Formation Of Nano-sized Structures Research Articles

Nanosized Modification of the Silicon Surface by the Method of Focused Ion Beams

This paper presents the results of experimental studies of the modes of formation of nanosized structures on the surface of a silicon substrate by the method of focused ion beams (FIB). The regularities of the effect of the ion beam current, accelerating voltage, and radiation dose on the surface morphology of nanoscale structures are determined. The modes under which the effects of implantation swelling (structure height up to 3 nm) and etching (structure depth up to 8 nm) manifest themselves are determined. The average roughness of the resulting structures varies from 0.13 to 0.24 nm. The results can be used in the development of technology for manufacturing instrument structures in nanoelectronics and nanophotonics.

Enhancement in the luminescence of green-emission from emissive surface defects of Dy3+doped ZnO nanoluminophores: A simple, mass-scale productive approach for optoelectronic devices

In the present work, dysprosium doped ZnO (DZO). nanoluminophores with different Dy concentrations are prepared by simple, one-step and mass-scale productive solid state reaction method. The structural, morphological and optical properties of synthesized Dy doped ZnO nanoluminophores have been characterized using X-ray diffraction (XRD) patterns, field emission scanning microscopy (FE-SEM), Fourier transfer infrared spectroscopy (FT-IR) and photoluminescence (PL) spectroscopy respectively. The XRD patterns of Dy-doped ZnO samples show hexagonal wurtzite structure having broadening in peaks indicates the formation of nano-sized structures. The estimated particle sizes of prepared samples are found to be in the range of ∼17–85 nm. The SEM micrographs indicate that the synthesized samples are spherical in natures and observed a change in their morphologies with Dy concentrations. FTIR results exhibit several absorption bands of ZnO:Dy nanoluminophores at room temperature. Photoluminescence spectra illustrate enhanced PL emission intensity of peaks at ∼391–397 nm in UV region and defects related green emissions ranging from ∼505–510 nm in visible region. The obtained results reveal the suitability of synthesized rare-earth (RE) doped ZnO nanoluminophores for optoelectronic devices.

Nanosized Structure Formation by Trampoline Ion-Plasma Sputtering

Nanosized Structure Formation by Trampoline Ion-Plasma Sputtering

MnS nanoparticles embedded in N,S co-doped carbon nanosheets for superior lithium ion storage

Manganese sulfide has been explored as anode for LIBs owing to its impressive theoretical capacity. However, inferior electronic/ionic conductivity and severe volume expansion occurring during the electrochemical cycle usually result in poor electrochemical performance. In this report, a novel composite, MnS nanoparticles integrating N,S co-doped carbon nanosheets (N,S-C) grown on flexible carbon fiber cloth (MnS@N,S-C/CFC), is fabricated as anode material for LIBs. The N,S co-doped carbon nanosheets protect MnS particles from aggregation so as to facilitate nanosized structure formation, significantly accelerating Li+ diffusivity and accommodating stress/strain caused by volume changes. Nanosheets are also connected by CFC substrate to provide the transmission pathway of the electrons and promote fast electron transfer. Morever, compared to the MnS/CFC particles, the remarkably boosted integration between MnS@N,S-C and CFC substrate ensures superior conductivity and improved mechanical stability. Consequently, the MnS@N,S-C/CFC electrode delivers superior specific capacity of 800 mAh g−1 at 0.05 A g−1 as well as excellent rate-capability (535 mAh g−1 up to 2 A g−1), and improved durability (maintaining 52.7% after 500 cycles at 2 A g−1), presenting a simple strategy to boost the electrochemical performance of LIBs anodes by encapsulation of conductive carbon and heteroatom doping.

Core/shell nanoassembly of amphiphilic naproxen-polyethylene glycol: synthesis, characterisation and evaluation as drug delivery system.

Small molecule-based amphiphiles self-assemble into nanostructures (micelles) in aqueous medium which are currently being explored as novel drug delivery systems. Here, naproxen-polyethylene glycol (N-PEG), a small molecule-derived amphiphile, has been synthesised, characterised and evaluated as hydrophobic drug carrier. 1H, 13C Nuclear magnetic resonance (NMR), mass spectrometry (MS) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of N-PEG and dynamic light scattering (DLS) revealed the formation of nano-sized structures of ∼228 nm. Transmission electron microscope (TEM) analysis showed aggregation behaviour of the structures with average size of ∼230 nm. Biodegradability aspect of the micellar-structured N-PEG was demonstrated by lipase-mediated degradation studies using DLS and TEM. High encapsulation efficiency followed by release in a sustained manner of a well-known anticancer drug, doxorubicin, demonstrated the feasibility of the new drug delivery system. These results advocate the promising potential of N-PEG micelles as efficient drug delivery system for specific delivery to cancerous cells in vitro and in vivo.

