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Sample records for carbon nitride thin

  1. Anisotropies in magnetron sputtered carbon nitride thin films

    Science.gov (United States)

    Hellgren, Niklas; Johansson, Mats P.; Broitman, Esteban; Hultman, Lars; Sundgren, Jan-Eric

    2001-04-01

    Carbon nitride CNx (0⩽x⩽0.35) thin films, deposited by reactive dc magnetron sputtering in Ar/N2 discharges have been studied with respect to microstructure using electron microscopy, and elastic modulus using nanoindentation and surface acoustic wave analyses. For growth temperature of 100 °C, the films were amorphous, and with an isotropic Young's modulus of ˜170-200 GPa essentially unaffected by the nitrogen fraction. The films grown at elevated temperatures (350-550 °C) show anisotropic mechanical properties due to a textured microstructure with standing basal planes, as observed from measuring the Young's modulus in different directions. The modulus measured in the plane of the film was ˜60-80 GPa, while in the vertical direction the modulus increased considerably from ˜25 to ˜200 GPa as the nitrogen content was increased above ˜15 at. %.

  2. [FTIR spectroscopic studies of inner stress on boron carbon nitride thin films].

    Science.gov (United States)

    Wang, Yu-Xin; Zheng, Ya-Ru; Song, Zhe; Feng, Ke-Cheng; Zhao, Yong-Nian

    2008-07-01

    Boron carbon nitride thin films were deposited by radio frequency (RF) magnetron sputtering technique using a 50 mm-diameter composite target consisting of h-BN and graphite in an Ar-N2 gas mixture. The composite target was composed of two semi disks: one of h-BN and the other one of graphite. The distance between the target and the substrate was kept at 50 mm. The chamber base pressure was below 5 x 10(-4) Pa. During the deposition, the mixture of Ar (80%) and N2 (20%) was injected into the vacuum chamber and the total pressure was 1.3 Pa. The films were grown on silicon substrates at different deposition parameters, including sputtering power of 80-130 W, deposition temperature of 300-500 degrees C and deposition time of 1-4 h. The chemical bonding state of the samples was characterized by Fourier transform infrared absorption spectroscopy (FTIR). The results suggested that all of the films deposited at these deposition parameters are atomic-level hybrids composed of B, C and N atoms. Besides BN and carbons bonds, the boron carbide and carbon nitride bonds were formed in the BCN thin films. And the deposition parameters have important influences on the growth and inner stress of BCN thin films. That is the higher the sputtering power, the larger the inner stress; the higher or lower the deposition temperature, the larger the inner stress; the longer the deposition time, the larger the inner stress. So changing deposition parameters properly is a feasible method to relax the inner stress between the films and substrate. In the conditions of changing one parameter each time, the optimum deposition parameters to prepare BCN thin films with lower inner stress were obtained: sputtering power of 80 W, deposition temperature of 400 degrees C and deposition time of 2 h.

  3. Substrate temperature influence on the trombogenicity in amorphous carbon nitride thin coatings

    Energy Technology Data Exchange (ETDEWEB)

    Galeano-Osorio, D.S.; Vargas, S.; Lopez-Cordoba, L.M.; Ospina, R. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Magdalena, Manizales (Colombia); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Magdalena, Manizales (Colombia); Arango, P.J. [Laboratorio de Fisica del Plasma, Universidad Nacional de Colombia Sede Manizales, Km. 9 via al Magdalena, Manizales (Colombia)

    2010-10-01

    Carbon nitride thin films were obtained through plasma assisted physical vapor deposition technique by pulsed arc, varying the substrate temperature and investigating the influence of this parameter on the films hemocompatibility. For obtaining approaches of blood compatibility, environmental scanning electron microscopy (ESEM) was used in order to study the platelets adherence and their morphology. Moreover, the elemental chemical composition was determined by using energy dispersive spectroscopy (EDS), finding C, N and O. The coatings hemocompatibility was evaluated by in vitro thrombogenicity test, whose results were correlated with the microstructure and roughness of the films obtained. During the films growth process, the substrate temperature was varied, obtaining coatings under different temperatures, room temperature (T{sub room}), 100 deg. C, 150 deg. C and 200 deg. C. Parameters as interelectrodic distance, voltage, work pressure and number of discharges, were remained constant. By EDS, carbon and nitrogen were found in the films. Visible Raman spectroscopy was used, and it revealed an amorphous lattice, with graphitic process as the substrate temperature was increased. However, at a critical temperature of 150 deg. C, this tendency was broken, and the film became more amorphous. This film showed the lowest roughness, 2 {+-} 1 nm. This last characteristic favored the films hemocompatibility. Also, it was demonstrated that the blood compatibility of carbon nitride films obtained were affected by the I{sub D}/I{sub G} or sp{sup 3}/sp{sup 2} ratio and not by the absolute sp{sup 3} or sp{sup 2} concentration.

  4. Albumin and fibrinogen adsorption on boron nitride and carbon-based thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lousinian, S.; Kalfagiannis, N. [Laboratory for Thin Films - Nanosystems and Nanometrology (LTFN), Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Logothetidis, S. [Laboratory for Thin Films - Nanosystems and Nanometrology (LTFN), Department of Physics, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece)], E-mail: logot@auth.gr

    2008-08-25

    The haemocompatibility (in the sense of the least possibility of thrombus formation/thrombogenicity potential) of homogeneous and amorphous BN (a-BN) thin films through the adsorption of two basic blood plasma proteins, human serum albumin (HSA) and fibrinogen (Fib) is explored in this work. A comparative study of the thrombogenicity potential of BN, amorphous carbon (a-C) and amorphous hydrogenated carbon thin films (a-C:H) is also presented. a-BN and a-C thin films were produced by radio frequency (RF) magnetron sputtering onto c-Si (1 0 0) substrates under various values of substrate bias voltage. a-C:H thin films were developed by RF Reactive MS, with various values of substrate bias voltage and under different values of H{sub 2} partial pressure during deposition. For the consideration of the optical, compositional and structural properties of the films Spectroscopic Ellipsometry in the energy region of 1.5-6.5 eV was used, while for the study of surface topography and wetting properties Atomic Force Microscopy and Contact Angle measurements were additionally employed. The properties of the thin films were correlated with their thrombogenicity, through the estimation of the ratio of HSA/Fib surface concentration. a-BN films exhibit the smallest possibility of clot formation, with their wetting properties determining the thickness of the Fib layer formed on them as well as the ratio of HSA/Fib surface concentration. In the case of a-C thin films, the increase of % sp{sup 3} content is crucial, while the value of the fundamental gap seems to influence the possibility for clot formation on a-C:H thin films.

  5. Light emission in forward and reverse bias operation in OLED with amorphous silicon carbon nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Reyes, R [Facultad de Ingenieria Quimica y Textil, Universidad Nacional de Ingenieria, Av. Tupac Amaru SN, Lima (Peru); Cremona, M [Departamento de Fisica, PontifIcia Universidade Catolica de Rio de Janeiro, PUC-Rio, Cx. Postal 38071, Rio de Janeiro, RJ, CEP 22453-970 (Brazil); Achete, C A, E-mail: rreyes@uni.edu.pe [Departamento de Engenheria Metalurgica e de Materiais, Universidade Federal do Rio de Janeiro, Cx. Postal 68505, Rio de Janeiro, RJ, CEP 21945-970 (Brazil)

    2011-01-01

    Amorphous silicon carbon nitride (a-SiC:N) thin films deposited by magnetron sputtering were used in the structure of an organic light emitting diode (OLED), obtaining an OLED operating in forward and reverse bias mode. The device consist of the heterojunction structure ITO/a-SiC:N/Hole Transport Layer (HTL)/ Electron Transport Layer (ETL)/a-SiC:N/Al. As hole transporting layer was used a thin film of 1-(3-methylphenyl)-1,2,3,4 tetrahydroquinoline - 6 - carboxyaldehyde - 1,1'- diphenylhydrazone (MTCD), while the tris(8-hydroxyquinoline aluminum) (Alq{sub 3}) is used as electron transport and emitting layer. A significant increase in the voltage operation compared to the conventional ITO/MTCD/Alq{sub 3}/Al structure was observed, so the onset of electroluminescence occurs at about 22 V in the forward and reverse bias mode of operation. The electroluminescence spectra is similar in both cases, only slightly shifted 0.14 eV to lower energies in relation to the conventional device.

  6. Boron nitride converted carbon fiber

    Science.gov (United States)

    Rousseas, Michael; Mickelson, William; Zettl, Alexander K.

    2016-04-05

    This disclosure provides systems, methods, and apparatus related to boron nitride converted carbon fiber. In one aspect, a method may include the operations of providing boron oxide and carbon fiber, heating the boron oxide to melt the boron oxide and heating the carbon fiber, mixing a nitrogen-containing gas with boron oxide vapor from molten boron oxide, and converting at least a portion of the carbon fiber to boron nitride.

  7. Investiagtion of Nanoscale Carbon Nitride Thin Films Grown Using DC HCD Hollow Cathode Discharge%用直流中空阴极放电方法(DC HCD)生长的纳米级碳的氮化物薄膜研究

    Institute of Scientific and Technical Information of China (English)

    YAN Y.H.; SHI Y.C.; YANG P.; TANG X.L.; FENG P.X.

    2005-01-01

    There is growing interest in the underlying physical processes in optoelectronic devices based on thin-film multilayer structures. Recently, many investigators have made great efforts on synthesizing the ultra - hard nanoscale carbon nitride thin films. Considering low cost and simple configuration, we used DC hollow cathode discharge (HCD) for deposition of nanoscale carbon nitride thin films.

  8. Deposit of thin films of nitrided amorphous carbon using the laser ablation technique; Deposito de peliculas delgadas de carbono amorfo nitrurado utilizando la tecnica de ablacion laser

    Energy Technology Data Exchange (ETDEWEB)

    Rebollo, P.B.; Escobar A, L.; Camps C, E. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, C.P. 52045 Salazar, Estado de Mexico (Mexico); Haro P, E.; Camacho L, M.A. [Departamento de Fisica, Universidad Autonoma Metropolitana Iztapalapa (Mexico); Muhl S, S. [Instituto de Investigacion en Materiales, UNAM (Mexico)

    2000-07-01

    It is reported the synthesis and characterization of thin films of amorphous carbon (a-C) nitrided, deposited by laser ablation in a nitrogen atmosphere at pressures which are from 4.5 x 10 {sup -4} Torr until 7.5 x 10 {sup -2} Torr. The structural properties of the films are studied by Raman spectroscopy obtaining similar spectra at the reported for carbon films type diamond. The study of behavior of the energy gap and the ratio nitrogen/carbon (N/C) in the films, shows that the energy gap is reduced when the nitrogen incorporation is increased. It is showed that the refraction index of the thin films diminish as nitrogen pressure is increased, indicating the formation of graphitic material. (Author)

  9. Effect of acetic acid on electrochemical deposition of carbon-nitride thin film

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Electrochemical deposition method was employed to prepare CNx thin film from methanol-urea solution,and it was shown that adding a little acetic acid in the solution significantly affected the deposition process.After optimizing the experiment conditions,we obtained polycrystalline grains with sizes of about 3―7μm on the faces of single crystal silicon.X-ray diffraction spectrua indicate that the grains are mainly composed of cubic phase mixed with a small amount of β and α phases.

  10. Studies on Wear and Corrosion Resistances of Carbon Nitride Thin Films on Ti Alloy

    Institute of Scientific and Technical Information of China (English)

    LiJin-chai; GuoHuai-xi; LuXlan-feng; ZhangZhi-hong; YeMing-sheng

    2003-01-01

    CNx/SiCN composite films were prepared on titanium ( Ti ) alloy substrates by Radio Frequency Plasma Enhanced Chemical Vapor Deposition ( RF-PECVD ). As a buffer layer, SiCN ensured the adhesion of the CNx thin films on Ti substrates. X-ray diffraction (XRD) measurement revealed that the composite films possessed α-C3N4 structure.The microhardness of the films was 48 to 50 GPa. In or der totest the characteristics of wear and corrosion resistances, we prepared Ti alloy samples with and without CNx/SiCN composite films. Also for strengthening the effect of wear and corrosion, the wear tests were carried out under high load (12 MPa) and in 0. 9% NaCl solution. Results of the wear tests and the corrosive electrochemical measurements showed that the samples coated with CNx films had excellent charac-teristics of wear and corrosion resistances compared with Ti alloy substrate samples.

  11. Studies on Wear and Corrosion Resistances of Carbon Nitride Thin Films on Ti Alloy

    Institute of Scientific and Technical Information of China (English)

    Li Jin-chai; Guo Huai-xi; Lu Xian-feng; Zhang Zhi-hong; Ye Ming-sheng

    2003-01-01

    CNx/SiCN composite films were prepared on titanium ( Ti ) alloy substrates by Radio Frequency Plasma Enhanced Chemical Vapor Deposition ( RF-PECVD ). As a buffer layer, SiCN ensured the adhesion of the CNx thin films on Ti substrates. X-ray diffraction (XRD) measurement revealed that the composite films possessed α-C3N4 structure.The microhardness of the films was 48 to 50 GPa. In order to test the characteristics of wear and corrosion resistances, we prepared Ti alloy samples with and without CNx/SiCN composite films. Also for strengthening the effect of wear and corrosion, the wear tests were carried out under high load (12 MPa) and in 0. 9% NaCl solution. Results of the wear tests and the corrosive electrochemical measurements showed that the samples coated with CNx films had excellent characteristics of wear and corrosion resistances compared with Ti alloy substrate samples.

  12. Dangling bond energetics in carbon nitride and phosphorus carbide thin films with fullerene-like and amorphous structure

    OpenAIRE

    Kostov Gueorguiev, Gueorgui; Broitman, E; Furlan, Andrej; Stafström, Sven; Hultman, Lars

    2009-01-01

    The energy cost for dangling bond formation in Fullerene-like Carbon Nitride (FL-CNx) and Phosphorus carbide (FL-CPx) as well as their amorphous counterparts: a-CNx, a-CPx, and a-C has been calculated within the framework of Density Functional Theory and compared with surface water adsorption measurements. The highest energy cost is found in the FL-CNx ( about 1.37 eV) followed by FL-CPx compounds (0.62-1.04 eV). (C) 2009 Elsevier B. V. All rights reserved. Original Publication:Gueorgui K...

  13. Synthesis and characterization of thin films of nitrided amorphous carbon deposited by laser ablation; Sintesis y caracterizacion de peliculas delgadas de carbono amorfo nitrurado, depositadas por ablacion laser

    Energy Technology Data Exchange (ETDEWEB)

    Rebollo P, B

    2001-07-01

    The objective of this work is the synthesis and characterization of thin films of amorphous carbon (a-C) and thin films of nitrided amorphous carbon (a-C-N) using the laser ablation technique for their deposit. For this purpose, the physical properties of the obtained films were studied as function of diverse parameters of deposit such as: nitrogen pressure, power density, substrate temperature and substrate-target distance. For the characterization of the properties of the deposited thin films the following techniques were used: a) Raman spectroscopy which has demonstrated being a sensitive technique to the sp{sup 2} and sp{sup 3} bonds content, b) Energy Dispersive Spectroscopy which allows to know semi-quantitatively way the presence of the elements which make up the deposited films, c) Spectrophotometry, for obtaining the absorption spectra and subsequently the optical energy gap of the deposited material, d) Ellipsometry for determining the refraction index, e) Scanning Electron Microscopy for studying the surface morphology of thin films and, f) Profilemetry, which allows the determination the thickness of the deposited thin films. (Author)

  14. Multifractal characteristics of titanium nitride thin films

    Directory of Open Access Journals (Sweden)

    Ţălu Ştefan

    2015-09-01

    Full Text Available The study presents a multi-scale microstructural characterization of three-dimensional (3-D micro-textured surface of titanium nitride (TiN thin films prepared by reactive DC magnetron sputtering in correlation with substrate temperature variation. Topographical characterization of the surfaces, obtained by atomic force microscopy (AFM analysis, was realized by an innovative multifractal method which may be applied for AFM data. The surface micromorphology demonstrates that the multifractal geometry of TiN thin films can be characterized at nanometer scale by the generalized dimensions Dq and the singularity spectrum f(α. Furthermore, to improve the 3-D surface characterization according with ISO 25178-2:2012, the most relevant 3-D surface roughness parameters were calculated. To quantify the 3-D nanostructure surface of TiN thin films a multifractal approach was developed and validated, which can be used for the characterization of topographical changes due to the substrate temperature variation.

  15. Synthesis of ternary metal nitride nanoparticles using mesoporous carbon nitride as reactive template.

    Science.gov (United States)

    Fischer, Anna; Müller, Jens Oliver; Antonietti, Markus; Thomas, Arne

    2008-12-23

    Mesoporous graphitic carbon nitride was used as both a nanoreactor and a reactant for the synthesis of ternary metal nitride nanoparticles. By infiltration of a mixture of two metal precursors into mesoporous carbon nitride, the pores act first as a nanoconfinement, generating amorphous mixed oxide nanoparticles. During heating and decomposition, the carbon nitride second acts as reactant or, more precisely, as a nitrogen source, which converts the preformed mixed oxide nanoparticles into the corresponding nitride (reactive templating). Using this approach, ternary metal nitride particles with diameters smaller 10 nm composed of aluminum gallium nitride (Al-Ga-N) and titanium vanadium nitride (Ti-V-N) were synthesized. Due to the confinement effect of the carbon nitride matrix, the composition of the resulting metal nitride can be easily adjusted by changing the concentration of the preceding precursor solution. Thus, ternary metal nitride nanoparticles with continuously adjustable metal composition can be produced.

  16. Laser ablation of molecular carbon nitride compounds

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, D., E-mail: d.fischer@fkf.mpg.de [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Schwinghammer, K. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), 80799 Munich (Germany); Sondermann, C. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Lau, V.W.; Mannhart, J. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Lotsch, B.V. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), 80799 Munich (Germany)

    2015-09-15

    We present a method for the preparation of thin films on sapphire substrates of the carbon nitride precursors dicyandiamide (C{sub 2}N{sub 4}H{sub 4}), melamine (C{sub 3}N{sub 6}H{sub 6}), and melem (C{sub 6}N{sub 10}H{sub 6}), using the femtosecond-pulsed laser deposition technique (femto-PLD) at different temperatures. The depositions were carried out under high vacuum with a femtosecond-pulsed laser. The focused laser beam is scanned on the surface of a rotating target consisting of the pelletized compounds. The resulting polycrystalline, opaque films were characterized by X-ray powder diffraction, infrared, Raman, and X-ray photoelectron spectroscopy, photoluminescence, SEM, and MALDI-TOF mass spectrometry measurements. The crystal structures and optical/spectroscopic results of the obtained rough films largely match those of the bulk materials.

  17. Hard carbon nitride and method for preparing same

    Science.gov (United States)

    Haller, E.E.; Cohen, M.L.; Hansen, W.L.

    1992-05-05

    Novel crystalline [alpha](silicon nitride-like)-carbon nitride and [beta](silicon nitride-like)-carbon nitride are formed by sputtering carbon in the presence of a nitrogen atmosphere onto a single crystal germanium or silicon, respectively, substrate. 1 figure.

  18. Structure, Mechanics and Synthesis of Nanoscale Carbon and Boron Nitride

    Science.gov (United States)

    Rinaldo, Steven G.

    This thesis is divided into two parts. In Part I, we examine the properties of thin sheets of carbon and boron nitride. We begin with an introduction to the theory of elastic sheets, where the stretching and bending modes are considered in detail. The coupling between stretching and bending modes is thought to play a crucial role in the thermodynamic stability of atomically-thin 2D sheets such as graphene. In Chapter 2, we begin by looking at the fabrication of suspended, atomically thin sheets of graphene. We then study their mechanical resonances which are read via an optical transduction technique. The frequency of the resonators was found to depend on their temperature, as was their quality factor. We conclude by offering some interpretations of the data in terms of the stretching and bending modes of graphene. In Chapter 3, we look briefly at the fabrication of thin sheets of carbon and boron nitride nanotubes. We examine the structure of the sheets using transmission and scanning electron microscopy (TEM and SEM, respectively). We then show a technique by which one can make sheets suspended over a trench with adjustable supports. Finally, DC measurements of the resistivity of the sheets in the temperature range 600 -- 1400 C are presented. In Chapter 4, we study the folding of few-layer graphene oxide, graphene and boron nitride into 3D aerogel monoliths. The properties of graphene oxide are first considered, after which the structure of graphene and boron nitride aerogels is examined using TEM and SEM. Some models for their structure are proposed. In Part II, we look at synthesis techniques for boron nitride (BN). In Chapter 5, we study the conversion of carbon structures of boron nitride via the application of carbothermal reduction of boron oxide followed by nitridation. We apply the conversion to a wide variety of morphologies, including aerogels, carbon fibers and nanotubes, and highly oriented pyrolytic graphite. In the latter chapters, we look at the

  19. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  20. Deposition of carbon nitride films for space application

    Institute of Scientific and Technical Information of China (English)

    Feng Yu-Dong; Xu Chao; Wang Yi; Zhang Fu-Jia

    2006-01-01

    Carbon nitride thin films were prepared by electron-beam evaporation assisted with nitrogen ion bombardment and TiN/CNx composite films were by unbalanced dc magnetron sputtering, respectively. It was found that the sputtered films were better than the evaporated films in hardness and adhesion. The experiments of atomic oxygen action, cold welding, friction and wearing were emphasized, and the results proved that the sputtered TiN/CNx composite films were suitable for space application.

  1. Vertical III-nitride thin-film power diode

    Energy Technology Data Exchange (ETDEWEB)

    Wierer, Jr., Jonathan; Fischer, Arthur J.; Allerman, Andrew A.

    2017-03-14

    A vertical III-nitride thin-film power diode can hold off high voltages (kV's) when operated under reverse bias. The III-nitride device layers can be grown on a wider bandgap template layer and growth substrate, which can be removed by laser lift-off of the epitaxial device layers grown thereon.

  2. Electroless plating of thin gold films directly onto silicon nitride thin films and into micropores.

    Science.gov (United States)

    Whelan, Julie C; Karawdeniya, Buddini Iroshika; Bandara, Y M Nuwan D Y; Velleco, Brian D; Masterson, Caitlin M; Dwyer, Jason R

    2014-07-23

    A method to directly electrolessly plate silicon-rich silicon nitride with thin gold films was developed and characterized. Films with thicknesses plating free-standing ultrathin silicon nitride membranes, and we successfully plated the interior walls of micropore arrays in 200 nm thick silicon nitride membranes. The method is thus amenable to coating planar, curved, and line-of-sight-obscured silicon nitride surfaces.

  3. Preparation of graphitic carbon nitride by electrodeposition

    Institute of Scientific and Technical Information of China (English)

    LI Chao; CAO Chuanbao; ZHU Hesun

    2003-01-01

    The CNx thin film was deposited on Si(100) substrate from a saturated acetone solution of cyanuric trichloride and melamine (cyanuric trichloride/melamine=1︰1.5) at room temperature. X-ray diffraction (XRD) results showed that the diffraction peaks in the pattern coincided well with those of graphite-like carbon nitride calculated in the literature. The lattice constants (a=4.79 A, c=6.90 A) for g-C3N4 matched with those of ab initio calculations (a=4.74 A, c=6.72 A) quite well. X-ray photoelectron spectroscopy (XPS) measurements indicated that the elements in the deposited films were mostly of C and N (N/C=0.75), and N (400.00 eV) bonded with C (287.72 eV) in the form of six-member C3N3 ring. The peaks at 800 cm-1, 1310 cm-1 and 1610 cm-1 in the Fourier transform infrared (FTIR) spectrum indicated that triazine ring existed in the product. These results demonstrated that crystalline g-C3N4 was obtained in the CNx film.

  4. Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Bakoglidis, Konstantinos D., E-mail: konba@ifm.liu.se; Schmidt, Susann; Garbrecht, Magnus; Ivanov, Ivan G.; Jensen, Jens; Greczynski, Grzegorz; Hultman, Lars [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden)

    2015-09-15

    The potential of different magnetron sputtering techniques for the synthesis of low friction and wear resistant amorphous carbon nitride (a-CN{sub x}) thin films onto temperature-sensitive AISI52100 bearing steel, but also Si(001) substrates was studied. Hence, a substrate temperature of 150 °C was chosen for the film synthesis. The a-CN{sub x} films were deposited using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited using a N{sub 2}/Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage, V{sub s}, was varied from 20 to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy and selected area electron diffraction, while the film morphology was investigated by scanning electron microscopy. All films possessed an amorphous microstructure, while the film morphology changed with the bias voltage. Layers grown applying the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the sputter technique. Voids closed and dense films are formed at V{sub s} ≥ 60 V, V{sub s} ≥ 100 V, and V{sub s} = 120 V for MFMS, DCMS, and HiPIMS, respectively. X-ray photoelectron spectroscopy revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis showed that Ar content varied between 0 and 0.8 at. % and increased as a function of V{sub s} for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with values ranging between −0.4 and −1.2 GPa for all V{sub s}, while CN{sub x} films deposited by MFMS showed residual stresses up to −4.2

  5. New nanoforms of carbon and boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Pokropivny, V V [Institute for Problems of Materials Science of National Academy of Sciences of Ukraine (Ukraine); Ivanovskii, A L [Institute of Solid State Chemistry, Urals Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation)], e-mail: Ivanovskii@ihim.uran.ru

    2008-10-31

    Data on new carbon nanostructures including those based on fullerenes, nanotubes as well monolithic diamond-like nanoparticles, nanofibres, various nanocomposites, etc., published in the last decade are generalised. The experimental and theoretical data on their atomic and electronic structures, the nature of chemical bonds and physicochemical properties are discussed. These data are compared with the results obtained in studies of nanoforms of boron nitride, an isoelectronic analogue of carbon. Potential fields of applications of the new nanostructures are considered.

  6. New nanoforms of carbon and boron nitride

    Science.gov (United States)

    Pokropivny, V. V.; Ivanovskii, A. L.

    2008-10-01

    Data on new carbon nanostructures including those based on fullerenes, nanotubes as well monolithic diamond-like nanoparticles, nanofibres, various nanocomposites, etc., published in the last decade are generalised. The experimental and theoretical data on their atomic and electronic structures, the nature of chemical bonds and physicochemical properties are discussed. These data are compared with the results obtained in studies of nanoforms of boron nitride, an isoelectronic analogue of carbon. Potential fields of applications of the new nanostructures are considered.

  7. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    Science.gov (United States)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)

    2016-01-01

    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  8. Formation and control of stoichiometric hafnium nitride thin films by direct sputtering of hafnium nitride target

    CERN Document Server

    Gotoh, Y; Ishikawa, J; Liao, M Y

    2003-01-01

    Hafnium nitride thin films were prepared by radio-frequency sputter deposition with a hafnium nitride target. Deposition was performed with various rf powers, argon pressures, and substrate temperatures, in order to investigate the influences of these parameters on the film properties, particularly the nitrogen composition. It was found that stoichiometric hafnium nitride films were formed at an argon gas pressure of less than 2 Pa, irrespective of the other deposition parameters within the range investigated. Maintaining the nitrogen composition almost stoichiometric, orientation, stress, and electrical resistivity of the films could be controlled with deposition parameters. (author)

  9. Amorphous carbon buffer layers for separating free gallium nitride films

    Science.gov (United States)

    Altakhov, A. S.; Gorbunov, R. I.; Kasharina, L. A.; Latyshev, F. E.; Tarala, V. A.; Shreter, Yu. G.

    2016-11-01

    The possibility of using amorphous diamond-like carbon (DLC) films for self-separation of gallium nitride (GaN) layers grown by hydride vapor-phase epitaxy has been analyzed. DLC films have been synthesized by plasma-enhanced chemical vapor deposition under low pressure on sapphire (Al2O3) substrates with a (0001) crystallographic orientation. The samples have been studied by the methods of Raman scattering and X-ray diffraction analysis. It is shown that thin DLC films affect only slightly the processes of nucleation and growth of gallium nitride films. Notably, the strength of the "GaN film-Al2O3" substrate interface decreases, which facilitates separation of the GaN layers.

  10. Thermally grown thin nitride films as a gate dielectric

    CERN Document Server

    Shin, H C; Hwang, T K; Lee, K R

    1998-01-01

    High-quality very thin films ( <=6 nm) of silicon nitride were thermally grown in ammonia atmosphere with an IR (Infrared) gold image furnace. As-grown nitride film was analyzed using AES(Auger Emission Spectroscopy). Using MIS (Metal-Insulator-Semiconductor) devices, the growth rate was calculated using CV (Capacitance-Voltage) measurements and various electrical characteristics were obtained using CV, IV (Current-Voltage), trapping, time-dependent breakdown, high-field stress, constant current injection stress and dielectric breakdown techniques. These characteristics showed that very thin thermal silicon nitride films can be used as gate dielectrics for future highly scaled-down ULSI (Ultra Large Scale Integrated) devices, especially for EEPROM (Electrically Erasable and Programmable ROM)'s.

  11. Photocurrent generation in carbon nitride and carbon nitride/conjugated polymer composites.

    Science.gov (United States)

    Byers, Joshua C; Billon, Florence; Debiemme-Chouvy, Catherine; Deslouis, Claude; Pailleret, Alain; Semenikhin, Oleg A

    2012-09-26

    The semiconductor and photovoltaic properties of carbon nitride (CNx) thin films prepared using a reactive magnetron cathodic sputtering technique were investigated both individually and as composites with an organic conjugated polymer, poly(2,2'-bithiophene) (PBT). The CNx films showed an increasing thickness as the deposition power and/or nitrogen content in the gas mixture increase. At low nitrogen content and low deposition power (25-50 W), the film structure was dominated by the abundance of the graphitic sp(2) regions, whereas at higher nitrogen contents and magnetron power CNx films started to demonstrate semiconductor properties, as evidenced by the occurrence of photoconductivity and the development of a space charge region. However, CNx films alone did not show any reproducible photovoltaic properties. The situation changed, however, when CNx was deposited onto conjugated PBT substrates. In this configuration, CNx was found to function as an acceptor material improving the photocurrent generation both in solution and in solid state photovoltaic devices, with the external quantum efficiencies reaching 1% at high nitrogen contents. The occurrence of the donor-acceptor charge transfer was further evidenced by suppression of the n-doping of the PBT polymer by CNx. Nanoscale atomic force microscopy (AFM) and current-sensing AFM data suggested that CNx may form a bulk heterojunction with PBT.

  12. Synthesis of amorphous carbon nitride by ion implantation

    Institute of Scientific and Technical Information of China (English)

    ChenZ.; OlofinjanaA.; BellJ

    2001-01-01

    N2+ were implanted into diamondlike carbon (DLC) films in an attempt to synthesizeamorphous carbon nitride. The DLC films were previously deposited on steel substrate by using anion beam sputtering deposition (IBSD) where a single Kaufman type ion gun with argon sourcewas used to sputter a graphite target and simultaneously bombard the growing film. Parallel to theion implantation route, amorphous carbon nitride films were also synthesized by directly using thereactive ion beam sputtering deposition (RIBSD) with nitrogen source to incorporate nitrogen intothe film. The structure and properties of the films were determined by using Raman spectroscopy,XPS and nano-indentation. The implantation of N2+ into a-C films offers a higher hardness thanthat directly synthesized by RIBSD, probably through an increase in sp3/sp2 ratio and in the pro-portion of nitrogen atoms chemically bonding to carbon atoms. The results show that althoughthere are differences in film composition, structure and properties between these two processes,both methods can be used for synthesis of nitrogen-containing amorphous DLC thin films whichsignificantly modify the substrate surface.

  13. Nitrogen incorporation in sputter deposited molybdenum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stöber, Laura, E-mail: laura.stoeber@tuwien.ac.at; Patocka, Florian, E-mail: florian.patocka@tuwien.ac.at; Schneider, Michael, E-mail: michael.schneider@tuwien.ac.at; Schmid, Ulrich, E-mail: ulrich.e366.schmid@tuwien.ac.at [Institute of Sensor and Actuator Systems, TU Wien, Gußhausstraße 27-29, A-1040 Vienna (Austria); Konrath, Jens Peter, E-mail: jenspeter.konrath@infineon.com; Haberl, Verena, E-mail: verena.haberl@infineon.com [Infineon Technologies Austria AG, Siemensstraße 2, 9500 Villach (Austria)

    2016-03-15

    In this paper, the authors report on the high temperature performance of sputter deposited molybdenum (Mo) and molybdenum nitride (Mo{sub 2}N) thin films. Various argon and nitrogen gas compositions are applied for thin film synthetization, and the amount of nitrogen incorporation is determined by Auger measurements. Furthermore, effusion measurements identifying the binding conditions of the nitrogen in the thin film are performed up to 1000 °C. These results are in excellent agreement with film stress and scanning electron microscope analyses, both indicating stable film properties up to annealing temperatures of 500 °C.

  14. Experimental studies of superhard materials carbon nitride CNx prepared by ion-beam synthesis method

    Institute of Scientific and Technical Information of China (English)

    辛火平; 林成鲁; 许华平; 邹世昌; 石晓红; 吴兴龙; 朱宏; P.L.FHemment

    1996-01-01

    Formation of superhard materials carbon nitride CNt by using ion-beam synthesis method is reported.100-keV high-dose N+ ions were implanted into carbon thin films at different temperatures.The samples were evaluated by X-ray photoelectron spectroscopy (XPS),Fourier transformation-infrared absorption spectroscopy (FTIR),Raman spectroscopy,cross-sectional transmission electron microscopy (XTEM),Rutherford backscattering spectroscopy (RBS).X-ray diffraction analysis (XRD) and Vickers microhardness measurement.The results show that the buried carbon nitride CN> layer has been successfully formed by using 100-keV high-dose N+ ions implantation into carbon thin film.Implantation of reactive ions into silicon (IRIS) computer program has been used to simulate the formation of the buried β-C3N4 layer as N+ ions are implanted into carbon.A good agreement between experimental measurements and IRIS simulation is found.

  15. Chemical Structure of Carbon Nitride Films Prepared by MW-ECR Plasma Enhanced Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    XUJun,GAOPeng; DINGWan-yu; LIXin; DENGXin-lu; DONGChuang

    2004-01-01

    Amorphous carbon nitride thin films were prepared by plasma-enhanced DC magnetron sputtering using twinned microwave electron cyclotron resonance plasma sources. Chemical structure of deposited films was investigated using X-ray photoelectron spectroscopy and Fourier transtorm infrared spectroscopy. The results indicate that the deposition rate is strongly affected by direct current bias, and the films are mainly composed of a single amorphous carbon nitride phase with N/C ratio close to C3N4, and the bonding is predominantly of C-N type.

  16. Preparation of carbon-nitride bulk samples in the presence of seed carbon-nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. I. [Korea University of Technology and Education, Chonan (Korea, Republic of); Zorov, N. B. [Moscow State University, Moscow (Russian Federation)

    2004-05-15

    A procedure was developed for preparing bulk carbon-nitride crystals from polymeric alpha-C{sub 3}N{sub 4.2} at high pressure and high temperature in the presence of seeds of crystalline carbon-nitride films prepared by using a high-voltage discharge plasma combined with pulsed laser ablation of a graphite target. The samples were evaluated by using X-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, Auger electron spectroscopy (AES), secondary-ion mass spectrometry (SIMS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Notably, XPS studies of the film composition before and after thermobaric treatments demonstrated that the nitrogen composition in the alpha-C{sub 3}N{sub 4.2} material, which initially contained more than 58 % nitrogen, decreased during the annealing process and reached a common, stable composition of approx 45 %. The thermobaric experiments were performed at 10 - 77 kbar and 350 - 1200 .deg. C.

  17. Carbon nitride frameworks and dense crystalline polymorphs

    Science.gov (United States)

    Pickard, Chris J.; Salamat, Ashkan; Bojdys, Michael J.; Needs, Richard J.; McMillan, Paul F.

    2016-09-01

    We used ab initio random structure searching (AIRSS) to investigate polymorphism in C3N4 carbon nitride as a function of pressure. Our calculations reveal new framework structures, including a particularly stable chiral polymorph of space group P 43212 containing mixed s p2 and s p3 bonding, that we have produced experimentally and recovered to ambient conditions. As pressure is increased a sequence of structures with fully s p3 -bonded C atoms and three-fold-coordinated N atoms is predicted, culminating in a dense P n m a phase above 250 GPa. Beyond 650 GPa we find that C3N4 becomes unstable to decomposition into diamond and pyrite-structured CN2.

  18. Carbon Superatom Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Canning, A. [Cray Research, PSE, EPFL, 1015 Lausanne (Switzerland); Canning, A.; Galli, G. [Institut Romand de Recherche Numerique en Physique des Materiaux (IRRMA), IN-Ecublens, 1015 Lausanne (Switzerland); Kim, J. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)

    1997-06-01

    We report on quantum molecular dynamics simulations of C{sub 28} deposition on a semiconducting surface. Our results show that under certain deposition conditions C{sub 28} {close_quote}s act as building blocks on a nanometer scale to form a thin film of nearly defect-free molecules. The C{sub 28} {close_quote}s behave as carbon superatoms, with the majority of them being threefold or fourfold coordinated, similar to carbon atoms in amorphous systems. The microscopic structure of the deposited film supports recent suggestions about the stability of a new form of carbon, the hyperdiamond solid. {copyright} {ital 1997} {ital The American Physical Society}

  19. Room temperature synthesis of biodiesel using sulfonated graphitic carbon nitride

    Science.gov (United States)

    Baig, R. B. Nasir; Verma, Sanny; Nadagouda, Mallikarjuna N.; Varma, Rajender S.

    2016-12-01

    Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature.

  20. Room temperature synthesis of biodiesel using sulfonated graphitic carbon nitride

    Science.gov (United States)

    Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature.

  1. Magnetron sputter deposited tantalum and tantalum nitride thin films: An analysis of phase, hardness and composition

    Energy Technology Data Exchange (ETDEWEB)

    Bernoulli, D. [Laboratory for Nanometallurgy, Department of Materials, ETH-Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich (Switzerland); Müller, U. [EMPA, Swiss Federal Laboratories for Material Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Schwarzenberger, M. [Laboratory for Nanometallurgy, Department of Materials, ETH-Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich (Switzerland); Hauert, R. [EMPA, Swiss Federal Laboratories for Material Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Spolenak, R. [Laboratory for Nanometallurgy, Department of Materials, ETH-Zurich, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich (Switzerland)

    2013-12-02

    Tantalum (Ta) and tantalum nitride thin films are highly important as diffusion barriers and adhesion layers in microelectronics and hard coatings for cutting tools. In this study, the effect of the underlying substrate on the phase formation of Ta and the influence of a changing N{sub 2}/Ar flow ratio on hardness, phase and composition of reactively formed tantalum nitride have been investigated. Ta is DC sputter deposited and forms β-Ta on amorphous diamond-like carbon and on the amorphous natural oxide layers of Ti and Si(100) while a 15 nm TaN seed layer results in the formation of α-Ta. The chemical composition of the topmost layers of a substrate influences the formation of α- and β-Ta. With increasing N{sub 2}/Ar flow ratios a transition from amorphous Ta-rich tantalum nitride over face-centered cubic tantalum nitride (fcc-TaN) to (100) textured fcc-TaN at flow ratios above 45% is observed. The hardness of the tantalum nitride thin film reaches a maximum at a flow ratio of 45%, followed by a decrease in hardness for higher N{sub 2}/Ar flow ratios. The increase in hardness is associated with a decrease in grain size and shows a stronger correlation for a Meyers and Ashworth relationship than for a Hall–Petch relationship. - Highlights: • Chemical composition of the substrate influences the phase of deposited Ta. • FCC-TaN seed layer leads to α-Ta on the natural oxide layers of Ti and Si(100). • Meyers and Ashworth relationship correlates stronger than Hall–Petch relationship.

  2. Growth of gallium nitride and indium nitride nanowires on conductive and flexible carbon cloth substrates.

    Science.gov (United States)

    Yang, Yi; Ling, Yichuan; Wang, Gongming; Lu, Xihong; Tong, Yexiang; Li, Yat

    2013-03-07

    We report a general strategy for synthesis of gallium nitride (GaN) and indium nitride (InN) nanowires on conductive and flexible carbon cloth substrates. GaN and InN nanowires were prepared via a nanocluster-mediated growth method using a home built chemical vapor deposition (CVD) system with Ga and In metals as group III precursors and ammonia as a group V precursor. Electron microscopy studies reveal that the group III-nitride nanowires are single crystalline wurtzite structures. The morphology, density and growth mechanism of these nanowires are determined by the growth temperature. Importantly, a photoelectrode fabricated by contacting the GaN nanowires through a carbon cloth substrate shows pronounced photoactivity for photoelectrochemical water oxidation. The ability to synthesize group III-nitride nanowires on conductive and flexible substrates should open up new opportunities for nanoscale photonic, electronic and electrochemical devices.

  3. Synthesis of reduced carbon nitride at the reduction by hydroquinone of water-soluble carbon nitride oxide (g-C{sub 3}N{sub 4})O

    Energy Technology Data Exchange (ETDEWEB)

    Kharlamov, Alexey [Frantsevich Institute for Problems of Materials Science of NASU, Krzhyzhanovsky St. 3, 03680 Kiev (Ukraine); Bondarenko, Marina, E-mail: mebondarenko@ukr.net [Frantsevich Institute for Problems of Materials Science of NASU, Krzhyzhanovsky St. 3, 03680 Kiev (Ukraine); Kharlamova, Ganna [Taras Shevchenko National University of Kiev, Volodymyrs' ka St. 64, 01601 Kiev (Ukraine); Fomenko, Veniamin [Frantsevich Institute for Problems of Materials Science of NASU, Krzhyzhanovsky St. 3, 03680 Kiev (Ukraine)

    2016-09-15

    For the first time at the reduction by hydroquinone of water-soluble carbon nitride oxide (g-C{sub 3}N{sub 4})O reduced carbon nitride (or reduced multi-layer azagraphene) is obtained. It is differed from usually synthesized carbon nitride by a significantly large (on 0.09 nm) interplanar distance is. At the same time, the chemical bonds between atoms in a heteroatomic plane of reduced carbon nitride correspond to the bonds in a synthesized g-C{sub 3}N{sub 4}. The samples of water-soluble carbon nitride oxide were synthesized under the special reactionary conditions of a pyrolysis of melamine and urea. We believe that reduced carbon nitride consists of weakly connected carbon-nitrogen monosheets (azagraphene sheets) as well as reduced (from graphene oxide) graphene contains weakly connected graphene sheets. - Graphical abstract: XRD pattern and schematic atomic model of one layer of reduced carbon nitride, carbon nitride oxide and synthesized carbon nitride. For the first time at the reduction by hydroquinone of the water-soluble carbon nitride oxide (g-C{sub 3}N{sub 4})O is obtained the reduced carbon nitride (or reduced multi-layer azagraphene). Display Omitted - Highlights: • First the reduced carbon nitride (RCN) at the reduction of the carbon nitride oxide was obtained. • Water-soluble carbon nitride oxide was reduced by hydroquinone. • The chemical bonds in a heteroatomic plane of RCN correspond to the bonds in a synthesized g-C{sub 3}N{sub 4}. • Reduced carbon nitride consists of poorly connected heteroatomic azagraphene layers.

  4. Polymeric photocatalysts based on graphitic carbon nitride.

    Science.gov (United States)

    Cao, Shaowen; Low, Jingxiang; Yu, Jiaguo; Jaroniec, Mietek

    2015-04-01

    Semiconductor-based photocatalysis is considered to be an attractive way for solving the worldwide energy shortage and environmental pollution issues. Since the pioneering work in 2009 on graphitic carbon nitride (g-C3N4) for visible-light photocatalytic water splitting, g-C3N4 -based photocatalysis has become a very hot research topic. This review summarizes the recent progress regarding the design and preparation of g-C3N4 -based photocatalysts, including the fabrication and nanostructure design of pristine g-C3N4 , bandgap engineering through atomic-level doping and molecular-level modification, and the preparation of g-C3N4 -based semiconductor composites. Also, the photo-catalytic applications of g-C3N4 -based photocatalysts in the fields of water splitting, CO2 reduction, pollutant degradation, organic syntheses, and bacterial disinfection are reviewed, with emphasis on photocatalysis promoted by carbon materials, non-noble-metal cocatalysts, and Z-scheme heterojunctions. Finally, the concluding remarks are presented and some perspectives regarding the future development of g-C3N4 -based photocatalysts are highlighted.

  5. Studies of silicon carbide and silicon carbide nitride thin films

    Science.gov (United States)

    Alizadeh, Zhila

    Silicon carbide semiconductor technology is continuing to advance rapidly. The excellent physical and electronic properties of silicon carbide recently take itself to be the main focused power device material for high temperature, high power, and high frequency electronic devices because of its large band gap, high thermal conductivity, and high electron saturation drift velocity. SiC is more stable than Si because of its high melting point and mechanical strength. Also the understanding of the structure and properties of semiconducting thin film alloys is one of the fundamental steps toward their successful application in technologies requiring materials with tunable energy gaps, such as solar cells, flat panel displays, optical memories and anti-reflecting coatings. Silicon carbide and silicon nitrides are promising materials for novel semiconductor applications because of their band gaps. In addition, they are "hard" materials in the sense of having high elastic constants and large cohesive energies and are generally resistant to harsh environment, including radiation. In this research, thin films of silicon carbide and silicon carbide nitride were deposited in a r.f magnetron sputtering system using a SiC target. A detailed analysis of the surface chemistry of the deposited films was performed using x-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy whereas structure and morphology was studied atomic force microscopy (AFM), and nonoindentation.

  6. Unintentional carbide formation evidenced during high-vacuum magnetron sputtering of transition metal nitride thin films

    Science.gov (United States)

    Greczynski, G.; Mráz, S.; Hultman, L.; Schneider, J. M.

    2016-11-01

    Carbide signatures are ubiquitous in the surface analyses of industrially sputter-deposited transition metal nitride thin films grown with carbon-less source materials in typical high-vacuum systems. We use high-energy-resolution photoelectron spectroscopy to reveal details of carbon temporal chemical state evolution, from carbide formed during film growth to adventitious carbon adsorbed upon contact with air. Using in-situ grown Al capping layers that protect the as-deposited transition metal nitride surfaces from oxidation, it is shown that the carbide forms during film growth rather than as a result of post deposition atmosphere exposure. The XPS signature of carbides is masked by the presence of adventitious carbon contamination, appearing as soon as samples are exposed to atmosphere, and eventually disappears after one week-long storage in lab atmosphere. The concentration of carbon assigned to carbide species varies from 0.28 at% for ZrN sample, to 0.25 and 0.11 at% for TiN and HfN, respectively. These findings are relevant for numerous applications, as unintentionally formed impurity phases may dramatically alter catalytic activity, charge transport and mechanical properties by offsetting the onset of thermally-induced phase transitions. Therefore, the chemical state of C impurities in PVD-grown films should be carefully investigated.

  7. Graphitic carbon nitride based nanocomposites: a review.

    Science.gov (United States)

    Zhao, Zaiwang; Sun, Yanjuan; Dong, Fan

    2015-01-07

    Graphitic carbon nitride (g-C(3)N(4)), as an intriguing earth-abundant visible light photocatalyst, possesses a unique two-dimensional structure, excellent chemical stability and tunable electronic structure. Pure g-C(3)N(4) suffers from rapid recombination of photo-generated electron-hole pairs resulting in low photocatalytic activity. Because of the unique electronic structure, the g-C(3)N(4) could act as an eminent candidate for coupling with various functional materials to enhance the performance. According to the discrepancies in the photocatalytic mechanism and process, six primary systems of g-C(3)N(4)-based nanocomposites can be classified and summarized: namely, the g-C(3)N(4) based metal-free heterojunction, the g-C(3)N(4)/single metal oxide (metal sulfide) heterojunction, g-C(3)N(4)/composite oxide, the g-C(3)N(4)/halide heterojunction, g-C(3)N(4)/noble metal heterostructures, and the g-C(3)N(4) based complex system. Apart from the depiction of the fabrication methods, heterojunction structure and multifunctional application of the g-C(3)N(4)-based nanocomposites, we emphasize and elaborate on the underlying mechanisms in the photocatalytic activity enhancement of g-C(3)N(4)-based nanocomposites. The unique functions of the p-n junction (semiconductor/semiconductor heterostructures), the Schottky junction (metal/semiconductor heterostructures), the surface plasmon resonance (SPR) effect, photosensitization, superconductivity, etc. are utilized in the photocatalytic processes. Furthermore, the enhanced performance of g-C(3)N(4)-based nanocomposites has been widely employed in environmental and energetic applications such as photocatalytic degradation of pollutants, photocatalytic hydrogen generation, carbon dioxide reduction, disinfection, and supercapacitors. This critical review ends with a summary and some perspectives on the challenges and new directions in exploring g-C(3)N(4)-based advanced nanomaterials.

  8. DFT Studies on Electronic Structures of Boro-Nitride-Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    YAN Ming; HUANG Chun-Hui

    2005-01-01

    In this paper, the configurations of Boro-Nitride-Carbon nanotubes with BNC2 composition were optimized by ROHF method. According to the density functional theory, the electronic structures of Boro-Nitride-Carbon nanotubes were calculated by DFT/ROB3LYP method. By analyzing the energy gap, density of electronic state and bonding maps of atoms, the conductive properties of Boro-Nitride-Carbon nanotubes were obtained, and compared with those of carbon nanotubes and other Boro-Nitride nanotubes.

  9. Reactive pulsed laser deposition of gold nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Caricato, A.P. [University of Salento, Department of Physics, 73100 Lecce (Italy); Fernandez, M. [University of Salento, Department of Physics, 73100 Lecce (Italy); Leggieri, G. [University of Salento, Department of Physics, 73100 Lecce (Italy)]. E-mail: leggieri@le.infn.it; Luches, A. [University of Salento, Department of Physics, 73100 Lecce (Italy); Martino, M. [University of Salento, Department of Physics, 73100 Lecce (Italy); Romano, F. [University of Salento, Department of Physics, 73100 Lecce (Italy); Tunno, T. [University of Salento, Department of Physics, 73100 Lecce (Italy); Valerini, D. [University of Salento, Department of Physics, 73100 Lecce (Italy); Verdyan, A. [Science Department, Holon Academic Institute of Technology, Holon 58102 (Israel); Soifer, Y.M. [Science Department, Holon Academic Institute of Technology, Holon 58102 (Israel); Azoulay, J. [Science Department, Holon Academic Institute of Technology, Holon 58102 (Israel); Meda, L. [IGD Polimeri Europa S.p.A, Novara (Italy)

    2007-07-31

    We report on the growth and characterization of gold nitride thin films on Si <1 0 0> substrates at room temperature by reactive pulsed laser ablation. A pure (99.95%) Au target was ablated with KrF excimer laser pulses in nitrogen containing atmosphere (N{sub 2} or NH{sub 3}). The gas ambient pressure was varied in the range 0.1-100 Pa. The morphology of the films was studied by using optical, scanning electron and atomic force microscopy, evidencing compact films with RMS roughness in the range 3.6-35.1 nm, depending on the deposition pressure. Rutherford backscattering spectrometry and energy dispersion spectroscopy (EDS) were used to detect the nitrogen concentration into the films. The EDS nitrogen peak does not decrease in intensity after 2 h annealing at 250 deg. C. Film resistivity was measured using a four-point probe and resulted in the (4-20) x 10{sup -8} {omega} m range, depending on the ambient pressure, to be compared with the value 2.6 x 10{sup -8} {omega} m of a pure gold film. Indentation and scratch measurements gave microhardness values of 2-3 GPa and the Young's modulus close to 100 GPa. X-ray photoemission spectra clearly showed the N 1s peak around 400 eV and displaced with respect to N{sub 2} phase. All these measurements point to the formation of the gold nitride phase.

  10. Reactive pulsed laser deposition of gold nitride thin films

    Science.gov (United States)

    Caricato, A. P.; Fernàndez, M.; Leggieri, G.; Luches, A.; Martino, M.; Romano, F.; Tunno, T.; Valerini, D.; Verdyan, A.; Soifer, Y. M.; Azoulay, J.; Meda, L.

    2007-07-01

    We report on the growth and characterization of gold nitride thin films on Si substrates at room temperature by reactive pulsed laser ablation. A pure (99.95%) Au target was ablated with KrF excimer laser pulses in nitrogen containing atmosphere (N 2 or NH 3). The gas ambient pressure was varied in the range 0.1-100 Pa. The morphology of the films was studied by using optical, scanning electron and atomic force microscopy, evidencing compact films with RMS roughness in the range 3.6-35.1 nm, depending on the deposition pressure. Rutherford backscattering spectrometry and energy dispersion spectroscopy (EDS) were used to detect the nitrogen concentration into the films. The EDS nitrogen peak does not decrease in intensity after 2 h annealing at 250 °C. Film resistivity was measured using a four-point probe and resulted in the (4-20) × 10 -8 Ω m range, depending on the ambient pressure, to be compared with the value 2.6 × 10 -8 Ω m of a pure gold film. Indentation and scratch measurements gave microhardness values of 2-3 GPa and the Young's modulus close to 100 GPa. X-ray photoemission spectra clearly showed the N 1s peak around 400 eV and displaced with respect to N 2 phase. All these measurements point to the formation of the gold nitride phase.

  11. Structure and Thermal Stability of Copper Nitride Thin Films

    Directory of Open Access Journals (Sweden)

    Guangan Zhang

    2013-01-01

    Full Text Available Copper nitride (Cu3N thin films were deposited on glass via DC reactive magnetron sputtering at various N2 flow rates and partial pressures with 150°C substrate temperature. X-ray diffraction and scanning electron microscopy were used to characterize the microstructure and morphology. The results show that the films are composed of Cu3N crystallites with anti-ReO3 structure. The microstructure and morphology of the Cu3N film strongly depend on the N2 flow rate and partial pressure. The cross-sectional micrograph of the film shows typical columnar, compact structure. The thermal stabilities of the films were investigated using vacuum annealing under different temperature. The results show that the introducing of argon in the sputtering process decreases the thermal stability of the films.

  12. Spectroscopic ellipsometry characterization of thin-film silicon nitride

    Energy Technology Data Exchange (ETDEWEB)

    Jellison, G.E. Jr.; Modine, F.A. [Oak Ridge National Lab., TN (United States); Doshi, P.; Rohatgi, A. [Georiga Inst. of Technology, Atlanta, GA (United States)

    1997-05-01

    We have measured and analyzed the optical characteristics of a series of silicon nitride thin films prepared by plasma-enhanced chemical vapor deposition on silicon substrates for photovoltaic applications. Spectroscopic ellipsometry measurements were made by using a two-channel spectroscopic polarization modulator ellipsometer that measures N, S, and C data simultaneously. The data were fit to a model consisting of air / roughness / SiN / crystalline silicon. The roughness was modeled using the Bruggeman effective medium approximation, assuming 50% SiN, 50% voids. The optical functions of the SiN film were parameterized using a model by Jellison and Modine. All the {Chi}{sup 2} are near 1, demonstrating that this model works extremely well for all SiN films. The measured dielectric functions were used to make optimized SiN antireflection coatings for crystalline silicon solar cells.

  13. Synthesis of reduced carbon nitride at the reduction by hydroquinone of water-soluble carbon nitride oxide (g-C3N4)O

    Science.gov (United States)

    Kharlamov, Alexey; Bondarenko, Marina; Kharlamova, Ganna; Fomenko, Veniamin

    2016-09-01

    For the first time at the reduction by hydroquinone of water-soluble carbon nitride oxide (g-C3N4)O reduced carbon nitride (or reduced multi-layer azagraphene) is obtained. It is differed from usually synthesized carbon nitride by a significantly large (on 0.09 nm) interplanar distance is. At the same time, the chemical bonds between atoms in a heteroatomic plane of reduced carbon nitride correspond to the bonds in a synthesized g-C3N4. The samples of water-soluble carbon nitride oxide were synthesized under the special reactionary conditions of a pyrolysis of melamine and urea. We believe that reduced carbon nitride consists of weakly connected carbon-nitrogen monosheets (azagraphene sheets) as well as reduced (from graphene oxide) graphene contains weakly connected graphene sheets.

  14. Method of manufacture of atomically thin boron nitride

    Science.gov (United States)

    Zettl, Alexander K

    2013-08-06

    The present invention provides a method of fabricating at least one single layer hexagonal boron nitride (h-BN). In an exemplary embodiment, the method includes (1) suspending at least one multilayer boron nitride across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure. The present invention also provides a method of fabricating single layer hexagonal boron nitride. In an exemplary embodiment, the method includes (1) providing multilayer boron nitride suspended across a gap of a support structure and (2) performing a reactive ion etch upon the multilayer boron nitride to produce the single layer hexagonal boron nitride suspended across the gap of the support structure.

  15. Nanotribological performance of fullerene-like carbon nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Flores-Ruiz, Francisco Javier; Enriquez-Flores, Christian Ivan [Centro de Investigación y Estudios Avanzados (CINVESTAV) IPN, Unidad Querétaro, Lib. Norponiente 2000, Real de Juriquilla, C.P. 76230, Querétaro, Qro., México (Mexico); Chiñas-Castillo, Fernando, E-mail: fernandochinas@gmail.com [Department of Mechanical Engineering, Instituto Tecnológico de Oaxaca, Oaxaca, Oax. Calz. Tecnológico No. 125, CP. 68030, Oaxaca, Oax. (Mexico); Espinoza-Beltrán, Francisco Javier [Centro de Investigación y Estudios Avanzados (CINVESTAV) IPN, Unidad Querétaro, Lib. Norponiente 2000, Real de Juriquilla, C.P. 76230, Querétaro, Qro., México (Mexico)

    2014-09-30

    Highlights: • Fullerene-like CNx samples show an elastic recovery of 92.5% and 94.5% while amorphous CNx samples had only 75% elastic recovery. • Fullerene-like CNx films show an increment of 34.86% and 50.57% in fractions of C 1s and N 1s. • Fullerene-like CNx samples show a lower friction coefficient compared to amorphous CNx samples. • Friction reduction characteristics of fullerene-like CNx films are strongly related to the increase of sp{sup 3} CN bonds. - Abstract: Fullerene-like carbon nitride films exhibit high elastic modulus and low friction coefficient. In this study, thin CNx films were deposited on silicon substrate by DC magnetron sputtering and the tribological behavior at nanoscale was evaluated using an atomic force microscope. Results show that CNx films with fullerene-like structure have a friction coefficient (CoF ∼ 0.009–0.022) that is lower than amorphous CNx films (CoF ∼ 0.028–0.032). Analysis of specimens characterized by X-ray photoelectron spectroscopy shows that films with fullerene-like structure have a higher number of sp{sup 3} CN bonds and exhibit the best mechanical properties with high values of elastic modulus (E > 180 GPa) and hardness (H > 20 GPa). The elastic recovery determined on specimens with a fullerene-like CNx structure was of 95% while specimens of amorphous CNx structure had only 75% elastic recovery.

  16. Low temperature aluminum nitride thin films for sensory applications

    Science.gov (United States)

    Yarar, E.; Hrkac, V.; Zamponi, C.; Piorra, A.; Kienle, L.; Quandt, E.

    2016-07-01

    A low-temperature sputter deposition process for the synthesis of aluminum nitride (AlN) thin films that is attractive for applications with a limited temperature budget is presented. Influence of the reactive gas concentration, plasma treatment of the nucleation surface and film thickness on the microstructural, piezoelectric and dielectric properties of AlN is investigated. An improved crystal quality with respect to the increased film thickness was observed; where full width at half maximum (FWHM) of the AlN films decreased from 2.88 ± 0.16° down to 1.25 ± 0.07° and the effective longitudinal piezoelectric coefficient (d33,f) increased from 2.30 ± 0.32 pm/V up to 5.57 ± 0.34 pm/V for film thicknesses in the range of 30 nm to 2 μm. Dielectric loss angle (tan δ) decreased from 0.626% ± 0.005% to 0.025% ± 0.011% for the same thickness range. The average relative permittivity (ɛr) was calculated as 10.4 ± 0.05. An almost constant transversal piezoelectric coefficient (|e31,f|) of 1.39 ± 0.01 C/m2 was measured for samples in the range of 0.5 μm to 2 μm. Transmission electron microscopy (TEM) investigations performed on thin (100 nm) and thick (1.6 μm) films revealed an (002) oriented AlN nucleation and growth starting directly from the AlN-Pt interface independent of the film thickness and exhibit comparable quality with the state-of-the-art AlN thin films sputtered at much higher substrate temperatures.

  17. Synthesis of graphitic carbon nitride by reaction of melamine and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Dante, Roberto C., E-mail: rcdante@yahoo.com [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Martin-Ramos, Pablo, E-mail: pablomartinramos@gmail.com [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Correa-Guimaraes, Adriana, E-mail: acg@iaf.uva.es [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Martin-Gil, Jesus, E-mail: jesusmartingil@gmail.com [Laboratorio de Tecnologias del Medio Ambiente, Departamento de Ingenieria Agricola y Forestal, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain)

    2011-11-01

    Highlights: {yields} Graphitic carbon nitrides by CVD of melamine and uric acid on alumina. {yields} The building blocks of carbon nitrides are heptazine nuclei. {yields} Composite particles with alumina core and carbon nitride coating. - Abstract: Graphitic carbon nitrides were synthesized starting from melamine and uric acid. Uric acid was chosen because it thermally decomposes, and reacts with melamine by condensation at temperatures in the range of 400-600 deg. C. The reagents were mixed with alumina and subsequently the samples were treated in an oven under nitrogen flux. Alumina favored the deposition of the graphitic carbon nitrides layers on the exposed surface. This method can be assimilated to an in situ chemical vapor deposition (CVD). Infrared (IR) spectra, as well as X-ray diffraction (XRD) patterns, are in accordance with the formation of a graphitic carbon nitride with a structure based on heptazine blocks. These carbon nitrides exhibit poor crystallinity and a nanometric texture, as shown by transmission electron microscopy (TEM) analysis. The thermal degradation of the graphitic carbon nitride occurs through cyano group formation, and involves the bridging tertiary nitrogen and the bonded carbon, which belongs to the heptazine ring, causing the ring opening and the consequent network destruction as inferred by connecting the IR and X-ray photoelectron spectroscopy (XPS) results. This seems to be an easy and promising route to synthesize graphitic carbon nitrides. Our final material is a composite made of an alumina core covered by carbon nitride layers.

  18. Low-temperature CVD of iron, cobalt, and nickel nitride thin films from bis[di(tert-butyl)amido]metal(II) precursors and ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Cloud, Andrew N.; Abelson, John R., E-mail: abelson@illinois.edu [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 201 Materials Science and Engineering Building, 1304 W. Green St., Urbana, Illinois 61801 (United States); Davis, Luke M.; Girolami, Gregory S., E-mail: girolami@scs.illinois.edu [School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801 (United States)

    2014-03-15

    Thin films of late transition metal nitrides (where the metal is iron, cobalt, or nickel) are grown by low-pressure metalorganic chemical vapor deposition from bis[di(tert-butyl)amido]metal(II) precursors and ammonia. These metal nitrides are known to have useful mechanical and magnetic properties, but there are few thin film growth techniques to produce them based on a single precursor family. The authors report the deposition of metal nitride thin films below 300 °C from three recently synthesized M[N(t-Bu){sub 2}]{sub 2} precursors, where M = Fe, Co, and Ni, with growth onset as low as room temperature. Metal-rich phases are obtained with constant nitrogen content from growth onset to 200 °C over a range of feedstock partial pressures. Carbon contamination in the films is minimal for iron and cobalt nitride, but similar to the nitrogen concentration for nickel nitride. X-ray photoelectron spectroscopy indicates that the incorporated nitrogen is present as metal nitride, even for films grown at the reaction onset temperature. Deposition rates of up to 18 nm/min are observed. The film morphologies, growth rates, and compositions are consistent with a gas-phase transamination reaction that produces precursor species with high sticking coefficients and low surface mobilities.

  19. Anti corrosion layer for stainless steel in molten carbonate fuel cell - comprises phase vapour deposition of titanium nitride, aluminium nitride or chromium nitride layer then oxidising layer in molten carbonate electrolyte

    DEFF Research Database (Denmark)

    2000-01-01

    Forming an anticorrosion protective layer on a stainless steel surface used in a molten carbonate fuel cell (MCFC) - comprises the phase vapour deposition (PVD) of a layer comprising at least one of titanium nitride, aluminium nitride or chromium nitride and then forming a protective layer in situ...

  20. Tribological properties of sputtered tungsten and tungsten nitride thin films

    Institute of Scientific and Technical Information of China (English)

    Wong; K.M.; ShenY.G.; Wong; P.L.

    2001-01-01

    The surface roughness, hardness and tribological properties of tungsten (W) and tung-sten nitride (WNx) thin films prepared by dc magnetron sputtering and reactive magnetron sputter-ing in Ar-N2 gas mixtures have been studied using atomic force microscopy (AFM), nanoindenta-tion measurements and ball-on-disc wear testing. A pronounced surface roughness was observedonly for films under compressive strains. The surface was flat under tension but rough under com-pression. Similar hardness with value about 20 GPa were observed in the W and WNx (x=0.3)films. This is thought to be due to the fact the grains are restricted to a very small size in the coat-ings. The higher coefficients of friction (0.4 for W and 0.9 for WN0.3) suggest that WN0.3 is not theoptimum phase. Finally, discussions are made with tribological test results.

  1. Mechanical and electrochemical characterization of vanadium nitride (VN) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.C., E-mail: Jcesarca@calima.univalle.edu.co [Grupo de Peliculas Delgadas, Departamento de Fisica, Universidad del Valle, Cali (Colombia); Zambrano, G. [Grupo de Peliculas Delgadas, Departamento de Fisica, Universidad del Valle, Cali (Colombia); Aperador, W. [Ingenieria Mecatronica, Universidad Militar Nueva Granada, Bogota (Colombia); Escobar-Alarcon, L.; Camps, E. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico, DF 11801 (Mexico)

    2011-10-15

    Vanadium nitride (V-N) thin films were grown using a reactive d.c. magnetron sputtering process, from a vanadium target (99.999%) in an Ar/N{sub 2} gas mixture at different deposition bias voltage. Films were deposited onto silicon (1 0 0) and RUS-3 steel substrates at 400 deg. C. Structural, compositional, mechanical and electrochemical characterizations were performed by X-ray diffraction (XRD), elastic forward analysis (EFA), nanoindentation, electrochemical impedance spectroscopy (EIS), and Tafel polarization curves, respectively. X-ray diffraction patterns show the presence of (1 1 1) and (2 0 0) crystallographic orientations associated to the V-N cubic phase. Nanoindentation measurements revealed that when the bias voltage increases from 0 V to -150 V the hardness and elastic modulus are increased from 11 GPa to 20 GPa and from 187 GPa to 221 GPa, respectively. EIS and Tafel curves showed that the corrosion rate of steel, coated with V-N single layer films deposited without bias voltage, diminishes 90% compared to the steel without this coating. On the other hand, when the V-N coating was deposited at the highest d.c. bias voltage (-150 V), the corrosion rate was greater than in the steel coated with zero-voltage (0 V) V-N films. This last result could be attributed to the formation of porosities produced by the ion bombardment during the deposition process.

  2. Tuning the optical response in carbon doped boron nitride nanodots

    KAUST Repository

    Mokkath, Junais Habeeb

    2014-09-04

    Time dependent density functional theory and the hybrid B3LYP functional are used to investigate the structural and optical properties of pristine and carbon doped hexagonal boron nitride nanodots. In agreement with recent experiments, the embedded carbon atoms are found to favor nucleation. Our results demonstrate that carbon clusters of different shapes promote an early onset of absorption by generating in-gap states. The nanodots are interesting for opto-electronics due to their tunable optical response in a wide energy window. We identify cluster sizes and shapes with optimal conversion efficiency for solar radiation and a wide absorption range form infrared to ultraviolet. This journal is

  3. Nanoporous Carbon Nitride: A High Efficient Filter for Seawater Desalination

    OpenAIRE

    Weifeng LI; Yang, Yanmei; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2015-01-01

    The low efficiency of commercially-used reverse osmosis (RO) membranes has been the main obstacle in seawater desalination application. Here, we report the auspicious performance, through molecular dynamics simulations, of a seawater desalination filter based on the recently-synthesized graphene-like carbon nitride (g-C2N) [Nat. Commun., 2015, 6, 6486]. Taking advantage of the inherent nanopores and excellent mechanical properties of g-C2N filter, highly efficient seawater desalination can be...

  4. The influence of substrate temperature on the tribo- mechanical properties of chromium nitride thin films

    Science.gov (United States)

    Merie, V. V.; Negrea, G.; Modi, E.

    2016-08-01

    Different nitrides such as titanium nitride, chromium nitride and so on are used in a widespread range of applications such as cutting tools, medical implants, and microelectromechanical devices and all that due to their mechanical, physical and chemical properties. The aim of this study is to obtain chromium nitride thin films and to characterize them by atomic force microscopy investigations. The chromium nitride thin films were deposited by reactive magnetron sputtering on silicon substrates. During the deposition process, the discharge current, the argon and nitrogen flows, the pressure inside the chamber and the deposition time were kept constant. A chromium target with a purity of 99.95 % was used. Some of the films were deposited after a chromium buffer layer was previously deposited on the silicon substrate. The deposition was carried out when substrate temperature was at room temperature, at 300 and 500°C respectively. Once the films were deposited, atomic force microscopy investigations were performed in order to emphasize the influence of the substrate temperature on the topographical, mechanical and tribological characteristics. The results pointed out an important influence of the substrate temperature on topographical, mechanical and tribological properties of the investigated chromium nitride thin films.

  5. Mesoporous carbon nitride-tungsten oxide composites for enhanced photocatalytic hydrogen evolution.

    Science.gov (United States)

    Kailasam, Kamalakannan; Fischer, Anna; Zhang, Guigang; Zhang, Jinshui; Schwarze, Michael; Schröder, Marc; Wang, Xinchen; Schomäcker, Reinhard; Thomas, Arne

    2015-04-24

    Composites of mesoporous polymeric carbon nitride and tungsten(VI) oxide show very high photocatalytic activity for the evolution of hydrogen from water under visible light and in the presence of sacrificial electron donors. Already addition of very small amounts of WO3 yields up to a twofold increase in the efficiency when compared to bulk carbon nitrides and their composites and more notably even to the best reported mesoporous carbon nitride-based photocatalytic materials. The higher activity can be attributed to the high surface area and synergetic effect of the carbon nitrides and the WO3 resulting in improved charge separation through a photocatalytic solid-state Z-scheme mechanism.

  6. Thin film phase diagram of iron nitrides grown by molecular beam epitaxy

    Science.gov (United States)

    Gölden, D.; Hildebrandt, E.; Alff, L.

    2017-01-01

    A low-temperature thin film phase diagram of the iron nitride system is established for the case of thin films grown by molecular beam epitaxy and nitrided by a nitrogen radical source. A fine-tuning of the nitridation conditions allows for growth of α ‧ -Fe8Nx with increasing c / a -ratio and magnetic anisotropy with increasing x until almost phase pure α ‧ -Fe8N1 thin films are obtained. A further increase of nitrogen content below the phase decomposition temperature of α ‧ -Fe8N (180 °C) leads to a mixture of several phases that is also affected by the choice of substrate material and symmetry. At higher temperatures (350 °C), phase pure γ ‧ -Fe4N is the most stable phase.

  7. Nanocharacterization of Titanium Nitride Thin Films Obtained by Reactive Magnetron Sputtering

    Science.gov (United States)

    Merie, Violeta Valentina; Pustan, Marius Sorin; Bîrleanu, Corina; Negrea, Gavril

    2015-05-01

    Titanium nitride thin films are used in applications such as tribological layers for cutting tools, coating of some medical devices (scalpel blades, prosthesis, implants, etc.), sensors, electrodes for bioelectronics, microelectronics, diffusion barrier, bio-micro-electromechanical systems, and so on. This work is a comparative study concerning the influence of substrate temperature on some mechanical and tribological characteristics of titanium nitride thin films. The researched thin films were obtained by the reactive magnetron sputtering method. The experiments employed two kinds of substrates: a steel substrate and a silicon one. The elaboration of titanium nitride thin films was done at two temperatures. First, when the substrates were at room temperature, and second, when the substrates were previously heated at 250°C. The temperature of 250°C was kept constant during the deposition of the films. The samples were then investigated by atomic force microscopy in order to establish their mechanical and tribological properties. The nanohardness, Young's modulus, roughness, and friction force were some of the determined characteristics. The results demonstrated that the substrate which was previously heated at 250°C led to the obtaining of more adherent titanium nitride thin films than the substrate used at room temperature. The preheating of both substrates determined the decrease of thin films roughness. The friction force, nanohardness and Young's modulus of the tested samples increased when the substrates were preheated at 250°C.

  8. Melon: A carbon-nitride analog to graphene

    Science.gov (United States)

    Therrien, Joel; Li, Yancen; Schmidt, Daniel

    2012-02-01

    Although graphene remains the premier 2-D material, many others have been shown to exist. A close analog to graphene would be a two-dimensional sheet composed of carbon and nitrogen, known as melon. Bulk melon, also known as graphitic carbon-nitride, has been successfully synthesized and shown to be an organic semiconductor with a band-gap around 2.7 eV. We report on the successful synthesis of single layer and few layer melon. The physical and electrical characteristics of this close cousin to graphene will be presented along with the synthesis method.

  9. Preparation and characterization of boron nitride/carbon fiber composite with high specific surface area

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yan; Fan, Mingwen [Wuhan Univ. (China). Key Laboratory for Oral Biomedical Engineering; Yuan, Songdong; Xiong, Kun; Hu, Kunpeng; Luo, Yi [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Li, Dong [Hubei Univ. of Technology, Wuhan (China). School of Chemistry and Chemical Engineering; Oxford Univ. (United Kingdom). Chemistry Research Lab.

    2014-06-15

    Boron nitride can be used as a good catalyst carrier because of its high thermal conductivity and chemical stability. However, a high specific surface area of boron nitride is still desirable. In this work, a carbon fiber composite coated with boron nitride villous nano-film was prepared, and was also characterized by means of scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. The results indicated that the carbon fibers were covered by uniform villous boron nitride films whose thickness was about 150 - 200 nm. The specific surface area of the boron nitride/carbon fiber composite material was 96 m{sup 2} g{sup -1}, which was markedly improved compared with conventional boron nitride materials. (orig.)

