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The exchange interaction in metal/semiconductor interfaces is far from being completely understood. Therefore, in this paper, we have investigated the nature of silicon on the Fe interface in the ion beam deposited Fe/Si/Fe trilayers keeping the thickness of the Fe layers fixed at 3 nm and varying the thickness of the silicon sandwich layer from 1.5 nm to 4 nm. Grazing incidence x-ray diffraction and atomic force microscopy techniques were used, respectively, to study the structural and morphological changes in the deposited films as a function of layer thickness. The structural studies show silicide formation at the interfaces during deposition and better crystalline structure of Fe layers at a lower spacer layer thickness. The magnetization behavior was investigated using magneto-optical Kerr effect, which clearly shows that coupling between the ferromagnetic layers is highly influenced by the semiconductor spacer layer thickness. A strong antiferromagnetic coupling was observed for a value of tSi = 2.5 nm but above this value an unexpected behavior of hysteresis loop (step like) with two coercivity values is recorded. For spacer layer thickness greater than 2.5 nm, an elemental amorphous Si layer starts to appear in the spacer layer in addition to the silicide layer at the interfaces. It is observed that in the trilayer structure, Fe layers consist of various stacks, viz., Si doped Fe layers, ferromagnetic silicide layer, and nonmagnetic silicide layer at the interfaces. The two phase hysteresis loop is explained on the basis of magnetization reversal of two ferromagnetic layers, independent of each other, with different coercivities. X-ray photo electron spectroscopy technique was also used to study interfaces characteristics as a function of tSi. [ABSTRACT FROM AUTHOR]

Thin films of cobalt (10, 40, and 100 nm) are deposited on Si substrate by electron beam physical vapor deposition technique. After deposition, 4 pieces from each of the wafers of silicon substrate were cut and annealed at a temperature of 200°C, 300°C, and 400°C for 2 hours each, separately. X‐ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) are used to study the structural and morphological characteristics of the deposited films. To obtain TEM images, Co films are deposited on Cu grids; so far, no such types of TEM images of Co films are reported. Structural studies confirm nanocrystalline nature with hexagonal close packed structure of the deposited Co film at lower thickness, while at higher thickness, film structure transforms to amorphous with lower surface roughness value. The particle sizes in all the cases are in the range of 3 to 5 nm. Micro‐Raman spectroscopy is also used to study the phase formation and chemical composition as a function of thickness and temperature. The results confirm that the grown films are of good quality and free from any impurity. Studies show the silicide formation at the interface during deposition. The appearance of new band at 1550 cm−1 as a result of annealing indicates the structural transformation from CoSi to CoSi2, which further enhances at higher annealing temperatures. [ABSTRACT FROM AUTHOR]

In present work ZnO and Zn 0.98 La 0.02 O films were synthesized by sol-gel screen –printing method on glass substrate. The prepared films were investigated by XRD, SEM, EDAX, UV–vis and two probe methods for structural, optical and electrical properties. The X-ray diffraction results showed that the films were polycrystalline with hexagonal wurtzite structure and had preferred growth of grains along the (100) crystallographic direction. SEM images of pure ZnO and doped Zn 0.98 La 0.02 O films indicate the porous and unsymmetrical distribution of grains. The EDAX spectra showed the successful incorporation of La ions with ZnO lattice. The band gap of the films was determined through UV–vis Spectroscopy. It is observed that band gap increases with La doping. The electrical conductivity measurement was carried out via two probe method which reveals the semiconducting behavior of the films. [ABSTRACT FROM AUTHOR]

Catalyst-free ( 00 l) oriented ZnO nanorods (NRs) -based biosensor for the HO sensing has been reported. The (002) oriented ZnO NRs as confirmed by X-ray diffraction were successfully grown on indium tin oxide (ITO) coated glass substrate by radio frequency (RF) sputtering technique without using any catalyst. Horseradish peroxidase (HRP) enzyme was immobilized on ZnO NRs by physical adsorption technique to prepare the biosensor. In this HRP/ZnO NR/ITO bioelectrode, nafion solution was added to form a tight membrane on surface. The prepared bioelectrode has been used for biosensing measurements by electrochemical analyzer. The electrochemical studies reveal that the prepared HRP/ZnO NR/ITO biosensor is highly sensitive to the detection of HO over a linear range of 0.250-10 μM. The ZnO NR-based biosensor showed lower value of detection limit (0.125 μM) and higher sensitivity (13.40 µA/µM cm) towards HO. The observed value of higher sensitivity attributed to larger surface area of ZnO nanostructure for effective loading of HRP besides its high electron communication capability. In addition, the biosensor also shows lower value of enzyme's kinetic parameter (Michaelis-Menten constant, K ) of 0.262 μM which indicates enhanced enzyme affinity of HRP to HO. The reported biosensor may be useful for various applications in biosensing, clinical, food, and beverage industry. [ABSTRACT FROM AUTHOR]