Optical and dielectric properties of nano-sized tricalcium aluminate hexahydrate (C3AH6) cement

The present study investigates the optical and dielectric properties of nano-sized C3AH6 cement hydrates. A cement product was fabricated via a simple hydration process using a derivative of a C12A7 cement precursor reacting with de-ionized water while raising the reaction temperature to 100 °C. A crystalline phase of the C3AH6 cement product was characterized and confirmed using an XRD technique. Its morphology was also evaluated using TEM and SEM techniques. It was found that nano-sized C3AH6 (in size 10–50 nm) was successfully derived via this process. This cement product was thermodynamically stable over the range of room temperature to 300 °C. The optical direct gap was 4.1 eV and the indirect energy gap was 2.45 eV. Over the range of 20 Hz to 2 MHz, the observed capacitance was 10−10 F–10−11 F and the dielectric constant varied from 20 to 150. The dielectric properties were enhanced over those of general cement compounds. This effect was due to its complex structure in which –O–H bonding appeared in the structure and the formation of nano-sized structures from this process. These results suggested that the nano-C3AH6 hydrated particles were transparent to visible light and exhibited a high frequency electrical response. This implies an important role for these cement-based materials as potential candidates having optical and dielectric properties appropriate for applications such as smart building materials in the form of transparent electrode windows, smart wall capacitors, triboelectric devices and supercapacitors.

Viruses Occur Incorporated in Biogenic High-Mg Calcite from Hypersaline Microbial Mats.

Using three different microscopy techniques (epifluorescence, electronic and atomic force microscopy), we showed that high-Mg calcite grains in calcifying microbial mats from the hypersaline lake “La Salada de Chiprana”, Spain, contain viruses with a diameter of 50–80 nm. Energy-dispersive X-ray spectrometer analysis revealed that they contain nitrogen and phosphorus in a molar ratio of ~9, which is typical for viruses. Nucleic acid staining revealed that they contain DNA or RNA. As characteristic for hypersaline environments, the concentrations of free and attached viruses were high (>1010 viruses per g of mat). In addition, we showed that acid treatment (dissolution of calcite) resulted in release of viruses into suspension and estimated that there were ~15 × 109 viruses per g of calcite. We suggest that virus-mineral interactions are one of the possible ways for the formation of nano-sized structures often described as “nanobacteria” and that viruses may play a role in initiating calcification.

Formation of Ni-driven nano-sized structures on Ag/Ge(111)-√3 × √3 surface: STM study

The formation of nano-sized structures upon room temperature (RT) deposition of small amounts of Ni (~0.1 ml) onto an Ag/Ge(111)-√3 × √3 surface was investigated by scanning tunnelling microscopy. The RT behaviour was dominated by the formation of Ni clusters, which did not interact chemically with the surface. The images as obtained after annealing within the temperature range between 100oC and 500oC corresponded to the formation of clusters as well as triangular, elongated and hexagonal-shaped nano-sized islands. Annealing above 550oC resulted in the transformation of the √3 × √3 phase into a c(2 × 8) phase. This process was accompanied by the thermal decomposition of the majority of the islands, except the hexagonal-shaped ones. The latter remained on the surface in an unaltered form upon annealing even at 800oC. We propose that the hexagonal-islands are made of Ni and Ge compounds rather than pure Ni atoms.

Investigation of the Interactions Involved in the Formation of Nanotubes from Organogelators

Investigations into the formation of nanosized structures, particularly nanotubes, by a diamide ester compound are reported. Two aspects are concurrently examined: the role of the solvent and the role of the alkyl chain. The former is addressed by using a benzene derivative (o-xylene) and a totally saturated double ring (trans-decahydronaphthalene) whereas the latter is achieved by replacing the hydrogenous alkyl chain with its fluorinated counterpart while keeping the overall architecture the same. The thermodynamic behavior by differential scanning calorimetry, the morphology by transmission electron microscopy, and the structure by X-ray scattering and small-angle neutron scattering are studied. Despite the identical architecture, the fluorinated molecule does not produce any nanotubes, unlike its totally hydrogenous counterpart. Also, o-xylene prevents the hydrogenous molecule from forming nanotubes, while nanotapes are produced instead. Conversely, the fluorinated molecule produces regularly twisted protostructures in either solvent. Neutron scattering experiments show that the fluorinated alky chain is located within the core of this structure. This suggests that the prerequisite for forming nanotubes relies on the necessity of the alkyl group to point outward.

Protses formuvannya nanostruktur na VdV-poverkhni krystaliv CdI2

Morphological characteristics of nano-sized defects and nanostructures formed on the surface of CdI2 layered crystals have been studied, and the processes of their growth under conditions close to the thermodynamic equilibrium have been analyzed. The formation of nano-sized structures – nanoclusters and nanopores – emerging on the CdI2 surface after holding the crystals in air for some time is revealed for the first time. A mechanism of cluster formation is proposed, which includes a number of stages of cluster growth; these are the nucleation, formation of separate noninteracting nanoaggregates, and association of the latter into agglomerates. The major morphometric characteristics of nanostructures – their average radius and height, and the average distance between the nearest neighbors – are analyzed.

