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Sample records for inches high doped

  1. Recent developments in high charge state heavy ion beams at the LBL 88-inch Cyclotron

    International Nuclear Information System (INIS)

    Gough, R.A.; Clark, D.J.; Glasgow, L.R.

    1978-01-01

    Recent advances in design and operation of the internal PIG sources at the LBL 88-Inch Cyclotron have led to the development of high charge state (0.4 16 O 8+ . Total external intensities of these beams range from 10 12 particles/s for 6 Li 3+ to 0.1 particles/s for 16 O 8+ . Techniques have been developed for routine tune-out of the low intensity beams. These include use of model beams and reliance on the large systematic data base of cyclotron parameters which has been developed over many years of operation. Techniques for delivery of these weak beams to the experimental target areas are presented. Source design and operation, including special problems associated with Li, Be, and B beams are discussed

  2. High-Volume Production of Lightweight, Multi-Junction Solar Cells Using 6-inch GaAs, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In the proposed Phase II program, we will transition MicroLink's 6-inch epitaxial lift-off (ELO) solar cell fabrication process into a manufacturing platform capable...

  3. Development of a 55 μm pitch 8 inch CMOS image sensor for the high resolution NDT application

    Science.gov (United States)

    Kim, M. S.; Kim, G.; Cho, G.; Kim, D.

    2016-11-01

    A CMOS image sensor (CIS) with a large area for the high resolution X-ray imaging was designed. The sensor has an active area of 125 × 125 mm2 comprised with 2304 × 2304 pixels and a pixel size of 55 × 55 μm2. First batch samples were fabricated by using an 8 inch silicon CMOS image sensor process with a stitching method. In order to evaluate the performance of the first batch samples, the electro-optical test and the X-ray test after coupling with an image intensifier screen were performed. The primary results showed that the performance of the manufactured sensors was limited by a large stray capacitance from the long path length between the analog multiplexer on the chip and the bank ADC on the data acquisition board. The measured speed and dynamic range were limited up to 12 frame per sec and 55 dB respectively, but other parameters such as the MTF, NNPS and DQE showed a good result as designed. Based on this study, the new X-ray CIS with ~ 50 μm pitch and ~ 150 cm2 active area are going to be designed for the high resolution X-ray NDT equipment for semiconductor and PCB inspections etc.

  4. High temperature superconductors at optimal doping

    Directory of Open Access Journals (Sweden)

    W. E. Pickett

    2006-09-01

    Full Text Available   Intensive study of the high temperature superconductors has been ongoing for two decades. A great deal of this effort has been devoted to the underdoped regime, where the new and difficult physics of the doped Mott insulator has met extra complications including bilayer coupling/splitting, shadow bands, and hot spots. While these complications continue to unfold, in this short overview the focus is moved to the region of actual high-Tc, that of optimal doping. The focus here also is not on the superconducting state itself, but primarily on the characteristics of the normal state from which the superconducting instability arises, and even these can be given only a broad-brush description. A reminder is given of two issues,(i why the “optimal Tc” varies,for n-layered systems it increases for n up to 3, then decreases for a given n, Tc increases according to the ‘basis’ atom in the order Bi, Tl, Hg (ii how does pressure, or a particular uniaxial strain, increase Tc when the zero-strain system is already optimally doped?

  5. Replacement of a photomultiplier tube in a 2-inch thallium-doped sodium iodide gamma spectrometer with silicon photomultipliers and a light guide

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Kyu; Kim, Hyoung Taek; Kim, Jong Yul [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); and others

    2015-06-15

    The thallium-doped sodium iodide [NaI(Tl)] scintillation detector is preferred as a gamma spectrometer in many fields because of its general advantages. A silicon photomultiplier (SiPM) has recently been developed and its application area has been expanded as an alternative to photomultiplier tubes (PMTs). It has merits such as a low operating voltage, compact size, cheap production cost, and magnetic resonance compatibility. In this study, an array of SiPMs is used to develop an NaI(Tl) gamma spectrometer. To maintain detection efficiency, a commercial NaI(Tl) 2′ X 2′ scintillator is used, and a light guide is used for the transport and collection of generated photons from the scintillator to the SiPMs without loss. The test light guides were fabricated with polymethyl methacrylate and reflective materials. The gamma spectrometer systems were set up and included light guides. Through a series of measurements, the characteristics of the light guides and the proposed gamma spectrometer were evaluated. Simulation of the light collection was accomplished using the DETECT 97 code (A. Levin, E. Hoskinson, and C. Moison, University of Michigan, USA) to analyze the measurement results. The system, which included SiPMs and the light guide, achieved 14.11% full width at half maximum energy resolution at 662 keV.

  6. Replacement of a photomultiplier tube in a 2-inch thallium-doped sodium iodide gamma spectrometer with silicon photomultipliers and a light guide

    Directory of Open Access Journals (Sweden)

    Chankyu Kim

    2015-06-01

    Full Text Available The thallium-doped sodium iodide [NaI(Tl] scintillation detector is preferred as a gamma spectrometer in many fields because of its general advantages. A silicon photomultiplier (SiPM has recently been developed and its application area has been expanded as an alternative to photomultiplier tubes (PMTs. It has merits such as a low operating voltage, compact size, cheap production cost, and magnetic resonance compatibility. In this study, an array of SiPMs is used to develop an NaI(Tl gamma spectrometer. To maintain detection efficiency, a commercial NaI(Tl 2′ × 2′ scintillator is used, and a light guide is used for the transport and collection of generated photons from the scintillator to the SiPMs without loss. The test light guides were fabricated with polymethyl methacrylate and reflective materials. The gamma spectrometer systems were set up and included light guides. Through a series of measurements, the characteristics of the light guides and the proposed gamma spectrometer were evaluated. Simulation of the light collection was accomplished using the DETECT 97 code (A. Levin, E. Hoskinson, and C. Moison, University of Michigan, USA to analyze the measurement results. The system, which included SiPMs and the light guide, achieved 14.11% full width at half maximum energy resolution at 662 keV.

  7. PULSION registered HP: Tunable, High Productivity Plasma Doping

    International Nuclear Information System (INIS)

    Felch, S. B.; Torregrosa, F.; Etienne, H.; Spiegel, Y.; Roux, L.; Turnbaugh, D.

    2011-01-01

    Plasma doping has been explored for many implant applications for over two decades and is now being used in semiconductor manufacturing for two applications: DRAM polysilicon counter-doping and contact doping. The PULSION HP is a new plasma doping tool developed by Ion Beam Services for high-volume production that enables customer control of the dominant mechanism--deposition, implant, or etch. The key features of this tool are a proprietary, remote RF plasma source that enables a high density plasma with low chamber pressure, resulting in a wide process space, and special chamber and wafer electrode designs that optimize doping uniformity.

  8. Highly doped layer for tunnel junctions in solar cells

    Science.gov (United States)

    Fetzer, Christopher M.

    2017-08-01

    A highly doped layer for interconnecting tunnel junctions in multijunction solar cells is presented. The highly doped layer is a delta doped layer in one or both layers of a tunnel diode junction used to connect two or more p-on-n or n-on-p solar cells in a multijunction solar cell. A delta doped layer is made by interrupting the epitaxial growth of one of the layers of the tunnel diode, depositing a delta dopant at a concentration substantially greater than the concentration used in growing the layer of the tunnel diode, and then continuing to epitaxially grow the remaining tunnel diode.

  9. Ten inch Planar Optic Display

    Energy Technology Data Exchange (ETDEWEB)

    Beiser, L. [Beiser (Leo) Inc., Flushing, NY (United States); Veligdan, J. [Brookhaven National Lab., Upton, NY (United States)

    1996-04-01

    A Planar Optic Display (POD) is being built and tested for suitability as a high brightness replacement for the cathode ray tube, (CRT). The POD display technology utilizes a laminated optical waveguide structure which allows a projection type of display to be constructed in a thin (I to 2 inch) housing. Inherent in the optical waveguide is a black cladding matrix which gives the display a black appearance leading to very high contrast. A Digital Micromirror Device, (DMD) from Texas Instruments is used to create video images in conjunction with a 100 milliwatt green solid state laser. An anamorphic optical system is used to inject light into the POD to form a stigmatic image. In addition to the design of the POD screen, we discuss: image formation, image projection, and optical design constraints.

  10. 10-inch planar optic display

    Science.gov (United States)

    Beiser, Leo; Veligdan, James T.

    1996-05-01

    A planar optic display (POD) is being built and tested for suitability as a high brightness replacement for the cathode ray tube, (CRT). The POD display technology utilizes a laminated optical waveguide structure which allows a projection type of display to be constructed in a thin (1 to 2 inch) housing. Inherent in the optical waveguide is a black cladding matrix which gives the display a black appearance leading to very high contrast. A digital micromirror device, (DMD) from Texas Instruments is used to create video images in conjunction with a 100 milliwatt green solid state laser. An anamorphic optical system is used to inject light into the POD to form a stigmatic image. In addition to the design of the POD screen, we discuss: image formation, image projection, and optical design constraints.

  11. Spectroscopic properties of highly Nd-doped lead phosphate glass

    Energy Technology Data Exchange (ETDEWEB)

    Novais, A.L.F. [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil); Dantas, N.O. [Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Guedes, I. [Departamento de Física, Universidade Federal do Ceará, Campus do PICI, Caixa Postal 6030, 60455-760 Fortaleza, CE (Brazil); Vermelho, M.V.D., E-mail: vermelho@fis.ufal.br [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil)

    2015-11-05

    The spectroscopic characteristics of highly Nd{sup 3+}-doped lead phosphate glasses (xNd:Pb{sub 3}(PO{sub 4}){sub 2}) have been investigated. The X-ray spectra show that the matrices are glassy up to 25 wt% of Nd{sup 3+} doping. From the Judd–Ofelt analysis we observe that while the Ω{sub (2)} parameter remains constant indicating that the 4f{sup N} and 4f{sup N−1}5 d{sup 1} configurations are not affected by the Nd{sup 3+} doping, the behavior of both Ω{sub (4)} and Ω{sub (6)} changes for 15 wt% of Nd{sup 3+} doping. The reduction of the Ω{sub (6)} parameter is related to the increase of the covalence bonding between the ligands and the Nd{sup 3+} ions. At this particular concentration, the radiative lifetime has a four-fold enhancement. Such behaviors are likely to be related to a modification in the glass structure for high Nd{sup 3+} concentrations. - Graphical abstract: Highly doped lead-phosphate glass matrix, with nominal concentration of up to 25 wt%, maintain the spectroscopic properties without deterioration. The analysis concerning the point of view of Nd{sup 3+} ions showed that high concentrations only affects the rare earth electronic charge density distribution. - Highlights: • Spectroscopic characterization of Nd{sub 2}O{sub 3} highly doped lead phosphate glasses. • Phosphate glass doped with Nd{sup 3+} for applications in photonic devices. • Judd–Ofelt analysis in phosphate glasses doped with Neodymium.

  12. Iron solubility in highly boron-doped silicon

    International Nuclear Information System (INIS)

    McHugo, S.A.; McDonald, R.J.; Smith, A.R.; Hurley, D.L.; Weber, E.R.

    1998-01-01

    We have directly measured the solubility of iron in high and low boron-doped silicon using instrumental neutron activation analysis. Iron solubilities were measured at 800, 900, 1000, and 1100thinsp degree C in silicon doped with either 1.5x10 19 or 6.5x10 14 thinspboronthinspatoms/cm 3 . We have measured a greater iron solubility in high boron-doped silicon as compared to low boron-doped silicon, however, the degree of enhancement is lower than anticipated at temperatures >800thinsp degree C. The decreased enhancement is explained by a shift in the iron donor energy level towards the valence band at elevated temperatures. Based on this data, we have calculated the position of the iron donor level in the silicon band gap at elevated temperatures. We incorporate the iron energy level shift in calculations of iron solubility in silicon over a wide range of temperatures and boron-doping levels, providing a means to accurately predict iron segregation between high and low boron-doped silicon. copyright 1998 American Institute of Physics

  13. An in situ vapour phase hydrothermal surface doping approach for fabrication of high performance Co3O4 electrocatalysts with an exceptionally high S-doped active surface.

    Science.gov (United States)

    Tan, Zhijin; Liu, Porun; Zhang, Haimin; Wang, Yun; Al-Mamun, Mohammad; Yang, Hua Gui; Wang, Dan; Tang, Zhiyong; Zhao, Huijun

    2015-04-04

    A facile in situ vapour phase hydrothermal (VPH) surface doping approach has been developed for fabrication of high performance S-doped Co3O4 electrocatalysts with an unprecedentedly high surface S content (>47%). The demonstrated VPH doping approach could be useful for enrichment of surface active sites for other metal oxide electrocatalysts.

  14. Heavy doping effects in high efficiency silicon solar cells

    Science.gov (United States)

    Lindholm, F. A.; Neugroschel, A.

    1986-01-01

    The temperature dependence of the emitter saturation current for bipolar devices was studied by varying the surface recombination velocity at the emitter surface. From this dependence, the value was derived for bandgap narrowing that is in better agreement with other determinations that were obtained from the temperature dependence measure on devices with ohmic contacts. Results of the first direct measurement of the minority-carrier transit time in a transparent heavily doped emitter layer were reported. The value was obtained by a high-frequency conductance method recently developed and used for doped Si. Experimental evidence is presented for significantly greater charge storage in highly excited silicon near room temperature than conventional theory would predict. These data are compared with various data for delta E sub G in heavily doped silicon.

  15. Plasmonic bio-sensing based on highly doped semiconductors

    Science.gov (United States)

    Taliercio, Thierry; Gonzalez-Posada Flores, Fernando; Barho, Franziska B.; Milla-Rodrigo, María. José; Bomers, Mario; Cerutti, Laurent; Tournié, Eric

    2017-08-01

    Highly doped semiconductors, such as Si-doped InAsSb, are promising alternative materials for plasmonic application in the mid-infrared spectral range because they benefit from compatibility with silicon technology, from low losses and from tunable permittivity. We propose to detail what are the main advantages of InAsSb:Si compared to noble metals and how they can be used for bio-sensing applications. We demonstrate that 1-D InAsSb:Si ribbon arrays outperform 1- D gold ribbon arrays because of the latter uses little the lightning rod effect. In the case of 2-D nano-antenna arrays, it is possible to exploit a strong polarization dependent resonance to cover a large spectral range for sensing. Finally, we demonstrate that the highly doped semiconductor 1-D ribbon arrays and 2-D nano-antenna arrays allow surface plasmon resonance (SPR) sensing and surface-enhanced infrared absorption (SEIRA).

  16. 8-inch IBM floppy disk

    CERN Multimedia

    1971-01-01

    The 8-inch floppy disk was a magnetic storage disk for the data introduced commercially by IBM in 1971. It was designed by an IBM team as an inexpensive way to load data into the IBM System / 370. Plus it was a read-only bare disk containing 80 KB of data. The first read-write version was introduced in 1972 by Memorex and could contain 175 KB on 50 tracks (with 8 sectors per track). Other improvements have led to various coatings and increased capacities. Finally, it was surpassed by the mini diskette of 5.25 inches introduced in 1976.

  17. Comparative study of highly dense aluminium- and gallium-doped ...

    Indian Academy of Sciences (India)

    Administrator

    cause of their optoelectronic properties in addition to low cost, high stability and excellent surface uniformity (low roughness). Doping zinc oxide with some elements like aluminium, gallium, boron, niobium and indium has a great impact for having enhancements of its optical and electrical properties. Aluminium and gallium ...

  18. The Prevalence and Covariates of Potential Doping Behavior in Kickboxing; Analysis Among High-Level Athletes

    Directory of Open Access Journals (Sweden)

    Sekulic Damir

    2017-10-01

    Full Text Available The official reports on doping behavior in kickboxing are alarming, but there have been no empirical studies that examined this problem directly. The aim of this study was to investigate the prevalence, gender differences and covariates of potential-doping-behavior, in kickboxing athletes. A total of 130 high-level kickboxing athletes (92 males, 21.37 ± 4.83 years of age, 8.39 ± 5.73 years of training experience; 38 women, 20.31 ± 2.94 years of age; 9.84 ± 4.74 years of training experience completed questionnaires to study covariates and potential-doping behavior. The covariates were: sport factors (i.e. experience, success, doping-related factors (i.e. opinion about penalties for doping users, number of doping testing, potential-doping-behavior, etc., sociodemographic variables, task- and ego-motivation, knowledge on sports nutrition, and knowledge on doping. Gender-based differences were established by independent t-tests, and the Mann-Whitney test. Multinomial logistic regression analyses were performed to define the relationships between covariates and a tendency toward potential-doping behavior (positive tendency – neutral – negative tendency. The potential-doping behavior was higher in those athletes who perceived kickboxing as doping contaminated sport. The more experienced kickboxers were associated with positive intention toward potential-doping behavior. Positive intention toward potential-doping behavior was lower in those who had better knowledge on sports nutrition. The task- and ego-motivation were not associated to potential-doping behavior. Because of the high potential-doping-behavior (less than 50% of athletes showed a negative tendency toward doping, and similar prevalence of potential-doping behavior between genders, this study highlights the necessity of a systematic anti-doping campaign in kickboxing. Future studies should investigate motivational variables as being potentially related to doping behavior in younger

  19. Highly n -doped graphene generated through intercalated terbium atoms

    Science.gov (United States)

    Daukiya, L.; Nair, M. N.; Hajjar-Garreau, S.; Vonau, F.; Aubel, D.; Bubendorff, J. L.; Cranney, M.; Denys, E.; Florentin, A.; Reiter, G.; Simon, L.

    2018-01-01

    We obtained highly n -type doped graphene by intercalating terbium atoms between graphene and SiC(0001) through appropriate annealing in ultrahigh vacuum. After terbium intercalation angle-resolved-photoelectron spectroscopy (ARPES) showed a drastic change in the band structure around the K points of the Brillouin zone: the well-known conical dispersion band of a graphene monolayer was superposed by a second conical dispersion band of a graphene monolayer with an electron density reaching 1015cm-2 . In addition, we demonstrate that atom intercalation proceeds either below the buffer layer or between the buffer layer and the monolayer graphene. The intercalation of terbium below a pure buffer layer led to the formation of a highly n -doped graphene monolayer decoupled from the SiC substrate, as evidenced by ARPES and x-ray photoelectron spectroscopy measurements. The band structure of this highly n -doped monolayer graphene showed a kink (a deviation from the linear dispersion of the Dirac cone), which has been associated with an electron-phonon coupling constant one order of magnitude larger than those usually obtained for graphene with intercalated alkali metals.

  20. High gain photoconductive semiconductor switch having tailored doping profile zones

    Science.gov (United States)

    Baca, Albert G.; Loubriel, Guillermo M.; Mar, Alan; Zutavern, Fred J; Hjalmarson, Harold P.; Allerman, Andrew A.; Zipperian, Thomas E.; O'Malley, Martin W.; Helgeson, Wesley D.; Denison, Gary J.; Brown, Darwin J.; Sullivan, Charles T.; Hou, Hong Q.

    2001-01-01

    A photoconductive semiconductor switch with tailored doping profile zones beneath and extending laterally from the electrical contacts to the device. The zones are of sufficient depth and lateral extent to isolate the contacts from damage caused by the high current filaments that are created in the device when it is turned on. The zones may be formed by etching depressions into the substrate, then conducting epitaxial regrowth in the depressions with material of the desired doping profile. They may be formed by surface epitaxy. They may also be formed by deep diffusion processes. The zones act to reduce the energy density at the contacts by suppressing collective impact ionization and formation of filaments near the contact and by reducing current intensity at the contact through enhanced current spreading within the zones.

  1. Highly luminescent Eu{sup 3+}-doped benzenetricarboxylate based materials

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Ivan G.N. [Departamento de Química Fundamental, Instituto de Química da Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-900, SP (Brazil); Mustafa, Danilo, E-mail: dmustafa@iq.usp.br [Departamento de Química Fundamental, Instituto de Química da Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-900, SP (Brazil); Andreoli, Bruno [Departamento de Química Fundamental, Instituto de Química da Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-900, SP (Brazil); Felinto, Maria C.F.C. [Centro de Química do Meio Ambiente, Instituto de Pesquisas Energéticas e Nucleares, Av. Prof. Lineu Prestes 2242, São Paulo 05508-000, SP (Brazil); Malta, Oscar L. [Departamento de Química Fundamental, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235, Recife 50670-90, PE (Brazil); Brito, Hermi F., E-mail: hefbrito@iq.usp.br [Departamento de Química Fundamental, Instituto de Química da Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-900, SP (Brazil)

    2016-02-15

    [RE(TMA)] anhydrous complexes (RE{sup 3+}: Y, Gd and Lu) present high red emission intensity with a quantum efficiency (~45%) for the [Y(TMA):Eu{sup 3+}] complexes, due to the absence of non-radioactive decay pathways mediated by water molecules. The complexes were prepared in mild conditions. All the compounds are crystalline and thermostable up to 460 °C. Phosphorescence data of the complexes with Y, Gd and Lu show that the T{sub 1} state of the TMA{sup 3−} anion has energy higher than the {sup 5}D{sub 0} emitting level of the Eu{sup 3+} ion, indicating that the ligand can act as an intramolecular energy sensitizer. The photoluminescence properties of the doped materials were studied based on the excitation and emission spectra and luminescence decay curves. The experimental intensity parameters (Ω{sub λ}), lifetimes (τ), radiative (A{sub rad}) and non-radiative (A{sub nrad}) decay rates were determined and discussed. - Highlights: • Highly luminescent Europium doped anhydrous complexes. • Efficient monochromatic red light conversion molecular devices (LCMDs). • High emission quantum efficiencies.

  2. Development of 52 inches last stage blade for steam turbines

    International Nuclear Information System (INIS)

    Suzuki, Atsuhide; Hisa, Shoichi; Nagao, Shinichiro; Ogata, Hisao

    1986-01-01

    The last stage blades of steam turbines are the important component controlling the power output and performance of plants. In order to realize a unit of large capacity and high efficiency, the proper exhaust area and the last stage blades having good performance are indispensable. Toshiba Corp. has completed the development of the 52 inch last stage blades for 1500 and 1800 rpm steam turbines. The 52 inch last stage blades are the longest in the world, which have the annular exhaust area nearly 1.5 times as much as that of 41 inch blades used for 1100 MW, 1500 rpm turbines in nuclear power stations. By adopting these 52 inch blades, the large capacity nuclear power plants up to 1800 MW can be economically constructed, the rate of heat consumption of 1350 MW plants is improved by 3 ∼ 4 % as compared with 41 inch blades, and in the plants up to 1100 MW, LP turbines can be reduced from three sets to two. The features of 52 inch blades, the flow pattern and blade form design, the structural strength analysis and the erosion withstanding property, and the verification by the rotation test of the actual blades, the performance test using a test turbine, the vibration analysis of the actually loaded blades and the analysis of wet steam behavior are reported. (Kako, I.)

  3. Heavily doped silicon electrode for dielectrophoresis in high conductivity media

    Science.gov (United States)

    Zhu, Xiongfeng; Tung, Kuan-Wen; Chiou, Pei-Yu

    2017-10-01

    A hemispherically shaped, heavily doped (N++) silicon electrode is proposed to overcome the challenges of dielectrophoretic (DEP) manipulation using a conventional metal electrode operating in high conductivity media. An N++ electrode decouples the strong electric field region from the electrode interface and provides a large interface capacitance to prevent surface charging in high conductivity media, thereby effectively suppressing electrochemical reactions. Compared to a conventional metal electrode, an N++ electrode can provide 3 times higher threshold voltage and a corresponding 9-fold enhancement of maximum DEP force in 1× phosphate-buffered saline buffer with an electrical conductivity of 1 S/m. Furthermore, an N++ silicon electrode has excellent thermal conductivity and low electrical impedance, ideal for powering massively parallel DEP manipulation in high conductivity media across a large area.

  4. High quantum efficiency of depth grade doping negative-electron-affinity GaN photocathode

    Science.gov (United States)

    Guo, Xiangyang; Wang, Xiaohui; Chang, Benkang; Zhang, Yijun; Gao, Pin

    2010-08-01

    A depth grade doping sample gallium nitride (GaN) photocathode was designed to obtain an extremely high quantum efficiency (QE). Two other uniform doping samples were prepared in the same procedure as contrast. The calibrated QE curves were achieved; by comparing theoretical calculated values with the experimental QE plots, the escape probability and diffusion length were fitted. The QE value of gradient doping sample is as high as 68.7% at 5.17 eV; the diffusion length of gradient doping sample is fitted to be 250 nm which is much higher than uniform doping samples. That explains why depth-grade-doping can improve the QE of GaN photocathode significantly.

  5. Highly doped InP as a low loss plasmonic material for mid-IR region

    DEFF Research Database (Denmark)

    Panah, Mohammad Esmail Aryaee; Takayama, Osamu; Morozov, S. V.

    2016-01-01

    We study plasmonic properties of highly doped InP in the mid-infrared (IR) range. InP was grown by metal-organic vapor phase epitaxy (MOVPE) with the growth conditions optimized to achieve high free electron concentrations by doping with silicon. The permittivity of the grown material was found b...

  6. Tm3+-doped CW fiber laser based on a highly GeO2-doped dispersion-shifted fiber

    OpenAIRE

    Dvoyrin, Vladislav; Sorokina, Irina T; Mashinsky, Valery M.; Ischakova, Lyudmila D.; Dianov, Evgenii M; Kalashnikov, Valdimir L; Yashkov, Mikhail V.; Khopin, Vladimir F.; Guryanov, Aleksey N.

    2011-01-01

    A novel all-fiber laser based on a highly GeO2-doped dispersion-shifted Tm-codoped fiber, pumped at 1.56 µm wavelength and lasing at 1.862 µm wavelength with a slope efficiency up to 37% was demonstrated. The single-mode Tm-doped fiber with the 55GeO2-45SiO2 core was fabricated for the first time by MCVD technique. The laser produces spectral side bands, resulting from the four-wave mixing owing to the shift of the zero-dispersion-wavelength of the fiber to the laser wavelength, thus, making ...

  7. Arsenic-doped high-resistivity-silicon epitaxial layers for integrating low-capacitance diodes

    NARCIS (Netherlands)

    Sakic, A.; Scholtes, T.L.M.; De Boer, W.B.; Golshani, N.; Derakhshandeh, J.; Nanver, L.K.

    2011-01-01

    An arsenic doping technique for depositing up to 40-?m-thick high-resistivity layers is presented for fabricating diodes with low RC constants that can be integrated in closely-packed configurations. The doping of the as-grown epi-layers is controlled down to 5 × 1011 cm?3, a value that is solely

  8. High-performace cladding-pumped erbium-doped fibre laser and amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Kotov, L V; Likhachev, M E; Bubnov, M M; Medvedkov, O I; Lipatov, D S; Vechkanov, N N; Guryanov, Aleksei N

    2012-05-31

    We report cladding-pumped erbium-doped fibre laser and amplifier configurations. Through fibre design optimisation, we have achieved a record-high laser slope efficiency, 40 % with respect to absorbed pump power ({lambda} = 976 nm), and an output power of 7.5 W. The erbium-doped fibre amplifier efficiency reaches 32 %.

  9. Application of highly silicon-doped marker layers in the investigation of unintentional doping in GaN on sapphire

    International Nuclear Information System (INIS)

    Oliver, R.A.

    2010-01-01

    To provide a route to the assessment of the impact of inclined facets on unintentional n-type doping during the growth of c-plane GaN on sapphire, thin (100 nm), highly Si-doped (at 10 19 cm -3 ) marker layers have been incorporated into a GaN epitaxial layer grown by a method involving a transition from initial three-dimensional island growth to later, two-dimensional, planar growth. Imaging of the completed epitaxial layer in cross-section by scanning capacitance microscopy reveals the shapes of the islands, which were present during the early stages of growth and the relationship between the facets present and the incorporation of unintentional dopants. The results show that unintentional dopants are mostly incorporated on facets inclined to the [0 0 0 1] direction, and suggest that gaseous impurities present in the MOVPE reactor are one source of dopant species. -- Research highlights: →Scanning capacitance microscopy has been used to study unintentional doping in GaN epilayers. →Highly doped marker layers provide the means to track the growth and coalescence of the islands, which form the epilayer, and how this relates to the incorporation of unintentional dopants. →The results suggest that the presence of facets inclined to (0 0 0 1) is important in the incorporation of unintentional dopants.

  10. Improving superconducting properties of YBCO high temperature superconductor by Graphene Oxide doping

    Energy Technology Data Exchange (ETDEWEB)

    Dadras, S., E-mail: dadras@alzahra.ac.ir; Dehghani, S.; Davoudiniya, M.; Falahati, S.

    2017-06-01

    In this research, we report the synthesis and characterization of YBa{sub 2}Cu{sub 3}O{sub 7-δ} (YBCO) high temperature superconductor prepared by sol-gel method and doped with Graphene Oxide (GO) in different weight percentages, 0, 0.1, 0.7 and 1 % wt. The x-ray diffraction (XRD) analysis confirms the formation of orthorhombic phase of superconductivity for all the prepared samples. We found that GO doping reduces the crystalline size of the samples. We evaluated the effects of GO doping on the normal state resistivity (ρ), superconducting transition temperature (T{sub c}) and critical current density (J{sub c}). The results show that the GO doping has a positive effect on these properties. Also, the highest J{sub c} is obtained for the 0.7 %wt GO doped YBCO compound that its critical current density is about 15 times more than the J{sub c} of pure one in 0.4 T magnetic field. The scanning electron microscope (SEM) analysis shows that there are better connections between the grains of GO doped samples. - Highlights: • Graphene Oxide doping increased the YBCO critical current density. • Graphene Oxide creates a better connection between the YBCO grains. • The normal resistivity of samples were decreased by GO doping to YBCO compounds. • Graphene Oxide doping has a positive effect on the critical transition temperature.

  11. High performance aqueous supercapacitor based on highly nitrogen-doped carbon nanospheres with unimodal mesoporosity

    Science.gov (United States)

    Sun, Fei; Gao, Jihui; Pi, Xinxin; Wang, Lijie; Yang, Yuqi; Qu, Zhibin; Wu, Shaohua

    2017-01-01

    Herein, we report a high performance aqueous supercapacitor which is made of highly nitrogen-doped carbon nanospheres (NRMCs) with unimodal mesoporosity. An aerosol-assisted spraying process is employed to obtain the nano-sized NRMC particles possessing large surface areas, high pore volumes and ultra-high N doping levels (14.51%-20.55%). Evaluated as supercapacitor electrode, the optimized NRMC exhibits excellent performance for aqueous electrical double layer capacitors with high material-level specific capacitance (432 F g-1 at 1 A g-1), excellent rate performance (205 F g-1 at a high current density of 100 A g-1) and high cycling stability. The constructed symmetric supercapacitor delivers high energy densities of 9.2 Wh kg-1 and 4 Wh kg-1 at power densities of 0.11 kW kg-1 and 23.24 kW kg-1, respectively. Moreover, the effect of N specie distribution on the rate performance is also demonstrated, which highlights the important role of tuning the N doping patterns on enhancing the supercapacitive performances of carbon materials.

  12. Highly improved sensibility and selectivity ethanol sensor of mesoporous Fe-doped NiO nanowires

    Science.gov (United States)

    Li, X. Q.; Wei, J. Q.; Xu, J. C.; Jin, H. X.; Jin, D. F.; Peng, X. L.; Hong, B.; Li, J.; Yang, Y. T.; Ge, H. L.; Wang, Xinqing

    2017-12-01

    In this paper, nickel oxides (NiO) and iron (Fe)-doped NiO nanowires (NWs) with the various doping content (from 1 to 9 at%) were synthesized by using SBA-15 templates with the nanocasting method. All samples were synthesized in the same conditions and exhibited the same mesoporous-structures, uniform diameter, and defects. Mesoporous-structures with high surface area created more active sites for the adsorption of oxygen on the surface of all samples, resulting in the smaller surface resistance in air. The impurity energy levels from the donor Fe-doping provided electrons to neutralize the holes of p-type Fe-doped NiO NWs, which greatly enhanced the total resistance. The comparative gas-sensing study between NiO NWs and Fe-doped NiO NWs indicated that the high-valence donor Fe-doping obviously improved the ethanol sensitivity and selectivity for Fe-doped NiO NWs. And Ni0.94Fe0.06O1.03 NWs sensor presented the highest sensitivity of 14.30 toward ethanol gas at 320 °C for the high-valence metal-doping.

  13. High performance yttrium-doped BSCF hollow fibre membranes

    DEFF Research Database (Denmark)

    Haworth, P.; Smart, S.; Glasscock, Julie

    2012-01-01

    Oxygen production from BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3−δ) and yttrium-doped BSCF (Ba0.5Sr0.5Co0.8Fe0.175Y0.025O3−δ) hollow fibres was investigated, and the role of yttrium in the crystal structure was further explored using high-temperature X-ray diffraction. Yttrium substitution acted to increase...... the oxygen flux significantly, from 4.9 to 7.0mlcm−2min−1 at 900°C for the BSCF and the BSCFY membranes, respectively. Permeation was particularly enhanced at lower temperatures, between 66% and 92% over the range 650–800°C. The lattice expansion determined from high temperature X-ray diffraction...... measurements in air was similar for both compositions, suggesting that the higher oxygen fluxes obtained for BSCFY hollow fibres could be attributed to the higher non-stoichiometry due to yttrium addition to the BSCF crystal structure. In addition, the improvement of oxygen fluxes for small wall thickness (∼0...

  14. Development of 8-inch Key Processes for Insulated-Gate Bipolar Transistor

    Directory of Open Access Journals (Sweden)

    Guoyou Liu

    2015-09-01

    Full Text Available Based on the construction of the 8-inch fabrication line, advanced process technology of 8-inch wafer, as well as the fourth-generation high-voltage double-diffused metal-oxide semiconductor (DMOS+ insulated-gate bipolar transistor (IGBT technology and the fifth-generation trench gate IGBT technology, have been developed, realizing a great-leap forward technological development for the manufacturing of high-voltage IGBT from 6-inch to 8-inch. The 1600 A/1.7 kV and 1500 A/3.3 kV IGBT modules have been successfully fabricated, qualified, and applied in rail transportation traction system.

  15. Biomineralization-Inspired Synthesis of Cerium-Doped Carbonaceous Nanoparticles for Highly Hydroxyl Radical Scavenging Activity

    Science.gov (United States)

    Zou, Shenqiang; Zhu, Xiaofang; Zhang, Lirong; Guo, Fan; Zhang, Miaomiao; Tan, Youwen; Gong, Aihua; Fang, Zhengzou; Ju, Huixiang; Wu, Chaoyang; Du, Fengyi

    2018-03-01

    Cerium oxide nanoparticles recently have received extensive attention in biomedical applications due to their excellent anti-oxidation performance. In this study, a simple, mild, and green approach was developed to synthesize cerium-doped carbonaceous nanoparticles (Ce-doped CNPs) using bio-mineralization of bull serum albumin (BSA) as precursor. The resultant Ce-doped CNPs exhibited uniform and ultrasmall morphology with an average size of 14.7 nm. XPS and FTIR results revealed the presence of hydrophilic group on the surface of Ce-doped CNPs, which resulted in excellent dispersity in water. The CCK-8 assay demonstrated that Ce-doped CNPs possessed favorable biocompatibility and negligible cytotoxicity. Using H2O2-induced reactive oxygen species (ROS) as model, Ce-doped CNPs showed highly hydroxyl radical scavenging capability. Furthermore, flow cytometry and live-dead staining results indicated that Ce-doped CNPs protected cells from H2O2-induced damage in a dose-dependent effect, which provided a direct evidence for anti-oxidative performance. These findings suggest that Ce-doped CNPs as novel ROS scavengers may provide a potential therapeutic prospect in treating diseases associated with oxidative stress.

  16. A highly conducting graphene film with dual-side molecular n-doping

    Science.gov (United States)

    Kim, Youngsoo; Park, Jaesung; Kang, Junmo; Yoo, Je Min; Choi, Kyoungjun; Kim, Eun Sun; Choi, Jae-Boong; Hwang, Chanyong; Novoselov, K. S.; Hong, Byung Hee

    2014-07-01

    Doping is an efficient way to engineer the conductivity and the work function of graphene, which is, however, limited to wet-chemical doping or metal deposition particularly for n-doping, Here, we report a simple method of modulating the electrical conductivity of graphene by dual-side molecular n-doping with diethylenetriamine (DETA) on the top and amine-functionalized self-assembled monolayers (SAMs) at the bottom. The resulting charge carrier density of graphene is as high as -1.7 × 1013 cm-2, and the sheet resistance is as low as ~86 +/- 39 Ω sq-1, which is believed to be the lowest sheet resistance of monolayer graphene reported so far. This facile dual-side n-doping strategy would be very useful to optimize the performance of various graphene-based electronic devices.Doping is an efficient way to engineer the conductivity and the work function of graphene, which is, however, limited to wet-chemical doping or metal deposition particularly for n-doping, Here, we report a simple method of modulating the electrical conductivity of graphene by dual-side molecular n-doping with diethylenetriamine (DETA) on the top and amine-functionalized self-assembled monolayers (SAMs) at the bottom. The resulting charge carrier density of graphene is as high as -1.7 × 1013 cm-2, and the sheet resistance is as low as ~86 +/- 39 Ω sq-1, which is believed to be the lowest sheet resistance of monolayer graphene reported so far. This facile dual-side n-doping strategy would be very useful to optimize the performance of various graphene-based electronic devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00479e

  17. Boron-doped diamond synthesized at high-pressure and high-temperature with metal catalyst

    Science.gov (United States)

    Shakhov, Fedor M.; Abyzov, Andrey M.; Kidalov, Sergey V.; Krasilin, Andrei A.; Lähderanta, Erkki; Lebedev, Vasiliy T.; Shamshur, Dmitriy V.; Takai, Kazuyuki

    2017-04-01

    The boron-doped diamond (BDD) powder consisting of 40-100 μm particles was synthesized at 5 GPa and 1500-1600 °C from a mixture of 50 wt% graphite and 50 wt% Ni-Mn catalyst with an addition of 1 wt% or 5 wt% boron powder. The size of crystal domains of doped and non-doped diamond was evaluated as a coherent scattering region by X-ray diffraction (XRD) and using small-angle neutron scattering (SANS), being ≥180 nm (XRD) and 100 nm (SANS). Magnetic impurities of NiMnx originating from the catalyst in the synthesis, which prevent superconductivity, were detected by magnetization measurements at 2-300 K. X-ray photoelectron spectroscopy, the temperature dependence of the resistivity, XRD, and Raman spectroscopy reveal that the concentration of electrically active boron is as high as (2±1)×1020 cm-3 (0.1 at%). To the best of our knowledge, this is the highest boron content for BDD synthesized in high-pressure high-temperature process with metal catalysts.

  18. A novel high breakdown voltage lateral bipolar transistor on SOI with multizone doping and multistep oxide

    International Nuclear Information System (INIS)

    Loan, Sajad A; Qureshi, S; Kumar Iyer, S S

    2009-01-01

    A novel high breakdown voltage lateral bipolar junction transistor (LBJT) on silicon-on- insulator (SOI) is proposed. The novelty of the device is the use of the combination of multistep-doped drift region and multistep buried oxide. The steps in doping and in oxide thickness have been used as a replacement for much complex linearly varying drift doping and linearly varying oxide thickness. The LBJT structure incorporating the combination of multistep doping and multistep oxide is analyzed for electrical characteristics using a two-dimensional numerical simulator MEDICI. Numerical simulation has demonstrated that the breakdown voltage of the proposed device with a two-zone step doped (TZSD) drift region is >150% higher than the conventional device. It has been observed that increasing the number of doping zones to 3 from 2 results in a >40% rise in breakdown voltage. The proposed device gives high breakdown voltage even at high doping concentration in the collector drift region. This reduces the on-resistance of the device and thus improves its speed. The dependence of breakdown voltage on various device parameters has been extensively studied to achieve optimum device performance. A process flow for the device fabrication is also being proposed

  19. High Power Narrow Linewidth 1.26 Micron Ho-Doped Fiber Amplifier, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development of an innovative, high power, and extremely reliable 1.26-micron Ho-doped fluoride fiber amplifier. The proposed fiber amplifier...

  20. High Power Narrow Linewidth 1.26 Micron Ho-Doped Fiber Amplifier, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development of an innovative, high power, and extremely reliable 1.26-micron Ho-doped fluoride fiber amplifier. The proposed fiber amplifier...

  1. Efficient High Power 2 micron Tm3+-Doped Fiber Laser, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development of new Tm3+ doped germanate glass fibers for efficient high power 2-micron fiber lasers capable of generating an output power of...

  2. Efficient high power 2 micron Tm3+-Doped Fiber Laser, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal is for the development of new Tm3+ doped germanate glass fibers for efficient high power 2 micron fiber lasers capable of generating an output power of...

  3. Application of highly silicon-doped marker layers in the investigation of unintentional doping in GaN on sapphire.

    Science.gov (United States)

    Oliver, R A

    2010-12-01

    To provide a route to the assessment of the impact of inclined facets on unintentional n-type doping during the growth of c-plane GaN on sapphire, thin (100 nm), highly Si-doped (at 10¹⁹ cm⁻³) marker layers have been incorporated into a GaN epitaxial layer grown by a method involving a transition from initial three-dimensional island growth to later, two-dimensional, planar growth. Imaging of the completed epitaxial layer in cross-section by scanning capacitance microscopy reveals the shapes of the islands, which were present during the early stages of growth and the relationship between the facets present and the incorporation of unintentional dopants. The results show that unintentional dopants are mostly incorporated on facets inclined to the [0001] direction, and suggest that gaseous impurities present in the MOVPE reactor are one source of dopant species. Copyright © 2010 Elsevier B.V. All rights reserved.

  4. Torque expression of 0.018 and 0.022 inch conventional brackets

    NARCIS (Netherlands)

    Sifakakis, I.; Pandis, N.; Makou, M.; Eliades, T.; Katsaros, C.; Bourauel, C.

    2013-01-01

    The aim of this study was to assess the effect of the moments generated with low- and high-torque brackets. Four different bracket prescription-slot combinations of the same bracket type (Mini Diamond(R) Twin) were evaluated: high-torque 0.018 and 0.022 inch and low-torque 0.018 and 0.022 inch.

  5. Doping of two-dimensional MoS2 by high energy ion implantation

    Science.gov (United States)

    Xu, Kang; Zhao, Yuda; Lin, Ziyuan; Long, Yan; Wang, Yi; Chan, Mansun; Chai, Yang

    2017-12-01

    Two-dimensional (2D) materials have been demonstrated to be promising candidates for next generation electronic circuits. Analogues to conventional Si-based semiconductors, p- and n-doping of 2D materials are essential for building complementary circuits. Controllable and effective doping strategies require large tunability of the doping level and negligible structural damage to ultrathin 2D materials. In this work, we demonstrate a doping method utilizing a conventional high-energy ion-implantation machine. Before the implantation, a Polymethylmethacrylate (PMMA) protective layer is used to decelerate the dopant ions and minimize the structural damage to MoS2, thus aggregating the dopants inside MoS2 flakes. By optimizing the implantation energy and fluence, phosphorus dopants are incorporated into MoS2 flakes. Our Raman and high-resolution transmission electron microscopy (HRTEM) results show that only negligibly structural damage is introduced to the MoS2 lattice during the implantation. P-doping effect by the incorporation of p+ is demonstrated by Photoluminescence (PL) and electrical characterizations. Thin PMMA protection layer leads to large kinetic damage but also a more significant doping effect. Also, MoS2 with large thickness shows less kinetic damage. This doping method makes use of existing infrastructures in the semiconductor industry and can be extended to other 2D materials and dopant species as well.

  6. Ultrabroadband terahertz conductivity of highly doped ZnO and ITO

    DEFF Research Database (Denmark)

    Wang, Tianwu; Zalkovskij, Maksim; Iwaszczuk, Krzysztof

    2015-01-01

    The broadband complex conductivities of transparent conducting oxides (TCO), namely aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO) and tin-doped indium oxide (ITO), were investigated by terahertz time domain spectroscopy (THz-TDS) in the frequency range from 0.5 to 18 THz using air...... to be more thickness dependent than GZO and ITO, indicating high importance of the surface states for electron dynamics in AZO. Finally, we measure the transmittance of the TCO films from 10 to 200 THz with Fourier transform infrared spectroscopy (FTIR) measurements, thus closing the gap between THz...

  7. Development of a 14-inch ID High-Pressure Hybrid Riser for SBOP Drilling Développement d’un riser hybride 14”ID haute pression pour le forage SBOP

    Directory of Open Access Journals (Sweden)

    Persent E.

    2009-11-01

    Full Text Available This paper discusses the development of a 14-inch ID high-pressure hybrid riser (10 000 psi for surface BOP drilling in ultra-deep water (10 000 ft. The high-pressure hybrid riser system is obtained by adapting and combining two existing technologies, previously developed by the IFP for other applications: – the Clip connector, a double breech-block type connector to provide a quick and safe connection for riser joints; – hybrid pipe technology, a steel pipe hoop-wound with tapes of carbon fibers impregnated with polyamide thermoplastic resin. IFP has developed a new 14-inch ID HP Clip connector for the hybrid riser application. The connector is capable of withstanding a 2.8 million pound tension and a 10 000 psi operating pressure. In addition, a 16-inch nominal OD hybrid riser pipe has been designed to replace the steel riser pipe with a thinnerwalled hoop-wound steel pipe. The significant weight savings that can be achieved with the hybrid riser pipe make it possible to design an effective riser architecture to withstand the high pressure and deep water requirements. Pursuant to design studies, a 14-inch ID prototype assembly consisting of two hybrid riser pipe sections with a high-pressure Clip connector was manufactured. A test program, including burst and collapse tests as well as cyclic fatigue testing, was formulated and carried out to qualify the performance of the Clip connector and hybrid riser pipe system. Completion of hybrid pipe additional fatigue testing and realization of a scale-one field testing of the hybrid riser are considered as the next steps of the project. To date, the main test results (burst, collapse, fatigue resistance confirm that the Clip connector and the hybrid pipe technologies are well suited for ultra-deep sea drilling with a surface BOP. However, the fatigue resistance of hybrid riser pipes still needs to be better characterized. Cet article présente le développement d’un riser hybride 14”ID haute

  8. Arsenic-Doped High-Resistivity-Silicon Epitaxial Layers for Integrating Low-Capacitance Diodes

    Directory of Open Access Journals (Sweden)

    Jaber Derakhshandeh

    2011-12-01

    Full Text Available An arsenic doping technique for depositing up to 40-μm-thick high-resistivity layers is presented for fabricating diodes with low RC constants that can be integrated in closely-packed configurations. The doping of the as-grown epi-layers is controlled down to 5 × 1011 cm−3, a value that is solely limited by the cleanness of the epitaxial reactor chamber. To ensure such a low doping concentration, first an As-doped Si seed layer is grown with a concentration of 1016 to 1017 cm−3, after which the dopant gas arsine is turned off and a thick lightly-doped epi-layer is deposited. The final doping in the thick epi-layer relies on the segregation and incorporation of As from the seed layer, and it also depends on the final thickness of the layer, and the exact growth cycles. The obtained epi-layers exhibit a low density of stacking faults, an over-the-wafer doping uniformity of 3.6%, and a lifetime of generated carriers of more than 2.5 ms. Furthermore, the implementation of a segmented photodiode electron detector is demonstrated, featuring a 30 pF capacitance and a 90 Ω series resistance for a 7.6 mm2 anode area.

  9. An asymmetric Zn//Ag doped polyaniline microparticle suspension flow battery with high discharge capacity

    Science.gov (United States)

    Wu, Sen; Zhao, Yongfu; Li, Degeng; Xia, Yang; Si, Shihui

    2015-02-01

    In this study, the effect of oxygen on the potential of reduced polyaniline (PANI) was investigated. In order to enhance the air oxidation of reduced PANI, several composites of PANI doped with co-catalysts were prepared, and a reasonable flow Zn//PANI suspension cell system was designed to investigate the discharge capacity of obtained PANI composite microparticle suspension cathodes. Compared with PANI doped with Cu2+, La+, Mn2+ and zinc protoporphyrin, Ag doped PANI composite at 0.90 weight percent doping of Ag gave the highest value of discharge capacity for the half-cell potential from the initial value to -0.20 V (vs. SCE). A comparison study on the electrochemical properties of both PANI and Ag doped PANI microparticle suspension was done by using cyclic voltammetry, AC Impedance. Due to partial utilization of Zn//air fuel cell, the discharge capacity for Ag doped PANI reached 470 mA h g-1 at the current density of 20 mA cm-2. At 15 mA cm-2, the discharge capacity even reached up to 1650 mA h g-1 after 220 h constant current discharge at the final discharge voltage of 0.65 V. This work demonstrates an effective and feasible approach toward obtaining high energy and power densities by a Zn//Ag-doped PANI suspension flow battery system combined with Zn//air fuel cell.

  10. Design of high quality doped CeO2 solid electrolytes with nanohetero structure

    International Nuclear Information System (INIS)

    Mori, T.; Ou, D.R.; Ye, F.; Drennan, J.

    2006-01-01

    Doped cerium (CeO 2 ) compounds are fluorite related oxides which show oxide ionic conductivity higher than yttria-stabilized zirconia in oxidizing atmosphere. As a consequence of this, a considerable interest has been shown in application of these materials for low (400-650 o C) temperature operation of solid oxide fuel cells (SOFCs). In this paper, our experimental data about the influence of microstructure at the atomic level on electrochemical properties were reviewed in order to develop high quality doped CeO 2 electrolytes in fuel cell applications. Using this data in the present paper, our original idea for a design of nanodomain structure in doped CeO 2 electrolytes was suggested. The nanosized powders and dense sintered bodies of M doped CeO 2 (M:Sm,Gd,La,Y,Yb, and Dy) compounds were fabricated. Also nanostructural features in these specimens were introduced for conclusion of relationship between electrolytic properties and domain structure in doped CeO 2 . It is essential that the electrolytic properties in doped CeO 2 solid electrolytes reflect in changes of microstructure even down to the atomic scale. Accordingly, a combined approach of nanostructure fabrication, electrical measurement and structure characterization was required to develop superior quality doped CeO 2 electrolytes in the fuel cells. (author)

  11. Phosphoric acid doped AB-PBI membranes and its applications in high temperature PEMFC

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Bjerrum, Niels

    2005-01-01

    Poly(2,5-benzimidazole) (ab-PBI) was prepared from 3,4-diaminobenzoic acid via a polymerisation reaction. The obtained polymer exhibits excellent thermal stability in a temperature range ….. The membrane of ab-PBI when doped with phosphoric acid at room temperaturepresents high proton conductivit......C with phosphoric acid doped ab-PBI as the electrolyte under atmospheric pressure at 200°C without humidification....