The catalytic reduction of methylene blue was studied using biosynthesised gold–silver (Au–Ag) alloy nanoparticles (NPs). The fungal biomass of Trichoderma harzianum was used as a reducing and stabilising agent in the synthesis of Au–Ag alloy NPs. The synthesised NPs were well characterised by UV–vis spectroscopy, dynamic light scattering, X‐ray diffraction, transmission electron microscopy, energy dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy. The plausible synthesis mechanism involved in the formation of Au–Ag alloy NPs was also discussed with diagrammatic representation. A series of experiments was performed to investigate the catalytic activity of the as‐prepared Au–Ag alloy NPs and found that the alloy NPs show excellent catalytic activity. [ABSTRACT FROM AUTHOR]

The X-ray diffraction analysis of Li1+δMn2-δO4 having δ = 0.00, 0.03, 0.06, 0.12, 0.18, 0.24, 0.33, 0.42, and 0.50 powders, synthesized by a sol-gel process, shows that a single-phase cubic spinel structure is stable only when δ ⩽ 0.24. When lithium content increases to ⩽ > 0.24, the percentage of monoclinic Li2MnO3 increases until δ = 0.42 and saturates thereafter. On magnesium doping, the range of stability of cubic spinel Li1+δMn2-δ-0.1Mg0.1O4 decreases to δ ⩽ 0.18, and monoclinic Li2MnO3 starts to appear when 6 > 0.18. In magnesium-doped Li1-δMn1.9-δ-0.1Mg0.1O4, the ion Mg2+ goes to octahedral sites and decreases the population of Mn3+ in the 16d octahedral sites, and so the lattice parameter of the magnesium-doped cubic spinel for the same δ is lower than that for undoped Li1-δMn2-δO4. However, at higher δ, the population of Mn3+ may get totally exhausted and the charge balance may be maintained by the creation of defects. The voltage step appearing in the discharge curve has been attributed to a transition from two cubic phases to one cubic phase. With increasing δ, the size of the step decreases and becomes broader. However, this voltage step does not appear to be affected by magnesium doping. [ABSTRACT FROM AUTHOR]

Abstract: Spinel powders of Li1.03Mn1.97O4, Li1.03[Mg x Mn1.97− x ]O4, Li1.03[Fe y Mn1.97− y ]O4 and Li1.03[Mg x Fe y Mn1.97− x − y ]O4 systems were synthesized by sol–gel technique using lithium acetate, manganese acetate, magnesium acetate, iron nitrate and citric acid as the starting materials. The effect of Mg and Fe substitutions on the structure and surface morphology of spinel Li1.03Mn1.97O4 has been examined by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and Infrared spectroscopy (IR). Electrochemical characteristics such as the cyclic performance was also investigated. The materials for all the compositions exhibit a phase pure cubic spinel structure as evident from the XRD analyses. The crystallinity and average particle size of the material increases by doping with Fe and Mg. The particles of doped samples have truncated octahedral shape. The discharge capacity of Li1.03Mn1.97O4 is 126mAh/g. The doping increases cyclability; however, the discharge capacity reduces. [Copyright &y& Elsevier]

The present study demonstrates a simple, cost effective and selective method for colorimetric detection of mercury(II) ions using gold nanoparticles (AuNPs) synthesized by non-pathogenic and agriculturally considerable fungal biomass of Trichoderma harzianum ( T. harzianum ). The synthesized nanoparticles were characterized by UV–vis spectroscopy (UV–vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The as-synthesized AuNPs were used further for the selective optical detection of Hg 2+ ions. The color of AuNPs solution changes in the presence of Hg 2+ ions and also a substantial change in the surface plasmon resonance (SPR) of nanoparticles was observed even at minute concentration of Hg 2+ ions. The sensitivity and selectivity of AuNPs towards Hg 2+ ions was also analyzed in the presence of Pb 2+ , Zn 2+ , Cd 2+ , Fe 3+ , Ni 2+ , Ca 2+ , Mn 2+ , Al 3+ , Co 2+ and Na + ions. The mechanism of colorimetric detection of Hg 2+ ions was also discussed along with diagrammatic representation. [ABSTRACT FROM AUTHOR]