Micro & Nano Letters
Volume 13, Issue 5, May 2018
Volumes & issues:
Volume 13, Issue 5
May 2018
Preparation of silver/chemically reduced graphene composite for flexible printed circuits
- Author(s): Bin Feng ; Junjie Ma ; Xiaolong Gu ; Xinbing Zhao ; Yu Zhang
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 576 –579
- DOI: 10.1049/mnl.2017.0621
- Type: Article
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Silver (Ag)/chemically reduced graphene (Ag/CGN) composite succeeded prepared using a simple chemical reduction method. X-ray diffraction, Raman spectra, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results revealed the formation of Ag and the reduction of graphite oxide to graphene during the synthesis process. Scanning electron microscopy observation showed that Ag particles were wrapped by graphene. The resistance of Ag/CGN circuits changed <10% when bended at a radius of 10 mm after 500 cycles and <15% when folded after 50 cycles, indicating the printed Ag/CGN fine circuits possess good electrical conductivity, flexibility and electrical stability under mechanical deformations. Furthermore, the Ag/CGN circuits exhibited high thermal stability, indicating its potential application for fabricating high performance flexible printed circuits.
Fabrication and characterisation of the dye-sensitised solar cells with the mixture of one-dimension TiO2 nanorods and graphite nanosheets as the mesoporous scafford
- Author(s): Junjian Lu ; Min Zhang ; Fei Luo ; Meixiu Wan ; Wen Jin ; Chuanyue Hu
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 580 –582
- DOI: 10.1049/mnl.2017.0591
- Type: Article
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One-dimension (1D) TiO2 nanorods (TiO2-N) has been fabricated via electro-spinning method. The composites of 1D TiO2-N and graphite nanosheets, termed as (TiO2-N/G-N), have been obtained by the physical doping method. The structure and properties of TiO2-N and TiO2-N/G-N have been characterised by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman spectrum. Dye-sensitised solar cells devices with TiO2 nanoparticles, TiO2-N and TiO2-N/G-N as the mesoporous scaffolds have been developed and investigated, respectively. Device 2 based on TiO2-N scaffolds showed short-circuit current (J sc) of 5.57 mA·cm−1, open-circuit voltage (V OC) of 0.68 V, filling factor of 0.75, and the power conversion efficiency of 2.85%, respectively. Compared with device 2, device 3 based on TiO2-N/G-N exhibited reduced photovoltaic properties.
Facile synthesis of hollow microspherical YPO4: Eu3+/Tb3+ using polystyrene spheres as sacrificial template and its photoluminescent properties
- Author(s): Yu Gao ; Jinzhao Feng ; Feixue Ai ; Guiyan Zhao ; Yanfeng Bi ; Fu Ding ; Yaguang Sun ; Zhenhe Xu
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 583 –587
- DOI: 10.1049/mnl.2017.0398
- Type: Article
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Monodisperse hollow microspherical YPO4:Ln3+ (Ln3+ = Eu3+/Tb3+) with diameters of around 2.5 µm have been successfully synthesised by combining a convenient homogeneous precipitation method, an ion exchange method, and a calcination process for the first time. X-ray diffraction, Fourier transform infrared, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and photoluminescence spectra were used to characterise the samples. Upon ultraviolet excitation, Eu3+- and Tb3+-doped microspherical YPO4 showed typical red and green emission, respectively, which provide potential applications in bioanalysis, future colour displays, light-emitting devices, and so on.
Carbonised composite materials based on elastomers filled with carbon nanofillers
- Author(s): Andrey A. Stepashkin ; Dilyus I. Chukov ; Sergey D. Kaloshkin ; Ivan S. Pyatov ; Magomed Ya. Deniev
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 588 –590
- DOI: 10.1049/mnl.2017.0235
- Type: Article
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New carbon–carbon composite materials with operating temperatures up to 400°C obtained by carbonisation of highly filled elastomeric compounds filled with carbon fillers of various morphologies are proposed. Low-temperature carbonisation in a range of 300–400°C allowed to produce thermally and dimensionally stable composite materials from elastomeric compounds. The carbonised composites show rather high values of tensile, compressive and flexural strength, as well as relatively high impact toughness.
Green approach for the synthesis of carboxycoumarins by using a highly active magnetically recyclable nanobiocomposite via sustainable catalysis
- Author(s): Ali Maleki ; Parisa Ravaghi ; Hamed Movahed
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 591 –594
- DOI: 10.1049/mnl.2017.0560
- Type: Article
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An efficient approach was reported for the synthesis of substituted 3-carboxycoumarins via a Knoevenagel condensation reaction between Meldrum's acid and substituted salicylaldehydes in the presence of a magnetic cellulose/Ag catalyst in EtOH at room temperature. This protocol includes many advantages such as remarkable magnetic properties of the nanobiocomposite catalyst, short reaction times, high yields and simple isolation of the organic products. In addition, the nanostructure catalyst can be easily separated from the reaction mixture and reused several times efficiently. Fourier transform infrared spectra, nuclear magnetic resonance spectra, X-ray diffraction pattern and field emission scanning electron microscopy images were performed for the characterisation of the products and the nanocatalyst.