  12. Doping Optimization for High Efficiency in Semiconductor Diode Lasers and Amplifiers

    Science.gov (United States)

    2016-03-01

    JOURNAL OF QUANTUM ELECTRONICS, VOL. , NO. , 1 Doping Optimization for High Efficiency in Semiconductor Diode Lasers and Amplifiers Dominic F...Siriani, Member, IEEE Abstract—A generalized theoretical formalism is derived that optimizes the doping profile of semiconductor diode lasers and amplifiers...Diode lasers, semiconductor lasers, semiconduc- tor optical amplifiers. I. INTRODUCTION ELECTRICALLY injected diode lasers have been demon-strated in many

  13. Highly efficient cobalt-doped carbon nitride polymers for solvent-free selective oxidation of cyclohexane

    Directory of Open Access Journals (Sweden)

    Yu Fu

    2017-04-01

    Full Text Available Selective oxidation of saturated hydrocarbons with molecular oxygen has been of great interest in catalysis, and the development of highly efficient catalysts for this process is a crucial challenge. A new kind of heterogeneous catalyst, cobalt-doped carbon nitride polymer (g-C3N4, was harnessed for the selective oxidation of cyclohexane. X-ray diffraction, Fourier transform infrared spectra and high resolution transmission electron microscope revealed that Co species were highly dispersed in g-C3N4 matrix and the characteristic structure of polymeric g-C3N4 can be retained after Co-doping, although Co-doping caused the incomplete polymerization to some extent. Ultraviolet–visible, Raman and X-ray photoelectron spectroscopy further proved the successful Co doping in g-C3N4 matrix as the form of Co(IIN bonds. For the selective oxidation of cyclohexane, Co-doping can markedly promote the catalytic performance of g-C3N4 catalyst due to the synergistic effect of Co species and g-C3N4 hybrid. Furthermore, the content of Co largely affected the activity of Co-doped g-C3N4 catalysts, among which the catalyst with 9.0 wt% Co content exhibited the highest yield (9.0% of cyclohexanone and cyclohexanol, as well as a high stability. Meanwhile, the reaction mechanism over Co-doped g-C3N4 catalysts was elaborated. Keywords: Selective oxidation of cyclohexane, Oxygen oxidant, Carbon nitride, Co-doping

  14. Superconductivity. Quasiparticle mass enhancement approaching optimal doping in a high-T(c) superconductor.

    Science.gov (United States)

    Ramshaw, B J; Sebastian, S E; McDonald, R D; Day, James; Tan, B S; Zhu, Z; Betts, J B; Liang, Ruixing; Bonn, D A; Hardy, W N; Harrison, N

    2015-04-17

    In the quest for superconductors with higher transition temperatures (T(c)), one emerging motif is that electronic interactions favorable for superconductivity can be enhanced by fluctuations of a broken-symmetry phase. Recent experiments have suggested the existence of the requisite broken-symmetry phase in the high-T(c) cuprates, but the impact of such a phase on the ground-state electronic interactions has remained unclear. We used magnetic fields exceeding 90 tesla to access the underlying metallic state of the cuprate YBa2Cu3O(6+δ) over a wide range of doping, and observed magnetic quantum oscillations that reveal a strong enhancement of the quasiparticle effective mass toward optimal doping. This mass enhancement results from increasing electronic interactions approaching optimal doping, and suggests a quantum critical point at a hole doping of p(crit) ≈ 0.18. Copyright © 2015, American Association for the Advancement of Science.

  15. Doped polymer electrodes for high performance ferroelectric capacitors on plastic substrates

    KAUST Repository

    Khan, M. A.

    2012-10-03

    Flexible ferroelectric capacitors with doped polymer electrodes have been fabricated on plastic substrates with performance as good as metal electrodes. The effect of doping on the morphology of polymer electrodes and its impact on device performance have been studied. Improved fatigue characteristics using doped and undoped poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) electrodes versus metal electrodes are observed. It is shown that the polymer electrodes follow classical ferroelectric and dielectric responses, including series resistance effects. The improved device characteristics obtained using highly conducting doped PEDOT:PSS suggest that it may be used both as an electrode and as global interconnect for all-polymer transparent circuits on flexible substrates.

  16. Enhanced mass diffusion phenomena in highly defective doped ceria

    DEFF Research Database (Denmark)

    Esposito, Vincenzo; Ni, De Wei; He, Zeming

    2013-01-01

    The densification and grain growth of the solid state ionic conductor material Ce0.9Gd0.1O1.95−δ (i.e. GDC10, gadolinium-doped ceria, with Gd 10mol.%) are analysed for nanometric and fine powders of various particle sizes, both in air and in a 9vol.% H2–N2 mixture. Due to a dominant solute drag...

  17. Diffusion in Intrinsic and Highly Doped III-V Semiconductors

    CERN Multimedia

    Stolwijk, N

    2002-01-01

    %title\\\\ \\\\Diffusion plays a key role in the fabrication of semiconductor devices. The diffusion of atoms in crystals is mediated by intrinsic point defects. Investigations of the diffusion behaviour of self- and solute atoms on the Ga sublattice of gallium arsenide led to the conclusion that in intrinsic and n-type material charged Ga vacancies are involved in diffusion processes whereas in p-type material diffusion if governed by charged Ga self-interstitials. Concerning the As sublattice of gallium arsenide there is a severe lack of reliable diffusion data. The few available literature data on intrinsic GaAs are not mutually consistent. A systematic study of the doping dependence of diffusion is completely missing. The most basic diffusion process - self-diffusion of As and its temperature and doping dependence - is practically not known. For GaP a similar statement holds.\\\\ \\\\The aim of the present project is to perform a systematic diffusion study of As diffusion in intrinsic and doped GaAs and in GaP. P...

  18. Fabrication of Chemically Doped, High Upper Critical Field Magnesium Diboride Superconducting Wires

    International Nuclear Information System (INIS)

    Marzik, James V.

    2005-01-01

    Controlled chemical doping of magnesium diboride (MgB2) has been shown to substantially improve its superconducting properties to the levels required for high field magnets, but the doping is difficult to accomplish through the usual route of solid state reaction and diffusion. Further, superconducting cables of MgB2 are difficult to fabricate because of the friable nature of the material. In this Phase I STTR project, doped and undoped boron fibers were made by chemical vapor deposition (CVD). Several >100m long batches of doped and undoped fiber were made by CVD codeposition of boron plus dopants. Bundles of these fibers infiltrated with liquid magnesium and subsequently converted to MgB2 to form Mg-MgB2 metal matrix composites. In a parallel path, doped boron nano-sized powder was produced by a plasma synthesis technique, reacted with magnesium to produce doped MgB2 superconducting ceramic bodies. The doped powder was also fabricated into superconducting wires several meters long. The doped boron fibers and powders made in this program were fabricated into fiber-metal composites and powder-metal composites by a liquid metal infiltration technique. The kinetics of the reaction between boron fiber and magnesium metal was investigated in fiber-metal composites. It was found that the presence of dopants had significantly slowed the reaction between magnesium and boron. The superconducting properties were measured for MgB2 fibers and MgB2 powders made by liquid metal infiltration. Properties of MgB2 products (Jc, Hc2) from Phase I are among the highest reported to date for MgB2 bulk superconductors. Chemically doped MgB2 superconducting magnets can perform at least as well as NbTi and NbSn3 in high magnetic fields and still offer an improvement over the latter two in terms of operating temperature. These characteristics make doped MgB2 an effective material for high magnetic field applications, such as magnetic confined fusion, and medical MRI devices. Developing

  19. Fabrication of Chemically Doped, High Upper Critical Field Magnesium Diboride Superconducting Wires

    Energy Technology Data Exchange (ETDEWEB)

    Marzik, James, V.

    2005-10-13

    Controlled chemical doping of magnesium diboride (MgB2) has been shown to substantially improve its superconducting properties to the levels required for high field magnets, but the doping is difficult to accomplish through the usual route of solid state reaction and diffusion. Further, superconducting cables of MgB2 are difficult to fabricate because of the friable nature of the material. In this Phase I STTR project, doped and undoped boron fibers were made by chemical vapor deposition (CVD). Several >100m long batches of doped and undoped fiber were made by CVD codeposition of boron plus dopants. Bundles of these fibers infiltrated with liquid magnesium and subsequently converted to MgB2 to form Mg-MgB2 metal matrix composites. In a parallel path, doped boron nano-sized powder was produced by a plasma synthesis technique, reacted with magnesium to produce doped MgB2 superconducting ceramic bodies. The doped powder was also fabricated into superconducting wires several meters long. The doped boron fibers and powders made in this program were fabricated into fiber-metal composites and powder-metal composites by a liquid metal infiltration technique. The kinetics of the reaction between boron fiber and magnesium metal was investigated in fiber-metal composites. It was found that the presence of dopants had significantly slowed the reaction between magnesium and boron. The superconducting properties were measured for MgB2 fibers and MgB2 powders made by liquid metal infiltration. Properties of MgB2 products (Jc, Hc2) from Phase I are among the highest reported to date for MgB2 bulk superconductors. Chemically doped MgB2 superconducting magnets can perform at least as well as NbTi and NbSn3 in high magnetic fields and still offer an improvement over the latter two in terms of operating temperature. These characteristics make doped MgB2 an effective material for high magnetic field applications, such as magnetic confined fusion, and medical MRI devices. Developing

  20. High-resolution calorimetry: limitations of doped semiconductor thermometers

    CERN Document Server

    McCammon, D; Apodaca, E; Deiker, S; Galeazzi, M; Han, S I; Lesser, A; Sanders, W; Kelley, R L; Moseley, S H; Porter, F S; Stahle, C K; Szymkowiak, A E

    1999-01-01

    Small thermal calorimeters operating at cryogenic temperatures have achieved an energy resolution for single X-ray photons that is a factor of 20 better than the theoretical limit for a silicon ionization detector. To determine the potential for further improvements and decide on likely routes for achieving them, we discuss detector design optimization, first for an ideal calorimeter, and then for the case where components exhibit non-ideal behavior. Two serious non-ideal properties of doped semiconductor thermometers are electron-phonon decoupling and excess noise. These have been characterized over a range of sensitivity and operating temperature, and their effects on design optimization and ultimate performance can be evaluated.

  1. Bright and high-photostable inner-Mn-doped core/giant-shell quantum dots

    Science.gov (United States)

    Xu, Ruilin; Huang, Bo; Wang, Tian; Yuan, Yufen; Zhang, Lei; Lu, Changgui; Cui, Yiping; Zhang, Jiayu

    2017-11-01

    Compared with quantum-dot (QD) displays, QD lighting possesses higher demand of photostability. Owing to high photostability from the combination of inner independent luminescence center and thick shell (≥15 monolayers (MLs)), inner-Mn-doped core/giant-shell QDs with bright wide emission are a promising candidate for QD lighting. Aiming at bright and high-photostable giant QDs with low time cost (giant-shell growth time: within 20 min), we put forward the perfect combination strategy of hot-injection nucleation doping and optimized ;flash; synthesis, going beyond the combination strategy of one-pot growth doping and typical ;flash; synthesis, which led to an increase in photoluminescence (PL) quantum yield (QY) of giant Mn-doped CdS/ZnS QDs (ZnS shell: ∼18 MLs) from ≤20% to 40%. The PLQY was enhanced to 45% by light annealing. Using traditional LED as the reference, these simply-encapsulated QDs can exhibit the high photostability, throwing light of the application of these inner-Mn-doped core/giant-shell QDs even for QD lighting.

  2. High precision trace neutron transmutation doping of detector-grade high resistance zone-refined silicon mono-crystal

    International Nuclear Information System (INIS)

    Chen Bingxian; Gao Jijin; Gao Xiuqing; Dong Heqin; Li Shiling

    1993-08-01

    The technique of high precision trace neutron transmutation doping of detector grade high resistance zone-refined Si mono-crystal is introduced. The key technique is to precisely control the doping element. It includes the determination of ρ 0 value according to theoretical calculation and experimental results, the selection of irradiation channel and improvement of irradiation devices, the regulation of doping coefficient K, the simulation experiment of silicon crystal, strict control of irradiation time and the study on mechanism of radiation damage and its elimination. The developed N-type (10 ∼ 100) kΩcm NTD FZ Si has excellent uniformity of specific resistance, long life of minority carrier and high-purity of the crystal

  3. A fundamental self-generated quenching center for lanthanide-doped high-purity solids

    International Nuclear Information System (INIS)

    Auzel, F.

    2002-01-01

    An intrinsic self-generated quenching center for lanthanide-doped high-purity solids is presented for transitions, which cannot be quenched by cross-relaxation. This center, in fact a cluster-like pair of active centers, is shown to come from a particular multiphonon-assisted energy transfer between them. Being due to the vibronic properties of the host it cannot be suppressed. Its role in lanthanide first excited states self-quenching is analyzed and a simple mathematical expression is derived. This law is compared with experimental results for self-quenching in Er-doped fluorophosphate glasses

  4. Ferromagnetism carried by highly delocalized hybrid states in Sc-doped ZnO thin films

    KAUST Repository

    Benali Kanoun, Mohammed

    2012-05-29

    We present first-principles results for Sc-doped ZnOthin films. Neighboring Sc atoms in the surface and/or subsurface layers are found to be coupled ferromagnetically, where only two of the possible configurations induce spin polarization. In the first configuration, the polarization is carried by the Sc d states as expected for transition metaldoping. However, there is a second configuration which is energetically favorable. It is governed by polarized hybrid states of the Zns, O p, and Sc d orbitals. Such highly delocalized states can be an important ingredient for understanding the magnetism of dopedZnOthin films.

  5. Highly piezoelectric MgZr co-doped aluminum nitride-based vibrational energy harvesters.

    Science.gov (United States)

    Minh, Le Van; Hara, Motoaki; Yokoyama, Tsuyoshi; Nishihara, Tokihiro; Ueda, Masanori; Kuwano, Hiroki

    2015-11-01

    The first MgZr co-doped AlN-based vibrational energy harvester (VEH) is presented. (MgZr)AlN, which is a new class of doped AlN, provides high piezoelectricity and cost advantage. Using 13%-(MgZr)-doped AlN for micromachined VEHs, maximum output power of 1.3 μW was achieved with a Q-factor of 400 when resonant frequency, vibration acceleration, load resistance were 792 Hz, 8 m/s(2), and 1.1 MΩ, respectively. Normalized power density was 8.1 kW·g(-2)·m(-3). This was one of the highest values among the currently available piezoelectric VEHs.

  6. Doping of GaN{sub 1-x}As{sub x} with high As content

    Energy Technology Data Exchange (ETDEWEB)

    Levander, A.X.; Novikov, S.V.; Liliental-Weber, Z.; dos Reis, R.; Dubon, O.D.; Wu, J.; Foxon, C.T.; Yu, K.M.; Walukiewicz, W.

    2011-09-22

    Recent work has shown that GaN{sub 1-x}As{sub x} can be grown across the entire composition range by low temperature molecular beam epitaxy with intermediate compositions being amorphous, but control of the electrical properties through doping is critical for functionalizing this material. Here we report the bipolar doping of GaN{sub 1-x}As{sub x} with high As content to conductivities above 4 S/cm at room temperature using Mg or Te. The carrier type was confirmed by thermopower measurements. Doping requires an increase in Ga flux during growth resulting in a mixed phase material of polycrystalline GaAs:N embedded in amorphous GaN{sub 1-x}As{sub x}.

  7. Doping Lanthanide into Perovskite Nanocrystals: Highly Improved and Expanded Optical Properties.

    Science.gov (United States)

    Pan, Gencai; Bai, Xue; Yang, Dongwen; Chen, Xu; Jing, Pengtao; Qu, Songnan; Zhang, Lijun; Zhou, Donglei; Zhu, Jinyang; Xu, Wen; Dong, Biao; Song, Hongwei

    2017-12-13

    Cesium lead halide (CsPbX 3 ) perovskite nanocrystals (NCs) have demonstrated extremely excellent optical properties and great application potentials in various optoelectronic devices. However, because of the anion exchange, it is difficult to achieve white-light and multicolor emission for practical applications. Herein, we present the successful doping of various lanthanide ions (Ce 3+ , Sm 3+ , Eu 3+ , Tb 3+ , Dy 3+ , Er 3+ , and Yb 3+ ) into the lattices of CsPbCl 3 perovskite NCs through a modified hot-injection method. For the lanthanide ions doped perovskite NCs, high photoluminescence quantum yield (QY) and stable and widely tunable multicolor emissions spanning from visible to near-infrared (NIR) regions are successfully obtained. This work indicates that the doped perovskite NCs will inherit most of the unique optical properties of lanthanide ions and deliver them to the perovskite NC host, thus endowing the family of perovskite materials with excellent optical, electric, or magnetic properties.

  8. Origin of the high p-doping in F intercalated graphene on SiC

    KAUST Repository

    Cheng, Yingchun

    2011-08-04

    The atomic and electronic structures of F intercalated epitaxialgraphene on a SiC(0001) substrate are studied by first-principles calculations. A three-step fluorination process is proposed. First, F atoms are intercalated between the graphene and the SiC, which restores the Dirac point in the band structure. Second, saturation of the topmost Si dangling bonds introduces p-doping up to 0.37 eV. Third, F atoms bond covalently to the graphene to enhance the p-doping. Our model explains the highly p-doped state of graphene on SiC after fluorination [A. L. Walter et al., Appl. Phys. Lett. 98, 184102 (2011)].

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

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Pei-Wen; Li, Kui; Yu, Yu-Xiang; Zhang, Wei-De, E-mail: zhangwd@scut.edu.cn

    2017-01-15

    Graphical abstract: Cobalt-doped graphitic carbon nitride (Co−CN) was synthesized by one-step thermal polycondensation using cobalt phthalocyanine and melamine as precursors. The obtained photocatalysts display high and stable activity for photocatalytic generation of hydrogen through water splitting. - Highlights: • Cobalt-doped g-C{sub 3}N{sub 4} photocatalysts were prepared. • High and stable visible light photocatalytic activity for H{sub 2} evolution. • Efficient separation and transfer of photo-induced electron-hole pairs. - Abstract: Cobalt-doped graphitic carbon nitride (Co−CN) was synthesized by one-step thermal polycondensation using cobalt phthalocyanine (CoPc) and melamine as precursors. The π-π interaction between melamine and CoPc promotes cobalt doping into the framework of g-C{sub 3}N{sub 4}. The prepared samples were carefully characterized and the results demonstrated that Co-doped graphitic carbon nitride inhibited the crystal growth of graphitic carbon nitride (CN), leading to larger specific surface area (33.1 m{sup 2} g{sup −1}) and abundant Co-N{sub x} active sites, narrower band gap energy and more efficient separation of photogenerated electrons and holes. 0.46% Co−CN exhibited higher hydrogen evolution rate (28.0 μmol h{sup −1}) under visible light irradiation, which is about 3.0 times of that over the pure CN and about 2.2 times of that over cobalt-doped CN using CoCl{sub 2} ∙ 6H{sub 2}O as a cobalt source. This study provides a valuable strategy to modify CN with enhanced photocatalytic performance.

  10. Phosphoric acid doped imidazolium polysulfone membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Jensen, Jens Oluf

    2012-01-01

    A novel acid–base polymer membrane is prepared by doping of imidazolium polysulfone with phosphoric acid for high temperature proton exchange membrane fuel cells. Polysulfone is first chloromethylated, followed by functionalization of the chloromethylated polysulfone with alkyl imidazoles i.e. me...

  11. Raman study of bromine-doped single-walled carbon nanotubes under high pressure

    CERN Document Server

    Liu Bing Bing; Yu Miao; Zou Guang Tian; Carlsten, J; Wagberg, T; Sundqvist, B

    2002-01-01

    Raman results for different single-walled carbon nanotube bundles doped with Br sub 2 were studied both at ambient pressure and under high pressure up to 6 GPa. Our study indicates that bromine resides in the interstitial channel of nanotube bundles as a form of polymer.

  12. Instability of supercritical porosity in highly doped ceria under reduced oxygen partial pressure

    DEFF Research Database (Denmark)

    Teocoli, Francesca; Ni, De Wei; Esposito, Vincenzo

    2015-01-01

    The thermomechanical behavior and microstructural evolution of low relative density (∼0.40) gadolinium-doped ceria are characterized under oxidative and reducing conditions at high temperatures. The electronic defects generated in the structure by Ce4+ to Ce3+ reduction play an important role on ...

  13. High rate performance of LiFePO4 cathode materials co-doped with ...

    Indian Academy of Sciences (India)

    Administrator

    Indian Academy of Sciences. 579. High rate performance of LiFePO4 cathode materials co-doped with. C and Ti. 4+ by microwave synthesis. YAN CUI, MIAO WANG and RUISONG GUO*. Key Laboratory of Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin University,. Tianjin 300072, China.

  14. Strongly asymmetric doping profiles at mask edges in high energy ion implantation

    NARCIS (Netherlands)

    Wijburg, R.C.M.; Wijburg, Rutger C.; Hemink, Gertjan; Hemink, Gertjan J.; Middelhoek, J.; Middelhoek, Jan

    1990-01-01

    The application of high-energy ion implantation is restricted by an asymmetric doping profile at the mask edges. As a result, buried interconnect cannot easily be formed. Moreover, the holding voltage and threshold voltage of CMOS-processes with retrograde wells may be strongly affected by this

  15. Thermo-optical effects in high-power Ytterbium-doped fiber amplifiers

    DEFF Research Database (Denmark)

    Hansen, Kristian Rymann; Alkeskjold, Thomas Tanggaard; Broeng, Jes

    2011-01-01

    We investigate the effect of temperature gradients in high-power Yb-doped fiber amplifiers by a numerical beam propagation model, which takes thermal effects into account in a self-consistent way. The thermally induced change in the refractive index of the fiber leads to a thermal lensing effect...

  16. High-Level Heteroatom Doped Two-Dimensional Carbon Architectures for Highly Efficient Lithium-Ion Storage

    Directory of Open Access Journals (Sweden)

    Zhijie Wang

    2018-04-01

    Full Text Available In this work, high-level heteroatom doped two-dimensional hierarchical carbon architectures (H-2D-HCA are developed for highly efficient Li-ion storage applications. The achieved H-2D-HCA possesses a hierarchical 2D morphology consisting of tiny carbon nanosheets vertically grown on carbon nanoplates and containing a hierarchical porosity with multiscale pore size. More importantly, the H-2D-HCA shows abundant heteroatom functionality, with sulfur (S doping of 0.9% and nitrogen (N doping of as high as 15.5%, in which the electrochemically active N accounts for 84% of total N heteroatoms. In addition, the H-2D-HCA also has an expanded interlayer distance of 0.368 nm. When used as lithium-ion battery anodes, it shows excellent Li-ion storage performance. Even at a high current density of 5 A g−1, it still delivers a high discharge capacity of 329 mA h g−1 after 1,000 cycles. First principle calculations verifies that such unique microstructure characteristics and high-level heteroatom doping nature can enhance Li adsorption stability, electronic conductivity and Li diffusion mobility of carbon nanomaterials. Therefore, the H-2D-HCA could be promising candidates for next-generation LIB anodes.

  17. N-doped ZnO nanosheets: towards high performance two dimensional catalysts

    Science.gov (United States)

    Guo, Na; Meng Yam, Kah; Wang, Xiaolu; Zhang, Chun

    2018-03-01

    Recently, catalytic activity of atomically thin two dimensional (2D) materials has attracted great interest. In this paper, via first principles calculations, we show for the first time that N-doped 2D one-atom-thick ZnO nanosheets exhibit high catalytic activity towards CO oxidation. A pristine 2D ZnO nanosheet is chemically inert and as a result, CO and O2 molecules do not chemically bind on the nanosheet. Our calculations predict that the N doping activates the ZnO sheet, leading to strong CO and O2 adsorptions. We further show that the CO oxidation catalyzed by the N-doped 2D ZnO sheet has a low reaction barrier around 0.5 eV. Besides high catalytic activity, the N-doped 2D ZnO sheet also demonstrates intriguing electronic and magnetic properties. These findings provide new opportunities for the future development of high performance 2D catalysts.

  18. Spontaneous doping on high quality talc-graphene-hBN van der Waals heterostructures

    Science.gov (United States)

    Mania, E.; Alencar, A. B.; Cadore, A. R.; Carvalho, B. R.; Watanabe, K.; Taniguchi, T.; Neves, B. R. A.; Chacham, H.; Campos, L. C.

    2017-09-01

    Steady doping, added to its remarkable electronic properties, would make graphene a valuable commodity in the solar cell market, as energy power conversion could be substantially increased. Here we report a graphene van der Waals heterostructure which is able to spontaneously dope graphene (p-type) up to n ~ 2.2  ×  1013 cm-2 while providing excellent charge mobility (μ ~ 25 000 cm2 V-1 s-1). Such properties are achieved via deposition of graphene on atomically flat layered talc, a natural and abundant dielectric crystal. Raman investigation shows a preferential charge accumulation on graphene-talc van der Waals heterostructures, which are investigated through the electronic properties of talc/graphene/hBN heterostructure devices. These heterostructures preserve graphene’s good electronic quality, verified by the observation of quantum Hall effect at low magnetic fields (B  =  0.4 T) at T  =  4.2 K. In order to investigate the physical mechanisms behind graphene-on-talc p-type doping, we performed first-principles calculations of their interface structural and electronic properties. In addition to potentially improving solar cell efficiency, graphene doping via van der Waals stacking is also a promising route towards controlling the band gap opening in bilayer graphene, promoting a steady n or p type doping in graphene and, eventually, providing a new path to access superconducting states in graphene, predicted to exist only at very high doping.

  19. Record power, ultra-broadband supercontinuum source based on highly GeO2 doped silica fiber

    DEFF Research Database (Denmark)

    Jain, Deepak; Sidharthan, R.; Moselund, Peter M.

    2016-01-01

    We demonstrate highly germania doped fibers for mid-infrared supercontinuum generation. Experiments ensure a highest output power of 1.44 W for a broadest spectrum from 700 nm to 3200 nm and 6.4 W for 800 nm to 2700 nm from these fibers, while being pumped by a broadband Erbium-Ytterbium doped fi...

  20. Synthesis and characterization of highly triboluminescent doped europium tetrakis compounds

    International Nuclear Information System (INIS)

    Fontenot, Ross S.; Hollerman, William A.; Bhat, Kamala N.; Aggarwal, Mohan D.

    2012-01-01

    One of the most intriguing properties involving crystals is their ability to emit light when fractured. While this property was discovered over 200 years ago, no one has ever been able to come up with a complete theory that can predict the physical principles associated with triboluminescence. However, this has not stopped scientists from coming up with various uses for these materials. One such application is to use these materials as the active element for smart impact sensors that can warn of catastrophic impacts. If these sensors are to become a reality however, the material must emit a bright light when fractured. One of the brightest triboluminescent materials found thus far is europium dibenzoylmethide triethylammonium (EuD 4 TEA). This material was discovered by Hurt in 1966 and is bright enough to be seen in daylight. In 2011, the authors discovered that synthesizing EuD 4 TEA using europium nitrate instead of chloride significantly increased the triboluminescence yield and made the synthesis much easier and more consistent. However, to date, there are few investigations into the effects of dopants on the triboluminescence of EuD 4 TEA. This paper reports the investigation of the effects of various dopants on: (1) The triboluminescent light yield, (2) Crystal size and structure, (3) Synthesis time, and (4) Prompt decay time. Results show that inclusion of dopants during synthesis increases the triboluminescence emission of EuD 4 TEA by 55%, significantly reduces the synthesis time, and controls the decay time. All of these properties can be useful for constructing the first prototype of a customized impact sensor. - Highlights: ► Doped europium dibenzoylmethide triethylammonium (EuD 4 TEA) was synthesized. ► Effects of dopants was studied from EuD 4 TEA during low velocity (<10 m/s) impacts. ► The triboluminescent light yield, decay time, and synthesis time were measured. ► A specially-built drop tower was developed to measure triboluminescence

  1. High-efficiency 2 μm Tm-doped fiber laser

    International Nuclear Information System (INIS)

    Dvornikov, D.

    2013-01-01

    Full text: Tm doped fiber laser operating in so called 'eye safe' wavelength region and designed in a MOPA configuration has been demonstrated. Large-mode-area fiber design and availability of high-brightness, high-power pump diodes at 795 nm made possible maximum output power of 25 W achieved at incident pump power of 72 W resulting in optical conversion efficiency about 35%. An important factor that led to an interest in 2 μm Tm-doped lasers is significantly broader spectral tunability of Tm-doped fibers compared to Yb-doped fibers, spanning wavelengths from below 1850 nm to beyond 2100 nm, corresponding to more than 200 nm of available bandwidth. This wavelength region covers the water absorption peaks around 1940 nm, making these lasers a valuable tool for precise medical procedures including noninvasive surgery, as well as several atmospheric transmission windows that are useful for remote sensing, laser radar and range-finding. This work was carried out as part of the EU funded Joint Operational Programme 'Black Sea Basin 2007-2013' and project 2.2.1.74459.339, MIS-ETC 1443 'Research networking for the environmental monitoring and mitigation of adverse ecological effects in the Black Sea Basin (BSB Net-Eco)'.

  2. Evolution of electronic structure in highly charge doped MoS2 compounds

    Science.gov (United States)

    Bin Subhan, Mohammed; Watson, Matthew; Liu, Zhongkai; Walters, Andrew; Hoesch, Moritz; Howard, Chris; Diamond I05 beamline Collaboration

    Transition-metal dichalcogenides (TMDCs) are a group of layered materials that exhibit a rich array of electronic ground states including semiconductivity, metallicity, superconductivity and charge density waves. In recent years, 2D TMDCs have attracted considerable attention due to their unique properties and potential applications in optoelectronics. It has been shown that the charge carrier density in few layer MoS2 can be tunably increased via electrostatic gating. At high levels of doping, MoS2 exhibits superconductivity with a dome-like dependence of Tc on doping analogous to that found in the cuprate superconductors. High doping can also be achieved via intercalation of alkali metals in bulk MoS2. The origin of this superconductivity is not yet fully understood with predictions ranging from exotic pairing mechanisms in bulk systems to Ising superconductivity in single layers. Despite these interesting properties, there has been limited research to date on the electronic structure of these doped compounds. Here we present our work on alkali metal intercalated MoS2 using the low temperature metal ammonia solution method. Using X-ray diffraction, Raman spectroscopy and ARPES measurements we will discuss the physical and electronic structure of these materials. EPSRC, Diamond Light Source.

  3. Yb-doped aluminophosphosilicate ternary fiber with high efficiency and excellent laser stability

    Science.gov (United States)

    Li, Yuwei; Peng, Kun; Zhan, Huan; Liu, Shuang; Ni, Li; Wang, Yuying; Yu, Juan; Wang, Xiaolong; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

    2018-03-01

    By using chelate precursor doping technique and traditional modified chemical vapor deposition system, we fabricated Yb-doped aluminophosphosilicate (Al2O3-P2O5-SiO2, ternary Yb-APS) large-mode-area fiber and reported on its laser performance. The fiber preform was doped with Al, P and Yb with concentration of ∼8000 ppm, ∼1700 ppm and ∼400 ppm in molar percent, respectively. Tested with master oscillator power amplifier system, the home-made Yb-APS fiber was found to present 1.02 kW at 1061.1 nm with a high slope efficiency of 81.2% and excellent laser stability with power fluctuation less than ±1.1% for over 10 h. Compared with Yb-doped aluminosilicate (Al2O3-SiO2, binary Yb-AS) fiber, the introduction of P2O5 effectively suppressed photodarkening effect even the P/Al ratio is much less than 1, indicating that Yb-APS fiber is a better candidate for high power fiber lasers.

  4. Production of medical radioisotopes in ORNL 86-Inch Cyclotron

    International Nuclear Information System (INIS)

    Skidmore, M.R.

    1975-01-01

    Procedures, targets, and costs are discussed for the production of iodine-123 at the ORNL 86-Inch Cyclotron. The cyclotron is a fixed frequency machine producing 22-MeV proton beams with currents of 3 mA. Flat plate targets are used in the bombardment of readily fabricated metals when highest production rates are necessary, while capsule targets are used when flat plate coatings are difficult or when high production rates are not required. Window targets with metal foils or powders, inorganic compounds, or isotopically enriched materials are also used. (PMA)

  5. High capacity and high rate capability of nitrogen-doped porous hollow carbon spheres for capacitive deionization

    International Nuclear Information System (INIS)

    Zhao, Shanshan; Yan, Tingting; Wang, Hui; Chen, Guorong; Huang, Lei; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong

    2016-01-01

    Graphical abstract: - Highlights: • The nitrogen-doped porous hollow carbon spheres were prepared. • The obtained materials have a good capacitive deionization performance. • The electrodes show high salt adsorption rate and good regeneration performance. - Abstract: In this work, nitrogen-doped porous hollow carbon spheres (N-PHCS) were well prepared by using polystyrene (PS) spheres as hard templates and dopamine hydrochloride as carbon and nitrogen sources. Field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate that the N-PHCS have a uniform, spherical and hollow structure. Nitrogen adsorption–desorption analysis shows that the N-PHCS have a high specific area of 512 m 2 /g. X-ray photoelectron spectroscopy result reveals that the nitrogen doping amount is 2.92%. The hollow and porous structure and effective nitrogen doping can contribute to large accessible surface area, efficient ion transport and good conductivity. In the electrochemical tests, we can conclude that the N-PHCS have a high specific capacitance value, a good stability and low inner resistance. The N-PHCS electrodes present a high salt adsorption capacity of 12.95 mg/g at a cell voltage of 1.4 V with a flow rate of 40 mL/min in a 500 mg/L NaCl aqueous solution. Moreover, the N-PHCS electrodes show high salt adsorption rate and good regeneration performance in the CDI process. With high surface specific area and effective nitrogen doping, the N-PHCS is promising to the CDI and other electrochemical applications.

  6. High capacity and high rate capability of nitrogen-doped porous hollow carbon spheres for capacitive deionization

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Shanshan; Yan, Tingting; Wang, Hui; Chen, Guorong; Huang, Lei; Zhang, Jianping; Shi, Liyi; Zhang, Dengsong, E-mail: dszhang@shu.edu.cn

    2016-04-30

    Graphical abstract: - Highlights: • The nitrogen-doped porous hollow carbon spheres were prepared. • The obtained materials have a good capacitive deionization performance. • The electrodes show high salt adsorption rate and good regeneration performance. - Abstract: In this work, nitrogen-doped porous hollow carbon spheres (N-PHCS) were well prepared by using polystyrene (PS) spheres as hard templates and dopamine hydrochloride as carbon and nitrogen sources. Field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate that the N-PHCS have a uniform, spherical and hollow structure. Nitrogen adsorption–desorption analysis shows that the N-PHCS have a high specific area of 512 m{sup 2}/g. X-ray photoelectron spectroscopy result reveals that the nitrogen doping amount is 2.92%. The hollow and porous structure and effective nitrogen doping can contribute to large accessible surface area, efficient ion transport and good conductivity. In the electrochemical tests, we can conclude that the N-PHCS have a high specific capacitance value, a good stability and low inner resistance. The N-PHCS electrodes present a high salt adsorption capacity of 12.95 mg/g at a cell voltage of 1.4 V with a flow rate of 40 mL/min in a 500 mg/L NaCl aqueous solution. Moreover, the N-PHCS electrodes show high salt adsorption rate and good regeneration performance in the CDI process. With high surface specific area and effective nitrogen doping, the N-PHCS is promising to the CDI and other electrochemical applications.

  7. Bismuth doping strategies in GeTe nanowires to promote high-temperature phase transition from rhombohedral to face-centered cubic structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jie; Huang, Rong; Wei, Fenfen; Cheng, Guosheng, E-mail: gscheng2006@sinano.ac.cn [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 398 Ruoshui Road, Suzhou Industrial Park, Jiangsu 215123 (China); University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049 (China); Kong, Tao [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 398 Ruoshui Road, Suzhou Industrial Park, Jiangsu 215123 (China)

    2014-11-17

    The phase transition of Bi-doped (∼3 at. %) GeTe nanowires from a rhombohedral (R) to a face-centered cubic (C) structure was observed in in situ high-temperature X-ray diffraction. The promotion of high-temperature R-C phase transition by a doping approach was revealed. Ab initio energy calculations of doped GeTe at various Bi doping concentrations were performed to interpret the promoted temperature-induced phase transitions. Those results indicated that the total energy differences between R and C structures of doped GeTe decreased as Bi doping concentrations increased, which facilitated R-C phase transitions.

  8. Bismuth doping strategies in GeTe nanowires to promote high-temperature phase transition from rhombohedral to face-centered cubic structure

    International Nuclear Information System (INIS)

    Zhang, Jie; Huang, Rong; Wei, Fenfen; Cheng, Guosheng; Kong, Tao

    2014-01-01

    The phase transition of Bi-doped (∼3 at. %) GeTe nanowires from a rhombohedral (R) to a face-centered cubic (C) structure was observed in in situ high-temperature X-ray diffraction. The promotion of high-temperature R-C phase transition by a doping approach was revealed. Ab initio energy calculations of doped GeTe at various Bi doping concentrations were performed to interpret the promoted temperature-induced phase transitions. Those results indicated that the total energy differences between R and C structures of doped GeTe decreased as Bi doping concentrations increased, which facilitated R-C phase transitions

  9. Highly efficient green light harvesting from Mg doped ZnO nanoparticles: Structural and optical studies

    International Nuclear Information System (INIS)

    Sharma, Sarla; Vyas, Rishi; Sharma, Neha; Singh, Vidyadhar; Singh, Arvind; Kataria, Vanjula; Gupta, Bipin Kumar; Vijay, Y.K.

    2013-01-01

    Graphical abstract: Demonstration of highly efficient green light emission harvesting from Mg doped ZnO nanoparticles were synthesized via facile wet chemical route with an average particle size ∼15 nm. The resulted nanoparticles exhibit intense green emission peaking at 530 nm upon 325 nm excitation. The photoluminescence (PL) intensity of visible emission depends upon the doping concentration of Mg. The PL intensity was found maximum up to 4% doping of Mg and beyond it exhibits a decrees in emission. The obtained highly luminescent green emission of ZnO nanoparticle would be an ultimate choice for next generation optoelectronics device materials. Highlights: ► Zn 1−x Mg x O nanoparticles were prepared by mechanochemical processing. ► High blue emission intensity was observed contrary to previous reports. ► Blue emission is suggested to be originating from the high density of defects. ► Defect density in as-milled condition is very high resulting in high emission. ► Mg promoted non-radiative recombination and lowered intensities. -- Abstract: Highly efficient green light emission was observed from Mg doped ZnO nanoparticles synthesized via facile wet chemical route with an average particle size ∼15 nm. The XRD analysis confirmed the growth of wurtzite phase of ZnO nanoparticles. Moreover, the optical properties of these nanoparticles were investigated by different spectroscopic techniques. The resulted nanoparticles exhibit intense green emission peaking at 530 nm (2.34 eV) upon 325 nm (3.81 eV) excitation. The photoluminescence (PL) intensity of visible emission depends upon the doping concentration of Mg. The PL intensity was found maximum up to 4% doping of Mg, and beyond it exhibits a decrees in emission. Furthermore, by varying the band gap from 3.50 to 3.61 eV, the PL spectra showed a near band edge (NBE) emission at wavelength around 370 nm (3.35 eV) and a broad deep level emission in the visible region. The obtained highly luminescent green

  10. Enhancement of polymer electronics via surface states on highly doped polymeric anodes

    International Nuclear Information System (INIS)

    Frohne, Holger; McNeill, Christopher R; Wallace, Gordon G; Dastoor, Paul C

    2004-01-01

    Organic optoelectronic devices that can be operated as organic light-emitting diodes and solar cells have been prepared using a poly(phenylenevinylene) (PPV)-based polymer as the active layer. Poly(3,4-ethylenedioxythiophene) (PEDOT) was grown potentiostatically atop indium-tin oxide to serve as the hole-injecting/collecting electrode, and its work function (Φ W ) was pre-adjusted by electrochemically altering the doping level. Subsequent controlled exposure to atmosphere produced devices with approximately constant open-circuit voltages consistent with the creation of an air-induced interfacial layer atop the PEDOT, which determines its Fermi level. The short-circuit current of the air-exposed devices was still found to vary systematically with Φ W . This interpretation is supported by UV/Vis investigations as well as electric force microscopy and Kelvin probe measurements of the surfaces of doped and non-doped PEDOT layers, which show very little difference in their surface potential after exposure to air, even though their optical spectra differ significantly. Using this new approach means that it is now possible to dope the PEDOT to high levels (thus maximizing its conductivity) without electrochemically altering the overlying PPV-based polymer layer

  11. Facile preparation of nitrogen-doped hierarchical porous carbon with high performance in supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Kun [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050 (China); Kong, Ling-Bin, E-mail: konglb@lut.cn [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050 (China); School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China); Shen, Kui-Wen; Dai, Yan-Hua; Shi, Ming; Hu, Bing [State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050 (China); Luo, Yong-Chun; Kang, Long [School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050 (China)

    2016-02-28

    Graphical abstract: Preparing and activating process of nitrogen-doped hierarchical porous carbon (NHPC). - Highlights: • The well-defined PAN-b-PMMA copolymer was synthesized by atom transfer radical polymerization with narrow molecular weight distribution. • Nitrogen-doped hierarchical porous structure (NHPC) was prepared through a simple carbonization procedure of PAN-b-PMMA precursor. • NHPC possessed hierarchical porous structure with high BET surface area of 257 m{sup 2} g{sup −1} and DFT mesopore size of 14.61 nm. • Effects of activation conditions on supercapacitive behavior were systematically studied. - Abstract: The nitrogen-doped hierarchical porous carbon (NHPC) material was successfully prepared through a simple carbonization procedure of well-defined diblock copolymer precursor containing nitrogen-enriched carbon source, i.e., polyacrylonitrile (PAN), and asacrificial block, i.e., polymethylmethacrylate (PMMA). PAN-b-PMMA diblock copolymer was synthesized by atom transfer radical polymeriation (ATRP) with narrow molecular weight distribution. The as-obtained NHPC possessed nitrogen-doped hierarchical porous structure with high BET surface area of 257 m{sup 2} g{sup −1} and Nonlocal density functional theory (NLDFT) mesopore size of 14.61 nm. Surface activated nitrogen-doped hierarchical porous carbon (A-NHPC) materials were obtained by subsequent surface activation with HNO{sub 3} solution. The effects of activation conditions on supercapacitive behavior were systematically studied, a maximum specific capacitance of 314 F g{sup −1} at a current density of 0.5 A g{sup −1} was achieved in 2 M KOH aqueous electrolyte. Simultaneously, it exhibited excellent rate capability of 67.8% capacitance retention as the current density increased from 0.5 to 20 A g{sup −1} and superior cycling performance of 90% capacitance retention after 10,000 cycles at the current density of 2 A g{sup −1}.

  12. Spectroscopic XPEEM of highly conductive SI-doped GaN wires

    Energy Technology Data Exchange (ETDEWEB)

    Renault, O., E-mail: olivier.renault@cea.fr [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Morin, J. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Tchoulfian, P. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); CNRS, Inst. NEEL, F-38042 Grenoble (France); Chevalier, N. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Feyer, V. [Peter Grünberg Institute (PGI-6) and JARA-FIT, Research Center Jülich, D-52425 Jülich (Germany); Pernot, J. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CNRS, Inst. NEEL, F-38042 Grenoble (France); Institut Universitaire de France, F-75005 Paris (France); Schneider, C.M. [Peter Grünberg Institute (PGI-6) and JARA-FIT, Research Center Jülich, D-52425 Jülich (Germany)

    2015-12-15

    Using soft X-ray photoelectron emission microscopy (XPEEM), complemented by scanning Auger microscopy (SAM) and scanning capacitance microscopy, we have quantitatively studied the incorporation of silicon and band bending at the surface (m-facet) of an individual, highly conductive Si-doped GaN micro-wires (Tchoulfian et al., Applied Physics Letters 102 (12), 2013). Electrically active n-dopants Si atoms in Ga interstitial sites are detected as nitride bonding states in the high-resolution Si2p core level spectra, and represent only a small fraction (<10%) of the overall Si surface concentration measured by SAM. The derived carrier concentration of 2×10{sup 21} at cm{sup −3} is in reasonable agreement with electrical measurements. A consistent surface band bending of ~1 eV is directly evidenced by surface photo-voltage measurements. Such an approach combining different surface-sensitive microscopies is of interest for studying other heavily doped semiconducting wires. - Highlights: • XPEEM analysis of state-of-the-art, heavily doped GaN wires with insights on the issue of the origin of the increased conductivity. • Combined microscopic approach with Scanning Auger microscopy and X-ray Photoeletron Emission Microscopy, to quantity the electrically active Si-dopants in GaN. • The determined concentration is found in reasonable agreement with the one derived from bulk electrical measurements. • The proposed method is of interest for studying the electronics and chemistry of doping in other heavily doped semiconducting wires.

  13. Coilable single crystal fibers of doped-YAG for high power laser applications

    Science.gov (United States)

    Maxwell, Gisele; Soleimani, Nazila; Ponting, Bennett; Gebremichael, Eminet

    2013-05-01

    Single crystal fibers are an intermediate between laser crystals and doped glass fibers. They can combine the advantages of both by guiding laser light and matching the efficiencies found in bulk crystals, making them ideal candidates for high-power laser and fiber laser applications. In particular, a very interesting feature of single crystal fiber is that they can generate high power in the eye-safe range (Er:YAG) with a high efficiency, opening new possibilities for portable directed energy weapons. This work focuses on the growth of a flexible fiber with a core of dopant (Er, Nd, Yb, etc…) that will exhibit good waveguiding properties. Direct growth or a combination of growth and cladding experiments are described. We have, to date, demonstrated the growth of a flexible foot long 45 microns doped YAG fiber. Scattering loss measurements at visible wavelengths along with dopant profile characterization are also presented. Laser characterization for these fibers is in progress.

  14. Doping in sport: Attitudes, beliefs and knowledge of competitive high ...

    African Journals Online (AJOL)

    South African TuksSport academy athletes at the High Performance Centre, University of Pretoria, and competitive high-school athletes at four private high schools in Gauteng completed the survey. A selfdetermined, structured questionnaire was used to establish the attitudes, beliefs and knowledge of the athletes. Results.

  15. Highly effective catalytic peroxymonosulfate activation on N-doped mesoporous carbon for o-phenylphenol degradation.

    Science.gov (United States)

    Hou, Jifei; Yang, Shasha; Wan, Haiqin; Fu, Heyun; Qu, Xiaolei; Xu, Zhaoyi; Zheng, Shourong

    2018-04-01

    As a broad-spectrum preservative, toxic o-phenylphenol (OPP) was frequently detected in aquatic environments. In this study, N-doped mesoporous carbon was prepared by a hard template method using different nitrogen precursors and carbonization temperatures (i.e., 700, 850 and 1000 °C), and was used to activate peroxymonosulfate (PMS) for OPP degradation. For comparison, mesoporous carbon (CMK-3) was also prepared. Characterization results showed that the N-doped mesoporous carbon samples prepared under different conditions were perfect replica of their template. In comparison with ethylenediamine (EDA) and dicyandiamide (DCDA) as the precursors, N-doped mesoporous carbon prepared using EDA and carbon tetrachloride as the precursors displayed a higher catalytic activity for OPP degradation. Increasing carbonization temperature of N-doped mesoporous carbon led to decreased N content and increased graphitic N content at the expense of pyridinic and pyrrolic N. Electron paramagnetic resonance (EPR) analysis showed that PMS activation on N-doped mesoporous carbon resulted in highly active species and singlet oxygen, and catalytic PMS activation for OPP degradation followed a combined radical and nonradical reaction mechanism. Increasing PMS concentration enhanced OPP degradation, while OPP degradation rate was independent on initial OPP concentration. Furthermore, the dependency of OPP degradation on PMS concentration followed the Langmuir-Hinshelwood model, reflecting that the activation of adsorbed PMS was the rate controlling step. Based on the analysis by time-of-flight mass spectrometry, the degradation pathway of OPP was proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Highly conducting and crystalline doubly doped tin oxide films fabricated using a low-cost and simplified spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Ravichandran, K., E-mail: kkr1365@yahoo.co [P.G. and Research Department of Physics, AVVM. Sri Pushpum College, Poondi, Thanjavur District, Tamil Nadu 613503 (India); Muruganantham, G.; Sakthivel, B. [P.G. and Research Department of Physics, AVVM. Sri Pushpum College, Poondi, Thanjavur District, Tamil Nadu 613503 (India)

    2009-11-15

    Doubly doped (simultaneous doping of antimony and fluorine) tin oxide films (SnO{sub 2}:Sb:F) have been fabricated by employing an inexpensive and simplified spray technique using perfume atomizer from aqueous solution of SnCl{sub 2} precursor. The structural studies revealed that the films are highly crystalline in nature with preferential orientation along the (2 0 0) plane. It is found that the size of the crystallites of the doubly doped tin oxide films is larger (69 nm) than that (27 nm) of their undoped counterparts. The dislocation density of the doubly doped film is lesser (2.08x10{sup 14} lines/m{sup 2}) when compared with that of the undoped film (13.2x10{sup 14} lines/m{sup 2}), indicating the higher degree of crystallinity of the doubly doped films. The SEM images depict that the films are homogeneous and uniform. The optical transmittance in the visible range and the optical band gap of the doubly doped films are 71% and 3.56 eV respectively. The sheet resistance (4.13 OMEGA/square) attained for the doubly doped film in this study is lower than the values reported for spray deposited fluorine or antimony doped tin oxide films prepared from aqueous solution of SnCl{sub 2} precursor (without using methanol or ethanol).

  17. Highly doped InP as a low loss plasmonic material for mid-IR region.

    Science.gov (United States)

    Panah, M E Aryaee; Takayama, O; Morozov, S V; Kudryavtsev, K E; Semenova, E S; Lavrinenko, A V

    2016-12-12

    We study plasmonic properties of highly doped InP in the mid-infrared (IR) range. InP was grown by metal-organic vapor phase epitaxy (MOVPE) with the growth conditions optimized to achieve high free electron concentrations by doping with silicon. The permittivity of the grown material was found by fitting the calculated infrared reflectance spectra to the measured ones. The retrieved permittivity was then used to simulate surface plasmon polaritons (SPPs) propagation on flat and structured surfaces, and the simulation results were verified in direct experiments. SPPs at the top and bottom interfaces of the grown epilayer were excited by the prism coupling. A high-index Ge hemispherical prism provides efficient coupling conditions of SPPs on flat surfaces and facilitates acquiring their dispersion diagrams. We observed diffraction into symmetry-prohibited diffraction orders stimulated by the excitation of surface plasmon-polaritons in a periodically structured epilayer. Characterization shows good agreement between the theory and experimental results and confirms that highly doped InP is an effective plasmonic material aiming it for applications in the mid-IR wavelength range.

