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Sample records for carbon nitride thin

  1. Oxidized carbon nitrides: water-dispersible, atomically thin carbon nitride-based nanodots and their performances as bioimaging probes.

    Science.gov (United States)

    Oh, Junghoon; Yoo, Ran Ji; Kim, Seung Yeon; Lee, Yong Jin; Kim, Dong Wook; Park, Sungjin

    2015-04-13

    Three-dimensional (3D) carbon nitride (C3 N4 )-based materials show excellent performance in a wide range of applications because of their suitable band structures. To realize the great promise of two-dimensional (2D) allotropes of various 3D materials, it is highly important to develop routes for the production of 2D C3 N4 materials, which are one-atom thick, in order to understand their intrinsic properties and identify their possible applications. In this work, water-dispersible, atomically thin, and small carbon nitride nanodots were produced using the chemical oxidation of graphitic C3 N4 . Various analyses, including X-ray diffraction, X-ray photoelectron, Fourier-transform infrared spectroscopy, and combustion-based elemental analysis, and thermogravimetric analysis, confirmed the production of 3D oxidized C3 N4 materials. The 2D C3 N4 nanodots were successfully exfoliated as individual single layers; their lateral dimension was several tens of nanometers. They showed strong photoluminescence in the visible region as well as excellent performances as cell-imaging probes in an in vitro study using confocal fluorescence microscopy.

  2. Deposit of thin films of nitrided amorphous carbon using the laser ablation technique

    International Nuclear Information System (INIS)

    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 -4 Torr until 7.5 x 10 -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)

  3. [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.

  4. Synthesis and characterization of thin films of nitrided amorphous carbon deposited by laser ablation

    International Nuclear Information System (INIS)

    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 sp2 and sp3 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)

  5. CRYSTALLINE CARBON NITRIDE THIN FILMS DEPOSITED BY MICROWAVE PLASMA CHEMICAL VAPOR DEPOSITION

    Institute of Scientific and Technical Information of China (English)

    Zhang Yong-ping; Gu You-song; Chang Xiang-rong; Tian Zhong-zhuo; Shi Dong-xia; Zhang Xiu-fang; Yuan lei

    2000-01-01

    The crystalline carbon nitride thin films have beenprepared on Si (100) substrates using microwave plasma chemical vapordeposition technique. The experimental X-ray diffractionpattern of the films prepared contain all the strongpeaks of -C3N4 and -C3N4, but most of thepeaks are overlapped.The films are composed of -C3N4 and -C3N4.The N/C atomic ratio isclose to the stoichiometric value 1.33. X-ray photoelectronspectroscopic analysis indicated that thebinding energies of C 1s and N 1s are 286.43eV and 399.08 eV respectively.The shifts are attributed to the polarization of C-N bond. Bothobserved Raman and Fourier transform infrared spectra werecompared with the theoretical calculations. The results support theexistence of C-N covalent bond in - and -C3N4 mixture.

  6. Boron nitride converted carbon fiber

    Energy Technology Data Exchange (ETDEWEB)

    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)

    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.

  11. Carbon Nitride Thin Films Deposited by Plasma Assisted Nd∶YAG Laser Ablation of Graphite in N2+H2 Atmosphere

    Institute of Scientific and Technical Information of China (English)

    YU Wei; WANG Shufang; ZHANG Lianshui; LI Xiaowei; FU Guangsheng

    2001-01-01

    Carbon nitride thin films are deposited on silicon wafers by 532 nm Nd∶YAG laser ablation of graphite in the N2+H2 atmosphere assisted by a dc glow discharge plasma at a higher gas pressure of about 4.0 kPa. The properties of the thin films are investigated by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and X-ray diffraction (XRD). The results show that the deposited films are composed of α-C3N4, β-C3N4 phase and have the N/C atomic ratio of 2.01. The optical emission spectroscopy (OES) studies indicate that the introduction of a dc glow discharge and the adoption of a higher gas pressure during the film deposition are favorable to the net generation of the atomic N, CN radicals and N+2 in B2Σ+u excited state in the plasma, which are considered to play a major role in the synthesis of carbon nitride.

  12. Hard carbon nitride and method for preparing same

    Science.gov (United States)

    Haller, Eugene E.; Cohen, Marvin L.; Hansen, William L.

    1992-01-01

    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.

  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. Graphitic Carbon Nitride Supported Catalysts for Polymer Electrolyte Fuel Cells.

    OpenAIRE

    Mansor, N.; Jorge, A. B.; Corà, F.; Gibbs, C.; Jervis, R.; Mcmillan, P. F.; X. Wang; Brett, D. J.

    2014-01-01

    Graphitic carbon nitrides are investigated for developing highly durable Pt electrocatalyst supports for polymer electrolyte fuel cells (PEFCs). Three different graphitic carbon nitride materials were synthesized with the aim to address the effect of crystallinity, porosity, and composition on the catalyst support properties: polymeric carbon nitride (gCNM), poly(triazine) imide carbon nitride (PTI/Li(+)Cl(-)), and boron-doped graphitic carbon nitride (B-gCNM). Following accelerated corrosion...

  15. 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.

  16. 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 coating planar, curved, and line-of-sight-obscured silicon nitride surfaces. PMID:24999923

  17. 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

  18. 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.

  19. 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.

  20. Graphitic Carbon Nitride Supported Catalysts for Polymer Electrolyte Fuel Cells.

    Science.gov (United States)

    Mansor, Noramalina; Jorge, A Belen; Corà, Furio; Gibbs, Christopher; Jervis, Rhodri; McMillan, Paul F; Wang, Xiaochen; Brett, Daniel J L

    2014-04-01

    Graphitic carbon nitrides are investigated for developing highly durable Pt electrocatalyst supports for polymer electrolyte fuel cells (PEFCs). Three different graphitic carbon nitride materials were synthesized with the aim to address the effect of crystallinity, porosity, and composition on the catalyst support properties: polymeric carbon nitride (gCNM), poly(triazine) imide carbon nitride (PTI/Li(+)Cl(-)), and boron-doped graphitic carbon nitride (B-gCNM). Following accelerated corrosion testing, all graphitic carbon nitride materials are found to be more electrochemically stable compared to conventional carbon black (Vulcan XC-72R) with B-gCNM support showing the best stability. For the supported catalysts, Pt/PTI-Li(+)Cl(-) catalyst exhibits better durability with only 19% electrochemical surface area (ECSA) loss versus 36% for Pt/Vulcan after 2000 scans. Superior methanol oxidation activity is observed for all graphitic carbon nitride supported Pt catalysts on the basis of the catalyst ECSA.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Magnetron sputtering of thin nitride films

    OpenAIRE

    Kola, Prashanthi V

    1995-01-01

    The objective in this investigation was to design and commission a magnetron sputter deposition system and investigate the properties of hard coatings for mechanical and biomedical applications. The deposition of titanium (Ti) and titanium nitride (TiN) was undertaken as part of the commissioning tests and further work was conducted on the effect of the deposition parameters on the properties of TiN, specifically for biocompatible applications. A thorough understanding of the deposition proce...

  6. 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.

  7. Mechanisms of Low-Temperature Nitridation Technology on a TaN Thin Film Resistor for Temperature Sensor Applications.

    Science.gov (United States)

    Chen, Huey-Ru; Chen, Ying-Chung; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Chu, Tian-Jian; Shih, Chih-Cheng; Chuang, Nai-Chuan; Wang, Kao-Yuan

    2016-12-01

    In this letter, we propose a novel low-temperature nitridation technology on a tantalum nitride (TaN) thin film resistor (TFR) through supercritical carbon dioxide (SCCO2) treatment for temperature sensor applications. We also found that the sensitivity of temperature of the TaN TFR was improved about 10.2 %, which can be demonstrated from measurement of temperature coefficient of resistance (TCR). In order to understand the mechanism of SCCO2 nitridation on the TaN TFR, the carrier conduction mechanism of the device was analyzed through current fitting. The current conduction mechanism of the TaN TFR changes from hopping to a Schottky emission after the low-temperature SCCO2 nitridation treatment. A model of vacancy passivation in TaN grains with nitrogen and by SCCO2 nitridation treatment is eventually proposed to increase the isolation ability in TaN TFR, which causes the transfer of current conduction mechanisms. PMID:27251325

  8. Mechanisms of Low-Temperature Nitridation Technology on a TaN Thin Film Resistor for Temperature Sensor Applications

    Science.gov (United States)

    Chen, Huey-Ru; Chen, Ying-Chung; Chang, Ting-Chang; Chang, Kuan-Chang; Tsai, Tsung-Ming; Chu, Tian-Jian; Shih, Chih-Cheng; Chuang, Nai-Chuan; Wang, Kao-Yuan

    2016-06-01

    In this letter, we propose a novel low-temperature nitridation technology on a tantalum nitride (TaN) thin film resistor (TFR) through supercritical carbon dioxide (SCCO2) treatment for temperature sensor applications. We also found that the sensitivity of temperature of the TaN TFR was improved about 10.2 %, which can be demonstrated from measurement of temperature coefficient of resistance (TCR). In order to understand the mechanism of SCCO2 nitridation on the TaN TFR, the carrier conduction mechanism of the device was analyzed through current fitting. The current conduction mechanism of the TaN TFR changes from hopping to a Schottky emission after the low-temperature SCCO2 nitridation treatment. A model of vacancy passivation in TaN grains with nitrogen and by SCCO2 nitridation treatment is eventually proposed to increase the isolation ability in TaN TFR, which causes the transfer of current conduction mechanisms.

  9. 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.

  10. Novel nanoscroll structures from carbon nitride layers.

    Science.gov (United States)

    Perim, Eric; Galvao, Douglas S

    2014-08-01

    Nanoscrolls (papyrus-like nanostructures) are very attractive structures for a variety of applications, owing to their tunable diameter and large accessible surface area. They have been successfully synthesized from different materials. In this work, we investigate, through fully atomistic molecular dynamics simulations, the dynamics of scroll formation for a series of graphene-like carbon nitride (CN) two-dimensional systems: g-CN, triazine-based g-C3 N4 , and heptazine-based g-C3 N4 . Our results show that stable nanoscrolls can be formed for each of these structures. Possible synthetic routes to produce these nanostructures are also addressed. PMID:24819427

  11. Solvothermal synthesis of crystalline carbon nitrides

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A solvothermal reaction of anhydrous C3N3Cl3 and Li3N using benzene as the solvent has been carried out to prepare crystalline carbon nitrides successfully at 350℃ and 5-6 MPa. X-ray diffraction (XRD) indicated that the major part of our brown sample was mainly composed of α-C3N4 and β-C3N4 with lattice parameters of a = 0. 65 nm, c = 0.47 nm for α-C3N4 and a = 0.644 nm, c = 0. 246 nm for β-C3N4, which match the latest ab-initio calculations quite well. The N/C ratio in the powder is about 0.66. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses suggested the presence of both single and double carbon-nitrogen bonds. The kinetics effects of our solvothermal reaction to prepare crystalline carbon nitrides are also discussed chiefly.

  12. A chromium nitride/carbon nitride containing graphitic carbon nanocapsule hybrid as a Pt-free electrocatalyst for oxygen reduction.

    Science.gov (United States)

    Zhao, Lu; Wang, Lei; Yu, Peng; Zhao, Dongdong; Tian, Chungui; Feng, He; Ma, Jing; Fu, Honggang

    2015-08-11

    Chromium nitride nanoparticles supported on graphitic carbon nanocapsules containing carbon nitride (CrN/GC) have been synthesized by a solvothermal-assisted ion-exchange route. As a Pt-free catalyst, the CrN/GC hybrid exhibits superior activity, stability, methanol immunity and a dominant 4-electron pathway towards oxygen reduction reaction.

  13. Beryllium nitride thin film grown by reactive laser ablation

    OpenAIRE

    G. Soto; Diaz, J.A.; Machorro, R.; Reyes-Serrato, A.; de la Cruz, W.

    2001-01-01

    Beryllium nitride thin films were grown on silicon substrates by laser ablating a beryllium foil in molecular nitrogen ambient. The composition and chemical state were determined with Auger (AES), X-Ray photoelectron (XPS) and energy loss (EELS) spectroscopies. A low absorption coefficient in the visible region, and an optical bandgap of 3.8 eV, determined by reflectance ellipsometry, were obtained for films grown at nitrogen pressures higher than 25 mTorr. The results show that the reaction ...

  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. Grafting titanium nitride surfaces with sodium styrene sulfonate thin films.

    Science.gov (United States)

    Zorn, Gilad; Migonney, Véronique; Castner, David G

    2014-09-01

    The importance of titanium nitride lies in its high hardness and its remarkable resistance to wear and corrosion, which has led to its use as a coating for the heads of hip prostheses, dental implants and dental surgery tools. However, the usefulness of titanium nitride coatings for biomedical applications could be significantly enhanced by modifying their surface with a bioactive polymer film. The main focus of the present work was to graft a bioactive poly(sodium styrene sulfonate) (pNaSS) thin film from titanium nitride surfaces via a two-step procedure: first modifying the surface with 3-methacryloxypropyltrimethoxysilane (MPS) and then grafting the pNaSS film from the MPS modified titanium through free radical polymerization. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used after each step to characterize success and completeness of each reaction. The surface region of the titanium nitride prior to MPS functionalization and NaSS grafting contained a mixture of titanium nitride, oxy-nitride, oxide species as well as adventitious surface contaminants. After MPS functionalization, Si was detected by XPS, and characteristic MPS fragments were detected by ToF-SIMS. After NaSS grafting, Na and S were detected by XPS and characteristic NaSS fragments were detected by ToF-SIMS. The XPS determined thicknesses of the MPS and NaSS overlayers were ∼1.5 and ∼1.7 nm, respectively. The pNaSS film density was estimated by the toluidine blue colorimetric assay to be 260 ± 70 ng/cm(2). PMID:25280842

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

    Institute of Scientific and Technical Information of China (English)

    XU Jun; GAO Peng; DING Wan-yu; LI Xin; DENG Xin-lu; DONG Chuang

    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 transform 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.

  17. 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.

  18. 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.

  19. 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.

  20. Nanocrystalline-graphene-tailored hexagonal boron nitride thin films.

    Science.gov (United States)

    Lee, Kang Hyuck; Shin, Hyeon-Jin; Kumar, Brijesh; Kim, Han Sol; Lee, Jinyeong; Bhatia, Ravi; Kim, Sang-Hyeob; Lee, In-Yeal; Lee, Hyo Sug; Kim, Gil-Ho; Yoo, Ji-Beom; Choi, Jae-Young; Kim, Sang-Woo

    2014-10-20

    Unintentionally formed nanocrystalline graphene (nc-G) can act as a useful seed for the large-area synthesis of a hexagonal boron nitride (h-BN) thin film with an atomically flat surface that is comparable to that of exfoliated single-crystal h-BN. A wafer-scale dielectric h-BN thin film was successfully synthesized on a bare sapphire substrate by assistance of nc-G, which prevented structural deformations in a chemical vapor deposition process. The growth mechanism of this nc-G-tailored h-BN thin film was systematically analyzed. This approach provides a novel method for preparing high-quality two-dimensional materials on a large surface. PMID:25204810

  1. 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...... by replacement of the nitride ions with oxide ions in the molten carbonate electrolyte....

  2. Triple templating of graphitic carbon nitride to enhance photocatalytic properties

    Directory of Open Access Journals (Sweden)

    Z. Yang

    2016-01-01

    Full Text Available Graphitic carbon nitride materials show some promising properties for applications such as photocatalytic water splitting. However, the conversion efficiency is still low due to factors such as a low surface area and limited light absorption. In this paper, we describe a “triple templating” approach to generating porous graphitic carbon nitride. The introduction of pores on several length-scales results in enhanced photocatalytic properties.

  3. 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.

  4. 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.

  5. Electron field emission from boron nitride thin films

    Science.gov (United States)

    Encarnacion, Pedro Aron

    A systematic study of electron field emission from boron nitride thin films is presented, establishing nanostructured thin film cubic boron nitride (cBN) as a robust and chemically inert material with a low effective workfunction, able to sustain electron emission in a space plasma environment. RHEED data shows the films as polycrystalline, composed of partially oriented crystallites of cBN with predominantly (001) crystallographic texture relative to the Si substrate. FTIR data showed our films to be overwhelmingly cBN, with a volume fraction greater than 75%. AFM images show nanostructures relevant to field enhancement, with a mean feature height of 79 nm, mean RMS roughness of 19 nm, average grain size of 155 nm2 +/- 84 nm2, and a mean feature radius of ˜7 nm. The results are discussed in the light of current theoretical models for electron field emission, including particulars relevant to semiconductors and nanostructured surfaces. Electron emission thresholds were measured from under 1V/mum up to just under 20V/mum in vacuum. Voltage sweep measurements were made both in vacuo and in various gas environments relevant to space applications. Repeatability of emission results was demonstrated, albeit with indications of threshold shifts, possibly due to desorption of adsorbate impurities. Time dependence measurements at constant extraction field show stable field emission over periods of extended operation. An effective barrier height ow of approximately 9.3 meV for the as-grown cBN thin films is measured, based on the application of the generalised Fowler-Nordheim theory to the electron field emission measurements, and employing a model of the film surface as an ensemble of self-assembled protruberances in the shape of prolate half ellipsoids of revolution on a flat surface. To our knowledge, this is the first experimental determination of this important parameter for cBN films. It appears that the low value of o w measured for cBN is a direct consequence of the

  6. 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.

  7. 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.

  8. Triazine-based graphitic carbon nitride: a two-dimensional semiconductor.

    Science.gov (United States)

    Algara-Siller, Gerardo; Severin, Nikolai; Chong, Samantha Y; Björkman, Torbjörn; Palgrave, Robert G; Laybourn, Andrea; Antonietti, Markus; Khimyak, Yaroslav Z; Krasheninnikov, Arkady V; Rabe, Jürgen P; Kaiser, Ute; Cooper, Andrew I; Thomas, Arne; Bojdys, Michael J

    2014-07-14

    Graphitic carbon nitride has been predicted to be structurally analogous to carbon-only graphite, yet with an inherent bandgap. We have grown, for the first time, macroscopically large crystalline thin films of triazine-based, graphitic carbon nitride (TGCN) using an ionothermal, interfacial reaction starting with the abundant monomer dicyandiamide. The films consist of stacked, two-dimensional (2D) crystals between a few and several hundreds of atomic layers in thickness. Scanning force and transmission electron microscopy show long-range, in-plane order, while optical spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations corroborate a direct bandgap between 1.6 and 2.0 eV. Thus TGCN is of interest for electronic devices, such as field-effect transistors and light-emitting diodes.

  9. Symmetric organization of self-assembled carbon nitride

    International Nuclear Information System (INIS)

    A scheme for creating 'flower-like' nanostructures of carbon nitride is described that involves the self-assembly of nanocrystals following laser ablation of a solid graphite target immersed in aqueous ammonia solution. The primary nanocrystals possess rod-like symmetry, and then self-assemble upon drying to form nanoleaf or nanopetal shaped structures. Samples were characterized using x-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), x-ray photoelectron microscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The analyses confirmed their composition to be consistent with that of crystalline β-phase carbon nitride. The morphologies of the carbon nitride nanostructures depended strongly on the synthesis conditions and upon the conditions under which the aqueous suspension of ablated particles were dried

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Templateless Infrared Heating Process for Fabricating Carbon Nitride Nanorods with Efficient Photocatalytic H2 Evolution.

    Science.gov (United States)

    Li, Hui-Jun; Qian, Dong-Jin; Chen, Meng

    2015-11-18

    The bottom-up fabrication of carbon nitride nanorods is realized through the direct infrared heating of dicyandiamide. The approach requires no templates or extra organics. The controlled infrared heating has a major influence on the morphology of the obtained carbon nitrides. The precursors assemble into carbon nitride nanorods at low power levels, and they grow into nanoplates at high power levels. The formation mechanism of the carbon nitride nanorods is proposed to be a kinetically driven process, and the photocatalytic activity of the carbon nitride nanorods prepared at 50% power for hydrogen evolution is about 2.9 times that of carbon nitride nanoplates at 100% power. Structural, optical, and electronic analysis demonstrates that the enhancement is primarily attributed to the elimination of structural defects and the improved charge-carrier separation in highly condensed and oriented carbon nitride nanorods.

  15. DC conductivity of silicon nitride based carbon-ceramic composites

    Directory of Open Access Journals (Sweden)

    B. Fényi

    2007-12-01

    Full Text Available The silicon nitride ceramics are usually known as strongly refractory and enduring materials and have typical electrically insulating properties. If the reinforcing phase of ceramic composite (that is mainly put in the material to improve mechanical properties is a good electrical conductor, it is worth to investigate the composite in electrical aspect. In this work carbon nanotubes, black-carbon and graphite were added to the basic silicon nitride ceramic and the electrical conductivity of the prepared carbon-ceramic composites was determined. The conductivity of the ceramic composites with different type and concentration of the carbon additives was observed by applying four point DC resistance measurements. Insulator and conductor composites in a wide conductivity range can be produced depending on the type and quantity of the additives. The additive types as well as the sintering parameters have influence on the basic electrical properties of the conductor composites.

  16. Preparation and characterization of morph-genetic aluminum nitride/carbon composites from filter paper

    International Nuclear Information System (INIS)

    Morph-genetic aluminum nitride/carbon composites with cablelike structure were prepared from filter paper template through the surface sol-gel process and carbothermal nitridation reaction. The resulting materials have a hierarchical structure originating from the morphology of cellulose paper. The aluminum nitride/carbon composites have the core-shell microstructure, the core is graphitic carbon, and the shell is aluminum nitride nanocoating formed by carbothermal nitridation reduction of alumina with the interfacial carbon in nitrogen atmosphere. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscope were employed to characterize the structural morphology and phase compositions of the final products

  17. 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.

  18. Reactive DC Magnetron Sputtering Deposition of Copper Nitride Thin Film

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Copper nitride thin film was deposited on glass substrates by reactive DC (direct current) magnetron sputtering at a 0.5 Pa N2 partial pressure and different substrate temperatures. The as-prepared film, characterized with X-Ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy measurements, showed a composed structure of Cu3N crystallites with anti-ReO3 structure and a slight oxidation of the resulted film.The crystal structure and growth rate of Cu3N films were affected strongly by substrate temperature. The preferred crystalline orientation of Cu3N films were (111) and (200) at RT, 100℃. These peaks decayed at 200℃ and 300℃ only Cu (111) peak was noticed. Growth of Cu3N films at 100℃ is the optimum substrate temperature for producing high-quality (111) Cu3N films. The deposition rate of Cu3N films estimated to be in range of 18-30 nm/min increased while the resistivity and the microhardness of Cu3N films decreased when the temperature of glass substrate increased.

  19. 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.

  20. 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.

  1. Synthesis of carbon black/carbon nitride intercalation compound composite for efficient hydrogen production.

    Science.gov (United States)

    Wu, Zhaochun; Gao, Honglin; Yan, Shicheng; Zou, Zhigang

    2014-08-21

    The photoactivity of g-C3N4 is greatly limited by its high recombination rate of photogenerated carriers. Coupling g-C3N4 with other materials has been demonstrated to be an effective way to facilitate the separation and transport of charge carriers. Herein we report a composite of conductive carbon black and carbon nitride intercalation compound synthesized through facile one-step molten salt method. The as-prepared carbon black/carbon nitride intercalation compound composite was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), UV-vis absorption spectrum and photoluminescence spectroscopy (PL). The carbon black nanoparticles, homogeneously dispersed on the surface of carbon nitride intercalation compound, efficiently enhanced separation and transport of photogenerated carriers, thus improving the visible-light photocatalytic activity. The composite of 0.5 wt% carbon black and carbon nitride intercalation compound exhibited a H2 production rate of 68.9 μmol h(-1), which is about 3.2 times higher than hydrogen production on pristine carbon nitride intercalation compound.

  2. Silicon nitride thin-films by RF sputtering : application on solid state lithium batteries

    OpenAIRE

    Sousa, R.; Ribeiro, J. F.; Sousa, J. A.; Montenegro, R. T.; L.M. Gonçalves; Correia, J.H.

    2013-01-01

    Silicon nitride is the most common barrier material to protect microsystems from atmosphere, usually deposited through CVD techniques. In this paper our aim is to highlight the advantages brought by using PVD techniques, namely RF sputtering, to deposit silicon nitride thin-films. In particular, we intend to protect microsystems fabricated only by PVD techniques and avoid the necessity of a second CVD chamber to do the microsystem coating. The influence of gases (Ar/N2) during deposition was ...

  3. 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

  4. Degradation of a tantalum filament during the hot-wire CVD of silicon nitride thin films

    International Nuclear Information System (INIS)

    Electron backscatter diffraction revealed that during the hot-wire deposition of silicon nitride, a tantalum filament partially transformed to some of its nitrides and silicides. The deposition of an encapsulating silicon nitride layer occurred at the cooler filament ends. Time-of-flight secondary ion mass spectroscopy disclosed the presence of hydrogen, nitrogen and silicon containing ions within the aged filament bulk. Hardness measurements revealed that the recrystallized tantalum core experienced significant hardening, whereas the silicides and nitrides were harder but more brittle. Crack growth, porosity and the different thermal expansion amongst the various phases are all enhanced at the hotter centre regions, which resulted in failure at these areas. - Highlights: • Tantalum filament degrades and fails during hot-wire CVD of silicon nitride thin films. • An encapsulating silicon nitride layer is deposited at the cooler ends. • Electron backscatter diffraction reveals Ta-silicides and -nitrides with a Ta core. • Filament failure occurs at hot centre regions due to different mechanical properties of Ta, its silicides and nitrides

  5. 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.

  6. Thermal and quantum phase slips in niobium-nitride nanowires based on suspended carbon nanotubes

    Science.gov (United States)

    Masuda, Kohei; Moriyama, Satoshi; Morita, Yoshifumi; Komatsu, Katsuyoshi; Takagi, Tasuku; Hashimoto, Takayuki; Miki, Norihisa; Tanabe, Takasumi; Maki, Hideyuki

    2016-05-01

    Superconducting nanowires have attracted considerable attention due to their unique quantum-mechanical properties, as well as their potential as next-generation quantum nanodevices, such as single-photon detectors, phase-slip (PS) qubits, and other hybrid structures. In this study, we present the results of one-dimensional (1D) superconductivity in nanowires fabricated by coating suspended carbon nanotubes with a superconducting thin niobium nitride (NbN) film. In the resistance-temperature characteristic curves, hallmarks of 1D superconductivity with PS events are observed with unconventional negative magnetoresistance. We also confirm that a crossover occurs between thermal and quantum PSs as the temperature is lowered.

  7. Photoluminescence and Raman Spectroscopy Studies of Carbon Nitride Films

    OpenAIRE

    Hernández-Torres, J.; Gutierrez-Franco, A.; P. G. González; L. García-González; Hernandez-Quiroz, T.; Zamora-Peredo, L.; V.H. Méndez-García; A. Cisneros-de la Rosa

    2016-01-01

    Amorphous carbon nitride films with N/C ratios ranging from 2.24 to 3.26 were deposited by reactive sputtering at room temperature on corning glass, silicon, and quartz as substrates. The average chemical composition of the films was obtained from the semiquantitative energy dispersive spectroscopy analysis. Photoluminescence measurements were performed to determine the optical band gap of the films. The photoluminescence spectra displayed two peaks: one associated with the substrate and the ...

  8. Grafting titanium nitride surfaces with sodium styrene sulfonate thin films

    OpenAIRE

    Zorn, Gilad; MIGONNEY, Véronique; Castner, David G.

    2014-01-01

    The importance of titanium nitride lies in its high hardness and its remarkable resistance to wear and corrosion, which has led to its use as a coating for the heads of hip prostheses, dental implants and dental surgery tools. However, the usefulness of titanium nitride coatings for biomedical applications could be significantly enhanced by modifying their surface with a bioactive polymer film. The main focus of the present work was to graft a bioactive poly(sodium styrene sulf...

  9. 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.

  10. 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.

  11. Mathematical Model of Prediction of Nitrogen Pickup in Nitriding Process of Low Carbon Ferromanganese

    OpenAIRE

    Ghali, Saeed

    2014-01-01

    Low carbon ferromanganese was nitrided through gas-solid reaction. The nitriding process has been carried out on lab scale at temperature range 800°C–950°C at different nitrogen pressures. Temperature, time, and partial nitrogen pressure of nitriding process of fine low carbon ferromanganese were investigated. Nitrogen content, in weight percent, was more than 9%. MATLAB software was used to derive mathematical model to predict nitrogen content as a function of temperature and nitrogen pressu...

  12. 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.

  13. Low-temperature nitriding of iron through a thin nickel layer

    NARCIS (Netherlands)

    Inia, D.K.; Propper, M.H.; Arnoldbik, W.M.; Vredenberg, A.M.; Boerma, D.O

    1997-01-01

    We present a new method for nitriding iron at low temperatures. First, iron is coated with a thin layer of nickel (similar to 36 nm), after which it is exposed to an NH3 atmosphere at temperatures below 300 degrees C. Underneath the nickel layer epsilon-Fe3-xN is formed at temperatures as low as 225

  14. Magnetic graphitic carbon nitride: its application in the C–H activation of amines

    Science.gov (United States)

    Magnetic graphitic carbon nitride, Fe@g-C3N4, has been synthesized by adorning graphitic carbon nitride (g-C3N4) support with iron oxide via non-covalent interaction. The magnetically recyclable catalyst showed excellent reactivity for expeditious C-H activation and cyanation of ...

  15. Plasma-Chemical Synthesis of Nanosized Powders-Nitrides, Carbides, Oxides, Carbon Nanotubes and Fullerenes

    Institute of Scientific and Technical Information of China (English)

    Katerina ZAHARIEVA; Gheorghi VISSOKOV; Janis GRABIS; Slavcho RAKOVSKY

    2012-01-01

    In this article the plasma-chemical synthesis of nanosized powders (nitrides, car- bides, oxides, carbon nanotubes and fullerenes) is reviewed. Nanosized powders - nitrides, carbides, oxides, carbon nanotubes and fullerenes have been successfully produced using different techniques, technological apparatuses and conditions for their plasma-chemical synthesis.

  16. Selective Breaking of Hydrogen Bonds of Layered Carbon Nitride for Visible Light Photocatalysis.

    Science.gov (United States)

    Kang, Yuyang; Yang, Yongqiang; Yin, Li-Chang; Kang, Xiangdong; Wang, Lianzhou; Liu, Gang; Cheng, Hui-Ming

    2016-08-01

    Selective breaking of the hydrogen bonds of graphitic carbon nitride can introduce favorable features, including increased band tails close to the band edges and the creation of abundant pores. These features can simultaneously improve the three basic processes of photocatalysis. As a consequence, the photocatalytic hydrogen-generation activity of carbon nitride under visible light is drastically increased by tens of times.

  17. 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.

  18. 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.

  19. Characterization of Ultra Thin Oxynitride Formed by Radical Nitridation with Slot Plane Antenna Plasma

    Science.gov (United States)

    Sugawara, Takuya; Matsuyama, Seiji; Sasaki, Masaru; Nakanishi, Toshio; Murakawa, Shigemi; Katsuki, Jiro; Ozaki, Shigenori; Tada, Yoshihide; Ohta, Tomohiro; Yamamoto, Nobuhiko

    2005-03-01

    We investigated the plasma nitridation mechanisms for an ultra-thin gate oxynitride (SiON) formation to extend the downscaling limit of equivalent oxide thickness (EOT). Using the slot plane antenna (SPA) plasma nitridation system, excellent gate SiON properties were obtained with low gate leakage and good carrier mobility down to less than 12 Å. From electrical and physical analysis results, the nitridation mechanism was discussed, which suggested that a control of oxygen partial pressure is important to achieve EOT reduction. A low electron temperature (Te) process under high-pressure condition leads to improved Gm and NBTI performance, which indicates that the reduction of a plasma damage under nitridation processes improve the performance and reliability of ultra thin SiON film. With optimized nitridation processes, the mobility degradation of nMOSFET is only 8% at \\textit{EOT}=11 Å. The NBTI reliability of pMOSFET is improved by more than 1 order compared with a low-pressure, high Te condition.

  20. Carbon nanotube quantum dots on hexagonal boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Baumgartner, A., E-mail: andreas.baumgartner@unibas.ch; Abulizi, G.; Gramich, J.; Schönenberger, C. [Institute of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland); Watanabe, K.; Taniguchi, T. [National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)

    2014-07-14

    We report the fabrication details and low-temperature characteristics of carbon nanotube (CNT) quantum dots on flakes of hexagonal boron nitride (hBN) as substrate. We demonstrate that CNTs can be grown on hBN by standard chemical vapor deposition and that standard scanning electron microscopy imaging and lithography can be employed to fabricate nanoelectronic structures when using optimized parameters. This proof of concept paves the way to more complex devices on hBN, with more predictable and reproducible characteristics and electronic stability.

  1. 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.

  2. 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

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

    International Nuclear Information System (INIS)

    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 sp2 carbon dominated structures, and diversiform bonds (N-C, N≡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 sp2C 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.

  4. 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.

  5. Lithium storage on carbon nitride, graphenylene and inorganic graphenylene.

    Science.gov (United States)

    Hankel, Marlies; Searles, Debra J

    2016-06-01

    We present results of density functional theory calculations on the lithium (Li) ion storage capacity of three different two dimensional porous graphene-like membranes. The graphitic carbon nitride membrane, g-CN, is found to have a large Li storage capacity of at least 813 mA h g(-1) (LiCN). However, it is also found that the Li interacts very strongly with the membrane indicating that this is most likely irreversible. According to the calculations, graphenylene or biphenylene carbon (BPC) has a storage capacity of 487 mA h g(-1) (Li1.5C6) which is higher than that for graphite. We also find that Li is very mobile on these materials and does not interact as strongly with the membrane making it a more suitable anode material. Inorganic graphenylene, which is a boron nitride analog of graphenylene, shows very low binding energies, much lower than the cohesive energy of lithium, and it appears to be unsuitable as an anode material for lithium ion batteries. We discuss how charge transfer leads to the very different behaviour observed in these three similar materials.

  6. 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 ...

  7. Electrophoretic Deposition of Carbon Nitride Layers for Photoelectrochemical Applications.

    Science.gov (United States)

    Xu, Jingsan; Shalom, Menny

    2016-05-25

    Electrophoretic deposition (EPD) is used for the growth of carbon nitride (C3N4) layers on conductive substrates. EPD is fast, environmentally friendly, and allows the deposition of negatively charged C3N4 with different compositions and chemical properties. In this method, C3N4 can be deposited on various conductive substrates ranging from conductive glass and carbon paper to nickel foam possessing complex 3D geometries. The high flexibility of this approach enables us to readily tune the photophysical and photoelectronic properties of the C3N4 electrodes. The advantage of this method was further illustrated by the tailored construction of a heterostructure between two complementary C3N4, with marked photoelectrochemical activity.

  8. Template-free synthesis of porous graphitic carbon nitride/carbon composite spheres for electrocatalytic oxygen reduction reaction.

    Science.gov (United States)

    Fu, Xiaorui; Hu, Xiaofei; Yan, Zhenhua; Lei, Kaixiang; Li, Fujun; Cheng, Fangyi; Chen, Jun

    2016-01-28

    Porous graphitic carbon nitride/carbon composite spheres were synthesized using melamine and cyanuric acid, and glucose as the carbon nitride and carbon precursor, respectively. The 3D hierarchical composites efficiently catalyzed the oxygen reduction reaction with an onset potential of 0.90 V and a kinetic current density of 23.92 mA cm(-2). These merit their promising applications in fuel cells and metal-air batteries.

