Characterization Of Nanostructures Research Articles

Plasmonic Properties of Self-Assembled Gold Nanocrescents: Implications for Chemical Sensing.

A bottom-up approach, the Langmuir-Blodgett technique, is used for the preparation of composite thin films of gold nanoparticles and polymers: poly(styrene-b-2-vinylpyridine), poly-2-vinylpyridine, and polystyrene. The self-assembly of poly(styrene-b-2-vinylpyridine) at the air-water interface leads to the formation of surface micelles, which serve as a template for the organization of gold nanoparticles into ring assemblies. By using poly-2-vinylpyridine in conjunction with low surface pressure, the distance between nanostructures can be increased, allowing for optical characterization of single nanostructures. Once deposited on a solid substrate, the preorganized gold nanoparticles are subjected to further growth by the reduction of additional gold, leading to a variety of nanostructures which can be divided into two categories: nanocrescents and circular arrays of nanoparticles. The optical properties of individual structures are investigated by optical dark-field spectroscopy and numerical calculations. The plasmonic behavior of the nanostructures is elucidated through the correlation of optical properties with structural features and the identification of dominant plasmon modes. Being based on a self-assembly approach, the reported method allows for the formation of interesting plasmonic materials under ambient conditions, at a relatively large scale, and at low cost. These attributes, in addition to the resonances located in the near-infrared region of the spectrum, make nanocrescents candidates for biological and chemical sensing.

Synthesis & Characterization of Carbon Nanostructures.

Synthesis In this research a study was conducted on the Synthesis and dimensional structural characterization of nanostructures consisting of Graphene, Nanotubes and Fullerenes C60 and C70 carbon research project consists of a synthesis and characterization in its theoretical and experimental framework to test yields in the synthesis of each nanostructure. Synthesis for Multiple Synthesis Rector MSR will be held in the exploder and electric fields in the toroidal coil Tesla coil. As for the structural dimensional characterization of nanostructured materials carbon is carried out by Raman spectroscopy, diffraction X-ray (XRD) and Transmission Electron Microscopy (TEM) Scanning Electron Microscopy (SEM) Atomic Force Microscopy (AFM) and EELS (Energy Electron loss Spectrum). Justification Synthesis System The main justification synthesis system is to generate nanostructures (Nanotubes, Nanofibers, Fullerenes, graphene) easily and economically; all using little equipment and a simple process which is reflected in lower costs simple synthesis as current processes are very expensive and too complex. Justification Synthesis System The main objective of this system is the generation synthesis of nanostructures by using a Tesla coil (Plasma Generator) as the main component of the system being accessible, simple and inexpensive technology. Another goal is to optimize the generation of nanostructures to its widespread use in industry, nanotechnology and materials science. Through a system very inexpensive and simple synthesis.

Investigation of coherent Fourier scatterometry as a calibration tool for determination of steep side wall angle and height of a nanostructure

Nanostructures with steep side wall angles (swa) play a pivotal role in various technological applications. Accurate characterization of these nanostructures is crucial for optimizing their performance. In this study, we propose a far-field detection method based on coherent Fourier scatterometry (CFS) for accurate quantification of steep swa and heights in cliff-like nanostructures. Our approach introduces a parameter termed ‘visibility’, derived from the unique far-field signatures of cliff-like nanostructures. This parameter serves as a quantitative metric for the calibration of swa and heights. The heightened sensitivity of our method is demonstrated, particularly when the incident polarization is perpendicular to the invariant direction of the nanostructure for swa calibration, while both polarization states exhibit sensitivity to height calibration. Furthermore, a comprehensive sensitivity analysis reveals the stable nature of our method, showcasing that even with fluctuations of ±10 nm in the position of the nanostructure, the resulting swa remains stable within a range of ±0.5∘ . The exponential variation of the visibility parameter with edge roundness is observed, with fluctuations in edge roundness within 10 nm resulting in swa variations within 1.7∘ for both polarization states. In experimental validations, our results demonstrate reasonable agreement between CFS-derived and AFM measurements. The AFM data for swa ( 77.99∘±1.37∘ ) and height (148.35 nm ±2.11 nm) are corroborated with CFS-derived value of swa ( 77.75∘±3.61∘ , 78.36∘±3.89∘ ) and height (149.42 nm ±1.66 nm, 150.05 nm ±1.04 nm) obtained from calibration curves for TM and TE incident beams, respectively. Overall, our findings underscore CFS as a potential and reliable tool for nanostructure characterization, offering precise measurements that are pivotal for advancing nanotechnology.

