检索结果-南通市图书馆

Mechanical properties of Al/a-C nanocomposite thin films synthesized using a plasma focus device

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第2期23卷 353-358页

作者： Z.A.Umar R.S.Rawat R.Ahmad A.K.kumar Y.Wang T.Hussain Z.Chen L.Shen Z.Zhang NSSE National Institute of EducationNanyang Technological University Department of Physics GC University Center for Advanced Studies in Physics (CASP) GC University School of Materials Science and Engineering Nanyang Technological University Institute of Materials Research and Engineering ASTAR (Agency for ScienceTechnology and Research)3 Research Link

The Al/a-C nanocomposite thin films are synthesized on Si substrates using a dense plasma focus device with alu- minum fitted anode and operating with CH4/Ar admixture. X-ray diffractometer results confirm the formation of metallic crystalline Al phases using different numbers of focus shots. raman analyses show the formation of D and G peaks for all thin film samples, confirming the presence of a-C in the nanocomposite thin films. The formation of Al/a-C nanocomposite thin films is further confirmed using X-ray photoelectron spectroscopy analysis. The scanning electron microscope results show that the deposited thin films consist of nanoparticles and their agglomerates. The sizes of th agglomerates increase with increasing numbers of focus deposition shots. The nanoindentation results show the variations in hardness and elastic modulus values of nanocomposite thin film with increasing the number of focus shots. Maximum values of hardness and elastic modulus of the composite thin film prepared using 20 focus shots are found to be about 10.7 GPa and 189.2 GPa, respectively.

关键词： dense plasma focus X-ray photoelectron spectroscopy field emission scanning electron micro- scope elastic modulus

Development of Cu-Exfoliated Graphite Nanoplatelets (xGnP) Metal Matrix Composite by Powder Metallurgy Route

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Graphene 2015年第4期4卷 91-111页

作者： Syed Nasimul Alam Lailesh kumar Nidhi Sharma Metallurgical and Materials Engineering Department National Institute of Technology Rourkela Rourkela India

In the present investigation the possibility of using exfoliated graphite nanoplatelets (xGnP) as reinforcement in order to enhance the mechanical properties of Cu-based metal matrix composites is explored. Cu-based metal matrix composites reinforced with different amounts of xGnP were fabricated by powder metallurgy route. The microstructure, sliding wear behaviour and mechanical properties of the Cu-xGnP composites were investigated. xGnP has been synthesized from the graphite intercalation compounds (GIC) through rapid evaporation of the intercalant at an elevated temperature. The thermally exfoliated graphite was later sonicated for a period of 5 h in acetone in order to achieve further exfoliation. The xGnP synthesized was characterized using SEM, HRTEM, X-ray diffraction, raman spectroscopy and Fourier transform infrared spectroscopy. The Cu and xGnP powder mixtures were consolidated under a load of 565 MPa followed by sintering at 850°C for 2 h in inert atmosphere. Cu-1, 2, 3 and 5 wt% xGnP composites were developed. Results of the wear test show that there is a significant improvement in the wear resistance of the composites up to addition of 2 wt% of xGnP. Hardness, tensile strength and strain at failure of the various Cu-xGnP composites also show improvement upto the addition of 2 wt% xGnP beyond which there is a decrease in these properties. The density of the composites decreases with the addition of higher wt% of xGnP although addition of higher wt% of xGnP leads to higher sinterability and densification of the composites, resulting in higher relative density values. The nature of fracture in the pure Cu as well as the various Cu-xGnP composites was found to be ductile. Nanoplatelets of graphite were found firmly embedded in the Cu matrix in case of Cu-xGnP composites containing low wt% of xGnP.