  9. Effects of applied radio frequency power on low-temperature catalytic-free nanostructured carbon nitride films by rf PECVD

    Science.gov (United States)

    Ritikos, Richard; Othman, Maisara; Abdul Rahman, Saadah

    2016-06-01

    Low-temperature catalytic-free carbon nitride, CN x nanostructured thin films were produced by using radio frequency (rf) plasma-enhanced chemical vapor deposition employing a parallel-plate electrode configuration. The effects of varying applied rf power, P rf (30-100 W), on the formation of these structures were studied. Aligned nanostructured CN x films were produced at P rf as low as 40 W, but uniform highly vertical-aligned CN x nanorods were produced at P rf of 60 and 80 W. This was induced by the presence of high ion bombardment on the growing films and the preferential bonding of isonitrile to aromatic bonds in the nanostructures. It was also observed that nitrogen incorporation is highest in this range and the structure and bonding in the nanostructure reflects those of typical polymeric/amorphous carbon nitride films.

  10. Thin films of pure vanadium nitride: Evidence for anomalous non-faradaic capacitance

    Science.gov (United States)

    Bondarchuk, Oleksandr; Morel, Alban; Bélanger, Daniel; Goikolea, Eider; Brousse, Thierry; Mysyk, Roman

    2016-08-01

    An impressive gravimetric capacitance of 1300 F g-1 (surface capacitance ∼3.3 mF cm-2) reported by Choi et al., 2006 for nanosized vanadium nitride has stimulated considerable interest in vanadium nitride as a potential electrode material for energy storing systems - supercapacitors. The postulated mechanism of charge storage in vanadium nitride materials involves redox reactions in the thin surface layer of vanadium oxide while the core vanadium nitride serves exclusively as a conducting platform. In this study we have synthesized pure oxygen-free vanadium nitride films and have found that they are capable of delivering a surface capacitance of up to ∼3 mF cm-2 at a potential scan rate of 3 mV s-1 and ∼2 mF cm-2 at a potential scan rate of 1 V s-1 in aqueous electrolytes. Combining electrochemical testing with X-ray photoelectron spectroscopy characterization has revealed that redox reactions play no or little role in the electrochemical response of pure VN, in contrast to the common wisdom stemming from the electrochemical response of oxygen-containing films. An alternative charge storage mechanism - space charge accumulation in a subsurface layer of ∼100 nm - was put forward to explain the experimentally observed capacitance of VN films in aqueous electrolytes.

  11. 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.

  12. 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

  13. 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.

  14. Optical and Electronic Properties of 2D Graphitic Carbon-Nitride and Carbon Enriched Alloys

    Science.gov (United States)

    Therrien, Joel; Li, Yancen; Schmidt, Daniel; Masaki, Michael; Syed, Abdulmannan

    The two-dimensional form of graphitic carbon-nitride (gCN) has been successfully synthesized using a simple CVD process. In it's pure form, the carbon to nitrogen ratio is 0.75. By adding a carbon bearing gas to the growth environment, the C/N ratio can be increased, ultimately reaching the pure carbon form: graphene. Unlike attempts at making a 2D alloy system out of BCN, the CN system does not suffer from phase segregation and thus forms a homogeneous alloy. The synthesis approach and electronic and optical properties will be presented for the pure gCN and a selection of alloy compositions.

  15. Crystallinity Modulation of Layered Carbon Nitride for Enhanced Photocatalytic Activities.

    Science.gov (United States)

    Wang, Jianhai; Shen, Yanfei; Li, Ying; Liu, Songqin; Zhang, Yuanjian

    2016-08-22

    As an emerging metal-free semiconductor, covalently bonded carbon nitride (CN) has attracted much attention in photocatalysis. However, drawbacks such as a high recombination rate of excited electrons and holes hinder its potential applications. Tailoring the crystallinity of semiconductors is an important way to suppress unwanted charge recombination, but has rarely been applied to CN so far. Herein, a simple method to synthesize CN of high crystallinity by protonation of specific intermediate species during conventional polymerization is reported. Interestingly, the as-obtained CN exhibited improved photocatalytic activities of up to seven times those of the conventional bulk CN. This approach, with only a slight change to the conventional method, provides a facile way to effectively regulate the crystallinity of bulk CN to improve its photocatalytic activities and sheds light on large-scale industrial applications of CN with high efficiency for sustainable energy.

  16. 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.

  17. Graphitic carbon nitride "reloaded": emerging applications beyond (photo)catalysis.

    Science.gov (United States)

    Liu, Jian; Wang, Hongqiang; Antonietti, Markus

    2016-04-21

    Despite being one of the oldest materials described in the chemical literature, graphitic carbon nitride (g-C3N4) has just recently experienced a renaissance as a highly active photocatalyst, and the metal-free polymer was shown to be able to generate hydrogen under visible light. The semiconductor nature of g-C3N4 has triggered tremendous endeavors on its structural manipulation for enhanced photo(electro)chemical performance, aiming at an affordable clean energy future. While pursuing the stem of g-C3N4 related catalysis (photocatalysis, electrocatalysis and photoelectrocatalysis), a number of emerging intrinsic properties of g-C3N4 are certainly interesting, but less well covered, and we believe that these novel applications outside of conventional catalysis can be favorably exploited as well. Thanks to the general efforts devoted to the exploration and enrichment of g-C3N4 based chemistry, the boundaries of this area have been possibly pushed far beyond what people could imagine in the beginning. This review strives to cover the achievements of g-C3N4 related materials in these unconventional application fields for depicting the broader future of these metal-free and fully stable semiconductors. This review starts with the general protocols to engineer g-C3N4 micro/nanostructures for practical use, and then discusses the newly disclosed applications in sensing, bioimaging, novel solar energy exploitation including photocatalytic coenzyme regeneration, templating, and carbon nitride based devices. Finally, we attempt an outlook on possible further developments in g-C3N4 based research.

  18. Phenyl-Modified Carbon Nitride Quantum Dots with Distinct Photoluminescence Behavior.

    Science.gov (United States)

    Cui, Qianling; Xu, Jingsan; Wang, Xiaoyu; Li, Lidong; Antonietti, Markus; Shalom, Menny

    2016-03-01

    A novel type of quantum dot (Ph-CN) is manufactured from graphitic carbon nitride by "lining" the carbon nitride structure with phenyl groups through supramolecular preorganization. This approach requires no chemical etching or hydrothermal treatments like other competing nanoparticle syntheses and is easy and safe to use. The Ph-CN nanoparticles exhibit bright, tunable fluorescence, with a high quantum yield of 48.4 % in aqueous colloidal suspensions. Interestingly, the observed Stokes shift of approximately 200 nm is higher than the maximum values reported for carbon nitride based fluorophores. The high quantum yield and the large Stokes shift are related to the structural surface organization of the phenyl groups, which affects the π-electron delocalization in the conjugated carbon nitride networks and induces colloidal stability. The remarkable performance of the Ph-CN nanoparticles in imaging is demonstrated by a simple incubation study with HeLa cells. PMID:26880237

  19. Phenyl-Modified Carbon Nitride Quantum Dots with Distinct Photoluminescence Behavior.

    Science.gov (United States)

    Cui, Qianling; Xu, Jingsan; Wang, Xiaoyu; Li, Lidong; Antonietti, Markus; Shalom, Menny

    2016-03-01

    A novel type of quantum dot (Ph-CN) is manufactured from graphitic carbon nitride by "lining" the carbon nitride structure with phenyl groups through supramolecular preorganization. This approach requires no chemical etching or hydrothermal treatments like other competing nanoparticle syntheses and is easy and safe to use. The Ph-CN nanoparticles exhibit bright, tunable fluorescence, with a high quantum yield of 48.4 % in aqueous colloidal suspensions. Interestingly, the observed Stokes shift of approximately 200 nm is higher than the maximum values reported for carbon nitride based fluorophores. The high quantum yield and the large Stokes shift are related to the structural surface organization of the phenyl groups, which affects the π-electron delocalization in the conjugated carbon nitride networks and induces colloidal stability. The remarkable performance of the Ph-CN nanoparticles in imaging is demonstrated by a simple incubation study with HeLa cells.

  20. Ionic liquid promoted synthesis of conjugated carbon nitride photocatalysts from urea.

    Science.gov (United States)

    Lin, Zhenzhen; Wang, Xinchen

    2014-06-01

    To allow for simultaneous textural engineering and doping of carbon nitride materials with heteroatoms, urea has been polymerized with an ionic liquid. The role of urea is to create a delamination effect during carbon nitride synthesis, whereas ionic liquid functions as texture modifier as well as B/F dopant source. This will result in the rational fabrication of boron- and fluorine-containing 2D carbon nitride nanosheets with enhanced optical harvesting and charge separation capabilities for hydrogen evolution catalysis using visible light. We believe that the innovative modification strategy developed herein can be coupled with the already known modification tools of 2D carbon nitride, thus further developing a new family of light-harvesting 2D platforms for the efficient and sustained utilization of solar radiation for a variety of advanced applications, including CO2 photofixation, organic photosynthesis, and pollutant controls.

  1. Field Emission from Amorphous carbon Nitride Films Deposited on silicon Tip Arrays

    Institute of Scientific and Technical Information of China (English)

    李俊杰; 郑伟涛; 孙龙; 卞海蛟; 金曾孙; 赵海峰; 宋航; 孟松鹤; 赫晓东; 韩杰才

    2003-01-01

    Amorphous carbon nitride films (a-CNx) were deposited on silicon tip arrays by rf magnetron sputtering in pure nitrogen atmosphere. The field emission property of carbon nitride films on Si tips was compared with that of carbon nitride on silicon wafer. The results show that field emission property of carbon nitride films deposited on silicon tips can be improved significantly in contrast with that on wafer. It can be explained that field emission is sensitive to the local curvature and geometry, thus silicon tips can effectively promote field emission property of a-CNx films. In addition, the films deposited on silicon tips have a smaller effective work function ( F = 0.024 eV)of electron field emission than that on silicon wafer ( F = 0.060 e V), which indicates a significant enhancement of the ability of electron field emission from a-CNx films.

  2. Preparation and Characterization of Metal-free graphitic Carbon Nitride Film Photocathodes for Light-induced Hydrogen Evolution

    CERN Document Server

    Yang, Florent; Orthmann, Steven; Merschjann, Christoph; Tyborski, Tobias; Rusu, Marin; Kanis, Michael; Thomas, Arne; Arrigo, Rosa; Haevecker, Michael; Schedel-Niedrig, Thomas

    2012-01-01

    Very recently, it has been shown that an abundant material, polymeric carbon nitride, can produce hydrogen from water under visible-light irradiation in the presence of a sacrificial donor [1]. We will present here the preparation and characterization of graphitic carbon nitride (g-C3N4) films on semiconducting substrates by thermal condensation of dicyandiamide precursor under inert gas conditions. Structural and surface morphological studies of the carbon nitride films suggest a high porosity of g-C3N4 thin film consisting of a network of nanocrystallites. Photo-electrochemical investigations show upon cathodic polarization light-induced hydrogen evolution for a wide range of proton concentrations in the aqueous electrolyte. Additionally, Synchrotron radiation based photoelectron spectroscopy has been applied to study the surface/near-surface chemical composition of the utilized g-C3N4 film photocathodes. For the first time it is shown that g-C3N4 films can be successfully applied as photoelectrochemical ma...

  3. 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; Raghavan, Srinivasan

    2015-10-01

    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.

  4. 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.

  5. Pulsed laser deposition of niobium nitride thin films

    International Nuclear Information System (INIS)

    Niobium nitride (NbNx) films were grown on Nb and Si(100) substrates using pulsed laser deposition. NbNx 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 NbNx films from mixed β-Nb2N and cubic δ-NbN phases to single hexagonal β-Nb2N. The substrate temperature affects the preferred orientation of the crystal structure. The structural and electronic, properties of NbNx deposited on Si(100) were also investigated. The NbNx 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 NbNx film morphology and phase

  6. 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.

  7. 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.

  8. Evidence for a low-compressibility carbon nitride polymorph elaborated at ambient pressure and mild temperature

    OpenAIRE

    Goglio, Graziella; Foy, Denis; Pechev, Stanislav; Majimel, Jérôme; Demazeau, Gérard; Guignot, Nicolas; Andrault, Denis

    2009-01-01

    International audience Superhard materials like diamond are essential for abrasive or cutting tool applications. In this way, carbon nitrides are of relevant interest because they are expected to exhibit exceptional mechanical properties, high values of bulk modulus being predicted. A smart and simple method was used to synthesize carbon nitrides and allowed elaborating a low-compressibility polymorph. The processing consists in the decomposition of commercial thiosemicarbazide (H2NC(S)N2H...

  9. 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.

  10. 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.

  11. Photoluminescence and Raman Spectroscopy Studies of Carbon Nitride Films

    Directory of Open Access Journals (Sweden)

    J. Hernández-Torres

    2016-01-01

    Full Text Available Amorphous carbon nitride films with N/C ratios ranging from 2.24 to 3.26 were deposited by reactive sputtering at room temperature on corning glass, silicon, and quartz as substrates. The average chemical composition of the films was obtained from the semiquantitative energy dispersive spectroscopy analysis. Photoluminescence measurements were performed to determine the optical band gap of the films. The photoluminescence spectra displayed two peaks: one associated with the substrate and the other associated with CNx films located at ≈2.13±0.02 eV. Results show an increase in the optical band gap from 2.11 to 2.15 eV associated with the increase in the N/C ratio. Raman spectroscopy measurements showed a dominant D band. ID/IG ratio reaches a maximum value for N/C ≈ 3.03 when the optical band gap is 2.12 eV. Features observed by the photoluminescence and Raman studies have been associated with the increase in the carbon sp2/sp3 ratio due to presence of high nitrogen content.

  12. Hydrogen Storage in Boron Nitride and Carbon Nanomaterials

    Directory of Open Access Journals (Sweden)

    Takeo Oku

    2014-12-01

    Full Text Available Boron nitride (BN nanomaterials were synthesized from LaB6 and Pd/boron powder, and the hydrogen storage was investigated by differential thermogravimetric analysis, which showed possibility of hydrogen storage of 1–3 wt%. The hydrogen gas storage in BN and carbon (C clusters was also investigated by molecular orbital calculations, which indicated possible hydrogen storage of 6.5 and 4.9 wt%, respectively. Chemisorption calculation was also carried out for B24N24 cluster with changing endohedral elements in BN cluster to compare the bonding energy at nitrogen and boron, which showed that Li is a suitable element for hydrogenation to the BN cluster. The BN cluster materials would store H2 molecule easier than carbon fullerene materials, and its stability for high temperature would be good. Molecular dynamics calculations showed that a H2 molecule remains stable in a C60 cage at 298 K and 0.1 MPa, and that pressures over 5 MPa are needed to store H2 molecules in the C60 cage.

  13. Low temperature synthesis of silicon nitride thin films deposited by VHF/RF PECVD for gas barrier application

    Science.gov (United States)

    Lee, Jun S.; Shin, Kyung S.; Sahu, B. B.; Han, Jeon G.

    2015-09-01

    In this work, silicon nitride (SiNx) thin films were deposited on polyethylene terephthalate (PET) substrates as barrier layers by plasma enhanced chemical vapor deposition (PECVD) system. Utilizing a combination of very high-frequency (VHF 40.68 MHz) and radio-frequency (RF 13.56 MHz) plasmas it was possible to adopt PECVD deposition at low-temperature using the precursors: Hexamethyldisilazane (HMDSN) and nitrogen. To investigate relationship between film properties and plasma properties, plasma diagnostic using optical emission spectroscopy (OES) was performed along with the film analysis using Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). OES measurements show that there is dominance of the excited N2 and N2+ emissions with increase in N2 dilution, which has a significant impact on the film properties. It was seen that all the deposited films contains mainly silicon nitride with a small content of carbon and no signature of oxygen. Interestingly, upon air exposure, films have shown the formation of Si-O bonds in addition to the Si-N bonds. Measurements and analysis reveals that SiNx films deposited with high content of nitrogen with HMDSN plasma can have lower gas barrier properties as low as 7 . 3 ×10-3 g/m2/day. Also at Chiang Mai University.

  14. 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.

  15. 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

  16. Method for making thin carbon foam electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Pekala, R.W.; Mayer, S.T.; Kaschmitter, J.L.; Morrison, R.L.

    1999-08-03

    A method for fabricating thin, flat carbon electrodes by infiltrating highly porous carbon papers, membranes, felts, metal fibers/powders, or fabrics with an appropriate carbon foam precursor material is disclosed. The infiltrated carbon paper, for example, is then cured to form a gel-saturated carbon paper, which is subsequently dried and pyrolyzed to form a thin sheet of porous carbon. The material readily stays flat and flexible during curing and pyrolyzing to form thin sheets. Precursor materials include polyacrylonitrile (PAN), polymethylacrylonitrile (PMAN), resorcinol/formaldehyde, catechol/formaldehyde, phenol/formaldehyde, etc., or mixtures thereof. These thin films are ideal for use as high power and energy electrodes in batteries, capacitors, and fuel cells, and are potentially useful for capacitive deionization, filtration and catalysis.

  17. Method for making thin carbon foam electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Pekala, Richard W. (Pleasant Hill, CA); Mayer, Steven T. (San Leandro, CA); Kaschmitter, James L. (Pleasanton, CA); Morrison, Robert L. (Modesto, CA)

    1999-01-01

    A method for fabricating thin, flat carbon electrodes by infiltrating highly porous carbon papers, membranes, felts, metal fibers/powders, or fabrics with an appropriate carbon foam precursor material. The infiltrated carbon paper, for example, is then cured to form a gel-saturated carbon paper, which is subsequently dried and pyrolyzed to form a thin sheet of porous carbon. The material readily stays flat and flexible during curing and pyrolyzing to form thin sheets. Precursor materials include polyacrylonitrile (PAN), polymethylacrylonitrile (PMAN), resorcinol/formaldehyde, catechol/formaldehyde, phenol/formaldehyde, etc., or mixtures thereof. These thin films are ideal for use as high power and energy electrodes in batteries, capacitors, and fuel cells, and are potentially useful for capacitive deionization, filtration and catalysis.

  18. Dip coating of boron nitride thin films on nicalon fibers

    International Nuclear Information System (INIS)

    This paper discusses a process involving dip coating of ceramic fibers in H3BO3 solution followed by reaction with NH3 has resulted in the formation of a BN coating on Nicalon and a carbon coated Nicalon fiber. BN coated C-Nicalon fiber maintained its strength during the coating process, while the BN coated Nicalon did not

  19. Improvement in surface properties with TiN thin film coating on plasma nitride austenitic 316 stainless steel

    OpenAIRE

    Pankaj Kumar Singh; Arbind Kumar; Sanjay Kumar Sinha; Aman Aggarwal; Gajendra Prasad Singh

    2016-01-01

    The surface of the austenitic 316 stainless steel was modified by using two processes, i.e, dc glow discharge plasma and RF magnetron sputtering. The plasma nitriding was carried out at 500°C under 3 mbar pressure for 5 h in presence of 4N2:1H2 gas mixture. A thin layer of TiN was coated on plasma nitrided samples by using RF magnetron sputtering.The phase formation, nitride layer, surface nanohardness and corrosion current density were evaluated by X-ray diffractogram, optical microscope and...

  20. 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.

  1. Turbostratic-like carbon nitride coatings deposited by industrial-scale direct current magnetron sputtering

    International Nuclear Information System (INIS)

    Carbon nitride thin films were deposited by direct current magnetron sputtering in an industrial-scale equipment at different deposition temperatures and substrate bias voltages. The films had N/(N + C) atomic fractions between 0.2 and 0.3 as determined by X-ray photoelectron spectroscopy (XPS). Raman spectroscopy provided insight into the ordering and extension of the graphite-like clusters, whereas nanoindentation revealed information on the mechanical properties of the films. The internal compressive film stress was evaluated from the substrate bending method. At low deposition temperatures the films were amorphous, whereas the film deposited at approximately 380 °C had a turbostratic-like structure as confirmed by high-resolution transmission electron microscopy images. The turbostratic-like film had a highly elastic response when subjected to nanoindentation. When a CrN interlayer was deposited between the film and the substrate, XPS and Raman spectroscopy indicated that the turbostratic-like structure was maintained. However, it was inconclusive whether the film still exhibited an extraordinary elastic recovery. An increased substrate bias voltage, without additional heating and without deposition of an interlayer, resulted in a structural ordering, although not to the extent of a turbostratic-like structure. - Highlights: • Carbon nitride films were deposited by industrial-scale magnetron sputtering. • The deposition temperature and the substrate bias voltage were varied. • A turbostratic-like structure was obtained at an elevated deposition temperature. • The turbostratic-like film exhibited a very high elastic recovery. • The influence of a CrN interlayer on the film properties was investigated

  2. Synthesis of beta carbon nitride nanosized crystal through mechanochemical reaction

    CERN Document Server

    Yin Long Wei; Liu Yu Xian; Sui Jin Ling; Wang Jing Min

    2003-01-01

    Nanosized beta carbon nitride (beta-C sub 3 N sub 4), of grain size several tens of nanometres, has been synthesized by mechanochemical reaction processing. The low-cost synthetic method developed facilitates the novel and effective synthesis of nanosized crystalline beta-C sub 3 N sub 4 (a = 6.36 A, c = 4.648 A) powders. The graphite powders were first milled to a nanoscale state, then the nanosized graphite powders were milled in an atmosphere of NH sub 3 gas. It was found that nanosized beta-C sub 3 N sub 4 was formed after high-energy ball milling under an NH sub 3 atmosphere. After thermal annealing, the shape of the beta-C sub 3 N sub 4 changes from flake-like to sphere-like. The nanosized beta-C sub 3 N sub 4 formed was characterized by x-ray diffraction, Fourier transformation infrared spectroscopy, and transmission electron microscopy. A solid-gas reaction mechanism was proposed for the formation of nanosized beta-C sub 3 N sub 4 at room temperature induced by mechanochemical activation.

  3. 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.

  4. Liquid nitrogen to room temperature thermometry using niobium nitride thin films

    OpenAIRE

    Bourgeois, Olivier; André, Emmanuel; Macovei, Cristina; Chaussy, Jacques

    2006-01-01

    Niobium nitride thin film thermometry has been developed for the temperature range of 70K to 300K. The deposition parameters have been optimized in order to get the best performances, i.e. the highest temperature coefficient of resistance (TCR), up to 300K. The TCR is found to be largely higher than 1% as the temperature is lowered from 300K, up to 6% at 77K. These significant performances are compared to the one of regular platinum thermometer as well as to other resistive thermometer: semic...

  5. RF plasma reactive pulsed laser deposition of boron nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mitu, B. [CNR-IMIP/PZ Zona Industriale di Tito Scalo, I - 85050 Tito Scalo (PZ) (Italy)]. E-mail: mitub@alpha1.infim.ro; Bilkova, P. [CNR-IMIP/PZ Zona Industriale di Tito Scalo, I - 85050 Tito Scalo (PZ) (Italy)]. E-mail: bilkova.petra@tiscali.cz; Marotta, V. [CNR-IMIP/PZ Zona Industriale di Tito Scalo, I - 85050 Tito Scalo (PZ) (Italy); Orlando, S. [CNR-IMIP/PZ Zona Industriale di Tito Scalo, I - 85050 Tito Scalo (PZ) (Italy)]. E-mail: orlando@imip.pz.cnr.it; Santagata, A. [CNR-IMIP/PZ Zona Industriale di Tito Scalo, I - 85050 Tito Scalo (PZ) (Italy)

    2005-07-15

    Thin films of boron nitride (BN) have been deposited on Si(1 0 0) substrates by reactive pulsed laser ablation (PLA) of a boron target in the presence of a 13.56 MHz radio frequency (RF) nitrogen plasma. The gaseous species have been deposited at several substrate temperatures, using the on-axis configuration. The film properties have been investigated by Scanning Electron Microscopy, Atomic Force Microscopy, Fourier Transformed Infrared Spectroscopy, and X-ray diffraction characterization techniques, and compared to those resulting from the conventional PLA method. The behavior of hexagonal-BN and cubic-BN phases grown by PLA as function of substrate temperature is also reported.

  6. 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.

  7. Conformational analysis and electronic structure of chiral carbon and carbon nitride nanotubes

    Directory of Open Access Journals (Sweden)

    Cristiano Geraldo de Faria

    2011-12-01

    Full Text Available Geometry and electronic structure of chiral carbon and carbon nitride (CNx nanotubes were investigated through quantum chemical methods. Finite nanotubes with diameters ranging from 5 to 10 Å and containing up to 500 atoms were considered. CNx structures were built through random substitution of carbon atoms by nitrogen. The molecules were fully optimized by semi-empirical quantum chemical method (PM3. Our results show that the energy associated with nitrogen incorporation depends strongly upon the tube helicity and diameter. The doping of nanotubes with nitrogen contributes to reduce the stress caused by the small diameter of the studied systems. Density of States (DOS results for pure carbon and CNx nanostructures, obtained through DFT and Hartree-Fock calculations, were analyzed. The introduction of nitrogen in the tube produce states in the gap region which characterizes the metallic behavior, as expected for these systems after N-doping.

  8. Thermal Contact Conductance Analysis of Nitride and Carbonitride Thin Film Coatings for Thermal Interface Material Application

    Science.gov (United States)

    Subramani, Shanmugan; Thing, Lee Yuan; Devarajan, Mutharasu

    2015-12-01

    In order to reduce and maintain the bond line thickness between substrate and LED package, solid thin film with good thermal conductivity is suggested as thermal interface material and the proposed film thickness is about less than 1 µ. The surface parameter such as roughness and hardness is a key factor which alters the contact conductance between the two matt surfaces. Consequently, filtered vacuum cathodic arc deposited nitride thin films (CrN, TiN, AlTiN, and TiCN) on copper substrate were tested for thermal interface material applications in electronic packaging. The thermal contact conductance of the prepared thin films was evaluated using surface properties such as microhardness and surface roughness. The results were verified with the theoretical model. The measured microhardness and surface roughness of CrN thin film are 17 GPa (low) and 0.768 µm (high), respectively. The measured thermal contact conductance of all thin films showed linear properties for applied pressure and very close to the values of theoretical model. High value in thermal contact conductance of about 256 W/m2 K was noticed with CrN thin film at 1100 kPa. The percentage of deviation for our measured contact conductance value from the theoretical model value was decreasing for the increased contact pressure and observed low value (7 pct) for CrN thin film at 1100 kPa. The thermal conductivity of all thin films was also calculated from the conductance model and observed high value (19.34 W/mK) with CrN thin film.

  9. 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.

  10. Processing, mechanical and thermophysical properties of silicon nitride based composites with carbon nanotubes and graphene

    Directory of Open Access Journals (Sweden)

    O. Koszor

    2007-12-01

    Full Text Available Silicon nitride based composites with different amount (1, 2 and 3 wt% of multi-wall and single-wall carbon nanotubes, and graphene have been prepared. Optimisation of the manufacturing processes has been conducted to preserve the carbon nanotubes in composites and to avoid damaging during high temperature processing. The first results show that carbon nanotubes have a good contact to the surface of silicon nitride grains. In the case of increase of sintering pressure an increase of bending strength was achieved. It was found that microstructure features achieved by properly designed sintering parameters are the main responsible factors for the strength improvements.

  11. An Overview on Structure and Field Emission Properties of Carbon Nitride Films

    Directory of Open Access Journals (Sweden)

    Qiong Wang

    2014-01-01

    Full Text Available Carbon nitride films have excellent properties and wide application prospects in the aspect of field emission properties. In this review structure characteristics and a variety of synthetic methods of carbon nitride film will be described. In the carbon nitrogen films, we mainly from the following three points: sp2/sp3 ratio, surface morphology and N content to discuss the change of field emission properties. Appropriate sp2/sp3 (about 1.0–1.25 ratio, N content (about 8 at.%–10 at.%, and rough surfaces will strengthen the field emission properties.

  12. 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.

  13. Carbon nitride films by RF plasma assisted PLD: Spectroscopic and electronic analysis

    International Nuclear Information System (INIS)

    Carbon nitride (CNx) thin films have been grown on Si by 193 nm ArF ns pulsed laser ablation of a pure graphite target in a low pressure atmosphere of a RF generated N2 plasma and compared with samples grown by PLD in pure nitrogen atmosphere. Composition, structure and bonding of the deposited materials have been evaluated by X-ray photoelectron spectroscopy (XPS), and Raman scattering. Significant chemical and micro-structural changes have been registered, associated to different nitrogen incorporation in the two types of films analyzed. The intensity of the reactive activated species is, indeed, increased by the presence of the bias confined RF plasma, as compared to the bare nitrogen atmosphere, thus resulting in a different nitrogen uptake in the growing films. The process has been also investigated by some preliminary optical emission studies of the carbon plume expanding in the nitrogen atmosphere. Optical emission spectroscopy reveals the presence of many excited species like C+ ions, C atoms, C2, N2; and CN radicals, and N2+ molecular ions, whose relative intensity appears to be increased in the presence of the RF plasma. The films were also characterised for electrical properties by the 'four-probe-test method' determining sheet resistivity and correlating surface conductivity with chemical composition.

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

    International Nuclear Information System (INIS)

    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 10B), 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 2.83×10−7 cm2/V for electrons and holes, which is comparable to the value of about 10−7 cm2/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

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

    Science.gov (United States)

    Doan, T. C.; Majety, S.; Grenadier, S.; Li, J.; Lin, J. Y.; Jiang, H. X.

    2015-05-01

    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 10B), 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 2.83×10-7 cm2/V for electrons and holes, which is comparable to the value of about 10-7 cm2/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.

  16. 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.

  17. 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.

  18. Improvement in surface properties with TiN thin film coating on plasma nitride austenitic 316 stainless steel

    Directory of Open Access Journals (Sweden)

    Pankaj Kumar Singh

    2016-02-01

    Full Text Available The surface of the austenitic 316 stainless steel was modified by using two processes, i.e, dc glow discharge plasma and RF magnetron sputtering. The plasma nitriding was carried out at 500°C under 3 mbar pressure for 5 h in presence of 4N2:1H2 gas mixture. A thin layer of TiN was coated on plasma nitrided samples by using RF magnetron sputtering.The phase formation, nitride layer, surface nanohardness and corrosion current density were evaluated by X-ray diffractogram, optical microscope and SEM, nanoindenter and electrochemical analyser. The untreated sample showed only γFe diffraction pattern while after nitriding CrN phase with γFe and after coating only TiN phase diffraction pattern is observed. The nitride layerof about 8-10 μm is observed in nitrided sample and TiN layer of about 200 nm is measured in TiN coated plasma nitride sample.The untreated 316 steel shows the surface nanohardness about 1. 59 to 1.88 GPa. The nitriding improved the surface hardness about five times (8.45GPa and TiN coating further enhanced the surface hardness about seven times (13.16GPa than untreated sample. The corrosion potential (ECorr of the plasma nitrided and TiN coated plasma nitrided 316 samples showing positive shift with reference to the untreated sample. The corrosion potential(ECorr value of untreated, plasma nitride and TiN coated plasma nitrided 316 samples are -0.593 V, -0.443 V and 0.074 V, respectively. The corrosion current density (ICorr is considerably enhanced after nitriding and TiN coating, i.e., 4.46 μAcm-2 and 2.24 μAcm-2 respectively than 15.13 μAcm-2 for untreated sample. The passivation current densities of samples measured at 0.6 V vs SHEare about 69.18 μAcm-2, 18.62 μAcm-2 and 3.16μAcm-2, respectively.

  19. An Amorphous Carbon Nitride Photocatalyst with Greatly Extended Visible-Light-Responsive Range for Photocatalytic Hydrogen Generation.

    Science.gov (United States)

    Kang, Yuyang; Yang, Yongqiang; Yin, Li-Chang; Kang, Xiangdong; Liu, Gang; Cheng, Hui-Ming

    2015-08-19

    Amorphous carbon nitride (ACN) with a bandgap of 1.90 eV shows an order of magnitude higher photocatalytic activity in hydrogen evolution under visible light than partially crystalline graphitic carbon nitride with a bandgap of 2.82 eV. ACN is photocatalytically active under visible light at a wavelength beyond 600 nm.

  20. Self-Sensitized Carbon Nitride Microspheres for Long-Lasting Visible-Light-Driven Hydrogen Generation.

    Science.gov (United States)

    Gu, Quan; Gao, Ziwei; Xue, Can

    2016-07-01

    A new type of metal-free photocatalyst is reported having a microsphere core of oxygen-containing carbon nitride and self-sensitized surfaces by covalently linked polymeric triazine dyes. These self-sensitized carbon nitride microspheres exhibit high visible-light activities in photocatalytic H2 generation with excellent stability for more than 100 h reaction. Comparing to the traditional g-C3 N4 with activities terminated at 450 nm, the polymeric triazine dyes on the carbon nitride microsphere surface allow for effective wide-range visible-light harvesting and extend the H2 generation activities up to 600 nm. It is believed that this new type of highly stable self-sensitized metal-free structure opens a new direction of future development of low-cost photocatalysts for efficient and long-term solar fuels production.

  1. Self-Sensitized Carbon Nitride Microspheres for Long-Lasting Visible-Light-Driven Hydrogen Generation.

    Science.gov (United States)

    Gu, Quan; Gao, Ziwei; Xue, Can

    2016-07-01

    A new type of metal-free photocatalyst is reported having a microsphere core of oxygen-containing carbon nitride and self-sensitized surfaces by covalently linked polymeric triazine dyes. These self-sensitized carbon nitride microspheres exhibit high visible-light activities in photocatalytic H2 generation with excellent stability for more than 100 h reaction. Comparing to the traditional g-C3 N4 with activities terminated at 450 nm, the polymeric triazine dyes on the carbon nitride microsphere surface allow for effective wide-range visible-light harvesting and extend the H2 generation activities up to 600 nm. It is believed that this new type of highly stable self-sensitized metal-free structure opens a new direction of future development of low-cost photocatalysts for efficient and long-term solar fuels production. PMID:27225827

  2. 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

  3. ERDA characterization of carbon nitride films deposited by hollow cathode discharge process

    International Nuclear Information System (INIS)

    The interest in carbon nitride (CN) thin films stems from the theoretical work of Liu and Cohen predicting the extreme hardness of this material, comparable to or greater than that of diamond. The growth of CN thin films employing various deposition techniques such as plasma chemical vapor deposition, sputtering, laser ablation, ion assisted dynamic mixing and low energy ion implantation has been reported. This contribution presents some results about the characterization of CNx films using elastic recoil detection analysis (ERDA) technique. CN films were deposited on silicon substrates by electron beam evaporation of pure graphite in a nitrogen environment. A hollow cathode discharge in arc regime was used both for evaporating a graphite target and for generating a high density plasma in the vicinity of the substrate. The main deposition parameters were as follows: gas (N2) pressure, 10-2 - 5.10-2 mbar; hollow cathode discharge power, 2.5 - 5 kW; substrate negative bias voltage, 0-150 V; graphite evaporation rate, 0.08 - 0.2 g/min; deposition duration, 15-60 min. The ERDA measurements were carried out at the Tandem accelerator of IFIN-HH using a 63Cu10+ beam at 80 MeV. The samples were mounted in a scattering target chamber with a vacuum higher than 5 x 10-5 Torr. The detector consisted in a compact ΔE(gas)-E(solid) telescope, placed at 30 angle with respect to the beam. The elements of the main interests were C and N. The measured Δ E -E spectra for two samples prepared in different conditions are presented. A quantitative analysis of the C and N energy spectra using our program SURFAN have been carried out for the these samples. It shows that the nitrogen to carbon atomic concentration ratio is close to 0.3. The nitrogen content is lower than that expected for the ideal β - C3N4 solid. (authors)

  4. 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.

  5. 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.