Characterization of nanostructure of naturally occurring disordered sp2 carbon by impedance spectroscopy

We analyzed main structural models of sp2 carbon with a structure similar to glassy carbon from the point of view of impedance spectroscopy in the range from hertz frequencies to 15 MHz. We used samples of natural carbon (shungites, anthraxolites) with a structure and properties close to synthetic glassy carbon. The impedance spectroscopy results were compared to high-resolution transmission electron microscopy (HRTEM) images, which revealed a complex nanoscale structure including stacks of misoriented graphene layers, multilayer ribbons, and closed fullerene-like structures. The high locality of the HRTEM method often does not allow identifying the predominant nano-sized structure if two or more types of structural elements are observed in one sample. Using impedance spectroscopy, we found samples with an inductive type of resistance indicating predominant extended and tortuous elements (ribbons, fibrils), as well as samples with a capacitive type of resistance with a significant predominance of nano-sized stacks of graphene layers with impurities/dielectric gaps and micropores.

Nanoscale x-ray imaging with high spectral sensitivity using fluorescence intensity correlations.

This paper introduces spectral incoherent diffractive imaging (SIDI) as a novel method for achieving dark-field imaging of nanostructures with heterogeneous oxidation states. With SIDI, shifts in photoemission profiles can be spatially resolved, enabling the independent imaging of the underlying emitter distributions contributing to each spectral line. In the x-ray domain, this approach offers unique insights beyond the conventional combination of diffraction and x-ray emission spectroscopy. When applied at x-ray free-electron lasers, SIDI promises to be a versatile tool for investigating a broad range of systems, offering unprecedented opportunities for detailed characterization of heterogeneous nanostructures for catalysis and energy storage, including of their ultrafast dynamics.

Synthesis and Characterization of Graphitic Carbon Nanostructures from Cellulose Extraction of Durian Peel Waste

The synthesis of graphitic carbon nanostructures from cellulose extraction of durian peel waste has been successfully carried out in this study. This study aim to produce the graphitic carbon nanostructures to give innovative solutions to the renewable energy storage challenge. Durian peel cellulose was synthesized into graphitic carbon nanostructures through catalytic graphitization method. 4.8 grams of durian peel cellulose was hydrocharred at 200°C for 4 hours, then impregnated using Fe(NO3).9H2O and ethanol for 90 minutes. The sample was then precipitated for 12 hours and dried at 60°C. The sample was pyrolysed at 900°C for 3 hours. Characterization was carried out using TEM and XRD. Characterization TEM showed the morphological characteristics of graphitic carbon nanostructures in the form of coils in uneven amounts with the avarage diameter size is 24.9134 nm. In addition, the XRD characterization results also strengthen the characteristic phase of graphitic carbon nanostructures at 2θ 26.5° and 44.7°, although nanoparticles from Fe catalysis are visible in the sample due to the absence of reflux.

Stochastic 3D Modeling of Nanostructured NVP/C Active Material Particles for Sodium‐Ion Batteries

AbstractA data‐driven modeling approach is presented to quantify the influence of morphology on effective properties in nanostructured sodium vanadium phosphate / carbon composites (NVP/C), which are used as cathode material in sodium‐ion batteries. This approach is based on the combination of advanced imaging techniques, experimental nanostructure characterization and stochastic modeling of the 3D nanostructure consisting of NVP, carbon and pores. By 3D imaging and subsequent post‐processing involving image segmentation, the spatial distribution of NVP is resolved in 3D, and the spatial distribution of carbon and pores is resolved in 2D. Based on this information, a parametric stochastic model, specifically a Pluri‐Gaussian model, is calibrated to the 3D morphology of the nanostructured NVP/C particles. Model validation is performed by comparing the nanostructure of simulated NVP/C composites with image data in terms of morphological descriptors which have not been used for model calibration. Finally, the stochastic model is used for predictive simulation to quantify the effect of varying the amount of carbon while keeping the amount of NVP constant. The presented methodology opens new possibilities for a ressource‐efficient optimization of the morphology of NVP/C particles by modeling and simulation.

