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Synthesis of Aligned ZnO Nanorod Array on Silicon and Sapphire Substrates by Thermal Evaporation Technique

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Journal of Materials Science & Technology 2011年第8期27卷 701-706页

作者： K.M.K. Srivatsa Deepak Chhikara M. senthil kumar Materials Physics and Engineering Division National Physical Laboratory Council of Scientific & Industrial Research (CSIR) Physics of Energy Harvesting Division National Physical Laboratory Council of Scientific & Industrial Research (CSIR)

High density ZnO nanorods were grown by thermal evaporation of Zn powder at 700℃ on Si （100） and sapphire （0001） substrates at atmospheric pressure without adding any catalyst. The nanorods were characterizated in terms of their structural and optical properties. The nanorods grown on Si have a diameter of 350-400 nm and a length of 1.2 μm while those on sapphire have a diameter of 600-800 nm and a length of 2.5 μm. During the structural characterization, it is noticed that the rods grow along the （0002） plane with perfect hexagonal facet. The room temperature photoluminescence spectrum showed a strong UV emission peak at 385 nm with a weak green band emission, which confirms that nanorods have good optical properties. It is observed that the oxygen partial pressure plays an important role to control the shape and size of the nanorods in thermal evaporation growth technique.

关键词： Thermal evaporation technique ZnO nanorods X-ray diffraction Photoluminescence

The nonlinear optical properties of a magneto-exciton in a strained Ga_(0.2)In_(0.8)As/GaAs quantum dot

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Chinese Physics B 2013年第10期22卷 479-485页

作者： N.R.senthil kumar A.John Peter Chang Kyoo Yoo Department of Physics SBM College of Engineering and Technology Department of Physics Govt.Arts CollegeMelur-625 106MaduraiIndia Center for Environmental Studies/Green Energy Center Deptartment of Environmental Science and EngineeringCollege of EngineeringKyung Hee UniversitySeocheon-dong 1Giheung-guYongin-SiGyeonggi-Do446-701South Korea

The magnetic field-dependent heavy hole excitonic states in a strained ***/GaAs quantum dot are investi- gated by taking into account the anisotropy, non-parabolicity of the conduction band, and the geometrical confinement. The strained quantum dot is considered as a parabolic dot of InAs embedded in a GaAs barrier material. The dependence of the effective excitonic g-factor as a function of dot radius and the magnetic field strength is numerically measured. The interband optical transition energy as a function of geometrical confinement is computed in the presence of a mag- netic field. The magnetic field-dependent oscillator strength of interband transition under the geometrical confinement is studied. The exchange enhancements as a function of dot radius are observed for various magnetic field strengths in a strained ***/GaAs quantum dot. Heavy hole excitonic absorption spectra, the changes in refractive index, and the third-order susceptibility of third-order harmonic generation are investigated in the Gao.2Ino.8As/GaAs quantum dot. The result shows that the effect of magnetic field strength is more strongly dependent on the nonlinear optical property in a low-dimensional semiconductor system.

关键词： oscillator strength exciton quantum dot

Synthesis,characterization and sintering behavior influencing mechanical,thermal and physical properties of pure cordierite and cordierite-ceria

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Journal of Advanced Ceramics 2015年第1期4卷 22-30页

作者： Marikkannan senthil kumar Ayyasamy ELAYA PERUMAL T.R.VIJAYARAM School of Mechanical Building and Sciences VIT UniversityChennai-600127Tamil Nadu StateIndia Department of Mechanical Engineering Anna UniversityChennai-600025Tamil Nadu StateIndia

The study of cordierite ceramic is the need of the hour in present technological world for various advanced engineering ***,which has relatively poor mechanical properties,has induced the use of various dopants to study the improvement in mechanical *** of seeking new materials with good mechanical properties has revived the research on ceria doped *** research conducted on pure cordierite and ceria doped cordierite ceramics has investigated the results of characterization and studied their *** cordierite and cordierite-ceria(CeO_(2))composite ceramics synthesized for various stoichiometric composition(5-20 wt%)were compacted at 240 MPa and sintered between 600℃and 1350℃for 3 *** characterization techniques used in this study were X-ray diffraction(XRD),thermogravimetric(TG)analysis and Fourier transform infrared(FTIR).The density was calculated using the Archimedes *** of the ceria addition on cordierite’s mechanical properties such as hardness,flexural strength and fracture toughness and on thermal properties as thermal expansion was *** results confirmed the presence of cordierite and ceria in the samples heat treated at 1350℃.Results of FTIR and TG analyses revealed the formation of cordierite and the effect of ceria *** mechanical properties studied were found to be encouraging and confirmed the suitability of cordierite-ceria as an alternate material for cordierite.