Torsional vibration analysis of nanorods with elastic torsional restraints using non-local elasticity theory
- Author(s): Mustafa Özgür Yayli
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 595 –599
- DOI: 10.1049/mnl.2017.0751
- Type: Article
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In this work, torsional vibration of nanorods with torsional elastic boundary conditions is presented via non-local elasticity theory. The present model developed based on non-local elasticity theory gives the opportunity to interpret size effect. Two torsional elastic springs are attached to a nanorod at both ends. A mathematical transformation known as ‘Stoke transformation’ is utilised to work out the Fourier series for the nanorods with torsional restraints. A coefficient matrix including torsional coefficients is determined by using non-local boundary conditions. A comparison is performed to validate numerical simulations with those given in the literature and the results agree with each other exactly. The non-local effects of torsional end restraints on the free torsional vibration response are investigated for both deformable and rigid boundary conditions.
Effect of tensile strain on the band structure and carrier transport of germanium monosulphide monolayer: a first-principles study
- Author(s): Guanxing Guo and Gang Bi
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 600 –605
- DOI: 10.1049/mnl.2017.0733
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The electronic properties of germanium monosulphide (GeS) monolayer under tensile strain were investigated using first-principles calculations. Our computations showed that the band gap of GeS monolayer was tuned from 1.96 to 2.72 eV via uniaxial and biaxial tensile strain in the range of 10%. Besides, two transitions involving indirect to direct and direct to indirect were triggered when GeS monolayer was applied 3.5 and 9% tensile strain in the zigzag direction, however this transition had not happened when the tensile strain was applied in the armchair and biaxial direction. The band gap variations of GeS monolayer with the tensile strain were explained using a bond nature mechanism based on the Heitler–London's exchange energy model. Moreover, upon applying external strain, the acoustic phonon limited carrier mobility of GeS monolayer had an enhancement with more than two orders of magnitude at 300 K, from to . These findings show that strain engineering is an effective way to tune the electronic properties of GeS monolayer and to extend the applications of GeS monolayer in the field of electronics and optoelectronics.
Ordered mesoporous silicon doped with HPMo-SiO2 solid phase extraction of trace Pb prior to flame atomic absorption spectrometry determination
- Author(s): Junfeng Liu ; Hongli Sun ; Yang Zheng ; Qiuyue Wang ; Jing Guo ; Yiwei Wu
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 606 –610
- DOI: 10.1049/mnl.2017.0915
- Type: Article
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A new selective and sensitivity method for lead (Pb) determination by flame atomic absorption spectrometry has been established using an ordered mesoporous silicon doped with phosphomolybdic acid (HPMo-SiO2) material as an adsorbent. The possible adsorptive mechanism was speculated, and factors affecting its adsorptive behaviours of Pb were investigated in detail. At potassium hydrogen phthalate media, Pb can be quantitatively adsorbed at pH 3.0–6.0, and HPMo-SiO2 exhibited good selectivity toward it. With an enrichment factor of 50, the detection limit and relative standard deviation of Pb are 0.78 ng ml−1 and 0.76 % (n = 9 and C = 2.0 ng ml−1), respectively. The proposed method has been applied to the determination of Pb in human serum, waste water, pond water, soil and whitening cosmetics with recoveries of 93.9–108.5%. To validate the accuracy verification, a GSB-07-1183-2000 certified reference was analysed, and the result is in good agreement with the certified value.
Nano3YSZ electrophoretic deposition from acetylacetone + ethanol solvent on the surface of AZ91 magnesium alloy
- Author(s): Sahand Behrangi and Hossein Aghajani
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 611 –616
- DOI: 10.1049/mnl.2017.0623
- Type: Article
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In the present work, the conditions for electrophoretic deposition of yttria-stabilised zirconia (YSZ) nanopowder have been investigated. For this purpose, the mixture of acetyl acetone and ethanol with different mixing ratios was used as solvent with iodine as a dispersant. To achieve a smooth, homogeneous and crack-free coatings, the following parameters were chosen to be optimised: the mixing ratio of acetyl acetone and ethanol, voltage and duration of deposition. The obtained coatings were observed by scanning electron microscope and optical microscope. The weight of deposits was also measured in different deposition conditions to observe the effects of above-mentioned parameters on the weight and consequently the quality of green coatings. All in all, the suspensions which composed of 50 vol% acetylacetone + 50 vol% ethanol led to more uniformity and fewer cracks/pores in deposits. The other parameters were optimised as follows: deposition voltage of 40 V and deposition time of 3 min. The results of polarisation test showed an improved corrosion resistance of the magnesium alloy with the application of YSZ coating, so that the I corr value decreased from 1.16 to 0.088 mA.