Synthesis and characterization of efficient Sr-doped ZnO nanostructures for optoelectronic, and photocatalytic applications

With increasing technological advancements, optoelectronics emergence is inevitable. Various metal oxides are explored for optoelectronics properties and Zinc oxide-based nanostructures have various advantages that can be explored in optoelectronic devices. Nanomaterials that are undoped and Strontium doped were synthesized via a simple wet chemistry route. The study set out to quantify the impact of Strontium doping in Zinc Oxide on optical and photocatalytic properties. The doping of strontium concentration within ZnO varied from 0 % to 3 % by weight of the total molar ratio. The characterization of SZO nanomaterials was done using measurements of X-ray diffraction, Raman Spectroscopy, SEM, Hall effect measurements, UV/Vis, and PL regarding their structural properties, morphological properties, optical properties, and electrical characteristics. X-ray diffraction analysis showed that the Sr-doped ZnO had the hexagonal wurtzite structure of zinc oxide. SEM showed that the morphology of Sr-doped ZnO thin films changed by increasing Sr concentration. Meanwhile, the film’s surface was smooth and crack-free. In UV–Vis experiments, the concentration of Sr doping reduced the optical band gap ranges from 3.27 eV to 2.98 eV. All the samples exhibited n-type conductivity in the Hall Effect. Photocatalytic degradation Methylene Blue was studied and SZO (3 at. %) was best for degradation with efficiency over 80 %.

Synthesis and characterization of Cu-Doped ZnO nanostructures for UV sensing application

In this work, Fabrication, and characterization of Cu-doped ZnO thin films deposited on porous silicon (PSi) substrates have been reported using electrochemical deposition (ECD) technique. The influence of Cu-doping concentrations on morphology, structure, and electrical characteristics of zinc oxide (ZnO) thin films were presented. X-ray diffraction analysis (XRD) has been used to characterize the lattice constants, average size, in-plane (along a-axis) and out of plane (along c-axis) strains for the Cu–ZnO crystals. The effects of Cu-doping concentration on crystal parameters were also investigated from the XRD analysis. The samples were used for UV-sensing applications. In addition, Cu-doped ZnO and pure ZnO metal–semiconductor-metal photodetector, with Cu as electrode contacts were successfully produced for ultraviolet (UV) detection. The I-V (current–voltage) characteristics were used to study the sensing enhancement. Finally, the UV photodetector based on Cu-doped ZnO films was successfully fabricated and shows a five times enhancement in the sensitivity to UV light compared to that of pure ZnO photodetector.

Synthesis and Characterization of Flower-Like Cobalt-Doped ZnO Nanostructures for Ammonia Sensing Applications

Abstract The present study uses the co-precipitation method to explore the synthesis of zinc oxide and cobalt-doped ZnO sensors, encompassing a range of cobalt concentrations from 1 to 4 wt.%. The synthesized samples undergo comprehensive analysis to evaluate their structural, morphological, optical, and gas-sensing properties. X-ray diffraction revealed a hexagonal Wurtzite structure, and the crystallite size decreased from 16.92 to 15.39 nm. Energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy collectively affirmed the presence of cobalt. Scanning electron microscopy was used to analyze the morphological characteristics. The Tauc-plot was used to determine the optical bandgap via diffuse reflectance spectroscopy. As cobalt doping increased, the band gap increased from 3.18 to 3.23 eV. Further, atomic force microscopy and Brunauer-Emmett-Teller analysis were used to assess the surface topography and pore size distribution. The AFM measurements indicated roughness within 435-700 nm. The BET analysis revealed mesoporous properties, with surface area ranging between 18.657 to 21.962 m2/g. Subsequently, the gas-sensing capabilities of the Co-doped ZnO sensors were examined for various volatile organic compounds at room temperature. The sensor with 4% Cobalt doping exhibited a fast response and recovery time of 21 and 20 seconds for 2 ppm of NH3

