Journal of Nano Research, available online http://www.scientific.net/JNanoR
Journal of Nano Research Vol. 29: Content/List of papers
1. The Microstructural, Mechanical and Electro-Mechanical Properties of Graphene Aerogel-PVDF Nanoporous Composites
Authors: Guang Ping Zheng, Z. Han, Y.Z. Liu
Abstract: Graphene aerogel-poly (vinylidene fluoride) (GA-PVDF) nanoporous composites with different concentrations of PVDF are fabricated. Scanning electron microscopy reveals that PVDF films with a typical thickness below 100 nm are coated at the graphene sheets in the nanoporous composites. The GA-PVDF composites show excellent compressibility, ductility and mechanical strength, as well as better sensitivity of stress-dependent electrical resistance compared with those of GAs. The improved mechanical and electro-mechanical behaviours of nanoporous composites are ascribed to the PVDF which possesses piezoelectricity. The structural properties of the graphene-PVDF nanosized hybrid scaffolds are analyzed by dynamical mechanical relaxation. The results demonstrate that the nanoporous composites could be used as high-performance sensors, actuators and kinetic energy harvesters.
Direct link: http://www.scientific.net/JNanoR.29.1
2. Potassium Sulfate Nanoparticles in Water Solutions: Experiment and Quantum Chemistry Simulation
Authors: Marat Myrzakhmet, Kurmangali Baimagambetov, Aliya Bekturganova, Gani Kumisbek, Seitzhan Yessengali
Abstract: Pure potassium sulfate single crystals are transparent in a wide spectral range up to 155 nm and do not show fluorescence and absorption over a wide spectral range of 200-800 nm before and after X-ray irradiation of the samples. The centers of luminescence in thallium-doped potassium sulfate crystals showed a maximum absorption 216 nm and emission 285 nm at room temperature. These centers are singly charged thallium ions. It is interesting to research the optical properties with decreasing size of crystals (size effects). For this, we used a supersaturated aqueous solution of potassium sulfate, in which the crystallization begins. The results of computer simulations using Scigress quantum chemistry package show that the occurrence of macromolecules in a cooled supersaturated solution should result in an increased absorption. In supercooled saturated aqueous solutions of ionic crystals nucleation occurs. A decrease of transparency of saturated solutions with decreasing temperature is clearly seen. This is due to absorption and scattering in the medium with the growing small crystals in the solution.
Direct link: http://www.scientific.net/JNanoR.29.7
3. Characteristics of Nanostructured Cr75Ni25 Alloy Powders Produced by High-Energy Ball Milling
Authors: S. Triaa, L. Faghi, F. Otmane, F. Kali-Ali, M. Azzaz
Abstract: Nanomaterial Cr75Ni25 alloy with a mean crystallite size of 8.3 nm and microstrain of 1.23% after 48h of milling was synthesized by mechanical alloying using a high energy planetary ball milling. The morphological changes and particles size were investigated by scanning electron microscopy and laser diffraction. Magnetic results were measured by Foucault currants, coercive field and residual magnetisation. Structural change during ball milling was evaluated by X-ray diffraction. It was found that the paramagnetic Cr0.8Ni0.2 phase with bcc structure appears for 12 h of milling.
Direct link: http://www.scientific.net/JNanoR.29.13
4. Effect of Hydrogen on Formation of Fe-Al Nanoparticles by Mechanical Milling
Authors: František Lukáč, Jakub Čížek, Yvonna Jirásková, Ivan Procházka, Marian Vlček, Peter Švec, Dušan Janičkovič
Abstract: Nanocrystalline powders of iron aluminum alloy of the Fe82Al18 nominal composition were prepared under air, hydrogen and nitrogen atmospheres from the Fe and Al elemental powders by mechanical alloying and also from the conventionally cast Fe82Al18 alloy by the high-energy ball milling. The intensive plastic deformation during high-energy mechanical treatment has introduced high concentrations of open volume defects and contributed to a rapid decrease in the crystallite size down to a nanoscopic range.The hydrogen atmosphere was found to be the most efficient for the Fe-Al mechanical alloying since it has resulted into the fully alloyed Fe82Al18 after 30 h of milling. On the other hand, the nitrogen and air atmosphere have slightly prevented mechanical alloying and after the same milling time the pure iron particles were still detected in the powder mixtures. This partial suppression of the mechanical alloying process is explained by a formation of thin iron nitride and/or oxide layers on the surface of Fe particles preventing mutual inter-diffusion of Fe and Al atoms.