  18. High-power Yb-doped continuous-wave and pulsed fibre lasers

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... becomes a critical issue in scaling high output power from Yb-doped double clad fibres. Since polymer coating is used to .... Techniques to exploit self-pulsing to achieve reg- ular narrow pulses with .... a single order if the beam is incident at an angle equal to the Bragg angle (θB) given by sin θB = λ0. 2n0.

  19. High Mobility of Graphene-Based Flexible Transparent Field Effect Transistors Doped with TiO2 and Nitrogen-Doped TiO2.

    Science.gov (United States)

    Wu, Yu-Hsien; Tseng, Po-Yuan; Hsieh, Ping-Yen; Chou, Hung-Tao; Tai, Nyan-Hwa

    2015-05-13

    Graphene with carbon atoms bonded in a honeycomb lattice can be tailored by doping various species to alter the electrical properties of the graphene for fabricating p-type or n-type field-effect transistors (FETs). In this study, large-area and single-layer graphene was grown on electropolished Cu foil using the thermal chemical vapor deposition method; the graphene was then transferred onto a poly(ethylene terephthalate) (PET) substrate to produce flexible, transparent FETs. TiO2 and nitrogen-doped TiO2 (N-TiO2) nanoparticles were doped on the graphene to alter its electrical properties, thereby enhancing the carrier mobility and enabling the transistors to sense UV and visible light optically. The results indicated that the electron mobility of the graphene was 1900 cm(2)/(V·s). Dopings of TiO2 and N-doped TiO2 (1.4 at. % N) lead to n-type doping effects demonstrating extremely high carrier mobilities of 53000 and 31000 cm(2)/(V·s), respectively. Through UV and visible light irradiation, TiO2 and N-TiO2 generated electrons and holes; the generated electrons transferred to graphene channels, causing the FETs to exhibit n-type electric behavior. In addition, the Dirac points of the graphene recovered to their original state within 5 min, confirming that the graphene-based FETs were photosensitive to UV and visible light. In a bending state with a radius of curvature greater than 2.0 cm, the carrier mobilities of the FETs did not substantially change, demonstrating the application possibility of the fabricated graphene-based FETs in photosensors.

  20. Sulfur-doped ordered mesoporous carbon with high electrocatalytic activity for oxygen reduction

    International Nuclear Information System (INIS)

    Wang, Huan; Bo, Xiangjie; Zhang, Yufan; Guo, Liping

    2013-01-01

    Highlights: • Synthesis of novel sulfur-doped ordered mesoporous carbon (OMC-S). • OMC-S as metal-free electrocatalyst for ORR. • High electrocatalytic activity and excellent tolerance to crossover effect. • Sulfide groups (-C-S-C-) playing an important role in promoting ORR. -- Abstract: Sulfur-doped ordered mesoporous carbons (OMC-S-X) (X = 1, 2 and 3) with different sulfur contents were synthesized as metal-free electrocatalyst for oxygen reduction reaction (ORR). Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectra (EDX), nitrogen adsorption–desorption, X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS) were employed to confirm the characterizations of OMC and OMC-S. The prepared OMC-S-3 exhibits high electrocatalytic activity, good stability and excellent tolerance to crossover effect for ORR. The high electrocatalytic activity of OMC-S-3 for ORR can be mainly ascribed to the doping of sulfur especially the existence of sulfide groups (-C-S-C-) which play an important role in promoting the ORR

  1. High critical currents in heavily doped (Gd,Y)Ba2Cu3Ox superconductor tapes

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V; Gharahcheshmeh, MH; Xu, A; Galstyan, E; Delgado, L; Cantoni, C

    2015-01-19

    REBa2Cu3Ox ((REBCO), RE = rare earth) superconductor tapes with moderate levels of dopants have been optimized for high critical current density in low magnetic fields at 77 K, but they do not exhibit exemplary performance in conditions of interest for practical applications, i.e., temperatures less than 50K and fields of 2-30 T. Heavy doping of REBCO tapes has been avoided by researchers thus far due to deterioration in properties. Here, we report achievement of critical current densities (J(c)) above 20 MA/cm(2) at 30 K, 3 T in heavily doped (25 mol.% Zr-added) (Gd,Y)Ba2Cu3Ox superconductor tapes, which is more than three times higher than the J(c) typically obtained in moderately doped tapes. Pinning force levels above 1000 GN/m(3) have also been attained at 20 K. A composition map of lift factor in J(c) (ratio of J(c) at 30 K, 3 T to the J(c) at 77 K, 0 T) has been developed which reveals the optimum film composition to obtain lift factors above six, which is thrice the typical value. A highly c-axis aligned BaZrO3 (BZO) nanocolumn defect density of nearly 7 x 10(11) cm(-2) as well as 2-3 nm sized particles rich in Cu and Zr have been found in the high J(c) films. (C) 2015 AIP Publishing LLC.

  2. Stable high efficiency two-dimensional perovskite solar cells via cesium doping

    KAUST Repository

    Zhang, Xu

    2017-08-15

    Two-dimensional (2D) organic-inorganic perovskites have recently emerged as one of the most important thin-film solar cell materials owing to their excellent environmental stability. The remaining major pitfall is their relatively poor photovoltaic performance in contrast to 3D perovskites. In this work we demonstrate cesium cation (Cs) doped 2D (BA)(MA)PbI perovskite solar cells giving a power conversion efficiency (PCE) as high as 13.7%, the highest among the reported 2D devices, with excellent humidity resistance. The enhanced efficiency from 12.3% (without Cs) to 13.7% (with 5% Cs) is attributed to perfectly controlled crystal orientation, an increased grain size of the 2D planes, superior surface quality, reduced trap-state density, enhanced charge-carrier mobility and charge-transfer kinetics. Surprisingly, it is found that the Cs doping yields superior stability for the 2D perovskite solar cells when subjected to a high humidity environment without encapsulation. The device doped using 5% Cs degrades only ca. 10% after 1400 hours of exposure in 30% relative humidity (RH), and exhibits significantly improved stability under heating and high moisture environments. Our results provide an important step toward air-stable and fully printable low dimensional perovskites as a next-generation renewable energy source.

  3. 3D Polyaniline Architecture by Concurrent Inorganic and Organic Acid Doping for Superior and Robust High Rate Supercapacitor Performance.

    Science.gov (United States)

    Gawli, Yogesh; Banerjee, Abhik; Dhakras, Dipti; Deo, Meenal; Bulani, Dinesh; Wadgaonkar, Prakash; Shelke, Manjusha; Ogale, Satishchandra

    2016-02-12

    A good high rate supercapacitor performance requires a fine control of morphological (surface area and pore size distribution) and electrical properties of the electrode materials. Polyaniline (PANI) is an interesting material in supercapacitor context because it stores energy Faradaically. However in conventional inorganic (e.g. HCl) acid doping, the conductivity is high but the morphological features are undesirable. On the other hand, in weak organic acid (e.g. phytic acid) doping, interesting and desirable 3D connected morphological features are attained but the conductivity is poorer. Here the synergy of the positive quality factors of these two acid doping approaches is realized by concurrent and optimized strong-inorganic (HCl) and weak-organic (phytic) acid doping, resulting in a molecular composite material that renders impressive and robust supercapacitor performance. Thus, a nearly constant high specific capacitance of 350 F g(-1) is realized for the optimised case of binary doping over the entire range of 1 A g(-1) to 40 A g(-1) with stability of 500 cycles at 40 A g(-1). Frequency dependant conductivity measurements show that the optimized co-doped case is more metallic than separately doped materials. This transport property emanates from the unique 3D single molecular character of such system.

  4. High Quality Manganese-Doped Zinc Sulfide Quantum Rods with Tunable Dual-Color and Multi-Photon Emissions

    Science.gov (United States)

    Deng, Zhengtao; Tong, Ling; Flores, Marco; Lin, Su; Cheng, Ji-Xin; Yan, Hao; Liu, Yan

    2011-01-01

    We report a simple, fast and green phosphine-free colloidal chemistry to synthesize high quality wurtzite-type Mn-doped ZnS quantum rods (QRs) with tunable diameters (1.6 nm to 5.6 nm), high aspect ratios (up to 50), variable Mn doping levels (0.18% to 1.60%), and high quantum yields (up to 45%). The electron paramagnetic resonance (EPR) spectra with modeling reveal the successful doping of paramagnetic Mn2+ ions in the host ZnS QRs. The Mn-doped ZnS QRs demonstrate tunable dual color (orange and blue) emissions by tuning the doping levels and UV excitation wavelengths. The orange emission with long decay lifetime (3.3 millisecond) originates from the doped Mn2+ states, while the blue emission with fast decay lifetime (0.31 nanosecond) is attributed to the QR surface states. The bright two- and three-photon excitation upconversion luminescence (2PL and 3PL) from the Mn-doped ZnS QRs have been observed using tunable near-infrared (NIR) femtosecond (fs) laser. Our strategy provides a versatile route to programmably control the optical properties of anisotropic semiconductor nanomaterials, which may create new opportunities for photonic devices and bioimaging applications. PMID:21405017

  5. All-Solid-State Drivers for High Power Excimer Lasers Used in Projection Gas Immersion Laser Doping

    National Research Council Canada - National Science Library

    Jacob, Jonah

    2001-01-01

    The objective of this SBIR program is to develop all-solid-state pulsed modulators to drive the high power excimer lasers required to commercialize the Projection Gas Immersion Laser Doping (P-GILD) process...

  6. Nitrogen-doped graphene-wrapped iron nanofragments for high-performance oxygen reduction electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jang Yeol [Korea Institute of Science and Technology, Photo-Electronic Hybrid Research Center (Korea, Republic of); Kim, Na Young [Korea Institute of Science and Technology, Fuel Cell Research Center (Korea, Republic of); Shin, Dong Yun [Chungbuk National University, Department of Environmental Engineering (Korea, Republic of); Park, Hee-Young [Korea Institute of Science and Technology, Fuel Cell Research Center (Korea, Republic of); Lee, Sang-Soo [Korea Institute of Science and Technology, Photo-Electronic Hybrid Research Center (Korea, Republic of); Joon Kwon, S. [Korea Institute of Science and Technology, Nanophotonics Research Center (Korea, Republic of); Lim, Dong-Hee [Chungbuk National University, Department of Environmental Engineering (Korea, Republic of); Bong, Ki Wan [Korea University, Department of Chemical and Biological Engineering (Korea, Republic of); Son, Jeong Gon, E-mail: jgson@kist.re.kr [Korea Institute of Science and Technology, Photo-Electronic Hybrid Research Center (Korea, Republic of); Kim, Jin Young, E-mail: jinykim@kist.re.kr [Korea Institute of Science and Technology, Fuel Cell Research Center (Korea, Republic of)

    2017-03-15

    Transition metals, such as iron (Fe)- or cobalt (Co)-based nanomaterials, are promising electrocatalysts for oxygen reduction reactions (ORR) in fuel cells due to their high theoretical activity and low cost. However, a major challenge to using these metals in place of precious metal catalysts for ORR is their low efficiency and poor stability, thus new concepts and strategies should be needed to address this issue. Here, we report a hybrid aciniform nanostructures of Fe nanofragments embedded in thin nitrogen (N)-doped graphene (Fe@N-G) layers via a heat treatment of graphene oxide-wrapped iron oxide (Fe{sub 2}O{sub 3}) microparticles with melamine. The heat treatment leads to transformation of Fe{sub 2}O{sub 3} microparticles to nanosized zero-valent Fe fragments and formation of core-shell structures of Fe nanofragments and N-doped graphene layers. Thin N-doped graphene layers massively promote electron transfer from the encapsulated metals to the graphene surface, which efficiently optimizes the electronic structure of the graphene surface and thereby triggers ORR activity at the graphene surface. With the synergistic effect arising from the N-doped graphene and Fe nanoparticles with porous aciniform nanostructures, the Fe@N-G hybrid catalyst exhibits high catalytic activity, which was evidenced by high E{sub 1/2} of 0.82 V, onset potential of 0.93 V, and limiting current density of 4.8 mA cm{sup −2} indicating 4-electron ORR, and even exceeds the catalytic stability of the commercial Pt catalyst.

  7. Nitrogen-doped graphene-wrapped iron nanofragments for high-performance oxygen reduction electrocatalysts

    Science.gov (United States)

    Lee, Jang Yeol; Kim, Na Young; Shin, Dong Yun; Park, Hee-Young; Lee, Sang-Soo; Joon Kwon, S.; Lim, Dong-Hee; Bong, Ki Wan; Son, Jeong Gon; Kim, Jin Young

    2017-03-01

    Transition metals, such as iron (Fe)- or cobalt (Co)-based nanomaterials, are promising electrocatalysts for oxygen reduction reactions (ORR) in fuel cells due to their high theoretical activity and low cost. However, a major challenge to using these metals in place of precious metal catalysts for ORR is their low efficiency and poor stability, thus new concepts and strategies should be needed to address this issue. Here, we report a hybrid aciniform nanostructures of Fe nanofragments embedded in thin nitrogen (N)-doped graphene (Fe@N-G) layers via a heat treatment of graphene oxide-wrapped iron oxide (Fe2O3) microparticles with melamine. The heat treatment leads to transformation of Fe2O3 microparticles to nanosized zero-valent Fe fragments and formation of core-shell structures of Fe nanofragments and N-doped graphene layers. Thin N-doped graphene layers massively promote electron transfer from the encapsulated metals to the graphene surface, which efficiently optimizes the electronic structure of the graphene surface and thereby triggers ORR activity at the graphene surface. With the synergistic effect arising from the N-doped graphene and Fe nanoparticles with porous aciniform nanostructures, the Fe@N-G hybrid catalyst exhibits high catalytic activity, which was evidenced by high E1/2 of 0.82 V, onset potential of 0.93 V, and limiting current density of 4.8 mA cm-2 indicating 4-electron ORR, and even exceeds the catalytic stability of the commercial Pt catalyst.

  8. Structural stability of the smectite-doped lanthanum under high pressures and high temperatures

    International Nuclear Information System (INIS)

    Stefani, Vicente Fiorini

    2012-01-01

    Smectites are phyllosilicates that have a tetrahedron: octahedron structure ratio of 2:1, with high cation exchange capacity (CEC) in the interlayers. For these and other features, smectites have been used in many parts of the world as secondary barriers with the goal of containing a possible leak of radioactive elements in final disposal facilities for radioactive waste through cation exchange. Our aim in this work is to reach the cation exchange in calcium montmorillonite (smectite dioctahedral) by lanthanum to simulate trivalent radionuclides and to study the stability of this structure under high pressure and high temperature. To achieve high pressure it was used two different technique: DAC (Diamond Anvil Cell), achieving pressures up to 12GPa at room temperature and hydraulic press with a toroidal chamber profile to achieve pressures up to 7,7GPa and temperatures up to 900 degree C. The heating is achieved simultaneously by an electric system coupled in the hydraulic press. The outcomes show that the smectite structure doped with lanthanum remains stable under 12GPa at room temperature and 2.5GPa at 200 degree C. However, above 300 degree C at 2.5GPa the structure becomes a new phase of muscovite-like, rich of La, where it loses its interlayer water and turns out to be irreversible. Furthermore, it is important to point out that the higher temperature the better ordered is the structure and it is still stable under 7.7GPa and 900 degree C. Moreover, after all experiments the structure continues being dioctahedral. The new phase of muscovite-like, rich of La, in contact with a calcium solution remains partially unchanged, whereas the other part returns to the original structure (montmorillonite-Ca). The following analyses were performed: X-ray diffraction (XRD) for evaluating the spatial structure; Fourier transform infrared spectroscopy (FTIR) for getting information about the vibrational modes; scanning electron microscopy with dispersive Xray spectroscopy

  9. A high-performance mesoporous carbon supported nitrogen-doped carbon electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Xu, Jingjing; Lu, Shiyao; Chen, Xu; Wang, Jianan; Zhang, Bo; Zhang, Xinyu; Xiao, Chunhui; Ding, Shujiang

    2017-12-01

    Investigating low-cost and highly active electrocatalysts for oxygen reduction reactions (ORR) is of crucial importance for energy conversion and storage devices. Herein, we design and prepare mesoporous carbon supported nitrogen-doped carbon by pyrolysis of polyaniline coated on CMK-3. This electrocatalyst exhibits excellent performance towards ORR in alkaline media. The optimized nitrogen-doped mesoporous electrocatalyst show an onset potential (E onset) of 0.95 V (versus reversible hydrogen electrode (RHE)) and half-wave potential (E 1/2) of 0.83 V (versus RHE) in 0.1 M KOH. Furthermore, the as-prepared catalyst presents superior durability and methanol tolerance compared to commercial Pt/C indicating its potential applications in fuel cells and metal-air batteries.

  10. Nitrogen Doped Macroporous Carbon as Electrode Materials for High Capacity of Supercapacitor

    Directory of Open Access Journals (Sweden)

    Yudong Li

    2017-01-01

    Full Text Available Nitrogen doped carbon materials as electrodes of supercapacitors have attracted abundant attention. Herein, we demonstrated a method to synthesize N-doped macroporous carbon materials (NMC with continuous channels and large size pores carbonized from polyaniline using multiporous silica beads as sacrificial templates to act as electrode materials in supercapacitors. By the nice carbonized process, i.e., pre-carbonization at 400 °C and then pyrolysis at 700/800/900/1000 °C, NMC replicas with high BET specific surface areas exhibit excellent stability and recyclability as well as superb capacitance behavior (~413 F ⋅ g−1 in alkaline electrolyte. This research may provide a method to synthesize macroporous materials with continuous channels and hierarchical pores to enhance the infiltration and mass transfer not only used as electrode, but also as catalyst somewhere micro- or mesopores do not work well.

  11. Optimization of TM-Doped Phosphosilicate Glass for High Power Fiber Lasers

    Science.gov (United States)

    2016-04-28

    phosphosilicate glass for high efficiency and low photo- darkening 4. Fabricate Tm-doped silica core glass with an index uniformity of < 5×10-5 and an index ...composition…………………………………………………………………………………………………………….……………….…….……. 8 6 Composition and refractive index of the fiber with Tm doping for checking...background loss (the first composition).……………………………………………………………….…………………………………………..…….…………….. 9 7 Composition and refractive index of a preform with

  12. Strain-induced extrinsic high-temperature ferromagnetism in the Fe-doped hexagonal barium titanate.

    Science.gov (United States)

    Zorko, A; Pregelj, M; Gomilšek, M; Jagličić, Z; Pajić, D; Telling, M; Arčon, I; Mikulska, I; Valant, M

    2015-01-09

    Diluted magnetic semiconductors possessing intrinsic static magnetism at high temperatures represent a promising class of multifunctional materials with high application potential in spintronics and magneto-optics. In the hexagonal Fe-doped diluted magnetic oxide, 6H-BaTiO3-δ, room-temperature ferromagnetism has been previously reported. Ferromagnetism is broadly accepted as an intrinsic property of this material, despite its unusual dependence on doping concentration and processing conditions. However, the here reported combination of bulk magnetization and complementary in-depth local-probe electron spin resonance and muon spin relaxation measurements, challenges this conjecture. While a ferromagnetic transition occurs around 700 K, it does so only in additionally annealed samples and is accompanied by an extremely small average value of the ordered magnetic moment. Furthermore, several additional magnetic instabilities are detected at lower temperatures. These coincide with electronic instabilities of the Fe-doped 3C-BaTiO3-δ pseudocubic polymorph. Moreover, the distribution of iron dopants with frozen magnetic moments is found to be non-uniform. Our results demonstrate that the intricate static magnetism of the hexagonal phase is not intrinsic, but rather stems from sparse strain-induced pseudocubic regions. We point out the vital role of internal strain in establishing defect ferromagnetism in systems with competing structural phases.

  13. Nano silver diffusion behaviour on conductive polymer during doping process for high voltage application

    Science.gov (United States)

    Mohammad, A.; Mahmood, A.; Chin, K. T.; Danquah, M. K.; van Stratan, S.

    2017-06-01

    Conductive polymer had opened a new era of engineering for microelectronics and semiconductor applications. However, it is still a challenge for high voltage applications due to lower electrical conductivity compare to metals. This results tremendous energy losses during transmission and restricts its usage. In order to address such problem a novel method was investigated using nano silver particle doped iodothiophene since silver is the highest electrical conductive material. The experiments were carried out to study the organometallic diffusion behaviour of nanosilver doped iodothiophene with different concentration of iodothiophene. Five different mixing ratio between nanosilver and the solution of iodothiophene dissolved in diethyl ether were used which are 1:1.25, 1:1.5, 1:2.5, 1:3 and l:5. It was revealed that there is an effective threshold concentration of which the nano silver evenly distributed and there was no coagulation observed. These parameters laid the foundation of better doping process between the nano silver and the polymer significantly which would contribute developing conductive polymer towards high voltage application for industries that are vulnerable to corrosive environment.

  14. Studies of High-T$_{c}$ Superconductors Doped with Radioactive Isotopes

    CERN Multimedia

    Alves, E J; Goncalves marques, J; Cardoso, S; Lourenco, A A; Sousa, J B

    2002-01-01

    %title\\\\ \\\\We propose to study High T$_{c} $ Superconductors~(HTSc) doped with radioactive elements at ISOLDE, in order to investigate some of the problems that persist after use of conventional characterization techniques. Three main topics are proposed: \\begin{enumerate} \\item Characterization of the order/disorder of Hg in the Hg-planes of the HTSc family Hg$_{1}$Ba$_{2}$R$_{(n-1)}$Cu$_{n}$O$_{(2n+2+\\delta)}$ (T$_{c}$ > 130 K) due to defects or impurities such as C and Au. \\item Studies of the doping of Infinite Layers Cuprates (RCuO$_{2}$)$_{n}$, R=Ca, Sr or Ba, using unstable nuclei of the alkaline-earth (IIA) group which decay to the alkaline nuclei (IA) group. The purpose is to introduce charge carriers in these materials by changing the valence of the cations during the nuclear transmutation. The possibility of using ion implantation to introduce directly an alkaline dopant will also be studied. \\item Studies of the Hg/Au doping of high quality YBa$_{2}$Cu$_{3}$O$_{6+x}$ thin films. We intend to chara...

  15. A new switching characteristics of highly doped multi-quantum well

    CERN Document Server

    Song, C K

    1999-01-01

    A new type of hysteretic current-voltage characteristics, which switched from a low conductance off-state into a high conductance on-state at a threshold voltage and the high conductance state was sustained even when the bias voltage reduced below the threshold voltage, was experimentally observed for the highly doped multi-quantum well structure. The characteristics were attributed to confinement of electrons and impact ionization of the confined electrons out of the quantum wells. The test devices employing 10 periods of quantum wells were fabricated by using AlGaAs/GaAs semiconductor heterostructure and I-V characteristics were examined.

  16. Highly conductive boron-doped hydrogenated microcrystalline silicon films obtained by hot wire deposition

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, W. [IEF5-Photovoltaik, Forschungszentrum Juelich (Germany); Malibu GmbH and Co. KG, Bielefeld (Germany); Carius, R.; Einsele, F.; Lennartz, D.; Niessen, L.; Pennartz, F. [IEF5-Photovoltaik, Forschungszentrum Juelich (Germany)

    2010-04-15

    The growth of highly conductive boron doped microcrystalline silicon by the hot wire method was studied. Various series of films were deposited to investigate the influence of the deposition parameters on conductivity, crystallinity and (void-related) microstructure. Maximum (room temperature) conductivities > 200 S/cm with carrier mobilities > 2.5 cm{sup 2}/Vs were achieved. While a high crystallinity is the major requirement for achieving high conductivities, the microstructure is also of influence. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Gd-Doped BaSnO3 Thin Films: High Mobility in a Magnetically-Doped Transparent Conducting Oxide

    Science.gov (United States)

    Alaan, Urusa; Shafer, Padraic; N'diaye, Alpha; Arenholz, Elke; Suzuki, Yuri

    It has recently been shown that when the perovskite-structure BaSnO3 (BSO) is doped with LaBa', the result is a transparent conducting oxide with room-temperature electron mobilities that are much higher than conventional ternary oxides. The ability to achieve high carrier mobilities in BSO is promising for future perovskite-structure devices. We have used pulsed laser deposition to grow epitaxial thin films of Ba0.96Gd0.04SnO3 (Gd:BSO) and Ba0.96La0.04SnO3 (La:BSO) on (001) SrTiO3 and (001) MgO substrates. At 300 K, Gd:BSO films have ρ ~2 m Ω .cm, μe ~28 cm2/V .s and n ~1.0 × 1020cm-3. At the same temperature, La:BSO films have ρ ~0.4 m Ω .cm, μe ~58 cm2/V .s and n ~2.5 × 1020 cm-3. While La:BSO is diamagnetic, Gd:BSO is paramagnetic with a clear magnetic response that saturates at ~7 μB/Gd3+, and a negative ordinary magnetoresistance at low temperatures. Like La:BSO, Gd:BSO is transparent and colorless in the visible regime. Thus, we have shown that Gd is good dopant for BSO in order to achieve transparency and metallicity that is coincident with a magnetic response. We acknowledge support from the Army Research Office under Grant # W911NF-14-1-0611, the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, and the National Science Foundation Graduate Research Fellowship Program.

  18. Highly doped ZnO films deposited by spray-pyrolysis. Design parameters for optoelectronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Garcés, F.A., E-mail: felipe.garces@santafe-conicet.gov.ar [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Budini, N. [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Schmidt, J.A.; Arce, R.D. [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829, Santa Fe S3000AOM (Argentina)

    2016-04-30

    Synthesis and preparation of ZnO films are relevant subjects for obtaining transparent and conducting layers with interesting applications in optoelectronics and photovoltaics. Optimization of parameters such as dopant type and concentration, deposition time and substrate temperature is important for obtaining ZnO layers with optimal properties. In this work we present a study about the induced effects of deposition time on optical and electrical properties of ZnO thin films. These films were deposited by spray pyrolysis of a suitable Zn precursor, obtained through the sol–gel method. The deposition time has direct incidence on internal stress in the crystal structure, generating defects that may affect transparency and electrical transport into the layers. We performed mosaicity measurements, through X-ray diffraction, and used it as a tool to get an insight on structural characteristics and homogeneity of ZnO layers. Also, through this technique, we analyzed thickness and doping effects on crystallinity and carrier transport properties. - Highlights: • Al-doped ZnO films with high conductivity and moderate Hall mobility were obtained. • Mosaicity between crystalline domains increased with film thickness. • Lattice parameters a and c diminished linearly as a function of Al concentration. • First steps for developing porous silicon/doped ZnO heterojunctions were presented.

  19. Highly doped ZnO films deposited by spray-pyrolysis. Design parameters for optoelectronic applications

    International Nuclear Information System (INIS)

    Garcés, F.A.; Budini, N.; Schmidt, J.A.; Arce, R.D.

    2016-01-01

    Synthesis and preparation of ZnO films are relevant subjects for obtaining transparent and conducting layers with interesting applications in optoelectronics and photovoltaics. Optimization of parameters such as dopant type and concentration, deposition time and substrate temperature is important for obtaining ZnO layers with optimal properties. In this work we present a study about the induced effects of deposition time on optical and electrical properties of ZnO thin films. These films were deposited by spray pyrolysis of a suitable Zn precursor, obtained through the sol–gel method. The deposition time has direct incidence on internal stress in the crystal structure, generating defects that may affect transparency and electrical transport into the layers. We performed mosaicity measurements, through X-ray diffraction, and used it as a tool to get an insight on structural characteristics and homogeneity of ZnO layers. Also, through this technique, we analyzed thickness and doping effects on crystallinity and carrier transport properties. - Highlights: • Al-doped ZnO films with high conductivity and moderate Hall mobility were obtained. • Mosaicity between crystalline domains increased with film thickness. • Lattice parameters a and c diminished linearly as a function of Al concentration. • First steps for developing porous silicon/doped ZnO heterojunctions were presented.

  20. High doping Nd:YAG transparent ceramics fabricated by solid-state reactive sintering

    International Nuclear Information System (INIS)

    Liu, Jing; Liu, Qiang; Cheng, Xiaonong; Li, Jiang; Ba, Xuewei; Liu, Wenbin; Kou, Huamin; Jiang, Benxue; Pan, Yubai; Guo, Jingkun

    2013-01-01

    Nd:YAG transparent ceramics with different doping concentrations were fabricated by a solid-state reaction method and vacuum sintering. Powder mixture of α-Al 2 O 3 , Y 2 O 3 , and Nd 2 O 3 doped with tetraethoxysilane (TEOS) and MgO were sintered between 1500 o C and 1750 o C to examine the densification behavior in Nd:YAG ceramics. For the high doping 5 at%Nd:YAG transparent ceramics, the sintering kinetics and microstructure evolution were mainly discussed. It is found that the optimal sintering temperature for 5.0 at%Nd:YAG ceramics was at ∝1700 o C, and the in-line transmittance increased with the increase of holding time. The best specimen with the holding time of 30h achieved 82.2% in transmittance at 1064nm, whose average grain size was ∝15μm. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. High-temperature thermoelectric properties of La-doped BaSnO3 ceramics

    International Nuclear Information System (INIS)

    Yasukawa, Masahiro; Kono, Toshio; Ueda, Kazushige; Yanagi, Hiroshi; Hosono, Hideo

    2010-01-01

    To elucidate the thermoelectric properties at high temperatures, perovskite-type La-doped BaSnO 3 ceramics were fabricated by a polymerized complex (PC) method and subsequent spark plasma sintering (SPS) technique. Fine powders of Ba 1-x La x SnO 3 (x = 0.00-0.07) were prepared by the PC method using citrate complexes, and SPS treatment converted the powders into dense ceramics with relative densities of 93-97%. The La content dependence of the lattice parameter suggested that the solubility of La for Ba sites was approximately x = 0.03. The temperature dependence of the electrical conductivity σ and Seebeck coefficient S showed that each La-doped ceramic was an n-type degenerate semiconductor in the measured temperature range of 373-1073 K. The La content dependence of the S values indicated that the electron carrier concentration increased successively up to x = 0.03, which was the solubility limit of the La atoms. The thermoelectric power factors S 2 σ increased drastically with La doping, and reached a maximum for x = 0.01 with values of 0.8 x 10 -4 W m -1 K -2 at 373 K to 2.8 x 10 -4 W m -1 K -2 at 1073 K.

  2. Nitrogen-doped carbon nanotubes with tunable structure and high yield produced by ultrasonic spray pyrolysis

    Science.gov (United States)

    Liu, Jian; Zhang, Yong; Ionescu, Mihnea Ioan; Li, Ruying; Sun, Xueliang

    2011-06-01

    Nitrogen-doped carbon nanotubes (CN x) were prepared by ultrasonic spray pyrolysis from mixtures of imidazole and acetonitrile. Imidazole, as an additive, was used to control the structure and nitrogen doping in CN x by adjusting its concentration in the mixtures. Scanning electron microscopy observation showed that the addition of imidazole increased the nanotube growth rate and yield, while decreased the nanotube diameter. Transmission electron microscopy study indicated that the addition of imidazole promoted the formation of a dense bamboo-like structure in CN x. X-ray photoelectron spectroscopy analysis demonstrated that the nitrogen content varied from 3.2 to 5.2 at.% in CN x obtained with different imidazole concentrations. Raman spectra study showed that the intensity ratio of D to G bands gradually increased, while that of 2D to G bands decreased, due to increasing imidazole concentration. The yield of CN x made from mixtures of imidazole and acetonitrile can reach 192 mg in 24 min, which is 15 times that of CN x prepared from only acetonitrile. The aligned CN x, with controlled nitrogen doping, tunable structure and high yield, may find applications in developing non-noble catalysts and novel catalyst supports for fuel cells.

  3. Significance of optimal N-doping in mesoporous carbon framework to achieve high specific capacitance

    Science.gov (United States)

    Sahoo, Malaya K.; Gogoi, Pranjal; Rajeshkhanna, G.; Chilukuri, Satyanarayana V.; Rao, G. Ranga

    2017-10-01

    Nitrogen-doped mesoporous carbon (NMC) has been synthesized by sol-gel process using a mixture of phenol and formaldehyde as source of carbon, and melamine as source of nitrogen. The Ludox-AS40 (40 wt% SiO2) is employed, for the first time, as hard template to obtain polymeric gel by prolonged heat treatment at 80 °C. The wt% of nitrogen is tuned by varying the weight ratio of melamine to phenol. Stable mesoporous carbon frameworks are obtained by pyrolysis of the dry gel at 800 °C in nitrogen atmosphere and treated with alkali to remove silica. One of the carbon framework samples has 11 wt% nitrogen doping and shows pore volume of 0.5 cm3 g-1 and surface area 609 m2 g-1. The other carbon frame work sample has 6 wt% nitrogen doping and shows higher pore volume of 1.1 cm3 g-1 and surface area 736 m2 g-1. The later sample exhibits highest electrochemical capacitance of 196 F g-1 at 0.5 A g-1 while the former shows only 146 F g-1 at 0.5 A g-1. However, both the NMC electrodes show good cyclic performance (91% of the initial capacitance after 1000 cycles) in an aqueous KOH electrolyte. This study demonstrates that there is an optimum level of nitrogen doping required to keep the meso-structure of carbon network intact, simultaneously maintaining high surface area and sufficient electrical conductivity for electrochemical applications.

  4. First-principles study on the effect of high In doping on the conductivity of ZnO

    International Nuclear Information System (INIS)

    Hou Qing-Yu; Li Ji-Jun; Ying Chun; Zhao Chun-Wang; Zhao Er-Jun; Zhang Yue

    2013-01-01

    Based on the density functional theory (DFT), using first-principles plane-wave ultrasoft pseudopotential method, the models of the unit cell of pure ZnO and two highly In-doped supercells of Zn 0.9375 In 0.0625 O and Zn 0.875 In 0.125 O are constructed, and the geometry optimizations of the three models are carried out. The total density of states (DOS) and the band structures (BS) are also calculated. The calculation results show that in the range of high doping concentration, when the doping concentration is hihger than a specific value, the conductivity decreases with the increase of the doping concentration of In in ZnO, which is in consistence with the change trend of the experimental results

  5. A high-performance supercapacitor electrode based on N-doped porous graphene

    Science.gov (United States)

    Dai, Shuge; Liu, Zhen; Zhao, Bote; Zeng, Jianhuang; Hu, Hao; Zhang, Qiaobao; Chen, Dongchang; Qu, Chong; Dang, Dai; Liu, Meilin

    2018-05-01

    The development of high-performance supercapacitors (SCs) often faces some contradictory and competing requirements such as excellent rate capability, long cycling life, and high energy density. One effective strategy is to explore electrode materials of high capacitance, electrode architectures of fast charge and mass transfer, and electrolytes of wide voltage window. Here we report a facile and readily scalable strategy to produce high-performance N-doped graphene with a high specific capacitance (∼390 F g-1). A symmetric SC device with a wide voltage window of 3.5 V is also successfully fabricated based on the N-doped graphene electrode. More importantly, the as-assembled symmetric SC delivers a high energy density of 55 Wh kg-1 at a power density of 1800 W kg-1 while maintaining superior cycling life (retaining 96.6% of the initial capacitance after 20,000 cycles). Even at a power density as high as 8800 W kg-1, it still retains an energy density of 29 Wh kg-1, higher than those of previously reported graphene-based symmetric SCs.

  6. Low Reflectivity and High Flexibility of Tin-Doped Indium Oxide Nanofiber Transparent Electrodes

    KAUST Repository

    Wu, Hui

    2011-01-12

    Tin-doped indium oxide (ITO) has found widespread use in solar cells, displays, and touch screens as a transparent electrode; however, two major problems with ITO remain: high reflectivity (up to 10%) and insufficient flexibility. Together, these problems severely limit the applications of ITO films for future optoelectronic devices. In this communication, we report the fabrication of ITO nanofiber network transparent electrodes. The nanofiber networks show optical reflectivity as low as 5% and high flexibility; the nanofiber networks can be bent to a radius of 2 mm with negligible changes in the sheet resistance. © 2010 American Chemical Society.

  7. Assessment of effect of Yb3+ ion pairs on a highly Yb-doped double-clad fibre laser

    Science.gov (United States)

    Vallés, J. A.; Martín, J. C.; Berdejo, V.; Cases, R.; Álvarez, J. M.; Rebolledo, M. Á.

    2018-03-01

    Using a previously validated characterization method based on the careful measurement of the characteristic parameters and fluorescence emission spectra of a highly Yb-doped double-clad fibre, we evaluate the contribution of ion pair induced processes to the output power of a double-clad Yb-doped fibre ring laser. This contribution is proved to be insignificant, contrary to analysis by other authors, who overestimate the role of ion pairs.

  8. Manganese oxide nanowires wrapped with nitrogen doped carbon layers for high performance supercapacitors.

    Science.gov (United States)

    Li, Ying; Mei, Yuan; Zhang, Lin-Qun; Wang, Jian-Hai; Liu, An-Ran; Zhang, Yuan-Jian; Liu, Song-Qin

    2015-10-01

    In this study, manganese oxide nanowires wrapped by nitrogen-doped carbon layers (MnO(x)@NCs) were prepared by carbonization of poly(o-phenylenediamine) layer coated onto MnO2 nanowires for high performance supercapacitors. The component and structure of the MnO(x)@NCs were controlled through carbonization procedure under different temperatures. Results demonstrated that this composite combined the high conductivity and high specific surface area of nitrogen-doped carbon layers with the high pseudo-capacitance of manganese oxide nanowires. The as-prepared MnO(x)@NCs exhibited superior capacitive properties in 1 M Na2SO4 aqueous solution, such as high conductivity (4.167×10(-3) S cm(-1)), high specific capacitance (269 F g(-1) at 10 mV s(-1)) and long cycle life (134 F g(-1) after 1200 cycles at a scan rate of 50 mV s(-1)). It is reckoned that the present novel hybrid nanowires can serve as a promising electrode material for supercapacitors and other electrochemical devices. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Highly Doped Phosphate Glass Fibers for Compact Lasers and Amplifiers: A Review

    Directory of Open Access Journals (Sweden)

    Nadia Giovanna Boetti

    2017-12-01

    Full Text Available In recent years, the exploitation of compact laser sources and amplifiers in fiber form has found extensive applications in industrial and scientific fields. The fiber format offers compactness, high beam quality through single-mode regime and excellent heat dissipation, thus leading to high laser reliability and long-term stability. The realization of devices based on this technology requires an active medium with high optical gain over a short length to increase efficiency while mitigating nonlinear optical effects. Multicomponent phosphate glasses meet these requirements thanks to the high solubility of rare-earth ions in their glass matrix, alongside with high emission cross-sections, chemical stability and high optical damage threshold. In this paper, we review recent advances in the field thanks to the combination of highly-doped phosphate glasses and innovative fiber drawing techniques. We also present the main performance achievements and outlook both in continuous wave (CW and pulsed mode regimes.

  10. Seismic fragility test of a 6-inch diameter pipe system

    International Nuclear Information System (INIS)

    Chen, W.P.; Onesto, A.T.; DeVita, V.

    1987-02-01

    This report contains the test results and assessments of seismic fragility tests performed on a 6-inch diameter piping system. The test was funded by the US Nuclear Regulatory Commission (NRC) and conducted by ETEC. The objective of the test was to investigate the ability of a representative nuclear piping system to withstand high level dynamic seismic and other loadings. Levels of loadings achieved during seismic testing were 20 to 30 times larger than normal elastic design evaluations to ASME Level D limits would permit. Based on failure data obtained during seismic and other dynamic testing, it was concluded that nuclear piping systems are inherently able to withstand much larger dynamic seismic loadings than permitted by current design practice criteria or predicted by the probabilistic risk assessment (PRA) methods and several proposed nonlinear methods of failure analysis

  11. High-efficiency white organic light-emitting devices with a non-doped yellow phosphorescent emissive layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Juan; Yu Junsheng, E-mail: jsyu@uestc.edu.cn; Hu Xiao; Hou Menghan; Jiang Yadong

    2012-03-30

    Highly efficient phosphorescent white organic light-emitting devices (PHWOLEDs) with a simple structure of ITO/TAPC (40 nm)/mCP:FIrpic (20 nm, x wt.%)/bis[2-(4-tertbutylphenyl)benzothiazolato-N,C{sup 2} Prime ] iridium (acetylacetonate) (tbt){sub 2}Ir(acac) (y nm)/Bphen (30 nm)/Mg:Ag (200 nm) have been developed, by inserting a thin layer of non-doped yellow phosphorescent (tbt){sub 2}Ir(acac) between doped blue emitting layer (EML) and electron transporting layer. By changing the doping concentration of the blue EML and the thickness of the non-doped yellow EML, a PHWOLED comprised of higher blue doping concentration and thinner yellow EML achieves a high current efficiency of 31.7 cd/A and Commission Internationale de l'Eclairage coordinates of (0.33, 0.41) at a luminance of 3000 cd/m{sup 2} could be observed. - Highlights: Black-Right-Pointing-Pointer We introduce a simplified architecture for phosphorescent white organic light-emitting device. Black-Right-Pointing-Pointer The key concept of device fabrication is combination of doped blue emissive layer (EML) with non-doped ultra-thin yellow EML. Black-Right-Pointing-Pointer Doping concentration of the blue EML and thickness of the yellow EML are sequentially adjusted. Black-Right-Pointing-Pointer High device performance is achieved due to improved charge carrier balance as well as two parallel emission mechanisms in the EMLs.

  12. Graphene quantum-dot-doped polypyrrole counter electrode for high-performance dye-sensitized solar cells.

    Science.gov (United States)

    Chen, Lijia; Guo, Chun Xian; Zhang, Qiaoming; Lei, Yanlian; Xie, Jiale; Ee, Shujing; Guai, Guanhong; Song, Qunliang; Li, Chang Ming

    2013-03-01

    Herein graphene quantum dot (GQD), a graphene material with lateral dimension less than 100 nm, is explored to dope PPy on F-doped tin oxide glass as an efficient counter electrode for high-performance dye-sensitized solar cells (DSSCs). The GQDs-doped PPy film has a porous structure in comparison to the densely structured plain PPy, and displays higher catalytic current density and lower charge transfer resistance than the latter toward I3(-)/I(-) redox reaction. The highest power conversion efficiency (5.27%) for DSSCs is achieved with PPy doped with10% GQDs, which is comparable to that of Pt counter electrode-based DSSCs. This work provides an inexpensive alternative to replace platinum for DSSCs.

  13. High critical currents in heavily doped (Gd,Y)Ba2Cu3Ox superconductor tapes

    International Nuclear Information System (INIS)

    Selvamanickam, V.; Gharahcheshmeh, M. Heydari; Xu, A.; Galstyan, E.; Delgado, L.; Cantoni, C.

    2015-01-01

    REBa 2 Cu 3 O x ((REBCO), RE = rare earth) superconductor tapes with moderate levels of dopants have been optimized for high critical current density in low magnetic fields at 77 K, but they do not exhibit exemplary performance in conditions of interest for practical applications, i.e., temperatures less than 50 K and fields of 2–30 T. Heavy doping of REBCO tapes has been avoided by researchers thus far due to deterioration in properties. Here, we report achievement of critical current densities (J c ) above 20 MA/cm 2 at 30 K, 3 T in heavily doped (25 mol. % Zr-added) (Gd,Y)Ba 2 Cu 3 O x superconductor tapes, which is more than three times higher than the J c typically obtained in moderately doped tapes. Pinning force levels above 1000 GN/m 3 have also been attained at 20 K. A composition map of lift factor in J c (ratio of J c at 30 K, 3 T to the J c at 77 K, 0 T) has been developed which reveals the optimum film composition to obtain lift factors above six, which is thrice the typical value. A highly c-axis aligned BaZrO 3 (BZO) nanocolumn defect density of nearly 7 × 10 11  cm −2 as well as 2–3 nm sized particles rich in Cu and Zr have been found in the high J c films

  14. Cobalt-Doped Nickel Phosphite for High Performance of Electrochemical Energy Storage.

    Science.gov (United States)

    Li, Bing; Shi, Yuxin; Huang, Kesheng; Zhao, Mingming; Qiu, Jiaqing; Xue, Huaiguo; Pang, Huan

    2018-02-19

    Compared to single metallic Ni or Co phosphides, bimetallic Ni-Co phosphides own ameliorative properties, such as high electrical conductivity, remarkable rate capability, upper specific capacity, and excellent cycle performance. Here, a simple one-step solvothermal process is proposed for the synthesis of bouquet-like cobalt-doped nickel phosphite (Ni 11 (HPO 3 ) 8 (OH) 6 ), and the effect of the structure on the pseudocapacitive performance is investigated via a series of electrochemical measurements. It is found that when the cobalt content is low, the glycol/deionized water ratio is 1, and the reaction is under 200 °C for 20 h, the morphology of the sample is uniform and has the highest specific surface area. The cobalt-doped Ni 11 (HPO 3 ) 8 (OH) 6 electrode presents a maximum specific capacitance of 714.8 F g -1 . More significantly, aqueous and solid-state flexible electrochemical energy storage devices are successfully assembled. The aqueous device shows a high energy density of 15.48 mWh cm -2 at the power density of 0.6 KW cm -2 . The solid-state device shows a high energy density of 14.72 mWh cm -2 at the power density of 0.6 KW cm -2 . These excellent performances confirm that the cobalt-doped Ni 11 (HPO 3 ) 8 (OH) 6 are promising materials for applications in electrochemical energy storage devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. A Facile Synthesis of Nitrogen-Doped Highly Porous Carbon Nanoplatelets: Efficient Catalysts for Oxygen Electroreduction

    Science.gov (United States)

    Zhang, Yaqing; Zhang, Xianlei; Ma, Xiuxiu; Guo, Wenhui; Wang, Chunchi; Asefa, Tewodros; He, Xingquan

    2017-02-01

    The oxygen reduction reaction (ORR) is of great importance for various renewable energy conversion technologies such as fuel cells and metal-air batteries. Heteroatom-doped carbon nanomaterials have proven to be robust metal-free electrocatalysts for ORR in the above-mentioned energy devices. Herein, we demonstrate the synthesis of novel highly porous N-doped carbon nanoplatelets (N-HPCNPs) derived from oatmeal (or a biological material) and we show the materials’ high-efficiency as electrocatalyst for ORR. The obtained N-HPCNPs hybrid materials exhibit superior electrocatalytic activities towards ORR, besides excellent stability and good methanol tolerance in both basic and acidic electrolytes. The unique nanoarchitectures with rich micropores and mesopores, as well as the high surface area-to-volume ratios, present in the materials significantly increase the density of accessible catalytically active sites in them and facilitate the transport of electrons and electrolyte within the materials. Consequently, the N-HPCNPs catalysts hold a great potential to serve as low-cost and highly efficient cathode materials in direct methanol fuel cells (DMFCs).

  16. High resolution patterning of quadratic non-linear optical properties in doped photopolymer thin films

    Science.gov (United States)

    Bombenger, J.-P.; Mager, L.; Gindre, D.; Vola, J.-P.; Dorkenoo, K. D.; Fort, A.; Carré, C.

    2007-12-01

    We demonstrate the patterning of the quadratic non-linear optical (QNLO) properties in a photopolymerizable resin doped with push-pull chromophores. Advantage is taken of the crosslinking process to perform the patterning directly. QNLO gratings with a period of 8.5 μm have been achieved over areas of a few cm 2. This spacing is comparable to the typical visible and near infrared coherence lengths in this material and is therefore suitable for the elaboration of quasi-phase matched waveguides. An accurate characterization of the QNLO gratings has been performed using a high spatial resolution second harmonic generation microscope with a femtosecond laser source.

  17. High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb

    International Nuclear Information System (INIS)

    Tu, Nguyen Thanh; Hai, Pham Nam; Anh, Le Duc; Tanaka, Masaaki

    2016-01-01

    We show high-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga 1−x ,Fe x )Sb (x = 23% and 25%) thin films grown by low-temperature molecular beam epitaxy. Magnetic circular dichroism spectroscopy and anomalous Hall effect measurements indicate intrinsic ferromagnetism of these samples. The Curie temperature reaches 300 K and 340 K for x = 23% and 25%, respectively, which are the highest values reported so far in intrinsic III-V ferromagnetic semiconductors.

  18. High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Nguyen Thanh [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physics, Ho Chi Minh City University of Pedagogy, 280, An Duong Vuong Street, District 5, Ho Chi Minh City 748242 (Viet Nam); Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-0033 (Japan); Center for Spintronics Research Network (CSRN), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Anh, Le Duc [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Center for Spintronics Research Network (CSRN), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2016-05-09

    We show high-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga{sub 1−x},Fe{sub x})Sb (x = 23% and 25%) thin films grown by low-temperature molecular beam epitaxy. Magnetic circular dichroism spectroscopy and anomalous Hall effect measurements indicate intrinsic ferromagnetism of these samples. The Curie temperature reaches 300 K and 340 K for x = 23% and 25%, respectively, which are the highest values reported so far in intrinsic III-V ferromagnetic semiconductors.

  19. Durability Issues of High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    DEFF Research Database (Denmark)

    To achieve high temperature operation of proton exchange membrane fuel cells (PEMFC), preferably under ambient pressure, phosphoric acid doped polybenzimidazole (PBI) membrane represents an effective approach, which in recent years has motivated extensive research activities with great progress....... As a critical concern, issues of long term durability of PBI based fuel cells are addressed in this talk, including oxidative degradation of the polymer, mechanical failures of the membrane, acid leaching out, corrosion of carbon support and sintering of catalysts particles. Excellent polymer durability has...

  20. Thermal conductivity of high-porosity heavily doped biomorphic silicon carbide prepared from sapele wood biocarbon

    Science.gov (United States)

    Parfen'eva, L. S.; Orlova, T. S.; Smirnov, B. I.; Smirnov, I. A.; Misiorek, H.; Mucha, J.; Jezowski, A.; Cabezas-Rodriguez, R.; Ramirez-Rico, J.

    2012-08-01

    The electrical resistivity and thermal conductivity of high-porosity (˜52 vol %, channel-type pores) bio-SiC samples prepared from sapele wood biocarbon templates have been measured in the temperature range 5-300 K. An analysis has been made of the obtained results in comparison with the data for bio-SiC samples based on beech and eucalyptus, as well as for polycrystalline β-SiC. The conclusion has been drawn that the electrical resistivity and thermal conductivity of bio-SiC samples based on natural wood are typical of heavily doped polycrystalline β-SiC.

