Journal of Nano Research Vol. 61

Abstract: In this study, a simple one-step synthetic approach using lotus seed pods and iron(III) chloride has been developed to prepare Fe₃O₄ nanoparticles loaded activated carbon composite (Fe₃O₄-NPs/AC) for removal of Ni(II) ions from aqueous solution. The physical and chemical characteristics of Fe₃O₄-NPs/AC were comprehensively analyzed by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and Brunauer–Emmett–Teller analysis. On account of the combined advantages of lotus seed pod carbon and Fe₃O₄ nanoparticles, the Fe₃O₄-NPs/AC showed excellent adsorption efficiency for Ni(II) ions with the maximum adsorption capacity of 50.72 mg g^-1 at optimal conditions (pH of 6, contact time of 60 min, 25 °C, and adsorbent dosage of 4.0 g L^-1). It was found that the adsorption process of Ni(II) on Fe₃O₄-NPs/AC was feasible, spontaneous and endothermic, and was well described by the Langmuir isotherm model and pseudo-first-order kinetic equation. The Fe₃O₄-NPs/AC composite also showed good reusability with removal efficiency of greater than 86.25% after five cycles of reuse.

Abstract: Oleic acid (OA) and octadecylamine (ODA) capped lead sulphide (PbS) nanoparticles were prepared at 150, 190 and 230 °C. X-ray diffraction patterns indicates that the synthesized PbS nanoparticles were in the rock cubic salt crystalline phase. The particle sizes of the as-prepared PbS nanoparticles are in the range 2.91–10.05 nm for OA-PbS(150), 24.92–39.98 nm for ODA-PbS(150), 9.26 – 29.08 nm for OA-PbS(190), 34.54 – 48.04 nm for ODA-PbS(190), 17.96–88.07 nm for OA-PbS(230) and 53.60 – 94.42 nm for ODA-PbS(230). SEM images revealed flaky and agglomerated spherical like morphology for the nanoparticles. The energy bandgap of the PbS nanoparticles are in the range 4.14 – 4.25 eV, OA-PbS(230) have the lowest bandgap of 4.14 eV while ODA-PbS(150) have the highest bandgap of 4.25 eV. The PbS nanoparticles were used as photocatalyst for the degradation of Rhodamine B and OA-PbS(150) showed efficiency of 44.11% after 360 mins. Cyclic voltammetry of the PbS nanoparticles showed a reversible redox reaction and linear Randles-Sevcik plots indicates electron transfer process is diffusion controlled.

Abstract: In this work, we simulated and analysed phase transformations in the structure of nanosized bimetallic titanium-containing clusters during the cooling process. The results demonstrate the predominantly α+β crystalline structure of the TiAl nanoalloy after cooling, and the TiV nanoalloy has an amorphous structure. The glass transition temperatures for bimetallic systems TiAl and TiV for various compositions were determined.

Abstract: A simple method to synthesize metal nanoparticles (Nps) has been proposed using high vacuum thermal deposition (HVTD) by reverse engineering of thin films to Nps. Metal Nps synthesized by this technique corresponds to the top-down approach of nanomaterial synthesis from bulk metals of silver and copper wires to metal Nps. A high-vacuum thermal deposition is a commonly used technique for thin-film deposition in many applications. Synthesis of metal Nps by HVTD is simple, efficient, and can provide particle of about few tens of nanometers is effortless. A precoated thin layer of polyethylene glycol (PEG) on a glass substrate (Petri dish), is allowed deposit with a metallic thin film by thermionically evaporating bulk metal wires in high vacuum. The deposited metal thin film is removed along with the PEG coating into a liquid medium and subjected to sonication, stirring, and deoxidation. Obtaining the particle size in tens of nanometer range in one step is one projecting factor by HVTD technique. Also, providing the feasibility of reusing large particles as precursors after synthesis is a unique vantage point. The Nps were analyzed by various characterizations tools to evaluate the underlying properties.

Abstract: Kaolin is a cheap and abundant source of silica and alumina, which may be used as precursors for the production of zeolites, molecular sieves with pores in the nanometer scale. Brazil, one the largest producers of kaolin, generates tons of kaolin waste in the paper coating process. That waste may be used to synthesize zeolite A and hydroxysodalite, greater added value materials with a wide range of applications. In this work, Zeolite A and hydroxysodalite were synthesized from kaolin waste of processing industries for paper coating. Kaolin was calcined to dehydroxylate kaolinite and obtain metakaolin, an amorphous material with Si/Al ratio equal to 1, being suitable for production of zeolite A and hydroxysodalite. Zeolites were synthesized under static hydrothermal conditions by reacting metakaolin with NaOH solutions of different concentrations. The zeolitic products were characterized by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The results showed that the higher the NaOH concentration in the reaction medium, the higher the proportion of hydroxysodalite in the zeolitic samples.