Direct link: http://www.scientific.net/JNanoR.29.23
5. Electrochemically Exfoliated Graphene
Authors: Mauro Cesar Terence, Ederson Esteves Silva, Juan Alfredo Guevara Carrió
Abstract: We analyze graphene obtained by electrochemical exfoliation. This showed an interesting process for obtaining fast and low cost exfoliated graphene. Within a few minutes a large amount exfoliated graphite oxide was produced. Analysis by Raman spectroscopy of the exfoliated graphene showed the effectiveness of the process and the factors that may intensify the disorder of graphene obtained.
Direct link: http://www.scientific.net/JNanoR.29.29
6. Solid State Synthesis and Characterization of NiTe Nanocrystals
Authors: C.E.M. Campos
Abstract: NiTe nanocrystals were prepared through facile and fast solid state reaction (mechanical alloying) of pure elemental tellurium and nickel powders in an argon atmosphere. The samples processed for 3 h, 5 h and 10 h were characterized by X-ray diffraction, transmission electron microscopy, magnetization and Raman spectroscopy. Hexagonal NiTe crystals with an average size of 30 nm can be obtained after only 3 h of processing time. Transmission electron microscopy images showed a broad crystalline size distribution in the agglomerated particles and selected area electron diffraction revealed its crystalline character. NiTe ferromagnetic behavior was confirmed and magnetic parameters were dependent on processing time. Raman spectra showed no unreacted Te or tellurium oxides, but it also showed that laser induced phases transitions (including Te re-crystallization) can be observed for modest laser power (<3 mW).
Direct link: http://www.scientific.net/JNanoR.29.35
7. Irradiation of Pseudoboehmite-Polypropilene Nanocomposites
Authors: Leila F. de Miranda, Antonio H. Minhoz, Rodrigo A. Vicente, Mauro C. Terence, Leonardo G. de Andrade E Silva
Abstract: Polymeric nanocomposites are hybrid materials, where inorganic nanoscale dimensions substances are dispersed in a polymeric matrix. The fillers have a high surface area, promoting better dispersion in the polymeric matrix and therefore an improvement in physical properties of the composite depending on the homogeneity of the material. The preparation of nanocomposites polymer matrix allows in many cases to find a relationship between low cost due to the use of a lower amount of charge, and a high level of performance. In the present work, nanocomposites of polypropylene with different concentrations of pseudoboehmite obtained by a sol-gel process, and treated with octadecylamine were prepared. After preparation, the samples were irradiated with a 0, 50, 100, 200 e 300kGy radiation dose in an electron accelerator. The pseudoboehmite nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, differential thermal analysis and thermogravimetric analysis. The nanocomposites were characterized by thermal and mechanical tests. The addition of pseudoboehmite promoted a reduction of the melting flow during the production of the composites evidencing the interaction of pseudoboehmite with the polymeric matrix. Because the polypropylene is a semicrystalline polymer, when exposed to the irradiation process, their morphology was modified due to scission mechanisms of the polymer chains..
