Small Area Electron Diffraction Research Articles

Effect of cerium concentration on photoluminescence behavior of Y6Ba4(SiO4)6F2 phosphors

Conventional solid state reaction method was used for the synthesis of Y6Ba4(SiO4)6F2 apatite compounds doped with different mol% concentration of cerium. The structural analysis and various parameters of the prepared phosphors are determined by x-ray diffraction pattern. Scanning electron microscope (SEM), Transmission electron microscope (TEM) and small area electron diffraction pattern (SAED) were used to view the morphology of the surface for the prepared phosphors. The photoluminescence emission and excitation spectra for prepared phosphors were obtained. Due to the host environment crystal field spiltting and centroid shift occurred which resulted in red shift of emission peaks. From Commission Internationale de I′Eclairage(CIE) chromaticity coordinate, emission color from the prepared phosphors were observed in blue region.

Analysis of electrical response, gas evolution and coating morphology during transition to soft sparking PEO of Al

The soft sparking regime of Plasma Electrolytic Oxidation (PEO) of valve metals attracts increasing attention as it enables a better process control with improved energy efficiency and coatings with enhanced performance to be obtained. Here, the discharges softening phenomenon was characterised by evaluation of changes in electrical signal, composition of gaseous products and morphology of the metal-oxide interface in PEO coatings on Al. The coatings were formed using two electrical regimes retarding or promoting soft sparking conditions. Harmonic analysis of PEO process has been performed using independent evaluation of the positive and negative half-waves of polarisation signal. The composition of gas evolved during the PEO process was evaluated by a quantitative gas analyser. Coatings were characterised by scanning and transmission electron microscopy with energy dispersive spectroscopy and small area electron diffraction. It was found that discharge softening is accompanied with a decrease in oxygen evolution rate, an increase in equivalent capacitance of anodic process as well as structural and compositional changes near the metal-oxide interface. The experimental findings provide further support to the explanation of discharge softening phenomenon by narrowing the active zone at the metal-oxide interface due to intercalation of hydrogen species into anodic alumina under cathodic polarisation. Such mechanistic understanding allows rational regime selection, in-situ process control and optimisation of the coating properties to be performed that paves the way to intellectual manufacturing approach based on careful process monitoring in operando.

Simple synthesis of biogenic Pd[sbnd]Ag bimetallic nanostructures for an ultra-sensitive electrochemical sensor for sensitive determination of uric acid

Bimetallic nanomaterials have potential catalytic behaviour in hydrogenation, clean- energy production, catalysis and sensors due to their great stability, loftier activity unique electrical and chemical properties. Herein, we prepared PdAg bimetallic nanoparticles synthesized by using fungal extracted aqueous method, which is environmentally friendly cost-effective and simple procedure. The fabricated PdAg bimetallic nanoparticles were investigated by small area electron diffraction (SAED), transmission electron microscopy (TEM) X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) analysis. The electrochemical response of uric acid (UA) at Pd-Ag/CPE was studied in 0.1 M phosphate buffer solution at various pH, concentration and scan rate was investigated. Compare to Bare CPE, the PdAg nanocomposite modified electrode displayed the highest electrocatalytic activity for the detection of UA A linear response in the range of 4.69–273 nM with remarkable detection limit of 5.543 nM (CDL = 3ϭ/M) and quantification limit of 16.64 nM (CQL = 10ϭ/M) was obtained. The established nanoparticles (PdAg) embedded with carbon paste electrode (Pd-Ag/CPE) makes a good analytical tool for the sensing of UA in the biological and pharmaceutical samples.