  10. Generation and Characteristics of IV-VI transition Metal Nitride and Carbide Nanoparticles using a Reactive Mesoporous Carbon Nitride

    KAUST Repository

    Alhajri, Nawal Saad

    2016-02-22

    Interstitial nitrides and carbides of early transition metals in groups IV–VI exhibit platinum-like electronic structures, which make them promising candidates to replace noble metals in various catalytic reactions. Herein, we present the preparation and characterization of nano-sized transition metal nitries and carbides of groups IV–VI (Ti, V, Nb, Ta, Cr, Mo, and W) using mesoporous graphitic carbon nitride (mpg-C3N4), which not only provides confined spaces for restricting primary particle size but also acts as a chemical source of nitrogen and carbon. We studied the reactivity of the metals with the template under N2 flow at 1023 K while keeping the weight ratio of metal to template constant at unity. The produced nanoparticles were characterized by powder X-ray diffraction, CHN elemental analysis, nitrogen sorption, X-ray photoelectron spectroscopy, and transmission electron microscopy. The results show that Ti, V, Nb, Ta, and Cr form nitride phases with face centered cubic structure, whereas Mo and W forme carbides with hexagonal structures. The tendency to form nitride or carbide obeys the free formation energy of the transition metal nitrides and carbides. This method offers the potential to prepare the desired size, shape and phase of transition metal nitrides and carbides that are suitable for a specific reaction, which is the chief objective of materials chemistry.

  11. Compositional analysis of silicon oxide/silicon nitride thin films

    Directory of Open Access Journals (Sweden)

    Meziani Samir

    2016-06-01

    Full Text Available Hydrogen, amorphous silicon nitride (SiNx:H abbreviated SiNx films were grown on multicrystalline silicon (mc-Si substrate by plasma enhanced chemical vapour deposition (PECVD in parallel configuration using NH3/SiH4 gas mixtures. The mc-Si wafers were taken from the same column of Si cast ingot. After the deposition process, the layers were oxidized (thermal oxidation in dry oxygen ambient environment at 950 °C to get oxide/nitride (ON structure. Secondary ion mass spectroscopy (SIMS, Rutherford backscattering spectroscopy (RBS, Auger electron spectroscopy (AES and energy dispersive X-ray analysis (EDX were employed for analyzing quantitatively the chemical composition and stoichiometry in the oxide-nitride stacked films. The effect of annealing temperature on the chemical composition of ON structure has been investigated. Some species, O, N, Si were redistributed in this structure during the thermal oxidation of SiNx. Indeed, oxygen diffused to the nitride layer into Si2O2N during dry oxidation.

  12. Nanoporous Carbon Nitride: A High Efficient Filter for Seawater Desalination

    CERN Document Server

    Li, Weifeng; Zhou, Hongcai; Zhang, Xiaoming; Zhao, Mingwen

    2015-01-01

    The low efficiency of commercially-used reverse osmosis (RO) membranes has been the main obstacle in seawater desalination application. Here, we report the auspicious performance, through molecular dynamics simulations, of a seawater desalination filter based on the recently-synthesized graphene-like carbon nitride (g-C2N) [Nat. Commun., 2015, 6, 6486]. Taking advantage of the inherent nanopores and excellent mechanical properties of g-C2N filter, highly efficient seawater desalination can be achieved by modulating the nanopores under tensile strain. The water permeability can be improved by two orders of magnitude compared to RO membranes, which offers a promising approach to the global water shortage solution.

  13. Silicon nitride coated silicon thin film on three dimensions current collector for lithium ion battery anode

    Science.gov (United States)

    Wu, Cheng-Yu; Chang, Chun-Chi; Duh, Jenq-Gong

    2016-09-01

    Silicon nitride coated silicon (N-Si) has been synthesized by two-step DC sputtering on Cu Micro-cone arrays (CMAs) at ambient temperature. The electrochemical properties of N-Si anodes with various thickness of nitride layer are investigated. From the potential window of 1.2 V-0.05 V, high rate charge-discharge and long cycle test have been executed to investigate the electrochemical performances of various N-Si coated Si-based lithium ion batteries anode materials. Higher specific capacity can be obtained after 200 cycles. The cycling stability is enhanced via thinner nitride layer coating as silicon nitride films are converted to Li3N with covered Si thin films. These N-Si anodes can be cycled under high rates up to 10 C due to low charge transfer resistance resulted from silicon nitride films. This indicates that the combination of silicon nitride and silicon can effectively endure high current and thus enhance the cycling stability. It is expected that N-Si is a potential candidate for batteries that can work effectively under high power.

  14. Improvement of orthodontic friction by coating archwire with carbon nitride film

    Energy Technology Data Exchange (ETDEWEB)

    Wei Songbo [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shao Tianmin, E-mail: shaotm@mail.tsinghua.edu.cn [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Ding Peng [Department of Orthodontics, Peking University School and Hospital of Stomatology, Beijing 100081 (China)

    2011-10-01

    In order to reduce frictional resistance between archwire and bracket during orthodontic tooth movement, carbon nitride (CNx) thin films were deposited on the surface of archwires with ion beam assisted deposition (IBAD). The energy-dispersive X-ray spectrometer (EDS) analysis showed that the CNx film was successfully deposited on the surface of the orthodontic wires. X-ray photoelectron spectroscopy (XPS) analysis suggested that the deposited CNx film was sp{sup 2} carbon dominated structures, and diversiform bonds (N-C, N{identical_to}C, et al.) coexisted in the film. The friction tests indicated that the CNx film significantly reduced the wire-bracket friction both in ambient air and in artificial saliva. The sp{sup 2}C rich structure of the CNx film as well as its protection function for the archwire was responsible for the low friction of the wire-bracket sliding system.

  15. Elaboration of nitride thin films by reactive sputtering

    Directory of Open Access Journals (Sweden)

    Pierre Yves Jouan

    2006-06-01

    Full Text Available The aim of this paper is first a better understanding of DC reactive magnetron sputtering and its implications, such as the hysteresis effect and the process instability. In a second part, this article is devoted to an example of specific application: Aluminium Nitride. AlN thin films have been deposited by reactive triode sputtering. We have studied the effect of the nitrogen contents in the discharge and the RF bias voltage on the growth of AlN films on Si(100 deposited by triode sputtering. Stoichiometry and crystal orientation of AlN films have been characterized by means of Fourier-transform infrared spectroscopy, X-ray diffraction and secondary electron microscopy. Dense and transparent AlN layers were obtained at high deposition rates. These films have a (002 orientation whatever the nitrogen content in the discharge, but the best crystallised ones are obtained at low value (10%. A linear relationship was observed between the AlN lattice parameter "c" (perpendicular to the substrate surface and the in-plane compressive stress. Applying an RF bias to the substrate leads to a (100 texture, and films become amorphous. Moreover, the film's compressive stress increases up to a value of 8GPa before decreasing slowly as the bias voltage increases.O objetivo desse artigo, em um primeiro momento, é uma melhor compreensão da vaporização em um ambiente magnetron reativo DC e as suas conseqüências, tais como o efeito da histeresis e o processo de instabilidade. A segunda parte desse trabalho está dedicada a um estudo de caso: o nitreto de alumínio. Filmes finos de nitreto de alumínio foram depositados por vaporização triodo reativa. Estudamos o efeito dos teores de nitrogênio, na descarga, e da voltagem RF(bias, no crescimento dos filmes de AlN em Si(100 depositados por vaporização triodo. A estequiometria e a orientação cristalina dos filmes de AlN foram caracterizadas por espectroscopia infravermelha em transformada de Fourier

  16. Convert Graphene Sheets to Boron Nitride and Boron Nitride-Carbon Sheets via a Carbon-Substitution-Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Han, W.; Yu, H.-G.; Liu. Z.

    2011-05-16

    Here we discuss our synthesis of highly crystalline pure boron nitride (BN) and BN-carbon (BN-C) sheets by using graphene sheets as templates via a carbon-substitution reaction. Typically, these sheets are several micrometers wide and have a few layers. The composition ratios of BN-C sheets can be controlled by the post-treatment (remove carbon by oxidation) temperature. We also observed pure BN and BN-C nanoribbons. We characterized the BN-C sheets via Raman spectroscopy and density functional theory calculations. The results reveal that BN-C sheets with an armchair C-BN chain, and embedded C{sub 2} or C{sub 6} units in BN-dominated regions energetically are the most favorable.

  17. Microstructure of titanium nitride thin films controlled by ion bombardment in a magnetron-sputtering device

    Energy Technology Data Exchange (ETDEWEB)

    Cerny, R. (Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni); Kuzel, R. Jr. (Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni); Valvoda, V. (Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni); Kadlec, S. (Czechoslovak Academy of Sciences, Prague (Czechoslovakia). Inst. of Physics); Musil, J. (Czechoslovak Academy of Sciences, Prague (Czechoslovakia). Inst. of Physics)

    1994-05-01

    The structure of titanium nitride thin films deposited by unbalanced magnetron sputtering on high chromium steel substrates was studied by X-ray diffraction. In order to characterize relations between the microstructure of sputtered TiN films and the deposition conditions, the parameter E[sub p] was introduced as the average energy transmitted from bombarding particles (ions, electrons, neutrals, photons) to one condensing particle of the film. A transition from a porous to a compact microstructure was found with increasing E[sub p]. The possible inhomogeneity of titanium nitride films is discussed. (orig.)

  18. Multipactor suppressing titanium nitride thin films analyzed through XPS and AES

    Energy Technology Data Exchange (ETDEWEB)

    Castro C, M.; Durrer, W.; Lopez, J. A.; Pinales, L. A. [Physics Department, University of Texas, El Paso TX 79968 (United States); Encinas B, C.; Moller, D. [Centro de Investigacion en Materiales Avanzados S. C., Miguel de Cervantes Saavedra 120, Complejo Industrial Chihuahua, 31109 Chihuahua (Mexico)

    2008-02-15

    Cathodic-magnetron-deposited titanium nitride films were grown on anodized aluminum substrates and studied via AES and XPS spectroscopies to determine their depth-dependence composition. As it is well known, the native oxide grown on aluminum does not make the substrate impervious to radio frequency damage, and typically a thin film coating is needed to suppress substrate damage. In this article we present the profile composition of titanium nitride films, used as a protective coating for aluminum, that underwent prior conditioning through anodization, observed after successive sputtering stages. (Author)

  19. Optical properties of plasma deposited amorphous carbon nitride films on polymer substrates

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, S.H., E-mail: abo_95@yahoo.co [Physics Department, Faculty of Science, Sohag University, 82524 Sohag (Egypt); El-Hossary, F.M. [Physics Department, Faculty of Science, Sohag University, 82524 Sohag (Egypt); Gamal, G.A.; Kahlid, M.M. [Physics Department, Faculty of Science, South Valley University, 83523 Qena (Egypt)

    2010-01-01

    Amorphous carbon nitride thin films were deposited on polymer substrates using radio frequency (rf) plasma in a mixture of nitrogen (N{sub 2}) and acetylene (C{sub 2}H{sub 2}) gasses. The samples were prepared at different rf plasma power (350, 400, 450, 500, and 550 W), at constant plasma exposure time of 10 min, and constant N{sub 2}/C{sub 2}H{sub 2} ratio of 50%. The crystal structure and surface morphology of the prepared samples were examined using X-ray diffraction and atomic force microscopy analysis, respectively. The absence of the carbon nitride diffraction peaks confirms the amorphous nature of these films. The root mean square roughness of the films increased from 3.77 to 25.22 nm as the power increased from 350 to 550 W. The thickness and the deposition rate were found to increase with increasing plasma power. Over the whole studied wavelength range, from 200 to 2500 nm, the transmittance decreased with increasing plasma power. A shift in the onset of absorption towards higher wavelengths with increasing plasma power, indicating a decrease in the optical band gap, has been observed. The refractive index values were found to decrease while the extinction coefficient increased with increasing plasma power.

  20. MOCVD of hexagonal boron nitride thin films on Si(100) using new single source precursors

    CERN Document Server

    Boo, J H; Yu, K S; Kim, Y S; Kim, Y S; Park, J T

    1999-01-01

    We have been carried out the growth of hexagonal boron nitride (h-BN) thin films on Si(100) substrates by low pressure metal-organic chemical vapor deposition (LPMOCVD) method using triethylborane tert-butylamine complex (TEBTBA), Et sub 3 BNH sub 2 ( sup t Bu), and triethylborane isopropylamine complex (TEBIPA), Et sub 3 BNH sub 2 ( sup t Pr) as a new single molecular precursors in the temperature range of 850 approx 1000 .deg. C. polycrystalline, crack-free h-BN film was successfully grown on Si(100) substrate at 850 .deg. C using TEBTBA. This growth temperature is very lower than those in previous reports. Carbon-rich polycrystalline BN was also obtained at 900 .deg. C from TEBIPA. With increasing substrate temperature to 1000 .deg. C, however, BC sub 4 N-like species are strongly formed along with h-BN and the BN films obtained from both TEBTBA and TEBIPA but almost polycrystalline. To our best knowledge, this is the first report of the growth of h-BN films formed with the new single source precursors of ...

  1. Water adsorption on fullerene-like carbon nitride overcoats

    Energy Technology Data Exchange (ETDEWEB)

    Broitman, E. [Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 (United States)], E-mail: broitman@andrew.cmu.edu; Gueorguiev, G.K.; Furlan, A.; Son, N.T. [IFM, Linkoeping University, SE 581-83 Linkoeping (Sweden); Gellman, A.J. [Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Stafstroem, S.; Hultman, L. [IFM, Linkoeping University, SE 581-83 Linkoeping (Sweden)

    2008-12-01

    Humidity influences the tribological performance of the head-disk interface in magnetic data storage devices. In this work we compare the uptake of water of amorphous carbon nitride (a-CN{sub x}) films, widely used as protective overcoats in computer disk drive systems, with fullerene-like carbon nitride (FL-CN{sub x}) and amorphous carbon (a-C) films. Films with thickness in the range 10-300 nm were deposited on quartz crystal substrates by reactive DC magnetron sputtering. A quartz crystal microbalance placed in a vacuum chamber was used to measure the water adsorption. Electron paramagnetic resonance (EPR) has been used to correlate water adsorption with film microstructure and surface defects (dangling bonds). Measurements indicate that the amount of adsorbed water is highest for the pure a-C films and that the FL-CN{sub x} films adsorbed less than a-CN{sub x}. EPR data correlate the lower water adsorption on FL-CN{sub x} films with a possible lack of dangling bonds on the film surface. To provide additional insight into the atomic structure of defects in the FL-CN{sub x}, a-CN{sub x} and a-C compounds, we performed first-principles calculations within the framework of Density Functional Theory. Emphasis was put on the energy cost for formation of vacancy defects and dangling bonds in relaxed systems. Cohesive energy comparison reveals that the energy cost formation for dangling bonds in different configurations is considerably higher in FL-CN{sub x} than for the amorphous films. These simulations thus confirm the experimental results showing that dangling bonds are much less likely in FL-CN{sub x} than in a-CN{sub x} and a-C films.

  2. Porous carbon nitride nanosheets for enhanced photocatalytic activities

    Science.gov (United States)

    Hong, Jindui; Yin, Shengming; Pan, Yunxiang; Han, Jianyu; Zhou, Tianhua; Xu, Rong

    2014-11-01

    Porous carbon nitride nanosheets (PCNs) have been prepared for the first time by a simple liquid exfoliation method via probe sonication. These mesoporous nanosheets of around 5 nm in thickness combine several advantages including high surface area, enhanced light absorption and excellent water dispersity. It can be used as a versatile support for co-catalyst loading for photocatalytic dye degradation and water reduction. With 3.8 wt% Co3O4 loaded, PCNs can achieve more efficient photocatalytic degradation of Rhodamine B, compared with non-porous C3N4 nanosheets (CNs), bulk porous C3N4 (PCN) and bulk nonporous C3N4 (CN). With 1.0 wt% Pt loaded, CNs and PCN exhibit 7-8 times enhancement in H2 evolution than CN. Remarkably, PCNs with both porous and nanosheet-like features achieve 26 times higher activity in H2 evolution than CN. These significant improvements in photocatalytic activities can be attributed to the high surface area as well as better electron mobility of the two-dimensional nanostructure.Porous carbon nitride nanosheets (PCNs) have been prepared for the first time by a simple liquid exfoliation method via probe sonication. These mesoporous nanosheets of around 5 nm in thickness combine several advantages including high surface area, enhanced light absorption and excellent water dispersity. It can be used as a versatile support for co-catalyst loading for photocatalytic dye degradation and water reduction. With 3.8 wt% Co3O4 loaded, PCNs can achieve more efficient photocatalytic degradation of Rhodamine B, compared with non-porous C3N4 nanosheets (CNs), bulk porous C3N4 (PCN) and bulk nonporous C3N4 (CN). With 1.0 wt% Pt loaded, CNs and PCN exhibit 7-8 times enhancement in H2 evolution than CN. Remarkably, PCNs with both porous and nanosheet-like features achieve 26 times higher activity in H2 evolution than CN. These significant improvements in photocatalytic activities can be attributed to the high surface area as well as better electron mobility of

  3. Visible-light photocatalytic activity of nitrided TiO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Camps, Enrique, E-mail: enrique.camps@inin.gob.mx [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, Mexico DF 11801 (Mexico); Escobar-Alarcon, L. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, Mexico DF 11801 (Mexico); Camacho-Lopez, Marco Antonio [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados, Facultad de Quimica, UAEM, km 14.5 Carretera Toluca-Atlacomulco (Mexico); Casados, Dora A. Solis [Centro de Investigacion en Quimica Sustentable, Facultad de Quimica, UAEM, km 14.5 Carretera Toluca-Atlacomulco (Mexico)

    2010-10-25

    TiO{sub 2} thin films have been applied in UV-light photocatalysis. Nevertheless visible-light photocatalytic activity would make this material more attractive for applications. In this work we present results on the modification of titanium oxide (anatase) sol-gel thin films, via a nitriding process using a microwave plasma source. After the treatment in the nitrogen plasma, the nitrogen content in the TiO{sub 2} films varied in the range from 14 up to 28 at%. The titanium oxide films and the nitrided ones were characterized by XPS, micro-Raman spectroscopy and UV-vis spectroscopy. Photocatalytic activity tests were done using a Methylene Blue dye solution, and as catalyst TiO{sub 2} and nitrided TiO{sub 2} films. The irradiation of films was carried out with a lamp with emission in the visible (without UV). The results showed that the nitrided TiO{sub 2} films had photocatalytic activity, while the unnitrided films did not.

  4. Oxygen functional groups in graphitic carbon nitride for enhanced photocatalysis.

    Science.gov (United States)

    Liu, Shizhen; Li, Degang; Sun, Hongqi; Ang, Ha Ming; Tadé, Moses O; Wang, Shaobin

    2016-04-15

    Metal-free semiconductors offer a new opportunity for environmental photocatalysis toward a potential breakthrough in high photo efficiency with complete prevention of metal leaching. In this study, graphitic carbon nitride (GCN) modified by oxygen functional groups was synthesized by a hydrothermal treatment of pristine GCN at different temperatures with H2O2. Insights into the emerging characteristics of the modified GCN in photocatalysis were obtained by determining the optical properties, band structure, electrochemical activity and pollutant degradation efficiency. It was found that the introduction of GCN with oxygen functional groups can enhance light absorption and accelerate electron transfer so as to improve the photocatalytic reaction efficiency. The photoinduced reactive radicals and the associated photodegradation were investigated by in situ electron paramagnetic resonance (EPR). The reactive radicals, O2(-) and OH, were responsible for organic degradation.

  5. Graphitic carbon nitride embedded hydrogels for enhanced gel electrophoresis.

    Science.gov (United States)

    Zarei, Mohammad; Ahmadzadeh, Hossein; Goharshadi, Elaheh K; Farzaneh, Ali

    2015-08-05

    Here, we show, for the first time, the use of graphitic carbon nitride (g-C3N4) nanosheets to improve the resolution and efficiency of protein separation in gel electrophoresis. By loading 0.04% (m/v) g-C3N4 nanosheets into the polyacrylamide gel at 25 °C, the thermal conductivity increased approximately 80% which resulted in 20% reduction in Joule heating and overall increase of separation efficiency. Also, polymerization of acrylamide occurred in the absence of tetramethylethylenediamine (TEMED) when the polyacrylamide gel contained g-C3N4 nanosheets. Hence, the g-C3N4 act simultaneously as a polymerization catalyst as well as heat sinks to lower Joule heating effect on band broadening.

  6. Transverse electric surface mode in atomically thin Boron-Nitride

    CERN Document Server

    Merano, Michele

    2016-01-01

    The spatial confinement and the propagation length of surface waves in a single-layer two-dimensional atomic crystal are analysed in term of its surface susceptibility and its surface conductivity. Based on the values of these macroscopic parameters, extracted from experimental observations, it is confirmed that graphene supports a transverse magnetic non-radiating surface mode in the ultraviolet spectral region while a single-layer hexagonal Boron-Nitride is predicted to support a transverse electric non-radiating surface mode in the visible spectrum. This last mode, at a vacuum wavelength of 633 nm, has a spatial confinement of 15 microns and an intensity-propagation distance greater than 2 cm.

  7. Lifetime dependence of nitrided carbon stripper foils on sputter angle during N{sup +} ion beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Sugai, I., E-mail: isao.Sugai@kek.jp [High Energy Accelerator Research Organization, Accelerator Laboratory, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Oyaizu, M. [High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Takeda, Y. [High Energy Accelerator Research Organization, Accelerator Laboratory, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Kawakami, H. [High Energy Accelerator Research Organization, Institute of Particle and Nuclear Studies, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan); Kawasaki, K.; Hattori, T. [Department of Physics, Tokyo Institute of Technology, Ohokayama, Meguro, Tokyo 152-8550 (Japan); Kadono, T. [Department of Physics, University of Tokyo, Hongo, 7-3-1, Bunkyo, Tokyo 113-0033 (Japan)

    2015-09-01

    We fabricated high-lifetime thin nitride carbon stripper (NCS) foils with high nitrogen contents using ion-beam sputtering with reactive nitrogen gas and investigated the dependence of their lifetimes on the sputter angle. The nitrogen in carbon foils plays a critical role in determining their lifetime. Therefore, in order to investigate the effects of the nitrogen level in NCS foils on foil lifetime, we measured the sputtering yield for different sputter angles at a sputtering voltage of 10 kV while using carbon-based targets. We also measured the nitrogen-to-carbon thickness ratios of the foils using Rutherford backscattering spectrometry. The foils made at a sputter angle of 15° using a glassy amorphous carbon target exhibited an average increase of 200-fold in lifetime when compared to commercially available foils.

  8. Selective and Regenerative Carbon Dioxide Capture by Highly Polarizing Porous Carbon Nitride.

    Science.gov (United States)

    Oh, Youngtak; Le, Viet-Duc; Maiti, Uday Narayan; Hwang, Jin Ok; Park, Woo Jin; Lim, Joonwon; Lee, Kyung Eun; Bae, Youn-Sang; Kim, Yong-Hyun; Kim, Sang Ouk

    2015-09-22

    Energy-efficient CO2 capture is a stringent demand for green and sustainable energy supply. Strong adsorption is desirable for high capacity and selective capture at ambient conditions but unfavorable for regeneration of adsorbents by a simple pressure control process. Here we present highly regenerative and selective CO2 capture by carbon nitride functionalized porous reduced graphene oxide aerogel surface. The resultant structure demonstrates large CO2 adsorption capacity at ambient conditions (0.43 mmol·g(-1)) and high CO2 selectivity against N2 yet retains regenerability to desorb 98% CO2 by simple pressure swing. First-principles thermodynamics calculations revealed that microporous edges of graphitic carbon nitride offer the optimal CO2 adsorption by induced dipole interaction and allows excellent CO2 selectivity as well as facile regenerability. This work identifies a customized route to reversible gas capture using metal-free, two-dimensional carbonaceous materials, which can be extended to other useful applications.

  9. Synthesis of crumpled nanosheets of polymeric carbon nitride from melamine cyanurate

    Energy Technology Data Exchange (ETDEWEB)

    Dante, Roberto C., E-mail: rcdante@yahoo.com [Laboratorio de Materiales Avanzados (Advanced Materials Laboratory) ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Martín-Ramos, Pablo [Laboratorio de Materiales Avanzados (Advanced Materials Laboratory) ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Sánchez-Arévalo, F.M.; Huerta, L.; Bizarro, M. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apdo. Postal 70-360, Cd. Universitaria, Mexico, D.F. 04510 (Mexico); Navas-Gracia, Luis M.; Martín-Gil, Jesús [Laboratorio de Materiales Avanzados (Advanced Materials Laboratory) ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain)

    2013-05-01

    Polymeric carbon nitride was synthesized by pyrolysis in nitrogen flux at different temperatures between 450 and 700 °C using melamine cyanurate as a reagent and sulfuric acid as a catalyst. The obtained carbon nitride consisted of curled nanosheets (650 °C), and globular particles (700 °C) with formula C₆N₇NHNH₂. The reaction yield of the catalyzed reaction was around the 15% for the sample treated at 700 °C, in a tapped crucible. The optical band gap of the polymer obtained at 700 °C is around 2.9 eV. The gap to the Fermi level is around 2 eV, considerably above the half of the band gap (due to electrons trapped in the gap), indicating that the polymer is probably a n-type semiconductor. - Graphical abstract: Transition from amorphous to crystalline carbon nitride, which is composed of globular particles and is a n-type wide band semiconductor. Highlights: • We synthetized carbon nitride using melamine cyanurate. • The reaction of carbon nitride formation is catalyzed by sulfuric acid. • The carbon nitride obtained at 700 °C is composed of globular particles. • The material obtained at 700 °C is a n-type semiconductor.

  10. The electrical properties of sulfur-implanted cubic boron nitride thin films

    Institute of Scientific and Technical Information of China (English)

    Deng Jin-Xiang; Qin Yang; Kong Le; Yang Xue-Liang; Li Ting; Zhao Wei-Ping; Yang Ping

    2012-01-01

    Cubic boron nitride (c-BN) thin films are deposited on p-type Si wafers using radio frequency (RF) sputtering and then doped by implanting S ions.The implantation energy of the ions is 19 keV,and the implantation dose is between 1015 ions/cm2 and 1016 ions/cm2.The doped c-BN thin films are then annealed at a temperature between 400 ℃ and 800 ℃.The results show that the surface resistivity of doped and annealed c-BN thin films is lowered by two to three orders,and the activation energy of c-BN thin films is 0.18 eV.

  11. Pulsed laser deposition of niobium nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Farha, Ashraf Hassan, E-mail: ahass006@odu.edu; Elsayed-Ali, Hani E., E-mail: helsayed@odu.edu [Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529 (United States); Applied Research Center, Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Department of Physics, Faculty of Science, Ain Shams University, Cairo 11566 (Egypt); Ufuktepe, Yüksel, E-mail: ufuk@cu.edu.tr [Department of Physics, University of Cukurova, 01330 Adana (Turkey); Myneni, Ganapati, E-mail: rao@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)

    2015-12-04

    Niobium nitride (NbN{sub x}) films were grown on Nb and Si(100) substrates using pulsed laser deposition. NbN{sub x} films were deposited on Nb substrates using PLD with a Q-switched Nd:YAG laser (λ = 1064 nm, ∼40 ns pulse width, and 10 Hz repetition rate) at different laser fluences, nitrogen background pressures and deposition substrate temperatures. When all the fabrication parameters are fixed, except for the laser fluence, the surface roughness, nitrogen content, and grain size increase with increasing laser fluence. Increasing nitrogen background pressure leads to a change in the phase structure of the NbN{sub x} films from mixed β-Nb{sub 2}N and cubic δ-NbN phases to single hexagonal β-Nb{sub 2}N. The substrate temperature affects the preferred orientation of the crystal structure. The structural and electronic, properties of NbN{sub x} deposited on Si(100) were also investigated. The NbN{sub x} films exhibited a cubic δ-NbN with a strong (111) orientation. A correlation between surface morphology, electronic, and superconducting properties was found. The observations establish guidelines for adjusting the deposition parameters to achieve the desired NbN{sub x} film morphology and phase.

  12. Spotting 2D atomic layers on aluminum nitride thin films.

    Science.gov (United States)

    Chandrasekar, Hareesh; Bharadwaj B, Krishna; Vaidyuala, Kranthi Kumar; Suran, Swathi; Bhat, Navakanta; Varma, Manoj; Srinivasan Raghavan

    2015-10-23

    Substrates for 2D materials are important for tailoring their fundamental properties and realizing device applications. Aluminum nitride (AIN) films on silicon are promising large-area substrates for such devices in view of their high surface phonon energies and reasonably large dielectric constants. In this paper epitaxial layers of AlN on 2″ Si wafers have been investigated as a necessary first step to realize devices from exfoliated or transferred atomic layers. Significant thickness dependent contrast enhancements are both predicted and observed for monolayers of graphene and MoS2 on AlN films as compared to the conventional SiO2 films on silicon, with calculated contrast values approaching 100% for graphene on AlN as compared to 8% for SiO2 at normal incidences. Quantitative estimates of experimentally measured contrast using reflectance spectroscopy show very good agreement with calculated values. Transistors of monolayer graphene on AlN films are demonstrated, indicating the feasibility of complete device fabrication on the identified layers.

  13. Combination of carbon nitride and carbon nanotubes: synergistic catalysts for energy conversion.

    Science.gov (United States)

    Gong, Yutong; Wang, Jing; Wei, Zhongzhe; Zhang, Pengfei; Li, Haoran; Wang, Yong

    2014-08-01

    Due to their versatile features and environmental friendliness, functionalized carbon materials show great potential in practical applications, especially in energy conversion. Developing carbon composites with properties that can be modulated by simply changing the ratio of the original materials is an intriguing synthetic strategy. Here, we took cyanamide and multiwalled carbon nanotubes as precursors and introduced a facile method to fabricate a series of graphitic carbon nitride/carbon nanotubes (g-C3 N4 /CNTs) composites. These composites demonstrated different practical applications with different weight ratios of the components, that is, they showed synergistic effects in optoelectronic conversion when g-C3 N4 was the main ingredient and in oxygen reduction reaction (ORR) when CNTs dominated the composites. Our experiments indicated that the high electrical conductivity of carbon nanotubes promoted the transmission of the charges in both cases.

  14. Adhesion analysis for chromium nitride thin films deposited by reactive magnetron sputtering

    Science.gov (United States)

    Rusu, F. M.; Merie, V. V.; Pintea, I. M.; Molea, A.

    2016-08-01

    The thin film industry is continuously growing due to the wide range of applications that require the fabrication of advanced components such as sensors, biological implants, micro-electromechanical devices, optical coatings and so on. The selection regarding the deposition materials, as well as the deposition technology influences the properties of the material and determines the suitability of devices for certain real-world applications. This paper is focused on the adhesion force for several chromium nitride thin films obtained by reactive magnetron sputtering. All chromium nitride thin films were deposited on a silicon substrate, the discharge current and the argon flow being kept constant. The main purpose of the paper is to determine the influence of deposition parameters on the adhesion force. Therefore some of the deposition parameters were varied in order to study their effect on the adhesion force. Experimentally, the values of the adhesion force were determined in multiple points for each sample using the spectroscopy in point mode of the atomic force microscope. The obtained values were used to estimate the surface energy of the CrN thin films based on two existing mathematical models for the adhesion force when considering the contact between two bodies.

  15. Impact of annealing temperature on the mechanical and electrical properties of sputtered aluminum nitride thin films

    Science.gov (United States)

    Gillinger, M.; Schneider, M.; Bittner, A.; Nicolay, P.; Schmid, U.

    2015-02-01

    Aluminium nitride (AlN) is a promising material for challenging sensor applications such as process monitoring in harsh environments (e.g., turbine exhaust), due to its piezoelectric properties, its high temperature stability and good thermal match to silicon. Basically, the operational temperature of piezoelectric materials is limited by the increase of the leakage current as well as by enhanced diffusion effects in the material at elevated temperatures. This work focuses on the characterization of aluminum nitride thin films after post deposition annealings up to temperatures of 1000 °C in harsh environments. For this purpose, thin film samples were temperature loaded for 2 h in pure nitrogen and oxygen gas atmospheres and characterized with respect to the film stress and the leakage current behaviour. The X-ray diffraction results show that AlN thin films are chemically stable in oxygen atmospheres for 2 h at annealing temperatures of up to 900 °C. At 1000 °C, a 100 nm thick AlN layer oxidizes completely. For nitrogen, the layer is stable up to 1000 °C. The activation energy of the samples was determined from leakage current measurements at different sample temperatures, in the range between 25 and 300 °C. Up to an annealing temperature of 700 °C, the leakage current in the thin film is dominated by Poole-Frenkel behavior, while at higher annealing temperatures, a mixture of different leakage current mechanisms is observed.

  16. Nano Indentation Inspection of the Mechanical Properties of Gold Nitride Thin Films

    Directory of Open Access Journals (Sweden)

    Armen Verdyan

    2007-10-01

    Full Text Available The morphology and the local mechanical properties of gold nitride thin films were studied by atomic force microscope (AFM. Gold nitride films were deposited for the first time on silicon substrate without any buffer layer at room temperature by reactive pulsed laser ablation deposition (RPLD. The films were fabricated on (100 Si wafers by RPLD technique in which KrF excimer laser was used to ablate a gold target in N2 atmosphere (0.1 GPa-100 Pa and ambient temperature. Scanning electron microscopy (SEM and atomic force microscopy inspections showed that the films were flat plane with rms roughness in the range of 35.1 nm-3.6 nm, depending on the deposition pressure. Rutherford backscattering spectrometry (RBS and energy dispersion spectroscopy (EDS used to detect the nitrogen concentration in the films, have revealed a composition close to Au3N. The film

  17. Influence of Thickness on Field Emission Characteristics of Nanometre Boron Nitride Thin Films

    Institute of Scientific and Technical Information of China (English)

    顾广瑞; 李英爱; 陶艳春; 何志; 李俊杰; 殷红; 李卫青; 赵永年

    2003-01-01

    Nanometre boron nitride (BN) thin films with various thickness (54-135 nm) were prepared on Si(100) by rf magnetic sputtering physical vapour deposition. The field emission characteristics of the BN thin films were measured in an ultrahigh vacuum system. A threshold electric field of 11 V/μm and the highest emission current density of 240 μA/cm2 at an electric field of 23 V/μm were obtained for the about 54-nm-thick BN film. The threshold electric field increases with increasing the thickness in the nanometre range. The Fowler-Nordheim plots show that electrons were emitted from BN to vacuum by tunnelling through the potential barrier at the surface of BN thin films.

  18. Mesoporous Metal-Containing Carbon Nitrides for Improved Photocatalytic Activities

    Directory of Open Access Journals (Sweden)

    Jie Luo

    2013-01-01

    Full Text Available Graphitic carbon nitrides (g-C3N4 have attracted increasing interest due to their unusual properties and promising applications in water splitting, heterogeneous catalysis, and organic contaminant degradation. In this study, a new method was developed for the synthesis of mesoporous Fe contained g-C3N4 (m-Fe-C3N4 photocatalyst by using SiO2 nanoparticles as hard template and dicyandiamide as precursor. The physicochemical properties of m-Fe-C3N4 were thoroughly investigated. The XRD and XPS results indicated that Fe was strongly coordinated with the g-C3N4 matrix and that the doping and mesoporous structure partially deteriorated its crystalline structure. The UV-visible absorption spectra revealed that m-Fe-C3N4 with a unique electronic structure displays an increased band gap in combination with a slightly reduced absorbance, implying that mesoporous structure modified the electronic properties of g-Fe-C3N4. The photocatalytic activity of m-Fe-C3N4 for photodegradation of Rhodamine B (RhB was much higher than that of g-Fe-C3N4, clearly demonstrating porous structure positive effect.

  19. Deposition of Low Stress Silicon Nitride Thin Film and Its Application in Surface Micromachining Device Structures

    Directory of Open Access Journals (Sweden)

    Beirong Zheng

    2013-01-01

    Full Text Available Surface machining processes are responsible for creating microstructures that reside near the surfaces of a substrate and are characterized by the fabrication of micromechanical structures from deposited thin films. These films can be selectively removed to build three-dimensional structures whose functionality typically requires that they should be freed from the planar substrate. Silicon nitride thin film is one of these important materials. In this paper, by adjusting the SiH2Cl2/NH3 gaseous ratio, low stress silicon nitride (LS SiN is deposited by the low pressure chemical vapor deposition (LPCVD process. The internal stress generally in 135 MPa has been detected using an FLX-2320 film stress tester. Based on the wide application in surface micromachining devices, the mechanical properties of LS SiN are measured by nanoindentation, giving the value of Young’s modulus of 224 GPa and the hardness of 22.5 GPa, respectively. Dry etching and wet etching are utilized to fabricate the LS SiN thin film for structural layers. The etching rate compared with normal Si3N4 film by LPCVD is demonstrated for silicon chip manufacture.

  20. Low temperature NbSi thin film thermometers on Silicon Nitride membranes for bolometer applications

    Energy Technology Data Exchange (ETDEWEB)

    Camus, Ph. E-mail: camus@csnsm.in2p3.fr; Berge, L.; Dumoulin, L.; Marnieros, S.; Torre, J.P

    2000-04-07

    We report the design of amorphous NbSi thin film bolometer thermometers on Silicon Nitride membranes. Due to the low-thermal conductivity of Si{sub 3}N{sub 4}, this material has several applications in millimeter wavelength bolometers and microcalorimetry. Compared to NTD-Ge thermometers, similar sensitivities are obtained with a 50 times lesser volume. The smallest realized films have a rectangular surface (100x400 {mu}m{sup 2}) and are 100 nm thick. Optimization of the thermometer shape, NbSi composition and electrical material contact is discussed. The goal of this development is to manufacture a complete array of bolometers by photolithography techniques.

  1. Nitridation of nanocrystalline TiO{sub 2} thin films by treatment with ammonia

    Energy Technology Data Exchange (ETDEWEB)

    Romero-Gomez, P.; Rico, V.; Espinos, J.P.; Gonzalez-Elipe, Agustin R. [Instituto de Ciencia de Materiales de Sevilla (CSIC-Univ. Sevilla), Avda. Americo Vespucio 49, 41092 Sevilla (Spain); Palgrave, Robert G. [Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA (United Kingdom); Egdell, Russell G., E-mail: russell.egdell@chem.ox.ac.u [Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA (United Kingdom)

    2011-03-31

    Nanocrystalline anatase (TiO{sub 2}) thin films prepared by a physical vapour deposition method were nitrided by annealing in flowing NH{sub 3} at temperatures ranging between 650 {sup o}C and 700 {sup o}C. It was established that there was a narrow window of temperatures which allowed both incorporation of interstitial nitrogen into the films with retention of the anatase phase without chemical reduction and preservation of the characteristic nanocrystalline morphology. These optimally modified films responded to visible light in photowetting tests and showed the ability to degrade an organic dye under visible light irradiation.

  2. Recent progress in the synthesis and characterization of amorphous and crystalline carbon nitride coatings

    CERN Document Server

    Widlow, I

    2000-01-01

    This review summarizes our most recent findings in the structure and properties of amorphous and crystalline carbon nitride coatings, synthesized by reactive magnetron sputtering. By careful control of the plasma conditions via proper choice of process parameters such as substrate bias, target power and gas pressure, one can precisely control film structure and properties. With this approach, we were able to produce amorphous carbon nitride films with controlled hardness and surface roughness. In particular, we can synthesize ultrathin (1 nm thick) amorphous carbon nitride films to be sufficiently dense and uniform that they provide adequate corrosion protection for hard disk applications. We demonstrated the strong correlation between ZrN (111) texture and hardness in CN sub x /ZrN superlattice coatings. Raman spectroscopy and near-edge X-ray absorption show the predominance of sp sup 3 -bonded carbon in these superlattice coatings.

  3. Aluminizing and subsequent nitriding of plain carbon low alloy steels for piston ring applications

    Energy Technology Data Exchange (ETDEWEB)

    Bindumadhavan, P.N.; Keng Wah, H.; Prabhakar, O. [Nanyang Technol. Univ., Singapore (Singapore). Div. of Mater. Eng.; Makesh, S. [Chemical and Nuclear Engineering Building, University of Maryland, 20783, College Park, MD (United States); Gowrishankar, N. [I P Rings Ltd., D 11/12, Industrial Estate, 603209, Maraimalainagar (India)

    2000-05-22

    Nitriding is a case hardening process that is commonly used for increasing the wear life of automotive piston rings. However, special alloy steels are required to achieve high surface hardness and nitrided case depth values required by the automotive industry. The cost of such alloy steels is one of the major components of the total cost of the nitrided piston ring. To address this issue, efforts have been directed towards development of cheaper raw materials as substitutes for nitridable steels. In this study, an attempt has been made to increase the surface hardness of two plain carbon low alloy steels by aluminizing and subsequent diffusion treatment and nitriding. The process parameters for the aluminizing operation are discussed. Results indicate that a near twofold increase in surface hardness is achievable by aluminizing followed by diffusion treatment and nitriding (580-1208 HV for EN32B steel and 650-1454 HV for 15CR3 steel). It has also been found that the nitrided case depth obtained (0.11-0.13 mm for EN32B steel and 0.10-0.14 mm for 15CR3 steel) matches well with the general requirements of the piston ring industry. The diffusion of aluminum into the alloy layer has also been discussed and the theoretical predictions were compared with actual values of Al concentration, as obtained by SEM-EDS system. It is found that Fick's law gives a fairly good prediction of the actual Al concentration profile, in spite of the complexity of the diffusion path. X-Ray diffraction studies have confirmed the presence of AlN in the alloy layer, which could be instrumental in the significant increase in surface hardness. It is proposed that aluminizing followed by diffusion treatment and nitriding of plain carbon low alloy steels could provide an alternative to the use of expensive nitridable steels for piston ring applications. (orig.)

  4. Surface morphology of titanium nitride thin films synthesized by DC reactive magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Ţǎlu Ştefan

    2015-03-01

    Full Text Available In this paper the influence of temperature on the 3-D surface morphology of titanium nitride (TiN thin films synthesized by DC reactive magnetron sputtering has been analyzed. The 3-D morphology variation of TiN thin films grown on p-type Si (100 wafers was investigated at four different deposition temperatures (473 K, 573 K, 673 K, 773 K in order to evaluate the relation among the 3-D micro-textured surfaces. The 3-D surface morphology of TiN thin films was characterized by means of atomic force microscopy (AFM and fractal analysis applied to the AFM data. The 3-D surface morphology revealed the fractal geometry of TiN thin films at nanometer scale. The global scale properties of 3-D surface geometry were quantitatively estimated using the fractal dimensions D, determined by the morphological envelopes method. The fractal dimension D increased with the substrate temperature variation from 2.36 (at 473 K to 2.66 (at 673 K and then decreased to 2.33 (at 773 K. The fractal analysis in correlation with the averaged power spectral density (surface yielded better quantitative results of morphological changes in the TiN thin films caused by substrate temperature variations, which were more precise, detailed, coherent and reproducible. It can be inferred that fractal analysis can be easily applied for the investigation of morphology evolution of different film/substrate interface phases obtained using different thin-film technologies.

  5. Supramolecular intermediates in the synthesis of polymeric carbon nitride from melamine cyanurate

    Energy Technology Data Exchange (ETDEWEB)

    Dante, Roberto C., E-mail: rcdante@yahoo.com [Facultad de Mecánica, Escuela Politécnica Nacional (EPN), Ladrón de Guevara E11-253, Quito (Ecuador); Sánchez-Arévalo, Francisco M. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de Mexico, Apdo. Postal 70-360, Cd. Universitaria, Mexico D.F. 04510 (Mexico); Chamorro-Posada, Pedro [Dpto. de Teoría de la Señal y Comunicaciones e IT, Universidad de Valladolid, ETSI Telecomunicación, Paseo Belén 15, 47011 Valladolid (Spain); Vázquez-Cabo, José [Dpto. de Teoría de la Señal y Comunicaciones, Universidad de Vigo, ETSI Telecomunicación, Lagoas Marcosende s/n, Vigo (Spain); Huerta, Lazaro [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de Mexico, Apdo. Postal 70-360, Cd. Universitaria, Mexico D.F. 04510 (Mexico); Lartundo-Rojas, Luis [Centro de Nanociencias y Micro y Nanotecnologías—IPN, Luis Enrique Erro s/n, U. Prof. Adolfo López Mateos, 07738 Ciudad de Mexico, Distrito Federal (Mexico); Santoyo-Salazar, Jaime [Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV-IPN, Apdo. Postal 14-740, Mexico D.F. 07360 (Mexico); and others

    2015-03-15

    The adduct of melamine and cyanuric acid (MCA) was used in past research to produce polymeric carbon nitride and precursors. The reaction yield was considerably incremented by the addition of sulfuric acid. The polymeric carbon nitride formation occurs around 450 °C at temperatures above the sublimation of the adduct components, which occurs around 400 °C. In this report the effect of sulfuric acid on MCA was investigated. It was found that the MCA rosette supramolecular channel structures behave as a solid solvent able to host small molecules, such as sulfuric acid, inside these channels and interact with them. Therefore, the sulfuric acid effect was found to be close to that of a solute that causes a temperature increment of the “solvent sublimation” enough to allowing the formation of polymeric carbon nitride to occur. Sulfate ions are presumably hosted in the rosette channels of MCA as shown by simulations. - Graphical abstract: The blend of melamine cyanurate and sulfuric acid behaves like a solution so that melamine cyanurate decomposition is shifted to temperatures high enough to react and form polymeric carbon nitride. - Highlights: • The adduct of melamine and cyanuric acid behaves as a solid solvent. • The blend of sulfuric acid and melamine cyanurate behaves like a solution. • Melamine cyanurate decomposition is shifted to higher temperatures by sulfuric acid. • The formation of polymeric carbon nitride occurs for these higher temperatures.

  6. Pentagonal monolayer crystals of carbon, boron nitride, and silver azide

    Energy Technology Data Exchange (ETDEWEB)

    Yagmurcukardes, M., E-mail: mehmetyagmurcukardes@iyte.edu.tr; Senger, R. T., E-mail: tugrulsenger@iyte.edu.tr [Department of Physics, Izmir Institute of Technology, 35430 Urla, Izmir (Turkey); Sahin, H.; Kang, J.; Torun, E.; Peeters, F. M. [Department of Physics, University of Antwerp, Campus Groenenborgerlaan, 2020, Antwerp (Belgium)

    2015-09-14

    In this study, we present a theoretical investigation of structural, electronic, and mechanical properties of pentagonal monolayers of carbon (p-graphene), boron nitride (p-B{sub 2}N{sub 4} and p-B{sub 4}N{sub 2}), and silver azide (p-AgN{sub 3}) by performing state-of-the-art first principles calculations. Our total energy calculations suggest feasible formation of monolayer crystal structures composed entirely of pentagons. In addition, electronic band dispersion calculations indicate that while p-graphene and p-AgN{sub 3} are semiconductors with indirect bandgaps, p-BN structures display metallic behavior. We also investigate the mechanical properties (in-plane stiffness and the Poisson's ratio) of four different pentagonal structures under uniaxial strain. p-graphene is found to have the highest stiffness value and the corresponding Poisson's ratio is found to be negative. Similarly, p-B{sub 2}N{sub 4} and p-B{sub 4}N{sub 2} have negative Poisson's ratio values. On the other hand, the p-AgN{sub 3} has a large and positive Poisson's ratio. In dynamical stability tests based on calculated phonon spectra of these pentagonal monolayers, we find that only p-graphene and p-B{sub 2}N{sub 4} are stable, but p-AgN{sub 3} and p-B{sub 4}N{sub 2} are vulnerable against vibrational excitations.

  7. Reactive DC magnetron sputtered zirconium nitride (ZrN) thin film and its characterization

    Science.gov (United States)

    Subramanian, B.; Ashok, K.; Sanjeeviraja, C.; Kuppusami, P.; Jayachandran, M.

    2008-05-01

    Zirconium nitride (ZrN) thin films were prepared by using reactive direct current (DC) magnetron sputtering onto different substrates. A good polycrystalline nature with face centered cubic structure was observed from X-ray Diffraction for ZrN thin films. The observed 'd' values from the X-ray Diffraction pattern were found to be in good agreement with the standard 'd' values (JCPDS-89-5269). An emission peak is observed at 587nm from Photoluminescence studies for the excitation at 430nm. The resistivity value (ρ) of 2.1798 (μΩ cm) was observed. ZrN has high wear resistance and low coefficient of friction. A less negative value of Ecorr and lower value of Icorr observed for ZrN / Mild Steel (MS) clearly confirm the better corrosion resistance than the bare substrate. Also the higher Rct value and lower Cdl value was observed for ZrN / MS from Nyquist - plot.

  8. Carbon nanotube based transparent conductive thin films.

    Science.gov (United States)

    Yu, X; Rajamani, R; Stelson, K A; Cui, T

    2006-07-01

    Carbon nanotube (CNT) based optically transparent and electrically conductive thin films are fabricated on plastic substrates in this study. Single-walled carbon nanotubes (SWNTs) are chemically treated with a mixture of concentrated sulfuric acid and nitric acid before being dispersed in aqueous surfactant-contained solutions. SWNT thin films are prepared from the stable SWNT solutions using wet coating techniques. The 100 nm thick SWNT thin film exhibits a surface resistivity of 6 kohms/square nanometer with an average transmittance of 88% on the visible light range, which is three times better than the films prepared from the high purity as-received SWNTs.

  9. Impact of annealing temperature on the mechanical and electrical properties of sputtered aluminum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gillinger, M.; Schneider, M.; Bittner, A.; Schmid, U. [Institute of Sensor and Actuator Systems, Vienna University of Technology, Vienna 1040 (Austria); Nicolay, P. [CTR Carinthian Tech Research AG, Villach 9524 (Austria)

    2015-02-14

    Aluminium nitride (AlN) is a promising material for challenging sensor applications such as process monitoring in harsh environments (e.g., turbine exhaust), due to its piezoelectric properties, its high temperature stability and good thermal match to silicon. Basically, the operational temperature of piezoelectric materials is limited by the increase of the leakage current as well as by enhanced diffusion effects in the material at elevated temperatures. This work focuses on the characterization of aluminum nitride thin films after post deposition annealings up to temperatures of 1000 °C in harsh environments. For this purpose, thin film samples were temperature loaded for 2 h in pure nitrogen and oxygen gas atmospheres and characterized with respect to the film stress and the leakage current behaviour. The X-ray diffraction results show that AlN thin films are chemically stable in oxygen atmospheres for 2 h at annealing temperatures of up to 900 °C. At 1000 °C, a 100 nm thick AlN layer oxidizes completely. For nitrogen, the layer is stable up to 1000 °C. The activation energy of the samples was determined from leakage current measurements at different sample temperatures, in the range between 25 and 300 °C. Up to an annealing temperature of 700 °C, the leakage current in the thin film is dominated by Poole-Frenkel behavior, while at higher annealing temperatures, a mixture of different leakage current mechanisms is observed.

  10. Carbon nanofiber growth on thin rhodium layers

    NARCIS (Netherlands)

    Chinthaginjala, J.K.; Unnikrishnan, S.; Smithers, M.A.; Kip, G.A.M.; Lefferts, L.

    2012-01-01

    A thinlayer of carbon nanofibers (CNFs) was synthesized on a thin polycrystalline rhodium (Rh) metal layer by decomposing ethylene in the presence of hydrogen. Interaction of Rh crystals with carbon results in fragmentation and formation of Rh-nanoparticles, facilitating CNF growth. CNFs are immobil

  11. Synthesis of graphitic carbon nitride through pyrolysis of melamine and its electrocatalysis for oxygen reduction reaction

    Institute of Scientific and Technical Information of China (English)

    He-Sheng Zhai; Lei Cao; Xing-Hua Xia

    2013-01-01

    Graphitic carbon nitride (g-C3N4) was synthesized via direct pyrolysis of melamine and its electrocatalysis toward oxygen reduction reaction was studied.The morphology and structures of the products were characterized by scanning electron microscope and X-ray powder diffractometer.It was found that higher pyrolysis temperature resulted in more perfect crystalline structure of the graphitic carbon nitride product.Electrochemical characterizations show that the g-C3N4 has electrocatalytic activity toward ORR through a two-step and two-electron process.

  12. Synthesis and photocatalytic performance of europium-doped graphitic carbon nitride

    Institute of Scientific and Technical Information of China (English)

    徐冬冬; 李晓妮; 刘娟; 黄浪欢

    2013-01-01

    Europium-doped graphitic carbon nitride was synthesized by an easy method and characterized by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-Vis DRS), Fourier transform infrared spectroscopy (FTIR), photolu-minescence spectra (PL) and transmission electron microscopy (TEM). The effect of dopant concentration on the rate of photocata-lytic degradation was investigated through degrading methylene blue aqueous solution. The results indicated that the europium-doped samples all possessed increased photocatalytic activity and the optimal europium content was 0.38 wt.%. Moreover, a possible photo-catalytic mechanism for the europium-doped graphitic carbon nitride was proposed.

  13. Biomolecule-assisted synthesis of carbon nitride and sulfur-doped carbon nitride heterojunction nanosheets: An efficient heterojunction photocatalyst for photoelectrochemical applications.

    Science.gov (United States)

    Tao, Hua Bing; Yang, Hong Bin; Chen, Jiazang; Miao, Jianwei; Liu, Bin

    2014-01-01

    A biomolecule-assisted pyrolysis method has been developed to synthesize sulfur-doped graphitic carbon nitride (CNS) nanosheets. During the synthesis, sulfur could be introduced as a dopant into the lattice of carbon nitride (CN). Sulfur doping changed the texture as well as relative band positions of CN. By growing CN on preformed sulfur-doped CN nanosheets, composite CN/CNS heterojunction nanosheets were constructed, which significantly enhanced the photoelectrochemical performance as compared with various control counterparts including CN, CNS and physically mixed CN and CNS (CN+CNS). The enhanced photoelectrochemical performance of CN/CNS heterojunction nanosheets could be ascribed to the efficient separation of photoexcited charge carriers across the heterojunction interface. The strategy of designing and preparing CN/CNS heterojunction photocatalysts in this work can open up new directions for the construction of all CN-based heterojunction photocatalysts.

  14. Effects of Nitride on the Tribological Properties of the Low Carbon Alloy Steel

    Directory of Open Access Journals (Sweden)

    Yuh-Ping Chang

    2013-01-01

    Full Text Available The technology of composite heat treatment is used popularly for low friction and wear resistance of drive elements. A large number of papers about the heat treatment technology had been proposed. Especially, the nitride treatment has been used widely for the purpose of wear resistance and low friction in the industry. Therefore, the self-developed vertical ball/disk friction tester with the measurement system was used to study the effects of nitride on the tribological properties of the low carbon alloy steel—SCM415— in this study. The experiments were conducted under dry and severe wear conditions. The variations of friction coefficient and surface magnetization were simultaneously recorded during dynamic friction process. After each test, the microstructures of the wear particles were observed and analyzed under a SEM, and the depth of wear track is measured by means of a surface tester. According to the experimental results, the wear resistance of the specimens with carburizing-nitride is significantly larger than the case of nitride-carburizing. Moreover, the surface magnetization was especially larger for the case of nitride-carburizing. As a result, the wear particles always stay in the interfaces and the wear mechanism becomes complex. Therefore, it is necessary to put nitride after carburizing for the composite heat treatments.

  15. Structural investigation of two carbon nitride solids produced by cathodic arc deposition and nitrogen implantation

    Energy Technology Data Exchange (ETDEWEB)

    Merchant, A.R.; McCulloch, D.; McKenzie, D.R.; Yin, Y.; Gerstner, E.G. [New South Wales Univ., Kensington, NSW (Australia)

    1996-12-31

    Carbon nitride materials have been the focus of research efforts worldwide. Most materials studied have been amorphous, with only a few groups claiming to have found a crystalline material. In this paper, carbon nitride materials prepared by two different techniques are analysed, and found to be remarkably similar in bonding and structure. The materials appear to have a primarily sp{sup 2} bonded carbon structure with a lower bond length than found in an amorphous carbon. This is explained by nitrogen substituting into `rings` to a saturation level of about one nitrogen per three carbon atoms. No evidence was found for a crystalline structure of formula C{sub 3}N{sub 4}, or any amorphous derivative of it. 16 refs., 1 tab., 5 figs.

  16. Substrate-dependent thermal conductivity of aluminum nitride thin-films processed at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Belkerk, B. E., E-mail: boubakeur.belkerk@gmail.com [Institut des Matériaux Jean Rouxel (IMN), University of Nantes, 2 rue de la Houssinière BP 32229, 44322 Nantes cedex 3 (France); Universités de Constantine, Laboratoire Microsystèmes et Instrumentation (LMI), Université Constantine 1, Faculté des Sciences de la Technologie, Route de Ain El Bey, Constantine 25017 (Algeria); Bensalem, S.; Soussou, A.; Carette, M.; Djouadi, M. A.; Scudeller, Y. [Institut des Matériaux Jean Rouxel (IMN), University of Nantes, 2 rue de la Houssinière BP 32229, 44322 Nantes cedex 3 (France); Al Brithen, H. [Department of Physics and Astronomy at College of Science, King Saud University at Riyadh (Saudi Arabia)

    2014-12-01

    In this paper, we report on investigation concerning the substrate-dependent thermal conductivity (k) of Aluminum Nitride (AlN) thin-films processed at low temperature by reactive magnetron sputtering. The thermal conductivity of AlN films grown at low temperature (<200 °C) on single-crystal silicon (Si) and amorphous silicon nitride (SiN) with thicknesses ranging from 100 nm to 4000 nm was measured with the transient hot-strip technique. The k values for AlN films on SiN were found significantly lower than those on Silicon consistently with their microstructures revealed by X-ray diffraction, high resolution scanning electron microscopy, and transmission electron microscopy. The change in k was due to the thermal boundary resistance found to be equal to 10 × 10{sup −9} Km{sup 2}W{sup −1} on SiN against 3.5 × 10{sup −9} Km{sup 2}W{sup −1} on Si. However, the intrinsic thermal conductivity was determined with a value as high as 200 Wm{sup −1}K{sup −1} whatever the substrate.

  17. Reactive magnetron sputter deposition of superconducting niobium titanium nitride thin films with different target sizes

    CERN Document Server

    Bos, B G C; Haalebos, E A F; Gimbel, P M L; Klapwijk, T M; Baselmans, J J A; Endo, A

    2016-01-01

    The superconducting critical temperature (Tc>15 K) of niobium titanium nitride (NbTiN) thin films allows for low-loss circuits up to 1.1 THz, enabling on-chip spectroscopy and multi-pixel imaging with advanced detectors. The drive for large scale detector microchips is demanding NbTiN films with uniform properties over an increasingly larger area. This article provides an experimental comparison between two reactive d.c. sputter systems with different target sizes: a small target (100 mm diameter) system and a large target (127 mm x 444.5 mm) one, with the aim of improving the film uniformity using the large target system. We focus on the Tc of the films and I-V characteristics of the sputter plasma, and we find that both systems are capable of depositing films with Tc>15 K. We find that these films are deposited within the transition from metallic to compound sputtering, at the point where target nitridation most strongly depends on nitrogen flow. Key in the deposition optimization is to increase the system'...

  18. Thermal stability of tungsten sub-nitride thin film prepared by reactive magnetron sputtering

    Science.gov (United States)

    Zhang, X. X.; Wu, Y. Z.; Mu, B.; Qiao, L.; Li, W. X.; Li, J. J.; Wang, P.

    2017-03-01

    Tungsten sub-nitride thin films deposited on silicon samples by reactive magnetron sputtering were used as a model system to study the phase stability and microstructural evolution during thermal treatments. XRD, SEM&FIB, XPS, RBS and TDS were applied to investigate the stability of tungsten nitride films after heating up to 1473 K in vacuum. At the given experimental parameters a 920 nm thick crystalline film with a tungsten and nitrogen stoichiometry of 2:1 were achieved. The results showed that no phase and microstructure change occurred due to W2N film annealing in vacuum up to 973 K. Heating up to 1073 K led to a partial decomposition of the W2N phase and the formation of a W enrichment layer at the surface. Increasing the annealing time at the same temperature, the further decomposition of the W2N phase was negligible. The complete decomposition of W2N film happened as the temperature reached up to 1473 K.

  19. Thin Film Formation of Gallium Nitride Using Plasma-Sputter Deposition Technique

    Directory of Open Access Journals (Sweden)

    R. Flauta

    2003-06-01

    Full Text Available The formation of gallium nitride (GaN thin film using plasma-sputter deposition technique has beenconfirmed. The GaN film deposited on a glass substrate at an optimum plasma condition has shown x-raydiffraction (XRD peaks at angles corresponding to that of (002 and (101 reflections of GaN. The remainingmaterial on the sputtering target exhibited XRD reflections corresponding to that of bulk GaN powder. Toimprove the system’s base pressure, a new UHV compatible system is being developed to minimize theimpurities in residual gases during deposition. The sputtering target configuration was altered to allow themonitoring of target temperature using a molybdenum (Mo holder, which is more stable against Gaamalgam formation than stainless steel.

  20. Imaging and identifying defects in nitride semiconductor thin films using a scanning electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Naresh-Kumar, G.; Hourahine, B.; Trager-Cowan, C. [Department of Physics, SUPA, University of Strathclyde, Glasgow (United Kingdom); Vilalta-Clemente, A.; Ruterana, P. [CIMAP UMR 6252 CNRS-ENSICAEN-CEA-UCBN, 6, Caen (France); Gamarra, P.; Lacam, C.; Tordjman, M.; Di Forte-Poisson, M.A. [Thales Research and Technology, III-V Lab, Marcoussis (France); Parbrook, P.J. [Department of Electrical and Electronic Engineering, University of Sheffield (United Kingdom); Day, A.P. [Aunt Daisy Scientific Ltd., Claremont House, High St, Lydney (United Kingdom); England, G. [K. E. Developments Ltd., Cambridge (United Kingdom)

    2012-03-15

    We describe the use of electron channelling contrast imaging (ECCI) - in a field emission scanning electron microscope (SEM) - to reveal and identify defects in nitride semiconductor thin films. In ECCI changes in crystallographic orientation, or changes in lattice constant due to local strain, are revealed by changes in grey scale in an image constructed by monitoring the intensity of backscattered electrons (BSEs) as an electron beam is scanned over a suitably oriented sample. Extremely small orientation changes are detectable, enabling small angle tilt and rotation boundaries and dislocations to be imaged. Images with a resolution of tens of nanometres are obtainable with ECCI. In this paper, we describe the use of ECCI with TEM to determine threading dislocation densities and types in InAlN/GaN heterostructures grown on SiC and sapphire substrates. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Investigation of hexagonal boron nitride as an atomically thin corrosion passivation coating in aqueous solution

    Science.gov (United States)

    Zhang, Jing; Yang, Yingchao; Lou, Jun

    2016-09-01

    Hexagonal boron nitride (h-BN) atomic layers were utilized as a passivation coating in this study. A large-area continuous h-BN thin film was grown on nickel foil using a chemical vapor deposition method and then transferred onto sputtered copper as a corrosion passivation coating. The corrosion passivation performance in a Na2SO4 solution of bare and coated copper was investigated by electrochemical methods including cyclic voltammetry (CV), Tafel polarization and electrochemical impedance spectroscopy (EIS). CV and Tafel analysis indicate that the h-BN coating could effectively suppress the anodic dissolution of copper. The EIS fitting result suggests that defects are the dominant leakage source on h-BN films, and improved anti-corrosion performances could be achieved by further passivating these defects.

  2. Characteristics of Disorder and Defect in Hydrogenated Amorphous Silicon Nitride Thin Films Containing Silicon Nanograins

    Institute of Scientific and Technical Information of China (English)

    DING Wen-ge; YU Wei; ZHANG Jiang-yong; HAN Li; FU Guang-sheng

    2006-01-01

    The hydrogenated amorphous silicon nitride (SiNx) thin films embedded with nano-structural silicon were prepared and the microstructures at the interface of silicon nano-grains/SiNx were identified by the optical absorption and Raman scattering measurements. Characterized by the exponential tail of optical absorption and the band-width of the Raman scattering TO mode, the disorder in the interface region increases with the gas flow ratio increasing. Besides, as reflected by the sub-gap absorption coefficients, the density of interface defect states decreases, which can be attributed to the structural mismatch in the interface region and also the changes of hydrogen content in the deposited films. Additional annealing treatment results in a significant increase of defects and degree of disorder, for which the hydrogen out-diffusion in the annealing process would be responsible.

  3. Synthesis of aluminum nitride thin films and their potential applications in solid state thermoluminescence dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Choudhary, R.K., E-mail: rupeshkr@barc.gov.in [Materials Processing Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Soni, A. [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mishra, P. [Materials Processing Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Mishra, D.R.; Kulkarni, M.S. [Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2014-11-15

    In this work, aluminum nitride thin films were deposited on Si (1 1 1) substrate by magnetron sputtering. The obtained film was studied for thermoluminescence after irradiating it to various doses of γ-rays. Thermoluminescence measurement showed photon emission at an irradiation dose of 100 Gy or higher. Deconvolution of the experimental glow curve indicated that recombination centers in AlN were present below 2 eV trap depth. Irradiated AlN films showed less than 2% fading of TL signals on storage for 1 month in dark conditions and for the same period, light induced fading was also less than 4%. A linear variation of integrated thermoluminescence counts with absorbed dose has been observed up to an irradiation dose of 10 kGy. The deposited film was also characterized by grazing incidence X-ray diffraction, atomic force microscopy and secondary ion mass spectroscopy. Grazing incidence X-ray diffraction measurement of the obtained film has shown formation of polycrystalline wurtzite AlN having preferred orientation along (1 0 0) plane. Secondary ion mass spectroscopy analysis revealed the presence of oxygen in the film. - Highlights: • TL emission in sputter deposited AlN thin films when irradiated to gamma rays. • Linear dose–response up to 10 kGy irradiation dose. • Negligible fading of TL signals on storage. • Nominal light induced TL fading. • AlN thin films found potentially suitable for high dose dosimetry applications.

  4. Stoichiometry and thickness dependence of superconducting properties of niobium nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Beebe, Melissa R., E-mail: mrbeebe@email.wm.edu; Beringer, Douglas B.; Burton, Matthew C.; Yang, Kaida; Lukaszew, R. Alejandra [Department of Physics, The College of William & Mary, Small Hall, 300 Ukrop Way, Williamsburg, Virginia 23185 (United States)

    2016-03-15

    The current technology used in linear particle accelerators is based on superconducting radio frequency (SRF) cavities fabricated from bulk niobium (Nb), which have smaller surface resistance and therefore dissipate less energy than traditional nonsuperconducting copper cavities. Using bulk Nb for the cavities has several advantages, which are discussed elsewhere; however, such SRF cavities have a material-dependent accelerating gradient limit. In order to overcome this fundamental limit, a multilayered coating has been proposed using layers of insulating and superconducting material applied to the interior surface of the cavity. The key to this multilayered model is to use superconducting thin films to exploit the potential field enhancement when these films are thinner than their London penetration depth. Such field enhancement has been demonstrated in MgB{sub 2} thin films; here, the authors consider films of another type-II superconductor, niobium nitride (NbN). The authors present their work correlating stoichiometry and superconducting properties in NbN thin films and discuss the thickness dependence of their superconducting properties, which is important for their potential use in the proposed multilayer structure. While there are some previous studies on the relationship between stoichiometry and critical temperature T{sub C}, the authors are the first to report on the correlation between stoichiometry and the lower critical field H{sub C1}.

  5. Optical properties of hexagonal boron nitride thin films deposited by radio frequency bias magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    Deng Jin-Xiang; Zhang Xiao-Kang; Yao Qian; Wang Xu-Yang; Chen Guang-Hua; He De-Yan

    2009-01-01

    The optical properties of hexagonal boron nitride (h-BN) thin films were studied in this paper. The films were characterized by Fourier transform infrared spectroscopy,UV-visible transmittance and reflection spectra,h-BN thin films with a wide optical band gap Eg (5.86 eV for the as-deposited film and 5.97 eV for the annealed film) approaching h-BN single crystal were successfully prepared by radio frequency (RF) bias magnetron sputtering and post-deposition annealing at 970 K. The optical absorption behaviour of h-BN films accords with the typical optical absorption characteristics of amorphous materials when fitting is made by the Urbach tail model. The annealed film shows satisfactory structure stability. However,high temperature still has a significant effect on the optical absorption properties,refractive index n,and optical conductivity σ of h-BN thin films. The blue-shift of the optical absorption edge and the increase of Eg probably result from stress relaxation in the film under high temperatures. In addition,it is found that the refractive index clearly exhibits different trends in the visible and ultraviolet regions. Previous calculational results of optical conductivity of h-BN films are confirmed in our experimental results.

  6. High temperature performance of sputter-deposited piezoelectric aluminum nitride thin films

    Science.gov (United States)

    Gillinger, M.; Schneider, M.; Bittner, A.; Nicolay, P.; Schmid, U.

    2015-05-01

    Aluminum nitride (AlN) is a promising material for sensor applications in harsh environments such as turbine exhausts or thermal power plants due to its piezoelectric properties, good thermal match to silicon and high temperature stability. Typically, the usage of piezoelectric materials in high temperature is limited by the Curie-temperature, the increase of the leakage current as well as by enhanced diffusion effects in the materials. In order to exploit the high temperature potential of AlN thin films, post deposition annealing experiments up to 1000°C in both oxygen and nitrogen gas atmospheres for 2 h were performed. X-ray diffraction measurements indicate that the thin films are chemically stable in a pure oxygen atmosphere for 2 h at annealing temperatures of up to 900°C. After a 2 h annealing step at 1000°C in pure oxygen. However, a 100 nm thin AlN film is completely oxidized. In contrast, the layer is stable up to 1000°C in pure nitrogen atmosphere. The surface topology changes significantly at annealing temperatures above 800°C independent of annealing atmosphere. The surface roughness is increased by about one order of magnitude compared to the "as deposited" state. This is predominantly attributed to recrystallization processes occurring during high temperature loading. Up to an annealing temperature of 700°C, a Poole-Frenkel conduction mechanism dominates the leakage current characteristics. Above, a mixture of different leakage current mechanisms is observed.

  7. Hexagonal boron nitride thin film thermal neutron detectors with high energy resolution of the reaction products

    Energy Technology Data Exchange (ETDEWEB)

    Doan, T.C.; Majety, S.; Grenadier, S.; Li, J.; Lin, J.Y.; Jiang, H.X., E-mail: hx.jiang@ttu.edu

    2015-05-21

    Hexagonal boron nitride (h-BN) is highly promising for solid-state thermal neutron detector applications due to its many outstanding physical properties, especially its very large thermal neutron capture cross-section (~3840 barns for {sup 10}B), which is several orders of magnitude larger than those of most other isotopes. The focus of the present work is to carry out studies on h-BN thin film and detector properties to lay the foundation for the development of a direct-conversion solid-state thermal neutron detector with high sensitivity. The measured carrier mobility-lifetime (μτ) product of h-BN thin films grown on sapphire substrates is 2.83×10{sup −7} cm{sup 2}/V for electrons and holes, which is comparable to the value of about 10{sup −7} cm{sup 2}/V for GaN thin films grown on sapphire. Detectors based on h-BN thin films were fabricated and the nuclear reaction product pulse height spectra were measured. Under a bias of 20 V, very narrow individual peaks corresponding to the reaction product energies of α and Li particles as well as the sum peaks have been clearly resolved in the pulse height spectrum for the first time by a B-based direct-conversion semiconductor neutron detector. Our results indicate that h-BN thin film detectors possess unique advantages including small size, low weight, portability, low voltage operation and high energy resolution of specific reaction products.

  8. Carbon Nanotube Thin-Film Antennas.

    Science.gov (United States)

    Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

    2016-08-17

    Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed.

  9. High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, R.; Pagan, V.R.; Kabulski, A.; Kuchibhatla, S.; Harman, J.; Kasarla, K.R.; Rodak, L.E.; Hensel, J.P.; Famouri, P.; Korakakis, D.

    2008-01-01

    A Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPE-grown Aluminum Nitride (AlN) thin films at temperatures up to 1000°C in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000°C. Below 1000°C the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature [1]. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300°C for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300°C possibly due to stress in the film.

  10. High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films

    Energy Technology Data Exchange (ETDEWEB)

    R. Farrell; V. R. Pagan; A. Kabulski; Sridhar Kuchibhatl; J. Harman; K. R. Kasarla; L. E. Rodak; P. Famouri; J. Peter Hensel; D. Korakakis

    2008-05-01

    A Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPE grown Aluminum Nitride (AlN) thin films at temperatures up to 1000°C in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000°C. Below 1000°C the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature [1]. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300°C for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300°C possibly due to stress in the film.

  11. Atomic-Resolution Observations of Semi-Crystalline IntegranularThin Films in Silicon Nitride

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, Alexander; Idrobo, Juan C.; Cinibulk, Michael K.; Kisielowski, Christian; Browning, Nigel D.; Ritchie, Robert O.

    2005-08-01

    The thin intergranular phase in a silicon nitride (Si3N4)ceramic, which has been regarded for decades as having an entirely amorphous morphology, is shown to have a semi-crystalline structure. Using two different but complementary high-resolution electron microscopy methods, the intergranular atomic structure was directly imaged at the atomic level. These high-resolution images show that the atomic arrangement of the dopand element cerium takes very periodic positions not only along the interface between the intergranular phase and the Si3N4 matrix grains, but it arranges in a semi-crystalline structure that spans the entire width of the intergranular phase between two adjacent matrix grains, in principle connecting the two separate matrix grains. The result will have implications on the approach of understanding the materials properties of ceramics, most significantly on the mechanical properties and the associated computational modeling of the atomic structure of the thin intergranular phase in Si3N4 ceramics.

  12. Graphene-analogue carbon nitride: novel exfoliation synthesis and its application in photocatalysis and photoelectrochemical selective detection of trace amount of Cu²⁺.

    Science.gov (United States)

    Xu, Hui; Yan, Jia; She, Xiaojie; Xu, Li; Xia, Jiexiang; Xu, Yuanguo; Song, Yanhua; Huang, Liying; Li, Huaming

    2014-01-01

    Graphene-analogue nanostructures defined as a new kind of promising materials with unique electronic, surface and optical properties have received much attention in the fields of catalysis, energy storage, sensing and electronic devices. Due to the distinctive structure characteristics of the graphene-analogue materials, they brought novel and amazing properties. Herein, graphene-analogue carbon nitride (GA-C₃N₄) was synthesized by high-yield, large-scale thermal exfoliation from the graphitic C₃N₄-based intercalation compound. Graphene-analogue carbon nitride exhibited 2D thin-layer structure with 6-9 atomic thickness, a high specific surface area of 30.1 m(2) g(-1), increased photocurrent responses and improved electron transport ability, which could give rise to enhancing the photocatalytic activity and stability. The graphene-analogue carbon nitride had a new features that could make it suitable as a sensor for Cu(2+) determination. So GA-C₃N₄ is a new but promising candidate for heavy metal ions (Cu(2+)) determination in water environment. The photocatalytic mechanism and photoelectrochemical selective sensing of Cu(2+) were also discussed.