  6. Chemical Cleavage of Layered Carbon Nitride with Enhanced Photoluminescent Performances and Photoconduction.

    Science.gov (United States)

    Zhou, Zhixin; Shen, Yanfei; Li, Ying; Liu, Anran; Liu, Songqin; Zhang, Yuanjian

    2015-12-22

    Graphene quantum dots (GQDs) and carbon dots (C-dots) have various alluring properties and potential applications, but they are often limited by unsatisfied optical performance such as low quantum yield, ambiguous fluorescence emission mechanism, and narrow emission wavelength. Herein, we report that bulk polymeric carbon nitride could be utilized as a layered precursor to prepare carbon nitride nanostructures such as nanorods, nanoleaves and quantum dots by chemical tailoring. As doped carbon materials, these carbon nitride nanostructures not only intrinsically emitted UV lights but also well inherited the explicit photoluminescence mechanism of the bulk pristine precursor, both of which were rarely reported for GQDs and C-dots. Especially, carbon nitride quantum dots (CNQDs) had a photoluminescence quantum yield (QY) up to 46%, among the highest QY for metal-free quantum dots so far. As examples, the CNQDs were utilized as a photoluminescence probe for rapid detection of Fe(3+) with a detection limit of 1 μM in 2 min and a photoconductor in an all-solid-state device. This work would open up an avenue for doped nanocarbon in developing photoelectrical devices and sensors.

  7. Fabrication of particular structures of hexagonal boron nitride and boron-carbon-nitrogen layers by anisotropic etching

    Science.gov (United States)

    Vishwakarma, Riteshkumar; Sharma, Subash; Shinde, Sachin M.; Sharma, Kamal P.; Thangaraja, Amutha; Kalita, Golap; Tanemura, Masaki

    2016-05-01

    Anisotropic etching of hexagonal boron nitride (h-BN) and boron-carbon-nitrogen (BCN) basal plane can be an exciting platform to develop well-defined structures with interesting properties. Here, we developed an etching process of atomically thin h-BN and BCN layers to fabricate nanoribbons (NRs) and other distinct structures by annealing in H2 and Ar gas mixture. BCN and h-BN films are grown on Cu foil by chemical vapor deposition (CVD) using solid camphor and ammonia borane as carbon, nitrogen and boron source, respectively. Formation of micron size well-defined etched holes and NRs are obtained in both h-BN and BCN layers by the post growth annealing process. The etching process of h-BN and BCN basal plane to fabricate NRs and other structures with pronounced edges can open up new possibilities in 2D hybrid materials.

  8. Is hexagonal boron nitride always good as a substrate for carbon nanotube-based devices?

    Science.gov (United States)

    Kang, Seoung-Hun; Kim, Gunn; Kwon, Young-Kyun

    2015-02-21

    Hexagonal boron nitride sheets have been noted especially for their enhanced properties as substrates for sp(2) carbon-based nanodevices. To evaluate whether such enhanced properties would be retained under various realistic conditions, we investigate the structural and electronic properties of semiconducting carbon nanotubes on perfect and defective hexagonal boron nitride sheets under an external electric field as well as with a metal impurity, using density functional theory. We verify that the use of a perfect hexagonal boron nitride sheet as a substrate indeed improves the device performances of carbon nanotubes, compared with the use of conventional substrates such as SiO2. We further show that even the hexagonal boron nitride with some defects can show better performance as a substrate. Our calculations, on the other hand, also suggest that some defective boron nitride layers with a monovacancy and a nickel impurity could bring about poor device behavior since the imperfections impair electrical conductivity due to residual scattering under an applied electric field.

  9. 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. PMID:26267150

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

    Directory of Open Access Journals (Sweden)

    Hua Bing Tao

    2014-06-01

    Full Text Available 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.

  11. 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.

  12. Magnetic and structural properties of nitrided Fe and FeTi thin films

    CERN Document Server

    Bonder, M J

    2001-01-01

    presence of weak perpendicular anisotropy occurring as the bilayer thickness increased. As the bilayer thickness was increased there was an asymptotic approach of the magnetization to the level of the unexposed materials. The presence of the perpendicular anisotropy was maintained for a larger parameter space. In both series the anisotropy is attributed to stress induced by the substrate, Nitriding Fe and FeTi using the aforementioned technique provides a controlled and viable way to alter the magnetic and structural properties. This thesis investigates the magnetic and structural properties of Fe and Fe sub 8 sub 5 Ti sub 1 sub 5 thin films nitrided using a nitrogen atom source. In this novel technique, the atom source produces an atomic nitrogen beam for which multilayer samples with bilayers of the form Fe/FeN or FeTi/FeTiN were synthesized by varying the thickness of the Fe or FeTi exposed to the nitrogen beam. The samples studied here are all in the as-deposited state. X-Ray reflectivity confirms the pre...

  13. 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'...

  14. 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.

  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. 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 m2 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 Cu2+ determination. So GA-C3N4 is a new but promising candidate for heavy metal ions (Cu2+) determination in water environment. The photocatalytic mechanism and photoelectrochemical selective sensing of Cu2+ were also discussed.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 m2 g-1, increased photocurrent responses and improved electron transport ability, which could give rise to enhancing the photocatalytic activity and stability. The graphene

  17. 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.

  18. Impact of sputter deposition parameters on molybdenum nitride thin film properties

    International Nuclear Information System (INIS)

    Molybdenum and molybdenum nitride thin films are presented, which are deposited by reactive dc magnetron sputtering. The influence of deposition parameters, especially the amount of nitrogen during film synthesization, to mechanical and electrical properties is investigated. The crystallographic phase and lattice constants are determined by x-ray diffraction analyses. Further information on the microstructure as well as on the biaxial film stress are gained from techniques such as transmission electron microscopy, scanning electron microscopy and the wafer bow. Furthermore, the film resistivity and the temperature coefficient of resistance are measured by the van der Pauw technique starting from room temperature up to 300 °C. Independent of the investigated physical quantity, a dominant dependence on the sputtering gas nitrogen content is observed compared to other deposition parameters such as the plasma power or the sputtering gas pressure in the deposition chamber. (paper)

  19. 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.

  20. MgB2 thin films on silicon nitride substrates prepared by an in situ method

    International Nuclear Information System (INIS)

    Large-area MgB2 thin films were deposited on silicon nitride and sapphire substrates by co-deposition of Mg and B. After a post-annealing in Ar atmosphere at temperatures between 773 and 1173 K depending on the substrate, the films showed a critical temperature higher than 35 K with a transition width less than 0.5 K. The x-ray diffraction pattern suggested a c-axis preferential orientation in films deposited on amorphous substrate. The smooth surface and the good structural properties of these MgB2 films allowed their reproducible patterning by a standard photolithographic process down to dimensions of the order of 10 μm and without a considerable degradation of the superconducting properties

  1. Flexible piezoelectric pressure sensors using oriented aluminum nitride thin films prepared on polyethylene terephthalate films

    Science.gov (United States)

    Akiyama, Morito; Morofuji, Yukari; Kamohara, Toshihiro; Nishikubo, Keiko; Tsubai, Masayoshi; Fukuda, Osamu; Ueno, Naohiro

    2006-12-01

    We have investigated the high sensitive piezoelectric response of c-axis oriented aluminum nitride (AlN) thin films prepared on polyethylene terephthalate (PET) films. The AlN films were deposited using a radio frequency magnetron sputtering method at temperatures close to room temperature. The c axes of the AlN films were perpendicularly oriented to the PET film surfaces. The sensor consisting of the AlN and PET films is flexible like PET films and the electrical charge is linearly proportional to the stress within a wide range from 0to8.5MPa. The sensor can respond to the frequencies from 0.3 to over 100Hz and measures a clear human pulse wave form by holding the sensor between thumb and middle finger. The resolution of the pulse wave form is comparable to a sphygmomanometer at stress levels of 10kPa. We think that the origin of the high performance of the sensor is the deflection effect, the thin thickness and high elastic modulus of the AlN layer, and the thin thickness and low elastic modulus of the PET film.

  2. 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.

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

    International Nuclear Information System (INIS)

    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 MgB2 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 TC, the authors are the first to report on the correlation between stoichiometry and the lower critical field HC1

  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. Bacterial adhesion studies on titanium, titanium nitride and modified hydroxyapatite thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jeyachandran, Y.L. [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Venkatachalam, S. [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Karunagaran, B. [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Narayandass, Sa.K. [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India)]. E-mail: sakndass@yahoo.com; Mangalaraj, D. [Department of Physics, Bharathiar University, Coimbatore 641 046, Tamil Nadu (India); Bao, C.Y. [West China College of Stomatology, Sichuan University, Chengdu 610041 (China); Zhang, C.L. [West China College of Stomatology, Sichuan University, Chengdu 610041 (China)

    2007-01-15

    A qualitative study on adhesion of the oral bacteria Porphyromonas gingivalis on titanium (Ti), titanium nitride (TiN), fluorine modified hydroxyapatite (FHA) and zinc modified FHA (Zn-FHA) thin films is investigated. Ti and TiN thin films were deposited by DC magnetron sputtering and hydroxyapatite-based films were prepared by solgel method. The crystalline structure, optical characteristics, chemical composition and surface topography of the films were studied by XRD, optical transmission, XPS, EDAX and AFM measurements. The predominant crystallite orientation in the Ti and TiN films was along (002) and (111) of hcp and cubic structures, respectively. The Ti : O : N composition ratio in the surface of the Ti and TiN films was found to be 7 : 21 : 1 and 3 : 8 : 2, respectively. The atomic concentration ratio (Zn + Ca) / P in Zn-FHA film was found to be 1.74 whereby the Zn replaced 3.2% of Ca. The rough surface feature in modified HA films was clearly observed in the SEM images and the surface roughness (rms) of Ti and TiN films was 2.49 and 3.5 nm, respectively, as observed using AFM. The film samples were sterilized, treated in the bacteria culture medium, processed and analyzed using SEM. Surface roughness of the films was found to have least influence on the bacterial adhesion. More bacteria were observed on the TiN film with oxide nitride surface layer and less number of adhered bacteria was noticed on the Ti film with native surface oxide layer and on Zn-FHA film.

  6. Cobalt oxide and nitride particles supported on mesoporous carbons as composite electrocatalysts for dye-sensitized solar cells

    Science.gov (United States)

    Chen, Ming; Shao, Leng-Leng; Gao, Ze-Min; Ren, Tie-Zhen; Yuan, Zhong-Yong

    2015-07-01

    The composite electrocatalysts of cobalt oxide/mesoporous carbon and cobalt nitride/mesoporous carbon are synthesized via a convenient oxidation and subsequent ammonia nitridation of cobalt particles-incorporated mesoporous carbon, respectively. The cobalt oxide and nitride particles are uniformly imbedded in mesoporous carbon matrix, forming the unique composites with high surface area and mesopore architecture, and the resultant composites are evaluated as counter electrode materials, exhibiting good catalytic activity for the reduction of triiodide. The composites of cobalt nitride and mesoporous carbon are superior to the counterparts of cobalt oxide and mesoporous carbon in catalyzing the triiodide reduction, and the dye-sensitized solar cell with the composites achieves an optimum power conversion efficiency of 5.26%, which is comparable to the one based on the conventional Pt counter electrode (4.88%).

  7. 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.

  8. β-Sialon Produced by Carbon Thermal Nitriding Reaction of Bauxite

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    β-Sialon was produced by carbon thermal nitriding reaction in N2 gas atmosphere when the mixtures of bauxite and anthracite were put into vertical furnace. According to the mass loss of raw materials and the result of X-ray diffration (XRD) of products, the influences of the process parameters on the compositions and relative contents of products, such as the fixed carbon content, the flow of N2, the soaking time and the temperature, were researched.

  9. Connecting effect on the first hyperpolarizability of armchair carbon-boron-nitride heteronanotubes: pattern versus proportion.

    Science.gov (United States)

    Zhong, Rong-Lin; Xu, Hong-Liang; Su, Zhong-Min

    2016-05-18

    Carbon-boron-nitride heteronanotubes (BNCNT) have attracted a lot of attention because of their adjustable properties and potential applications in many fields. In this work, a series of CA, PA and HA armchair BNCNT models were designed to explore their nonlinear optical (NLO) properties and provide physical insight into the structure-property relationships; CA, PA and HA represent the models that are obtained by doping the carbon segment into pristine boron nitride nanotube (BNNT) fragments circularly around the tube axis, parallel to the tube axis and helically to the tube axis, respectively. Results show that the first hyperpolarizability (β0) of an armchair BNCNT model is dramatically dependent on the connecting patterns of carbon with the boron nitride fragment. Significantly, the β0 value of PA-6 is 2.00 × 10(4) au, which is almost two orders of magnitude larger than those (6.07 × 10(2) and 1.55 × 10(2) au) of HA-6 and CA-6. In addition, the β0 values of PA and CA models increase with the increase in carbon proportion, whereas those of HA models show a different tendency. Further investigations on transition properties show that the curved charge transfer from N-connecting carbon atoms to B-connecting carbon atoms of PA models is essentially the origin of the big difference among these models. This new knowledge about armchair BNCNTs may provide important information for the design and preparation of advanced NLO nano-materials.

  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. 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.

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

    International Nuclear Information System (INIS)

    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 10-9 A/cm2 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 10-9A/cm2 at 1MV/cm was achieved

  13. Divalent Fe Atom Coordination in Two-Dimensional Microporous Graphitic Carbon Nitride.

    Science.gov (United States)

    Oh, Youngtak; Hwang, Jin Ok; Lee, Eui-Sup; Yoon, Minji; Le, Viet-Duc; Kim, Yong-Hyun; Kim, Dong Ha; Kim, Sang Ouk

    2016-09-28

    Graphitic carbon nitride (g-C3N4) is a rising two-dimensional material possessing intrinsic semiconducting property with unique geometric configuration featuring superimposed heterocyclic sp(2) carbon and nitrogen network, nonplanar layer chain structure, and alternating buckling. The inherent porous structure of heptazine-based g-C3N4 features electron-rich sp(2) nitrogen, which can be exploited as a stable transition metal coordination site. Multiple metal-functionalized g-C3N4 systems have been reported for versatile applications, but local coordination as well as its electronic structure variation upon incoming metal species is not well understood. Here we present detailed bond coordination of divalent iron (Fe(2+)) through micropore sites of graphitic carbon nitride and provide both experimental and computational evidence supporting the aforementioned proposition. In addition, the utilization of electronic structure variation is demonstrated through comparative photocatalytic activities of pristine and Fe-g-C3N4.

  14. Effect of hydrogen addition on the deposition of titanium nitride thin films in nitrogen added argon magnetron plasma

    Science.gov (United States)

    Saikia, P.; Bhuyan, H.; Diaz-Droguett, D. E.; Guzman, F.; Mändl, S.; Saikia, B. K.; Favre, M.; Maze, J. R.; Wyndham, E.

    2016-06-01

    The properties and performance of thin films deposited by plasma assisted processes are closely related to their manufacturing techniques and processes. The objective of the current study is to investigate the modification of plasma parameters occurring during hydrogen addition in N2  +  Ar magnetron plasma used for titanium nitride thin film deposition, and to correlate the measured properties of the deposited thin film with the bulk plasma parameters of the magnetron discharge. From the Langmuir probe measurements, it was observed that the addition of hydrogen led to a decrease of electron density from 8.6 to 6.2  ×  (1014 m‑3) and a corresponding increase of electron temperature from 6.30 to 6.74 eV. The optical emission spectroscopy study reveals that with addition of hydrogen, the density of argon ions decreases. The various positive ion species involving hydrogen are found to increase with increase of hydrogen partial pressure in the chamber. The thin films deposited were characterized using standard surface diagnostic tools such as x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), x-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Although it was possible to deposit thin films of titanium nitride with hydrogen addition in nitrogen added argon magnetron plasma, the quality of the thin films deteriorates with higher hydrogen partial pressures.

  15. Graphitic carbon nitride nanosheets doped graphene oxide for electrochemical simultaneous determination of ascorbic acid, dopamine and uric acid

    International Nuclear Information System (INIS)

    Graphical abstract: Schematic drawing of electrochemical oxidize AA, DA and UA on graphitic carbon nitride nanosheets-graphene oxide composite modified electrode. - Highlights: • Synthesize g-C3N4, GO and CNNS-GO composite. • CNNS-GO composite was the first time for simultaneous determination of AA, DA and UA. • CNNS-GO/GCE displays fantastic selectivity and sensitivity for AA, DA and UA. • CNNS-GO/GCE was applied to detect real sample with satisfactory results. - Abstract: Graphitic carbon nitride nanosheets with a graphite-like structure have strong covalent bonds between carbon and nitride atoms, and nitrogen atoms in the carbon architecture can accelerate the electron transfer and enhance electrical properties effectually. The graphitic carbon nitride nanosheets-graphene oxide composite was synthesized. And the electrochemical performance of the composite was investigated by cyclic voltammetry and differential pulse voltammetry ulteriorly. Due to the synergistic effects of layer-by-layer structures by π-π stacking or charge-transfer interactions, graphitic carbon nitride nanosheets-graphene oxide composite can improved conductivity, electro-catalytic and selective oxidation performance. The proposed graphitic carbon nitride nanosheets-graphene oxide composite modified electrode was employed for simultaneous determination of ascorbic acid, dopamine and uric acid in their mixture solution, it exhibited distinguished sensitivity, wide linear range and low detection limit. Moreover, the modified electrode was applied to detect urine and dopamine injection sample, and then the samples were spiked with certain concentration of three substances with satisfactory recovery results

  16. GLANCING INCIDENCE X-RAY STUDIES OF TITANIUM NITRIDE THIN FILMS USING A NEW MULTIPURPOSE LABORATORY SPECTROMETER

    OpenAIRE

    Buschert, R.C; Gibson, P.; Gissler, W.; Haupt, J.; Crabb, T.

    1989-01-01

    A multipurpose laboratory glancing angle X-ray spectrometer using a standard X-ray tube and a germanium solid state detector has been designed for vertical and horizontal diffraction scans, reflectivity and glancing angle fluorescence measurements. It has been used to study titanium nitride thin films grown under various conditions that vary the stoichiometry, strain, grain size, orientation and lattice parameter. In particular, films grown at liquid nitrogen substrate temperature show very h...

  17. 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. PMID:24309635

  18. 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.

  19. Applicability of carbon and boron nitride nanotubes as biosensors: Effect of biomolecular adsorption on the transport properties of carbon and boron nitride nanotubes

    Science.gov (United States)

    Zhong, Xiaoliang; Mukhopadhyay, Saikat; Gowtham, S.; Pandey, Ravindra; Karna, Shashi P.

    2013-04-01

    The effect of molecular adsorption on the transport properties of single walled carbon and boron nitride nanotubes (CNTs and BNNTs) is investigated using density functional theory and non-equilibrium Green's function methods. The calculated I-V characteristics predict noticeable changes in the conductivity of semiconducting BNNTs due to physisorption of nucleic acid base molecules. Specifically, guanine which binds to the side wall of BNNT significantly enhances its conductivity by introducing conduction channels near the Fermi energy of the bioconjugated system. For metallic CNTs, a large background current masks relatively small changes in current due to the biomolecular adsorption. The results therefore suggest the suitability of BNNTs for biosensing applications.

  20. Vertically self-ordered orientation of nanocrystalline hexagonal boron nitride thin films for enhanced thermal characteristics

    Science.gov (United States)

    Cometto, Olivier; Sun, Bo; Tsang, Siu Hon; Huang, Xi; Koh, Yee Kan; Teo, Edwin Hang Tong

    2015-11-01

    Vertically self-ordered hexagonal boron nitride (ordered h-BN) is a highly ordered turbostratic BN (t-BN) material similar to hexagonal BN, with its planar structure perpendicularly oriented to the substrate. The ordered h-BN thin films were grown using a High Power Impulse Magnetron Sputtering (HiPIMS) system with a lanthanum hexaboride (LaB6) target reactively sputtered in nitrogen gas. The best vertical alignment was obtained at room temperature, with a grounded bias and a HiPIMS peak power density of 60 W cm-2. Even though the film contains up to 7.5 at% lanthanum, it retains its highly insulative properties and it was observed that an increase in compressive stress is correlated to an increase in film ordering quality. Importantly, the thermal conductivity of vertically ordered h-BN is considerably high at 5.1 W m-1 K-1. The favourable thermal conductivity coupled with the dielectric properties of this novel material and the low temperature growth could outperform SiO2 in high power density electronic applications.Vertically self-ordered hexagonal boron nitride (ordered h-BN) is a highly ordered turbostratic BN (t-BN) material similar to hexagonal BN, with its planar structure perpendicularly oriented to the substrate. The ordered h-BN thin films were grown using a High Power Impulse Magnetron Sputtering (HiPIMS) system with a lanthanum hexaboride (LaB6) target reactively sputtered in nitrogen gas. The best vertical alignment was obtained at room temperature, with a grounded bias and a HiPIMS peak power density of 60 W cm-2. Even though the film contains up to 7.5 at% lanthanum, it retains its highly insulative properties and it was observed that an increase in compressive stress is correlated to an increase in film ordering quality. Importantly, the thermal conductivity of vertically ordered h-BN is considerably high at 5.1 W m-1 K-1. The favourable thermal conductivity coupled with the dielectric properties of this novel material and the low temperature

  1. 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

  2. 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.

  3. Co-implantation of carbon and nitrogen into silicon dioxide for synthesis of carbon nitride materials

    CERN Document Server

    Huang, M B; Nuesca, G; Moore, R

    2002-01-01

    Materials synthesis of carbon nitride has been attempted with co-implantation of carbon and nitrogen into thermally grown SiO sub 2. Following implantation of C and N ions to doses of 10 sup 1 sup 7 cm sup - sup 2 , thermal annealing of the implanted SiO sub 2 sample was conducted at 1000 degree sign C in an N sub 2 ambient. As evidenced in Fourier transform infrared measurements and X-ray photoelectron spectroscopy, different bonding configurations between C and N, including C-N single bonds, C=N double bonds and C=N triple bonds, were found to develop in the SiO sub 2 film after annealing. Chemical composition profiles obtained with secondary ion mass spectroscopy were correlated with the depth information of the chemical shifts of N 1s core-level electrons, allowing us to examine the formation of C-N bonding for different atomic concentration ratios between N and C. X-ray diffraction and transmission electron microscopy showed no sign of the formation of crystalline C sub 3 N sub 4 precipitates in the SiO ...

  4. Activation of peroxymonosulfate by graphitic carbon nitride loaded on activated carbon for organic pollutants degradation.

    Science.gov (United States)

    Wei, Mingyu; Gao, Long; Li, Jun; Fang, Jia; Cai, Wenxuan; Li, Xiaoxia; Xu, Aihua

    2016-10-01

    Graphitic carbon nitride supported on activated carbon (g-C3N4/AC) was prepared through an in situ thermal approach and used as a metal free catalyst for pollutants degradation in the presence of peroxymonosulfate (PMS) without light irradiation. It was found that g-C3N4 was highly dispersed on the surface of AC with the increase of surface area and the exposition of more edges and defects. The much easier oxidation of C species in g-C3N4 to CO was also observed from XPS spectra. Acid Orange 7 (AO7) and other organic pollutants could be completely degraded by the g-C3N4/AC catalyst within 20min with PMS, while g-C3N4+PMS and AC+PMS showed no significant activity for the reaction. The performance of the catalyst was significantly influenced by the amount of g-C3N4 loaded on AC; but was nearly not affected by the initial solution pH and reaction temperature. In addition, the catalysts presented good stability. A nonradical mechanism accompanied by radical generation (HO and SO4(-)) in AO7 oxidation was proposed in the system. The CO groups play a key role in the process; while the exposure of more N-(C)3 group can further increase its electron density and basicity. This study can contribute to the development of green materials for sustainable remediation of aqueous organic pollutants.

  5. Activation of peroxymonosulfate by graphitic carbon nitride loaded on activated carbon for organic pollutants degradation.

    Science.gov (United States)

    Wei, Mingyu; Gao, Long; Li, Jun; Fang, Jia; Cai, Wenxuan; Li, Xiaoxia; Xu, Aihua

    2016-10-01

    Graphitic carbon nitride supported on activated carbon (g-C3N4/AC) was prepared through an in situ thermal approach and used as a metal free catalyst for pollutants degradation in the presence of peroxymonosulfate (PMS) without light irradiation. It was found that g-C3N4 was highly dispersed on the surface of AC with the increase of surface area and the exposition of more edges and defects. The much easier oxidation of C species in g-C3N4 to CO was also observed from XPS spectra. Acid Orange 7 (AO7) and other organic pollutants could be completely degraded by the g-C3N4/AC catalyst within 20min with PMS, while g-C3N4+PMS and AC+PMS showed no significant activity for the reaction. The performance of the catalyst was significantly influenced by the amount of g-C3N4 loaded on AC; but was nearly not affected by the initial solution pH and reaction temperature. In addition, the catalysts presented good stability. A nonradical mechanism accompanied by radical generation (HO and SO4(-)) in AO7 oxidation was proposed in the system. The CO groups play a key role in the process; while the exposure of more N-(C)3 group can further increase its electron density and basicity. This study can contribute to the development of green materials for sustainable remediation of aqueous organic pollutants. PMID:27214000

  6. Shock induced polymorphic transition in quartz, carbon, and boron nitride

    Science.gov (United States)

    Tan, Hua; Ahrens, Thomas J.

    1990-01-01

    The model proposed by Ahrens (1988) to explain the mechanism of the polymorphism in silicates is revised, and the revised model is applied to the quartz/stishovite, graphite/diamond, and graphite-boron nitride (g-BN) phase transformations. In this model, a key assumption is that transformation to a high-density amorphous or possibly liquid phase which rapidly crystallized to the high-pressure phase is triggered by the high temperatures in the shear band and upon crossing the metastable extension of a melting curve. Good agreement between the calcualted results and published data is obtained. The present theory predicts the standard entropy for cubic BN to be 0.4-0.5 J/g K.

  7. Electrical behavior of multi-walled carbon nanotube network embedded in amorphous silicon nitride

    Directory of Open Access Journals (Sweden)

    Buiculescu Raluca

    2011-01-01

    Full Text Available Abstract The electrical behavior of multi-walled carbon nanotube network embedded in amorphous silicon nitride is studied by measuring the voltage and temperature dependences of the current. The microstructure of the network is investigated by cross-sectional transmission electron microscopy. The multi-walled carbon nanotube network has an uniform spatial extension in the silicon nitride matrix. The current-voltage and resistance-temperature characteristics are both linear, proving the metallic behavior of the network. The I-V curves present oscillations that are further analyzed by computing the conductance-voltage characteristics. The conductance presents minima and maxima that appear at the same voltage for both bias polarities, at both 20 and 298 K, and that are not periodic. These oscillations are interpreted as due to percolation processes. The voltage percolation thresholds are identified with the conductance minima.

  8. Hydrogen production using zinc-doped carbon nitride catalyst irradiated with visible light

    Directory of Open Access Journals (Sweden)

    Bing Yue, Qiuye Li, Hideo Iwai, Tetsuya Kako and Jinhua Ye

    2011-01-01

    Full Text Available Recently, graphitic carbon nitride (g-C3N4 has been investigated as a photocatalyst for water splitting and organic dye degradation. In this study, we have developed a simple soft-chemical method of doping Zn into g-C3N4 to prepare a metal-containing carbon nitride. The doping was confirmed by x-ray photoelectron spectroscopy, and diffusion reflectance spectra revealed a significant red shift in the absorption edge of Zn/g-C3N4. This hybrid material shows high photocatalytic activity and good stability for hydrogen evolution from an aqueous methanol solution under visible light irradiation (λ≥420 nm. The hydrogen evolution rate was more than 10 times higher for a 10%-Zn/g-C3N4 sample (59.5 μmol h−1 than for pure g-C3N4. The maximum quantum yield was 3.2% at 420 nm.

  9. The energy landscape of fullerene materials: a comparison between boron, boron-nitride and carbon

    CERN Document Server

    De, Sandip; Amsler, Maximilian; Pochet, Pascal; Genovese, Luigi; Goedecker, Stefan

    2010-01-01

    Using the minima hopping global geometry optimization method on the density functional potential energy surface we study medium size and large boron clusters. Even though for isolated medium size clusters the ground state is a cage like structure they are unstable against external perturbations such as contact with other clusters. The energy landscape of larger boron clusters is glass like and has a large number of structures which are lower in energy than the cages. This is in contrast to carbon and boron nitride systems which can be clearly identified as structure seekers in our minima hopping runs. The differences in the potential energy landscape explain why carbon and boron nitride systems are found in nature whereas pure boron fullerenes have not been found.

  10. 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.

  11. Facile synthesis and enhanced visible-light photocatalysis of graphitic carbon nitride composite semiconductors.

    Science.gov (United States)

    Li, Huiquan; Liu, Yuxing; Gao, Xing; Fu, Cong; Wang, Xinchen

    2015-04-13

    The semiconductor heterojunction has been an effective architecture to enhance photocatalytic activity by promoting photogenerated charge separation. Here, graphitic carbon nitride (CN) and B-modified graphitic carbon nitride (CNB) composite semiconductors were fabricated by a facile calcination process using cheap, sustainable, and easily available sodium tetraphenylboron and urea as precursors. The synthetic CN-CNB-25 semiconductor with a suitable CNB content showed the highest visible-light activity. Its degradation ratio for methyl orange and phenol was more than twice that of CN and CNB and its H2 evolution rate was ∼3.4 and ∼1.8 times higher than that of CN and CNB, respectively. It also displayed excellent stability and reusability. The enhanced activity of CN-CNB-25 was attributed predominantly to the efficient separation of photoinduced electrons and holes. This paper describes a visible-light-responsive CN composite semiconductor with great potential in environmental and energy applications.

  12. 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.

  13. Ultra-thin epitaxial films of graphite and hexagonal boron nitride on solid surfaces

    CERN Document Server

    Oshima, C

    1997-01-01

    In this article, we have reviewed the recent progress of the experimental studies on ultra-thin films of graphite and hexagonal boron nitride (h-BN) by using angle-resolved electron spectroscopy together with other techniques. The fundamental properties of these high-quality films are discussed on the basis of the data on dispersion relations of valence electrons, phonon dispersion etc. The interfacial orbital mixing of the pi-state of the monolayer graphite (MG) with the d states of the reactive substrates is the origin for the phonon softening, expansion of the nearest-neighbour C-C distance, modification of the pi-band, low work function, and two-dimensional plasmons with high electron density, etc. In the cases of weak mixing at the interface between the MG and relatively inert substrates, the observed properties of the MG are very close to the bulk ones. In contrast to the case for MG, the interfacial interaction between the h-BN monolayer and the substrate is weak. (author)

  14. 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. PMID:26193701

  15. 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.

  16. 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.

  17. 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.

  18. 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.

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

    OpenAIRE

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

    2015-01-01

    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 n...

  20. 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.

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

    Directory of Open Access Journals (Sweden)

    Hongling Han

    2015-07-01

    Full Text Available 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.

  2. One Dimensional Graphitic Carbon Nitrides as Effective Metal-Free Oxygen Reduction Catalysts

    OpenAIRE

    Muhammad Tahir; Nasir Mahmood; Jinghan Zhu; Asif Mahmood; Butt, Faheem K.; Syed Rizwan; Imran Aslam; Tanveer, M.; Faryal Idrees; Imran Shakir; Chuanbao Cao; Yanglong Hou

    2015-01-01

    To explore the effect of morphology on catalytic properties of graphitic carbon nitride (GCN), we have studied oxygen reduction reaction (ORR) performance of two different morphologies of GCN in alkaline media. Among both, tubular GCN react with dissolved oxygen in the ORR with an onset potential close to commercial Pt/C. Furthermore, the higher stability and excellent methanol tolerance of tubular GCN compared to Pt/C emphasizes its suitability for fuel cells.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Fabrication of titanium nitride thin films by DC magneton sputtering on different types of substrates for coating applications

    International Nuclear Information System (INIS)

    Titanium nitride thin films (TiN) are fabricated by DC magneton sputtering on different types of substrates such as glass substrates, PET substrates, substrate alloy (AISI 304) and drill steel. In this work we study the effect of target-substrate distance, sputtering time and negative voltage to the crystal structure, mechanical and optical properties of the films. The properties of the thin films were studied by X-ray diffraction method Stylus, UV-Vis method and scanning electron microscopy. Results showed that the target-substrate distance, sputtering time and negative voltage affects the crystalline structure, mechanical and optical properties of the films. TiN films have been synthesized highly crystalline structure, crystal structure of thin films oriented along the surface lattice (111), (200) and (311). Besides TiN thin films also have high reflectance in the visible and infrared range, good adhesion, high chemical durability. (author)

  8. 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.

  9. 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.

  10. 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.

  11. Highly Selective and Stable Reduction of CO2 to CO by a Graphitic Carbon Nitride/Carbon Nanotube Composite Electrocatalyst.

    Science.gov (United States)

    Lu, Xunyu; Tan, Tze Hao; Ng, Yun Hau; Amal, Rose

    2016-08-16

    A stable and selective electrocatalyst for CO2 reduction was fabricated by covalently attaching graphitic carbon nitride onto multiwall carbon nanotubes (g-C3 N4 /MWCNTs). The as-prepared composite is able to reduce CO2 exclusively to CO with a maximum Faraday efficiency of 60 %, and no decay in the catalytic activity was observed even after 50 h of reaction. The enhanced catalytic activity towards CO2 reduction is attributed to the formation of active carbon-nitrogen bonds, high specific surface area, and improved material conductivity of the g-C3 N4 /MWCNT composite.

  12. 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.

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

    Science.gov (United States)

    Broas, M.; Liu, X.; Ge, Y.; Mattila, T. T.; Paulasto-Kröckel, M.

    2015-06-01

    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/SiNx 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 SiNx part of the films. Scanning electron microscopy revealed a porous-like reaction layer on top of SiNx. 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.

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

    International Nuclear Information System (INIS)

    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/SiNx 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 SiNx part of the films. Scanning electron microscopy revealed a porous-like reaction layer on top of SiNx. 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

  15. 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.

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

    Science.gov (United States)

    Guan, Weiwei; Gu, Wei; Ye, Ling; Guo, Chenyang; Su, Su; Xu, Pinxiang; Xue, Ming

    2014-01-01

    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. PMID:25382977

  17. Thermal conduction mechanisms in isotope-disordered boron nitride and carbon nanotubes

    Science.gov (United States)

    Savic, Ivana; Mingo, Natalio; Stewart, Derek

    2009-03-01

    We present first principles studies which determine dominant effects limiting the heat conduction in isotope-disordered boron nitride and carbon nanotubes [1]. Using an ab initio atomistic Green's function approach, we demonstrate that localization cannot be observed in the thermal conductivity measurements [1], and that diffusive scattering is the dominant mechanism which reduces the thermal conductivity [2]. We also give concrete predictions of the magnitude of the isotope effect on the thermal conductivities of carbon and boron nitride single-walled nanotubes [2]. We furthermore show that intershell scattering is not the main limiting mechanism for the heat flow through multi-walled boron nitride nanotubes [1], and that heat conduction restricted to a few shells leads to the low thermal conductivities experimentally measured [1]. We consequently successfully compare the results of our calculations [3] with the experimental measurements [1]. [1] C. W. Chang, A. M. Fennimore, A. Afanasiev, D. Okawa, T. Ikuno, H. Garcia, D. Li, A. Majumdar, A. Zettl, Phys. Rev. Lett. 2006, 97, 085901. [2] I. Savic, N. Mingo, D. A. Stewart, Phys. Rev. Lett. 2008, 101, 165502. [3] I. Savic, D. A. Stewart, N. Mingo, to be published.

  18. 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.

  19. Synthesis and Characterization of Carbon Nitride Films for Micro Humidity Sensors

    Directory of Open Access Journals (Sweden)

    Sung Pil Lee

    2008-03-01

    Full Text Available Nano-structured carbon nitride (CNx films were synthesized by a reactive RFmagnetron sputtering system with a DC bias under various deposition conditions, and theirphysical and electrical properties were investigated with a view to using them for microhumidity sensors. The FTIR spectra of the deposited films showed a C=N stretching bandin the range of 1600~1700 ㎝-1, depending on the amount of nitrogen incorporation. Thecarbon nitride films deposited on the Si substrate had a nano-structured surfacemorphology with a grain size of about 20 nm, and their deposition rate was 1.5 μm/hr. Thesynthesized films had a high electrical resistivity in the range of 108 to 109 ω·cm,depending on the deposition conditions. The micro humidity sensors showed a goodlinearity and low hysteresis between 5 ~ 95 %RH.