Plectranthus amboinicus-mediated silver, gold, and silver-gold nanoparticles: phyto-synthetic, catalytic, and antibacterial studies

Bio-based green nanotechnology aims to characterize compounds from natural sources and establish efficient routes for the preparation of nontoxic materials that have applicability in biodegradable and biocompatible devices. The present study has investigated the use of Plectranthus amboinicus leaf extracts as reducing and capping materials for the green fabrication of silver, gold, and silver-gold (Ag, Au, and Ag/Au) metal and bimetallic nanoparticles. The catalytic behavior of these phyto-inspired nanoparticles was then assessed in terms of the reduction of 4-nitrophenol. Transmission electron microscopy was used to investigate the shape, morphology, distribution, and diameter of the phytomolecules capped with Ag, Au, and Ag/Au metal nanoparticles. The nature of the crystallinity of the nanoparticles was studied by small area electron diffraction (SAED) and x-ray diffraction analysis (XRD), and Fourier transform infrared (FTIR) spectroscopy was used to study the reduction and stabilizing involvement of the phyto-organic moieties in aqueous medium. The phyto-inspired Ag and Ag/Au nanoparticles demonstrated good antibacterial properties toward Gram-negative Escherichia coli and Pseudomonas spp. and Gram-positive Bacillus spp. and Staphylococcus spp. microorganisms using the well diffusion method. Notably, the Ag nanoparticles were shown to possess effective antibacterial properties.

ZnSe-WO3 nano-hetero-assembly stacked on Gum ghatti for photo-degradative removal of Bisphenol A: Symbiose of adsorption and photocatalysis

In this research work we report Gum-ghatti supported ZnSe-WO3 nano-hetero-assembly for solar powered degradation of endocrine disruptor Bisphenol S (BPA). The photocatalyst was characterized by Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HRTEM), Small area electron diffraction (SAED), X-Ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), Photoluminescence (PL), Energy dispersive X-ray (EDX), UV–vis spectrophotometry and Brauner Emmet Teller surface area analyzer (BET). We achieve a Z-scheme photocatalyst (ZnSe-WO3) with a higher charge flow and visible absorption. Gum ghatti acts as a superadsorbent and a sink for charge carriers. The removal of BPA has been studied under three experimental protocols where 99.5% removal was achieved by symbiose of photocatalysis-adsorption-ozonation in just 45min hetero-assembly has a high surface area, stability and reduced carrier recombination. The results have been analyzed by scavenger effect, mass spectrometry, kinetics and total organic carbon (TOC) analysis. 49.4% of TOC was removed and COD was reduced to 16.7% after 2h in symbiotic condition. From the band edges and scavenger effect it was inferred that superoxide radical anions are major attacking species. The work paves way for designing of novel photocatalysts with increasing biogenic quotient and higher efficiency.

Green synthesis of palladium nanoparticles using fenugreek tea and their catalytic applications in organic reactions

In this communication, we present the fenugreek tea aided green synthesis of Pd nanoparticles (PdNPs@FT). The synthesized PdNPs were characterized by UV–Visible spectroscopy, scanning electron microscopy (SEM), small area electron diffraction (SAED), fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). FT-IR manifested that polyol and amide groups present in fenugreek may have participated in the synthesis of palladium nanoparticles. PdNPs@FT exhibited high catalytic activity towards hydrogenation of 4-nitrophenol to 4-aminophenol. PdNPs@FT catalyzed Suzuki–Miyaura coupling reaction between bromobenzene and phenyl boronic acid gave desired biphenyl in excellent yield.

New frontiers in water purification: highly stable amphopolycarboxyglycinate-stabilized Ag–AgCl nanocomposite and its newly discovered potential

A simple synthetic procedure for high-stable dispersions of porous composite Ag/AgCl nanoparticles stabilized with amphoteric surfactant sodium tallow amphopolycarboxyglycinate has been proposed for the first time. The prepared samples were characterized by UV–vis spectroscopy, x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy, small area electron diffraction (SAED), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and electron probe micro-analysis. In addition, measurements (carried out at the Kurchatov synchrotron radiation source stations) of the Ag K-edge extended x-ray absorption fine structure (EXAFS) and x-ray absorption near edge structure (XANES) spectra and XRD of the prepared nanoparticles have been performed. The obtained results suggest that small-sized Ag clusters are homogeneously distributed in the mass of the AgCl nanoparticle (~80 nm) formed during the synthesis. The Ag/AgCl dispersion demonstrates photocatalytic activity (with respect to methyl orange) and high bactericidal activity against E. coli. This activity is superior to the activity of both Ag and AgCl nanoparticles stabilized by the same surfactant. Thus, porous composite Ag/AgCl nanoparticles can be used as a multifunctional agent that is able to remove both pollutants and bacterium from water.