  13. Nanotribological Behavior of Carbon Based Thin Films: Friction and Lubricity Mechanisms at the Nanoscale

    Directory of Open Access Journals (Sweden)

    Costas A. Charitidis

    2013-04-01

    Full Text Available The use of materials with very attractive friction and wear properties has raised much attention in research and industrial sectors. A wide range of tribological applications, including rolling and sliding bearings, machining, mechanical seals, biomedical implants and microelectromechanical systems (MEMS, require thin films with high mechanical strength, chemical inertness, broad optical transparency, high refractive index, wide bandgap excellent thermal conductivity and extremely low thermal expansion. Carbon based thin films like diamond, diamond-like carbon, carbon nitride and cubic boron nitride known as “super-hard” material have been studied thoroughly as the ideal candidate for tribological applications. In this study, the results of experimental and simulation works on the nanotribological behavior of carbon films and fundamental mechanisms of friction and lubricity at the nano-scale are reviewed. The study is focused on the nanomechanical properties and analysis of the nanoscratching processes at low loads to obtain quantitative analysis, the comparison obtain quantitative analysis, the comparison of their elastic/plastic deformation response, and nanotribological behavior of the a-C, ta-C, a-C:H, CNx, and a-C:M films. For ta-C and a-C:M films new data are presented and discussed.

  14. Effects of carbon doping on the electronic properties of boron nitride nanotubes: Tight binding calculation

    Science.gov (United States)

    Chegel, Raad

    2016-10-01

    The electronic properties of pure and carbon doped zigzag and armchair Boron Nitride Nanotubes (BNNTs) have been investigated based on tight binding formalism. It was found that the band gap is reduced due to substitution of Boron or Nitrogen atoms by carbon atoms and the doping effects of B- and N-substituted BNNTs are different. The applied electric field converts the carbon doped BNNTs from semiconductor to metal. The gap energy reduction shows an identical dependence to electric field and doping for both armchair and zigzag carbon doped BNNTs. Our results indicate that the band gap of carbon doped BNNTs is a function of the Impurity concentration, electric field strength and the direction between the electric field and dopant location. The band gap for C-doped BNNTs with four carbon atoms decreases linearly but for two carbon atoms, it is constant at first then decreases linearly.

  15. Filtered pulsed cathodic arc deposition of fullerene-like carbon and carbon nitride films

    Science.gov (United States)

    Tucker, Mark D.; Czigány, Zsolt; Broitman, Esteban; Näslund, Lars-Åke; Hultman, Lars; Rosen, Johanna

    2014-04-01

    Carbon and carbon nitride films (CNx, 0 ≤ x ≤ 0.26) were deposited by filtered pulsed cathodic arc and were investigated using transmission electron microscopy and X-ray photoelectron spectroscopy. A "fullerene-like" (FL) structure of ordered graphitic planes, similar to that of magnetron sputtered FL-CNx films, was observed in films deposited at 175 °C and above, with N2 pressures of 0 and 0.5 mTorr. Higher substrate temperatures and significant nitrogen incorporation are required to produce similar FL structure by sputtering, which may, at least in part, be explained by the high ion charge states and ion energies characteristic of arc deposition. A gradual transition from majority sp3-hybridized films to sp2 films was observed with increasing substrate temperature. High elastic recovery, an attractive characteristic mechanical property of FL-CNx films, is evident in arc-deposited films both with and without nitrogen content, and both with and without FL structure.

  16. Filtered pulsed cathodic arc deposition of fullerene-like carbon and carbon nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, Mark D., E-mail: martu@ifm.liu.se; Broitman, Esteban; Näslund, Lars-Åke; Hultman, Lars; Rosen, Johanna [Thin Film Physics Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-58183 Linköping (Sweden); Czigány, Zsolt [Institute for Technical Physics and Materials Science, RCNS, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary)

    2014-04-14

    Carbon and carbon nitride films (CN{sub x}, 0 ≤ x ≤ 0.26) were deposited by filtered pulsed cathodic arc and were investigated using transmission electron microscopy and X-ray photoelectron spectroscopy. A “fullerene-like” (FL) structure of ordered graphitic planes, similar to that of magnetron sputtered FL-CN{sub x} films, was observed in films deposited at 175 °C and above, with N{sub 2} pressures of 0 and 0.5 mTorr. Higher substrate temperatures and significant nitrogen incorporation are required to produce similar FL structure by sputtering, which may, at least in part, be explained by the high ion charge states and ion energies characteristic of arc deposition. A gradual transition from majority sp{sup 3}-hybridized films to sp{sup 2} films was observed with increasing substrate temperature. High elastic recovery, an attractive characteristic mechanical property of FL-CN{sub x} films, is evident in arc-deposited films both with and without nitrogen content, and both with and without FL structure.

  17. Catalytic self-assembly preparation and characterization of carbon nitride nanotubes by a solvothermal method

    Institute of Scientific and Technical Information of China (English)

    HUANG Fuling; CAO Chuanbao; ZHU Hesun

    2005-01-01

    A solvothermal reaction of anhydrous C3N3Cl3 and sodium using cyclohexane as solvent and NiCl2 as catalyst precursor has been carried out to prepare carbon nitride nanotubes successfully at 230℃ and 1.8 MPa. The carbon nitride nanotubes were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), electron energy loss spectrum (EELS) and Raman spectrum. SEM and TEM results indicated that the tubes have a length of 20-30 μm, a uniform outer diameter of about 50-60 nm, an inner diameter of 30-40 nm and are highly ordered assembled as bundles. The EELS measurement indicated that the ratio of N/C was about 1.00. The ED and XRD analyses revealed that the tube may have a new CN crystalline structure. The growth mechanism of nanotubes was discussed.

  18. Gallium nitride based thin films for photon and particle radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, Markus

    2012-07-23

    Ionization chambers have been used since the beginning of the 20th century for measuring ionizing radiation and still represent the ''gold standard'' in dosimetry. However, since the sensitivity of the devices is proportional to the detection volume, ionization chambers are not common in numerous medical applications, such as imaging. In these fields, spatially resolved dose information is, beside film-systems, usually measured with scintillators and photo-multipliers, which is a relatively complex and expensive technique. For thus much effort has been focused on the development of novel detection systems in the last decades and especially in the last few years. Examples include germanium or silicon photoconductive detectors, MOSFETs, and PIN-diodes. Although for these systems, miniaturization for spatially resolved detection is possible, they suffer from a range of disadvantages. Characteristics such as poor measurement stability, material degradation, and/or a limited measurement range prevent routine application of these techniques in medical diagnostic devices. This work presents the development and evaluation of gallium nitride (GaN) thin films and heterostructures to validate their application in x-ray detection in the medical regime. Furthermore, the impact of particle radiation on device response was investigated. Although previous publications revealed relatively low energy absorption of GaN, it is possible to achieve very high signal amplification factors inside the material due to an appropriate sensor configuration, which, in turn, compensates the low energy absorption. Thus, gallium nitride can be used as a photo-conductor with ohmic contacts. The conductive volume of the sensor changes in the presence of external radiation, which results in an amplified measurement signal after applying a bias voltage to the device. Experiments revealed a sensitivity of the device between air kerma rates of 1 {mu}Gy/s and 20 mGy/s. In this range

  19. Facile fabrication of boron nitride nanosheets-amorphous carbon hybrid film for optoelectronic applications

    KAUST Repository

    Wan, Shanhong

    2015-01-01

    A novel boron nitride nanosheets (BNNSs)-amorphous carbon (a-C) hybrid film has been deposited successfully on silicon substrates by simultaneous electrochemical deposition, and showed a good integrity of this B-C-N composite film by the interfacial bonding. This synthesis can potentially provide the facile control of the B-C-N composite film for the potential optoelectronic devices. This journal is

  20. 2D to 3D transition of polymeric carbon nitride nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Chamorro-Posada, Pedro [Dpto. de Teoría de la Señal y Comunicaciones e IT, Universidad de Valladolid, ETSI Telecomunicación, Paseo Belén 15, 47011 Valladolid (Spain); Vázquez-Cabo, José [Dpto. de Teoría de la Señal y Comunicaciones, Universidad de Vigo, ETSI Telecomunicación, Lagoas Marcosende s/n, Vigo (Spain); Sánchez-Arévalo, Francisco M. [Instituto de Investigaciones en Materiales (IIM), Universidad Nacional Autónoma de México, Apdo. Postal 70–360, Cd. Universitaria, México D.F. 04510 (Mexico); Martín-Ramos, Pablo [Dpto. de Teoría de la Señal y Comunicaciones e IT, Universidad de Valladolid, ETSI Telecomunicación, Paseo Belén 15, 47011 Valladolid (Spain); Laboratorio de Materiales Avanzados (Advanced Materials Laboratory) ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Martín-Gil, Jesús; Navas-Gracia, Luis M. [Laboratorio de Materiales Avanzados (Advanced Materials Laboratory) ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Dante, Roberto C., E-mail: rcdante@yahoo.com [Laboratorio de Materiales Avanzados (Advanced Materials Laboratory) ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain)

    2014-11-15

    The transition from a prevalent turbostratic arrangement with low planar interactions (2D) to an array of polymeric carbon nitride nanosheets with stronger interplanar interactions (3D), occurring for samples treated above 650 °C, was detected by terahertz-time domain spectroscopy (THz-TDS). The simulated 3D material made of stacks of shifted quasi planar sheets composed of zigzagged polymer ribbons, delivered a XRD simulated pattern in relatively good agreement with the experimental one. The 2D to 3D transition was also supported by the simulation of THz-TDS spectra obtained from quantum chemistry calculations, in which the same broad bands around 2 THz and 1.5 THz were found for 2D and 3D arrays, respectively. This transition was also in accordance with the tightening of the interplanar distance probably due to an interplanar π bond contribution, as evidenced also by a broad absorption around 2.6 eV in the UV–vis spectrum, which appeared in the sample treated at 650 °C, and increased in the sample treated at 700 °C. The band gap was calculated for 1D and 2D cases. The value of 3.374 eV for the 2D case is, within the model accuracy and precision, in a relative good agreement with the value of 3.055 eV obtained from the experimental results. - Graphical abstract: 2D lattice mode vibrations and structural changes correlated with the so called “2D to 3D transition”. - Highlights: • A 2D to 3D transition has been detected for polymeric carbon nitride. • THz-TDS allowed us to discover and detect the 2D to 3D transition of polymeric carbon nitride. • We propose a structure for polymeric carbon nitride confirming it with THz-TDS.

  1. Negative differential resistance in an (8, 0) carbon/boron nitride nanotube heterojunction*

    Institute of Scientific and Technical Information of China (English)

    Song Jiuxu; Yang Yintang; Liu Hongxia; Guo Lixin

    2011-01-01

    Using the method combined non-equilibrium Green's function with density functional theory, the electronic transport properties of an (8, 0) carbon/boron nitride nanotube heterojunction coupled to Au electrodes were investigated. In the current voltage characteristic of the heterojunction, negative differential resistance was found under positive and negative bias, which is the variation of the localization for corresponding molecular orbital caused by the applied bias voltage These results are meaningful to modeling and simulating on related electronic devices.

  2. Immobilizing photogenerated electrons from graphitic carbon nitride for an improved visible-light photocatalytic activity

    OpenAIRE

    Han Sun; Yue Cao; Leiyu Feng; Yinguang Chen

    2016-01-01

    Reducing the recombination probability of photogenerated electrons and holes is pivotal in enhancing the photocatalytic ability of graphitic carbon nitride (g-C3N4). Speeding the departure of photogenerated electrons is the most commonly used method of achieving this. To the best of our knowledge, there is no report on suppressing the recombination of photogenerated electron–hole pairs by immobilizing the electrons with ester functional groups. Here, for the first time the mesoporous g-C3N4 (...

  3. Facile synthesis of phosphorus doped graphitic carbon nitride polymers with enhanced visible-light photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ligang [Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, Xiufang; Guan, Jing; Jiang, Yijun; Hou, Tonggang [Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China); Mu, Xindong, E-mail: muxd@qibebt.ac.cn [Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101 (China)

    2013-09-01

    Graphical abstract: - Highlights: • P-doped g-C{sub 3}N{sub 4} has been prepared by a one-pot green synthetic approach. • The incorporation of P resulted in favorable textural and electronic properties. • Doping with P enhanced the visible-light photocatalytic activity of g-C{sub 3}N{sub 4}. • A postannealing treatment further enhanced the activity of P-doped g-C{sub 3}N{sub 4}. • Photogenerated holes were the main species responsible for the activity. - Abstract: Phosphorus-doped carbon nitride materials were prepared by a one-pot green synthetic approach using dicyandiamide monomer and a phosphorus containing ionic liquid as precursors. The as-prepared materials were subjected to several characterizations and investigated as metal-free photocatalysts for the degradation of organic pollutants (dyes like Rhodamine B, Methyl orange) in aqueous solution under visible light. Results revealed that phosphorus-doped carbon nitride have a higher photocatalytic activity for decomposing Rhodamine B and Methyl orange in aqueous solution than undoped g-C{sub 3}N{sub 4}, which was attributed to the favorable textural, optical and electronic properties caused by doping with phosphorus heteroatoms into carbon nitride host. A facile postannealing treatment further improved the activity of the photocatalytic system, due to the higher surface area and smaller structural size in the postcalcined catalysts. The phosphorus-doped carbon nitride showed high visible-light photocatalytic activity, making them promising materials for a wide range of potential applications in photochemistry.

  4. The Effects of Radial Compression on Thermal Conductivity of Carbon and Boron Nitride Nanotubes

    OpenAIRE

    Haijun Shen

    2012-01-01

    By using molecular dynamics method, thermal conductivity of (10, 10) carbon and boron nitride (BN) nanotubes under radial compression was investigated, and the - (thermal conductivity versus temperature) curves of the two nanotubes were obtained. It is found that with the increase of temperature the thermal conductivity of two nanotubes decreases; the nanotubes, under both the local compression and whole compression, have lower thermal conductivity, and the larger the compressive deformat...

  5. Cu and Boron Doped Carbon Nitride for Highly Selective Oxidation of Toluene to Benzaldehyde.

    Science.gov (United States)

    Han, Hongling; Ding, Guodong; Wu, Tianbin; Yang, Dexin; Jiang, Tao; Han, Buxing

    2015-07-13

    A novel Cu and boron doped graphitic carbon nitride catalyst (Cu-CNB) was synthesized using cheap precursors and systematically characterized. The selective oxidation of toluene proceeded very smoothly over the catalyst at 70 °C using tert-butyl hydroperoxide (TBHP) as the oxidant to exclusively afford benzaldehyde. The catalyst can be used for at least five cycles without decrease in activity and selectivity.

  6. Cobalt-doped graphitic carbon nitride photocatalysts with high activity for hydrogen evolution

    Science.gov (United States)

    Chen, Pei-Wen; Li, Kui; Yu, Yu-Xiang; Zhang, Wei-De

    2017-01-01

    Cobalt-doped graphitic carbon nitride (Cosbnd CN) was synthesized by one-step thermal polycondensation using cobalt phthalocyanine (CoPc) and melamine as precursors. The π-π interaction between melamine and CoPc promotes cobalt doping into the framework of g-C3N4. The prepared samples were carefully characterized and the results demonstrated that Co-doped graphitic carbon nitride inhibited the crystal growth of graphitic carbon nitride (CN), leading to larger specific surface area (33.1 m2 g-1) and abundant Co-Nx active sites, narrower band gap energy and more efficient separation of photogenerated electrons and holes. 0.46% Cosbnd CN exhibited higher hydrogen evolution rate (28.0 μmol h-1) under visible light irradiation, which is about 3.0 times of that over the pure CN and about 2.2 times of that over cobalt-doped CN using CoCl2 • 6H2O as a cobalt source. This study provides a valuable strategy to modify CN with enhanced photocatalytic performance.

  7. Charge Modulation in Graphitic Carbon Nitride as a Switchable Approach to High-Capacity Hydrogen Storage.

    Science.gov (United States)

    Tan, Xin; Kou, Liangzhi; Tahini, Hassan A; Smith, Sean C

    2015-11-01

    Electrical charging of graphitic carbon nitride nanosheets (g-C4 N3 and g-C3 N4 ) is proposed as a strategy for high-capacity and electrocatalytically switchable hydrogen storage. Using first-principle calculations, we found that the adsorption energy of H2 molecules on graphitic carbon nitride nanosheets is dramatically enhanced by injecting extra electrons into the adsorbent. At full hydrogen coverage, the negatively charged graphitic carbon nitride achieves storage capacities up to 6-7 wt %. In contrast to other hydrogen storage approaches, the storage/release occurs spontaneously once extra electrons are introduced or removed, and these processes can be simply controlled by switching on/off the charging voltage. Therefore, this approach promises both facile reversibility and tunable kinetics without the need of specific catalysts. Importantly, g-C4 N3 has good electrical conductivity and high electron mobility, which can be a very good candidate for electron injection/release. These predictions may prove to be instrumental in searching for a new class of high-capacity hydrogen storage materials.

  8. The Combination of Direct and Confined Laser Ablation Mechanisms for the Selective Structuring of Thin Silicon Nitride Layers

    Science.gov (United States)

    Rapp, Stephan; Heinrich, Gerrit; Domke, Matthias; Huber, Heinz P.

    In the production process of microelectronic devices and high efficiency solar cells, local openings in thin dielectric layers are required. Instead of photolithographic, laser based processing enables to open these dielectric layers locally in a low-cost mass production step. In this work, thin silicon nitride layers deposited on planar silicon wafers are processed by single infrared Gaussian shaped 660 fs laser pulses. The transparent silicon nitride layer, becoming absorptive at fluences higher than 0.3 J/cm2, is selectively removed by confined ablation at fluences below that value. At pulse peak fluences exceeding 1.0 J/cm2 a "SiNx island"is created by direct ablation in the spot center. In this article, theselective SiNx ablation by a combination of confined and direct laser ablation at the medium pulse peak fluence of 0.5 J/cm2 is investigated. To clarify the influence of the nonlinear absorption in the pulse center, the ablation behavior is investigated by time- and space-resolved pump-probe microscopy experiments. The results showphase changes in the silicon and in the silicon nitride in the first picoseconds after excitation, the ablation onset at around 10 ps and the subsequent mechanical materialmotion after a few nanoseconds. The actual silicon nitride layer removal starts after around 10 ns, whereas confined ablation processes are the driving mechanisms even in the nonlinearly absorbing spot center. A comparison of the energetic ablation efficiency of the SiNx layer system to further dielectric thin films shows no detrimental influence of the nonlinear absorbance.

  9. Study of the structure and electrical properties of the copper nitride thin films deposited by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gallardo-Vega, C. [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (CICESE), Km. 107 Carretera Tijuana-Ensenada, A. Postal 2732, 22860, Ensenada B.C. (Mexico)]. E-mail: gallardo@ccmc.unam.mx; Cruz, W. de la [Centro de Ciencias de la Materia Condensada, UNAM, Km. 107 Carretera Tijuana-Ensenada, A. Postal 2681, 22860, Ensenada B.C. (Mexico)

    2006-09-15

    Copper nitride thin films were prepared on glass and silicon substrates by ablating a copper target at different pressure of nitrogen. The films were characterized in situ by X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and ex situ by X-ray diffraction (XRD). The nitrogen content in the samples, x = [N]/[Cu], changed between 0 and 0.33 for a corresponding variation in nitrogen pressure of 9 x 10{sup -2} to 1.3 x 10{sup -1} Torr. Using this methodology, it is possible to achieve sub-, over- and stoichiometric films by controlling the nitrogen pressure. The XPS results show that is possible to obtain copper nitride with x = 0.33 (Cu{sub 3}N) and x = 0.25 (Cu{sub 4}N) when the nitrogen pressure is 1.3 x 10{sup -1} and 5 x 10{sup -2} Torr, respectively. The lattice constants obtained from XRD results for copper nitride with x = 0.25 is of 3.850 A and with x = 0.33 have values between 3.810 and 3.830 A. The electrical properties of the films were studied as a function of the lattice constant. These results show that the electrical resistivity increases when the lattice parameter is decreasing. The electrical resistivity of copper nitride with x = 0.25 was smaller than samples with x = 0.33.

  10. Low Temperature Reactive Sputtering of Thin Aluminum Nitride Films on Metallic Nanocomposites.

    Science.gov (United States)

    Ramadan, Khaled Sayed Elbadawi; Evoy, Stephane

    2015-01-01

    Piezoelectric aluminum nitride thin films were deposited on aluminum-molybdenum (AlMo) metallic nanocomposites using reactive DC sputtering at room temperature. The effect of sputtering parameters on film properties was assessed. A comparative study between AlN grown on AlMo and pure aluminum showed an equivalent (002) crystallographic texture. The piezoelectric coefficients were measured to be 0.5±0.1 C m(-2) and 0.9±0.1 C m(-2), for AlN deposited on Al/0.32Mo and pure Al, respectively. Films grown onto Al/0.32Mo however featured improved surface roughness. Roughness values were measured to be 1.3nm and 5.4 nm for AlN films grown on AlMo and on Al, respectively. In turn, the dielectric constant was measured to be 8.9±0.7 for AlN deposited on Al/0.32Mo seed layer, and 8.7±0.7 for AlN deposited on aluminum; thus, equivalent within experimental error. Compatibility of this room temperature process with the lift-off patterning of the deposited AlN is also reported.

  11. Photochemical functionalization of gallium nitride thin films with molecular and biomolecular layers.

    Science.gov (United States)

    Kim, Heesuk; Colavita, Paula E; Metz, Kevin M; Nichols, Beth M; Sun, Bin; Uhlrich, John; Wang, Xiaoyu; Kuech, Thomas F; Hamers, Robert J

    2006-09-12

    We demonstrate that photochemical functionalization can be used to functionalize and photopattern the surface of gallium nitride crystalline thin films with well-defined molecular and biomolecular layers. GaN(0001) surfaces exposed to a hydrogen plasma will react with organic molecules bearing an alkene (C=C) group when illuminated with 254 nm light. Using a bifunctional molecule with an alkene group at one end and a protected amine group at the other, this process can be used to link the alkene group to the surface, leaving the protected amine exposed. Using a simple contact mask, we demonstrate the ability to directly pattern the spatial distribution of these protected amine groups on the surface with a lateral resolution of <12 mum. After deprotection of the amines, single-stranded DNA oligonucleotides were linked to the surface using a bifunctional cross-linker. Measurements using fluorescently labeled complementary and noncomplementary sequences show that the DNA-modified GaN surfaces exhibit excellent selectivity, while repeated cycles of hybridization and denaturation in urea show good stability. These results demonstrate that photochemical functionalization can be used as an attractive starting point for interfacing molecular and biomolecular systems with GaN and other compound semiconductors.

  12. The impact of substrate properties and thermal annealing on tantalum nitride thin films

    Science.gov (United States)

    Grosser, M.; Münch, M.; Seidel, H.; Bienert, C.; Roosen, A.; Schmid, U.

    2012-01-01

    In this study film properties of sputter-deposited tantalum nitride (TaNx) thin layers are investigated focusing on the impact of substrate properties, varying nitrogen content for film synthetization as well as post-deposition annealings in the temperature range up to 500 °C. For comparison, these investigations are done on low temperature co-fired ceramics and on silicon based substrates whereas the latter approach ensures defined and well-known surface properties. Furthermore, results on the phase evolution with high temperature annealings are presented showing a transformation of Ta4N to Ta2N in the temperature range between 350 °C and 500 °C. With increasing nitrogen content (i.e. nitrogen flow during film deposition) in the TaNx layers the topography shows first an increase in surface roughness, next a range where a smoothing of the surface characteristics is observed, and finally buckling and the existence of grain agglomerates. All these analyses are further evaluated with electrical measurements on the film resistivity and on the oxidation behaviour to gain deeper insight into material parameters relevant for micromachined devices which are operated under harsh environmental conditions.

  13. The impact of substrate properties and thermal annealing on tantalum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Grosser, M., E-mail: michaela_grosser@yahoo.de [Chair of Micromechanics, Microfluidics/Microactuators, Saarland University, 66123 Saarbruecken (Germany); Muench, M.; Seidel, H. [Chair of Micromechanics, Microfluidics/Microactuators, Saarland University, 66123 Saarbruecken (Germany); Bienert, C.; Roosen, A. [Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 5, D-91058 Erlangen (Germany); Schmid, U. [Department for Microsystems Technology, Institute of Sensor and Actuator Systems, Vienna University of Technology, Floragasse 7, 1040 Vienna (Austria)

    2012-01-15

    In this study film properties of sputter-deposited tantalum nitride (TaN{sub x}) thin layers are investigated focusing on the impact of substrate properties, varying nitrogen content for film synthetization as well as post-deposition annealings in the temperature range up to 500 Degree-Sign C. For comparison, these investigations are done on low temperature co-fired ceramics and on silicon based substrates whereas the latter approach ensures defined and well-known surface properties. Furthermore, results on the phase evolution with high temperature annealings are presented showing a transformation of Ta{sub 4}N to Ta{sub 2}N in the temperature range between 350 Degree-Sign C and 500 Degree-Sign C. With increasing nitrogen content (i.e. nitrogen flow during film deposition) in the TaN{sub x} layers the topography shows first an increase in surface roughness, next a range where a smoothing of the surface characteristics is observed, and finally buckling and the existence of grain agglomerates. All these analyses are further evaluated with electrical measurements on the film resistivity and on the oxidation behaviour to gain deeper insight into material parameters relevant for micromachined devices which are operated under harsh environmental conditions.

  14. Superconducting energy scales and anomalous dissipative conductivity in thin films of molybdenum nitride

    Science.gov (United States)

    Simmendinger, Julian; Pracht, Uwe S.; Daschke, Lena; Proslier, Thomas; Klug, Jeffrey A.; Dressel, Martin; Scheffler, Marc

    2016-08-01

    We report investigations of molybdenum nitride (MoN) thin films with different thickness and disorder and with superconducting transition temperature 9.89 K ≥Tc≥2.78 K . Using terahertz frequency-domain spectroscopy we explore the normal and superconducting charge carrier dynamics for frequencies covering the range from 3 to 38 cm-1 (0.1 to 1.1 THz). The superconducting energy scales, i.e., the critical temperature Tc, the pairing energy Δ , and the superfluid stiffness J , and the superfluid density ns can be well described within the Bardeen-Cooper-Schrieffer theory for conventional superconductors. At the same time, we find an anomalously large dissipative conductivity, which cannot be explained by thermally excited quasiparticles, but rather by a temperature-dependent normal-conducting fraction, persisting deep into the superconducting state. Our results on this disordered system constrain the regime, where discernible effects stemming from the disorder-induced superconductor-insulator transition possibly become relevant, to MoN films with a transition temperature lower than at least 2.78 K.

  15. Low-temperature silicon nitride for thin-film electronics on polyimide foil substrates

    Science.gov (United States)

    Gleskova, H.; Wagner, S.; Gašparík, V.; Kováč, P.

    2001-05-01

    We optimized silicon nitride (SiN x) layers, deposited by 13.56 MHz plasma enhanced chemical vapor deposition (PECVD) at 150°C, to provide a high quality gate dielectric layer for the amorphous silicon thin film technology on polyimide foils. The layers were deposited from mixtures of silane, ammonia, and hydrogen. We varied the H 2 flow rate from 55 to 220 sccm and the rf power from 5 to 50 W, while the pressure was kept at 500 mTorr and the ratio of ammonia to silane flow at 10:1. The best film was obtained from the gas composition of SiH 4:NH 3:H 2=1:10:44 and the rf power of ˜20 W. This film grows at the rate of 1.5 Å/s, has a refractive index n=1.80, a dielectric constant ɛ=7.46, a dielectric breakdown field >3.4 MV/cm, a Si/N ratio of ˜0.67, and a hydrogen content of ˜2×10 22 cm -3, and etches in 10:1 buffered HF at a rate of 61 Å/s.

  16. In situ infrared spectroscopic study of cubic boron nitride thin film delamination

    Institute of Scientific and Technical Information of China (English)

    Yang Hang-Sheng; Zhang Jian-Ying; Nie An-Min; Zhang Xiao-Bin

    2008-01-01

    This paper investigates the procedure of cubic boron nitride(cBN)thin film delamination by Fourier-transform infrared(IR)spectroscopy.It finds that the apparent IR absorption peak area near 1380 cm-1 and 1073 cm-1 attributed to the B-N stretching vibration of sp2-bonded BN and the transverse optical phonon of cBN,respectively,increased up to 195% and 175% of the original peak area after film delamination induced compressive stress relaxation.The increase of IR absorption of sp2-bonded BN is found to be non-linear and hysteretic to film delamination,which suggests that the relaxation of the turbostratic BN(tBN)layer from the compressed condition is also hysteretic to film delamination.Moreover,cross-sectional transmission electron microscopic observations revealed that cBN film delamination is possible from near the aBN(amorphons BN)/tBN interface at least for films prepared by plasma-enhanced chemical vapour deposition.

  17. Deposition and characterization of amorphous aluminum nitride thin films for a gate insulator

    Energy Technology Data Exchange (ETDEWEB)

    Oikawa, H.; Akiyama, R. [Institute of Materials Science, University of Tsukuba,1-1-1 Tennoudai, Tsukuba, 305-8573 (Japan); Tsukuba Nano-Tech Human Resource Development Program, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8571 (Japan); Kanazawa, K. [Institute of Materials Science, University of Tsukuba,1-1-1 Tennoudai, Tsukuba, 305-8573 (Japan); Kuroda, S., E-mail: kuroda@ims.tsukuba.ac.jp [Institute of Materials Science, University of Tsukuba,1-1-1 Tennoudai, Tsukuba, 305-8573 (Japan); Tsukuba Nano-Tech Human Resource Development Program, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8571 (Japan); Harayama, I. [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8573 (Japan); Tsukuba Nano-Tech Human Resource Development Program, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8571 (Japan); Nagashima, K. [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8573 (Japan); Sekiba, D. [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8573 (Japan); Tandem Accelerator Complex, Research Facility Center for Science and Technology, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8577 (Japan); Ashizawa, Y.; Tsukamoto, A.; Nakagawa, K. [College of Science and Technology, Nihon University, 7-24-1 Narashinodai, Funabashi, 274-8501 (Japan); Ota, N. [Tsukuba Nano-Tech Human Resource Development Program, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, 305-8571 (Japan)

    2015-01-01

    Thin films of aluminum nitride (AlN) fabricated by reactive deposition were characterized in order to examine the electrical insulation properties suitable for a gate insulator. For a series of AlN films deposited with a variation of the amount of Al flux at a fixed N flux, compositional and chemical analyses were performed using X-ray photoelectron spectroscopy (XPS) and elastic recoil detection analysis (ERDA). Combined with the result of current-voltage (I-V) measurement, it is found that the insulation properties are correlated with the compositional ratio between Al and N estimated by the ERDA measurement; a good electrical insulation with a minimal leak current of the order of 10{sup -9} A/cm{sup 2} at a high electric field 1 MV/cm is achieved in the film of nearly stoichiometric compositional ratio of Al/N, in which the dominance of the Al-N bonding state is confirmed in the XPS measurement. On the other hand, the incorporation of oxygen, probably caused by the surface oxidization due to the exposure to the air, has little effect on the electrical properties. - Highlights: • AlN thin films deposited by reactive deposition were characterized for gate insulator. • A good electrical insulation was achieved at nearly stoichiometric composition. • The effects of oxygen incorporation and Al-N bonding state were also investigated. • A minimum leak current density as low as 10{sup -9}A/cm{sup 2} at 1MV/cm was achieved.

  18. Poly-crystalline thin-film by aluminum induced crystallization on aluminum nitride substrate

    Science.gov (United States)

    Bhopal, Muhammad Fahad; Lee, Doo Won; Lee, Soo Hong

    2016-09-01

    Thin-film polycrystalline silicon ( pc-Si) on foreign (non-silicon) substrates has been researched by various research groups for the production of photovoltaic cells. High quality pc-Si deposition on foreign substrates with superior optical properties is considered to be the main hurdle in cell fabrication. Metal induced crystallization (MIC) is one of the renowned techniques used to produce this quality of material. In the current study, an aluminum induced crystallization (AIC) method was adopted to produce pc-Si thin-film on aluminum nitride (AlN) substrate by a seed layer approach. Aluminum and a-Si layer were deposited using an e-beam evaporator. Various annealing conditions were used in order to investigate the AIC grown pc-Si seed layers for process optimization. The effect of thermal annealing on grain size, defects preferentially crystallographic orientation of the grains were analyzed. Surface morphology was studied using an optical microscope. Poly-silicon film with a crystallinity fraction between 95-100% and an FWHM between 5-6 cm-1 is achievable at low temperatures and for short time intervals. A grain size of about 10 micron can be obtained at a low deposition rate on an AIN substrate. Similarly, Focused ion beam (FIB) also showed that at 425 °C sample B and at 400 °C sample A were fully crystallized. The crystalline quality of pc-Si was evaluated using μ-Raman spectroscopy as a function of annealed conditions and Grazing incidence X-ray diffraction (GIXRD) was used to determine the phase direction of the pc-Si layer. The current study implicates that a poly-silicon layer with good crystallographic orientation and crystallinity fraction is achievable on AIN substrate at low temperatures and short time frames.

  19. Deposition of magnesium nitride thin films on stainless steel-304 substrates by using a plasma focus device

    Science.gov (United States)

    Ramezani, Amir Hoshang; Habibi, Maryam; Ghoranneviss, Mahmood

    2014-08-01

    In this research, for the first time, we synthesize magnesium nitride thin films on 304-type stainless steel substrates using a Mather-type (2 kJ) plasma focus (PF) device. The films of magnesium nitride are coated with different number of focus shots (like 15, 25 and 35) at a distance of 8 cm from the anode tip and at 0° angular position with respect to the anode axis. For investigation of the structural properties and surface morphology of magnesium nitride films, we utilized the X-ray diffractometer (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis, respectively. Also, the elemental composition is characterized by energy-dispersive X-ray (EDX) analysis. Furthermore, Vicker's microhardness is used to study the mechanical properties of the deposited films. The results show that the degree of crystallinity of deposited thin films (from XRD), the average size of particles and surface roughness (from AFM), crystalline growth of structures (from SEM) and the hardness values of the films depend on the number of focus shots. The EDX analysis demonstrates the existence of the elemental composition of magnesium in the deposited samples.

  20. Nanostructures based in boro nitride thin films deposited by PLD onto Si/Si{sub 3}N{sub 4}/DLC substrate

    Energy Technology Data Exchange (ETDEWEB)

    Roman, W S; Riascos, H [Grupo Plasma, Laser y Aplicaciones, Universidad Tecnologica de Pereira (Colombia); Caicedo, J C [Grupo de PelIculas Delgadas, Universidad del Valle, Cali (Colombia); Ospina, R [Laboratorio de Plasma, Universidad Nacional de Colombia, sede Manizales (Colombia); Tirado-MejIa, L, E-mail: hriascos@utp.edu.c [Laboratorio de Optoelectronica, Universidad del Quindio (Colombia)

    2009-05-01

    Diamond-like carbon and boron nitride were deposited like nanostructered bilayer on Si/Si{sub 3}N{sub 4} substrate, both with (100) crystallographic orientation, these films were deposited through pulsed laser technique (Nd: YAG: 8 Jcm{sup -2}, 9ns). Graphite (99.99%) and boron nitride (99.99%) targets used to growth the films in argon atmosphere. The thicknesses of bilayer were determined with a perfilometer, active vibration modes were analyzed using infrared spectroscopy (FTIR), finding bands associated around 1400 cm{sup -1} for B - N bonding and bands around 1700 cm{sup -1} associated with C=C stretching vibrations of non-conjugated alkenes and azometinic groups, respectively. The crystallites of thin films were analyzed using X-ray diffraction (XRD) and determinated the h-BN (0002), alpha-Si{sub 3}N{sub 4} (101) phases. The aim of this study is to relate the dependence on physical and chemical characteristics of the system Si/Si{sub 3}N{sub 4}/DLC/BN with gas pressure adjusted at the 1.33, 2.67 and 5.33 Pa values.

  1. Galvanic corrosion of structural non-stoichiometric silicon nitride thin films and its implications on reliability of microelectromechanical devices

    Energy Technology Data Exchange (ETDEWEB)

    Broas, M., E-mail: mikael.broas@aalto.fi; Mattila, T. T.; Paulasto-Kröckel, M. [Department of Electrical Engineering and Automation, Aalto University, Espoo, P.O. Box 13500, FIN-00076 Aalto (Finland); Liu, X.; Ge, Y. [Department of Materials Science and Engineering, Aalto University, Espoo, P.O. Box 16200, FIN-00076 Aalto (Finland)

    2015-06-28

    This paper describes a reliability assessment and failure analysis of a poly-Si/non-stoichiometric silicon nitride thin film composite structure. A set of poly-Si/SiN{sub x} thin film structures were exposed to a mixed flowing gas (MFG) environment, which simulates outdoor environments, for 90 days, and an elevated temperature and humidity (85 °C/95% R.H.) test for 140 days. The mechanical integrity of the thin films was observed to degrade during exposure to the chemically reactive atmospheres. The degree of degradation was analyzed with nanoindentation tests. Statistical analysis of the forces required to initiate a fracture in the thin films indicated degradation due to the exposure to the MFG environment in the SiN{sub x} part of the films. Scanning electron microscopy revealed a porous-like reaction layer on top of SiN{sub x}. The morphology of the reaction layer resembled that of galvanically corroded poly-Si. Transmission electron microscopy further clarified the microstructure of the reaction layer which had a complex multi-phase structure extending to depths of ∼100 nm. Furthermore, the layer was oxidized two times deeper in a 90 days MFG-tested sample compared to an untested reference. The formation of the layer is proposed to be caused by galvanic corrosion of elemental silicon in non-stoichiometric silicon nitride during hydrofluoric acid etching. The degradation is proposed to be due uncontrolled oxidation of the films during the stress tests.

  2. Oxygen Reduction Electrocatalysts Based on Coupled Iron Nitride Nanoparticles with Nitrogen-Doped Carbon

    Directory of Open Access Journals (Sweden)

    Min Jung Park

    2016-06-01

    Full Text Available Aimed at developing a highly active and stable non-precious metal electrocatalyst for oxygen reduction reaction (ORR, a novel FexNy/NC nanocomposite—that is composed of highly dispersed iron nitride nanoparticles supported on nitrogen-doped carbon (NC—was prepared by pyrolyzing carbon black with an iron-containing precursor in an NH3 atmosphere. The influence of the various synthetic parameters such as the Fe precursor, Fe content, pyrolysis temperature and pyrolysis time on ORR performance of the prepared iron nitride nanoparticles was investigated. The formed phases were determined by experimental and simulated X-ray diffraction (XRD of numerous iron nitride species. We found that Fe3N phase creates superactive non-metallic catalytic sites for ORR that are more active than those of the constituents. The optimized Fe3N/NC nanocomposite exhibited excellent ORR activity and a direct four-electron pathway in alkaline solution. Furthermore, the hybrid material showed outstanding catalytic durability in alkaline electrolyte, even after 4,000 potential cycles.

  3. Effective Route to Graphitic carbon Nitride from Ball-Milled Amorphous carbon in NH3 Atmosphere Under Annealing

    Institute of Scientific and Technical Information of China (English)

    费振义; 刘玉先

    2003-01-01

    Graphitic carbon nitride (g-C3N4) powders were successfully synthesized from ball-milled amorphous carbon under NHs atmosphere at high temperature, for the first time to the best of our knowledge. The combined characteristic data obtained by x-ray diffraction, high-resolution transmission-electron microscopy, electron energy loss spectroscopy, Raman spectroscopy, energy dispersive spectroscopic analysis, and Fourier transformation infrared spectroscopy provide substantial evidence for the graphite-like sp2-bonded structure with C3N4 stoichiometry.

  4. Effect of applied dc bias voltage on composition, chemical bonding and mechanical properties of carbon nitride films prepared by PECVD

    Institute of Scientific and Technical Information of China (English)

    LI Hong-xuan; XU Tao; HAO Jun-ying; CHEN Jian-min; ZHOU Hui-di; XUE Qun-ji; LIU Hui-wen

    2004-01-01

    Carbon nitride films were deposited on Si (100) substrates using plasma-enhanced chemical vapor deposition (PECVD) technique from CH4 and N2 at different applied dc bias voltage. The microstructure, composition and chemical bonding of the resulting films were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The mechanical properties such as hardness and elastic modulus of the films were evaluated using nano-indentation. As the results, the Raman spectra, showing the G and D bands, indicate the amorphous structure of the films. XPS and FTIR measurements demonstrate the existence of various carbon-nitride bonds in the films and the hydrogenation of carbon nitride phase. The composition ratio of N to C, the nano-hardness and the elastic modulus of the carbon nitride films increase with increasing dc bias voltage and reach the maximums at a dc bias voltage of 300 V, then they decrease with further increase of the dc bias voltage. Moreover, the XRD analyses indicate that the carbon nitride film contains some polycrystalline C3N4 phase embedded in the amorphous matrix at optimized deposition condition of dc bias voltage of 300 V.

  5. Non-linear processes in thin titanium nitride transmission lines for parametric amplification

    Science.gov (United States)

    Vissers, Michael; Gao, Jiansong; Chaudhuri, Suptarshi; Bockstiegel, Clint; Sandberg, Martin; Pappas, David P.

    2013-03-01

    Nitride superconductors, such as titanium nitride and niobium titanium nitride, are a non-linear, low dissipation medium at microwave frequencies. The lossless nonlinearity may be probed and utilized. Important applications include generation of higher harmonics, e.g. 3f, and a microwave version of the optical paramagnetic amplifier, i.e. the degenerate-pump case of four-photon mixing (FPM). An amplifier based on these principles should allow for very wide bandwidth, low noise (quantum limited) and high dynamic range devices. These measurements are performed via a single layer, 3 meter long TiN spiral and measured at temperatures below 100 mK. Initial results of the design, fabrication, testing, and impedance optimization of a titanium nitride based parametric amplifier are presented.

  6. Optical properties of aluminum nitride thin films grown by direct-current magnetron sputtering close to epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, A. [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France); Soltani, A., E-mail: ali.soltani@iemn.univ-lille1.fr [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France); Abdallah, B. [Department of Materials Physics, Atomic Energy Commission of Syria, Damascus, P.O. Box 6091 (Syrian Arab Republic); Charrier, J. [Fonctions Optiques pour les Technologies de l' informatiON (FOTON), UMR CNRS 6082, 6, rue de Kerampont CS 80518, 22305 Lannion Cedex (France); Deresmes, D. [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France); Jouan, P.-Y.; Djouadi, M.A. [Institut des Matériaux Jean Rouxel – IMN, UMR CNRS 6502, 2, rue de la Houssinère BP 32229, 44322 Nantes (France); Dogheche, E.; De Jaeger, J.-C. [Institut d' Electronique de Microélectronique et de Nanotechnologie (IEMN), UMR CNRS 8520, PRES Lille, Université Nord de France, Avenue Poincaré, 59652 Villeneuve d' Ascq Cedex (France)

    2013-05-01

    Low-temperature Aluminum Nitride (AlN) thin films with a thickness of 3 μm were deposited by Direct-Current magnetron sputtering on sapphire substrate. They present optical properties similar to those of epitaxially grown films. Different characterization methods such as X-Ray Diffraction, Transmission Electron Microscopy and Atomic Force Microscopy were used to determine the structural properties of the films such as its roughness and crystallinity. Newton interferometer was used for stress measurement of the films. Non-destructive prism-coupling technique was used to determine refractive index and thickness homogeneity by a mapping on the whole sample area. Results show that AlN films grown on AlGaN layer have a high crystallinity close to epitaxial films, associated to a low intrinsic stress for low thickness. These results highlight that it is possible to grow thick sample with microstructure and optical properties close to epitaxy, even on a large surface. - Highlights: ► Aluminum Nitride sputtering technique with a low temperature growth process ► Epitaxial quality of two microns sputtered Aluminum Nitride film ► Optics as a non-destructive accurate tool for acoustic wave investigation.

  7. Yellow luminescence of gallium nitride generated by carbon defect complexes.

    Science.gov (United States)

    Demchenko, D O; Diallo, I C; Reshchikov, M A

    2013-02-22

    We demonstrate that yellow luminescence often observed in both carbon-doped and pristine GaN is the result of electronic transitions via the C(N)-O(N) complex. In contrast to common isolated defects, the C(N)-O(N) complex is energetically favorable, and its calculated optical properties, such as absorption and emission energies, a zero phonon line, and the thermodynamic transition level, all show excellent agreement with measured luminescence data. Thus, by combining hybrid density functional theory and experimental measurements, we propose a solution to a long-standing problem of the GaN yellow luminescence.

  8. Crystal structure of polymeric carbon nitride and the determination of its process-temperature-induced modifications

    Science.gov (United States)

    Tyborski, T.; Merschjann, C.; Orthmann, S.; Yang, F.; Lux-Steiner, M.-Ch; Schedel-Niedrig, Th

    2013-10-01

    Based on the arrangement of two-dimensional ‘melon’, we construct a unit cell for polymeric carbon nitride (PCN) synthesized via thermal polycondensation, whose theoretical diffraction powder pattern includes all major features measured in x-ray diffraction. With the help of this unit cell, we describe the process-temperature-induced crystallographic changes in PCN that occur within a temperature interval between 510 and 610 °C. We also discuss further potential modifications of the unit cell for PCN. It is found that both triazine- and heptazine-based g-C3N4 can only account for minor phases within the investigated synthesis products.

  9. Negative differential resistance in an (8, 0) carbon/boron nitride nanotube heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Song Jiuxu; Yang Yintang; Liu Hongxia [Key Laboratory of Ministry of Education for Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Guo Lixin, E-mail: songjiuxu@126.com [School of Science, Xidian University, Xi' an 710071 (China)

    2011-04-15

    Using the method combined non-equilibrium Green's function with density functional theory, the electronic transport properties of an (8, 0) carbon/boron nitride nanotube heterojunction coupled to Au electrodes were investigated. In the current voltage characteristic of the heterojunction, negative differential resistance was found under positive and negative bias, which is the variation of the localization for corresponding molecular orbital caused by the applied bias voltage. These results are meaningful to modeling and simulating on related electronic devices. (semiconductor physics)

  10. Nickel Decorated on Phosphorous-Doped Carbon Nitride as an Efficient Photocatalyst for Reduction of Nitrobenzenes

    Science.gov (United States)

    Kumar, Anurag; Kumar, Pawan; Joshi, Chetan; Manchanda, Manvi; Boukherroub, Rabah; Jain, Suman L.

    2016-01-01

    Nickel nanoparticle-decorated phosphorous-doped graphitic carbon nitride (Ni@g-PC3N4) was synthesized and used as an efficient photoactive catalyst for the reduction of various nitrobenzenes under visible light irradiation. Hydrazine monohydrate was used as the source of protons and electrons for the intended reaction. The developed photocatalyst was found to be highly active and afforded excellent product yields under mild experimental conditions. In addition, the photocatalyst could easily be recovered and reused for several runs without any detectable leaching during the reaction.

  11. Microwave-assisted polyol synthesis of carbon nitride dots from folic acid for cell imaging

    Directory of Open Access Journals (Sweden)

    Guan WW

    2014-10-01

    Full Text Available Weiwei Guan,1,* Wei Gu,2,* Ling Ye,2 Chenyang Guo,1 Su Su,1 Pinxiang Xu,1,3 Ming Xue1,3 1Department of Pharmacology, School of Basic Medical Sciences, Capital Medical University, Beijing, People’s Republic of China; 2Department of Chemical Biology, School of Chemical Biology and Pharmaceutical Sciences, Capital Medical University, Beijing, People’s Republic of China; 3Beijing Laboratory for Biomedical Detection Technology and Instrument, Beijing, People’s Republic of China *These authors contributed equally to this work Abstract: A green, one-step microwave-assisted polyol synthesis was employed to prepare blue luminescent carbon nitride dots (CNDs using folic acid molecules as both carbon and nitrogen sources. The as-prepared CNDs had an average size of around 4.51 nm and could be well dispersed in water. Under excitation at 360 nm, the CNDs exhibited a strong blue luminescence and the quantum yield was estimated to be 18.9%, which is greater than that of other reported CNDs. Moreover, the CNDs showed low cytotoxicity and could efficiently label C6 glioma cells, demonstrating their potential in cell imaging. Keywords: carbon nitride dots (CNDs, folic acid, photoluminescence, cell imaging

  12. Effects of strain on carbon donors and acceptors in hexagonal boron nitride monolayers

    Science.gov (United States)

    Fujimoto, Yoshitaka; Saito, Susumu

    2016-01-01

    We present first-principles density functional calculations that clarify the electronic properties of carbon defects in hexagonal boron nitride (h -BN) monolayers under biaxially applied strains. We find that strain can control the ionization energies of both donor and acceptor states. Furthermore, we also find that strain can lead to the dramatic change in conduction channel properties of donor states due to the interchange of the conduction-band-minimum state with the nearly-free-electron state. We also report the simulated scanning tunneling microscopy (STM) images of carbon defects in h -BN monolayers for experimental identification of those defects. We show that the STM images strongly reflect distinctive spatial distributions of local density of states around carbon defects depending on the substitution sites and thereby they could be identified by using STM experiments.

  13. Nanostructures of Indium Gallium Nitride Crystals Grown on Carbon Nanotubes.

    Science.gov (United States)

    Park, Ji-Yeon; Man Song, Keun; Min, Yo-Sep; Choi, Chel-Jong; Seok Kim, Yoon; Lee, Sung-Nam

    2015-11-16

    Nanostructure (NS) InGaN crystals were grown on carbon nanotubes (CNTs) using metalorganic chemical vapor deposition. The NS-InGaN crystals, grown on a ~5-μm-long CNT/Si template, were estimated to be ~100-270 nm in size. Transmission electron microscope examinations revealed that single-crystalline InGaN NSs were formed with different crystal facets. The observed green (~500 nm) cathodoluminescence (CL) emission was consistent with the surface image of the NS-InGaN crystallites, indicating excellent optical properties of the InGaN NSs on CNTs. Moreover, the CL spectrum of InGaN NSs showed a broad emission band from 490 to 600 nm. Based on these results, we believe that InGaN NSs grown on CNTs could aid in overcoming the green gap in LED technologies.

  14. Quality improvement of ZnO thin layers overgrown on Si(100 substrates at room temperature by nitridation pretreatment

    Directory of Open Access Journals (Sweden)

    Peng Wang

    2012-06-01

    Full Text Available To improve the quality of ZnO thin film overgrown on Si(100 substrate at RT (room temperature, the Si(100 surface was pretreated with different methods. The influence of interface on the overgrown ZnO layers was investigated by atomic force microscopy, photoluminescence and X-ray diffraction. We found that the nitridation pretreatment could significantly improve the quality of RT ZnO thin film through two-fold effects: one was to buffer the big lattice mismatch and ease the stress resulted from heterojunction growth; the other was to balance the interface charge, block the symmetric inheritance from the cubic Si (100 substrate and thus restrain the formation of zincblende phase.

  15. Scanning proximal microscopy study of the thin layers of silicon carbide-aluminum nitride solid solution manufactured by fast sublimation epitaxy

    Directory of Open Access Journals (Sweden)

    Tománek P.

    2013-05-01

    Full Text Available The objective of the study is a growth of SiC/(SiC1−x(AlNx structures by fast sublimation epitaxy of the polycrystalline source of (SiC1−x(AlNx and their characterisation by proximal scanning electron microscopy and atomic force microscopy. For that purpose optimal conditions of sublimation process have been defined. Manufactured structures could be used as substrates for wide-band-gap semiconductor devices on the basis of nitrides, including gallium nitride, aluminum nitride and their alloys, as well as for the production of transistors with high mobility of electrons and also for creation of blue and ultraviolet light emitters (light-emitted diodes and laser diodes. The result of analysis shows that increasing of the growth temperature up to 2300 K allows carry out sublimation epitaxy of thin layers of aluminum nitride and its solid solution.

  16. Dispersing molecular cobalt in graphitic carbon nitride frameworks for photocatalytic water oxidation.

    Science.gov (United States)

    Zhang, Guigang; Huang, Caijin; Wang, Xinchen

    2015-03-01

    The development of water oxidation catalysts (WOCs) to cooperate with light-energy transducers for solar energy conversion by water splitting and CO2 fixation is a demanding challenge. The key measure is to develop efficient and sustainable WOCs that can support a sustainable photocatalyst to reduce over-potentials and thus to enhance reaction rate of water oxidation reaction. Cobalt has been indentified as active component of WOCs for photo/electrochemical water oxidation, and its performance relies strongly on the contact and adhesion of the cobalt species with photoactive substrates. Here, cobalt is homogeneously engineered into the framework of pristine graphitic carbon nitride (g-C3 N4 ) via chemical interaction, establishing surface junctions on the polymeric photocatalyst for the water oxidation reaction. This modification promotes the surface kinetics of oxygen evolution reaction by the g-C3 N4 -based photocatalytic system made of inexpensive substances, and further optimizations in the optical and textural structure of Co-g-C3 N4 is envisaged by considering ample choice of modification schemes for carbon nitride materials.

  17. Graphitic carbon nitride/graphene oxide/reduced graphene oxide nanocomposites for photoluminescence and photocatalysis

    Science.gov (United States)

    Aleksandrzak, Malgorzata; Kukulka, Wojciech; Mijowska, Ewa

    2017-03-01

    The study presents a modification of graphitic carbon nitride (g-C3N4) with graphene oxide (GO) and reduced graphene oxide (rGO) and investigation of photoluminescent and photocatalytic properties. The influence of GO and rGO lateral sizes used for the modification was investigated. The nanomaterials were characterized with atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance UV-vis spectroscopy (DR-UV-vis) and photoluminescence spectroscopy (PL). PL revealed that pristine graphitic carbon nitride and its nanocomposites with GO and rGO emitted up-converted photoluminescence (UCPL) which could contribute to the improvement of photocatalytic activity of the materials. The photoactivity was evaluated in a process of phenol decomposition under visible light. A hybrid composed of rGO nanoparticles (rGONPs, 4-135 nm) exhibited the highest photoactivity compared to rGO with size of 150 nm-7.2 μm and graphene oxide with the corresponding sizes. The possible reason of the superior photocatalytic activity is the most enhanced UCPL of rGONPs, contributing to the emission of light with higher energy than the incident light, resulting in improved photogeneration of electron-hole pairs.

  18. Polymeric graphitic carbon nitride as a heterogeneous organocatalyst: from photochemistry to multipurpose catalysis to sustainable chemistry.

    Science.gov (United States)

    Wang, Yong; Wang, Xinchen; Antonietti, Markus

    2012-01-02

    Polymeric graphitic carbon nitride materials (for simplicity: g-C(3)N(4)) have attracted much attention in recent years because of their similarity to graphene. They are composed of C, N, and some minor H content only. In contrast to graphenes, g-C(3)N(4) is a medium-bandgap semiconductor and in that role an effective photocatalyst and chemical catalyst for a broad variety of reactions. In this Review, we describe the "polymer chemistry" of this structure, how band positions and bandgap can be varied by doping and copolymerization, and how the organic solid can be textured to make it an effective heterogenous catalyst. g-C(3)N(4) and its modifications have a high thermal and chemical stability and can catalyze a number of "dream reactions", such as photochemical splitting of water, mild and selective oxidation reactions, and--as a coactive catalytic support--superactive hydrogenation reactions. As carbon nitride is metal-free as such, it also tolerates functional groups and is therefore suited for multipurpose applications in biomass conversion and sustainable chemistry.

  19. Rational design of carbon nitride photocatalysts by identification of cyanamide defects as catalytically relevant sites

    Science.gov (United States)

    Lau, Vincent Wing-Hei; Moudrakovski, Igor; Botari, Tiago; Weinberger, Simon; Mesch, Maria B.; Duppel, Viola; Senker, Jürgen; Blum, Volker; Lotsch, Bettina V.

    2016-07-01

    The heptazine-based polymer melon (also known as graphitic carbon nitride, g-C3N4) is a promising photocatalyst for hydrogen evolution. Nonetheless, attempts to improve its inherently low activity are rarely based on rational approaches because of a lack of fundamental understanding of its mechanistic operation. Here we employ molecular heptazine-based model catalysts to identify the cyanamide moiety as a photocatalytically relevant `defect'. We exploit this knowledge for the rational design of a carbon nitride polymer populated with cyanamide groups, yielding a material with 12 and 16 times the hydrogen evolution rate and apparent quantum efficiency (400 nm), respectively, compared with the unmodified melon. Computational modelling and material characterization suggest that this moiety improves coordination (and, in turn, charge transfer kinetics) to the platinum co-catalyst and enhances the separation of the photogenerated charge carriers. The demonstrated knowledge transfer for rational catalyst design presented here provides the conceptual framework for engineering high-performance heptazine-based photocatalysts.

  20. Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation

    Science.gov (United States)

    Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

    2016-01-01

    Light isotopes separation, such as 3He/4He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as 3He/4He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high 3He/4He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application. PMID:26813491

  1. Mechanical and Structural Properties of Graphene-like Carbon Nitride Sheets

    CERN Document Server

    de Sousa, J M; Perim, E; Bizao, R A; Galvao, Douglas S

    2016-01-01

    Carbon nitride-based nanostructures have attracted special attention (from theory and experiments) due to their remarkable electromechanical properties. In this work we have investigated the mechanical properties of some graphene-like carbon nitride membranes through fully atomistic reactive molecular dynamics simulations. We have analyzed three different structures of these CN families, the so-called graphene-based g-CN, triazine-based g-C3N4 and heptazine-based g-C3N4. The stretching dynamics of these membranes was studied for deformations along their two main axes and at three different temperatures: 10K, 300K and 600K. We show that g-CN membranes have the lowest ultimate fracture strain value, followed by heptazine-based and triazine-based ones, respectively. This behavior can be explained in terms of their differences in terms of density values, topologies and types of chemical bonds. The dependency of the fracture patterns on the stretching directions is also discussed.

  2. Carbon nitride nanotubulite densely-packed and well-aligned tubular nanostructures

    Science.gov (United States)

    Suenaga, K.; Johansson, M. P.; Hellgren, N.; Broitman, E.; Wallenberg, L. R.; Colliex, C.; Sundgren, J.-E.; Hultman, L.

    1999-02-01

    Tubular carbon nitride (CN x, x=0.01-0.32) nanoparticles were successfully synthesized by d.c. magnetron sputtering. These tubes were grown in a highly packed form perpendicularly on a sodium chloride substrate. Their number density is estimated to be ˜1×10 4 per μm 2 and is constant over macroscopic regions. Sub-nanometer scale chemical mapping shows that the nitrogen to carbon atomic ratio is rather constant across these tubes. This successful synthesis of a nanotubulite - made of a rather compact aggregation of tubular nanoparticles - could facilitate experimental approaches to measure mechanical or electrical transport properties of such nanotubes and to open the way to variable nanotube applications.

  3. Electronic structures of an (8, 0) boron nitride/carbon nanotube heterojunction

    Energy Technology Data Exchange (ETDEWEB)

    Liu Hongxia; Zhang Heming; Song Jiuxu [Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Zhang Zhiyong, E-mail: liuhongxia_xidian@126.co [Information Science and Technology Institution, Northwest University, Xi' an 710069 (China)

    2010-01-15

    The electronic structure of the heterojunction is the foundation of the study on its working mechanism. Models of the heterojunctions formed by an (8, 0) boron nitride nanotube and an (8, 0) carbon nanotube with C-B or C-N interface have been established. The structures of the above heterojunctions were optimized with first-principle calculations based on density functional theory. The rearrangements of the heterojunctions concentrate mainly on their interfaces. The highest occupied molecular orbital and the lowest unoccupied molecular orbital of the heterojunctions distribute in the carbon nanotube section. As the band offsets of the above heterojunctions are achieved with the average bond energy method, the band structure is plotted. (semiconductor materials)

  4. Superior Current Carrying Capacity of Boron Nitride Encapsulated Carbon Nanotubes with Zero-Dimensional Contacts.

    Science.gov (United States)

    Huang, Jhao-Wun; Pan, Cheng; Tran, Son; Cheng, Bin; Watanabe, Kenji; Taniguchi, Takashi; Lau, Chun Ning; Bockrath, Marc

    2015-10-14

    We report fabrication and characterization of hexagonal boron nitride (hBN)-encapsulated carbon nanotube (CNT) field effect transistors, which are coupled to electrical leads via zero-dimensional contacts. Device quality is attested by the ohmic contacts and observation of Coulomb blockade with a single periodicity in small bandgap semiconducing nanotubes. Surprisingly, hBN-encapsulated CNT devices demonstrate significantly enhanced current carrying capacity; a single-walled CNT can sustain >180 μA current or, equivalently, a current density of ∼2 × 10(10) A/cm(2), which is a factor of 6-7 higher than devices supported on SiO2 substrates. Such dramatic enhancement of current carrying capacity arises from the high thermal conductivity of hBN and lower hBN-CNT interfacial thermal resistance and has implications for carbon electronic applications.

  5. Surface morphology stabilization by chemical sputtering in carbon nitride film growth

    Energy Technology Data Exchange (ETDEWEB)

    Buijnsters, J G [Institute for Molecules and Materials (IMM), Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen (Netherlands); Vazquez, L [Instituto de Ciencia de Materiales de Madrid (CSIC), C/Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)

    2008-01-07

    We have studied the influence of chemical sputtering effects on the morphology of carbon nitride films grown on silicon substrates by electron cyclotron resonance chemical vapour deposition. This study has been performed by comparing the evolution of their morphology with that of hydrogenated amorphous carbon films grown under similar conditions, where these effects are not present. When chemical sputtering effects operate we observe a film surface stabilization for length scales in the 60-750 nm range after a threshold roughness of about 3-4 nm has been developed. This stabilization is explained on the basis of the re-emission of nitrogen etching species, which is confirmed by growth experiments on microstructured substrates. (fast track communication)

  6. In Situ Mechanical Property Measurements of Amorphous Carbon-Boron Nitride Nanotube Nanostructures

    Science.gov (United States)

    Kim, Jae-Woo; Lin, Yi; Nunez, Jennifer Carpena; Siochi, Emilie J.; Wise, Kristopher E.; Connell, John W.; Smith, Michael W.

    2011-01-01

    To understand the mechanical properties of amorphous carbon (a-C)/boron nitride nanotube (BNNT) nanostructures, in situ mechanical tests are conducted inside a transmission electron microscope equipped with an integrated atomic force microscope system. The nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation. We demonstrate multiple in situ tensile, compressive, and lap shear tests with a-C/BNNT hybrid nanostructures. The tensile strength of the a-C/BNNT hybrid nanostructure is 5.29 GPa with about 90 vol% of a-C. The tensile strength and strain of the end-to-end joint structure with a-C welding is 0.8 GPa and 5.2% whereas the lap shear strength of the side-by-side joint structure with a-C is 0.25 GPa.

  7. Ultrafast deposition of silicon nitride and semiconductor silicon thin films by Hot Wire Chemical Vapor Deposition

    NARCIS (Netherlands)

    Schropp, R.E.I.; van der Werf, C.H.M.; Verlaan, V.; Rath, J.K.; Li, H. B. T.

    2009-01-01

    The technology of Hot Wire Chemical Vapor Deposition (HWCVD) or Catalytic Chemical Vapor Deposition (Cat-CVD) has made great progress during the last couple of years. This review discusses examples of significant progress. Specifically, silicon nitride deposition by HWCVD (HW-SiNx) is highlighted, a

  8. Group III-nitride thin films grown using MBE and bismuth

    Science.gov (United States)

    Kisielowski, Christian K.; Rubin, Michael

    2000-01-01

    The present invention comprises growing gallium nitride films in the presence of bismuth using MBE at temperatures of about 1000 K or less. The present invention further comprises the gallium nitride films fabricated using the inventive fabrication method. The inventive films may be doped with magnesium or other dopants. The gallium nitride films were grown on sapphire substrates using a hollow anode Constricted Glow Discharge nitrogen plasma source. When bismuth was used as a surfactant, two-dimensional gallium nitride crystal sizes ranging between 10 .mu.m and 20 .mu.m were observed. This is 20 to 40 times larger than crystal sizes observed when GaN films were grown under similar circumstances but without bismuth. It is thought that the observed increase in crystal size is due bismuth inducing an increased surface diffusion coefficient for gallium. The calculated value of 4.7.times.10.sup.-7 cm.sup.2 /sec. reveals a virtual substrate temperature of 1258 K which is 260 degrees higher than the actual one.

  9. Effect of contact metals on the piezoelectric properties of aluminum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Harman, J.P.; Kabulski, A. (West Virginia U., Morgantown, WV); Pagan, V.R. (West Virginia U., Morgantown, WV); Famouri, K. (West Virginia U., Morgantown, WV); Kasarla, K.R.; Rodak, L.E. (West Virginia U., Morgantown, WV); Hensel, J.P.; Korakakis, D.

    2008-07-01

    The converse piezoelectric response of aluminum nitride evaluated using standard metal insulator semiconductor structures has been found to exhibit a linear dependence on the work function of the metal used as the top electrode. The apparent d33 of the 150–1100 nm films also depends on the dc bias applied to the samples.

  10. Effect of contact metals on the piezoelectric properties of aluminum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Harman, J.; Kabulski, A.; Pagán, V. R.; Famouri, P.; Kasarla, K. R.; Rodak, L. E.; Peter Hensel, J.; Korakakis, D.

    2008-01-01

    The converse piezoelectric response of aluminum nitride evaluated using standard metal insulator semiconductor structures has been found to exhibit a linear dependence on the work function of the metal used as the top electrode. The apparent d33 of the 150–1100 nm films also depends on the dc bias applied to the samples.

  11. Electron beam generation and structure of defects in carbon and boron nitride nano-tubes

    Energy Technology Data Exchange (ETDEWEB)

    Zobelli, A

    2007-10-15

    The nature and role of defects is of primary importance to understand the physical properties of C and BN (boron nitride) single walled nano-tubes (SWNTs). Transmission electron microscopy (TEM) is a well known powerful tool to study the structure of defects in materials. However, in the case of SWNTs, the electron irradiation of the TEM may knock out atoms. This effect may alter the native structure of the tube, and has also been proposed as a potential tool for nano-engineering of nano-tubular structures. Here we develop a theoretical description of the irradiation mechanism. First, the anisotropy of the emission energy threshold is obtained via density functional based calculations. Then, we numerically derive the total Mott cross section for different emission sites of carbon and boron nitride nano-tubes with different chiralities. Using a dedicated STEM (Scanning Transmission Electron Microscope) microscope with experimental conditions optimised on the basis of derived cross-sections, we are able to control the generation of defects in nano-tubular systems. Either point or line defects can be obtained with a spatial resolution of a few nanometers. The structure, energetics and electronics of point and line defects in BN systems have been investigated. Stability of mono- and di- vacancy defects in hexagonal boron nitride layers is investigated, and their activation energies and reaction paths for diffusion have been derived using the nudged elastic band method (NEB) combined with density functional based techniques. We demonstrate that the appearance of extended linear defects under electron irradiation is more favorable than a random distribution of point defects and this is due to the existence of preferential sites for atom emission in the presence of pre-existing defects, rather than thermal vacancy nucleation and migration. (author)

  12. Graphitic carbon nitride (g-C3N4) coated titanium oxide nanotube arrays with enhanced photo-electrochemical performance.

    Science.gov (United States)

    Sun, Mingxuan; Fang, Yalin; Kong, Yuanyuan; Sun, Shanfu; Yu, Zhishui; Umar, Ahmad

    2016-08-09

    Herein, we report the successful formation of graphitic carbon nitride coated titanium oxide nanotube array thin films (g-C3N4/TiO2) via the facile thermal treatment of anodized Ti sheets over melamine. The proportion of C3N4 and TiO2 in the composite can be adjusted by changing the initial addition mass of melamine. The as-prepared samples are characterized by several techniques in order to understand the morphological, structural, compositional and optical properties. UV-vis absorption studies exhibit a remarkable red shift for the g-C3N4/TiO2 thin films as compared to the pristine TiO2 nanotubes. Importantly, the prepared composites exhibit an enhanced photocurrent and photo-potential under both UV-vis and visible light irradiation. Moreover, the observed maximum photo-conversion efficiency of the prepared composites is 1.59 times higher than that of the pristine TiO2 nanotubes. The optical and electrochemical impedance spectra analysis reveals that the better photo-electrochemical performance of the g-C3N4/TiO2 nanotubes is mainly due to the wider light absorption and reduced impedance compared to the bare TiO2 nanotube electrode. The presented work demonstrates a facile and simple method to fabricate g-C3N4/TiO2 nanotubes and clearly revealed that the introduction of g-C3N4 is a new and innovative approach to improve the photocurrent and photo-potential efficiencies of TiO2.

  13. Oxygen- and Lithium-Doped Hybrid Boron-Nitride/Carbon Networks for Hydrogen Storage.

    Science.gov (United States)

    Shayeganfar, Farzaneh; Shahsavari, Rouzbeh

    2016-12-20

    Hydrogen storage capacities have been studied on newly designed three-dimensional pillared boron nitride (PBN) and pillared graphene boron nitride (PGBN). We propose these novel materials based on the covalent connection of BNNTs and graphene sheets, which enhance the surface and free volume for storage within the nanomaterial and increase the gravimetric and volumetric hydrogen uptake capacities. Density functional theory and molecular dynamics simulations show that these lithium- and oxygen-doped pillared structures have improved gravimetric and volumetric hydrogen capacities at room temperature, with values on the order of 9.1-11.6 wt % and 40-60 g/L. Our findings demonstrate that the gravimetric uptake of oxygen- and lithium-doped PBN and PGBN has significantly enhanced the hydrogen sorption and desorption. Calculations for O-doped PGBN yield gravimetric hydrogen uptake capacities greater than 11.6 wt % at room temperature. This increased value is attributed to the pillared morphology, which improves the mechanical properties and increases porosity, as well as the high binding energy between oxygen and GBN. Our results suggest that hybrid carbon/BNNT nanostructures are an excellent candidate for hydrogen storage, owing to the combination of the electron mobility of graphene and the polarized nature of BN at heterojunctions, which enhances the uptake capacity, providing ample opportunities to further tune this hybrid material for efficient hydrogen storage.

  14. Encapsulation of cisplatin as an anti-cancer drug into boron-nitride and carbon nanotubes: Molecular simulation and free energy calculation

    Energy Technology Data Exchange (ETDEWEB)

    Roosta, Sara [Molecular Simulation Research Laboratory, Department of Chemistry, Iran University of Science & Technology, Tehran (Iran, Islamic Republic of); Hashemianzadeh, Seyed Majid, E-mail: hashemianzadeh@iust.ac.ir [Molecular Simulation Research Laboratory, Department of Chemistry, Iran University of Science & Technology, Tehran (Iran, Islamic Republic of); Ketabi, Sepideh, E-mail: sepidehketabi@yahoo.com [Department of Chemistry, East Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2016-10-01

    Encapsulation of cisplatin anticancer drug into the single walled (10, 0) carbon nanotube and (10, 0) boron-nitride nanotube was investigated by quantum mechanical calculations and Monte Carlo Simulation in aqueous solution. Solvation free energies and complexation free energies of the cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube complexes was determined as well as radial distribution functions of entitled compounds. Solvation free energies of cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube were − 4.128 kcal mol{sup −1} and − 2457.124 kcal mol{sup −1} respectively. The results showed that cisplatin@ boron-nitride nanotube was more soluble species in water. In addition electrostatic contribution of the interaction of boron- nitride nanotube complex and solvent was − 281.937 kcal mol{sup −1} which really more than Van der Waals and so the electrostatic interactions play a distinctive role in the solvation free energies of boron- nitride nanotube compounds. On the other hand electrostatic part of the interaction of carbon nanotube complex and solvent were almost the same as Van der Waals contribution. Complexation free energies were also computed to study the stability of related structures and the free energies were negative (− 374.082 and − 245.766 kcal mol{sup −1}) which confirmed encapsulation of drug into abovementioned nanotubes. However, boron-nitride nanotubes were more appropriate for encapsulation due to their larger solubility in aqueous solution. - Highlights: • Solubility of cisplatin@ boron-nitride nanotube is larger than cisplatin@ carbon nanotube. • Boron- nitride nanotube complexes have larger electrostatic contribution in solvation free energy. • Complexation free energies confirm encapsulation of drug into the nanotubes in aqueous solution. • Boron- nitride nanotubes are appropriate drug delivery systems compared with carbon nanotubes.

  15. Production of Metal-Free Composites Composed of Graphite Oxide and Oxidized Carbon Nitride Nanodots and Their Enhanced Photocatalytic Performances.

    Science.gov (United States)

    Kim, Seung Yeon; Oh, Junghoon; Park, Sunghee; Shim, Yeonjun; Park, Sungjin

    2016-04-01

    A novel metal-free composite (GN) composed of two types of carbon-based nanomaterials, graphite oxide (GO) and 2D oxidized carbon nitride (OCN) nanodots was produced. Chemical and morphological characterizations reveal that GN contains a main component of GO with well-dispersed 2D OCN nanodots. GN shows enhanced photocatalytic performance for degrading an organic pollutant, Rhodamine B, under visible light.

  16. Methods of forming boron nitride

    Science.gov (United States)

    Trowbridge, Tammy L; Wertsching, Alan K; Pinhero, Patrick J; Crandall, David L

    2015-03-03

    A method of forming a boron nitride. The method comprises contacting a metal article with a monomeric boron-nitrogen compound and converting the monomeric boron-nitrogen compound to a boron nitride. The boron nitride is formed on the same or a different metal article. The monomeric boron-nitrogen compound is borazine, cycloborazane, trimethylcycloborazane, polyborazylene, B-vinylborazine, poly(B-vinylborazine), or combinations thereof. The monomeric boron-nitrogen compound is polymerized to form the boron nitride by exposure to a temperature greater than approximately 100.degree. C. The boron nitride is amorphous boron nitride, hexagonal boron nitride, rhombohedral boron nitride, turbostratic boron nitride, wurzite boron nitride, combinations thereof, or boron nitride and carbon. A method of conditioning a ballistic weapon and a metal article coated with the monomeric boron-nitrogen compound are also disclosed.

  17. Marine corrosion protective coatings of hexagonal boron nitride thin films on stainless steel.

    Science.gov (United States)

    Husain, Esam; Narayanan, Tharangattu N; Taha-Tijerina, Jose Jaime; Vinod, Soumya; Vajtai, Robert; Ajayan, Pulickel M

    2013-05-22

    Recently, two-dimensional, layered materials such as graphene and hexagonal boron nitride (h-BN) have been identified as interesting materials for a range of applications. Here, we demonstrate the corrosion prevention applications of h-BN in marine coatings. The performance of h-BN/polymer hybrid coatings, applied on stainless steel, were evaluated using electrochemical techniques in simulated seawater media [marine media]. h-BN/polymer coating shows an efficient corrosion protection with a low corrosion current density of 5.14 × 10(-8) A/cm(2) and corrosion rate of 1.19 × 10(-3) mm/year and it is attributed to the hydrofobic, inert and dielectric nature of boron nitride. The results indicated that the stainless steel with coatings exhibited improved corrosion resistance. Electrochemical impedance spectroscopy and potentiodynamic analysis were used to propose a mechanism for the increased corrosion resistance of h-BN coatings.