Study and Characterization of Copper and Titanium Oxides Nanostructures for Some Molecular and Biological Applications

In this work, Copper and Titanium nanocomposites (NPs) were prepared by mixture exchange process with ratios (25, 50 and 75 % CuO-TiO2). The biological activity was studied, and it was found that the concentrations of 50 and 100 µg/mL of 50 and 75 % CuO-TiO2 were the best concentrations, Low concentrations of the nanoparticle mixture at 25 µg/mL also stimulated the growth of symbiotic bacteria. The mixture of nanoparticles was easier to prepare and more effective in inhibiting bacterial growth. biochemical test and PCR were performed to confirm the identity of the studied bacteria. While isolating the bacteria, a new type of bacteria was detected and registered in the Global Gen Bank under accession No. OP942239. Surface and structure properties have been studied using FESEM, EDS analysis, XRD and FTIR respectively. It can be seen that the size and diameter of the nanocomposite increase with the weight ratio of CuO-TiO2. The aggregated CuO-TiO2 nanostructures with different ratios were transformed gradually into a uniform spherical shape. The average size of the CuO/TiO2 composite was found to be about 32.122, 29.865 and 27.607 nm at 25, 50 and 75 % CuO-TiO2 respectively. While the mean sizes of CuO and TiO2 were 25.35 and 34.38 nm respectively. The crystalline size decreases after the ion exchange process, which could be due to the diffraction peaks being broad in all the samples of Copper Titanate at the surface. Subsequently, adding Copper particles to the TiO2 film can improve the performance of the material. HIGHLIGHTSThe nanostructure CuO-TiO2 was created through various loading ratios. These NPs’ efficiency was calculated using a number of techniques, including FTIR, X-ray diffraction, EDS spectra, and FESEM. The observations indicate that molecular transition parameters play an essential role in determining the size, shape, and functionality of CuO- TiO2 NPs. The sharp peaks observed in the composites indicated higher crystallinity in CuO. In addition, two types of NPs have shown promising effects in inhibiting NPs aggregation and enhancing biological effects but the potential of these NPs against different bacteria may differ. Thus, further research and testing is needed to assess its efficacy and human health and environmental impact before considering its use. In conclusion, copper and titanium NPs have their distinct advantages in bacterial inhibition, and the choice between them should be based on specific conditions and environmentally friendly factors. GRAPHICAL ABSTRACT

Structural and optical characterization of dilute Bi-doped GaN nanostructures grown by molecular beam epitaxy

We have carried out detailed studies on the epitaxy and characterization of dilute Bi-doped GaN nanostructures. A comprehensive investigation of Bi-doped GaN nanowires and quasi-film epitaxial growth conditions has been performed. Scanning electron microscopy studies show that lowering the GaBiN growth temperature causes gradual changes in top c-plane nanowire morphology due to the incremental incorporation of foreign Bi atoms. This trend is further substantiated by the secondary ion mass spectroscopy analysis of a multi-layer Bi-doped GaN quasi-film. However, it is also found that the amount of Bi incorporation into the GaN lattice is relatively independent of the N2 flow rate variation under the growth conditions investigated. Furthermore, room-temperature micro-Raman spectra show that there are additional peaks near 530, 650, and 729 cm−1 wave numbers in the Bi-doped GaN samples, which can primarily be attributed to Bi local vibrational modes, indicative of a small amount of Bi incorporation in the GaN lattice. Moreover, phonon calculations with density functional theory indicate that Bi replacing the N sites is the likely origin of the experimentally measured Raman modes. X-ray photoelectron spectroscopy measurements have also been obtained to deduce the electronic interaction between the Bi dopant atom and the GaN nanostructure. Such one-dimensional nanowires permit the synthesis of dislocation-free highly mismatched alloys due to strain relaxation, allowing efficient light absorption and charge carrier extraction that is relevant for solar energy harvesting and artificial photosynthesis.