关键词： Powder Metallurgy Exfoliated Graphite Nanoplatelets (xGnP) Cu-Based Metal Matrix Composite Sliding Wear

Synthesis of Graphene Oxide (GO) by Modified Hummers Method and Its Thermal Reduction to Obtain Reduced Graphene Oxide (rGO)

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Graphene 2017年第1期6卷 1-18页

作者： Syed Nasimul Alam Nidhi Sharma Lailesh kumar Department of Metallurgical and Materials Engineering National Institute of Technology Rourkela Rourkela India

Over the span of years, improvements over various synthesis methods of graphene are constantly pursued to provide safer and more effective alternatives. Though the extraction of graphene through Hummers method is one of the oldest techniques yet it is one of the most suitable methods for the formation of bulk graphene. Graphene can be obtained in the form of reduced Graphite oxide, sometimes also referred as Graphene oxide. The effectiveness of this oxidation process can be evaluated by the magnitude of carbon/oxygen ratio of the obtained graphene. Here, graphene oxide (GO) was prepared by oxidizing the purified natural flake graphite (NFG) by a modified Hummers method. The attempts have been made to synthesize GO having few layers by using a modified Hummers method where the amount of NaNO3 has been decreased, and the amount of KMnO4 is increased. The reaction has been performed in a 9:1 (by volume) mixture of H2SO4/H3PO4. This modification is successful in increasing the reaction yield and reducing the toxic gas evolution while using a varied proportion of KMnO4 and H2SO4 as those required by Hummers method. A new component of K2S2O8 has been introduced to the reaction system to maintain the pH value. Reduced graphene oxide (rGO) was thereafter extracted by thermal modification of GO. Here, GO has been used as a precursor for graphene synthesis by thermal reduction processes. The results of FTIR and raman spectroscopy analysis show that the NFG when oxidized by strong oxidants like KMnO4 and NaNO3, introduced oxygen atoms into the graphite layers and formed bonds like C=O, C-H, COOH and C-O-C with the carbon atoms in the graphite layers. The structure and morphology of both GO and rGO were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy, raman spectroscopy, Brunauer-Emmett-Teller (BET) surface area

关键词： Graphene Oxide (GO) Reduced Graphene Oxide (rGO) Exfoliated Graphite Nanoplatelets (xGnP)

Economics of Yield and Production of Alkaloid of Withania somnifera(L.) Dunal

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

American Journal of Plant Sciences 2013年第10期4卷 2023-2030页

作者： Atul kumar Shrivastava Pankaj K. Sahu Directorate of Research Services Jawarharlal Nehru Krishi Viswavidylaya Jabalpur India Dr. C.V. raman University Bilaspur India.

The yield parameters and cost economics of Withania somnifera were studied using Integrated Nutrient Management (INM) treatments. Withania somnifera is cultivated in around 10,780 ha with a production of 8429 tones in India. The annual demand of this herb increased from 7028 tones (2001-2002) to 9127 tones (2004-2005). The field experiment was conducted at the research farm of Department of Plant Physiology, College of Agriculture, Jabalpur during Kharif season of 2008-2009 (1st year) and 2009-2010 (2nd year), whereas the laboratory work was carried out in Quality Laboratory, College of Agriculture, Jabalpur. The soil of experimental field was sandy loam in texture with pH 7.5, EC 0.18 dsm-1 having good drainage. Soil analysis revealed that available nitrogen was low (202.0 kg·ha-1) whereas available phosphorus (16.25 kg·ha-1) and potassium (236.0 kg·ha-1) were in the medium range. The present paper shows how to determine the economics of varying INM treatments. Cultivation of W. somnifera in India is gaining popularity among farmers;however, due to poor soil fertility, and costly chemical fertilizers and pesticides its production is not economical or profitable.

