reports on the synthesis of indium intercalation compounds In x WS 2 (0 ⩽ x ⩽ 1). The material has been characterized by X-ray studies for structure determination and particle size distribution, room temperature magnetic susceptibility, thermoelectric power experiments and conductivity measurements in the temperature range 150–300 K. These results have indicated that, like the host material WS 2 , the intercalated compounds also possess hexagonal symmetry and are diamagnetic p-type semiconductors. The activation energy for these compounds was determined from the conductivity data.

The present work reports a detailed investigation on crytal structure, electrical properties, and thermal stability for indium intercalation compounds of molybdenum disulphide. In x MoS 2 (0⩽x⩽1). X-ray analyses show that intercalated compounds, like the host material 2HMoS 2 , also possess hexagonal symmetry with a small but continuous increase in interlayer spacing; there also exists a particle size anisotropy. Room temperature thermoelectric power experiments and low temperature (150 – 300 K) conductivity measurements indicate that intercalated compounds also exhibit n-type semiconducting behaviour similar to that of the base material MoS 2 . Thermal stability behaviour of these compounds in air and argon atmosphere has also been studied.

Thin film sandwich structures of the type Al(Al2O3)CdSAl, where the Al2O3 layer is thermally grown at room temperature and the CdS layer has a conductivity of the order of 5 × 10 -9 Ω -1 cm -1 , exhibit bistable switching in the post-breakdown stage. This stage, which consists of two distinct states of high and low conductivity, was studied with the help of conductivity and small signal capacitance measurements. It was found, as a result of these measurements, that the value of ionized donor density in the high conductivity state is about twice that in the low conductivity state, and further, that both the contacts are non-ohmic. In view of these results, the dominant mechanism of conduction in the post-breakdown stage was ascertained to be the one involving field ionization of traps.

Polycrystalline silicon (Wacker) solar cells have been made by diffusion process and subsequently deuterium implantation was done for passivation. It was found that short-circuit current, fill factor and efficiency were improved significantly. Most significant improvement was observed in the dark I–V characteristics. Qualitative explanations for the improvement and of the characteristics of solar cells following deuterium ion implantation are proposed. These interpretations are supported by the preliminary results of studies on the physico-chemical properties of the hydrogen in polycrystalline silicon. It is concluded that the deuterium ion-implantation may be one of the necessary approaches to improve the photovoltaic properties of polycrystalline silicon solar cells.