Abstract: Many of the excavated pottery artifacts are suffering from different deterioration aspects. The pressure of burial environment is considered the most deteriorative agent for pottery in soil, which leads to damage of the artifact. Therefore, it is necessary to join these damaged parts to be suitable for museum display. The adhesive materials play a significant role in the joining processes of these artifacts. In this study, Paraloid B-72 in its traditional and nano form was prepared (50% in acetone) as adhesive for pottery artifacts. Twelve pottery tiles (14 ×4×1 cm) were prepared and then were adhered together with the adhesive in traditional and nano forms. The pottery samples were exposed to artificial aging as follows; accelerated heat-humid aging (temperature 100°C and 60% relative humidity) and light aging by U.V lamp for 100 hours. Visual assessment and several analytical techniques were used for the evaluation of the selected adhesive. The analytical techniques are transmission electron microscope (TEM), scanning electron microscope (SEM), color change and tensile strength. The results obtained from transmission electron microscope showed that grain size of nano paraloid was ranging from 33 to 51 nm where the particle size of the traditional paraloid was in the range between 103 to 150 nm. Visual assessment proved that nano paraloid had some simple changes in appearance. Scanning electron microscope revealed that the nano paraloid was more resistance for aging than traditional form. Color change revealed that nano paraloid gave the lowest level of total color differences (ΔE) after light, heat-humid and light-heat aging with 2.31, 3.26 and 4.60 respectively. The tensile strength revealed that nano paraloid gave highest tensile strength (81.3 N/mm²). According to these results, we recommend the use of nano paraloid in joining of archaeological pottery artifacts.

Abstract: In the present study, Zn_xSn_1-xS (x = 0, 0.25, 0.5, 0.75 and 1) thin film samples were deposited by ultrasonic spray pyrolysis technique on glass substrates at 350°C to investigate the effect of variation of Zn concentration (x) on the structural, morphological, optical and electrical properties of Zn_xSn_1-xS thin films. The films were deposited by varying Zn content in the starting solution. The films deposited were found to be amorphous having root mean square (RMS) roughness ranged from 18.2 to 93.5 nm. The optical characterization by UV-Vis spectroscopy showed that the transmittance and reflectance of all samples are lower than 12.2 % and 10 % respectively. The optical band gap was estimated from the reflectance and transmittance spectra are about 3.86 eV. The carrier mobility is ranged from 113 to 2600 cm²/v.s.

Abstract: While much numerical studies have been done on short channel carbon nanotube field effect transistors (CNT-FETs), there are only a few numerical reports on long channel devices. Long channel CNT-FETs have been widely used in chemical sensors and biosensors as well as light emitters. Therefore, numerical study is helpful for a better understanding of the behavior of such devices. In this paper, we numerically analyze long-channel CNT-FETs by solving the continuity and charge equations self-consistently. To increase the accuracy of simulation, filed-dependent mobility is applied to the equations. Furthermore, a method is proposed to obtain the electrical current of transistors as a function of CNT diameter. Obtained results are in good agreement with the previous experimental data. It is found that compared to a CNT-based resistor, the dependence of current on diameter is much higher in a CNT-FET. Finally, reproducibility of transistors based on the arrays of random CNTs of 1-2 nm diameter in terms of the CNTs number is also investigated.

Abstract: In this article, an analytical model for Double gate Metal Oxide Semiconductor Field Effect Transistor (DG MOSFET) is developed including Quantum effects. The Schrodinger–Poisson’s equation is used to develop the analytical Quantum model using Variational method. A mathematical expression for inversion charge density is obtained and the model was developed with quantum effects by means of oxide capacitance for different channel thickness and gate oxide thickness. Based on inversion charge density model the compact model is developed for transfer characteristics, transconductance and C-V curves of DG MOSFETs. The results of the model are compared to the simulated results. The comparison shows the accuracy of the proposed model.

Abstract: This paper presents an investigation of the size-dependent static and dynamic characteristics of functionally graded (FG) Timoshenko nanobeams embedded in a double-parameter elastic medium. Unlike existing Timoshenko nanobeam models, the combined effects of surface elasticity, residual surface stress, surface mass density and Poisson’s ratio, in addition to axial deformation, are incorporated in the newly developed model. Also, the continuous gradation through the thickness of all the properties of both bulk and surface materials is considered via power law. The Navier-type solution is developed for simply supported FG nanobeam in the form of infinite power series for bending, buckling and free vibration. The obtained results agree well with those available in the literature. In addition, selected numerical results are presented to explore the effects of the material length scale parameter, surface parameters, gradient index, elastic medium, and thickness on the static and dynamic responses of FG Timoshenko nanobeams.