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  • 1
    Publication Date: 2018-07-02
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): Ashish Ravalia, Bharat Kataria, Savan Katba, Sadaf Jethva, Megha Vagadia, K. Asokan, Sanjeev Gautam, Keun Hwa Chae, D.G. Kuberkar We report the effect of electronic excitations induced modifications in the ferroelectric polarization in BiFeO 3 (BFO) multiferroic films grown on 0.2% Nb doped SrTiO 3 (SNTO) substrates by pulsed laser deposition. The BFO/SNTO films were irradiated with 200 MeV Ag +15 ions with ion fluences of 5 × 10 10 to 5 × 10 12 ions/cm 2 and characterized by using X–ray diffraction (XRD), atomic force microscopy (AFM), ferroelectric polarization and near-edge X-ray absorption fine structure (NEXAFS) measurements. The XRD and AFM results show the creation of structural defects and oxygen vacancies by ion irradiation. Such defects induced enhancement in structural strain and reduction in mobility of charge carriers leading to the improvement in ferroelectric behaviour in BFO films. In addition, the local electronic structures investigated using NEXAFS studies reveal the significant change in spectral features suggesting the role of Bi-O and Fe-O hybridizations that modifies the ferroelectric behaviour of BFO films. These results are used to understand the mechanism.
    Print ISSN: 0042-207X
    Electronic ISSN: 1879-2715
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 2
    Publication Date: 2018-07-02
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): Chander Prakash, Sunpreet Singh, Kartikey Verma, Sarabjeet S. Sidhu, Subhash Singh This paper presents an investigation of design and development of low elastic modulus porous biodegradable Mg-Zn-Mn-HA composite for orthopedic applications via mechanical alloying and spark plasma sintering (MA-SPS) technique. The effect of MA-SPS process parameters like milling time, sintering temperature and sintering pressure have been studied on the structural porosity, elastic modulus and hardness of as-synthesized composite. The percentage of structural porosity was determined by Archimedes method and the elastic modulus and hardness of as-synthesized alloy were measured by the nano-indentation method. HA compound induced composite not only refined the grain but also enhanced porosity, which favoured osseointergation. The microstructure examination of the MA-SPS synthesized composite reveals the formation of high degree of structural porosity (15–25%), witnessed at low alloying time and high temperature. Sintering pressure enables pores reduction and induces an additional driving force for the compaction and sintering temperature assists the powder particles to coalesce, which subsequently reduces the porosity, densified the compact, and enhanced the mechanical properties. XRD pattern analysis confirmed the formation of MgCaO, β-TCP, Mn-CaO, and Ca-Mg-Zn phases, enhanced mechanical properties and corrosion characteristics. The degradation rate of Mg-Zn-Mn-HA alloy was reduced from 1.98 mm/year to 0.97mm/year by the alloying of HA elements.
    Print ISSN: 0042-207X
    Electronic ISSN: 1879-2715
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 3
    Publication Date: 2018-06-30
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): S. Ben Ameur, H. Bel hadjltaief, A. Barhoumi, B. Duponchel, G. Leroy, M. Amlouk, H. Guermazi ZnO and SnO 2 thin films were deposited on glass and Polyetherimide (PEI) flexible substrates by spray pyrolysis deposition at low temperature (250 °C). The structural characterization by X-ray diffraction (XRD) reveals that PEI promotes the crystallization of ZnO and SnO 2 thin films while the films deposited on glass substrate are amorphous. The physical investigations show that ZnO/PEI and SnO 2 /PEI have a good crystalline quality and high transparency in visible range (T>80%). Their gap energies are calculated from absorbance data (3.3 eV for ZnO and 3.72 eV for SnO 2 ). Furthermore, the surface properties are investigated by atomic force microscopy and contact angle measurements. It is found that the ZnO/PEI film has a higher surface roughness (RMS = 20.20 nm ± 0.62 nm) compared to SnO 2 /PEI (RMS = 5.41 nm ± 0.16 nm). The metal oxides (ZnO and SnO 2 ) catalysts exhibit excellent photodegradation activities under UV irradiation up to 80%. The highest activity was observed for ZnO thin films because it exhibits smaller gap energy. Furthermore, both samples show excellent photocatalytic stability.