  18. Magnetostrictive iron gallium thin films grown onto antiferromagnetic manganese nitride: Structure and magnetism

    Science.gov (United States)

    Mandru, Andrada-Oana; Corbett, Joseph P.; Richard, Andrea L.; Gallagher, James; Meng, Keng-Yuan; Ingram, David C.; Yang, Fengyuan; Smith, Arthur R.

    2016-10-01

    We report structural and magnetic properties of magnetostrictive Fe100 -xGax (x ≈ 15) alloys when deposited onto antiferromagnetic manganese nitride and non-magnetic magnesium oxide substrates. From X-ray diffraction measurements, we find that the FeGa films are single crystalline. Scanning tunneling microscopy imaging reveals that the surface morphologies are dictated by the growth temperature, composition, and substrate. The magnetic properties can be tailored by the substrate, as found by magnetic force microscopy imaging and vibrating sample magnetometry measurements. In addition to pronounced tetragonal deformations, depositing FeGa onto manganese nitride leads to the formation of stripe-like magnetic domain patterns and to the appearance of perpendicular magnetic anisotropy.

  19. Crystallographic investigation of aluminium nitride thin films on stainless steel foil for highly efficient piezoelectric vibration energy harvesters

    Science.gov (United States)

    Moriwaki, N.; Minh, L. V.; Ohigashi, R.; Shimada, O.; Kitayoshi, H.; Kuwano, H.

    2016-11-01

    This study reports piezoelectric properties and crystallographic microstructures of aluminium nitride (AlN, wurtzite structure) thin films on 50 μm thick stainless steel foil. The transverse piezoelectric coefficient d31f and e31f of 10 pm thick AlN films were estimated as -1.42 ± 0.08 μm/V and -0.48 ± 0.03 C/m2 from a tip displacement of the piezoelectric cantilevers. Dielectric constant s33 was measured as 10.5 ± 1.0. An electron beam diffraction pattern by a high-resolution transmission electron microscope and x-ray diffraction pattern showed that abundance ratio of the orientation such as , and of AlN crystal on stainless steel foils increased with increasing thickness.

  20. Influence of laser pulse frequency on the microstructure of aluminum nitride thin films synthesized by pulsed laser deposition

    Science.gov (United States)

    Antonova, K.; Duta, L.; Szekeres, A.; Stan, G. E.; Mihailescu, I. N.; Anastasescu, M.; Stroescu, H.; Gartner, M.

    2017-02-01

    Aluminum Nitride (AlN) thin films were synthesized on Si (100) wafers at 450 °C by pulsed laser deposition. A polycrystalline AlN target was multipulsed irradiated in a nitrogen ambient, at different laser pulse repetition rate. Grazing Incidence X-Ray Diffraction and Atomic Force Microscopy analyses evidenced nanocrystallites with a hexagonal lattice in the amorphous AlN matrix. The thickness and optical constants of the layers were determined by infrared spectroscopic ellipsometry. The optical properties were studied by Fourier Transform Infrared reflectance spectroscopy in polarised oblique incidence radiation. Berreman effect was observed around the longitudinal phonon modes of the crystalline AlN component. Angular dependence of the A1LO mode frequency was analysed and connected to the orientation of the particles' optical axis to the substrate surface normal. The role of the laser pulse frequency on the layers' properties is discussed on this basis.

  1. Ion-induced stress relaxation during the growth of cubic boron nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Abendroth, B.E.

    2004-08-01

    in this thesis the deposition of cubic boron nitride films by magnetron sputtering is described. The deposition process is analyzed by Langmuir-probe measurement and energy resolved mass spectroscopy. the films are studied by stress measurement, spectroscopic ellipsometry, infrared spectroscopy, elastic recoil detection analysis, Rutherford backscattering spectroscopy, X-ray absorption near edge spectroscopy, X-ray diffraction, and transmission electron microscopy. Discussed are the stress relaxation and the microstructure and bonding characteristics together with the effects of ion bombardement. (HSI)

  2. Carbon nitride supported copper nanoparticles: light-induced electronic effect of the support for triazole synthesis

    Science.gov (United States)

    Nandi, Debkumar; Taher, Abu; Ul Islam, Rafique; Siwal, Samarjeet; Choudhary, Meenakshi; Mallick, Kaushik

    2016-11-01

    The composite framework of graphitic carbon nitride (gCN) supported copper nanoparticle can act as a high-performance photoreactor for the synthesis of 1,2,3-triazole derivatives under light irradiation in the absence of alkaline condition. The photoactivity of gCN originates from an electron transition from the valence band to the conduction band, in the presence of photon energy, and the hot electron acts as a scavenger of the terminal proton of the alkyne molecule to facilitate the formation of copper acetanilide complex. In this study, we have performed the experiment under a different photonic environment, including dark condition, and in the presence and absence of base. A comparative study was also executed using Cu-TiO2 system, as a reference material, in the support of our proposed mechanism. The recycling performance and the photocorrosion effect of the catalyst have also been reported in this study.

  3. CMOS Humidity Sensor System Using Carbon Nitride Film as Sensing Materials

    Directory of Open Access Journals (Sweden)

    Shaestagir Chowdhury

    2008-04-01

    Full Text Available An integrated humidity sensor system with nano-structured carbon nitride film as humidity sensing material is fabricated by a 0.8 μm analog mixed CMOS process. The integrated sensor system consists of differential humidity sensitive field effect transistors (HUSFET, temperature sensor, and operational amplifier. The process contains two poly, two metal and twin well technology. To form CNx film on Si3N4/Si substrate, plasma etching is performed to the gate area as well as trenches. CNx film is deposited by reactive RF magnetron sputtering method and patterned by the lift-off technique. The drain current is proportional to the dielectric constant, and the sensitivity is 2.8 ㎂/%RH.

  4. Interacting Carbon Nitride and Titanium Carbide Nanosheets for High-Performance Oxygen Evolution.

    Science.gov (United States)

    Ma, Tian Yi; Cao, Jian Liang; Jaroniec, Mietek; Qiao, Shi Zhang

    2016-01-18

    Free-standing flexible films, constructed from two-dimensional graphitic carbon nitride and titanium carbide (with MXene phase) nanosheets, display outstanding activity and stability in catalyzing the oxygen-evolution reaction in alkaline aqueous system, which originates from the Ti-N(x) motifs acting as electroactive sites, and the hierarchically porous structure with highly hydrophilic surface. With this excellent electrocatalytic ability, comparable to that of the state-of-the-art precious-/transition-metal catalysts and superior to that of most free-standing films reported to date, they are directly used as efficient cathodes in rechargeable zinc-air batteries. Our findings reveal that the rational interaction between different two-dimensional materials can remarkably promote the oxygen electrochemistry, thus boosting the entire clean energy system.

  5. Influence of oxygen impurity on electronic properties of carbon and boron nitride nanotubes: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ram Sevak, E-mail: singh915@gmail.com [Department of Physics, National Institute of TechnologyKurukshetra 136119 (Haryana) (India)

    2015-11-15

    Influence of oxygen impurity on electronic properties of carbon and boron nitride nanotubes (CNTs and BNNTs) is systematically studied using first principle calculations based on density functional theory. Energy band structures and density of states of optimized zigzag (5, 0), armchair (3, 3), and chiral (4, 2) structures of CNT and BNNT are calculated. Oxygen doping in zigzag CNT exhibits a reduction in metallicity with opening of band gap in near-infrared region while metallicity is enhanced in armchair and chiral CNTs. Unlike oxygen-doped CNTs, energy bands are drastically modulated in oxygen-doped zigzag and armchair BNNTs, showing the nanotubes to have metallic behaviour. Furthermore, oxygen impurity in chiral BNNT induces narrowing of band gap, indicating a gradual modification of electronic band structure. This study underscores the understanding of different electronic properties induced in CNTs and BNNTs under oxygen doping, and has potential in fabrication of various nanoelectronic devices.

  6. Influence of oxygen impurity on electronic properties of carbon and boron nitride nanotubes: A comparative study

    Directory of Open Access Journals (Sweden)

    Ram Sevak Singh

    2015-11-01

    Full Text Available Influence of oxygen impurity on electronic properties of carbon and boron nitride nanotubes (CNTs and BNNTs is systematically studied using first principle calculations based on density functional theory. Energy band structures and density of states of optimized zigzag (5, 0, armchair (3, 3, and chiral (4, 2 structures of CNT and BNNT are calculated. Oxygen doping in zigzag CNT exhibits a reduction in metallicity with opening of band gap in near-infrared region while metallicity is enhanced in armchair and chiral CNTs. Unlike oxygen-doped CNTs, energy bands are drastically modulated in oxygen-doped zigzag and armchair BNNTs, showing the nanotubes to have metallic behaviour. Furthermore, oxygen impurity in chiral BNNT induces narrowing of band gap, indicating a gradual modification of electronic band structure. This study underscores the understanding of different electronic properties induced in CNTs and BNNTs under oxygen doping, and has potential in fabrication of various nanoelectronic devices.

  7. Harvesting solar light with crystalline carbon nitrides for efficient photocatalytic hydrogen evolution

    KAUST Repository

    Bhunia, Manas Kumar

    2014-08-14

    Described herein is the photocatalytic hydrogen evolution using crystalline carbon nitrides (CNs) obtained by supramolecular aggregation followed by ionic melt polycondensation (IMP) using melamine and 2,4,6-triaminopyrimidine as a dopant. The solid state NMR spectrum of 15N-enriched CN confirms the triazine as a building unit. Controlling the amount and arrangements of dopants in the CN structure can dramatically enhance the photocatalytic performance for H2 evolution. The polytriazine imide (PTI) exhibits the apparent quantum efficiency (AQE) of 15% at 400 nm. This method successfully enables a substantial amount of visible light to be harvested for H2 evolution, and provides a promising route for the rational design of a variety of highly active crystalline CN photocatalysts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Metal-free hybrids of graphitic carbon nitride and nanodiamonds for photoelectrochemical and photocatalytic applications.

    Science.gov (United States)

    Zhou, Li; Zhang, Huayang; Guo, Xiaochen; Sun, Hongqi; Liu, Shaomin; Tade, Moses O; Wang, Shaobin

    2017-05-01

    Graphitic carbon nitride (g-C3N4) has been considered as a metal-free, cost-effective, eco-friendly and efficient catalyst for various photoelectrochemical applications. However, compared to conventional metal-based photocatalysts, its photocatalytic activity is still low because of the low mobility of carriers restricted by the polymer nature. Herein, a series of hybrids of g-C3N4 (GCN) and nanodiamonds (NDs) were synthesized using a solvothermal method. The photoelectrochemical performance and photocatalytic efficiency of the GCN/NDs were investigated by means of the generation of photocurrent and photodegradation of methylene blue (MB) solutions under UV-visible light irradiations. In this study, the sample of GCN/ND-33% derived from 0.1g GCN and 0.05g NDs displayed the highest photocatalytic activity and the strongest photocurrent density. The mechanism of enhanced photoelectrochemical and photocatalytic performances was also discussed.

  9. Nickel Oxide and Nickel Co-doped Graphitic Carbon Nitride Nanocomposites and its Octylphenol Sensing Application

    KAUST Repository

    Gong, Wanyun

    2015-11-16

    Nickel oxide and nickel co-doped graphitic carbon nitride (NiO-Ni-GCN) nanocomposites were successfully prepared by thermal treatment of melamine and NiCl2 6H2O. NiO-Ni-GCN nanocomposites showed superior electrochemical catalytic activity for the oxidation of octylphenol to pure GCN. A detection method of octylphenol in environmental water samples was developed based at NiO-Ni-GCN nanocomposites modified electrode under infrared light irradiation. Differential pulse voltammetry was used as the analytic technique of octylphenol, exhibiting stable and specific concentration-dependent oxidation signal in the presence of octylphenol in the range of 10nM to 1μM and 1μM to 50μM, with a detection limit of 3.3nM (3S/N). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Boron Nitride Coated Carbon Nanotube Arrays with Enhanced Compressive Mechanical Property

    Science.gov (United States)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Tan, Dunlin; Zhang, Bowei; Tok, Alfred Iing Yoong; Teo, Edwin Hang Tong

    Vertically aligned carbon nanotube (CNT) array is one of the most promising energy dissipating materials due to its excellent temperature invariant mechanical property. However, the CNT arrays with desirable recoverability after compression is still a challenge. Here, we report on the mechanical enhancement of the CNT arrays reinforced by coating with boron nitride (BN) layers. These BN coated CNT (BN/CNT) arrays exhibit excellent compressive strength and recoverability as compared to those of the as-prepared CNT arrays which totally collapsed after compression. In addition, the BN coating also provides better resistance to oxidation due to its intrinsic thermal stability. This work presented here opens a new pathway towards tuning mechanical behavior of any arbitrary CNT arrays for promising potential such as damper, vibration isolator and shock absorber applications.

  11. Vibrational Spectroscopy of Chemical Species in Silicon and Silicon-Rich Nitride Thin Films

    Directory of Open Access Journals (Sweden)

    Kirill O. Bugaev

    2012-01-01

    Full Text Available Vibrational properties of hydrogenated silicon-rich nitride (SiN:H of various stoichiometry (0.6≤≤1.3 and hydrogenated amorphous silicon (a-Si:H films were studied using Raman spectroscopy and Fourier transform infrared spectroscopy. Furnace annealing during 5 hours in Ar ambient at 1130∘C and pulse laser annealing were applied to modify the structure of films. Surprisingly, after annealing with such high-thermal budget, according to the FTIR data, the nearly stoichiometric silicon nitride film contains hydrogen in the form of Si–H bonds. From analysis of the FTIR data of the Si–N bond vibrations, one can conclude that silicon nitride is partly crystallized. According to the Raman data a-Si:H films with hydrogen concentration 15% and lower contain mainly Si–H chemical species, and films with hydrogen concentration 30–35% contain mainly Si–H2 chemical species. Nanosecond pulse laser treatments lead to crystallization of the films and its dehydrogenization.

  12. Facile fabrication of ordered mesoporous graphitic carbon nitride for RhB photocatalytic degradation

    Science.gov (United States)

    Luo, Lei; Zhang, Anfeng; Janik, Michael J.; Li, Keyan; Song, Chunshan; Guo, Xinwen

    2017-02-01

    Ordered mesoporous graphitic carbon nitrides were prepared by directly condensing the uniform mixtures of melamine and KIT-6. After removal of the KIT-6 sacrificial template, the carbon nitrides were characterized with TEM, N2 physical adsorption, XRD, FT-IR, XPS, UV-vis and PL spectrometries, and tested for their RhB photocatalytic degradation activity. Together, these characterizations confirmed the as-prepared tunable mesoporous materials with enhanced charge separation efficiency and superior photocatalytic performance. Compared with a conventional bulk g-C3N4, ordered mesoporous g-C3N4 exhibits a larger specific surface area of 279.3 m2/g and a pore size distribution about 4.0 nm and 13.0 nm. Meanwhile, the reduced bandgap energy of 2.77 eV and lower photogenerated electron-hole pair recombination frequency were evidenced by UV-Vis and PL spectra. The RhB photocatalytic degradation activity maximizes with a mass ratio of KIT-6/melamine of 80% (KCN80), and the kinetic constant reaches 0.0760 min-1 which is 16 times higher than that of the bulk sample. Reusability of KCN80 was demonstrated by a lack of evident deactivation after three consecutive reaction periods. The direct condensation of the KIT-6 and melamine mixture does not require pre-casting of the precursor into the pore system of the templates. Owing to its high product yield, improved SBET, reduced bandgap energy and limited charge recombination, the facile-prepared ordered mesoporous g-C3N4 is a practical candidate for further modification.

  13. Pulsed laser deposition of carbon nanotube and polystyrene-carbon nanotube composite thin films

    Science.gov (United States)

    Stramel, A. A.; Gupta, M. C.; Lee, H. R.; Yu, J.; Edwards, W. C.

    2010-12-01

    In this work, we report on the fabrication of carbon nanotube thin films via pulsed laser deposition using a pulsed, diode pumped, Tm:Ho:LuLF laser with 2 μm wavelength. The thin films were deposited on silicon substrates using pure carbon nanotube targets and polystyrene-carbon nanotube composite targets. Raman spectra, scanning electron micrographs, and transmission electron micrographs show that carbon nanotubes are present in the deposited thin films, and that the pulsed laser deposition process causes minimal degradation to the quality of the nanotubes when using pure carbon nanotube targets.

  14. Stepwise Synthesis of Mesoporous Carbon Nitride Functionalized by Melamine Based Dendrimer Amines for Adsorption of CO2 and CH4

    Directory of Open Access Journals (Sweden)

    Mansoor Anbia

    2016-12-01

    Full Text Available In this study, a novel solid dendrimer amine (hyperbranched polymers was prepared using mesoporous carbon nitride functionalized by melamine based dendrimer amines. This adsorbent was denoted MDA-MCN-1. The process was stepwise synthesis and hard-templating method using mesoporous silica SBA-15 as a template. Cyanuric chloride and N,N-diisopropylethylamine (DIPEA, Merck were used for functionalization of the MCN-1. Fourier transform infrared spectroscopy (FT-IR, Nitrogen adsorption-desorption analysis, Small Angle X-ray Scattering (SAXS, X-ray diffraction (XRD and thermogravimetric analysis (TGA were used for characterization of the adsorbent. This material was used for carbon dioxide gas (CO2 and methane gas (CH4 adsorption at high pressure (up to 20 bar and room temperature. The volumetric method was used for the tests of the gas adsorption. The CO2 adsorption capacity of modified mesoporous carbon nitrides was about 4 mmol CO2 per g adsorbent. The methane adsorption capacity of this material was less than that CO2. Modified Mesoporous Carbon Nitride adsorbed about 3.52 mmol CH4 /g adsorbent. The increment of melamine based dendrimer generation on mesoporous surface increased adsorption capacity of both carbon dioxide and methane gases. According to the results obtained, the solid dendrimer amines, (MDA-MCN-1, performs excellently for CO2 and CH4 capture from flow gases and CO2 and CH4 storage.

  15. First-principles studies of the vibrational properties of amorphous carbon nitrides

    Institute of Scientific and Technical Information of China (English)

    Niu Li; Wang Xuan-Zhang; Zhu Jia-Qi; Gao Wei

    2013-01-01

    Raman spectra of amorphous carbon nitride films (a-C:N) resemble those of typical amorphous carbon (a-C),and no specific features in the spectra are shown due to N doping.The present work provides a correlation between the microstructure and vibrational properties of a-C:N films from first principles.The six periodic model structures of 64 atoms with various mass densities and nitrogen contents are generated by the liquid-quench method using Car-Parinello molecular dynamics.By using Raman coupling tensors calculated with the finite electric field method,Raman spectra are obtained.The calculated results show that the vibrations of C=N could directly contribute to the Raman spectrum.The similarity of the Raman line shapes of N-doped and N-free amorphous carbons is due to the overlapping of C=N and C=C vibration bands.In addition,the origin of characteristic Raman peaks is also given.

  16. Magnetic properties of gadolinium and carbon co-doped gallium nitride

    Science.gov (United States)

    Syed Kaleemullah, N.; Ramsubramanian, S.; Mohankumar, R.; Munawar Basha, S.; Rajagopalan, M.; Kumar, J.

    2017-01-01

    Investigations have been carried out to study the ferromagnetic properties of Gadolinium (Gd) Carbon (C) co-doped wurtzite Gallium Nitride (GaN) using full-potential linear augmented plane wave (FP-LAPW) method within the density functional theory. The system shows half-metallic nature when single Gd is substituted in Ga36N36 supercell. The presence of carbon in GaN supercell is found to generate weak magnetic moment (Ms) in the neighbouring atoms. When Carbon is codoped in the Gd-GaN, it increased the total magnetic moment of the system (Mtot). The cause of ferromagnetism in the Gd and C co-doped GaN has been explained by Zener's p-d exchange mechanism. The role of defects in the magnetic property of this system is also investigated. The results indicate the gallium vacancy influences the magnetic moment of the Gd and C codoped GaN more than the nitrogen vacancy. The presence of holes is effective than electrons in achieving the ferromagnetism in the considered system.

  17. Preparation and characterization of boron nitride coatings on carbon fibers from borazine by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Li Junsheng, E-mail: charlesljs@163.com [State Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, Changsha, 410073 (China); Zhang Changrui; Li Bin [State Key Laboratory of Advanced Ceramic Fibers and Composites, College of Aerospace and Materials Engineering, National University of Defense Technology, Changsha, 410073 (China)

    2011-06-15

    Boron nitride (BN) coatings were deposited on carbon fibers by chemical vapor deposition (CVD) using borazine as single source precursor. The deposited coatings were characterized by scanning electron microscopy (SEM), Auger electron spectroscopy (AES), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The effect of temperatures on growth kinetics, morphology, composition and structure of the coatings was investigated. In the low temperature range of 900 deg. C-1000 deg. C, the growth rate increased with increasing temperature complying with Arrhenius law, and an apparent active energy of 72 kJ/mol was calculated. The coating surface was smooth and compact, and the coatings uniformly deposited on individual fibers of carbon fiber bundles. The growth was controlled by surface reaction. At 1000 deg. C, the deposition rate reached a maximum (2.5 {mu}m/h). At the same time, the limiting step of the growth translated to be mass-transportation. Above 1100 deg. C, the growth rate decreased drastically due to the occurrence of gas-phase nucleation. Moreover, the coating surface became loose and rough. Composition and structure examinations revealed that stoichiometric BN coatings with turbostratic structure were obtained below 1000 deg. C, while hexagonal BN coatings were deposited above 1100 deg. C. A penetration of carbon element from the fibers to the coatings was observed.

  18. Angular magnetoresistance in semiconducting undoped amorphous carbon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sagar, Rizwan Ur Rehman; Saleemi, Awais Siddique; Zhang, Xiaozhong, E-mail: xzzhang@tsinghua.edu.cn [Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, People' s Republic of China and Beijing National Center for Electron Microscopy, Beijing 100084 (China)

    2015-05-07

    Thin films of undoped amorphous carbon thin film were fabricated by using Chemical Vapor Deposition and their structure was investigated by using High Resolution Transmission Electron Microscopy and Raman Spectroscopy. Angular magnetoresistance (MR) has been observed for the first time in these undoped amorphous carbon thin films in temperature range of 2 ∼ 40 K. The maximum magnitude of angular MR was in the range of 9.5% ∼ 1.5% in 2 ∼ 40 K. The origin of this angular MR was also discussed.

  19. Thin Coatings of Polymeric Carbon and Carbon Nanotubes for Corrosion Protection

    Science.gov (United States)

    2009-02-01

    Carbon Nanotube Functionalization /Doping Polyvinylpyrrolidone (PVP) A) p-Doping C) Polymer Wrapping Model B) n-Doping Polyethyleneimine ( PEI ) SWCNT Paint...fluorine-containing) groups functions as the barrier layer Multilayer Smart Carbon Nanotube Coating Insoluble polymer layer top coating -PMMA Substrate...Thin Coatings of Polymeric Carbon and Carbon Nanotubes for Corrosion Protection Zafar Iqbal Department of Chemistry and Environmental Science New

  20. Encapsulation of cisplatin as an anti-cancer drug into boron-nitride and carbon nanotubes: Molecular simulation and free energy calculation.

    Science.gov (United States)

    Roosta, Sara; Hashemianzadeh, Seyed Majid; Ketabi, Sepideh

    2016-10-01

    Encapsulation of cisplatin anticancer drug into the single walled (10, 0) carbon nanotube and (10, 0) boron-nitride nanotube was investigated by quantum mechanical calculations and Monte Carlo Simulation in aqueous solution. Solvation free energies and complexation free energies of the cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube complexes was determined as well as radial distribution functions of entitled compounds. Solvation free energies of cisplatin@ carbon nanotube and cisplatin@ boron-nitride nanotube were -4.128kcalmol(-1) and -2457.124kcalmol(-1) respectively. The results showed that cisplatin@ boron-nitride nanotube was more soluble species in water. In addition electrostatic contribution of the interaction of boron- nitride nanotube complex and solvent was -281.937kcalmol(-1) which really more than Van der Waals and so the electrostatic interactions play a distinctive role in the solvation free energies of boron- nitride nanotube compounds. On the other hand electrostatic part of the interaction of carbon nanotube complex and solvent were almost the same as Van der Waals contribution. Complexation free energies were also computed to study the stability of related structures and the free energies were negative (-374.082 and -245.766kcalmol(-1)) which confirmed encapsulation of drug into abovementioned nanotubes. However, boron-nitride nanotubes were more appropriate for encapsulation due to their larger solubility in aqueous solution.

  1. CARBON NITRIDE FILMS PREPARED AT DIFFERENT N2/Ar RATIOS BY CLOSED FIELD UNBALANCED REACTIVE MAGNETRON SPUTTERING

    Institute of Scientific and Technical Information of China (English)

    A. Vyas; K.Y. Li; Z.F. Zhou; Y.G. Shen

    2005-01-01

    Carbon nitride (CNx) thin films have been deposited onto Si(100) (for structural and mechanical analyses) and M42 high-speed-steel (for tribological measurements) substrates at room temperature by closed-field unbalanced magnetron sputtering. The mechanical and tribological properties of these films were highly dependent on the N/C concentration ratio that was adjusted by the F(N2)/F(Ar) flow-rate ratio at fixed substrate biasing of -60V during deposition. The films were characterized by employing scanning electron microscopy (SEM), atomic force microscopy(AFM), nano-indentation measurements, X-ray photoelectron spectroscopy (XPS), Raman scattering and Fourier transform infrared (FTIR) spectroscopy, pin-on-disc tribometer, scratch tester, and Rockwell-C tester. The results showed that the N content in the films increased with the N2 pressure. However, the maximum N/C ratio obtained was 0.25. The nanohardness was measured to be in the range of 11.7-20.8GPa depending on the N/C ratios. The XPS N 1s spectra showed the existence of both N-C sp2 and N-C sp3 bonds in films. Raman and FTIR spectra exhibited that N-C bonds were fewer when compared to other N-C bonds. The friction coefficient of the film deposited onto steel substrate with N/C=0.26 was measured to be ~0.08and for film with N/C=0.22 a high critical load of 70N was obtained. The tribological data also showed that the wear rates of these films were in the range of~10-16m3/Nm, indicating excellent wear resistance for CNxfilms.

  2. Effect of Hydrogen Dilution on Growth of Silicon Nanocrystals Embedded in Silicon Nitride Thin Film bv Plasma-Enhanced CVD

    Institute of Scientific and Technical Information of China (English)

    DING Wenge; ZHEN Lanfang; ZHANG Jiangyong; LI Yachao; YU Wei; FU Guangsheng

    2007-01-01

    An investigation was conducted into the effect of hydrogen dilution on the mi-crostructure and optical properties of silicon nanograins embedded in silicon nitride (Si/SiNx) thin film deposited by the helicon wave plasma-enhanced chemical vapour deposition technique. With Ar-diluted SiH4 and N2 as the reactant gas sources in the fabrication of thin film, the film was formed at a high deposition rate. There was a high density of defect at the amorphous silicon (a-Si)/SiNx interface and a relative low optical gap in the film. An addition of hydrogen into the reactant gas reduced the film deposition rate sharply. The silicon nanograins in the SiNx matrix were in a crystalline state, and the density of defects at the silicon nanocrystals (nc-Si)/SiNx interface decreased significantly and the optical gap of the films widened. These results suggested that hydrogen activated by the plasma could not only eliminate in the defects between the interface of silicon nanograins and SiNx matrix, but also helped the nanograins transform from the amorphous into crystalline state. By changing the hydrogen dilution ratio in the reactant gas sources, a tunable band gap from 1.87 eV to 3.32 eV was obtained in the Si/SiNx film.

  3. Atomic layer deposited tungsten nitride thin films as a new lithium-ion battery anode.

    Science.gov (United States)

    Nandi, Dip K; Sen, Uttam K; Sinha, Soumyadeep; Dhara, Arpan; Mitra, Sagar; Sarkar, Shaibal K

    2015-07-14

    This article demonstrates the atomic layer deposition (ALD) of tungsten nitride using tungsten hexacarbonyl [W(CO)6] and ammonia [NH3] and its use as a lithium-ion battery anode. In situ quartz crystal microbalance (QCM), ellipsometry and X-ray reflectivity (XRR) measurements are carried out to confirm the self-limiting behaviour of the deposition. A saturated growth rate of ca. 0.35 Å per ALD cycle is found within a narrow temperature window of 180-195 °C. In situ Fourier transform infrared (FTIR) vibrational spectroscopy is used to determine the reaction pathways of the surface bound species after each ALD half cycle. The elemental presence and chemical composition is determined by XPS. The as-deposited material is found to be amorphous and crystallized to h-W2N upon annealing at an elevated temperature under an ammonia atmosphere. The as-deposited materials are found to be n-type, conducting with an average carrier concentration of ca. 10(20) at room temperature. Electrochemical studies of the as-deposited films open up the possibility of this material to be used as an anode material in Li-ion batteries. The incorporation of MWCNTs as a scaffold layer further enhances the electrochemical storage capacity of the ALD grown tungsten nitride (WNx). Ex situ XRD analysis confirms the conversion based reaction mechanism of the as-grown material with Li under operation.

  4. Surface enhanced Raman scattering activity of TiN thin film prepared via nitridation of sol-gel derived TiO2 film

    Science.gov (United States)

    Dong, Zhanliang; Wei, Hengyong; Chen, Ying; Wang, Ruisheng; Zhao, Junhong; Lin, Jian; Bu, Jinglong; Wei, Yingna; Cui, Yi; Yu, Yun

    2015-10-01

    Surface-enhanced Raman scattering (SERS) is a powerful and non-destructive analytical technique tool for chemical and biological sensing applications. Metal-free SERS substrates have recently been developed by using semiconductor nanostructures. The optical property of TiN film is similar to that of gold. Besides that, its good chemical inertness and thermodynamic stability make TiN thin film an excellent candidate for SERS. In order to investigate its SERS activity, the TiN thin film was successfully prepared via direct nitridation of the sol-gel derived TiO2 thin film on the quartz substrate using ammonia gas as reducing agent. The crystallite structures and morphology of TiN thin film were determined by XRD, RAMAN and FE-SEM. The results show that the thin film obtained is cubic titanium nitride with a lattice parameter of 4.2349 Å. The surface of TiN thin film is rough and with the particles of 50 nm in average sizes. The thickness of TiN thin film is about 130 nm. The TiN thin film displays a surface Plasmon resonance absorption peak at around 476 nm, which can lead to a strong enhancement of the EM field on the interface. The Raman signal of the probe molecule R6G was greatly enhanced through TiN thin film substrates. The enhancement factor is about 4.1×103 and the detection limit achieves 10-6 M for R6G. The TiN thin film substrate also shows a good reproducibility of SERS performance. The results indicate that TiN thin film is an attractive material with potential application in SERS substrates.

  5. Metal-functionalized single-walled graphitic carbon nitride nanotubes: a first-principles study on magnetic property

    Directory of Open Access Journals (Sweden)

    Shenoy Vivek

    2011-01-01

    Full Text Available Abstract The magnetic properties of metal-functionalized graphitic carbon nitride nanotubes were investigated based on first-principles calculations. The graphitic carbon nitride nanotube can be either ferromagnetic or antiferromagnetic by functionalizing with different metal atoms. The W- and Ti-functionalized nanotubes are ferromagnetic, which are attributed to carrier-mediated interactions because of the coupling between the spin-polarized d and p electrons and the formation of the impurity bands close to the band edges. However, Cr-, Mn-, Co-, and Ni-functionalized nanotubes are antiferromagnetic because of the anti-alignment of the magnetic moments between neighboring metal atoms. The functionalized nanotubes may be used in spintronics and hydrogen storage.

  6. Vanadium nitride quantum dot/nitrogen-doped microporous carbon nanofibers electrode for high-performance supercapacitors

    Science.gov (United States)

    Wu, Yage; Ran, Fen

    2017-03-01

    In this article, vanadium nitride quantum dot/nitrogen-doped microporous carbon nanofibers (VNQD/CNF) is developed by a method of combination of electrostatic spinning and high-temperature calcination under the atmosphere of NH3: N2 = 3: 2 for high performance supercapacitors. VNQD dispersing into CNF, enrichment of N atom doped in carbon bulk, and abundant porous structure not only prevent the growth and aggregation of VN nanoparticles, improve electrical conductivity, wettability, and stability of the electrode materials, but also enhance fast migration of electrolyte ions during the electrochemical process. Thus, VNQD/CNF exhibits a high specific capacitance of 406.5 F g-1 at 0.5 A g-1 and a good rate capability with a capacitance retention of 75.1% at 5.0 A g-1. Additionally, VNQD/CNF as a negative electrode are combined with Ni(OH)2 as a positive electrode to fabricate the hybrid supercapacitor of VNQD/CNF//Ni(OH)2. Remarkably, at a power density of 774.6 W kg-1, the supercapacitor device delivers an ultrahigh energy density of 31.2 Wh kg-1.

  7. Enhanced visible light photocatalytic degradation of Rhodamine B over phosphorus doped graphitic carbon nitride

    Science.gov (United States)

    Chai, Bo; Yan, Juntao; Wang, Chunlei; Ren, Zhandong; Zhu, Yuchan

    2017-01-01

    Phosphorus doped graphitic carbon nitride (g-C3N4) was easily synthesized using ammonium hexafluorophosphate (NH4PF6) as phosphorus source, and ammonium thiocyanate (NH4SCN) as g-C3N4 precursor, through a direct thermal co-polycondensation procedure. The obtained phosphorus doped g-C3N4 was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), UV-vis diffuse reflectance absorption spectra (UV-DRS), photoelectrochemical measurement and photoluminescence spectra (PL). The photocatalytic activities of phosphorus doped g-C3N4 samples were evaluated by degradation of Rhodamine B (RhB) solution under visible light irradiation. The results showed that the phosphorus doped g-C3N4 had a superior photocatalytic activity than that of pristine g-C3N4, attributing to the phosphorus atoms substituting carbon atoms of g-C3N4 frameworks to result in light harvesting enhancement and delocalized π-conjugated system of this copolymer, beneficial for the increase of photocatalytic performance. The photoelectrochemical measurements also verified that the charge carrier separation efficiency was promoted by phosphorus doping g-C3N4. Moreover, the tests of radical scavengers demonstrated that the holes (h+) and superoxide radicals (rad O2-) were the main active species for the degradation of RhB.

  8. Synthesis of silicon carbide-silicon nitride composite ultrafine particles using a carbon dioxide laser

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Masaaki; Maniette, Yves; Nakata, Yoshinori; Okutani, Takeshi (Government Industrial Development Lab., Hokkaido, Sapporo (Japan))

    1993-05-01

    The synthesis and the structure of silicon carbide-silicon nitride (SiC-Si[sub 3]N[sub 4]) composite ultrafine particles have been studied. SiC-Si[sub 3]N[sub 4] composite ultrafine particles were prepared by irradiating a SiH[sub 4], C[sub 2]H[sub 4], and NH[sub 3] gas mixture with a CO[sub 2] laser at atmospheric pressure. The composition of composite powders changed with the reactant gas flow rate. The carbon and nitrogen content of the powder could be controlled in a wide range from 0 to 30 wt%. The composite powder, which contained 25.3 wt% carbon and 5.8 wt% nitrogen, had a [beta]-SiC structure. As the nitrogen content increased, SiC decreased and amorphous phase, Si[sub 3]N[sub 4], Si appeared. The results of XPS and lattice constant measurements suggested that Si, C, and N atoms were intimately mixed in the composite particles.

  9. Polymeric Graphitic Carbon Nitride Doped with CuO Dispersed on Dealuminated Clinoptilolite (CuO/HCP): Synthesis and Characterisation

    OpenAIRE

    Saheed Olalekan Sanni; Omoruyi Gold Idemudia

    2015-01-01

    CuO dispersed on dealuminated clinoptilolite (CuO/HCP) and further doped with polymeric graphitic carbon nitride (CuO/HCP-g-C3N4) was synthesized through 2 facile routes: precipitation method for CuO/HCP and impregnation through ultrasonication method for the hybrid composite material. The hybrid composite material crystalline phase, surface morphology, and structural and thermal properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-r...

  10. Improvement in nano-hardness and corrosion resistance of low carbon steel by plasma nitriding with negative DC bias voltage

    Science.gov (United States)

    Alim, Mohamed Mounes; Saoula, Nadia; Tadjine, Rabah; Hadj-Larbi, Fayçal; Keffous, Aissa; Kechouane, Mohamed

    2016-10-01

    In this work, we study the effect of plasma nitriding on nano-hardness and corrosion resistance of low carbon steel samples. The plasma was generated through a radio-frequency inductively coupled plasma source. The substrate temperature increased (by the self-induced heating mechanism) with the treatment time for increasing negative bias voltages. X-rays diffraction analysis revealed the formation of nitride phases (ɛ-Fe2-3N and γ'-Fe4N) in the compound layer of the treated samples. A phase transition occurred from 3.5 kV to 4.0 kV and was accompanied by an increase in the volume fraction of the γ'-Fe4N phase and a decrease in that of the ɛ-Fe2-3N phase. Auger electron spectroscopy revealed a deep diffusion of the implanted nitrogen beyond 320 nm. The nano-hardness increased by ~400% for the nitrogen-implanted samples compared to the untreated state, the nitride phases are believed to participate to the hardening. Potentiodynamic polarization measurements revealed that the plasma nitriding has improved the corrosion resistance behavior of the material. When compared to the untreated state, the sample processed at 4.0 kV exhibits a shift of +500 mV and a reduction to 3% in its corrosion current. These results were obtained for relatively low bias voltages and short treatment time (2 h).

  11. Effective Third-Order Nonlinearities in Metallic Refractory Titanium Nitride Thin Films

    CERN Document Server

    Kinsey, Nathaniel; Courtwright, Devon; DeVault, Clayton; Bonner, Carl E; Gavrilenko, Vladimir I; Shalaev, Vladimir M; Hagan, David J; Van Stryland, Eric W; Boltasseva, Alexandra

    2015-01-01

    Nanophotonic devices offer an unprecedented ability to concentrate light into small volumes which can greatly increase nonlinear effects. However, traditional plasmonic materials suffer from low damage thresholds and are not compatible with standard semiconductor technology. Here we study the nonlinear optical properties in the novel refractory plasmonic material titanium nitride using the Z scan method at 1550 nm and 780 nm. We compare the extracted nonlinear parameters for TiN with previous works on noble metals and note a similarly large nonlinear optical response. However, TiN films have been shown to exhibit a damage threshold up to an order of magnitude higher than gold films of a similar thickness, while also being robust, cost-efficient, bio- and CMOS compatible. Together, these properties make TiN a promising material for metal-based nonlinear optics.

  12. Synthesis of atomically thin hexagonal boron nitride films on nickel foils by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Nakhaie, S.; Wofford, J. M.; Schumann, T.; Jahn, U.; Ramsteiner, M.; Hanke, M.; Lopes, J. M. J., E-mail: lopes@pdi-berlin.de; Riechert, H. [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2015-05-25

    Hexagonal boron nitride (h-BN) is a layered two-dimensional material with properties that make it promising as a dielectric in various applications. We report the growth of h-BN films on Ni foils from elemental B and N using molecular beam epitaxy. The presence of crystalline h-BN over the entire substrate is confirmed by Raman spectroscopy. Atomic force microscopy is used to examine the morphology and continuity of the synthesized films. A scanning electron microscopy study of films obtained using shorter depositions offers insight into the nucleation and growth behavior of h-BN on the Ni substrate. The morphology of h-BN was found to evolve from dendritic, star-shaped islands to larger, smooth triangular ones with increasing growth temperature.

  13. Uniform non-stoichiometric titanium nitride thin films for improved kinetic inductance detector array

    CERN Document Server

    Coiffard, G; Driessen, E F C; Pignard, S; Calvo, M; Catalano, A; Goupy, J; Monfardini, A

    2015-01-01

    We describe the fabrication of homogeneous sub-stoichiometric titanium nitride films for microwave kinetic inductance detector (mKID) arrays. Using a 6 inch sputtering target and a homogeneous nitrogen inlet, the variation of the critical temperature over a 2 inch wafer was reduced to <25 %. Measurements of a 132-pixel mKID array from these films reveal a sensitivity of 16 kHz/pW in the 100 GHz band, comparable to the best aluminium mKIDs. We measured a noise equivalent power of NEP = 3.6e-15 Hz/Hz^(1/2). Finally, we describe possible routes to further improve the performance of these TiN mKID arrays.

  14. Thickness Influence on In Vitro Biocompatibility of Titanium Nitride Thin Films Synthesized by Pulsed Laser Deposition

    Directory of Open Access Journals (Sweden)

    Liviu Duta

    2016-01-01

    Full Text Available We report a study on the biocompatibility vs. thickness in the case of titanium nitride (TiN films synthesized on 410 medical grade stainless steel substrates by pulsed laser deposition. The films were grown in a nitrogen atmosphere, and their in vitro cytotoxicity was assessed according to ISO 10993-5 [1]. Extensive physical-chemical analyses have been carried out on the deposited structures with various thicknesses in order to explain the differences in biological behavior: profilometry, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy (XPS, X-ray diffraction and surface energy measurements. XPS revealed the presence of titanium oxynitride beside TiN in amounts that vary with the film thickness. The cytocompatibility of films seems to be influenced by their TiN surface content. The thinner films seem to be more suitable for medical applications, due to the combined high values of bonding strength and superior cytocompatibility.

  15. Transition-metal embedded carbon nitride monolayers: high-temperature ferromagnetism and half-metallicity

    Science.gov (United States)

    Choudhuri, Indrani; Kumar, Sourabh; Mahata, Arup; Rawat, Kuber Singh; Pathak, Biswarup

    2016-07-01

    High-temperature ferromagnetic materials with planar surfaces are promising candidates for spintronics applications. Using state-of-the-art density functional theory (DFT) calculations, transition metal (TM = Cr, Mn, and Fe) incorporated graphitic carbon nitride (TM@gt-C3N4) systems are investigated as possible spintronics devices. Interestingly, ferromagnetism and half-metallicity were observed in all of the TM@gt-C3N4 systems. We find that Cr@gt-C3N4 is a nearly half-metallic ferromagnetic material with a Curie temperature of ~450 K. The calculated Curie temperature is noticeably higher than other planar 2D materials studied to date. Furthermore, it has a steel-like mechanical stability and also possesses remarkable dynamic and thermal (500 K) stability. The calculated magnetic anisotropy energy (MAE) in Cr@gt-C3N4 is as high as 137.26 μeV per Cr. Thereby, such material with a high Curie temperature can be operated at high temperatures for spintronics devices.High-temperature ferromagnetic materials with planar surfaces are promising candidates for spintronics applications. Using state-of-the-art density functional theory (DFT) calculations, transition metal (TM = Cr, Mn, and Fe) incorporated graphitic carbon nitride (TM@gt-C3N4) systems are investigated as possible spintronics devices. Interestingly, ferromagnetism and half-metallicity were observed in all of the TM@gt-C3N4 systems. We find that Cr@gt-C3N4 is a nearly half-metallic ferromagnetic material with a Curie temperature of ~450 K. The calculated Curie temperature is noticeably higher than other planar 2D materials studied to date. Furthermore, it has a steel-like mechanical stability and also possesses remarkable dynamic and thermal (500 K) stability. The calculated magnetic anisotropy energy (MAE) in Cr@gt-C3N4 is as high as 137.26 μeV per Cr. Thereby, such material with a high Curie temperature can be operated at high temperatures for spintronics devices. Electronic supplementary information (ESI

  16. Formation of Silicon/Carbon Core-Shell Nanowires Using Carbon Nitride Nanorods Template and Gold Catalyst

    Directory of Open Access Journals (Sweden)

    Ilyani Putri Jamal

    2013-01-01

    Full Text Available In this experiment, silicon/carbon (Si/C core-shell nanowires (NWs were synthesized using gold nanoparticles (Au NPs coated carbon nitride nanorods (CN NRs as a template. To begin with, the Au NPs coated CN NRs were prepared by using plasma-enhanced chemical vapor deposition assisted with hot-wire evaporation technique. Fourier transform infrared spectrum confirms the C–N bonding of the CN NRs, while X-ray diffraction pattern indicates the crystalline structure of the Au NPs and amorphous structure of the CN NRs. The Au NPs coated CN NRs were thermally annealed at temperature of 800°C in nitrogen ambient for one hour to induce the growth of Si/C core-shell NWs. The growth mechanism for the Si/C core-shell NWs is related to the nitrogen evolution and solid-liquid-solid growth process which is a result of the thermal annealing. The formation of Si/C core-shell NWs is confirmed by electron spectroscopic imaging analysis.

  17. Studies to Enhance Superconductivity in Thin Film Carbon

    Science.gov (United States)

    Pierce, Benjamin; Brunke, Lyle; Burke, Jack; Vier, David; Steckl, Andrew; Haugan, Timothy

    2012-02-01

    With research in the area of superconductivity growing, it is no surprise that new efforts are being made to induce superconductivity or increase transition temperatures (Tc) in carbon given its many allotropic forms. Promising results have been published for boron doping in diamond films, and phosphorus doping in highly oriented pyrolytic graphite (HOPG) films show hints of superconductivity.. Following these examples in the literature, we have begun studies to explore superconductivity in thin film carbon samples doped with different elements. Carbon thin films are prepared by pulsed laser deposition (PLD) on amorphous SiO2/Si and single-crystal substrates. Doping is achieved by depositing from (C1-xMx) single-targets with M = B4C and BN, and also by ion implantation into pure-carbon films. Previous research had indicated that Boron in HOPG did not elicit superconducting properties, but we aim to explore that also in thin film carbon and see if there needs to be a higher doping in the sample if trends were able to be seen in diamond films. Higher onset temperatures, Tc , and current densities, Jc, are hoped to be achieved with doping of the thin film carbon with different elements.

  18. Carbon emission reduction potentials through thinned wood in Japan

    Directory of Open Access Journals (Sweden)

    Ninomiya H

    2011-06-01

    Full Text Available Substituting fossil fuel with woody biomass for bioelectricity production has great potentials for carbon emission reductions while increasing forest productivity to increase carbon sequestration and improve ecological functionalities. Until recently, study on such potentials was very limited. Beginning in 2007, Japan’s special budgets were allocated for a 6-year intensive thinning on about 3.3 million ha of young stands for increasing carbon sinks in Japanese forests to meet the capped amount of 47.7 Tg CO2 year-1 allowed under the Marrakesh Accord. Because of only 30% of the thinned wood were used for sawntimber, CO2 and CH4 must have been emitted from the disposed thinned wood and wood waste. Such emissions and reduction potentials need to be assessed to provide future alternatives for climate change mitigation. We assessed carbon emission reduction potentials when woody biomass from thinned wood is fully utilized for bioelectricity production as compared with the generation of the same amount of energy produced under coal, oil, and natural gas scenarios. Our analytical results show that if all disposed thinned wood and wood waste are utilized to generate energy, about 62.6, 58.3, and 37.8 Tg CO2 year-1 could be prevented from emitting depending on emission scenarios or about 33.2, 30.9, and 20.0% of Japan’s reduction commitment to the Kyoto Protocol. On the other hand, if thinned wood and wood waste are not utilized, about 13.4 Tg CO2 year-1 would be released due to thinning. Our results suggest that incentives to reducing emission reductions in forest sector in the future climate change mitigation agreements will likely lead to large emission reductions, otherwise leakages due to thinning are unavoidable.

  19. Infrared analysis of thin films amorphous, hydrogenated carbon on silicon

    CERN Document Server

    Jacob, W; Schwarz-Selinger, T

    2000-01-01

    The infrared analysis of thin films on a thick substrate is discussed using the example of plasma-deposited, amorphous, hydrogenated carbon layers (a-C:H) on silicon substrates. The framework for the optical analysis of thin films is presented. The main characteristic of thin film optics is the occurrence of interference effects due to the coherent superposition of light multiply reflected at the various internal and external interfaces of the optical system. These interference effects lead to a sinusoidal variation of the transmitted and reflected intensity. As a consequence, the Lambert-Beer law is not applicable for the determination of the absorption coefficient of thin films. Furthermore, observable changes of the transmission and reflection spectra occur in the vicinity of strong absorption bands due to the Kramers-Kronig relation. For a sound data evaluation these effects have to be included in the analysis. To be able to extract the full information contained in a measured optical thin film spectrum, ...

  20. Assembly and Applications of Carbon Nanotube Thin Films

    Institute of Scientific and Technical Information of China (English)

    Hongwei ZHU; Bingqing WEI

    2008-01-01

    The ultimate goal of current research on carbon nanotubes (CNTs) is to make breakthroughs that advance nanotechnological applications of bulk CNT materials. Especially, there has been growing interest in CNT thin films because of their unique and usually enhanced properties and tremendous potential as components for use in nano-electronic and nano-mechanical device applications or as structural elements in various devices. If a synthetic or a post processing method can produce high yield of nanotube thin films, these structures will provide tremendous potential for fundamental research on these devices. This review will address the synthesis, the post processing and the device applications of self-assembled nanotube thin films.

  1. Novel Hybrid Nanoparticles of Vanadium Nitride/Porous Carbon as an Anode Material for Symmetrical Supercapacitor

    Institute of Scientific and Technical Information of China (English)

    Yunlong Yang; Kuiwen Shen; Ying Liu; Yongtao Tan; Xiaoning Zhao; Jiayu Wu; Xiaoqin Niu; Fen Ran

    2017-01-01

    Hybrid materials of vanadium nitride and porous carbon nanoparticles (VN/PCNPs) were fabricated by a facile pyrolysis process of vanadium pentoxide (V2O5) xerogel and melamine at relatively low temperature of 800 ?C for supercapacitor application. The effects of the feed ratio of V2O5 to melamine (r), and nitrogen flow rate on the microstructure and electrochemical performance were also investigated. It was found that the size of the as-synthesized nanoparticles is about 20 nm. Both r value and N2 flow rate have enormous impacts on morphology and microstructure of the nanoparticle, which correspondingly determined the electrochemical performance of the material. The VN/C hybrid nanoparticles exhibited high capacitive properties, and a maximum specific capacitance of 255.0 F g-1 was achieved at a current density of 1.0 A g-1 in 2 M KOH aqueous electrolyte and the potential range from 0 to -1.15 V. In addition, symmetrical supercapacitor fabricated with the as-synthesized VN/PCNPs presents a high specific capacitance of 43.5 F g-1 at 0.5 A g-1 based on the entire cell, and an energy density of 8.0 Wh kg-1 when the power density was 575 W kg-1. Even when the power density increased to 2831.5 W kg-1, the energy density still remained 6.1 Wh kg-1.

  2. Lattice mismatch induced curved configurations of hybrid boron nitride-carbon nanotubes

    Science.gov (United States)

    Zhang, Jin

    2016-10-01

    A unique curved configuration is observed in freestanding hybrid boron nitride-carbon nanotubes (BN-CNTs) based on molecular dynamics simulations, which, in previous studies, was tacitly assumed as a straight configuration. The physical fundamentals of this phenomenon are explored by using the continuum mechanics theory, where the curved configuration of BN-CNTs is found to be induced by the bending effect due to the lattice mismatch between the C domain and the BN domain. In addition, our results show that the curvature of the curved BN-CNTs is determined by their radius and composition. The curvature of BN-CNTs decreases with growing radius of BN-CNTs and becomes ignorable when their radius is relatively large. A non-monotonic relationship is detected between the curvature and the composition of BN-CNTs. Specifically, the curvature of BN-CNTs increases with growing BN concentration when the molar fraction of BN atoms is smaller than a critical value 0.52, but decreases with growing BN concentration when the molar fraction of BN atoms is larger than this critical value.

  3. Ag nanoparticles loaded on porous graphitic carbon nitride with enhanced photocatalytic activity for degradation of phenol

    Science.gov (United States)

    Han, Zhenwei; Wang, Nan; Fan, Hai; Ai, Shiyun

    2017-03-01

    Highly efficient photocatalyst of visible-light-driven Ag nanoparticles loaded on porous graphitic carbon nitride (g-C3N4) was prepared by the reduction of Ag ions on porous g-C3N4. The obtained Ag/porous g-C3N4 composite products were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflection spectra (DRS), thermal gravimetric analysis (TGA). The results demonstrated that a homogeneous distribution of Ag NPs of 10 nm was attached onto the surface of the porous g-C3N4. The prepared Ag/porous g-C3N4 samples were applied for catalyzing the degradation of phenol in water under visible light irradiation. Porous g-C3N4 demonstrated an excellent support for the formation and dispersion of small uniform Ag NPs. When the weight percentage of Ag reaches 5%, the nanohybrid exhibits superior photocatalytic activities compared to bulk g-C3N4, porous g-C3N4, and 2% Ag/porous g-C3N4 hybrids. The enhanced photocatalytic performance is due to the synergic effect between Ag and porous g-C3N4, which suppressed the recombination of photogenerated electron-hole pairs.

  4. Kinetically Enhanced Electrochemical Redox of Polysulfides on Polymeric Carbon Nitrides for Improved Lithium-Sulfur Batteries.

    Science.gov (United States)

    Liang, Ji; Yin, Lichang; Tang, Xiaonan; Yang, Huicong; Yan, Wensheng; Song, Li; Cheng, Hui-Ming; Li, Feng

    2016-09-28

    The kinetics and stability of the redox of lithium polysulfides (LiPSs) fundamentally determine the overall performance of lithium-sulfur (Li-S) batteries. Inspired by theoretical predictions, we herein validated the existence of a strong electrostatic affinity between polymeric carbon nitride (p-C3N4) and LiPSs, that can not only stabilize the redox cycling of LiPSs, but also enhance their redox kinetics. As a result, utilization of p-C3N4 in a Li-S battery has brought much improved performance in the aspects of high capacity and low capacity fading over prolonged cycling. Especially upon the application of p-C3N4, the kinetic barrier of the LiPS redox reactions has been significantly reduced, which has thus resulted in a better rate performance. Further density functional theory simulations have revealed that the origin of such kinetic enhancement was from the distortion of molecular configurations of the LiPSs anchored on p-C3N4. Therefore, this proof-of-concept study opens up a promising avenue to improve the performance of Li-S batteries by accelerating their fundamental electrochemical redox processes, which also has the potential to be applied in other electrochemical energy storage/conversion systems.

  5. Production and characterization of a novel carbon nanotube/titanium nitride nanocomposite

    Science.gov (United States)

    Baddour, Carole Emilie; Das, Kaushik; Vengallatore, Srikar; Meunier, Jean-Luc

    2016-12-01

    A novel titanium nitride (TiN)/carbon nanotube (CNT) nanocomposite is produced with the purpose to mechanically, structurally and chemically stabilize a ‘felt-like’ CNT growth structure. The CNTs are grown on stainless steel (SS) 304 by chemical vapor deposition using the direct growth method previously developed, which does not require the use of an additional catalyst precursor. The TiN coating is achieved by physical vapor deposition and is shown here to generate a nanocomposite with a porous three-dimensional architecture. The contact stiffness is evaluated using nanoindentation, and wetting properties of the TiN/CNT nanocomposites are determined from contact angle measurements. An increase in contact stiffness and effective elastic modulus with TiN coating time was observed. The TiN coating on the non-wetting CNT felt results in a wetting nanocomposite surface. The wetting property is found to be a function of the TiN coating thickness on the CNT structure.

  6. Immobilizing photogenerated electrons from graphitic carbon nitride for an improved visible-light photocatalytic activity.

    Science.gov (United States)

    Sun, Han; Cao, Yue; Feng, Leiyu; Chen, Yinguang

    2016-03-07

    Reducing the recombination probability of photogenerated electrons and holes is pivotal in enhancing the photocatalytic ability of graphitic carbon nitride (g-C3N4). Speeding the departure of photogenerated electrons is the most commonly used method of achieving this. To the best of our knowledge, there is no report on suppressing the recombination of photogenerated electron-hole pairs by immobilizing the electrons with ester functional groups. Here, for the first time the mesoporous g-C3N4 (mpg-C3N4) was integrated with polymethyl methacrylate, a polymer abundant in ester groups, which showed a photocatalytic activity unexpectedly higher than that of the original mpg-C3N4 under visible-light irradiation. Experimental observations, along with theoretical calculations, clarified that the impressive photocatalytic ability of the as-modified mpg-C3N4 was mainly derived from the immobilization of photogenerated electrons via an electron-gripping effect imposed by the ester groups in the polymethyl methacrylate. This novel strategy might also be applied in improving the photocatalytic performance of other semiconductors.

  7. Conductive Graphitic Carbon Nitride as an Ideal Material for Electrocatalytically Switchable CO2 Capture.

    Science.gov (United States)

    Tan, Xin; Kou, Liangzhi; Tahini, Hassan A; Smith, Sean C

    2015-12-01

    Good electrical conductivity and high electron mobility of the sorbent materials are prerequisite for electrocatalytically switchable CO2 capture. However, no conductive and easily synthetic sorbent materials are available until now. Here, we examined the possibility of conductive graphitic carbon nitride (g-C4N3) nanosheets as sorbent materials for electrocatalytically switchable CO2 capture. Using first-principle calculations, we found that the adsorption energy of CO2 molecules on g-C4N3 nanosheets can be dramatically enhanced by injecting extra electrons into the adsorbent. At saturation CO2 capture coverage, the negatively charged g-C4N3 nanosheets achieve CO2 capture capacities up to 73.9 × 10(13) cm(-2) or 42.3 wt%. In contrast to other CO2 capture approaches, the process of CO2 capture/release occurs spontaneously without any energy barriers once extra electrons are introduced or removed, and these processes can be simply controlled and reversed by switching on/off the charging voltage. In addition, these negatively charged g-C4N3 nanosheets are highly selective for separating CO2 from mixtures with CH4, H2 and/or N2. These predictions may prove to be instrumental in searching for a new class of experimentally feasible high-capacity CO2 capture materials with ideal thermodynamics and reversibility.

  8. Self-floating graphitic carbon nitride/zinc phthalocyanine nanofibers for photocatalytic degradation of contaminants.

    Science.gov (United States)

    Xu, Tiefeng; Ni, Dongjing; Chen, Xia; Wu, Fei; Ge, Pengfei; Lu, Wangyang; Hu, Hongguang; Zhu, ZheXin; Chen, Wenxing

    2016-11-05

    The effective elimination of micropollutants by an environmentally friendly method has received extensive attention recently. In this study, a photocatalyst based on polyacrylonitrile (PAN)-supported graphitic carbon nitride coupled with zinc phthalocyanine nanofibers (g-C3N4/ZnTcPc/PAN nanofibers) was successfully prepared, where g-C3N4/ZnTcPc was introduced as the catalytic entity and the PAN nanofibers were employed as support to overcome the defects of easy aggregation and difficult recycling. Herein, rhodamine B (RhB), 4-chlorophenol and carbamazepine (CBZ) were selected as the model pollutants. Compared with the typical hydroxyl radical-dominated catalytic system, g-C3N4/ZnTcPc/PAN nanofibers displayed the targeted adsorption and degradation of contaminants under visible light or solar irradiation in the presence of high additive concentrations. According to the results of the radical scavenging techniques and the electron paramagnetic resonance technology, the degradation of target substrates was achieved by the attack of active species, including photogenerated hole, singlet oxygen, superoxide radicals and hydroxyl radicals. Based on the results of ultra-performance liquid chromatography and mass spectrometry, the role of free radicals on the photocatalytic degradation intermediates was identified and the final photocatalytic degradation products of both RhB and CBZ were some biodegradable small molecules.

  9. Facile preparation and applications of graphitic carbon nitride coating in solid-phase microextraction.

    Science.gov (United States)

    Xu, Na; Wang, Yiru; Rong, Mingcong; Ye, Zhifeng; Deng, Zhuo; Chen, Xi

    2014-10-17

    In this study, graphitic carbon nitride (g-C3N4) was used as a coating material for solid-phase microextraction (SPME) applications. Coupled to gas chromatography (GC), the extraction ability of the SPME fiber was investigated and compared with the commercial fibers of 100 μm PDMS and 85 μm CAR/PDMS using six target analytes including deltamethrin, nerolidol, amphetamine, dodecane, ametryn and acrylamide. The g-C3N4 coating revealed excellent extraction ability and durability comparing with those of the commercial fibers due to its loose structure and unique physicochemical properties. The repeatability for each single fiber was found to be 3.46% and reproducibility for fiber to fiber was 8.53%. The g-C3N4 SPME fiber was applied to the determination of acrylamide in potato chips, the linearity and detection limit was 0.5-250 μg g(-1) and 0.018 μg g(-1), respectively.

  10. Coaxial carbon@boron nitride nanotube arrays with enhanced thermal stability and compressive mechanical properties

    Science.gov (United States)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Huang, Jingfeng; Tan, Dunlin; Zhang, Bowei; Teo, Edwin Hang Tong; Tok, Alfred Iing Yoong

    2016-05-01

    Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability. CNT arrays are grown using a commercially available thermal chemical vapor deposition (TCVD) technique and an outer BNNT with a wall thickness up to 1.37 nm is introduced by a post-growth TCVD treatment. Importantly, compared to the as-grown CNT arrays which deform almost plastically upon compression, the coaxial C@BNNT arrays exhibit an impressive ~4-fold increase in compressive strength with nearly full recovery after the first compression cycle at a 50% strain (76% recovery maintained after 10 cycles), as well as a significantly high and persistent energy dissipation ratio (~60% at a 50% strain after 100 cycles), attributed to the synergistic effect between the CNT and outer BNNT. Additionally, the as-prepared C@BNNT arrays show an improved structural stability in air at elevated temperatures, attributing to the outstanding thermal stability of the outer BNNT. This work provides new insights into tailoring the mechanical and thermal behaviours of arbitrary CNT arrays which enables a broader range of applications.Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability

  11. Sub-picowatt resolution calorimetry with niobium nitride thin-film thermometer

    Energy Technology Data Exchange (ETDEWEB)

    Dechaumphai, Edward; Chen, Renkun, E-mail: rkchen@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

    2014-09-15

    High-resolution calorimetry has many important applications such as probing nanoscale thermal transport and studying the thermodynamics of biological and chemical systems. In this work, we demonstrated a calorimeter with an unprecedentedly high resolution at room temperature using a high-performance resistive thermometry material, niobium nitride (NbN{sub x}). Based on a theoretical analysis, we first showed that the heat flux resolution of a resistive-thermometry based calorimeter depends on the parasitic thermal conductance of the device and the temperature coefficient of resistance (TCR) of the thermometer, when the noise is limited by the Johnson noise. Based on this analysis, we then developed a calorimeter using NbN{sub x} as the thermometry material because it possesses both high TCR (∼0.67%/K) and a low thermal conductivity (k ∼ 1.1 W/m K). This calorimeter, when used with the modulated heating scheme, demonstrated an unprecedentedly high power resolution of 0.26 pW at room temperature. In addition, NbN{sub x} based resistive thermometry can also be extended to cryogenic temperature, where the TCR is shown to be significantly higher.

  12. Ultra-thin SiN{sub x} in superlattice via nitridation of a-Si in-situ hot wire chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rai, Dharmendra Kumar; Solanki, Chetan Singh; Balasubramaniam, K.R., E-mail: bala.kavaipatti@gmail.com

    2014-08-28

    The fabrication of ultra-thin SiN{sub x} (< 2 nm) is a necessary step in third generation photovoltaics, memory, or light-emitting diode applications. Using the low temperature, cheap, scaleable synthesis technique of hot-wire chemical vapor deposition (HWCVD) for this purpose poses many challenges. Here, an approach of fabricating ultra thin SiN{sub x} of thickness ∼ 1.9 nm in a superlattice (SL) structure via nitridation of a-Si layers in-situ HWCVD at 250 °C is reported. Quantum well SL and quantum dot (QD) SL films are realized, wherein SiN{sub x} layers are formed by nitriding a-Si. Both these films investigated by Raman spectroscopy and high resolution transmission electron microscopy, reveal the formation of ultra-thin SiN{sub x} in a SL structure with a-Si, accompanied by sharp interfaces. In addition, annealing of the SL structures, results in QDs of crystalline Si in the a-Si layers, maintaining the SiN{sub x} layer as well as the sharp interface between the SiN{sub x} and a-Si layers of the as-deposited SL structure. - Highlights: • Ultra thin SiN{sub x} is fabricated by hot wire chemical vapor deposition. • SiN{sub x} layer of thickness ∼ 1.9 nm is formed via nitridation of a-Si layer at 250 °C. • Ultra thin SiN{sub x} layers are realized in superlattice films of quantum wells and quantum dots.

  13. Preparation and characterization of silicon nitride (Si−N)-coated carbon fibers and their effects on thermal properties in composites

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyeon-Hye [R& D Division, Korea Institute of Carbon Convergence Technology, Jeonju 561-844 (Korea, Republic of); Nano& Advanced Materials Engineering, Jeonju University, Jeonju 560-759 (Korea, Republic of); Han, Woong [R& D Division, Korea Institute of Carbon Convergence Technology, Jeonju 561-844 (Korea, Republic of); Lee, Hae-seong [Nano& Advanced Materials Engineering, Jeonju University, Jeonju 560-759 (Korea, Republic of); Min, Byung-Gak [Department of Polymer Science & Engineering, Korea National University of Transportation, Chungju 380-702 (Korea, Republic of); Kim, Byung-Joo, E-mail: ap2-kbj@hanmail.net [R& D Division, Korea Institute of Carbon Convergence Technology, Jeonju 561-844 (Korea, Republic of)

    2015-10-15

    Graphical abstract: We report preparation and characterization of silicon nitride (Si−N)-coated carbon fibers and their effects on thermal properties in composites. Thermally composites showed enhanced thermal conductivity increasing from up to 59% by the thermal network. - Highlights: • A new method of Si−N coating on carbon fibers was reported. • Silane layer were successfully converted to Si−N layer on carbon fiber surface. • Si−N formation was confirmed by FT-IR, XPS, and EDX. • Thermal conductivity of Si−N coated CF composites were enhanced to 0.59 W/mK. - Abstract: This study investigates the effect of silicon nitride (Si−N)-coated carbon fibers on the thermal conductivity of carbon-fiber-reinforced epoxy composite. The surface properties of the Si−N-coated carbon fibers (SiNCFs) were observe using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy, and the thermal stability was analyzed using thermogravimetric analysis. SiNCFs were fabricated through the wet thermal treatment of carbon fibers (Step 1: silane finishing of the carbon fibers; Step 2: high-temperature thermal treatment in a N{sub 2}/NH{sub 3} environment). As a result, the Si−N belt was exhibited by SEM. The average thickness of the belt were 450–500 nm. The composition of Si−N was the mixture of Si−N, Si−O, and C−Si−N as confirmed by XPS. Thermal residue of the SiNCFs in air was enhanced from 3% to 50%. Thermal conductivity of the composites increased from 0.35 to 0.59 W/mK after Si−N coating on carbon surfaces.

  14. Synthesis of thin films in boron-carbon-nitrogen ternary system by microwave plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Kukreja, Ratandeep Singh

    The Boron Carbon Nitorgen (B-C-N) ternary system includes materials with exceptional properties such as wide band gap, excellent thermal conductivity, high bulk modulus, extreme hardness and transparency in the optical and UV range that find application in most fields ranging from micro-electronics, bio-sensors, and cutting tools to materials for space age technology. Interesting materials that belong to the B-C-N ternary system include Carbon nano-tubes, Boron Carbide, Boron Carbon Nitride (B-CN), hexagonal Boron Nitride ( h-BN), cubic Boron Nitride (c-BN), Diamond and beta Carbon Nitride (beta-C3N4). Synthesis of these materials requires precisely controlled and energetically favorable conditions. Chemical vapor deposition is widely used technique for deposition of thin films of ceramics, metals and metal-organic compounds. Microwave plasma enhanced chemical vapor deposition (MPECVD) is especially interesting because of its ability to deposit materials that are meta-stable under the deposition conditions, for e.g. diamond. In the present study, attempt has been made to synthesize beta-carbon nitride (beta-C3N4) and cubic-Boron Nitride (c-BN) thin films by MPECVD. Also included is the investigation of dependence of residual stress and thermal conductivity of the diamond thin films, deposited by MPECVD, on substrate pre-treatment and deposition temperature. Si incorporated CNx thin films are synthesized and characterized while attempting to deposit beta-C3N4 thin films on Si substrates using Methane (CH4), Nitrogen (N2), and Hydrogen (H2). It is shown that the composition and morphology of Si incorporated CNx thin film can be tailored by controlling the sequence of introduction of the precursor gases in the plasma chamber. Greater than 100mum size hexagonal crystals of N-Si-C are deposited when Nitrogen precursor is introduced first while agglomerates of nano-meter range graphitic needles of C-Si-N are deposited when Carbon precursor is introduced first in the

  15. Localization and pair breaking parameter in superconducting molybdenum nitride thin films

    Science.gov (United States)

    Tsuneoka, Takuya; Makise, Kazumasa; Maeda, Sho; Shinozaki, Bunju; Ichikawa, Fusao

    2017-01-01

    We have investigated the superconductor-insulator transition in molybdenum nitride films prepared by deposition onto MgO substrates. It is indicated that the T c depression from ≈ 6.6 \\text{K} for thick films with increase of the normal state sheet resistance R\\text{sq}\\text{N} was well explained by the Finkel’stein formula from the localization theory. Present analysis suggests that the superconducting-insulator transition occurs at a critical sheet resistance {{R}\\text{c}}≈ 2 \\text{k} Ω . It is found that the {{R}\\text{sq}}(T) above {{R}\\text{c}} shows different characteristics of {{R}\\text{sq}}(T)={{R}\\text{sq,0}}-A\\ln T and {{R}\\text{sq}}(T)\\propto \\exp ≤ft[{≤ft({{T}0}/T\\right)}1/2}\\right] in the regions {{R}\\text{c}}\\text{sq}\\text{N}{{R}\\text{Q}} , respectively, where {{R}\\text{sq,0}} is the classical residual resistance and A is a constant. The excess conductance {{σ\\prime}{}(T) due to thermal fluctuation has been analyzed by the sum of the Aslamazov-Larkin and Maki-Thompson correction terms with use of the pair breaking parameter δ in the latter term. The sum agrees well with the data, although the experimental results of the R\\text{sq}\\text{N} dependence of δ , that is, δ \\propto {{≤ft(R\\text{sq}\\text{N}\\right)}≈ 1.7} shows the disagreement with a linear relation δ \\propto ≤ft(R\\text{sq}\\text{N}\\right) derived from the localization theory.

  16. Advances in targetry with thin diamond-like carbon foils

    CERN Document Server

    Liechtenstein, V K; Olshanski, E D; Repnow, R; Levin, J; Hellborg, R; Persson, P; Schenkel, T

    2002-01-01

    Thin and stable diamond-like carbon (DLC) foils, which were fabricated at the Kurchatov Institute by sputter deposition, have proved recently to be advantageous for stripping and secondary electron timing of high energy heavy ions in a number of accelerator experiments. This resulted in expanding applications of these DLC foils which necessitated further development efforts directed toward the following applications of DLC targetry: (i) thin stripper foils for lower energy tandem accelerators, (ii) enlarged (up to 66 mm in diameter) stop foils for improved time-of-flight elastic recoil detection ion beam analysis, and (iii) ultra-thin (about 0.6 mu g/cm sup 2) DLC foils for some fundamental and applied physics experiments. Along with the fabrication of thin DLC stripper foils for tandem accelerators, much thicker (up to 200 mu g/cm sup 2) foils for post-stripping of heavy-ion beams in higher energy linacs, are within reach.

  17. Fabrication of a Carbon Nanotube-Embedded Silicon Nitride Membrane for Studies of Nanometer-Scale Mass Transport

    Energy Technology Data Exchange (ETDEWEB)

    Holt, J K; Noy, A; Huser, T; Eaglesham, D; Bakajin, O

    2004-08-25

    A membrane consisting of multiwall carbon nanotubes embedded in a silicon nitride matrix was fabricated for fluid mechanics studies on the nanometer scale. Characterization by tracer diffusion and scanning electron microscopy suggests that the membrane is free of large voids. An upper limit to the diffusive flux of D{sub 2}O of 2.4x10-{sup 8} mole/m{sup 2}-s was determined, indicating extremely slow transport. By contrast, hydrodynamic calculations of water flow across a nanotube membrane of similar specifications predict a much higher molar flux of 1.91 mole/m{sup 2}-s, suggesting that the nanotubes produced possess a 'bamboo' morphology. The carbon nanotube membranes were used to make nanoporous silicon nitride membranes, fabricated by sacrificial removal of the carbon. Nitrogen flow measurements on these structures give a membrane permeance of 4.7x10{sup -4} mole/m{sup 2}-s-Pa at a pore density of 4x10{sup 10} cm{sup -2}. Using a Knudsen diffusion model, the average pore size of this membrane is estimated to be 66 nm, which agrees well with TEM observations of the multiwall carbon nanotube outer diameter. These membranes are a robust platform for the study of confined molecular transport, with applications inseparations and chemical sensing.

