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Applied Nanoscience (v.3, #2)

Optical properties of gallium phosphide (GaP) nanowires by Satyendra Singh; Pankaj Srivastava (pp. 89-94).

The linear and non-linear optical properties of different geometrical structures of gallium phosphide (GaP) nanowires have been studied by employing ab initio method. We have calculated the optical response of four different GaP nanowires, viz., two atom linear wire, two atom zigzag wire, four atom square wire and six atom hexagonal wire. We have investigated imaginary part of the zz component of the linear dielectric tensor and second order susceptibility for different structures along with bulk material. We revealed that strongest absorption occurs for four atom square nanowire configuration.

Keywords: Gallium phosphide nanowires; Linear and non-linear optical properties

The effects of nanosilver on egg quality traits in laying Japanese quail by Amjad Farzinpour; Naser Karashi (pp. 95-99).

Silver nanoparticles could prove to be a valuable alternative raw material for antibiotics and disinfectants as it is relatively free of adverse effects. Nanosilver is now been put to practical use in commonly used items, such as, clothes, electric home appliances, and electronic industry, but has not been widely applied in the medical or pharmacological fields. This study was designed to investigate the effects of nanosilver on egg quality traits in laying Japanese quail in completely randomized design with four treatments and six repetitions at 0, 4, 8 and 12 ppm of silver nanoparticle levels. Eggs collected daily and egg parameters, including egg weight, length, width; yolk weight and eggshell thickness were examined. The effect of the different silver nanoparticle levels was determined using the General Linear Model of SAS procedure, whilst differences between the groups were determined using least significant difference test. Results indicated that silver nanoparticles at all levels caused significantly reduce of yolk weight and hen-day egg production for each week than the control treatment (P < 0.05), whilst silver nanoparticle had no significant effect on egg weight, egg length and width and eggshell thickness.

Keywords: Nanosilver; Quail; Egg quality; Hen-day egg production

Large-scale synthesis of Au–Ni alloy nanowires using electrochemical deposition by Sanjeev Kumar; Deepak Saini (pp. 101-107).

The template-assisted electrodeposition technique has been utilized to synthesize highly ordered, well-aligned, and dense Au–Ni alloy nanowires. The electrochemical impedance spectroscopy has been carried out to study the in situ growth process of alloy nanowires at different electrodeposition times. Their morphological studies have been carried out using the high-resolution transmission electron microscopy. Elemental composition of template-synthesized nanowires has been studied by energy dispersive X-ray analysis. The X-ray diffraction study revealed the face centered cubic structure of the nanowires. Magnetic properties of the nanowires have been studied using Quantum Design vibrating sample magnetometer.

Keywords: Electrodeposition; Nanowires; Electrochemical impedance; Magnetism

Analysis of temperature and wave function penetration effects in nanoscale double-gate MOSFETs by E. Farzana; S. Chowdhury; R. Ahmed; M. Ziaur Rahman Khan (pp. 109-117).

Wave function penetration has significant impact on nanoscale devices having ultrathin gate oxide. Although wave function penetration effects on ballistic drain current and capacitance-voltage characteristics in nanoscale devices have been reported in literature, to the best of the authors’ knowledge, effects of temperature on drain current incorporating with and without wave function penetration are yet to be studied. In this work, the impacts of temperature, gate dielectric and film thickness in wave function penetration on ballistic drain current of nanoscale double-gate (DG) MOSFETs are presented. The effects are observed using two-dimensional self-consistent solution of Schrödinger and Poisson equations. It has been obtained that temperature effect on drain current is greatly dependent on silicon surface orientation. Drain current of DG MOSFETs fabricated on $$langle110 angle$$ surface is more sensitive to temperature compared to $$langle001 angle$$ surface. This has been obtained for both the cases with and without incorporating wave function penetration in silicon–gate oxide interface. Electrostatics behind this phenomenon has been explained from the transmission probability of electrons from source to drain which is largely influenced by temperature on $$langle110 angle$$ surface compared to $$langle001 angle.$$ Moreover, the transmission coefficient is significantly affected by wave function penetration in $$langle110 angle hbox{ than }langle001 angle$$ surface. Both these demonstrate greater sensitivity of temperature and wave function penetration in $$langle110 angle$$ silicon surface orientation compared to $$langle001 angle.$$ Furthermore, gate dielectric with lower conduction band offset and device scaling with thin channel thickness tend to exhibit greater impact of wave function penetration.

Keywords: Wave function penetration; Surface orientation; Ballistic drain current; Transmission coefficient

A simple microwave assists aqueous route to synthesis CuS nanoparticles and further aggregation to spherical shape by Muhammad Nafees; Salamat Ali; Saima Idrees; Khalid Rashid; Muhammad Ahsan Shafique (pp. 119-124).