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    Electronic ISSN: 1879-2715
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 4
    Publication Date: 2018-06-29
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): Nagaraj P. Shetti, Deepti S. Nayak, Shweta J. Malode In the current research, nanoclay particles modified carbon paste surface employed to determine sunset yellow (SY), a well-known azo food dye in nano level. With several astonishing characteristics such as strong adsorption, large surface area, and simple surface modification, the modifier grabbed some interest. The surface features of the modifier were premeditated by SEM (Scanning electronic microscopy) and XRD (X-ray diffraction) analysis. Unlike other techniques adopted for the electro oxidation study. A tremendous electrocatalytic behavior of the nanoclay modified electrode was explored towards the dye oxidation and a linear vibrant relationship in 0.001 μM–0.1 μM range with a LOD value of 0.2 nM. The main practical applicability of the fabricated sensor was explored by determining the dye in tablets, food materials including biological fluids. The low detection limit with good sensitivity, stability and specificity makes the modified sensor valuable for the entire analysis of SY. Graphical abstract
    Print ISSN: 0042-207X
    Electronic ISSN: 1879-2715
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 5
    Publication Date: 2018-06-29
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): Jiajie Zhang, Yong Zheng, Wei Zhou, Guotao Zhang, Zheng Ke, Zuowei Dong, Ping Feng Six series of cermet samples with Cr contents between 0 and 12.5 wt.% in 2.5 wt.% increments were prepared by vacuum sintering. The transverse rupture strength (TRS), hardness (HRA) and fracture toughness (K 1C ) were also measured. It was discovered that the grain size was affected by the Cr content. As the Cr addition increased, the average grain size and aspect ratio of the Mo 2 FeB 2 hard phase decreased, while the lattice constant ratio c/a increased. Consequently, the particle morphology gradually transformed from elongated to nearly equiaxed. The transverse rupture strength and hardness of the cermets firstly increased and following decreased slightly as the Cr content increased, while the fracture toughness gradually decreased. The cermets with 10 wt.% of Cr addition exhibited the lowest grain size. The cermets with 10 wt.% of Cr addition demonstrated the TRS, hardness and fracture toughness values of 2124.1 MPa, 89.0HRA and 23.8 MPa m 1/2 , respectively.
    Print ISSN: 0042-207X
    Electronic ISSN: 1879-2715
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 6
    Publication Date: 2018-06-22
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): Xiaoming Gao, Jiayi Sun, Yanlong Fu, Dong Jiang, Desheng Wang, Lijun Weng, Ming Hu The goal of this paper was to investigate the structural/mechanical properties of arc-ion-plated Ti film deposited at ultralow temperature (166 K, LT-Ti film) and its effect as an interlayer on the wear resistance of sputtered WS 2 film. The results revealed that the LT-Ti film mainly exhibited ω-phase structure due to the insufficient mobility of Ti adatoms at LT surface, while the α-phase was predominated in the Ti film deposited at room temperature (RT-Ti film). The LT-Ti film showed a higher hardness than the RT-Ti film as well as the better toughness and film-substrate adhesion on steel substrates. The wear resistance of sputtered WS 2 film could be significantly improved by employing the Ti films as its interlayer, especially for the LT-Ti film.