  18. Stabilization of ultrafine metal nanocatalysts on thin carbon sheets

    Science.gov (United States)

    Liu, Xiaofang; Cui, Xinrui; Liu, Yiding; Yin, Yadong

    2015-10-01

    A novel strategy was proposed to anchor ultrafine metal nanoparticles (NPs) on thin carbon sheets for highly stable and efficient heterogeneous catalysts. In this facile approach, a dense monolayer of ultrafine AuNPs was sandwiched between a silica core and a resin shell, followed by carbonization of the shell at a high temperature and then selective removal of the silica core. The shrinkage of the shells during carbonization facilitates partial embedment of the AuNPs on the carbon shell surface and provides superior stability against particle sintering during high temperature/mechanical post-treatments and catalytic reactions. It was also found that diffusion of reactants to the surface of AuNPs could be maximized by reducing the thickness of the hollow shells or simply by cracking the shells into thin carbon sheets, both significantly benefiting the catalytic efficiency. The advantages of this ultra-stable architecture together with the densely dispersed catalytic sites were demonstrated by their high stability and superior catalytic activity in reducing hydrophilic 4-nitrophenol and hydrophobic nitrobenzene.A novel strategy was proposed to anchor ultrafine metal nanoparticles (NPs) on thin carbon sheets for highly stable and efficient heterogeneous catalysts. In this facile approach, a dense monolayer of ultrafine AuNPs was sandwiched between a silica core and a resin shell, followed by carbonization of the shell at a high temperature and then selective removal of the silica core. The shrinkage of the shells during carbonization facilitates partial embedment of the AuNPs on the carbon shell surface and provides superior stability against particle sintering during high temperature/mechanical post-treatments and catalytic reactions. It was also found that diffusion of reactants to the surface of AuNPs could be maximized by reducing the thickness of the hollow shells or simply by cracking the shells into thin carbon sheets, both significantly benefiting the

  19. Synthesis and characterization of atomic layer deposited titanium nitride thin films on lithium titanate spinel powder as a lithium-ion battery anode

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, Mark Q.; Wheeler, M. Clayton [Department of Chemical and Biological Engineering, University of Maine, 5737 Jenness Hall, Orono, ME 04469 (United States); Trebukhova, Svetlana A.; Ravdel, Boris; DiCarlo, Joseph [Yardney Technical Products/Lithion Inc., Pawcatuck, CT 06379 (United States); Tripp, Carl P. [Laboratory for Surface Science and Technology (LASST), 5708 ESRB-Barrows, Orono, ME 04469 (United States); Department of Chemistry, University of Maine, Orono, ME 04469 (United States); DeSisto, William J. [Department of Chemical and Biological Engineering, University of Maine, 5737 Jenness Hall, Orono, ME 04469 (United States); Laboratory for Surface Science and Technology (LASST), 5708 ESRB-Barrows, Orono, ME 04469 (United States)

    2007-02-25

    Lithium titanate spinel (Li{sub 4}Ti{sub 5}O{sub 12}, or LTS) is receiving consideration as a nanopowder anode material for use in lithium-ion batteries. LTS has more positive working potential than traditional graphite anodes, and it does not react with electrolyte components. However, the main drawback of LTS powder is its poor interparticle electronic conductance that reduces the high-rate ability of the electrode. To improve this we have coated the surface of the LTS powder with a titanium nitride layer by atomic layer deposition (ALD). In situ infrared spectroscopy studies were conducted to confirm the attachment of the titanium precursor. The nitrogen content of films was measured by total nitrogen content testing. Transmission electron microscopy (TEM) micrographs confirmed the formation of a thin titanium nitride film around LTS particles by ALD. Finally, lithium cells with electrodes made of original and modified LTS nanopowders were assembled and tested. (author)

  20. Carbon Nanotubes for Thin Film Transistor: Fabrication, Properties, and Applications

    Directory of Open Access Journals (Sweden)

    Yucui Wu

    2013-01-01

    Full Text Available We review the present status of single-walled carbon nanotubes (SWCNTs for their production and purification technologies, as well as the fabrication and properties of single-walled carbon nanotube thin film transistors (SWCNT-TFTs. The most popular SWCNT growth method is chemical vapor deposition (CVD, including plasma-enhanced chemical vapor deposition (PECVD, floating catalyst chemical vapor deposition (FCCVD, and thermal CVD. Carbon nanotubes (CNTs used to fabricate thin film transistors are sorted by electrical breakdown, density gradient ultracentrifugation, or gel-based separation. The technologies of applying CNT random networks to work as the channels of SWCNT-TFTs are also reviewed. Excellent work from global researchers has been benchmarked and analyzed. The unique properties of SWCNT-TFTs have been reviewed. Besides, the promising applications of SWCNT-TFTs have been explored. Finally, the key issues to be solved in future have been summarized.

  1. The Multiple Effects of Precursors on the Properties of Polymeric Carbon Nitride

    Directory of Open Access Journals (Sweden)

    Wendong Zhang

    2013-01-01

    Full Text Available Polymeric graphitic carbon nitride (g-C3N4 materials were prepared by direct pyrolysis of thiourea, dicyandiamide, melamine, and urea under the same conditions, respectively. In order to investigate the effects of precursors on the intrinsic physicochemical properties of g-C3N4, a variety of characterization tools were employed to analyze the samples. The photocatalytic activity of the samples was evaluated by the removal of NO in gas phase under visible light irradiation. The results showed that the as-prepared CN-T (from thiourea, CN-D (from dicyandiamide, CN-M (from melamine, and CN-U (from urea exhibited significantly different morphologies and microstructures. The band gaps of CN-T, CN-D, CN-M, and CN-U were 2.51, 2.58, 2.56, and 2.88 eV, respectively. Both thermal stability and yield are in the following order: CN-M > CN-D > CN-T > CN-U. The photoactivity of CN-U (31.9% is higher than that of CN-T (29.6%, CN-D (22.2%, and CN-M (26.8%. Considering the cost, toxicity, and yield of the precursors and the properties of g-C3N4, the best precursor for preparation of g-C3N4 was melamine. The present work could provide new insights into the selection of suitable precursor for g-C3N4 synthesis and in-depth understanding of the microstructure-dependent photocatalytic activity of g-C3N4.

  2. Photoluminescence Study of Gallium Nitride Thin Films Obtained by Infrared Close Space Vapor Transport

    Directory of Open Access Journals (Sweden)

    Luis A. Hernández

    2013-03-01

    Full Text Available Photoluminescence (PL studies in GaN thin films grown by infrared close space vapor transport (CSVT-IR in vacuum are presented in this work. The growth of GaN thin films was done on a variety of substrates like silicon, sapphire and fused silica. Room temperature PL spectra of all the GaN films show near band-edge emission (NBE and a broad blue and green luminescence (BL, GL, which can be seen with the naked eye in a bright room. The sample grown by infrared CSVT on the silicon substrate shows several emission peaks from 2.4 to 3.22 eV with a pronounced red shift with respect to the band gap energy. The sample grown on sapphire shows strong and broad ultraviolet emission peaks (UVL centered at 3.19 eV and it exhibits a red shift of NBE. The PL spectrum of GaN films deposited on fused silica exhibited a unique and strong blue-green emission peak centered at 2.38 eV. The presence of yellow and green luminescence in all samples is related to native defects in the structure such as dislocations in GaN and/or the presence of amorphous phases. We analyze the material quality that can be obtained by CSVT-IR in vacuum, which is a high yield technique with simple equipment set-up, in terms of the PL results obtained in each case.

  3. Novel band gap-tunable K–Na co-doped graphitic carbon nitride prepared by molten salt method

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jiannan [Institute of Eco-environmental Sciences, Liaoning Shihua University, Fushun 113001 (China); School of Environmental and Biological Engineering, Liaoning Shihua University, Fushun 113001 (China); Ma, Lin [School of Petrochemical Engineering, Liaoning Shihua University, Fushun 113001 (China); Wang, Haoying; Zhao, Yanfeng [School of Environmental and Biological Engineering, Liaoning Shihua University, Fushun 113001 (China); Zhang, Jian [School of Petrochemical Engineering, Liaoning Shihua University, Fushun 113001 (China); Hu, Shaozheng, E-mail: hushaozhenglnpu@163.com [Institute of Eco-environmental Sciences, Liaoning Shihua University, Fushun 113001 (China)

    2015-03-30

    Graphical abstract: K and Na ions co-doped into g-C{sub 3}N{sub 4} crystal lattice can tune the position of CB and VB potentials, influence the structural and optical properties, and thus improve the photocatalytic degradation and mineralization ability. - Highlights: • K, Na co-doped g-C{sub 3}N{sub 4} was prepared in KCl/NaCl molten salt system. • The structural and optical properties of g-C{sub 3}N{sub 4} were greatly influenced by co-doping. • The position of VB and CB can be tuned by controlling the weight ratio of eutectic salts to melamine. • Co-doped g-C{sub 3}N{sub 4} showed outstanding photodegradation ability, mineralization ability, and catalytic stability. - Abstract: Novel band gap-tunable K–Na co-doped graphitic carbon nitride was prepared by molten salt method using melamine, KCl, and NaCl as precursor. X-ray diffraction (XRD), N{sub 2} adsorption, Scanning electron microscope (SEM), UV–vis spectroscopy, Photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared catalysts. The CB and VB potentials of graphitic carbon nitride could be tuned from −1.09 and +1.55 eV to −0.29 and +2.25 eV by controlling the weight ratio of eutectic salts to melamine. Besides, ions doping inhibited the crystal growth of graphitic carbon nitride, enhanced the surface area, and increased the separation rate of photogenerated electrons and holes. The visible-light-driven Rhodamine B (RhB) photodegradation and mineralization performances were significantly improved after K–Na co-doping.

  4. Structural characterization of thin films of titanium nitride deposited by laser ablation; Caracterizacion estructural de peliculas delgadas de nitruro de titanio depositadas por ablacion laser

    Energy Technology Data Exchange (ETDEWEB)

    Castro C, M.A.; Escobar A, L.; Camps C, E.; Mejia H, J.A. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    Thin films of titanium nitride were deposited using the technique of laser ablation. It was studied the effect of the density of laser energy used for ablation the target as well as of the pressure of the work gas about the structure and the hardness of the deposited thin films. Depending on the pressure of the work gas films was obtained with preferential orientation in the directions (200) and (111). At a pressure of 1 x 10{sup -2} Torr only the direction (200) was observed. On the other hand to the pressure of 5 x 10{sup -3} Torr the deposited material this formed by a mixture of the orientation (200) and (111), being the direction (111) the predominant one. Thin films of Ti N were obtained with hardness of up to 24.0 GPa that makes to these attractive materials for mechanical applications. The hardness showed an approximately linear dependence with the energy density. (Author)

  5. Aluminum nitride thin film based acoustic wave sensors for biosensing applications

    Science.gov (United States)

    Xu, Jianzeng

    In recent years, SAW devices have drawn enormous interest from the analytical assay and sensing business, especially in the biosensing area where highly sensitive, cost efficient and miniaturized sensors are in urgent needs. This dissertation focuses on the development of AIN thin film based SAW devices suitable for biosensing applications. AIN thin films have been synthesized on different orientations of sapphire substrates by a plasma source molecular beam epitaxy system. Surface and structural characterization techniques have been applied to investigate the film quality and the results show that high quality c-plane AIN was epitaxially grown on both c-plane and a-plane sapphire substrates. Complete process flows have been developed for the fabrication of SAW delay line and resonator devices. Important electrical parameters such as the insertion loss, bandwidth, and impedance have been measured to assist the design optimization and derivation the phase velocity, electromechanical coupling coefficient, and temperature coefficient of frequency. On both c-plane and a-plane sapphire substrates, the SAW phase velocities (˜5700 m/s) and electromechanical coupling coefficients (˜0.3%) have been thoroughly mapped out with respect to the propagation direction and film thickness to wavelength ratio. The data are of practical importance for designing AIN-based SAW devices. A higher velocity (>6000 m/s) shear horizontal SAW mode has been discovered only at isolated propagating directions. This mode is especially suitable for aqueous biosensing due to its weak energy coupling to liquid. Much stronger response of the SH-SAW mode has been detected on the c-plane AIN on a-plane sapphire structure than on the c-plane AIN on c-plane sapphire structure, which could be attributed to large anisotropy in a-plane sapphire substrate. Linear frequency-temperature relationship has also been observed for both modes. We further quantify the mass sensitivity of the SAW and SH-SAW by

  6. Structural Characterization of Atomically Thin Hexagonal Boron Nitride via Raman Spectroscopy

    Science.gov (United States)

    2014-03-27

    successfully been doped with carbon for use in neutron detectors [8]. 3 Figure 1.1: Currently, only graphene on a h-BN substrate has been...collecting the h- BN spectra to include the selection of appropriate excitation sources, use of filtering packages, and focusing objective. Chapter 4...of one another, it is often the practice of Raman spectroscopy to filter out both the Rayleigh laser line and anti- Stokes lines to solely isolate

  7. A Monolithically Integrated Gallium Nitride Nanowire/Silicon Solar Cell Photocathode for Selective Carbon Dioxide Reduction to Methane.

    Science.gov (United States)

    Wang, Yichen; Fan, Shizhao; AlOtaibi, Bandar; Wang, Yongjie; Li, Lu; Mi, Zetian

    2016-06-20

    A gallium nitride nanowire/silicon solar cell photocathode for the photoreduction of carbon dioxide (CO2 ) is demonstrated. Such a monolithically integrated nanowire/solar cell photocathode offers several unique advantages, including the absorption of a large part of the solar spectrum and highly efficient carrier extraction. With the incorporation of copper as the co-catalyst, the devices exhibit a Faradaic efficiency of about 19 % for the 8e(-) photoreduction to CH4 at -1.4 V vs Ag/AgCl, a value that is more than thirty times higher than that for the 2e(-) reduced CO (ca. 0.6 %).

  8. Application of magnetic graphitic carbon nitride nanocomposites for the solid-phase extraction of phthalate esters in water samples.

    Science.gov (United States)

    Wang, Man; Yang, Xiaodi; Bi, Wentao

    2015-02-01

    Magnetic graphitic carbon nitride nanocomposites were successfully prepared in situ and used to develop a highly sensitive magnetic solid-phase extraction method for the preconcentration of phthalate esters such as di-n-butyl phthalate, butyl phthalate, dihexyl phthalate, and di-(2-ethyl hexyl) phthalate from water. The adsorption and desorption of the phthalate esters on magnetic graphitic carbon nitride nanocomposites were investigated and the parameters affecting the partition of the phthalate esters, such as adsorption, desorption, recovery, were assessed. Under the optimized conditions, the proposed method showed excellent sensitivity with limits of detection (S/N = 3) in the range of 0.05-0.1 μg/L and precision in the range of 1.1-2.6% (n = 5). This method was successfully applied to the analysis of real water samples, and good spiked recoveries over the range of 79.4-99.4% were obtained. This research provides a possibility to apply this nanocomposite for adsorption, preconcentration, or even removal of various carbon-based ring or hydrophobic pollutants.

  9. Correlation between iron self-diffusion and thermal stability in doped iron nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tayal, Akhil; Gupta, Mukul, E-mail: mgupta@csr.res.in, E-mail: dr.mukul.gupta@gmail.com; Kumar, D.; Reddy, V. R.; Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 001 (India); Amir, S. M. [Jülich Centre for Neutron Science, Forschungszentrum Jülich GmbH, Outstation at MLZ Lichtenbergstrasse 1, 85747 Garching (Germany); Korelis, Panagiotis; Stahn, Jochen [Laboratory for Neutron Scattering, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

    2014-12-14

    Nanocrystalline Fe-X-N thin films (with doping X = 0, 3.1 at. % Al, 1.6 at. % Zr), were deposited using reactive ion beam sputtering. Magnetization study reveals that the deposited films exhibit a perpendicular magnetic anisotropy. Thermal stability of the films was investigated systematically and it was observed that the structural and the magnetic stability gets significantly enhanced with Al doping, whereas Zr doping has only a marginal effect. Fe self-diffusion, obtained using polarized neutron reflectivity, shows a suppression with both additives. A correlation between the thermal stability and the diffusion process gives a direct evidence that the enhancement in the thermal stability is primarily diffusion controlled. A combined picture of diffusion, structural, and magnetic stability has been drawn to understand the obtained results.

  10. Growth kinetics and characterizations of gallium nitride thin films by remote PECVD

    Science.gov (United States)

    Choi, S. W.; Bachmann, K. J.; Lucovsky, G.

    1993-01-01

    Thin films of GaN have been deposited at relatively low growth temperatures by remote plasma-enhanced chemical-vapor deposition (RPECVD), using a plasma excited NH3, and trimethylgallium (TMG), injected downstream from the plasma. The activation energy for GaN growth has been tentatively assigned to the dissociation of NH groups as the primary N-atom precursors in the surface reaction with adsorbed TMG, or TMG fragments. At high He flow rates, an abrupt increase in the growth rate is observed and corresponds to a change in the reaction mechanism attributed to the formation of atomic N. XRD reveals an increased tendency to ordered growth in the (0001) direction with increasing growth temperature, He flow rate, and RF plasma power. IR spectra show the fundamental lattice mode of GaN at 530 cm without evidence for vibrational modes of hydrocarbon groups.

  11. Development and evaluation of gallium nitride-based thin films for x-ray dosimetry.

    Science.gov (United States)

    Hofstetter, Markus; Howgate, John; Sharp, Ian D; Stutzmann, Martin; Thalhammer, Stefan

    2011-06-07

    X-ray radiation plays an important role in medical procedures ranging from diagnostics to therapeutics. Due to the harm such ionizing radiation can cause, it has become common practice to closely monitor the dosages received by patients. To this end, precise online dosimeters have been developed with the dual objectives of monitoring radiation in the region of interest and improving therapeutic methods. In this work, we evaluate GaN thin film high electron mobility heterostructures with sub-mm(2) detection areas as x-ray radiation detectors. Devices were tested using 40-300 kV Bremsstrahlung x-ray sources. We find that the photoconductive device response exhibits a large gain, is almost independent of the angle of irradiation, and is constant to within 2% of the signal throughout this medical diagnostic x-ray range, indicating that these sensors do not require recalibration for geometry or energy. Furthermore, the devices show a high sensitivity to x-ray intensity and can measure in the air kerma rate (free-in-air) range of 1 µGy s(-1) to 10 mGy s(-1) with a signal stability of ±1% and a linear total dose response over time. Medical conditions were simulated by measurements of device responses to irradiation through human torso phantoms. Direct x-ray imaging is demonstrated using the index finger and wrist sections of a human phantom. The results presented here indicate that GaN-based thin film devices exhibit a wide range of properties, which make them promising candidates for dosimetry applications. In addition, with potential detection volumes smaller than 10(-6) cm(3), they are well suited for high-resolution x-ray imaging. Moreover, with additional engineering steps, these devices can be adapted to potentially provide both in vivo biosensing and x-ray dosimetry.

  12. Development and evaluation of gallium nitride-based thin films for x-ray dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, Markus; Thalhammer, Stefan [Helmholtz Zentrum Muenchen, Ingolstaedter Landstrasse 1, 85764 Neuherberg (Germany); Howgate, John; Sharp, Ian D; Stutzmann, Martin, E-mail: stefan.thalhammer@helmholtz-muenchen.de [Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, 85748 Garching (Germany)

    2011-06-07

    X-ray radiation plays an important role in medical procedures ranging from diagnostics to therapeutics. Due to the harm such ionizing radiation can cause, it has become common practice to closely monitor the dosages received by patients. To this end, precise online dosimeters have been developed with the dual objectives of monitoring radiation in the region of interest and improving therapeutic methods. In this work, we evaluate GaN thin film high electron mobility heterostructures with sub-mm{sup 2} detection areas as x-ray radiation detectors. Devices were tested using 40-300 kV Bremsstrahlung x-ray sources. We find that the photoconductive device response exhibits a large gain, is almost independent of the angle of irradiation, and is constant to within 2% of the signal throughout this medical diagnostic x-ray range, indicating that these sensors do not require recalibration for geometry or energy. Furthermore, the devices show a high sensitivity to x-ray intensity and can measure in the air kerma rate (free-in-air) range of 1 {mu}Gy s{sup -1} to 10 mGy s{sup -1} with a signal stability of {+-}1% and a linear total dose response over time. Medical conditions were simulated by measurements of device responses to irradiation through human torso phantoms. Direct x-ray imaging is demonstrated using the index finger and wrist sections of a human phantom. The results presented here indicate that GaN-based thin film devices exhibit a wide range of properties, which make them promising candidates for dosimetry applications. In addition, with potential detection volumes smaller than 10{sup -6} cm{sup 3}, they are well suited for high-resolution x-ray imaging. Moreover, with additional engineering steps, these devices can be adapted to potentially provide both in vivo biosensing and x-ray dosimetry.

  13. Preparation of Poly(p-phenylene sulfi de)/Carbon Composites with Enhanced Thermal Conductivity and Electrical Insulativity via Hybrids of Boron Nitride and Carbon Fillers

    Institute of Scientific and Technical Information of China (English)

    WU Jieli; WANG Jinwen; CHEN Feng

    2015-01-01

    The present work enhanced the thermal conductivity of poly(p-phenylene sulfi de)/expanded graphites and poly(p-phenylene sulfi de)/carbon nanotubes, by incorporating composites with hexagonal boron nitride, which simultaneously succeeded in raising the electrical conductivity of the systems. A two-step mechanical processing method which includes rotating solid-state premixing and inner mixing was adopted to improve dispersion of the hybrids, contributing to the formation of an interspered thermal conductive network. Similar synergic effect in thermal conductivity enhancement was discovered in the hybrid systems regardless of the dimension difference between the two carbonfi llers. Such is postulated to be the one satisfying advantage generated by the afore-mentioned network; the other is the insulativity of the hybrid systems given by the effective blockage of hexagonal boron nitride as an insulating material in our network.

  14. Al capping layers for nondestructive x-ray photoelectron spectroscopy analyses of transition-metal nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Greczynski, Grzegorz, E-mail: grzgr@ifm.liu.se; Hultman, Lars [Thin Film Physics Division, Department of Physics (IFM), Linköping University, SE-581 83 Linköping (Sweden); Petrov, Ivan [Thin Film Physics Division, Department of Physics (IFM), Linköping University, SE-581 83 Linköping, Sweden and Materials Science Department and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States); Greene, J. E. [Thin Film Physics Division, Department of Physics (IFM), Linköping University, SE-581 83 Linköping (Sweden); Materials Science Department and Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801(United States); Department of Physics, University of Illinois, Urbana, Illinois 61801 (United States)

    2015-09-15

    X-ray photoelectron spectroscopy (XPS) compositional analyses of materials that have been air exposed typically require ion etching in order to remove contaminated surface layers. However, the etching step can lead to changes in sample surface and near-surface compositions due to preferential elemental sputter ejection and forward recoil implantation; this is a particular problem for metal/gas compounds and alloys such as nitrides and oxides. Here, the authors use TiN as a model system and compare XPS analysis results from three sets of polycrystalline TiN/Si(001) films deposited by reactive magnetron sputtering in a separate vacuum chamber. The films are either (1) air-exposed for ≤10 min prior to insertion into the ultrahigh-vacuum (UHV) XPS system; (2) air-exposed and subject to ion etching, using different ion energies and beam incidence angles, in the XPS chamber prior to analysis; or (3) Al-capped in-situ in the deposition system prior to air-exposure and loading into the XPS instrument. The authors show that thin, 1.5–6.0 nm, Al capping layers provide effective barriers to oxidation and contamination of TiN surfaces, thus allowing nondestructive acquisition of high-resolution core-level spectra representative of clean samples, and, hence, correct bonding assignments. The Ti 2p and N 1s satellite features, which are sensitive to ion bombardment, exhibit high intensities comparable to those obtained from single-crystal TiN/MgO(001) films grown and analyzed in-situ in a UHV XPS system and there is no indication of Al/TiN interfacial reactions. XPS-determined N/Ti concentrations acquired from Al/TiN samples agree very well with Rutherford backscattering and elastic recoil analysis results while ion-etched air-exposed samples exhibit strong N loss due to preferential resputtering. The intensities and shapes of the Ti 2p and N 1s core level signals from Al/TiN/Si(001) samples do not change following long-term (up to 70 days) exposure to ambient conditions

  15. A structural insight into mechanical strength of graphene-like carbon and carbon nitride networks

    Science.gov (United States)

    Rahaman, Obaidur; Mortazavi, Bohayra; Dianat, Arezoo; Cuniberti, Gianaurelio; Rabczuk, Timon

    2017-02-01

    Graphene, one of the strongest materials ever discovered, triggered the exploration of many 2D materials in the last decade. However, the successful synthesis of a stable nanomaterial requires a rudimentary understanding of the relationship between its structure and strength. In the present study, we investigate the mechanical properties of eight different carbon-based 2D nanomaterials by performing extensive density functional theory calculations. The considered structures were just recently either experimentally synthesized or theoretically predicted. The corresponding stress-strain curves and elastic moduli are reported. They can be useful in training force field parameters for large scale simulations. A comparative analysis of these results revealed a direct relationship between atomic density per area and elastic modulus. Furthermore, for the networks that have an armchair and a zigzag orientation, we observed that they were more stretchable in the zigzag direction than the armchair direction. A critical analysis of the angular distributions and radial distribution functions suggested that it could be due to the higher ability of the networks to suppress the elongations of the bonds in the zigzag direction by deforming the bond angles. The structural interpretations provided in this work not only improve the general understanding of a 2D material’s strength but also enables us to rationally design them for higher qualities.

  16. Extreme strain rate and temperature dependence of the mechanical properties of nano silicon nitride thin layers in a basal plane under tension: a molecular dynamics study.

    Science.gov (United States)

    Lu, Xuefeng; Wang, Hongjie; Wei, Yin; Wen, Jiangbo; Niu, Min; Jia, Shuhai

    2014-08-01

    Molecular dynamics simulations are performed to clarify the extreme strain rate and temperature dependence of the mechanical behaviors of nano silicon nitride thin layers in a basal plane under tension. It is found that fracture stresses show almost no change with increasing strain rate. However, fracture strains decrease gradually due to the appearance of additional N(2c)-Si bond breaking defects in the deformation process. With increasing loading temperature, there is a noticeable drop in fracture stress and fracture strain. In the low temperature range, roughness phases can be observed owing to a combination of factors such as configuration evolution and energy change.

  17. Carbon Nanotube Thin Film Transistors for Flat Panel Display Application.

    Science.gov (United States)

    Liang, Xuelei; Xia, Jiye; Dong, Guodong; Tian, Boyuan; Peng, Lianmao

    2016-12-01

    Carbon nanotubes (CNTs) are promising materials for both high performance transistors for high speed computing and thin film transistors for macroelectronics, which can provide more functions at low cost. Among macroelectronics applications, carbon nanotube thin film transistors (CNT-TFT) are expected to be used soon for backplanes in flat panel displays (FPDs) due to their superior performance. In this paper, we review the challenges of CNT-TFT technology for FPD applications. The device performance of state-of-the-art CNT-TFTs are compared with the requirements of TFTs for FPDs. Compatibility of the fabrication processes of CNT-TFTs and current TFT technologies are critically examined. Though CNT-TFT technology is not yet ready for backplane production line of FPDs, the challenges can be overcome by close collaboration between research institutes and FPD manufacturers in the short term.

  18. Silver quantum cluster (ag9 )-grafted graphitic carbon nitride nanosheets for photocatalytic hydrogen generation and dye degradation.

    Science.gov (United States)

    Sridharan, Kishore; Jang, Eunyong; Park, Jung Hyun; Kim, Jong-Ho; Lee, Jung-Ho; Park, Tae Joo

    2015-06-15

    We report the visible-light photocatalytic properties of a composite system consisting of silver quantum clusters [Ag9 (H2 MSA)7 ] (H2 MSA=mercaptosuccinic acid) embedded on graphitic carbon nitride nanosheets (AgQCs-GCN). The composites were prepared through a simple chemical route; their structural, chemical, morphological, and optical properties were characterized by using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, transmission electron microscopy, UV/Vis diffuse reflectance spectroscopy, and photoluminescence spectroscopy. Embedment of [Ag9 (H2 MSA)7 ] on graphitic carbon nitride nanosheets (GCN) resulted in extended visible-light absorption through multiple single-electron transitions in Ag quantum clusters and an effective electronic structure for hydroxyl radical generation, which enabled increased activity in the photocatalytic degradation of methylene blue and methyl orange dye molecules compared with pristine GCN and silver nanoparticle-grafted GCN (AgNPs-GCN). Similarly, the amount of hydrogen generated by using AgQCs-GCN was 1.7 times higher than pristine GCN. However, the rate of hydrogen generated using AgQCs-GCN was slightly less than that of AgNPs-GCN because of surface hydroxyl radical formation. The plausible photocatalytic processes are discussed in detail.

  19. Improved tensile and buckling behavior of defected carbon nanotubes utilizing boron nitride coating - A molecular dynamic study

    Science.gov (United States)

    Badjian, H.; Setoodeh, A. R.

    2017-02-01

    Synthesizing inorganic nanostructures such as boron nitride nanotubes (BNNTs) have led to immense studies due to their many interesting functional features such as piezoelectricity, high temperature resistance to oxygen, electrical insulation, high thermal conductivity and very long lengths as physical features. In order to utilize the superior properties of pristine and defected carbon nanotubes (CNTs), a hybrid nanotube is proposed in this study by forming BNNTs surface coating on the CNTs. The benefits of such coating on the tensile and buckling behavior of single-walled CNTs (SWCNTs) are illustrated through molecular dynamics (MD) simulations of the resulted nanostructures during the deformation. The AIREBO and Tersoff-Brenner potentials are employed to model the interatomic forces between the carbon and boron nitride atoms, respectively. The effects of chiral indices, aspect ratio, presence of mono-vacancy defects and coating dimension on coated/non-coated CNTs are examined. It is demonstrated that the coated defective CNTs exhibit remarkably enhanced ultimate strength, buckling load capacity and Young's modulus. The proposed coating not only enhances the mechanical properties of the resulted nanostructure, but also conceals it from few external factors impacting the behavior of the CNT such as humidity and high temperature.

  20. Direct electrochemistry of cytochrome c immobilized on titanium nitride/multi-walled carbon nanotube composite for amperometric nitrite biosensor.

    Science.gov (United States)

    Haldorai, Yuvaraj; Hwang, Seung-Kyu; Gopalan, Anantha-Iyengar; Huh, Yun Suk; Han, Young-Kyu; Voit, Walter; Sai-Anand, Gopalan; Lee, Kwang-Pill

    2016-05-15

    In this report, titanium nitride (TiN) nanoparticles decorated multi-walled carbon nanotube (MWCNTs) nanocomposite is fabricated via a two-step process. These two steps involve the decoration of titanium dioxide nanoparticles onto the MWCNTs surface and a subsequent thermal nitridation. Transmission electron microscopy shows that TiN nanoparticles with a mean diameter of ≤ 20 nm are homogeneously dispersed onto the MWCNTs surface. Direct electrochemistry and electrocatalysis of cytochrome c immobilized on the MWCNTs-TiN composite modified on a glassy carbon electrode for nitrite sensing are investigated. Under optimum conditions, the current response is linear to its concentration from 1 µM to 2000 µM with a sensitivity of 121.5 µA µM(-1)cm(-2) and a low detection limit of 0.0014 µM. The proposed electrode shows good reproducibility and long-term stability. The applicability of the as-prepared biosensor is validated by the successful detection of nitrite in tap and sea water samples.

  1. Designing nanoscale constructs from atomic thin sheets of graphene, boron nitride and gold nanoparticles for advanced material applications

    Science.gov (United States)

    Jasuja, Kabeer

    2011-12-01

    Nanoscale materials invite immense interest from diverse scientific disciplines as these provide access to precisely understand the physical world at their most fundamental atomic level. In concert with this aim of enhancing our understanding of the fundamental behavior at nanoscale, this dissertation presents research on three nanomaterials: Gold nanoparticles (GNPs), Graphene and ultra-thin Boron Nitride sheets (UTBNSs). The three-fold goals which drive this research are: incorporating mobility in nanoparticle based single-electron junction constructs, developing effective strategies to functionalize graphene with nano-forms of metal, and exfoliating ultrathin sheets of Boron Nitride. Gold nanoparticle based electronic constructs can achieve a new degree of operational freedom if nanoscale mobility is incorporated in their design. We achieved such a nano-electromechanical construct by incorporating elastic polymer molecules between GNPs to form 2-dimensional (2-D) molecular junctions which show a nanoscale reversible motion on applying macro scale forces. This GNP-polymer assembly works like a molecular spring opening avenues to maneuver nano components and store energy at nano-scale. Graphene is the first isolated nanomaterial that displays single-atom thickness. It exhibits quantum confinement that enables it to possess a unique combination of fascinating electronic, optical, and mechanical properties. Modifying the surface of graphene is extremely significant to enable its incorporation into applications of interest. We demonstrated the ability of chemically modified graphene sheets to act as GNP stabilizing templates in solution, and utilized this to process GNP composites of graphene. We discovered that GNPs synthesized by chemical or microwave reduction stabilize on graphene-oxide sheets to form snow-flake morphologies and bare-surfaces respectively. These hybrid nano constructs were extensively studied to understand the effect and nature of GNPs

  2. Hetero-junctions of Boron Nitride and Carbon Nanotubes: Synthesis and Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Yap, Yoke Khin

    2013-03-14

    Hetero-junctions of boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs) are expected to have appealing new properties that are not available from pure BNNTs and CNTs. Theoretical studies indicate that BNNT/CNT junctions could be multifunctional and applicable as memory, spintronic, electronic, and photonics devices with tunable band structures. This will lead to energy and material efficient multifunctional devices that will be beneficial to the society. However, experimental realization of BNNT/CNT junctions was hindered by the absent of a common growth technique for BNNTs and CNTs. In fact, the synthesis of BNNTs was very challenging and may involve high temperatures (up to 3000 degree Celsius by laser ablation) and explosive chemicals. During the award period, we have successfully developed a simple chemical vapor deposition (CVD) technique to grow BNNTs at 1100-1200 degree Celsius without using dangerous chemicals. A series of common catalyst have then been identified for the synthesis of BNNTs and CNTs. Both of these breakthroughs have led to our preliminary success in growing two types of BNNT/CNT junctions and two additional new nanostructures: 1) branching BNNT/CNT junctions and 2) co-axial BNNT/CNT junctions, 3) quantum dots functionalized BNNTs (QDs-BNNTs), 4) BNNT/graphene junctions. We have started to understand their structural, compositional, and electronic properties. Latest results indicate that the branching BNNT/CNT junctions and QDs-BNNTs are functional as room-temperature tunneling devices. We have submitted the application of a renewal grant to continue the study of these new energy efficient materials. Finally, this project has also strengthened our collaborations with multiple Department of Energy's Nanoscale Science Research Centers (NSRCs), including the Center for Nanophase Materials Sciences (CNMS) at Oak Ridge National Laboratory, and the Center for Integrated Nanotechnologies (CINTs) at Sandia National Laboratories and Los

  3. Dendritic Tip-on Polytriazine-Based Carbon Nitride Photocatalyst with High Hydrogen Evolution Activity

    KAUST Repository

    Bhunia, Manas Kumar

    2015-11-23

    Developing stable, ubiquitous and efficient water-splitting photocatalyst material that has extensive absorption in the visible-light range is desired for a sustainable solar energy-conversion device. We herein report a triazine-based carbon nitride (CN) material with different C/N ratios achieved by varying the monomer composition ratio between melamine (Mel) and 2,4,6-triaminopyrimidine (TAP). The CN material with a different C/N ratio was obtained through a two-step synthesis protocol: starting with the solution state dispersion of the monomers via hydrogen-bonding supramolecular aggregate, followed by a salt-melt high temperature polycondensation. This protocol ensures the production of a highly crystalline polytriazine imide (PTI) structure con-sisting of a copolymerized Mel-TAP network. The observed bandgap narrowing with an increasing TAP/Mel ratio is well simulated by density functional theory (DFT) calculations, revealing a positive shift in the valence band upon substitution of N with CH in the aromatic rings. Increasing the TAP amount could not maintain the crystalline PTI structure, consistent with DFT calculation showing the repulsion associated with additional C-H introduced in the aromatic rings. Due to the high exciton binding energy calculated by DFT for the obtained CN, the cocatalyst must be close to any portion of the material to assist the separation of excit-ed charge carriers for an improved photocatalytic performance. The photocatalytic activity was improved by providing a dendritic tip-on-like shape grown on a porous fibrous silica KCC-1 spheres, and highly dispersed Pt nanoparticles (<5 nm) were photodepos-ited to introduce heterojunction. As a result, the Pt/CN/KCC-1 photocatalyst exhibited an apparent quantum efficiency (AQE) as high as 22.1 ± 3% at 400 nm and the silica was also beneficial for improving photocatalytic stability. The results obtained by time-resolved transient absorption spectroscopy measurements were consistent with

  4. carbon Nitride Compounds Synthesized by Thermal Annealing Amorphous Nanostructured Graphite under the Flow of NH3 Gas

    Institute of Scientific and Technical Information of China (English)

    公志光; 李木森

    2003-01-01

    Graphitic-C3N4 (g-C3N4) and pseudocubic-C3N4 (p-C3N4) have been synthesized by thermally annealing highenergy ball milled amorphous nanostructured graphite powders under NH3 atmosphere. The experimental results by x-ray, transmission-electron microscopy, selected electron area diffraction and parallel electron energy loss spectroscopy indicated that g-C3N4 grew from the milled graphite powders in the presence of NH3 gas at a temperature of 1050 ℃. After treatment at a temperature of 1350 ℃, the pseudocubic-C3N4 phase forms. It was believed that the high-energy ball milling generates nanosized amorphous graphite structures, under subsequent isothermal annealing in a flow of NH3 gas, the carbon nitride compound can easily form through reaction of nanostructured carbon with nitrogen of NH3.

  5. A Fabrication Route for Arrays of Ultra-low-Noise MoAu Transition Edge Sensors on Thin Silicon Nitride for Space Applications

    CERN Document Server

    Glowacka, D M; Goldie, D J; Withington, S

    2014-01-01

    We describe a process route to fabricate arrays of Ultra-low-Noise MoAu Transition Edge Sensors (TESs). The low thermal conductance required for space applications is achieved using 200 nm-thick Silicon Nitride (SiNx ) patterned to form long-thin legs with widths of 2.1 {\\mu}m. Using bilayers formed on SiNx islands from films with 40 nm-thick Mo and Au thicknesses in the range 30 to 280 nm deposited by dc-sputtering in ultra-high vacuum we can obtain tunable transition temperatures in the range 700 to 70 mK. The sensors use large-area absorbers fabricated from high resistivity, thin-film beta-phase Ta to provide impedance-matching to incident radiation. The absorbers are patterned to reduce the heat capacity associated with the nitride support structure and include Au thermalizing features to assist the heat flow into the TES. Arrays of 400 detectors at the pixel spacing required for the long-wavelength band of the far-infrared instrument SAFARI are now being fabricated. Device yields approaching 99% are achi...

  6. Layer by layer assembly of catalase and amine-terminated ionic liquid onto titanium nitride nanoparticles modified glassy carbon electrode: Study of direct voltammetry and bioelectrocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Saadati, Shagayegh [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Hallaj, Rahman; Rostami, Amin [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2012-11-13

    Highlights: Black-Right-Pointing-Pointer Catalase and amine-terminated ionic liquid were immobilized to GC/TiNnp with LBL assembly method. Black-Right-Pointing-Pointer First a thin layer of NH{sub 2}-IL is covalently attached to GC/TiNnp electrode using electro-oxidation. Black-Right-Pointing-Pointer With alternative assemble of IL and catalase with positive and negative charged, multilayer was formed. Black-Right-Pointing-Pointer Immobilized catalase shows excellent electrocatalytic activity toward H{sub 2}O{sub 2} reduction. Black-Right-Pointing-Pointer Biosensor response is directly correlated to the number of bilayers. - Abstract: A novel, simple and facile layer by layer (LBL) approach is used for modification of glassy carbon (GC) electrode with multilayer of catalase and nanocomposite containing 1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid (NH{sub 2}-IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of NH{sub 2}-IL is covalently attached to GC/TiNnp electrode using electro-oxidation method. Then, with alternative self assemble positively charged NH{sub 2}-IL and negatively charged catalase a sensitive H{sub 2}O{sub 2} biosensor is constructed, whose response is directly correlated to the number of bilayers. The surface coverage of active catalase per bilayer, heterogeneous electron transfer rate constant (k{sub s}) and Michaelis-Menten constant (K{sub M}) of immobilized catalase were 3.32 Multiplication-Sign 10{sup -12} mol cm{sup -2}, 5.28 s{sup -1} and 1.1 mM, respectively. The biosensor shows good stability, high reproducibility, long life-time, and fast amperometric response with the high sensitivity of 380 {mu}A mM{sup -1} cm{sup -2} and low detection limit of 100 nM at concentration range up to 2.1 mM.

  7. Synthesis and Characterization of Magnetite/Carbon Nanocomposite Thin Films for Electrochemical Applications

    Institute of Scientific and Technical Information of China (English)

    Suh Cem Pang; Wai Hwa Khoh; Suk Fun Chin

    2011-01-01

    Stable colloidal suspension of magnetite/starch nanocomposite was prepared by a facile and aqueous-based chemical precipitation method, Magnetite/carbon nanocomposite thin films were subsequently formed upon carbonization of the starch component by heat treatment under controlled conditions. The initial content of native sago starch as the carbon source was found to affect the microstructure and electrochemical properties of the resulted magnetite/carbon nanocomposite thin films, A specific capacitance of 124 F/g was achieved for the magnetite/carbon nanocomposite thin films as compared to that of 82 F/g for pure magnetite thin films in Na2SO4 aqueous electrolyte.

  8. Printable thin film supercapacitors using single-walled carbon nanotubes.

    Science.gov (United States)

    Kaempgen, Martti; Chan, Candace K; Ma, J; Cui, Yi; Gruner, George

    2009-05-01

    Thin film supercapacitors were fabricated using printable materials to make flexible devices on plastic. The active electrodes were made from sprayed networks of single-walled carbon nanotubes (SWCNTs) serving as both electrodes and charge collectors. Using a printable aqueous gel electrolyte as well as an organic liquid electrolyte, the performances of the devices show very high energy and power densities (6 W h/kg for both electrolytes and 23 and 70 kW/kg for aqueous gel electrolyte and organic electrolyte, respectively) which is comparable to performance in other SWCNT-based supercapacitor devices fabricated using different methods. The results underline the potential of printable thin film supercapacitors. The simplified architecture and the sole use of printable materials may lead to a new class of entirely printable charge storage devices allowing for full integration with the emerging field of printed electronics.

  9. Printable Thin Film Supercapacitors Using Single-Walled Carbon Nanotubes

    KAUST Repository

    Kaempgen, Martti

    2009-05-13

    Thin film supercapacitors were fabricated using printable materials to make flexible devices on plastic. The active electrodes were made from sprayed networks of single-walled carbon nanotubes (SWCNTs) serving as both electrodes and charge collectors. Using a printable aqueous gel electrolyte as well as an organic liquid electrolyte, the performances of the devices show very high energy and power densities (6 W h/kg for both electrolytes and 23 and 70 kW/kg for aqueous gel electrolyte and organic electrolyte, respectively) which is comparable to performance in other SWCNT-based supercapacitor devices fabricated using different methods. The results underline the potential of printable thin film supercapacitors. The simplified architecture and the sole use of printable materials may lead to a new class of entirely printable charge storage devices allowing for full integration with the emerging field of printed electronics. © 2009 American Chemical Society.

  10. Tribological behaviors of diamond-like carbon coatings on plasma nitrided steel using three BN-containing lubricants

    Energy Technology Data Exchange (ETDEWEB)

    Jia Zhengfeng [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China); College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Graduate School of the Chinese Academy of Sciences, Beijing 10039 (China); Wang Peng [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China); Xia Yanqiu, E-mail: xiayanqiu@yahoo.com [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China); Zhang Haobo; Pang Xianjuan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China); Graduate School of the Chinese Academy of Sciences, Beijing 10039 (China); Li Bin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, 18 Tianshui Middle Road, Lanzhou 73000 (China)

    2009-04-15

    In this work, diamond-like carbon (DLC) coatings were deposited on plasma nitrided AISI 1045 steel by magnetron sputtering. Three BN-containing additives and molybdenum dithiocarbamate (MoDTC) were added to poly-alpha-olefin (PAO) as additives. The additive content (mass fraction) in PAO was fixed at 0.5 wt%. The friction and wear characters of DLC coatings on nitrided steel discs sliding against AISI 52100 steel balls were tested under the lubricated conditions. It was found that borate esters have a higher load carrying capacity and much better anti-wear and friction-reducing ability than that of MoDTC. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were employed to explore the properties of the worn surface and the mechanism of friction and wear. According to the XPS analysis, the adsorbed organic N-containing compounds and BN are, possibly, the primary reason for the novel borate esters to possess a relatively constant coefficient of friction and lower wear rate. On the other hand, possibly, the MoDTC molecules break down during sliding and produce many Mo-oxides, and then the Mo-oxides destroy the DLC coating because of its sharp edge crystalline solid structure. After destroying the DLC coating, the MoDTC react with metals and form MoS{sub 2} tribofilm, and decrease coefficient of friction of rubbing pairs.

  11. Methodical Specifics of Thermal Experiments with Thin Carbon Reinforced Plates

    Directory of Open Access Journals (Sweden)

    O. V. Denisov

    2015-01-01

    Full Text Available Polymer composite materials (CM are widely used in creation of large space constructions, especially reflectors of space antennas. Composite materials should provide high level of specific stiffness and strength for space structures. Thermal conductivity in reinforcement plane is a significant factor in case of irregular heating space antennas. Nowadays, data on CM reinforcement plane thermal conductivity are limited and existing methods of its defining are imperfect. Basically, traditional methods allow us to define thermal conductivity in perpendicular direction towards the reinforcement plane on the samples of round or rectangular plate. In addition, the thickness of standard samples is larger than space antenna thickness. Consequently, new methods are required. Method of contact heating, which was developed by BMSTU specialists with long hollow carbon beam, could be a perspective way. This article is devoted to the experimental method of contact heating on the thin carbon plates.Thermal tests were supposed to provide a non-stationary temperature field with a gradient being co-directional with the plane reinforcement in the material sample. Experiments were conducted in vacuum chamber to prevent unstructured convection. Experimental thermo-grams processing were calculated by 1-d thermal model for a thin plate. Influence of uncertainty of experimental parameters, such as (radiation emission coefficients of sample surface, glue, temperature sensors and uncertainty of sensors placement on the result of defined thermal conductivity has been estimated. New data on the thermal conductivity in reinforcement plane were obtained within 295 - 375 K temperature range, which can be used to design and develop reflectors of precision space antennas. In the future it is expedient to conduct tests of thin-wall plates from carbon fiber-reinforced plastic in wide temperature range, especially in the low-range temperatures.

  12. Impact damage resistance of thin stitched carbon/epoxy laminates

    Science.gov (United States)

    Francesconi, L.; Aymerich, F.

    2015-07-01

    The study examines the influence of through-thickness stitching on the damage response of thin cross-ply carbon/epoxy laminates subjected to low-velocity impacts. Instrumented impact tests were carried out on unstitched and polyethylene stitched laminates and the resulting damage was assessed in detail by X-radiography analyses. The results of the observations carried out during the experimental analyses are illustrated and discussed to identify the mechanical role played by through-thickness reinforcement and to highlight the influence of the laminate layup on the impact resistance of stitched laminates.

  13. Effect of gate-dielectrics on the electrical characteristics of solution-processed single-wall-carbon-nanotube thin-film transistors

    Science.gov (United States)

    Ha, Tae-Jun

    2017-02-01

    High performance of solution-processed, single-wall-carbon-nanotube (SWCNT) thin-film transistors (TFTs) is investigated through the use in the different gate-dielectrics of silicon dioxide (SiO2), silicon nitride (SiNx), the bilayers of SiO2 and SiNx, and hexagonal boron-nitride (h-BN) thin films. The different interfacial characteristics affect the electrical characteristics of the SWCNT-TFTs including key device metrics. Significantly, the hysteresis window that is normally observed in drop-casted SWCNT-TFTs was majorly suppressed by the employment of a thin lower dielectric-constant material on a higher dielectricconstant material. Sub-2V operating SWCNT-TFTs with solution-processed h-BN gate dielectrics with good above- and sub-threshold characteristics are also investigated on the basis of interfacial characteristics underlying the device physics. Such performance can be realized by the suppressed interfacial impurity scattering through the chemically clean interface combined with optimized solution-process below 100 °C. [Figure not available: see fulltext.

  14. Platinum-coordinated graphitic carbon nitride nanosheet used for targeted inhibition of amyloid β-peptide aggregation

    Institute of Scientific and Technical Information of China (English)

    Meng Li; Yijia Guan; Zhaowei Chen; Nan Gao; Jinsong Ren; Kai Dong; Xiaogang Qu

    2016-01-01

    Amyloid β-peptide (Aβ) aggregation is a critical step in the pathogenesis of Alzheimer's disease (AD).Inhibition of Aβ production,dissolution of existing aggregates and clearance of Aβ represent valid therapeutic strategies against AD.Herein,a novel platinum(Ⅱ)-coordinated graphitic carbon nitride (g-C3N4)nanosheet (g-C3N4@Pt) has been designed to covalently bind to Aβ and modulate the peptide's aggregation and toxicity.Furthermore,g-C3N4@Pt nanosheets possess high photocatalytic activity and can oxygenate Aβ upon visible light irradiation,remarkably attenuating both the aggregation potency and neurotoxidty of Aβ.Due to its ability to cross the blood-brain barrier (BBB) and its good biocompatibility,g-C3N4@Pt nanosheet is a promising inhibitor of Aβ aggregation.This study may serve as a model for the engineering of novel multifunctional nanomaterials used for the treatment of AD.

  15. Porous graphitic carbon nitride synthesized via direct polymerization of urea for efficient sunlight-driven photocatalytic hydrogen production.

    Science.gov (United States)

    Zhang, Yuewei; Liu, Jinghai; Wu, Guan; Chen, Wei

    2012-09-07

    Energy captured directly from sunlight provides an attractive approach towards fulfilling the need for green energy resources on the terawatt scale with minimal environmental impact. Collecting and storing solar energy into fuel through photocatalyzed water splitting to generate hydrogen in a cost-effective way is desirable. To achieve this goal, low cost and environmentally benign urea was used to synthesize the metal-free photocatalyst graphitic carbon nitride (g-C₃N₄). A porous structure is achieved via one-step polymerization of the single precursor. The porous structure with increased BET surface area and pore volume shows a much higher hydrogen production rate under simulated sunlight irradiation than thiourea-derived and dicyanamide-derived g-C₃N₄. The presence of an oxygen atom is presumed to play a key role in adjusting the textural properties. Further improvement of the photocatalytic function can be expected with after-treatment due to its rich chemistry in functionalization.

  16. Photosensitization of Carbon Nitride Photoelectrodes with CdS: A Novel Architecture with Highly Efficient Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Xiaosong Zhou

    2014-01-01

    Full Text Available CdS with well-defined crystallinity is anchored on carbon nitride photoelectrodes by a successive chemical bath deposition. And the as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy techniques. The effect of the amount of CdS on the catalytic activity for the degradation of acid Orange II is investigated under visible light irradiation. Results show that the photoelectrodes composed of CdS/CN exhibit much higher catalytic activity than pure CN photoelectrodes. A possible photocatalytic mechanism of the CdS/CN electrodes is proposed under visible light irradiation.

  17. The function-led design of Z-scheme photocatalytic systems based on hollow carbon nitride semiconductors.

    Science.gov (United States)

    Zheng, Dandan; Pang, Chenyang; Wang, Xinchen

    2015-12-21

    A ternary photocatalyst has been successfully constructed through the integration of Au, CdS and hollow carbon nitride nanospheres (HCNS), where Au nanoparticles were designed to shuttle interparticle transfer of charge carriers between CdS and HCNS photosensitizers to establish two-photon (Z-scheme) photocatalytic tandem systems for solar fuel production. The solid-state CdS-Au-HCNS Z-scheme nanocomposites were efficient for H2 evolution (with a quantum yield of 8.7% at 420 nm) and CO2 reduction catalysis with visible light irradiation. This work further proves the feasibility of employing hollow conjugated polymer photocatalysts in the function-led design of artificial Z-type photosynthetic machinery on soft material interfaces.

  18. Dispersed conductive polymer nanoparticles on graphitic carbon nitride for enhanced solar-driven hydrogen evolution from pure water.

    Science.gov (United States)

    Sui, Yi; Liu, Jinghai; Zhang, Yuewei; Tian, Xike; Chen, Wei

    2013-10-07

    Developing new methods to improve the photocatalytic activity of graphitic carbon nitride (g-C₃N₄) for hydrogen (H₂) evolution has attracted intensive research interests. Here, we report that the g-C₃N₄ exhibits photocatalytic activity for H₂ evolution from pure water. And, the activity is dramatically improved by loading highly dispersed conductive polymer nanoparticles. The H₂ evolution rate increases up to 50 times for g-C₃N₄ with 1.5 wt% polypyrrole (PPy) nanoparticles on the surface. The reaction proceeding in a pure water system excludes the need for sacrificial agents. The role of the highly conductive PPy in enhancing H₂ evolution is as a surface junction to increase the number of photoinduced electrons, and to facilitate electron transfer to the interface.

  19. DFT Study on Structural and Mechanical Properties of Single-walled Carbon and Boron Nitride Nanotubes Functionalized with Carbenes

    Directory of Open Access Journals (Sweden)

    I.K. Petrushenko

    2016-10-01

    Full Text Available This paper presents quantum chemistry study on structural and mechanical properties of a series of single-walled carbon nanotubes (SWCNTs and boron nitride nanotubes (BNNTs functionalized with carbenes. At the PBE/SVP level, the obtained data on pristine nanotubes are in good accordance with the results of previous experimental and theoretical studies. The calculations show that carbenes functionalization, in general, distorts both SWNCTs and BNNTs frameworks, but there exists the difference between ‘axial’ and ‘circumferential’ functionalization. It turns out that in both cases elastic properties diminish with increasing concentration of adsorbents, however, the functionalized SWCNTs and BNNTs remain strong enough to be suitable for reinforcement of composites.

  20. Influence of Nitrided Layer on The Properties of Carbon Coatings Produced on X105CrMo17 Steel Under DC Glow-Discharge Conditions

    Directory of Open Access Journals (Sweden)

    Tomasz BOROWSKI

    2016-09-01

    Full Text Available In most cases, machine components, which come in contact with each other, are made of steel. Common steel types include 100Cr6 and X105CrMo17 are widely used in rolling bearings, which are subjected to high static loads. However, more and more sophisticated structural applications require increasingly better performance from steel. The most popular methods for improving the properties of steel is carburisation or nitriding. Unfortunately, when very high surface properties of steel are required, this treatment may be insufficient. Improvement of tribological properties can be achieved by increasing the hardness of the surface, reducing roughness or reducing the coefficient of friction. The formation of composite layers on steel, consisting of a hard nitride diffusion layer and an external carbon coating with a low coefficient of friction, seems to be a prospect with significant potential. The article describes composite layers produced on X105CrMo17 steel and defines their morphology, surface roughness and their functional properties such as: resistance to friction-induced wear, coefficient of friction and corrosion resistance. The layers have been formed at a temperature of 370°C in successive processes of: nitriding in low-temperature plasma followed by deposition of a carbon coating under DC glow-discharge conditions. An evaluation was also made of the impact of the nitrided layers on the properties and morphology of the carbon coatings formed by comparing them to coatings formed on non-nitrided X105CrMo17 steel substrates. A study of the surface topography, adhesion, resistance to friction-induced wear and corrosion shows the significant importance of the substrate type the carbon coatings are formed on.DOI: http://dx.doi.org/10.5755/j01.ms.22.3.7532

  1. Construction of carbon quantum dots/proton-functionalized graphitic carbon nitride nanocomposite via electrostatic self-assembly strategy and its application

    Energy Technology Data Exchange (ETDEWEB)

    Jian, Xuan; Liu, Xian; Yang, Hui-min; Li, Jia-gang; Song, Xiu-li; Dai, Hong-yan; Liang, Zhen-hai, E-mail: liangzhenh@sina.com

    2016-05-01

    Highlights: • An electrostatic self-assembly strategy was proposed to prepare CQDs/HpCN nanocomposite. • Carbon quantum dots (CQDs) attached onto surface of proton-functionalized graphitic carbon nitride (HpCN) through electrostatic attraction. • The CQDs/HpCN nanocomposite exhibited excellent photocatalytic and photoelectrochemical properties. - Abstract: Carbon quantum dots (CQDs) and graphitic carbon nitride (g-C{sub 3}N{sub 4}), as advanced metal-free material catalysts have been the focus of considerable attention because of their superior photocatalytic activities. In this study, we developed a novel approach to obtain CQDs/g-C{sub 3}N{sub 4} nanocomposite with effective interfacial contact by incorporating negatively charged CQDs and tailor-made proton-functionalized g-C{sub 3}N{sub 4}via the electrostatic self-assembly strategy. Then, the morphology and microstructure of the new nanocomposite were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The CQDs and proton-functionalized g-C{sub 3}N{sub 4} nanocomposite exhibited excellent electron transfer properties though electrochemical impedance spectroscopy (EIS), significantly enhanced photoactivity in the photoelectrochemical i–t curve test and degradation of methylene blue solution under visible light irradiation. These results demonstrated that the electrostatic self-assembly strategy process is a promising method of fabricating uniform metal-free material catalysts for an extensive range of applications.

  2. Surface wet-ability modification of thin PECVD silicon nitride layers by 40 keV argon ion treatments

    Science.gov (United States)

    Caridi, F.; Picciotto, A.; Vanzetti, L.; Iacob, E.; Scolaro, C.

    2015-10-01

    Measurements of wet-ability of liquid drops have been performed on a 30 nm silicon nitride (Si3N4) film deposited by a PECVD reactor on a silicon wafer and implanted by 40 keV argon ions at different doses. Surface treatments by using Ar ion beams have been employed to modify the wet-ability. The chemical composition of the first Si3N4 monolayer was investigated by means of X-ray Photoelectron Spectroscopy (XPS). The surface morphology was tested by Atomic Force Microscopy (AFM). Results put in evidence the best implantation conditions for silicon nitride to increase or to reduce the wet-ability of the biological liquid. This permits to improve the biocompatibility and functionality of Si3N4. In particular experimental results show that argon ion bombardment increases the contact angle, enhances the oxygen content and increases the surface roughness.

  3. Plasma assisted metal-organic chemical vapor deposition of hard chromium nitride thin film coatings using chromium(III) acetylacetonate as the precursor

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, Arup; Kuppusami, P.; Lawrence, Falix; Raghunathan, V.S.; Antony Premkumar, P.; Nagaraja, K.S

    2004-06-15

    A new technique has been developed for depositing hard nanocrystalline chromium nitride (CrN) thin films on metallic and ceramic substrates using plasma assisted metal-organic chemical vapor deposition (PAMOCVD) technique. In this low temperature and environment-friendly process, a volatile mixture of chromium(III) acetylacetonate and either ammonium iodide or ammonium bifluoride were used as precursors. Nitrogen and hydrogen have been used as the gas precursors. By optimizing the processing conditions, a maximum deposition rate of {approx}0.9 {mu}m/h was obtained. A comprehensive characterization of the CrN films was carried out using X-ray diffraction (XRD), microhardness, and microscopy. The microstructure of the CrN films deposited on well-polished stainless steel (SS) showed globular particles, while a relatively smooth surface morphology was observed for coatings deposited on polished yittria-stabilized zirconia (YSZ)

  4. Ultrasonic Fatigue Endurance of Thin Carbon Fiber Sheets

    Science.gov (United States)

    Domínguez Almaraz, Gonzalo M.; Ruiz Vilchez, Julio A.; Dominguez, Aymeric; Meyer, Yann

    2016-04-01

    Ultrasonic fatigue tests were carried out on thin carbon fiber sheets (0.3 mm of thickness) to determine the fatigue endurance under very high-frequency loading (20 kHz). This material, called the gas diffusion layer (GDL), plays a major role in the overall performances of proton exchange membrane fuel cells (PEMFCs). The study of its physical-chemical properties is an on-going subject in the literature; nevertheless, no knowledge is available concerning the high-frequency fatigue endurance. A principal difficulty in carrying out ultrasonic fatigue tests on this material was to determine the dimensions of testing specimen to fit the resonance condition. This aspect was solved by modal numerical simulation: The testing specimen has been a combination of a low-strength steel frame (to facilitate the attachment to the ultrasonic machine and to increase the mass of the specimen), and the carbon fiber hourglass-shape profile. Under resonance condition, a stationary elastic wave is generated along the specimen that induces high stress at the neck section and high displacements at the ends. Results show that fatigue life was close to 3 × 108 cycles when the high Von Misses stress at the neck section was 170 MPa, whereas fatigue life attains the 4.5 × 109 cycles when stress decreases to 117 MPa. Crack initiation and propagation were analyzed, and conclusions were drawn concerning the fatigue endurance of these fiber carbon sheets under ultrasonic fatigue testing.

  5. Single-step synthesis of crystalline h-BN quantum- and nanodots embedded in boron carbon nitride films

    Science.gov (United States)

    Matsoso, Boitumelo J.; Ranganathan, Kamalakannan; Mutuma, Bridget K.; Lerotholi, Tsenolo; Jones, Glenn; Coville, Neil J.

    2017-03-01

    Herein we report on the synthesis and characterization of novel crystalline hexagonal boron nitride (h-BN) quantum- and nanodots embedded in large-area boron carbon nitride (BCN) films. The films were grown on a Cu substrate by an atmospheric pressure chemical vapour deposition technique. Methane, ammonia, and boric acid were used as precursors for C, N and B to grow these few atomic layer thick uniform films. We observed that both the size of the h-BN quantum/nanodots and thickness of the BCN films were influenced by the vaporization temperature of boric acid as well as the H3BO3 (g) flux over the Cu substrate. These growth conditions were easily achieved by changing the position of the solid boric acid in the reactor with respect to the Cu substrate. Atomic force microscope (AFM) and TEM analyses show a variation in the h-BN dot size distribution, ranging from nanodots (∼224 nm) to quantum dots (∼11 nm) as the B-source is placed further away from the Cu foil. The distance between the B-source and the Cu foil gave an increase in the C atomic composition (42 at% C–65 at% C) and a decrease in both B and N contents (18 at% B and 14 at% N to 8 at% B and 7 at% N). UV–vis absorption spectra showed a higher band gap energy for the quantum dots (5.90 eV) in comparison with the nanodots (5.68 eV) due to a quantum confinement effect. The results indicated that the position of the B-source and its reaction with ammonia plays a significant role in controlling the nucleation of the h-BN quantum- and nanodots. The films are proposed to be used in solar cells. A mechanism to explain the growth of h-BN quantum/nanodots in BCN films is reported.

  6. Investigating the Dispersion Behavior in Solvents, Biocompatibility, and Use as Support for Highly Efficient Metal Catalysts of Exfoliated Graphitic Carbon Nitride.

    Science.gov (United States)

    Ayán-Varela, M; Villar-Rodil, S; Paredes, J I; Munuera, J M; Pagán, A; Lozano-Pérez, A A; Cenis, J L; Martínez-Alonso, A; Tascón, J M D

    2015-11-04

    The liquid-phase exfoliation of graphitic carbon nitride (g-C3N4) to afford colloidal dispersions of two-dimensional flakes constitutes an attractive route to facilitate the processing and implementation of this novel material toward different technological applications, but quantitative knowledge about its dispersibility in solvents is lacking. Here, we investigate the dispersion behavior of exfoliated g-C3N4 in a wide range of solvents and evaluate the obtained results on the basis of solvent surface energy and Hildebrand/Hansen solubility parameters. Estimates of the three Hansen parameters for exfoliated g-C3N4 from the experimentally derived data yielded δD ≈ 17.8 MPa(1/2), δP ≈ 10.8 MPa(1/2), and δH ≈ 15.4 MPa(1/2). The relatively high δH value suggested that, contrary to the case of other two-dimensional materials (e.g., graphene or transition metal dichalcogenides), hydrogen-bonding plays a substantial role in the efficient interaction, and thus dispersibility, of exfoliated g-C3N4 with solvents. Such an outcome was attributed to a high density of primary and/or secondary amines in the material, the presence of which was associated with incomplete condensation of the structure. Furthermore, cell proliferation tests carried out on thin films of exfoliated g-C3N4 using murine fibroblasts suggested that this material is highly biocompatible and noncytotoxic. Finally, the exfoliated g-C3N4 flakes were used as supports in the synthesis of Pd nanoparticles, and the resulting hybrids exhibited an exceptional catalytic activity in the reduction of nitroarenes.

  7. Generation of mirage effect by heated carbon nanotube thin film

    Energy Technology Data Exchange (ETDEWEB)

    Tong, L. H. [Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230026 (China); USTC-CityU Joint Advanced Research Centre, Suzhou, Jiangsu 215123 (China); Lim, C. W., E-mail: bccwlim@cityu.edu.hk [USTC-CityU Joint Advanced Research Centre, Suzhou, Jiangsu 215123 (China); Department of Civil and Architectural Engineering, City University of Hong Kong, Kowloon, Hong Kong, People’s Republic of China and City University of Hong Kong Shenzhen Research Institute, Shenzhen 518057 (China); Li, Y. C. [Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Chuanzeng; Quoc Bui, Tinh [Department of Civil Engineering, University of Siegen, Paul-Bonatz-Str. 9-11, D-57076 Siegen (Germany)

    2014-06-28

    Mirage effect, a common phenomenon in nature, is a naturally occurring optical phenomenon in which lights are bent due to the gradient variation of refraction in the temperature gradient medium. The theoretical analysis of mirage effect generated by heated carbon nanotube thin film is presented both for gas and liquid. Excellent agreement is demonstrated through comparing the theoretical prediction with published experimental results. It is concluded from the theoretical prediction and experimental observation that the mirage effect is more likely to happen in liquid. The phase of deflected optical beam is also discussed and the method for measurement of thermal diffusivity of medium is theoretically verified. Furthermore, a method for measuring the refractive index of gas by detecting optical beam deflection is also presented in this paper.

  8. Ultrathin graphitic carbon nitride nanosheets: a low-cost, green, and highly efficient electrocatalyst toward the reduction of hydrogen peroxide and its glucose biosensing application

    Science.gov (United States)

    Tian, Jingqi; Liu, Qian; Ge, Chenjiao; Xing, Zhicai; Asiri, Abdullah M.; Al-Youbi, Abdulrahman O.; Sun, Xuping

    2013-09-01

    In this communication, we demonstrate for the first time that ultrathin graphitic carbon nitride (g-C3N4) nanosheets can serve as a low-cost, green, and highly efficient electrocatalyst toward the reduction of hydrogen peroxide. We further demonstrate its application for electrochemical glucose biosensing in both buffer solution and human serum medium with a detection limit of 11 μM and 45 μM, respectively.In this communication, we demonstrate for the first time that ultrathin graphitic carbon nitride (g-C3N4) nanosheets can serve as a low-cost, green, and highly efficient electrocatalyst toward the reduction of hydrogen peroxide. We further demonstrate its application for electrochemical glucose biosensing in both buffer solution and human serum medium with a detection limit of 11 μM and 45 μM, respectively. Electronic supplementary information (ESI) available: Experimental section and supplementary figures. See DOI: 10.1039/c3nr02031b

  9. Metal-Free Oxidation of α-Hydroxy Ketones to 1,2-Diketones Catalyzed by Mesoporous Carbon Nitride with Visible Light

    Institute of Scientific and Technical Information of China (English)

    郑志硕; 周小松

    2012-01-01

    As a photocatalyst, mesoporous carbon nitride (mpg-C3N4) shows higher photocatalytic activities in organic synthesis. Herein we report an mpg-C3N4-catalyzed oxidation of α-hydroxy ketones to synthesize 1,2-diketones using visible light. This transformation represents a green and highly efficient synthetic route to synthesize 1,2-diketones for which catalytic approaches are scarce.

  10. Porous, single crystalline titanium nitride nanoplates grown on carbon fibers: excellent counter electrodes for low-cost, high performance, fiber-shaped dye-sensitized solar cells.

    Science.gov (United States)

    Chen, Liang; Dai, Hui; Zhou, Yong; Hu, Yingjie; Yu, Tao; Liu, Jianguo; Zou, Zhigang

    2014-11-28

    An excellent, platinum free fiber counter electrode (CE) was successfully fabricated, consisting of porous, single crystalline titanium nitride (TiN) nanoplates grown on carbon fibers (CF). The fiber-shaped dye-sensitized solar cells (FDSSCs) based on the TiN-CF CE show a high conversion efficiency of 7.20%, comparable or even superior to that of the Pt wire (6.23%).

  11. Carbon and water fluxes from ponderosa pine forests disturbed by wildfire and thinning.

    Science.gov (United States)

    Dore, S; Kolb, T E; Montes-Helu, M; Eckert, S E; Sullivan, B W; Hungate, B A; Kaye, J P; Hart, S C; Koch, G W; Finkral, A

    2010-04-01

    Disturbances alter ecosystem carbon dynamics, often by reducing carbon uptake and stocks. We compared the impact of two types of disturbances that represent the most likely future conditions of currently dense ponderosa pine forests of the southwestern United States: (1) high-intensity fire and (2) thinning, designed to reduce fire intensity. High-severity fire had a larger impact on ecosystem carbon uptake and storage than thinning. Total ecosystem carbon was 42% lower at the intensely burned site, 10 years after burning, than at the undisturbed site. Eddy covariance measurements over two years showed that the burned site was a net annual source of carbon to the atmosphere whereas the undisturbed site was a sink. Net primary production (NPP), evapotranspiration (ET), and water use efficiency were lower at the burned site than at the undisturbed site. In contrast, thinning decreased total ecosystem carbon by 18%, and changed the site from a carbon sink to a source in the first posttreatment year. Thinning also decreased ET, reduced the limitation of drought on carbon uptake during summer, and did not change water use efficiency. Both disturbances reduced ecosystem carbon uptake by decreasing gross primary production (55% by burning, 30% by thinning) more than total ecosystem respiration (TER; 33-47% by burning, 18% by thinning), and increased the contribution of soil carbon dioxide efflux to TER. The relationship between TER and temperature was not affected by either disturbance. Efforts to accurately estimate regional carbon budgets should consider impacts on carbon dynamics of both large disturbances, such as high-intensity fire, and the partial disturbance of thinning that is often used to prevent intense burning. Our results show that thinned forests of ponderosa pine in the southwestern United States are a desirable alternative to intensively burned forests to maintain carbon stocks and primary production.

  12. GROWTH, MORPHOLOGICAL, STRUCTURAL, ELECTRICAL AND OPTICAL PROPERTIES OF NITROGEN DOPED ZINC OXIDE THIN FILM ON POROUS GALLIUM NITRIDE TEMPLATE

    OpenAIRE

    2016-01-01

    Gallium nitride (GaN) is susceptible of producing efficient display and lighting devices.  Low cost hybrid heterostructured lighting devices are developed by combining zinc oxide (ZnO) with GaN that has gained much more research interest, nowadays.  Porous GaN receives a great deal of attraction by its excellent and improved properties compared with its bulk counterpart.  Several potential applications have been realized, including for serving as a strain-relaxed substrates for...

  13. Theoretical study of interaction between Tacrine and finite-length Al-doped Carbon and Boron nitride Nanotubes: A Semiempirical drug delivery study in thermodynamic view

    Directory of Open Access Journals (Sweden)

    Nasrin Zeighami

    2014-12-01

    Full Text Available In order to extend our previous theoretical calculations that dealt with the thermochemistry of doping the single walled boron nitride nano tubes, BNNTs, and carbon nanotubes ,CNTs, with alminium atoms [1], we have used the AM 1, PM 3, and PM 6 semiempirical methods to investigate the interaction of the tacrine molecule (a drug for the treatment of Alzheimer's disease with the side-walls of aluminum doped boron nitride and carbon nano tubes in thermodynamic views.At first, the frequency calculations were carried out to confirm the stability of the involved structures. In addition, the theoretical thermodynamic study of tacrine adsorption onto the considered nanotubes was performed and the thermodynamic functions such as enthalpy changes, entropy changes and Gibbs free energy changes of the adsorption process were evaluated at different temperatures. Our results suggest the aluminum doped boron nitride nano tubes and alminium doped carbon nano tubes may be considered as the proper carries for the drug delivery of tacrine.

  14. A graphitic hollow carbon nitride nanosphere as a novel photochemical internalization agent for targeted and stimuli-responsive cancer therapy

    Science.gov (United States)

    Liu, Chaoqun; Chen, Zhaowei; Wang, Zhenzhen; Li, Wei; Ju, Enguo; Yan, Zhengqing; Liu, Zhen; Ren, Jinsong; Qu, Xiaogang

    2016-06-01

    As a novel technique, photochemical internalization (PCI) has been employed as a new approach to overcome endo/lysosomal restriction, which is one of the main difficulties in both drug and gene delivery. However, the complicated synthesis procedure (usually requiring the self-assembly of polymers, photosensitizers and cargos) and payload specificity greatly limit its further application. In this paper, we employ a highly fluorescent graphitic hollow carbon nitride nanosphere (GHCNS) to simultaneously serve as a PCI photosensitizer, an imaging agent and a drug carrier. The surface modification of GHCNS with multifunctional polysaccharide hyaluronic acid (HA) endows the system with colloidal stability, biocompatibility and cancer cell targeting ability. After CD44 receptor-mediated endocytosis, the nanosystem is embedded in endo/lysosomal vesicles and HA could be specially degraded by hyaluronidase (Hyal), inducing open pores. In the following, with visible light illumination, GHCNS could produce ROS that effectively induced lipid peroxidation and caused endo/lysosomal membrane break, accelerating the cytoplasmic release of the drug in the targeted and irradiated cells. As a result, significantly increased therapeutic potency and specificity against cancer cells could be achieved.As a novel technique, photochemical internalization (PCI) has been employed as a new approach to overcome endo/lysosomal restriction, which is one of the main difficulties in both drug and gene delivery. However, the complicated synthesis procedure (usually requiring the self-assembly of polymers, photosensitizers and cargos) and payload specificity greatly limit its further application. In this paper, we employ a highly fluorescent graphitic hollow carbon nitride nanosphere (GHCNS) to simultaneously serve as a PCI photosensitizer, an imaging agent and a drug carrier. The surface modification of GHCNS with multifunctional polysaccharide hyaluronic acid (HA) endows the system with colloidal

  15. Porous graphitic carbon nitride synthesized via direct polymerization of urea for efficient sunlight-driven photocatalytic hydrogen production

    Science.gov (United States)

    Zhang, Yuewei; Liu, Jinghai; Wu, Guan; Chen, Wei

    2012-08-01

    Energy captured directly from sunlight provides an attractive approach towards fulfilling the need for green energy resources on the terawatt scale with minimal environmental impact. Collecting and storing solar energy into fuel through photocatalyzed water splitting to generate hydrogen in a cost-effective way is desirable. To achieve this goal, low cost and environmentally benign urea was used to synthesize the metal-free photocatalyst graphitic carbon nitride (g-C3N4). A porous structure is achieved via one-step polymerization of the single precursor. The porous structure with increased BET surface area and pore volume shows a much higher hydrogen production rate under simulated sunlight irradiation than thiourea-derived and dicyanamide-derived g-C3N4. The presence of an oxygen atom is presumed to play a key role in adjusting the textural properties. Further improvement of the photocatalytic function can be expected with after-treatment due to its rich chemistry in functionalization.Energy captured directly from sunlight provides an attractive approach towards fulfilling the need for green energy resources on the terawatt scale with minimal environmental impact. Collecting and storing solar energy into fuel through photocatalyzed water splitting to generate hydrogen in a cost-effective way is desirable. To achieve this goal, low cost and environmentally benign urea was used to synthesize the metal-free photocatalyst graphitic carbon nitride (g-C3N4). A porous structure is achieved via one-step polymerization of the single precursor. The porous structure with increased BET surface area and pore volume shows a much higher hydrogen production rate under simulated sunlight irradiation than thiourea-derived and dicyanamide-derived g-C3N4. The presence of an oxygen atom is presumed to play a key role in adjusting the textural properties. Further improvement of the photocatalytic function can be expected with after-treatment due to its rich chemistry in

  16. Deposition of silicon nitride thin films by hot-wire CVD at 100 {sup o}C and 250 {sup o}C

    Energy Technology Data Exchange (ETDEWEB)

    Alpuim, P., E-mail: palpuim@fisica.uminho.p [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Goncalves, L.M. [Departamento de Electronica Industrial, Universidade do Minho, 4800-058 Guimaraes (Portugal); Marins, E.S. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Viseu, T.M.R. [Departamento de Fisica, Universidade do Minho, 4710-057 Braga (Portugal); Ferdov, S. [Departamento de Fisica, Universidade do Minho, 4800-058 Guimaraes (Portugal); Bouree, J.E. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS UMR 7647, Ecole Polytechnique, 91128 Palaiseau (France)

    2009-04-30

    Silicon nitride thin films for use as passivation layers in solar cells and organic electronics or as gate dielectrics in thin-film transistors were deposited by the Hot-wire chemical vapor deposition technique at a high deposition rate (1-3 A/s) and at low substrate temperature. Films were deposited using NH{sub 3}/SiH{sub 4} flow rate ratios between 1 and 70 and substrate temperatures of 100 {sup o}C and 250 {sup o}C. For NH{sub 3}/SiH{sub 4} ratios between 40 and 70, highly transparent (T {approx} 90%), dense films (2.56-2.74 g/cm{sup 3}) with good dielectric properties and refractive index between 1.93 and 2.08 were deposited on glass substrates. Etch rates in BHF of 2.7 A/s and < 0.5 A/s were obtained for films deposited at 100 {sup o}C and 250 {sup o}C, respectively. Films deposited at both substrate temperatures showed electrical conductivity {approx} 10{sup -14} {Omega}{sup -1} cm{sup -1} and breakdown fields > 10 MV cm{sup -1}.