  1. Ultrabroadband terahertz characterization of highly doped ZnO and ITO

    DEFF Research Database (Denmark)

    Wang, Tianwu; Zalkovskij, Maksim; Iwaszczuk, Krzysztof

    2015-01-01

    The broadband complex conductivities of transparent conducting oxides (TCO), namely, aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO) and tin-doped indium oxide (ITO), were investigated by using THz-TDS from 0.5 to 18 THz. The complex conductivities were accurately calculated using...... resonance tail even in the low frequency part of the spectrum....

  2. Three-dimensional N-doped graphene/polyaniline composite foam for high performance supercapacitors

    Science.gov (United States)

    Zhu, Jun; Kong, Lirong; Shen, Xiaoping; Chen, Quanrun; Ji, Zhenyuan; Wang, Jiheng; Xu, Keqiang; Zhu, Guoxing

    2018-01-01

    Three-dimensional (3D) graphene aerogel and its composite with interconnected pores have aroused continuous interests in energy storage field owning to its large surface area and hierarchical pore structure. Herein, we reported the preparation of 3D nitrogen-doped graphene/polyaniline (N-GE/PANI) composite foam for supercapacitive material with greatly improved electrochemical performance. The 3D porous structure can allow the penetration and diffusion of electrolyte, the incorporation of nitrogen doping can enhance the wettability of the active material and the number of active sites with electrolyte, and both the N-GE and PANI can ensure the high electrical conductivity of total electrode. Moreover, the synergistic effect between N-GE and PANI materials also play an important role on the electrochemical performance of electrode. Therefore, the as-prepared composite foam could deliver a high specific capacitance of 528 F g-1 at 0.1 A g-1 and a high cyclic stability with 95.9% capacitance retention after 5000 charge-discharge cycles. This study provides a new idea on improving the energy storage capacity of supercapacitors by using 3D graphene-based psedocapacitive electrode materials.

  3. Comparative investigation of surface transfer doping of hydrogen terminated diamond by high electron affinity insulators

    Energy Technology Data Exchange (ETDEWEB)

    Verona, C.; Marinelli, Marco; Verona-Rinati, G. [Dip. di Ingegneria Industriale, Università di Roma “Tor Vergata,” Via del Politecnico 1, I-00133 Roma (Italy); Ciccognani, W.; Colangeli, S.; Limiti, E. [Dip. di Ingegneria Elettronica, Università di Roma “Tor Vergata,” Via del Politecnico 1, I-00133 Roma (Italy)

    2016-07-14

    We report on a comparative study of transfer doping of hydrogenated single crystal diamond surface by insulators featured by high electron affinity, such as Nb{sub 2}O{sub 5}, WO{sub 3}, V{sub 2}O{sub 5}, and MoO{sub 3}. The low electron affinity Al{sub 2}O{sub 3} was also investigated for comparison. Hole transport properties were evaluated in the passivated hydrogenated diamond films by Hall effect measurements, and were compared to un-passivated diamond films (air-induced doping). A drastic improvement was observed in passivated samples in terms of conductivity, stability with time, and resistance to high temperatures. The efficiency of the investigated insulators, as electron accepting materials in hydrogenated diamond surface, is consistent with their electronic structure. These surface acceptor materials generate a higher hole sheet concentration, up to 6.5 × 10{sup 13} cm{sup −2}, and a lower sheet resistance, down to 2.6 kΩ/sq, in comparison to the atmosphere-induced values of about 1 × 10{sup 13} cm{sup −2} and 10 kΩ/sq, respectively. On the other hand, hole mobilities were reduced by using high electron affinity insulator dopants. Hole mobility as a function of hole concentration in a hydrogenated diamond layer was also investigated, showing a well-defined monotonically decreasing trend.

  4. Unexpectedly high piezoelectricity of Sm-doped lead zirconate titanate in the Curie point region.

    Science.gov (United States)

    Seshadri, Shruti B; Nolan, Michelle M; Tutuncu, Goknur; Forrester, Jennifer S; Sapper, Eva; Esteves, Giovanni; Granzow, Torsten; Thomas, Pam A; Nino, Juan C; Rojac, Tadej; Jones, Jacob L

    2018-03-07

    Large piezoelectric coefficients in polycrystalline lead zirconate titanate (PZT) are traditionally achieved through compositional design using a combination of chemical substitution with a donor dopant and adjustment of the zirconium to titanium compositional ratio to meet the morphotropic phase boundary (MPB). In this work, a different route to large piezoelectricity is demonstrated. Results reveal unexpectedly high piezoelectric coefficients at elevated temperatures and compositions far from the MPB. At temperatures near the Curie point, doping with 2 at% Sm results in exceptionally large piezoelectric coefficients of up to 915 pm/V. This value is approximately twice those of other donor dopants (e.g., 477 pm/V for Nb and 435 pm/V for La). Structural changes during the phase transitions of Sm-doped PZT show a pseudo-cubic phase forming ≈50 °C below the Curie temperature. Possible origins of these effects are discussed and the high piezoelectricity is posited to be due to extrinsic effects. The enhancement of the mechanism at elevated temperatures is attributed to the coexistence of tetragonal and pseudo-cubic phases, which enables strain accommodation during electromechanical deformation and interphase boundary motion. This work provides insight into possible routes for designing high performance piezoelectrics which are alternatives to traditional methods relying on MPB compositions.

  5. Methanesulfonic acid-assisted synthesis of N/S co-doped hierarchically porous carbon for high performance supercapacitors

    Science.gov (United States)

    Huo, Silu; Liu, Mingquan; Wu, Linlin; Liu, Mingjie; Xu, Min; Ni, Wei; Yan, Yi-Ming

    2018-05-01

    Nitrogen and sulfur co-doped carbons are considered as electrode materials for high performance supercapacitors, while their further development is still limited by complicated synthesis procedure, unsatisfied structure and low energy density. Developing a simple synthetic strategy to obtain rationally structured carbon materials and high supercapacitor performance is remaining a grand challenge. Herein, we describe the synthesis of nitrogen and sulfur co-doped hierarchical porous carbons as high performance supercapacitors electrode by a methanesulfonic acid-assisted one-step carbonization and activation of the freeze-dried precursors mixture. The as-prepared carbon material not only exhibits ideally hierarchical pores, but also realizes uniform nitrogen and sulfur co-doping. In 6.0 M KOH electrolyte, the material can achieve a high specific capacitance of 272 F g-1 at 1.0 A g-1 and a promising rate performance retaining 172 F g-1 even at 100 A g-1. Moreover, a fabricated symmetric supercapacitor based on as-prepared nitrogen and sulfur co-doped hierarchical porous carbon delivers high energy densities of 12.4 W h kg-1 and 8.0 W h kg-1 in 6.0 M KOH liquid and KOH/PVA solid-state electrolytes, respectively. This work presents a simple and effective methanesulfonic acid-assisted approach for mass production of heteroatomic doping hierarchical porous carbons for future energy storage applications.

  6. Effects of Yttrium and Iron co-doping on the high temperature thermoelectric properties of Ca3Co4O9+δ

    International Nuclear Information System (INIS)

    Wu, NingYu; Van Nong, Ngo; Pryds, Nini; Linderoth, Søren

    2015-01-01

    Highlights: • The Fe and Fe/Y doping at the Co- and Ca-sites of Ca 3 Co 4 O 9+δ were investigated. • The rising ρ by Y doping can be mitigated by the coupled Fe doping. • The increased Seebeck coefficient by Y doping can be maintained in co-doped system. • The co-doped system leads to an improvement of the thermoelectric performance. • The co-doped system may preserve the merits from each component doping. - Abstract: A series of Y and Fe co-doped Ca 3−x Y x Co 4−y Fe y O 9+δ (0 ⩽ x ⩽ 0.3, 0 ⩽ y ⩽ 0.1) samples synthesized by auto-combustion reaction and followed by a spark plasma sintering (SPS) processing with the effects of Fe and Y doping on the high temperature (RT to 800 °C) thermoelectric properties were systematically investigated. For the Fe-doped system (x = 0, y ⩽ 0.1), the electrical resistivity (ρ) decreased over the whole measured temperature range, while the Seebeck coefficient (S) remained almost the same. For the co-doped system, at any fixed Fe doping content, both ρ and S tended to increase with increasing Y dopants, however, the effect is more substantial on ρ than on S, particularly in the low temperature regime. In contrast to ρ and S, the in-plane thermal conductivity (κ) is only slightly influenced by Y and Fe substitutions. Among all the investigated samples, the co-doped sample with x = 0.1 and y = 0.03 showed a decrease of ρ, enhanced power factor over the measured temperature range, and improved ZT at 800 °C as compared to un-doped Ca 3 Co 4 O 9+δ

  7. Upconverting crystal/dextran-g-DOPE with high fluorescence stability for simultaneous photodynamic therapy and cell imaging

    International Nuclear Information System (INIS)

    Wang, HanJie; Wang, Sheng; Liu, Zhongyun; Dong, Chunhong; Chang, Jin; Yang, Jiumin; Gong, Xiaoqun

    2014-01-01

    To date, the application of photodynamic therapy in deep tissue has been severely restricted by the limited penetration depth of excitation light, such as UV light and visible light. In this work, a protocol of upconverting crystal/dextran-g-DOPE nanocomplex (UCN/dextran-g-DOPE) was developed. The nanocomplex was assembled from the hydrophobic upconverting nanoparticle (UCN) core and hydrophilic lipid shell. The photosensitizer zinc phthalocyanine (ZnPc) loaded UCN/dextran-g-DOPE offers possibilities to overcome the problem mentioned above. The UCN core works as a transducer to convert deeply penetrating near-infrared light to visible light to activate ZnPc for photodynamic therapy. The dextran-g-DOPE lipid shell is used for loading ZnPc and protecting the whole system from nonspecific absorbance or corrosion during the transportation. The experiment results show that the nanocomplex is an individual sphere with an average size of 30 nm. The ZnPc was activated to produce singlet oxygen successfully by the upconverting fluorescence emitted from UCN. The nanocomplex has high fluorescence stability in alkaline or neutral buffer solutions. Importantly, the ZnPc loaded UCN/dextran-g-DOPE nanocomplex showed a significant inhibitory effect on tumor cells after NIR exposure. Our data suggest that a ZnPc loaded UCN/dextran-g-DOPE nanocomplex may be a useful nanoplatform for future PDT treatment in deep-cancer therapy based on the upconverting mechanism. (paper)

  8. Vanadium doped WS2 nanosheets grown on carbon cloth as highly efficient electrocatalyst for hydrogen evolution reaction.

    Science.gov (United States)

    Jiang, Anning; Zhang, Baohua; Li, Zhonghao; Jin, Guoxia; Hao, Jingcheng

    2018-04-01

    Two-dimensional transition metal dichalcogenides have been widely studied as electrocatalysts for hydrogen evolution reaction. However, the limited active sites and poor conductivity hinder their application. To solve these disadvantages, heteroatom doping has attracted wide attention, which can not only increases the active sites but also affects the intrinsic catalytic properties of the electrocatalysts. Herein, we grew vanadium doped WS2 nanosheets on carbon cloth (V-WS2/CC) as electrocatalyst for HER under acidic and alkaline conditions respectively. With proper vanadium doping concentration, the electrochemical surface areas of V0.065-WS2/CC are 9.6 and 2.6 times as large as that of pure WS2 electrocatalyst under acidic and alkaline conditions, respectively. In addition, the charge-transfer resistance also decreases with moderate vanadium doping. Based on this, the synthesized vanadium doped WS2 nanosheets exhibited good stability with high HER catalytic activity that can reach the current density of 10 mA cm-2 at the overpotential of 148 and 134 mV in 0.5 H2SO4 and 1 M KOH solution, respectively. The corresponding Tafel slopes are 71 and 85 mV dec-1. Therefore, our synthesized vanadium doped WS2 nanosheets can be a promising electrocatalyst for the production of hydrogen over a wide pH range. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Improved structural strength and lifetime of monoblock divertor targets by using doped tungsten alloys under cyclic high heat flux loading

    Science.gov (United States)

    Nogami, S.; Guan, W. H.; Hattori, T.; James, K.; Hasegawa, A.

    2017-12-01

    The divertor is one of the most important components of a fusion reactor, which performs the function of the removal of waste material from fusion plasma. Because the divertor is subjected to cyclic high heat flux loading up to about 20 MW m-2 induced by the plasma, the plasma facing material of the divertor should exhibit good thermo-mechanical properties. In this work, the possibility of improving the structural strength and the lifetime of fusion reactor divertors by using K-doped W and K-doped W-3%Re as plasma facing material instead of ordinary pure W was evaluated by thermo-mechanical finite element analysis (FEA). These materials have been developed for divertor applications in Japan and show higher recrystallization temperature and strength than pure W. The results of the present study indicated that K-doped W and K-doped W-3%Re render lower applied strain to the divertor and longer fatigue life of the plasma facing material. The evaluation results regarding the macro-crack formation life based on the FEA analyses indicated the possibility of an extension of the fatigue life by using K-doped W and K-doped W-3%Re.

  10. TEM investigation of aluminium containing precipitates in high aluminium doped silicon carbide

    International Nuclear Information System (INIS)

    Wong-Leung, J.; FitzGerald, J.D.

    2002-01-01

    Full text: Silicon carbide is a promising semiconductor material for applications in high temperature and high power devices. The successful growth of good quality epilayers in this material has enhanced its potential for device applications. As a novel semiconductor material, there is a need for studying its basic physical properties and the role of dopants in this material. In this study, silicon carbide epilayers were grown on 4H-SiC wafers of (0001) orientation with a miscut angle of 8 deg at a temperature of 1550 deg C. The epilayers contained regions of high aluminium doping well above the solubility of aluminium in silicon carbide. High temperature annealing of this material resulted in the precipitation of aluminium in the wafers. The samples were analysed by secondary ion mass spectrometry and transmission electron microscopy. Selected area diffraction studies show the presence of aluminium carbide and aluminium silicon carbide phases. Copyright (2002) Australian Society for Electron Microscopy Inc

  11. Kr and Xe irradiations in lanthanum (La) doped ceria: Study at the high dose regime

    Science.gov (United States)

    Yun, Di; Oaks, Aaron J.; Chen, Wei-ying; Kirk, Marquis A.; Rest, Jeffrey; Insopov, Zinetula Z.; Yacout, Abdellatif M.; Stubbins, James F.

    2011-11-01

    In order to understand cavity and bubble formation and growth in oxide nuclear fuel materials, ion beam irradiation experiments were conducted with two common fission gas species: Kr and Xe. Ceria (CeO 2) was selected as a surrogate material for uranium dioxide (UO 2) due to its many similar properties to UO 2. Ion beam energies were chosen such that both cavities and gas bubbles structures were induced by ion irradiations. The ion irradiation experiments were carried out at 600 °C, at which temperature, cavity/gas bubble structures are believed to be immobile in this material. Lanthanum (La) was chosen as a dopant in CeO 2 to investigate the effect of impurities. The presence of La in the CeO 2 lattice also introduces a predictable initial concentration of oxygen vacancies, similar to the introduction of oxygen vacancies by the existence of Pu 3+ in MOX fuel [1]. The influence of two La concentrations, 5% and 25%, were examined. The study focused on the high dose regime where cavity/gas bubble structures were clearly identifiable with their sizes and number densities readily measurable. Cavity/gas bubble coarsening by coalescence was identified with TEM (Transmission Electron Microscopy) characterizations of as-irradiated La doped CeO 2 specimens. The results revealed that lanthanum trapping has significant influence on the cavity/bubble growth in the material lattice by comparing the cavity/gas bubble size distributions between 5% La doped ceria and 25% La doped ceria. Lattice and kinetic Monte Carlo calculations described in a previous work have provided insights to the interpretations of the experimental results [2]. Solid state Xe precipitates were observed in low energy Xe implantation in 5% La doped ceria to a very high fluence of 1 × 10 17 ions/cm 2 at 600 °C. The solid state Xe precipitate structures are represented by faceted morphology. Very similar observations of solid state/near solid state Xe bubbles were made by Nogita et al. in the outer region

  12. Highly flexible and robust N-doped SiC nanoneedle field emitters

    KAUST Repository

    Chen, Shanliang

    2015-01-23

    Flexible field emission (FE) emitters, whose unique advantages are lightweight and conformable, promise to enable a wide range of technologies, such as roll-up flexible FE displays, e-papers and flexible light-emitting diodes. In this work, we demonstrate for the first time highly flexible SiC field emitters with low turn-on fields and excellent emission stabilities. n-Type SiC nanoneedles with ultra-sharp tips and tailored N-doping levels were synthesized via a catalyst-assisted pyrolysis process on carbon fabrics by controlling the gas mixture and cooling rate. The turn-on field, threshold field and current emission fluctuation of SiC nanoneedle emitters with an N-doping level of 7.58 at.% are 1.11 V μm-1, 1.55 V μm-1 and 8.1%, respectively, suggesting the best overall performance for such flexible field emitters. Furthermore, characterization of the FE properties under repeated bending cycles and different bending states reveal that the SiC field emitters are mechanically and electrically robust with unprecedentedly high flexibility and stabilities. These findings underscore the importance of concurrent morphology and composition controls in nanomaterial synthesis and establish SiC nanoneedles as the most promising candidate for flexible FE applications. © 2015 Nature Publishing Group All rights reserved.

  13. Yb-doped phosphate double-cladding optical fiber for high-power laser applications

    Science.gov (United States)

    Mura, E.; Scarpignato, G. C.; Lousteau, J.; Boetti, N. G.; Abrate, S.; Milanese, D.

    2013-02-01

    A Yb-doped phosphate glass double cladding optical fiber was prepared using a custom designed glass composition (P2O5 - Al2O3 - Li2O - B2O3 - BaO - PbO - La2O3) for high-power amplifier and laser applications. The preform drawing method was followed, with the preform being fabricated using the rotational casting technique. This technique, previously developed for tellurite, fluoride or chalcogenide glass preforms is reported for the first time using rare earth doped phosphate glasses. The main challenge was to design an adequate numerical aperture between first and second cladding while maintaining similar thermo-mechanical properties in view of the fiber drawing process. The preform used for the fiber drawing was produced by rod-in-tube technique at a rotation speed of 3000 rpm. The rotational casting technique allowed the manufacturing of an optical fiber featuring high quality interfaces between core and internal cladding and between the internal and external cladding, respectively. Loss attenuation was measured using the cut-back method and lasing was demonstrated at 1022 nm by core pumping with a fiber pigtailed laser diode at the wavelength of 976 nm.

  14. Spectroscopic XPEEM of highly conductive SI-doped GaN wires.

    Science.gov (United States)

    Renault, O; Morin, J; Tchoulfian, P; Chevalier, N; Feyer, V; Pernot, J; Schneider, C M

    2015-12-01

    Using soft X-ray photoelectron emission microscopy (XPEEM), complemented by scanning Auger microscopy (SAM) and scanning capacitance microscopy, we have quantitatively studied the incorporation of silicon and band bending at the surface (m-facet) of an individual, highly conductive Si-doped GaN micro-wires (Tchoulfian et al., Applied Physics Letters 102 (12), 2013). Electrically active n-dopants Si atoms in Ga interstitial sites are detected as nitride bonding states in the high-resolution Si2p core level spectra, and represent only a small fraction (<10%) of the overall Si surface concentration measured by SAM. The derived carrier concentration of 2×10(21) at cm(-3) is in reasonable agreement with electrical measurements. A consistent surface band bending of ~1 eV is directly evidenced by surface photo-voltage measurements. Such an approach combining different surface-sensitive microscopies is of interest for studying other heavily doped semiconducting wires. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Modified Stoeber synthesis of highly luminescent dye-doped silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Canton, G.; Ricco, R. [Coordinamento Interuniversitario Veneto per le Nanotecnologie (CIVEN) (Italy); Marinello, F. [Universita di Padova, Dipartimento di Innovazione Meccanica e Gestionale (DIMEG) (Italy); Carmignato, S. [Universita di Padova, Dipartimento di Tecnica e Gestione dei Sistemi Industriali (DTG) (Italy); Enrichi, F., E-mail: enrichi@civen.org [Coordinamento Interuniversitario Veneto per le Nanotecnologie (CIVEN) (Italy)

    2011-09-15

    Dye-doped silica nanoparticles (NPs) have been demonstrated to be sensitive labeling markers for biosensing and bioimaging. Their flexible conjugation, excellent photostability and ultrasensitivity make them a powerful tool in biological analysis. Although there have been many reports on the basic research and application of these NPs, they are far from reaching their full potential. Silica NPs can be obtained through two principal approaches: the Stoeber synthesis and the microemulsion method. The Stoeber synthesis has the advantage of being easily scaled up for commercial applications and the possibility to effortlessly transfer the NPs into aqueous solutions (typical of bioanalysis). However, further investigation on the impact of the synthesis parameters on the particles size and on the doping process are needed in order to obtain highly luminescent particles. In this study a modified Stoeber synthesis is proposed and a systematic study of the different reagents is reported, which provides a better picture on the influence of ethanol, ammonia, water, silica precursors, and dye concentration on the final morpho-optical properties. As a result, samples of luminescent silica NPs from 10 to 300 nm have been synthesized and optimized to be highly promising labels for biological applications.

  16. Modified Stöber synthesis of highly luminescent dye-doped silica nanoparticles

    International Nuclear Information System (INIS)

    Canton, G.; Riccò, R.; Marinello, F.; Carmignato, S.; Enrichi, F.

    2011-01-01

    Dye-doped silica nanoparticles (NPs) have been demonstrated to be sensitive labeling markers for biosensing and bioimaging. Their flexible conjugation, excellent photostability and ultrasensitivity make them a powerful tool in biological analysis. Although there have been many reports on the basic research and application of these NPs, they are far from reaching their full potential. Silica NPs can be obtained through two principal approaches: the Stöber synthesis and the microemulsion method. The Stöber synthesis has the advantage of being easily scaled up for commercial applications and the possibility to effortlessly transfer the NPs into aqueous solutions (typical of bioanalysis). However, further investigation on the impact of the synthesis parameters on the particles size and on the doping process are needed in order to obtain highly luminescent particles. In this study a modified Stöber synthesis is proposed and a systematic study of the different reagents is reported, which provides a better picture on the influence of ethanol, ammonia, water, silica precursors, and dye concentration on the final morpho-optical properties. As a result, samples of luminescent silica NPs from 10 to 300 nm have been synthesized and optimized to be highly promising labels for biological applications.

  17. Realization of ferromagnetic graphene oxide with high magnetization by doping graphene oxide with nitrogen.

    Science.gov (United States)

    Liu, Yuan; Tang, Nujiang; Wan, Xiangang; Feng, Qian; Li, Ming; Xu, Qinghua; Liu, Fuchi; Du, Youwei

    2013-01-01

    The long spin diffusion length makes graphene very attractive for novel spintronic devices, and thus has triggered a quest for integrating the charge and spin degrees of freedom. However, ideal graphene is intrinsic non-magnetic, due to a delocalized π bonding network. Therefore, synthesis of ferromagnetic graphene or its derivatives with high magnetization is urgent due to both fundamental and technological importance. Here we report that N-doping can be an effective route to obtain a very high magnetization of ca. 1.66 emu/g, and can make graphene oxide (GO) to be ferromagnetism with a Curie-temperature of 100.2 K. Clearly, our findings can offer the easy realization of ferromagnetic GO with high magnetization, therefore, push the way for potential applications in spintronic devices.

  18. Electronic properties of chlorine doped cadmium telluride used as high energy photoconductive detector

    International Nuclear Information System (INIS)

    Verger, L.; Cuzin, M.; Gaude, G.; Glasser, F.; Mathy, F.; Rustique, J.; Schaub, B.

    1991-01-01

    A new high energy X-ray chlorine doped Cadmium Telluride (CdTe:Cl) photoconductor is described. We discuss different deposition techniques (Sputtering, Evaporation, Electroless) to realize ohmic contacts which have low leakage current and which allow high applied electric field. The temperature dependence of the dark current give an activation energy of 0.6 eV for standard CdTe:Cl. The transient response of photoconductors under high X-ray energy beams has been characterized using three different pulse duration 150 ps, 30 ns and 4 μs. Sensitivity and speed of response are studied as a function of neutron pre-irradiated doses (0, 10 14 , 10 15 , 10 16 n/cm 2 ): neutron irradiations reduce the carrier lifetime at the expense of a lower sensitivity

  19. Microstructure and high-temperature tribological properties of Si-doped hydrogenated diamond-like carbon films

    Science.gov (United States)

    Zhang, Teng Fei; Wan, Zhi Xin; Ding, Ji Cheng; Zhang, Shihong; Wang, Qi Min; Kim, Kwang Ho

    2018-03-01

    Si-doped DLC films have attracted great attention for use in tribological applications. However, their high-temperature tribological properties remain less investigated, especially in harsh oxidative working conditions. In this study, Si-doped hydrogenated DLC films with various Si content were synthesized and the effects of the addition of Si on the microstructural, mechanical and high-temperature tribological properties of the films were investigated. The results indicate that Si doping leads to an obvious increase in the sp3/sp2 ratio of DLC films, likely due to the silicon atoms preferentially substitute the sp2-hybridized carbon atoms and augment the number of sp3 sites. With Si doping, the mechanical properties, including hardness and adhesion strength, were improved, while the residual stress of the DLC films was reduced. The addition of Si leads to higher thermal and mechanical stability of DLC films because the Si atoms inhibit the graphitization of the films at an elevated temperature. Better high-temperature tribological properties of the Si-DLC films under oxidative conditions were observed, which can be attributed to the enhanced thermal stability and formation of a Si-containing lubricant layer on the surfaces of the wear tracks. The nano-wear resistance of the DLC films was also improved by Si doping.

  20. Photoluminescence of highly compensated GaAs doped with high concentration of Ge

    Science.gov (United States)

    Watanabe, Masaru; Watanabe, Akira; Suezawa, Masashi

    1999-12-01

    We have studied the photoluminescence (PL) properties of Ge-doped GaAs crystals to confirm the validity of a theory developed by Shklovskii and Efros to explain the donor-acceptor pair (DAP) recombination in potential fluctuation. GaAs crystals doped with Ge of various concentrations were grown by a liquid-encapsulated Czochralski method. They were homogenized by annealing at 1200°C for 20 h under the optimum As vapor pressure. Both quasi-continuous and time-resolved PL spectra were measured at 4.2 K. The quasi-continuous PL spectra showed that the peak position shifted to lower energy as the Ge concentration increased, which was consistent with the Shklovskii and Efros's theory. Under very strong excitation in time-resolved measurements, the exciton peak appeared within short periods after excitation and then the peak shifted to that of DAP recombination. This clearly showed that the potential fluctuation disappeared under strong excitation and then recovered as the recombination proceeded.

  1. High field magnetic behavior in Boron doped Fe{sub 2}VAl Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, Ch., E-mail: venkyphysicsiitm@gmail.com [Department of Physics, Indian Institute of Technology, Kharagpur (India); DCMP & MS, Tata Institute of Fundamental Research, Mumbai (India); Vasundhara, M., E-mail: vasu.mutta@gmail.com [Materials Science and Technology Division, National Institute for Interdisciplinary Science and Technology, CSIR, Trivandrum 695019 (India); Srinivas, V. [Department of Physics, Indian Institute of Technology, Chennai (India); Rao, V.V. [Cryogenic Engineering Centre, Indian Institute of Technology, Kharagpur (India)

    2016-11-15

    We have investigated the magnetic behavior of Fe{sub 2}VAl{sub 1−x}B{sub x} (x=0, 0.03, 0.06 and 0.1) alloys under high temperature and high magnetic field conditions separately. Although, the low temperature DC magnetization data for the alloys above x>0 show clear magnetic transitions, the zero field cooled (ZFC) and field cooled (FC) curves indicate the presence of spin cluster like features. Further, critical exponent (γ) deduced from the initial susceptibility above the T{sub c}, does not agree with standard models derived for 3 dimensional long range magnetic systems. The deviation in γ values are consistent with the short range magnetic nature of these alloys. We further extend the analysis of magnetic behavior by carrying the magnetization measurements at high temperatures and high magnetic fields distinctly. We mainly emphasize the following observations; (i) The magnetic hysteresis loops show sharp upturns at lower fields even at 900 K for all the alloys. (ii) High temperature inverse susceptibility do not overlap until T=900 K, indicating the persistent short range magnetic correlations even at high temperatures. (iii) The Arrott's plot of magnetization data shows spontaneous moment (M{sub S}) for the x=0 alloy at higher magnetic fields which is absent at lower fields (<50 kOe), while the Boron doped samples show feeble M{sub S} at lower fields. The origin of this short range correlation is due to presence of dilute magnetic heterogeneous phases which are not detected from the X-ray diffraction method. - Highlights: • Short range magnetic character has been confirmed by the critical exponents analysis. • Magnetoresistace is about −14% with non-saturating tendency even at 150 kOe for Fe{sub 2}VAl alloy. • Boron doped Fe{sub 2}VAl alloys show a weak magnetism even at T=900 K.

  2. The Six-Inch Lunar Atlas A Pocket Field Guide

    CERN Document Server

    Spain, Don

    2009-01-01

    The Six-Inch Lunar Atlas has been designed specifically for use in the field by lunar observers so it’s perfect for fitting into an observer’s pocket! The author’s own lunar photographs were taken with a 6-inch (150mm) telescope and CCD camera, and closely match the visual appearance of the Moon when viewed through 3-inch to 8-inch telescopes. Each picture is shown oriented "as the Moon really is" when viewed from the northern hemisphere, and is supplemented by exquisite computer sketches that list the main features. Two separate computer sketches are provided to go with each photograph, one oriented to appear as seen through an SCT telescope (e.g. the Meade and Celestron ranges), the other oriented for Newtonian and refracting telescopes. Observers using the various types telescopes will find it extremely helpful to identify lunar features as the human brain is very poor at making "mirror-image" visual translations.

  3. Aerosol Research Branch (ARB) 48 inch Lidar Data

    Data.gov (United States)

    National Aeronautics and Space Administration — The ARB_48_IN_LIDAR data set contains data collected from a 48-inch lidar system located at NASA Langley Research Center. Each granule consists of one year of data....

  4. Lithium and sodium storage in highly ordered mesoporous nitrogen-doped carbons derived from honey

    Science.gov (United States)

    Zhang, Yongzhi; Chen, Li; Meng, Yan; Xie, Jun; Guo, Yong; Xiao, Dan

    2016-12-01

    Honey, a widely existent biomass, consists mainly of carbohydrate and other nitrogen-containing substances such as proteins, enzymes and organic acids. It can be mixed homogeneously with mesoporous silica template for its excellent water-solubility and moderate viscosity. In this work, honey was employed as a nitrogen-containing carbon precursor to prepare nitrogen-doped ordered mesoporous carbons (OMCs). The obtained honey derived mesoporous nitrogen-doped carbons (HMNCs) with dilated interlayer spacings of 0.387-0.395 nm, narrow pore size distributions centering at around 4 nm and satisfactory N contents of 1.38-4.32 wt% offer superb dual functionality for lithium ion battery (LIB) and sodium ion battery (NIB) anodes. Tested against Li, the optimized HMNC-700 delivers a superior reversible capacity of 1359 mA h g-1 after 10 cycles at 100 mA g-1 and excellent rate capability and cycling stability of 722 mA h g-1 after 200 cycles at 1 A g-1. For NIB applications, HMNC-700 offers a high initial reversible capacity of 427 mA h g-1 and stable reversible capacity of 394 mA h g-1 at 100 mA g-1.

  5. Probing the electrical properties of highly-doped Al:ZnO nanowire ensembles

    KAUST Repository

    Noriega, Rodrigo

    2010-01-01

    The analysis of transparent conducting oxide nanostructures suffers from a lack of high throughput yet quantitatively sensitive set of analytical techniques that can properly assess their electrical properties and serve both as characterization and diagnosis tools. This is addressed by applying a comprehensive set of characterization techniques to study the electrical properties of solution-grown Al-doped ZnO nanowires as a function of composition from 0 to 4 at. % Al:Zn. Carrier mobility and charge density extracted from sensitive optical absorption measurements are in agreement with those extracted from single-wire field-effect transistor devices. The mobility in undoped nanowires is 28 cm2 /V s and decreases to ∼14 cm2 /V s at the highest doping density, though the carrier density remains approximately constant (1020 cm-3) due to limited dopant activation or the creation of charge-compensating defects. Additionally, the local geometry of the Al dopant is studied by nuclear magnetic resonance, showing the occupation of a variety of dopant sites. © 2010 American Institute of Physics.

  6. High Resolution Fluorescence Imaging of Cancers Using Lanthanide Ion-Doped Upconverting Nanocrystals

    Directory of Open Access Journals (Sweden)

    John A. Capobianco

    2012-10-01

    Full Text Available During the last decade inorganic luminescent nanoparticles that emit visible light under near infrared (NIR excitation (in the biological window have played a relevant role for high resolution imaging of cancer. Indeed, semiconductor quantum dots (QDs and metal nanoparticles, mostly gold nanorods (GNRs, are already commercially available for this purpose. In this work we review the role which is being played by a relatively new class of nanoparticles, based on lanthanide ion doped nanocrystals, to target and image cancer cells using upconversion fluorescence microscopy. These nanoparticles are insulating nanocrystals that are usually doped with small percentages of two different rare earth (lanthanide ions: The excited donor ions (usually Yb3+ ion that absorb the NIR excitation and the acceptor ions (usually Er3+, Ho3+ or Tm3+, that are responsible for the emitted visible (or also near infrared radiation. The higher conversion efficiency of these nanoparticles in respect to those based on QDs and GNRs, as well as the almost independent excitation/emission properties from the particle size, make them particularly promising for fluorescence imaging. The different approaches of these novel nanoparticles devoted to "in vitro" and "in vivo" cancer imaging, selective targeting and treatment are examined in this review.

  7. Hierarchically porous carbons with optimized nitrogen doping as highly active electrocatalysts for oxygen reduction

    Science.gov (United States)

    Liang, Hai-Wei; Zhuang, Xiaodong; Brüller, Sebastian; Feng, Xinliang; Müllen, Klaus

    2014-09-01

    Development of efficient, low-cost and stable electrocatalysts as the alternative to platinum for the oxygen reduction reaction is of significance for many important electrochemical devices, such as fuel cells, metal-air batteries and chlor-alkali electrolysers. Here we report a highly active nitrogen-doped, carbon-based, metal-free oxygen reduction reaction electrocatalyst, prepared by a hard-templating synthesis, for which nitrogen-enriched aromatic polymers and colloidal silica are used as precursor and template, respectively, followed by ammonia activation. Our protocol allows for the simultaneous optimization of both porous structures and surface functionalities of nitrogen-doped carbons. Accordingly, the prepared catalysts show the highest oxygen reduction reaction activity (half-wave potential of 0.85 V versus reversible hydrogen electrode with a low loading of 0.1 mg cm-2) in alkaline media among all reported metal-free catalysts. Significantly, when used for constructing the air electrode of zinc-air battery, our metal-free catalyst outperforms the state-of the-art platinum-based catalyst.

  8. High Resolution Fluorescence Imaging of Cancers Using Lanthanide Ion-Doped Upconverting Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Naccache, Rafik; Rodríguez, Emma Martín; Bogdan, Nicoleta [Department of Chemistry and Biochemistry, Concordia University, Montreal H4B 1R6 (Canada); Sanz-Rodríguez, Francisco [Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Cruz, Maria del Carmen Iglesias de la [Departamento de Fisiología. Facultad de Medicina, Universidad Autónoma de Madrid, Madrid 28029 (Spain); Fuente, Ángeles Juarranz de la [Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Vetrone, Fiorenzo [Institut National de la Recherche Scientifique-Énergie, Matériaux et Télécommunications, Université du Québec, Varennes J3X 1S2 (Canada); Jaque, Daniel; Solé, José García, E-mail: jose.garcia_sole@uam.es [Departamento de Física de Materiales, Universidad Autónoma de Madrid, Madrid 28049 (Spain); Capobianco, John A., E-mail: jose.garcia_sole@uam.es [Department of Chemistry and Biochemistry, Concordia University, Montreal H4B 1R6 (Canada)

    2012-10-22

    During the last decade inorganic luminescent nanoparticles that emit visible light under near infrared (NIR) excitation (in the biological window) have played a relevant role for high resolution imaging of cancer. Indeed, semiconductor quantum dots (QDs) and metal nanoparticles, mostly gold nanorods (GNRs), are already commercially available for this purpose. In this work we review the role which is being played by a relatively new class of nanoparticles, based on lanthanide ion doped nanocrystals, to target and image cancer cells using upconversion fluorescence microscopy. These nanoparticles are insulating nanocrystals that are usually doped with small percentages of two different rare earth (lanthanide) ions: The excited donor ions (usually Yb{sup 3+} ion) that absorb the NIR excitation and the acceptor ions (usually Er{sup 3+}, Ho{sup 3+} or Tm{sup 3+}), that are responsible for the emitted visible (or also near infrared) radiation. The higher conversion efficiency of these nanoparticles in respect to those based on QDs and GNRs, as well as the almost independent excitation/emission properties from the particle size, make them particularly promising for fluorescence imaging. The different approaches of these novel nanoparticles devoted to “in vitro” and “in vivo” cancer imaging, selective targeting and treatment are examined in this review.

  9. Gender- and Sport-Specific Associations Between Religiousness and Doping Behavior in High-Level Team Sports.

    Science.gov (United States)

    Zvan, Milan; Zenic, Natasa; Sekulic, Damir; Cubela, Mladen; Lesnik, Blaz

    2017-08-01

    Religiousness is known to be specifically associated with substance abuse, but there is an evident lack of studies investigating the association between religiousness and doping behavior as a specific type of substance abuse in athletes. This study aimed to provide evidence for possible gender- and sport-specific associations between religiousness and doping behavior among team-sport athletes of both genders. The participants were 886 athletes (21.9 ± 3.8 years of age; 352 females) involved in four sports: volleyball (n = 154; 78 females), handball (n = 206; 68 females), soccer (n = 316; 110 females) and basketball (n = 230; 96 females) from Croatia and Slovenia (all traditionally Roman Catholics). The data were collected using a previously validated structured questionnaire that examined sociodemographic, sport- and doping-related factors. In addition, religiousness was captured by the Santa Clara Strength of Religious Faith questionnaire (SCSRF). Gender-stratified simple logistic regressions were applied to determine associations between covariates and doping behavior (criterion). There was no significant difference in potential doping behavior between males and females (OR 1.06, 95 % CI 0.76-1.46), while females reported higher religiousness (SCSRF: 23.11 ± 3.23 and 25.46 ± 7.2 for males and females, respectively; t test = 1.82, p sport and age, the SCSRF remained a significant predictor of potential doping behavior (OR 0.95, 95 % CI 0.91-0.99). For males, the belief that doping was present in sport was strongly associated with a higher likelihood of doping. Our results suggest that highly religious females involved in three of the studies sports (i.e., volleyball, handball and basketball) show a weaker tendency toward doping. Meanwhile, there is no evidence that religiousness influences doping behavior among male team-sport athletes. Therefore, sport-specific and gender-specific approach in studying possible relationships that exist

  10. 16 CFR 500.19 - Conversion of SI metric quantities to inch/pound quantities and inch/pound quantities to SI...

    Science.gov (United States)

    2010-01-01

    .../pound quantities and inch/pound quantities to SI metric quantities. 500.19 Section 500.19 Commercial... LABELING ACT § 500.19 Conversion of SI metric quantities to inch/pound quantities and inch/pound quantities to SI metric quantities. (a) For calculating the conversion of SI metric quantities to inch/pound...

  11. Three-Dimensional Porous Nitrogen-Doped NiO Nanostructures as Highly Sensitive NO2 Sensors

    Directory of Open Access Journals (Sweden)

    Van Hoang Luan

    2017-10-01

    Full Text Available Nickel oxide has been widely used in chemical sensing applications, because it has an excellent p-type semiconducting property with high chemical stability. Here, we present a novel technique of fabricating three-dimensional porous nitrogen-doped nickel oxide nanosheets as a highly sensitive NO2 sensor. The elaborate nanostructure was prepared by a simple and effective hydrothermal synthesis method. Subsequently, nitrogen doping was achieved by thermal treatment with ammonia gas. When the p-type dopant, i.e., nitrogen atoms, was introduced in the three-dimensional nanostructures, the nickel-oxide-nanosheet-based sensor showed considerable NO2 sensing ability with two-fold higher responsivity and sensitivity compared to non-doped nickel-oxide-based sensors.

  12. Phosphorus-doped silicon nanorod anodes for high power lithium-ion batteries

    Directory of Open Access Journals (Sweden)

    Chao Yan

    2017-01-01

    Full Text Available Heavy-phosphorus-doped silicon anodes were fabricated on CuO nanorods for application in high power lithium-ion batteries. Since the conductivity of lithiated CuO is significantly better than that of CuO, after the first discharge, the voltage cut-off window was then set to the range covering only the discharge–charge range of Si. Thus, the CuO core was in situ lithiated and acts merely as the electronic conductor in the following cycles. The Si anode presented herein exhibited a capacity of 990 mAh/g at the rate of 9 A/g after 100 cycles. The anode also presented a stable rate performance even at a current density as high as 20 A/g.

  13. Photo-induced current transient spectroscopy for high-resistivity neutron-transmutation-doped silicon

    International Nuclear Information System (INIS)

    Tokuda, Yutaka; Inoue, Yajiro; Usami, Akira

    1987-01-01

    Defects in high-resistivity neutron-transmutation-doped (NTD) silicon prior to annealing were studied by photo-induced current transient spectroscopy (PICTS). The thermal-neutron fluence was 9.5 x 10 17 cm -2 to give a resistivity of about 30 Ω after annealing, and the fast-neutron fluence was 9.5 x 10 16 cm -2 . Four traps with thermal emission activation energies of 0.15, 0.41. 0.47 and 0.50 eV were observed in NTD silicon. A trap with the thermal emission activation energy of 0.15 eV was considered to correspond to the divacancy. Although the clustered nature of the defects was observed, PICTS measurements suggest that the material state of high-resistivity NTD silicon is still crystalline and not amorphous. (author)

  14. 3D nitrogen-doped graphene foam with encapsulated germanium/nitrogen-doped graphene yolk-shell nanoarchitecture for high-performance flexible Li-ion battery

    Science.gov (United States)

    Mo, Runwei; Rooney, David; Sun, Kening; Yang, Hui Ying

    2017-01-01

    Flexible electrochemical energy storage devices have attracted extensive attention as promising power sources for the ever-growing field of flexible and wearable electronic products. However, the rational design of a novel electrode structure with a good flexibility, high capacity, fast charge–discharge rate and long cycling lifetimes remains a long-standing challenge for developing next-generation flexible energy-storage materials. Herein, we develop a facile and general approach to three-dimensional (3D) interconnected porous nitrogen-doped graphene foam with encapsulated Ge quantum dot/nitrogen-doped graphene yolk-shell nano architecture for high specific reversible capacity (1,220 mAh g−1), long cycling capability (over 96% reversible capacity retention from the second to 1,000 cycles) and ultra-high rate performance (over 800 mAh g−1 at 40 C). This work paves a way to develop the 3D interconnected graphene-based high-capacity electrode material systems, particularly those that suffer from huge volume expansion, for the future development of high-performance flexible energy storage systems. PMID:28051065

  15. 3D nitrogen-doped graphene foam with encapsulated germanium/nitrogen-doped graphene yolk-shell nanoarchitecture for high-performance flexible Li-ion battery

    Science.gov (United States)

    Mo, Runwei; Rooney, David; Sun, Kening; Yang, Hui Ying

    2017-01-01

    Flexible electrochemical energy storage devices have attracted extensive attention as promising power sources for the ever-growing field of flexible and wearable electronic products. However, the rational design of a novel electrode structure with a good flexibility, high capacity, fast charge-discharge rate and long cycling lifetimes remains a long-standing challenge for developing next-generation flexible energy-storage materials. Herein, we develop a facile and general approach to three-dimensional (3D) interconnected porous nitrogen-doped graphene foam with encapsulated Ge quantum dot/nitrogen-doped graphene yolk-shell nano architecture for high specific reversible capacity (1,220 mAh g-1), long cycling capability (over 96% reversible capacity retention from the second to 1,000 cycles) and ultra-high rate performance (over 800 mAh g-1 at 40 C). This work paves a way to develop the 3D interconnected graphene-based high-capacity electrode material systems, particularly those that suffer from huge volume expansion, for the future development of high-performance flexible energy storage systems.

  16. Band gap tunning in BN-doped graphene systems with high carrier mobility

    KAUST Repository

    Kaloni, T. P.

    2014-02-17

    Using density functional theory, we present a comparative study of the electronic properties of BN-doped graphene monolayer, bilayer, trilayer, and multilayer systems. In addition, we address a superlattice of pristine and BN-doped graphene. Five doping levels between 12.5% and 75% are considered, for which we obtain band gaps from 0.02 eV to 2.43 eV. We demonstrate a low effective mass of the charge carriers.

  17. Effect of germanium doping on the formation kinetics of vacancy-dioxygen complexes in high dose neutron irradiated crystalline silicon

    Science.gov (United States)

    Dong, Peng; Yu, Xuegong; Chen, Lin; Ma, Xiangyang; Yang, Deren

    2017-09-01

    The effect of germanium (Ge) doping on the formation kinetics of vacancy-dioxygen (VO2) complexes in high dose neutron irradiated crystalline silicon (c-Si) has been quantitatively investigated using infrared spectroscopy at 10 K. It is observed that Ge doping of 1019 cm-3 enhances the formation of vacancy-oxygen (VO) complexes by ˜15% during neutron irradiation and slightly suppresses the conversion of VO into VO2 complexes. By studying the generation kinetics of VO2 complexes in the temperature range of 300-345 °C, it is found that the activation energies of VO2 generation are determined to be 1.52 and 1.71 eV in the reference and Ge-doped c-Si, respectively. According to the theory for diffusion limited reactions, it is suggested that Ge doping can retard the VO diffusion in c-Si and therefore reduce the capture probability of Oi for VO complexes. This may be attributed to the temporary trapping of vacancies by Ge atoms. Hence, the formation of VO2 complexes in c-Si is slightly suppressed by Ge doping.

  18. High-Quality Fe-doped TiO2 films with Superior Visible-Light Performance

    DEFF Research Database (Denmark)

    Su, Ren; Bechstein, Ralf; Kibsgaard, Jakob

    2012-01-01

    We report on high-quality polycrystalline Fe-doped TiO2 (Fe–TiO2) porous films synthesized via one-step electrochemical oxidation. We demonstrate that delicate properties such as the impurity concentration and the microstructure that strongly influence the performance of the material...... for photovoltaic and photocatalysis applications can be controlled by adjusting the electrolyte composition. Compared to Fe-doped TiO2 films prepared with traditional phosphate- or silicate-based electrolytes, our newly synthesised Fe–TiO2 films contain solely Fe dopants, which results in excellent photocatalytic...... and photovoltaic performance under visible light irradiation....

  19. Catalyst Degradation in High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    DEFF Research Database (Denmark)

    Cleemann, Lars Nilausen; Buazar, F.; Li, Qingfeng

    2013-01-01

    confirmed by the post TEM and XRD analysis. A strong dependence of the fuel cell performance degradation on the catalyst supports was observed. Graphitization of the carbon blacks improved the stability and catalyst durability though at the expense of a significant decrease in the specific surface area......Degradation of carbon supported platinum catalysts is a major failure mode for the long term durability of high temperature proton exchange membrane fuel cells based on phosphoric acid doped polybenzimidazole membranes. With Vulcan carbon black as a reference, thermally treated carbon black...... and multi‐walled carbon nanotubes were used as supports for electrode catalysts and evaluated in accelerated durability tests under potential cycling at 150 °C. Measurements of open circuit voltage, area specific resistance and hydrogen permeation through the membrane were carried out, indicating little...

  20. Crystal orientation dependent thermoelectric properties of highly oriented aluminum-doped zinc oxide thin films

    KAUST Repository

    Abutaha, Anas I.

    2013-02-06

    We demonstrate that the thermoelectric properties of highly oriented Al-doped zinc oxide (AZO) thin films can be improved by controlling their crystal orientation. The crystal orientation of the AZO films was changed by changing the temperature of the laser deposition process on LaAlO3 (100) substrates. The change in surface termination of the LaAlO3 substrate with temperature induces a change in AZO film orientation. The anisotropic nature of electrical conductivity and Seebeck coefficient of the AZO films showed a favored thermoelectric performance in c-axis oriented films. These films gave the highest power factor of 0.26 W m−1 K−1 at 740 K.

  1. Stability of uranium(VI) doped CSH phases in high saline water

    Energy Technology Data Exchange (ETDEWEB)

    Wolter, Jan-Martin; Schmeide, Katja [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes

    2017-06-01

    To evaluate the long-term stability of U(VI) doped calcium silicate hydrate (CSH) phases at high saline conditions, leaching experiments with NaCl, NaCl/Na{sub 2}SO{sub 4} and NaCl/NaHCO{sub 3} containing solutions were performed. Time-resolved laser-induced fluorescence spectroscopy (TRLFS), infrared spectroscopy (IR) and X-ray powder diffraction (XRD) were applied to study the U(VI) binding onto the CSH phases and to get a deeper understanding of structural changes due to leaching. Results indicate that neither NaCl nor Na{sub 2}SO{sub 4} affect the structural stability of CSH phases and their retention potential for U(VI). However, carbonate containing solutions lead to a decomposition of CSH phases and thus, to a release of incorporated uranium.

  2. High conversion efficiency distributed feedback laser from a dye-doped holographic transmission grating

    Science.gov (United States)

    Liu, Lijuan; Zhang, Guiyang; Kong, Xiaobo; Liu, Yonggang; Xuan, Li

    2018-01-01

    A high conversion efficiency distributed feedback (DFB) laser from a dye-doped holographic polymer dispersed liquid crystal (HPDLC) transmission grating structure was reported. The alignment polyimide (PI) films were used to control the orientation of the phase separated liquid crystals (LCs) to increase the refractive index difference between the LC and the polymer, so it can provide better light feedback. The lasing wavelength located at 645.8 nm near the maximum of the amplified spontaneous emission (ASE) spectrum with the lowest threshold 0.97 μ J/pulse and the highest conversion efficiency 1.6% was obtained. The laser performance under electric field were also investigated and illustrated. The simple configuration, one-step fabrication organic dye laser shows the potential to realize ultra-low cost plastic lasers.

  3. High Power Tm3+-Doped Fiber Lasers Tuned by a Variable Reflective Output Coupler

    Directory of Open Access Journals (Sweden)

    Yulong Tang

    2008-01-01

    Full Text Available Wide wavelength tuning by a variable reflective output coupler is demonstrated in high-power double-clad Tm3+-doped silica fiber lasers diode-pumped at ∼790  nm. Varying the output coupling from 96% to 5%, the laser wavelength is tuned over a range of 106  nm from 1949 to 2055  nm. The output power exceeds 20  W over 90-nm range and the maximum output power is 32  W at 1949  nm for 51-W launched pump power, corresponding to a slope efficiency of ∼70%. Assisted with different fiber lengths, the tuning range is expanded to 240  nm from 1866 to 2107  nm with the output power larger than 10  W.