  20. Direct growth of graphene on gallium nitride using C2H2 as carbon source

    Science.gov (United States)

    Wang, Bing; Zhao, Yun; Yi, Xiao-Yan; Wang, Guo-Hong; Liu, Zhi-Qiang; Duan, Rui-Rei; Huang, Peng; Wang, Jun-Xi; Li, Jin-Min

    2016-04-01

    Growing graphene on gallium nitride (GaN) at temperatures greater than 900°C is a challenge that must be overcome to obtain high quality of GaN epi-layers. We successfully met this challenge using C2H2 as the carbon source. We demonstrated that graphene can be grown both on copper and directly on GaN epi-layers. The Raman spectra indicated that the graphene films were about 4-5 layers thick. Meanwhile, the effects of the growth temperature on the growth of the graphene films were systematically studied, and 830°C was found to be the optimum growth temperature. We successfully grew high-quality graphene films directly on gallium nitride.

  1. Effect of Nitridation Time on the Surface Hardness of Medium Carbon Steels (AISI 1045)

    International Nuclear Information System (INIS)

    It has been investigated the effect of nitridation time on the surface hardness of medium carbon steels (AISI 1045). Parameters determining to the results were flow rate of the nitrogen gas, temperature and time. In this experiments, sample having diameter of 15 mm, thick 2 mm placed in tube of glass with diameter 35 mm heated 550 oC, flow rate and temperature were kept constants, 100 cc/minutes and 550 oC respectively, while the time were varied from 5, 10, 20 and 30 hours. It was found, that for the nitridation time of 5, 10, 20, and 30 hours, the surface hardness increased from 145 VHN to, 23.7, 296.8, 382.4 and 426.1 VHN, respectively. (author)

  2. Optical characterization of nanocrystalline boron nitride thin films grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Snure, Michael, E-mail: michael.snure.1@us.af.mil [Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, OH (United States); Paduano, Qing; Hamilton, Merle [Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, OH (United States); Shoaf, Jodie [Wyle Laboratories, Inc., Wright-Patterson AFB, OH (United States); Mann, J. Matthew [Air Force Research Laboratory, Sensors Directorate, Wright-Patterson AFB, OH (United States)

    2014-11-28

    Boron nitride thin films were grown on sapphire and Si substrates by atomic layer deposition from triethylborane (TEB) and NH{sub 3} precursors in the temperature range of 500 to 900 °C. By varying the TEB exposure the film thickness can be controlled with< 1 nm precision. At 600 °C the process is self-limiting, but films are found to be amorphous. Films grown at higher temperatures were identified as sp{sup 2} BN, but the process is no longer self-limiting. From Raman and IR absorption spectroscopy films deposited at 900 °C were identified as nanocrystalline sp{sup 2} BN with crystallite sizes in the range of 3 to 8 nm depending on the NH{sub 3} dosage. Films deposited at lower temperatures had broad red shifted IR absorption peaks indicating the lack of long range ordering. The visible and UV optical properties of these films were characterized by UV–Vis transmission measurements over the range of 800 to 190 nm. Nanocrystalline films are highly transparent over this range up to the band gap, which was measured to be in the range of 5.83 to 5.65 eV depending on the NH{sub 3} dosage. - Highlights: • Atomic layer deposition of BN with< 1 nm per cycle deposition rates • A narrow self-limiting temperature window was found. • Nanocrystalline h-BN films with a wide transparence window with E{sub g} up to 5.85 eV.

  3. Structural and optical characterization of pure Si-rich nitride thin films

    Science.gov (United States)

    Debieu, Olivier; Nalini, Ramesh Pratibha; Cardin, Julien; Portier, Xavier; Perrière, Jacques; Gourbilleau, Fabrice

    2013-01-01

    The specific dependence of the Si content on the structural and optical properties of O- and H-free Si-rich nitride (SiN x>1.33) thin films deposited by magnetron sputtering is investigated. A semiempirical relation between the composition and the refractive index was found. In the absence of Si-H, N-H, and Si-O vibration modes in the FTIR spectra, the transverse and longitudinal optical (TO-LO) Si-N stretching pair modes could be unambiguously identified using the Berreman effect. With increasing Si content, the LO and the TO bands shifted to lower wavenumbers, and the LO band intensity dropped suggesting that the films became more disordered. Besides, the LO and the TO bands shifted to higher wavenumbers with increasing annealing temperature which may result from the phase separation between Si nanoparticles (Si-np) and the host medium. Indeed, XRD and Raman measurements showed that crystalline Si-np formed upon 1100°C annealing but only for SiN x0.9, demonstrating that this PL is not originating from confined states in crystalline Si-np. As an additional proof, the PL was quenched while crystalline Si-np could be formed by laser annealing. Besides, the PL cannot be explained neither by defect states in the bandgap nor by tail to tail recombination. The PL properties of SiN x>0.9 could be then due to a size effect of Si-np but having an amorphous phase.

  4. 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.

  5. Improved piezoelectric constants of sputtered aluminium nitride thin films by pre-conditioning of the silicon surface

    Science.gov (United States)

    Schneider, M.; Bittner, A.; Schmid, U.

    2015-10-01

    The group III-V material aluminium nitride (AlN) is frequently used in micro-electromechanical devices and systems (MEMS) due to its piezoelectric properties, its high thermal and electrical stability as well as its compatibility with CMOS technology. But, the trend towards miniaturization of MEMS devices requests a continuous decrease in geometrical dimensions of the active AlN thin film, thus demanding at least the same piezoelectric properties at lower film thickness. In this work, two different approaches are applied to measure the piezoelectric coefficients, using the direct as well as the converse piezoelectric effect. The first approach utilizes laser doppler vibrometry measurements in combination with finite element analysis, allowing the determination of d 33 and d 31. For the second method, an oscillating force is applied to the thin film and the generated charge is measured. A surface-near substrate conditioning step applying sputter etching is used in order to improve the piezoelectric coefficients over a wide thickness range (i.e. 40 nm to 400 nm) by about 20% compared to samples without pre-treatment. Basically, the coefficients remain constant for a film thickness of 100 nm and above, thus allowing the application of thin active layers of aluminium nitride without any reduction in the sensing and actuation potential.

  6. 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.

  7. Mechanical properties measurement of silicon nitride thin films using the bulge test

    Science.gov (United States)

    Lee, Hun Kee; Ko, Seong Hyun; Han, Jun Soo; Park, HyunChul

    2007-12-01

    The mechanical properties of silicon nitride films are investigated. Freestanding films of silicon nitride are fabricated using the MEMS technique. The films were deposited onto (100) silicon wafers by LPCVD (Low Pressure Chemical Vapor Deposition). Square and rectangular membranes are made by anisotropic etching of the silicon substrates. Then the bulge test for silicon nitride film was carried out. The thickness of specimens was 0.5, 0.75 and 1μm respectively. By testing both square and rectangular membranes, the reliability and valiant-ness of bulge test with regard to the shape of specimens was investigated. Also considering residual stress in the films, one can evaluate the Young's modulus from experimental load-deflection curves. Young's modulus of the silicon nitride films was about 232GPa. The residual stress is below 100MPa.

  8. 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.

  9. Influence of Bias on the Properties of Carbon Nitride Films Prepared by Vacuum Cathodic Arc Method

    Institute of Scientific and Technical Information of China (English)

    Zhimin ZHOU; Lifang XIA; Mingren SUN

    2004-01-01

    Carbon nitride films have been synthesized in a wide range of biases from 0 to -900 V by vacuum cathodic arc method. The N content was about 12.0~22.0 at. Pct. Upon increasing the biases from 0 to -100 V, the N content increased from 15.0 to 22.0 at. Pct which could be attributed to the knot-on effect. While the further increasing biases led to the gradual falling of the N content to 12.0 at. Pct at -900 V due to the enhancement of the sputtering effect. Below -200 V, with the increasing biases the sp2C fraction in the films decreased, as a result of which the I(D)/I(G) fell in the Raman spectra and the sp peaks also showed the decreasing tendency relative to the s peaks in the VBXPS (valence band X-ray photoelectron spectroscopy). While above -200 V, the sp2C fraction increased and the films became graphitinized gradually, accompanying which theI(D)/I(G) rose from -200 V to -300 V and the Raman spectra even showed the graphite characteristic above -300 V and the sp peaks rose again relative to the s peak. The carbon nitride films mainly consist of three types of bonding: CC, sp2CN and sp3CN bonds. In the first stage the sp3CN relative ratio rises and falls in the second stage, which corresponded well with the variation of the sp2C in the films. The subplantation mechanism resulting from the effect of ion energy played an important role in decidingthe variation of the microstructure of the carbon nitride films.

  10. Carbon nanotubes with atomic impurities on boron nitride sheets under applied electric fields

    OpenAIRE

    Kang, Seoung-Hun; Kim, Gunn; Kwon, Young-Kyun

    2013-01-01

    We perform first-principles calculations to investigate the structural and electronic properties of metal-doped (10, 0) carbon nanotubes (CNTs) on a single hexagonal boron nitride (hBN) sheet in the presence of an external electric field. We consider K, Cl and Ni atoms as dopants to study the dependence of the electronic properties of the CNT on doping polarity and concentration. The electric field strength is varied from -0.2 V/\\AA to +0.2 V/\\AA to explore the effects of an external electric...

  11. Synthesis, Al3+/Mg2+ Intercalation and Structure Study of Graphite-like Carbon Nitride

    Institute of Scientific and Technical Information of China (English)

    Xifeng Lu; Hongjun Wang; Yi Yang; Tao Liu

    2011-01-01

    Graphite-like carbon nitride (g-C3N4) was synthesized in large quantities at 300℃ under nitrogen by a solidstate reaction route. Furthermore, Al3+ and Mg2+ intercalation of g-C3N4 was performed by an electrochemical method. The starting C3N4 materials and intercalation compounds were characterized by X-ray powder diffraction, Fourier transform infrared spectra, thermogravimetry, transmission electron microscopy, and X-ray photoelectron spectroscopy. The possible structure model of intercalation compounds was proposed. The cation-π interactions and electrostatic interactions were used to explain the changes of microstructure and chemical bonds before and after intercalation.

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

    Directory of Open Access Journals (Sweden)

    Haijun Shen

    2012-01-01

    Full Text Available 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 deformation is, the lower the thermal conductivity is; the whole compression has more remarkable effect on thermal conductivity than the local compression.

  13. 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.

  14. 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

  15. Chemically Modulated Carbon Nitride Nanosheets for Highly Selective Electrochemiluminescent Detection of Multiple Metal-ions.

    Science.gov (United States)

    Zhou, Zhixin; Shang, Qiuwei; Shen, Yanfei; Zhang, Linqun; Zhang, Yuye; Lv, Yanqin; Li, Ying; Liu, Songqin; Zhang, Yuanjian

    2016-06-01

    Chemical structures of two-dimensional (2D) nanosheet can effectively control the properties thus guiding their applications. Herein, we demonstrate that carbon nitride nanosheets (CNNS) with tunable chemical structures can be obtained by exfoliating facile accessible bulk carbon nitride (CN) of different polymerization degree. Interestingly, the electrochemiluminescence (ECL) properties of as-prepared CNNS were significantly modulated. As a result, unusual changes for different CNNS in quenching of ECL because of inner filter effect/electron transfer and enhancement of ECL owing to catalytic effect were observed by adding different metal ions. On the basis of this, by using various CNNS, highly selective ECL sensors for rapid detecting multiple metal-ions such as Cu(2+), Ni(2+), and Cd(2+) were successfully developed without any labeling and masking reagents. Multiple competitive mechanisms were further revealed to account for such enhanced selectivity in the proposed ECL sensors. The strategy of preparing CNNS with tunable chemical structures that facilely modulated the optical properties would open a vista to explore 2D carbon-rich materials for developing a wide range of applications such as sensors with enhanced performances.

  16. Chemically Modulated Carbon Nitride Nanosheets for Highly Selective Electrochemiluminescent Detection of Multiple Metal-ions.

    Science.gov (United States)

    Zhou, Zhixin; Shang, Qiuwei; Shen, Yanfei; Zhang, Linqun; Zhang, Yuye; Lv, Yanqin; Li, Ying; Liu, Songqin; Zhang, Yuanjian

    2016-06-01

    Chemical structures of two-dimensional (2D) nanosheet can effectively control the properties thus guiding their applications. Herein, we demonstrate that carbon nitride nanosheets (CNNS) with tunable chemical structures can be obtained by exfoliating facile accessible bulk carbon nitride (CN) of different polymerization degree. Interestingly, the electrochemiluminescence (ECL) properties of as-prepared CNNS were significantly modulated. As a result, unusual changes for different CNNS in quenching of ECL because of inner filter effect/electron transfer and enhancement of ECL owing to catalytic effect were observed by adding different metal ions. On the basis of this, by using various CNNS, highly selective ECL sensors for rapid detecting multiple metal-ions such as Cu(2+), Ni(2+), and Cd(2+) were successfully developed without any labeling and masking reagents. Multiple competitive mechanisms were further revealed to account for such enhanced selectivity in the proposed ECL sensors. The strategy of preparing CNNS with tunable chemical structures that facilely modulated the optical properties would open a vista to explore 2D carbon-rich materials for developing a wide range of applications such as sensors with enhanced performances. PMID:27187874

  17. 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.

  18. 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.

  19. Three-dimensional Carbon Nitride/Graphene Framework as a High-Performance Cathode for Lithium-Ion Batteries.

    Science.gov (United States)

    Huang, Yanshan; Tang, Yanping; Mai, Yiyong; Wang, Xinjing; Wang, Chi; Han, Sheng; Zhang, Fan; Wu, Dongqing; Feng, Xinliang

    2016-04-20

    A three-dimensional polymeric carbon nitride/graphene framework (CN/GF) was fabricated by the ionic self-assembly of graphene oxide and protonated polymeric carbon nitride nanosheets. As the cathode material in lithium-ion batteries, CN/GF showed an excellent reversible capacity of 184 mA h g(-1) at 0.05 A g(-1) for 150 cycles and maintained the capacity of 60 mA h g(-1) at 5 A g(-1) .

  20. Thin film silicon on silicon nitride for radiation hardened dielectrically isolated MISFET's

    International Nuclear Information System (INIS)

    The permanent ionizing radiation effects resulting from charge trapping in a silicon nitride isolation dielectric have been determined for a total ionizing dose up to 107 rads (Si). Junction FET's, whose active channel region is directly adjacent to the silicon-silicon nitride interface, were used to measure the effects of the radiation induced charge trapping in the Si3N4 isolation dielectric. The JFET saturation current and channel conductance versus junction gate voltage and substrate voltage were characterized as a function of the total ionizing radiation dose. The experimental results on the Si3N4 are compared to results on similar devices with SiO2 dielectric isolation. The ramifications of using the silicon nitride for fabricating radiation hardened dielectrically isolated MIS devices are discussed

  1. Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

    Science.gov (United States)

    Alam, M. T.; Bresnehan, M. S.; Robinson, J. A.; Haque, M. A.

    2014-01-01

    Thermal conductivity of freestanding 10 nm and 20 nm thick chemical vapor deposited hexagonal boron nitride films was measured using both steady state and transient techniques. The measured value for both thicknesses, about 100 ± 10 W m-1 K-1, is lower than the bulk basal plane value (390 W m-1 K-1) due to the imperfections in the specimen microstructure. Impressively, this value is still 100 times higher than conventional dielectrics. Considering scalability and ease of integration, hexagonal boron nitride grown over large area is an excellent candidate for thermal management in two dimensional materials-based nanoelectronics.

  2. A ternary hybrid of carbon nanotubes/graphitic carbon nitride nanosheets/gold nanoparticles used as robust substrate electrodes in enzyme biofuel cells.

    Science.gov (United States)

    Gai, Panpan; Song, Rongbin; Zhu, Cheng; Ji, Yusheng; Chen, Yun; Zhang, Jian-Rong; Zhu, Jun-Jie

    2015-10-11

    A novel ternary hybrid of carbon nanotubes/graphitic carbon nitride nanosheets/gold nanoparticles was prepared and used as robust substrate electrodes for fabricating membrane-less glucose/O2 enzyme biofuel cells (EBFCs), and a remarkably improved power output was observed for the prepared EBFC.

  3. Integrated oxygen-doping and dye sensitization of graphitic carbon nitride for enhanced visible light photodegradation.

    Science.gov (United States)

    Liu, Shizhen; Sun, Hongqi; Ang, H M; Tade, Moses O; Wang, Shaobin

    2016-08-15

    Graphitic carbon nitride (GCN) is a promising metal-free photocatalyst while suffering from low charge mobility induced inefficient photocatalysis. In this work, oxygen doping was employed to enhance the photodegradation of organic pollutants in water on graphitic carbon nitride (GCNO) under visible light. For further absorption extension, four organic dyes (Eosin-Y, Perylene, Nile-red and Coumarin) were adopted to dye-sensitize the GCNO photocatalyst. It was found that O-doping can promote dye sensitization, which was dependent on the type of dyes and influenced the photodegradation efficiencies of methylene blue (MB) and phenol. Nile-red sensitized GCNO presented the best activity in MB degradation under λ>480nm irradiations while Eosin-Y showed the best sensitization performance for phenol degradation under λ>420nm light source. However, dye sensitization was not effective for enhanced pollutant degradation on GCN without O-doping. UV-vis diffuse reflectance spectra (UV-vis DRS), photoluminescence (PL) spectra, and photocurrent analyses were applied to investigate the mechanism of carriers' transfer, which indicated that dye molecules could inject extra electrons into GCNO energy band and the energy dislocation could suppress electron/hole recombination, enhancing photocatalytic performances. PMID:27218807

  4. Integrated oxygen-doping and dye sensitization of graphitic carbon nitride for enhanced visible light photodegradation.

    Science.gov (United States)

    Liu, Shizhen; Sun, Hongqi; Ang, H M; Tade, Moses O; Wang, Shaobin

    2016-08-15

    Graphitic carbon nitride (GCN) is a promising metal-free photocatalyst while suffering from low charge mobility induced inefficient photocatalysis. In this work, oxygen doping was employed to enhance the photodegradation of organic pollutants in water on graphitic carbon nitride (GCNO) under visible light. For further absorption extension, four organic dyes (Eosin-Y, Perylene, Nile-red and Coumarin) were adopted to dye-sensitize the GCNO photocatalyst. It was found that O-doping can promote dye sensitization, which was dependent on the type of dyes and influenced the photodegradation efficiencies of methylene blue (MB) and phenol. Nile-red sensitized GCNO presented the best activity in MB degradation under λ>480nm irradiations while Eosin-Y showed the best sensitization performance for phenol degradation under λ>420nm light source. However, dye sensitization was not effective for enhanced pollutant degradation on GCN without O-doping. UV-vis diffuse reflectance spectra (UV-vis DRS), photoluminescence (PL) spectra, and photocurrent analyses were applied to investigate the mechanism of carriers' transfer, which indicated that dye molecules could inject extra electrons into GCNO energy band and the energy dislocation could suppress electron/hole recombination, enhancing photocatalytic performances.

  5. An alkali treating strategy for the colloidization of graphitic carbon nitride and its excellent photocatalytic performance.

    Science.gov (United States)

    Cheng, Fuxing; Yan, Jing; Zhou, Chenjuan; Chen, Binhe; Li, Peiran; Chen, Zhi; Dong, Xiaoping

    2016-04-15

    The colloid of graphitic carbon nitride (g-C3N4) was of great importance for practical application. Herein we introduced an alkali treatment route to efficiently colloidize g-C3N4 under mild conditions by destroying the hydrogen bonds between linearly polymeric melon chains and hydrolyzing partial C−NH−C bonds linked two tri-s-triazine units. The obtained colloidal suspension was extremely stable due to its negative charges on surface, and the particle size of several hundred nanometers and the nanobelt-like morphology were revealed by electron microscopy and dynamic light scattering technologies. The structural, optical and functional group analysis demonstrated that the structure of CN heterocycles was preserved after the alkali treatment, and the produced colloidal g-C3N4 can be re-assembled by an electrostatic interaction. Moreover, contributing to the reduced electron-hole recombination, the photocatalytic performance of restacked carbon nitride colloids had more enhanced photocatalytic performance than bulk g-C3N4.

  6. 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

  7. 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.

  8. 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.

  9. An alkali treating strategy for the colloidization of graphitic carbon nitride and its excellent photocatalytic performance.

    Science.gov (United States)

    Cheng, Fuxing; Yan, Jing; Zhou, Chenjuan; Chen, Binhe; Li, Peiran; Chen, Zhi; Dong, Xiaoping

    2016-04-15

    The colloid of graphitic carbon nitride (g-C3N4) was of great importance for practical application. Herein we introduced an alkali treatment route to efficiently colloidize g-C3N4 under mild conditions by destroying the hydrogen bonds between linearly polymeric melon chains and hydrolyzing partial C−NH−C bonds linked two tri-s-triazine units. The obtained colloidal suspension was extremely stable due to its negative charges on surface, and the particle size of several hundred nanometers and the nanobelt-like morphology were revealed by electron microscopy and dynamic light scattering technologies. The structural, optical and functional group analysis demonstrated that the structure of CN heterocycles was preserved after the alkali treatment, and the produced colloidal g-C3N4 can be re-assembled by an electrostatic interaction. Moreover, contributing to the reduced electron-hole recombination, the photocatalytic performance of restacked carbon nitride colloids had more enhanced photocatalytic performance than bulk g-C3N4. PMID:26835580

  10. Li and Na Co-decorated carbon nitride nanotubes as promising new hydrogen storage media

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu Sheng [Center of Clean Energy and Quantum Structures, and School of Physics and Engineering, Zhengzhou University, Zhengzhou, Henan, 450052 (China); College of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou, Henan, 450011 (China); Li, Meng; Wang, Fei; Sun, Qiang [Center of Clean Energy and Quantum Structures, and School of Physics and Engineering, Zhengzhou University, Zhengzhou, Henan, 450052 (China); Jia, Yu, E-mail: jiayu@zzu.edu.cn [Center of Clean Energy and Quantum Structures, and School of Physics and Engineering, Zhengzhou University, Zhengzhou, Henan, 450052 (China)

    2012-01-09

    The capacity of Li and Na co-decorated carbon nitride nanotube (CNNT) for hydrogen storage is studied using first-principles density functional theory. The results show that with two H{sub 2} molecules attached to per Li and four H{sub 2} molecules per Na the Li and Na co-decorated CNNT gains a gravimetric density of H{sub 2} as high as 9.09 wt% via electrostatic interaction without the clustering of the deposited metal atoms (at T=0 K). The average adsorption energy of hydrogen molecule is in the range of 0.09–0.22 eV/H{sub 2}, which is suitable for practical hydrogen storage at ambient temperatures. -- Highlights: ► Li and Na co-decorated carbon nitride nanotubes as hydrogen storage media. ► The gravimetric density of H{sub 2} is 9.09 wt%. ► The average adsorption energy of hydrogen molecule is 0.09–0.22 eV/H{sub 2}. ► It can operate under ambient thermodynamic conditions.

  11. 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.

  12. Controlled translocation of DNA through nanopores in carbon nano-, silicon-nitride- and lipid-coated membranes.

    Science.gov (United States)

    Sischka, Andy; Galla, Lukas; Meyer, Andreas J; Spiering, Andre; Knust, Sebastian; Mayer, Michael; Hall, Adam R; Beyer, André; Reimann, Peter; Gölzhäuser, Armin; Anselmetti, Dario

    2015-07-21

    We investigated experimentally and theoretically the translocation forces when a charged polymer is threaded through a solid-state nanopore and found distinct dependencies on the nanopore diameter as well as on the nano membrane material chemistry. For this purpose we utilized dedicated optical tweezers force mechanics capable of probing the insertion of negatively charged double-stranded DNA inside a helium-ion drilled nanopore. We found that both the diameter of the nanopore and the membrane material itself have significant influences on the electroosmotic flow through the nanopore and thus on the threading force. Compared to a bare silicon-nitride membrane, the threading of DNA through only 3 nm thin carbon nano membranes as well as lipid bilayer-coated nanopores increased the threading force by 15% or 85%, respectively. This finding was quantitatively described by our recently developed theoretical model that also incorporates hydrodynamic slip effects on the translocating DNA molecule and the force dependence on the membrane thickness. The additional measurements presented in this paper further support our model.

  13. Functionalized Graphitic Carbon Nitride for Metal-free, Flexible and Rewritable Nonvolatile Memory Device via Direct Laser-Writing

    Science.gov (United States)

    Zhao, Fei; Cheng, Huhu; Hu, Yue; Song, Long; Zhang, Zhipan; Jiang, Lan; Qu, Liangti

    2014-01-01

    Graphitic carbon nitride nanosheet (g-C3N4-NS) has layered structure similar with graphene nanosheet and presents unusual physicochemical properties due to the s-triazine fragments. But their electronic and electrochemical applications are limited by the relatively poor conductivity. The current work provides the first example that atomically thick g-C3N4-NSs are the ideal candidate as the active insulator layer with tunable conductivity for achieving the high performance memory devices with electrical bistability. Unlike in conventional memory diodes, the g-C3N4-NSs based devices combined with graphene layer electrodes are flexible, metal-free and low cost. The functionalized g-C3N4-NSs exhibit desirable dispersibility and dielectricity which support the all-solution fabrication and high performance of the memory diodes. Moreover, the flexible memory diodes are conveniently fabricated through the fast laser writing process on graphene oxide/g-C3N4-NSs/graphene oxide thin film. The obtained devices not only have the nonvolatile electrical bistability with great retention and endurance, but also show the rewritable memory effect with a reliable ON/OFF ratio of up to 105, which is the highest among all the metal-free flexible memory diodes reported so far, and even higher than those of metal-containing devices. PMID:25073687

  14. Electrochemistry of Layered Graphitic Carbon Nitride Synthesised from Various Precursors: Searching for Catalytic Effects.

    Science.gov (United States)

    Yew, Ying Teng; Lim, Chee Shan; Eng, Alex Yong Sheng; Oh, Junghoon; Park, Sungjin; Pumera, Martin

    2016-02-16

    Graphitic carbon nitride (g-C3 N4 ), synthesised by pyrolysis of different precursors (dicyandiamide, melamine and urea) under varying reaction conditions (air and nitrogen gas) is subjected to electrochemical studies for the elucidation of the inherent catalytic efficiency of the pristine material. Contrary to popular belief, pristine g-C3 N4 shows negligible, if any, enhancement in its electrochemical behaviour in this comprehensive study. Voltammetric analysis reveals g-C3 N4 to display similar catalytic efficiency to the unmodified glassy carbon electrode surface on which the bulk material was deposited. This highlights the non-catalytic nature of the pristine material and challenges the feasibility of using g-C3 N4 as a heterogeneous catalyst to deliver numerous promised applications.

  15. Reversible Assembly of Graphitic Carbon Nitride 3D Network for Highly Selective Dyes Absorption and Regeneration.

    Science.gov (United States)

    Zhang, Yuye; Zhou, Zhixin; Shen, Yanfei; Zhou, Qing; Wang, Jianhai; Liu, Anran; Liu, Songqin; Zhang, Yuanjian

    2016-09-27

    Responsive assembly of 2D materials is of great interest for a range of applications. In this work, interfacial functionalized carbon nitride (CN) nanofibers were synthesized by hydrolyzing bulk CN in sodium hydroxide solution. The reversible assemble and disassemble behavior of the as-prepared CN nanofibers was investigated by using CO2 as a trigger to form a hydrogel network at first. Compared to the most widespread absorbent materials such as active carbon, graphene and previously reported supramolecular gel, the proposed CN hydrogel not only exhibited a competitive absorbing capacity (maximum absorbing capacity of methylene blue up to 402 mg/g) but also overcame the typical deficiencies such as poor selectivity and high energy-consuming regeneration. This work would provide a strategy to construct a 3D CN network and open an avenue for developing smart assembly for potential applications ranging from environment to selective extraction.

  16. 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.

  17. In situ mechanical property measurements of amorphous carbon-boron nitride nanotube nanostructures

    Science.gov (United States)

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

    2012-01-01

    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.

  18. 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)

  19. Preparation of carbon nitride fine powder by laser induced gas-phase reactions

    Science.gov (United States)

    Alexandrescu, R.; Huisken, F.; Pugna, G.; Crunteanu, A.; Petcu, S.; Cojocaru, S.; Cireasa, R.; Morjan, I.

    We present the possibility of carbon nitride fine powder synthesis by sensitized laser pyrolysis of acethylene/nitrous oxide/ammonia mixtures. The powders were analyzed using X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and IR transmission measurements. It was found that nitrogen was incorporated in powders and that in the carbon-nitrogen phases formed, the presence of the triple bonded C≡N was not detected. The majority of X-ray diffraction data suggests the presence of a mixture of the predicted α- and β-C3N4 structure, with an α-C3N4-like form being prevalent. The powders were found to be slightly contaminated by SF6 sensitizer products. Our results suggest that by improving the experimental parameters this contamination might be reduced and that the laser pyrolysis method offers possibilities for production of CxNy materials, with controlled composition.

  20. Controlled route to the fabrication of carbon and boron nitride nanoscrolls: A molecular dynamics investigation

    Science.gov (United States)

    Perim, Eric; Paupitz, Ricardo; Galvão, Douglas S.

    2013-02-01

    Carbon nanoscrolls (graphene layers rolled up into papyrus-like tubular structures) are nanostructures with unique and interesting characteristics that could be exploited to build several new nanodevices. However, an efficient and controlled synthesis of these structures was not achieved yet, making its large scale production a challenge to materials scientists. Also, the formation process and detailed mechanisms that occur during its synthesis are not completely known. In this work, using fully atomistic molecular dynamics simulations, we discuss a possible route to nanoscrolls made from graphene layers deposited over silicon oxide substrates containing chambers/pits. The scrolling mechanism is triggered by carbon nanotubes deposited on the layers. The process is completely general and can be used to produce scrolls from other lamellar materials, like boron nitride, for instance.

  1. 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.

  2. 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.

  3. 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.

  4. 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)

  5. Merging Single-Atom-Dispersed Silver and Carbon Nitride to a Joint Electronic System via Copolymerization with Silver Tricyanomethanide.

    Science.gov (United States)

    Chen, Zupeng; Pronkin, Sergey; Fellinger, Tim-Patrick; Kailasam, Kamalakannan; Vilé, Gianvito; Albani, Davide; Krumeich, Frank; Leary, Rowan; Barnard, Jon; Thomas, John Meurig; Pérez-Ramírez, Javier; Antonietti, Markus; Dontsova, Dariya

    2016-03-22

    Herein, we present an approach to create a hybrid between single-atom-dispersed silver and a carbon nitride polymer. Silver tricyanomethanide (AgTCM) is used as a reactive comonomer during templated carbon nitride synthesis to introduce both negative charges and silver atoms/ions to the system. The successful introduction of the extra electron density under the formation of a delocalized joint electronic system is proven by photoluminescence measurements, X-ray photoelectron spectroscopy investigations, and measurements of surface ζ-potential. At the same time, the principal structure of the carbon nitride network is not disturbed, as shown by solid-state nuclear magnetic resonance spectroscopy and electrochemical impedance spectroscopy analysis. The synthesis also results in an improvement of the visible light absorption and the development of higher surface area in the final products. The atom-dispersed AgTCM-doped carbon nitride shows an enhanced performance in the selective hydrogenation of alkynes in comparison with the performance of other conventional Ag-based materials prepared by spray deposition and impregnation-reduction methods, here exemplified with 1-hexyne. PMID:26863408

  6. Merging Single-Atom-Dispersed Silver and Carbon Nitride to a Joint Electronic System via Copolymerization with Silver Tricyanomethanide.

    Science.gov (United States)

    Chen, Zupeng; Pronkin, Sergey; Fellinger, Tim-Patrick; Kailasam, Kamalakannan; Vilé, Gianvito; Albani, Davide; Krumeich, Frank; Leary, Rowan; Barnard, Jon; Thomas, John Meurig; Pérez-Ramírez, Javier; Antonietti, Markus; Dontsova, Dariya

    2016-03-22

    Herein, we present an approach to create a hybrid between single-atom-dispersed silver and a carbon nitride polymer. Silver tricyanomethanide (AgTCM) is used as a reactive comonomer during templated carbon nitride synthesis to introduce both negative charges and silver atoms/ions to the system. The successful introduction of the extra electron density under the formation of a delocalized joint electronic system is proven by photoluminescence measurements, X-ray photoelectron spectroscopy investigations, and measurements of surface ζ-potential. At the same time, the principal structure of the carbon nitride network is not disturbed, as shown by solid-state nuclear magnetic resonance spectroscopy and electrochemical impedance spectroscopy analysis. The synthesis also results in an improvement of the visible light absorption and the development of higher surface area in the final products. The atom-dispersed AgTCM-doped carbon nitride shows an enhanced performance in the selective hydrogenation of alkynes in comparison with the performance of other conventional Ag-based materials prepared by spray deposition and impregnation-reduction methods, here exemplified with 1-hexyne.

  7. 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

    2016-08-01

    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.

  8. Hollow porous carbon nitride immobilized on carbonized nanofibers for highly efficient visible light photocatalytic removal of NO.

    Science.gov (United States)

    Wu, Hongxin; Chen, Dongyun; Li, Najun; Xu, Qingfeng; Li, Hua; He, Jinghui; Lu, Jianmei

    2016-06-01

    With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability. PMID:27245319

  9. A combined SNMS and EFTEM/EELS study on focused ion beam prepared vanadium nitride thin films

    Science.gov (United States)

    Kothleitner, Gerald; Rogers, M.; Berendes, A.; Bock, W.; Kolbesen, B. O.

    2005-09-01

    We investigated the diffusion profiles and core-loss fine-structures (ELNES) of thin vanadium nitride films by electron energy-loss spectroscopy (EELS) and energy filtering transmission electron microscopy (EFTEM). The nitride layers have been produced by rapid thermal processing in a NH 3 or N 2 atmosphere and have then been cross-sectioned with a focused ion beam instrument (FIB) under mild milling conditions to maintain crystallography. For the high-resolution electron energy-loss spectroscopy studies (HREELS), a recently developed TEM gun monochromator, implemented into a 200 kV field emission gun column was used in combination with a new post-column spectrometer. It was found that, dependent on substrate and atmosphere, layers with different vanadium and nitrogen content were formed, showing distinct differences in their ELNES. With an energy resolution at the 0.2 eV level and a TEM beam spot size of approximately 2 nm these layers could be unambiguously identified when compared to theoretical ELNES simulations from the literature.

  10. Constructing a novel carbon nitride/polyaniline/ZnO ternary heterostructure with enhanced photocatalytic performance using exfoliated carbon nitride nanosheets as supports.

    Science.gov (United States)

    Pandiselvi, Kannusamy; Fang, Huaifang; Huang, Xiubo; Wang, Jingyu; Xu, Xiaochan; Li, Tao

    2016-08-15

    Graphitic carbon nitride (CN) is an emerging photocatalyst with promising prospect, but presently it still falls short on photocatalytic efficiency and photoresponsive range. We herein constructed a novel ternary heterostructure by hybridization of conducting polymer and semiconductor with CN. The exfoliated two dimension CN nanosheets (CN-NSs) are superior to bulk CN as both catalysts and supporting materials. Most recently, there are few reports involving the construction of heterojunction photocatalysts using CN-NSs as supports. The improvement of charge separation efficiency, specific surface area and visible light harvesting is simultaneously achieved in such a novel ternary heterostructure due to the synergetic effect of polyaniline (PANI) and ZnO coupling. As a result, the CN-NS/PANI/ZnO photocatalyst possesses excellent visible photocatalytic performance for MB and 4-CP degradation with a rate constant of 0.026 and 0.0049min(-1), which is about 3.6 and 3.3 times of CN, respectively. The enhanced mechanism is proposed based on the confirmation of OH and h(+) as main oxidative species. Overall, this work can not only yield high-efficient visible photocatalysts but also provide deeper insight into the enhanced mechanisms of CN-NS-based ternary heterostructure.