  17. Passivation of Si and a-Si:H surfaces by thin oxide and oxy-nitride layers

    Energy Technology Data Exchange (ETDEWEB)

    Pincik, E. [Institute of Physics of SAS, Dubravska Cesta 9, 845 11 Bratislava (Slovakia)]. E-mail: emil.pincik@savba.sk; Kobayashi, H. [Institute of Scientific and Industrial Research, Osaka University, and CREST, Japan Science and Technology Organizarion, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Rusnak, J. [Institute of Physics of SAS, Dubravska Cesta 9, 845 11 Bratislava (Slovakia); Takahashi, M. [Institute of Scientific and Industrial Research, Osaka University, and CREST, Japan Science and Technology Organizarion, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Brunner, R. [Institute of Physics of SAS, Dubravska Cesta 9, 845 11 Bratislava (Slovakia); Jergel, M. [Institute of Physics of SAS, Dubravska Cesta 9, 845 11 Bratislava (Slovakia); Morales-Acevedo, A. [CINVESTAV-IPN, Electrical Engineering Departmant, Avenida IPN No. 2508, 07360 Mexico, D.F. (Mexico); Ortega, L. [Laboratoire de Cristallographie du CNRS, BP 166, 38042 Grenoble Cedex 09 (France); Kakos, J. [Department of Ceramics, Glass and Cement of FCFT of SUT, Radlinskeho 9, 812 37 Bratislava (Slovakia)

    2006-08-31

    An aim of the contribution is focused predominantly on investigation of electrical interface properties of MIS structures consisting of silicon-based substrates, which were passivated by 1.5-12 nm silicon dioxide, silicon nitride and/or silicon oxy-nitride layers. Substrates of different structural properties were used-crystalline Si (c-Si), amorphous hydrogenated silicon (a-Si:H), and silicon layer deposited by plasma enhanced chemical vapor deposition (PECVD). A stress was laid upon structures prepared on n moderately doped c-Si. The paper presents also changes of structural properties of a-Si:H surface after Ar low energy beam impact. For the first time we are presenting important results concerning utilization of X-ray diffraction with {beta} filter in investigation of a-Si:H cluster structure. Considerable part of the contribution is devoted to investigation of electrical properties of Al/Si{sub 3}N{sub 4}/Si (2-3 nm)/GaAs structures with aim to clarify the particular effect of the ultrathin Si interlayer in the structure. Our observations indicate that the silicon interlayer can act as delta doping of GaAs and/or as quantum well. Therefore, the experimental results are compared and discussed with calculated ones obtained by application of our theoretical description of electron emission of quantum well.

  18. Synthesis of Crystalline Carbon Nitride Thin Films by Pulsed Arc Discharge at Atmospheric Pressure

    Institute of Scientific and Technical Information of China (English)

    SHI Changyong; MA Zhibin

    2007-01-01

    The preparation of crystalline C3N4 films was investigated using pulsed arc discharge from mixed methanol and ammonia water at atmospheric pressure.The X-ray diffraction(XRD)patterns of the films prepared at a substrate temperature of 450℃ suggested that the film was composed of α-C3N4 and β-C3N4 crystallites.Raman spectra exhibited distinct peaks which are in good agreement with those predicted theoretically for C3N4 crystallites.

  19. Soil labile organic carbon and carbon-cycle enzyme activities under different thinning intensities in Chinese fir plantations

    NARCIS (Netherlands)

    Chen, Xinli; Chen, Han Y.H.; Chen, Xin; Wang, Jing; Chen, Bin; Wang, Dong; Guan, Qingwei

    2016-01-01

    Thinning is a silvicultural tool that is used to facilitate the growth of timber plantations worldwide. Plantations are important CO2 sinks, but the mechanism by which thinning affects the quantity and stability of soil organic carbon (SOC) is poorly understood. In this study, we exami

  20. A comparison between the mechanical and thermal properties of single-walled carbon nanotubes and boron nitride nanotubes

    Science.gov (United States)

    Li, Ting; Tang, Zhenan; Huang, Zhengxing; Yu, Jun

    2017-01-01

    Carbon nanotubes (CNTs) are semimetallic while boron nitride nanotubes (BNNTs) are wide band gap insulators. Despite the discrepancy in their electrical properties, a comparison between the mechanical and thermal properties of CNTs and BNNTs has a significant research value for their potential applications. In this work, molecular dynamics simulations are performed to systematically investigate the mechanical and thermal properties of CNTs and BNNTs. The calculated Young's modulus is about 1.1 TPa for CNTs and 0.72 TPa for BNNTs under axial compressions. The critical bucking strain and maximum stress are inversely proportional to both diameter and length-diameter ratio and CNTs are identified axially stiffer than BNNTs. Thermal conductivities of (10, 0) CNTs and (10, 0) BNNTs follow similar trends with respect to length and temperature and are lower than that of their two-dimensional counterparts, graphene nanoribbons (GNRs) and BN nanoribbons (BNNRs), respectively. As the temperature falls below 200 K (130 K) the thermal conductivity of BNNTs (BNNRs) is larger than that of CNTs (GNRs), while at higher temperature it is lower than the latter. In addition, thermal conductivities of a (10, 0) CNT and a (10, 0) BNNT are further studied and analyzed under various axial compressive strains. Low-frequency phonons which mainly come from flexure modes are believed to make dominant contribution to the thermal conductivity of CNTs and BNNTs.

  1. Largely enhanced dielectric properties of carbon nanotubes/polyvinylidene fluoride binary nanocomposites by loading a few boron nitride nanosheets

    Science.gov (United States)

    Yang, Minhao; Zhao, Hang; He, Delong; Bai, Jinbo

    2016-08-01

    The ternary nanocomposites of boron nitride nanosheets (BNNSs)/carbon nanotubes (CNTs)/polyvinylidene fluoride (PVDF) are fabricated via a combination of solution casting and extrusion-injection processes. The effects of BNNSs on the electrical conductivity, dielectric behavior, and microstructure changes of CNTs/PVDF binary nanocomposites are systematically investigated. A low percolation value (fc) for the CNTs/PVDF binary system is obtained due to the integration of solution and melting blending procedures. Two kinds of CNTs/PVDF binary systems with various CNTs contents (fCNTs) as the matrix are discussed. The results reveal that compared with CNTs/PVDF binary systems at the same fCNTs, the ternary BNNSs/CNTs/PVDF nanocomposites exhibit largely enhanced dielectric properties due to the improvement of the CNTs dispersion state and the conductive network. The dielectric constant of CNTs/PVDF binary nanocomposite with 6 vol. % CNTs (fCNTs fc), it displays a 43.32% improvement from 1325 to 1899 after the addition of 3 vol. % BNNSs. The presence of BNNSs facilitates the formation of the denser conductive network. Meanwhile, the ternary BNNSs/CNTs/PVDF systems exhibit a low dielectric loss. The adjustable dielectric properties could be obtained by employing the ternary systems due to the microstructure changes of nanocomposites.

  2. Gold and graphific carbon nitride hybrid plasmonic nanocomposites for photocatalytic reduction of 4-nitrophenol and 4-nitrobenzenethiol

    Science.gov (United States)

    Yan, Jiao; Xiao, Yuli; Liang, Xiu; Yang, Nan; Zhao, Dongyu; Yin, Penggang

    2016-09-01

    Gold nanoparticles (GNPs) were deposited on the surface of graphitic carbon nitride (g-C3N4) via an in situ reduction method using either sodium borohydride or trisodium citrate as the reducing agent. The corresponding hybrid Au/C3N4 nanocatalysts, viz., Au@CN-B or Au@CN-C, exhibited high light-driven catalytic activities toward reduction of 4-nitrophenol (4-NP) under either visible-light or ultra violet (UV) irradiation. The photocatalytic efficiency of Au@CN-B was only slightly higher than that of Au@CN-C, most likely owing to the average grain size difference between the both. However, as for plasmon-driven catalytic reactions monitored by surface-enhanced Raman scattering (SERS) technique, an immediate and almost-complete reduction of 4-nitrobenzenethiol (4-NBT) to p,p‧-dimercaptoazobenzene (DMAB) occurred when Au@CN-B was utilized as both the nanocatalyst and SERS substrate, whereas distinct characteristic peaks of 4-NBT still existed for the case of Au@CN-C.

  3. Transition metal (Fe, Co and Ni) oxide nanoparticles grafted graphitic carbon nitrides as efficient optical limiters and recyclable photocatalysts

    Science.gov (United States)

    Sridharan, Kishore; Kuriakose, Tintu; Philip, Reji; Park, Tae Joo

    2014-07-01

    A single-step pyrolysis assisted route towards the large scale fabrication of metal oxide nanoparticles (Fe2O3, Co3O4 and NiO) ingrained in graphitic carbon nitride (GCN) is demonstrated. Urea, an abundantly available precursor, plays a dual role during the synthesis: while it acts as a reducing agent, it also gets converted to GCN. The formation of GCN and the in-situ growth and embedment of oxide nanoparticles are discussed on the basis of the experimental results. The wide absorption of the samples in the visible light region makes them suitable for nonlinear transmission and photocatalytic activity studies. Visible light photocatalytic activities of the samples are studied by monitoring the degradation of Rhodamine B dye. Optical limiting properties of the prepared samples are studied through the open aperture z-scan technique using 5 ns laser pulses at a wavelength of 532 nm. The cost-efficient and time saving synthetic approach is complemented by the magnetic behaviour of the samples, which enables their use as recyclable photocatalyst and magnetically controllable optical limiters.

  4. Sulfur doping effects on the electronic and geometric structures of graphitic carbon nitride photocatalyst: insights from first principles.

    Science.gov (United States)

    Stolbov, Sergey; Zuluaga, Sebastian

    2013-02-27

    We present here results of our first-principles studies of the sulfur doping effects on the electronic and geometric structures of graphitic carbon nitride (g-C(3)N(4)). Using the ab initio thermodynamics approach combined with some kinetic analysis, we reveal the favorable S-doping configurations. By analyzing the valence charge densities of the doped and undoped systems, we find that sulfur partially donates its p(x)- and p(y)- electrons to the system with some back donation to the S p(z)-states. To obtain an accurate description of the excited electronic states, we calculate the electronic structure of the systems using the GW method. The band gap width calculated for g-C(3)N(4) is found to be equal to 2.7 eV, which is in agreement with experiment. We find the S doping causes a significant narrowing of the gap. Furthermore, the electronic states just above the gap become occupied upon doping, making the material a conductor. Analysis of the projected local density of states provides an insight into the mechanism underlying such changes in the electronic structure of g-C(3)N(4) upon S doping. Based on our results, we propose a possible explanation for the S-doping effect on the photocatalytic properties of g-C(3)N(4) observed in experiments.

  5. Polymeric Graphitic Carbon Nitride Doped with CuO Dispersed on Dealuminated Clinoptilolite (CuO/HCP: Synthesis and Characterisation

    Directory of Open Access Journals (Sweden)

    Saheed Olalekan Sanni

    2015-01-01

    Full Text Available CuO dispersed on dealuminated clinoptilolite (CuO/HCP and further doped with polymeric graphitic carbon nitride (CuO/HCP-g-C3N4 was synthesized through 2 facile routes: precipitation method for CuO/HCP and impregnation through ultrasonication method for the hybrid composite material. The hybrid composite material crystalline phase, surface morphology, and structural and thermal properties were investigated by X-ray diffraction (XRD, scanning electron microscopy (SEM, energy-dispersive X-ray analysis (EDAX, Fourier transform infrared spectroscopy (FTIR, and thermal analysis. The formation of the hybrid composite material was confirmed by XRD showing crystalline phase of CuO and g-C3N4 present on the surface of dealuminated clinoptilolite (HCP. SEM images analysis depicts no aggregation of the mixed metal oxide semiconductor nanoparticles at the center of HCP. The hybrid composite material, CuO/HCP-g-C3N4, with a good homogeneously dispersed metal oxide conductor having excellent catalytic activities has been synthesized.

  6. Application of gallium nitride nanostructures and nitrogen doped carbon spheres as supports for the hydrogenation of cinnamaldehyde.

    Science.gov (United States)

    Kente, Thobeka; Dube, Sibongile M A; Coville, Neil J; Mhlanga, Sabelo D

    2013-07-01

    This paper reports on the synthesis and use of nanostructures of gallium nitride (GaN NSs) and nitrogen doped carbon spheres (NCSs) as support materials for the hydrogenation of cinnamaldehyde. This study provides the first investigation of GaN as a catalyst support in hydrogenation reactions. The GaN NSs were synthesized via chemical vapour deposition (CVD) in a double stage furnace (750 degrees C) while NCSs were made by CVD in a single stage furnace (950 degrees C) respectively. TEM analysis revealed that the GaN NSs were rod-like with average diameters of 200 nm, while the NCSs were solid with smoother surfaces, and with diameters of 450 nm. Pd nanoparticles (1 and 3% loadings) were uniformly dispersed on acid functionalized GaN NSs and NCS. The Pd nanoparticles had average diameters that were influenced by the type of support material used. The GaN NSs and NCSs were tested for the selective hydrogenation of cinnamaldehyde in isopropanol at 40 and 60 degrees C under atmospheric pressure. A comparative study of the activity of the nanostructured materials revealed that the order of catalyst activity was 3% Pd/GaN > 3% Pd/NCSs > 1% Pd/NCSs > 1% Pd/GaN. However, 100% selectivity to hydrocinnamaldehyde (HCALD) was obtained with 1% Pd/GaN at reasonable conversion rates.

  7. Highly efficient photocatalytic H₂ evolution from water using visible light and structure-controlled graphitic carbon nitride.

    Science.gov (United States)

    Martin, David James; Qiu, Kaipei; Shevlin, Stephen Andrew; Handoko, Albertus Denny; Chen, Xiaowei; Guo, Zhengxiao; Tang, Junwang

    2014-08-25

    The major challenge of photocatalytic water splitting, the prototypical reaction for the direct production of hydrogen by using solar energy, is to develop low-cost yet highly efficient and stable semiconductor photocatalysts. Herein, an effective strategy for synthesizing extremely active graphitic carbon nitride (g-C3N4) from a low-cost precursor, urea, is reported. The g-C3N4 exhibits an extraordinary hydrogen-evolution rate (ca. 20,000 μmol h(-1) g(-1) under full arc), which leads to a high turnover number (TON) of over 641 after 6 h. The reaction proceeds for more than 30 h without activity loss and results in an internal quantum yield of 26.5% under visible light, which is nearly an order of magnitude higher than that observed for any other existing g-C3N4 photocatalysts. Furthermore, it was found by experimental analysis and DFT calculations that as the degree of polymerization increases and the proton concentration decreases, the hydrogen-evolution rate is significantly enhanced.

  8. Density functional theory study of ultrasmall diameter (2,2) boron nitride, silicon carbide, and carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Fakhrabad, Davoud Vahedi; Shahtahmassebi, Nasser [Nano Research Center, Department of Physics, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Movlarooy, Tayebeh [Department of Physics, Shahrood University of Technology, Shahrood (Iran, Islamic Republic of)

    2012-05-15

    We present a first principles calculation on the electronic structure and optical properties of ultrasmall-diameter (2,2) boron nitride, silicon carbide, and carbon nanotubes (BNNT, SiCNT, and CNT) by using full potential linear augmented plane wave (FP-LAPW) and pseudo potential plane wave (PP-PW) methods. The atomic geometries of all considered models are optimized. Calculations of optical spectra are performed under electric fields polarized both parallel and perpendicular with respect to the nanotube (NT) axis. Our results show that the dielectric function is anisotropic and it is revealed that (2,2) SiCNT would be better dielectric material than (2,2) BNNT. We have calculated the first, second and third optical transitions for the considered models. The value of the optical gap for (2,2) BNNT is obtained much larger than that of (2,2) SiCNT and (2,2) CNT. The results show that contrary to the (2,2) CNT being metallic, the (2,2) BNNT, and (2,2) SiCNT are wide indirect gap semiconductors. We also present the energy loss function; in this case the intertube interactions play an important role with respect to the optical spectroscopy. Our results revealed that unlike the dielectric function, the calculated energy loss function show rather weak anisotropy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. A simple fabrication for sulfur doped graphitic carbon nitride porous rods with excellent photocatalytic activity degrading RhB dye

    Science.gov (United States)

    Fan, Qianjing; Liu, Jianjun; Yu, Yingchun; Zuo, Shengli; Li, Baoshan

    2017-01-01

    Constructing special nanostructures with large surface areas and tuning the band gap by element doping are efficient strategies to enhance the photocatalytic activity of semiconductor materials. Here we combined both strategies in one material to form sulfur-doped graphitic carbon nitride porous rods (S-pg-C3N4) in one pot by simply pyrolysis of the melamine-trithiocyanuric acid complex with different temperatures. The samples were characterized by XRD, FT-IR, and elemental analysis; nitrogen adsorption isotherms, SEM and TEM images; and UV-vis DRS and photoluminescence spectra. Characterizations showed that S-pg-C3N4 possessed porous rod structure with a larger surface area (20-52 m2/g) than that of bulk g-C3N4, and the surface area of the S-pg-C3N4 samples increased with the increase of heating temperature. Meanwhile, the trace sulfur remained in the framework of g-C3N4 formed sulfur doped g-C3N4, and the visible light absorption edge of the S-pg-C3N4 was extended, corresponding to a narrowed band gap. As a result, the S-pg-C3N4 samples exhibited an enhanced physical adsorption and photocatalytic activity in the degradation of Rhodamine B dye under visible light.

  10. Facile fabrication of novel porous graphitic carbon nitride/copper sulfide nanocomposites with enhanced visible light driven photocatalytic performance.

    Science.gov (United States)

    Chen, Xi; Li, Huankun; Wu, Yuxin; Wu, Hanshuo; Wu, Laidi; Tan, Pengfei; Pan, Jun; Xiong, Xiang

    2016-08-15

    In this work, a novel organic-inorganic heterostructured photocatalyst: porous graphitic carbon nitride (g-C3N4) hybrid with copper sulfide (CuS) had been synthesized via a precipitation-deposition method at low temperature for the first time. UV-vis spectroscopy revealed the porous g-C3N4/CuS nanocomposites showed a strong and broad visible light absorption. Furthermore, the g-C3N4/CuS nanocomposites showed higher photocatalytic activity in the photodegradation of various organic dyes than that of pure g-C3N4 and CuS, and the selected sample of g-C3N4/CuS-2 exhibited the best photocatalytic activity under visible light. The good photocatalytic activity could be ascribed to the matching of the g-C3N4 and CuS band gap energies. Besides, photoluminescent spectra and photoelectrochemical measurements also proved that the CuS/g-C3N4 could greatly enhance the charge generation and suppress the charge recombination of photogenerated carriers. According to the experimental result, a possible photocatalytic mechanism has been proposed. Due to the high stability, the porous g-C3N4/CuS could be applied in the field of environmental remediation. Our work highlights that coupling semiconductors with well-matched band energies provides a facile way to improve the photocatalytic activity.

  11. Carbon Nanotube/Boron Nitride Nanocomposite as a Significant Bifunctional Electrocatalyst for Oxygen Reduction and Oxygen Evolution Reactions.

    Science.gov (United States)

    Patil, Indrajit M; Lokanathan, Moorthi; Ganesan, Balakrishnan; Swami, Anita; Kakade, Bhalchandra

    2017-01-12

    It is an immense challenge to develop bifunctional electrocatalysts for oxygen reduction reactions (ORR) and oxygen evolution reactions (OER) in low temperature fuel cells and rechargeable metal-air batteries. Herein, a simple and cost-effective approach is developed to prepare novel materials based on carbon nanotubes (CNTs) and a hexagonal boron nitride (h-BN) nanocomposite (CNT/BN) through a one-step hydrothermal method. The structural analysis and morphology study confirms the formation of a homogeneous composite and merging of few exfoliated graphene layers of CNTs on the graphitic planes of h-BN, respectively. Moreover, the electrochemical study implies that CNT/BN nanocomposite shows a significantly higher ORR activity with a single step 4-electron transfer pathway and an improved onset potential of +0.86 V versus RHE and a current density of 5.78 mA cm(-2) in alkaline conditions. Interestingly, it exhibits appreciably better catalytic activity towards OER at low overpotential (η=0.38 V) under similar conditions. Moreover, this bifunctional catalyst shows substantially higher stability than a commercial Pt/C catalyst even after 5000 cycles. Additionally, this composite catalyst does not show any methanol oxidation reactions that nullify the issues due to fuel cross-over effects in direct methanol fuel cell applications.

  12. Large-scale production of graphitic carbon nitride with outstanding nitrogen photofixation ability via a convenient microwave treatment

    Science.gov (United States)

    Ma, Huiqiang; Shi, Zhenyu; Li, Shuang; Liu, Na

    2016-08-01

    A convenient microwave treatment for synthesizing graphitic carbon nitride (g-C3N4) with outstanding nitrogen photofixation ability under visible light is reported. X-ray diffraction (XRD), N2 adsorption, UV-vis spectroscopy, SEM, N2-TPD, EPR, photoluminescence (PL) and photocurrent measurements were used to characterize the prepared catalysts. The results indicate that microwave treatment can form many irregular pores in as-prepared g-C3N4, which causes the increased surface area and separation rate of electrons and holes. More importantly, microwave treatment causes the formation of many nitrogen vacancies in as-prepared g-C3N4. These nitrogen vacancies not only serve as active sites to adsorb and activate N2 molecules but also promote interfacial charge transfer from catalysts to N2 molecules, thus significantly improving the nitrogen photofixation ability. Moreover, the present process is a convenient method for large-scale production of g-C3N4 which is significantly important for the practical application.

  13. Mesoporous carbon nitride based biosensor for highly sensitive and selective analysis of phenol and catechol in compost bioremediation.

    Science.gov (United States)

    Zhou, Yaoyu; Tang, Lin; Zeng, Guangming; Chen, Jun; Cai, Ye; Zhang, Yi; Yang, Guide; Liu, Yuanyuan; Zhang, Chen; Tang, Wangwang

    2014-11-15

    Herein, we reported here a promising biosensor by taking advantage of the unique ordered mesoporous carbon nitride material (MCN) to convert the recognition information into a detectable signal with enzyme firstly, which could realize the sensitive, especially, selective detection of catechol and phenol in compost bioremediation samples. The mechanism including the MCN based on electrochemical, biosensor assembly, enzyme immobilization, and enzyme kinetics (elucidating the lower detection limit, different linear range and sensitivity) was discussed in detail. Under optimal conditions, GCE/MCN/Tyr biosensor was evaluated by chronoamperometry measurements and the reduction current of phenol and catechol was proportional to their concentration in the range of 5.00 × 10(-8)-9.50 × 10(-6)M and 5.00 × 10(-8)-1.25 × 10(-5)M with a correlation coefficient of 0.9991 and 0.9881, respectively. The detection limits of catechol and phenol were 10.24 nM and 15.00 nM (S/N=3), respectively. Besides, the data obtained from interference experiments indicated that the biosensor had good specificity. All the results showed that this material is suitable for load enzyme and applied to the biosensor due to the proposed biosensor exhibited improved analytical performances in terms of the detection limit and specificity, provided a powerful tool for rapid, sensitive, especially, selective monitoring of catechol and phenol simultaneously. Moreover, the obtained results may open the way to other MCN-enzyme applications in the environmental field.

  14. Correlation of photothermal conversion on the photo-induced deformation of amorphous carbon nitride films prepared by reactive sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Harata, T.; Aono, M., E-mail: aono@nda.ac.jp; Kitazawa, N.; Watanabe, Y. [Department of Materials Science and Engineering, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa 239-8686 (Japan)

    2014-08-04

    The photo-induced deformation of hydrogen-free amorphous carbon nitride (a-CN{sub x}) films was investigated under visible-light illumination. The films gave rise to photothermal conversion by irradiation. In this study, we investigated the effects of thermal energy generated by irradiation on the deformation of a-CN{sub x}/ultrathin substrate bimorph specimens. The films were prepared on both ultrathin Si and SiO{sub 2} substrates by reactive radio-frequency magnetron sputtering from a graphite target in the presence of pure nitrogen gas. The temperature of the film on the SiO{sub 2} substrate increased as the optical band-gap of the a-CN{sub x} was decreased. For the film on Si, the temperature remained constant. The deformation degree of the films on Si and SiO{sub 2} substrates were approximately the same. Thus, the deformation of a-CN{sub x} films primarily induced by photon energy directly.

  15. Torsional properties of hexagonal boron nitride nanotubes, carbon nanotubes and their hybrid structures: A molecular dynamics study

    Directory of Open Access Journals (Sweden)

    Qi-lin Xiong

    2015-10-01

    Full Text Available The torsional mechanical properties of hexagonal single-walled boron nitride nanotubes (SWBNNTs, single-walled carbon nanotubes (SWCNTs, and their hybrid structures (SWBN-CNTs are investigated using molecular dynamics (MD simulation. Two approaches - force approach and energy approach, are adopted to calculate the shear moduli of SWBNNTs and SWCNTs, the discrepancy between two approaches is analyzed. The results show that the shear moduli of single-walled nanotubes (SWNTs, including SWBNNTs and SWCNTs are dependent on the diameter, especially for armchair SWNTs. The armchair SWNTs show the better ability of resistance the twisting comparable to the zigzag SWNTs. The effects of diameter and length on the critical values of torque of SWNTs are obtained by comparing the torsional behaviors of SWNTs with different diameters and different lengths. It is observed that the MD results of the effect of diameter and length on the critical values of torque agrees well with the prediction of continuum shell model. The shear modulus of SWBN-CNT has a significant dependence on the percentages of SWCNT and the hybrid style has also an influence on shear modulus. The critical values of torque of SWBN-CNTs increase with the increase of the percentages of SWCNT. This phenomenon can be interpreted by the function relationship between the torque of different bonds (B-N-X, C-C-X, C-B-X, C-N-X and the angles of bonds.

  16. Facile and Scale Up Synthesis of Red Phosphorus-Graphitic Carbon Nitride Heterostructures for Energy and Environment Applications

    Science.gov (United States)

    Ansari, Sajid Ali; Ansari, Mohammad Omaish; Cho, Moo Hwan

    2016-06-01

    The development of heterostructured materials for efficient solar energy conversion and energy storage devices are essential for practical applications. In this study, a simple and relatively inexpensive method was used to improve the visible light-driven photocatalytic activity and electrochemical supercapacitor behavior of the graphitic carbon nitride (g-C3N4) by elemental red phosphorus (RPh). The as-prepared RPh-g-C3N4 was characterized in detail using a range of spectroscopic techniques to understand the structure, morphology, chemical interaction, and chemical state of the materials. The visible light-driven photocatalytic activity and supercapacitive electrode performance were assessed by the photodegradation of model colored, non-colored organic pollutants, and electrochemical half-cell measurements, respectively. The RPh-g-C3N4 heterostructure with 30 weight percent of RPh exhibited remarkably high photocatalytic activity for the degradation of pollutants compared to the bare constituent materials, which was further confirmed by the photoelectrochemical study under similar visible photoirradiation conditions. The RPh-g-C3N4 heterostructure supercapacitor electrode displayed a high capacitance of 465 F/g and excellent cyclic stability with capacitance retention of 90% after 1000 cycles at a current of 10 A/g. The superior performance was attributed mainly to the narrow band gap, high surface area, capacitive nature of RPh, and nitrogen-rich skeleton of g-C3N4.

  17. Aligned carbon nanotube thin films for DNA electrochemical sensing

    Energy Technology Data Exchange (ETDEWEB)

    Berti, F. [Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, Firenze 50019 (Italy); Lozzi, L. [Department of Physics, University of L' Aquila, Coppito, L' Aquila 67100 (Italy); Palchetti, I. [Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, Firenze 50019 (Italy); Santucci, S. [Department of Physics, University of L' Aquila, Coppito, L' Aquila 67100 (Italy); Marrazza, G. [Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, Firenze 50019 (Italy)], E-mail: giovanna.marrazza@unifi.it

    2009-09-01

    Carbon nanotubes are interesting materials for DNA electrochemical sensing due to their unique electric properties: high surface area, fast heterogeneous electron transfer, and electrochemical stability. In this work aligned Carbon NanoTube (CNT) thin films were designed and tested as candidate platforms for DNA immobilization and for the development of an electrochemical genosensor. The films were prepared by Chemical Vapor Deposition (CVD) using acetylene and ammonia as precursor gases and nickel particles as catalyst. A preliminary electrochemical characterization was performed using cyclic voltammetry since, so far, these films have been used only for gas sensing. The surfaces were then covalently functionalized with a DNA oligonucleotide probe, complementary to the sequence of the most common inserts in the GMOs: the Promoter 35S. The genosensor format involved the immobilization of the probe onto the sensor surface, the hybridization with the target-sequence and the electrochemical detection of the duplex formation. Careful attention was paid to the probe immobilization conditions in order to minimize the signal due to non-specifically adsorbed sequences. For the detection of the hybridization event both label-free and enzyme-labelled methods were investigated. In case of the enzyme-labelled method a target concentration at nanomolar level can be easily detected, with a linear response from 50 nM to 200 nM, whereas the label-free method showed a linear response between 0.5 {mu}M and 10 {mu}M. The reproducibility was 11% and 20% with the enzyme-labelled method and the label-free method, respectively. The batch-to-batch reproducibility of the different sensors was also evaluated.

  18. Durable ultrathin silicon nitride/carbon bilayer overcoats for magnetic heads: The role of enhanced interfacial bonding

    Energy Technology Data Exchange (ETDEWEB)

    Yeo, Reuben J.; Dwivedi, Neeraj; Bhatia, Charanjit S., E-mail: elebcs@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore 117583 (Singapore); Zhang, Lu [Institute of Microelectronics (IME), A*STAR (Agency for Science, Technology, and Research), 11 Science Park Road, Singapore Science Park II, Singapore, Singapore 117685 (Singapore); Zhang, Zheng; Tripathy, S. [Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology, and Research), 3 Research Link, Singapore, Singapore 117602 (Singapore); Lim, Christina Y. H. [Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore 117575 (Singapore)

    2015-01-28

    Pole tip recession (PTR) is one of the major issues faced in magnetic tape storage technology, which causes an increase in the magnetic spacing and hence signal loss during data readback. Despite efforts to reduce the magnetic spacing, PTR, and surface wear on the heads by using protective overcoats, most of them either employ complex fabrication processes and approaches do not provide adequate protection to the head or are too thick (∼10–20 nm), especially for future high density tape storage. In this work, we discuss an approach to reduce the PTR and surface wear at the head by developing an ultrathin ∼7 nm bilayer overcoat of silicon/silicon nitride (Si/SiN{sub x}) and carbon (C), which is totally fabricated by a cost-effective and industrial-friendly magnetron sputtering process. When compared with a monolithic C overcoat of similar thickness, the electrically insulating Si/SiN{sub x}/C bilayer overcoat was found to provide better wear protection for commercial tape heads, as demonstrated by Auger electron spectroscopic analyses after wear tests with commercial tape media. Although the microstructures of carbon in the monolithic and bilayer overcoats were similar, the improved wear durability of the bilayer overcoat was attributed to the creation of extensive interfacial bonding of Si and N with the C overcoat and the alumina-titanium carbide composite head substrate, as predicted by time-of-flight secondary ion mass spectrometry and confirmed by in-depth X-ray photoelectron spectroscopy analyses. This study highlights the pivotal role of enhanced interfaces and interfacial bonding in developing ultrathin yet wear-durable overcoats for tape heads.

  19. Ultra-small vanadium nitride quantum dots embedded in porous carbon as high performance electrode materials for capacitive energy storage

    Science.gov (United States)

    Yang, Yunlong; Zhao, Lei; Shen, Kuiwen; Liu, Ying; Zhao, Xiaoning; Wu, Yage; Wang, Yanqin; Ran, Fen

    2016-11-01

    Ultra-small vanadium nitride quantum dots embedded in porous carbon (VNQDs/PC) were fabricated by a thermal treatment process of NH4VO3/C3H6N6 under nitrogen atmosphere. The specific capacitance of VNQDs/PC was 1008 mF cm-2 at a current density of 0.004 A cm-2, whereas the VN/carbon hybrid material obtained by a solid-state blending of NH4VO3 and C3H6N6 just exhibited a capacitance of 432 mF cm-2 at the same current density. By mediating the ratio of NH4VO3 and C3H6N6, a maximum specific capacitance of 1124 mF cm-2 was achieved at a current density of 0.002 A cm-2 in aqueous 6 mol/L KOH electrolyte with the potential range from 0 to -1.15 V when it reached 1: 7 (wt./wt.). Additionally, symmetrical supercapacitor fabricated with synthesized VNQDs/PC presented a high specific capacitance of 215 mF cm-2 at 0.002 A cm-2 based on the entire cell, and exhibited a high capacitance retention of 86.6% with current density increased to 5 A g-1. The VNQDs/PC negative electrodes were combined with Ni(OH)2 positive electrodes for the fabrication of hybrid supercapacitors. Remarkably, at a power density of 828.7 W kg-1, the device delivered an ultrahigh energy density of 47.2 Wh kg-1.

  20. Construction of carbon quantum dots/proton-functionalized graphitic carbon nitride nanocomposite via electrostatic self-assembly strategy and its application

    Science.gov (United States)

    Jian, Xuan; Liu, Xian; Yang, Hui-min; Li, Jia-gang; Song, Xiu-li; Dai, Hong-yan; Liang, Zhen-hai

    2016-05-01

    Carbon quantum dots (CQDs) and graphitic carbon nitride (g-C3N4), as advanced metal-free material catalysts have been the focus of considerable attention because of their superior photocatalytic activities. In this study, we developed a novel approach to obtain CQDs/g-C3N4 nanocomposite with effective interfacial contact by incorporating negatively charged CQDs and tailor-made proton-functionalized g-C3N4via the electrostatic self-assembly strategy. Then, the morphology and microstructure of the new nanocomposite were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The CQDs and proton-functionalized g-C3N4 nanocomposite exhibited excellent electron transfer properties though electrochemical impedance spectroscopy (EIS), significantly enhanced photoactivity in the photoelectrochemical i-t curve test and degradation of methylene blue solution under visible light irradiation. These results demonstrated that the electrostatic self-assembly strategy process is a promising method of fabricating uniform metal-free material catalysts for an extensive range of applications.

  1. Novel metal-carbon(60) nanocrystalline magnetic thin films

    Science.gov (United States)

    Zheng, Lingyi

    1999-11-01

    A novel type of nanocrystalline magnetic thin films consisting of ferromagnetic metals and C60 have been developed and investigated. CO-C 60, Fe-C60 and CoFe-C60 with different concentrations of C60 thin films have been manufactured by thermal vapor codeposition. The microstructures and magnetic properties of the films can be significantly enhanced by varying the concentrations of C60 in the films. The stability of C60 and the compatibility of C60 with the metallic matrices are confirmed by mass spectrometry, Raman, WDS, XRD and TEM. Strong metal- C60 interaction is indicated by higher desorption temperatures of C60 in the meta- C60 films than that in pure C60 and the peak shift in Raman spectra. TEM shows that the grain size of the matrix metal decreases proportionally with increasing C60 concentration. Nanosize uniform columnar grains with nanoscale dispersion of C60 on the grain boundaries are commonly observed in the metal-C60 films. A self- assembly grain growth model based on the size effect of C60 and the metal-C60 interaction is proposed to delineate the microstructural evolution by C60. Calculations based on this model are consistent with experimental observations and give a grain size vs. C60 (carbon) concentration relationship. Grain growth retardation by C60 is observed in a CO-C60 film. Out-plane magnetic remanence and coercivity are enhanced in both the CO-C60 and Fe-C60 films. In the in-plane direction, the coercivity deceases in CO- C60 films but increases slightly in Fe- C60 films with increasing C60 concentrations. In-plane magnetic anisotropy is detected in CO-C60 films but not in Fe-C60 films. Strong temperature-dependent magnetization remanence and saturation are found in both the Co- C60 and Fe-C60 films with high C60 concentrations due to the nanosize grain effects. Temperature effects on the coercivity of CO- C60 and Fe-C60 are different and determined by the intrinsic magnetocrystalline anisotropy energy. Coercivity of the CoFe-C60 films

  2. Correlations between optical properties, microstructure, and processing conditions of Aluminum nitride thin films fabricated by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Jonghoon [Department of Electrical and Computer Engineering, Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States)]. E-mail: jhoon6@hotmail.com; Ma, James [Materials Science and Engineering Program, Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States); Becker, Michael F. [Department of Electrical and Computer Engineering, Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States); Keto, John W. [Department of Physics, Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States); Kovar, Desiderio [Department of Mechanical Engineering, Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States)

    2007-06-25

    Aluminum nitride (AlN) films were deposited using pulsed laser deposition (PLD) onto sapphire (0001) substrates with varying processing conditions (temperature, pressure, and laser fluence). We have studied the dependence of optical properties, structural properties and their correlations for these AlN films. The optical transmission spectra of the produced films were measured, and a numerical procedure was applied to accurately determine the optical constants for films of non-uniform thickness. The microstructure and texture of the films were studied using various X-ray diffraction techniques. The real part of the refractive index was found to not vary significantly with processing parameters, but absorption was found to be strongly dependent on the deposition temperature and the nitrogen pressure in the deposition chamber. We report that low optical absorption, textured polycrystalline AlN films can be produced by PLD on sapphire substrates at both low and high laser fluence using a background nitrogen pressure of 6.0 x 10{sup -2} Pa (4.5 x 10{sup -4} Torr) of 99.9% purity.

  3. Improving the Microstructure and Electrical Properties of Aluminum Induced Polysilicon Thin Films Using Silicon Nitride Capping Layer

    Directory of Open Access Journals (Sweden)

    Min-Hang Weng

    2014-01-01

    Full Text Available We investigated the capping layer effect of SiNx (silicon nitride on the microstructure, electrical, and optical properties of poly-Si (polycrystalline silicon prepared by aluminum induced crystallization (AIC. The primary multilayer structure comprised Al (30 nm/SiNx (20 nm/a-Si (amorphous silicon layer (100 nm/ITO coated glass and was then annealed in a low annealing temperature of 350°C with different annealing times, 15, 30, 45, and 60 min. The crystallization properties were analyzed and verified by X-ray diffraction (XRD and Raman spectra. The grain growth was analyzed via optical microscope (OM and scanning electron microscopy (SEM. The improved electrical properties such as Hall mobility, resistivity, and dark conductivity were investigated by using Hall and current-voltage (I-V measurements. The results show that the amorphous silicon film has been effectively induced even at a low temperature of 350°C and a short annealing time of 15 min and indicate that the SiNx capping layer can improve the grain growth and reduce the metal content in the induced poly-Si film. It is found that the large grain size is over 20 μm and the carrier mobility values are over 80 cm2/V-s.

  4. Covalently coupled hybrid of graphitic carbon nitride with reduced graphene oxide as a superior performance lithium-ion battery anode.

    Science.gov (United States)

    Fu, Yongsheng; Zhu, Junwu; Hu, Chong; Wu, Xiaodong; Wang, Xin

    2014-11-01

    An in situ chemical synthetic approach has been designed for the fabrication of a covalently coupled hybrid consisting of graphitic carbon nitride (g-C3N4) with reduced graphene oxide (rGO) with differing g-C3N4/rGO ratio. The epoxy groups of graphene oxide (GO) undergo a nucleophilic substitution reaction with dicyandiamide (C2H4N4) to form the C2H4N4-GO composite via a covalent C-N bond, and then both the in situ polymerization of C2H4N4 and the thermal reduction of GO can be achieved at higher temperatures, forming the covalently coupled g-C3N4-rGO. FT-IR, CP-MAS NMR and XPS analyses, clearly revealed a covalent interaction between the g-C3N4 and rGO sheets. The g-C3N4-rGO exhibits an unprecedented high, stable and reversible capacity of 1525 mA h g(-1) at a current density of 100 mA g(-1) after 50 cycles. Even at a large current density of 1000 mA g(-1), a reversible capacity of 943 mA h g(-1) can still be retained. The superior electrochemical performance of g-C3N4-rGO is attributed to the specific characteristics of the unique nanostructure of g-C3N4-rGO and the concerted effects of g-C3N4 and rGO, including covalent interactions between the two moieties, the good conductivity and high special surface area of the nanocomposite, as well as the template effect of the planar amino group of g-C3N4 for the dispersed decoration of Li(+) ions.

  5. Amorphous carbon nitride as an alternative electrode material in electroanalysis: simultaneous determination of dopamine and ascorbic acid.

    Science.gov (United States)

    Medeiros, Roberta A; Matos, Roberto; Benchikh, Abdelkader; Saidani, Boualem; Debiemme-Chouvy, Catherine; Deslouis, Claude; Rocha-Filho, Romeu C; Fatibello-Filho, Orlando

    2013-10-03

    Boron-doped diamond (BDD) films are excellent electrode materials, whose electrochemical activity for some analytes can be tuned by controlling their surface termination, most commonly either to predominantly hydrogen or oxygen. This tuning can be accomplished by e.g. suitable cathodic or anodic electrochemical pretreatments. Recently, it has been shown that amorphous carbon nitride (a-CNx) films may present electrochemical characteristics similar to those of BDD, including the influence of surface termination on their electrochemical activity toward some analytes. In this work, we report for the first time a complete electroanalytical method using an a-CNx electrode. Thus, an a-CNx film deposited on a stainless steel foil by DC magnetron sputtering is proposed as an alternative electrode for the simultaneous determination of dopamine (DA) and ascorbic acid (AA) in synthetic biological samples by square-wave voltammetry. The obtained results are compared with those attained using a BDD electrode. For both electrodes, a same anodic pretreatment in 0.1 mol L(-1) KOH was necessary to attain an adequate and equivalent separation of the DA and AA oxidation potential peaks of about 330 mV. The detection limits obtained for the simultaneous determination of these analytes using the a-CNx electrode were 0.0656 μmol L(-1) for DA and 1.05 μmol L(-1) for AA, whereas with the BDD electrode these values were 0.283 μmol L(-1) and 0.968 μmol L(-1), respectively. Furthermore, the results obtained in the analysis of the analytes in synthetic biological samples were satisfactory, attesting the potential application of the a-CNx electrode in electroanalysis.

  6. The production of silicon carbon nitride ceramic fibres from poly-silazane polymers. Herstellung von Siliciumcarbonitrid-Keramikfasern aus Polysilazan-Polymeren

    Energy Technology Data Exchange (ETDEWEB)

    Holzinger, R.

    1994-07-14

    The investigations carried out in this work can be divided into two main points. One, the process technique branch, goes along the polymer precursor route. This includes the melt spinning of the poly-silazane polymers, the stabilisation of the green fibres and finally pyrolysis to silicon-carbon nitride ceramic fibres. Starting from the polymers, all the reactions and structural changes during the individual steps are examined. These experiments represent the second main part of the work. The optimisation criterion is always the tensile strength of the resulting ceramic fibres. (orig.)

  7. Interfacial electronic structure and charge transfer of hybrid graphene quantum dot and graphitic carbon nitride nanocomposites: insights into high efficiency for photocatalytic solar water splitting.

    Science.gov (United States)

    Ma, Zuju; Sa, Rongjian; Li, Qiaohong; Wu, Kechen

    2016-01-14

    New metal-free carbon nanodot/carbon nitride (C3N4) nanocomposites have shown to exhibit high efficiency for photocatalytic solar water splitting. (J. Liu, et al., Science, 2015, 347, 970) However, the mechanism underlying the ultrahigh performance of these nanocomposites and consequently the possibilities for further improvements are not at present clear. In this work, we performed hybrid functional calculations and included long-range dispersion corrections to accurately characterize the interfacial electron coupling of the graphene quantum dot-graphitic carbon nitride composites (Gdot/g-C3N4). The results revealed that the band gap of Gdot/g-C3N4 could be engineered by changing the lateral size of Gdots. In particular, the C24H12/g-C3N4 composites present an ideal band gap of 1.92 eV to harvest a large part of solar light. More interestingly, a type-II heterojunction is formed at the interface of the Gdot/g-C3N4 composites, a desirable feature for enhanced photocatalytic activity. The charge redistribution at the interface leads to strong electron depletion above the Gdot sheet and electron accumulation below the g-C3N4 monolayer, potentially facilitating the separation of H2O oxidation and reduction reactions. Furthermore, we suggested that the photocatalytic performance of the Gdot/g-C3N4 nanocomposites can be further improved by decreasing the thickness of Gdots and tuning the size of Gdots.

  8. Controlling the Pore Size of Mesoporous Carbon Thin Films through Thermal and Solvent Annealing.

    Science.gov (United States)

    Zhou, Zhengping; Liu, Guoliang

    2017-02-02

    Herein an approach to controlling the pore size of mesoporous carbon thin films from metal-free polyacrylonitrile-containing block copolymers is described. A high-molecular-weight poly(acrylonitrile-block-methyl methacrylate) (PAN-b-PMMA) is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The authors systematically investigate the self-assembly behavior of PAN-b-PMMA thin films during thermal and solvent annealing, as well as the pore size of mesoporous carbon thin films after pyrolysis. The as-spin-coated PAN-b-PMMA is microphase-separated into uniformly spaced globular nanostructures, and these globular nanostructures evolve into various morphologies after thermal or solvent annealing. Surprisingly, through thermal annealing and subsequent pyrolysis of PAN-b-PMMA into mesoporous carbon thin films, the pore size and center-to-center spacing increase significantly with thermal annealing temperature, different from most block copolymers. In addition, the choice of solvent in solvent annealing strongly influences the block copolymer nanostructure and the pore size of mesoporous carbon thin films. The discoveries herein provide a simple strategy to control the pore size of mesoporous carbon thin films by tuning thermal or solvent annealing conditions, instead of synthesizing a series of block copolymers of various molecular weights and compositions.

  9. Preparation and Characterization of Nano-Structured SiO2 Thin Films on Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    Rong Chun XIONG; Dong Zhou YAN; Gang WEI

    2003-01-01

    Nano-structured SiO2 thin films were prepared on the surface of carbon steel for the first time by LPD. The compositions of the films were analyzed by XPS, and the surface morphology of the thin films were observed by AFM. The thin films were constituted by compact particles of SiO2, and there was no Fe in the films. In the process of film forming, the SiO2 colloid particles were deposited or absorbed directly onto the surface of carbon steel substrates that were activated by acid solution containing inhibitor, and corrosion of the substrates was avoided. The nano-structured SiO2 thin films that were prepared had excellent protective efficiency to the carbon steel.

  10. Amorphous carbon nitride as an alternative electrode material in electroanalysis: Simultaneous determination of dopamine and ascorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, Roberta A., E-mail: roantigo@hotmail.com [Departamento de Química, Universidade Federal de São Carlos, C.P. 676, 13560-970 São Carlos, SP (Brazil); Matos, Roberto [Departamento de Química, Universidade Federal de São Carlos, C.P. 676, 13560-970 São Carlos, SP (Brazil); Benchikh, Abdelkader [LECVE, Faculté de la Technologie, Département de Génie des Procédés, Université Abderrahmane MIRA, Béjaïa (Algeria); LISE UPR 15 du CNRS, Université Pierre et Marie Curie, 4, Place Jussieu, 75005 Paris (France); Saidani, Boualem [LECVE, Faculté de la Technologie, Département de Génie des Procédés, Université Abderrahmane MIRA, Béjaïa (Algeria); Debiemme-Chouvy, Catherine [LISE UPR 15 du CNRS, Université Pierre et Marie Curie, 4, Place Jussieu, 75005 Paris (France); Deslouis, Claude, E-mail: claude.deslouis@upmc.fr [LISE UPR 15 du CNRS, Université Pierre et Marie Curie, 4, Place Jussieu, 75005 Paris (France); Rocha-Filho, Romeu C.; Fatibello-Filho, Orlando [Departamento de Química, Universidade Federal de São Carlos, C.P. 676, 13560-970 São Carlos, SP (Brazil)

    2013-10-03

    Graphical abstract: -- Highlights: •a-CN{sub x} films are a new class of electrodic carbon materials that present several properties similar to those of BDD films. •a-CN{sub x} and BDD were used as working electrodes for simultaneous determination of DA and AA. •Electrochemical pretreatments on a-CN{sub x} or BDD modified the nature of the surface terminations. •An anodic pretreatment in 0.1 mol L{sup −1} KOH was necessary to attain an adequate separation of the DA and AA oxidation potential peaks. •For the first time in the literature, the use of an a-CN{sub x} electrode in a complete electroanalytical procedure is reported. -- Abstract: Boron-doped diamond (BDD) films are excellent electrode materials, whose electrochemical activity for some analytes can be tuned by controlling their surface termination, most commonly either to predominantly hydrogen or oxygen. This tuning can be accomplished by e.g. suitable cathodic or anodic electrochemical pretreatments. Recently, it has been shown that amorphous carbon nitride (a-CN{sub x}) films may present electrochemical characteristics similar to those of BDD, including the influence of surface termination on their electrochemical activity toward some analytes. In this work, we report for the first time a complete electroanalytical method using an a-CN{sub x} electrode. Thus, an a-CN{sub x} film deposited on a stainless steel foil by DC magnetron sputtering is proposed as an alternative electrode for the simultaneous determination of dopamine (DA) and ascorbic acid (AA) in synthetic biological samples by square-wave voltammetry. The obtained results are compared with those attained using a BDD electrode. For both electrodes, a same anodic pretreatment in 0.1 mol L{sup −1} KOH was necessary to attain an adequate and equivalent separation of the DA and AA oxidation potential peaks of about 330 mV. The detection limits obtained for the simultaneous determination of these analytes using the a-CN{sub x

  11. Improvements of stress controllability and radiation resistance by adding carbon to boron-nitride

    Energy Technology Data Exchange (ETDEWEB)

    Nakaishi, M.; Sugishima, K. (Fujitsu Limited, Advanced Technology Div., Nakahara-ku, Kawasaki 211 (JP)); Yamada, M. (Stanford Electronics Lab., Stanford Univ., Stanford, CA (US))

    1990-07-01

    The addition of an atom having different bonding radii to a matrix film is an effective method for changing the stress of the film. In a plasma-enhanced CVD of BN, it is difficult to obtain tensile stress except for extremely boron-rich films. The controllability of tensile stress in BN film was improved by introducing a small amount of carbon into the BN matrix, using plasma-enhanced CVD between 400{degrees} and 500{degrees}C. The authors have obtained transparent films with high Young's modulus and tensile stress. They report that the radiation resistance of BNC deposited at 400{degrees}C was improved five times better than that of BN deposited by low-pressure CVD at similar temperatures.

  12. Remarkable enhancement of the electrical conductivity of carbon nanostructured thin films after compression.

    Science.gov (United States)

    Georgakilas, Vasilios; Koutsioukis, Apostolos; Petr, Martin; Tucek, Jiri; Zboril, Radek

    2016-06-01

    In this work, we demonstrate a significant improvement in the electrical conductivity of carbon nanostructured thin films, composed of graphene nanosheets and multiwalled carbon nanotubes, by compression/polishing. It is shown that the sheet resistance of compressed thin films of carbon nanostructures and hybrids is remarkably decreased in comparison with that of as-deposited films. The number of the interconnections, the distance between the nanostructures as well as their orientation are highly altered by the compression favoring the electrical conductivity of the compressed samples.

  13. Silicon nitride and intrinsic amorphous silicon double antireflection coatings for thin-film solar cells on foreign substrates

    Energy Technology Data Exchange (ETDEWEB)

    Li, Da; Kunz, Thomas [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Photovoltaics and Thermosensoric, Haberstr. 2a, 91058 Erlangen (Germany); Wolf, Nadine [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Energy Efficiency, Am Galgenberg 87, 97074 Wuerzburg (Germany); Liebig, Jan Philipp [Materials Science and Engineering, Institute I, University of Erlangen-Nuremberg, Martensstr. 5, 91058 Erlangen (Germany); Wittmann, Stephan; Ahmad, Taimoor; Hessmann, Maik T.; Auer, Richard [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Photovoltaics and Thermosensoric, Haberstr. 2a, 91058 Erlangen (Germany); Göken, Mathias [Materials Science and Engineering, Institute I, University of Erlangen-Nuremberg, Martensstr. 5, 91058 Erlangen (Germany); Brabec, Christoph J. [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Photovoltaics and Thermosensoric, Haberstr. 2a, 91058 Erlangen (Germany); Institute of Materials for Electronics and Energy Technology, University of Erlangen-Nuremberg, Martensstr. 7, 91058 Erlangen (Germany)

    2015-05-29

    Hydrogenated intrinsic amorphous silicon (a-Si:H) was investigated as a surface passivation method for crystalline silicon thin film solar cells on graphite substrates. The results of the experiments, including quantum efficiency and current density-voltage measurements, show improvements in cell performance. This improvement is due to surface passivation by an a-Si:H(i) layer, which increases the open circuit voltage and the fill factor. In comparison with our previous work, we have achieved an increase of 0.6% absolute cell efficiency for a 40 μm thick 4 cm{sup 2} aperture area on the graphite substrate. The optical properties of the SiN{sub x}/a-Si:H(i) stack were studied using spectroscopic ellipsometer techniques. Scanning transmission electron microscopy inside a scanning electron microscope was applied to characterize the cross section of the SiN{sub x}/a-Si:H(i) stack using focus ion beam preparation. - Highlights: • We report a 10.8% efficiency for thin-film silicon solar cell on graphite. • Hydrogenated intrinsic amorphous silicon was applied for surface passivation. • SiN{sub x}/a-Si:H(i) stacks were characterized by spectroscopic ellipsometer techniques. • Cross-section micrograph was obtained by scanning transmission electron microscopy. • Quantum efficiency and J-V measurements show improvements in the cell performance.

  14. Enhanced current transport and injection in thin-film gallium-nitride light-emitting diodes by laser-based doping.

    Science.gov (United States)

    Kim, Su Jin; Kim, Kyeong Heon; Chung, Ho Young; Shin, Hee Woong; Lee, Byeong Ryong; Jeong, Tak; Park, Hyung Jo; Kim, Tae Geun

    2014-10-08

    This paper reports improvements in the electrical and optical properties of blue-emission gallium nitride (GaN)-based thin-film light-emitting diodes (TFLEDs) after laser-based Si doping (LBSD) of a nitrogen-face n-GaN (denoted as hereafter n-GaN) layer. Experimental results show that the light-output powers of the flat- and rough-surface TFLEDs after LBSD are 52.1 and 11.35% higher than those before LBSD, respectively, at a current of 350 mA, while the corresponding operating voltages are decreased by 0.22 and 0.28 V for the flat- and rough-surface TFLEDs after LBSD, respectively. The reduced operating voltage after LBSD of the top n-GaN layer may result from the remarkably decreased specific contact resistance at the metal/n-GaN interface and the low series resistance of the TFLED device. The LBSD of n-GaN increases the number of nitrogen vacancies, and Si substitutes for Ga (SiGa) at the metal/n-GaN interface to produce highly Si-doped regions in n-GaN, leading to a decrease in the Schottky barrier height and width. As a result, the specific contact resistances are significantly decreased to 1.56 × 10(-5) and 2.86 × 10(-5) Ω cm(2) for the flat- and rough-surface samples after LBSD, respectively. On the other hand, the increased light-output power after LBSD can be explained by the uniform current spreading, efficient current injection, and enhanced light scattering resulting from the low contact resistivity, low lateral current resistance, and additional textured surface, respectively. Furthermore, LBSD did not degrade the electrical properties of the TFLEDs owing to low reverse leakage currents. The results indicate that our approach could potentially enable high-efficiency and high-power capabilities for optoelectronic devices.

  15. MoS2-coated microspheres of self-sensitized carbon nitride for efficient photocatalytic hydrogen generation under visible light irradiation

    Science.gov (United States)

    Gu, Quan; Sun, Huaming; Xie, Zunyuan; Gao, Ziwei; Xue, Can

    2017-02-01

    We have successfully coated the self-sensitized carbon nitride (SSCN) microspheres with a layer of MoS2 through a facile one-pot hydrothermal method by using (NH4)2MoS4 as the precursor. The resulted MoS2-coated SSCN photocatalyst appears as a core-shell structure and exhibits enhanced visible-light activities for photocatalytic H2 generation as compared to the un-coated SSCN and the standard g-C3N4 reference with MoS2 coating. The photocatalytic test results suggest that the oligomeric s-triazine dyes on the SSCN surface can provide additional light-harvesting capability and photogenerated charge carriers, and the coated MoS2 layer can serve as active sites for proton reduction towards H2 evolution. This synergistic effect of surface triazine dyes and MoS2 coating greatly promotes the activity of carbon nitride microspheres for vishible-light-driven H2 generation. This work provides a new way of future development of low-cost noble-metal-free photocatalysts for efficient solar-driven hydrogen production.

  16. Carbon Nitride-Aromatic Diimide-Graphene Nanohybrids: Metal-Free Photocatalysts for Solar-to-Hydrogen Peroxide Energy Conversion with 0.2% Efficiency.

    Science.gov (United States)

    Kofuji, Yusuke; Isobe, Yuki; Shiraishi, Yasuhiro; Sakamoto, Hirokatsu; Tanaka, Shunsuke; Ichikawa, Satoshi; Hirai, Takayuki

    2016-08-10

    Solar-to-chemical energy conversion is a challenging subject for renewable energy storage. In the past 40 years, overall water splitting into H2 and O2 by semiconductor photocatalysis has been studied extensively; however, they need noble metals and extreme care to avoid explosion of the mixed gases. Here we report that generating hydrogen peroxide (H2O2) from water and O2 by organic semiconductor photocatalysts could provide a new basis for clean energy storage without metal and explosion risk. We found that carbon nitride-aromatic diimide-graphene nanohybrids prepared by simple hydrothermal-calcination procedure produce H2O2 from pure water and O2 under visible light (λ > 420 nm). Photoexcitation of the semiconducting carbon nitride-aromatic diimide moiety transfers their conduction band electrons to graphene and enhances charge separation. The valence band holes on the semiconducting moiety oxidize water, while the electrons on the graphene moiety promote selective two-electron reduction of O2. This metal-free system produces H2O2 with solar-to-chemical energy conversion efficiency 0.20%, comparable to the highest levels achieved by powdered water-splitting photocatalysts.

  17. Low-Pt loaded on a vanadium nitride/graphitic carbon composite as an efficient electrocatalyst for the oxygen reduction reaction.

    Science.gov (United States)

    Yin, Jie; Wang, Lei; Tian, Chungui; Tan, Taixing; Mu, Guang; Zhao, Lu; Fu, Honggang

    2013-10-04

    The high cost of platinum electrocatalysts for the oxygen reduction reaction (ORR) has hindered the commercialization of fuel cells. An effective support can reduce the usage of Pt and improve the reactivity of Pt through synergistic effects. Herein, the vanadium nitride/graphitic carbon (VN/GC) nanocomposites, which act as an enhanced carrier of Pt nanoparticles (NPs) towards ORR, have been synthesized for the first time. In the synthesis, the VN/GC composite could be obtained by introducing VO3 (-) and [Fe(CN)6 ](4-) ions into the polyacrylic weak-acid anion-exchanged resin (PWAR) through an in-situ anion-exchanged route, followed by carbonization and a subsequent nitridation process. After loading only 10 % Pt NPs, the resulting Pt-VN/GC catalyst demonstrates a more positive onset potential (1.01 V), higher mass activity (137.2 mA mg(-1) ), and better cyclic stability (99 % electrochemical active surface area (ECSA) retention after 2000 cycles) towards ORR than the commercial 20 % Pt/C. Importantly, the Pt-VN/GC catalyst mainly exhibits a 4 e(-) -transfer mechanism and a low yield of peroxide species, suggesting its potential application as a low-cost and highly efficient ORR catalyst in fuel cells.

  18. Modelling of the layer evolution during nitriding processes

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, U.; Oseguera, J.; Schabes, P. [CEM, Atizapan (Mexico)

    1995-12-31

    The evolution of concomitant layers of nitrides is presented. The layer formation is experimentally achieved through two processes: Nitriding with a weakly ionized plasma and nitrogen post-discharge nitriding. The nitriding processes were performed on samples of pure iron and carbon steel. Nitriding temperatures were close but different from the eutectoid transformation point temperature. The experimental layer growth pattern is compared with a model of mass transfer, in which interface mass balance is considered. In the model the authors have considered the formation of one and two compact nitride layers. For short time of treatment, it is shown that a parabolic profile does not satisfactorily describe the layer growth.

  19. Facile synthesis of graphitic carbon nitride/nanostructured α-Fe2O3 composites and their excellent electrochemical performance for supercapacitor and enzyme-free glucose detection applications

    Science.gov (United States)

    Liu, Lin; Wang, Jinxiang; Wang, Chengyin; Wang, Guoxiu

    2016-12-01

    The graphitic carbon nitride (g-C3N4)/iron oxide (α-Fe2O3) composites have been prepared by a one-step pyrolysis of Prussian blue (PB) and melamine. The Fe2O3 nanoparticles derived from PB effectively protect the thin layers of g-C3N4 from restacking and expanding. The as-prepared g-C3N4/α-Fe2O3 composites exhibit a large specific surface area, and demonstrate their excellent electrochemical performance in the supercapacitor and non-enzymatic detection of glucose. The g-C3N4/α-Fe2O3 composites facilitate the faster faradic reaction in 1.0 M KOH electrolyte, and deliver the highest specific capacitance (580 F g-1) at the current density of 1.0 A g-1. The resultant composites also show an excellent long cycle life (up to 1000 cycles) at the current density of 2 A g-1. In addition, the modified electrode based on the g-C3N4/α-Fe2O3 hybrids are also used for the non-enzymatic detection of glucose. The as-fabricated modified electrode exhibits good electrochemical performance towards the oxidation of glucose with a response time devices and sensors.

  20. Two-electron reductive carbonylation of terminal uranium(V) and uranium(VI) nitrides to cyanate by carbon monoxide.

    Science.gov (United States)

    Cleaves, Peter A; King, David M; Kefalidis, Christos E; Maron, Laurent; Tuna, Floriana; McInnes, Eric J L; McMaster, Jonathan; Lewis, William; Blake, Alexander J; Liddle, Stephen T

    2014-09-22

    Two-electron reductive carbonylation of the uranium(VI) nitride [U(Tren(TIPS))(N)] (2, Tren(TIPS)=N(CH2CH2NSiiPr3)3) with CO gave the uranium(IV) cyanate [U(Tren(TIPS))(NCO)] (3). KC8 reduction of 3 resulted in cyanate dissociation to give [U(Tren(TIPS))] (4) and KNCO, or cyanate retention in [U(Tren(TIPS))(NCO)][K(B15C5)2] (5, B15C5=benzo-15-crown-5 ether) with B15C5. Complexes 5 and 4 and KNCO were also prepared from CO and the uranium(V) nitride [{U(Tren(TIPS))(N)K}2] (6), with or without B15C5, respectively. Complex 5 can be prepared directly from CO and [U(Tren(TIPS))(N)][K(B15C5)2] (7). Notably, 7 reacts with CO much faster than 2. This unprecedented f-block reactivity was modeled theoretically, revealing nucleophilic attack of the π* orbital of CO by the nitride with activation energy barriers of 24.7 and 11.3 kcal mol(-1) for uranium(VI) and uranium(V), respectively. A remarkably simple two-step, two-electron cycle for the conversion of azide to nitride to cyanate using 4, NaN3 and CO is presented.

  1. Microstructure and strengthening parameters of ultra-thin hot strip of low carbon steel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The microstructure and precipitation mechanism of ultra-thinhot strip produced by CSP technology were analyzed by electron back scattered diffraction (EBSD), H-800 transmission electron microscope (TEM) and thermodynamics theory. The EBSD results show that the finishing hot rolling microstructures are mixture of recrystallized and deformed austenite. After phase transformation, ferrite grains embody substructures and dislocations that led ultra-thin hot strip high strength and relatively low elongation rate. TEM observations show that there are a lot of fine and dispersive precipitates in microstructures. Most of aluminium nitrides are in grains, while coexisted precipitates of MnS along grain boundaries. Coexisted precipitates compose cation-vacancy type oxides such as Al2O3 in the core , while MnS at the fringe of surface. At the same time, reasons for microstructure refinement and strengthening effect were investigated.

  2. Complexes of carbon nanotubes with oligonucleotides in thin Langmuir-Blodgett films to detect electrochemically hybridization

    Science.gov (United States)

    Egorov, A. S.; Egorova, V. P.; Krylova, H. V.; Lipnevich, I. V.; Orekhovskaya, T. I.; Veligura, A. A.; Govorov, M. I.; Shulitsky, B. G.

    2014-10-01

    Self-assembled complexes consisting of thin multi-walled carbon nanotubes (MWCNTs) and DNA-oligonucleotides which are able to a cooperative binding to complementary oligonucleotides have been investigated. It was establised a high-performance charge transport in nanostructured Langmuir-Blodgett complexes thin MWCNTs/DNA. A method to electrochemically detect DNA hybridization on the self-organized structures has been proposed.

  3. Electron Damage Effects on Carbon Nanotube Thin Films

    Science.gov (United States)

    2013-03-01

    antennas surrounding the acceleration column, and the banks of diodes under the RF antennas... diode banks. The tank is filled with SF6 at a pressure of 95 psi to minimize arcing in the accelerator...the diamond structure, graphite or graphene , and more recently the carbon nanotube and Buckyballs shown in Figure 2. Each of these carbon arrangements

  4. Aligned carbon nanotube, graphene and graphite oxide thin films via substrate-directed rapid interfacial deposition.

    Science.gov (United States)

    D'Arcy, Julio M; Tran, Henry D; Stieg, Adam Z; Gimzewski, James K; Kaner, Richard B

    2012-05-21

    A procedure for depositing thin films of carbon nanostructures is described that overcomes the limitations typically associated with solution based methods. Transparent and conductively continuous carbon coatings can be grown on virtually any type of substrate within seconds. Interfacial surface tension gradients result in directional fluid flow and film spreading at the water/oil interface. Transparent films of carbon nanostructures are produced including aligned ropes of single-walled carbon nanotubes and assemblies of single sheets of chemically converted graphene and graphite oxide. Process scale-up, layer-by-layer deposition, and a simple method for coating non-activated hydrophobic surfaces are demonstrated.

  5. Multi-Walled Carbon Nanotube-Doped Tungsten Oxide Thin Films for Hydrogen Gas Sensing

    OpenAIRE

    2010-01-01

    In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT)-doped tungsten oxide (WO3) thin films by means of the powder mixing and electron beam (E-beam) evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO3 thin film exhibits high sensitivity and selectivity ...

  6. Optimum design of the carbon fiber thin-walled baffle for the space-based camera

    Science.gov (United States)

    Yan, Yong; Song, Gu; Yuan, An; Jin, Guang

    2011-08-01

    The thin-walled baffle design of the space-based camera is an important job in the lightweight space camera research task for its stringent quality requirement and harsh mechanical environment especially for the thin-walled baffle of the carbon fiber design. In the paper, an especially thin-walled baffle of the carbon fiber design process was described and it is sound significant during the other thin-walled baffle design of the space camera. The designer obtained the design margin of the thin-walled baffle that structural stiffness and strength can tolerated belong to its development requirements through the appropriate use of the finite element analysis of the walled parameters influence sensitivity to its structural stiffness and strength. And the designer can determine the better optimization criterion of thin-walled baffle during the geometric parameter optimization process in such guiding principle. It sounds significant during the optimum design of the thin-walled baffle of the space camera. For structural stiffness and strength of the carbon fibers structure which can been designed, the effect of the optimization will be more remarkable though the optional design of the parameters chose. Combination of manufacture process and design requirements the paper completed the thin-walled baffle structure scheme selection and optimized the specific carbon fiber fabrication technology though the FEM optimization, and the processing cost and process cycle are retrenchment/saved effectively in the method. Meanwhile, the weight of the thin-walled baffle reduced significantly in meet the design requirements under the premise of the structure. The engineering prediction had been adopted, and the related result shows that the thin-walled baffle satisfied the space-based camera engineering practical needs very well, its quality reduced about 20%, the final assessment index of the thin-walled baffle were superior to the overall design requirements significantly. The design

  7. Organic nanodielectrics for low voltage carbon nanotube thin film transistors and complementary logic gates.

    Science.gov (United States)

    Hur, Seung-Hyun; Yoon, Myung-Han; Gaur, Anshu; Shim, Moonsub; Facchetti, Antonio; Marks, Tobin J; Rogers, John A

    2005-10-12

    We report the implementation of three dimensionally cross-linked, organic nanodielectric multilayers as ultrathin gate dielectrics for a type of thin film transistor device that uses networks of single-walled carbon nanotubes as effective semiconductor thin films. Unipolar n- and p-channel devices are demonstrated by use of polymer coatings to control the behavior of the networks. Monolithically integrating these devices yields complementary logic gates. The organic multilayers provide exceptionally good gate dielectrics for these systems and allow for low voltage, low hysteresis operation. The excellent performance characteristics suggest that organic dielectrics of this general type could provide a promising path to SWNT-based thin film electronics.

  8. Methods of making non-covalently bonded carbon-titania nanocomposite thin films and applications of the same

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Yu Teng; Vijayan, Baiju K.; Gray, Kimberly A.; Hersam, Mark C.

    2016-07-19

    In one aspect, a method of making non-covalently bonded carbon-titania nanocomposite thin films includes: forming a carbon-based ink; forming a titania (TiO.sub.2) solution; blade-coating a mechanical mixture of the carbon-based ink and the titania solution onto a substrate; and annealing the blade-coated substrate at a first temperature for a first period of time to obtain the carbon-based titania nanocomposite thin films. In certain embodiments, the carbon-based titania nanocomposite thin films may include solvent-exfoliated graphene titania (SEG-TiO.sub.2) nanocomposite thin films, or single walled carbon nanotube titania (SWCNT-TiO.sub.2) nanocomposite thin films.

  9. Evanescent field phase shifting in a silicon nitride waveguide using a coupled silicon slab

    DEFF Research Database (Denmark)

    Jensen, Asger Sellerup; Oxenløwe, Leif Katsuo; Green, William M. J.

    2015-01-01

    An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration.......An approach for electrical modulation of low-loss silicon nitride waveguides is proposed, using a silicon nitride waveguide evanescently loaded with a thin silicon slab. The thermooptic phase-shift characteristics are investigated in a racetrack resonator configuration....

  10. Carbon nanotube network thin-film transistors on flexible/stretchable substrates

    Energy Technology Data Exchange (ETDEWEB)

    Takei, Kuniharu; Takahashi, Toshitake; Javey, Ali

    2016-03-29

    This disclosure provides systems, methods, and apparatus for flexible thin-film transistors. In one aspect, a device includes a polymer substrate, a gate electrode disposed on the polymer substrate, a dielectric layer disposed on the gate electrode and on exposed portions of the polymer substrate, a carbon nanotube network disposed on the dielectric layer, and a source electrode and a drain electrode disposed on the carbon nanotube network.

  11. Surface Energy in Nanocrystalline Carbon Thin Films: Effect of Size Dependence and Atmospheric Exposure.

    Science.gov (United States)

    Kumar, Manish; Javid, Amjed; Han, Jeon Geon

    2017-03-14

    Surface energy (SE) is the most sensitive and fundamental parameter for governing the interfacial interactions in nanoscale carbon materials. However, on account of the complexities involved of hybridization states and surface bonds, achieved SE values are often less in comparison with their theoretical counterparts and strongly influenced by stability aspects. Here, an advanced facing-target pulsed dc unbalanced magnetron-sputtering process is presented for the synthesis of undoped and H/N-doped nanocrystalline carbon thin films. The time-dependent surface properties of the undoped and H/N-doped nanocrystalline carbon thin films are systematically studied. The advanced plasma process induced the dominant deposition of high-energy neutral carbon species, consequently controlling the intercolumnar spacing of nanodomain morphology and surface anisotropy of electron density. As a result, significantly higher SE values (maximum = 79.24 mJ/m(2)) are achieved, with a possible window of 79.24-66.5 mJ/m(2) by controlling the experimental conditions. The intrinsic (size effects and functionality) and extrinsic factors (atmospheric exposure) are resolved and explained on the basis of size-dependent cohesive energy model and long-range van der Waals interactions between hydrocarbon molecules and the carbon surface. The findings anticipate the enhanced functionality of nanocrystalline carbon thin films in terms of selectivity, sensitivity, and stability.

  12. Nano-structural Modification of Amorphous Carbon Thin Films by Low-energy Electron Beam Irradiation

    Institute of Scientific and Technical Information of China (English)

    EijiIwamura; MasanoriYamaguchi

    2004-01-01

    A new approach using a low-energy electron beam radiation system was investigated to synthesize carbon hybrid structures in amorphous carbon thin films. Two types of amorphous carbon films, which were 15at% iron containing film and with column/inter-column structures, were deposited onto Si substrates by a sputtering technique and subsequently exposed to an electron shower of which the energy and dose rate were much smaller compared to an intense electron beam used in a transmission electron microscopy. As a result of the low-energy and low-dose electron irradiation process, graphitic structures formed in amorphous matrix at a relatively low temperature up to 450 K. Hybrid carbon thin films containing onion-like structures in an amorphous carbon matrix were synthesized by dynamic structural modification of iron containing amorphous carbon thin films. It was found that the graphitization progressed more in the electron irradiation than in annealing at 773K, and it was attributed to thermal and catalytic effects which are strongly related to grain growth of metal clusters. On the other hand, a reversal of TEM image contrast was observed in a-C films with column/inter-column structures. It is presumed that preferable graphitization occurred in the inter-column regions induced by electron irradiation.