Using focused ion beam for nanosized structure formation in microfluidic chips

Microfluidic chips (MFCs) provide a basis for modern compact analytical systems possessing unique performance characteristics. Using nanosized functional structures in MFCs opens new possibilities in this field. Results of the formation of nanosized structures used as traps for microscopic particles in MFC channels are presented and discussed. Micron-sized channels in MFC structures on glass substrates were formed by photolithography and acid etching, while nanosized structures were obtained using focused ion and electron beams. The proposed MFC structures can be used for studying biological objects by high-resolution microscopy techniques.

Nanosized structure formation in metals under the action of pulsed electric-explosion-induced plasma jets

A new mechanism is proposed that explains the formation of a thin nanostructural near-surface layer in the alloyed zone formed during the metal surface fusion treatment under the action of a pulsed plasma jet generated by the electric explosion of conductors. The proposed mechanism is based upon the development of the Kelvin-Helmholtz (KH) instability at the plasma-melt interface. A dispersion equation is obtained for the KH problem with allowance for the viscous and capillary stresses in the melt. The dependence of the KH instability increment on the surface perturbation wavelength exhibits a maximum in a nanometer range for the relative velocities of plasma with respect to the melt (within 100–1000 m/s) achieved under real treatment conditions.

Nonradiative energy transfer as a method for investigation of self-assembling nanostructures of lanthanide complexes in solutions

Works concerning the application of nonradiative transfer of electronic excitation energy to investigation into nanostructures of lanthanide complexes in aqueous solutions are surveyed. The effect of the formation of nanosized structures on the quenching of energy donors Ln(III) ions by acceptor ions in concentrated chloride solutions of structuring ions (Li(I), Ca(II)) was discussed. The columinescence phenomenon observed in aqueous solutions of lanthanide chelates was considered. It was shown that the enhancement of luminescence Eu(III) and Tb(III) complexes in water in the presence of excess β-diketones with an admixture of other Ln(III) ions, primarily Gd(III), (columinescence) is due to sensitization via energy transfer over triplet levels of the ligands in the nanostructures formed under these conditions and to the weakening of deactivation of excited luminescent ions by the formation of nanostructures. The influence of the solution preparation procedure on the formation of nanostructures of chelates with different lanthanide ions was revealed, which manifest itself as a variation in the enhancement and quenching of luminescence in the presence of ions from the cerium and yttrium subgroups. Possible applications of the columinescence phenomenon to chemical and medical analysis are briefly discussed.

Pattern formation on InP(1 1 1) surfaces after ion implantation

We have investigated the formation of nanosized structures on InP(111) surfaces after 1.5MeV Sb implantation. Scanning probe microscope (SPM) has been utilized to investigate the size, height and the density distributions of the nanostructures as a function of ion fluence. We observe nanostructures smaller than 100nm and lower than 4nm at all fluences. Moreover in large nanostructures we observe agglomeration of several smaller structures. We have also investigated the rms surface roughness of the InP(111) surfaces after MeV implantations.

Atomic “needles” and “bullets” in Bose-Einstein condensate and the formation of nanosized structures

The Gross-Pitaevski equation modified through the inclusion of a term accounting for the nonlocality of interatomic interaction was used to demonstrate the occurrence of extremely narrow two-and three-dimensional solitonic states in atomic Bose-Einstein condensates. The estimates of the sizes of these states gave a value of ∼ 20–60 nm (atomic “needles” and “bullets”) for lithium atoms. The soliton lifetimes caused by two-and three-particle collisions were estimated. The limiting possibilities of the formation of nanostructures using needles and bullets were compared with the possibilities of other nanolithographic methods.

Effect of sol-gel derived Al2O3-ZrO2 and Al2O3-TiO2 oxides on the selectivity of NO reduction by CO under oxidizing conditions

The role of Al2O3-ZrO2 and Al2O3-TiO2 sol-gel prepared supports in the activity of platinum for the NO reduction by CO under oxidizing conditions has been studied. 27Al MAS-NMR spectra have shown the formation of pentacoordinate AlV in alumina-zirconia support. ZrO2 or TiO2 crystalline phases cannot be identified by XRD diffraction, suggesting the formation of nanosized structures supported on alumina. When the reaction was carried out in presence of oxygen, large amounts of NO2 were observed on Pt/Al2O3-ZrO2catalyst, while the formation of N2O is more prononced on Pt/Al2O3-TiO2 catalyst. The effect of water during NO reduction is discussed.