Thermophysical properties of CNT and CNT/Al2O3 hybrid nanofluid
- Author(s): Mageshbabu Devarajan ; Nagarajan Parasumanna Krishnamurthy ; Madhu Balasubramanian ; Bharathwaaj Ramani ; Somchai Wongwises ; Kabeel Abd El-Naby ; Ravishankar Sathyamurthy
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 617 –621
- DOI: 10.1049/mnl.2017.0029
- Type: Article
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This work presents the thermophysical properties of carbon nanotubes (CNT) and CNT/Al2O3 hybrid nanofluids for heat transfer applications. An equal proportion of nanoparticles CNT (50%) and Al2O3 (50%) were added to the base fluid for two different concentration of 0.05 and 0.1%. Results show that addition of Al2O3 nanoparticles with CNT nanofluid improves the thermophysical properties. The thermal conductivity of hybrid nanofluids improved by 20% with a maximum concentration of 0.1%, while the thermal conductivity of CNT alone improved by only 8% with the base fluid. Similarly, density and viscosity of hybrid nanofluid increased up to 7 and 10%, respectively, while comparing it with the base fluid. The result of specific heat energy capacity of hybrid nanofluids increases to about 138% than CNT nanofluid with a maximum concentration of 0.2%.
Facile synthesis and photocatalytic performance of flower-like Ag/ZnO nanocomposites
- Author(s): Honglan Cai ; Qingan Qiao ; Shuhua Ren ; Dongdong Zhu ; Zhongxin Xue
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 622 –625
- DOI: 10.1049/mnl.2018.0019
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Flower-like Ag/ZnO nanocomposites were successfully synthesised by a facile solvothermal method. The product was characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. It was found that ZnO was in the wurtzite phase and the Ag metal particles were loaded on the surface of the ZnO nanosheet. Compared with pure ZnO, the Ag/ZnO nanocomposite displayed significantly visible-light absorption, reduced PL emission intensity, and enhanced photocatalytic activity for the degradation of Rhodamine B, which could be attributed to an effective separation of the photo-generated electron–hole pairs in the nanocomposite.
Suppression of ambipolar conduction and investigation of RF performance characteristics of gate-drain underlap SiGe Schottky barrier field effect transistor
- Author(s): Prashanth Kumar and Brinda Bhowmick
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 626 –630
- DOI: 10.1049/mnl.2017.0895
- Type: Article
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In this work, a hetero structure gate-drain underlap (UL) Schottky barrier (SB) Field Effect Transistor (FET) is explored to achieve high device performance compared with high-k and low-k hetero structure SB FET (HSBFET). The effects of gate drain UL junction on the performances of UL-HSBFETs have been studied in terms of electrical characteristics including on-current (I on), subthreshold swing, I on/I off ratio, ambipolar conduction, and I off current. The low on-state current of silicon-based SB FETs can be enhanced by introducing the low bandgap silicon germanium material. Gate-drain UL and silicon germanium channel with low barrier height provides less tunnelling width which enhances the carrier injection at on-state compared with low-k and high-k HSBFET. Further, the proposed UL-HSBFET suppresses the ambipolar conduction due to holes. In contrast to conventional high-k and low-k HSBFET that suffers from severe ambipolar conduction, the UL-HSBFET device reduces the conduction at drain-channel junction with increasing the UL length to 5, 10, 15, and 20 nm. This provides better radio frequency performances with improved carrier capability of the proposed device. Therefore, UL-HSBFET device can be one of the best possible competitor for high-frequency application. The performance comparison of all the devices is carried out using Technology Computer-Aided Design (TCAD) simulator.
Tunable THz perfect absorber with two absorption peaks based on graphene microribbons
- Author(s): Mingyue Gu ; Binggang Xiao ; Sanshui Xiao
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 631 –635
- DOI: 10.1049/mnl.2017.0742
- Type: Article
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Perfect absorption is characterised by the complete suppression of incident and reflected electromagnetic wave, and complete dissipation of the incident energy. A tunable perfect terahertz (THz) absorber with two absorption peaks based on graphene is presented. The proposed structure consists of graphene microribbons sandwiched between aluminium oxide strips and polymethyl methacrylate slab on a silicon dioxide (SiO2) layer which is covered by periodic gold (Au) ribbons, and the SiO2 layer is supported by the Au substrate. The influence of the structural parameters on the absorption performance was analysed too. Especially, graphene can be used to design tunable THz devices due to its tunability of sheet conductivity which could be controlled by applying a bias voltage or chemical doping. A single-band perfect absorption can be achieved when the chemical potential is set to 0.1 eV. Interestingly, when the chemical potential changed to 0.6 eV, a dual-band absorption spectrum is obtained with absorption efficiency of the two peaks more than 90%. These results imply that the characteristics of graphene-based surface plasmon could be used to design novel THz devices in future.