Coating of Vertically Aligned Carbon Nanotubes by a Novel Manganese Oxide Atomic Layer Deposition Process for Binder‐Free Hybrid Capacitors

A novel atomic layer deposition process of manganese oxide from methylcyclopentadienyl manganese tricarbonyl and ozone has been developed. It is used to coat vertically aligned carbon nanotubes (VACNTs) grown on a conductive Inconel substrate in order to produce a 3D array of metal oxide‐carbon nanotube electrode. Electron microscopy studies show that a conformal polycrystalline film can be deposited on the VACNTs arrays. X‐ray diffraction, small area electron diffraction, and X‐ray photoelectron spectroscopy analysis determine the formation of hausmannite (Mn3O4). The electrochemical properties of the as‐prepared VACNTs/Mn3O4 nanocomposite electrodes are studied using cyclic voltammetry, galvanostatic charge and discharge cycling in 1 m Na2SO4 aqueous electrolyte. Capacitances as high as 78.62 mF cm−2 at 5 mV s−1 are demonstrated which is one order of magnitude higher than that of pristine VACNTs. In addition, the as‐prepared VACNTs/Mn3O4 nanocomposite electrode showed a good reversibility and cycling stability.

Solvothermal Synthesis and Surface Chemistry To Control the Size and Morphology of Nanoquartz

In this work, we report a solvothermal synthesis method that allows the crystallization of quartz to occur at a relatively low temperature of 300 °C in the form of isolated nanosized euhedral crystals. Transmission electron microscopy (TEM) and small area electron diffraction (SAED) were used to confirm the phases present and their particle sizes, morphologies, and crystallinity of the products. The results show that it is possible to control the size and morphology of the nanoquartz from rough nanospheres to nanorods using fluoride, which templates the nanocrystals and moderates growth.

SPION/β-cyclodextrin core–shell nanostructures for oil spill remediation and organic pollutant removal from waste water

Water contaminated by oil, dyes and micropollutant as Bisphenol A (BPA) pose challenges to the management of water resources. In this small scale laboratory experiment we report the synthesis of superparamagnetic iron-oxide nanoparticles (SPION) and their nanocomposite with β-cyclodextrin (SPION/β-CD). Fourier transform infra red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), high resolution transmission electron microscopy (HRTEM), small area electron diffraction (SAED), photoluminescence (PL), UV–vis spectroscopy, Mossbauer and vibrating sample magnetometry (VSM). Visible light assisted photo-oxidation of BPA was investigated in presence of SPION and SPION/β-CD. The treatment performances were evaluated in terms of BPA degradation using UV–visible spectrophotometer, gas chromatography–mass spectrometry (GC–MS), total organic carbon analysis (TOC), chemical oxygen demand analysis (COD) and CO2 emission. 82.55% degradation was achieved through photodegradation under solar illumination. The magnetic nanocomposite was capable of scavenging oil from water as determined from oil sorption studies and magnetic separation thereof. An oil retention capacity of 7.2g/g of nanocomposite has been observed. In addition 94.22% degradation of Malachite Green dye was also achieved in a 2h sunlight driven photocatalysis process. Interestingly, the higher removal efficiency and reusability studies confirm the suitability for oil spill remediation. Magnetically recoverable, photocatalytic, bio-compatible nanocomposite of SPION and with β-cyclodextrin were prepared by the simple technique and utilized for multi pollutant removal and has a higher reusability and potential biomedical applications.