Direct link: http://www.scientific.net/JNanoR.29.41
8. Grain Size Influence on Microwave Absorption Properties in Nanocrystalline Fe40Co60
Authors: Fadhéla Otmane, Salim Triaa, Said Bergheul, Mohamed Azzaz
Abstract: The work we have undertaken consists of preparing nanocrystalline Fe40Co60 powders by the Mechanical Alloying (MA) route. Characterization of obtained powders was applied on two steps. First, structural properties were investigated. X-ray Diffraction (XRD) was used to identify the formation of a disordered α (Fe40Co60) solid solution with a bcc lattice after 60h milling. By the Halder-Wagner approach lattice size, average grain size and residual strain were fixed. The morphology of milled powders was investigated by Scanning Electron Microscopy (SEM). Then bulk specimens were prepared by cold compaction for microwave measurements. Microwave dielectric permittivity and conductivity were determined using cavity perturbation technique. Microwave absorbing characteristic was measured according to line transmission method. Results obtained confirm that the developed structure after milling is the main factor that influences the microwave properties of nanocrystalline Fe40Co60 powders compared to elemental Fe.
Direct link: http://www.scientific.net/JNanoR.29.49
9. Pore Size Control of Macro Porous Carbonized Material by Pyrolysis of Resin/Carbon Composite: Synthesis of Na-A Zeolite Membrane
Authors: S. Aroua, A. Lounis, S. Condom
Abstract: the porous carbon solid (mean pore size 0.1μm ; porosity 32%) was prepared by pyrolysis of composite paste of phenolic resin/AC with a mass ratio (1/1) and a mean grain size of AC of 2.28 μm. The porous agent (starch and PVB) is then added to the paste at 5% and 9% respectively to maintain a pore size of 0.1 microns and maximum porosity. A layer of pure zeolite Na-A is deposited on the carbon support after an oxidation by nitric acid and a seeding of the surface with pre-synthesized Na-A zeolite crystals.
Direct link: http://www.scientific.net/JNanoR.29.55
10. Preparation of Samarium Iron Garnet Nanoparticles via Modified Conventional Mixing Oxides Method
Authors: Ramadan Al Habashi, Zulkifly Abbas
Abstract: This work is concerned with the preparation of samarium iron garnet (Sm3Fe5O12) nanoparticles via an improved technique named: Modified Conventional Mixing Oxides (MCMO) method. This material was characterized by XRD, FESEM, EDX and TEM. Metal oxides and ethanol solution were used as raw materials to prepare Sm3Fe5O12 (SmIG) material. Single-phase SmIG nanoparticles with an average particle value of 25 nm and average crystallite size value of 44 nm have been synthesized at 1350 °C via the MCMO method. SmIG powders with grain sizes below 1 μm and high purity have been presented by FESEM and EDX results, respectively. Lattice constant value of 12.535 Å and density value of 6.221 g.cm-3, were calculated for the SmIG sample. The latter has reached around 99% of its theoretical density. The MCMO method appears to be an attractive route due to the enhancement of structural properties of the interested sample with high yield in the nanoscale product as compared to other preparation techniques.
Direct link: http://www.scientific.net/JNanoR.29.59
11. Synthesis and Characterization of Polymer Nanocomposites Containing Fe- 40 at.% Si Powder Particles Prepared by High Energy Ball Mill
Authors: F. Siahmed, L. Faghi
Abstract: Fe‒Si alloys are widely used as transformer magnets and magnetic cores because of their excellent soft magnetic properties. Fe60Si40 powders were milled in a high energy planetary ball mill (Rctsch PM400) under argon atmosphere at different time of milling. The metal powders obtained have an average diameter d50 of 2.5 to 6 um. The introduction of Si into Fe can result in a decrease of magnetic anisotropy (therefore leading to a decrease of coercivity). The nanocomposite magnetic cores were made from the Fe60Si40 powder obtained by high energy ball milling for different milling time. The particles of powder were mixed with unsaturated polyester (UP) to obtain toroidal cores. The polymerization process was made under a magnetic field H-500 Am. and ensured a preferential orientation of powder particles. Influences of the metallic powder fraction on soft magnetic properties as well as thermal increase under isothermal conditions were investigated along with the possibility to control these properties with the size and amount of powder fraction. It was also found that the soft magnetic properties of the polymer composites can be controlled in a wide range and depends on the mass fraction of the metallic powder Fe60Si40 in the composite, on shape and size of the powder particles and their orientation in the composite.