  11. Logic circuits composed of flexible carbon nanotube thin-film transistor and ultra-thin polymer gate dielectric

    Science.gov (United States)

    Lee, Dongil; Yoon, Jinsu; Lee, Juhee; Lee, Byung-Hyun; Seol, Myeong-Lok; Bae, Hagyoul; Jeon, Seung-Bae; Seong, Hyejeong; Im, Sung Gap; Choi, Sung-Jin; Choi, Yang-Kyu

    2016-05-01

    Printing electronics has become increasingly prominent in the field of electronic engineering because this method is highly efficient at producing flexible, low-cost and large-scale thin-film transistors. However, TFTs are typically constructed with rigid insulating layers consisting of oxides and nitrides that are brittle and require high processing temperatures, which can cause a number of problems when used in printed flexible TFTs. In this study, we address these issues and demonstrate a method of producing inkjet-printed TFTs that include an ultra-thin polymeric dielectric layer produced by initiated chemical vapor deposition (iCVD) at room temperature and highly purified 99.9% semiconducting carbon nanotubes. Our integrated approach enables the production of flexible logic circuits consisting of CNT-TFTs on a polyethersulfone (PES) substrate that have a high mobility (up to 9.76 cm2 V‑1 sec‑1), a low operating voltage (less than 4 V), a high current on/off ratio (3 × 104), and a total device yield of 90%. Thus, it should be emphasized that this study delineates a guideline for the feasibility of producing flexible CNT-TFT logic circuits with high performance based on a low-cost and simple fabrication process.

  12. Hollow porous carbon nitride immobilized on carbonized nanofibers for highly efficient visible light photocatalytic removal of NO

    Science.gov (United States)

    Wu, Hongxin; Chen, Dongyun; Li, Najun; Xu, Qingfeng; Li, Hua; He, Jinghui; Lu, Jianmei

    2016-06-01

    With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability.With the deterioration of air quality, great efforts were devoted to designing various photocatalysts for effective removal of NOx in air. However, the present photocatalysts have a fatal problem of low photocatalytic efficiency. In this work, a hollow porous carbon nitride nanosphere coupled with reduced graphene oxide (HCNS/rGO) was exploited as a visible-light photocatalyst to remove nitrogen monoxide in air at a low concentration (600 ppb level) under irradiation of an energy saving lamp. HCNS/rGO showed a NO removal ratio of 64%, which was superior to that of most other visible-light photocatalysts. The excellent photocatalytic ability of HCNS/rGO originates from the hollow porous morphology of HCNS and the grafted rGO on the surface. HCNS/rGO was immobilized on porous carbonized polymer nanofibers to obtain a photocatalytic membrane without affecting photocatalytic efficiency. Furthermore, the membrane showed excellent photochemical stability and recyclability. Electronic supplementary information

  13. Wetting behaviour of carbon nitride nanostructures grown by plasma enhanced chemical vapour deposition technique

    International Nuclear Information System (INIS)

    Highlights: • Carbon nitride films were prepared by using radio frequency plasma enhanced chemical vapour deposition system by altering the electrode distance. • The effect of electrode distance on surface morphology, surface roughness, chemical bonding and hydrophobic behaviour has been studied. • Hydrophobic behaviour were studied by measuring contact angle and calculating surface energy. • CNx nanostructures show super-hydrophobic behaviour. • We report a tunable transition of hydrophilic to super-hydrophobic behaviour of film as electrode distance is reduced. - Abstract: Tuning the wettability of various coating materials by simply controlling the deposition parameters is essential for various specific applications. In this work, carbon nitride (CNx) films were deposited on silicon (1 1 1) substrates using radio-frequency plasma enhanced chemical vapour deposition employing parallel plate electrode configuration. Effects of varying the electrode distance (DE) on the films’ structure and bonding properties were investigated using Field emission scanning electron microscopy, Atomic force microscopy, Fourier transform infrared and X-ray photoemission spectroscopy. The wettability of the films was analyzed using water contact angle measurements. At high DE, the CNx films’ surface was smooth and uniform. This changed into fibrous nanostructures when DE was decreased. Surface roughness of the films increased with this morphological transformation. Nitrogen incorporation increased with decrease in DE which manifested the increase in both relative intensities of C=N to C=C and N−H to O−H bonds. sp2-C to sp3-C ratio increased as DE decreased due to greater deformation of sp2 bonded carbon at lower DE. The films’ characteristics changed from hydrophilic to super-hydrophobic with the decrease in DE. Roughness ratio, surface porosity and surface energy calculated from contact angle measurements were strongly dependent on the morphology, surface

  14. 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.

  15. 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)

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

    International Nuclear Information System (INIS)

    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)

  17. 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.

  18. 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.

  19. SHG spectroscopy of gallium nitride thin films on sapphire with ultrashort pulses

    Science.gov (United States)

    Angerer, William Edward

    We present results of ultrafast second-harmonic generation spectroscopy of GaN/Alsb2Osb3 samples. We develop a formalism to calculate the nonlinear response of thin nonlinear films excited by an ultrashort laser source (Ti:Alsb2Osb3), and we use this formalism to extract chisbsp{zxx}{(2)}(omega=2omegasb{o}) and chisbsp{xzx}{(2)}(omega=2omegasb{o}) from our SHG measurements over a two photon energy range of 2.6-3.4 eV. By comparing spectra from several samples, we find a weak sub-band gap enhancement of chisbsp{zxx}{(2)}(omega=2omegasb{o}) at a two photon energy of 2.80 eV that is not present in chisbsp{xzx}{(2)}(omega=2omegasb{o}). This enhancement is independent of the carrier concentration, intentional doping, and presence of the "yellow luminescence band" defects. This feature may result from a three photon process involving a midgap defect state. We analyze three photon processes that include a defect state with group theory and demonstrate that several processes contribute to chisbsp{zxx}{(2)}(omega=2omegasb{o}) but not to chisbsp{xzx}{(2)}(omega=2omegasb{o}). In addition, we determined sample orientational miscuts by rotational SHG, and we found that these miscuts do not generate strain induced interface states. We determined a Sellmeier dispersion relationship for the index of refraction of GaN by a novel light transmission method, and we report on photoluminescence of our GaN/Alsb2Osb3 samples. In a second project we have designed and built a nonlinear optical microscope. We have used the new tool to perform preliminary investigations of the nonlinear optical properties of carbon nanoropes. We suggest that nonlinear optical microscopy is a potentially useful technique for analyzing carbon nanotube symmetry, as well as in studies of other heterogeneities. Finally, we place an upper limit on the dominant second order hyperpolarizability, alphasbsp{zzz}{(2)}, of carbon nanotubes based on our nonlinear optical microscopy measurements.

  20. Diamond and diamondlike carbon as wear-resistant, self-lubricating coatings for silicon nitride

    Science.gov (United States)

    Miyoshi, Kazuhisa

    1995-01-01

    Recent work on the friction and wear properties of as-deposited fine-grain diamond, polished coarse-grain diamond, and as-deposited diamondlike carbon (DLC) films in humid air at a relative humidity of approximately 40 percent and in dry nitrogen is reviewed. Two types of chemical vapor deposition (CVD) processes are used to deposit diamond films on silicon nitride (Si3N4) substrates: microwave-plasma and hot-filament. Ion beams are used to deposit DLC films of Si3N4 substrates. The diamond and DLC films in sliding contact with hemispherical bare Si3N4 pins have low steady-state coefficients of friction (less than 0.2) and low wear rates (less than 10(exp -7) mm(exp 2)/N-m), and thus, can be used effectively as wear-resistant, self-lubricating coatings for Si3N4 in the aforementioned two environments.

  1. Magnetic graphitic carbon nitride anion exchanger for specific enrichment of phosphopeptides.

    Science.gov (United States)

    Zhu, Gang-Tian; He, Xiao-Mei; Chen, Xi; Hussain, Dilshad; Ding, Jun; Feng, Yu-Qi

    2016-03-11

    Anion-exchange chromatography (AEX) is one of the chromatography-based methods effectively being used for phosphopeptide enrichment. However, the development of AEX materials with high specificity toward phosphopeptides is still less explored as compared to immobilized metal affinity chromatography (IMAC) or metal oxide affinity chromatography (MOAC). In this work, magnetic graphitic carbon nitride (MCN) was successfully prepared and introduced as a promising AEX candidate for phosphopeptide enrichment. Due to the extremely abundant content of nitrogen with basic functionality on the surface, this material kept excellent retention for phosphopeptides at pH as low as 1.8. Benefiting from the large binding capacity at such low pH, MCN showed remarkable specificity to capture phosphopeptides from tryptic digests of standard protein mixtures as well as nonfat milk and human serum. In addition, MCN was also applied to selective enrichment of phosphopeptides from the tryptic digests of rat brain lysate and 2576 unique phosphopeptides were successfully identified.

  2. 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.

  3. Invisible Security Ink Based on Water-Soluble Graphitic Carbon Nitride Quantum Dots.

    Science.gov (United States)

    Song, Zhiping; Lin, Tianran; Lin, Lihua; Lin, Sen; Fu, Fengfu; Wang, Xinchen; Guo, Liangqia

    2016-02-18

    Stimuli-responsive photoluminescent (PL) materials have been widely used as fluorescent ink for data security applications. However, traditional fluorescent inks are limited in maintaining the secrecy of information because the inks are usually visible by naked eyes either under ambient light or UV-light illumination. Here, we introduced metal-free water-soluble graphitic carbon nitride quantum dots (g-CNQDs) as invisible security ink for information coding, encryption, and decryption. The information written by the g-CNQDs is invisible in ambient light and UV light, but it can be readable by a fluorescence microplate reader. Moreover, the information can be encrypted and decrypted by using oxalic acid and sodium bicarbonate as encryption reagent and decryption reagent, respectively. Our findings provide new opportunities for high-level information coding and protection by using water-soluble g-CNQDs as invisible security ink.

  4. 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.

  5. Moving Graphitic Carbon Nitride from Electrocatalysis and Photocatalysis to a Potential Electrode Material for Photoelectric Devices.

    Science.gov (United States)

    Xu, Jingsan; Antonietti, Markus; Shalom, Menny

    2016-09-20

    Carbon nitride (g-CN) has attracted significant interest in the last years as a robust, low-cost alternative to metal-based materials in different fields due to its low price, environmentally benign character, simple synthesis and tunable properties. In particular, g-CN demonstrates promising activity in energy-related applications such as photo and heterogeneous catalysis, batteries and electrolysis. However, while g-CN is already well-established as a photocatalyst, its utilization in (opto)electronic devices is still at an early stage. This Focus Review concentrates on the utilization of g-CN in solar and photoelectrochemical cells, electrolyzers and light emitting diode alongside the recap of new synthetic approaches. This review is expected to provide useful insights into the design and fabrication of g-CN based photoelectronic devices as well as g-CN working principles, including the main challenges toward its integration in optoelectronic devices.

  6. Copper Phthalocyanine-Functionalized Graphitic Carbon Nitride: A Hybrid Heterostructure toward Photoelectrochemical and Photocatalytic Degradation Applications.

    Science.gov (United States)

    Liu, Zhong-Guo; Wan, Jia-Yun; Yang, Ze; Wang, Shi-Quan; Wang, Hang-Xing

    2016-07-01

    In this work, alcian blue 8GX (AB), a copper(II) phthalocyanine derivative, was employed to functionalize graphitic carbon nitride (g-C3 N4 ) for the preparation of a highly efficient photocatalyst. The approach relies on a facile AB-assisted ethanol/water mixed-solvent exfoliation of bulk g-C3 N4 . The as-prepared g-C3 N4 /AB hybrid possesses significantly enhanced solution dispersibility and photoelectrochemical performance resulting from the synergistic effect between g-C3 N4 and AB, which involves the optimization of intimate interfacial contact, extension of light absorption range, and enhancement of charge-transfer efficiency. This synergy contributes enormously to the photocatalytic degradation of rhodamine 6G (R6G) under light irradiation.

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

    International Nuclear Information System (INIS)

    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

  8. Invisible Security Ink Based on Water-Soluble Graphitic Carbon Nitride Quantum Dots.

    Science.gov (United States)

    Song, Zhiping; Lin, Tianran; Lin, Lihua; Lin, Sen; Fu, Fengfu; Wang, Xinchen; Guo, Liangqia

    2016-02-18

    Stimuli-responsive photoluminescent (PL) materials have been widely used as fluorescent ink for data security applications. However, traditional fluorescent inks are limited in maintaining the secrecy of information because the inks are usually visible by naked eyes either under ambient light or UV-light illumination. Here, we introduced metal-free water-soluble graphitic carbon nitride quantum dots (g-CNQDs) as invisible security ink for information coding, encryption, and decryption. The information written by the g-CNQDs is invisible in ambient light and UV light, but it can be readable by a fluorescence microplate reader. Moreover, the information can be encrypted and decrypted by using oxalic acid and sodium bicarbonate as encryption reagent and decryption reagent, respectively. Our findings provide new opportunities for high-level information coding and protection by using water-soluble g-CNQDs as invisible security ink. PMID:26797811

  9. 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.

  10. Moving Graphitic Carbon Nitride from Electrocatalysis and Photocatalysis to a Potential Electrode Material for Photoelectric Devices.

    Science.gov (United States)

    Xu, Jingsan; Antonietti, Markus; Shalom, Menny

    2016-09-20

    Carbon nitride (g-CN) has attracted significant interest in the last years as a robust, low-cost alternative to metal-based materials in different fields due to its low price, environmentally benign character, simple synthesis and tunable properties. In particular, g-CN demonstrates promising activity in energy-related applications such as photo and heterogeneous catalysis, batteries and electrolysis. However, while g-CN is already well-established as a photocatalyst, its utilization in (opto)electronic devices is still at an early stage. This Focus Review concentrates on the utilization of g-CN in solar and photoelectrochemical cells, electrolyzers and light emitting diode alongside the recap of new synthetic approaches. This review is expected to provide useful insights into the design and fabrication of g-CN based photoelectronic devices as well as g-CN working principles, including the main challenges toward its integration in optoelectronic devices. PMID:27558641

  11. 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.

  12. 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.

  13. 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.

  14. 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. PMID:26629779

  15. 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.

  16. Electrochemiluminescence of graphitic carbon nitride and its application in ultrasensitive detection of lead(II) ions.

    Science.gov (United States)

    Zhang, Yan; Zhang, Lina; Kong, Qingkun; Ge, Shenguang; Yan, Mei; Yu, Jinghua

    2016-10-01

    Graphitic carbon nitride (g-C3N4) materials with a layered structure have unusual physicochemical properties. Herein it was shown that g-C3N4 quantum dots (QDs) obtained through a thermal-chemical etching route exhibited attractive upconversion and electrochemiluminescence (ECL) properties. After modification on nanoporous gold (NPG) with a sponge-like porous structure, g-C3N4 QDs were employed to fabricate an ECL sensor for the determination of Pb(2+) using target - dependent DNAzyme as the recognition unit. Moreover, magnetic reduced graphene oxide nanosheets (rGO) attached with Fe3O4 nanoparticles (rGO-Fe3O4) were obtained via a one-pot in situ reduction approach, and used as carriers of DNAzyme. To make full use of the unique magnetic property the prepared rGO-Fe3O4, a flow injection ECL detecting cell was designed using indium tin oxide (ITO) glass as working electrode. Due to the unique separation and enrichment properties of magnetic Fe3O4-rGO materials as well as wire-like conductivity of NPG, high sensitivity and selectivity for the determination of Pb(2+) in real water samples were achieved. This indicates that g-C3N4 has excellent anodic ECL performance in the presence of triethanolamine, and could be applied in real environmental samples analyses. Graphical Abstract Graphitic carbon nitride based electrochemiluminescence sensor for the sensitive monitor of lead(II) ions in real samples was constructed.

  17. Deposition and characterization of zirconium nitride (ZrN) thin films by reactive magnetron sputtering with linear gas ion source and bias voltage

    International Nuclear Information System (INIS)

    Zirconium nitride thin films have been prepared on stainless steel substrate (304L grade) by reactive cylindrical magnetron sputtering method with Gas Ion Source (GIS) and bias voltage using optimized coating parameters. The structure and surface morphologies of the ZrN films were characterized using X-ray diffraction, atomic microscopy and scanning electron microscopy. The adhesion property of ZrN thin film has been increased due to the GIS. The coating exhibits better adhesion strength up to 10 N whereas the ZrN thin film with bias voltage exhibits adhesion up to 500 mN

  18. Deposition and characterization of zirconium nitride (ZrN) thin films by reactive magnetron sputtering with linear gas ion source and bias voltage

    Energy Technology Data Exchange (ETDEWEB)

    Kavitha, A.; Kannan, R. [Department of Physics, University College of Engineering, Anna University, Dindugal-624622 (India); Subramanian, N. Sankara [Department of Physics, Thiagarajar College of Engineering, Madurai -625015, Tamilnadu (India); Loganathan, S. [Ion Plating, Titan Industries Ltd., Hosur - 635126, Tamilnadu (India)

    2014-04-24

    Zirconium nitride thin films have been prepared on stainless steel substrate (304L grade) by reactive cylindrical magnetron sputtering method with Gas Ion Source (GIS) and bias voltage using optimized coating parameters. The structure and surface morphologies of the ZrN films were characterized using X-ray diffraction, atomic microscopy and scanning electron microscopy. The adhesion property of ZrN thin film has been increased due to the GIS. The coating exhibits better adhesion strength up to 10 N whereas the ZrN thin film with bias voltage exhibits adhesion up to 500 mN.

  19. 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.

  20. 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.

  1. Nano-solenoid: helicoid carbon-boron nitride hetero-nanotube

    Science.gov (United States)

    Zhang, Zi-Yue; Miao, Chunyang; Guo, Wanlin

    2013-11-01

    As a fundamental element of a nanoscale passive circuit, a nano-inductor is proposed based on a hetero-nanotube consisting of a spiral carbon strip and a spiral boron nitride strip. It is shown by density functional theory associated with nonequilibrium Green function calculations that the nanotube exhibits attractive transport properties tunable by tube chirality, diameter, component proportion and connection manner between the two strips, with excellent `OFF' state performance and high current on the order of 10-100 μA. All the hetero-nanotubes show negative differential resistance. The transmission peaks of current are absolutely derived from the helicoid carbon strips or C-BN boundaries, giving rise to a spiral current analogous with an energized nano-solenoid. According to Ampere's Law, the energized nano-solenoid can generate a uniform and tremendous magnetic field of more than 1 tesla, closing to that generated by the main magnet of medical nuclear magnetic resonance. Moreover, the magnitude of magnetic field can be easily modulated by bias voltage, providing great promise for a nano-inductor to realize electromagnetic conversion at the nanoscale.As a fundamental element of a nanoscale passive circuit, a nano-inductor is proposed based on a hetero-nanotube consisting of a spiral carbon strip and a spiral boron nitride strip. It is shown by density functional theory associated with nonequilibrium Green function calculations that the nanotube exhibits attractive transport properties tunable by tube chirality, diameter, component proportion and connection manner between the two strips, with excellent `OFF' state performance and high current on the order of 10-100 μA. All the hetero-nanotubes show negative differential resistance. The transmission peaks of current are absolutely derived from the helicoid carbon strips or C-BN boundaries, giving rise to a spiral current analogous with an energized nano-solenoid. According to Ampere's Law, the energized nano

  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. 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. PMID:27287103

  4. 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.

  5. 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.

  6. Temporally and spatially resolved plasma spectroscopy in pulsed laser deposition of ultra-thin boron nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Glavin, Nicholas R., E-mail: nicholas.glavin.1@us.af.mil, E-mail: andrey.voevodin@us.af.mil [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433 (United States); School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Muratore, Christopher [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433 (United States); University of Dayton, Dayton, Ohio 45409 (United States); Jespersen, Michael L.; Hu, Jianjun [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433 (United States); University of Dayton Research Institute, Dayton, Ohio 45409 (United States); Fisher, Timothy S. [School of Mechanical Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Voevodin, Andrey A., E-mail: nicholas.glavin.1@us.af.mil, E-mail: andrey.voevodin@us.af.mil [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433 (United States)

    2015-04-28

    Physical vapor deposition (PVD) has recently been investigated as a viable, alternative growth technique for two-dimensional materials with multiple benefits over other vapor deposition synthesis methods. The high kinetic energies and chemical reactivities of the condensing species formed from PVD processes can facilitate growth over large areas and at reduced substrate temperatures. In this study, chemistry, kinetic energies, time of flight data, and spatial distributions within a PVD plasma plume ablated from a boron nitride (BN) target by a KrF laser at different pressures of nitrogen gas were investigated. Time resolved spectroscopy and wavelength specific imaging were used to identify and track atomic neutral and ionized species including B{sup +}, B*, N{sup +}, N*, and molecular species including N{sub 2}*, N{sub 2}{sup +}, and BN. Formation and decay of these species formed both from ablation of the target and from interactions with the background gas were investigated and provided insights into fundamental growth mechanisms of continuous, amorphous boron nitride thin films. The correlation of the plasma diagnostic results with film chemical composition and thickness uniformity studies helped to identify that a predominant mechanism for BN film formation is condensation surface recombination of boron ions and neutral atomic nitrogen species. These species arrive nearly simultaneously to the substrate location, and BN formation occurs microseconds before arrival of majority of N{sup +} ions generated by plume collisions with background molecular nitrogen. The energetic nature and extended dwelling time of incident N{sup +} ions at the substrate location was found to negatively impact resulting BN film stoichiometry and thickness. Growth of stoichiometric films was optimized at enriched concentrations of ionized boron and neutral atomic nitrogen in plasma near the condensation surface, providing few nanometer thick films with 1:1 BN stoichiometry and good

  7. 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.

  8. 非晶碳氮纳米尖端的微结构和发光机理%Microstructure and Photoluminescence Mechanism of Amorphous Carbon Nitride Nanotips

    Institute of Scientific and Technical Information of China (English)

    王必本; 谢焕玲; 陈玉安; 董国波

    2012-01-01

    利用等离子体增强热丝化学气相沉积系统,用CH4、H2和N2为反应气体,在Si衬底上制备了碳氮纳米尖端.用扫描电子显微镜和显微Raman光谱仪对其进行了表征.在室温下测试了它的发光性能,发光谱由中心约为406 nm和506 nm的两条发光带组成.根据Raman散射谱,对其微结构进行了分析.结合非晶碳氮薄膜的结构和发光机理,分析了它的发光性能.%Carbon nitride nanotips were prepared on silicon substrate in plasma-enhanced hot fila ment chemical vapor deposition system, in which methane, hydrogen and nitrogen were used as the reaction gases. The carbon nitride nanotips were characterized by scanning electron microscopy and micro-Raman spectroscopy. The photoluminescence of the carbon nitride nanotips was measured at room temperature and the photoluminescence spectrum shows two emission bands at 406 and 506 nm. Combined with the Raman spectrum, the microstructure of the carbon nitride was analyzed. Ac cording to the structure and photoluminescence mechanism of amorphous carbon nitride films, the photoluminescence of carbon nitride nanotips was studied.

  9. Carbon-Dot-Decorated Carbon Nitride Nanoparticles for Enhanced Photodynamic Therapy against Hypoxic Tumor via Water Splitting.

    Science.gov (United States)

    Zheng, Di-Wei; Li, Bin; Li, Chu-Xin; Fan, Jin-Xuan; Lei, Qi; Li, Cao; Xu, Zushun; Zhang, Xian-Zheng

    2016-09-27

    Hypoxia, a typical feature of solid tumors, remarkably restricts the efficiency of photodynamic therapy (PDT). Here, a carbon nitride (C3N4)-based multifunctional nanocomposite (PCCN) for light-driven water splitting was used to solve this problem. Carbon dots were first doped with C3N4 to enhance its red region absorption because red light could be used to trigger the in vivo water splitting process. Then, a polymer containing a protoporphyrin photosensitizer, a polyethylene glycol segment, and a targeting Arg-Gly-Asp motif was synthesized and introduced to carbon-dot-doped C3N4 nanoparticles. In vitro study showed that PCCN, thus obtained, could increase the intracellular O2 concentration and improve the reactive oxygen species generation in both hypoxic and normoxic environments upon light irradiation. Cell viability assay demonstrated that PCCN fully reversed the hypoxia-triggered PDT resistance, presenting a satisfactory growth inhibition of cancer cells in an O2 concentration of 1%. In vivo experiments also indicated that PCCN had superior ability to overcome tumor hypoxia. The use of water splitting materials exhibited great potential to improve the intratumoral oxygen level and ultimately reverse the hypoxia-triggered PDT resistance and tumor metastasis.

  10. 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.

  11. Carbon- and crack-free growth of hexagonal boron nitride nanosheets and their uncommon stacking order.

    Science.gov (United States)

    Khan, Majharul Haque; Casillas, Gilberto; Mitchell, David R G; Liu, Hua Kun; Jiang, Lei; Huang, Zhenguo

    2016-09-21

    The quality of hexagonal boron nitride nanosheets (h-BNNS) is often associated with the most visible aspects such as lateral size and thickness. Less obvious factors such as sheet stacking order could also have a dramatic impact on the properties of BNNS and therefore its applications. The stacking order can be affected by contamination, cracks, and growth temperatures. In view of the significance of chemical-vapour-decomposition (CVD) assisted growth of BNNS, this paper reports on strategies to grow carbon- and crack-free BNNS by CVD and describes the stacking order of the resultant BNNS. Pretreatment of the most commonly used precursor, ammonia borane, is necessary to remove carbon contamination caused by residual hydrocarbons. Flattening the Cu and W substrates prior to growth and slow cooling around the Cu melting point effectively facilitate the uniform growth of h-BNNS, as a result of a minimal temperature gradient across the Cu substrate. Confining the growth inside alumina boats effectively minimizes etching of the nanosheet by silica nanoparticles originating from the commonly used quartz reactor tube. h-BNNS grown on solid Cu surfaces using this method adopt AB, ABA, AC', and AC'B stacking orders, which are known to have higher energies than the most stable AA' configuration. These findings identify a pathway for the fabrication of high-quality h-BNNS via CVD and should spur studies on stacking order-dependent properties of h-BNNS.

  12. 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.

  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. Effect of the nanoscratch resistance of indium nitride thin films in the etching duration

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Wen-Nong, E-mail: nong88@yam.com [Department of Mechanical Engineering, National Central University, Chung-Li, Taiwan (China); Department of Vehicle Engineering, Army Academy, Chung-Li, Taiwan (China); Shih, Teng-Shih [Department of Mechanical Engineering, National Central University, Chung-Li, Taiwan (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer We evaluated the tribological properties of InN films/AlN buffer/Si. Black-Right-Pointing-Pointer The measured values of friction upon increasing the etching duration. Black-Right-Pointing-Pointer Low In-N density of InN films at longer etching duration to decay resistance and plastic deformation. - Abstract: This study present the nanotribological behavior of single-crystalline indium nitride (InN) films onto aluminum nitride (AlN) buffer layers on Si(1 1 1) substrates. The surface morphology and friction ({mu}) were analyzed using atomic force microscopy and nanoscratch system. It is confirmed that the normal force (F{sub n}) measured values of {mu} of the InN films, from 10 to 60 min of etching duration, were in the range from 0.2 to 0.43 for F{sub n} = 2000 {mu}N; 0.25 to 0.58 for F{sub n} = 6000 {mu}N, respectively. It is suggested that the measured values of {mu} is slightly increased based on the etching duration due to the etching effect on the grain boundary and reduce film quality of InN films. From morphological observations, we compared the sliding resistance against contact-induced damage of the InN films in the presented ploughed of the area. It is confirmed that the contact sliding line is observable due to the increased F{sub n}, the following investigation with friction curve and lateral force is studied.

  15. Unique Static Magnetic and Dynamic Electromagnetic Behaviors in Titanium Nitride/Carbon Composites Driven by Defect Engineering

    OpenAIRE

    Chunhong Gong; Hongjie Meng; Xiaowei Zhao; Xuefeng Zhang; Laigui Yu; Jingwei Zhang; Zhijun Zhang

    2016-01-01

    Recently, the defect-induced static magnetic behaviours of nanomaterials have been a cutting-edge issue in diluted magnetic semiconductor materials. However, the dynamic magnetic properties of nanomaterials are commonly ignored if their bulk counterparts are non-magnetic. In the present research, titanium nitride-carbon (TiN/C) nanocomposites were found to exhibit both static and dynamic magnetic properties that vary in the opposite trend. Moreover, novel unconventional electromagnetic resona...

  16. 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).

  17. Nickel-supported carbon nitride photocatalyst combined with organic dye for visible-light-driven hydrogen evolution from water.

    Science.gov (United States)

    Mori, Kohsuke; Itoh, Taiki; Kakudo, Hiroki; Iwamoto, Tomoyuki; Masui, Yoichi; Onaka, Makoto; Yamashita, Hiromi

    2015-10-01

    A noble-metal-free photocatalytic H2 production system consisting of a Ni-based catalyst, visible-light-responsive organic dye, and graphitic carbon nitride (g-C3N4) as a support has been developed. Characterization by means of XAFS revealed that the deposition of a trinuclear Ni precursor complex, Ni(NiL2)2Cl2 (L = β-mercaptoethylamine), on the g-C3N4 affords a monomeric Ni(ii) species involving β-mercaptoethylamine and aqua ligands in an octahedral coordination geometry. Such a Ni species acts as a hydrogen production site from an aqueous solution without an electron relay reagent by combining with thiazole orange (TO) as a photosensitizer. The emission of the attached TO at around 550 nm decreases with increasing loading amount of Ni catalyst, suggesting electron transfer from TO to the Ni catalyst via the g-C3N4 support. Leaching and agglomeration of the active Ni catalyst and TO are not observed during the photocatalytic reaction. Moreover, the use of highly porous carbon nitride (nanoporous carbon nitride; nanoC3N4) is proven to significantly enhance the photocatalytic activity because of the high surface area due to the unique porous structure as well as high absorption and emission properties of TO associated with nanoC3N4.

  18. Iron-Doped Carbon Nitride-Type Polymers as Homogeneous Organocatalysts for Visible Light-Driven Hydrogen Evolution.

    Science.gov (United States)

    Gao, Lin-Feng; Wen, Ting; Xu, Jing-Yin; Zhai, Xin-Ping; Zhao, Min; Hu, Guo-Wen; Chen, Peng; Wang, Qiang; Zhang, Hao-Li

    2016-01-13

    Graphitic carbon nitrides have appeared as a new type of photocatalyst for water splitting, but their broader and more practical applications are oftentimes hindered by the insolubility or difficult dispersion of the material in solvents. We herein prepared novel two-dimensional (2D) carbon nitride-type polymers doped by iron under a mild one-pot method through preorganizing formamide and citric acid precursors into supramolecular structures, which eventually polycondensed into a homogeneous organocatalyst for highly efficient visible light-driven hydrogen evolution with a rate of ∼16.2 mmol g(-1) h(-1) and a quantum efficiency of 0.8%. Laser photolysis and electrochemical impedance spectroscopic measurements suggested that iron-doping enabled strong electron coupling between the metal and the carbon nitride and formed unique electronic structures favoring electron mobilization along the 2D nanomaterial plane, which might facilitate the electron transfer process in the photocatalytic system and lead to efficient H2 evolution. In combination with electrochemical measurements, the electron transfer dynamics during water reduction were depicted, and the earth-abundant Fe-based catalyst may open a sustainable strategy for conversion of sunlight into hydrogen energy and cope with current challenging energy issues worldwide.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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, ...

  4. SURFACE PHONON AND CONFINED PHONON POLARITONS IN WURTIZTE NITRIDE THIN-FILM STRUCTURES

    OpenAIRE

    L. ZHANG

    2008-01-01

    The polar phonon polariton modes in a wurtzite thin-film structure have been theoretically investigated in the present paper. It has been confirmed that there are two types of phonon polariton modes, i.e., the surface phonon polariton (SPP) modes and the confined phonon polariton (CPP) modes in wurtzite thin-film systems. The frequency ranges of the SPP and CPP modes have been discussed in detail. The dispersive equations for the two types of polarition modes are also deduced. Numerical calcu...

  5. 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.

  6. Ultra-thin superconducting film coated silicon nitride nanowire resonators for low-temperature applications

    Science.gov (United States)

    Sebastian, Abhilash; Zhelev, Nikolay; de Alba, Roberto; Parpia, Jeevak

    We demonstrate fabrication of high stress silicon nitride nanowire resonators with a thickness and width of less than 50 nm intended to be used as probes for the study of superfluid 3He. The resonators are fabricated as doubly-clamped wires/beams using a combination of electron-beam lithography and wet/dry etching techniques. We demonstrate the ability to suspend (over a trench of depth ~8 µm) wires with a cross section as small as 30 nm, covered with a 20 nm superconducting film, and having lengths up to 50 µm. Room temperature resonance measurements were carried out by driving the devices using a piezo stage and detecting the motion using an optical interferometer. The results show that metalizing nano-mechanical resonators not only affects their resonant frequencies but significantly reduce their quality factor (Q). The devices are parametrically pumped by modulating the system at twice its fundamental resonant frequency, which results in observed amplification of the signal. The wires show self-oscillation with increasing modulation strength. The fabricated nanowire resonators are intended to be immersed in the superfluid 3He. By tracking the resonant frequency and the Q of the various modes of the wire versus temperature, we aim to probe the superfluid gap structure.

  7. 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.

  8. Correlation between stress profiles of cubic boron nitride thin films and the phase sequence revealed from infrared data

    Science.gov (United States)

    Klett, A.; Malavé, A.; Freudenstein, R.; Plass, M. F.; Kulisch, W.

    Cubic boron nitride thin films have been ion-beam-assisted deposited on silicon cantilever structures and subsequently back-etched in order to study the stress evolution and finally the growth mechanisms. After each sputtering step, the film stress, the remaining thickness, and the IR data were examined. In this way, the layered sequence of cBN on top of a hBN base layer, influencing the development of the intrinsic film stress, could be studied in detail. The observed stress distribution can be divided into three regions. First, a non-cubic base layer with a constant stress value is formed, followed by a linear increase in the stress after cBN nucleation as a result of the coalescence of cBN nanocrystals. Finally, the stress reaches a second plateau characteristic of the cBN top layer. In addition, the layered sequence was verified by the evolution of the FTIR spectra. Furthermore, the fraction of the sp2-bonded material of the cBN top layer was determined from the IR data. For various deposition conditions, a linear relationship between the stress of the nanocrystalline cBN top layer and the amount of sp3-bonded material was observed. From this, it can be concluded that stress relaxation occurs at the sp2-bonded grain boundary material. No evidence for stress relaxation after cBN nucleation was found.

  9. Correlation between stress profiles of cubic boron nitride thin films and the phase sequence revealed from infrared data

    Energy Technology Data Exchange (ETDEWEB)

    Klett, A.; Malave, A.; Freudenstein, R.; Plass, M.F.; Kulisch, W. [Kassel Univ. (Gesamthochschule) (Germany). Inst. fuer Technische Physik

    1999-12-01

    Cubic boron nitride thin films have been ion-beam-assisted deposited on silicon cantilever structures and subsequently back-etched in order to study the stress evolution and finally the growth mechanisms. After each sputtering step, the film stress, the remaining thickness, and the IR data were examined. In this way, the layered sequence of cBN on top of a hBN base layer, influencing the development of the intrinsic film stress, could be studied in detail. The observed stress distribution can be divided into three regions. First, a non-cubic base layer with a constant stress value is formed, followed by a linear increase in the stress after cBN nucleation as a result of the coalescence of cBN nanocrystals. Finally, the stress reaches a second plateau characteristic of the cBN top layer. In addition, the layered sequence was verified by the evolution of the FTIR spectra. Furthermore, the fraction of the sp{sup 2}-bonded material of the cBN top layer was determined from the IR data. For various deposition conditions, a linear relationship between the stress of the nanocrystalline cBN top layer and the amount of sp{sup 3}-bonded material was observed. From this, it can be concluded that stress relaxation occurs at the sp{sup 2}-bonded grain boundary material. No evidence for stress relaxation after cBN nucleation was found. (orig.)