关键词： Withania somnifera INM Yield Alkaloid Economics

Synthesis, Characterization, Optical and Transport Properties of BaSnO3Synthesized by Wet Chemical Route

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Materials Sciences and Applications 2018年第1期9卷 92-110页

作者： Rakesh Kurre Sharmila Bajpai Parmendra kumar Bajpai Department of Pure & Applied Physics Guru Ghasidas Vishwavidyalaya Bilaspur India

Alkaline earth stannates have renewed attention as potential materials for gas sensing, transparent conducting oxides and ceramic capacitor applications. A noble wet chemical route is chosen to synthesize BaSnO3 powders having micron size grains. Problems related to uneven grains and poor densification in conventional solid state route have been overcome in the present method. X-ray diffraction data confirms the single phase formation without any secondary phase having cubic perovskite structure (S.G. Pm-3m). The estimated lattice parameter is ≈4.11933Åand percentage density is ≈90%. The microstructure probed by scanning electron micrograph reveals almost homogeneously distributed particles having random shape with some porosity. Phonon modes in FT-IR and raman spectra confirm the local symmetry distortion. The DC conductivity at 200°C approaches almost 2 × 10-2 (Ω-cm)-1, which is almost of the same order as that observed in perovskite based electronic conductors. DC and a.c. electrical conductivity of the material follow Mott’s variable range hopping at low temperature and Arrhenius type thermally activated process at elevated temperatures. Evidence of small polar on formation is also verified. Optical band gap estimated from absorption data is ≈2.94 very close to the reported value. Composition prepared through the noble wet chemical route has high electrical conduction and suitable for gas sensing applications.

关键词： X-Ray Diffraction raman Spectra Variable Range Hopping Phonons

FTIR and raman Studies of Cellulose Fibers of Luffa cylindrica

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Composite Materials 2015年第1期5卷 5-10页

作者： Chhatrapati Parida Sarat kumar Dash Chinmay Pradhan Depatment of Physics Orissa University of Agriculture and Technology Bhubaneswar India Department of Education in Science and Mathematics National Council of Educational Research and Training Bhubaneswar India Post Graduate Department of Botany Vani Vihar Utkal University Bhubaneswar India

In view of biomedical applications of cellulose fibers in orthopedics, dentistry and reconstructive surgery, Luffa cylindrica (LC), a local forest product of Orissa, India, has been used for preparation of alkali treated LC fiber modified with calcium carbonate and calcium phosphate separately by following standard procedures. FTIR and raman spectra were obtained for these samples at wavelength range 500 - 4000 cm–1 and 300 - 3000 cm–1 respectively. Lattice structures of cellulose i.e., crystalline cellulose and amorphous cellulose were detected using raman spectroscopy and discussed. The property of cellulose such as its degree of crystallinity was determined from intensity of FT IR peaks and was found to be 74.12%. The presence of calcite and hydroxy apatite, polymorphs of calcium carbonate and calcium phosphate respectively were confirmed in the treated modified LC fibers which can be used as bioactive materials.

关键词： Degree of Crystallinity Hydroxy Apatite FTIR LC Fibers raman Spectra

Laser Induced Breakdown of Poly （Methyl Methacrylate （PMMA）） in Air

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Physical Science and Application 2014年第7期4卷 426-429页

作者： Archana Kushwaha Indrajeet kumar Alika Khare Laser and Photonics Lab Department of Physics lndian Institute of Technology Guwahati Guwahati-781039 Assam lndia

In the present work, Laser induced Breakdown spectroscopy technique is used to investigate the laser induced plasma of PMMA in air. The optical emission of PMMA plasma is found quite intense and dominated by vibrational band of CN molecules （violet band, B^2∑^＋ - X^2∑^＋） at 388.4 nm. The temporal response of the CN band emission is studied and found decay time 22 ns. The low decay time and small laser spot （34 × 32 μm^2） conf＇n-ms good thermal stability of PMMA. To get structural fingerprint of PMMA, raman spectrum is recorded prior to the exposure to laser. Several sharp raman peaks have been observed along with a very intense peak at 2,957 cm1 attributed to C-H stretching vibration. Post exposure raman spectrum is also recorded to analyze the heating effect and re-deposition of ablated material.