Direct link: http://www.scientific.net/JNanoR.29.65
12. Modeling Gas Barrier Property Improvements in Polymer-Clay Nano-Composites
Authors: A. Al-Abduljabbar
Abstract: Polymer-clay nanocomposites (PCNC) offer better properties at very low volume fraction of the nanofiller compared to conventional polymer composites, thus minimizing the effect on other favored properties of the polymer. The mechanism by which clay platelets, which have thicknesses of a few nanometers in size compared with several hundred nanometers in the other two dimensions, introduce mechanical and other properties improvement can be attributed to their high efficiency in introducing a discontinuity to flows through the bulk matrix polymer material. The extent of this improvement depends on the success of intercalation or separation of the clay platelets through the bulk matrix. This paper contains a general overview of polymer-clay nanocomposites in terms of properties and processing. The improvements in gas barrier properties are discussed in detail; and a model to represent the effect of introduction of nanofillers on the permeability is proposed. The model builds on previous models to explain the improvements in the gas barrier properties due to the presence of clay nanoparticles and by assuming a proper distribution of these particles.
Direct link: http://www.scientific.net/JNanoR.29.75
13. On the Stiffness of Carbon Nanotubes with Spiral Distortion
Authors: Sadegh Imani Yengejeh, Andreas Öchsner
Abstract: Perfect and spiral configurations of carbon nanotubes (CNTs) were modeled by a commercial finite element package and their tensile behavior was studied. Computational tests with cantilevered boundary conditions were performed to evaluate their Young’s modulus. It was concluded that the existence of any imperfection, spiral shape in particular, in the structure of perfect CNTs results in a remarkable reduction in the stiffness. It was also revealed that the Young’s modulus of perfect CNTs decreases by introducing spiral distortion.
Direct link: http://www.scientific.net/JNanoR.29.85
14. A Numerical Evaluation of the Influence of Atomic Modifications on the Elastic and Shear Behavior of Connected Carbon Nanotubes with Parallel Longitudinal Axes
Authors: Sadegh Imani Yengejeh, Seyedeh Alieh Kazemi, Andreas Öchsner
Abstract: This study deals with the investigation of the tensile and shear behavior of connected carbon nanotubes (CNTs) with parallel longitudinal axes by performing several computational tests. In particular, the effect of imperfections on the mechanical properties, i.e. Young’s modulus and shear modulus, of these nanoconfigurations was analyzed. For this purpose, straight hetero-junctions were simulated in their perfect form and different boundary conditions were considered. In the second phase the three most likely atomic defects, i.e. impurities (doping with Si atoms), vacant sites (carbon vacancy) and introduced perturbations of the ideal geometry in different amounts to the perfect models, were simulated. Finally, the mechanical properties of imperfect hetero-junctions were numerically evaluated and compared with the behavior of perfect ones. It was concluded that the existence of any type of imperfections in the structure of connected CNTs leads to a reduction in the Young’s modulus as well as the shear modulus, and as a result, lower stiffness of these straight nanostructures.