  10. Low-temperature (≤200 °C) plasma enhanced atomic layer deposition of dense titanium nitride thin films

    International Nuclear Information System (INIS)

    Titanium nitride (TiN) has been widely used in the semiconductor industry for its diffusion barrier and seed layer properties. However, it has seen limited adoption in other industries in which low temperature (2) as co-reactant. This process was developed in a Veeco NEXUS™ chemical vapor deposition tool. The tool uses a substrate rf-biased configuration with a grounded gas shower head. In this paper, the complimentary and self-limiting character of this process is demonstrated. The effects of key processing parameters including temperature, pulse time, and plasma power are investigated in terms of growth rate, stress, crystal morphology, chemical, electrical, and optical properties. Stoichiometric thin films with growth rates of 0.4–0.5 Å/cycle were achieved. Low electrical resistivity (4 g/cm3), low stress (85% step coverage for aspect ratio of 10:1 were realized. Wet chemical etch data show robust chemical stability of the film. The properties of the film have been optimized to satisfy industrial viability as a Ruthenium (Ru) preseed liner in potential data storage and TSV applications.

  11. Synthesis and high temperature XRD studies of tantalum nitride thin films prepared by reactive pulsed dc magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Elangovan, T. [Thin Film and Nanomaterials Laboratory, Department of Physics, Bharathiar University, Coimbatore-641 046 (India); Murugeshan, S. [Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603 102 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.com [Department of Nanoscience and Technology, Bharathiar University, Coimbatore-641 046 (India); Kuppusami, P.; Khan, Shabhana; Sudha, C. [Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603 102 (India); Ganesan, V. [UGC-DAE CSR, Indore-452 017 (India); Divakar, R.; Mohandas, E. [Physical Metallurgy Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603 102 (India)

    2011-06-02

    In the present work, the growth characteristics of tantalum nitride (TaN) thin films prepared on (1 0 0) Si substrates by reactive pulsed DC magnetron sputtering are investigated. XRD analyses indicated the presence of {alpha}-Ta and {beta}-Ta in the films deposited in pure argon atmosphere, while {beta}-TaN and fcc-TaN phases appeared for 2 sccm of nitrogen, and cubic TaN for 5-25 sccm of nitrogen in the sputtering gas mixture of argon and nitrogen at a substrate temperature of 773 K. The TaN films obtained with increasing substrate temperature and pulse width showed a change in the texture from [1 1 1] to [2 0 0] orientation. Atomic force microscopy (AFM) results indicated that the average surface roughness was low for films deposited in pure argon than for the films deposited in a mixed Ar + N{sub 2} atmosphere. Nanocrystalline phase of the deposited material was identified from the high-resolution transmission electron microscopy (HRTEM) images. X-ray photoelectron spectroscopy (XPS) core level spectra confirmed the formation of TaN phase. The high temperature X-ray diffraction analysis of the optimized TaN thin film was performed in the temperature range 298-1473 K. The lattice parameter of the TaN films was found to increase from 4.383 to 4.393 A on increasing the temperature from 298 to 823 K and it reduced to 4.345 A at 1473 K. The thermal expansion coefficient value was found to be negative for the TaN films.

  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. Detection of Ag(+) using graphite carbon nitride nanosheets based on fluorescence quenching.

    Science.gov (United States)

    Bian, Wei; Zhang, Hao; Yu, Qing; Shi, Meijuan; Shuang, Shaomin; Cai, Zongwei; Choi, Martin M F

    2016-12-01

    The graphite carbon nitride (g-C3N4) nanosheets were synthesized and applied for the detection of Ag(+) ion in aqueous solutions. Transmission electron microscopy, Fourier infrared spectroscopy, x-ray diffraction, ultraviolet/visible and photoluminescence spectroscopy were used for characterization of g-C3N4 nanosheets. The fluorescence intensity of g-C3N4 nanosheets decreases with the increase in the concentration of Ag(+). The fluorescence probe can be applied for detection of Ag(+). The results show that it has high selectivity to Ag(+) and exhibits a good linearity over the concentration range 0.020-2.0μM with a detection limit of 27nM. Most cations do not have any interference on the detection of Ag(+). The quenching process is assessed and discussed. Finally, the g-C3N4 nanosheets have been successfully used for the detection of Ag(+) in real water samples. The recoveries of spiked water samples are >97%. PMID:27348047

  14. Graphitic carbon nitride/BiOCl composites for sensitive photoelectrochemical detection of ciprofloxacin.

    Science.gov (United States)

    Xu, Li; Li, Henan; Yan, Pengcheng; Xia, Jiexiang; Qiu, Jingxia; Xu, Qian; Zhang, Shanqing; Li, Huaming; Yuan, Shouqi

    2016-12-01

    Ciprofloxacin, as a second generation of fluoroquinolone antibiotics, has been proved to cause environmental harm and exhibits toxic effects on the wastewater and surface water even at low concentrations due to their continuous input and persistence. Despite tremendous efforts, developing ciprofloxacin detection method with accuracy and sensitivity at low-cost remains a great challenge. Herein, graphitic carbon nitride/BiOCl composite (g-CN/BiOCl) has been designed for a facile and sensitive photoelectrochemical (PEC) monitoring platform of ciprofloxacin at first time. BiOCl can be modified with the g-CN nanosheets which are obtained via solvothermal process at low-temperature conditions. The use of g-CN is shown to strongly enhance the PEC response of BiOCl due to the formation of heterojunctions. The photocurrent generated at the g-CN/BiOCl-modified ITO (with 13wt%g-CN content) is much higher and more stable than that of a BiOCl-modified ITO. Based on these findings, the g-CN/BiOCl-modified ITO was used to design a PEC assay for the antibiotic ciprofloxacin. Furthermore, the limit of detection of the ciprofloxacin PEC sensor has been significantly lowered to 0.2ngmL(-1). In addition, the PEC sensor can detect ciprofloxacin in the wide range of 0.5-1840ngmL(-1).

  15. Theoretical investigation of methane adsorption onto boron nitride and carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Masoud Darvish Ganji, Amir Mirnejad and Ali Najafi

    2010-01-01

    Full Text Available Methane adsorption onto single-wall boron nitride nanotubes (BNNTs and carbon nanotubes (CNTs was studied using the density functional theory within the generalized gradient approximation. The structural optimization of several bonding configurations for a CH4 molecule approaching the outer surface of the (8,0 BNNT and (8,0 CNT shows that the CH4 molecule is preferentially adsorbed onto the CNT with a binding energy of −2.84 kcal mol−1. A comparative study of nanotubes with different diameters (curvatures reveals that the methane adsorptive capability for the exterior surface increases for wider CNTs and decreases for wider BNNTs. The introduction of defects in the BNNT significantly enhances methane adsorption. We also examined the possibility of binding a bilayer or a single layer of methane molecules and found that methane molecules preferentially adsorb as a single layer onto either BNNTs or CNTs. However, bilayer adsorption is feasible for CNTs and defective BNNTs and requires binding energies of −3.00 and −1.44 kcal mol−1 per adsorbed CH4 molecule, respectively. Our first-principles findings indicate that BNNTs might be an unsuitable material for natural gas storage.

  16. Graphitic carbon nitride as high-resolution stationary phase for gas chromatographic separations.

    Science.gov (United States)

    Zheng, Yunzhong; Qi, Meiling; Fu, Ruonong

    2016-07-01

    This work presents the first example of utilization of graphitic carbon nitride (g-C3N4) as stationary phase for capillary gas chromatographic (GC) separations. The statically coated g-C3N4 column showed the column efficiencies of 3760 plates/m and weak polarity. Its resolving capability and retention behaviours were investigated by using the Grob test mixture, and mixtures of diverse types of analytes, and structural and positional isomers. The results showed superior separation performance of the g-C3N4 stationary phase for some critical analytes and preferential retention for aromatic analytes. Specifically, it exhibited high-resolution capability for aromatic and aliphatic isomers such as methylnaphthalenes and dimethylnaphthalenes, phenanthrene and anthracene and alkane isomers. In addition, g-C3N4 column showed excellent thermal stability up to 280°C and good repeatability with relative standard deviation (RSD) values less than 0.09% for intra-day, below 0.23% for inter-day and in the range of 1.9-8.4% for between-column, respectively. The advantageous separation performance shows the potential of g-C3N4 and related materials as stationary phase in GC and other separation technologies.

  17. Ultrafine Cobalt Catalysts on Covalent Carbon Nitride Frameworks for Oxygenic Photosynthesis.

    Science.gov (United States)

    Zhang, Guigang; Zang, Shaohong; Lin, Lihua; Lan, Zhi-An; Li, Guosheng; Wang, Xinchen

    2016-01-27

    The rational cooperation of sustainable catalysts with suitable light-harvesting semiconductors to fabricate photosynthetic device/machinery has been regarded as an ideal technique to alleviate the current worldwide energy and environmental issues. Cobalt based species (e.g., Co-Pi, Co3O4, and Co-cubene) have attracted particular attentions because they are earth-abundant, cost-acceptable, and more importantly, it shows comparable water oxidation activities to the noble metal based catalysts (e.g., RuO2, IrO2). In this contribution, we compared two general cocatalysts modification strategies, based on the surface depositing and bulk doping of ultrafine cobalt species into the sustainable graphitic carbon nitride (g-C3N4) polymer networks for oxygenic photosynthesis by splitting water into oxygen, electrons, and protons. The chemical backbone of g-C3N4 does not alter after both engineering modifications; however, in comparison with the bulk doping, the optical and electronic properties of the surface depositing samples are efficiently promoted, and the photocatalytic water oxidation activities are increased owing to much more exposed active sites, reduced overpotential for oxygen evolution and the accelerated interface charge mobility. This paper underlines the advantage of surface engineering to establish efficient advanced polymeric composites for water oxidation, and it opens new insights into the architectural design of binary hybrid photocatalysts with high reactivity and further utilizations in the fields of energy and environment.

  18. Carbon nitride nanosheet-supported porphyrin: a new biomimetic catalyst for highly efficient bioanalysis.

    Science.gov (United States)

    Deng, Shengyuan; Yuan, Peixin; Ji, Xubo; Shan, Dan; Zhang, Xueji

    2015-01-14

    A highly efficient biomimetic catalyst was fabricated based on ultrathin carbon nitride nanosheets (C3N4)-supported cobalt(II) proto-porphyrin IX (CoPPIX). The periodical pyridinic nitrogen units in C3N4 backbone could serve as electron donors for great affinity with Co(2+) in PPIX, which resembled the local electronic structure as vitamin B12 and heme cofactor of hemoglobin. UV-vis kinetics and electrochemistry revealed its competitive (electro)catalysis with conventional peroxidase, while X-ray photoelectron spectroscopy and theoretical calculations suggest that the rehybridization of Co 3d with N orbitals from the backside can result in significant changes in enthalpy and charge density, which greatly promoted the activity of CoPPIX. The prepared nanocatalyst was further conjugated with streptavidin via multiple amines on the edge plane of C3N4 for facile tagging. Using biotinylated molecular beacon as the capture probe, a sensitive electrochemiluminescence-based DNA assay was developed via the electroreduction of H2O2 as the coreactant after the hairpin unfolded by the target, exhibiting linearity from 1.0 fM to 0.1 nM and a detection limit of 0.37 fM. Our results demonstrate a new paradigm to rationally design inexpensive and durable biomimics for electrochemiluminescence quenching strategy, showing great promise in bioanalytical applications.

  19. Comparison Study of the Photoelectrochemical Activity of Carbon Nitride with Different Photoelectrode Configurations.

    Science.gov (United States)

    Lou, Shuang; Zhou, Zhixin; Shen, Yanfei; Zhan, Zongsheng; Wang, Jianhai; Liu, Songqin; Zhang, Yuanjian

    2016-08-31

    Polymeric carbon nitride (CN) has recently emerged as a novel metal-free semiconductor due to its unique electronic structure, wide availability, and promising applications in photoelectrochemical solar energy conversion. However, few works regarding CN photoelectrode optimization such as by minimization of unwanted grain boundary effects have been reported, which would greatly influence the photoelectrochemcial conversion efficiency. Herein, three general ways of preparing CN photoelectrode are presented and compared, including drop-casting of CN particles, or further blendeding with Nafion or PEDOT-PSS as the binder. In addition, the influences of CN particle sizes (0.5, 1.1, and 3.2 μm) and the film thickness (i.e., the loading amount) to the overall photoelectrochemcial activity were also evaluated in detail. As a result, when PEDOT-PSS acted as binder, CN particles with size of 0.5 μm and an optimal loading amount (2.4 mg/cm(2)) were adopted; the as-prepared CN photoelectrode had much superior photoelectrochemical activity than all other counterparts. Therefore, this study would pave the way for preparing CN photoelectrode of superior quality so as to promote CN materials to be better applied in solar fuel and sensing applications.

  20. A graphitic carbon nitride based fluorescence resonance energy transfer detection of riboflavin.

    Science.gov (United States)

    Han, Jing; Zou, Hong Yan; Gao, Ming Xuan; Huang, Cheng Zhi

    2016-01-01

    Fluorescence resonance energy transfer (FRET), which occurs between two luminescent chromophores, can greatly improve the selectivity and sensitivity of a fluorescent assay when a ratiometric signaling with the fluorescence enhancement of the acceptor at the expense of the donor is adopted. In this study, a fluorescence ratiometric detection (FRD) of riboflavin (RF) has been made based on FRET, as the strong overlap occurred between the emission spectrum of graphitic carbon nitride (g-C3N4) and absorption spectrum of RF, in which g-C3N4 acts as the energy donor and RF as the energy acceptor. With increasing concentration of RF, the fluorescence intensity of g-C3N4 emission at 444 nm decreased and the fluorescence peak at 523 nm for RF increased regularly, making the fluorescence intensity ratio of 523 nm to 444 nm linearly dependent on the concentration of RF in the range from 0.4 μM to 10 μM, giving a limit of the detection of 170 nM. This method can be used to quantify RF in complex systems such as milk and drink, showing that the novel FRET-based fluorescence ratiometric detection can enable an attractive assay platform for analytes of interest.

  1. The investigation of carbon nitride films prepared at various arc currents by vacuum cathode arc method

    International Nuclear Information System (INIS)

    The carbon nitride films have been prepared in the arc currents range of 20-60 A at the Ar/N2 atmosphere of 50/400 sccm by the vacuum cathode arc deposition method. The properties of the films were characterized by x-ray photoelectron spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and nanoindentation. The N concentration showed a maximum of 35 at% at 20 A and decreased gradually with the arc currents. The films below 40 A consisted of linear polymeric-like component and sp2 graphitic cluster. With the increasing of the arc current from 20 to 40 A, the ID/IG rose and the photoluminescence (PL) fell gradually, which resulted from the development of the sp2 graphitic phase and the decrease of the polymeric-like phase. As a result, the CC bonds increased and sp3CN and sp2CN decreased. Above 40 A, with the increasing of arc currents, ID/IG fell and the PL increased gradually, which reflected the decreasing of sp2 graphitic phase and the modification of C and N atoms in sp2 cluster. The CC bonds and sp3CN fell and the sp2CN rose. The nanohardness of films showed increasing tendency with the arc currents. The variation of the relative ratio and the average energy of N-containing species and C-containing species at the atmosphere would be responsible for the change in the properties of films. (author)

  2. 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

    2016-11-01

    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. PMID:27239724

  3. 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

    2016-03-01

    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 (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.

  4. 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.

  5. Graphitic carbon nitride nanosheet-based multicolour fluorescent nanoprobe for multiplexed analysis of DNA

    International Nuclear Information System (INIS)

    We demonstrate that nanosheets composed of graphitic carbon nitride (g-C3N4) can serve as a low-cost and efficient fluorescent nanoprobe for the multiplexed detection of DNA in solution. The strategy is based on the finding that g-C3N4 is capable of binding dye-labeled single-stranded DNA (ssDNA) which results in quenching of the fluorescence of the dye. If target DNA hybridizes with dye-labeled ssDNA, the interaction between dye-labeled ssDNA and g-C3N4 is weakened, and this results in desorption of the dsDNA from the surface of the g-C3N4 and in recovery of fluorescence. The large surface area of g-C3N4 nanosheets allows for simultaneous quenching of multicolor DNA probes labeled with different dyes, leading to the development of multiplexed DNA sensors for the detection of multiple DNA targets in a single solution. By using one 15-mer DNA fragment and one 18-mer DNA fragment as proof-of-principle analytes, the method displayed good analytical performance. The limits of detection are 75 and 62 pM, respectively. The method is simple and sensitive, and was used to detect DNA in serum samples. We perceive that this method represents a new approach towards multiplexed assays for applications in DNA monitoring, clinical diagnosis, and in the detection of genetic disorders. (author)

  6. Polymerization of cyanoacetylene under pressure: Formation of carbon nitride polymers and bulk structures

    Science.gov (United States)

    Khazaei, Mohammad; Liang, Yunye; Venkataramanan, Natarajan S.; Kawazoe, Yoshiyuki

    2012-02-01

    High-pressure phase transitions of polar and nonpolar molecular structures of cyanoacetylene (HC3N) are studied by using first-principles simulations at constant pressure. In both polar and nonpolar crystals, at pressure ˜20 GPa, the cyanoacetylene molecules are interconnected together and form polyacrylonitrile (PA) polymers. At pressure ˜30 GPa, PA polymers are transformed to polymers with fused pyridine rings (FPR's). The individual geometrical structures of PA and FPR polymers obtained from polar and nonpolar molecular crystals of cyanoacetylene are identical, but their stacking is different. At pressures above 40 GPa, the FPR polymers are interconnected together and new three-dimensional (3D) carbon nitride systems are formed. At ambient pressure, the long-length PA and FPR polymers are metallic, and the created 3D structures are an insulator with energy band gaps around 2.85 eV. The electron transport characteristics of FPR polymers with different lengths are investigated at finite biases by using the nonequilibrium Green's function technique combined with density functional theory (DFT) by connecting the polymers to gold electrodes. The results show that FPR polymers have negative differential resistance behavior. Our time-dependent DFT calculations reveal that FPR polymers can absorb light in the visible region. From our results, it is expected that the FPR polymers will be a good material for optoelectronic applications.

  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. Graphitic carbon nitride/BiOCl composites for sensitive photoelectrochemical detection of ciprofloxacin.

    Science.gov (United States)

    Xu, Li; Li, Henan; Yan, Pengcheng; Xia, Jiexiang; Qiu, Jingxia; Xu, Qian; Zhang, Shanqing; Li, Huaming; Yuan, Shouqi

    2016-12-01

    Ciprofloxacin, as a second generation of fluoroquinolone antibiotics, has been proved to cause environmental harm and exhibits toxic effects on the wastewater and surface water even at low concentrations due to their continuous input and persistence. Despite tremendous efforts, developing ciprofloxacin detection method with accuracy and sensitivity at low-cost remains a great challenge. Herein, graphitic carbon nitride/BiOCl composite (g-CN/BiOCl) has been designed for a facile and sensitive photoelectrochemical (PEC) monitoring platform of ciprofloxacin at first time. BiOCl can be modified with the g-CN nanosheets which are obtained via solvothermal process at low-temperature conditions. The use of g-CN is shown to strongly enhance the PEC response of BiOCl due to the formation of heterojunctions. The photocurrent generated at the g-CN/BiOCl-modified ITO (with 13wt%g-CN content) is much higher and more stable than that of a BiOCl-modified ITO. Based on these findings, the g-CN/BiOCl-modified ITO was used to design a PEC assay for the antibiotic ciprofloxacin. Furthermore, the limit of detection of the ciprofloxacin PEC sensor has been significantly lowered to 0.2ngmL(-1). In addition, the PEC sensor can detect ciprofloxacin in the wide range of 0.5-1840ngmL(-1). PMID:27552431

  9. A graphitic carbon nitride based fluorescence resonance energy transfer detection of riboflavin.

    Science.gov (United States)

    Han, Jing; Zou, Hong Yan; Gao, Ming Xuan; Huang, Cheng Zhi

    2016-01-01

    Fluorescence resonance energy transfer (FRET), which occurs between two luminescent chromophores, can greatly improve the selectivity and sensitivity of a fluorescent assay when a ratiometric signaling with the fluorescence enhancement of the acceptor at the expense of the donor is adopted. In this study, a fluorescence ratiometric detection (FRD) of riboflavin (RF) has been made based on FRET, as the strong overlap occurred between the emission spectrum of graphitic carbon nitride (g-C3N4) and absorption spectrum of RF, in which g-C3N4 acts as the energy donor and RF as the energy acceptor. With increasing concentration of RF, the fluorescence intensity of g-C3N4 emission at 444 nm decreased and the fluorescence peak at 523 nm for RF increased regularly, making the fluorescence intensity ratio of 523 nm to 444 nm linearly dependent on the concentration of RF in the range from 0.4 μM to 10 μM, giving a limit of the detection of 170 nM. This method can be used to quantify RF in complex systems such as milk and drink, showing that the novel FRET-based fluorescence ratiometric detection can enable an attractive assay platform for analytes of interest. PMID:26653450

  10. Preparation of thin carbon films (1963)

    International Nuclear Information System (INIS)

    Carbon deposits have been prepared on silica glass supports in order to determine more accurately than by weighing the losses liable to occur during oxidation, for example under irradiation in the presence of CO2. Several processes have been studied with a view to obtaining deposits for which the variation in optical density as a function of carbon departure shall be reproducible for each sample. Among the methods used, the most satisfactory is that in which the pyrolytic carbon deposited on a carbon filament is evaporated; however only the samples prepared simultaneously exhibit the required identical behaviour. The carbonaceous deposits have been studied by micro-electronic diffraction. An examination of the photographs shows the presence of graphite monocrystals of about (30 μ)2. (author)

  11. 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

  12. Tungsten nitride nanorods array grown on carbon cloth as an efficient hydrogen evolution cathode at all pH values

    International Nuclear Information System (INIS)

    It is highly desired but still remains a challenging task to develop efficient non-noble-metal hydrogen evolution reaction (HER) electrocatalysts operating efficiently under all pH conditions. In this paper, tungsten nitride nanorods array was developed on carbon cloth (WN NA/CC) through nitridation of corresponding WO3 NA/CC precursor with NH3 as an efficient 3D hydrogen evolution cathode with strong durability in acidic solutions. It needs overpotential of 198 mV to achieve current density of 10 mA cm−2 and it maintains its catalytic activity for at least 60 h. This electrode also performs well under both neutral and alkaline conditions. In addition, this electrode shows nearly 100% Faradaic efficiency at all pH values

  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. 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.

  15. 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

  16. The electron-phonon relaxation time in thin superconducting titanium nitride films

    International Nuclear Information System (INIS)

    We report on the direct measurement of the electron-phonon relaxation time, τeph, in disordered TiN films. Measured values of τeph are from 5.5 ns to 88 ns in the 4.2 to 1.7 K temperature range and consistent with a T−3 temperature dependence. The electronic density of states at the Fermi level N0 is estimated from measured material parameters. The presented results confirm that thin TiN films are promising candidate-materials for ultrasensitive superconducting detectors

  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. 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.

  19. 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.

  20. 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)

  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. 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.

  3. Synthesis of Spherical Carbon Nitride-Based Polymer Composites by Continuous Aerosol-Photopolymerization with Efficient Light Harvesting.

    Science.gov (United States)

    Poostforooshan, Jalal; Badiei, Alireza; Kolahdouz, Mohammadreza; Weber, Alfred P

    2016-08-24

    Here we report a novel, facile, and sustainable approach for the preparation of spherical submicrometer carbon nitride-based polymer composites by a continuous aerosol-photopolymerization process. In this regard, spherical mesoporous carbon nitride (SMCN) nanoparticles were initially prepared via a nanocasting approach using spray-drying synthesized spherical mesoporous silica (SMS) nanoparticles as hard templates. In addition to experimental characterization, the effect of porosity on the light absorption enhancement and consequently the generation rate of electron-hole pairs inside the SMCN was simulated using a three-dimensional finite difference time-domain (FDTD) method. To produce the carbon nitride-based polymer composite, SMCN nanoparticles exhibit excellent performance in photopolymerization of butyl acrylate (PBuA) monomer in the presence of n-methyldiethanolamine (MDEA) as a co-initiator in a continuous aerosol-based process. In this one-pot synthesis, SMCN nanoparticles act not only as photoinitiators but at the same time as fillers and templates. The average aerosol residence time in the photoreactor is about 90 s. The presented aerosol-photopolymerization process avoids the need for solvent and surfactant, operates at room temperature, and, more importantly, is suitable to produce the spherical composite with hydrophobic polymers. Furthermore, we simulated the condition of SMCN nanoparticles during illumination in the gas phase process, which can freely rotate. The results demonstrated that the hole (h(+)) density is almost equally distributed in the whole part of the SMCN nanoparticles due to their rotation, leading to efficient light harvesting and more homogeneous photoreaction. The combination of the outstanding features of environmentally friendly SMCN, photopolymerization, and aerosol processing might open new avenues, especially in green chemistry, to produce novel polymer composites with multifunctional properties.

  4. Synthesis of Spherical Carbon Nitride-Based Polymer Composites by Continuous Aerosol-Photopolymerization with Efficient Light Harvesting.

    Science.gov (United States)

    Poostforooshan, Jalal; Badiei, Alireza; Kolahdouz, Mohammadreza; Weber, Alfred P

    2016-08-24

    Here we report a novel, facile, and sustainable approach for the preparation of spherical submicrometer carbon nitride-based polymer composites by a continuous aerosol-photopolymerization process. In this regard, spherical mesoporous carbon nitride (SMCN) nanoparticles were initially prepared via a nanocasting approach using spray-drying synthesized spherical mesoporous silica (SMS) nanoparticles as hard templates. In addition to experimental characterization, the effect of porosity on the light absorption enhancement and consequently the generation rate of electron-hole pairs inside the SMCN was simulated using a three-dimensional finite difference time-domain (FDTD) method. To produce the carbon nitride-based polymer composite, SMCN nanoparticles exhibit excellent performance in photopolymerization of butyl acrylate (PBuA) monomer in the presence of n-methyldiethanolamine (MDEA) as a co-initiator in a continuous aerosol-based process. In this one-pot synthesis, SMCN nanoparticles act not only as photoinitiators but at the same time as fillers and templates. The average aerosol residence time in the photoreactor is about 90 s. The presented aerosol-photopolymerization process avoids the need for solvent and surfactant, operates at room temperature, and, more importantly, is suitable to produce the spherical composite with hydrophobic polymers. Furthermore, we simulated the condition of SMCN nanoparticles during illumination in the gas phase process, which can freely rotate. The results demonstrated that the hole (h(+)) density is almost equally distributed in the whole part of the SMCN nanoparticles due to their rotation, leading to efficient light harvesting and more homogeneous photoreaction. The combination of the outstanding features of environmentally friendly SMCN, photopolymerization, and aerosol processing might open new avenues, especially in green chemistry, to produce novel polymer composites with multifunctional properties. PMID:27483090

  5. 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.

  6. 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

  7. Graphitic Carbon Nitride/Nitrogen-Rich Carbon Nanofibers: Highly Efficient Photocatalytic Hydrogen Evolution without Cocatalysts.

    Science.gov (United States)

    Han, Qing; Wang, Bing; Gao, Jian; Qu, Liangti

    2016-08-26

    An interconnected framework of mesoporous graphitic-C3 N4 nanofibers merged with in situ incorporated nitrogen-rich carbon has been prepared. The unique composition and structure of the nanofibers as well as strong coupling between the components endow them with efficient light-harvesting properties, improved charged separation, and a multidimensional electron transport path that enhance the performance of hydrogen production. The as-obtained catalyst exhibits an extremely high hydrogen-evolution rate of 16885 μmol h(-1)  g(-1) , and a remarkable apparent quantum efficiency of 14.3 % at 420 nm without any cocatalysts, which is much higher than most reported g-C3 N4 -based photocatalysts even in the presence of Pt-based cocatalysts.

  8. 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 %). PMID:27128407

  9. 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 %).

  10. 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.

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

    OpenAIRE

    Glowacka, D. M.; Crane, 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 ran...

  12. 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.

  13. Nanoindentation study of niobium nitride thin films on niobium fabricated by reactive pulsed laser deposition

    International Nuclear Information System (INIS)

    Highlights: • NbN films were deposited on Nb by pulsed laser deposition in nitrogen background. • We studied structural/mechanical properties by XRD, SEM, AFM, and nanoindentation. • The hardness increased from 14.0 to 18.9 GPa for laser fluence 15–25 J/cm2 at 10.7 Pa. • The hardness showed no correlation with laser fluence at high background pressure. • Increasing the laser fluence resulted in NbNx films with larger grain sizes. - Abstract: Nanomechanical and structural properties of NbNx films deposited on single crystal Nb using pulsed laser deposition for different substrate temperature were previously investigated as a function of film/substrate crystal structure (Mamun et al. (2012) [30]). In this study we focus on the effect of laser fluences and background nitrogen pressure on the nanomechanical and structural properties of NbNx films. The crystal structure and surface morphology of the thin films were tested by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. Using nanoindentation, the investigation of the nanomechanical properties revealed that the hardness of the NbNx films was directly influenced by the laser fluence for low background nitrogen pressure, whereas the nanomechanical hardness showed no apparent correlation with laser fluence at high background nitrogen pressure. The NbNx film hardness measured at 30% film thickness increased from 14.0 ± 1.3 to 18.9 ± 2.4 GPa when the laser fluence was increased from 15 to 25 J/cm2 at 10.7 Pa N2 pressure. X-ray diffraction showed NbNx films with peaks that correspond to δ-NbN cubic and β-Nb2N hexagonal phases in addition to the δ′-NbN hexagonal phase. Increasing the laser fluence resulted in NbNx films with larger grain sizes

  14. Facile One-Step Synthesis of Hybrid Graphitic Carbon Nitride and Carbon Composites as High-Performance Catalysts for CO2 Photocatalytic Conversion.

    Science.gov (United States)

    Wang, Yangang; Bai, Xia; Qin, Hengfei; Wang, Fei; Li, Yaguang; Li, Xi; Kang, Shifei; Zuo, Yuanhui; Cui, Lifeng

    2016-07-13

    Utilizing and reducing carbon dioxide is a key target in the fight against global warming. The photocatalytic performance of bulk graphitic carbon nitride (g-C3N4) is usually limited by its low surface area and rapid charge carrier recombination. To develop g-C3N4 more suitable for photocatalysis, researchers have to enlarge its surface area and accelerate the charge carrier separation. In this work, novel hybrid graphitic carbon nitride and carbon (H-g-C3N4/C) composites with various carbon contents have been developed for the first time by a facile one-step pyrolysis method using melamine and natural soybean oil as precursors. The effect of carbon content on the structure of H-g-C3N4/C composites and the catalytic activity for the photoreduction of CO2 with H2O were investigated. The results indicated that the introduction of carbon component can effectively improve the textural properties and electronic conductivity of the composites, which exhibited imporved photocatalytic activity for the reduction of CO2 with H2O in comparison with bulk g-C3N4. The highest CO and CH4 yield of 22.60 μmol/g-cat. and 12.5 μmol/g-cat., respectively, were acquired on the H-g-C3N4/C-6 catalyst with the carbon content of 3.77 wt % under 9 h simulated solar irradiation, which were more than twice as high as that of bulk g-C3N4. The remarkably increased photocatalytic performance arises from the synergistic effect of hybrid carbon and g-C3N4. PMID:27112547

  15. Facile One-Step Synthesis of Hybrid Graphitic Carbon Nitride and Carbon Composites as High-Performance Catalysts for CO2 Photocatalytic Conversion.

    Science.gov (United States)

    Wang, Yangang; Bai, Xia; Qin, Hengfei; Wang, Fei; Li, Yaguang; Li, Xi; Kang, Shifei; Zuo, Yuanhui; Cui, Lifeng

    2016-07-13

    Utilizing and reducing carbon dioxide is a key target in the fight against global warming. The photocatalytic performance of bulk graphitic carbon nitride (g-C3N4) is usually limited by its low surface area and rapid charge carrier recombination. To develop g-C3N4 more suitable for photocatalysis, researchers have to enlarge its surface area and accelerate the charge carrier separation. In this work, novel hybrid graphitic carbon nitride and carbon (H-g-C3N4/C) composites with various carbon contents have been developed for the first time by a facile one-step pyrolysis method using melamine and natural soybean oil as precursors. The effect of carbon content on the structure of H-g-C3N4/C composites and the catalytic activity for the photoreduction of CO2 with H2O were investigated. The results indicated that the introduction of carbon component can effectively improve the textural properties and electronic conductivity of the composites, which exhibited imporved photocatalytic activity for the reduction of CO2 with H2O in comparison with bulk g-C3N4. The highest CO and CH4 yield of 22.60 μmol/g-cat. and 12.5 μmol/g-cat., respectively, were acquired on the H-g-C3N4/C-6 catalyst with the carbon content of 3.77 wt % under 9 h simulated solar irradiation, which were more than twice as high as that of bulk g-C3N4. The remarkably increased photocatalytic performance arises from the synergistic effect of hybrid carbon and g-C3N4.

  16. 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

  17. Structural investigations of local non-homogeneities in thermally treated nitrided layers in carbon steels

    International Nuclear Information System (INIS)

    In order to improve steel performance in some applications the nitrided layers in steel may be subjected to additional heat treatment. One of the forms of such treatment is the incorporate quench hardening from the diphase α-γ area on the Fe-C diagram. This treatment results in secondary diffusion of nitrogen into the base metal, decompose of the surface nitride layer and an increase in the thickness of the hardened layer. An incomplete α-γ transition creates zones of varied bainite-martensite structures with varying nitrogen concentration and hardness. (author)

  18. 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. PMID:26748372

  19. A Graphene-like Oxygenated Carbon Nitride Material for Improved Cycle-Life Lithium/Sulfur Batteries.

    Science.gov (United States)

    Liu, Jinghai; Li, Wanfei; Duan, Limei; Li, Xin; Ji, Lei; Geng, Zhibin; Huang, Keke; Lu, Luhua; Zhou, Lisha; Liu, Zongrui; Chen, Wei; Liu, Liwei; Feng, Shouhua; Zhang, Yuegang

    2015-08-12

    Novel sulfur (S) anchoring materials and the corresponding mechanisms for suppressing capacity fading are urgently needed to advance the performance of Li/S batteries. Here, we designed and synthesized a graphene-like oxygenated carbon nitride (OCN) host material that contains tens of micrometer scaled two-dimensional (2D) rippled sheets, micromesopores, and oxygen heteroatoms. N content can reach as high as 20.49 wt %. A sustainable approach of one-step self-supporting solid-state pyrolysis (OSSP) was developed for the low-cost and large-scale production of OCN. The urea in solid sources not only provides self-supporting atmospheres but also produces graphitic carbon nitride (g-C3N4) working as 2D layered templates. The S/OCN cathode can deliver a high specific capacity of 1407.6 mA h g(-1) at C/20 rate with 84% S utilization and retain improved reversible capacity during long-term cycles at high current density. The increasing micropores, graphitic N, ether, and carboxylic O at the large sized OCN sheet favor S utilization and trapping for polysulfides.

  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. 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

  2. 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

  3. 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...