  4. High temperature thermoelectric properties of strontium titanate thin films with oxygen vacancy and niobium doping

    KAUST Repository

    Sarath Kumar, S. R.

    2013-08-14

    We report the evolution of high temperature thermoelectric properties of SrTiO3 thin films doped with Nb and oxygen vacancies. Structure-property relations in this important thermoelectric oxide are elucidated and the variation of transport properties with dopant concentrations is discussed. Oxygen vacancies are incorporated during growth or annealing in Ar/H2 above 800 K. An increase in lattice constant due to the inclusion of Nb and oxygen vacancies is found to result in an increase in carrier density and electrical conductivity with simultaneous decrease in carrier effective mass and Seebeck coefficient. The lattice thermal conductivity at 300 K is found to be 2.22 W m-1 K-1, and the estimated figure of merit is 0.29 at 1000 K. © 2013 American Chemical Society.

  5. Highly Dispersed Re-Doped CoAl2O4 Nanopigments: Synthesis and Chromatic Properties

    Directory of Open Access Journals (Sweden)

    Yuping Tong

    2016-01-01

    Full Text Available Nanosized spinel CoAl2-xRexO4 complex oxides were prepared by self-propagation combustion method. The products have been characterized by XRD, SEM, and EDS. The results indicated that Al3+ can be partly replaced by Re3+ when the doped amount is less than 10%, which forms single solid solution. The NIR reflectance and chromatic properties of samples have also been investigated. The substitution of Re3+ for Al3+ in CoAl2O4 can increase the blueness of pigments. SEM results revealed that the obtained CoAl2-xRexO4 pigments consisted of highly dispersed spherical-like nanoparticles with uniform size distribution. EDS results indicated that the distribution of element was considerably uniform with no chemical segregation phenomenon.

  6. The Electrical Properties of Tb-Doped CaF2 Nanoparticles under High Pressure

    Directory of Open Access Journals (Sweden)

    Tingjing Hu

    2018-02-01

    Full Text Available The high-pressure transport behavior of CaF2 nanoparticles with 3 mol% Tb concentrations was studied by alternate-current impedance measurement. All of the electrical parameters vary abnormally at approximately 10.76 GPa, corresponding to the fluorite-cotunnite structural transition. The substitution of Ca2+ by Tb3+ leads to deformation in the lattice, and finally lowers the transition pressure. The F− ions diffusion, electronic transport, and charge-discharge process become more difficult with the rising pressure. In the electronic transport process, defects at grains play a dominant role. The charge carriers include both F− ions and electrons, and electrons are dominant in the transport process. The Tb doping improves the pressure effect on the transport behavior of CaF2 nanocrystals.

  7. High pressure in-situ X-ray diffraction study on Zn-doped magnetite nanoparticles

    Science.gov (United States)

    Ferrari, S.; Bilovol, V.; Pampillo, L. G.; Grinblat, F.; Errandonea, D.

    2018-03-01

    We have performed high pressure synchrotron X-ray powder diffraction experiments on two different samples of Zn-doped magnetite nanoparticles (formula Fe(3-x)ZnxO4; x = 0.2, 0.5). The structural behavior of then a noparticles was studied up to 13.5 GPa for x = 0.2, and up to 17.4 GPa for x = 0.5. We have found that both systems remain in the cubic spinel structure as expected for this range of applied pressures. The analysis of the unit cell volume vs. pressure results in bulk modulus values lower than in both end-members, magnetite (Fe3O4) and zinc ferrite (ZnFe2O4), suggesting that chemical disorder may favor compressibility, which is expected to improve the increase of the Neel temperature under compression.

  8. Effect of fabrication parameters on morphological and optical properties of highly doped p-porous silicon

    Science.gov (United States)

    Zare, Maryam; Shokrollahi, Abbas; Seraji, Faramarz E.

    2011-09-01

    Porous silicon (PS) layers were fabricated by anodization of low resistive (highly doped) p-type silicon in HF/ethanol solution, by varying current density, etching time and HF concentration. Atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM) analyses were used to investigate the physical properties and reflection spectrum was used to investigate the optical behavior of PS layers in different fabrication conditions. Vertically aligned mesoporous morphology is observed in fabricated films and with HF concentration higher than 20%. The dependence of porosity, layer thickness and rms roughness of the PS layer on current density, etching time and composition of electrolyte is also observed in obtained results. Correlation between reflectivity and fabrication parameters was also explored. Thermal oxidation was performed on some mesoporous layers that resulted in changes of surface roughness, mean height and reflectivity of the layers.

  9. Highly Luminescent Heterostructured Copper-Doped Zinc Sulfide Nanocrystals for Application in Cancer Cell Labeling.

    Science.gov (United States)

    Ang, Huixiang; Bosman, Michel; Thamankar, Ramesh; Zulkifli, Muhammad Faizal B; Yen, Swee Kuan; Hariharan, Anushya; Sudhaharan, Thankiah; Selvan, Subramanian Tamil

    2016-08-18

    The structural characteristics of the seed-mediated synthesis of heterostructured CuS-ZnS nanocrystals (NCs) and Cu-doped ZnS (ZnS:Cu) NCs synthesized by two different protocols are compared and analyzed. At high Cu dopant concentrations, segregated subclusters of ZnS and CuS are observed. The photoluminescence quantum yield of ZnS:Cu NCs is about 50-80 %; a value much higher than that of ZnS NCs (6 %). Finally, these NCs are coated with a thin silica shell by using (3-mercaptopropyl)triethoxysilane in a reverse microemulsion to make them water soluble. Cytotoxicity experiments show that these silica-coated NCs have greatly reduced toxicity on both cancerous HeLa and noncancerous Chinese hamster ovary cells. The labeling of cancerous HeLa cells is also demonstrated. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Crumpled Nitrogen-Doped Graphene for Supercapacitors with High Gravimetric and Volumetric Performances.

    Science.gov (United States)

    Wang, Jie; Ding, Bing; Xu, Yunling; Shen, Laifa; Dou, Hui; Zhang, Xiaogang

    2015-10-14

    Graphene is considered a promising electrochemical capacitors electrode material due to its high surface area and high electrical conductivity. However, restacking interactions between graphene nanosheets significantly decrease the ion-accessible surface area and impede electronic and ionic transfer. This would, in turn, severely hinder the realization of high energy density. Herein, we report a strategy for preparation of few-layer graphene material with abundant crumples and high-level nitrogen doping. The two-dimensional graphene nanosheets (CNG) feature high ion-available surface area, excellent electronic and ion transfer properties, and high packing density, permitting the CNG electrode to exhibit excellent electrochemical performance. In ionic liquid electrolyte, the CNG electrode exhibits gravimetric and volumetric capacitances of 128 F g(-1) and 98 F cm(-3), respectively, achieving gravimetric and volumetric energy densities of 56 Wh kg(-1) and 43 Wh L(-1). The preparation strategy described here provides a new approach for developing a graphene-based supercapacitor with high gravimetric and volumetric energy densities.

  11. Airplane dopes and doping

    Science.gov (United States)

    Smith, W H

    1919-01-01

    Cellulose acetate and cellulose nitrate are the important constituents of airplane dopes in use at the present time, but planes were treated with other materials in the experimental stages of flying. The above compounds belong to the class of colloids and are of value because they produce a shrinking action on the fabric when drying out of solution, rendering it drum tight. Other colloids possessing the same property have been proposed and tried. In the first stages of the development of dope, however, shrinkage was not considered. The fabric was treated merely to render it waterproof. The first airplanes constructed were covered with cotton fabric stretched as tightly as possible over the winds, fuselage, etc., and flying was possible only in fine weather. The necessity of an airplane which would fly under all weather conditions at once became apparent. Then followed experiments with rubberized fabrics, fabrics treated with glue rendered insoluble by formaldehyde or bichromate, fabrics treated with drying and nondrying oils, shellac, casein, etc. It was found that fabrics treated as above lost their tension in damp weather, and the oil from the motor penetrated the proofing material and weakened the fabric. For the most part the film of material lacked durability. Cellulose nitrate lacquers, however were found to be more satisfactory under varying weather conditions, added less weight to the planes, and were easily applied. On the other hand, they were highly inflammable, and oil from the motor penetrated the film of cellulose nitrate, causing the tension of the fabric to be relaxed.

  12. Boron-Doped Graphite for High Work Function Carbon Electrode in Printable Hole-Conductor-Free Mesoscopic Perovskite Solar Cells.

    Science.gov (United States)

    Duan, Miao; Tian, Chengbo; Hu, Yue; Mei, Anyi; Rong, Yaoguang; Xiong, Yuli; Xu, Mi; Sheng, Yusong; Jiang, Pei; Hou, Xiaomeng; Zhu, Xiaotong; Qin, Fei; Han, Hongwei

    2017-09-20

    Work function of carbon electrodes is critical in obtaining high open-circuit voltage as well as high device performance for carbon-based perovskite solar cells. Herein, we propose a novel strategy to upshift work function of carbon electrode by incorporating boron atom into graphite lattice and employ it in printable hole-conductor-free mesoscopic perovskite solar cells. The high-work-function boron-doped carbon electrode facilitates hole extraction from perovskite as verified by photoluminescence. Meanwhile, the carbon electrode is endowed with an improved conductivity because of a higher graphitization carbon of boron-doped graphite. These advantages of the boron-doped carbon electrode result in a low charge transfer resistance at carbon/perovskite interface and an extended carrier recombination lifetime. Together with the merit of both high work function and conductivity, the power conversion efficiency of hole-conductor-free mesoscopic perovskite solar cells is increased from 12.4% for the pristine graphite electrode-based cells to 13.6% for the boron-doped graphite electrode-based cells with an enhanced open-circuit voltage and fill factor.

  13. Large-scale high aspect ratio Al-doped ZnO nanopillars arrays as anisotropic metamaterials

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Takayama, Osamu; Panah, Mohammad Esmail Aryaee

    2017-01-01

    High aspect ratio free-standing Al-doped ZnO (AZO) nanopillars and nanotubes were fabricated using a combination of advanced reactive ion etching and atomic layer deposition (ALD) techniques. Prior to the pillar and tube fabrication, AZO layers were grown on flat silicon and glass substrates with...

  14. Lowering the platinum loading of high temperature polymer electrolyte membrane fuel cells with acid doped polybenzimidazole membranes

    DEFF Research Database (Denmark)

    Fernandez, Santiago Martin; Li, Qingfeng; Jensen, Jens Oluf

    2015-01-01

    Membrane electrode assemblies (MEAs) with ultra-low Pt loading electrodes were prepared for high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) based on acid doped polybenzimidazole. With no electrode binders or ionomers, the triple phase boundary of the catalyst layer was establ...

  15. High repetition rate Q-switched Er3+-doped fiber ring laser

    DEFF Research Database (Denmark)

    Sejka, Milan; Poulsen, Christian; Shi, Yuan

    1993-01-01

    In this paper we present for the first time Q switched Er-doped fibre laser utilising a ring Fabry-Perot cavity......In this paper we present for the first time Q switched Er-doped fibre laser utilising a ring Fabry-Perot cavity...

  16. Progress in efficient doping of high aluminum-containing group III-nitrides

    Science.gov (United States)

    Liang, Y.-H.; Towe, E.

    2018-03-01

    The group III-nitride (InN, GaN, and AlN) class of semiconductors has become one of two that are critical to a number of technologies in modern life—the other being silicon. Light-emitting diodes made from (In,Ga)N, for example, dominate recent innovations in general illumination and signaling. Even though the (In,Ga)N materials system is fairly well established and widely used in advanced devices, challenges continue to impede development of devices that include aluminum-containing nitride films such as (Al,Ga)N. The main difficulty is efficient doping of films with aluminum-rich compositions; the problem is particularly severe for p-type doping, which is essential for Ohmic contacts to bipolar device structures. This review briefly summarizes the fundamental issues related to p-type doping, and then discusses a number of approaches that are being pursued to resolve the doping problem or for circumventing the need for p-type doping. Finally, we discuss an approach to doping under liquid-metal-enabled growth by molecular beam epitaxy. Recent results from a number of groups appear to indicate that p-type doping of nitride films under liquid-metal-enabled growth conditions might offer a solution to the doping problem—at least for materials grown by molecular beam epitaxy.

  17. Phosphoric acid doped AB-PBI membranes and its applications in high temperature PEMFC

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Bjerrum, Niels

    2005-01-01

    in a wide temperature range.. The conductivity of the acid doped ab-PBI membranes was studied in a temperature range of 80oC to 200oC under different relative humidity and with different acid doping levels. PEMFC test results indicated that the fuel cell could be operated at temperatures up to 200o...

  18. High gain L-band erbium-doped fiber amplifier with two-stage ...

    Indian Academy of Sciences (India)

    stage erbium-doped fiber amplifier; amplified spontaneous emission. Abstract. An experiment on gain enhancement in the long wavelength band erbium-doped fiber amplifier (L-band EDFA) is demonstrated using dual forward pumping scheme ...

  19. Plasma-induced high efficient synthesis of boron doped reduced graphene oxide for supercapacitors

    DEFF Research Database (Denmark)

    Li, Shaobo; Wang, Zhaofeng; Jiang, Hanmei

    2016-01-01

    In this work, we presented a novel route to synthesize boron doped reduced graphene oxide (rGO) by using the dielectric barrier discharge (DBD) plasma technology under ambient conditions. The doping of boron (1.4 at%) led to a significant improvement in the capacitance of rGO and supercapacitors...

  20. Highly photosensitive polymethyl methacrylate microstructured polymer optical fiber with doped core

    DEFF Research Database (Denmark)

    Sáez-Rodríguez, D.; Nielsen, Kristian; Rasmussen, Henrik K.

    2013-01-01

    , providing a grating with a strong transmission rejection of −23  dB with an inscription time of only 13 min. The fabrication method has a big advantage compared to doping step index fiber since it enables doping of the fiber without using extra dopants to compensate for the index reduction in the core...

  1. [Microstructure and spectral property of Er3+ doped transparent oxyfluoride glass ceramics with high fluorine contents].

    Science.gov (United States)

    Lin, Le-Jing; Ren, Guo-Zhong; Chen, Min-Peng; Liu, Yang

    2009-12-01

    The microstructure and spectral properties of Er3+ doped transparent oxyfluoride glass ceramics with high fluorine content were reported. Two samples with the same initial contents (50SiO2-45PbF2-5PbO-1ErF3) were prepared under the different preparation parameters. The final fluorine contents were detected by a fluoride ion selective electrode. The results shows that the final fluorine contents increase by covering crucibles with corundum lid during melt. The samples were characterized by X-ray diffraction, transmission electron microscopy (TEM), absorption spectra and upconversion luminescence spectra. The results show that PbF2 crystals were precipitated in the sample with high fluorine content before heat treatment. And the PbF2 crystals precipitated inside the glass matrix are spherical with diameters of approximately 10-15 nm in size from the high resolution TEM micrograph. The absorption spectra, J-O parameters and the upconversion spectra show that the Er3+ ions were located in crystalline and vitreous mixed states. It is different from the sample with low fluorine content which is completely amorphous. After heat treatment, Er3+ ions that remain in the glassy phase entered into fluoride nanocrystals in the sample with high fluorine content. The fluorine environment decreases non-radiative transfer which eases the upconversion processes. Hence, the upconversion luminescence intensity of Er3+ ions in the high fluorine content sample after heat treatment is much stronger than that in the precursor sample.

  2. A confined "microreactor" synthesis strategy to three dimensional nitrogen-doped graphene for high-performance sodium ion battery anodes

    Science.gov (United States)

    Li, Jiajie; Zhang, Yumin; Gao, Tangling; Han, Jiecai; Wang, Xianjie; Hultman, Benjamin; Xu, Ping; Zhang, Zhihua; Wu, Gang; Song, Bo

    2018-02-01

    In virtue of abundant sodium resources, sodium ion batteries (SIBs) have been regarded as one of the most promising alternatives for large-scale energy storage applications. However, the absence of a suitable anode material makes it difficult to realize these applications. Here, we demonstrate an effective synthesis strategy of using a "microreactor" consisting of melamine fiber (inside) and graphene oxide (GO, outside) to fabricate three dimensional (3D) nitrogen doped (N-doped) graphene as high-performance anode materials for sodium ion batteries. Through a controlled pyrolysis, the inside melamine fiber and the outside GO layer has been converted into N-doped graphene and reduced graphene oxide (r-GO) respectively, and thus the "microreactor" is transformed into interconnected 3D N-doped graphene structures. Such highly desired 3D graphene structures show reversible sodium storage capacities up to ∼305 mA h g-1 after 500 cycles at a current density of 0.2 A g-1 and promising long cycling stability with a stable capacity of ∼198 mA h g-1 at 5 A g-1 after 5000 cycles. The high capacity and superior durability in combination with the facile synthesis procedure of the 3D graphene structure make it a promising anode material for SIBs and other energy storage applications.

  3. Temperature-dependent stimulated emission cross section and concentration quenching in highly doped Nd3+:YAG crystals

    International Nuclear Information System (INIS)

    Dong, Jun; Rapaport, A.; Bass, M.; Szipocs, F.; Ueda, Ken-ichi

    2005-01-01

    Measurements are reported of the spectroscopic properties (absorption and emission spectra, stimulated emission cross section, and radiative lifetime) of Nd:YAG crystals doped with 1, 2 and 3 at% Nd 3+ in the temperature range between 70 and 300 K. The stimulated emission cross sections for these crystals were determined using the Fuechtbauer-Ladenburg (F-L) formula at each different temperature. The absorption spectra at room temperature were used to calculate the 4 F 3/2 → 4 I 11/2 stimulated-emission cross section and the 4 F 3/2 radiative lifetime according to Judd-Ofelt theory. As the temperature decreases the emission cross section increases, while the emission lifetime remains constant for all the samples. The temperature dependences of the stimulated emission cross sections for the differently doped crystals are in good agreement with earlier predictions. The concentration quenching effect in highly doped Nd:YAG was also addressed. Although there is concentration quenching in the highly doped Nd:YAG crystals, they are still promising efficient laser materials for high-power microchip solid-state lasers. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Simplifying and expanding analytical capabilities for various classes of doping agents by means of direct urine injection high performance liquid chromatography high resolution/high accuracy mass spectrometry.

    Science.gov (United States)

    Görgens, Christian; Guddat, Sven; Thomas, Andreas; Wachsmuth, Philipp; Orlovius, Anne-Katrin; Sigmund, Gerd; Thevis, Mario; Schänzer, Wilhelm

    2016-11-30

    So far, in sports drug testing compounds of different classes are processed and measured using different screening procedures. The constantly increasing number of samples in doping analysis, as well as the large number of substances with doping related, pharmacological effects require the development of even more powerful assays than those already employed in sports drug testing, indispensably with reduced sample preparation procedures. The analysis of native urine samples after direct injection provides a promising analytical approach, which thereby possesses a broad applicability to many different compounds and their metabolites, without a time-consuming sample preparation. In this study, a novel multi-target approach based on liquid chromatography and high resolution/high accuracy mass spectrometry is presented to screen for more than 200 analytes of various classes of doping agents far below the required detection limits in sports drug testing. Here, classic groups of drugs as diuretics, stimulants, β 2 -agonists, narcotics and anabolic androgenic steroids as well as various newer target compounds like hypoxia-inducible factor (HIF) stabilizers, selective androgen receptor modulators (SARMs), selective estrogen receptor modulators (SERMs), plasma volume expanders and other doping related compounds, listed in the 2016 WADA prohibited list were implemented. As a main achievement, growth hormone releasing peptides could be implemented, which chemically belong to the group of small peptides (0.99), limit of detection (0.1-25ng/mL; 3'OH-stanozolol glucuronide: 50pg/mL; dextran/HES: 10μg/mL) and matrix effects. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. High-Surface-Area Nitrogen-Doped Reduced Graphene Oxide for Electric Double-Layer Capacitors.

    Science.gov (United States)

    Youn, Hee-Chang; Bak, Seong-Min; Kim, Myeong-Seong; Jaye, Cherno; Fischer, Daniel A; Lee, Chang-Wook; Yang, Xiao-Qing; Roh, Kwang Chul; Kim, Kwang-Bum

    2015-06-08

    A two-step method consisting of solid-state microwave irradiation and heat treatment under NH3 gas was used to prepare nitrogen-doped reduced graphene oxide (N-RGO) with a high specific surface area (1007 m(2)  g(-1) ), high electrical conductivity (1532 S m(-1) ), and low oxygen content (1.5 wt %) for electrical double-layer capacitor applications. The specific capacitance of N-RGO was 291 F g(-1) at a current density of 1 A g(-1) , and a capacitance of 261 F g(-1) was retained at 50 A g(-1) , which indicated a very good rate capability. N-RGO also showed excellent cycling stability and preserved 96 % of the initial specific capacitance after 100 000 cycles. Near-edge X-ray absorption fine-structure spectroscopy results provided evidenced for the recovery of π conjugation in the carbon networks with the removal of oxygenated groups and revealed chemical bonding of the nitrogen atoms in N-RGO. The good electrochemical performance of N-RGO is attributed to its high surface area, high electrical conductivity, and low oxygen content. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Boron doped diamond synthesized from detonation nanodiamond in a C-O-H fluid at high pressure and high temperature

    Science.gov (United States)

    Shakhov, Fedor M.; Abyzov, Andrey M.; Takai, Kazuyuki

    2017-12-01

    Boron doped diamond (BDD) was synthesized under high pressure and high temperature (HPHT) of 7 GPa, 1230 °C in a short time of 10 s from a powder mixtures of detonation nanodiamond (DND), pentaerythritol C5H8(OH)4 and amorphous boron. SEM, TEM, XRD, XPS, FTIR and Raman spectroscopy indicated that BDD nano- and micro-crystals have formed by consolidation of DND particles (4 nm in size). XRD showed the enlargement of crystallites size to 6-80 nm and the increase in diamond lattice parameter by 0.02-0.07% without appearance of any microstrains. Raman spectroscopy was used to estimate the content of boron atoms embedded in the diamond lattice. It was found that the Raman diamond peak shifts significantly from 1332 cm-1 to 1290 cm-1 without appearance of any non-diamond carbon. The correlation between Raman peak position, its width, and boron content in diamond is proposed. Hydrogenated diamond carbon in significant amount was detected by IR spectroscopy and XPS. Due to the doping with boron content of about 0.1 at%, the electrical conductivity of the diamond achieved approximately 0.2 Ω-1 cm-1. Reaction mechanism of diamond growth (models of recrystallization and oriented attachment) is discussed, including the initial stages of pentaerythritol pyrolysis and thermal desorption of functional groups from the surface of DND particles with the generation of supercritical fluid of low-molecular substances (H2O, CH4, CO, CO2, etc.), as well as byproducts formation (B2O3, B4C).

  7. Boron-doped diamond heater and its application to large-volume, high-pressure, and high-temperature experiments.

    Science.gov (United States)

    Shatskiy, Anton; Yamazaki, Daisuke; Morard, Guillaume; Cooray, Titus; Matsuzaki, Takuya; Higo, Yuji; Funakoshi, Ken-ichi; Sumiya, Hitoshi; Ito, Eiji; Katsura, Tomoo

    2009-02-01

    A temperature of 3500 degrees C was generated using a diamond resistance heater in a large-volume Kawai-type high-pressure apparatus. Re and LaCrO(3) have conventionally been used for heaters in high-pressure studies but they cannot generate temperatures higher than 2900 degrees C and make in situ x-ray observations difficult due to their high x-ray absorption. Using a boron-doped diamond heater overcomes these problems and achieves stable temperature generation for pressure over 10 GPa. The heater starting material is a cold-compressed mixture of graphite with boron used to avoid the manufacturing difficulties due to the extreme hardness of diamond. The diamond heater was synthesized in situ from the boron-graphite mixture at temperature of 1600+/-100 degrees C and pressure of 20 GPa. By using the proposed technique, we have employed the diamond heater for high-temperature generation in a large-volume high-pressure apparatus. Achievement of temperatures above 3000 degrees C allows us to measure the melting points of the important constituents in earth's mantle (MgSiO(3), SiO(2), and Al(2)O(3)) and core (Fe and Ni) at extremely high pressures.

  8. Nitrogen-doped Carbon Microfiber with Wrinkled Surface for High Performance Supercapacitors

    Science.gov (United States)

    Liu, Ruili; Pan, Lixia; Jiang, Jianzhong; Xi, Xin; Liu, Xiaoxue; Wu, Dongqing

    2016-02-01

    In this work, nitrogen-doped carbon microfiber (NCMF) is fabricated via a facile co-assembly of natural silk and graphene oxide (GO) and the following thermal treatment. The amphiphilic nature of GO endows NCMF a crumpled surface with a high surface area of 115 m2 g-1. As the binder-free electrode in electrical double-layer capacitors, NCMF shows an excellent capacitance of 196 F g-1 at scan rate of 5 mV s-1, which is almost four times higher than that of the pristine CMF from silk (55 F g-1). Additionally, the capacitance of NCMF can be kept around 92 F g-1 at a high scan rate of 300 mV s-1 even after 10000 cycles. More importantly, a high energy density (≈22.7 μW h cm-2) and power density (≈10.26 mW cm-2) are achieved by the all-solid-state supercapacitor based on NCMF.

  9. Gold-doped graphene: A highly stable and active electrocatalysts for the oxygen reduction reaction.

    Science.gov (United States)

    Stolbov, Sergey; Alcántara Ortigoza, Marisol

    2015-04-21

    In addressing the growing need of renewable and sustainable energy resources, hydrogen-fuel-cells stand as one of the most promising routes to transform the current energy paradigm into one that integrally fulfills environmental sustainability. Nevertheless, accomplishing this technology at a large scale demands to surpass the efficiency and enhance the cost-effectiveness of platinum-based cathodes, which catalyze the oxygen reduction reaction (ORR). In this work, our first-principles calculations show that Au atoms incorporated into graphene di-vacancies form a highly stable and cost-effective electrocatalyst that is, at the same time, as or more (dependently of the dopant concentration) active toward ORR than the best-known Pt-based electrocatalysts. We reveal that partial passivation of defected-graphene by gold atoms reduces the reactivity of C dangling bonds and increases that of Au, thus optimizing them for catalyzing the ORR and yielding a system of high thermodynamic and electrochemical stabilities. We also demonstrate that the linear relation among the binding energies of the reaction intermediates assumed in computational high-throughput material screening does not hold, at least for this non-purely transition-metal material. We expect Au-doped graphene to finally overcome the cathode-related challenge hindering the realization of hydrogen-fuel cells as the leading means of powering transportation and portable devices.

  10. Gold-doped graphene: A highly stable and active electrocatalysts for the oxygen reduction reaction

    International Nuclear Information System (INIS)

    Stolbov, Sergey; Alcántara Ortigoza, Marisol

    2015-01-01

    In addressing the growing need of renewable and sustainable energy resources, hydrogen-fuel-cells stand as one of the most promising routes to transform the current energy paradigm into one that integrally fulfills environmental sustainability. Nevertheless, accomplishing this technology at a large scale demands to surpass the efficiency and enhance the cost-effectiveness of platinum-based cathodes, which catalyze the oxygen reduction reaction (ORR). In this work, our first-principles calculations show that Au atoms incorporated into graphene di-vacancies form a highly stable and cost-effective electrocatalyst that is, at the same time, as or more (dependently of the dopant concentration) active toward ORR than the best-known Pt-based electrocatalysts. We reveal that partial passivation of defected-graphene by gold atoms reduces the reactivity of C dangling bonds and increases that of Au, thus optimizing them for catalyzing the ORR and yielding a system of high thermodynamic and electrochemical stabilities. We also demonstrate that the linear relation among the binding energies of the reaction intermediates assumed in computational high-throughput material screening does not hold, at least for this non-purely transition-metal material. We expect Au-doped graphene to finally overcome the cathode-related challenge hindering the realization of hydrogen-fuel cells as the leading means of powering transportation and portable devices

  11. High energy transmission of Al2O3 doped with light transition metals

    KAUST Repository

    Schuster, Cosima

    2012-01-31

    The transmission of transparent colored ceramics based on Al2O3doped with light transition metals is measured in the visible and infrared range. To clarify the role of the dopands we perform ab initiocalculations. We discuss the electronic structure and present optical spectra obtained in the independent particle approximation. We argue that the gross spectral features of Co- and Ni-doped Al2O3 samples are described by our model, while the validity of the approach is limited for Cr-doped Al2O3.

  12. High-temperature ionic and electronic resistivity of MgO- and Ta2O5- doped aluminum nitride

    Science.gov (United States)

    Yu, Dongsu; Lee, Eunsil; Lee, Sung-Min; Kim, Jong-Young; Park, Myung Ha

    2018-01-01

    In this work, using high-temperature impedance spectroscopy and microstructure analysis, we investigated the ionic and the electronic transport properties of aluminum nitride materials doped with MgO and Ta2O5 at temperatures up to 773 K. The electronic conductivity, due to the electron carrier, was greatly inhibited by addition of MgO, which might be due to the decreased electron carrier concentration via electronic compensation of MgO in the AlN matrix. The ionic conductivity due to grains of MgO-doped AlN increased by several orders of magnitude due to ionic defects generated by MgO substitution, whereas the ionic conductivity of the grain boundary of MgO-doped AlN decreased by one order of magnitude as a result of the formation of Mg'Al defects in the grain boundary, which elevated the Schottky barrier. The microstructural analysis showed that MgO addition promoted formation of an amorphous liquid phase including Mg, which is evidence of the selective precipitation of Mg in the grain boundary. Ta2O5-doped AlN also exhibited a decreased ionic conductivity of the grain boundary, which might have been due to the formation of an ionic pair of (ON ·-V‴Al) caused by the dissolution of Ta in the AlN matrix.

  13. Synthesis of biocompatible and highly photoluminescent nitrogen doped carbon dots from lime: Analytical applications and optimization using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Barati, Ali [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of); Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Arkan, Elham [Nano Drug Delivery Research Center Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Hosseinzadeh, Leila [Novel Drug Delivery Research Center, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah (Iran, Islamic Republic of); Abdollahi, Hamid, E-mail: abd@iasbs.ac.ir [Faculty of Chemistry, Institute for Advanced Studies in Basic Sciences, Zanjan (Iran, Islamic Republic of)

    2015-02-01

    Herein, a facile hydrothermal treatment of lime juice to prepare biocompatible nitrogen-doped carbon quantum dots (N-CQDs) in the presence of ammonium bicarbonate as a nitrogen source has been presented. The resulting N-CQDs exhibited excitation and pH independent emission behavior; with the quantum yield (QY) up to 40%, which was several times greater than the corresponding value for CQDs with no added nitrogen source. The N-CQDs were applied as a fluorescent probe for the sensitive and selective detection of Hg{sup 2+} ions with a detection limit of 14 nM. Moreover, the cellular uptake and cytotoxicity of N-CQDs at different concentration ranges from 0.0 to 0.8 mg/ml were investigated by using PC12 cells as a model system. Response surface methodology was used for optimization and systematic investigation of the main variables that influence the QY, including reaction time, reaction temperature, and ammonium bicarbonate weight. - Highlights: • High fluorescent N-doped CQDs from lime juice have been prepared. • Response surface methodology was used to optimize and model the main factors. • N-doped CQDs were used in the selective and sensitive detection of Hg(II). • The biocompatibility of prepared N-doped CQDs was conformed using PC12 cells.

  14. Facile synthesis high nitrogen-doped porous carbon nanosheet from pomelo peel and as catalyst support for nitrobenzene hydrogenation

    Science.gov (United States)

    Zuo, Pingping; Duan, Jiaqi; Fan, Huailin; Qu, Shijie; Shen, Wenzhong

    2018-03-01

    Nitrogen-doping porous carbon-based nanosheets were fabricated from pemole peel and melamine through hydrothermal route and carbonization. The pomelo peel with sponge-like natural structure was employed as carbon source, and melamine was used both as nitrogen precursors and as nanosheet structure directing. The morphology and chemical composition of the obtained porous carbon nanosheet carbon materials were characterized by scanning electron microscopy, thermogravimetric analyzer, Fourier transform infrared spectra, transmission electron microscopy, BET surface area measurement, X-ray photoelectron spectroscopy and X-ray powder diffraction. The result indicated that the nanosheet thickness, nitrogen-doped amount and surface area were determined by the ratio of pomelo peel to melamine and carbonization temperature. The catalytic nitrobenzene hydrogenation was evaluated after Pd was loaded on nitrogen-doping porous carbon-based nanosheet. The results showed Pd@PCN had almost 100% conversion and good cycling performance towards the hydrogenation of nitrobenzene due to the developed pore structure, high nitrogen-doping and well dispersed less Pd particle; it was superior to other nanomaterial supports and demonstrated great potential application.

  15. Optimization of Electrochemical Performance of LiFePO4/C by Indium Doping and High Temperature Annealing

    Directory of Open Access Journals (Sweden)

    Ajay Kumar

    2017-10-01

    Full Text Available We have prepared nano-structured In-doped (1 mol % LiFePO4/C samples by sol–gel method followed by a selective high temperature (600 and 700 °C annealing in a reducing environment of flowing Ar/H2 atmosphere. The crystal structure, particle size, morphology, and magnetic properties of nano-composites were characterized by X-ray diffraction (XRD, scanning electron microsopy (SEM, transmission electron microscopy (TEM, and 57Fe Mössbauer spectroscopy. The Rietveld refinement of XRD patterns of the nano-composites were indexed to the olivine crystal structure of LiFePO4 with space group Pnma, showing minor impurities of Fe2P and Li3PO4 due to decomposition of LiFePO4. We found that the doping of In in LiFePO4/C nanocomposites affects the amount of decomposed products, when compared to the un-doped ones treated under similar conditions. An optimum amount of Fe2P present in the In-doped samples enhances the electronic conductivity to achieve a much improved electrochemical performance. The galvanostatic charge/discharge curves show a significant improvement in the electrochemical performance of 700 °C annealed In-doped-LiFePO4/C sample with a discharge capacity of 142 mAh·g−1 at 1 C rate, better rate capability (~128 mAh·g−1 at 10 C rate, ~75% of the theoretical capacity and excellent cyclic stability (96% retention after 250 cycles compared to other samples. This enhancement in electrochemical performance is consistent with the results of our electrochemical impedance spectroscopy measurements showing decreased charge-transfer resistance and high exchange current density.

  16. High-throughput combinatorial chemical bath deposition: The case of doping Cu (In, Ga) Se film with antimony

    Science.gov (United States)

    Yan, Zongkai; Zhang, Xiaokun; Li, Guang; Cui, Yuxing; Jiang, Zhaolian; Liu, Wen; Peng, Zhi; Xiang, Yong

    2018-01-01

    The conventional methods for designing and preparing thin film based on wet process remain a challenge due to disadvantages such as time-consuming and ineffective, which hinders the development of novel materials. Herein, we present a high-throughput combinatorial technique for continuous thin film preparation relied on chemical bath deposition (CBD). The method is ideally used to prepare high-throughput combinatorial material library with low decomposition temperatures and high water- or oxygen-sensitivity at relatively high-temperature. To check this system, a Cu(In, Ga)Se (CIGS) thin films library doped with 0-19.04 at.% of antimony (Sb) was taken as an example to evaluate the regulation of varying Sb doping concentration on the grain growth, structure, morphology and electrical properties of CIGS thin film systemically. Combined with the Energy Dispersive Spectrometer (EDS), X-ray Photoelectron Spectroscopy (XPS), automated X-ray Diffraction (XRD) for rapid screening and Localized Electrochemical Impedance Spectroscopy (LEIS), it was confirmed that this combinatorial high-throughput system could be used to identify the composition with the optimal grain orientation growth, microstructure and electrical properties systematically, through accurately monitoring the doping content and material composition. According to the characterization results, a Sb2Se3 quasi-liquid phase promoted CIGS film-growth model has been put forward. In addition to CIGS thin film reported here, the combinatorial CBD also could be applied to the high-throughput screening of other sulfide thin film material systems.

  17. Optoelectrochemical biorecognition by optically transparent highly conductive graphene-modified fluorine-doped tin oxide substrates.

    Science.gov (United States)

    Lamberti, F; Brigo, L; Favaro, M; Luni, C; Zoso, A; Cattelan, M; Agnoli, S; Brusatin, G; Granozzi, G; Giomo, M; Elvassore, N

    2014-12-24

    Both optical and electrochemical graphene-based sensors have gone through rapid development, reaching high sensitivity at low cost and with fast response time. However, the complex validating biochemical operations, needed for their consistent use, currently limits their effective application. We propose an integration strategy for optoelectrochemical detection that overcomes previous limitations of these sensors used separately. We develop an optoelectrochemical sensor for aptamer-mediated protein detection based on few-layer graphene immobilization on selectively modified fluorine-doped tin oxide (FTO) substrates. Our results show that the electrochemical properties of graphene-modified FTO samples are suitable for complex biological detection due to the stability and inertness of the engineered electrodic interface. In addition, few-layer immobilization of graphene sheets through electrostatic linkage with an electrochemically grafted FTO surface allows obtaining an optically accessible and highly conductive platform. As a proof of concept, we used insulin as the target molecule to reveal in solution. Because of its transparency and low sampling volume (a few microliters), our sensing unit can be easily integrated in lab-on-a-chip cell culture systems for effectively monitoring subnanomolar concentrations of proteins relevant for biomedical applications.

  18. Doping palladium with tellurium for the highly selective electrocatalytic reduction of aqueous CO2 to CO.

    Science.gov (United States)

    Tao, Hengcong; Sun, Xiaofu; Back, Seoin; Han, Zishan; Zhu, Qinggong; Robertson, Alex W; Ma, Tao; Fan, Qun; Han, Buxing; Jung, Yousung; Sun, Zhenyu

    2018-01-14

    Designing highly selective and energy-efficient electrocatalysts to minimize the competitive hydrogen evolution reaction in the electrochemical reduction of aqueous CO 2 remains a challenge. In this study, we report that doping Pd with a small amount of Te could selectively convert CO 2 to CO with a low overpotential. The PdTe/few-layer graphene (FLG) catalyst with a Pd/Te molar ratio of 1 : 0.05 displayed a maximum CO faradaic efficiency of about 90% at -0.8 V ( vs. a reversible hydrogen electrode, RHE), CO partial current density of 4.4 mA cm -2 , and CO formation turnover frequency of 0.14 s -1 at -1.0 V ( vs. a RHE), which were 3.7-, 4.3-, and 10-fold higher than those of a Pd/FLG catalyst, respectively. Density functional calculations showed that Te adatoms preferentially bind at the terrace sites of Pd, thereby suppressing undesired hydrogen evolution, whereas CO 2 adsorption and activation occurred on the high index sites of Pd to produce CO.

  19. Unusually high dispersion of nitrogen-doped carbon nanotubes in DNA solution.

    Science.gov (United States)

    Kim, Jin Hee; Kataoka, Masakazu; Fujisawa, Kazunori; Tojo, Tomohiro; Muramatsu, Hiroyuki; Vega-Díaz, Sofía M; Tristán-López, F; Hayashi, Takuya; Kim, Yoong Ahm; Endo, Morinobu; Terrones, Mauricio; Dresselhaus, Mildred S

    2011-12-08

    The dispersibility in a DNA solution of bundled multiwalled carbon nanotubes (MWCNTs), having different chemical functional groups on the CNT sidewall, was investigated by optical spectroscopy. We observed that the dispersibility of nitrogen (N)-doped MWCNTs was significantly higher than that of pure MWCNTs and MWCNTs synthesized in the presence of ethanol. This result is supported by the larger amount of adsorbed DNA on N-doped MWCNTs, as well as by the higher binding energy established between nucleobases and the N-doped CNTs. Pure MWCNTs are dispersed in DNA solution via van der Waals and hydrophobic interactions; in contrast, the nitrogenated sites within N-doped MWCNTs provided additional sites for interactions that are important to disperse nanotubes in DNA solutions. © 2011 American Chemical Society

  20. High-power Yb-doped continuous-wave and pulsed fibre lasers

    Indian Academy of Sciences (India)

    2014-01-05

    wave fibre laser; Q-switched fibre laser; nonlinearity; thermal effects; selfpulsing; Yb-doped fibre; nanosecond pulse ... Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013, India ...

  1. Nitrogen and phosphorus co-doped carbon hollow spheres derived from polypyrrole for high-performance supercapacitor electrodes

    Science.gov (United States)

    Lv, Bingjie; Li, Peipei; Liu, Yan; Lin, Shanshan; Gao, Bifen; Lin, Bizhou

    2018-04-01

    Nitrogen and phosphorus co-doped carbon hollow spheres (NPCHSs) have been prepared by a carbonization and subsequent chemical activation route using dehydrated polypyrrole hollow spheres as the precursor and KOH as the activating agent. NPCHSs are interconnected into a unique 3D porous network, which endows the as-prepared carbon to exhibit a large specific surface area of 1155 m2 g-1 and a high specific capacitance of 232 F g-1 at a current density of 1 A g-1. The as-obtained NPCHSs present a high-level heteroatom doping with N, O and P contents of 11.4, 6.7 and 3.5 wt%, respectively. The capacitance of NPCHSs has been retained at 89.1% after 5000 charge-discharge cycles at a relatively high current density of 5 A g-1. Such excellent performance suggests that NPCHSs are attractive electrode candidates for electrical double layer capacitors.

  2. Study of high mobility carriers in Ni-doped CdO films

    Indian Academy of Sciences (India)

    Their d.c. conductivity, carrier concentration and mobility increased compared to undoped CdO film. The largest mobility of 112·6 cm2/V·s was measured for 1–2% Ni-doped CdO film. From optoelectronics point of view, Ni-doped CdO can be used in infrared-transparent-conducting-oxide (NIR–TCO) applications. Keywords.

  3. Ultramicroporous carbon with extremely narrow pore distribution and very high nitrogen doping for efficient methane mixture gases upgrading

    KAUST Repository

    Yao, Kexin

    2017-06-24

    It is notably challenging to fabricate heavily heteroatom-doped porous carbonaceous materials with narrow ultramicropore size distributions for highly effective mixed-gas separation. In this study, new carbon-based materials with narrow ultramicropore size (<7 Å) distributions (>95%) and high N doping contents (>10 at%) are fabricated through the pyrolysis of a perchloro-substituted porous covalent triazine-based framework (ClCTF). In particular, the sample prepared at 650 °C (ClCTF-1-650) possesses the highest ultramicropores content (98%) and large N content (12 at%) and demonstrates a very high CH and CO capacity, as well as a low N uptake under ambient conditions. The extraordinarily high CH/N and CO/N selectivities correlate with both the ideal adsorption solution theory (IAST) method and performed dynamic separation experiments (breakthrough experiments). The results reported in this study far exceed the CH/N and CO/N selectivities of previously reported carbon-based adsorbents including various nitrogen-doped ones. These results are believed to be associated with the unusually high N content, as well as the suitably narrow ultramicropore size distribution. This report introduces a new pathway to design porous absorbents with precisely controlled ultramicropores for gas separation.

  4. Highly active Ni/Y-doped ZrO{sub 2} catalysts for CO{sub 2} methanation

    Energy Technology Data Exchange (ETDEWEB)

    Takano, H., E-mail: takano_hi@hitachizosen.co.jp [Hitachi Zosen Corporation, Kashiwa, 277-8515 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628 (Japan); Kirihata, Y.; Izumiya, K.; Kumagai, N. [Hitachi Zosen Corporation, Kashiwa, 277-8515 (Japan); Habazaki, H., E-mail: habazaki@eng.hokudai.ac.jp [Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, 060-8628 (Japan); Division of Applied Chemistry & Frontier Chemistry Center, Faculty of Engineering, Hokkaido University, Sapporo, 060-8628 (Japan); Hashimoto, K. [Tohoku Institute of Technology, Sendai, 277-8515 (Japan)

    2016-12-01

    Highlights: • The Ni/Y-doped ZrO{sub 2} catalysts show highly catalytic activity for CO{sub 2} methanation. • Bidentate carbonate is a major adsorption spice on the Ni/Y-doped ZrO{sub 2} catalysts. • The oxide support of t-ZrO{sub 2} and/or c-ZrO{sub 2} with oxygen vacancies plays a key role. - Abstract: The catalytic methanation of CO{sub 2} was carried out on Ni catalysts supported on Y-doped ZrO{sub 2} with various Y{sup 3+} concentrations and Ni/(Zr + Y) molar ratio = 1. The catalysts were characterized by X-ray diffraction, scanning transmission electron microscopy, specific surface area, temperature-programmed desorption of CO{sub 2}, and temperature-programmed reaction. In addition, operando diffuse-reflectance infrared Fourier-transform spectroscopy (DRIFT) was used to identify the adsorbed reaction intermediate. Catalysts supported on Y-doped ZrO{sub 2} show higher catalytic activity than the catalyst on Y-free ZrO{sub 2} with a monoclinic ZrO{sub 2} phase. The catalytic activity is also dependent upon the Y{sup 3+} concentration, and the highest activity was obtained for the catalyst with a Y/(Zr + Y) molar ratio of 0.333, which consists mainly of fcc Ni and cubic ZrO{sub 2} phase. Y{sup 3+} doping into ZrO{sub 2} introduces oxygen vacancies, which play an important role in enhancing the catalytic activity. The operando DRIFT study reveals that a CO adsorption intermediate is absent, and bidentate carbonate is an important intermediate for CH{sub 4} formation.

  5. Physical and magnetic properties of highly aluminum doped strontium ferrite nanoparticles prepared by auto-combustion route

    Energy Technology Data Exchange (ETDEWEB)

    Luo, H.; Rai, B.K. [Department of Physics, University of Memphis, Memphis, TN 38152 (United States); Mishra, S.R., E-mail: srmishra@memphis.edu [Department of Physics, University of Memphis, Memphis, TN 38152 (United States); Nguyen, V.V.; Liu, J.P. [Department of Physics, University of Texas, Arlington, TX 76019 (United States)

    2012-08-15

    Highly Al{sup 3+} ion doped nanocrystalline SrFe{sub 12-x}Al{sub x}O{sub 19} (0{<=}x{<=}12), were prepared by the auto-combustion method and heat treated in air at 1100 Degree-Sign C for 12 h. The phase identification of the powders performed using x-ray diffraction show presence of high-purity hexaferrite phase and absence of any secondary phases. With Al{sup 3+} doping, the lattice parameters decrease due to smaller Al{sup 3+} ion replacing Fe{sup 3+} ions. Morphological analysis performed using transmission electron microscope show growth of needle shaped ferrites with high aspect ratio at Al{sup 3+} ion content exceeding x{>=}2. Al{sup 3+} substitution modifies saturation magnetization (M{sub S}) and coercivity (H{sub C}). The room temperature M{sub S} values continuously reduced while H{sub C} value increased to a maximum value of 18,100 Oe at x=4, which is an unprecedented increase ({approx}321%) in the coercivity as compared to pure Sr-Ferrite. However, at higher Al{sup 3+} content x>4, a decline in magnetization and coercivity has been observed. The magnetic results indicate that the best results for applications of this ferrite will be obtained with an iron deficiency in the stoichiometric formulation. - Highlights: Black-Right-Pointing-Pointer The study reports synthesis and characterization of highly aluminum doped SrFe{sub 12-x}Al{sub x}O{sub 19} ferrite. Black-Right-Pointing-Pointer Synthesis of pure phase aluminum doped Sr-Ferrite using autocombustion method is reported. Black-Right-Pointing-Pointer An unprecedented increase in coercivity {approx}321% is observed upon aluminum at x=4 Al doping. Black-Right-Pointing-Pointer The observed magnetic properties of SrFe{sub 12-x}Al{sub x}O{sub 19} are related to changes in anisotropy. Black-Right-Pointing-Pointer And morphology in compound upon aluminum doping.

  6. High temperature surface Brillouin scattering study of mechanical properties of boron-doped epitaxial polysilicon

    Directory of Open Access Journals (Sweden)

    B. A. Mathe

    2017-02-01

    Full Text Available A study of the mechanical properties of a boron-doped epitaxial polysilicon layer deposited on a Si (100 substrate specimen has been carried out by surface Brillouin scattering at high temperatures. This type of specimen is widely used in micro-electro-mechanical systems (MEMS. By accumulating spectra with the Rayleigh mode and the Lamb continuum the isotropic elastic constants C44 and C11 were obtained, from which the values of the bulk, shear and Young’s moduli and Poisson’s ratio for the layer were determined over a range of temperatures from 20 °C to 110 °C. By contrast, an examination of the literature on polycrystalline silicon shows that other methods each provide a limited range of the above properties and thus additional experiments and techniques were needed. The SBS method is applicable to other polycrystalline materials such as silicon carbide, silicon nitride, silicon germanium and amorphous diamond that have also been used for MEMS applications.

  7. PtRu nanoparticles embedded in nitrogen doped carbon with highly stable CO tolerance and durability

    Science.gov (United States)

    Ling, Ying; Yang, Zehui; Yang, Jun; Zhang, Yunfeng; Zhang, Quan; Yu, Xinxin; Cai, Weiwei

    2018-02-01

    As is well known, the lower durability and sluggish methanol oxidation reaction (MOR) of PtRu alloy electrocatalyst blocks the commercialization of direct methanol fuel cells (DMFCs). Here, we design a new PtRu electrocatalyst, with highly stable CO tolerance and durability, in which the PtRu nanoparticles are embedded in nitrogen doped carbon layers derived from carbonization of poly(vinyl pyrrolidone). The newly fabricated electrocatalyst exhibits no loss in electrochemical surface area (ECSA) and MOR activity after potential cycling from 0.6-1.0 V versus reversible hydrogen electrode, while commercial CB/PtRu retains only 50% of its initial ECSA. Meanwhile, due to the same protective layers, the Ru dissolution is decelerated, resulting in stable CO tolerance. Methanol oxidation reaction (MOR) testing indicates that the activity of newly fabricated electrocatalyst is two times higher than that of commercial CB/PtRu, and the fuel cell performance of the embedded PtRu electrocatalyst was comparable to that of commercial CB/PtRu. The embedded PtRu electrocatalyst is applicable in real DMFC operation. This study offers important and useful information for the design and fabrication of durable and CO tolerant electrocatalysts.