  13. Nano-structural Modification of Amorphous Carbon Thin Films by Low-energy Electron Beam Irradiation

    Institute of Scientific and Technical Information of China (English)

    Eiji Iwamura; Masanori Yamaguchi

    2004-01-01

    A new approach using a low-energy electron beam radiation system was investigated to synthesize carbon hybrid structures in amorphous carbon thin films. Two types of amorphous carbon films, which were 15at% iron containing film and with column/inter-column structures, were deposited onto Si substrates by a sputtering technique and subsequently exposed to an electron shower of which the energy and dose rate were much smaller compared to an intense electron beam used in a transmission electron microscopy. As a result of the low-energy and low-dose electron irradiation process,graphitic structures formed in amorphous matrix at a relatively low temperature up to 450 K. Hybrid carbon thin films containing onion-like structures in an amorphous carbon matrix were synthesized by dynamic structural modification of iron containing amorphous carbon thin films. It was found that the graphitization progressed more in the electron irradiation than in annealing at 773K, and it was attributed to thermal and catalytic effects which are strongly related to grain growth of metal clusters. On the other hand, a reversal of TEM image contrast was observed in a-C films with column/inter-column structures. It is presumed that preferable graphitization occurred in the inter-column regions induced by electron irradiation.

  14. Modification of rubber surface with hydrogenated diamond-like carbon thin films

    NARCIS (Netherlands)

    Pei, Y. T.; Bui, X. L.; De Hosson, J. Th. M.; Laudon, M; Romanowicz, B

    2009-01-01

    Thin films of hydrogenated diamond-like carbon (DLC) have been deposited on hydrogenated nitrile butadiene rubber (HNBR) for reduction of friction and enhancement of wear resistance of dynamic rubber seals, by sputtering graphite targets in C(2)H(2)/Ar plasma. The wax removal and pre-deposition plas

  15. Flexible diamond-like carbon thin film coated rubbers: fundamentals and applications

    NARCIS (Netherlands)

    Pei, Y.T.

    2015-01-01

    Dynamic rubber seals are major sources of friction of lubrication systems and bearings, which may take up to 75% of the total friction. The solution we present is to coat rubbers with diamond-like carbon (DLC) thin film, by which the coefficient of friction is reduced to less than one tenth. Coating

  16. Flexible diamond-like carbon thin film coated on rubbers: fundamentals and applications

    NARCIS (Netherlands)

    Pei, Yutao

    2015-01-01

    Dynamic rubber seals are the major source of friction in lubrication systems and bearings, which may take up to 70% of the total friction. Our solution is to coat rubbers with flexible diamond-like carbon (DLC) thin film by which the coefficient of friction is reduced from above 1.5 to below 0.15. C

  17. Influence of thin film nickel pretreatment on catalytic thermal chemical vapor deposition of carbon nanofibers

    NARCIS (Netherlands)

    Tiggelaar, R.M.; Thakur, D.B.; Nair, H.; Lefferts, L.; Seshan, K.; Gardeniers, J.G.E.

    2013-01-01

    Nickel and other metal nanoparticles are known to be active as catalysts in the synthesis of carbon nanofibers. In this paper we investigate how dewetting and break-up of nickel thin films depends on film thickness, film–substrate interaction and pretreatment conditions. This is evaluated for films

  18. Deposition and characterization of hydrogenated diamond-like carbon thin films on rubber seals

    NARCIS (Netherlands)

    Pei, Y.T.; Bui, X.L.; Hosson, J.Th.M. De

    2010-01-01

    Thin films of hydrogenated diamond-like carbon (DLC) have been deposited on hydrogenated nitrile butadiene rubber (HNBR) for reduction of friction and enhancement of wear resistance of dynamic rubber seals. The wax removal and pre-deposition plasma treatment of HNBR substrates are proven to be cruci

  19. Thin sulfonated poly(ether ether ketone) films for the dehydration of compressed carbon dioxide

    NARCIS (Netherlands)

    Koziara, B.T.

    2015-01-01

    In this thesis, the properties of thin films from highly sulfonated poly(ether ether ketone) (SPEEK) have been investigated within the context of their application as membranes for the dehydration of compressed carbon dioxide. Spectroscopic ellipsometry has been used as the predominant measurement t

  20. Low temperature silicon nitride by hot wire chemical vapour deposition for the use in impermeable thin film encapsulation on flexible substrates.

    Science.gov (United States)

    Spee, D A; van der Werf, C H M; Rath, J K; Schropp, R E I

    2011-09-01

    High quality non porous silicon nitride layers were deposited by hot wire chemical vapour deposition at substrate temperatures lower than 110 degrees C. The layer properties were investigated using FTIR, reflection/transmission measurements and 1:6 buffered HF etching rate. A Si-H peak position of 2180 cm(-1) in the Fourier transform infrared absorption spectrum indicates a N/Si ratio around 1.2. Together with a refractive index of 1.97 at a wavelength of 632 nm and an extinction coefficient of 0.002 at 400 nm, this suggests that a transparent high density silicon nitride material has been made below 110 degrees C, which is compatible with polymer films and is expected to have a high impermeability. To confirm the compatibility with polymer films a silicon nitride layer was deposited on poly(glycidyl methacrylate) made by initiated chemical vapour deposition, resulting in a highly transparent double layer.

  1. Cu2+ coordinated graphitic carbon nitride (Cu-g-C3N4) nanosheets from melamine for the liquid phase hydroxylation of benzene and VOCs

    Science.gov (United States)

    Muniandy, Lingeswarran; Adam, Farook; Mohamed, Abdul Rahman; Iqbal, Anwar; Rahman, Nur Ruzaina Abdul

    2017-03-01

    Copper modified graphitic carbon nitride nanosheets (Cu-g-C3N4) was synthesized and used in the hydroxylation of benzene under mild conditions with hydrogen peroxide as a "green" oxidant. The presence of copper ions (Cu2+) was confirmed from the XPS, EDX and also the hydrogen TPR analyses. The catalyst shows excellent activity, resulting in 74.1% conversion of benzene with phenol as the major product (97.5%) and only p-benzoquinone as the by-product. The catalyst's selectivity towards phenol did not exhibit significant change even after being reused for several cycles. The catalyst was also used for the oxidation of several other organic compounds with interesting results.

  2. Platinum containing amorphous hydrogenated carbon (a-C:H/Pt) thin films as selective solar absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Yung-Hsiang; Brahma, Sanjaya [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Tzeng, Y.H. [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Ting, Jyh-Ming, E-mail: jting@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan (China)

    2014-10-15

    We have investigated a double-cermet structured thin film in which an a-C:H thin film was used as an anti-reflective (AR) layer and two platinum-containing amorphous hydrogenated carbon (a-C:H/Pt) thin films were used as the double cermet layers. A reactive co-sputter deposition method was used to prepare both the anti-reflective and cermet layers. Effects of the target power and heat treatment were studied. The obtained films were characterized using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy. The optical absorptance and emittance of the as deposited and annealed films were determined using UV–vis-NIR spectroscopy. We show that the optical absorptance of the resulting double-cermet structured thin film is as high as 96% and remains to be 91% after heat treatment at 400 °C, indicating the thermal stability of the film.

  3. Solar-Driven Reduction of Aqueous Protons Coupled to Selective Alcohol Oxidation with a Carbon Nitride-Molecular Ni Catalyst System.

    Science.gov (United States)

    Kasap, Hatice; Caputo, Christine A; Martindale, Benjamin C M; Godin, Robert; Lau, Vincent Wing-Hei; Lotsch, Bettina V; Durrant, James R; Reisner, Erwin

    2016-07-27

    Solar water-splitting represents an important strategy toward production of the storable and renewable fuel hydrogen. The water oxidation half-reaction typically proceeds with poor efficiency and produces the unprofitable and often damaging product, O2. Herein, we demonstrate an alternative approach and couple solar H2 generation with value-added organic substrate oxidation. Solar irradiation of a cyanamide surface-functionalized melon-type carbon nitride ((NCN)CNx) and a molecular nickel(II) bis(diphosphine) H2-evolution catalyst (NiP) enabled the production of H2 with concomitant selective oxidation of benzylic alcohols to aldehydes in high yield under purely aqueous conditions, at room temperature and ambient pressure. This one-pot system maintained its activity over 24 h, generating products in 1:1 stoichiometry, separated in the gas and solution phases. The (NCN)CNx-NiP system showed an activity of 763 μmol (g CNx)(-1) h(-1) toward H2 and aldehyde production, a Ni-based turnover frequency of 76 h(-1), and an external quantum efficiency of 15% (λ = 360 ± 10 nm). This precious metal-free and nontoxic photocatalytic system displays better performance than an analogous system containing platinum instead of NiP. Transient absorption spectroscopy revealed that the photoactivity of (NCN)CNx is due to efficient substrate oxidation of the material, which outweighs possible charge recombination compared to the nonfunctionalized melon-type carbon nitride. Photoexcited (NCN)CNx in the presence of an organic substrate can accumulate ultralong-lived "trapped electrons", which allow for fuel generation in the dark. The artificial photosynthetic system thereby catalyzes a closed redox cycle showing 100% atom economy and generates two value-added products, a solar chemical, and solar fuel.

  4. Fabrication of periodical surface structures by picosecond laser irradiation of carbon thin films: transformation of amorphous carbon in nanographite

    Science.gov (United States)

    Popescu, C.; Dorcioman, G.; Bita, B.; Besleaga, C.; Zgura, I.; Himcinschi, C.; Popescu, A. C.

    2016-12-01

    Thin films of carbon were synthesized by ns pulsed laser deposition in vacuum on silicon substrates, starting from graphite targets. Further on, the films were irradiated with a picosecond laser source emitting in visible at 532 nm. After tuning of laser parameters, we obtained a film surface covered by laser induced periodical surface structures (LIPSS). They were investigated by optical, scanning electron and atomic force microscopy. It was observed that changing the irradiation angle influences the LIPSS covered area. At high magnification it was revealed that the LIPSS pattern was quite complex, being composed of other small LIPSS islands, interconnected by bridges of nanoparticles. Raman spectra for the non-irradiated carbon films were typical for a-C type of diamond-like carbon, while the LIPSS spectra were characteristic to nano-graphite. The pristine carbon film was hydrophilic, while the LIPSS covered film surface was hydrophobic.

  5. Implementation of Carbon Thin Film Coatings in the Super Proton Synchrotron (SPS) for Electron Cloud Mitigation

    CERN Document Server

    Costa Pinto, P; Basso, T; Edwards, P; Mensi, M; Sublet, A; Taborelli, M

    2014-01-01

    Low Secondary Electron Yield (SEY) carbon thin films eradicate electron multipacting in accelerator beam pipes. Two magnetic cells of the SPS were coated with such material and installed. In total more than forty vacuum vessels and magnet interconnections were treated. The feasibility of the coating process was validated. The performance of the carbon thin film will be tested with LHC nominal beams after the end of the long shutdown 1. Particular attention will be drawn to the long term behaviour. This paper presents the sputtering techniques used to coat the different components; their characterization (SEY measurements on coupons, RF multipacting tests and pump down curves); and the technology to etch the carbon film in case of a faulty coating. The strategy to coat the entire SPS will also be described.

  6. Low Temperature Silicon Nitride by Hot Wire Chemical Vapour Deposition for the Use in Impermeable Thin Film Encapsulation on Flexible Substrates

    NARCIS (Netherlands)

    Spee, D.A.; van der Werf, C.H.M.; Rath, J.K.; Schropp, R.E.I.

    2011-01-01

    High quality non porous silicon nitride layers were deposited by hot wire chemical vapour deposition at substrate temperatures lower than 110 C. The layer properties were investigated using FTIR, reflection/transmission measurements and 1:6 buffered HF etching rate. A Si–H peak position of 2180 cm−1

  7. Passive wireless strain and pH sensing using carbon nanotube-gold nanocomposite thin films

    Science.gov (United States)

    Loh, Kenneth J.; Lynch, Jerome P.; Kotov, Nicholas A.

    2007-04-01

    The recent development of wireless sensors for structural health monitoring has revealed their strong dependency on portable, limited battery supplies. Unlike current wireless sensors, passive radio frequency identification (RFID) systems based on inductive coupling can wirelessly receive power from a portable reader while transmitting collected data back. In this paper, preliminary results of a novel inductively coupled strain and corrosion sensor based upon material fabrication techniques from the nanotechnology field are presented. By varying polyelectrolyte species during a layer-by-layer fabrication process, carbon nanotube-polyelectrolyte multilayer thin film sensors sensitive to different mechanical (e.g. strain) and chemical (e.g. pH) stimuli can be produced. Validation studies conducted with different carbon nanotube thin films designed as either strain or pH sensors reveal high sensitivity and linear performance. When coupled with a copper inductive coil antenna, resulting RFID-based sensors exhibit wirelessly readable changes in resonant frequency and bandwidth. Furthermore, a carbon nanotube-gold nanocomposite thin film is fabricated and patterned into a highly conductive coil structure to realize a novel thin film inductive antenna. Preliminary results indicate that nanotube-gold nanocomposites exhibit resonance conditions, holding great promise for future RFID applications.

  8. Mechanical properties and interfacial characteristics of carbon-nanotube-reinforced epoxy thin films

    Science.gov (United States)

    Xu, Xiaojing; Thwe, Moe Moe; Shearwood, Christopher; Liao, Kin

    2002-10-01

    Multiwalled carbon nanotubes (MWNT) reinforced epoxy composite thin films were prepared by a microfabrication process and their elastic modulus was determined using a shaft-loaded blister test and linear and nonlinear elasticity models. Compared to net resin thin films, a 20% increase in elastic modulus was seen when 0.1 wt % MWNTs were added, suggesting MWNT alignment by spin coating. Electron microscopic observations of the fracture surfaces suggested high interfacial shear stress between MWNTs and the epoxy matrix, a result supported by both molecular mechanics simulation and micromechanics calculations.

  9. Eroding forest carbon sinks following thinning for combined fire prevention and bioenergy production

    Science.gov (United States)

    Hudiburg, T. W.; Law, B. E.; Luyssaert, S.

    2010-12-01

    Temperate forest annual net uptake of CO2 from the atmosphere is equivalent to ~16% of the annual fossil fuel emissions in the United States. Mitigation strategies to reduce emissions of carbon dioxide have lead to investigation of alternative sources of energy including forest biomass. The prospect of forest derived bioenergy has led to implementation of new forest management strategies based on the assumption that they will reduce total CO2 emissions to the atmosphere by simultaneously reducing the risk of wildfire and substituting for fossil fuels. Using Forest Inventory Analysis (FIA) plot data, regional supplemental plot data, and remote sensing products we determined the carbon stocks and fluxes of West Coast forests under current and proposed management scenarios for a 20 year treatment period. Varying biofuels thinning treatments designed to meet multiple objectives emphasizing fire prevention, economic gain, or energy production were applied to determine the resulting net carbon balance and bioenergy potential. Contrary to the management objectives, we find that increased removals result in substantial decreases in forest carbon stocks and Net Biome Production (NBP) and increased emissions. Thinning forests for energy production is not carbon neutral. Emissions are estimated to increase over the 20-year period because preventive thinning removals exceed the CO2 that would have been emitted due to wildfires, fossil fuel inputs are required for harvest and manufacturing, and use of woody biomass in short-lived products emits large quantities of CO2 to the atmosphere. It has the net effect of releasing otherwise sequestered carbon to the atmosphere, which may effectively reduce ongoing carbon uptake by forests and as a result, increase net greenhouse gas emissions, undermining the objective of greenhouse gas reductions over the next several decades.

  10. Tribological properties of boron nitride synthesized by ion beam deposition

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.; Spalvins, T.

    1985-01-01

    The adhesion and friction behavior of boron nitride films on 440 C bearing stainless steel substrates was examined. The thin films containing the boron nitride were synthesized using an ion beam extracted from a borazine plasma. Sliding friction experiments were conducted with BN in sliding contact with itself and various transition metals. It is indicated that the surfaces of atomically cleaned BN coating film contain a small amount of oxides and carbides, in addition to boron nitride. The coefficients of friction for the BN in contact with metals are related to the relative chemical activity of the metals. The more active the metal, the higher is the coefficient of friction. The adsorption of oxygen on clean metal and BN increases the shear strength of the metal - BN contact and increases the friction. The friction for BN-BN contact is a function of the shear strength of the elastic contacts. Clean BN surfaces exhibit relatively strong interfacial adhesion and high friction. The presence of adsorbates such as adventitious carbon contaminants on the BN surfaces reduces the shear strength of the contact area. In contrast, chemically adsorbed oxygen enhances the shear strength of the BN-BN contact and increases the friction.

  11. Nanostructured silicon carbon thin films grown by plasma enhanced chemical vapour deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Coscia, U. [Dipartimento di Fisica, Università di Napoli “Federico II” Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); CNISM Unita' di Napoli, Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); Ambrosone, G., E-mail: ambrosone@na.infn.it [Dipartimento di Fisica, Università di Napoli “Federico II” Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); SPIN-CNR, Complesso Universitario MSA, via Cinthia, 80126 Napoli (Italy); Basa, D.K. [Department of Physics, Utkal University, Bhubaneswar 751004 (India); Rigato, V. [INFN Laboratori Nazionali Legnaro, 35020 Legnaro (Padova) (Italy); Ferrero, S.; Virga, A. [Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino, C.so Duca degli Abruzzi 24, 10129 Torino (Italy)

    2013-09-30

    Nanostructured silicon carbon thin films, composed of Si nanocrystallites embedded in hydrogenated amorphous silicon carbon matrix, have been prepared by varying rf power in ultra high vacuum plasma enhanced chemical vapour deposition system using silane and methane gas mixtures diluted in hydrogen. In this paper we have studied the compositional, structural and electrical properties of these films as a function of rf power. It is shown that with increasing rf power the atomic densities of carbon and hydrogen increase while the atomic density of silicon decreases, resulting in a reduction in the mass density. Further, it is demonstrated that carbon is incorporated into amorphous matrix and it is mainly bonded to silicon. The study has also revealed that the crystalline volume fraction decreases with increase in rf power and that the films deposited with low rf power have a size distribution of large and small crystallites while the films deposited with relatively high power have only small crystallites. Finally, the enhanced transport properties of the nanostructured silicon carbon films, as compared to amorphous counterpart, have been attributed to the presence of Si nanocrystallites. - Highlights: • The mass density of silicon carbon films decreases from 2.3 to 2 g/cm{sup 3}. • Carbon is incorporated in the amorphous phase and it is mainly bonded to silicon. • Nanostructured silicon carbon films are deposited at rf power > 40 W. • Si nanocrystallites in amorphous silicon carbon enhance the electrical properties.

  12. Synthesis and characterization of boron incorporated diamond-like carbon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, L.L. [Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9 (Canada); Yang, Q., E-mail: qiaoqin.yang@usask.ca [Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9 (Canada); Tang, Y.; Yang, L.; Zhang, C. [Department of Mechanical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, SK S7N 5A9 (Canada); Hu, Y.; Cui, X. [Canadian Light Source Inc., 101 Perimeter Road, Saskatoon, SK S7N 0X4 (Canada)

    2015-08-31

    Boron incorporated diamond-like carbon (B-DLC) (up to 8 wt.% boron) thin films were synthesized on silicon wafers using biased target ion beam deposition technique, where diamond-like carbon (DLC) was deposited by ion beam deposition and boron (B) was simultaneously incorporated by biased target sputtering of a boron carbide (B{sub 4}C) target under different conditions. Pure DLC films and B–C films were also synthesized by ion beam deposition and biased target sputtering of B{sub 4}C under similar conditions, respectively, as reference samples. The microstructure and mechanical properties of the synthesized films have been characterized by various technologies. It has been found that B exists in different states in B-DLC, including carbon-rich and B-rich boron carbides, boron suboxide and boron oxide, and the oxidation of B probably occurs during the film deposition. The incorporation of B into DLC leads to the increase of sp{sup 3} bonded carbon in the films, the increase of both film hardness and elastic modulus, and the decrease of both surface roughness and friction coefficient. Furthermore, the content of sp{sup 3} bonded carbon, film hardness and elastic modulus increase, and the film surface roughness and friction coefficient decrease with the increase of B-rich carbide in the B-DLC films. - Highlights: • Biased target ion beam deposition technique is promising to produce high quality DLC based thin films; • Boron exists in different states in B-DLC thin films; • The incorporation of B to DLC with different levels leads to improved film properties; • The fraction of sp{sup 3} bonded C in B-DLC thin films increase with the increase of B-rich carbide content in the films.

  13. A laser ultrasound transducer using carbon nanofibers–polydimethylsiloxane composite thin film

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Bao-Yu; Kim, Jinwook; Li, Sibo; Jiang, Xiaoning, E-mail: xjiang5@ncsu.edu [Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Zhu, Jiadeng; Zhang, Xiangwu [Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2015-01-12

    The photoacoustic effect has been broadly applied to generate high frequency and broadband acoustic waves using lasers. However, the efficient conversion from laser energy to acoustic power is required to generate acoustic waves with high intensity acoustic pressure (>10 MPa). In this study, we demonstrated laser generated high intensity acoustic waves using carbon nanofibers–polydimethylsiloxane (CNFs-PDMS) thin films. The average diameter of the CNFs is 132.7 ± 11.2 nm. The thickness of the CNFs film and the CNFs-PDMS composite film is 24.4 ± 1.43 μm and 57.9 ± 2.80 μm, respectively. The maximum acoustic pressure is 12.15 ± 1.35 MPa using a 4.2 mJ, 532 nm Nd:YAG pulsed laser. The maximum acoustic pressure using the CNFs-PDMS composite was found to be 7.6-fold (17.62 dB) higher than using carbon black PDMS films. Furthermore, the calculated optoacoustic energy conversion efficiency K of the prepared CNFs-PDMS composite thin films is 15.6 × 10{sup −3 }Pa/(W/m{sup 2}), which is significantly higher than carbon black-PDMS thin films and other reported carbon nanomaterials, carbon nanostructures, and metal thin films. The demonstrated laser generated high intensity ultrasound source can be useful in ultrasound imaging and therapy.

  14. Crystalline boron nitride aerogels

    Energy Technology Data Exchange (ETDEWEB)

    Zettl, Alexander K.; Rousseas, Michael; Goldstein, Anna P.; Mickelson, William; Worsley, Marcus A.; Woo, Leta

    2017-04-04

    This disclosure provides methods and materials related to boron nitride aerogels. In one aspect, a material comprises an aerogel comprising boron nitride. The boron nitride has an ordered crystalline structure. The ordered crystalline structure may include atomic layers of hexagonal boron nitride lying on top of one another, with atoms contained in a first layer being superimposed on atoms contained in a second layer.

  15. Carbon-Incorporated Amorphous Indium Zinc Oxide Thin-Film Transistors

    Science.gov (United States)

    Parthiban, S.; Park, K.; Kim, H.-J.; Yang, S.; Kwon, J.-Y.

    2014-11-01

    We propose the use of amorphous-carbon indium zinc oxide (a-CIZO) as a channel material for thin-film transistor (TFT) fabrication. This study chose a carbon dopant as a carrier suppressor and strong oxygen binder in amorphous-indium zinc oxide (a-IZO) channel material. a-CIZO thin films were deposited using radiofrequency (RF) sputtering and postannealed at 150°C. X-ray diffraction and transmission electron microscopy analysis revealed that the film remained amorphous even after postannealing. The a-CIZO TFT postannealed at 150°C exhibited saturation field-effect mobility of 16.5 cm2 V-1 s-1 and on-off current ratio of ˜4.3 × 107.

  16. Plasma nitriding of steels

    CERN Document Server

    Aghajani, Hossein

    2017-01-01

    This book focuses on the effect of plasma nitriding on the properties of steels. Parameters of different grades of steels are considered, such as structural and constructional steels, stainless steels and tools steels. The reader will find within the text an introduction to nitriding treatment, the basis of plasma and its roll in nitriding. The authors also address the advantages and disadvantages of plasma nitriding in comparison with other nitriding methods. .

  17. Boron nitride composites

    Energy Technology Data Exchange (ETDEWEB)

    Kuntz, Joshua D.; Ellsworth, German F.; Swenson, Fritz J.; Allen, Patrick G.

    2017-02-21

    According to one embodiment, a composite product includes: a matrix material including hexagonal boron nitride and one or more borate binders; and a plurality of cubic boron nitride particles dispersed in the matrix material. According to another embodiment, a composite product includes: a matrix material including hexagonal boron nitride and amorphous boron nitride; and a plurality of cubic boron nitride particles dispersed in the matrix material.

  18. Monitoring structural defects and crystallinity of carbon nanotubes in thin films

    Indian Academy of Sciences (India)

    S S Mahajan; M D Bambole; S P Gokhale; A B Gaikwad

    2010-03-01

    We report the influence of catalyst formulation and reaction temperature on the formation of carbon nanotube (CNT) thin films by the chemical vapour deposition (CVD) method. Thin films of CNTs were grown on Fe–Mo/Al2O3-coated silicon wafer by thermal decomposition of methane at different temperatures ranging from 800 to 1000°C. The electron microscopic investigations, SEM as well as HRTEM, of the as-grown CNT thin films revealed the growth of uniform multi-walled CNTs in abundance. The intensity ratio of D-band to G-band and FWHM of G-band through Raman measurements clearly indicated the dependency of structural defects and crystallinity of CNTs in thin films on the catalyst formulation and CVD growth temperature. The results suggest that thin films of multi-walled CNTs with negligible amount of defects in the nanotube structure and very high crystallinity can be obtained by thermal CVD process at 925°C.

  19. Electrochemical Solution Growth of Magnetic Nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Monson, Todd C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pearce, Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-10-01

    Magnetic nitrides, if manufactured in bulk form, would provide designers of transformers and inductors with a new class of better performing and affordable soft magnetic materials. According to experimental results from thin films and/or theoretical calculations, magnetic nitrides would have magnetic moments well in excess of current state of the art soft magnets. Furthermore, magnetic nitrides would have higher resistivities than current transformer core materials and therefore not require the use of laminates of inactive material to limit eddy current losses. However, almost all of the magnetic nitrides have been elusive except in difficult to reproduce thin films or as inclusions in another material. Now, through its ability to reduce atmospheric nitrogen, the electrochemical solution growth (ESG) technique can bring highly sought after (and previously inaccessible) new magnetic nitrides into existence in bulk form. This method utilizes a molten salt as a solvent to solubilize metal cations and nitrogen ions produced electrochemically and form nitrogen compounds. Unlike other growth methods, the scalable ESG process can sustain high growth rates (~mm/hr) even under reasonable operating conditions (atmospheric pressure and 500 °C). Ultimately, this translates into a high throughput, low cost, manufacturing process. The ESG process has already been used successfully to grow high quality GaN. Below, the experimental results of an exploratory express LDRD project to access the viability of the ESG technique to grow magnetic nitrides will be presented.

  20. Terminal Uranium(V/VI) Nitride Activation of Carbon Dioxide and Carbon Disulfide: Factors Governing Diverse and Well-Defined Cleavage and Redox Reactions.

    Science.gov (United States)

    Cleaves, Peter A; Kefalidis, Christos E; Gardner, Benedict M; Tuna, Floriana; McInnes, Eric J L; Lewis, William; Maron, Laurent; Liddle, Stephen T

    2017-02-24

    The reactivity of terminal uranium(V/VI) nitrides with CE2 (E=O, S) is presented. Well-defined C=E cleavage followed by zero-, one-, and two-electron redox events is observed. The uranium(V) nitride [U(Tren(TIPS) )(N)][K(B15C5)2 ] (1, Tren(TIPS) =N(CH2 CH2 NSiiPr3 )3 ; B15C5=benzo-15-crown-5) reacts with CO2 to give [U(Tren(TIPS) )(O)(NCO)][K(B15C5)2 ] (3), whereas the uranium(VI) nitride [U(Tren(TIPS) )(N)] (2) reacts with CO2 to give isolable [U(Tren(TIPS) )(O)(NCO)] (4); complex 4 rapidly decomposes to known [U(Tren(TIPS) )(O)] (5) with concomitant formation of N2 and CO proposed, with the latter trapped as a vanadocene adduct. In contrast, 1 reacts with CS2 to give [U(Tren(TIPS) )(κ(2) -CS3 )][K(B15C5)2 ] (6), 2, and [K(B15C5)2 ][NCS] (7), whereas 2 reacts with CS2 to give [U(Tren(TIPS) )(NCS)] (8) and "S", with the latter trapped as Ph3 PS. Calculated reaction profiles reveal outer-sphere reactivity for uranium(V) but inner-sphere mechanisms for uranium(VI); despite the wide divergence of products the initial activation of CE2 follows mechanistically related pathways, providing insight into the factors of uranium oxidation state, chalcogen, and NCE groups that govern the subsequent divergent redox reactions that include common one-electron reactions and a less-common two-electron redox event. Caution, we suggest, is warranted when utilising CS2 as a reactivity surrogate for CO2 .

  1. Ellipsometric study of silicon nitride on gallium arsenide

    Science.gov (United States)

    Alterovitz, S. A.; Bu-Abbud, G. H.; Woollam, J. A.; Liu, D.; Chung, Y.; Langer, D.

    1982-01-01

    A method for optimizing the sensitivity of ellipsometric measurements for thin dielectric films on semiconductors is described in simple physical terms. The technique is demonstrated for the case of sputtered silicon nitride films on gallium arsenide.

  2. A review of production methods of carbon nanotube and graphene thin films for electrothermal applications

    Science.gov (United States)

    Janas, D.; Koziol, K. K.

    2014-02-01

    Electrothermal materials transform electric energy into heat due to the Joule effect. To date, resistive wires made of heavy metal alloys have primarily been used as the heat source in many appliances surrounding us. Recent discoveries in the field of carbon nanostructures revealed that they can offer a spectrum of advantages over the traditional materials. We review the production methods of thin films composed of carbon nanotubes or graphene and depict how they can be used as conductive coatings for electrothermal applications. We screen all reports from the field up to now and highlight the features of designed nanoheaters. A particular focus is placed on the analysis of general findings of how to tune their electrothermal properties, why carbon nanostructure devices operate the way they do and in what aspects they are superior to the currently available materials on the market.

  3. Fabrication of ultra thin and aligned carbon nanofibres from electrospun polyacrylonitrile nanofibres

    Indian Academy of Sciences (India)

    Javed Rafique; Jie Yu; Xiaoxiong Zha; Khalid Rafique

    2010-10-01

    Ultra thin and aligned carbon nanofibres (CNFs) have been fabricated by heat treatment from aligned polyacrylonitrile (PAN) nanofibre precursors prepared by electrospinning. The alignment of the precursor nanofibres was achieved by using a modified electrospinning set up developed recently, where a tip collector was used to collect and align the nanofibres. The average diameter of the aligned CNFs is about 80 nm. The stabilization and carbonization behaviour were studied mainly based on the randomly oriented PAN nanofibres. The effects of stabilization and carbonization temperatures, temperature-increasing rates, and with and without substrates on the morphology and structure of the CNFs were investigated. Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Raman spectroscopy were used to characterize the structure of the CNFs and thermogravimetric/differential temperature analysis was used to evaluate the thermal behaviour of PAN nanofibres.

  4. Study on Titanium Nitride Film Modified for Intraocular Lens

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Objective:To study the characteristics of the intraocular lens using ion beam sputtering depositing titanium nitride thin film on the intraocular lens(IOLs).Methods:To deposite titanium nitride thin film on the top of intraocular lens by ion beam sputtering depositing.We analyzed the surface morphology of intraocular lens through SEM and AFM.We detected intraocular lens resolution through the measurement of intraocular lens.Biocompatibility of intraocular lens is preliminary evaluated in this test.Results:T...

  5. Dynamics of 3D representation of interfaces in UV-induced chemical vapor deposition: experiments, modeling, and simulation for silicon nitride thin layers

    Science.gov (United States)

    Flicstein, Jean; Guillonneau, E.; Marquez, Jose; How Kee Chun, L. S.; Maisonneuve, D.; David, C.; Wang, Zh. Z.; Palmier, Jean F.; Courant, J. L.

    2001-06-01

    We study the surface dynamics of silicon nitride films deposited by UV-induced low pressure chemical vapor pressure. Atomic force microscopy measurements show that the surface reaches a scale invariant stationary state coherent wit the Kardar-Parisi-Zhang (KPZ) equation. Discrete geometry techniques are oriented to extra morphological characteristics of surface and bulk which corresponds to computer simulated photodeposit. This allows to determine the physical origin of KPZ scaling to be al ow value of the surface sticking probability, and connected to the surface concentration of activate charged centers, which permits to start the evaluation of the Monte Carlo-molecular dynamics simulator.

  6. The origin and chemical evolution of carbon in the Galactic thin and thick disks

    CERN Document Server

    Bensby, T

    2006-01-01

    [ABRIDGED] In order to trace the origin and evolution of carbon in the Galactic disk we have determined carbon abundances in 51 nearby F and G dwarf stars. The sample is divided into two kinematically distinct subsamples with 35 and 16 stars that are representative of the Galactic thin and thick disks, respectively. The analysis is based on spectral synthesis of the forbidden [C I] line at 872.7 nm using spectra of very high resolution (R~220000)and high signal-to-noise (S/N>300) that were obtained with the CES spectrograph on the ESO 3.6-m telescope on La Silla in Chile. We find that [C/Fe] versus [Fe/H] trends for the thin and thick disks are totally merged and flat for sub-solar metallicities. The thin disk that extends to higher metallicities than the thick disk,shows a shallow decline in [C/Fe] from [Fe/H]=0 and up to [Fe/H]=+0.4. The [C/O] versus [O/H] trends are well separated between the two disks (due to differences in the oxygen abundances)and bear a great resemblance to the [Fe/O] versus [O/H] tren...

  7. Efficient visible-light photocatalytic oxidation of gaseous NO with graphitic carbon nitride (g-C3N4) activated by the alkaline hydrothermal treatment and mechanism analysis.

    Science.gov (United States)

    Nie, Haoyu; Ou, Man; Zhong, Qin; Zhang, Shule; Yu, Lemeng

    2015-12-30

    In this paper, an enhanced visible-light photocatalytic oxidation (PCO) of NO (∼ 400 ppm) in the presence of the graphitic carbon nitride (g-C3N4) treated by the alkaline hydrothermal treatment is evaluated. Various g-C3N4 samples were treated in different concentrations of NaOH solutions and the sample treated in 0.12 mol L(-1) of NaOH solution possesses the largest BET specific surface area as well as the optimal ability of the PCO of NO. UV-vis diffuse reflection spectra (DRS) and photoluminescence (PL) spectra were also conducted, and the highly improved photocatalytic performance is ascribed to the large specific surface area and high pore volume, which provides more adsorption and active sites, the wide visible-light adsorption edge and the narrow band gap, which is favorable for visible-light activation, as well as the decreased recombination rate of photo-generated electrons and holes, which could contribute to the production of active species. Fluorescence spectra and a trapping experiment were conducted to further the mechanism analysis of the PCO of NO, illustrating that superoxide radicals (O2(-)) play the dominant role among active species in the PCO of NO.

  8. Room-temperature synthesis of nanoporous 1D microrods of graphitic carbon nitride (g-C3N4) with highly enhanced photocatalytic activity and stability

    Science.gov (United States)

    Pawar, Rajendra C.; Kang, Suhee; Park, Jung Hyun; Kim, Jong-Ho; Ahn, Sunghoon; Lee, Caroline S.

    2016-08-01

    A one-dimensional (1D) nanostructure having a porous network is an exceptional photocatalytic material to generate hydrogen (H2) and decontaminate wastewater using solar energy. In this report, we synthesized nanoporous 1D microrods of graphitic carbon nitride (g-C3N4) via a facile and template-free chemical approach at room temperature. The use of concentrated acids induced etching and lift-off because of strong oxidation and protonation. Compared with the bulk g-C3N4, the porous 1D microrod structure showed five times higher photocatalytic degradation performance toward methylene blue dye (MB) under visible light irradiation. The photocatalytic H2 evolution of the 1D nanostructure (34 μmol g-1) was almost 26 times higher than that of the bulk g-C3N4 structure (1.26 μmol g-1). Additionally, the photocurrent stability of this nanoporous 1D morphology over 24 h indicated remarkable photocorrosion resistance. The improved photocatalytic activities were attributed to prolonged carrier lifetime because of its quantum confinement effect, effective separation and transport of charge carriers, and increased number of active sites from interconnected nanopores throughout the microrods. The present 1D nanostructure would be highly suited for photocatalytic water purification as well as water splitting devices. Finally, this facile and room temperature strategy to fabricate the nanostructures is very cost-effective.

  9. ZnO-Layered Double Hydroxide@Graphitic Carbon Nitride Composite for Consecutive Adsorption and Photodegradation of Dyes under UV and Visible Lights

    Directory of Open Access Journals (Sweden)

    Luhong Zhang

    2016-11-01

    Full Text Available In this work, a ZnO-layered double hydroxide@graphitic carbon nitride composite (ZnO-LDH@C3N4 was synthesized via co-precipitation method with solvothermal treatment. The structure and morphology of ZnO-LDH@C3N4 composite were characterized using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FT-IR, scanning electron microscopes/transmission electron microscopes (SEM/TEM, N2 adsorption/desorption, ultraviolet visible diffuse reflectance spectroscopy (UV-Vis-DRS, photoluminescence spectrometer (PL and electrochemical impedance spectroscopy (EIS. The adsorption and photocatalytic properties of ZnO-LDH@C3N4 composite towards the organic dyes: Orange II sodium salt (OrgII, an anionic azo dye and methylene blue (MB, a cationic azo dye were investigated. Compared to ZnO-LDH and g-C3N4, the ZnO-LDH@C3N4 composite displayed an excellent performance in both adsorption and photocatalytic degradation of the organic dyes. Moreover, a combination of ZnO-LDH and g-C3N4 significantly improved the photocatalytic performance of ZnO-LDH and g-C3N4 under visible-light irradiation. The adsorption and photocatalytic mechanism were also investigated.

  10. Hydrothermal synthesis of graphitic carbon nitride-BiVO4 composites with enhanced visible light photocatalytic activities and the mechanism study

    Science.gov (United States)

    Guo, Feng; Shi, Weilong; Lin, Xue; Che, Guangbo

    2014-11-01

    Novel graphitic carbon nitride (C3N4) and bismuth vanadate (BiVO4) composite photocatalysts were successfully synthesized by a facile hydrothermal method. The scanning electron microscopy (SEM) revealed that an intimate interface between C3N4 and BiVO4 formed in the composites. Compared with the pure C3N4 and BiVO4, the C3N4-BiVO4 photocatalysts showed remarkably the higher photocatalytic activities in degrading rhodamine B (Rh B). The best active heterojunction proportion was 0.5C3N4-0.5BiVO4. Over this catalyst, the 100% degradation of Rh B (0.002 mmol L-1) was obtained under visible light irradiation (λ>420 nm) for 40 min. The active species in Rh B degradation were examined by adding a series of scavengers. The study on photocatalytic mechanism revealed that the electrons injected directly from the conduction band of C3N4 to that of BiVO4, resulting in the production of superoxide radical (O2•-) and hydroxyl radical (OH•) in the conduction band of BiVO4. Simultaneously, the rich holes in the valence band of g-C3N4 oxidized Rh B directly to promote the photocatalytic degradation reaction.

  11. Improvement of visible light-induced photocatalytic performance by Cr-doped SrTiO3-carbon nitride intercalation compound (CNIC) composite

    Institute of Scientific and Technical Information of China (English)

    杨明; 金效齐

    2016-01-01

    Novel organic−inorganic composite photocatalyst offers new opportunities in the practical applications of photocatalysis. Novel visible light-induced Cr-doped SrTiO3–carbon nitride intercalation compound (CNIC) composite photocatalysts were synthesized. The composite photocatalyst was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) spectroscopy, UV-vis diffuse reflection spectroscopy, photoluminescence (PL) spectroscopy, and BET surface area analyzer. The photocatalytic oxidation ability of the novel composite photocatalyst was evaluated using methyl orange (MO) as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading MO. For maximizing the photodegradation activity of the composite photocatalysts, the optimal CNIC content was determined. The improved photocatalytic activity of the as-prepared Cr-doped SrTiO3–CNIC composite photocatalyst may be attributed to the enhancement of photo-generated electron–hole separations at the interface.

  12. Facile synthesis of magnetic carbon nitride nanosheets and its application in magnetic solid phase extraction for polycyclic aromatic hydrocarbons in edible oil samples.

    Science.gov (United States)

    Zheng, Hao-Bo; Ding, Jun; Zheng, Shu-Jian; Zhu, Gang-Tian; Yuan, Bi-Feng; Feng, Yu-Qi

    2016-01-01

    In this study, we proposed a method to fabricate magnetic carbon nitride (CN) nanosheets by simple physical blending. Low-cost CN nanosheets prepared by urea possessed a highly π-conjugated structure; therefore the obtained composites were employed as magnetic solid-phase extraction (MSPE) sorbent for extraction of polycyclic aromatic hydrocarbons (PAHs) in edible oil samples. Moreover, sample pre-treatment time could be carried out within 10 min. Thus, a simple and cheap method for the analysis of PAHs in edible oil samples was established by coupling magnetic CN nanosheets-based MSPE with gas chromatography-mass spectrometry (GC/MS) analysis. Limits of quantitation (LOQs) for eight PAHs ranged from 0.4 to 0.9 ng/g. The intra- and inter-day relative standard deviations (RSDs) were less than 15.0%. The recoveries of PAHs for spiked soybean oil samples ranged from 91.0% to 124.1%, with RSDs of less than 10.2%. Taken together, the proposed method offers a simple and cost-effective option for the convenient analysis of PAHs in oil samples.

  13. Carbon nanotube thin film strain sensor models assembled using nano- and micro-scale imaging

    Science.gov (United States)

    Lee, Bo Mi; Loh, Kenneth J.; Yang, Yuan-Sen

    2017-02-01

    Nanomaterial-based thin films, particularly those based on carbon nanotubes (CNT), have brought forth tremendous opportunities for designing next-generation strain sensors. However, their strain sensing properties can vary depending on fabrication method, post-processing treatment, and types of CNTs and polymers employed. The objective of this study was to derive a CNT-based thin film strain sensor model using inputs from nano-/micro-scale experimental measurements of nanotube physical properties. This study began with fabricating ultra-low-concentration CNT-polymer thin films, followed by imaging them using atomic force microscopy. Image processing was employed for characterizing CNT dispersed shapes, lengths, and other physical attributes, and results were used for building five different types of thin film percolation-based models. Numerical simulations were conducted to assess how the morphology of dispersed CNTs in its 2D matrix affected bulk film electrical and electromechanical (strain sensing) properties. The simulation results showed that CNT morphology had a significant impact on strain sensing performance.

  14. Chemical Sharpening, Shortening, and Unzipping of Boron Nitride Nanotubes

    Science.gov (United States)

    Liao, Yunlong; Chen, Zhongfang; Connell, John W.; Fay, Catharine C.; Park, Cheol; Kim, Jae-Woo; Lin, Yi

    2014-01-01

    Boron nitride nanotubes (BNNTs), the one-dimensional member of the boron nitride nanostructure family, are generally accepted to be highly inert to oxidative treatments and can only be covalently modifi ed by highly reactive species. Conversely, it is discovered that the BNNTs can be chemically dispersed and their morphology modifi ed by a relatively mild method: simply sonicating the nanotubes in aqueous ammonia solution. The dispersed nanotubes are significantly corroded, with end-caps removed, tips sharpened, and walls thinned. The sonication treatment in aqueous ammonia solution also removes amorphous BN impurities and shortened BNNTs, resembling various oxidative treatments of carbon nanotubes. Importantly, the majority of BNNTs are at least partially longitudinally cut, or "unzipped". Entangled and freestanding BN nanoribbons (BNNRs), resulting from the unzipping, are found to be approximately 5-20 nm in width and up to a few hundred nanometers in length. This is the fi rst chemical method to obtain BNNRs from BNNT unzipping. This method is not derived from known carbon nanotube unzipping strategies, but is unique to BNNTs because the use of aqueous ammonia solutions specifi cally targets the B-N bond network. This study may pave the way for convenient processing of BNNTs, previously thought to be highly inert, toward controlling their dispersion, purity, lengths, and electronic properties.

  15. Properties of silicon nitride thin overlays deposited on optical fibers — Effect of fiber suspension in radio frequency plasma-enhanced chemical vapor deposition reactor

    Energy Technology Data Exchange (ETDEWEB)

    Śmietana, M., E-mail: M.Smietana@elka.pw.edu.pl [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, Warsaw 00-662 (Poland); Dominik, M.; Myśliwiec, M.; Kwietniewski, N. [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, Warsaw 00-662 (Poland); Mikulic, P. [Centre de Recherche en Photonique, Université du Québec en Outaouais, 101 rue Saint-Jean-Bosco, Gatineau, J8X 3X7, Québec (Canada); Witkowski, B.S. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, Warsaw 02-666 (Poland); Bock, W.J. [Centre de Recherche en Photonique, Université du Québec en Outaouais, 101 rue Saint-Jean-Bosco, Gatineau, J8X 3X7, Québec (Canada)

    2016-03-31

    This work discusses the effect of sample suspension in radio frequency plasma-enhanced chemical vapor deposition process on properties of the obtained overlays. Silicon nitride (SiN{sub x}) overlays were deposited on flat silicon wafers and cylindrical fused silica optical fibers. The influence of the suspension height and fiber diameter on SiN{sub x} deposition rate is investigated. It has been found that thickness of the SiN{sub x} overlay significantly increases with suspension height, and the deposition rate depends on fiber dimensions. Moreover, the SiN{sub x} overlays were also deposited on long-period gratings (LPGs) induced in optical fiber. Measurements of the LPG spectral response combined with its numerical simulations allowed for a discussion on properties of the deposited overlay. The measurements have proven higher overlay deposition rate on the suspended fiber than on flat Si wafer placed on the electrode. Results of this work are essential for precise tuning of the functional properties of new generations of optical devices such as optical sensors, filters and resonators, which typically are based on optical fibers and require the overlays with well defined properties. - Highlights: • The effect of optical fiber suspension in plasma process is discussed. • The deposition rate of silicon nitride (SiN{sub x}) overlay depends on fiber dimensions. • Thickness of the SiN{sub x} overlay strongly increases with suspension height. • Measurements and simulations of long-period grating confirms experimental results.

  16. In-plane Thermal and Electrical Transport Through Single-walled Carbon Nanotube Thin Films

    Science.gov (United States)

    Ferguson, A. J.; Avery, A. D.; Mistry, K. S.; Zink, B. L.; Olsen, M. L.; Parilla, P. A.; Blackburn, J. L.

    2014-03-01

    Recent advances in both chemical processing and fabrication techniques have enabled the development of a variety of new nanostructured materials for energy conversion technologies. Single-walled carbon nanotube (SWNT) networks may enable a number of cost-effective energy technologies, including transparent conductors for photovoltaics and thermoelectric composites. For such applications, a fundamental understanding of the physics governing their thermal and electrical properties is needed. Transport in SWNT networks is highly anisotropic; therefore the ability to measure the in-plane transport, both thermal and electrical, for these systems is extremely important. In this talk, we discuss the dispersion of highly enriched semiconducting SWNTs in organic solvents and deposition techniques optimized to enable measurements of in-plane transport of uniform thin films. We present results from in-plane thermal and electrical measurements as well as optical properties of SWNT:polymer thin films. Finally, we discuss the application of these results to developing nanocomposite films optimized for thermoelectric applications.

  17. Characterization of hydrogenated and deuterated thin carbon films deposited by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Pantelica, D., E-mail: pantel@nipne.ro [Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), P.O.B. MG-6, 30 Reactorului St., RO 077125 Magurele (Romania); Ionescu, P.; Petrascu, H. [Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), P.O.B. MG-6, 30 Reactorului St., RO 077125 Magurele (Romania); Nita, C.R. [Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), P.O.B. MG-6, 30 Reactorului St., RO 077125 Magurele (Romania); University Politehnica of Bucharest, RO 060042 Bucharest (Romania); Matei, E.; Rasoga, O. [National Institute for Materials Physics, 105 Atomistilor Str., RO 077125 Magurele-Bucharest (Romania); Acsente, T.; Dinescu, G. [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., RO 077125 Magurele-Bucharest (Romania)

    2014-07-15

    Thin films of C layers were deposited by radiofrequency magnetron sputtering on silicon substrates using three gaseous atmospheres: pure Ar, Ar + H{sub 2} and Ar + D{sub 2} mixtures. Scanning Electron Microscopy investigations showed that addition of D{sub 2} or H{sub 2} to main sputtering gas (Ar) leads to the enhancement of the deposition rate while the layer morphology remained columnar. Fourier Transform Infrared Spectroscopy measurements revealed the presence of D–C or H–C chemical bonds in the samples. Ion beam analysis measurements performed by simultaneous recording of the recoiled H and D ions, and of backscattered {sup 4}He confirmed the incorporation of hydrogen and deuterium in the deposited carbon thin films.

  18. Structure of reactively sputter deposited tin-nitride thin films: A combined X-ray photoelectron spectroscopy, in situ X-ray reflectivity and X-ray absorption spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Luetzenkirchen-Hecht, Dirk [Fachbereich C-Physik, Bergische Universitaet Wuppertal, Gaussstr. 20, D-42097 Wuppertal (Germany)]. E-mail: dirklh@uni-wuppertal.de; Frahm, Ronald [Fachbereich C-Physik, Bergische Universitaet Wuppertal, Gaussstr. 20, D-42097 Wuppertal (Germany)

    2005-12-22

    Amorphous tin-nitride thin films were prepared by reactive sputter deposition on smooth float glass substrates in a vacuum chamber with an integrated small magnetron source. The films were investigated using in situ reflection mode X-ray absorption spectroscopy and ex situ X-ray photoelectron spectroscopy (XPS). Both the X-ray absorption near edge structure (XANES) and the extended X-ray absorption fine structure (EXAFS) were analysed, yielding bond distances, coordination numbers and Debye-Waller factors. XPS yields the chemical composition and the binding state of the constituents of the films, specular X-ray reflectivity allows the determination of the sample density and of the roughness and its changes with film thickness. The results were compared to those of crystalline Sn{sub 3}N{sub 4}, indicating that the electronic and atomic structure of the amorphous films determined by EXAFS data analysis are very similar to the stoichiometric reference compound. Two different Sn-N interactions with about 2.09 and 2.19 A bond distance and 4 and 6 nearest neighbours, respectively, are present. These bond distances are slightly relaxed compared to the crystalline reference material, which is consistent with the sample density, which is reduced by about 8% in comparison to Sn{sub 3}N{sub 4}. XPS as well as XANES revealed a Sn valence of about 4+ and the presence of nitric bonds, while XPS also suggests that the nitride is slightly decomposed under X-ray irradiation in ultra-high vacuum.

  19. Amorphous Hydrogenated Carbon-Nitrogen Alloy Thin Films for Solar Cell Application

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhi-Bin; DING Zheng-Ming; PANG Qian-Jun; CUI Rong-Qiang

    2001-01-01

    Amorphous hydrogenated carbon-nitrogen alloy (a-CNx :H) thin films have been deposited on silicon substratesby improved dc magnetron sputtering from a graphite target in nitrogen and hydrogen gas discharging. Thefilms are investigated by using Raman spectroscopy, x-ray photoelectron spectroscopy, spectral ellipsometer and electron spin resonance techniques. The optimized process condition for solar cell application is discussed. Thephotovoltaic property of a-CNx:H/silicon heterojunctions can be improved by the adjustment of the pressureratio of hydrogen to nitrogen and unbalanced magnetic field intensity. Open-circuit voltage and short-circuitcurrent reach 300mV and 5.52 Ma/cm2, respectively.

  20. Thin, Flexible Supercapacitors Made from Carbon Nanofiber Electrodes Decorated at Room Temperature with Manganese Oxide Nanosheets

    Directory of Open Access Journals (Sweden)

    S. K. Nataraj

    2013-01-01

    Full Text Available We report the fabrication and electrochemical performance of a flexible thin film supercapacitor with a novel nanostructured composite electrode. The electrode was prepared by in situ coprecipitation of two-dimensional (2D MnO2 nanosheets at room temperature in the presence of carbon nanofibers (CNFs. The highest specific capacitance of 142 F/g was achieved for CNFs-MnO2 electrodes in sandwiched assembly with PVA-H4SiW12O40·nH2O polyelectrolyte separator.

  1. Carbon Nanotube Thin Film Biosensors for Sensitive and Reproducible Whole Virus Detection

    Directory of Open Access Journals (Sweden)

    Himadri S. Mandal, Zhengding Su, Andrew Ward, Xiaowu (Shirley Tang

    2012-01-01

    Full Text Available Here, we report the label-free, sensitive, and real-time electrical detection of whole viruses using carbon nanotube thin film (CNT-TF field effect devices. Selective detection of approximately 550 model viruses, M13-bacteriophage, is demonstrated using a simple two-terminal (no gate electrode configuration. Chemical gating through specific antibody-virus binding on CNT surface is proposed to be the sensing mechanism. Compared to electrical impedance sensors with identical microelectrode dimensions (no CNT, the CNT-TF sensors exhibit sensitivity 5 orders higher. We believe the reported approach could lead to a reproducible and cost-effective solution for rapid viral identification.

  2. Plasma breaking of thin films into nano-sized catalysts for carbon nanotube synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Gao, J.S.; Umeda, K.; Uchino, K.; Nakashima, H.; Muraoka, K

    2003-07-15

    Iron thin films deposited by pulse laser deposition (PLD) were broken into uniform nano-sized catalysts by plasma bombardment for carbon nanotube (CNT) synthesis. Size distributions of broken catalysts were obtained in terms of plasma discharge conditions. Vertically arranged high-density (10{sup 13} per m{sup 2}) CNTs were synthesized using microwave plasma chemical vapor deposition (MP-CVD) system and the gas mixture of N{sub 2} and CH{sub 4} on optimally broken catalysts with few carbonaceous particles on a large area Si substrate. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy (RS) were used to evaluate the obtained CNTs.

  3. STUDY OF DYNAMIC RECRYSTALLIZATION OF LOW CARBON STEEL IN THIN SLAB CONTINUOUS ROLLING PROCESS

    Institute of Scientific and Technical Information of China (English)

    X.K. Liang; X.J. Sun; Q.Y. Liu; H. Dong

    2006-01-01

    Combined with the technological characteristics of thin slab continuous rolling process (TSCR),dynamic recrystallization of an extremely coarse austenite of low carbon steel is studied by Thermecmaster-Z hot simulator. By the analysis of true stress-strain curves and the observation of microstructures at different deformation stages, the critical stress and critical strain are determined under different deformation conditions. The effect of Z parameter on dynamic recrystallization of coarse austenite is studied. The microstructure evolution in real production is also discussed.

  4. Carbon dioxide and water adsorption on highly epitaxial Delafossite CuFeO2 thin film

    Science.gov (United States)

    Rojas, S.; Joshi, T.; Borisov, P.; Sarabia, M.; Lederman, D.; Cabrera, A. L.

    2015-03-01

    Thermal programmed desorption (TPD) of CO2 and H2O from a 200 nm thick CuFeO2 Delafossite surface was performed in a standard UHV chamber, The CuFeO2 thin film grown using Pulsed Laser Deposition (PLD) over an Al2O3 (0001) substrate with controlled O2 atmosphere resulted with highly epitaxial crystal structure. The adsorption/desorption of CO2 and H2O process was also monitored with X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). Our results revealed that carbon dioxide interacts with CuFeO2 forming Fe carbonates compounds on its surface. Hydroxides were also formed on the surface due to water presence. Using TPD data, Arrhenius plots for CO2 and water desorption were done and activation energy for desorption was obtained. Funds FONDECyT 1130372; Thanks to P. Ferrari.

  5. Swift heavy ion induced modifications of single walled carbon nanotube thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vishalli, E-mail: vishalli_2008@yahoo.com [Department of Physics, Panjab University, Chandigarh 160014 (India); Raina, K.K. [Materials Research Laboratory, School of Physics and Materials Science, Thapar University, P.O. Box 32, Patiala 147004, Punjab (India); Avasthi, D.K. [Materials Science Group, Inter University Accelerator Centre, Aruna Asaf Ali Marg, P.O. Box 10502, New Delhi 110067 (India); Srivastava, Alok [Department of Chemistry, Panjab University, Chandigarh 160014 (India); Dharamvir, Keya [Department of Physics, Panjab University, Chandigarh 160014 (India)

    2016-04-15

    Thin films of single walled carbon nanotubes (SWCNTs) were prepared by Langmuir–Blodgett method and irradiated with swift heavy ions, carbon and nickel each of energy 60 MeV. The ion beams have different electronic energy loss (S{sub e}) values and the samples were exposed to various irradiation doses. The irradiated films were characterized using Raman and optical absorption spectroscopy. Raman spectroscopy results indicate the competing processes of defect creation and healing (annealing) of SWCNTs at lower fluences, while at higher fluences defect creation or damage dominates. In UV–Vis–NIR spectroscopy we find that there is decrease in the intensity of characteristic peaks with every increasing fluence, indicating decrease in the optically active states with irradiation.

  6. Percolation of Carbon Nanoparticles in Poly(3-Hexylthiophene Enhancing Carrier Mobility in Organic Thin Film Transistors

    Directory of Open Access Journals (Sweden)

    Chang-Hung Lee

    2014-01-01

    Full Text Available To improve the field-effect mobility of all-inkjet-printed organic thin film transistors (OTFTs, a composite material consisted of carbon nanoparticles (CNPs and poly(3-hexylthiophene (P3HT was reported by using homemade inkjet-printing system. These all-inkjet-printed composite OTFTs represented superior characteristics compared to the all-inkjet-printed pristine P3HT OTFTs. To investigate the enhancement mechanism of the blended materials, the percolation model was established and experimentally verified to illustrate the enhancement of the electrical properties with different blending concentrations. In addition, experimental results of OTFT contact resistances showed that both contact resistance and channel resistance were halved. At the same time, X-ray diffraction measurements, Fourier transform infrared spectra, ultraviolet-visible light, and photoluminescence spectra were also accomplished to clarify the material blending effects. Therefore, this study demonstrates the potential and guideline of carbon-based nanocomposite materials in all-inkjet-printed organic electronics.

  7. Low temperature gaseous nitriding and carburising of stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A.J.

    2005-01-01

    The response of various austenitic and duplex stainless steel grades to low temperature gaseous nitriding and carburising was investigated. Gaseous nitriding was performed in ammonia/hydrogen mixtures at temperatures ,723 K; gaseous carburising was carried out in carbon monoxide/hydrogen mixtures...

  8. Modeling the kinetics of the nitriding and nitrocarburizing of iron

    DEFF Research Database (Denmark)

    Somers, Marcel A. J.; Mittemeijer, Eric J.

    1998-01-01

    The growth kinetics of the iron-nitride compound layer during nitriding and nitrocarburizing of pure iron has been investigated for various temperatures and various combinations of imposed nitrogen and carbon activities. The results indicate that no local equilibrium occurs at the gas/solid inter...

  9. Structure-property relations for silicon nitride matrix composites reinforced with pyrolytic carbon pre-coated Hi-Nicalon fibers

    NARCIS (Netherlands)

    Kooi, B.J.; Hosson, J.Th.M. De; Olivier, C.; Veyret, J.B.

    1999-01-01

    Si3N4 matrix composites reinforced with pyrolytic carbon pre-coated Hi-Nicalon (SiC) fibers, were studied using tensile testing and transmission electron microscopy. Three types of samples were evaluated all with a nominal coating thickness of 200 nm. The composites were densified by hot pressing at

  10. Density functional theory study on the full ALD process of silicon nitride thin film deposition via BDEAS or BTBAS and NH3.

    Science.gov (United States)

    Huang, Liang; Han, Bo; Han, Bing; Derecskei-Kovacs, Agnes; Xiao, Manchao; Lei, Xinjian; O'Neill, Mark L; Pearlstein, Ronald M; Chandra, Haripin; Cheng, Hansong

    2014-09-14

    A detailed reaction mechanism has been proposed for the full ALD cycle of Si3N4 deposition on the β-Si3N4(0001) surface using bis(diethylamino)silane (BDEAS) or bis(tertiarybutylamino)silane (BTBAS) as a Si precursor with NH3 acting as the nitrogen source. Potential energy landscapes were derived for all elementary steps in the proposed reaction network using a periodic slab surface model in the density functional approximation. Although the dissociative reactivity of BTBAS was slightly better than that of BDEAS, the thermal deposition process was still found to be an inherently high temperature process due to the high activation energies during the dissociative chemisorption of both precursors and the surface re-amination steps. These results underline the need to develop new precursors and alternative nitrogen sources when low temperature thermal silicon nitride films are targeted.

  11. Structural, nanomechanical and variable range hopping conduction behavior of nanocrystalline carbon thin films deposited by the ambient environment assisted filtered cathodic jet carbon arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Panwar, O.S., E-mail: ospanwar@mail.nplindia.ernet.in [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Rawal, Ishpal; Tripathi, R.K. [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Srivastava, A.K. [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Kumar, Mahesh [Ultrafast Opto-Electronics and Tetrahertz Photonics Group, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India)

    2015-04-15

    Highlights: • Nanocrystalline carbon thin films are grown by filtered cathodic jet carbon arc process. • Effect of gaseous environment on the properties of carbon films has been studied. • The structural and nanomechanical properties of carbon thin films have been studied. • The VRH conduction behavior in nanocrystalline carbon thin films has been studied. - Abstract: This paper reports the deposition and characterization of nanocrystalline carbon thin films by filtered cathodic jet carbon arc technique assisted with three different gaseous environments of helium, nitrogen and hydrogen. All the films are nanocrystalline in nature as observed from the high resolution transmission electron microscopic (HRTEM) measurements, which suggests that the nanocrystallites of size ∼10–50 nm are embedded though out the amorphous matrix. X-ray photoelectron spectroscopic studies suggest that the film deposited under the nitrogen gaseous environment has the highest sp{sup 3}/sp{sup 2} ratio accompanied with the highest hardness of ∼18.34 GPa observed from the nanoindentation technique. The film deposited under the helium gaseous environment has the highest ratio of the area under the Raman D peak to G peak (A{sub D}/A{sub G}) and the highest conductivity (∼2.23 S/cm) at room temperature, whereas, the film deposited under the hydrogen environment has the lowest conductivity value (2.27 × 10{sup −7} S/cm). The temperature dependent dc conduction behavior of all the nanocrystalline carbon thin films has been analyzed in the light of Mott’s variable range hopping (VRH) conduction mechanism and observed that all the films obey three dimension VRH conduction mechanism for the charge transport.

  12. Inprovement of Field Emission Properties of PBS Thin Films by Amorphous Carbon Coating

    Directory of Open Access Journals (Sweden)

    S. Jana

    2011-01-01

    Full Text Available Lead sulfide (PbS nanocrystalline thin films were synthesized at room temperature via chemical bath deposition on both silicon and glass substrates and coated with amorphous carbon of different thickness by varying deposition time in plasma enhanced chemical vapor deposition technique. The as prepared samples were characterized by X-ray diffraction (XRD, field emission scanning electron microscope (FESEM and atomic force microscope (AFM. XRD study reveals that coating of amorphous carbon does not change the crystal structure of PbS. From FESEM images it is seen that the average size of PbS nanoparticle does not exceed 100 nm, though sometomes small cubic particles agglomerated to form bigger particles. The coating of amorphous carbon can be clearly visible by the FESEM as well as from AFM micrographs. Field emission study show a significant betterment for the carbon coated sample as compared to the pure PbS. The effect of inter-electrode distance on the field emission characteristics of best field emitting sample has been studied for three different inter-electrode distances.

  13. Amorphous Carbon Gold Nanocomposite Thin Films: Structural and Spectro-ellipsometric Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Montiel-Gonzalez, Z., E-mail: zeuzmontiel@hotmail.com [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito exterior s/n, Ciudad Universitaria, Coyoacan 04510, Mexico D.F (Mexico); Rodil, S.E.; Muhl, S. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito exterior s/n, Ciudad Universitaria, Coyoacan 04510, Mexico D.F (Mexico); Mendoza-Galvan, A. [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional, Unidad Queretaro, 76010 Queretaro, Queretaro (Mexico); Rodriguez-Fernandez, L. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Circuito de la Investigacion Cientifica, Ciudad Universitaria, 04510, Mexico D.F (Mexico)

    2011-07-01

    Spectroscopic Ellipsometry was used to determine the optical and structural properties of amorphous carbon:gold nanocomposite thin films deposited by dc magnetron co-sputtering at different deposition power. The incorporation of gold as small particles distributed in the amorphous carbon matrix was confirmed by X-ray Diffraction, Rutherford Backscattering measurements and High Resolution Transmission Electron Microscopy. Based on these results, an optical model for the films was developed using the Maxwell-Garnett effective medium with the Drude-Lorentz model representing the optical response of gold and the Tauc-Lorentz model for the amorphous carbon. The gold volume fraction and particle size obtained from the fitting processes were comparable to those from the physical characterization. The analysis of the ellipsometric spectra for all the samples showed strong changes in the optical properties of the carbon films as a consequence of the gold incorporation. These changes were correlated to the structural modification observed by Raman Spectroscopy, which indicated a clustering of the sp{sup 2} phase with a subsequent decrease in the optical gap. Finally, measurements of Reflection and Transmission Spectroscopy were carried out and Transmission Electron Microscopy images were obtained in order to support the ellipsometric model results.

  14. The production of carbon nanofibers and thin films on palladium catalysts from ethylene oxygen mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Jonathan [Los Alamos National Laboratory; Doorn, Stephen [Los Alamos National Laboratory; Atwater, Mark [UNM MECH.ENG.; Leseman, Zayd [UNM MECH.ENG.; Luhrs, Claudia C [UNM ENG.MECH; Diez, Yolanda F [SPAIN; Diaz, Angel M [SPAIN

    2009-01-01

    The characteristics of carbonaceous materials deposited in fuel rich ethylene-oxygen mixtures on three types of palladium: foil, sputtered film, and nanopowder, are reported. It was found that the form of palladium has a dramatic influence on the morphology of the deposited carbon. In particular, on sputtered film and powder, tight 'weaves' of sub-micron filaments formed quickly. In contrast, on foils under identical conditions, the dominant morphology is carbon thin films with basal planes oriented parallel to the substrate surface. Temperature, gas flow rate, reactant flow ratio (C2H4:02), and residence time (position) were found to influence both growth rate and type for all three forms of Pd. X-ray diffraction, high-resolution transmission electron microscopy, temperature-programmed oxidation, and Raman spectroscopy were used to assess the crystallinity of the as-deposited carbon, and it was determined that transmission electron microscopy and x-ray diffraction were the most reliable methods for determining crystallinity. The dependence of growth on reactor position, and the fact that no growth was observed in the absence of oxygen support the postulate that the carbon deposition proceeds by combustion generated radical species.

  15. Multi-Walled Carbon Nanotube-Doped Tungsten Oxide Thin Films for Hydrogen Gas Sensing

    Directory of Open Access Journals (Sweden)

    Adisorn Tuantranont

    2010-08-01

    Full Text Available In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT-doped tungsten oxide (WO3 thin films by means of the powder mixing and electron beam (E-beam evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO3 thin film exhibits high sensitivity and selectivity to hydrogen. Thus, MWCNT doping based on E-beam co-evaporation was shown to be an effective means of preparing hydrogen gas sensors with enhanced sensing and reduced operating temperatures. Creation of nanochannels and formation of p-n heterojunctions were proposed as the sensing mechanism underlying the enhanced hydrogen sensitivity of this hybridized gas sensor. To our best knowledge, this is the first report on a MWCNT-doped WO3 hydrogen sensor prepared by the E-beam method.

  16. Multi-walled carbon nanotube-doped tungsten oxide thin films for hydrogen gas sensing.

    Science.gov (United States)

    Wongchoosuk, Chatchawal; Wisitsoraat, Anurat; Phokharatkul, Ditsayut; Tuantranont, Adisorn; Kerdcharoen, Teerakiat

    2010-01-01

    In this work we have fabricated hydrogen gas sensors based on undoped and 1 wt% multi-walled carbon nanotube (MWCNT)-doped tungsten oxide (WO(3)) thin films by means of the powder mixing and electron beam (E-beam) evaporation technique. Hydrogen sensing properties of the thin films have been investigated at different operating temperatures and gas concentrations ranging from 100 ppm to 50,000 ppm. The results indicate that the MWCNT-doped WO(3) thin film exhibits high sensitivity and selectivity to hydrogen. Thus, MWCNT doping based on E-beam co-evaporation was shown to be an effective means of preparing hydrogen gas sensors with enhanced sensing and reduced operating temperatures. Creation of nanochannels and formation of p-n heterojunctions were proposed as the sensing mechanism underlying the enhanced hydrogen sensitivity of this hybridized gas sensor. To our best knowledge, this is the first report on a MWCNT-doped WO(3) hydrogen sensor prepared by the E-beam method.

  17. Iron, nitrogen and silicon doped diamond like carbon (DLC) thin films: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Sekhar C., E-mail: Raysc@unisa.ac.za [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Private Bag X6, Florida, 1710, Science Campus, Christiaan de Wet and Pioneer Avenue, Florida Park, Johannesburg (South Africa); Pong, W.F. [Department of Physics, Tamkang University, Tamsui 251, New Taipei City, Taiwan (China); Papakonstantinou, P. [Nanotechnology and Integrated Bio-Engineering Centre, University of Ulster, Shore Road, Newtownabbey BT37 0QB (United Kingdom)

    2016-07-01

    The X-ray absorption near edge structure (XANES), X-ray photoelectron spectroscopy (XPS), valence band photoemission (VB-PES) and Raman spectroscopy results show that the incorporation of nitrogen in pulsed laser deposited diamond like carbon (DLC) thin films, reverts the sp{sup 3} network to sp{sup 2} as evidenced by an increase of the sp{sup 2} cluster and I{sub D}/I{sub G} ratio in C K-edge XANES and Raman spectra respectively which reduces the hardness/Young's modulus into the film network. Si-doped DLC film deposited in a plasma enhanced chemical vapour deposition process reduces the sp{sup 2} cluster and I{sub D}/I{sub G} ratio that causes the decrease of hardness/Young's modulus of the film structure. The Fe-doped DLC films deposited by dip coating technique increase the hardness/Young's modulus with an increase of sp{sup 3}-content in DLC film structure. - Highlights: • Fe, N and Si doped DLC films deposited by dip, PLD and PECVD methods respectively • DLC:Fe thin films have higher hardness/Young's modulus than DLC:N(:Si) thin films. • sp{sup 3} and sp{sup 2} contents are estimated from C K-edge XANES and VB-PES measurements.

  18. Graphene oxide/carbon nanoparticle thin film based IR detector: Surface properties and device characterization

    Energy Technology Data Exchange (ETDEWEB)

    Chowdhury, Farzana Aktar [Experimental Physics Division, Atomic Energy Centre, 4, Kazi Nazrul Islam Avenue, Dhaka-1000 (Bangladesh); Hossain, Mohammad Abul [Department of Chemistry, Faculty of Science, University of Dhaka, Dhaka-1000 (Bangladesh); Uchida, Koji; Tamura, Takahiro; Sugawa, Kosuke; Mochida, Tomoaki; Otsuki, Joe [College of Science and Technology, Nihon University, 1-8-14 Kanda Surugadai, Chiyoda-ku, Tokyo 101-8308 (Japan); Mohiuddin, Tariq [Department of Physics, College of Science, Sultan Qaboos University, Muscat (Oman); Boby, Monny Akter [Department of Physics, Faculty of Science, University of Dhaka, Dhaka-1000 (Bangladesh); Alam, Mohammad Sahabul, E-mail: msalam@ksu.edu.sa [Department of Physics, Faculty of Science, University of Dhaka, Dhaka-1000 (Bangladesh); Department of Chemical Engineering, College of Engineering & King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)

    2015-10-15

    This work deals with the synthesis, characterization, and application of carbon nanoparticles (CNP) adorned graphene oxide (GO) nanocomposite materials. Here we mainly focus on an emerging topic in modern research field presenting GO-CNP nanocomposite as a infrared (IR) radiation detector device. GO-CNP thin film devices were fabricated from liquid phase at ambient condition where no modifying treatments were necessary. It works with no cooling treatment and also for stationary objects. A sharp response of human body IR radiation was detected with time constants of 3 and 36 sec and radiation responsivity was 3 mAW{sup −1}. The current also rises for quite a long time before saturation. This work discusses state-of-the-art material developing technique based on near-infrared photon absorption and their use in field deployable instrument for real-world applications. GO-CNP-based thin solid composite films also offer its potentiality to be utilized as p-type absorber material in thin film solar cell, as well.

  19. Graphene oxide/carbon nanoparticle thin film based IR detector: Surface properties and device characterization

    Directory of Open Access Journals (Sweden)

    Farzana Aktar Chowdhury

    2015-10-01

    Full Text Available This work deals with the synthesis, characterization, and application of carbon nanoparticles (CNP adorned graphene oxide (GO nanocomposite materials. Here we mainly focus on an emerging topic in modern research field presenting GO-CNP nanocomposite as a infrared (IR radiation detector device. GO-CNP thin film devices were fabricated from liquid phase at ambient condition where no modifying treatments were necessary. It works with no cooling treatment and also for stationary objects. A sharp response of human body IR radiation was detected with time constants of 3 and 36 sec and radiation responsivity was 3 mAW−1. The current also rises for quite a long time before saturation. This work discusses state-of-the-art material developing technique based on near-infrared photon absorption and their use in field deployable instrument for real-world applications. GO-CNP-based thin solid composite films also offer its potentiality to be utilized as p-type absorber material in thin film solar cell, as well.

  20. Bimodal Latex Effect on Spin-Coated Thin Conductive Polymer-Single-Walled Carbon Nanotube Layers.

    Science.gov (United States)

    Moradi, Mohammad-Amin; Larrakoetxea Angoitia, Katalin; van Berkel, Stefan; Gnanasekaran, Karthikeyan; Friedrich, Heiner; Heuts, Johan P A; van der Schoot, Paul; van Herk, Alex M

    2015-11-10

    We synthesize two differently sized poly(methyl methacrylate-co-tert-butyl acrylate) latexes by emulsion polymerization and mix these with a sonicated single-walled carbon nanotube (SWCNT) dispersion, in order to prepare 3% SWCNT composite mixtures. We spin-coat these mixtures at various spin-speed rates and spin times over a glass substrate, producing a thin, transparent, solid, conductive layer. Keeping the amount of SWCNTs constant, we vary the weight fraction of our smaller 30-nm latex particles relative to the larger 70-nm-sized ones. We find a maximum in the electrical conductivity up to 370 S/m as a function of the weight fraction of smaller particles, depending on the overall solid content, the spin speed, and the spin time. This maximum occurs at 3-5% of the smaller latex particles. We also find a more than 2-fold increase in conductivity parallel to the radius of spin-coating than perpendicular to it. Atomic force microscopy points at the existence of lanes of latex particles in the spin-coated thin layer, while large-area transmission electron microscopy demonstrates that the SWCNTs are aligned over a grid fixed on the glass substrate during the spin-coating process. We extract the conductivity distribution on the surface of the thin film and translate this into the direction of the SWCNTs in it.