  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. The Effect of Mesoporous Carbon Nitride Modification by Titanium Oxide Nanoparticles on Photocatalytic Degradation of 1,3-Dinitrobenzene

    Directory of Open Access Journals (Sweden)

    Seyyed Ershad Moradi

    2015-11-01

    Full Text Available In the present work, well ordered, mesoporous carbon nitride (MCN sorbent with uniform mesoporous wall, high surface area and pore volume has been fabricated using the simple polymerization reaction between ethylene diamine and carbon tetrachloride in mesoporous silica media, and then modified by TiO2 nanoparticles (Ti-MCN. The structural order and textural properties of the nanoporous materials were studied by XRD, elemental analysis, and nitrogen adsorption–desorption experiments. Photodegradation experiments for 1,3-dinitrobenzene were conducted in batch mode, the Ti-MCN catalysts were found to be more active compared to the free TiO2 nanoparticles for 1,3-dinitrobenzene degradation.

  6. Influence of cubic boron nitride grinding on the fatigue strengths of carbon steels and a nickel-base superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Kawagoishi, N.; Chen, Q.; Kondo, E. [Kagoshima Univ. (Japan). Faculty of Engineering; Goto, M. [Oita Univ. (Japan). Faculty of Engineering; Nisitani, H. [Kyushu Sangyo Univ., Fukuoka (Japan). Faculty of Engineering

    1999-04-01

    The influence of cubic boron nitride (CBN) grinding on fatigue strength was investigated on an annealed carbon steel, a quenched and tempered carbon steel at room temperature, and a nickel-base superalloy, Inconel 718, at room temperature and 500 C. The results were discussed from several viewpoints, including surface roughness, residual stress, and work hardening or softening due to CBN grinding. The fatigue strength increased upon CBN grinding at room temperature, primarily because of the generation of compressive residual stress in the surface region. However, in the case of Inconel 718, this marked increase in the fatigue strength tended to disappear at the elevated temperature due to the release of compressive residual stress and the decrease of crack growth resistance at an elevated temperature.

  7. Preparation of self-supporting carbon thin films

    CERN Document Server

    Lommel, B; Kindler, B; Klemm, J; Steiner, J

    2002-01-01

    For heavy-ion beam experiments, self-supporting carbon thin films are needed as targets, stripper foils and as backings (Nucl. Instr. and Meth. A 334 (1993) 69) for materials which cannot be produced self-supporting. Using resistance evaporation under high vacuum, self-supporting carbon foils with a thickness of 5 mu g/cm sup 2 and a diameter of 10 mm, a thickness of 10 mu g/cm sup 2 and a diameter of 50 mm up to a thickness of 50 mu g/cm sup 2 and a diameter of 300 mm can be obtained. Due to the energy impact of the heavy-ion beam, the amorphous carbon is restructured into textured graphite, as was found already by Dollinger et al. (Nucl. Instr. and Meth. A 303 (1991) 79). The discuss the production process as well as the change of the layer structure caused by the energy deposit.

  8. Hydorgen sputtering of carbon thin films deposited on platinum

    International Nuclear Information System (INIS)

    Carbon has been suggested as a suitable low Z element for the lining of the first walls of controlled thermonuclear reactors in order to reduce radiative plasma losses due to sputtering. In this paper the measurement of sputtering of carbon thin films by protons in the energy range 0.6-10.0 keV, is described. H2+ or H3+ ions were used as bombarding ions to obtain equivalent H+ sputtering yields at energies below that at which the ion source provides sufficient proton current. The sputter yield was found to range from 7x10-3-1.5x10-2 atoms/proton with a broad maximum in the 2.0 keV region with the carbon film kept near ambient temperature. (B.D.)

  9. 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.

  10. 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.

  11. Applications of thin carbon coatings and films in injection molding

    Science.gov (United States)

    Cabrera, Eusebio Duarte

    In this research, the technical feasibility of two novel applications of thin carbon coatings is demonstrated. The first application consists of using thin carbon coatings on molds for molding ultra-thin plastic parts (EMI) shielding for plastic parts using in mold coated nanoparticle thin films or nanopapers to create a conductive top layer. During this research, the technical feasibility of a new approach was proven which provides injection molding of ultra-thin parts at lower pressures, without the need of fast heating/fast cooling or other expensive mold modification. An in-house developed procedure by other members of our group, was employed for coating the mold surface using chemical vapor deposition (CVD) resulting in a graphene coating with carbide bonding to the mold surface. The coating resulted in a significant decrease of surface friction and consequently easiness of flow when compared to their uncoated counterparts. Thermoplastic polymers and their composites are a very attractive alternative but are hindered by the non-conductive nature of polymers. There are two general approaches used to date to achieve EMI shielding for plastic products. One is to spray a conductive metal coating onto the plastic surface forming a layer that must maintain its shielding effectiveness (SE), and its adhesion to the plastic throughout the expected life of the product. However, metal coatings add undesirable weight and tend to corrode over time. Furthermore, scratching the coating may create shielding failure; therefore, a protective topcoat may be required. The other approach is to use polymer composites filled with conductive fillers such as carbon black (CB), carbon nanofiber (CNF), and carbon nanotube (CNT). While conductive fillers may increase the electrical conductivity of polymer composites, the loading of such fillers often cannot reach a high level (EMI shielding of plastic parts was proven using in mold coated nanoparticle thin films or nanopapers to create a

  12. 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.

  13. 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.

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

    Science.gov (United States)

    Jia, Zheng-feng; Wang, Peng; Xia, Yan-qiu; Zhang, Hao-bo; Pang, Xian-juan; Li, Bin

    2009-04-01

    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 2 tribofilm, and decrease coefficient of friction of rubbing pairs.

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

    International Nuclear Information System (INIS)

    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 MoS2 tribofilm, and decrease coefficient of friction of rubbing pairs.

  16. Insertion of nanocrystalline diamond film and the addition of hydrogen gas during deposition for adhesion improvement of cubic boron nitride thin film deposited by unbalanced magnetron sputtering method

    International Nuclear Information System (INIS)

    Cubic boron nitride (c-BN) thick film growth was attempted by the addition of hydrogen for residual stress reduction and by using a nanocrystalline diamond (NCD) buffer layer for stabilizing the turbostratic boron nitride interfacial layer. The c-BN films were deposited by the unbalanced magnetron sputtering method. Thin (100 μm) Si strips (3 × 40 mm2) were used as substrates. A boron nitride target was used, which was connected to a radio frequency power supply at 400 W. High frequency power connected to a substrate holder was used for self-biasing of − 40 V. The deposition pressure was 0.27 Pa with a flow of Ar (18 sccm)–N2 (2 sccm) mixed gas. Hydrogen gas of 2 sccm was added to the Ar–N2 mixed gas. The effect of the addition time of the hydrogen to the Ar–N2 gas during deposition was investigated and found to be critical to the occurrence of the delamination of the c-BN film on the NCD buffer layer. As the addition of the hydrogen was delayed, the delamination started later. C-BN film of 3 μm thickness adherent to the substrate was obtained. - Highlights: • A nanocrystalline diamond (NCD) buffer layer was applied to enhance the adhesion. • Hydrogen in the reaction gas caused delamination of the film at c-BN/NCD interface. • A delayed hydrogen addition was effective in inhibiting such delamination. • About 3 μm thick c-BN film could be grown

  17. Highly selective hydrogenation of phenol and derivatives over a Pd@carbon nitride catalyst in aqueous media.

    Science.gov (United States)

    Wang, Yong; Yao, Jia; Li, Haoran; Su, Dangsheng; Antonietti, Markus

    2011-03-01

    Cyclohexanone is an important intermediate in the manufacture of polyamides in chemical industry, but direct selective hydrogenation of phenol to cyclohexanone under mild conditions is a challenge. We report here a catalyst made of Pd nanoparticles supported on a mesoporous graphitic carbon nitride, Pd@mpg-C(3)N(4), which was shown to be highly active and promoted the selective formation of cyclohexanone under atmospheric pressure of hydrogen in aqueous media without additives. Conversion of 99% and a selectivity higher than 99% were achieved within 2 h at 65 °C. The reaction can be accelerated at higher temperature, but even at room temperature, 99% conversion and 96% selectivity could still be obtained. The generality of the Pd@mpg-C(3)N(4) catalyst for this reaction was demonstrated by selective hydrogenation of other hydroxylated aromatic compounds with similar performance. PMID:21294506

  18. 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.

  19. 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. PMID:26473176

  20. 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.

  1. 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.

  2. Unique Static Magnetic and Dynamic Electromagnetic Behaviors in Titanium Nitride/Carbon Composites Driven by Defect Engineering

    Science.gov (United States)

    Gong, Chunhong; Meng, Hongjie; Zhao, Xiaowei; Zhang, Xuefeng; Yu, Laigui; Zhang, Jingwei; Zhang, Zhijun

    2016-01-01

    Recently, the defect-induced static magnetic behaviours of nanomaterials have been a cutting-edge issue in diluted magnetic semiconductor materials. However, the dynamic magnetic properties of nanomaterials are commonly ignored if their bulk counterparts are non-magnetic. In the present research, titanium nitride-carbon (TiN/C) nanocomposites were found to exhibit both static and dynamic magnetic properties that vary in the opposite trend. Moreover, novel unconventional electromagnetic resonance behaviour was demonstrated in TiN/C systems, and their permeability and permittivity show similar trend. This is challenging for the traditional understanding of electromagnetism and makes it possible to achieve an appropriate balance between the permeability and permittivity simultaneously in a simple system. Hopefully, the results could provide some valuable clues to revealing the magnetism and electromagnetism of nanostructures. PMID:26739853

  3. 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

  4. 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.

  5. Effect of the stoichiometry of Si-rich silicon nitride thin films on their photoluminescence and structural properties

    Energy Technology Data Exchange (ETDEWEB)

    Torchynska, T.V., E-mail: ttorch@esfm.ipn.mx [ESFM—Instituto Politecnico Nacional, Mexico DF 07738 (Mexico); Casas Espinola, J.L. [ESFM—Instituto Politecnico Nacional, Mexico DF 07738 (Mexico); Vergara Hernandez, E. [UPIITA—Instituto Politecnico Nacional, Mexico DF 07320 (Mexico); Khomenkova, L., E-mail: khomen@ukr.net [V. Lashkaryov Institute of Semiconductor Physics, 45 Pr. Nauky, 03028 Kyiv (Ukraine); Delachat, F.; Slaoui, A. [ICube, 23 rue du Loess, BP 20 CR, 67037 Strasbourg Cedex 2 (France)

    2015-04-30

    Si-rich Silicon nitride films were grown on silicon substrates by plasma enhanced chemical vapor deposition. The film stoichiometry was controlled via the variation of NH{sub 3}/SiH{sub 4} ratio from 0.45 up to 1.0. Thermal annealing at 1100 °C for 30 min in the nitrogen flow was applied to form the Si nanocrystals in the films that have been investigated by means of photoluminescence and Raman scattering methods, as well as transmission electron microscopy. Several emission bands have been detected with the peak positions at: 2.8–3.0 eV, 2.5–2.7 eV, 2.10–2.25 eV, and 1.75–1.98 eV. The temperature dependences of photoluminescence spectra were studied with the aim to confirm the types of optical transitions and the nature of light emitting defects in silicon nitride. The former three bands were assigned to the defects in silicon nitride, whereas the last one (1.75–1.98 eV) was attributed to the exciton recombination inside of Si nanocrystals. The photoluminescence mechanism is discussed. - Highlights: • Substoichiometric silicon nitride films were grown by PECVD technique. • The variation of the NH{sub 3}/SiH{sub 4} ratio controls excess Si content in the films. • Both Si nanocrystals and amorphous Si phase were observed in annealed films. • Temperature evolution of carrier recombination via Si nanocrystals and host defects.

  6. 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)

  7. Microstructural Characterization of Low Temperature Gas Nitrided Martensitic Stainless Steel

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2015-01-01

    The present work presents microstructural investigations of the surface zone of low temperature gas nitrided precipitation hardening martensitic stainless steel AISI 630. Grazing incidence X-ray diffraction was applied to investigate the present phases after successive removal of very thin sections...... of the sample surface. The development of epsilon nitride, expanded austenite and expanded martensite resulted from the low temperature nitriding treatments. The microstructural features, hardness and phase composition are discussed with emphasis on the influence of nitriding duration and nitriding potential....

  8. Properties of thermally oxidized and nitrided Zr-oxynitride thin film on 4H-SiC in diluted N{sub 2}O ambient

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Yew Hoong [Energy Efficient and Sustainable Semiconductor Research Group, School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Seberang Perai Selatan, Penang (Malaysia); Cheong, Kuan Yew, E-mail: cheong@eng.usm.my [Energy Efficient and Sustainable Semiconductor Research Group, School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Seberang Perai Selatan, Penang (Malaysia)

    2012-10-15

    A systematic investigation on the structural, chemical, and electrical properties of thermally oxidized and nitrided sputtered Zr thin film in various N{sub 2}O ambient (10-100%) at 500 Degree-Sign C for 15 min to form Zr-oxynitride on 4H-SiC substrate has been carried out. The chemical composition, depth profile analysis, and energy band alignment have been evaluated by X-ray photoelectron spectrometer. Zr-oxynitride layer and its interfacial layer comprised of compounds related to Zr-O, Zr-N, Zr-O-N, Si-N, and/or C-N were identified. A model related to the oxidation and nitridation mechanism has been suggested. Supportive results related to the model were obtained by energy filtered transmission electron microscopy, X-ray diffraction, and Raman analyses. A proposed crystal structure was employed to elucidate the surface roughness and topographies of the samples, which were characterized by atomic force microscopy. The electrical results revealed that 10% N{sub 2}O sample has possessed the highest breakdown field and reliability. This was owing to the confinement of nitrogen-related compounds of Zr-O-N and/or Zr-N at or near interfacial layer region, smaller grain with finer structure on the surface, the lowest interface trap density, total interface trap density, and effective oxide charge, and highest barrier height between conduction band edge of oxide and semiconductor. -- Highlights: Black-Right-Pointing-Pointer Zr-oxynitride as the gate oxide deposited on 4H-SiC substrate. Black-Right-Pointing-Pointer Simultaneous oxidation and nitridation of sputtered Zr thin film on 4H-SiC using various concentrations of N{sub 2}O gas. Black-Right-Pointing-Pointer Presence of interfacial layer comprised of mixed compounds related to Zr-O, Zr-N, Zr-O-N, Si-N, and/or C-N. Black-Right-Pointing-Pointer The highest electrical breakdown and highest reliability at diluted N{sub 2}O of 10%.

  9. 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.

  10. 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

    2015-11-01

    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.

  11. Separation and concentration of natural products by fast forced adsorption using well-dispersed velvet-like graphitic carbon nitride with response surface methodology optimisation.

    Science.gov (United States)

    Ding, Xinru; Zhu, Jun; Zhang, Yue; Xia, Qian; Bi, Wentao; Yang, Xiaodi; Yang, Jinfei

    2016-07-01

    Well-dispersed velvet-like graphitic carbon nitride nanoparticles with a large surface area were prepared and utilized for separation and concentration of bioactive compounds from fruit extracts by fast (20s) forced adsorption. The large surface area, enhanced non-covalent interactions of this nanoparticle with bioactive compounds and good dispersity in different solvents benefited its application as a good sorbent. To evaluate their adsorption capabilities, these carbon nitride nanoparticles were used for separation and concentration of flavonoids from fruit extracts by a forced-adsorption dispersive solid phase extraction method. The combined use of this nanoparticle and our experimental conditions showed excellent precision (3.6-4.7%) and sensitivity (limits of detection (S/N=3): 0.6-3.75ng/mL). This research provides an alternative strategy to prepare suitable sorbents for adsorption, separation and concentration of various compounds from different extracts.

  12. 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

  13. Influence of the power on the processes controlling the formation of ECR-CVD carbon nitride films from CH{sub 4}/Ar/N{sub 2} plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Camero, M [Instituto de Ciencia de Materiales de Madrid (CSIC), 28049 Madrid (Spain); Gordillo-Vazquez, F J [Instituto de Optica (CSIC), Serrano 121, 28006 Madrid (Spain); Ortiz, J [Instituto de Ciencia de Materiales de Madrid (CSIC), 28049 Madrid (Spain); Gomez-Aleixandre, C [Instituto de Ciencia de Materiales de Madrid (CSIC), 28049 Madrid (Spain)

    2004-02-01

    Carbon nitride films have been synthesized by means of electron cyclotron resonance chemical vapour deposition (ECR-CVD) using different power values (50-212 W) at constant pressure conditions (0.03 mbar). Optical emission spectroscopy and mass spectrometry were used for the characterization of the plasma. The films were analysed using energy dispersive x-ray spectroscopies. It was found that all signal peaks in the optical emission spectra increased monotonically following the increase in microwave power. Moreover, we have observed that the radiative emission from the 4p({sup 2}p{sub 9}) resonant state of Ar is the most affected by CH{sub 4} addition to a pure argon plasma. The latter suggests that a Penning mechanism controls the activation of CH{sub 4} molecules with increasing power levels at relatively low pressures. Besides, the increase of excited N atoms indicates a higher activity of the etching mechanisms of carbon nitride films with increasing power.

  14. Initial nitride formation during plasma-nitridation of cobalt surfaces

    Science.gov (United States)

    Mattson, E. C.; Michalak, D. J.; Cabrera, W.; Veyan, J. F.; Chabal, Y. J.

    2016-08-01

    Nitridation of metal surfaces is of central importance in microelectronics and spintronics due to the excellent mechanical, thermal, and electrical properties of refractory nitrides. Here, we examine the chemical and structural modification of cobalt surfaces upon nitrogen plasma treatment, using in situ spectroscopic methods, as a method for synthesis of cobalt nitride thin films. We find that nitrogen is incorporated below the surface and forms an ultrathin film of CoN at temperatures as low as 50 °C. In addition, we observe the incorporation of oxygen and NO+ within the surface region. The nitrided cobalt surfaces are fully passivated by N, O, and NO+. These results provide a route for incorporation of cobalt nitride into a wide range applications.

  15. 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.

  16. 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.

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

    International Nuclear Information System (INIS)

    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. - Highlights: • Measurements of wet-ability of liquid drops on a 30 nm Si3N4 film were performed. • Chemical composition was investigated by X-ray Photoelectron Spectroscopy (XPS). • Surface morphology was tested by Atomic Force Microscopy (AFM). • Ar+ bombardment increases the contact angle, oxygen content and surface roughness

  18. 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.

  19. Research of Graphitic Carbon Nitride and the Applications in Photocatalysis%石墨相氮化碳材料及其光催化应用

    Institute of Scientific and Technical Information of China (English)

    苗阳森; 卢春山; 李小年

    2016-01-01

    Graphitic carbon nitride has a unique electronic band structure and excellent chemical stabil-ity, and it's widely used as a novel metal-free visible light photocatalyst in the field of photocatalysis. The ar-ticle reviews the recent advances of graphitic carbon nitride, especially on the synthesis methods, the struc-tural characteristics, carbon nitride-based derivatives, applications in photocatalysis and so on.%石墨相氮化碳具有独特的电子能带结构和优异的化学稳定性,作为一种不含金属成分的新型可见光光催化剂,在光催化领域有着广泛的应用前景。介绍了近年来石墨相氮化碳的研究现状,重点探讨其合成方法、结构特性和其相关的衍生物以及在光催化中的应用。

  20. Thin film thickness measurements using Scanning White Light Interferometry

    International Nuclear Information System (INIS)

    Scanning White Light Interferometry is a well-established technique for providing accurate surface roughness measurements and three dimensional topographical images. Here we report on the use of a variant of Scanning White Light Interferometry called coherence correlation interferometry which is now capable of providing accurate thickness measurements from transparent and semi-transparent thin films with thickness below 1 μm. This capability will have many important applications which include measurements on optical coatings, displays, semiconductor devices, transparent conducting oxides and thin film photovoltaics. In this paper we report measurements of thin film thickness made using coherence correlation interferometry on a variety of materials including metal-oxides (Nb2O5 and ZrO2), a metal-nitride (SiNx:H), a carbon-nitride (SiCxNy:H) and indium tin oxide, a transparent conducting oxide. The measurements are compared with those obtained using spectroscopic ellipsometry and in all cases excellent correlation is obtained between the techniques. A key advantage of this capability is the combination of thin film thickness and surface roughness and other three-dimensional metrology measurements from the same sample area. - Highlights: • Capability to make thin film measurements with sub-nanometre accuracy • Measurements of thin film thickness made on metal-oxides, nitrides and carbon-nitrides • Excellent correlation with thickness measurements using spectroscopic ellipsometry • Thin film measurement and nanometrology from the same sample area

  1. Thin film thickness measurements using Scanning White Light Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Maniscalco, B.; Kaminski, P.M.; Walls, J.M., E-mail: J.M.Walls@lboro.ac.uk

    2014-01-01

    Scanning White Light Interferometry is a well-established technique for providing accurate surface roughness measurements and three dimensional topographical images. Here we report on the use of a variant of Scanning White Light Interferometry called coherence correlation interferometry which is now capable of providing accurate thickness measurements from transparent and semi-transparent thin films with thickness below 1 μm. This capability will have many important applications which include measurements on optical coatings, displays, semiconductor devices, transparent conducting oxides and thin film photovoltaics. In this paper we report measurements of thin film thickness made using coherence correlation interferometry on a variety of materials including metal-oxides (Nb{sub 2}O{sub 5} and ZrO{sub 2}), a metal-nitride (SiN{sub x}:H), a carbon-nitride (SiC{sub x}N{sub y}:H) and indium tin oxide, a transparent conducting oxide. The measurements are compared with those obtained using spectroscopic ellipsometry and in all cases excellent correlation is obtained between the techniques. A key advantage of this capability is the combination of thin film thickness and surface roughness and other three-dimensional metrology measurements from the same sample area. - Highlights: • Capability to make thin film measurements with sub-nanometre accuracy • Measurements of thin film thickness made on metal-oxides, nitrides and carbon-nitrides • Excellent correlation with thickness measurements using spectroscopic ellipsometry • Thin film measurement and nanometrology from the same sample area.

  2. 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.

  3. Unique Solvent Effects on Visible-Light CO2 Reduction over Ruthenium(II)-Complex/Carbon Nitride Hybrid Photocatalysts.

    Science.gov (United States)

    Kuriki, Ryo; Ishitani, Osamu; Maeda, Kazuhiko

    2016-03-01

    Photocatalytic CO2 reduction using hybrids of carbon nitride (C3N4) and a Ru(II) complex under visible light was studied with respect to reaction solvent. Three different Ru(II) complexes, trans(Cl)-[Ru(X2bpy) (CO)2Cl2] (X2bpy = 2,2'-bipyridine with substituents X in the 4-positions, X = COOH, PO3H2, or CH2PO3H2), were employed as promoters and will be abbreviated as RuC (X = COOH), RuP (X = PO3H2), and RuCP (X = CH2PO3H2). When C3N4 modified with a larger amount of RuCP (>7.8 μmol g(-1)) was employed as a photocatalyst in a solvent having a relatively high donor number (e.g., N,N-dimethylacetamide (DMA), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO)) with the aid of triethanolamine (TEOA) as an electron donor, the hybrid photocatalyst exhibited high performance for CO2 reduction, producing CO and HCOOH with relatively high CO selectivity (40-70%). On the other hand, HCOOH was the major product when RuC/C3N4 or RuP/C3N4 was employed regardless of the loading amount of the Ru(II) complex and the reaction solvent. Results of photocatalytic reactions and UV-visible diffuse reflectance spectroscopy indicated that polymeric Ru species, which were formed in situ from RuCP on C3N4 under irradiation in a solvent having a high donor number, were active catalysts for CO formation. Nonsacrificial CO2 reduction using RuP/C3N4 was accomplished in a DMA solution containing methanol as an electron donor, which means that visible light energy was stored as chemical energy in the form of CO and formaldehyde (ΔG° = +67.6 kJ mol(-1)). This study demonstrated the first successful example of an energy conversion scheme using carbon nitride through photocatalytic CO2 reduction.

  4. 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

  5. Single Atom (Pd/Pt) Supported on Graphitic Carbon Nitride as an Efficient Photocatalyst for Visible-Light Reduction of Carbon Dioxide.

    Science.gov (United States)

    Gao, Guoping; Jiao, Yan; Waclawik, Eric R; Du, Aijun

    2016-05-18

    Reducing carbon dioxide to hydrocarbon fuel with solar energy is significant for high-density solar energy storage and carbon balance. In this work, single atoms of palladium and platinum supported on graphitic carbon nitride (g-C3N4), i.e., Pd/g-C3N4 and Pt/g-C3N4, respectively, acting as photocatalysts for CO2 reduction were investigated by density functional theory calculations for the first time. During CO2 reduction, the individual metal atoms function as the active sites, while g-C3N4 provides the source of hydrogen (H*) from the hydrogen evolution reaction. The complete, as-designed photocatalysts exhibit excellent activity in CO2 reduction. HCOOH is the preferred product of CO2 reduction on the Pd/g-C3N4 catalyst with a rate-determining barrier of 0.66 eV, while the Pt/g-C3N4 catalyst prefers to reduce CO2 to CH4 with a rate-determining barrier of 1.16 eV. In addition, deposition of atom catalysts on g-C3N4 significantly enhances the visible-light absorption, rendering them ideal for visible-light reduction of CO2. Our findings open a new avenue of CO2 reduction for renewable energy supply.

  6. Single Atom (Pd/Pt) Supported on Graphitic Carbon Nitride as an Efficient Photocatalyst for Visible-Light Reduction of Carbon Dioxide.

    Science.gov (United States)

    Gao, Guoping; Jiao, Yan; Waclawik, Eric R; Du, Aijun

    2016-05-18

    Reducing carbon dioxide to hydrocarbon fuel with solar energy is significant for high-density solar energy storage and carbon balance. In this work, single atoms of palladium and platinum supported on graphitic carbon nitride (g-C3N4), i.e., Pd/g-C3N4 and Pt/g-C3N4, respectively, acting as photocatalysts for CO2 reduction were investigated by density functional theory calculations for the first time. During CO2 reduction, the individual metal atoms function as the active sites, while g-C3N4 provides the source of hydrogen (H*) from the hydrogen evolution reaction. The complete, as-designed photocatalysts exhibit excellent activity in CO2 reduction. HCOOH is the preferred product of CO2 reduction on the Pd/g-C3N4 catalyst with a rate-determining barrier of 0.66 eV, while the Pt/g-C3N4 catalyst prefers to reduce CO2 to CH4 with a rate-determining barrier of 1.16 eV. In addition, deposition of atom catalysts on g-C3N4 significantly enhances the visible-light absorption, rendering them ideal for visible-light reduction of CO2. Our findings open a new avenue of CO2 reduction for renewable energy supply. PMID:27116595

  7. 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

  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. 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.

  10. Copper(II)-Graphitic Carbon Nitride Triggered Synergy: Improved ROS Generation and Reduced Glutathione Levels for Enhanced Photodynamic Therapy.

    Science.gov (United States)

    Ju, Enguo; Dong, Kai; Chen, Zhaowei; Liu, Zhen; Liu, Chaoqun; Huang, Yanyan; Wang, Zhenzhen; Pu, Fang; Ren, Jinsong; Qu, Xiaogang

    2016-09-12

    Graphitic carbon nitride (g-C3 N4 ) has been used as photosensitizer to generate reactive oxygen species (ROS) for photodynamic therapy (PDT). However, its therapeutic efficiency was far from satisfactory. One of the major obstacles was the overexpression of glutathione (GSH) in cancer cells, which could diminish the amount of generated ROS before their arrival at the target site. Herein, we report that the integration of Cu(2+) and g-C3 N4 nanosheets (Cu(2+) -g-C3 N4 ) led to enhanced light-triggered ROS generation as well as the depletion of intracellular GSH levels. Consequently, the ROS generated under light irradiation could be consumed less by reduced GSH, and efficiency was improved. Importantly, redox-active species Cu(+) -g-C3 N4 could catalyze the reduction of molecular oxygen to the superoxide anion or hydrogen peroxide to the hydroxyl radical, both of which facilitated the generation of ROS. This synergy of improved ROS generation and GSH depletion could enhance the efficiency of PDT for cancer therapy.

  11. Phosphorus-Doped Carbon Nitride Tubes with a Layered Micro-nanostructure for Enhanced Visible-Light Photocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Guo, Shien; Deng, Zhaopeng; Li, Mingxia; Jiang, Baojiang; Tian, Chungui; Pan, Qingjiang; Fu, Honggang

    2016-01-26

    Phosphorus-doped hexagonal tubular carbon nitride (P-TCN) with the layered stacking structure was obtained from a hexagonal rod-like single crystal supramolecular precursor (monoclinic, C2/m). The production process of P-TCN involves two steps: 1) the precursor was prepared by self-assembly of melamine with cyanuric acid from in situ hydrolysis of melamine under phosphorous acid-assisted hydrothermal conditions; 2) the pyrolysis was initiated at the center of precursor under heating, thus giving the hexagonal P-TCN. The tubular structure favors the enhancement of light scattering and active sites. Meanwhile, the introduction of phosphorus leads to a narrow band gap and increased electric conductivity. Thus, the P-TCN exhibited a high hydrogen evolution rate of 67 μmol h(-1) (0.1 g catalyst, λ >420 nm) in the presence of sacrificial agents, and an apparent quantum efficiency of 5.68 % at 420 nm, which is better than most of bulk g-C3 N4 reported.

  12. Graphene oxide amplified electrochemiluminescence of graphitic carbon nitride and its application in ultrasensitive sensing for Cu(2+).

    Science.gov (United States)

    Xia, Binyuan; Chu, Mingfu; Wang, Shaofei; Wang, Wanqing; Yang, Shanli; Liu, Chengbin; Luo, Shenglian

    2015-09-01

    Here for the first time, we present a novel electrochemiluminescence (ECL) sensor based on graphitic carbon nitride/graphene oxide (g-C3N4/GO) hybrid for the ultrasensitive detection of Cu(2+), which is a common pollutant in environmental system. The g-C3N4/GO shows stable ECL signal in the presence of the self-produced coreactant from oxygen reduction, and the ECL signal could be effectively quenched by Cu(2+), the possible ECL detection mechanism has been proposed in detail. GO can not only significantly enhance the cathodic ECL signal of g-C3N4 (∼3.8 times), but also serve as immobilization platform for g-C3N4. After optimization of experimental conditions, the proposed protocol can offer an ultrasensitive, highly selective and recyclable method for the detection of Cu(2+) with a low detection limit of 1.0 × 10(-11) M and a wide linear range from 1.0 × 10(-11) to 1.0 × 10(-7) M. Moreover, the practicability of the ECL sensor in real wastewater samples is also tested, showing that the proposed ECL sensor could be a promising alternative method for the emergency and routine monitoring of Cu(2+) in real sample.

  13. Torsional properties of hexagonal boron nitride nanotubes, carbon nanotubes and their hybrid structures: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Qi-lin, E-mail: xiongql@hust.edu.cn [Department of Mechanics, Huazhong University of Science & Technology, 1037 Luoyu Road, Wuhan 430074 (China); Hubei Key Laboratory of Engineering Structural Analysis and Safety Assessment, Luoyu Road 1037, Wuhan 430074 (China); Tian, Xiao Geng [State Key Laboratory for Mechanical Structure Strength and Vibration, Xi’an Jiaotong University, Xi’an 710049 (China)

    2015-10-15

    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.

  14. 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.

  15. A novel photoelectrochemical biosensor for protein kinase activity assay based on phosphorylated graphite-like carbon nitride.

    Science.gov (United States)

    Li, Xue; Zhou, Yunlei; Xu, Yan; Xu, Huijie; Wang, Minghui; Yin, Huanshun; Ai, Shiyun

    2016-08-31

    Protein kinases are general and significant regulators in the cell signaling pathway, and it is still greatly desired to achieve simple and quick kinase detection. Herein, we develop a simple and sensitive photoelectrochemical strategy for the detection of protein kinase activity based on the bond between phosphorylated peptide and phosphorylated graphite-like carbon nitride (P-g-C3N4) conjugates triggered by Zr(4+) ion coordination. Under optimal conditions, the increased photocurrent is proportional to the protein kinase A (PKA) concentration ranging from 0.05 to 50 U/mL with a detection limit of 0.077 U/mL. Moreover, this photoelectrochemical assay can be also applied to quantitative analysis of kinase inhibition. The results indicated that the IC50 value (inhibitor concentration producing 50% inhibitor) for ellagic acid was 9.1 μM. Moreover, the developed method is further applied to detect PKA activity in real samples, which contains serum from healthy person and gastric cancer patients and breast tissue from healthy person and breast cancer patients. Therefore, the established protocol provides a new and simple tool for assay of kinase activity and its inhibitors with low cost and high sensitivity.

  16. 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.

  17. Synthesis of a graphitic carbon nitride nanocomposite with magnetite as a sorbent for solid phase extraction of phenolic acids

    International Nuclear Information System (INIS)

    We have developed a facile in-situ growth method for the deposition of magnetite (Fe3O4) particles on the surface of a graphitic carbon nitride (g-C3N4) nanosheet. The material was characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The high affinity of g-C3N4 for phenolic acids in combination with the magnetism of Fe3O4 provides an efficient means for magnetic solid phase extraction. The adsorption, desorption and recoveries were examined. Under optimized conditions, the method has limits of detection in the range from 17.5–42.6 ng mL−1 (at an S/N of 3), and precisions from 2.8–3.8 % (for n = 5). The method was successfully applied to the determination of protocatechuic, caffeic, and ferulic acids in Salicornia herbacea L. plant extracts. Recoveries ranged from 92.4–99.5 %. (author)

  18. 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.

  19. Phosphorus-Doped Carbon Nitride Tubes with a Layered Micro-nanostructure for Enhanced Visible-Light Photocatalytic Hydrogen Evolution.

    Science.gov (United States)

    Guo, Shien; Deng, Zhaopeng; Li, Mingxia; Jiang, Baojiang; Tian, Chungui; Pan, Qingjiang; Fu, Honggang

    2016-01-26

    Phosphorus-doped hexagonal tubular carbon nitride (P-TCN) with the layered stacking structure was obtained from a hexagonal rod-like single crystal supramolecular precursor (monoclinic, C2/m). The production process of P-TCN involves two steps: 1) the precursor was prepared by self-assembly of melamine with cyanuric acid from in situ hydrolysis of melamine under phosphorous acid-assisted hydrothermal conditions; 2) the pyrolysis was initiated at the center of precursor under heating, thus giving the hexagonal P-TCN. The tubular structure favors the enhancement of light scattering and active sites. Meanwhile, the introduction of phosphorus leads to a narrow band gap and increased electric conductivity. Thus, the P-TCN exhibited a high hydrogen evolution rate of 67 μmol h(-1) (0.1 g catalyst, λ >420 nm) in the presence of sacrificial agents, and an apparent quantum efficiency of 5.68 % at 420 nm, which is better than most of bulk g-C3 N4 reported. PMID:26692105

  20. 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.