  8. High-temperature conversion of methane on a composite gadolinia-doped ceria-gold electrode

    DEFF Research Database (Denmark)

    Marina, O.A.; Mogensen, Mogens Bjerg

    1999-01-01

    Direct electrochemical oxidation of methane was attempted on a gadolinia-doped ceria Ce(0.6)Gd(0.4)O(1.8) (CG4) electrode in a solid oxide fuel cell using a porous gold-CG4 mixture as current collector Gold is relatively inert to methane in contrast to other popular SOFC anode materials......) increased sharply. No carbon deposition was observed on the CG4 electrode after operating at 1000 degrees C during 350 h of total testing time with partial pressures of methane and steam in the range of 0.5-33 and 3-26 kPa, respectively. (C) 1999 Elsevier Science B.V, All rights reserved....... observed at the open-circuit potential and low anodic overpotentials seems to be due to thermal methane cracking in the gas phase and on the alumina surfaces in the cell housing. At high anodic overpotentials, at electrode potentials where oxygen evolution was expected to take place, the formation of CO(2...

  9. Aluminum-Doped Zinc Oxide as Highly Stable Electron Collection Layer for Perovskite Solar Cells.

    Science.gov (United States)

    Zhao, Xingyue; Shen, Heping; Zhang, Ye; Li, Xin; Zhao, Xiaochong; Tai, Meiqian; Li, Jingfeng; Li, Jianbao; Li, Xin; Lin, Hong

    2016-03-01

    Although low-temperature, solution-processed zinc oxide (ZnO) has been widely adopted as the electron collection layer (ECL) in perovskite solar cells (PSCs) because of its simple synthesis and excellent electrical properties such as high charge mobility, the thermal stability of the perovskite films deposited atop ZnO layer remains as a major issue. Herein, we addressed this problem by employing aluminum-doped zinc oxide (AZO) as the ECL and obtained extraordinarily thermally stable perovskite layers. The improvement of the thermal stability was ascribed to diminish of the Lewis acid-base chemical reaction between perovskite and ECL. Notably, the outstanding transmittance and conductivity also render AZO layer as an ideal candidate for transparent conductive electrodes, which enables a simplified cell structure featuring glass/AZO/perovskite/Spiro-OMeTAD/Au. Optimization of the perovskite layer leads to an excellent and repeatable photovoltaic performance, with the champion cell exhibiting an open-circuit voltage (Voc) of 0.94 V, a short-circuit current (Jsc) of 20.2 mA cm(-2), a fill factor (FF) of 0.67, and an overall power conversion efficiency (PCE) of 12.6% under standard 1 sun illumination. It was also revealed by steady-state and time-resolved photoluminescence that the AZO/perovskite interface resulted in less quenching than that between perovskite and hole transport material.

  10. Extracting dielectric fixed charge density on highly doped crystalline-silicon surfaces using photoconductance measurements

    Science.gov (United States)

    To, A.; Hoex, B.

    2017-11-01

    A novel method for the extraction of fixed interface charge, Qf, and the surface recombination parameters, Sn0 and Sp0, from the injection-level dependent effective minority carrier lifetime measurements is presented. Unlike conventional capacitance-voltage measurements, this technique can be applied to highly doped surfaces provided the surface carrier concentration transitions into strong depletion or inversion with increased carrier injection. By simulating the injection level dependent Auger-corrected inverse lifetime curve of symmetrically passivated and diffused samples after sequential annealing and corona charging, it was revealed that Qf, Sn0, and Sp0 have unique signatures. Therefore, these important electronic parameters, in some instances, can independently be resolved. Furthermore, it was shown that this non-linear lifetime behaviour is exhibited on both p-type and n-type diffused inverted surfaces, by demonstrating the approach with phosphorous diffused n+pn+ structures and boron diffused p+np+ structures passivated with aluminium oxide (AlOx) and silicon nitride, respectively (SiNx). The results show that the approximation of a mid-gap Shockley-Read-Hall defect level with equal capture cross sections is able to, in the samples studied in this work, reproduce the observed injection level dependent lifetime behaviour.

  11. High concentration Yb-Er co-doped phosphate glass for optical fiber amplification

    International Nuclear Information System (INIS)

    Boetti, Nadia Giovanna; Scarpignato, Gerardo Cristian; Pugliese, Diego; Milanese, Daniel; Lousteau, Joris; Bastard, Lionel; Broquin, Jean-Emmanuel

    2015-01-01

    We present the fabrication and characterization of two high concentration Yb 3+ -Er 3+ co-doped double clad phosphate glass optical fibers (named A and B for short) manufactured by preform drawing, with the preform being obtained by the rod-in-tube technique. Optical amplification was demonstrated by core pumping 27 mm of fiber A (7/25/70 μm and NA = 0.17 between core and inner cladding) with a laser diode at 976 nm, achieving a 10.7 dB internal gain, i.e., 4.0 dB cm −1 , for small signal input at 1535 nm. Amplification was also demonstrated in a cladding-pumped counter propagating configuration using both fibers A and B (12/48/140 μm and NA = 0.08). A maximum internal gain of 18.5 dB was achieved with 8 cm of fiber B, corresponding to an amplification of 2.3 dB cm −1 , for small signal input at 1535 nm. (paper)

  12. High concentration Yb-Er co-doped phosphate glass for optical fiber amplification

    Science.gov (United States)

    Giovanna Boetti, Nadia; Cristian Scarpignato, Gerardo; Lousteau, Joris; Pugliese, Diego; Bastard, Lionel; Broquin, Jean-Emmanuel; Milanese, Daniel

    2015-06-01

    We present the fabrication and characterization of two high concentration Yb3+-Er3+ co-doped double clad phosphate glass optical fibers (named A and B for short) manufactured by preform drawing, with the preform being obtained by the rod-in-tube technique. Optical amplification was demonstrated by core pumping 27 mm of fiber A (7/25/70 μm and NA = 0.17 between core and inner cladding) with a laser diode at 976 nm, achieving a 10.7 dB internal gain, i.e., 4.0 dB cm-1, for small signal input at 1535 nm. Amplification was also demonstrated in a cladding-pumped counter propagating configuration using both fibers A and B (12/48/140 μm and NA = 0.08). A maximum internal gain of 18.5 dB was achieved with 8 cm of fiber B, corresponding to an amplification of 2.3 dB cm-1, for small signal input at 1535 nm.

  13. An Investigation of Carbon-Doping-Induced Current Collapse in GaN-on-Si High Electron Mobility Transistors

    Directory of Open Access Journals (Sweden)

    An-Jye Tzou

    2016-06-01

    Full Text Available This paper reports the successful fabrication of a GaN-on-Si high electron mobility transistor (HEMT with a 1702 V breakdown voltage (BV and low current collapse. The strain and threading dislocation density were well-controlled by 100 pairs of AlN/GaN superlattice buffer layers. Relative to the carbon-doped GaN spacer layer, we grew the AlGaN back barrier layer at a high temperature, resulting in a low carbon-doping concentration. The high-bandgap AlGaN provided an effective barrier for blocking leakage from the channel to substrate, leading to a BV comparable to the ordinary carbon-doped GaN HEMTs. In addition, the AlGaN back barrier showed a low dispersion of transiently pulsed ID under substrate bias, implying that the buffer traps were effectively suppressed. Therefore, we obtained a low-dynamic on-resistance with this AlGaN back barrier. These two approaches of high BV with low current collapse improved the device performance, yielding a device that is reliable in power device applications.

  14. Biomass-Derived Oxygen and Nitrogen Co-Doped Porous Carbon with Hierarchical Architecture as Sulfur Hosts for High-Performance Lithium/Sulfur Batteries

    OpenAIRE

    Zhao, Yan; Wang, Li; Huang, Lanyan; Maximov, Maxim. Yu.; Jin, Mingliang; Zhang, Yongguang; Wang, Xin; Zhou, Guofu

    2017-01-01

    In this work, a facile strategy to synthesize oxygen and nitrogen co-doped porous carbon (ONPC) is reported by one-step pyrolysis of waste coffee grounds. As-prepared ONPC possesses highly rich micro/mesopores as well as abundant oxygen and nitrogen co-doping, which is applied to sulfur hosts as lithium/sulfur batteries’ appropriate cathodes. In battery testing, the sulfur/oxygen and nitrogen co-doped porous carbon (S/ONPC) composite materials reveal a high initial capacity of 1150 mAh·g−1 as...

  15. Effect of high pressure on the ground state of low doped manganite: a neutron diffraction and transport property study

    International Nuclear Information System (INIS)

    Ghosh, Barnali; Raychaudhuri, A.K.; Siruguri, V.; Chatterji, Tapan; Thomas, Hansen; Mukovskii, Ya.M.

    2013-01-01

    Depending on the doping level x the hole-doped perovskite manganites, like La 1-x Ca x MnO 3 exhibit a wide variety of physical properties. These compounds lead their high sensitivity to thermodynamic variables like temperature, magnetic field and pressure. The structure can be modified by application of high pressure and it can be quantitative that changes the Mn-O bond length and increases the Mn-O-Mn bond angle. In some cases the pressure can bring about qualitative changes in the structure like change in the lattice structure or its symmetry. These structural factors can contribute to the effective electron transfer integral between Mn ions, which in turn can change the magnetic exchanges like the double-exchange as well as the super exchange. For low hole doping (0.15 ≤ x ≤ 0.2), the low temperature ground state is Ferromagnetic insulator (FMI). The ground state of the low doped manganite La 0.79 Ca 0.21 MnO 3 (LCMO) can be destabilized by external hydrostatic pressure. We have done electrical transport measurement under magnetic field and under high pressure for understanding the nature of the resulting phase(s) that arise from the applied hydrostatic pressure. We find that the metallic phase so created under pressure has no appreciable magnetoresistance (MR). The Neutron powder diffraction measurement done on D20 diffractometer (λ=1.3Å) at ILL, Grenoble, France under high hydrostatic pressure up to 10GPa shows that the pressure leads to a change in the crystal structure from orthorhombic to rhombohedral and leading to a change in magnetic structure also; and most importantly collapse of the magnetic moment to a low value that leads to absence of any MR under pressure induced metallization. (author)

  16. Advanced Sulfur Cathode Enabled by Highly Crumpled Nitrogen-Doped Graphene Sheets for High-Energy-Density Lithium-Sulfur Batteries.

    Science.gov (United States)

    Song, Jiangxuan; Yu, Zhaoxin; Gordin, Mikhail L; Wang, Donghai

    2016-02-10

    Herein, we report a synthesis of highly crumpled nitrogen-doped graphene sheets with ultrahigh pore volume (5.4 cm(3)/g) via a simple thermally induced expansion strategy in absence of any templates. The wrinkled graphene sheets are interwoven rather than stacked, enabling rich nitrogen-containing active sites. Benefiting from the unique pore structure and nitrogen-doping induced strong polysulfide adsorption ability, lithium-sulfur battery cells using these wrinkled graphene sheets as both sulfur host and interlayer achieved a high capacity of ∼1000 mAh/g and exceptional cycling stability even at high sulfur content (≥80 wt %) and sulfur loading (5 mg sulfur/cm(2)). The high specific capacity together with the high sulfur loading push the areal capacity of sulfur cathodes to ∼5 mAh/cm(2), which is outstanding compared to other recently developed sulfur cathodes and ideal for practical applications.

  17. Controllable electrical properties of metal-doped In2O3 nanowires for high-performance enhancement-mode transistors.

    Science.gov (United States)

    Zou, Xuming; Liu, Xingqiang; Wang, Chunlan; Jiang, Ying; Wang, Yong; Xiao, Xiangheng; Ho, Johnny C; Li, Jinchai; Jiang, Changzhong; Xiong, Qihua; Liao, Lei

    2013-01-22

    In recent years, In(2)O(3) nanowires (NWs) have been widely explored in many technological areas due to their excellent electrical and optical properties; however, most of these devices are based on In(2)O(3) NW field-effect transistors (FETs) operating in the depletion mode, which induces relatively higher power consumption and fancier circuit integration design. Here, n-type enhancement-mode In(2)O(3) NW FETs are successfully fabricated by doping different metal elements (Mg, Al, and Ga) in the NW channels. Importantly, the resulting threshold voltage can be effectively modulated through varying the metal (Mg, Ga, and Al) content in the NWs. A series of scaling effects in the mobility, transconductance, threshold voltage, and source-drain current with respect to the device channel length are also observed. Specifically, a small gate delay time (0.01 ns) and high on-current density (0.9 mA/μm) are obtained at 300 nm channel length. Furthermore, Mg-doped In(2)O(3) NWs are then employed to fabricate NW parallel array FETs with a high saturation current (0.5 mA), on/off ratio (>10(9)), and field-effect mobility (110 cm(2)/V·s), while the subthreshold slope and threshold voltage do not show any significant changes. All of these results indicate the great potency for metal-doped In(2)O(3) NWs used in the low-power, high-performance thin-film transistors.

  18. Highly photostable NV centre ensembles in CVD diamond produced by using N2O as the doping gas

    Science.gov (United States)

    Tallaire, A.; Mayer, L.; Brinza, O.; Pinault-Thaury, M. A.; Debuisschert, T.; Achard, J.

    2017-10-01

    High density Nitrogen-Vacancy (NV) centre ensembles incorporated in plasma assisted chemical vapour deposition (CVD) diamond are crucial to the development of more efficient sensing devices that use the properties of luminescent defects. Achieving high NV doping with N2 as the dopant gas source during diamond growth is, however, plagued by the formation of macroscopic and point defects that quench luminescence. Moreover, such NVs are found to exhibit poor photostability under high laser powers. Although this effect can be harnessed to locally and durably switch off NV luminescence for data storage, it is usually undesirable for most applications. In this work, the use of N2O as an alternative doping source is proposed. Much higher amounts of the doping gas can be added without significantly generating defects, which allows the incorporation of perfectly photostable and higher density NV ensembles. This effect is believed to be related to the lower dissociation energy of the N2O molecule together with the beneficial effect of the presence of a low and controlled amount of oxygen near the growing surface.

  19. Highly efficient and heavily-doped organic light-emitting devices based on an orange phosphorescent iridium complex

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shunliang; Wang, Qi [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Li, Ming [College of Chemistry, Sichuan University, Chengdu, 610064 (China); Lu, Zhiyun, E-mail: luzhiyun@scu.edu.cn [College of Chemistry, Sichuan University, Chengdu, 610064 (China); Yu, Junsheng, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2014-10-15

    Heavily doped and highly efficient phosphorescent organic light-emitting devices (PhOLEDs) had been fabricated by utilizing an orange iridium complex, bis[2-(3′,5′-di-tert-butylbiphenyl-4-yl)benzothiazolato-N,C{sup 2'}]iridium(III) (acetylacetonate) [(tbpbt){sub 2}Ir(acac)], as a phosphor. When the doping concentration of [(tbpbt){sub 2}Ir(acac)] reached as high as 15 wt%, the PhOLEDs exhibited a power efficiency, current efficiency, and external quantum efficiency of 24.5 lm/W, 32.1 cd/A, 15.7%, respectively, implying a promising quenching-resistant characteristics of this novel phosphor. Furthermore, the efficient white PhOLEDs had been obtained by employing (tbpbt){sub 2}Ir(acac) as a self-host orange emitter, indicating that (tbpbt){sub 2}Ir(acac) could serve as a promising phosphor to fabricate white organic light-emitting devices with simplified manufacturing process. - Highlights: • Efficient phosphorescent devices were fabricated. • Optimized phosphor doping ratio reached as high as 15 wt%. • The results proved a promising quench-resistant property of the phosphor. • Efficient white devices based on this phosphor as self-host layer had been realized.

  20. L-lactic acid and sodium p-toluenesulfonate co-doped polypyrrole for high performance cathode in sodium ion battery

    Science.gov (United States)

    Liao, Qishu; Hou, Hongying; Liu, Xianxi; Yao, Yuan; Dai, Zhipeng; Yu, Chengyi; Li, Dongdong

    2018-04-01

    In this work, polypyrrole (PPy) was co-doped with L-lactic acid (LA) and sodium p-toluenesulfonate (TsONa) for high performance cathode in sodium ion battery (SIB) via facile one-step electropolymerization on Fe foil. The as-synthesized LA/TsONa co-doped PPy cathode was investigated in terms of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), galvanostatic charge/discharge and cyclic voltammetry (CV). The results suggested that some oval-bud-like LA/TsONa co-doped PPy particles did form and tightly combine with the surface of Fe foil; furthermore, LA/TsONa co-doped PPy cathode also delivered higher electrochemical performances than TsONa mono-doped PPy cathode. For example, the initial specific discharge capacity was as high as about 124 mAh/g, and the reversible specific capacity still maintained at about 110 mAh/g even after 50 cycles, higher than those of TsONa mono-doped PPy cathode. The synergy effect of multi components of LA/TsONa co-doped PPy cathode should be responsible for high electrochemical performances.

  1. High gain and double phase conjugation with strongly doped CO:BaTiO 3 in reflection grating configurations

    Science.gov (United States)

    Glick, Yaakov; Sternklar, Shmuel

    1997-02-01

    A study of highly doped photorefractive Co:BaTiO 3 reveals its usefulness for wave mixing through reflection grating interactions. Gain and noise figures are characterized for a counter-propagating pump-signal amplifier. Gain as high as 3 × 10 7, extraction efficiency as high as 40% and noise equivalent power as low as 0.15 pW were demonstrated. To the best of our knowledge this is the highest photorefractive gain reported to date. In addition the double phase conjugate mirror (DPCM) is operated in a reflection grating geometry. High absorption limits the DPCM reflectivity to about 1%.

  2. Feasibility study on silicon doping using high temperature test engineering reactor

    International Nuclear Information System (INIS)

    Seki, Masaya; Takaki, Naoyuki; Goto, Minoru; Shimakawa, Satoshi

    2011-01-01

    The feasibility study on silicon doping using the High Temperature engineering Test Reactor (HTTR) is performed by numerical simulations. The HTTR is a High Temperature Gas-cooled Reactor (HTGR) situated at JAEA Oarai research and development center. It has a 30MW thermal power and the outlet coolant temperature is 950degC. The objective of this study is to evaluate the following issues, 1. The impact of loading Si-ingots into the core on the criticality, 2. The uniformity of the neutron capture reaction rate in Si-ingots, and 3. The production rate of silicon semiconductor. In this study, six Si-ingots are loaded into the irradiation area which is located in the peripheral region of the core. They are irradiated with rotation movement around the axial direction to obtain uniform neutron capture reaction rate in the radial direction. Additionally, the neutron filter, which is made of graphite containing boron, is used to obtain uniform neutron capture reaction rate in the axial direction. The evaluations were conducted by performing the HTTR whole core calculations with the Monte Carlo code MVP-2.0. In the calculations, several tally regions were defined on the Si-ingots to investigate the uniformity of the neutron capture reaction rate. As a result, loading the Si-ingots into the core causes negative reactivity by about 0.7%dk/k. Uniform neutron capture reaction rate of Si-ingot is obtained 98% in the radial and the axial direction. In case of the target of semiconductor resistivity is set to 50 Ωcm, the required irradiation time becomes 10 hours. The HTTR is able to produce silicon semiconductor of 540kg in one-time irradiation. This study was conducted as a joint research with JAEA, Nuclear Fuel Industries, LTD, Toyota Tsusho Corporation and Tokai University. (author)

  3. Highly optimized tunable Er3+-doped single longitudinal mode fiber ring laser, experiment and model

    DEFF Research Database (Denmark)

    Poulsen, Christian; Sejka, Milan

    1993-01-01

    A continuous wave (CW) tunable diode-pumped Er3+-doped fiber ring laser, pumped by diode laser at wavelengths around 1480 nm, is discussed. Wavelength tuning range of 42 nm, maximum slope efficiency of 48% and output power of 14.4 mW have been achieved. Single longitudinal mode lasing with a line...... with a linewidth of 6 kHz has been measured. A fast model of erbium-doped fiber laser was developed and used to optimize output parameters of the laser......A continuous wave (CW) tunable diode-pumped Er3+-doped fiber ring laser, pumped by diode laser at wavelengths around 1480 nm, is discussed. Wavelength tuning range of 42 nm, maximum slope efficiency of 48% and output power of 14.4 mW have been achieved. Single longitudinal mode lasing...

  4. Doping phosphoric acid in polybenzimidazole membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Jensen, Jens Oluf

    2007-01-01

    Polybenzimidazole (PBI) membranes were doped in phosphoric acid solutions of different concentrations at room temperature. The doping chemistry was studied using the Scatchard method. The energy distribution of the acid complexation in polymer membranes is heterogeneous, that is, there are two...... different types of sites in PBI for the acid doping. The protonation constants of PBI by phosphoric acid are found to be 12.7 L mol(-1) (K-1) for acid complexing sites with higher affinity, and 0.19 L mol(-1) (K-2) for the sites with lower affinity. The dissociation constants for the complexing acid onto...... these two types of PBI sites are found to be 5.4 X 10(-4) and 3.6 X 10(-2), respectively, that is, about 10 times smaller than that of aqueous phosphoric acid in the first case but 5 times higher in the second. The proton conducting mechanism is also discussed....

  5. The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films

    KAUST Repository

    Venkatesh, S.

    2016-03-24

    We studied the nature of magnetic ordering in Mn-doped ZnO thin films that exhibited ferromagnetism at 300 K and superparamagnetism at 5 K. We directly inter-related the magnetisation and magnetoresistance by invoking the polaronpercolation theory and variable range of hopping conduction below the metal-to-insulator transition. By obtaining a qualitative agreement between these two models, we attribute the ferromagnetism to the s-d exchange-induced spin splitting that was indicated by large positive magnetoresistance (∼40 %). Low temperature superparamagnetism was attributed to the localization of carriers and non-interacting polaron clusters. This analysis can assist in understanding the presence or absence of ferromagnetism in doped/un-doped ZnO.

  6. Nitrogen-doped Carbon Derived from ZIF-8 as a High-performance Metal-free Catalyst for Acetylene Hydrochlorination

    Science.gov (United States)

    Chao, Songlin; Zou, Fang; Wan, Fanfan; Dong, Xiaobin; Wang, Yanlin; Wang, Yuxuan; Guan, Qingxin; Wang, Guichang; Li, Wei

    2017-01-01

    Acetylene hydrochlorination is a major industrial technology for manufacturing vinyl chloride monomer in regions with abundant coal resources; however, it is plagued by the use of mercury(II) chloride catalyst. The development of a nonmercury catalyst has been extensively explored. Herein, we report a N-doped carbon catalyst derived from ZIF-8 with both high activity and quite good stability. The acetylene conversion reached 92% and decreased slightly during a 200 h test at 220 °C and atmospheric pressure. Experimental studies and theoretical calculations indicate that C atoms adjacent to the pyridinic N are the active sites, and coke deposition covering pyridinic N is the main reason for catalyst deactivation. The performance of those N-doped carbons makes it possible for practical applications with further effort. Furthermore, the result also provides guidance for designing metal-free catalysts for similar reactions.

  7. MoP Nanoparticles Supported on Indium-Doped Porous Carbon: Outstanding Catalysts for Highly Efficient CO2 Electroreduction.

    Science.gov (United States)

    Sun, Xiaofu; Lu, Lu; Zhu, Qinggong; Wu, Congyi; Yang, Dexin; Chen, Chunjun; Han, Buxing

    2018-02-23

    Electrochemical reduction of CO 2 into value-added product is an interesting area. MoP nanoparticles supported on porous carbon were synthesized using metal-organic frameworks as the carbon precursor, and initial work on CO 2 electroreduction using the MoP-based catalyst were carried out. It was discovered that MoP nanoparticles supported on In-doped porous carbon had outstanding performance for CO 2 reduction to formic acid. The Faradaic efficiency and current density could reach 96.5 % and 43.8 mA cm -2 , respectively, when using ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate as the supporting electrolyte. The current density is higher than those reported up to date with very high Faradaic efficiency. The MoP nanoparticles and the doped In 2 O 3 cooperated very well in catalyzing the CO 2 electroreduction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Resistivity Effects of Cation Ordering in Highly-Doped La2-xSrxCu4 Epitaxial Thin Films

    Science.gov (United States)

    Burquest, Franklin; Marmol, Rodrigo; Cox, Nicholas; Nelson-Cheeseman, Brittany

    Highly-doped La2-xSrxCuO4 (LSCO) films (0.5 causes internal polar electrostatic forces, which have been shown to cause stretching of the apical oxygen bond in analogous epitaxial nickelate films. Thin film samples are grown concurrently to minimize extraneous effects on film structure and properties. Atomic force microscopy and x-ray reflectivity demonstrate that the films are single crystalline, epitaxial, and smooth. X-ray diffraction is used to measure the c-axis of the films as a function of doping and dopant cation ordering. Electrical transport data of the ordered samples is compared with transport data of conventional disordered cation samples. Preliminary data indicates significant differences in resistivity at both 300K and 10K between the cation-ordered and cation-disordered samples. This work indicates that dopant cation ordering within the layered cuprates could significantly modify the conduction mechanisms at play in these materials.

  9. Spectrophotometric Analysis of Phosphoric Acid Leakage in High-Temperature Phosphoric Acid-Doped Polybenzimidazole Membrane Fuel Cell Application

    Directory of Open Access Journals (Sweden)

    Seungyoon Han

    2016-01-01

    Full Text Available High-temperature proton exchange membrane fuel cells (HT-PEMFCs utilize a phosphoric acid- (PA- doped polybenzimidazole (PBI membrane as a polymer electrolyte. The PA concentration in the membrane can affect fuel cell performance, as a significant amount of PA can leak from the membrane electrode assembly (MEA by dissolution in discharged water, which is a byproduct of cell operation. Spectrophotometric analysis of PA leakage in PA-doped polybenzimidazole membrane fuel cells is described here. This spectrophotometric analysis is based on measurement of absorption of an ion pair formed by phosphomolybdic anions and the cationoid color reagent. Different color reagents were tested based on PA detection sensitivity, stability of the formed color, and accuracy with respect to the amount of PA measured. This method allows for nondestructive analysis and monitoring of PA leakage during HT-PEMFCs operation.

  10. Highly sensitive ethanol chemical sensor based on Ni-doped SnO₂ nanostructure materials.

    Science.gov (United States)

    Rahman, Mohammed M; Jamal, Aslam; Khan, Sher Bahadar; Faisal, M

    2011-10-15

    Due to potential applications of semiconductor transition doped nanostructure materials and the important advantages of synthesis in cost-effective and environmental concerns, a significant effort has been consummated for improvement of Ni-doped SnO(2) nanomaterials using hydrothermal technique at room conditions. The structural and optical properties of the low-dimensional (average diameter, 52.4 nm) Ni-doped SnO(2) nanostructures were demonstrated using various conventional techniques such as UV/visible spectroscopy, FT-IR spectroscopy, X-ray powder diffraction (XRD), and Field-emission scanning electron microscopy (FE-SEM). The calcined doped material is an attractive semiconductor nanoparticle for accomplishment in chemical sensing by simple I-V technique, where toxic chemical (ethanol) is used as a target chemical. Thin-film of Ni-doped SnO(2) nanostructure materials with conducting coating agents on silver electrodes (AgE, surface area, 0.0216 cm(2)) revealed higher sensitivity and repeatability. The calibration plot is linear (R, 0.8440) over the large dynamic range (1.0 nM-1.0 mM), where the sensitivity is approximately 2.3148 μA cm(-2) mM(-1) with a detection limit of 0.6 nM, based on signal/noise ratio in short response time. Consequently on the basis of the sensitive communication among structures, morphologies, and properties, it is exemplified that the morphologies and the optical characteristics can be extended to a large scale in doping nanomaterials and proficient chemical sensors applications. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Aqueous synthesis of highly luminescent glutathione-capped Mn²⁺-doped ZnS quantum dots.

    Science.gov (United States)

    Kolmykov, Oleksii; Coulon, Joël; Lalevée, Jacques; Alem, Halima; Medjahdi, Ghouti; Schneider, Raphaël

    2014-11-01

    In this paper, an aqueous-based route has been developed to prepare highly luminescent glutathione (GSH)-capped Mn-doped ZnS quantum dots (QDs). The dots obtained have an average diameter of 4.3 nm and exhibit the Mn(2+)-related orange luminescence with very low surface defect density. The highest photoluminescence was observed for a Mn(2+) to Zn(2+) molar ratio of 3%. Consecutive overcoating of the Mn:ZnS@GSH QDs by a ZnS shell was done, and the core/shell structured QDs exhibit a PL quantum yield of 23%. Transmission electron microscopy, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy, UV-visible spectroscopy and spectrofluorometry have been used to characterize the crystal structure, the doping status, and the optical properties of the doped-QDs. Our systematic investigation shows that Mn:ZnS/ZnS@GSH QDs are highly promising fluorescent labels in biological applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Microwave-Hydrothermal Synthesis and Characterization of High-Purity Nb Doped BaTiO3 Nanocrystals

    Directory of Open Access Journals (Sweden)

    A. Khanfekr

    2014-01-01

    Full Text Available The synthesis of Nb doped BaTiO3 has been investigated under Microwave-Hydrothermal (MH conditions in the temperature of 150°C for only 2 h using C16H36O4Ti, BaH2O2.8H2O and NbCl5 as Ba, Ti and  Nb sources, respectively.  Typical experiments performed on MH processing have not yet reported for Nb doped BaTiO3.  In the MH process, the formation of high purity nano tetragonal Nb-BaTiO3 was strongly enhanced. New hydrothermal method was used instead of the previous solid state reaction for the BaTiO3±Nb2O3 system. The new method uses high pressure to create nano dimension particles in a lower time and temperature. In case of the phase evolution studies, the XRD pattern measurements and Raman spectroscopy were performed. TEM and FE-SEM images were taken for the detailed analysis of the particle size, surface and morphology.  Synthesis of Nb doped BaTiO3 with the Microwave-hydrothermal provides an advantage of fast crystallization and reduced crystal size when compared to existing methods.

  13. Infrared response of the lateral PIN structure of a highly titanium-doped silicon-on-insulator material

    International Nuclear Information System (INIS)

    Ma Zhi-Hua; Cao Quan; Zuo Yu-Hua; Zheng Jun; Xue Chun-Lai; Cheng Bu-Wen; Wang Qi-Ming

    2011-01-01

    The intermediate band (IB) solar cell is a promising third-generation solar cell that could possibly achieve very high efficiency above the Shockley—Queisser limit. One of the promising ways to synthesize IB material is to introduce heavily doped deep level impurities in conventional semiconductors. High-doped Ti with a concentration of 10 20 cm −3 –10 21 cm −3 in the p-type top Si layer of silicon-on-insulator (SOI) substrate is obtained by ion implantation and rapid thermal annealing (RTA). Secondary ion mass spectrometry measurements confirm that the Ti concentration exceeds the theoretical Mott limit, the main requirement for the formation of an impurity intermediate band. Increased absorption is observed in the infrared (IR) region by Fourier transform infrared spectroscopy (FTIR) technology. By using a lateral p-i-n structure, an obvious infrared response in a range of 1100 nm–2000 nm is achieved in a heavily Ti-doped SOI substrate, suggesting that the improvement on IR photoresponse is a result of increased absorption in the IR. The experimental results indicate that heavily Ti-implanted Si can be used as a potential kind of intermediate-band photovoltaic material to utilize the infrared photons of the solar spectrum. (condensed matter: structural, mechanical, and thermal properties)

  14. Surface damages of polycrystalline W and La2O3-doped W induced by high-flux He plasma irradiation

    Science.gov (United States)

    Liu, Lu; Li, Shouzhe; Liu, Dongping; Benstetter, Günther; Zhang, Yang; Hong, Yi; Fan, Hongyu; Ni, Weiyuan; Yang, Qi; Wu, Yunfeng; Bi, Zhenhua

    2018-04-01

    In this study, polycrystalline tungsten (W) and three oxide dispersed strengthened W with 0.1 vol %, 1.0 vol % and 5.0 vol % lanthanum trioxide (La2O3) were irradiated with low-energy (200 eV) and high-flux (5.8 × 1021 or 1.4 × 1022 ions/m2ṡs) He+ ions at elevated temperature. After He+ irradiation at a fluence of 3.0 × 1025/m2, their surface damages were observed by scanning electron microscopy, energy dispersive spectroscopy, scanning electron microscopy-electron backscatter diffraction, and conductive atomic force microscopy. Micron-sized holes were formed on the surface of W alloys after He+ irradiation at 1100 K. Analysis shows that the La2O3 grains doped in W were sputtered preferentially by the high-flux He+ ions when compared with the W grains. For irradiation at 1550 K, W nano-fuzz was formed at the surfaces of both polycrystalline W and La2O3-doped W. The thickness of the fuzz layers formed at the surface of La2O3-doped W is 40% lower than the one of polycrystalline W. The presence of La2O3 could suppress the diffusion and coalescence of He atoms inside W, which plays an important role in the growth of nanostructures fuzz.

  15. Graphene quantum dots with nitrogen-doped content dependence for highly efficient dual-modality photodynamic antimicrobial therapy and bioimaging.

    Science.gov (United States)

    Kuo, Wen-Shuo; Chen, Hua-Han; Chen, Shih-Yao; Chang, Chia-Yuan; Chen, Pei-Chi; Hou, Yung-I; Shao, Yu-Ting; Kao, Hui-Fang; Lilian Hsu, Chih-Li; Chen, Yi-Chun; Chen, Shean-Jen; Wu, Shang-Rung; Wang, Jiu-Yao

    2017-03-01

    Reactive oxygen species is the main contributor to photodynamic therapy. The results of this study show that a nitrogen-doped graphene quantum dot, serving as a photosensitizer, was capable of generating a higher amount of reactive oxygen species than a nitrogen-free graphene quantum dot in photodynamic therapy when photoexcited for only 3 min of 670 nm laser exposure (0.1 W cm -2 ), indicating highly improved antimicrobial effects. In addition, we found that higher nitrogen-bonding compositions of graphene quantum dots more efficiently performed photodynamic therapy actions than did the lower compositions that underwent identical treatments. Furthermore, the intrinsically emitted luminescence from nitrogen-doped graphene quantum dots and high photostability simultaneously enabled it to act as a promising contrast probe for tracking and localizing bacteria in biomedical imaging. Thus, the dual modality of nitrogen-doped graphene quantum dots presents possibilities for future clinical applications, and in particular multidrug resistant bacteria. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Cellulose-derived nitrogen and phosphorus dual-doped carbon as high performance oxygen reduction catalyst in microbial fuel cell

    Science.gov (United States)

    Liu, Qin; Zhou, Yan; Chen, Shuiliang; Wang, Zejie; Hou, Haoqing; Zhao, Feng

    2015-01-01

    Microbial fuel cells (MFCs) couple functions of waste removal and electricity generation. The future success of MFCs inevitably depends on the increase of performance at decrease of material cost. Therefore, the use of renewable and sustainable materials, e.g. cellulose, to prepare high performance materials for MFCs would be an inevitable trend. In this communication, nitrogen and phosphorus dual-doped carbons were prepared by pyrolysis of cellulose using ammonium phosphate as doping source and employed as oxygen reduction reaction (ORR) catalyst in air-cathode of MFCs. A maximum power density of 2293 ± 50 mW m-2 was generated by the air-cathode using the dual-doped carbon catalyst, which was higher than the air-cathode using Pt/C catalyst with Pt load of 0.5 mg cm-2 (1680 ± 32 mW m-2). This study provided a facile and sustainable way to prepare low-cost and high-efficient ORR catalyst for scaled-up MFC applications.

  17. Microstructural parameters and high third order nonlinear absorption characteristics of Mn-doped PbS/PVA nanocomposite films

    Science.gov (United States)

    Ramezanpour, B.; Mahmoudi Chenari, Hossein; Sadigh, M. Khadem

    2017-11-01

    In this work, undoped and Mn-doped PbS/PVA nanocomposite films have been successfully fabricated using the simple solution-casting method. Their crystalline structure was examined by X-ray powder diffraction (XRD). XRD pattern show the formation of cubic structure of PbS for Mn-doped PbS in PVA matrix. Microstructure parameters of Mn-doped PbS/PVA nanocomposite films were obtained through the size-strain plot (SSP) method. The thermal stability of the nanocomposite film was determined using Thermogravimetric analysis (TGA). Furthermore, Z-scan technique was used to investigate the optical nonlinearity of nanocomposite films by a continuous-wave laser irradiation at the wavelength of 655 nm. This experimental results show that undoped PbS/PVA nanocomposite films indicate high nonlinear absorption characteristics. Moreover, the nanocomposite films with easy preparation characteristics, high thermal stability and nonlinear absorption properties can be used as an active element in optics and photonic devices.

  18. Combined host–guest doping and host-free systems for high-efficiency white organic light-emitting devices

    International Nuclear Information System (INIS)

    Zhao Juan; Yu Junsheng; Liu Shengqiang; Jiang Yadong

    2012-01-01

    Highly efficient white organic light-emitting devices (WOLEDs) with a four-layer structure were realized by utilizing phosphorescent blue and yellow emitters. The key concept of device construction is to combine host–guest doping system of the blue emitting layer (EML) and the host-free system of yellow EML. Two kinds of WOLEDs incorporated with distinct host materials, namely N,N'-dicarbazolyl-3,5-benzene (mCP) and p-bis(triphenylsilyly)benzene (UGH2), were fabricated. Without using light out-coupling technology, a maximum current efficiency (η C ) of 58.8 cd/A and a maximum external quantum efficiency (η EQE ) of 18.77% were obtained for the mCP-based WOLED; while a maximum η C of 65.3 cd/A and a maximum η EQE of 19.04% were achieved for the UGH2-based WOLED. Meanwhile, both WOLEDs presented higher performance than that of conventionally full-doping WOLEDs. Furthermore, systematic studies of the high-efficiency WOLEDs were progressed. - Highlights: ► Efficient WOLEDs by combining two systems. ► Host–guest doping system for blue emitting layer. ► Host-free system for yellow emitting layer. ► Maximum current efficiency of 65.3 cd/A and external quantum efficiency of 19.04%.

  19. Magnetic and transport properties of Sb2Te3 doped with high concentration of Cr

    Science.gov (United States)

    Gupta, Sachin; Kanai, Shun; Matsukura, Fumihiro; Ohno, Hideo

    2017-10-01

    We report on the molecular beam epitaxy and properties of a magnetic topological insulator (TI): Cr-doped Sb2Te3. Composition analysis reveals that Cr replaces Sb, and X-ray diffraction confirms that a single-phase textured crystal structure can be obtained for (Cr x Sb1- x )2Te3 with x up to 0.44. A further increase in x results in phase separation or precipitates in the material. The Curie temperature T C increases with x up to 0.44 and reaches 250 K, which is the highest T C observed thus far in magnetically doped TIs.

  20. Conductive Boron-Doped Graphene as an Ideal Material for Electrocatalytically Switchable and High-Capacity Hydrogen Storage.

    Science.gov (United States)

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

    2016-12-07

    Electrocatalytic, switchable hydrogen storage promises both tunable kinetics and facile reversibility without the need for specific catalysts. The feasibility of this approach relies on having materials that are easy to synthesize, possessing good electrical conductivities. Graphitic carbon nitride (g-C 4 N 3 ) has been predicted to display charge-responsive binding with molecular hydrogen-the only such conductive sorbent material that has been discovered to date. As yet, however, this conductive variant of graphitic carbon nitride is not readily synthesized by scalable methods. Here, we examine the possibility of conductive and easily synthesized boron-doped graphene nanosheets (B-doped graphene) as sorbent materials for practical applications of electrocatalytically switchable hydrogen storage. Using first-principle calculations, we find that the adsorption energy of H 2 molecules on B-doped graphene can be dramatically enhanced by removing electrons from and thereby positively charging the adsorbent. Thus, by controlling charge injected or depleted from the adsorbent, one can effectively tune the storage/release processes which occur spontaneously without any energy barriers. At full hydrogen coverage, the positively charged BC 5 achieves high storage capacities up to 5.3 wt %. Importantly, B-doped graphene, such as BC 49 , BC 7 , and BC 5 , have good electrical conductivity and can be easily synthesized by scalable methods, which positions this class of material as a very good candidate for charge injection/release. These predictions pave the route for practical implementation of electrocatalytic systems with switchable storage/release capacities that offer high capacity for hydrogen storage.

  1. Research and Development of High Energy 2 - Micron Lasers Based on TM: Doped Ceramic Laser Gain Media and TM: Doped Optical Fibers

    Science.gov (United States)

    2016-07-20

    OPTICAL FIBERS Robert Byer LELAND STANFORD JUNIOR UNIV CA 450 SERRA MALL STANFORD, CA 94305-2004 07/20/2016 Final Report DISTRIBUTION A: Distribution...TM: DOPED OPTICAL FIBERS 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-10-1-0560 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Robert L. Byer (PI...LASERS BASED ON TM: DOPED CERAMIC LASER GAIN MEDIA AND TM: DOPED OPTICAL FIBERS AFOSR FA9550-10-1-0560 PI - Robert L. Byer Ginzton Laboratory

  2. Strong doping of the n-optical confinement layer for increasing output power of high- power pulsed laser diodes in the eye safe wavelength range

    Science.gov (United States)

    Ryvkin, Boris S.; Avrutin, Eugene A.; Kostamovaara, Juha T.

    2017-12-01

    An analytical model for internal optical losses at high power in a 1.5 μm laser diode with strong n-doping in the n-side of the optical confinement layer is created. The model includes intervalence band absorption by holes supplied by both current flow and two-photon absorption (TPA), as well as the direct TPA effect. The resulting losses are compared with those in an identical structure with a weakly doped waveguide, and shown to be substantially lower, resulting in a significant improvement in the output power and efficiency in the structure with a strongly doped waveguide.

  3. Erosion of pyrolytic graphite and Ti-doped graphite due to high flux irradiation

    International Nuclear Information System (INIS)

    Ohtsuka, Yusuke; Ohashi, Junpei; Ueda, Yoshio; Isobe, Michiro; Nishikawa, Masahiro

    1997-01-01

    The erosion of pyrolytic graphite and titanium doped graphite RG-Ti above 1,780 K was investigated by 5 keV Ar beam irradiation with the flux from 4x10 19 to 1x10 21 m -2 ·s -1 . The total erosion yields were significantly reduced with the flux. This reduction would be attributed to the reduction of RES (radiation enhanced sublimation) yield, which was observed in the case of isotropic graphite with the flux dependence of RES yield of φ -0.26 (φ: flux) obtained in our previous work. The yield of pyrolytic graphite was roughly 30% higher than that of isotropic graphite below the flux of 10 20 m -2 ·s -1 whereas each yield approached to very close value at the highest flux of 1x10 21 m -2 ·s -1 . This result indicated that the effect of graphite structure on the RES yield, which was apparent in the low flux region, would disappear in the high flux region probably due to the disordering of crystal structure. In the case of irradiation to RG-Ti at 1,780 K, the surface undulations evolved with a mean height of about 3 μm at 1.2x10 20 m -2 ·s -1 , while at higher flux of 8.0x10 20 m -2 ·s -1 they were unrecognizable. These phenomena can be explained by the reduction of RES of graphite parts excluding TiC grains. (author)

  4. Highly active and durable Ca-doped Ce-SBA-15 catalyst for biodiesel production

    International Nuclear Information System (INIS)

    Thitsartarn, Warintorn; Maneerung, Thawatchai; Kawi, Sibudjing

    2015-01-01

    In this work, Ca-doped Ce-incorporated SBA-15 (Ca/CeS) catalyst was successfully synthesized by using direct synthesis of Ce-incorporated SBA-15 followed by impregnation of CaO (calcium oxide). The maximum Si/Ce molar ratio that Ce atoms can be incorporated successfully into the mesoporous framework was found to be 5 (CeS-5). After the impregnation of 30 wt. % Ca, the obtained 30Ca/CeS-5 catalysts showed the superior catalytic performance for transesterification reaction of palm oil with methanol and also the higher catalytic activity as compared to other supported catalysts, i.e. CaO/CeO 2 and CaO–CeO 2 /SBA-15. This can be attributed to the well-dispersion of CaO on the CeS-5 support surface. Furthermore, it was found that the leaching of Si, Ce and Ca from the catalyst into biodiesel produced was negligible (i.e. <1 ppm after 7 cycles), indicating the strong interaction between CaO and CeS-5 support. As a result, the 30Ca/CeS-5 catalyst can be reused at least 15 cycles with insignificant decrease in catalytic activity, offering the efficient CaO-based catalyst for biodiesel production. - Highlights: • Mesoporous Ca-based catalyst was successfully developed for biodiesel production. • Catalyst exhibited high activity towards transesterification (FAME yield > 98%). • Catalyst can be effectively re-used at least 15 cycles. • Extremely low catalyst contaminant (<1 ppm) was presented

  5. High energy Er-doped Q-switched fiber laser with WS2 saturable absorber

    Science.gov (United States)

    Li, Lu; Wang, Yonggang; Wang, Zhen Fu; Wang, Xi; Yang, Guowen

    2018-01-01

    The report presents a stable Q-switched Er-doped fiber (EDF) laser with WS2-based saturable absorber (SA). The SA is obtained by mixing WS2 dispersion with polyvinyl alcohol (PVA) into polystyrene cells, and then evaporating them to form WS2/PVA film. The modulation depth (MD) of WS2/PVA is 2% and the saturable intensity (Isat) is 27.2 MW/cm2. Employing the WS2/PVA film into EDF laser cavity, stable Q-switched operation is achieved with central wavelength of 1560 nm. The repetition rate can be tuned from 16.15 to 60.88 kHz with increasing pump power from 30 to 320 mW. The single pulse energy increases from 82 to 195 nJ and then decreases down to 156 nJ with increasing pump power from 30 to 320 mW. The pulse width shows the same variation trend. The shortest pulse duration of 2.396 μs and the maximum single pulse energy of 195 nJ are obtained at the pump power of 220 mW. To the best of our knowledge, 195 nJ is the largest single pulse energy at 1.55 μm region with TMDs as Q-switcher. The signal-to-noise ratio (SNR) is measured to be 60 dB at the pump power of 130 mW. The long term stability of working is good too. The experimental results evidently show that the WS2/PVA SA can work as a promising Q-switcher for high power fiber lasers.

  6. Fabrication and photovoltaic performance of niobium doped TiO{sub 2} hierarchical microspheres with exposed {001} facets and high specific surface area

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yongqiang; Ran, Huili [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, Zhengzhou University, Zhengzhou 450001 (China); Fan, Jiajie, E-mail: fanjiajie@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, Zhengzhou University, Zhengzhou 450001 (China); Zhang, Xiaoli; Mao, Jing [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, Zhengzhou University, Zhengzhou 450001 (China); Shao, Guosheng [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); State Centre for International Cooperation on Designer Low-Carbon and Environmental Materials, Zhengzhou University, Zhengzhou 450001 (China); Institute for Renewable Energy and Environmental Technologies, University of Bolton, Bolton BL3 5AB (United Kingdom)

    2017-07-15

    Highlights: • Nb-doped hierarchical TiO{sub 2} microsphere DSSCs show enhanced performance. • Nb{sup 5+} dopant replaces Ti{sup 4+} cation in TiO{sub 2} lattice. • Electrons transport was enhanced due to the down-shifted conduction band minimum. • Exposed (001) facets and high specific surface area allows high dye-loading. - Abstract: The niobium doped hierarchical anatase TiO{sub 2} microspheres, which are consist of a serried nano-thorns and plicate nano-ribbons with exposed {001} facets, were synthesized using hydrothermal method followed by heat treatment. The effects of niobium on the microstructures and photovoltaic performances of the dye-sensitized solar cells (DSSCs) were studied. The results revealed that Nb{sup 5+} doping replaces Ti{sup 4+} cations in TiO{sub 2} lattice, and the bandgap of the films varies with increasing Nb doping concentration because of the downshift of the conduction band minimum (CBM). The niobium-doped TiO{sub 2} DSSCs with moderate loadings show enhanced performance comparing with their pure TiO{sub 2} counterparts. Optimally, the conversion efficiency of the Nb-3.5 (Nb 3.5 mol%) DSSC is 4.99%. This is higher than that (4.39%) of pure TiO{sub 2} cells by 13.7%. This is due to the fact that the Nb-doped solar cells have increased the number of the photo-induced electrons because of their exposed (001) facets and higher specific surface area; and enhanced electrons collection and transport because of the downshifted CBM of the Nb-doped TiO{sub 2}. However, heavy Nb doping results in the decrease of the performance of the niobium-doped cells due to the excessive defects within the Nb-TiO{sub 2} samples resulting in enhanced charge recombination at defects.

  7. High efficient removal of chromium (VI) using glycine doped polypyrrole adsorbent from aqueous solution

    CSIR Research Space (South Africa)

    Ballav, N

    2012-08-01

    Full Text Available Glycine doped polypyrrole (PPy-gly) adsorbent was prepared via in situ polymerization of pyrrole (Py) monomer in the presence of glycine (gly) for the removal of Cr(VI). Formation of PPy homopolymer and inclusion of gly in the PPy matrix were...

  8. Investigation of the Role of Hole Doping in Different High Temperature Superconducting Systems Using XANES Technique

    International Nuclear Information System (INIS)

    Hamdan, N.M.; Hasan, A.; Faiz, M.; Salim, M.A.; Hussain, Z.

    2004-01-01

    X-ray Absorption Near edge Structure (XANES) technique was used to study the role of hole doping in F-doped Hg-1223 and the Ce-doped Tl-1223. Oxygen k-edge and Cu L2,3-edge structures were thoroughly investigated. The pre-edge features of O k-edge spectra, as a function of doping, reveal important information about the projected local density of unoccupied states on the O sites in the region close to the absorption edge, which is a measure of O 2p hole concentration in the valance band. Furthermore, the Cu L2,3 absorption edge provides useful information about the valance state of Cu which is also related to the hole state in the CuO 2 planes. In this work, we will discuss these XANES results in these systems and correlate the observed improvements in the superconducting properties to the electronic structure in the CuO2 planes

  9. Highly sensitive miniature fluidic flowmeter based on an FBG heated by Co2+-doped fiber

    NARCIS (Netherlands)

    Liu, Z.; Htein, L.; Cheng, L.K.; Martina, Q.; Jansen, R.; Tam, H.Y.

    2017-01-01

    In this paper, we present a miniature fluidic flow sensor based on a short fiber Bragg grating inscribed in a single mode fiber and heated by Co2+-doped multimode fibers. The proposed flow sensor was employed to measure the flow rates of oil and water, showing good sensitivity of 0.339 nm/(m/s) and

  10. Graphene quantum dot-doped polyaniline nanofiber as high performance supercapacitor electrode materials.

    Science.gov (United States)

    Mondal, Sanjoy; Rana, Utpal; Malik, Sudip

    2015-08-11

    Graphene quantum dot-doped polyaniline composites have been prepared by the chemical oxidation of aniline. Synthesized novel fibrous composites show an excellent specific capacitance value of ∼1044 F g(-1) at a current density of 1 A g(-1) as well as moderate cyclic stability with a retention of life time of 80.1% after 3000 cycles.

