Influence of silver and graphite on zinc oxide nanostructures for optical application

Silver and graphite doped zinc oxide (ZnO) nanostructures were fabricated by facile and efficient direct sublimation process by employing thermal evaporation. Silver and graphite were incorporated to modify ZnO tetrapod structures for optical applications. Scanning and transmission electron microscopy techniques were used to investigate micro and nanostructures variation with doping in bare ZnO. Electrical measurements have been performed to study the conducting nature of these fascinating nanoobjects. Silver in ZnO results into flower shape multipod structure and graphite doping in ZnO results into tetrapods constituted with multiple rods like structure. Photoluminescence measurements revealed the alteration in emission towards near band edge peak with different excitation wavelength. Similar changes have been noted in UV graph by influencing the absorbance properties of the bare-ZnO with doping of silver and graphite

Silver (Ag) incorporated Cu2ZnSnS4 thin film for improved optical and morphological properties

Replacing copper (Cu) with silver (Ag) which is always in monovalent state can improve the stability and quality of Cu2ZnSnS4 (CZTS). In this work, few copper (Cu) atoms have been substituted by Ag into the crystal lattice of CZTS by Ag deposition using DC (direct current) magnetron sputtering before stacked layer reactively sputtered individual Sn-Cu-Zn targets at room temperature and post annealed at 550 degrees C for 5 min only. Substitution of Cu with Ag reduces antisite defects, secondary phases and also improves the optical absorbance and grain size of the (Ag,Cu)(2)ZnSnS4 (ACZTS) thin film. Rice-like structured ACZTS film showed optical absorption coefficient one order of magnitude higher than CZTS thin film. The band gap was slightly smaller 1.4 eV for ACZTS as compared to 1.5 eV for CZTS film. To the best of our acquaintance, this is the first study on synthesis of rice-like structured ACZTS film and investigation of optical and morphological properties. Also the method used for sample preparation (sputtering) with short annealing time can be an industrially viable technique

Synthesis of N and F co-doped TiO2 nanophotocatalysts for degradation of malathion in water

N and F codoped nanophotocatalysts were synthesized by sol-gel method and their photocatalytic activity were studied for the degradation of insecticide malathion. Photocatalysts were characterised by X-ray diffraction (XRD), scanning electron microscope, transmission electron microscope and micro Raman spectroscopy to determine the structural, morphological properties and phase composition. The particle size calculated by XRD are in agreement with the measured value by TEM. Band gap calculated by absorption spectra shows a shift in the absorption edge towards longer wavelength side. Photoluminescence spectra show emission behaviour of synthesized photocatalysts. In comparison with undoped TiO2, N, F codoped particles exhibits higher photocatalytic activity due to generation of more reactive oxidative species (ROS). Mechanism of ROS generation is graphically discussed

Silver (Ag) incorporated Cu2ZnSnS4 thin film for improved optical and morphological properties

Replacing copper (Cu) with silver (Ag) which is always in monovalent state can improve the stability and quality of Cu2ZnSnS4 (CZTS). In this work, few copper (Cu) atoms have been substituted by Ag into the crystal lattice of CZTS by Ag deposition using DC (direct current) magnetron sputtering before stacked layer reactively sputtered individual Sn-Cu-Zn targets at room temperature and post annealed at 550 degrees C for 5 min only. Substitution of Cu with Ag reduces antisite defects, secondary phases and also improves the optical absorbance and grain size of the (Ag,Cu)(2)ZnSnS4 (ACZTS) thin film. Rice-like structured ACZTS film showed optical absorption coefficient one order of magnitude higher than CZTS thin film. The band gap was slightly smaller 1.4 eV for ACZTS as compared to 1.5 eV for CZTS film. To the best of our acquaintance, this is the first study on synthesis of rice-like structured ACZTS film and investigation of optical and morphological properties. Also the method used for sample preparation (sputtering) with short annealing time can be an industrially viable technique

Microstructural evolution and photoluminescence performanance of nickel and chromium doped ZnO nanostructures

Columnar growth morphology of ZnO nanostructures were synthesized by employing simple thermal evaporation of zinc precursor electroplated with nickel and chromium. The X-ray powder diffraction studies carried out for determining crystallographic phases of varied ZnO morphologies. The elemental analysis has been carried out to confirm the presence of Ni and Cr doping. The electron microscopy techniques, SEM and HRTEM, were used to investigate the influence of doping on microstructural properties. The columnar growth of ZnO structures observed in undoped ZnO, whereas, Ni doped ZnO reveals the spherical nanoparticles decorated on columnar growth of ZnO nanostructures and Cr doping leads to rod like structures with spherical and cubical nanoscale objects. HRTEM micrograph reveals the growth along different planes of ZnO crystal structure. Photoluminescence (PL) measurements reveal the alteration in defect related emission with doping. Time resolved PL elucidates the decay time parameters and its dependence on microstructural modification in ZnO