Polyacrylamide/Ni0.02Zn0.98O Nanocomposite with High Solar Light Photocatalytic Activity and Efficient Adsorption Capacity for Toxic Dye Removal

Photocatalytic removal of toxic textile dyes from wastewater is a challenge because of the relatively low efficiency of photocatalysts. There has been sustained interest in a variety of cheap, hybrid, and efficient nanomaterials for wastewater treatment. In the present work, a novel photocatalyst polyacrylamide/Ni0.02Zn0.98O (PAM/NZP) was synthesized successfully by addition of nanoparticles during polymerization of acrylamide in aqueous medium using ammonium persulfate and N,N′-methylenebis(acrylamide). The material possesses excellent photoactivity and high adsorption capacity.The present investigation describes the applicability of PAM/NZP for removal of malachite green (MG) and rhodamine B (RB) from aqueous solution. The effect of adsorption capacity of cross-linked polyacrylamide on photocatalytic activity of Ni0.02Zn0.98O was also studied. The materials were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, small area electron diffraction, thermal gravimetric analysis, and ultraviolet–visible spectroscopy. The optical band gap was 3.17 eV for NZP and 3.07 eV for PAM/NZP, which is quite lower than that of bare ZnO. The simultaneous adsorption and photocatalysis proved to be a better reaction condition for photodegradation of both the dyes in the presence of PAM/NZP under natural sunlight irradiation. A significant removal efficiency of 99.17% for RB and 96.55% for MG was achieved in 2 h of solar illumination in the presence of the nanocomposite. In addition, the nanocomposite has a high recycling efficiency.

Soft-Templated Room Temperature Fabrication of Nanoscale Lanthanum Phosphate: Synthesis, Photoluminescence, and Energy-Transfer Behavior

We herein report a simple and effective soft template mediated synthesis protocol for the room temperature preparation of highly crystalline cerium (Ce3+) and terbium (Tb3+) doped lanthanum phosphate (LaPO4) nanorods (NRs) and nanoflowers. Anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-alkane soft template was chosen since it forms stable reverse micelles (RMs). Transmission electron microscopy (TEM) analysis corroborated successful formation of LaPO4:Ce3+,Tb3+ NRs having different aspect ratios (ranging from 2.8:1 to 7.6:1) under varying reaction conditions. The crystalline nature of the nanomaterials (NMs) was ascertained by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and small-area electron diffraction (SAED) studies. Energy-dispersive X-ray (EDX) and Fourier transform infrared (FTIR) spectroscopy further verified the elemental existence of the desirably synthesized nanostructures. Experimental results from thermogravimetric-differential therma...

Removal of malachite green and methylene blue by Fe0.01Ni0.01Zn0.98O/polyacrylamide nanocomposite using coupled adsorption and photocatalysis

This study describes the removal of malachite green (MG) and methylene blue (MB) from aqueous solution using adsorption and photodegradation activity of Fe0.01Ni0.01Zn0.98O/polyacrylamide nanocomposite (FNZP/PAM). Fourier transform infra red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), high resolution transmission electron microscopy (HRTEM), small area electron diffraction (SAED) and UV–vis spectroscopy techniques were used for characterization of nanocomposite. The coupled photocatalysis and adsorption shown by FNZP/PAM resulted in fast and higher degradation of MB and MG as compared to dye removal by FNZP. The FNZP/PAM shows a higher rate of dyes removal due to excellent adsorbing properties of cross linked polyacrylamide (PAM). A remarkable 97.56% of MB and 96.13% of MG was achieved for FNZP/PAM by coupled adsorption and photocatalysis after two hours. Thermo gravimetric analysis confirmed the higher thermal stability of FNZP/PAM as compared to PAM. The nanocomposite proved to be a promising antimicrobial agent against bacterial strains of Staphylococcus aureus (S. aureus).