TEM-compatible microdevice for the complete thermoelectric characterization of epitaxially integrated Si-based nanowires.

Nanostructured materials present improved thermoelectric properties due to non-trivial effects at the nanoscale. However, the characterization of individual nanostructures, especially from the thermal point of view, is still an unsolved topic. This work presents the complete structural, morphological, and thermoelectrical evaluation of the selfsame individual bottom-up integrated nanowire employing an innovative micro-machined device compatible with transmission electron microscopy whose fabrication is also discussed. Thanks to a design that arranges the nanostructured samples completely suspended, detailed structural analysis using transmission electron microscopy is enabled. In the same device architecture, electrical collectors and isolated heaters are available at both ends of the trenches for thermoelectrical measurements of the nanowire i.e. thermal and electrical properties simultaneously. This allows the direct measurement of the nanowire power factor. Furthermore, micro-Raman thermometry measurements were performed to evaluate the thermal conductivity of the same suspended silicon nanowire. A thermal profile of the self-heating nanowire could be spatially resolved and used to compute the thermal conductivity. In this work, heavily-doped silicon nanowires were grown on this microdevices yielding a thermal conductivity of 30.8 ± 1.7 W Km-1 and a power factor of 2.8 mW mK-2 at an average nanowire temperature of 400 K. Notably, no thermal contact resistance was observed between the nanowire and the bulk, confirming the epitaxial attachment. The device presented here shows remarkable utility in the challenging thermoelectrical characterization of integrated nanostructures and in the development of multiple devices such as thermoelectric generators.

Fabrication and characterization of a novel magnetic nanostructure based on pectin-cellulose hydrogel for in vitro hyperthermia during cancer therapy.

Herein, a new magnetic nanobiocomposite based on a synthesized cross-linked pectin-cellulose hydrogel (cross-linked Pec-Cel hydrogel) substrate was designed and synthesized. The formation of the cross-linked Pec-Cel hydrogel with a calcium chloride agent and its magnetization process caused a new and efficient magnetic nanobiocomposite. Several spectral and analytical techniques, including FTIR, SEM, VSM, TGA, XRD, and EDX analyses, were performed to confirm and characterize the structural features of the magnetic cross-linked pectin-cellulose hydrogel nanobiocomposite (magnetic cross-linked Pec-Cel hydrogel nanobiocomposite). Based on SEM images, prepared Fe3O4 magnetic nanoparticles (MNPs) were uniformly dispersed in the Pec-Cel hydrogel context, representing an average particle size between 50.0 and 60.0 nm. The XRD pattern also confirms the crystallinity of the magnetic nanobiocomposite. All constituent elements and their distribution have been depicted in the EDX analysis of the magnetic nanobiocomposite. VSM curves confirmed the superparamagnetic behavior of Fe3O4 MNPs and the magnetic nanobiocomposite with a saturation magnetization of 77.31 emu g-1 and 48.80 emu g-1, respectively. The thermal stability of the nanobiocomposite was authenticated to ca. 800 °C based on the TGA thermogram. Apart from analyzing the structural properties of the magnetic cross-linked Pec-Cel hydrogel nanobiocomposite, different concentrations (0.5 mg mL-1, 1.0 mg mL-1, 2.0 mg mL-1, 5.0 mg mL-1, and 10.0 mg mL-1) of this new magnetic nanostructure were exposed to an alternating magnetic field (AMF) at different frequencies (100.0 MHz, 200.0 MHz, 300.0 MHz, and 400.0 MHz) to evaluate its capacity for an in vitro hyperthermia process; in addition, the highest specific absorption rate (126.0 W g-1) was obtained by the least magnetic nanobiocomposite concentration (0.5 mg mL-1).