Preparation and characterisation of ginkgolide nanoparticles via the emulsion solvent evaporation method
- Author(s): Jianfang Jiang ; Juan Ao ; Chunyang He ; Jun Xiong ; Jiaqi Zhao ; Jintao Liu ; Shengrong You ; Hao Jiang
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 636 –640
- DOI: 10.1049/mnl.2017.0906
- Type: Article
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Ginkgolide is the first choice for treatment of cardiovascular and cerebrovascular diseases. However, its conventional dosage form (ginkgolide injection) can easily produce side effects and adverse reactions. Hence, developing a new, safe and efficient nanometre dosage form is imperative. Ginkgolide nanoparticles (GLNs) were prepared via the emulsion solvent evaporation method, and their mean hydrodynamic diameter, surface zeta potential, and surface morphology were characterised. The work studied four factors that were able to influence the properties of GLNs and discussed the preparation mechanism. The results showed that the prepared GLNs were nanomaterials. The optimum preparation conditions were with a W/O of 5.0, C PVA of 6.0%, P of 250 W and T of 4.0 min. The GLN that was prepared under optimum conditions exhibited good dispersity and stability. Its surface zeta potential was −20.97 mV, single particle size was 20–50 nm, and the preparation yield was 73.51%. The pharmacokinetics of GLN was studied in detail, and the C max and AUC0→∞ increased by 63.29 and 67.56%, respectively, compared with ginkgolide injection. This study lays a foundation for the research and development of new nano-dosage forms of ginkgolide and has an important value.
Adsorption of toluene vapours on micro–meso hierarchical porous carbon
- Author(s): Xi Yan ; Fang Liu ; Guiqin Mu ; Zhiguo Zhou ; Yan Xie ; Long Li ; Yangyang Yang ; Xinzhe Wang
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 641 –645
- DOI: 10.1049/mnl.2017.0760
- Type: Article
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This work reports the synthesis of micro–meso hierarchical porous carbons prepared with sucrose as a carbon source. With properties characterised, dynamic adsorption performances of toluene on carbons were investigated at various initial concentrations. Results showed that adsorption capacities as high as 687.60 mg/g toluene/1 cm modified carbon can be achieved. Thus, large surface area, large volume of narrow microporosity and proper average pore size are the desired parameters to achieve strong toluene adsorption capacities. Moderate amounts of surface oxygen groups can also improve the adsorbents performance.
Efficient photocatalytic degradation of methylene blue by using GO/hemin/TiO2 nanocomposite under visible irradiation
- Author(s): Hongming Shang ; Liang Chen ; Yujie Wang ; Hanyu Liu
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 646 –651
- DOI: 10.1049/mnl.2017.0654
- Type: Article
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A hybrid photocatalyst with high photocatalytic activity under visible light was developed. The photocatalyst – graphene oxide (GO)/hemin/titanium dioxide (TiO2) nanocomposite was prepared by a simple method via adsorption at room temperature within 3 h, and was characterised using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV–Vis spectroscopy. The results show that TiO2 nanoparticles were dispersed on the surface of GO sheets uniformly, and the crystal structure remained the same as original anatase TiO2 phase in the presence of GO and hemin. Extended absorption of the nanocomposite into the visible region is benefit for the novel hybrid photocatalyst to utilise visible light more efficiently in the photocatalytic reaction. The photocatalytic activity increased about 70% in the presence of GO and hemin (96%) comparing to pure TiO2 (26%). The nanocomposite catalyst could stably adsorb and degrade methylene blue of different concentration without H2O2 or sacrificial electron donor at a relatively wide range of pH values within 3 h. As well as, the prepared GO/hemin/TiO2 nanocomposite shows good stability and reusability in the photocatalytic reaction, enabling it a potential application in wastewater treatment.
Preparation and thermoelectric properties of PANI matrix graphene composite material
- Author(s): Dengwu Wang ; Qian Xu ; Bo Hu ; Sude Ma
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 652 –656
- DOI: 10.1049/mnl.2017.0607
- Type: Article
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Enormous amounts of unused waste heat have created a strong demand for high-efficient heat-to-electric generators, so thermoelectric (TE) material (i.e. a kind of semiconductor which can generate electricity from a temperature difference) has become increasingly important. However, the inorganic TE materials are expensive, scarce reserves in the earth crust, poisonous and hard to be processed, so the research and development of organic TE materials are very urgent. The polyaniline (PANI, i.e. one of the conducting polymer) and PANI matrix graphene composite material were prepared. The chemical structure, microstructure and properties were investigated by Fourier transformer infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and TE properties measurement system. Results showed that the distribution of the molecule chains in PANI were irregular, however, graphene worked as an interconnected network in the composite materials when 20 wt% graphene was added. Power factor, electrical and thermal conductivities of the composite material increased greatly while ZT (i.e. the figure of merit) of which was two times of PANI. The addition of graphene was an effective method to increase the TE properties of PANI.