Nanocrystalline ZnO thin films: optoelectronic and gas sensing properties

Nanocrystalline Zinc oxide thin films have been deposited by sol–gel spin coating technique and then have been analyzed before and after a suitable thermal annealing in order to test their applications in various reducing and oxidizing gases. ZnO thin films were highly sensitive and selective for NH3 gas. The spectrophotometric and conductivity measurements have been performed in order to determine the optical and electrical properties of zinc oxide thin films. The structure and the morphology of such material have been investigated by high resolution electron microscopy and small area electron diffraction. The average particle size is in 60–70 nm.

Single step synthesis of highly stable good quality water soluble semiconductor/dendrimer nanocomposites through irradiation route

Gamma irradiation method has been used successfully to prepare nanocrystalline CdS/dendrimer nanocomposites in both aqueous and non-aqueous media at room temperature under ambient pressure. Sodium thiosulfate and carbon disulfide were used as sulfur sources in aqueous solution or in methanol. To the best of our knowledge, this is the first report of room temperature synthesis of semiconductor/dendrimer nanocomposites through gamma irradiation route. The sizes of CdS nanoparticles within the nanocomposites were found to be 3.1 and 2.9 nm in water and methanol, respectively, under identical conditions. Dependence of generation, core and surface functionality of dendrimer on particle size, distribution and also on surface charge has been investigated. Small area electron diffraction (SAED) pattern shows that different phase of CdS nanocrystallites in the composite materials can be generated in the present method if sulfur source is varied. Interestingly, in contrast to the available methods, the present radiolytic process has enabled to produce CdS nanoparticles within the dendrimer matrix with narrow size distribution (as low as 6%) along with increased stability. Our adopted method is suitable for synthesis of nanocomposites in aqueous medium, which is a pre-requisite for biomedical applications.

Cation composition effects on oxide conductivity in theZr2Y2O7–Y3NbO7 system

Polarizable interaction potentials, parametrized using ab initio electronicstructure calculations, have been used in molecular dynamics simulationsto study the effect of cation composition on the ionic conductivity in theZr2Y2O7–Y3NbO7 system and to link the dynamical properties to the degree of lattice disorder.Across the composition range, this system retains a disordered fluoritecrystal structure and the vacancy concentration is constant. The observedtrends of decreasing conductivity and increasing disorder with increasingNb5+ content were reproduced in simulations with the cations randomly assigned to positions onthe cation sublattice. The trends were traced to the influences of the cation chargesand relative sizes and their effect on vacancy ordering by carrying out additionalcalculations in which, for example, the charges of the cations were equalized. Thesimulations did not, however, reproduce all of the observed properties, particularly forY3NbO7. Its conductivity was significantly overestimated and prominent diffuse scatteringfeatures observed in small area electron diffraction studies were not alwaysreproduced. Consideration of these deficiencies led to a preliminary attempt tocharacterize the consequence of partially ordering the cations on their lattice,which significantly affects the propensity for vacancy ordering. The extentand consequences of cation ordering seem to be much less pronounced on theZr2Y2O7 side of the composition range.

Size Tunablity of CdTe Crystallites in Dendrimer Nanocomposites and Temperature Dependent Focusing of Size Distribution