The aggregation of CuS nanoparticles during synthesis by a hassle-free aqueous route under microwave irradiation gave remarkable spherical shape, utilizing Cu(CH₃COO)₂·H₂O as the source of copper and Na₂S₂O₃·5H₂O, as sulfur source; these materials were used without assistance of any surfactant or template. An X-ray powder diffraction pattern proved that the product is hexagonal CuS phase. The morphologies of the product were observed by scanning electron microscopy. Thermal behavior, different solid state, and chemical conversion in CuS with respect to temperature were studied by DSC/TGA, which confirmed the thermal oxidation of CuS and its conversion into CuO then to Cu₂O.

Keywords: Microwave; Nanoparticles; Copper sulfide; Aggregation; Thermal oxidation; Spherical shape

Synthesis and characterization of flower-like ZnSe nanostructured thin films by chemical bath deposition (CBD) method by G. Bakiyaraj; R. Dhanasekaran (pp. 125-131).

Flower-like zinc selenide nanostructured thin films were successfully prepared by a chemical bath deposition method on non-conducting glass substrate in an aqueous alkaline medium using sodium selenosulphate as Se²⁻ ion source. The as-deposited films have been characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (HRSEM), energy-dispersive X-ray analysis (EDX), optical absorption, and photoluminescence spectroscopy (PL). The XRD studies reveal that the as-deposited ZnSe thin film is nanocrystalline with a face-centered cubic phase. SEM image shows the tens to hundreds of petals are self-assembled within a single nanoflower. The direct optical band gap ‘E _g’ for as-deposited flower-like ZnSe thin films is found to be 2.80 eV. Room temperature PL measurement indicates that the as-deposited cubic ZnSe thin films have a near band edge (NBE) emission peaked at around 440 nm (2.81 eV) and broad weak band emission peak from 552 nm (2.24 eV) to 658 nm (1.88 eV). The strong NBE emission from the flower-like ZnSe nanostructured thin films reveals their potential as building for optoelectronic devices.

Keywords: Semiconductor thin films; Nanostructured materials; Chemical bath deposition; Structural properties; Optical properties

Structure, optical properties and synthesis of Co-doped ZnO superstructures by Talaat M. Hammad; Jamil K. Salem; R. G. Harrison (pp. 133-139).

Co-doped ZnO nanoparticles were synthesized by a simple chemical method at low temperature with Co:Zn atomic ratio from 0 to 7 %. The synthesis process is based on the hydrolysis of zinc acetate dihydrate and cobalt acetate tetrahydrate heated under reflux to 65 °C using methanol as a solvent. X-ray diffraction analysis reveals that the Co-doped ZnO crystallizes in a wurtzite structure with crystal size of 12–5 nm. These nanocrystals self-aggregated themselves in a highly spherical superstructure of broad size distribution. High-resolution transmission electron microscopy image also shows that each sphere is made up of numerous nanocrystals with average interfringe distance of ~0.28 nm. The X-ray diffraction patterns, energy dispersive X-ray, scanning electron microscopy and high-resolution transmission electron microscopy micrographs of doping of Co in ZnO confirmed the formation of spherical superstructure and indicated that the Co²⁺ is successfully substituted into the ZnO host structure of the Zn²⁺ site. The optical band gap of ZnO nanoparticles was remarkably from 3.32 to 4.12 eV with increase of Co doping levels from 0 to 7 %. Photoluminescence measurements confirm these results.

Keywords: Synthesis; Structural; Optical; Co-doped ZnO

Synthesis and conjugation of ZnO nanoparticles with bovine serum albumin for biological applications by Pawan Kumar; Parveen Kumar; Akash Deep; Lalit M. Bharadwaj (pp. 141-144).

Semiconductor nanomaterials tagged with biomarkers may be used for an early fluorescence-based detection of breast cancer. ZnO nanoparticles are water-soluble, non-toxic, photo-chemically stable with highly fluorescence applicability and are regarded for their possible biocompatibility. As a long-term research planning, we are aiming to use QDs conjugated with serum-biomarker for the diagnosis of breast cancer. The present work is a part in the said direction and reports preliminary observations on the synthesis and conjugation of ZnO nanoparticles with a representative protein marker.

Keywords: ZnO nanomaterials; Quantum dots; Breast cancer; Biomarkers

Facile green synthesis of variable metallic gold nanoparticle using Padina gymnospora, a brown marine macroalga by M. Singh; R. Kalaivani; S. Manikandan; N. Sangeetha; A. K. Kumaraguru (pp. 145-151).