Low Pr-doped Bi2O3 photocatalyst with long-wavelength response: mechanisms by first-principles calculation
- Author(s): Guoying Wang ; Xuefu Chen ; Lan Li ; Gaofeng Shi
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 657 –660
- DOI: 10.1049/mnl.2017.0849
- Type: Article
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The low Pr-doped Bi2O3 photocatalyst was prepared via the acrylamide polymerisation method. The photocatalytic activity of prepared samples was evaluated by degrading methyl orange under visible-light irradiation. In comparison to α-Bi2O3 nanoparticles, 4% Pr-α-Bi2O3 photocatalyst exhibit obviously enhanced photocatalytic performance. The theoretical calculation and experimental results show that Pr doping can extend the optical absorption range from 436 to 518 nm and improve the photocatalytic efficiency from 40.9 to 70.4%. This long-wavelength response can be happened because of Pr doping that gives rise to the modification of electron structure and the hybridisation of the energy levels.
Synthesis of SiO2@PAA microspheres and their application for controlling diisooctyl terephthalate migration from flexible PVC materials
- Author(s): Bin Zhang and Jian Han
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 661 –665
- DOI: 10.1049/mnl.2017.0685
- Type: Article
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The preparation of silicon dioxide (SiO2)@poly(acrylic acid) (PAA) microsphere was reported. The modified microspheres can be well dispersed in polyvinyl chloride (PVC) matrix. The structure of SiO2@PAA microspheres can be well-controlled and its mixtures with chlorinated polyethylene (CPE) for controlling diisooctyl terephthalate (DOTP) migration from PVC matrix. The results showed that the migration of DOTP was decreased with increasing content of SiO2@PAA microspheres, and the use of CPE together with SiO2@PAA microspheres has a synergistic effect on the reduction of DOTP migration. Moreover, CPE can enhance the interface combination between SiO2@PAA microsphere and PVC, and good dispersibility was observed in PVC/CPE/SiO2@PAA composites.
Facile synthesis of SiO2@TiO2 hybrid NPs with improved photocatalytic performance
- Author(s): Hongguang Zhang ; Guowei Wang ; Ge Sun ; Feng Xu ; Hongmei Li ; Shuang Li ; Shuang Fu
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 666 –668
- DOI: 10.1049/mnl.2017.0519
- Type: Article
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SiO2@TiO2 hybrid nanoparticles (NPs) were successfully prepared via a simple solvothermal approach using tetrabutyl titanate (Ti(OBu)4) as a titanium source. The morphology and crystal structure of the sample were characterised by scanning electron microscope, transmission electron microscope, and X-ray diffraction. The photocatalytic properties of SiO2@TiO2 hybrid NPs were also investigated in detail. The results showed that the layers of TiO2 NPs have been successfully coated onto the uniform silica sphere and transformed into anatase after calcination at 500°C. In addition, the photocatalytic activity of the as-obtained product was higher than that of the commercial P25-TiO2. The method for producing hybrid NPs has potential applications in building various types of hybrid NPs.
Intercalation pseudocapacitance of expanded graphite in sodium-ion capacitors
- Author(s): Zhendong Zhang ; Jiachang Zhao ; Chaofei Guo ; Jingli Xu
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 669 –672
- DOI: 10.1049/mnl.2017.0714
- Type: Article
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The intercalation pseudocapacitance of expanded graphite (EG) which was prepared by a process of oxidation and partial reduction on pristine graphite was investigated in this work. The structure of EG was characterised by X-ray diffraction (XRD) and high-resolution transmission electron microscope (HRTEM), and the electrochemical performance of EG was measured by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy. The interlayer distance of EG is enlarged from 0.34 to 0.40 nm, which is demonstrated by XRD and HRTEM. EG electrode exhibits a specific capacitance of 228 F/g at current density of 0.5 A/g. Moreover, the material shows excellent cycle stability after 2000 charge–discharge cycles at a current density of 1 A/g. EG could be a very promising material for the supercapacitors industry.
Trapping and scattering effect of charge carriers on impulse breakdown characteristics of nano-fluids
- Author(s): Binbin Xu ; Zicheng Zhang ; Yanpan Hou ; Chao Li ; Jiande Zhang
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 673 –675
- DOI: 10.1049/mnl.2017.0639
- Type: Article
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Propylene carbonate (PC)-based nano-fluids (NFs), containing only 2 ppm TiO2 nano-particles, exhibit more than 60% higher negative impulse breakdown voltage than that of base liquid. It is found that the resistance of the test gap containing PC remains basically invariable when subjected to high amplitude voltage before the development of electrical breakdown. However, for the NF case, the resistance increases by a factor. Moreover, compared with PC, the streamers in NFs are more complex branched. These experimental results indicate that the charge carriers in NFs can be effectively captured and scattered by nano-particles, which is verified by means of the thermally stimulated current method.