Carbon Dots Hybrid Nanostructure-based Electrochemical Sensors: Applications in Determining Different Species in a Real Sample

Abstract: This overview describes the synthesis, characterization, and application of different carbon dots hybrid nanostructures obtained by chemical interaction between nanomaterials or nanomaterials bonded to another material, i.e. silicon (SiO2/Carbon dots-N), reduced graphene oxide (rGO/Carbon dots), multiwalled carbon nanotubes (MWCNTs/Carbon dots), nano magnetite (Carbon dots/Fe3O4), reduced graphene oxide and gold nanoparticles (rGO/Carbon dots/AuNPs), copper oxide (CuO/Carbon dots), and Carbon dots/Metallic NPs that were employed in the development of electrochemical (bio)sensors. The formation of different carbon dots hybrid nanostructures has been characterized by X-ray diffraction (XRD), Raman and ultraviolet- visible spectroscopy, atomic force microscopy (AFM), high-resolution transmission electron microscopy (HR-TEM), and electrochemical techniques. These carbon dots hybrid nanostructures have been used to modify the surface of glassy carbon and screen-printed electrodes and to determine various analytes, i.e., dopamine, uric acid, paracetamol, ephynefrin, dihydroxybenzenes, pesticides, endocrine disruptors, NADH, and other substances in real samples.

Design and Synthesis of DNA Origami Nanostructures to Control TNF Receptor Activation.

Clustering of type II tumor necrosis factor (TNF) receptors (TNFRs) is essential for their activation, yet currently available drugs fail to activate signaling. Some strategies aim to cluster TNFR by using multivalent streptavidin or scaffolds based on dextran or graphene. However, these strategies do not allow for control of the valency or spatial organization of the ligands, and consequently control of the TNFR activation is not optimal. DNA origami nanostructures allow nanometer-precise control of the spatial organization of molecules and complexes, with defined spacing, number and valency. Here, we demonstrate the design and characterization of a DNA origami nanostructure that can be decorated with engineered single-chain TNF-related apoptosis-inducing ligand (SC-TRAIL) complexes, which show increased cell killing compared to SC-TRAIL alone on Jurkat cells. The information in this chapter can be used as a basis to decorate DNA origami nanostructures with various proteins, complexes, or other biomolecules.

Ultrafast Plasmonics for All-Optical Switching and Pulsed Lasers

Surface plasmon resonances (SPRs) are often regarded as the collective oscillations of charge carriers localized at the dielectric–metal interface that display an ultrafast response upon light excitation. The recent developments in the fabrication and characterization of plasmonic nanostructures have stimulated continuous effects in the search for their potential applications in the photonic fields. Concentrating on the role of plasmonics in photonics, this review covers recent advances in ultrafast plasmonic materials with a prime focus on all-optical switching. Fundamental phenomena of plasmonic light–matter interaction and plasmon dynamics are discussed by elaborating on the ultrafast processes unraveled by both experimental and theoretical methods, along with a comprehensive illustration of leveraging ultrafast plasmonics for all-optical switching and pulse laser generation with a focus on device design and performance. This review is concluded with a brief highlight of the current progress and the potential future directions in ultrafast plasmonics.

Nanoscale in-Situ Characterization of Polymer Electrolyte Membrane Fuel Cell Catalyst Layers for Improved Water Management