关键词： cordierite ceria(CeO_(2)) temperature phase transformation properties

Synthesis methods of functionalized nanoparticles:a review

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Bio-Design and Manufacturing 2021年第2期4卷 379-404页

作者： Niyou Wang Jerry Ying Hsi Fuh S.Thameem Dheen A.senthil kumar Department of Mechanical Engineering National University of Singapore9 Engineering Drive 1#07-08 Block EASingapore 117575Singapore Department of Anatomy National University of Singapore4 Medical DriveMD10YLLSoMSingapore 117594Singapore

With the recent advancement in nanotechnology,nanoparticles(NPs)offer an ample variety of smart functions than conventional materials in various *** compared to larger particles,NPs possess unique characteristics and excellent abilities,such as low toxicity,chemical stability,surface functionality,and *** advantageous properties allow them to be widely utilized in many applications,including biomedical applications,energy applications,IT applications,and industrial *** order to fulfill the increasing demands of NP applications,existing NP synthesis methods need to be improved based on the requirements of different applications to further their usage.A comprehensive understanding of the relationships between synthesis parameters and properties of NPs can help us better fine-tune them with designed properties and minimal *** review paper will discuss the commonly used synthesis methods of functionalized NPs,as well as future directions and challenges to develop various synthesis methods further.

关键词： Nanoparticles Single synthesis methods Biosynthesis methods Combined synthesis methods Processing parameters

A novel,green 1-glycyl-3-methyl imidazolium chloride-copper(Ⅱ) complex catalyzed C-H oxidation of alkyl benzene and cyclohexane

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Chinese Chemical Letters 2012年第6期23卷 681-684页

作者： Parasuraman Karthikeyan Pundlik Rambhau Bhagat S.senthil kumar Organic Chemistry Division School of Advanced SciencesVIT UniversityVellore 632 014India

A variety of alkyl-arenes and cyclohexane were converted to the corresponding ketones with NaC10 as the oxidant in the presence of 1-glycyl-3-methyl imidazolium chloride--copper（II） complex. This method contains simplified product isolation and catalyst recycling, affording benzylic C-H oxidation of alkyl-arenes imparting high yield of ketones. Furthermore, complex could be reused seven times without a significant loss of its catalytic activity.

关键词： Copper Alkane Ionic liquid Room temperature

Effect of Oxygen Admittance Temperature on the Growth of ZnO Microcrystals by Thermal Evaporation Technique

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Journal of Materials Science & Technology 2012年第4期28卷 317-320页

作者： K.M.K. Srivatsa Deepak Chhikara M. senthil kumar Physics of Energy Harvesting Division National Physical Laboratory Council of Scientific & Industrial Research (CSIR) New Delhi 110012 India

Hexagonally well-faceted microcrystals of ZnO have been grown by thermal evaporation of Zn powder in oxygen ambient at 700℃ under atmospheric pressure. It has been observed that the properties （size and quality） of ZnO microcrystals have a strong dependence on the reactor temperature at which the oxygen gas is admitted into the growth zone. The microcrystals grown with oxygen admittance at 450℃ have a length of 1 μm and a diameter of 0.75 μm while that grown with oxygen admittance at 600 ℃ have a length of 1.5-2 μm and a diameter of 1 μm. Room temperature photoluminescence spectra show a ultraviolet （UV） emission peak at 385 nm with a green band emission at around 500 nm. The UV-to-green band emission ratio for the microcrystals grown with oxygen admittance at 450℃ is observed to be 1.25 and the ratio decreases to 0.45 for the sample grown with oxygen admittance at 600℃.