Etched Al0.32Ga0.68N/GaN HEMTs with high output current and breakdown voltage (>600 V)
- Author(s): Baoxing Duan ; Shenlong Xie ; Haijun Guo ; Yintang Yang
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 676 –679
- DOI: 10.1049/mnl.2017.0651
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By etching the AlGaN layer close to the gate edge of the drain side, the novel AlGaN/GaN high-electron-mobility transistor with the etched AlGaN epitaxial layer (etched AlGaN/GaN high-electron-mobility transistors, HEMTs) is proposed in this work with the high-resistance GaN buffer layer. The relationship between the 2D electron gas (2DEG) concentration and the thickness of the AlGaN layer has been explored. The 2DEG density under the etched barrier is reduced to optimise the surface electric field and mobility of 2DEG. The electric field is reshaped by the etched AlGaN layer, featuring an extra electric field peak far away from the gate edge. The electric field peak near the gate is decreased effectively because of the extra electric field peak, which therefore improves the breakdown voltage (BV). The mobility of 2DEG is increased because of the low 2DEG concentration, which improves the output current (I DS). The experimental BV is improved from 152 V for the conventional structure to 620 V for etched AlGaN/GaN HEMTs because of the optimised surface electric field. The maximum output current (I max) is increased from 381 to 478 mA/mm. The trade-off between the BV and R on,sphas been improved to break the silicon limit. It is concluded that the gate-edge etching technique can significantly increase both BV and I DS for AlGaN/GaN HEMTs.
High sensitivity vanadium–vanadium pentoxide–aluminium metal–insulator–metal diode
- Author(s): Mohamed Abdel-Rahman ; Khaled Issa ; Muhammad F. Zia ; Mohammad Alduraibi ; Mohammad Siraj ; Amr Ragheb ; Saleh Alshebeili
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 680 –683
- DOI: 10.1049/mnl.2017.0728
- Type: Article
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This work reports on the fabrication of an improved sensitivity metal–insulator–metal (MIM) diode. They devise an asymmetric structure diode that cascades vanadium, vanadium pentoxide, and aluminium (V–V2O5–Al) thin film layers. The MIM diode is fabricated using electron-beam lithography, sputter deposition and metal liftoff techniques. X-ray photoelectron spectroscopy analysis is performed to determine the phase composition of the V2O5 insulating thin film. Electrical characterisation of the fabricated V–V2O5–Al shows a clear high sensitivity at −316 mV that reaches −8.52 V−1 with a dynamic resistance of 5.024 kΩ.
Approach to suppress ambipolarity and improve RF and linearity performances on ED-Tunnel FET
- Author(s): Bandi Venkata Chandan ; Sushmitha Dasari ; Shivendra Yadav ; Dheeraj Sharma
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 684 –689
- DOI: 10.1049/mnl.2017.0814
- Type: Article
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This work reports a dual metal bipolar gate-based electrically doped tunnel field-effect transistor (DMBG-ED-TFET) which overcomes the ambipolarity issue and gives improved radio frequency (RF) and linearity metrics. The formations of , drain and source regions in this device is performed by applying polarity biases at polarity gate (PG)-1 and PG-2 with 1.2 and −1.2 V. In DMBG-ED-TFET, the gate is alienated into three subdivisions and each subdivision named as tunnel gate (M1), BG (M2) and auxiliary gate (M3) with their respective work functions as , and , respectively. Finally, some existent applications were applied on a proposed device with different possible combinations (work function). Those different possible combinations of work function, the proposed device (DMBG-ED-TFET) gives superior results with , where is near to source region because to increase the current and is located near the drain region to overwhelm the ambipolarity. Additionally, the application of work function engineering on the proposed device results in improving the DC characteristics along with analogue/RF and linearity figure of merits (VIP3, IIP3 and IMD3) also discussed.
Effect of varying Indium concentration of InGaAs channel on device and circuit performance of nanoscale double gate heterostructure MOSFET
- Author(s): Kalyan Biswas ; Angsuman Sarkar ; Chandan Kumar Sarkar
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 690 –694
- DOI: 10.1049/mnl.2017.0884
- Type: Article
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The detailed numerical analysis is performed to study and evaluate the impact of Indium (In) concentrations of the Indium gallium arsenide (InGaAs) channel on different device performances of InGaAs/In phosphide double gate metal–oxide–semiconductor field-effect transistor using TCAD software. The RF/analogue figures of merits under investigation are transconductance (gm ), transconductance-to-current ratio (gm/I d), cut-off frequency (fT ), maximum frequency of oscillations (f max) etc. A cascode amplifier is then designed using the device under study and its voltage transfer characteristics and differential gain are plotted to estimate the device performance in circuits. It is seen that with higher Indium content, the analogue/RF performance of the device significantly improves.