The process of development of reliable and eco-friendly metallic nanoparticles is an important step in the field of nanotechnology. To achieve this, use of natural sources like biological systems becomes essential. In the present work, extracellular biosynthesis of gold nanoparticles using Padina gymnospora has been attempted and achieved rapid formation of gold nanoparticles in a short duration. The UV–vis spectrum of the aqueous medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. Scanning electron microscopy showed the formation of well-dispersed gold nanoparticles. FTIR spectra of brown alga confirmed that hydroxyl groups present in the algal polysaccharides were involved in the gold bioreduction. AFM analysis showed the results of particle sizes (53–67 nm) and average height of the particle roughness (60.0 nm). X-ray diffraction (XRD) spectrum of the gold nanoparticles exhibited Bragg reflections corresponding to gold nanoparticles. This environment-friendly method of biological gold nanoparticle synthesis can be applied potentially in various products that directly come in contact with the human body, such as cosmetics, and foods and consumer goods, besides medical applications.

Keywords: Chloroauric acid; Padina gymnospora ; Marine macroalgae; Extracellular synthesis; Biological synthesis

Optical and magnetic properties of Zn_0.98Mn_0.02O nanoparticles by Talaat M. Hammad; S. Griesing; M. Wotocek; S. Kuhn; R. Hempelmann; U. Hartmann; Jamil K. Salem (pp. 153-159).

Pure and Mn-doped colloidal ZnO particles were prepared in a solvo-thermal via sol–gel process by base-catalyzed hydrolysis of zinc acetate. We have studied the structural, magnetic and optical properties of the samples using X-ray diffraction (XRD), transmission electron microscopy, energy dispersive X-ray analysis, superconducting quantum interferometer device and UV–Vis spectroscopy. The XRD spectra show that all the samples are hexagonal wurtzite structures. The calculated average particle size of the samples was approximately 7–3 nm, indicating that the particle size decreased by doping with manganese. Magnetic investigations showed that at room temperature the Mn-doped ZnO possessed ferromagnetism with the saturation magnetic moment of 0.194 emu/g. The room temperature PL measurements illustrate UV-emission centered at 351 nm (3.53 eV), which is ascribed to the near-band-edge emissions of ZnO, violet emission at 512 nm (2.42 eV). The UV–Vis spectra showed a blue-shift from 3.42 to 3.78 eV when the ZnO doped with manganese.

Keywords: Structural; Optical; Magnetic; Mn-doped ZnO; Nanoparticles

Organic free synthesis of flower-like hierarchical CuO microspheres by reflux condensation approach by K. Mageshwari; R. Sathyamoorthy (pp. 161-166).

In the present work, CuO nanostructures with different morphologies were synthesized by a simple one-pot reflux condensation approach using different alkaline precursors. Structural analysis by X-ray diffraction and Fourier transform infrared spectroscopy revealed the formation of single phase CuO with a monoclinic crystal structure. Morphological analysis by scanning electron microscopy showed the formation of spindle-shaped and flower-like CuO architecture when NaOH and NH₄OH were used as alkaline precursors, respectively. The flower-like CuO architecture is found to be made up of 2D nanosheets as building blocks, which were self-assembled to form spherical assemblies. Optical analysis by UV–VIS diffused reflectance spectroscopy showed blue-shift in the optical band gap due to quantum confinement effect. Photoluminescence spectra showed both UV and visible emission. The plausible growth mechanism for the formation of different CuO nanostructures was proposed.

Keywords: CuO; Nanostructures; Hierarchical assemblies; X-ray diffraction; Quantum confinement

Enhancement of TiO₂ nanoparticle properties and efficiency of dye-sensitized solar cells using modifiers by M. M. Rashad; A. E. Shalan; Mónica Lira-Cantú; M. S. A. Abdel-Mottaleb (pp. 167-174).

A low-temperature hydrothermal process developed to synthesizes titania nanoparticles with controlled size. We investigate the effects of modifier substances, urea, on surface chemistry of titania (TiO₂) nanopowder and its applications in dye-sensitized solar cells (DSSCs). Treating the nanoparticles with a modifier solution changes its morphology, which allows the TiO₂ nanoparticles to exhibit properties that differ from untreated TiO₂ nanoparticles. The obtained TiO₂ nanoparticle electrodes characterized by XRD, SEM, TEM/HRTEM, UV–VIS Spectroscopy and FTIR. Experimental results indicate that the effect of bulk traps and the surface states within the TiO₂ nanoparticle films using modifiers enhances the efficiency in DSSCs. Under 100-mW cm⁻² simulated sunlight, the titania nanoparticles DSSC showed solar energy conversion efficiency = 4.6 %, with V _oc = 0.74 V, J _sc = 9.7324 mA cm⁻², and fill factor = 71.35.

Keywords: Dye-sensitized solar cells; Titania nanoparticles; Modifiers; Electron transport; Photovoltaic performance

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Applied Nanoscience (v.3, #2)

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Applied Nanoscience (v.3, #2)