关键词： Laser induced breakdown PMMA plasma CN band raman spectrum.

A New Insight in the Physical and Photoelectrochemical Properties of Molybdenum Disulfide Alpha-Hematite Nanocomposite Films

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

American Journal of Analytical Chemistry 2017年第8期8卷 523-539页

作者： Hussein Alrobei Ashok kumar Manoj K. Ram Department of Mechanical Engineering University of South Florida Tampa FL USA Clean Energy Research Center University of South Florida Tampa FL USA

The alpha (α)-hematite (Fe2O3) as photoanode has been used for photoelectrochemical applications due to low bandgap, low cost, high chemical stability, nontoxicity, and abundance in nature. The doping with various transition metals, formation of nanostructured and nanocomposite of α-Fe2O3 have been attempted to enrich the carrier mobility, surface kinetics and carrier diffusion properties. The manuscript is an attempt to improve the photoelectrochemical properties of α-Fe2O3 by formation of nanocomposite with dichalcogenide (molybdenum disulfide (MoS2) nanomaterials. The nanocomposite of MoS2-α-Fe2O3 have been synthesized by varying the amount of MoS2 in sol-gel synthesis process. The nanocomposite MoS2-α-Fe2O3 materials were characterized using UV-visible, FTIR, SEM, X-ray diffraction, raman and particle analyzer. The photoelectrochemical properties were investigated using cyclic voltammetry and chronoamperometry studies. The optical and structural properties of MoS2-α-Fe2O3 nanocomposite have been found to be dependent on MoS2 doping. The band gap has shifted whereas;the structure is more prominent as flower-like morphology, which is a result of doping of MoS2. The photocurrent is more pronounced with and without light exposition to MoS2-α-Fe2O3 based electrode in photoelectrochemical cell. We have understood the photoelectrochemical water splitting using nanocomposite α-Fe2O3-MoS2 through schematic representation based on experimental results. The enhanced photoelectrochemical properties of nanocomposite α-Fe2O3-MoS2 films have been observed as compared to pristine α-Fe2O3 and transition metal doped α-Fe2O3 nanostructured films.

关键词： Water Splitting Photoelectrochemical Hematite (α-Fe2O3) MoS2 Nanocomposite

Study of Structural and Dielectrical Properties of Lead Free Polycrystalline Electro Ceramics Ba5CaTi2Nb8O30(BCTN) for Microwave Tunable Device Applications

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Materials Sciences and Applications 2018年第1期9卷 55-67页

作者： Shilpi Jindal Sheela Devi Ajay Vasishth Gagan kumar Department of Physics Chandigarh University Mohali Punjab India Department of Applied Sciences MSIT New Delhi India Department of Applied Sciences Chandigarh Engineering College Punjab India

Tungsten bronze structure ceramics have found vital potential in many applications such as actuators, transducer, electro-optic, ferroelectric random access memory and microwave devices. These type ceramics are extensively used in many industrial applications due to their spontaneous polarization and well-known for its high dielectric constant, low dielectric loss, low leakage current density, good thermal stability and high piezoelectric coefficient. In present work, Ba5CaTi2Nb8O30 (BCTN) has been synthesized first time through solid state reaction method. The microstructures, dielectric, ferroelectric, ferromagnetic and raman spectra have been investigated by means of X-ray diffraction, Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), LCR meter, P-E loop tracer, VSM and raman spectrometer respectively. X-ray dif-fraction study revealed the formation of single phase tetragonal structure with space group P4bm. The crystallite size was observed to be in the range 14.4 nm. Detailed dielectric properties of BCTN compound as function of temperature at different frequencies show that sample exhibits diffuse type transition at curie temperature 316°C. The P-E and M-H studies confirmed the coexistent ferroelectricity and magnetism at room temperature.

关键词： Ceramic X-Ray Diffraction Scanning Electron Microscopy raman Spectrometer