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    Electronic ISSN: 1879-2715
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 7
    Publication Date: 2018-06-21
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): S. Iwan, J.L. Zhao, S.T. Tan, X.W. Sun We have synthesized ZnO tubes, without any catalyst, on Al 2 O 3 (001) substrates by metal organic chemical vapor deposition (MOCVD) at different growth temperatures, pressures and Zn-O ratios. The results confirm that the growth temperature, reactor pressure and Zn-O ratio play important roles in the formation of hexagonal ZnO tubes. Scanning electron microscopy (SEM) images indicated that, at a growth temperature of 500 °C, reactor pressure of 75 Torr and Zn-O ratio of 10/75 are an appropriate condition to obtain hexagonal and well-aligned ZnO tubes. High-resolution, double crystal XRD analysis shows a symmetric ω-scan rocking curve, with a full width at half maximum (FWHM) of 1.1°. It confirms the ZnO tubes have highly c-axis orientation on Al 2 O 3 substrate. Subsequently, room temperature photoluminescence (PL) studies confirm that the enhancement of UV emissions from ZnO tubes is due to increasing Zn-O ratios.
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 8
    Publication Date: 2018-06-20
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): Chaitanya B. Hiragond, Pawan K. Khanna, Priyesh V. More In the present work, we first synthesized widely used conducting polymers like polythiophene (PTh), polypyrrole (PPy) and polyaniline (PANI) by oxidative coupling method. Later, we have in-situ grown cadmium sulfide (CdS) quantum dots (QDs) in presence of these conducting polymers to form CdS/polythiophene (CdS/PTh), CdS/polypyrrole (CdS/PPy) and CdS/polyaniline (CdS/PANI) hybrid nanocomposites. All characterization techniques confirm the formation of hybrid nanocomposites while also highlights the interaction of CdS with conducting polymers. Thereafter, as synthesized conducting polymers and their hybrid nanocomposites were employed as photocatalyst for degradation of methylene blue (MB) dye under direct sun light (light intensity = 75000–90000 Lux). Here, CdS plays a key role to enhance the photocatalytic activity of overall composite due to effective charge transfer with these conducting polymers. The in-depth comparative study of photocatalytic activity was performed for these hybrid nanocomposites and the effectiveness with respect to stability is reported. The role of CdS QDs as sensitizer is proposed on the basis of synergetic effect between CdS and PTh, PPy or PANI polymers. Graphical abstract
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 9
    Publication Date: 2018-06-20
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): Zahra Jedi-Soltanabadi, Mahmood Ghoranneviss, Zohreh Ghorannevis, Hossein Akbari Anatase Nitrogen-doped Titanium Dioxide (Nitrogen-doped TiO 2 ) nanotubes were grown via an anodization process in an ethylene-glycol based electrolyte solution containing ammonium fluoride (NH 4 F) and different water contents (2–4 vol%). These electrolyte solutions act as the dopants sources of Nitrogen in anodic TiO 2 nanotubes. The influence of different water content of electrolyte solution on physical properties of the Nitrogen-doped TiO 2 nanotubes was studied. It was observed that the diameter of the Nitrogen-doped TiO 2 nanotubes was increased by the water content increasing of the electrolyte solution. Also, the Nitrogen-doped TiO 2 nanotubes which grown in the electrolyte solution with 3 vol% water content had maximum length. An energy dispersive X-Ray analysis (EDX) revealed that the TiO 2 nanotubes were heavily doped with Nitrogen. UV–Vis diffuse reflectance spectroscopy (DRS) and Photoluminescence (PL) measurements showed that the Nitrogen-doped TiO 2 nanotubes had narrow band gap energy (lower than 3 eV).
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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  • 10
    Publication Date: 2018-06-20
    Description: Publication date: September 2018 Source: Vacuum, Volume 155 Author(s): Lesley J. Beyers, Amy Van den Bulck, Bart Blanpain The common procedure to calculate vapour–liquid equilibrium (VLE) from an ideal gas and activity coefficient model is evaluated. The reliability of these calculations is assessed through a quantification of the uncertainty in the thermodynamic data of Ag–Pb and Au–Pb binary alloys and propagation of this uncertainty in the calculation of a prediction interval for the vapour–liquid equilibrium results. The advantage of this methodology is that all calculated results include an uncertainty interval, which permits an assessment of the impact of the uncertainty in the thermodynamic data and allows for the validation of VLE diagrams with experimental data to be done on a quantitative basis.
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
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