Polymer electrolyte membrane fuel cells (PEMFCs) facilitate a sustainable energy infrastructure by offering emission-free electricity generation using renewably sourced hydrogen gas. The electrochemical reactions in a fuel cell occur at platinum-loaded catalyst layers (CLs), which are susceptible to degradation. Obstructing catalyst sites (triple phase boundaries1) with reaction by-products, such as water2,3, is the primary degradation mechanism in PEMFCs. Although various CL designs have been tested for improved electrochemical performance, in situ nanoscale visualization of platinum degradation and water accumulation in the CL at controlled temperature and relative humidity (RH) values are required to understand fundamental water mechanics through platinum and carbon nanostructures.In this work, we employed scanning transmission X-ray microscopy (STXM) and X-ray absorption fine structure spectroscopy (XANES) to evaluate the effect of temperature on pristine and broken-in fuel cell CLs. We developed a novel CL in-situ sample cell to enable nanostructured characterization of catalyst layers using STXM in a controlled temperature environment. Carbon 1s, Fluorine 1s, and Oxygen 1s spectral edges were probed utilizing near-edge X-ray absorption fine structure spectroscopy (NEXAFS) to reveal chemical degradation mechanisms and differentiate material structure. Through our custom in-situ cell, we demonstrate that the chemical composition and water accumulation throughout the PEMFC CLs at low, intermediate, and high operating temperatures (25°C, 40°C, and 60°C, respectively) can be quantified, along with thermal expansion analyses of the CL and ionomer membrane. Moreover, we reveal realistic structural and chemical characteristics of nanoscale catalysts by distinguishing regions of Nafion® Ionomer, catalyst carbon support, and platinum throughout the PEMFC’s membrane electrode assembly at industrially relevant fuel cell temperatures. The insights from this work will inform strategies to mitigate water flooding from a nanoscale perspective in addition to the novel in-situ spectromicroscopy characterization of current CL features.1. Fouzaï, I., Gentil, S., Bassetto, V. C., Silva, W. O., Maher, R., & Girault, H. H. (2021). 9(18), 11096-11123.2. Li, H., Tang, Y., Wang, Z., Shi, Z., Wu, S., Song, D., ... & Mazza, A. (2008). 178(1), 103-117.3. Kumsa, D. W., Bhadra, N., Hudak, E. M., Kelley, S. C., Untereker, D. F., & Mortimer, J. T. (2016). 13(5), 052001.

Preparation and surface nanostructural characterization of multi-emitter sources based on superionic conductor CsAg4Br3-xI2+x (x=0.25)

Since the fabrication of micro-/nano-electronic devices is approaching nanoscales and demanding low energy, high dose ion beam processing with controlled area and dense patterns to meet the current semiconductor industry demands, continuous advancement is needed in terms of material design and ion beam techniques. In this perspective, development of new ion sources may provide advanced technologies useful in the manufacture of high-performance devices. Silver ion beams have salient features including simple generating process, nanoscale beam spot size and high intensity ion current. In this paper, we have developed a solid electrolyte multi emitter ion source (SEIS) with CsAg4Br3-xI2+x (x = 0.25) films deposited on silver tips. Ag+ ion emission is significantly enhanced with the added number of emitters and the ion current of 1.95 μA (with four emitter tips) has been obtained at 168 °C temperature and 20 kV accelerating voltage. The stability and cooling/heating curves of the multi-emitter ion beam are measured, and the interrelation between ion current intensity and mechanism of shape geometry of the emitter tips are discussed. Finally, both the solid electrolyte multi-tip emitters and the collector surfaces are analyzed, with an attempt to precisely control of formation of the nanoparticles (NPs) including their size and height through the control of the ion implantation parameters.

Nanostructural Characterization of Luminescent Polyvinyl Alcohol/Graphene Quantum Dots Nanocomposite Films.

This study focuses on the fabrication of polymer nanocomposite films using polyvinyl alcohol (PVA)/graphene quantum dots (GQDs). We investigate the relationship between the structural, thermal, and nanoscale morphological properties of these films and their photoluminescent response. Although according to X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and differential thermal analysis (DTA), the incorporation of GQDs does not significantly affect the percentage crystallinity of the PVA matrix, for a range of added GQD concentrations, atomic force microscopy (AFM) showed the formation of islands with apparent crystalline morphology on the surface of the PVA/GQD films. This observation suggests that GQDs presumably act as nucleating agents for island growth. The incorporation of GQDs also led to the formation of characteristic surface pores with increased stiffness and frictional contrast, as indicated by ultrasonic force microscopy (UFM) and frictional force microscopy (FFM) data. The photoluminescence (PL) spectra of the films were found to depend both on the amount of GQDs incorporated and on the film morphology. For GQD loads >1.2%wt, a GQD-related band was observed at ~1650 cm-1 in FT-IR, along with an increase in the PL band at lower energy. For a load of ~2%wt GQDs, the surface morphology was characterized by extended cluster aggregates with lower stiffness and friction than the surrounding matrix, and the PL signal decreased.