  1. Fabrication and microwave shielding properties of free standing polyaniline-carbon fiber thin sheets

    Energy Technology Data Exchange (ETDEWEB)

    Joon, Seema [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Department of Physics, DCRUST Murthal, Sonepat, Haryana 130001 (India); PDM College of Engineering, Bahadurgarh, Haryana 124507 (India); Kumar, Rakesh [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); PDM College of Engineering, Bahadurgarh, Haryana 124507 (India); Singh, Avanish Pratap [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India); Shukla, Rajni [Department of Physics, DCRUST Murthal, Sonepat, Haryana 130001 (India); Dhawan, S.K., E-mail: skdhawan@mail.nplindia.ernet.in [Polymeric & Soft Material Section, CSIR-National Physical Laboratory, New Delhi 110012 (India)

    2015-06-15

    Attempt has been made to synthesize polyaniline-carbon fiber (PANI-CF) composite via in-situ emulsion polymerization using β-naphthalene sulphonic acid (NSA) which acts as both surfactant as well as dopant. Free standing PANI-CF thin sheets are prepared which have electrical conductivity ∼1.02 S/cm with improved mechanical strength and thermal stability. The scanning electron microscopy is used to study the surface morphology of the composites. Structural characterization is done by using XRD. The dielectric attributes (ε* = ε′ − iε″) of PANI-CF sheets are calculated using experimental S parameters (S{sub 11}, S{sub 12}) by Nicolson Ross Wier equations. It has been demonstrated that these sheets show maximum shielding effectiveness (SE) of 31.9 dB at 12.4 GHz frequency at a thickness of 1.5 mm. Free standing PANI-CF sheets so prepared have a potential for X-band microwave absorber application. - Highlights: • Free standing polyaniline-carbon fiber thin sheets fabricated for EMI shielding. • The mechanical strength of sheets improves with phenolic resin loading. • The dielectric parameters were calculated by Nicholson Ross Wier equations. • Sheets (1.5 mm thickness) demonstrate SE of 31.9 dB at 12.4 GHz frequency. • Sheets find potential application for X-band microwave absorption.

  2. 负偏压对六方氮化硼薄膜沉积特性的影响%Influence of negative bias on deposition characteristics of hexagonal boron nitride thin film

    Institute of Scientific and Technical Information of China (English)

    龚甜; 吴隽; 李涛涛; 龙晓阳; 祝柏林; 祁婷

    2015-01-01

    Hexagonal boron nitride(h-BN)thin films were deposited on the surface of n-type Si(100) substrates by radio frequency (RF)sputtering method.The effects of negative bias on the characteris-tics of deposited thin fim,such as growth mode,structure,surface roughness,film orientation and phase transition were studied by means of AFM,Raman,XPS and FTIR.The results show that h-BN thin films with relative low surface roughness,good crystallinity,c axis normal to the substrate and layer-by-layer growth mode are produced at a negative bias of 0 V.With the enhancement of neg-ative bias,the growth of thin film changes from layer-by-layer mode to island mode along with the in-crease of its surface roughness.High negative bias also induces the transformation of h-BN from met-astable E-BN and w-BN phase to c-BN phase,which leads to the chaos of BN phase system and is un-favorable for the deposition of high quality h-BN layer thin film.%利用射频磁控溅射法在 n 型 Si(100)衬底上沉积六方氮化硼薄膜(h-BN),采用 AFM、Raman、XPS、FT-IR 等技术研究负偏压对所沉积薄膜生长模式、结构、表面粗糙度、薄膜取向、相变等特性的影响。结果表明,当负偏压为0 V 时,沉积所得 h-BN 薄膜表面粗糙度较低、结晶性良好、c 轴垂直于衬底且以层状模式生长;随着负偏压的增加,薄膜由层状模式生长转变为岛状模式生长,表面粗糙度增加,且 h-BN 经亚稳相 E-BN 和 w-BN 向 c-BN 转变,使得 BN 薄膜相系统更加混乱,不利于高质量层状 h-BN 薄膜的获取。

  3. Compressive creep of silicon nitride with additives; Fluencia por compressao de nitreto de silicio aditivado

    Energy Technology Data Exchange (ETDEWEB)

    Shibuya, Newton Hissao; Cavalcanti, Celso Berilo Cidade; Piorino Neto, Francisco; Silva, Vitor Alexandre da; Silva, Cosme Roberto Moreira da [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil). Inst. de Aeronautica e Espaco

    1995-12-31

    Manufacturing of engine and turbine components made of silicon nitride based ceramics requires knowledge of thermochemical properties such as resistance to compressive creep. In order to characterize this property a compressive creep apparatus was assembled at AMR/IAE/CTA, able to work at 1450 deg C in a continuous mode. Test pieces were prepared from mixtures of silicon nitride with rare earth carbonate and aluminium nitride. These test pieces were pressureless sintered at 1750 deg C for 30 minutes under nitrogen atmosphere. Experiments showed that rare earth carbonate and aluminium nitride are suitable additives for silicon nitride. (author) 1 fig., 2 tabs.

  4. Examination of Plasma Nitriding Microstructure with Addition of Rare Earths

    Institute of Scientific and Technical Information of China (English)

    张津

    2004-01-01

    Medium-carbon alloy steel was plasma nitrided with rare earths La,Ce and Nd into the nitriding chamber respectively.The nitriding layer microstructures with and without rare earths were compared using optical microscope,normal SEM and high resolution SEM,as well as TEM.It was found that the extent of the influence on plasma nitriding varies with different contents of rare earth.The effect of plasma nitriding is benefit from adding of Ce or Nd.The formation of hard and brittle phase Fe2-3N can be prevented and the butterfly-like structure can be improved by adding Ce or Nd.However,pure La may prevent the diffusion of nitrogen and the formation of iron nitride,and reduce the depth of diffusion layer.

  5. Photoelectrochemical Immunosensor for Detection of Carcinoembryonic Antigen Based on 2D TiO2 Nanosheets and Carboxylated Graphitic Carbon Nitride.

    Science.gov (United States)

    Wang, Huan; Wang, Yaoguang; Zhang, Yong; Wang, Qi; Ren, Xiang; Wu, Dan; Wei, Qin

    2016-06-06

    Carcinoembryonic antigen (CEA) was used as the model, an ultrasensitive label-free photoelectrochemical immunosensor was developed using 2D TiO2 nanosheets and carboxylated graphitic carbon nitride (g-C3N4) as photoactive materials and ascorbic acid as an efficient electron donor. 2D TiO2 nanosheets was sythsized by surfactant self-assembly method and proved to have higher photoelectrochemical signals than TiO2 nanoparticles. Firstly, carboxylated g-C3N4 could be attached to 2D TiO2 nanosheets through the bond formed between carboxyl group of carboxylated g-C3N4 and TiO2. And the photocurrent of g-C3N4/TiO2 drastically enhances compared to carboxylated g-C3N4 and TiO2. Then, antibody of CEA was bonded to TiO2 through the dentate bond formed between carboxyl group of anti-CEA and TiO2, leading to the decrease of the photocurrents. As proven by PEC experiments and electrochemical impedance spectroscopy (EIS) analysis, the fabrication process of the immunosensor is successful. Under the optimal conditions, the intensity decreased linearly with CEA concentration in the range of 0.01~10 ng/mL. The detection limit is 2.1 pg/mL. The work provides an effective method for the detection of tumor markers and can be extended for the application in food safety and environmental monitoring analysis.

  6. 石墨相g-C3N4聚合物半导体光催化剂%Graphitic Carbon Nitride Polymeric Semiconductor Photocatalyst

    Institute of Scientific and Technical Information of China (English)

    吴海波; 张婷婷; 刘芹; 李靖

    2016-01-01

    Semiconductor photocatalysis could drive photocatalytic oxidation-reduction reactions to purify water, remove pollutions in soil and air, catalytic hydrogen production via sunlight. Semiconductor photocatalytic technology was regarded as a effective path to deal with the problem of environment pollution and energy shortage, In the process of application of photocatalysis technology, conjugated graphitic carbon nitride was a new type of visible light catalyst, only consisted of C and N metal-free elements which through sp2 hybridization. g-C3N4 was widely used owing to the fact of unique semiconductor band structure and excellent chemical stability. In this paper, g-C3N4 was described around structure, properties and research progress in photocatalytic field.%半导体光催化技术通过太阳能驱动化学反应净化水体、处理土壤和空气污染物、催化制氢,在解决环境污染和能源短缺等问题上具有重要的应用前景。在光催化技术的推广应用过程中,一种仅由C、N两种元素通过sp2杂化组成的共轭半导体氮化碳,因其独特的半导体能带结构和优异的化学稳定性,被作为一类不含金属成分的新型可见光催化剂,引起人们的广泛关注。本文介绍石墨相氮化碳的结构、性质及其在光催化领域的一些研究进展。

  7. Electron Cloud in Steel Beam Pipe vs Titanium Nitride Coated and Amorphous Carbon Coated Beam Pipes in Fermilab's Main Injector

    Energy Technology Data Exchange (ETDEWEB)

    Backfish, Michael

    2013-04-01

    This paper documents the use of four retarding field analyzers (RFAs) to measure electron cloud signals created in Fermilab’s Main Injector during 120 GeV operations. The first data set was taken from September 11, 2009 to July 4, 2010. This data set is used to compare two different types of beam pipe that were installed in the accelerator. Two RFAs were installed in a normal steel beam pipe like the rest of the Main Injector while another two were installed in a one meter section of beam pipe that was coated on the inside with titanium nitride (TiN). A second data run started on August 23, 2010 and ended on January 10, 2011 when Main Injector beam intensities were reduced thus eliminating the electron cloud. This second run uses the same RFA setup but the TiN coated beam pipe was replaced by a one meter section coated with amorphous carbon (aC). This section of beam pipe was provided by CERN in an effort to better understand how an aC coating will perform over time in an accelerator. The research consists of three basic parts: (a) continuously monitoring the conditioning of the three different types of beam pipe over both time and absorbed electrons (b) measurement of the characteristics of the surrounding magnetic fields in the Main Injector in order to better relate actual data observed in the Main Injector with that of simulations (c) measurement of the energy spectrum of the electron cloud signals using retarding field analyzers in all three types of beam pipe.

  8. Graphitic carbon nitrides modified hollow fiber solid phase microextraction for extraction and determination of uric acid in urine and serum coupled with gas chromatography-mass spectrometry.

    Science.gov (United States)

    Sun, Ying-pei; Chen, Juan; Qi, Huan-yang; Shi, Yan-ping

    2015-11-01

    An elevated uric acid (UA) in urine or serum can affect renal function and blood pressure, which is an indicator of gout, cardiovascular and renal diseases, hypertension, etc. In this work, a new type of mixed matrix membrane (MMM), based on graphitic carbon nitrides (g-CNs) and hollow fiber (HF), was prepared and combined with solid phase microextraction (SPME) mode to determine UA in urine and serum followed by gas chromatography-mass spectrometry (GC/MS). The porous g-CNs were dispersed in ammonia, and then the exfoliated g-CNs nanosheets were held in the pores of HF by capillary forces and sonification. The prepared g-CNs modified HF (g-CNs-HF) was immersed in biofluid directly to extract UA with SPME mode and the solvent-free mode is convenient for further derivatization and analysis. To achieve the highest extraction efficiency (EF), main extraction and derivatization parameters, such as g-CNs-HF immobilizing time, sonification power and time of extraction, derivatization and desorption time, were optimized. Under the optimum extraction conditions, a favorable linearity of UA was obtained in the range 0.1-200μgmL(-1) with correlation coefficients higher than 0.9990, and the average recoveries at three spiked levels of UA in urine and serum ranged from 80.7% to 121.6%, from 84.7% to 101.1%, respectively. The obtained results demonstrated the developed g-CNs-HF-SPME is a simple, rapid, cost-effective, solvent-free method for the analysis of UA in biofluid.

  9. Electrical and magnetic properties of electrodeposited nickel incorporated diamond-like carbon thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, B., E-mail: pandey.beauty@yahoo.com [Department of Applied Physics, Indian School of Mines, Dhanbad 826004 (India); Das, D. [UGC-DAE CSR, Sector III/LB-8, Bidhan Nagar, Kolkata 700098 (India); Kar, A.K. [Department of Applied Physics, Indian School of Mines, Dhanbad 826004 (India)

    2015-05-15

    Highlights: • Electrical and magnetic properties of DLC and Ni-DLC thin films are studied. • The ohmicity and conductivity of DLC films rise with nickel addition. • The ohmicity of Ni-DLC is enhanced with increase in dilution of electrolyte. • Dielectric loss is high for Ni-DLC and decreases with frequency till 100 kHz. • (m–H) and (m–T) curves of Ni-DLC indicate superparamagnetic behavior. - Abstract: Nanocomposite diamond-like carbon (DLC) thin films have been synthesized by incorporating nickel (Ni) nanoparticles in DLC matrix with varying concentration of nickel. DLC and Ni-DLC thin films have been deposited on ITO coated glass substrates employing low voltage electrodeposition method. Electrical properties of the samples were studied by measuring current–voltage characteristics and dielectric properties. The current approaches toward an ohmic behavior with metal addition. This tendency of increasing ohmicity is enhanced with increase in dilution of the electrolyte. The conductivity increases with Ni addition and interestingly it continues to increase with dilution of Ni concentration in the electrolyte in the range of our study. Magnetic properties for DLC and Ni-DLC thin film samples were examined by electron paramagnetic resonance (EPR) measurements and Super Conducting Quantum Interference Device (SQUID) measurements. g-Value for DLC is 2.074, whereas it decreases to 2.055 with Ni addition in the electrolyte. This decrement arises from the increased sp{sup 2} content in DLC matrix. The magnetic moment vs. magnetic field (m–H) curves of Ni-DLC indicate superparamagnetic behavior which may be due to ferromagnetic contribution from the incorporated nickel nanoparticles in the DLC matrix. The ZFC curve of Ni-DLC after the blocking temperature shows a combined contribution of ferromagnetic, superparamagnetic and paramagnetic nature of the materials persisting up to 300 K.

  10. Carbon-doped Sb{sub 2}S{sub 3} thin films: Structural, optical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Cardenas, Emma; Arato, A.; Das Roy, T.K.; Alan Castillo, G.; Krishnan, B. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Perez-Tijerina, E. [Facultad de Ciencias Fisico y Matematica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico)

    2009-01-15

    We report the modification of electrical properties of chemical-bath-deposited antimony sulphide (Sb{sub 2}S{sub 3}) thin films by thermal diffusion of carbon. Sb{sub 2}S{sub 3} thin films were obtained from a chemical bath containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3} salts at room temperature (27 C) on glass substrates. A carbon thin film was deposited on Sb{sub 2}S{sub 3} film by arc vacuum evaporation and the Sb{sub 2}S{sub 3}-C layer was subjected to heating at 300 C in nitrogen atmosphere or in low vacuum for 30 min. The value of resistivity of Sb{sub 2}S{sub 3} thin films was substantially reduced from 10{sup 8} {omega} cm for undoped condition to 10{sup 2} {omega} cm for doped thin films. The doped films, Sb{sub 2}S{sub 3}:C, retained the orthogonal stibnite structure and the optical band gap energy in comparison with that of undoped Sb{sub 2}S{sub 3} thin films. By varying the carbon content (wt%) the electrical resistivity of Sb{sub 2}S{sub 3} can be controlled in order to make it suitable for various opto-electronic applications. (author)

  11. Electrical and Electrochemical Properties of Nitrogen-Containing Tetrahedral Amorphous Carbon (ta-C) Thin Films

    Science.gov (United States)

    Yang, Xingyi

    Tetrahedral amorphous carbon (ta-C) is a diamond-like carbon (DLC) material comprised of a mixture of sp2 (˜40%) and sp3-bonded (˜60%) carbon domains. The physicochemical structure and electrochemical properties depend strongly on the sp2/sp3 bonding ratio as well as the incorporation of impurities, such as hydrogen or nitrogen. The ability to grow ta-C films at lower temperatures (25-100 °C) on a wider variety of substrates is a potential advantage of these materials as compared with diamond films. In this project, the basic structural and electrochemical properties of nitrogen-incorporated ta-C thin films will be discussed. The major goal of this work was to determine if the ta-C:N films exhibit electrochemical properties more closely aligned with those of boron-doped diamond (sp 3 carbon) or glassy carbon (amorphous sp2 carbon). Much like diamond, ta-C:N thin-film electrodes are characterized by a low background voltammetric current, a wide working potential window, relatively rapid electron-transfer kinetics for aqueous redox systems, such as Fe(CN) 6-3/-4 and Ru(NH3)6+3/+2 , and weak adsorption of polar molecules from solution. For example, negligible adsorption of methylene blue was found on the ta-C:N films in contrast to glassy carbon; a surface on which this molecule strongly adsorbs. The film microstructure was studied with x-ray photoelectron microscopy (XPS), visible Raman spectroscopy and electron-energy loss spectroscopy (EELS); all of which revealed the sp2-bonded carbon content increased with increasing nitrogen. The electrical properties of ta-C:N films were studied by four-point probe resistance measurement and conductive-probe AFM (CP-AFM). The incorporation of nitrogen into ta-C films increased the electrical conductivity primarily by increasing the sp2-bonded carbon content. CP-AFM showed the distribution of the conductive sp2-carbon on the film surface was not uniform. These films have potential to be used in field emission area. The

  12. Preferred orientation in carbon and boron nitride: Does a thermodynamic theory of elastic strain energy get it right. [C; BN

    Energy Technology Data Exchange (ETDEWEB)

    McCarty, K.F. (Sandia National Laboratories, Livermore, California 94550 (United States))

    1999-09-01

    We address whether the elastic strain-energy theory (minimizing the Gibbs energy of a stressed crystal) of McKenzie and co-workers [D. R. McKenzie and M. M. M. Bilek, J. Vac. Sci. Technol. A [bold 16], 2733 (1998)] adequately explains the preferred orientation observed in carbon and BN films. In the formalism, the Gibbs energy of the cubic materials diamond and cubic boron includes the strain that occurs when the phases form, through specific structural transformations, from graphitic precursors. This treatment violates the requirement of thermodynamics that the Gibbs energy be a path-independent, state function. If the cubic phases are treated using the same (path-independent) formalism applied to the graphitic materials, the crystallographic orientation of lowest Gibbs energy is not that observed experimentally. For graphitic (hexagonal) carbon and BN, an elastic strain approach seems inappropriate because the compressive stresses in energetically deposited films are orders of magnitude higher than the elastic limit of the materials. Furthermore, using the known elastic constants of either ordered or disordered graphitic materials, the theory does not predict the orientation observed by experiment. [copyright] [ital 1999 American Vacuum Society.

  13. Silicon nitride equation of state

    Science.gov (United States)

    Brown, Robert C.; Swaminathan, Pazhayannur K.

    2017-01-01

    This report presents the development of a global, multi-phase equation of state (EOS) for the ceramic silicon nitride (Si3N4).1 Structural forms include amorphous silicon nitride normally used as a thin film and three crystalline polymorphs. Crystalline phases include hexagonal α-Si3N4, hexagonal β-Si3N4, and the cubic spinel c-Si3N4. Decomposition at about 1900 °C results in a liquid silicon phase and gas phase products such as molecular nitrogen, atomic nitrogen, and atomic silicon. The silicon nitride EOS was developed using EOSPro which is a new and extended version of the PANDA II code. Both codes are valuable tools and have been used successfully for a variety of material classes. Both PANDA II and EOSPro can generate a tabular EOS that can be used in conjunction with hydrocodes. The paper describes the development efforts for the component solid phases and presents results obtained using the EOSPro phase transition model to investigate the solid-solid phase transitions in relation to the available shock data that have indicated a complex and slow time dependent phase change to the c-Si3N4 phase. Furthermore, the EOSPro mixture model is used to develop a model for the decomposition products; however, the need for a kinetic approach is suggested to combine with the single component solid models to simulate and further investigate the global phase coexistences.

  14. Nanostructured thin films and coatings mechanical properties

    CERN Document Server

    2010-01-01

    The first volume in "The Handbook of Nanostructured Thin Films and Coatings" set, this book concentrates on the mechanical properties, such as hardness, toughness, and adhesion, of thin films and coatings. It discusses processing, properties, and performance and provides a detailed analysis of theories and size effects. The book presents the fundamentals of hard and superhard nanocomposites and heterostructures, assesses fracture toughness and interfacial adhesion strength of thin films and hard nanocomposite coatings, and covers the processing and mechanical properties of hybrid sol-gel-derived nanocomposite coatings. It also uses nanomechanics to optimize coatings for cutting tools and explores various other coatings, such as diamond, metal-containing amorphous carbon nanostructured, and transition metal nitride-based nanolayered multilayer coatings.

  15. Thin film solid-state reactions forming carbides as contact materials for carbon-containing semiconductors

    Science.gov (United States)

    Leroy, W. P.; Detavernier, C.; Van Meirhaeghe, R. L.; Lavoie, C.

    2007-03-01

    Metal carbides are good candidates to contact carbon-based semiconductors (SiC, diamond, and carbon nanotubes). Here, we report on an in situ study of carbide formation during the solid-state reaction between thin films. The solid-state reaction was examined between 11 transition metals (W, Mo, Fe, Cr, V, Nb, Mn, Ti, Ta, Zr, and Hf) and an amorphous carbon layer. Capping layers (C or TiN) of different thicknesses were applied to prevent oxidation. Carbide formation is evidenced for nine metals and the phases formed have been identified (for a temperature ranging from 100to1100°C). W first forms W2C and then WC; Mo forms Mo2C; Fe forms Fe3C; Cr first forms metastable phases Cr2C and Cr3C2-x, and finally forms Cr3C2; V forms VCx; Nb transforms into Nb2C followed by NbC; Ti forms TiC; Ta first forms Ta2C and then TaC; and Hf transforms into HfC. The activation energy for the formation of the various carbide phases has been obtained by in situ x-ray diffraction.

  16. Impact of Argon gas on optical and electrical properties of Carbon thin films

    Science.gov (United States)

    Usman, Arslan; Rafique, M. S.; Shaukat, S. F.; Siraj, Khurram; Ashfaq, Afshan; Anjum, Safia; Imran, Muhammad; Sattar, Abdul

    2016-12-01

    Nanostructured thin films of carbon were synthesized and investigated for their electrical, optical, structural and surface properties. Pulsed Laser Deposition (PLD) technique was used for the preparation of these films under Argon gas environment. A KrF Laser (λ=248 nm) was used as source of ablation and plasma formation. It was observed that the carbon ions and the background gas environment has deep impact on the morphology as well as on the microstructure of the films. Time of Flight (TOF) method was used to determine the energies of the ablated carbon ions. The morphology of film surfaces deposited at various argon pressure was analysed using an atomic force microscope. The Raman spectroscopic measurement reveal that there is shift in phase from sp3 to sp2 and a decrease in FWHM of G band, which is a clear indication of enhanced graphitic clusters. The electrical resistivity was also reduced from 85.3×10-1 to 2.57×10-1 Ω-cm. There is an exponential decrease in band gap Eg of the deposited films from 1.99 to 1.37 eV as a function of argon gas pressure.

  17. The precipitation and effect of nano nitrides in HSLC steel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The existing forms of N and Al in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process), the precipitation thermodynamics and kinetics of AlN, and its effects on structure and mechanical property are studied. The experimental results show that only a small quantity of nitrogen is com- bined into AlN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen. Aluminum-nitride is mainly precipitated during the period of slow air cooling after coiling, but not during rolling and water cooling. The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005%―0.043%. The precipitation of AlN is not the main cause of grain refinement of HSLC steel produced by TSCR, nor is AlN the dominating precipitate that has precipitation strengthening effect. The nano nitrides are not pure AlN, but have complex compositions.

  18. The precipitation and effect of nano nitrides in HSLC steel

    Institute of Scientific and Technical Information of China (English)

    FU Jiei; LIU YangChun; WU HuaJie

    2008-01-01

    The existing forms of N and AI in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process),the precipitation thermodynamics and kinetics of AIN,and its effects on structure and mechanical property are stud-ied.The experimental results show that only a small quantity of nitrogen is com-bined into AIN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen.AIuminum-nitride is mainly precipitated during the period of slow air cooling after coiling,but not during rolling and water cooling.The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005%-0.043%.The precipitation of AIN is not the main cause of grain refinement of HSLC steel produced by TSCR,nor is AIN the dominating precipitate that has precipitation strengthening effect.The nano nitrides are not pure AIN,but have complex compositions.

  19. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-01-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design. PMID:28145438

  20. Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

    Energy Technology Data Exchange (ETDEWEB)

    Aïssa, B., E-mail: aissab@emt.inrs.ca [Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha (Qatar); Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada); Nedil, M. [Telebec Wireless Underground Communication Laboratory, UQAT, 675, 1ère Avenue, Val d' Or, Quebec J9P 1Y3 (Canada); Kroeger, J. [NanoIntegris & Raymor Nanotech, Raymor Industries Inc., 3765 La Vérendrye, Boisbriand, Quebec J7H 1R8 (Canada); Haddad, T. [Department of Mechanical Engineering, McGill University, Montreal, Quebec H3A 0B8 (Canada); Rosei, F. [Centre Energie, Matériaux et Télécommunications, INRS, 1650, Boulevard Lionel-Boulet Varennes, Quebec J3X 1S2 (Canada)

    2015-09-28

    We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 10{sup 4} and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 10{sup 4} s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices.

  1. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  2. Investigation of the Carbon Monoxide Gas Sensing Characteristics of Tin Oxide Mixed Cerium Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Muhammad B. Haider

    2012-02-01

    Full Text Available Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6–21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

  3. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors.

    Science.gov (United States)

    Kim, Bongjun; Geier, Michael L; Hersam, Mark C; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  4. Dry-Transfer of Aligned Multiwalled Carbon Nanotubes for Flexible Transparent Thin Films

    Directory of Open Access Journals (Sweden)

    Matthew Cole

    2012-01-01

    Full Text Available Herein we present an inexpensive facile wet-chemistry-free approach to the transfer of chemical vapour-deposited multiwalled carbon nanotubes to flexible transparent polymer substrates in a single-step process. By controlling the nanotube length, we demonstrate accurate control over the electrical conductivity and optical transparency of the transferred thin films. Uniaxial strains of up to 140% induced only minor reductions in sample conductivity, opening up a number of applications in stretchable electronics. Nanotube alignment offers enhanced functionality for applications such as polarisation selective electrodes and flexible supercapacitor substrates. A capacitance of 17 F/g was determined for supercapacitors fabricated from the reported dry-transferred MWCNTs with the corresponding cyclic voltagrams showing a clear dependence on nanotube length.

  5. Efficient coating of transparent and conductive carbon nanotube thin films on plastic substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ng, M H Andrew; Hartadi, Lysia T; Tan Huiwen; Poa, C H Patrick [Institute of Materials Research and Engineering, 3 Research Link, 117602 (Singapore)], E-mail: patrick-poa@imre.a-star.edu.sg

    2008-05-21

    Optically transparent and electrically conductive single-walled carbon nanotube (SWNT) thin films were fabricated at room temperature using a dip-coating technique. The film transparency and sheet resistance can be easily tailored by controlling the number of coatings. Aminopropyltriethoxysilane (APTS) was used as an adhesion promoter and, together with surfactant Triton X-100, greatly improved the SWNTs coating. Only five coats were required to obtain a sheet resistance of 2.05 {omega}{open_square} and film transparency of 84 %T. The dip-coated film after post-deposition treatment with nitric acid has a sheet resistance as low as 130 {omega}{open_square} at 69 %T. This technique is suitable for large-scale SWNT coating at room temperature and can be used on different types of substrates such as glass and plastics. This paper will discuss the role of the adhesion promoter and surfactant in the coating process.

  6. All-printed and transparent single walled carbon nanotube thin film transistor devices

    Science.gov (United States)

    Sajed, Farzam; Rutherglen, Christopher

    2013-09-01

    We present fully transparent single-walled all-carbon nanotube thin film transistors (SWCNT TFT) fabricated using low-cost inkjet printing methods. Such a demonstration provides a platform towards low cost fully printed transparent electronics. The SWCNT TFTs were printed with metallic and semiconducting SWCNT using a room temperature printing process, without the requirement of expensive cleanroom facilities. The unoptimized SWCNT TFTs fabricated exhibited an Ion/off ratio of 92 and mobility of 2.27 cm2V-1s-1 and transmissivity of 82%. The combination of both high electrical performance and high transparency make all-SWCNT TFTs desirable for next generation transparent display backplanes and products such as Google Glass.

  7. Cryogenic separation of hydrogen isotopes in single-walled carbon and boron-nitride nanotubes: insight into the mechanism of equilibrium quantum sieving in quasi-one-dimensional pores.

    Science.gov (United States)

    Kowalczyk, Piotr; Gauden, Piotr A; Terzyk, Artur P

    2008-07-17

    Quasi-one-dimensional cylindrical pores of single-walled boron nitride and carbon nanotubes efficiently differentiate adsorbed hydrogen isotopes at 33 K. Extensive path integral Monte Carlo simulations revealed that the mechanisms of quantum sieving for both types of nanotubes are quantitatively similar; however, the stronger and heterogeneous external solid-fluid potential generated from single-walled boron nitride nanotubes enhanced the selectivity of deuterium over hydrogen both at zero coverage and at finite pressures. We showed that this enhancement of the D(2)/H(2) equilibrium selectivity results from larger localization of hydrogen isotopes in the interior space of single-walled boron nitride nanotubes in comparison to that of equivalent single-walled carbon nanotubes. The operating pressures for efficient quantum sieving of hydrogen isotopes are strongly depending on both the type as well as the size of the nanotube. For all investigated nanotubes, we predicted the occurrence of the minima of the D(2)/H(2) equilibrium selectivity at finite pressure. Moreover, we showed that those well-defined minima are gradually shifted upon increasing of the nanotube pore diameter. We related the nonmonotonic shape of the D(2)/H(2) equilibrium selectivity at finite pressures to the variation of the difference between the average kinetic energy computed from single-component adsorption isotherms of H(2) and D(2). In the interior space of both kinds of nanotubes hydrogen isotopes formed solid-like structures (plastic crystals) at 33 K and 10 Pa with densities above the compressed bulk para-hydrogen at 30 K and 30 MPa.

  8. Functionalized carbon nanotubes in ZnO thin films for photoinactivation of bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Akhavan, O. [Department of Physics, Sharif University of Technology, P.O. Box 11155-9161, Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 14588-89694, Tehran (Iran, Islamic Republic of); Azimirad, R., E-mail: azimirad@yahoo.com [Malek-Ashtar University of Technology, Tehran (Iran, Islamic Republic of); Safa, S. [Department of Nanotechnology, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of)

    2011-10-17

    Highlights: {yields} Unfunctionalized and functionalized MWCNT/ZnO thin films were synthesized by sol-gel method. {yields} Zn-O-C carbonaceous bonds formed in the functionalized MWCNT/ZnO thin films. {yields} The functionalized MWCNT/ZnO had stronger photoinactivation of the bacteria than the unfunctionalize type. {yields} 10 wt% functionalized MWCNT content had the optimum antibacterial property. - Abstract: Two types of unfunctionalized and functionalized multi-wall carbon nanotubes (MWCNTs) were prepared to be applied in fabrication of MWCNT-ZnO nanocomposite thin films with various MWCNT contents. X-ray photoelectron spectroscopy indicated formation of functional groups on surface of the functionalized MWCNTs in the MWCNT-ZnO nanocomposite. Formation of the effective carbonaceous bonds between the ZnO and the MWCNTs was also investigated through photoinactivation of Escherichia coli bacteria on surface of the both unfunctionalized and functionalized MWCNT-ZnO nanocomposites. The functionalized MWCNT-ZnO nanocomposites showed significantly stronger photoinactivation of the bacteria than the unfunctionalized ones, for all of the various MWCNT contents (from 2 to 30 wt%). While the functionalized MWCNT-ZnO nanocomposites with the optimum MWCNT content of 10 wt% inactivated whole of the bacteria after 10 min UV-visible light irradiation, the unfunctionalized ones could inactivate only 63% of the bacteria under the same conditions. The significant enhancement of the photoinactivation of the bacteria onto the surface of the functionalized MWCNT-ZnO nanocomposites was assigned to charge transfer through Zn-O-C bands formed between the Zn atoms of the ZnO film and oxygen atoms of the carboxylic functional groups of the functionalized MWCNTs.

  9. Characterization of the Mechanical and Electromechanical Properties of Carbon Nanotube-Latex Thin Films

    Science.gov (United States)

    Wang, Long

    The safe, reliable, and efficient operation of structural systems can be undermined by various damage modes. To identify and respond to structural damage in a timely fashion, technologies for structural health monitoring (SHM) have been extensively studied and widely applied in practice. In this context, strain sensors play a crucial role in evaluating structural performance, as they can provide insights about internal stresses within structural components. As compared to conventional rigid and locally implemented strain sensors, piezoresistive nanostructured materials provide considerable opportunities for developing flexible, light-weight, and densely distributed sensors or "sensing skins." Although many types of nanomaterial-based strain sensors have been fabricated, most of them rely on complicated and expensive manufacturing procedures, which hinder their large-scale applications. To address the aforementioned limitations, this thesis proposes the development, optimization, and characterization of a type of spray-fabricated carbon nanotube (CNT)-based thin film strain sensor. By using spray coating or airbrushing, thin films can be coated and readily applied onto large structural surfaces. It was found that the mechanical and electrical properties of the nanocomposite films could be optimized by modifying CNT concentrations and conducting post-fabrication annealing. Overall, the CNT nanocomposite films possess favorable mechanical properties as well as stable and reversible electromechanical properties, rendering them promising candidates as strain sensors suitable for SHM applications.

  10. Thin graphite films formation by carbon precipitation in metals: diffusion approach

    Science.gov (United States)

    Shvets, Petr V.; Obraztsov, Alexander N.

    2016-03-01

    Thin graphite films attract significant interest due to their unique physical properties and potential applications. Chemical vapor deposition in the presence of metal catalysts is one of the most promising and widely used techniques to produce these films. There are many experimental works devoted to the material synthesis; however, the results are usually obtained by the trial-and-error method without a proper understanding of the processes behind the experiment. We theoretically analyze the carbon diffusion processes inside a metal substrate during the deposition. The theory allows interconnection of the deposition parameters with the thickness of produced graphite films. Numerically solving the diffusion equations for the real systems, we obtained a good correlation between simulations and experimental data. Based on our simulations, we made some conclusions about the formation of graphite films by the precipitation process. The numerical simulations were mostly done for the popular nickel substrates, but we also made some calculations for iron, showing that it also could be used to form thin graphite films under certain conditions.

  11. Epitaxial transformation of hcp–fcc Ti sublattices during nitriding processes of evaporated-Ti thin films due to nitrogen-implantation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu; Feng, Xiaoyi [Department of Metallurgy, Tohoku University, Aramaki-Aza-Aoba 02, Sendai 980-8579 (Japan); Kasukabe, Yoshitaka, E-mail: kasukabe@insc.tohoku.ac.jp [Department of Metallurgy, Tohoku University, Aramaki-Aza-Aoba 02, Sendai 980-8579 (Japan); Center for International Exchange, Tohoku University, 41 Kawauchi, Sendai 980-8576 (Japan); Yamamoto, Shunya; Yoshikawa, Masahito [Quantum Beam Science Directorate, JAEA, 1233 Watanuki, Takasaki 370-1292 (Japan); Fujino, Yutaka [Center for International Exchange, Tohoku University, 41 Kawauchi, Sendai 980-8576 (Japan)

    2013-11-15

    Highlights: ► Atomistic transformation processes of Ti films due to N-implantation have been clarified. ► The N{sub 2}{sup +} ions with 62 keV are implanted into as-deposited Ti film in the in-situ TEM. ► The hcp-fcc transformation is induced by the shear in the <0 1 · 0> direction on the (<0 0 · 1>) plane. ► The shear is promoted by the forming of covalent bonds and by the weakening of Ti–Ti bonds. -- Abstract: Atomistic transformation processes of Ti films due to N-implantation have been clarified through in-situ observations by using transmission electron microscope (TEM) along with molecular orbital calculations. The N{sub 2}{sup +} ions with 62 keV are implanted into as-deposited Ti films which consist of hcp-Ti and TiH{sub x} with preferred orientations, in the 400 kV analytic high resolution TEM combined with ion accelerators. Thus, titanium nitride (TiN{sub y}) films with preferred orientations are epitaxially formed by the inheritance of partial atomic arrangement of hcp-Ti or TiH{sub x} in as-deposited Ti films and by the occupation of octahedral sites by N atoms, which elucidates that epitaxial transformation of hcp–fcc Ti sublattices occurs. The analysis of electronic structure of Ti films during the implantation clarifies that octahedral sites of hcp-Ti with larger space have lower electron density, which leads to the invasion of N ions into octahedral sites. Thus, the hcp–fcc transformation is induced by the shear in the <0 1 · 0> direction on the (0 0 · 1) plane, promoted by the forming of covalent bonds mainly composed of hybridized orbitals due to combination of Ti3d and N2p orbitals, and by the weakening of Ti–Ti bonds.

  12. Adhesion improvement of hydrogenated diamond-like carbon thin films by pre-deposition plasma treatment of rubber substrate

    NARCIS (Netherlands)

    Bui, X.L.; Pei, Y.T.; Mulder, E.D.G.; Hosson, J.Th.M. De

    2009-01-01

    For reduction of friction and enhancement of wear resistance of dynamic rubber seals, thin films of hydrogenated diamond-like carbon (DLC) have been deposited on hydrogenated nitrile butadiene rubber (HNBR) via magnetron-enhanced plasma chemical vapor deposition (ME-PCVD). Pre-deposition plasma trea

  13. Infrared Dielectric Properties of Low-stress Silicon Nitride

    Science.gov (United States)

    Cataldo, Giuseppe; Beall, James A.; Cho, Hsiao-Mei; McAndrew, Brendan; Niemack, Michael D.; Wollack, Edward J.

    2012-01-01

    Silicon nitride thin films play an important role in the realization of sensors, filters, and high-performance circuits. Estimates of the dielectric function in the far- and mid-IR regime are derived from the observed transmittance spectra for a commonly employed low-stress silicon nitride formulation. The experimental, modeling, and numerical methods used to extract the dielectric parameters with an accuracy of approximately 4% are presented.

  14. Numerical investigation of the seismic detectability of carbonate thin beds in the Boom Clay formation

    Science.gov (United States)

    Carcione, José M.; Gei, Davide

    2016-07-01

    The present study evaluates the capacity of the Boom Clay as a host rock for disposal purposes, more precisely its seismic characterization, which may assess its long-term performance to store radioactive wastes. Although the formation is relatively uniform and homogeneous, there are embedded thin layers of septaria (carbonates) that may affect the integrity of the Boom Clay. Therefore, it is essential to locate these geobodies. The seismic data to characterize the Boom Clay has been acquired at the Kruibeke test site. The inversion, which allowed us to obtain the anisotropy parameters and seismic velocities of the clay, is complemented with further information such as log and laboratory data. The attenuation properties have been estimated from equivalent formations (having similar composition and seismic velocities). The inversion yields quite consistent results although the symmetry of the medium is unusual but physically possible, since the anisotropy parameter ɛ is negative. According to a time-domain calculation of the energy velocity at four frequency bands up to 900 Hz, velocity increases with frequency, a behaviour described by the Zener model. Then, we use this model to describe anisotropy and anelasticity that are implemented into the equation of motion to compute synthetic seismograms in the space-time domain. The technique is based on memory variables and the Fourier pseudospectral method. We have computed reflection coefficients of the septaria thin layer. At normal incidence, the P-wave coefficient vanishes at specific thicknesses of the layer and there is no conversion to the S wave. For example, calculations at 600 Hz show that for thicknesses of 1 m the septarium can be detected more easily since the amplitudes are higher (nearly 0.8). Converted PS waves have a high amplitude at large offsets (between 30° and 80°) and can be useful to identify the target on this basis. Moreover, we have investigated the effect of septaria embedded in the Boom

  15. Hydrophobic and high transparent honeycomb diamond-like carbon thin film fabricated by facile self-assembled nanosphere lithography

    Science.gov (United States)

    Peng, Kai-Yu; Wei, Da-Hua; Lin, Chii-Ruey; Yu, Yueh-Chung; Yao, Yeong-Der; Lin, Hong-Ming

    2014-01-01

    In this paper, we take advantage of a facile fabrication technique called self-assembled nanosphere lithography (SANSL) combining with proper two-step reactive ion etching (RIE) method and radio frequency (RF) sputtering deposition process for manufacturing honeycomb diamond-like carbon (DLC) thin film structures with hydrophobic and high transparent properties. It is found that the DLC thin films deposited on clean glass substrates at the RF power of 100 W with the surface roughness (Ra) of 2.08 nm and the ID/IG ratio of 1.96 are realized. With a fill-factor of 0.691, the honeycomb DLC patterned thin film shows the best transmittance performance of 87% in the wavelength of visible light, and the optimized contact angle measurement is ˜108°. Compared with the pure DLC thin film and original glass substrate, the hydrophobic property of the patterned DLC films is significantly improved by 80 and 160%, respectively.

  16. ZnO thin films on single carbon fibres fabricated by Pulsed Laser Deposition (PLD)

    Science.gov (United States)

    Krämer, André; Engel, Sebastian; Sangiorgi, Nicola; Sanson, Alessandra; Bartolomé, Jose F.; Gräf, Stephan; Müller, Frank A.

    2017-03-01

    Single carbon fibres were 360° coated with zinc oxide (ZnO) thin films by pulsed laser deposition using a Q-switched CO2 laser with a pulse duration τ ≈ 300 ns, a wavelength λ = 10.59 μm, a repetition frequency frep = 800 Hz and a peak power Ppeak = 15 kW in combination with a 3-step-deposition technique. In a first set of experiments, the deposition process was optimised by investigating the crystallinity of ZnO films on silicon and polished stainless steel substrates. Here, the influence of the substrate temperature and of the oxygen partial pressure of the background gas were characterised by scanning electron microscopy and X-ray diffraction analyses. ZnO coated carbon fibres and conductive glass sheets were used to prepare photo anodes for dye-sensitised solar cells in order to investigate their suitability for energy conversion devices. To obtain a deeper insight of the electronic behaviour at the interface between ZnO and substrate I-V measurements were performed.

  17. Structural and nanomechanical properties of nanocrystalline carbon thin films for photodetection

    Energy Technology Data Exchange (ETDEWEB)

    Rawal, Ishpal [Department of Physics, Kirorimal College, University of Delhi, Delhi 110007 (India); Panwar, Omvir Singh, E-mail: ospanwar@mail.nplindia.ernet.in; Tripathi, Ravi Kant; Chockalingam, Sreekumar [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Srivastava, Avanish Kumar [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India); Kumar, Mahesh [Ultrafast Optoelectronics and Tetrahertz Photonics Group, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110012 (India)

    2015-05-15

    This paper reports the effect of helium gas pressure upon the structural, nanomechanical, and photoconductive properties of nanocrystalline carbon thin (NCT) films deposited by the filtered cathodic jet carbon arc technique. High-resolution transmission electron microscopy images confirm the nanocrystalline nature of the deposited films with different crystallite sizes (3–7 nm). The chemical structure of the deposited films is further analyzed by x-ray photoelectron spectroscopy and Raman spectroscopy, which suggest that the deposited films change from graphitelike to diamondlike, increasing in sp{sup 3} content, with a minor change in the dilution of the inert gas (helium). The graphitic character is regained upon higher dilution of the helium gas, whereupon the films exhibit an increase in sp{sup 2} content. The nanomechanical measurements show that the film deposited at a helium partial pressure of 2.2 × 10{sup −4} has the highest value of hardness (37.39 GPa) and elastic modulus (320.50 GPa). At a light intensity of 100 mW/cm{sup 2}, the NCT films deposited at 2.2 × 10{sup −4} and 0.1 mbar partial pressures of helium gas exhibit good photoresponses of 2.2% and 3.6%, respectively.

  18. Expeditious low-temperature sintering of copper nanoparticles with thin defective carbon shells

    Science.gov (United States)

    Kim, Changkyu; Lee, Gyoungja; Rhee, Changkyu; Lee, Minku

    2015-04-01

    The realization of air-stable nanoparticles, well-formulated nanoinks, and conductive patterns based on copper is a great challenge in low-cost and large-area flexible printed electronics. This work reports the synthesis of a conductively interconnected copper structure via thermal sintering of copper inks at a low temperature for a short period of time, with the help of thin defective carbon shells coated onto the copper nanoparticles. Air-stable copper/carbon core/shell nanoparticles (typical size ~23 nm, shell thickness ~1.0 nm) are prepared by means of an electric explosion of wires. Gaseous oxidation of the carbon shells with a defective structure occurs at 180 °C, impacting the choice of organic solvents as well as the sintering conditions to create a crucial neck formation. Isothermal oxidation and reduction treatment at 200 °C for only about 10 min yields an oxide-free copper network structure with an electrical resistivity of 25.1 μΩ cm (14.0 μΩ cm at 250 °C). Finally, conductive copper line patterns are achieved down to a 50 μm width with an excellent printing resolution (standard deviation ~4.0%) onto a polyimide substrate using screen printing of the optimized inks.The realization of air-stable nanoparticles, well-formulated nanoinks, and conductive patterns based on copper is a great challenge in low-cost and large-area flexible printed electronics. This work reports the synthesis of a conductively interconnected copper structure via thermal sintering of copper inks at a low temperature for a short period of time, with the help of thin defective carbon shells coated onto the copper nanoparticles. Air-stable copper/carbon core/shell nanoparticles (typical size ~23 nm, shell thickness ~1.0 nm) are prepared by means of an electric explosion of wires. Gaseous oxidation of the carbon shells with a defective structure occurs at 180 °C, impacting the choice of organic solvents as well as the sintering conditions to create a crucial neck formation

  19. Recent trends in preparation and application of carbon nanotube-graphene hybrid thin films

    Science.gov (United States)

    Thanh Dang, Van; Dung Nguyen, Duc; Thanh Cao, Thi; Le, Phuoc Huu; Tran, Dai Lam; Phan, Ngoc Minh; Chuc Nguyen, Van

    2016-09-01

    The combination of one-dimensional (1D) carbon nanotubes (CNTs) and two-dimensional (2D) graphene materials to generate three-dimensional (3D) carbon nanotube-graphene hybrid thin films (CNGHTFs) has attracted great attention owing to their intriguing properties via the synergistic effects of these two materials on their electrical, optical, and electrochemical properties in comparison with their individual components. This review aims to provide a brief introduction of recent trends in preparation methodologies and some outstanding applications of CNGHTFs. It contains two main scientific subjects. The first of these is the research on preparation techniques of CNGHTFs, including reduction agent-assisted mechanical blending of reduced graphene oxide (rGO) and CNTs, hybridization methods for layer-by-layer (LBL) assembly of CNTs and rGO sheets, multi-step methods using combinations of a solution and chemical vapor deposition (CVD) processing, one-step growth of CNGHTFs by the CVD method, and modified CVD methods via thermal deposition of carbon source on catalyst surfaces. The advantages and disadvantages of the preparation methods of CNGHTFs are presented and discussed in detail. The second scientific subject of the review is the research on some outstanding applications of CNGHTFs in various research fields, including transparent conductors, electron field emitters, field-effect transistors, biosensors and supercapacitors. In most cases, the CNGHTFs showed superior performances than those of the pristine GO/graphene or CNT materials. Therefore, the CNGHTFs exhibit as high-potential materials for various practical applications. Opportunites and challenges in the fields are also presented.

  20. Deposition and thermal characterization of nano-structured aluminum nitride thin film on Cu-W substrate for high power light emitting diode package.

    Science.gov (United States)

    Cho, Hyun Min; Kim, Min-Sun

    2014-08-01

    In this study, we developed AlN thick film on metal substrate for hybrid type LED package such as chip on board (COB) using metal printed circuit board (PCB). Conventional metal PCB uses ceramic-polymer composite as electrical insulating layer. Thermal conductivities of such type dielectric film are typically in the range of 1~4 W/m · K depending on the ceramic filler. Also, Al or Cu alloy are mainly used for metal base for high thermal conduction to dissipate heat from thermal source mounted on metal PCB. Here we used Cu-W alloy with low thermal expansion coefficient as metal substrate to reduce thermal stress between insulating layer and base metal. AlN with polyimide (PI) powder were used as starting materials for deposition. We could obtain very high thermal conductivity of 28.3 W/m · K from deposited AlN-PI thin film by AlN-3 wt% PI powder. We made hybrid type high power LED package using AlN-PI thin film. We tested thermal performance of this film by thermal transient measurement and compared with conventional metal PCB substrate.

  1. Synthesis of Gallium Nitride Nanowire Bundles Using Carbon Nanotubes as Template%基于碳纳米管模板的氮化镓纳米线束合成

    Institute of Scientific and Technical Information of China (English)

    严晗; 刘胜; 甘志银; 宋晓辉; 徐静平

    2009-01-01

    通过金属有机物化学气相沉积方法在碳纳米管模板上生长氮化镓纳米线束.对所生长的纳米结构进行了扫描电镜和X射线能谱分析,结果显示氮化镓纳米晶体可以与碳纳米管形成纳米线束状复合物.纳米线柬状复合物直径为100~200 nm,长度为1.5~2.5 μm,纳米线的两端呈现尖角状.由于氨气很容易吸附在碳纳米管表面.可知所获得的纳米结构的初始生长机制为碳纳米管的表面氮化.该研究也证明金属有机物化学气相沉积将是用于制造化合物纳米结构材料的一项有效的技术.%Template growth of gallium nitride nanowires was demonstrated by metal organic chemical va-por deposition (MOCVD) with carbon nanotubes as templates in this paper. The fabricated nanostruc-tures were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectrosco-py (EDX). The results reveal that gallium nitride nanocrystals are grown on carbon nanotubes in the form of composite nanowire bundles. The composite nanowire bundles are 100-200 nm thick with typical lengths of 1.5-2.5 μm, while there is a shape with a slight tapering toward the tip of the wire. The growth mechanism of the obtained nanostructures is initiated by nitridation of carbon nanotube surfaces, due to the fact that ammonia is easily adsorbed on carbon nanotube surface. MOCVD is also suggested to be an effective technology for the fabrication of compound nanostructure material in the future.

  2. Facile Solid-State Synthesis Route to Metal Nitride Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Yinxiao DU; Ming LEI; Hui YANG

    2008-01-01

    By a facile and efficient solid-state reaction route using an organic reagent cyanamide (CN2H2) as a precursor with another one being metal oxides, we successfully synthesized seven technologically important metal nitrides including cubic VN, CrN, NbN, hexagonal GaN, AIN, BN, and WN at moderate temperatures. The experimental results show that cyanamide (CN2H2) is a powerfully reducing and nitridizing reagent and the metal oxides are completely converted into the corresponding nitride nanoparticles at lower temperatures than that reported in the conventional methods. It is found that CN2H2 can exhibit some interesting condensation processes, and the final products, highly active carbon nitride species, play a crucial role in the reducing and nitridizing processes.

  3. Large-scale complementary macroelectronics using hybrid integration of carbon nanotubes and IGZO thin-film transistors.

    Science.gov (United States)

    Chen, Haitian; Cao, Yu; Zhang, Jialu; Zhou, Chongwu

    2014-06-13

    Carbon nanotubes and metal oxide semiconductors have emerged as important materials for p-type and n-type thin-film transistors, respectively; however, realizing sophisticated macroelectronics operating in complementary mode has been challenging due to the difficulty in making n-type carbon nanotube transistors and p-type metal oxide transistors. Here we report a hybrid integration of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors to achieve large-scale (>1,000 transistors for 501-stage ring oscillators) complementary macroelectronic circuits on both rigid and flexible substrates. This approach of hybrid integration allows us to combine the strength of p-type carbon nanotube and n-type indium-gallium-zinc-oxide thin-film transistors, and offers high device yield and low device variation. Based on this approach, we report the successful demonstration of various logic gates (inverter, NAND and NOR gates), ring oscillators (from 51 stages to 501 stages) and dynamic logic circuits (dynamic inverter, NAND and NOR gates).

  4. Variable range hopping in single-wall carbon nanotube thin films: a processing-structure-property relationship study.

    Science.gov (United States)

    Luo, Sida; Liu, Tao; Benjamin, Shermane M; Brooks, James S

    2013-07-09

    By varying the ultrasonication and ultracentrifugation conditions, single-walled carbon nanotube (SWCNT) dispersions with a broad range of SWCNT length and diameter (L = 342-3330 nm; d = 0.5-12 nm) were prepared and characterized by a preparative ultracentrifuge method (PUM) and dynamic light scattering (DLS) technique. The well-characterized dispersions were then fabricated into SWCNT thin films by spray coating. Combined optical, spectroscopic, and temperature-dependent electrical measurements were performed to study the effect of SWCNT structures on the charge transport behavior of SWCNT thin films. Regardless of SWCNT size in the dispersion and the thin film thickness, the three-dimensional variable range hopping (3D VRH) conduction model was found to be appropriate in explaining the temperature-dependent sheet resistance results for all SWCNT thin films prepared in this study. More importantly, with the SWCNT structural information determined by the PUM method, we were able to identify a strong correlation between the length of SWCNTs and the 3D VRH parameter T0, the Mott characteristic temperature. When the SWCNT length is less than ∼700 nm, the T0 of SWCNT thin films shows a drastic increase, but when the length is greater than ~700 nm, T0 is only weakly dependent on the SWCNT length. Under the framework of traditional VRH, we further conclude that the electron localization length of SWCNT thin films shows a similar dependence on the SWCNT length.

  5. Annealing and deposition effects of the chemical composition of silicon rich nitride

    DEFF Research Database (Denmark)

    Andersen, Karin Nordström; Svendsen, Winnie Edith; Stimpel-Lindner, T.;

    2005-01-01

    Silicon-rich nitride, deposited by LPCVD, is a low stress amorphous material with a high refractive index. After deposition the silicon-rich nitride thin film is annealed at temperatures above 1100 oC to break N-H bonds, which have absorption peaks in the wavelength band important for optical tel...

  6. Metal contact effect on the performance and scaling behavior of carbon nanotube thin film transistors

    Science.gov (United States)

    Xia, Jiye; Dong, Guodong; Tian, Boyuan; Yan, Qiuping; Zhang, Han; Liang, Xuelei; Peng, Lianmao

    2016-05-01

    Metal-tube contact is known to play an important role in carbon nanotube field-effect transistors (CNT-FETs) which are fabricated on individual CNTs. Less attention has been paid to the contact effect in network type carbon nanotube thin film transistors (CNT-TFTs). In this study, we demonstrate that contact plays an even more important role in CNT-TFTs than in CNT-FETs. Although the Schottky barrier height at the metal-tube contact can be tuned by the work function of the metal, similar to the case in CNT-FETs, the contact resistance (Rc) forms a much higher proportion of the total resistance in CNT-TFTs. Interestingly, the contact resistivity was found to increase with channel length, which is a consequence of the percolating nature of the transport in CNT films, and this behavior does not exist in CNT-FETs and normal 2D Ohmic conductors. Electrical transport in CNT-TFTs has been predicted to scale with channel length by stick percolation theory. However, the scaling behavior is also impacted, or even covered up by the effect of Rc. Once the contact effect is excluded, the covered scaling behavior can be revealed correctly. A possible way of reducing Rc in CNT-TFTs was proposed. We believe the findings in this paper will strengthen our understanding of CNT-TFTs, and even accelerate the commercialization of CNT-TFT technology.Metal-tube contact is known to play an important role in carbon nanotube field-effect transistors (CNT-FETs) which are fabricated on individual CNTs. Less attention has been paid to the contact effect in network type carbon nanotube thin film transistors (CNT-TFTs). In this study, we demonstrate that contact plays an even more important role in CNT-TFTs than in CNT-FETs. Although the Schottky barrier height at the metal-tube contact can be tuned by the work function of the metal, similar to the case in CNT-FETs, the contact resistance (Rc) forms a much higher proportion of the total resistance in CNT-TFTs. Interestingly, the contact

  7. Molecular Surveillance of Viral Processes Using Silicon Nitride Membranes

    Directory of Open Access Journals (Sweden)

    Deborah F. Kelly

    2013-03-01

    Full Text Available Here we present new applications for silicon nitride (SiN membranes to evaluate biological processes. We determined that 50-nanometer thin films of SiN produced from silicon wafers were sufficiently durable to bind active rotavirus assemblies. A direct comparison of SiN microchips with conventional carbon support films indicated that SiN performs equivalent to the traditional substrate to prepare samples for Electron Microscopy (EM imaging. Likewise, SiN films coated with Ni-NTA affinity layers concentrated rotavirus particles similarly to affinity-coated carbon films. However, affinity-coated SiN membranes outperformed glow-discharged conventional carbon films 5-fold as indicated by the number of viral particles quantified in EM images. In addition, we were able to recapitulate viral uncoating and transcription mechanisms directed onto the microchip surfaces. EM images of these processes revealed the production of RNA transcripts emerging from active rotavirus complexes. These results were confirmed by the functional incorporation of radiolabeled nucleotides into the nascent RNA transcripts. Collectively, we demonstrate new uses for SiN membranes to perform molecular surveillance on life processes in real-time.

  8. Processing and properties of lead zirconate titanate thin films on gallium nitride and ruthenium by sol-gel and chemical vapor deposition

    Science.gov (United States)

    Cao, Wei

    The Pb(ZrxTi1-x)O3 (PZT) thin films are potential candidates for ferroelectric random access memory (FeRAM) devices and components for microelectromechanical systems (MEMS). For example, the PZT/GaN system is being explored as RF MEMS devices for insertion in RF communication systems. A reproducible sol-gel process was developed for the deposition of PZT films on wurtzite (0001) GaN/sapphire substrates. The composition, crystallography, and interfacial nanochemistry were evaluated by various characterization techniques. The PZT/GaN heterostructure exhibited a chemically sharp interface with insignificant interdiffusion between PZT and GaN layers. However, PZT in metal -ferroelectric -semiconductor (MFS) configuration showed lower capacitance and asymmetrical polarization hysteresis compared to PZT in metal-ferroelectric-metal configuration. Such a deviation was attributed to the high depolarization field (Edepol) within PZT. To mitigate this issue, a two-pronged approach was used. First, the calculated spatial distribution of the electric field and potential, which stem from all the charge densities within the MFS configuration, demonstrated that by adjusting controllable parameters, one can minimize Edepol and maximize polarization. Second, a robust metal-organic chemical vapor deposition (MOCVD) process was developed to fabricate high quality PZT thin films on GaN. In this experimental approach, phase-pure and highly (111) oriented PZT films were deposited on GaN/sapphire substrates by MOCVD. The orientation relationships of PZT/GaN system were determined using x-ray pole figure and high-resolution transmission electron microscopy (TEM). The nanochemistry of the PZT/GaN interface, studied using analytical TEM, indicated a chemically sharp interface with interdiffusion limited to a region below 5 nm. The properties of MOCVD-PZT on GaN are briefly compared with PZT by sol-gel processing, rf sputtering, and pulsed laser deposition. Additionally, a preliminary study

  9. Influence of Nitrided Layer on The Properties of Carbon Coatings Produced on X105CrMo17 Steel Under DC Glow-Discharge Conditions

    OpenAIRE

    Borowski, Tomasz; Ossowski, Maciej (OPI); Kowalczyk, Piotr; Maciej DUBEK; Agnieszka BROJANOWSKA; Krzysztof ROŻNIATOWSKI

    2016-01-01

    In most cases, machine components, which come in contact with each other, are made of steel. Common steel types include 100Cr6 and X105CrMo17 are widely used in rolling bearings, which are subjected to high static loads. However, more and more sophisticated structural applications require increasingly better performance from steel. The most popular methods for improving the properties of steel is carburisation or nitriding. Unfortunately, when very high surface properties of steel are require...

  10. Solution-processed zinc oxide nanoparticles/single-walled carbon nanotubes hybrid thin-film transistors

    Science.gov (United States)

    Liu, Fangmei; Sun, Jia; Qian, Chuan; Hu, Xiaotao; Wu, Han; Huang, Yulan; Yang, Junliang

    2016-09-01

    Solution-processed thin-film transistors (TFTs) are the essential building blocks for manufacturing the low-cost and large-area consumptive electronics. Herein, solution-processed TFTs based on the composites of zinc oxide (ZnO) nanoparticles and single-walled carbon nanotubes (SWCNTs) were fabricated by the methods of spin-coating and doctor-blading. Through controlling the weight of SWCNTs, the ZnO/SWCNTs TFTs fabricated by spin-coating demonstrated a field-effect mobility of 4.7 cm2/Vs and a low threshold voltage of 0.8 V, while the TFTs devices fabricated by doctor-blading technique showed reasonable electrical performance with a mobility of 0.22 cm2/Vs. Furthermore, the ion-gel was used as an efficient electrochemical gate dielectric because of its large electric double-layer capacitance. The operating voltage of all the TFTs devices is as low as 4.0 V. The research suggests that ZnO/SWCNTs TFTs have the potential applications in low-cost, large-area and flexible consumptive electronics, such as chemical-biological sensors and smart label.

  11. Bulging Behavior of Thin-walled Welded Low Carbon Steel Tubes

    Directory of Open Access Journals (Sweden)

    XIE Wen-cai

    2017-01-01

    Full Text Available In order to investigate the deformation behaviour of welded tubes during hydraulic bulging process,the hydraulic bulging tests of thin-walled welded low carbon steel tubes (STKM11A were conducted on the tube hydroformability testing unit.The thickness distribution,profiles of bulging area and the strain distribution were all obtained.Results show that the thickness reduction of weld zone is just 2.4%-5.5% while its effective strain is just 0.05-0.10,which is very small and negligible compared with the parent material and means that just the geometric position of weld zone is changed with the continuous bulging.The thinnest points are located on the both sides of weld seam symmetrically and the angle between the thinnest point and weld seam is about 30°,at which the necking has been occurred.When the length of bulging area increases,the fracture pressure,the thickness reduction and the ultimate expansion ratio all decrease,and the profile of the bulging area gradually steps away from the elliptical model which is powerless for the ratio of length to diameter up to 2.0.Moreover,the strain state of the tube is transformed from biaxial tension to plane strain state with the increasing length of bulging area,on the basis of this the forming limit diagram of welded STKM11A steel tubes can be established.

  12. Photostable epoxy polymerized carbon quantum dots luminescent thin films and the performance study

    Science.gov (United States)

    Zhang, Chang; Du, Lei; Liu, Cui; Li, Yunchuan; Yang, ZhenZhen; Cao, Yuan-Cheng

    High photostable epoxy polymerized carbon quantum dots (C-dots) luminescent thin films were prepared and their performances were compared with the CdTe quantum dots (QDs). First, water soluble C-dots (λem = 543.60 nm) were synthesized. Poly (ethylene glycol) diglycidyl ether (PEG) and diaminooctane were used as the polymer matrix to make the epoxy resin films. FT-IR spectra showed that there were vibration at 3448 cm-1 and 1644 cm-1 which contributed to -OH and -NH respectively. SEM observations showed that the polymerizations of the films were uniform and there were no structure defects. Mechanical tests showed the tensile modulus of C-dots composite films were 4.6, 4.9, 6.4 and 7.8 MPa respectively with corresponding 0%, 1%, 2% and 5% mass fraction of C-dots, while the tensile modulus of CdTe QDs films were 4.6 MPa under the same mass fraction of CdTe QDs. Compared with semiconductor QDs, the decay of quantum yield were 5% and 10% for the C-dots and CdTe QDs, respectively. The pictures in the continuous irradiation of 48 h showed that the C-dots film was more photostable. This study provides much helpful and profound towards the fluorescent enhancement films in the field of flexible displays.

  13. Deodorisation effect of diamond-like carbon/titanium dioxide multilayer thin films deposited onto polypropylene

    Energy Technology Data Exchange (ETDEWEB)

    Ozeki, K., E-mail: ozeki@mx.ibaraki.ac.jp [Department of Mechanical Engineering, Ibaraki University, 4-12-1, Nakanarusawa, Hitachi, Ibaraki 316-8511 (Japan); Frontier Research Center for Applied Atomic Sciences, 162-1 Shirakata, Toukai, Ibaraki 319-1106 (Japan); Hirakuri, K.K. [Applied Systems Engineering, Graduate School of Science and Engineering, Tokyo Denki University, Ishizaka, Hatoyama, Hiki, Saitama 350-0394 (Japan); Masuzawa, T. [Department of Mechanical Engineering, Ibaraki University, 4-12-1, Nakanarusawa, Hitachi, Ibaraki 316-8511 (Japan)

    2011-04-15

    Many types of plastic containers have been used for the storage of food. In the present study, diamond-like carbon (DLC)/titanium oxide (TiO{sub 2}) multilayer thin films were deposited on polypropylene (PP) to prevent flavour retention and to remove flavour in plastic containers. For the flavour removal test, two types of multilayer films were prepared, DLC/TiO{sub 2} films and DLC/TiO{sub 2}/DLC films. The residual gas concentration of acetaldehyde, ethylene, and turmeric compounds in bottle including the DLC/TiO{sub 2}-coated and the DLC/TiO{sub 2}/DLC-coated PP plates were measured after UV radiation, and the amount of adsorbed compounds to the plates was determined. The percentages of residual gas for acetaldehyde, ethylene, and turmeric with the DLC/TiO{sub 2} coated plates were 0.8%, 65.2% and 75.0% after 40 h of UV radiation, respectively. For the DLC/TiO{sub 2}/DLC film, the percentages of residual gas for acetaldehyde, ethylene and turmeric decreased to 34.9%, 76.0% and 85.3% after 40 h of UV radiation, respectively. The DLC/TiO{sub 2}/DLC film had a photocatalytic effect even though the TiO{sub 2} film was covered with the DLC film.

  14. Investigation of superfast deposition of metal oxide and Diamond-Like Carbon thin films by nanosecond Ytterbium (Yb+) fiber laser

    Science.gov (United States)

    Serbezov, V.; Sotirov, S.; Benkhouja, K.; Zawadzka, A.; Sahraoui, B.

    2013-11-01

    Metal oxide (MOx, M: titanium, magnesium) and Diamond-Like Carbon (DLC) thin films were synthesized by Pulsed Laser Deposition (PLD) at room temperature and low vacuum of 2 Pa for MOx and vacuum of 4 × 10-3 Pa for DLC films. A fiber based Ytterbium (Yb+) laser operating in the nanosecond regime at a repetition rate of 20 kHz was used as an ablation source. Dense and smooth thin films with a thickness from 120 to 360 nm and an area of up to 10 cm2 were deposited on glass and stainless steel substrates at high growth rates up to 2 nm/s for a laser intensity of 10-12 J/cm2. The thin films synthesis was compared for two fiber laser modes of operation, at a repetition rate of 20 kHz and with an additional modulation at 1 kHz. The morphology, chemical composition and structure of the obtained thin films were evaluated using optical microscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and Raman spectroscopy. The morphology of the MOx thin films and the deposition rate strongly depend on the fiber laser mode of operation. Very smooth surfaces were obtained for the metal oxide thin films deposited at lower deposition rates in the modulation mode at 1 kHz. The effect of the substrate on the DLC film structure was studied. The films deposited on dielectric substrates were identified as typical tetrahedral (ta-C) DLC with high sp3 content. DLC films on metal substrates were found typical a-C amorphous carbon films with mixing sp2/sp3 bonds.

  15. Adhesion improvement of hydrogenated diamond-like carbon thin films by pre-deposition plasma treatment of rubber substrate

    OpenAIRE

    Bui, X. L.; Pei, Y.T.; Mulder, E.D.G.; De Hosson, J. Th. M.

    2009-01-01

    For reduction of friction and enhancement of wear resistance of dynamic rubber seals, thin films of hydrogenated diamond-like carbon (DLC) have been deposited on hydrogenated nitrile butadiene rubber (HNBR) via magnetron-enhanced plasma chemical vapor deposition (ME-PCVD). Pre-deposition plasma treatment of HNBR substrate is proved to be crucial for the improvement of film performance due to enhanced interfacial adhesion. The columnar structure and the crack network formed during deposition e...

  16. Controlled Zn-mediated grafting of thin layers of bipodal diazonium salt on gold and carbon substrates.

    Science.gov (United States)

    Torréns, Mabel; Ortiz, Mayreli; Turner, Anthony P F; Beni, Valerio; O'Sullivan, Ciara K

    2015-01-07

    A controlled, rapid, and potentiostat-free method has been developed for grafting the diazonium salt (3,5-bis(4-diazophenoxy)benzoic acid tetrafluoroborate (DCOOH)) on gold and carbon substrates, based on a Zn-mediated chemical dediazonation. The highly stable thin layer organic platforms obtained were characterized by cyclic voltammetry, AFM, impedance, XP, and Raman spectroscopies. A dediazonation mechanism based on radical formation is proposed. Finally, DCOOH was proved as a linker to an aminated electroactive probe.

  17. Scanning tunneling microscopy of initial nitridation processes on oxidized Si(100) surface with radical nitrogen

    CERN Document Server

    Takahashi, R; Ikeda, H; Sakashita, M; Sakai, A; Yasuda, Y; Nakatsuka, O; Zaima, S

    2003-01-01

    We have investigated the initial nitridation processes on oxidized Si(100) with radical nitrogen at a substrate temperature of 850degC using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). It is found that the thin oxide layer suppresses the changes of original Si step structures during nitridation, and this effect critically depends on the growth conditions of the oxide layer. Comparison of the nitride island morphology to the case of the clean surface suggests that the migration of the precursor during nitridation is suppressed by the oxygen in the layer. (author)

  18. 45钢表面交流电场增强粉末法铝氮复合渗研究%Study on Alternating Current Field Enhanced Pack Aluminizing Plus Nitriding of 4 5 Carbon Steel Surface

    Institute of Scientific and Technical Information of China (English)

    张格; 谢飞; 潘建伟

    2016-01-01

    Alternating current field enhanced pack aluminizing plus nitriding (ACFEPAN)was carried out on 45 steel surface by applying ACF to the sample and treating agents with a pair of electrodes for overco-ming shortcomings of thin cases and long treating time in conventional pack aluminizing plus nitriding process.By investigating cases�structures,phases and hardness distributions of differently treated sam-ples,a preliminary study was made on characterizations of ACFEPAN on the surface of 45 steel.The re-sults show that the alternating current field (ACF)not only speed up aluminizing but also can avoid the formation of aluminium-rich phases during the alternating current field enhanced pack aluminizing.The a-luminium-rich phases formed by conventional pack aluminizing prevent the diffusion of N into the alumini-zing case during the later nitriding.By applying ACF to nitriding,the infiltration of nitrogen into the alu-minizing case is promoted,and N reacts with the aluminizing case to form AlN and Fe3 N.A case with an effective thickness of more than 150μm can be obtained by alternating current field enhanced 4h pack alu-minizing plus 4h nitriding.%针对现有铝氮复合渗工艺存在的渗层薄、渗扩时间长等问题,对置于两电极间的45钢试样与渗剂施加交流电场,进行交流电场增强粉末法铝氮复合渗。通过观察分析不同工艺所得试样的渗层组织、相结构与硬度分布,初步研究了交流电场增强45钢表面粉末法铝氮复合渗特性。结果表明:在复合渗的渗铝阶段施加交流电场不仅加快渗铝速度,还能够避免常规粉末法渗铝在表面形成富铝相对后续渗氮的阻碍;在后续渗氮中施加交流电场可促进氮渗入与渗铝层反应,在共渗层表层形成 AlN和 Fe3 N;通过将4 h 的交流电场增强渗铝与4 h 电场渗氮复合,能够获得有效厚度在150μm以上的复合渗层。

  19. Bench Scale Thin Film Composite Hollow Fiber Membranes for Post-Combustion Carbon Dioxide Capture

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Paul [General Electric Global Research, Niskayuna, NY (United States); Bhandari, Dhaval [General Electric Global Research, Niskayuna, NY (United States); Narang, Kristi [General Electric Global Research, Niskayuna, NY (United States); McCloskey, Pat [General Electric Global Research, Niskayuna, NY (United States); Singh, Surinder [General Electric Global Research, Niskayuna, NY (United States); Ananthasayanam, Balajee [General Electric Global Research, Niskayuna, NY (United States); Howson, Paul [General Electric Global Research, Niskayuna, NY (United States); Lee, Julia [General Electric Global Research, Niskayuna, NY (United States); Wroczynski, Ron [General Electric Global Research, Niskayuna, NY (United States); Stewart, Frederick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States); Klaehn, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); McNally, Joshua [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rownaghi, Ali [Georgia Inst. of Technology, Atlanta, GA (United States); Lu, Liu [Georgia Inst. of Technology, Atlanta, GA (United States); Koros, William [Georgia Inst. of Technology, Atlanta, GA (United States); Goizueta, Roberto [Georgia Inst. of Technology, Atlanta, GA (United States); Sethi, Vijay [Western Research Inst., Laramie, WY (United States)

    2015-04-01

    GE Global Research, Idaho National Laboratory (INL), Georgia Institute of Technology (Georgia Tech), and Western Research Institute (WRI) proposed to develop high performance thin film polymer composite hollow fiber membranes and advanced processes for economical post-combustion carbon dioxide (CO2) capture from pulverized coal flue gas at temperatures typical of existing flue gas cleanup processes. The project sought to develop and then optimize new gas separations membrane systems at the bench scale, including tuning the properties of a novel polyphosphazene polymer in a coating solution and fabricating highly engineered porous hollow fiber supports. The project also sought to define the processes needed to coat the fiber support to manufacture composite hollow fiber membranes with high performance, ultra-thin separation layers. Physical, chemical, and mechanical stability of the materials (individual and composite) towards coal flue gas components was considered via exposure and performance tests. Preliminary design, technoeconomic, and economic feasibility analyses were conducted to evaluate the overall performance and impact of the process on the cost of electricity (COE) for a coal-fired plant including capture technologies. At the onset of the project, Membranes based on coupling a novel selective material polyphosphazene with an engineered hollow fiber support was found to have the potential to capture greater than 90% of the CO2 in flue gas with less than 35% increase in COE, which would achieve the DOE-targeted performance criteria. While lab-scale results for the polyphosphazene materials were very promising, and the material was incorporated into hollow-fiber modules, difficulties were encountered relating to the performance of these membrane systems over time. Performance, as measured by both flux of and selectivity for CO2 over other flue gas constituents was found to deteriorate over time, suggesting a system that was

  20. Gallium nitride optoelectronic devices

    Science.gov (United States)

    Chu, T. L.; Chu, S. S.

    1972-01-01

    The growth of bulk gallium nitride crystals was achieved by the ammonolysis of gallium monochloride. Gallium nitride single crystals up to 2.5 x 0.5 cm in size were produced. The crystals are suitable as substrates for the epitaxial growth of gallium nitride. The epitaxial growth of gallium nitride on sapphire substrates with main faces of (0001) and (1T02) orientations was achieved by the ammonolysis of gallium monochloride in a gas flow system. The grown layers had electron concentrations in the range of 1 to 3 x 10 to the 19th power/cu cm and Hall mobilities in the range of 50 to 100 sq cm/v/sec at room temperature.