关键词： ZnO microcrystals Thermal evaporation Scanning electron microscopy Transmission electron microscopy Room temperature photoluminescence

Synthesis of Anatase Titania Nanostructures at Room Temperature by PECVD Technique

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Journal of Materials Science & Technology 2011年第8期27卷 696-700页

titania nanostructures have been synthesized at room temperature by plasma enhanced chemical vapor deposition （PECVD） process on silicon （100） substrates using titanium tetraisopropoxide [Ti（OC3H7）4, TTIP] vapor, argon and oxygen mixtures under various deposition pressures. The deposited titania has been characterized for its structural, morphological and chemical composition by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray （EDX） spectroscopy and Fourier transform infrared （FTIR） spectroscopy recordings. With the variation of deposition pressure, titania assumes various nanostructures viz. nanocrystals, nanoparticles, noanorods and comb-like structure. EDX and FTIR measurements show that the deposited titania is of high chemical purity. The possible growth mechanisms for the observed titania nanostructures have been discussed.

关键词： Nanostructures Plasma enhanced chemical vapor deposition Anatase titania

Growth of ZnSe∶Mn Nanocrystals from Vapour Phase

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Journal of Rare Earths 2006年第z1期24卷 111-114页

作者： O senthil kumar K Balkis Ameen S Soundeswaran T Rajasekharan R Dhanasekaran Crystal Growth Centre Anna University Chennai-600 025 India Defence Metallurgical Research Laboratory Hyderabad-500 058 India Crystal Growth Centre Anna University Chennai-600 025 India Defence Metallurgical Research Laboratory Hyderabad-500 058 India Crystal Growth Centre Anna University Chennai-600 025 India

ZnSe∶Mn nanocrystals were grown by chemical vapour transport method using the matrix of SiO2 aerogels. The cubic structure of the nanocrystals was confirmed by powder X-ray diffraction (XRD) and electron diffraction (ED) studies. The size of the crystals was observed using transmission electron microscope (TEM). The oxidation state of Mn in ZnSe nanocrystal was found using electron spin resonance (ESR) spectrum. The room temperature luminescence measurements show the peaks corresponding to both bandgap of the material and Mn in ZnSe.

关键词： Ⅱ-Ⅵ semiconductors nanocrystalline materials electron spin resonance

Performance, emission and combustion characteristics of CI engine fuelled with diesel and hydrogen

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Frontiers in Energy 2015年第4期9卷 486-494页

作者： R. senthil kumar M. LOGANATHAN E. James GUNASEKARAN Department of Mechanical Engineering Annamalai University Chi- dambaram 608002 India

Hydrogen （H2） is being considered as a primary automotive fuel and as a replacement for conventional fuels. Some of the desirable properties, like high flame velocity, high calorific value motivate us to use hydrogen fuel as a dual fuel mode in diesel engine. In this experiment, hydrogen was inducted in the inlet manifold with intake air. The experiments were conducted on a four stroke, single cylinder, water cooled, direct injection （DI）, diesel engine at a speed of 1500r/min. Hydrogen was stored in a high pressure cylinder and supplied to the inlet manifold through a water-and-air-based flame arrestor. A pressure regulator was used to reduce the cylinder pressure from 140 bar to 2 bar. The hydrogen was inducted with a volume flow rate of 41 pm, 61 pm and 81 pm, respectively by a digital volume flow meter. The engine performance, emission and combustion parameters were analyzed at various flow rates of hydrogen and compared with diesel fuel operation. The brake thermal efficiency （BTE） was increased and brake specific fuel consumption （BSFC） decreased for the hydrogen flow rate of 81 pm as compared to the diesel and lower volume flow rates of hydrogen. The hydrocarbon （HC） and carbon monoxide （CO） were decreased and the oxides of nitrogen （NOx） increased for higher volume flow rates of hydrogen compared to diesel and lower volume flow rates of hydrogen. The heat release rate and cylinder pressure was increased for higher volume flow rates of hydrogen compared to diesel and lower volume flow rates of hydrogen.

关键词： hydrogen brake thermal efficiency crankangle compressed ignition (CI)