Double trenches LDMOS with trapezoidal gate
- Author(s): Na Yuan ; Lijuan Wu ; Hang Yang ; Yue Song ; Limin Hu ; Bing Lei ; Yinyan Zhang
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 695 –698
- DOI: 10.1049/mnl.2017.0532
- Type: Article
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p.
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A novel double trenches lateral double diffused metal oxide semiconductor with trapezoidal gate (TGDT LDMOS) is proposed. One feature of the device is that two dielectric trenches which are equivalent to two field plates are introduced in the drift region. The two dielectric trenches not only modulate the body electric field to improve the breakdown voltage (BV) of the device but also assist to deplete the drift region to reduce the specific on-resistance (R on,sp). The other feature is the presence of the trapezoidal gate which increases the gate oxide thickness to reduce the capacitance of gate and drain (C GD). Thereby the charge between the gate and drain (Q GD) is reduced, so that the conduction loss of the device is decreased. Compared with the conventional LDMOS with trapezoidal gate and the single trench LDMOS with trapezoidal gate, the figure of merit (FOM = BV2/R on,sp) of the TGDT LDMOS is increased by 112.5 and 54.5%, respectively. Compared with the conventional double trenches LDMOS with rectangle gate, the FOM is similar, but the Q GD is reduced by 45.7%. Simultaneously, the feasible process steps of the TGDT LDMOS are given in this work.
Synthesis and characterisation of fluorescent and biocompatible hydroxyapatite nanoparticles with cerium doping
- Author(s): Wenjie Huang ; Zhou Mao ; Li Chen ; Yuling Chi ; Hao Jiang ; Bhahat Lawlley Zimba ; Guoxi Xiong ; Qingzhi Wu
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 699 –703
- DOI: 10.1049/mnl.2017.0729
- Type: Article
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In this work, the fluorescent hydroxyapatite nanoparticles (HA NPs) were synthesised by doping cerium (Ce) ions into the crystal structure of HA at different concentrations. The fluorescent property of the Ce-doped HA NPs was determined by the content of Ce doping. The results show that HA NPs with the Ce-doping content of 5% displayed the highest fluorescent emission peak near 380 nm at the excitation wavelength of 300 nm. The CCK-8 assay showed that no significant cytotoxicity was observed when the L929 cells were incubated with the fluorescent HA NPs with the Ce-doping content of 5% for 12 h at the dose lower than 0.1 mg/ml. Therefore, the fluorescent HA NPs could be used as a fluorescent probing for cellular imaging and antioxidant agent against oxidative stress-induced cell damages.
Tracking of square reference signals using internal model-based LQG robust controller for positioning of a micro-electro-mechanical systems micromirror
- Author(s): Jiazheng Tan ; Weijie Sun ; John Yeow
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 704 –708
- DOI: 10.1049/mnl.2017.0681
- Type: Article
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This work studies the Lorentz force-based polymer hard-magnetic micromirror for optical switch application. For this purpose, a robust control design is proposed, which is based on the linear quadratic gaussian method incorporating with the well-known internal model principle. The proposed scheme can simultaneously be easily implemented and it can improve the positioning performances and noise rejection ability. The effectiveness is verified by experimental results.
Biocompatibility and bioactivity behaviour of coelectrospun silk fibroin-hydroxyapatite nanofibres using formic acid
- Author(s): Sara Zadegan ; Bahman Vahidi ; Jhamak Nourmohammadi ; Nooshin Haghighipour
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 709 –713
- DOI: 10.1049/mnl.2018.0047
- Type: Article
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–713
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Appending hydroxyapatite (HAp) to non-osteogenic silk fibroin (SF) scaffolds is an undeniable fact about the bone tissue engineering. The present research aimed to fabricate the uniform coelectrospun SF-HAp composites with 1, 3 and 5 wt% of nano-particles using acid solution to access fibres with favourable mechanical strength simultaneous with the enhanced bone cell compatibility. SEM images displayed that the average diameter of nanofibres increased from 90 ± 12 in SF nanofibres to 227 ± 13 in SF-5%HAp. Meanwhile, the elastic modulus and breaking strain were equal to 63.4 ± 1.08 MPa and 2.57 ± 0.04, respectively, for SF-3% HAp which was significantly higher than the SF fibres. Bioactivity property was evaluated after immersion in simulated body fluid by the SEM/EDS analysis. The results, which were confirmed by XRD and FTIR, asserted calcium phosphate deposition after 7 days rather than the SF mats. Finally, the MTT assay, Alkaline Phosphatase (ALP) activity, calcium deposition and cell adhesion approved that the SF-HAp nano-composite could raise the cell viability and significantly enhance osteogenic differentiation and mineralisation process by increasing osteoblast cell migration and adhesion to the surface of nanofibres. In brief, it can be concluded that the SF-HAp nanofibres can be considered as the superlative candidates for application in the bone tissue engineering.