  11. High-power Yb-doped continuous-wave and pulsed fibre lasers

    Indian Academy of Sciences (India)

    2014-01-05

    Jan 5, 2014 ... Continuous-wave fibre laser; Q-switched fibre laser; nonlinearity; thermal effects; selfpulsing; Yb-doped fibre; nanosecond pulse ... intracore fibre Bragg gratings, low thermal problems due to large surface to volume ratio, diffraction-limited beam quality, compactness, reliability and fibre-optic beam delivery.

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

    Science.gov (United States)

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

    2017-01-01

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

  13. Method of enhanced lithiation of doped silicon carbide via high temperature annealing in an inert atmosphere

    Science.gov (United States)

    Hersam, Mark C.; Lipson, Albert L.; Bandyopadhyay, Sudeshna; Karmel, Hunter J; Bedzyk, Michael J

    2014-05-27

    A method for enhancing the lithium-ion capacity of a doped silicon carbide is disclosed. The method utilizes heat treating the silicon carbide in an inert atmosphere. Also disclosed are anodes for lithium-ion batteries prepared by the method.

  14. Doping dependence of coupling between charge carriers and bosonic modes in the normal state of high- Tc superconductors

    Science.gov (United States)

    Saadaoui, H.; Azzouz, M.

    2005-11-01

    Recently, the doping dependence of the optical-conductivity scattering rate has been used by Hwang, Timusk, and Gu to gain some insight in the way the coupling between the charge carriers and the bosonic modes in high- Tc superconductors depends on doping. These authors used the extended Drude analysis, which does not take into account the normal-state pseudogap explicitly. In this work, we calculated the optical conductivity within the rotating antiferromagnetism theory, which models explicitly the pseudogap. Then we analyzed the resistivity as a function of temperature T and doping p . We extracted the scattering rate 1/τ by fitting the La2-xSrxCuO4 resistivity data. We found that for p smaller than a critical value pc , 1/τ shows a marginal-Fermi-liquid dependence for T greater than a p -dependent temperature Tρ* . But for T

  15. High energy electron irradiation effects on Ga-doped ZnO thin films for optoelectronic space applications

    Science.gov (United States)

    Serrao, Felcy Jyothi; Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.

    2018-03-01

    Gallium-doped ZnO (GZO) thin films of thickness 394 nm were prepared by a simple, cost-effective sol-gel spin coating method. The effect of 8 MeV electron beam irradiation with different irradiation doses ranging from 0 to 10 kGy on the structural, optical and electrical properties was investigated. Electron irradiation influences the changes in the structural properties and surface morphology of GZO thin films. X-ray diffraction analysis showed that the polycrystalline nature of the GZO films is unaffected by the high energy electron irradiation. The grain size and the surface roughness were found maximum for the GZO film irradiated with 10 kGy electron dosage. The average transmittance of GZO thin films decreased after electron irradiation. The optical band gap of Ga-doped ZnO films was decreased with the increase in the electron dosage. The electrical resistivity of GZO films decreased from 4.83 × 10-3 to 8.725 × 10-4 Ω cm, when the electron dosage was increased from 0 to 10 kGy. The variation in the optical and electrical properties in the Ga-doped ZnO thin films due to electron beam irradiation in the present study is useful in deciding their compatibility in optoelectronic device applications in electron radiation environment.

  16. Microstructure analysis of silicon nanocrystals formed from silicon rich oxide with high excess silicon: Annealing and doping effects

    Science.gov (United States)

    Nomoto, K.; Yang, T. C. J.; Ceguerra, A. V.; Zhang, T.; Lin, Z.; Breen, A.; Wu, L.; Puthen-Veettil, B.; Jia, X.; Conibeer, G.; Perez-Wurfl, I.; Ringer, S. P.

    2017-07-01

    Thin films consisting of silicon nanocrystals fabricated by high silicon content in silicon rich oxide show unique properties of decreasing resistivity and increasing light absorption while maintaining quantum confinement effects. With that said, the effect of the annealing temperature and doping element on the microscopic structure of silicon nanocrystals (Si NCs) and the film are still under research. In this study, individual intrinsic, boron-, and phosphorus-doped films are annealed at various temperatures, and their structural properties are analyzed via atom probe tomography together with glancing incidence x-ray diffraction, Raman spectroscopy (Raman), transmission electron microscopy (TEM), and energy filtered TEM. In addition, photoluminescence (PL) is performed and linked with their microstructural properties. The Si NC growth is confirmed at annealing temperatures of 1000 °C and 1100 °C. The microstructure of the Si NCs in the whole film is dramatically changed by increasing the annealing temperature from 1000 °C to 1100 °C. In addition, doping changes the arrangement of the Si NCs by assisting their penetration across the SiO2 barrier layers. This study helps to understand the relationship between the microscopic and macroscopic properties of the Si NC film, showing that the size and distribution of the Si NCs are correlated with the obtained PL profiles.

  17. Highly efficient Zr doped-TiO2/glass fiber photocatalyst and its performance in formaldehyde removal under visible light.

    Science.gov (United States)

    Huang, Chao; Ding, Yaping; Chen, Yingwen; Li, Peiwen; Zhu, Shemin; Shen, Shubao

    2017-10-01

    Zr-doped-TiO 2 loaded glass fiber (ZT/GF) composite photocatalysts with different Zr/Ti ratios were prepared with a sol-gel process. Zr 4+ can replace Ti 4+ in the TiO 2 lattice, which is conducive to forming the anatase phase and reducing the calcination temperature. The glass fiber carrier was responsible for better dispersion and loading of Zr-doped-TiO 2 particles, improving the applicability of the Zr-doped-TiO 2 . The ZT/GF photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis) and Barrett-Joyner-Halenda (BJH). The performance of photocatalysts with different loading was evaluated in formaldehyde degradation under visible light at room temperature. ZT/GF0.2 exhibited the highest activity, with a formaldehyde removal rate as high as 95.14% being observed, which is better than that of the photocatalyst particles alone. The stability of the catalyst was also tested, and ZT/GF exhibited excellent catalytic performance with 94.38% removal efficiency, even after seven uses. Copyright © 2017. Published by Elsevier B.V.

  18. Advanced interface modelling of n-Si/HNO3 doped graphene solar cells to identify pathways to high efficiency

    Science.gov (United States)

    Zhao, Jing; Ma, Fa-Jun; Ding, Ke; Zhang, Hao; Jie, Jiansheng; Ho-Baillie, Anita; Bremner, Stephen P.

    2018-03-01

    In graphene/silicon solar cells, it is crucial to understand the transport mechanism of the graphene/silicon interface to further improve power conversion efficiency. Until now, the transport mechanism has been predominantly simplified as an ideal Schottky junction. However, such an ideal Schottky contact is never realised experimentally. According to literature, doped graphene shows the properties of a semiconductor, therefore, it is physically more accurate to model graphene/silicon junction as a Heterojunction. In this work, HNO3-doped graphene/silicon solar cells were fabricated with the power conversion efficiency of 9.45%. Extensive characterization and first-principles calculations were carried out to establish an advanced technology computer-aided design (TCAD) model, where p-doped graphene forms a straddling heterojunction with the n-type silicon. In comparison with the simple Schottky junction models, our TCAD model paves the way for thorough investigation on the sensitivity of solar cell performance to graphene properties like electron affinity. According to the TCAD heterojunction model, the cell performance can be improved up to 22.5% after optimizations of the antireflection coatings and the rear structure, highlighting the great potentials for fabricating high efficiency graphene/silicon solar cells and other optoelectronic devices.

  19. Improvement in IBC-silicon solar cell performance by insertion of highly doped crystalline layer at heterojunction interfaces

    International Nuclear Information System (INIS)

    Bashiri, Hadi; Azim Karami, Mohammad; Mohammadnejad, Shahramm

    2017-01-01

    By inserting a thin highly doped crystalline silicon layer between the base region and amorphous silicon layer in an interdigitated back-contact (IBC) silicon solar cell, a new passivation layer is investigated. The passivation layer performance is characterized by numerical simulations. Moreover, the dependence of the output parameters of the solar cell on the additional layer parameters (doping concentration and thickness) is studied. By optimizing the additional passivation layer in terms of doping concentration and thickness, the power conversion efficiency could be improved by a factor of 2.5%, open circuit voltage is increased by 30 mV and the fill factor of the solar cell by 7.4%. The performance enhancement is achieved due to the decrease of recombination rate, a decrease in solar cell resistivity and improvement of field effect passivation at heterojunction interface. The above-mentioned results are compared with reported results of the same conventional interdigitated back-contact silicon solar cell structure. Furthermore, the effect of a-Si:H/c-Si interface defect density on IBC silicon solar cell parameters with a new passivation layer is studied. The additional passivation layer also reduces the sensitivity of output parameter of solar cell to interface defect density. (paper)

  20. High efficiency of transmittance and electrical conductivity of V doped ZnO used in solar cells applications

    Energy Technology Data Exchange (ETDEWEB)

    Boujnah, M., E-mail: boujnah.mourad@gmail.com [Laboratory of Magnetism and Physics of High Energies, Department of Physics, B.P. 1014, Faculty of Sciences, Mohammed V University, Rabat (Morocco); Boumdyan, M. [Laboratory of Magnetism and Physics of High Energies, Department of Physics, B.P. 1014, Faculty of Sciences, Mohammed V University, Rabat (Morocco); Naji, S. [Department of Physics, Faculty of Sciences, Ibb University, Ibb (Yemen); Benyoussef, A.; El Kenz, A.; Loulidi, M. [Laboratory of Magnetism and Physics of High Energies, Department of Physics, B.P. 1014, Faculty of Sciences, Mohammed V University, Rabat (Morocco)

    2016-06-25

    The full-potential linearized augmented plane wave method (FP-LAPW) based on the density functional theory (DFT) and Boltzmann's Transport theory, are employed to investigate theoretically the electronic structure, optical and electrical properties of vanadium -doped wurtzite ZnO with different concentrations (3.125%, 6.25%, 12.5%, 25%). The FP-LAPW based on the new potential approximation known as the Tran-Blaha modified Becke–Johnson exchange potential approximation (mBJ) was also applied with the primary goal of improving the electronic structure description specially the band gap energy. The calculated band structure and density of states (DOS) exhibit a band gap of pure ZnO (3.3 eV) closer to the experimental one. As well, our results indicate that the average transmittance in the 400–1000 nm wavelength region was 93%. We found that Zn{sub 96.875}V{sub 3.125}O is the optimized composition of the V doped ZnO, which has the highest conductivity (3.2 × 10{sup 3} (Ωcm){sup −1}) and transmittance. The high transmittance and electrical conductivity indicate that hexagonal V:ZnO system is a potential as material for solar energy applications. - Highlights: • We investigate theoretically the physical properties of V-doped wurtzite ZnO. • We used density functional calculations (DFT) and Boltzmann's Transport theory. • We examined the optical and electrical properties of different percentage of V doped ZnO.

  1. Comparative study of InGaP/GaAs high electron mobility transistors with upper and lower delta-doped supplied layers

    International Nuclear Information System (INIS)

    Tsai, Jung-Hui; Ye, Sheng-Shiun; Guo, Der-Feng; Lour, Wen-Shiung

    2012-01-01

    Influence corresponding to the position of δ-doped supplied layer on InGaP/GaAs high electron mobility transistors is comparatively studied by two-dimensional simulation analysis. The simulated results exhibit that the device with lower δ-doped supplied layer shows a higher gate potential barrier height, a higher saturation output current, a larger magnitude of negative threshold voltage, and broader gate voltage swing, as compared to the device with upper δ-doped supplied layer. Nevertheless, it has smaller transconductance and inferior high-frequency characteristics in the device with lower δ-doped supplied layer. Furthermore, a knee effect in current-voltage curves is observed at low drain-to-source voltage in the two devices, which is investigated in this article.

  2. Gram-scale production of B, N co-doped graphene-like carbon for high performance supercapacitor electrodes

    Science.gov (United States)

    Chen, Zhuo; Hou, Liqiang; Cao, Yan; Tang, Yushu; Li, Yongfeng

    2018-03-01

    Boron and nitrogen co-doped graphene-like carbon (BNC) with a gram scale was synthesized via a two-step method including a ball-milling process and a calcination process and used as electrode materials for supercapacitors. High surface area and abundant active sites of graphene-like carbon were created by the ball-milling process. Interestingly, the nitrogen atoms are doped in carbon matrix without any other N sources except for air. The textual and chemical properties can be easily tuned by changing the calcination temperature, and at 900 oC the BNC with a high surface area (802.35 m2/g), a high boron content (2.19 at%), a hierarchical pore size distribution and a relatively high graphitic degree was obtained. It shows an excellent performance of high specific capacitance retention about 78.2% at high current density (199 F/g at 100 A/g) of the initial capacitance (254 F/g at 0.25 A/g) and good cycling stability (90% capacitance retention over 1000 cycles at 100 A/g) measured in a three-electrode system. Furthermore, in a two-electrode system, a specific capacitance of 225 F/g at 0.25 A/g and a good cycling stability (93% capacitance retention over 20,000 cycles at 25 A/g) were achieved by using BNC as electrodes. The strategy of synthesis is facile and effective to fabricate multi-doped graphene-like carbon for promising candidates as electrode materials in supercapacitors.

  3. Nitrogen-doped porous carbon nanosheets made from biomass as highly active electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Pan, Fuping; Cao, Zhongyue; Zhao, Qiuping; Liang, Hongyu; Zhang, Junyan

    2014-12-01

    The successful commercialization of fuel cells requires the efficient electrocatalyst to make the oxygen reduction reaction (ORR) fast because of the sluggish nature of ORR and the high cost of the platinum catalysts. In this work, we report the excellent performance of metal-free nitrogen-doped porous carbon nanosheets (NPCN) with hierarchical porous structure and a high surface area of 1436.02 m2 g-1 for catalyzing ORR. The active NPCN is synthesized via facile high-temperature carbonization of natural ginkgo leaves followed by purification and ammonia post-treatment without using additional supporting templates and activation processes. In O2-saturated 0.1 M KOH solution, the resultant NPCN exhibits a high kinetic-limiting current density of 13.57 mA cm-2 at -0.25 V (vs. Ag/AgCl) approaching that of the commercial Pt/C catalyst (14 mA cm-2) and long-term electrochemical stability. Notably, the NPCN shows a slightly negative ORR half-wave potential in comparison with Pt/C (ΔE1/2 = 19 mV). The excellent electrocatalytic properties of NPCN originate from the combined effect of optimal nitrogen doping, high surface area, and porous architecture, which induce the high-density distribution of highly active and stable catalytic sites.

  4. Gadolinium-doped water cerenkov-based neutron and high energy gamma-ray detector and radiation portal monitoring system

    Science.gov (United States)

    Dazeley, Steven A; Svoboda, Robert C; Bernstein, Adam; Bowden, Nathaniel

    2013-02-12

    A water Cerenkov-based neutron and high energy gamma ray detector and radiation portal monitoring system using water doped with a Gadolinium (Gd)-based compound as the Cerenkov radiator. An optically opaque enclosure is provided surrounding a detection chamber filled with the Cerenkov radiator, and photomultipliers are optically connected to the detect Cerenkov radiation generated by the Cerenkov radiator from incident high energy gamma rays or gamma rays induced by neutron capture on the Gd of incident neutrons from a fission source. The PMT signals are then used to determine time correlations indicative of neutron multiplicity events characteristic of a fission source.

  5. Synthesis of highly fluorescent nitrogen and phosphorus doped carbon dots for the detection of Fe(3+) ions in cancer cells.

    Science.gov (United States)

    Chandra, Soumen; Laha, Dipranjan; Pramanik, Arindam; Ray Chowdhuri, Angshuman; Karmakar, Parimal; Sahu, Sumanta Kumar

    2016-02-01

    Highly fluorescent nitrogen and phosphorus-doped carbon dots with a quantum yield 59% have been successfully synthesized from citric acid and di-ammonium hydrogen phosphate by single step hydrothermal method. The synthesized carbon dots have high solubility as well as stability in aqueous medium. The as-obtained carbon dots are well monodispersed with particle sizes 1.5-4 nm. Owing to a good tunable fluorescence property and biocompatibility, the carbon dots were applied for intercellular sensing of Fe(3+) ions as well as cancer cell imaging. Copyright © 2015 John Wiley & Sons, Ltd.

  6. Examination of Factors Explaining Coaching Strategy and Training Methodology as Correlates of Potential Doping Behavior in High-Level Swimming

    Science.gov (United States)

    Liposek, Silvester; Zenic, Natasa; Saavedra, Jose M; Sekulic, Damir; Rodek, Jelena; Marinsek, Miha; Sajber, Dorica

    2018-01-01

    Although coaching is considered an important determinant of athletes’ potential doping behavior (PDB), there is an evident lack of studies that have examined coaching-strategy-and-training-methodology (CS&TM) in relation to PDB. This study was aimed to identify the specific associations that may exist between CS&TM -factors and other factors, and PDB in high-level swimming. The sample comprised 94 swimmers (35 females; 19.7 ± 2.3 years of age) and consisted of swimmers older than 18 years who participated in the 2017 National Championship. Variables were collected by previously validated questionnaires, with the addition of questions where athletes were asked about CS&TM to which they had been exposed. Multinomial logistic regression was applied for the criterion PDB (Negative PDB – Neutral PDB – Positive PDB). The higher risk for positive-PDB was found in males (OR: 6.58; 95%CI: 1.01-9.12); therefore, all regressions were adjusted for gender. Those swimmers who achieved better competitive result were less prone to neutral-PDB (0.41; 0.17-0.98). The positive-PDB was evidenced in those swimmers who perceived that their training was monotonous and lacked diversity (1.82; 1.41-5.11), and who were involved in training which was mostly oriented toward volume (1.76; 1.11-7.12). The lower likelihood of positive-PDB is found in those who replied that technique is practiced frequently (0.12; 0.01-0.81), those who replied that coach regularly provided the attention to explain the training aims (0.21; 0.04-0.81), and that coach frequently reviewed and discussed the quality of execution of specific tasks (0.41; 0.02-0.81). The findings on the relationships between the studied variables and PDB should be incorporated into targeted anti-doping efforts in swimming. Further studies examining sport-specific variables of CS&TM in younger swimmers and other sports are warranted. Key points The opinions about doping presence in swimming were not associated with athletes

  7. Compositionally modulated multilayer diamond-like carbon coatings with AlTiSi multi-doping by reactive high power impulse magnetron sputtering

    Science.gov (United States)

    Dai, Wei; Gao, Xiang; Liu, Jingmao; Kwon, Se-Hun; Wang, Qimin

    2017-12-01

    Diamond-like carbon (DLC) coatings with AlTiSi multi-doping were prepared by a reactive high power impulse magnetron sputtering with using a gas mixture of Ar and C2H2 as precursor. The composition, microstructure, compressive stress, and mechanical property of the as-deposited DLC coatings were studied systemically by using SEM, XPS, TEM, Raman spectrum, stress-tester, and nanoindentation as a function of the Ar fraction. The results show that the doping concentrations of the Al, Ti and Si atoms increased as the Ar fraction increased. The doped Ti and Si preferred to bond with C while the doped Al mainly existed in oxidation state without bonding with C. As the doping concentrations increased, TiC carbide nanocrystals were formed in the DLC matrix. The microstructure of coatings changed from an amorphous feature dominant AlTiSi-DLC to a carbide nanocomposite AlTiSi-DLC with TiC nanoparticles embedding. In addition, the coatings exhibited the compositionally modulated multilayer consisting of alternate Al-rich layer and Al-poor layer due to the rotation of the substrate holder and the diffusion behavior of the doped Al which tended to separate from C and diffuse towards the DLC matrix surface owing to its weak interactions with C. The periodic Al-rich layer can effectively release the compressive stress of the coatings. On the other hand, the hard TiC nanoparticles were conducive to the hardness of the coatings. Consequently, the DLC coatings with relatively low residual stress and high hardness could be acquired successfully through AlTiSi multi-doping. It is believed that the AlCrSi multi-doping may be a good way for improving the comprehensive properties of the DLC coatings. In addition, we believe that the DLC coatings with Al-rich multilayered structure have a high oxidation resistance, which allows the DLC coatings application in high temperature environment.

  8. High electrocatalytic performance of nitrogen-doped carbon nanofiber-supported nickel oxide nanocomposite for methanol oxidation in alkaline medium

    Energy Technology Data Exchange (ETDEWEB)

    Al-Enizi, Abdullah M. [Department of Chemistry, King Saud University, PO Box: 2455, Riyadh 11451 (Saudi Arabia); Elzatahry, Ahmed A., E-mail: aelzatahry@ksu.edu.sa [Materials Science and Technology Program, College of Arts and Science, Qatar University, Doha 2713 (Qatar); Advanced Technology and New Materials Research Institute, City of Scientific Research and Technology Applications, New Borg El-Arab City, Alexandria 21934 (Egypt); Abdullah, Aboubakr M., E-mail: bakr@qu.edu.qa [Center for Advanced Materials, Qatar University, Doha 2713 (Qatar); Vinu, Ajayan [Future Industries Institute, University of South Australia, Building X-X2-09, Mawson Lakes Campus, Mawson Lakes 5095 SA (Australia); Iwai, Hideo [Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047 (Japan); Al-Deyab, Salem S. [Petrochemical Research Chair, Department of Chemistry, King Saud University, PO Box: 2455, Riyadh 11451 (Saudi Arabia)

    2017-04-15

    Highlights: • A mixture of Polyvinylpyrrolidone (PVP), graphene and emeraldine base polyaniline (PANi) was electrospun and used as starting materials to prepare a nitrogen-doped carbon nanofiber (N-CNF). • Nickel oxide was loaded on the N-CNF to form a nanocomposite which was calcined later at different temperatures. • The effect of calcination temperature on the electrocatalytic behavior of the nanocomposite was studied which shows that the nanocomposite calcined at 500 °C was proved to be very high compared to the other calcination temperatures. • The stability of catalyst was excellent and its resistance to the adsorption of the intermediates generated from the methanol oxidation was very high. - Abstract: Nitrogen-Doped Carbon Nanofiber (N-CNF)–supported NiO composite was prepared by electrospinning a sol-gel mixture of graphene and polyaniline (PANi) with aqueous solutions of Polyvinylpyrrolidone (PVP) followed by a high-temperature annealing process. The electrospun was stabilized for 2 h at 280 °C, carbonized for 5 h at 1200 °C then loaded by 10% NiO. The electrocatalytic activities of the produced nanocomposite have been studied using cyclic voltammetry, and chronoamperometry. Also, N-CNF was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area (BET), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and scanning-electron microscopy (SEM). The obtained N-doped carbon nanofiber was found to have a nitrogen content of 2.6 atomic% with a diameter range of (140–160) nm, and a surface area (393.3 m{sup 2} g{sup −1}). In addition, it showed a high electrocatalytic behavior towards methanol oxidation reaction in alkaline medium and high stability and resistivity to the adsorption of intermediates.

  9. Laser-induced local activation of Mg-doped GaN with a high lateral resolution for high power vertical devices

    Directory of Open Access Journals (Sweden)

    Noriko Kurose

    2018-01-01

    Full Text Available A method for laser-induced local p-type activation of an as-grown Mg-doped GaN sample with a high lateral resolution is developed for realizing high power vertical devices for the first time. As-grown Mg-doped GaN is converted to p-type GaN in a confined local area. The transition from an insulating to a p-type area is realized to take place within about 1–2 μm fine resolution. The results show that the technique can be applied in fabricating the devices such as vertical field effect transistors, vertical bipolar transistors and vertical Schottkey diode so on with a current confinement region using a p-type carrier-blocking layer formed by this technique.

  10. Laser-induced local activation of Mg-doped GaN with a high lateral resolution for high power vertical devices

    Science.gov (United States)

    Kurose, Noriko; Matsumoto, Kota; Yamada, Fumihiko; Roffi, Teuku Muhammad; Kamiya, Itaru; Iwata, Naotaka; Aoyagi, Yoshinobu

    2018-01-01

    A method for laser-induced local p-type activation of an as-grown Mg-doped GaN sample with a high lateral resolution is developed for realizing high power vertical devices for the first time. As-grown Mg-doped GaN is converted to p-type GaN in a confined local area. The transition from an insulating to a p-type area is realized to take place within about 1-2 μm fine resolution. The results show that the technique can be applied in fabricating the devices such as vertical field effect transistors, vertical bipolar transistors and vertical Schottkey diode so on with a current confinement region using a p-type carrier-blocking layer formed by this technique.

  11. Electrochemical study of a novel high performance supercapacitor based on MnO{sub 2}/nitrogen-doped graphene nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Naderi, Hamid Reza, E-mail: hrnaderi@ut.ac.ir [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Norouzi, Parviz, E-mail: norouzi@khayam.ut.ac.ir [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Biosensor Research Center, Endocrinology & Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ganjali, Mohammad Reza, E-mail: ganjali@khayam.ut.ac.ir [Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Biosensor Research Center, Endocrinology & Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2016-03-15

    Graphical abstract: - Highlights: • MnO{sub 2} nanoparticles was prepared by sonochemical method. • MnO{sub 2} are anchored on the surface of nitrogen-doped reduced graphene oxide (NRGO). • MnO{sub 2}/NRGO nanocomposite show high capacitance, good rate and cycling performance. • The nanocomposite electrode exhibits specific capacitance of 522 F g{sup −1} in 2 mV s{sup −1}. • The electrode reveals 97% retention of initial capacitance after 4000 cycles. - Abstract: A new nanocomposite was synthesized via deposition of MnO{sub 2} on Nitrogen-doped reduced graphene (MnO{sub 2}/NRGO) by sonochemical method, in which, the particles of manganese oxide were uniformly distributed on NRGO sheets. The structure and morphology of MnO{sub 2}/NRGO nanocomposites are characterized by X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The electrochemical supercapacitive performance of the nanocomposite was investigated by cyclic voltammetry (CV), continuous cyclic voltammetry (CCV), galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS) methods. The MnO{sub 2}/NRGO nanocomposite shows enhanced specific capacitance of 522 F g{sup −1} at 2 mV s{sup −1} and its high synergistic effect was compared with MnO{sub 2}/RGO. The high specific capacitance and exceptionally high cyclic stability of MnO{sub 2}/NRGO attributes to the doping of nitrogen and uniform dispersion of MnO{sub 2} particles on NRGO. The CCV showed that the capacity retention for MnO{sub 2}/NRGO and MnO{sub 2}/RGO still maintained at 96.3% and 93% after 4000 CVs. The improved supercapacitive performance enables this nanocomposite as efficient electrode material for supercapacitor electrodes.

  12. Sulfur impregnated N, P co-doped hierarchical porous carbon as cathode for high performance Li-S batteries

    Science.gov (United States)

    Cai, Junjie; Wu, Chun; Zhu, Ying; Zhang, Kaili; Shen, Pei Kang

    2017-02-01

    A nitrogen and phosphorus co-doped hierarchical porous carbon (N, P-HPC) were fabricated by simply pyrolysis of polyaniline aerogels in the presence of phytic acid and subsequently activation treatment by KOH. The as-prepared N, P-HPC with a highly interconnected network structure and possesses a large surface area and pore volume is very favor in the impregnation of sulfur. Moreover, simultaneously introduced nitrogen and phosphorous into the carbon could create more active sites than the mono-doped carbons, the synergistic effects of dual activation of carbon atoms induced stronger chemical adsorption ability. Benefiting from the advantages of suitable hierarchical porosity, high conductivity, fast ion transportation, physical and chemical adsorption of the N, P-HPC, the Sulfur/N, P-HPC composite exhibits high initial discharge capacity of 1116 mAh g-1 at 0.1 C (1 C = 1675 mA g-1, based on sulfur content) and high rate capability of 550 mAh g-1 at 2C, as well as excellent long term cycling stability at a current rate of 1 C with only 0.058% capacity decay per cycle for over 500 cycles. Such a high capacity and stability suggests that the novel cathode have alluring prospect for Li-S batteries.

  13. Tetra-heteroatom self-doped carbon nanosheets derived from silkworm excrement for high-performance supercapacitors

    Science.gov (United States)

    Lei, Shuijin; Chen, Lianfu; Zhou, Wei; Deng, Peiqin; Liu, Yan; Fei, Linfeng; Lu, Wei; Xiao, Yanhe; Cheng, Baochang

    2018-03-01

    Carbon materials are deemed to be competitive candidate electrode materials for energy storage systems. It is still a great challenge to explore advanced carbon-based electrode materials for high-performance supercapacitors by a facile, economical and efficient method. In this work, N-, P-, S-, O-self-doped carbon nanosheets with high surface area and well-developed porosity are successfully prepared by pyrolysis carbonization and post KOH activation from silkworm excrement, a novel abundant, low-cost and eco-friendly agricultural waste. Thanks to their unique multi-heteroatom doping and porous structure, the obtained carbon materials exhibit high charge storage capacity with a specific capacitance of 401 F g-1 at a current density of 0.5 A g-1 in 6 M KOH and good cycling stability with a capacitance retention of 93.8% over 10000 cycles. A symmetric supercapacitor device using 1 M Na2SO4 aqueous solution as the electrolyte can deliver a specific capacitance of 41.7 F g-1 at a current density of 0.5 A g-1, and a high energy density of 23.17 Wh kg-1 at a power density of 500 W kg-1 with a wide voltage window of 2.0 V. This work develops a new strategy to produce favorable carbon-based electrode materials for supercapacitors with high electrochemical performances.

  14. Electron energy-loss spectroscopy on n-type doped high-temperature superconductors and related systems

    International Nuclear Information System (INIS)

    Alexander, M.

    1992-08-01

    Electron-enery loss spectroscopy measurements on n-type doped high temperature superconductors, their undoped parent compounds, Y-doped Bi 2 Sr 2 CaCu 2 O 8 and some rare earth oxides are presented. The undoped parent compounds Ln 2 CuO 4 (Ln = Pr, Nd, Sm) are charge transfer insulators with a charge transfer energy gap of 1.4 eV. The conduction band lies in the CuO 2 plane and has mainly Cu3d x 2 -y 2 character. O2p x,y states are slightly hybridized with this band. Upon partially substituting the trivalent Ln ions by tetravalent Ce or Th and monovalent F for the O ions, electron doping of the CuO 2 plane occurs with the electrons having mainly Cu3d character. A rigid band behaviour is proposed by several band structure calculations could be ruled out, as well as the occurence of so called 'mid-gap' states appearing inside the band gap between the valence and conduction bands. The position of the Fermi level was found to be at the bottom of the conduction bands. No measurable influence of the reduction process, necessary to obtain superconductivity, was detected in the unoccupied density of states. Characteristics shifts of the measured oxygen and copper edges were correlated with crossing the metal-insulator transition. These shifts are most probably caused by an improved screening capacity of the free charge carriers. A similar effect was also observed in Y-doped Bi 2 Sr 2 CaCu 2 O 8 . Thus, it was possible to show that the disappearance of the valence band hole states upon doping did not occur in a rigid-band-like manner. The low energy excitations in Nd 1.85 Ce 0.15 CuO 4-δ showed a plasmon like excitation at about 1 eV as well as a reduction and an energy shift of the charge transfer excitation. The dispersion of this plasmon excitation was determined. (orig.)

  15. High power, ultra-broadband supercontinuum source based on highly GeO2 doped silica fiber

    DEFF Research Database (Denmark)

    Jain, Deepak; Sidharthan, Raghuraman; Moselund, Peter M.

    2017-01-01

    We demonstrate a 74 mol % GeO2 doped fiber for mid-infrared supercontinuum generation. Experiments ensure a highest output power for a broadest spectrum from 700nm to 3200nm from this fiber, while being pumped by a broadband 4 stage Erbium fiber based MOPA. The effect of repetition rate of pump s...

  16. Hollow Amorphous MnSnO3 Nanohybrid with Nitrogen-Doped Graphene for High-Performance Lithium Storage

    International Nuclear Information System (INIS)

    Liu, Peng; Hao, Qingli; Xia, Xifeng; Lei, Wu; Xia, Hui; Chen, Ziyang; Wang, Xin

    2016-01-01

    Graphical abstract: A novel hybrid of hollow amorphous MnSnO 3 nanoparticles and nitrogen-doped reduced graphene oxide was fabricated. The unique structure and well-combination of both components account for the ultra long-term cyclic life with high reversible capacity of 610 mAh g −1 over 1000 cycles at 400 mA g −1 . - Highlights: • Novel hybrid of MnSnO 3 and nitrogen-doped reduced graphene oxide was fabricated. • The MnSnO 3 nanoparticles possess amorphous and hollow structure in the composite. • The excellent electrochemical performance benefits from unique nanostructure. • The reversible capacity of as-prepared hybrid is 610 mAh g −1 after 1000 cycles. • A long-term life with 97.3% capacity retention over 1000 cycles was obtained. - Abstract: Tin-based metal oxides usually suffer from severe capacity fading resulting from aggregation and considerable volume variation during the charge/discharge process in lithium ion batteries. In this work, a novel nanocomposite (MTO/N-RGO) of hollow amorphous MnSnO 3 (MTO) nanoparticles and nitrogen-doped reduced graphene oxide (N-RGO) has been designed and synthesized by a two-step method. Firstly, the nitrogen-doped graphene nanocomposite (MTO/N-RGO-P) with MnSn(OH) 6 crystal nanoparticles was synthesized by a facile solvothermal method. Subsequently, the MTO/N-RGO nanocomposite was obtained through the post heat treatment of MTO/N-RGO-P. The designed heterostructure and well-combination of the hollow amorphous MTO and N-RGO matrix can accelerate the ionic and electronic transport, and simultaneously accommodate the aggregation and volume variation of MTO nanoparticles during the lithiation–delithiation cycles. The as-prepared hybrid of MTO and N-RGO (MTO/N-RGO) exhibits a high reversible capacity of 707 mAh g −1 after 110 cycles at 200 mA g −1 , superior rate capability, and long-term cyclic life with high capacity of 610 mAh g −1 over 1000 cycles at 400 mA g −1 . Superior capacity retention of

  17. Highly efficient volume hologram multiplexing in thick dye-doped jelly-like gelatin.

    Science.gov (United States)

    Katarkevich, Vasili M; Rubinov, Anatoli N; Efendiev, Terlan Sh

    2014-08-01

    Dye-doped jelly-like gelatin is a thick-layer self-developing photosensitive medium that allows single and multiplexed volume phase holograms to be successfully recorded using pulsed laser radiation. In this Letter, we present a method for multiplexed recording of volume holograms in a dye-doped jelly-like gelatin, which provides significant increase in their diffraction efficiency. The method is based on the recovery of the photobleached dye molecule concentration in the hologram recording zone of gel, thanks to molecule diffusion from other unexposed gel areas. As an example, an optical recording of a multiplexed hologram consisting of three superimposed Bragg gratings with mean values of the diffraction efficiency and angular selectivity of ∼75% and ∼21', respectively, is demonstrated by using the proposed method.

  18. Electronic properites of electron-doped cuprate superconductors probed by high-field magnetotransport

    Energy Technology Data Exchange (ETDEWEB)

    Helm, Toni

    2013-09-18

    In the present work the normal-state properties of the electron-doped cuprate superconductor Nd{sub 2-x}Ce{sub x}CuO{sub 4} (NCCO) are investigated for a broad doping range, covering almost the whole phase diagram of this material. Magnetotransport measurements in the world's highest non-destructive magnetic fields were used as a spectroscopic tool for probing the electronic structure of single-crystalline NCCO as a function of the carrier concentration x. Quantum and semiclassical oscillations in the magnetoresistance provided new insights into various properties of the Fermi surface and the nature of the ground state in the system. The detailed investigations of the field- and temperature-dependent transport and its dependence on the field orientation have revealed a close correlation between symmetry-breaking ordering instabilities and the superconducting state.

  19. Electronic properites of electron-doped cuprate superconductors probed by high-field magnetotransport

    International Nuclear Information System (INIS)

    Helm, Toni

    2013-01-01

    In the present work the normal-state properties of the electron-doped cuprate superconductor Nd 2-x Ce x CuO 4 (NCCO) are investigated for a broad doping range, covering almost the whole phase diagram of this material. Magnetotransport measurements in the world's highest non-destructive magnetic fields were used as a spectroscopic tool for probing the electronic structure of single-crystalline NCCO as a function of the carrier concentration x. Quantum and semiclassical oscillations in the magnetoresistance provided new insights into various properties of the Fermi surface and the nature of the ground state in the system. The detailed investigations of the field- and temperature-dependent transport and its dependence on the field orientation have revealed a close correlation between symmetry-breaking ordering instabilities and the superconducting state.

  20. Hydrodynamic characteristics of high Z doped plastic targets irradiated by intense laser beams

    International Nuclear Information System (INIS)

    Pant, H.C.; Dhareshwar, L.J.; Shirsat, T.S.; Naik, P.A.; Nandwana, P.D.

    1990-01-01

    This paper reports on an enhanced spatial smoothing of ablative motion, stability and ablation pressure of laser irradiated thin plastic foil targets doped with tungsten that have been observed. Optical shadowgraphy and rear side cone calorimeter technique were used for measurement of foil motion and kinetic energy of accelerated target. Laser irradiance used in the experiment was in the range of 10 11 --10 13 W/cm 2 at 1.06 μm wavelength

  1. Study of high mobility carriers in Ni-doped CdO films

    Indian Academy of Sciences (India)

    Their d.c. conductivity, carrier concentration and mobility increased compared to undoped CdO film. The largest mobility of 112.6 cm2/V.s was measured for 1–2% Ni-doped CdO film. ... A A Dakhel1. Department of Physics, College of Science, University of Bahrain, P.O. Box 32038, Bahrain, Kingdom of Bahrain ...

  2. Effect of light rare earth doping in 123 high temperature supercoductors

    Directory of Open Access Journals (Sweden)

    M. Mirzadeh

    2006-09-01

    Full Text Available   We have studied the structural and electrical properties of Gd(Ba2-xLaxCu3O7+δ [Gd(BaLa123], Gd(Ba2-xNdxCu3O7+δ [Gd(BaNd123], and Nd(Ba2-xPrxCu3O7+δ [Nd(BaPr123] compounds with 0.0≤x≤0.8 prepared by the standard solid-state reaction. The XRD patterns show that all of the samples with x≤0.5 are isosructure 123 phase, but in Gd(BaNd123 and Nd(BaPr123 there are several impurity peaks in the XRD patterns for x≥0.6. We estimated the xcsolubility=1.1, 0.6 and 0.55 in Gd(BaLa123, Nd(BaPr123, and Gd(BaNd123, respectively. The resistivity increases with the increase of doping. The decrease of Tc with the increase of Pr doping is faster than Nd and La doping. The normal-state resistivity is fitted for two and three dimensional variable range hopping (2D&amp3D-VRH and Coulomb gap (CG regimes, separately. Our results indicate that the dominant mechanism for x≥xcSIT is 3D-VRH. The broadening of magnetoresistance have been investigated by TAFC and AH models. The pinning energy and Josephson coupling energy, decrease with the increase of applied magnetic field as U~H-β, these values also decrease with doping concentration Pr is more effective than Nd and La.

  3. 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.

  4. High resistivity In-doped ZnTe: electrical and optical properties

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Semi-insulating ZnTe prepared by In doping during Bridgman growth was found to have a resistivity of 5⋅74 × 107 ohm-cm, the highest reported so far in ZnTe, with hole concentration of 2⋅4 × 109/cm3 and hole mobility of 46 cm2/V⋅s at 300 K. The optical band gap was 2⋅06 eV at 293 K compared with ...

  5. Structure and high photocatalytic activity of (N, Ta)-doped TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Le, N. T. H.; Lam, V. D.; Manh, D. H.; Hong, L. V. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Hanoi (Viet Nam); Thanh, T. D., E-mail: thanhxraylab@yahoo.com, E-mail: scyu@cbnu.ac.kr [Institute of Materials Science, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Hanoi (Viet Nam); Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Pham, V.-T. [Center for Quantum Electronics, Institute of Physics, Vietnam Academy of Science and Technology, Hanoi (Viet Nam); Synchrotron SOLEIL, L' Orme des Merisiers, Boîte Postale, 48, 91192 Gif-sur-Yvette Cedex (France); Phan, T. L.; Yu, S. C., E-mail: thanhxraylab@yahoo.com, E-mail: scyu@cbnu.ac.kr [Department of Physics, Chungbuk National University, Cheongju 28644 (Korea, Republic of); Anh, T. X. [Center for Quantum Electronics, Institute of Physics, Vietnam Academy of Science and Technology, Hanoi (Viet Nam); Le, T. K. C. [Institut des Sciences Moleculaires d' Orsay, CNRS, Univ Paris-Sud, 91405 Orsay Cedex (France); Thammajak, N. [Synchrotron Light Research Institute, 111 University Avenue, Muang, Nakhon Ratchasima 30000 (Thailand)

    2016-10-14

    A hydrothermal method was used to prepare three nano-crystalline samples of TiO{sub 2} (S1), N-doped TiO{sub 2} (S2), and (N, Ta)-codoped TiO{sub 2} (S3) with average crystallite sizes (D) of 13–25 nm. X-ray diffraction studies confirmed a single phase of the samples with a tetragonal/anatase structure. A slight increase in the lattice parameters was observed when N and/or Ta dopants were doped into the TiO{sub 2} host lattice. Detailed analyses of extended X-ray absorption spectra indicated that N- and/or Ta-doping into TiO{sub 2} nanoparticles influenced the co-ordination number and radial distance (R) of Ti ions in the anatase structure. Concerning their absorption spectra, (N, Ta)-doping narrowed the band gap (E{sub g}) of TiO{sub 2} from 3.03 eV for S1 through 2.94 eV for S2 to 2.85 eV for S3. Such results revealed the applicability of these nanoparticles in the photocatalytic field working in the ultraviolet (UV)-visible region. Among these, photocatalytic activity of S3 was the strongest. By using S3 as a catalyst powder, the degradation efficiency of methylene blue solution was about 99% and 93% after irradiation of UV-visible light for 75 min and visible-light for 180 min, respectively.

  6. Highly hard yet toughened bcc-W coating by doping unexpectedly low B content

    KAUST Repository

    Yang, Lina

    2017-08-18

    Either hardness or toughness has been the core interest in scientific exploration and technological pursuit for a long time. However, it is still a big challenge to enhance the hardness and toughness at the same time, since the improvement of one side is always at the expense of the other one. Here, we have succeeded in dealing with this pair of conflict based on tungsten (W) coating by doping boron (B) via magnetron co-sputtering. The results reveal that the introduction of low concentrations of B (6.3 at. %), in the doping regime, leads to the formation of W(B) supersaturated solid solution with refined grains. Meanwhile, the doping-induced higher compressive stress, higher H/E* and denser microstructure result in a surprising combination of improved hardness (2 × larger than pure W) and superior toughness (higher crack formation threshold compared to pure W). We believe this is an innovative sight to design new generation of transition-metal-based multifunctional coatings. Besides, our results are applicable for industrial application because it can be realized by simple manufacturing approaches, e.g. magnetron sputtering technology.

  7. Honeysuckle-derived hierarchical porous nitrogen, sulfur, dual-doped carbon for ultra-high rate lithium ion battery anodes

    Science.gov (United States)

    Ou, Junke; Yang, Lin; Zhang, Zhen; Xi, Xianghui

    2016-11-01

    Nowadays, developing functional carbon materials from cheap natural materials is a highly compelling topic. Different from most explored biomass, honeysuckle is inherently rich in nitrogen and sulfur heteroatoms, and it has many advantages for production on a large scale. Here, hierarchical porous carbon (HPC), derived from waste honeysuckle via an environmentally friendly and economically viable method, has been reported as an anode for rechargeable lithium ion batteries. The as-fabricated HPC exhibits favorable features for electrochemical energy storage performance such as high specific surface area (830 m2 g-1), hierarchical three-dimensional (3D) pore network and heteroatoms (N and S) doping effects. HPC, when evaluated as an anode material for lithium ion batteries, shows superior cycling stability (maintaining a reversible capacity of 1215 mAh g-1 at the current density of 100 mA g-1 after 100 cycles) and excellent rate capability (370 mAh g-1 at the current density of 20 A g-1). Furthermore, owing to the appropriate heteroatoms doping, a high initial coulombic efficiency of 64.7% can be achieved. A widespread comparison with the literature also showed that the honeysuckle derived porous carbon was one of the most promising carbon-based anodes for high-rate lithium ion batteries.

  8. Porous polybenzimidazole membranes doped with phosphoric acid: Preparation and application in high-temperature proton-exchange-membrane fuel cells

    International Nuclear Information System (INIS)

    Li, Jin; Li, Xiaojin; Yu, Shuchun; Hao, Jinkai; Lu, Wangting; Shao, Zhigang; Yi, Baolian

    2014-01-01

    Highlights: • Porous polybenzimidazole membrane was prepared with glucose as porogen. • Phosphoric acid content was as high as 15.7 mol H 3 PO 4 per PBI repeat unit. • 200 h Constant current density test was carried out at 150 °C. • Degradation was due to the gap between membrane and catalyst layer. - Abstract: In this paper, the preparation and characterization of porous polybenzimidazole membranes doped with phosphoric acid were reported. For the preparation of porous polybenzimidazole membranes, glucose and saccharose were selected as porogen and added into PBI resin solution before solvent casting. The prepared porous PBI membranes had high proton conductivity and high content of acid doping at room temperature with 15.7 mol H 3 PO 4 per PBI repeat unit, much higher than pure PBI membrane at the same condition. Further, the performance and stability of the porous PBI membrane in high-temperature proton-exchange-membrane fuel cells was tested. It was found that the cell performance remained stable during 200 h stability test under a constant current discharge of 0.5 A cm −2 except for the last fifty hours. The decay in the last fifty hours was ascribed to the delamination between the catalyst layer and membrane increasing the charge-transfer resistance

  9. Sulfuric acid doped poly diaminopyridine/graphene composite to remove high concentration of toxic Cr(VI).

    Science.gov (United States)

    Dinda, Diptiman; Kumar Saha, Shyamal

    2015-06-30

    Sulfuric acid doped diaminopyridine polymers are synthesized in situ on graphene oxide surface via mutual oxidation-reduction technique. Exploiting large and highly porous surface, we have used this polymer composite as an adsorbent to remove high concentration of toxic Cr(VI) from water. It shows very high adsorption capacity (609.76 mg g(-1)) during removal process. The composite takes only 100 min to remove high concentration of 500 mg L(-1) Cr(VI) from water. Interesting features for this material is the enhancement of removal efficiency at lower acidic condition due to the formation of acid doped emeraldine salt during polymerization. XPS and AAS measurements reveal that our prepared material mainly follows reduction mechanism at higher acidic condition while anions exchange mechanism at lower acidic condition during the removal experiments. Good recycling ability with ∼ 92% removal efficiency after fifth cycle is also noticed for this material. Easy preparation, superior stability in acidic condition, remarkable removal efficiency and excellent recycling ability make this polymer composite an efficient material for modern filtration units in waste water purification. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Atomically Thin B doped g-C3N4 Nanosheets: High-Temperature Ferromagnetism and calculated Half-Metallicity

    OpenAIRE

    Daqiang Gao; Yonggang Liu; Peitao Liu; Mingsu Si; Desheng Xue

    2016-01-01

    Since the graphitic carbon nitride (g-C4N3), which can be seen as C-doped graphitic-C3N4 (g-C3N4), was reported to display ferromagnetic ground state and intrinsic half-metallicity (Du et al., PRL,108,197207,2012), it has attracted numerous research interest to tune the electronic structure and magnetic properties of g-C3N4 due to their potential applications in spintronic devices. In this paper, we reported the experimentally achieving of high temperature ferromagnetism in metal-free ultrath...

  11. Structure and thermal stability of nanostructured iron-doped zirconia prepared by high-energy ball milling

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Poulsen, Finn Willy; Mørup, Steen

    1999-01-01

    Fury stability cubic zirconia doped with iron oxide has been synthesized by high-energy ball milling from powder mixtures of monoclinic zirconia and hematite. It is found that the iron ions dissolved in cubic ZrO2 are in substitutional positions with a maximum solubility of approximately 18.5 mol......% alpha-Fe2O3. The unit-cell volume of the cubic ZrO2 phase decreases with increasing iron content. During heating hte cubic-to-tetragonal transition occurs at approximately 827 degrees C and the tetragonal-to-monoclinic transition seems to be absent at temperatures below 950 degrees C. During cooling...

  12. Cerium carbide embedded in nitrogen-doped carbon as a highly active electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Wang, Wei; Xue, Shouyuan; Li, Jinmei; Wang, Fengxia; Kang, Yumao; Lei, Ziqiang

    2017-08-01

    In this study, cerium carbide embedded in nitrogen-doped carbon (CeCx-NC) has been prepared by a facile pyrolysis of melamine formaldehyde resin containing rare-earth element. The as-prepared CeCx-NC catalyst shows high electrocatalytic activity towards oxygen reduction reaction (ORR) in alkaline electrolyte, with the half wave potential being almost equal to commercial Pt/C, nearly four electron transfer number, good toxicity tolerance durability and cycle stability. This rare-earth metal carbide opens a novel avenue for advanced electrocatalyst.

  13. Transition metal doped poly(aniline-co-pyrrole)/multi-walled carbon nanotubes nanocomposite for high performance supercapacitor electrode materials

    International Nuclear Information System (INIS)

    Dhibar, Saptarshi; Bhattacharya, Pallab; Hatui, Goutam; Das, C.K.