CdTe/Dendrimer nanocomposites have been synthesized for the first time in aqueous and nonaqueous media using PAMAM dendrimer (Generation 5.0). The average size of the as-prepared nanocomposites, as determined from dynamic light scattering (DLS) measurements, was found to be typically 182 nm and 23 nm in water and methanol, respectively under identical conditions of temperature (5 degrees C) and reagent ratio (Cd2+:Te2-, 1:0.5). The size of CdTe NPs within the nanocomposites, was found to be 3.1 and 2.8 nm for the aforementioned samples determined from optical absorption spectra using tight binding approximation. The NPs possess good degree of cystallinity as discernible from the lattice fringes in high-resolution transmission electron microscopic (HRTEM). Transmission electron microscopic (TEM) image and the cubic crystal phase was ascertained from the small area electron diffraction (SAED) pattern. Analysis of FTIR data suggests that CdTe NPs are bound to the surface amine groups as well as -NHCO- moieties lying in the interior of dendrimer structure. The present work demonstrates how the quality of the CdTe NPs formed within the dendrimer matrix can be nicely tuned by varying the parameters, namely, temperature, molar ratio of Cd2+: Te2- and pH. Changing of Cd2+: Te2- ratio of 1:1 to 1:0.5, decreased the average particle size from 5.0 nm to 3.4 nm with concomitant narrowing of size distribution by approximately 35% at 10 degrees C. On lowering down the synthesis temperature (25 degrees C-->5 degrees C), the average particle size remained unaffected while the size distribution became sharply focused. However, the extent of focusing was found to be more in methanol (40%) than that in water (30%).

Photoluminescence and Electroluminescence from a Hybrid of Lumogen Red in Nanoporous-Silica

CdTe/Dendrimer nanocomposites have been synthesized for the first time in aqueous and nonaqueous media using PAMAM dendrimer (Generation 5.0). The average size of the as-prepared nanocomposites, as determined from dynamic light scattering (DLS) measurements, was found to be typically 182 nm and 23 nm in water and methanol, respectively under identical conditions of temperature (5 degrees C) and reagent ratio (Cd2+:Te2-, 1:0.5). The size of CdTe NPs within the nanocomposites, was found to be 3.1 and 2.8 nm for the aforementioned samples determined from optical absorption spectra using tight binding approximation. The NPs possess good degree of cystallinity as discernible from the lattice fringes in high-resolution transmission electron microscopic (HRTEM). Transmission electron microscopic (TEM) image and the cubic crystal phase was ascertained from the small area electron diffraction (SAED) pattern. Analysis of FTIR data suggests that CdTe NPs are bound to the surface amine groups as well as -NHCO- moieties lying in the interior of dendrimer structure. The present work demonstrates how the quality of the CdTe NPs formed within the dendrimer matrix can be nicely tuned by varying the parameters, namely, temperature, molar ratio of Cd2+: Te2- and pH. Changing of Cd2+: Te2- ratio of 1:1 to 1:0.5, decreased the average particle size from 5.0 nm to 3.4 nm with concomitant narrowing of size distribution by approximately 35% at 10 degrees C. On lowering down the synthesis temperature (25 degrees C-->5 degrees C), the average particle size remained unaffected while the size distribution became sharply focused. However, the extent of focusing was found to be more in methanol (40%) than that in water (30%).

Size and Morphology Control of Gallium Oxide Hydroxide GaO(OH), Nano- to Micro-Sized Particles by Soft-Chemistry Route without Surfactant

Micro- to nano-sized GaOOH nanorods and particles were prepared under varying hydrothermal conditions without any surfactant and additive using gallium nitrate and sodium hydroxide as starting materials. The combination of X-ray diffraction (XRD), transmission electron microscopy (TEM), small area electron diffraction (SAED), energy-dispersive X-ray analysis (EDX), thermogravimetric analysis (TG), and FT-IR was employed to characterize the resulting gallium oxide hydroxide nanorods. Detailed results and the possible growth mechanism are presented.

Atomic force acoustic microscopy characterization of nanostructured selenium–tin thin films

Nanostructured tin selenide based ultrathin films have been deposited on fused quartz substrates by thermal evaporation. The morphological and structural properties of the obtained polycrystalline SnSe films have been routinely characterized using atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM), and small-area electron diffraction (SAED). The atomic force acoustic microscopy (AFAM) technique has been used in order to perform a preliminary characterization of the local elastic properties of a film surface. The reported results represent our first attempt to explore the capability of the AFAM technique to discriminate between different phases in such nanostructured compounds.