  1. First-principles study of hydrogen storage on Ti (Sc)-decorated boron-carbon-nitride sheet

    Energy Technology Data Exchange (ETDEWEB)

    Song Nahong [College of Computer and Information Engineering, Henan University of Economics and Law, Zhengzhou 450002 (China); Wang Yusheng [College of Mathematics and Information Science, North China University of Water Resources and Electric Power, Zhengzhou, Henan 450011 (China); Center of Clean Energy and Quantum Structures, School of Physics and Engineering, Zhengzhou University, Zhengzhou, Henan 450052 (China); Sun Qiang [Center of Clean Energy and Quantum Structures, School of Physics and Engineering, Zhengzhou University, Zhengzhou, Henan 450052 (China); Jia Yu, E-mail: xxwysheng@163.com [Center of Clean Energy and Quantum Structures, School of Physics and Engineering, Zhengzhou University, Zhengzhou, Henan 450052 (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer The gravimetric densities of H{sub 2} are 7.6 wt% and 7.8 wt%, respectively. Black-Right-Pointing-Pointer The average adsorption energy of hydrogen molecule is in the range of 0.4-0.56 eV/H{sub 2} (0.13-0.27 eV/H{sub 2}). Black-Right-Pointing-Pointer It can operate under ambient thermodynamic conditions. - Abstract: Ab initio first-principles calculations are carried out to investigate Ti (Sc)-decorated two-dimensional boron-carbon-nitride (BC{sub 2}N) sheets for their application as hydrogen storage materials. The results show that with four H{sub 2} molecules attached to per metal atom the Ti (Sc)-decorated BC{sub 2}N can store up to 7.6 wt% (7.8 wt%) of hydrogen in molecular form. The Kubas interaction and the polarization mechanism lead to the adsorption energy within the range of 0.4-0.56 eV/H{sub 2} (0.13-0.27 eV/H{sub 2}), which is suitable for ambient temperature hydrogen storage.

  2. 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.

  3. 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.

  4. Origin of photoactivity in graphitic carbon nitride and strategies for enhancement of photocatalytic efficiency: insights from first-principles computations.

    Science.gov (United States)

    Zhang, Haijun; Zuo, Xueqin; Tang, Huaibao; Li, Guang; Zhou, Zhen

    2015-03-01

    The origin of the photoactivity in graphitic carbon nitride (g-C3N4) and the strategies for improving its photocatalytic efficiency were systematically investigated using first-principles computations. We found that g-C3N4 composed of tri-s-triazine units (g-CN1) is preferable in photocatalysis, owing to its visible-light absorption and appropriate band edge potentials. Despite the benefit of nanocrystallization of g-CN1, excessively minimized and passivated g-CN1 nanosheets (g-CN1NSs) should be inhibited, due to the intensely broadened band gaps in these structures. C- or N-vacancies in g-CN1NSs lead to gap states and smaller band widths, which should also be restrained. Compared with C substitution in B doped g-CN1NSs, N-substitution is favourable for enhancing the photoactivity of g-CN1NSs, due to the red-shift light absorption and the absence of gap states within this structure. Both WTe2 coupled and CdSe cluster loaded g-CN1NSs have decreased band gaps and directly separated carriers, which are beneficial to promote the photoactivity of g-CN1NSs. Among these modified g-CN1NS photocatalysts, WTe2 coupled g-CN1NSs are more preferable, as a result of their smaller band gap, free gap states and more rapid migration of excitons. PMID:25648139

  5. Effects of substrate bias voltage and target sputtering power on the structural and tribological properties of carbon nitride coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Pengfei, E-mail: wangpf@szu.edu.cn [Institute of Nanosurface Science and Engineering, College of Mechatronics and Control Engineering, Shenzhen University, Shenzhen 518060 (China); Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Takeno, Takanori [Laboratory of Nanointerface Engineering, Division of Mechanical Engineering, Tohoku University, Aoba 6-6-1, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Fontaine, Julien [Laboratoire de Tribologie et Dynamique des Systèmes, UMR 5513 – CNRS/Ecole Centrale de Lyon, Bâtiment H10, 36 Avenue Guy de Collongue, 69134 Écully Cedex (France); Aono, Masami [Department of Materials Science and Engineering, National Defense Academy, 1-10-20 Hashirimizu, Yokosuka, Kanagawa 239-8686 (Japan); Adachi, Koshi [Laboratory of Nanointerface Engineering, Division of Mechanical Engineering, Tohoku University, Aoba 6-6-1, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Miki, Hiroyuki [Center for Interdisciplinary Research, Tohoku University, Aoba 6-3, Aramaki, Aoba-ku, Sendai 980-8578 (Japan); Takagi, Toshiyuki [Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan)

    2014-06-01

    Effects of substrate bias voltage and target sputtering power on the structural and tribological properties of carbon nitride (CN{sub x}) coatings are investigated. CN{sub x} coatings are fabricated by a hybrid coating process with the combination of radio frequency plasma enhanced chemical vapor deposition (RF PECVD) and DC magnetron sputtering at various substrate bias voltage and target sputtering power in the order of −400 V 200 W, −400 V 100 W, −800 V 200 W, and −800 V 100 W. The deposition rate, N/C atomic ratio, and hardness of CN{sub x} coatings as well as friction coefficient of CN{sub x} coating sliding against AISI 52100 pin in N{sub 2} gas stream decrease, while the residual stress of CN{sub x} coatings increases with the increase of substrate bias voltage and the decrease of target sputtering power. The highest hardness measured under single stiffness mode of 15.0 GPa and lowest residual stress of 3.7 GPa of CN{sub x} coatings are obtained at −400 V 200 W, whereas the lowest friction coefficient of 0.12 of CN{sub x} coatings is achieved at −800 V 100 W. Raman and XPS analysis suggest that sp{sup 3} carbon bonding decreases and sp{sup 2} carbon bonding increases with the variations in substrate bias voltage and target sputtering power. Optical images and Raman characterization of worn surfaces confirm that the friction behavior of CN{sub x} coatings is controlled by the directly sliding between CN{sub x} coating and steel pin. Therefore, the reduction of friction coefficient is attributed to the decrease of sp{sup 3} carbon bonding in the CN{sub x} coating. It is concluded that substrate bias voltage and target sputtering power are effective parameters for tailoring the structural and tribological properties of CN{sub x} coatings. - Highlights: • Various CN{sub x} coatings are produced using a unique hybrid coating process. • Structural and tribological properties of CN{sub x} coatings are investigated. • The lowest friction

  6. Boron carbon nitride materials for tribological and high temperature device applications

    International Nuclear Information System (INIS)

    We have used ion (or neutral) and electron cyclotron resonance assisted physical vapor deposition to produce high quality BN/CN thin films on Si and sapphire substrates. We have already demonstrated deposition of films containing a high fraction of the metastable c-BN phase as determined by FTIR spectroscopy and transmission electron microscopy (TEM). Atomic force microscopy (AFM) measurements have shown our films to have an excellent rms roughness ∼10.5 A (which is better than the best CVD diamond thin films). Results from frictional force microscopy (FFM) from BN and BCN films show a direct correlation with surface N content. Preliminary results show friction properties superior to that of TiN (the standard in the thin film coatings industry). Hardness measurements on the same films yielded Knoop hardness (KH) values of ∼3350 kg/mm2, close to that of ceramic c-BN (3500 kg/mm2). In this paper we will present our results on the synthesis of these materials and discuss their hardness and tribological properties. Finally, BN and CN samples have been subjected to laser experiments and preliminary results are encouraging as far as the application of these materials to high temperature, high power optoelectronic systems and solid state device fabrication

  7. Carbon nanotube thin film transistors based on aerosol methods

    International Nuclear Information System (INIS)

    We demonstrate a fabrication method for high-performance field-effect transistors (FETs) based on dry-processed random single-walled carbon nanotube networks (CNTNs) deposited at room temperature. This method is an advantageous alternative to solution-processed and direct CVD grown CNTN FETs, which allows using various substrate materials, including heat-intolerant plastic substrates, and enables an efficient, density-controlled, scalable deposition of as-produced single-walled CNTNs on the substrate directly from the aerosol (floating catalyst) synthesis reactor. Two types of thin film transistor (TFT) structures were fabricated to evaluate the FET performance of dry-processed CNTNs: bottom-gate transistors on Si/SiO2 substrates and top-gate transistors on polymer substrates. Devices exhibited on/off ratios up to 105 and field-effect mobilities up to 4 cm2 V-1 s-1. The suppression of hysteresis in the bottom-gate device transfer characteristics by means of thermal treatment in vacuum and passivation by an atomic layer deposited Al2O3 film was investigated. A 32 nm thick Al2O3 layer was found to be able to eliminate the hysteresis.

  8. 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.

  9. 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.

  10. Preparation of new titanium nitride-carbon nanocomposites in supercritical benzene and their oxygen reduction activity in alkaline medium

    International Nuclear Information System (INIS)

    Highlights: • TiN/C/graphene composite (SIV) was synthesized using supercritical benzene medium. • SIV catalyst shows high ORR activity due to both TiN and graphene phases. • SIV improves ORR via a mainly 4-electron pathway to form water and around 16% H2O2. • SIV exhibits high stability due to reduce H2O2 and prevent surface poisoning. - Abstract: Titanium nitride-carbon nanocomposites are synthesized by the reaction of TiCl4 and NaN3 in supercritical benzene medium that also serves as a carbon source. The as-prepared precursors (SI, SII) are subjected to several heat treatments (SIII–SV). The synthesized nanoparticles are characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The samples are tested as electrocatalyst for oxygen reduction reaction in an alkaline electrolyte. It is shown that the electrocatalytic properties of the synthesized nanoparticles are highly dependent on the heat treatment atmosphere and duration. The heat treatment under ammonia atmosphere at 1000 °C for 10 h (SIV) increased the ORR mass activity from −0.64 (SI) to −1.28 mA mg−1 (SIV) at −0.6 V vs. SCE. Moreover, the heat treated sample (SIV) shows almost twice ORR mass activity as commercial TiN. Rotating disk electrode (RDE) measurements exhibit ORR on commercial TiN proceeds via two parallel pathways including two and four electrons, resulting in almost 60% H2O2 production, while SIV sample improves ORR by reducing H2O2 formation to almost 16%. The high ORR activity and stability of the sample SIV are mainly due to (i) random layer structure of carbon that combines through a hybrid state with TiN nanoparticles, (ii) unstoichiometric nitrogen and oxygen doped into TiN lattice, and (iii) higher electrochemical surface area. Moreover, the possible pathways of carbon phase formation in vicinity of

  11. The interaction between Boron-carbon-nitride heteronanotubes and lithium atoms: Role of composition proportion

    Science.gov (United States)

    Zhong, Rong-Lin; Xu, Hong-Liang; Su, Zhong-Min

    2016-08-01

    A series of Li@BCN models were systematically investigated to explore the physical origin of the interaction between lithium atoms and BCNs. Theoretical results show that the crucial electron population in the BCNs of Li@B-BCN and Li@N-BCN series is dramatically different. As results, the first hyperpolarizability of Li@B-BCN series increases with the increase of carbon proportion whereas that of Li@N-BCN series significantly decreases with the increase of carbon proportion. The results indicate that the physical properties of Li@BCN models are significantly dependent on the different chemical environment of the tube termination.

  12. 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.

  13. 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.

  14. ANALYSIS ON THE BEHAVIOR OF PRECIPITATES IN ULTRA-THIN HOT STRIP OF PLAIN LOW CARBON STEEL PRODUCED BY COMPACT STRIP PRODUCTION

    Institute of Scientific and Technical Information of China (English)

    H. Yu; Y.L. Kang; H.B. Dong; D.L. Liu; J. Fu

    2002-01-01

    This paper investigated the mechanism of precipitation and its influence upon prop-erties of ultra-thin hot strips of low carbon steel produced by CSP techniques usingexperiment and thermodynamics theory. The experimental results show that thereare lots of fine and dispersive precipitates in microstructures. By analysis, most ofaluminum nitrides are in grains, while coexisted precipitates of MnS are along grainboundaries. Coexisted precipitates compose cation-vacancy type oxides such as Al2O3in the core, while MnS is at the fringe of surface. The precipitation behavior of AlNand MnS in the hot strip is studied by thermodynamic calculation. At last, implica-tions between strengthening effect and techniques are analyzed using obtained solubilityproducts.

  15. Anomalous electrostatic potential properties in carbon nanotube thin films under a weak external electric field

    OpenAIRE

    Ishiyama, U; Cuong, Nguyen Thanh; Okada, Susumu

    2016-01-01

    Using density functional theory, we studied the electronic properties of carbon nanotube (CNT) thin films under an electric field. The carrier accumulation due to the electric field depends strongly on the CNT species forming the thin films. Under a low electron concentration, the injected electrons are distributed throughout the CNTs, leading to an unusual electric field between CNTs, the direction of which is opposite to that of the applied field. This unusual field response of CNT thin fil...

  16. Microstructure and strengthening parameters of ultra—thin hot strip of low carbon steel

    Institute of Scientific and Technical Information of China (English)

    HaoYu; YonglinKang; 等

    2002-01-01

    The microstructure and precipitation mechanism of ultra-thin hot 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 subastructures 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 invstigated.

  17. Study of carbon nitride compounds synthesised by co-implantation of 13C and 14N in copper at different temperatures

    International Nuclear Information System (INIS)

    Research highlights: → Simultaneous implantation of 13C and 14N in copper were performed to synthesise CNx compounds. → The formation of fullerene-like CNx compounds was highlighted by XPS and TEM. → Only about 20% of the implanted 14N atoms are contained in the FL CxNy structures. → The exceeding of implanted nitrogen precipitates in large N2 gas bubbles. → A growth model for the FL CxNy structures is proposed. - Abstract: Carbon nitride compounds have been synthesised in copper by simultaneous high fluence (1018 at. cm-2) implantation of 13C and 14N ions. During the implantation process, the substrate temperature was maintained at 25, 250, 350 or 450 deg. C. Depth profiles of 13C and 14N were determined using the non-resonant nuclear reactions (NRA) induced by a 1.05 MeV deuteron beam. The retained doses were deduced from NRA measurements and compared to the implanted fluence. The chemical bonds between carbon and nitrogen were studied as a function of depth and temperature by X-ray photoelectron spectroscopy (XPS). The curve fitting of C 1s and N 1s core level photoelectron spectra reveal different types of C-N bonds and show the signature of N2 molecules. The presence of nitrogen gas bubbles in copper was highlighted by mass spectroscopy. The structure of carbon nitride compounds was characterised by transmission electron microscopy (TEM). For that purpose, cross-sectional samples were prepared using a focused ion beam (FIB) system. TEM observations showed the presence of small amorphous carbon nitride 'nano-capsules' and large gas bubbles in copper. Based on our observations, we propose a model for the growth of these nano-objects. Finally, the mechanical properties of the implanted samples were investigated by nano-indentation.

  18. Tribological properties of ion beam deposited diamond-like carbon film on silicon nitride

    International Nuclear Information System (INIS)

    The present article reports on the physical characterization and tribological properties of diamond-like carbon (DLC) films deposited on structural Si3N4 substrates. The films were deposited by the direct ion beam deposition technique. The ion beam was produced by plasma discharge of pre-mixed methane and hydrogen gas in a Kaufman-type ion source. The deposited films were found to be amorphous and contained about 70% carbon and 30% hydrogen. The friction coefficient of an uncoated Si3N4 ball on a DLC coated Si3N4 disc starts at about 0.2, then decreases rapidly to 0.1-0.15 with increasing sliding distance. Increasing humidity results in a slight increase in friction coefficient, but a significant decrease in wear factor. The wear factor for the tests at ≅60% rh (relative humidity) are about an order of magnitude smaller than the tests at 3% rh. (orig.)

  19. Reactive Pulsed Laser Deposition of titanium nitride thin film: Optimization of process parameters using Secondary Ion Mass Spectrometry

    International Nuclear Information System (INIS)

    Reactive Pulsed Laser Deposition is a single step process wherein the ablated elemental metal reacts with a low pressure ambient gas to form a compound. We report here a Secondary Ion Mass Spectrometry based analytical methodology to conduct minimum number of experiments to arrive at optimal process parameters to obtain high quality TiN thin film. Quality of these films was confirmed by electron microscopic analysis. This methodology can be extended for optimization of other process parameters and materials.

  20. Corrosion resistance and electrical properties of carbon/chromium-titanium-nitride multilayer coatings on stainless steel

    Science.gov (United States)

    Feng, Kai; Li, Zhuguo; Lu, Fenggui; Huang, Jian; Cai, Xun; Wu, Yixiong

    2014-03-01

    High electrical conductivity and corrosion resistance are central to advances in wider application of metallic bipolar plates in polymer electrolyte membrane fuel cell (PEMFC). In this study, C/Cr-Ti-N multilayer coatings are deposited by physical vapor deposition and the effect of Cr:Ti ratio on the corrosion resistance and interfacial contact resistance (ICR) are systematically investigated. Scanning electron microscopy (SEM) result shows that the carbon layer is compact and uniform. Excellent corrosion resistance of 0.127 μA cm-2 current density at operating voltage in PEMFC cathode environment and low ICR of 2.03 mΩ-cm2 at compaction force of 150 N cm-2 are achieved when Cr:Ti ratio is 2:4 and 3:3, respectively. The significant enhancement in surface conductivity is probably because that the current comes from carbon paper is homogenized by two electrically conductive layers and flows to the passive film with much more contact area. After polarization, ICR increase to 3.07 mΩ-cm2 and 3.02 mΩ-cm2 in the simulated PEMFC cathode and anode environment, respectively. However, the Raman spectroscopy results disclose that the bonding type of top carbon film before and after polarization shows little difference. The results indicate that C/Cr-Ti-N multilayer coating with Cr:Ti ratio of 2:4 achieves the optimal composition.

  1. 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.

  2. 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

    2013-10-01

    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.

  3. Dense Z-pinches by carbon fiber pinch and by conductive thin film linear compression

    International Nuclear Information System (INIS)

    Dense Z-pinch plasmas are created by two different ways and are examined experimentally. A stable plasma column existing for about 20 ns has been created in the carbon fiber pinch driven by a pulsed power generator. Any significant differences in emitted soft X-ray intensity from the plasma are not observed between fiber pinches of carbon fiber with nickel or copper coating and without any coating material. Techninal difficulties in handling thin foil metal liner for linear compression experiments are overcome by proposing a conductive thin film deposited on the surface of discharge tube wall as a compression liner. Uniform cyclindrical compression of the thin film liner has been confirmed

  4. 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.

  5. 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

  6. Silicon nitride and intrinsic amorphous silicon double antireflection coatings for thin-film solar cells on foreign substrates

    International Nuclear Information System (INIS)

    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 cm2 aperture area on the graphite substrate. The optical properties of the SiNx/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 SiNx/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. • SiNx/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

  7. 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.

  8. PECVD synthesis, optical and mechanical properties of silicon carbon nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Ermakova, Evgeniya; Rumyantsev, Yurii [Nikolaev Institute of Inorganic Chemistry SB RAS, 630090 Novosibirsk (Russian Federation); Shugurov, Artur [Institute of Strength Physics and Materials Science SB RAS, 634021 Tomsk (Russian Federation); Panin, Alexey [Institute of Strength Physics and Materials Science SB RAS, 634021 Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Kosinova, Marina, E-mail: marina@niic.nsc.ru [Nikolaev Institute of Inorganic Chemistry SB RAS, 630090 Novosibirsk (Russian Federation)

    2015-06-01

    Highlights: • SiC{sub x}/SiC{sub x}N{sub y}/SiN{sub y} films were prepared by PECVD from trimethylphenylsilane and NH{sub 3} mixture. • By varying the ammonia dilution, films changing from SiC{sub x}-like to SiN{sub x}-like were synthesized. • The SiN{sub x}-like films deposited at elevated temperature under ammonia dilution possessed high transmittance, hardness of 23 GPa and Young's modulus of 180 GPa. - Abstract: SiC{sub x}N{sub y} thin films were synthesized at a temperature of 700 °C by the PECVD process, using trimethylphenylsilane C{sub 6}H{sub 5}Si(CH{sub 3}){sub 3} (TMPhS) and ammonia as a reactive mixture. The effect of NH{sub 3} dilution on the structure and chemical bonding of SiC{sub x}N{sub y} films was investigated by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, high-resolution transmission electron microscopy and energy-dispersive X-ray analysis. The influence of deposition conditions on the transmittance, the optical band gap, the hardness and the Young's modulus of SiC{sub x}N{sub y} films was studied. It was shown that the chemical composition and the functional properties of the films are governed by the initial pressure ratio of NH{sub 3} to TMPhS. The variation of the ratio enables the film of different composition to be deposited, e.g. SiC{sub x}, SiC{sub x}N{sub y} and SiN{sub y}. It was shown that the films deposited from a reactive mixture with the highest ammonia dilution had a transmittance comparable to that of SiO{sub 2} and hardness of 23 GPa.

  9. 氮化硅胶的制备及其吸收CO2性能的研究%Preparation of Nitrided Silica Gels and Their Absorption Performance for Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    原艳芬; 王树国; 李琳; 伍明

    2013-01-01

    Nitrided silica gels were prepared by two-synthetic method,and the effects of water amount and nitridation temperature on the synthesis of nitrided silica gels were investigated. Several technologies such as scanning electron microscopy,elemental analysis,X-ray photoelectron spectroscopy,29Si MAS NMR and so on were used to characterize the nitrided silica gels. The results showed that water amount was an important factor to the particle size of nitrided silica gels, and with the rising of nitridation temperature, the nitrogen content (mass fraction) of the nitrided silica gels increased. When the ammonia flowing rate was kept on 100 mL· min-1 under the nitridation temperature of 1000 ℃ for 20 h, nitrogen content of nitrided silica gels reached up to 9. 48%. In this paper,the nitrided silica gels were applied to the absorption of carbon dioxide. Compared to the non-nitrided silica gels,the nitrided silica gels exhibited the significantly higher absorption capacity,and the absorption amount of CO2 increased from 3. 08×10-4g ·g-1 to 6. 71×10-4g· g-1.%采用二次合成法制备了氮化硅胶,考察了水量、氮化温度对氮化硅胶合成的影响.采用扫描电镜、元素分析、X-射线光电子能谱和29Si MAS NMR等方法对氮化硅胶进行了表征.结果表明:水量是影响氮化硅胶粒径大小的重要因素;随着氮化温度的升高,氮化硅胶的氮含量(质量分数)增加;在氨气流速为100mL,min-1、氮化温度为1000℃、氮化时间为20 h的条件下,氮化硅胶的氮含量达9.48%.将氮化硅胶用于CO2的吸收,与未氮化的硅胶相比,氮化硅胶对CO2有明显的吸收能力,吸收量从3.08×10-4g,g-1提高到6.71×10-4g,g-1.

  10. Self-assembly graphitic carbon nitride quantum dots anchored on TiO2 nanotube arrays: An efficient heterojunction for pollutants degradation under solar light.

    Science.gov (United States)

    Su, Jingyang; Zhu, Lin; Geng, Ping; Chen, Guohua

    2016-10-01

    In this study, an efficient heterojunction was constructed by anchoring graphitic carbon nitride quantum dots onto TiO2 nanotube arrays through hydrothermal reaction strategy. The prepared graphitic carbon nitride quantum dots, which were prepared by solid-thermal reaction and sequential dialysis process, act as a sensitizer to enhance light absorption. Furthermore, it was demonstrated that the charge transfer and separation in the formed heterojunction were significantly improved compared with pristine TiO2. The prepared heterojunction was used as a photoanode, exhibiting much improved photoelectrochemical capability and excellent photo-stability under solar light illumination. The photoelectrocatalytic activities of prepared heterojunction were demonstrated by degradation of RhB and phenol in aqueous solution. The kinetic constants of RhB and phenol degradation using prepared photoelectrode are 2.4 times and 4.9 times higher than those of pristine TiO2, respectively. Moreover, hydroxyl radicals are demonstrated to be dominant active radicals during the pollutants degradation.

  11. Self-assembly graphitic carbon nitride quantum dots anchored on TiO2 nanotube arrays: An efficient heterojunction for pollutants degradation under solar light.

    Science.gov (United States)

    Su, Jingyang; Zhu, Lin; Geng, Ping; Chen, Guohua

    2016-10-01

    In this study, an efficient heterojunction was constructed by anchoring graphitic carbon nitride quantum dots onto TiO2 nanotube arrays through hydrothermal reaction strategy. The prepared graphitic carbon nitride quantum dots, which were prepared by solid-thermal reaction and sequential dialysis process, act as a sensitizer to enhance light absorption. Furthermore, it was demonstrated that the charge transfer and separation in the formed heterojunction were significantly improved compared with pristine TiO2. The prepared heterojunction was used as a photoanode, exhibiting much improved photoelectrochemical capability and excellent photo-stability under solar light illumination. The photoelectrocatalytic activities of prepared heterojunction were demonstrated by degradation of RhB and phenol in aqueous solution. The kinetic constants of RhB and phenol degradation using prepared photoelectrode are 2.4 times and 4.9 times higher than those of pristine TiO2, respectively. Moreover, hydroxyl radicals are demonstrated to be dominant active radicals during the pollutants degradation. PMID:27232727

  12. 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. PMID:27439985

  13. 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.

  14. Slow ramp voltage technique for investigation of breakdown voltage distribution in thin plasma-nitrided SiO sub 2 films

    Energy Technology Data Exchange (ETDEWEB)

    Slavcheva, G. (Inst. of Solid State Physics, Bulgarian Academy of Sciences, Sofia (Bulgaria))

    1990-11-01

    The slow ramp current-voltage characteristics of NH{sub 3}-plasma-nitrided samples of thermally grown chlorine SiO{sub 2}, d=200-350 A, have been measured and the breakdown voltage statistics determined. The characteristics of the breakdown voltage distribution of a double layer and completely nitrided samples have been derived. Evidence is given that the dominant conductivity mechanism is contact-limited Fowler-Nordheim emission. (orig.).

  15. Microfabrication, separations, and detection by mass spectrometry on ultrathin-layer chromatography plates prepared via the low-pressure chemical vapor deposition of silicon nitride onto carbon nanotube templates.

    Science.gov (United States)

    Kanyal, Supriya S; Häbe, Tim T; Cushman, Cody V; Dhunna, Manan; Roychowdhury, Tuhin; Farnsworth, Paul B; Morlock, Gertrud E; Linford, Matthew R

    2015-07-24

    Microfabrication of ultrathin-layer chromatography (UTLC) plates via conformal deposition of silicon nitride by low-pressure chemical vapor deposition onto patterned carbon nanotube (CNT) scaffolds was demonstrated. After removal of the CNTs and hydroxylation, the resulting UTLC phase showed no expansion or distortion of their microfeatures and the absence/reduction of remaining nitrogenic species. Developing time of a mixture of lipophilic dyes on this UTLC plates was 86% shorter than on high-performance thin-layer chromatography (HPTLC) plates. A water-soluble food dye mixture was also separated resulting in low band broadening and reduced developing time compared to HPTLC. For the latter example, mobile phase optimization on a single UTLC plate consisted of 14 developments with different mobile phases, each preceded by a plate prewashing step. The same plate was again reused for additional 11 separations under varying conditions resulting in a development procedure with a mean separation efficiency of 233,000theoretical plates/m and a reduced mobile phase consumption of only 400μL. This repeated use proved the physical robustness of the ultrathin layer and its resistance to damage. The layer was highly suited for hyphenation to ambient mass spectrometry, including desorption electrospray ionization (DESI) mass spectrometry imaging and direct analysis in real time (DART) mass spectrometry.

  16. 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.

  17. Role of interfacial carbon layer in the thermal diffusivity/conductivity of silicon carbide fiber-reinforced reaction-bonded silicon nitride matrix composites

    Science.gov (United States)

    Bhatt, Hemanshu; Donaldson, Kimberly Y.; Hasselman, D. P. H.; Bhatt, Ramakrishna T.

    1992-01-01

    Experiments were carried out on samples of reaction-bonded silicon nitride uniaxially reinforced by SiC monofilaments with and without a 3-micron-thick carbon-rich coating. It is found that a combination of a carbon coatings on the fibers and an interfacial gap due to the thermal expansion mismatch in the composite can significantly (by a factor of 2) lower the effective thermal diffusivity in the direction transverse to the fiber. At atmospheric pressure, gaseous conduction across the interfacial gap makes a significant contribution to the heat transfer across the interface, indicated by significantly lower values of the effective thermal diffusivity under vacuum than in nitrogen or helium at atmospheric pressure.

  18. Humidity Sensor Based on Multi-Walled Carbon Nanotube Thin Films

    OpenAIRE

    Cao, C. L.; Hu, C. G.; Fang, L.; Wang, S. X.; Y. S. TIAN; Pan, C. Y.

    2011-01-01

    The properties of the humidity sensors made of chemically treated and untreated multi-walled carbon nanotube (MWCNT) thin films are investigated systematically. It shows that both the chemically treated and untreated MWCNT thin films demonstrate humidity sensitive properties, but the former have stronger sensitivity than the latter. In the range of 11%–98% relative humidity (RH), the resistances of the chemically treated and untreated MWCNT humidity sensors increase 120% and 28%, respectively...

  19. 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.

  20. Establishment of carbon atomic composition analysis by proton backscattering

    CERN Document Server

    Gotoh, Y; Fujii, R; Tsuji, H; Ishikawa, J

    2003-01-01

    Transition metal nitride and carbide thin films are expected to serve as a cathode material for cold cathodes. Since the atomic compositions of nitrogen and carbon will strongly affect the properties of the electron emission surface, quantification of these elements are necessary. In this report, we tried to quantify the carbon atomic compositions in the transition metal carbide thin films by resonant nuclear reaction of sup 1 sup 2 C(p, p) sup 1 sup 2 C.

  1. Visible photoluminescence from ZnO/diamond-like carbon thin films

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-chun; LI Qing-shan; DONG Yan-feng; MA Zi-xia

    2012-01-01

    ZnO/diamond-like carbon (DLC) thin films are deposited by pulsed laser deposition (PLD) on Si (111) wafer.Visible room-temperature photoluminescence (PL) is observed from ZnO/DLC thin films by fluorescence spectrophotometer.The Gaussian curve fitting of PL spectra reveals that the broadband visible emission contains three components with λ=508 nm,554 nm and 698 nm.The origin and possible mechanism of the visible PL are discussed,and they can be attributed to the PL recombination of ZnO and DLC thin films.

  2. 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

  3. 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.

  4. Assessment of wall-thinning in carbon steel pipe by using laser-generated guided wave

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do Yong; Cho, Youn Ho; Lee, Joon Hyun [Pusan National University, School of Mechanical Engineering, Busan (Korea, Republic of)

    2010-10-15

    The objective of this research is to estimate the crack location and size of a carbon steel pipe by using a laser ultrasound guided wave for the wall thinning evaluation of an elbow. The wall thinning of the carbon steel pipe is one of the most serious problems in nuclear power plants, especially the wall thinning of the carbon steel elbow caused by Flow-Accelerated Corrosion (FAC). Therefore, a non-destructive inspection method of elbow is essential for the nuclear power plants to operate safely. The specimens used in this study were carbon steel elbows, which represented the main elements of real nuclear power plants. The shape of the wall thinning was an oval with a width of 120mm, a length of 80mm, and a depth of 5mm. The L(0,1) and L(0,2) modes variation of the ultrasound guided wave signal is obtained from the response of the laser generation/air-coupled detection ultrasonic hybrid system represent the characteristics of the defect. The trends of these characteristics and signal processing were use dto estimate the size and location of wall thinning

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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

  11. 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

  12. 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

  13. Detection of wall thinning of carbon steel pipe covered with insulation using Pulsed Eddy Current technique

    International Nuclear Information System (INIS)

    The test sample is a ferromagnetic carbon steel pipe having different thickness, covered with a 10 cm plastic insulation laminated by 0.4 mm Al plate to simulate the pipelines in NPPs. The PEC Probe used for the wall thinning detection consists of an excitation coil and a Hall sensor. The excitation coils in the probe is driven by a rectangular bipolar current pulse and the Hall-sensor will detects the resultant field. The Hall sensor output is considered as PEC signal. Results shows that the PEC system can detect wall thinning in an insulated pipeline of the NPPs. Local wall thinning in pipelines affects the structural integrity of industries like nuclear power plants (NPPs). In the present study a pulsed eddy current (PEC) technology to detect the wall thing of carbon steel pipe covered with insulation is developed

  14. Transmission of fast H3+ molecules through thin carbon foils

    International Nuclear Information System (INIS)

    Observed for the first time is the transmission of H3+ molecules (2.4 MeV) through carbon foils (2 - 7μg/cm2). The thickness dependence of the yield follows a single decreasing exponential function with a unity coefficient which is expected for H3+ transmitted with their original electrons

  15. 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.

  16. A facile microwave-assisted fabrication of fluorescent carbon nitride quantum dots and their application in the detection of mercury ions.

    Science.gov (United States)

    Cao, Xiaotong; Ma, Jie; Lin, Yanping; Yao, Bixia; Li, Feiming; Weng, Wen; Lin, Xiuchun

    2015-12-01

    A facile microwave-assisted solvothermal method was used to prepare fluorescent carbon nitride quantum dots (CNQDs) using oleic acid as the reaction media at moderate reaction temperature in a short time (5 min). Citric acid monohydrate and urea were used as the precursors. The as-prepared CNQDs were characterized by multiple analytical techniques. The CNQDs exhibited an uncommon excitation wavelength-dependent fluorescence with two maximum emission peaks at 450 and 540 nm. The CNQDs with a quantum yield of 27.1% could serve as an effective fluorescent sensing platform for label-free sensitive detection of Hg(2+) ions with a detection limit of 0.14 μM. This method was also applied to the detection of Hg(2+) ions in tap water samples.

  17. Polyaniline/Carbon Nitride Nanosheets Composite Hydrogel: A Separation-Free and High-Efficient Photocatalyst with 3D Hierarchical Structure.

    Science.gov (United States)

    Jiang, Wenjun; Luo, Wenjiao; Zong, Ruilong; Yao, Wenqing; Li, Zhanping; Zhu, Yongfa

    2016-08-01

    A polyaniline (PANI)/carbon nitride nanosheets (CNNS) composite hydrogel with 3D hierarchical nanostructure is synthesized via in situ polymerization. The 3D hierarchical structure is robust and stable, making the composite hydrogel separation-free and easy to recycling. It is highly excellent in removing organic pollutant for PANI/CNNS composite hydrogel on account of the cooperation of adsorptive preconcentration and the following photocatalytic oxidation. Pollutants are first adsorbed and concentrated into the 3D hierarchical nanostructure of the composite hydrogel. Then the pollutants are in situ oxidized via photocatalysis. The promoted photocatalytic performance can be mainly ascribed to the outstanding interfacial charge separation and photoelectrochemical performance. A new idea of the construction of 3D hierarchical photocatalysts is presented, which can be applied in the sustainability field.

  18. Synthesis and characterization of an A2BC type phthalocyanine and its visible-light-responsive photocatalytic H2 production performance on graphitic carbon nitride.

    Science.gov (United States)

    Guo, Yingying; Song, Shuaishuai; Zheng, Ya; Li, Renjie; Peng, Tianyou

    2016-09-28

    A highly asymmetric A2BC type zinc phthalocyanine (Zn-di-PcNcTh) has been designed and synthesized. The Zn-di-PcNcTh used a π electron rich thiophene ring in place of the benzenoid rings of phthalocyanine which acted as an electron donor, diphenylphenoxy substituents to retard aggregation and a carboxyl-naphthalene unit as an electron acceptor. The asymmetric phthalocyanine shows a strongly split Q-band and wide spectral absorption in the visible/near-IR light region, which can extend the spectral response region of graphitic carbon nitride (g-C3N4) from ∼450 nm to more than 800 nm. By using it as a sensitizer of 1.0 wt% Pt-loaded graphitic carbon nitride (g-C3N4), the experimental results indicate that Zn-di-PcNcTh-Pt/g-C3N4 shows a H2 production efficiency of 249 μmol h(-1) with an impressive turnover number (TON) of 9960.8 h(-1) under visible light (λ≥ 420 nm) irradiation, much higher than that of pristine Pt/g-C3N4. Owing to the introduction of a highly bathochromic shift of 3,4-dicyanothiophene and the valuable "push-pull" effect from the thiophene (electron donor) to the carboxyl-naphthalene (electron acceptor) unit, Zn-di-PcNcTh/g-C3N4 gives an extremely high apparent quantum yield (AQY) of 2.44%, 3.05%, and 1.53% under 700, 730, and 800 nm monochromatic light irradiation, respectively, under optimized photocatalytic conditions.

  19. 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.

  20. 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. PMID:27337491