High permeability and low power loss of Ti and Zn substitution lithium ferrite in high frequency range

The effect of Zn and Ti on the magnetic, power loss and structural properties of Li0.5ZnxTixMn0.05Fe2.45−2xO4 ferrites (x=0.0 to 0.30 in step of 0.05)+0.5 wt% Bi2O3, prepared by standard ceramic technique, has been investigated. Complex permeability (μ*=μ′−jμ″) has been analyzed at room temperature in frequency range from 1 to 103 MHz. It was found an enhancement in permeability with Ti and Zn concentration in Li0.5ZnxTixMn0.05Fe2.45−2xO4 and exhibits the maximum value 106 for x=0.20 sample. Complex permeability of these ferrites exhibits stable frequency response up to 7 MHz beyond which the real part decreases sharply and imaginary part increases to have a peak at the relaxation frequency. Power loss measurements have been carried out in induction condition (B=10 mT) in frequency range of 50 kHz to 3 MHz. Power loss has been found to be quite low with the substitution of Ti and Zn in lithium ferrite

Epidermal Inspired Flexible Sensor with Buckypaper/PDMS Interfaces for Multimodal and Human Motion Monitoring Applications

The advancements in the areas of wearable devices and flexible electronic skin have led to the synthesis of scalable, ultrasensitive sensors to detect and differentiate multimodal stimuli and dynamic human movements. Herein, we reveal a novel architecture of an epidermal sensor fabricated by sandwiching the buckypaper between the layers of poly(dimethylsiloxane) (PDMS). This mechanically robust sensor can be conformally adhered on skin and has the perception capability to detect real-time transient human motions and the multimodal mechanical stimuli of stretching, bending, tapping, and twisting. The sensor has feasibility for real-time health monitoring as it can distinguish a wide range of human physiological activities like breathing, gulping, phonation, pulse monitoring, and finger and wrist bending. This multimodal wearable epidermal sensor possesses an ultrahigh gauge factor (GF) of 9178 with a large stretchability of 56%, significant durability for 5000 stretching–releasing cycles, and a fast response/recovery time of 59/88 ms. We anticipate that this novel, simple, and scalable design of a sensor with outstanding features will pave a new way to consummate the requirements of wearable electronics, flexible touch sensors, and electronic skin

Synthesis and characterization of ZnO tetrapods for optical and antibacterial applications

ZnO tetrapods have been grown by sublimation process employing thermal evaporation at 950 °C on quartz substrate. The grown ZnO tetrapods exhibited noteworthy microstructure, phase formation, emission bands and antibacterial performance. A detailed micro- and nano- analysis supported with analytical measurements elucidated the faceted tetrapod growth with hexagonal wurzite crystal structure of ZnO. Each arm of the tetrapod revealed a facetted hexagonal cross-section with uniform length and diameter. The photolumiscence spectra showed engrossing optical properties with pre-dominant green emission completely overwhelming the near band edge (NBE) UV peak. These fascinating tetrapod objects responded well for antibacterial activity against Escherichia coli and Staphylococcus aureus

An approach to produce single and double layer graphene from re-exfoliation of expanded graphite

We report the production of high quality single and double layer graphene from sonication and centrifugation of re-exfoliated expanded graphite (EG) in an organic solvent. The prepared graphene-sheets are identified by Ultraviolet-visible spectroscopy and characterized using different techniques. Transmission and scanning electron microscopy observations show that the graphene-sheets have an area of similar to(12 x 10) mu m(2). The selected area electron diffraction analysis and Raman spectroscopy have confirmed the presence of single layer graphene-sheet. The I(2D)/I(G) ratio from the Raman spectrum of graphene is found to be similar to 1.7 which suggests the presence of single and double layer graphene. Scanning probe microscopy studies reveals that on re-exfoliation of EG, thickness of graphene layer decreases from 6-7 nm to 0.75-1.075 nm. This suggests that re-exfoliation overcomes the problem of insufficient oxidation or inadequate pressure that builds-up during first thermal exfoliation of graphite intercalated compound. The photoluminescence spectrum of graphene shows the emission of blue light at similar to 390 nm which indicates the presence of some functional groups. These graphene-sheets should facilitate the manipulation and processing of graphene based material for various applications

Revelation of temperature-dependent cathodoluminescence by employing nanostructural pathway in fe-incorporated ZnO

[No abstract available