Simple, repeatable and low-cost SERS fibre probe for fluorochrome detection
- Author(s): Meijing Xia ; Hao Guo ; Jun Tang ; Chunming Li ; Rui Zhao ; Lei Wang ; Wenyao Liu ; Jiangtao Yang ; Jun Liu
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 714 –719
- DOI: 10.1049/mnl.2017.0740
- Type: Article
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A method for developing the spherical surface-enhanced Raman scattering (SERS) fibre probe is presented cladded with the silver nanoparticles to detect the fluorochrome molecular. By controlling the diameter of the fibre ball, the excellent SERS enhancement effect has been achieved up to about 105 due to the plasmonic silver nanoparticles, the coated parylene-C dielectric layer and the low-energy loss in the spherical resonant cavity. Meanwhile, the repeatability and stability of the fibre probe have been explored by coating the parylene-C with the error of 1%. It has proved an important superiority for potential commercial applications of this technique to detect the bio-molecular with the advantages of high sensitivity, high stability and low cost.
Synergistic effect of surface phase junction and surface defects on enhancing the photocatalytic performance of BiPO4
- Author(s): Xianyong Feng ; Peifang Wang ; Jin Qian ; Yanhui Ao ; Chao Wang ; Jun Hou
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 720 –724
- DOI: 10.1049/mnl.2017.0620
- Type: Article
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In this work, defective BiPO4 with surface phase junction (BPJ) was synthesised using a facile ball-milling method. The phase composition of BPJ was found to include monazite monoclinic BiPO4 and monoclinic BiPO4. Surface defects on BPJ could be controlled by changing ball-milling conditions. The optimal sample exhibited significantly enhanced photocatalytic performance compared with BiPO4 and BPJ under ultraviolet light irradiation. The enhancement of photocatalytic performance was due to the synergistic effect of the surface phase junction and surface defects, which significantly improved the separation and transfer efficiency of photogenerated charges.
Synthesis of porous silica materials with tunable morphologies and nanopore sizes using heterogemini surfactants
- Author(s): Xuanxian Wu ; Sili Yi ; Shuolin Li ; Linxi Hou
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 725 –727
- DOI: 10.1049/mnl.2017.0819
- Type: Article
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A series of heterogemini surfactants C16H33OCH2CH(OH)CH2N+(CH3)2C n H2n+1·Br– were used as the template to synthesise porous silica materials via a Stöber method. The influence of the alkyl chain length of heterogemini surfactants on the morphology of porous silica materials was studied. Porous silica materials were characterised by scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption analysis. Results showed that with the increase of alkyl chain length, the morphologies of porous silica materials gradually transform from sphere to sphere with cavity, sphere composed of vesicles, coral like and finally to lamella. Pore size of materials ranges from 1.17 to 3.93 nm. When the alkyl chain is short enough (n = 8 and 10), a hierarchical pore size distribution can be obtained. The possible formation mechanism of the porous silica materials has been discussed.
4-aminobenzensulphonate-assisted enhanced hydrophily of carbon nanotubes and simultaneous uniform dispersion of PtRu nanoparticles
- Author(s): Bohua Wu ; Jiajin Zhu ; Siyuan Yin ; Xue Li ; Jia Chu ; Shanxin Xiong
- Source: Micro & Nano Letters, Volume 13, Issue 5, p. 728 –731
- DOI: 10.1049/mnl.2017.0389
- Type: Article
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A 4-aminobenzensulphonate (p-ABS)-assisted strategy has been proposed to separate the aggregations of carbon nanotubes (CNTs) and deposit PtRu nanoparticles on them with holonomic graphitic structures. In this work, as an efficient dispersing agent, 0.5 wt% of p-ABS in isopropanol/water solution can drastically separate CNTs aggregations. Meanwhile, under the help of p-ABS, high dispersion of PtRu nanoparticles is anchored on CNTs surface with small average diameter (3.0 ± 0.5 nm). It is clear that p-ABS acts as dispersant, stabiliser and linker in the proposed strategy. The obtained PtRu/p-ABS-CNTs nanohybrids were applied as electrocatalysts for methanol oxidation and showed enhanced catalytic activity and stability. Due to the introduction of the amino (−NH2) and sulphonic acid (−SO3H) groups onto CNTs by non-covalent method, it ensures PtRu nanoparticles with the advantages of high dispersion, small particle size, locating in triple-phase zones to increase Pt utilisation and reduces the electrochemical corrosion of p-ABS-CNTs, which result in the improved catalytic performance. This work demonstrates an alternative approach to fabricate CNTs supported superior noble metal catalysts for broad applications in fuel cells and chemo/biosensors.
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- Author(s): Haijun Shen
- Source: Micro & Nano Letters, Volume 13, Issue 5, page: 732 –732
- DOI: 10.1049/mnl.2018.0207
- Type: Article
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Retracted: Kinetic resistance of carbon nanotubes in aqueous solution
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