Direct link: http://www.scientific.net/JNanoR.29.93
15. Effect of Annealing Temperature on the Crystallization of Hematite-Alumina (Fe2O3-Al2O3) Nanocomposite and its Influence in EOR Application
Authors: Hassan Soleimani, Noor Rasyada Ahmad Latiff, Noorhana Yahya, Hasnah Mohd Zaid, Maziyar Sabet, Beh Hoe Guan, Kean Chuan Lee
Abstract: Usage of magnetic materials is not unusual in oil and gas research, specifically in enhanced oil recovery (EOR) where various magnetic micro-and nanoparticles were used to enhance sweep efficiency, reducing interfacial tension and heat generation. Magnetic nanoparticles which are activated by a magnetic field are anticipated to have the ability to travel far into the oil reservoir and assist in the displacement of the trapped oil. In this work, magnetic Fe2O3-Al2O3 nanocomposite was synthesized and characterized for its morphological, structural and magnetic properties. At an annealing temperature of 900°C, this nanomaterial starts to exhibit magnetization as the composite structure crystallizes to the stable Fe2O3 and Al2O3. Subsequently, dispersion of the 0.01 wt% Fe2O3-Al2O3 nanocomposite in distilled water was used for displacement tests to validate its feasibility to be applied in EOR. In the displacement test, the effect of electromagnetic waves on the magnetization of Fe2O3-Al2O3 nanofluid was also investigated by irradiating a 13.6 MHz square wave to the porous medium while nanofluid injection is taking place. In conclusion, an almost 20% increment in the recovery of oil was obtained with the application of electromagnetic waves in 2.4 pore volumes (PV) injection of Fe2O3-Al2O3 nanofluid.
Direct link: http://www.scientific.net/JNanoR.29.105
16. Effect of Nickel: Zinc Ratio in Nickel-Zinc-Ferrite Nanoparticles as Surfactant on Recovery Efficiency in Enhanced Oil Recovery
Authors: Hasnah Mohd Zaid, W.A. Wan Azahar, H. Soleimani, N.R. Ahmad Latiff, Afza Shafie, Kean Chuan Lee, H.G. Beh
Abstract: Integration of nanoparticles in enhanced oil recovery (EOR) has been intensively studied in recent years due to their unique properties owing to the nanoscale dimensions, rendering them to have different properties in comparison with its bulk material. Application of magnetic nanoparticles such as ferrites was able to exploit their rheological properties as a chain-like structure formed due to dipole-dipole alignment with the applied magnetic field. Ferromagnetic nanoparticles had shown an increment in the oil recovery under the irradiation of an EM wave. In this research, the influence of magnetic nanoparticles nickel-zinc-ferrite, Ni1-xZnxFe2O2 in the form of nanofluids on the recovery efficiency in EOR was studied. Nickel-zinc-ferrite magnetic nanoparticles with various values of x were synthesized to observe the effect of nickel to zinc ratio on recovery efficiency. The nanoparticles were characterized using X-ray Diffraction (XRD) and Vibrating Sample Magnetometer (VSM). Coreflooding experiments were conducted where the nanofluids were injected into the compacted sand saturated with crude oil under EM irradiation. The amount of oil recovered from the core was evaluated. VSM tests shows that the sample with x = 0.5 had the highest magnetization of 52.6 emu/g. The nanofluids prepared from the sample also achieved the highest crude oil recovery of 26.07% of the residual oil in place (ROIP).
Direct link: http://www.scientific.net/JNanoR.29.115
17. Preparation of Nanocrystalline Ba-Cu-Si Clathrate Powders by Mechanical Milling Using a Process Control Agent
Authors: A. Zolriasatein, X. Yan, P. Rogl, A. Shokuhfar, S. Paschen
Abstract: Nanostructured Ba-Cu-Si clathrate powders were synthesized by mechanical milling using different amounts of process control agent (PCA). We investigated systematically the effects of PCA on the phase constitution and crystallite size of nanopowders using X-ray diffraction (XRD) as well as the particle size and morphology by scanning electron microscopy (SEM). The PCA increases the powder yield by reducing the powder agglomeration. No detectable reaction occurred between the PCA and the clathrate phase, and thus the composition of the clathrate phase is unchanged after milling. Compared to the powders milled without PCA, the crystalline size of powders with PCA is reduced from about 70 to about 50 nm.
Direct link: http://www.scientific.net/JNanoR.29.121
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