    2015-01-01

    Highlights: • The CuCl 2 doped copolymer (PANI and PPy)/MWCNTs nanocomposite was prepared. • The nanocomposite achieved highest specific capacitance of 383 F/g at a 0.5 A/g. • Nanocomposite exhibits better energy density as well as power density. • The nanocomposite also showed better electrical conductivity at room temperature. • The nanocomposite can be used as promising electrode materials for supercapacitor. - Abstract: In this present communication, copolymer of polyaniline (PANI) and polypyrrole (PPy) that is poly(aniline-co-pyrrole) [poly(An-co-Py)], copper chloride (CuCl 2 ) doped poly(aniline-co-pyrrole) [poly(An-co-Py) Cu], and CuCl 2 doped poly(aniline-co-pyrrole)/multi walled carbon nanotubes (MWCNTs) [poly(An-co-Py) Cu CNT] nanocomposite have been prepared by a simple and inexpensive in-situ chemical oxidative polymerization method, using ammonium persulfate (APS) as oxidant and hydrochloric acid (HCl) as dopant and investigated as high performance supercapacitor electrode materials. The possible interaction between CuCl 2 with copolymers and MWCNTs was investigated by Fourier transform infrared spectroscopy (FTIR) and UV–visible spectroscopy analysis. The morphological characteristic of all the electrode materials were analyzed by Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) study. The electrochemical characterizations of all the electrode materials were carried out by three electrode probe method where, standard calomel electrode and platinum were used as reference and counter electrodes, respectively. Among all the electrode materials, poly(An-co-Py) Cu CNT nanocomposite achieved highest specific capacitance value of 383 F/g at 0.5 A/g scan rate. The nanocomposite showed better electrical conductivity at room temperature and also attained nonlinear current–voltage characteristic. Based on the superior electrochemical as well as other properties the as prepared nanocomposite can be used

  14. Fabrication of high-performance metal ion doped iron oxide electrode for supercapacitor applications through a novel platform

    Science.gov (United States)

    Aghazadeh, Mustafa; Karimzadeh, Isa

    2017-10-01

    We provide a novel electrodeposition platform of undoped and Eu3+ doped iron oxide nanoparticles (Eu-IONPs) from an additive-free electrolyte containing Fe(NO3)3, FeCl2 and EuCl3. The prepared IONPs were analyzed using x-ray diffraction, field emission electron microscopy and energy-dispersive x-ray techniques, and the obtained data showed successful electrosynthesis of magnetite nanoparticles (size  ≈  10 nm) doped with about 10 wt% Eu3+ ions. The Eu-IONPs were used as supercapacitor electrode materials, and characterized by cyclic voltammetry and galvanostatic charge–discharge measurements. The as-synthesized Eu-IONPs exhibit remarkable pseudocapacitive activities including high specific capacitances of 212.5 and 153.2 F g‑1 at 0.5 and 2 A g‑1, respectively, and excellent cycling stabilities of 93.9% and 86.5% after 2000 discharging cycles. Furthermore, vibrational sample magnetometer data confirmed better superparamagnetic performance of Eu-IONPs (Ms  =  72.8 emu g‑1, Mr  =  0.24 emu g‑1 and H Ci  =  3.48 G) as compared with pure IONPs (Ms  =  51.92 emu g‑1, Mr  =  0.95 emu g‑1 and H Ci  =  14.62 G) due to exhibiting lower Mr and H Ci values. This novel synthetic platform of metal ion doped iron oxide is potentially a convenient way to fabricate high-performance iron oxide electrodes for energy storage systems.

  15. NiCoBP-doped carbon nanotube hybrid: A novel oxidase mimetic system for highly efficient electrochemical immunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bing; He, Yu; Liu, Bingqian; Tang, Dianping, E-mail: dianping.tang@fzu.edu.cn

    2014-12-03

    Highlights: • We report a new oxidase mimetic system for highly efficient electrochemical immunoassay. • NiCoBP-doped carbon nanotube hybrids were used as the nanocatalysts. • NiCoBP-doped carbon nanotube hybrids were used as the mimic oxidase. - Abstract: NiCoBP-doped multi-walled carbon nanotube (NiCoBP–MWCNT) was first synthesized by using induced electroless-plating method and functionalized with the biomolecules for highly efficient electrochemical immunoassay of prostate-specific antigen (PSA, used as a model analyte). We discovered that the as-synthesized NiCoBP–MWCNT had the ability to catalyze the glucose oxidization with a stable and well-defined redox peak. The catalytic current increased with the increment of the immobilized NiCoBP–MWCNT on the electrode. Transmission electron microscope (TEM) and energy dispersive X-ray spectrometry (EDX) were employed to characterize the as-prepared NiCoBP–MWCNT. Using the NiCoBP–MWCNT-conjugated anti-PSA antibody as the signal-transduction tag, a new enzyme-free electrochemical immunoassay protocol could be designed for the detection of target PSA on the capture antibody-functionalized immunosensing interface. Experimental results revealed that the designed immunoassay system could exhibit good electrochemical responses toward target PSA, and allowed the detection of PSA at a concentration as low as 0.035 ng mL{sup −1}. More importantly, the NiCoBP-MWCNT-based oxidase mimetic system could be further extended for the monitoring of other low-abundance proteins or disease-related biomarkers by tuning the target antibody.

  16. Transition metal doped poly(aniline-co-pyrrole)/multi-walled carbon nanotubes nanocomposite for high performance supercapacitor electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Dhibar, Saptarshi; Bhattacharya, Pallab; Hatui, Goutam; Das, C.K., E-mail: chapal12@yahoo.co.in

    2015-03-15

    Highlights: • The CuCl{sub 2} doped copolymer (PANI and PPy)/MWCNTs nanocomposite was prepared. • The nanocomposite achieved highest specific capacitance of 383 F/g at a 0.5 A/g. • Nanocomposite exhibits better energy density as well as power density. • The nanocomposite also showed better electrical conductivity at room temperature. • The nanocomposite can be used as promising electrode materials for supercapacitor. - Abstract: In this present communication, copolymer of polyaniline (PANI) and polypyrrole (PPy) that is poly(aniline-co-pyrrole) [poly(An-co-Py)], copper chloride (CuCl{sub 2}) doped poly(aniline-co-pyrrole) [poly(An-co-Py) Cu], and CuCl{sub 2} doped poly(aniline-co-pyrrole)/multi walled carbon nanotubes (MWCNTs) [poly(An-co-Py) Cu CNT] nanocomposite have been prepared by a simple and inexpensive in-situ chemical oxidative polymerization method, using ammonium persulfate (APS) as oxidant and hydrochloric acid (HCl) as dopant and investigated as high performance supercapacitor electrode materials. The possible interaction between CuCl{sub 2} with copolymers and MWCNTs was investigated by Fourier transform infrared spectroscopy (FTIR) and UV–visible spectroscopy analysis. The morphological characteristic of all the electrode materials were analyzed by Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) study. The electrochemical characterizations of all the electrode materials were carried out by three electrode probe method where, standard calomel electrode and platinum were used as reference and counter electrodes, respectively. Among all the electrode materials, poly(An-co-Py) Cu CNT nanocomposite achieved highest specific capacitance value of 383 F/g at 0.5 A/g scan rate. The nanocomposite showed better electrical conductivity at room temperature and also attained nonlinear current–voltage characteristic. Based on the superior electrochemical as well as other properties the as prepared

  17. Nitrogen-Doped Porous Carbons As Electrode Materials for High-Performance Supercapacitor and Dye-Sensitized Solar Cell.

    Science.gov (United States)

    Wang, Lan; Gao, Zhiyong; Chang, Jiuli; Liu, Xiao; Wu, Dapeng; Xu, Fang; Guo, Yuming; Jiang, Kai

    2015-09-16

    Activated N-doped porous carbons (a-NCs) were synthesized by pyrolysis and alkali activation of graphene incorporated melamine formaldehyde resin (MF). The moderate N doping levels, mesopores rich porous texture, and incorporation of graphene enable the applications of a-NCs in surface and conductivity dependent electrode materials for supercapacitor and dye-sensitized solar cell (DSSC). Under optimal activation temperature of 700 °C, the afforded sample, labeled as a-NC700, possesses a specific surface area of 1302 m2 g(-1), a N fraction of 4.5%, and a modest graphitization. When used as a supercapacitor electrode, a-NC700 offers a high specific capacitance of 296 F g(-1) at a current density of 1 A g(-1), an acceptable rate capability, and a high cycling stability in 1 M H2SO4 electrolyte. As a result, a-NC700 supercapacitor delivers energy densities of 5.0-3.5 Wh kg(-1) under power densities of 83-1609 W kg(-1). Moreover, a-NC700 also demonstrates high electrocatalytic activity for I3- reduction. When employed as a counter electrode (CE) of DSSC, a power conversion efficiency (PCE) of 6.9% is achieved, which is comparable to that of the Pt CE based counterpart (7.1%). The excellent capacitive and photovoltaic performances highlight the potential of a-NCs in sustainable energy devices.

  18. Hydrothermally Induced Oxygen Doping of Graphitic Carbon Nitride with a Highly Ordered Architecture and Enhanced Photocatalytic Activity.

    Science.gov (United States)

    Wang, Chao; Fan, Huiqing; Ren, Xiaohu; Ma, Jiangwei; Fang, Jiawen; Wang, Weijia

    2018-02-22

    As an amorphous or semicrystalline material, graphitic carbon nitride (g-C 3 N 4 ) displays poor photocatalytic activity owing to rapid recombination of the photogenerated charge carriers, which is mainly caused by a high density of defects in the graphitic structure. In this work, a porous O-doped g-C 3 N 4 (P-CNO) nanosheet with a highly ordered architecture is fabricated by introducing a novel hydrothermal treatment to the precursor before the final thermal condensation. The photocatalytic hydrogen evolution rate (HER) and HER per surface area of P-CNO are 13.9 and 1.7 times higher than that of bulk g-C 3 N 4 . The improved photocatalytic activity is ascribed to a synergistic effect of O doping, a porous sheet-like morphology, and increased crystallinity. This work also provides a new approach for the synthesis of other polymer-based photocatalysts with high crystallinity and excellent performance. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Highly-crystalline ultrathin gadolinium doped and carbon-coated Li4Ti5O12 nanosheets for enhanced lithium storage

    Science.gov (United States)

    Xu, G. B.; Yang, L. W.; Wei, X. L.; Ding, J. W.; Zhong, J. X.; Chu, P. K.

    2015-11-01

    Highly-crystalline gadolinium doped and carbon-coated ultrathin Li4Ti5O12 (LTO) nanosheets (denoted as LTO-Gd-C) as an anode material for Li-ion batteries (LIBs) are synthesized on large scale by controlling the amount of carbon precursor in the topotactic transformation of layered ultrathin Li1.81H0.19Ti2O5·xH2O (H-LTO) nanosheets at 700 °C. The characterizations of structure and morphology reveal that the gadolinium doped and carbon-coated ultrathin LTO nanosheets have high crystallinity with a thickness of about 10 nm. Gadolinium doping allows the spinel LTO products to be stabilized, thereby preserving the precursor's sheet morphology and single crystal structure. Carbon encapsulation serves dual functions by restraining crystal growth of the LTO primary nanoparticles in the LTO-Gd-C nanosheets and decreasing the external electron transport resistance. Owing to the synergistic effects rendered by ultrathin nanosheets with high crystallinity, gadolinium doping and carbon coating, the developed ultrathin LTO nanosheets possess excellent specific capacity, cycling performance, and rate capability compared with reference materials, when evaluated as an anode material for lithium ion batteries (LIBs). The simple and effective strategy encompassing nanoscale morphological engineering, surface modification, and doping improves the performance of LTO-based anode materials for high energy density and high power LIBs applied in large scale energy storage.

  20. First thin AC-coupled silicon strip sensors on 8-inch wafers

    Energy Technology Data Exchange (ETDEWEB)

    Bergauer, T., E-mail: thomas.bergauer@oeaw.ac.at [Institute of High Energy Physics of the Austrian Academy of Sciences, Nikolsdorfer Gasse 18, 1050 Wien (Vienna) (Austria); Dragicevic, M.; König, A. [Institute of High Energy Physics of the Austrian Academy of Sciences, Nikolsdorfer Gasse 18, 1050 Wien (Vienna) (Austria); Hacker, J.; Bartl, U. [Infineon Technologies Austria AG, Siemensstrasse 2, 9500 Villach (Austria)

    2016-09-11

    The Institute of High Energy Physics (HEPHY) in Vienna and the semiconductor manufacturer Infineon Technologies Austria AG developed a production process for planar AC-coupled silicon strip sensors manufactured on 200 μm thick 8-inch p-type wafers. In late 2015, the first wafers were delivered featuring the world's largest AC-coupled silicon strip sensors. Detailed electrical measurements were carried out at HEPHY, where single strip and global parameters were measured. Mechanical studies were conducted and the long-term behavior was investigated using a climate chamber. Furthermore, the electrical properties of various test structures were investigated to validate the quality of the manufacturing process.

  1. Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO thin films

    Directory of Open Access Journals (Sweden)

    Subodh K. Gautam

    2015-12-01

    Full Text Available The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO2 lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb+5 in the TiO2 lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR spectra of films with small size crystallites shows stiffening of about 4 cm−1 for the Eg(1 mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B1g mode exhibits a large anomalous softening of 20 cm−1 with asymmetrical broadening; which was not reported for the case of pure TiO2 crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb5+ doping induced reduction of Ti4+ ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

  2. Incorporation of DOPE into Lipoplexes formed from a Ferrocenyl Lipid leads to Inverse Hexagonal Nanostructures that allow Redox-Based Control of Transfection in High Serum.

    Science.gov (United States)

    Muller, John P E; Aytar, Burcu S; Kondo, Yukishige; Lynn, David M; Abbott, Nicholas L

    2012-01-01

    We report small angle X-ray and neutron scattering measurements that reveal that mixtures of the redox-active lipid bis(11-ferrocenylundecyl)dimethylammonium bromide (BFDMA) and dioleoylphosphatidylethanolamine (DOPE) spontaneously form lipoplexes with DNA that exhibit inverse hexagonal nanostructure (H(II) (c)). In contrast to lipoplexes of DNA and BFDMA only, which exhibit a multilamellar nanostructure (L(α) (c)) and limited ability to transfect cells in the presence of serum proteins, we measured lipoplexes of BFDMA and DOPE with the H(II) (c) nanostructure to survive incubation in serum and to expand significantly the range of media compositions (e.g., up to 80% serum) over which BFDMA can be used to transfect cells with high efficiency. Importantly, we also measured the oxidation state of the ferrocene within the BFDMA/DNA lipoplexes to have a substantial influence on the transfection efficiency of the lipoplexes in media containing serum. Specifically, whereas lipoplexes of reduced BFDMA and DOPE transfect cells with high efficiency, lipoplexes of oxidized BFDMA and DNA lead to low levels of transfection. Complementary measurements using SAXS reveal that the low transfection efficiency of the lipoplexes of oxidized BFDMA and DOPE correlates with the presence of weak Bragg peaks and thus low levels of H(II) (c) nanostructure in solution. Overall, these results provide support for our hypothesis that DOPE-induced formation of the H(II) (c) nanostructure of the BFDMA-containing lipoplexes underlies the high cell transfection efficiency measured in the presence of serum, and that the oxidation state of BFDMA within lipoplexes with DOPE substantially regulates the formation of the H(II) (c) nanostructure and thus the ability of the lipoplexes to transfect cells with DNA. More generally, the results presented in this paper suggest that lipoplexes formed from BFDMA and DOPE may offer the basis of approaches that permit active and external control of transfection of

  3. Highly doped semiconductor plasmonic nanoantenna arrays for polarization selective broadband surface-enhanced infrared absorption spectroscopy of vanillin

    Science.gov (United States)

    Barho, Franziska B.; Gonzalez-Posada, Fernando; Milla, Maria-Jose; Bomers, Mario; Cerutti, Laurent; Tournié, Eric; Taliercio, Thierry

    2017-11-01

    Tailored plasmonic nanoantennas are needed for diverse applications, among those sensing. Surface-enhanced infrared absorption (SEIRA) spectroscopy using adapted nanoantenna substrates is an efficient technique for the selective detection of molecules by their vibrational spectra, even in small quantity. Highly doped semiconductors have been proposed as innovative materials for plasmonics, especially for more flexibility concerning the targeted spectral range. Here, we report on rectangular-shaped, highly Si-doped InAsSb nanoantennas sustaining polarization switchable longitudinal and transverse plasmonic resonances in the mid-infrared. For small array periodicities, the highest reflectance intensity is obtained. Large periodicities can be used to combine localized surface plasmon resonances (SPR) with array resonances, as shown in electromagnetic calculations. The nanoantenna arrays can be efficiently used for broadband SEIRA spectroscopy, exploiting the spectral overlap between the large longitudinal or transverse plasmonic resonances and narrow infrared active absorption features of an analyte molecule. We demonstrate an increase of the vibrational line intensity up to a factor of 5.7 of infrared-active absorption features of vanillin in the fingerprint spectral region, yielding enhancement factors of three to four orders of magnitude. Moreover, an optimized readout for SPR sensing is proposed based on slightly overlapping longitudinal and transverse localized SPR.

  4. Highly doped semiconductor plasmonic nanoantenna arrays for polarization selective broadband surface-enhanced infrared absorption spectroscopy of vanillin

    Directory of Open Access Journals (Sweden)

    Barho Franziska B.

    2017-11-01

    Full Text Available Tailored plasmonic nanoantennas are needed for diverse applications, among those sensing. Surface-enhanced infrared absorption (SEIRA spectroscopy using adapted nanoantenna substrates is an efficient technique for the selective detection of molecules by their vibrational spectra, even in small quantity. Highly doped semiconductors have been proposed as innovative materials for plasmonics, especially for more flexibility concerning the targeted spectral range. Here, we report on rectangular-shaped, highly Si-doped InAsSb nanoantennas sustaining polarization switchable longitudinal and transverse plasmonic resonances in the mid-infrared. For small array periodicities, the highest reflectance intensity is obtained. Large periodicities can be used to combine localized surface plasmon resonances (SPR with array resonances, as shown in electromagnetic calculations. The nanoantenna arrays can be efficiently used for broadband SEIRA spectroscopy, exploiting the spectral overlap between the large longitudinal or transverse plasmonic resonances and narrow infrared active absorption features of an analyte molecule. We demonstrate an increase of the vibrational line intensity up to a factor of 5.7 of infrared-active absorption features of vanillin in the fingerprint spectral region, yielding enhancement factors of three to four orders of magnitude. Moreover, an optimized readout for SPR sensing is proposed based on slightly overlapping longitudinal and transverse localized SPR.

  5. Pomelo peels-derived porous activated carbon microsheets dual-doped with nitrogen and phosphorus for high performance electrochemical capacitors

    Science.gov (United States)

    Wang, Zhen; Tan, Yongtao; Yang, Yunlong; Zhao, Xiaoning; Liu, Ying; Niu, Lengyuan; Tichnell, Brandon; Kong, Lingbin; Kang, Long; Liu, Zhen; Ran, Fen

    2018-02-01

    In this work, biomass pomelo peel is used to fabricate the porous activated carbon microsheets, and diammonium hydrogen phosphate (DHP) is employed to dual-dope carbon with nitrogen and phosphorus elements. With the benefit of DHP inducement and dual-doping of nitrogen and phosphorus, the prepared carbon material has a higher carbon yield, and exhibits higher specific surface area (about 807.7 m2/g), and larger pore volume (about 0.4378 cm3/g) with hierarchically structure of interconnected thin microsheets compared to the pristine carbon. The material exhibits not only high specific capacitance (240 F/g at 0.5 A/g), but also superior cycling performance (approximately 100% of capacitance retention after 10,000 cycles at 2 A/g) in 2 M KOH aqueous electrolyte. Furthermore, the assembled symmetric electrochemical capacitor in 1 M Na2SO4 aqueous electrolyte exhibits a high energy density of 11.7 Wh/kg at a power density of 160 W/kg.

  6. Complex quantum transport in a modulation doped strained Ge quantum well heterostructure with a high mobility 2D hole gas

    Science.gov (United States)

    Morrison, C.; Casteleiro, C.; Leadley, D. R.; Myronov, M.

    2016-09-01

    The complex quantum transport of a strained Ge quantum well (QW) modulation doped heterostructure with two types of mobile carriers has been observed. The two dimensional hole gas (2DHG) in the Ge QW exhibits an exceptionally high mobility of 780 000 cm2/Vs at temperatures below 10 K. Through analysis of Shubnikov de-Haas oscillations in the magnetoresistance of this 2DHG below 2 K, the hole effective mass is found to be 0.065 m0. Anomalous conductance peaks are observed at higher fields which deviate from standard Shubnikov de-Haas and quantum Hall effect behaviour due to conduction via multiple carrier types. Despite this complex behaviour, analysis using a transport model with two conductive channels explains this behaviour and allows key physical parameters such as the carrier effective mass, transport, and quantum lifetimes and conductivity of the electrically active layers to be extracted. This finding is important for electronic device applications, since inclusion of highly doped interlayers which are electrically active, for enhancement of, for example, room temperature carrier mobility, does not prevent analysis of quantum transport in a QW.

  7. Hot Carrier Trapping in High-Purity and Doped Germanium Crystals at Millikelvin Temperatures

    Science.gov (United States)

    Piro, M.-C.; Broniatowski, A.; Marnieros, S.; Dumoulin, L.; Olivieri, E.

    2014-09-01

    A new set of experimental data is presented for the mean drift lengths and the drift velocities of hot electrons and holes as a function of the electric field in ultra-pure and in lightly doped (n- and p-type) germanium single crystals at mK temperatures. Measurements are made in the field range between 0.1 and 15 V/cm, typical for the operation of cryogenic germanium detectors for dark matter search. The analysis of the experimental data strongly suggests that the dominant trapping centers are the dopant species in the neutral state.

  8. Data acquisition and control of the 370 TBq high-pressure tritium doping device, TRIBA

    International Nuclear Information System (INIS)

    Pfeil, A.; Heer, H.; Laesser, R.; Klatt, K.H.

    1987-07-01

    The report is arranged as follows: After an introduction, the first section briefly discusses measured values obtained with the 37 TBq (10 3 Ci) doping device with a view to the enhanced measuring range that is achievable with the newly developed 370 TBq (10 4 Ci) device. Sections 3 and 4 explain the technical design of the device and the measuring and control equipment connected to the computer. All following sections are detailed descriptions of the computer configuration and the software. (orig./HP) [de

  9. Performance Degradation Tests of Phosphoric Acid Doped PBI Membrane Based High Temperature PEM Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2014-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation. Continuous tests with H2 and simulated reformate which was composed...... to the redistribution of PA between the membrane and electrodes. EIS measurement of first fuel cell during the start/stop test showed that the mass transfer resistance and ohmic resistance increased which can be attributed to the corrosion of carbon support in the catalyst layer and degradation of the PBI membrane...

  10. Remote target removal for the Oak Ridge 86-inch Cyclotron

    International Nuclear Information System (INIS)

    Walls, A.A.

    1982-01-01

    A remotely operated target remover has been plaed in operation at the 86-Inch Cyclotron located in Oak Ridge. The system provides for the remote removal of a target from inside the cyclotron, loading it into a cask, and the removal of the cask from the 1.5 m (5-ft) shielding walls. The remote system consists of multiple electrical and pneumatically operated equipment which is designed for controlled step-by-step operation, operated with an electrical control panel, and monitored by a television system. The target remover has reduced the radiation exposures to operating personnel at the facility and has increased the effective operating time. The system is fast, requires a minimum of skill to operate, and has demonstrated both reliability and durability

  11. Room-temperature ferromagnetism with high magnetic moment in Cu-doped AlN single crystal whiskers

    Science.gov (United States)

    Jiang, Liang-Bao; Liu, Yu; Zuo, Si-Bin; Wang, Wen-Jun

    2015-02-01

    Ferromagnetism is investigated in high-quality Cu-doped AlN single crystal whiskers. The whiskers exhibit room-temperature ferromagnetism with a magnetic moment close to the results from first-principles calculations. High crystallinity and low Cu concentrations are found to be indispensable for high magnetic moments. The difference between the experimental and theoretical moment values is explored in terms of the influence of nitrogen vacancies. The calculated results demonstrate that nitrogen vacancies can reduce the magnetic moments of Cu atom. Project supported by the National Basic Research Program of China (Grant No. 2013CB932901), the National Natural Science Foundation of China (Grant Nos. 51372267, 51210105026, and 51172270), the Funds from the Chinese Academy of Sciences, the International Centre for Diffraction Data, USA (2013 Ludo Frevel Crystallography Scholarship Award), and the Funds from the Ministry of Education of China (2012 Academic Scholarship Award for Doctoral Candidates).

  12. Heavily Graphitic-Nitrogen Self-doped High-porosity Carbon for the Electrocatalysis of Oxygen Reduction Reaction

    Science.gov (United States)

    Feng, Tong; Liao, Wenli; Li, Zhongbin; Sun, Lingtao; Shi, Dongping; Guo, Chaozhong; Huang, Yu; Wang, Yi; Cheng, Jing; Li, Yanrong; Diao, Qizhi

    2017-11-01

    Large-scale production of active and stable porous carbon catalysts for oxygen reduction reaction (ORR) from protein-rich biomass became a hot topic in fuel cell technology. Here, we report a facile strategy for synthesis of nitrogen-doped porous nanocarbons by means of a simple two-step pyrolysis process combined with the activation of zinc chloride and acid-treatment process, in which kidney bean via low-temperature carbonization was preferentially adopted as the only carbon-nitrogen sources. The results show that this carbon material exhibits excellent ORR electrocatalytic activity, and higher durability and methanol-tolerant property compared to the state-of-the-art Pt/C catalyst for the ORR, which can be mainly attributed to high graphitic-nitrogen content, high specific surface area, and porous characteristics. Our results can encourage the synthesis of high-performance carbon-based ORR electrocatalysts derived from widely-existed natural biomass.

  13. Doping of polycrystalline CdTe for high-efficiency solar cells on flexible metal foil

    Science.gov (United States)

    Kranz, Lukas; Gretener, Christina; Perrenoud, Julian; Schmitt, Rafael; Pianezzi, Fabian; La Mattina, Fabio; Blösch, Patrick; Cheah, Erik; Chirilă, Adrian; Fella, Carolin M.; Hagendorfer, Harald; Jäger, Timo; Nishiwaki, Shiro; Uhl, Alexander R.; Buecheler, Stephan; Tiwari, Ayodhya N.

    2013-08-01

    Roll-to-roll manufacturing of CdTe solar cells on flexible metal foil substrates is one of the most attractive options for low-cost photovoltaic module production. However, various efforts to grow CdTe solar cells on metal foil have resulted in low efficiencies. This is caused by the fact that the conventional device structure must be inverted, which imposes severe restrictions on device processing and consequently limits the electronic quality of the CdTe layer. Here we introduce an innovative concept for the controlled doping of the CdTe layer in the inverted device structure by means of evaporation of sub-monolayer amounts of Cu and subsequent annealing, which enables breakthrough efficiencies up to 13.6%. For the first time, CdTe solar cells on metal foil exceed the 10% efficiency threshold for industrialization. The controlled doping of CdTe with Cu leads to increased hole density, enhanced carrier lifetime and improved carrier collection in the solar cell. Our results offer new research directions for solving persistent challenges of CdTe photovoltaics.

  14. Highly conductive carbon nanotube buckypapers with improved doping stability via conjugational cross-linking.

    Science.gov (United States)

    Chen, I-Wen Peter; Liang, Richard; Zhao, Haibo; Wang, Ben; Zhang, Chuck

    2011-12-02

    Carbon nanotube (CNT) sheets or buckypapers have demonstrated promising electrical conductivity and mechanical performance. However, their electrical conductivity is still far below the requirements for engineering applications, such as using as a substitute for copper mesh, which is currently used in composite aircraft structures for lightning strike protection. In this study, different CNT buckypapers were stretched to increase their alignment, and then subjected to conjugational cross-linking via chemical functionalization. The conjugationally cross-linked buckypapers (CCL-BPs) demonstrated higher electrical conductivity of up to 6200 S cm( - 1), which is more than one order increase compared to the pristine buckypapers. The CCL-BPs also showed excellent doping stability in over 300 h in atmosphere and were resistant to degradation at elevated temperatures. The tensile strength of the stretched CCL-BPs reached 220 MPa, which is about three times that of pristine buckypapers. We attribute these property improvements to the effective and stable conjugational cross-links of CNTs, which can simultaneously improve the electrical conductivity, doping stability and mechanical properties. Specifically, the electrical conductivity increase resulted from improving the CNT alignment and inter-tube electron transport capability. The conjugational cross-links provide effective 3D conductive paths to increase the mobility of electrons among individual nanotubes. The stable covalent bonding also enhances the thermal stability and load transfer. The significant electrical and mechanical property improvement renders buckypaper a multifunctional material for various applications, such as conducting composites, battery electrodes, capacitors, etc.

  15. Efficient synthesis of highly fluorescent nitrogen-doped carbon dots for cell imaging using unripe fruit extract of Prunus mume

    International Nuclear Information System (INIS)

    Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Sethuraman, Mathur Gopalakrishnan; Lee, Yong Rok

    2016-01-01

    Graphical abstract: The green synthesis of highly fluorescent N-CDs was achieved using the extract of unripe P. mume fruit as a carbon precursor by a one-pot simple hydrothermal-carbonization method. The resulting N-CDs were used as a staining agent for the fluorescence imaging of MDA-MB-231 cells. Display Omitted - Highlights: • The green synthesis of highly fluorescent N-CDs using the extract of unripe P. mume. • The N-CDs were synthesized by one-pot hydrothermal-carbonization method. • This method of synthesis is a simple, cost effective and eco-friendly route. • N-CDs will be a good alternative for fluorescent dyes and SQDs for bio-applications. - Abstract: Highly fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized using the extract of unripe Prunus mume (P. mume) fruit by a simple one step hydrothermal-carbonization method. The N-CDs were synthesized at different pH ranges, 2.3, 5, 7, and 9. The pH of the P. mume extract was adjusted using an aqueous ammonia solution (25%). The optical properties of N-CDs were examined by UV–vis and fluorescence spectroscopy. The N-CDs synthesized at pH 9 emitted high fluorescence intensity compared to other obtained N-CDs. The N-CDs synthesized at pH 9 was further characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform-infra red (FT-IR) spectroscopy. HR-TEM showed that the average size of the synthesized N-CDs was approximately 9 nm and the interlayer distance was 0.21 nm, which was validated by XRD. The graphitic nature of the synthesized N-CDs were confirmed by Raman spectroscopy. XPS and FT-IR spectroscopy confirmed the doping of the nitrogen moiety over the synthesized CDs. The synthesized nitrogen doped CDs (N-CDs) were low toxicity and were used as a staining probe for fluorescence cell imaging.

  16. Efficient synthesis of highly fluorescent nitrogen-doped carbon dots for cell imaging using unripe fruit extract of Prunus mume

    Energy Technology Data Exchange (ETDEWEB)

    Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel [School of Chemical Engineering, Yeungnam University, Gyeongsan 38541 (Korea, Republic of); Sethuraman, Mathur Gopalakrishnan, E-mail: mgsethu@gmail.com [Department of Chemistry, Gandhigram Rural Institute-Deemed University, Gandhigram 624 302, Tamilnadu (India); Lee, Yong Rok, E-mail: yrlee@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan 38541 (Korea, Republic of)

    2016-10-30

    Graphical abstract: The green synthesis of highly fluorescent N-CDs was achieved using the extract of unripe P. mume fruit as a carbon precursor by a one-pot simple hydrothermal-carbonization method. The resulting N-CDs were used as a staining agent for the fluorescence imaging of MDA-MB-231 cells. Display Omitted - Highlights: • The green synthesis of highly fluorescent N-CDs using the extract of unripe P. mume. • The N-CDs were synthesized by one-pot hydrothermal-carbonization method. • This method of synthesis is a simple, cost effective and eco-friendly route. • N-CDs will be a good alternative for fluorescent dyes and SQDs for bio-applications. - Abstract: Highly fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized using the extract of unripe Prunus mume (P. mume) fruit by a simple one step hydrothermal-carbonization method. The N-CDs were synthesized at different pH ranges, 2.3, 5, 7, and 9. The pH of the P. mume extract was adjusted using an aqueous ammonia solution (25%). The optical properties of N-CDs were examined by UV–vis and fluorescence spectroscopy. The N-CDs synthesized at pH 9 emitted high fluorescence intensity compared to other obtained N-CDs. The N-CDs synthesized at pH 9 was further characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform-infra red (FT-IR) spectroscopy. HR-TEM showed that the average size of the synthesized N-CDs was approximately 9 nm and the interlayer distance was 0.21 nm, which was validated by XRD. The graphitic nature of the synthesized N-CDs were confirmed by Raman spectroscopy. XPS and FT-IR spectroscopy confirmed the doping of the nitrogen moiety over the synthesized CDs. The synthesized nitrogen doped CDs (N-CDs) were low toxicity and were used as a staining probe for fluorescence cell imaging.

  17. Developing high strength and ductility in biomedical Co-Cr cast alloys by simultaneous doping with nitrogen and carbon.

    Science.gov (United States)

    Yamanaka, Kenta; Mori, Manami; Chiba, Akihiko

    2016-02-01

    There is a strong demand for biomedical Co-Cr-based cast alloys with enhanced mechanical properties for use in dental applications. We present a design strategy for development of Co-Cr-based cast alloys with very high strength, comparable to that of wrought Co-Cr alloys, without loss of ductility. The strategy consists of simultaneous doping of nitrogen and carbon, accompanied by increasing of the Cr content to increase the nitrogen solubility. The strategy was verified by preparing Co-33Cr-9W-0.35N-(0.01-0.31)C (mass%) alloys. We determined the carbon concentration dependence of the microstructures and their mechanical properties. Metal ion release of the alloys in an aqueous solution of 0.6% sodium chloride (NaCl) and 1% lactic acid was also evaluated to ensure their corrosion resistance. As a result of the nitrogen doping, the formation of a brittle σ-phase, a chromium-rich intermetallic compound, was significantly suppressed. Adding carbon to the alloys resulted in finer-grained microstructures and carbide precipitation; accordingly, the strength increased with increasing carbon concentration. The tensile ductility, on the other hand, increased with increasing carbon concentration only up to a point, reaching a maximum at a carbon concentration of ∼0.1mass% and decreasing with further carbon doping. However, the alloy with 0.31mass% of carbon exhibited 14% elongation and also possessed very high strength (725MPa in 0.2% proof stress). The addition of carbon did not significantly degrade the corrosion resistance. The results show that our strategy realizes a novel high-strength Co-Cr-based cast alloy that can be produced for advanced dental applications using a conventional casting procedure. The present study suggested a novel alloy design concept for realizing high-strength Co-Cr-based cast alloys. The proposed strategy is beneficial from the practical point of view because it uses conventional casting approach-a simpler, more cost-effective, industrially

  18. Free-standing nitrogen-doped graphene paper as electrodes for high-performance lithium/dissolved polysulfide batteries.

    Science.gov (United States)

    Han, Kai; Shen, Jingmei; Hao, Shiqiang; Ye, Hongqi; Wolverton, Christopher; Kung, Mayfair C; Kung, Harold H

    2014-09-01

    Free-standing N-doped graphene papers (NGP), generated by pyrolysis of polydiallyldimethylammonium chloride, were successfully used as binder-free electrodes for the state-of-the-art Li/polysulfide-catholyte batteries. They exhibited high specific capacities of approximately 1000 mA h g(-1) (based on S) after 100 cycles and coulombic efficiencies great than 98%, significantly better than undoped graphene paper (GP). These NGP were characterized with XRD, X-ray photoelectron spectroscopy, thermogravimetric analysis, AFM, electron microscopy, and Raman and impedance spectroscopy before and after cycling. Spectroscopic evidence suggested stronger binding of sulfide to NGP relative to GP, and modelling results from DFT calculation, substantiated with experimental data, indicated that pyrrolic and pyridinic N atoms interacted more strongly with Li polysulfides than quaternary N atoms. Thus, more favorable partition of polysulfides between the electrode and the electrolyte and the corresponding effect on the morphology of the passivation layer were the causes of the beneficial effect of N doping. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Unintentional high-density p-type modulation doping of a GaAs/AlAs core-multishell nanowire.

    Science.gov (United States)

    Jadczak, J; Plochocka, P; Mitioglu, A; Breslavetz, I; Royo, M; Bertoni, A; Goldoni, G; Smolenski, T; Kossacki, P; Kretinin, A; Shtrikman, Hadas; Maude, D K

    2014-05-14

    Achieving significant doping in GaAs/AlAs core/shell nanowires (NWs) is of considerable technological importance but remains a challenge due to the amphoteric behavior of the dopant atoms. Here we show that placing a narrow GaAs quantum well in the AlAs shell effectively getters residual carbon acceptors leading to an unintentional p-type doping. Magneto-optical studies of such a GaAs/AlAs core-multishell NW reveal quantum confined emission. Theoretical calculations of NW electronic structure confirm quantum confinement of carriers at the core/shell interface due to the presence of ionized carbon acceptors in the 1 nm GaAs layer in the shell. Microphotoluminescence in high magnetic field shows a clear signature of avoided crossings of the n = 0 Landau level emission line with the n = 2 Landau level TO phonon replica. The coupling is caused by the resonant hole-phonon interaction, which points to a large two-dimensional hole density in the structure.

  20. Fabrication and Characterization of Highly Oriented N-Doped ZnO Nanorods by Selective Area Epitaxy

    Directory of Open Access Journals (Sweden)

    Yang Zhang

    2015-01-01

    Full Text Available High-quality nitrogen-doped ZnO nanorods have been selectively grown on patterned and bare ZnO templates by the combination of nanoimprint lithography and chemical vapor transport methods. The grown nanorods exhibited uniformity in size and orientation as well as controllable density and surface-to-volume ratio. The structural and optical properties of ZnO nanorods and the behaviour of N dopants have been investigated by means of the scanning electron microscope, photoluminescence (PL spectra, and Raman scattering spectra. The additional vibration modes observed in Raman spectra of N-doped ZnO nanorods provided solid evidence of N incorporation in ZnO nanorods. The difference of excitonic emissions from ZnO nanorods with varied density and surface-to-volume ratio suggested the different spatial distribution of intrinsic defects. It was found that the defects giving rise to acceptor-bound exciton (A0X emission were most likely to distribute in the sidewall surface with nonpolar characteristics, while the donor bound exciton (D0X emission related defects distributed uniformly in the near top polar surface.

  1. Highly selective detection of 2,4,6-trinitrophenol by using newly developed terbium-doped blue carbon dots.

    Science.gov (United States)

    Chen, Bin Bin; Liu, Ze Xi; Zou, Hong Yan; Huang, Cheng Zhi

    2016-04-25

    The detection of nitroaromatic explosives is of great importance owing to their strong explosive power and harmfulness in terms of the environment, homeland security and public safety. Herein, rare earth-doped carbon dots with multifunctional features were firstly prepared by simply keeping the mixture of terbium(iii) nitrate pentahydrate and citric acid at 190 °C for 30 min. The as-prepared terbium doped carbon dots (Tb-CDs), through a rapid and simple direct carbonization route, have a size of about 3 nm, and exhibit excitation wavelength dependent emission of blue fluorescence, are stable, and can be applied for the selective and colorimetric detection of 2,4,6-trinitrophenol (TNP) in the range of 500 nM-100 μM with a limit of detection of 200 nM based on the inner filtering effect (IFE) of the excitation and emission bands of Tb-CDs by TNP and the electron transfer (ET) from Tb-CDs to TNP, giving a precise and highly reproducible result for detecting complex water samples.

  2. Staging superstructures in high-Tc Sr/O co-doped La2-xSrxCuO4+y

    DEFF Research Database (Denmark)

    Ray, P. J.; Andersen, N. H.; Jensen, Thomas Bagger Stibius

    2017-01-01

    We present high-energy x-ray diffraction studies on the structural phases of an optimal high-Tc superconductor La2-xSrxCuO4+y tailored by co-hole-doping. This is specifically done by varying the content of two very different chemical species, Sr and O, respectively, in order to study the influence...

  3. Highly Dispersed Metal Carbide on ZIF-Derived Pyridinic-N-Doped Carbon for CO2Enrichment and Selective Hydrogenation.

    Science.gov (United States)

    Li, Yunhua; Cai, Xiaohu; Chen, Sijing; Zhang, Hua; Zhang, Kevin H L; Hong, Jinqing; Chen, Binghui; Kuo, Dong-Hau; Wang, Wenju

    2018-02-08

    Catalytic conversion of CO 2 into chemicals is a critical issue for energy and environmental research. Among such reactions, converting CO 2 into CO has been regarded as a significant foundation to generate a liquid fuels and chemicals on a large scale. In this work, zeolitic imidazolate framework-derived N-doped carbon-supported metal carbide catalysts (M/ZIF-8-C; M=Ni, Fe, Co and Cu) with highly dispersed metal carbide were prepared for selective CO 2 hydrogenation. Under the same metal loadings, catalytic activity for CO 2 hydrogenation to CO follows the order: Ni/ZIF-8-C≈Fe/ZIF-8-C>Co/ZIF-8-C>Cu/ZIF-8-C. These catalysts are composed of carbide or metal supported on pyridinic N sites within the N-doped carbon structure. ZIF-8-derived pyridinic nitrogen and carbide effect CO 2 adsorption, whereas dispersed Ni or Fe carbide and metal species serve as an active site for CO 2 hydrogenation. The supported Ni catalyst exhibits extraordinary catalytic performance, which results from high dispersion of the metal and exposure of the carbide. Based on high-sensitivity low-energy ion scattering (HS-LEIS) and line scan results, density functional theory (DFT) was used to understand reaction mechanism of selective CO 2 hydrogenation over Ni/ZIF-8-C. The product CO is derived mainly from the direct cleavage of C-O bonds in CO 2 * rather than decomposition of COOH*. The CO* desorption energy on Ni/ZIF-8-C is lower than that for further hydrogenation and dissociation. Comparison of Ni/ZIF-8-C with ZIF-8-C indicates that the combined effects of the highly dispersed metal or carbide and weak CO adsorption result in high CO selectivity for CO 2 hydrogenation. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Megawatt-peak-power picosecond all-fiber-based laser in MOPA using highly Yb3+-doped LMA phosphate fiber

    Science.gov (United States)

    Shi, Guannan; Fu, Shijie; Sheng, Quan; Li, Jinhui; Fang, Qiang; Liu, Huixian; Chavez-Pirson, Arturo; Peyghambarian, N.; Shi, Wei; Yao, Jianquan

    2018-03-01

    A megawatt-peak-power picosecond all-fiber-based laser in master oscillator power amplifier (MOPA) is experimentally demonstrated. Only 34-cm-long highly Yb3+-doped large mode area (LMA) phosphate fiber was used as the gain fiber in the amplification stage to alleviate nonlinearity and achieve high peak power. Picosecond pulses with single pulse energy of 21.2 μJ and peak power of 0.96 MW were achieved at the repetition rate of 500 kHz. Evident spectral degradation can be observed as the peak power approached 1 MW, and a stimulated Raman scattering (SRS) free peak power of 0.51 MW was obtained in the experiment. Moreover, the output power under different repetition rates was investigated.

  5. Ce-doped LuAG single-crystal fibers grown from the melt for high-energy physics

    CERN Document Server

    Xu, X; Moretti, F; Pauwels, K; Lecoq, P; Auffray, E; Dujardin, C

    2014-01-01

    Under a stationary stable regime undoped and Ce-doped LuAG (Lu3Al5O12) single-crystal fibers were grown by a micro-pulling-down technique. The meniscus length corresponding to the equilibrium state was <200 mu m. Fluctuations in the fiber composition and pulling rate were found to have a significant effect on the properties of the fibers grown. A great improvement in the performance was found in samples containing low Ce concentrations (<= 0.1 at.\\%) and produced using pulling rates <0.5 mm min(-1). Under such conditions a good lateral surface fiber quality was obtained and light propagation was significantly improved. Conversely, a high Ce concentration and a high pulling rate resulted in a strong degradation of the fiber surface quality causing defects to appear and a decrease in light output. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  6. Optical Studies at High Pressure on Chromium-Doped Ordered Perovskite Crystals.

    Science.gov (United States)

    Rinzler, Andrew Gabriel

    Pressure dependent luminescence spectra were recorded on the chromium-doped elpasolite crystal Cs_2NaYCl _6:Cr^{3+} at ambient and near liquid nitrogen temperatures in a diamond anvil cell. The broad ^4T_{2g}to ^4A_{2g} fluorescence band of the intrinsically low crystal field compound exhibited a rapid blue shift with increasing pressure. The low temperature measurements yielded enhanced resolution of a ^2E_{g}to ^4A _{2g} phosphorescence appearing at the higher pressures which was interpreted in terms of vibrational modes of the chromium-hexahalide complex. The blue shift of the broad band and the appearance of the structured emission were anticipated by their previous observation in uncorrected luminescence spectra of the chromium doped elpasolites K_2NaGaF_6:Cr ^{3+} and K_2NaScF _6:Cr^{3+}. The spectra of the three crystals were corrected for the spectral response of the corresponding detection system and a transformation was applied to permit interpretation in terms of theoretical lineshape curves. Pressure dependent Raman spectra were recorded on the three crystals. Values of the ratio of the Gruneisen parameter and the bulk modulus were derived for the Raman -active modes. Frequencies of defect modes were determined as a function of pressure in a sample of the K _2NaScF_6:Cr^{3+} crystal with a higher dopant concentration. The photoluminescence lifetime of the chromium -doped chloride elpasolite was measured as a function of temperature, at elevated pressures. The onset of thermal quenching was shifted to higher temperatures with increasing pressure. This behavior was modeled by a pressure dependent activation energy having a rate of change of 1668 +/- 52 cm^{-1}/GPa. Several derivations and calculations were performed. These included: The extraction of pressure-dependent local compressibilities of the chromium-hexahalide complex for the three crystals and the development (within the LCSCC model) of expressions for the pressure derivatives of the effective

  7. Low sintering temperature and high piezoelectric properties of Li-doped (Ba,Ca)(Ti,Zr)O3 lead-free ceramics

    International Nuclear Information System (INIS)

    Chen, Xiaoming; Ruan, Xuezheng; Zhao, Kunyun; He, Xueqing; Zeng, Jiangtao; Li, Yongsheng; Zheng, Liaoying; Park, Chul Hong; Li, Guorong

    2015-01-01

    Highlights: • Li-doped Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 (BCZT) lead-free piezoceramics were prepared by the two-step synthesis and solid-state reaction method. • Their sintering temperature decreases from about 1540 °C down to about 1400 °C. • With the proper addition of Li, the densities and grain sizes of ceramics increase. • The ceramics not only have the characteristics of hard piezoceramics but also possesses the features of soft piezoceramics at low sintering temperature. - Abstract: Li-doped Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 (BCZT) lead-free piezoelectric ceramics were prepared by the two-step synthesis and the solid-state reaction method. The density and grain size of ceramics sufficiently increases by Li-doped sintering aid, and their sintering temperature decreases from about 1540 °C down to about 1400 °C. X-ray diffraction reveals that the phase structure of Li-doped BCTZ ceramics is changed with the sintering temperature, which is consistent with their phase transition observed by the temperature-dependent dielectric curves. The well-poled Li-doped BCZT ceramics show a high piezoelectric constant d 33 (512 pC/N) and a planar electromechanical coupling factor k p (0.49), which have the characteristics of soft Pb(Zr,Ti)O 3 (PZT) piezoceramic, on the other hand, the mechanical quality factor Q m is about 190, which possesses the features of hard PZT piezoceramics. The enhanced properties of the Li-doped BCZT are explained by the combination of Li-doped effect and sintering effect on the microstructure and the phase transition around room temperature

  8. Study of the recrystallization mechanisms of ultra-high purity iron doped with carbon, manganese and phosphorus; Etude des mecanismes de recristallisation dans le fer de ultra-haute purete dope en carbone, manganese et phosphore

    Energy Technology Data Exchange (ETDEWEB)

    Lesne, L.

    2000-07-04

    High purity steels have the potential to improve deep drawing properties for automotive applications. Understanding the influence of the chemical composition on the recrystallization mechanisms and on texture development should help to improve their properties. We have studied the influence of 10 ppm of carbon, 1000 ppm of manganese and 120 ppm of phosphorus on the recrystallization mechanisms of ultra-high purity iron (UHP iron > 99.997%). For this purpose we used 4 materials: one undoped (UHP), one doped with C, one doped with C, Mn and one doped With C, Mn, P. In order to restrict grain coarsening in the hot strips, hot rolling was performed in the ferritic region, in one pass of 80% thickness reduction. The hot bands were then fully recrystallized but exhibited non-isotropic textures, with in particular an intense Goss [110]<001> component for the doped materials. The hot-bands were subsequently cold rolled down to a thickness of 0.8 mm corresponding to a thickness reduction of 80%, and then continuously annealed at 10 deg. C/s. The recrystallization kinetics are delayed with the addition of doping elements. In particular, the incubation time for nucleation is shifted towards higher temperatures while the recrystallization velocity increases. The textures of the fully recrystallized materials exhibit a strong Goss component prejudicial for deep drawing properties. We have established that this component can only appear if coarse grains and carbon in solid solution were simultaneously present in the material before deformation. Characterisation of the cold deformed state enabled us to evaluate the energy stored during deformation as a function of the material composition and the grain orientation: - the overall stored energy increases with the doping elements content. - the stored energy in the {gamma} fibre grains is greater than in the {alpha} fibre grains: 30 J/mol for the {gamma} fibre instead of 5 J/mol for the {alpha} fibre, in the undoped UHP iron. In the

  9. Oxygen doping of the high T/sub c/ superconducting perovskites

    International Nuclear Information System (INIS)

    Tarascon, J.M.; McKinnon, W.R.; Greene, L.H.; Hull, G.W.; Bagley, B.G.; Vogel, E.M.; Le Page, Y.

    1987-01-01

    Oxygen defect perovskites are studied because of their ability to reversibly intercalate oxygen atoms. Our previous studies of the La/sub 2-y/Sr/sub y/CuO/sub 4-x/ system shows that T/sub c/ is dramatically affected by subtle changes in oxygen content. However since this study did not achieve large values of x, a systematic study was not undertaken. The authors have found by thermogravimetric analysis (TGA) that a wide range of oxygen non-stoichiometry in the 90K superconductor YBa/sub 2/Cu/sub 3/O/sub 7-x/ is obtainable. This study of the effect of oxygen doping on the transport properties of the 40K material, and a systematic analysis of this over a broader range in the 90K superconductor is presented

  10. High-mobility transparent conductive thin films of cerium-doped hydrogenated indium oxide

    Science.gov (United States)

    Kobayashi, Eiji; Watabe, Yoshimi; Yamamoto, Tetsuya

    2015-01-01

    We have developed 100-nm-thick cerium-doped hydrogenated indium oxide (ICO:H) films with a superior Hall mobility of 130-145 cm2 V-1 s-1. The ICO:H films deposited at 150 °C by dc arc-discharge ion plating were post-annealed at 200 °C. The relationship between the Hall mobility and carrier density of the polycrystalline ICO:H films shows that the carrier transport is limited by an ionized impurity scattering mechanism inside the grains. The surfaces of the ICO:H films were found to be very smooth and clear grain-boundary areas were not observed.

  11. HIGH TEMPERATURE RESONANCE LOSSES IN SILICON-DOPED YTTRIUM-IRON GARNET (YIG)

    DEFF Research Database (Denmark)

    Epstein, D. J.; Tocci, L.

    1967-01-01

    for the electron ordering energy a value 5 × 10-4 eV which agrees closely with the energy deduced from magnetic anneal studies. The activation energy for electron transfer (0.25 eV) is virtually identical with values reported in investigations of electrical conductivity and acoustic loss. ©1967 The American......The ferrimagnetic resonance linewidth of silicon-doped YIG, measured as a function of temperature at 13.4 kMHz, is found to show a pronounced peak at 105°C. The anisotropic behavior of this peak is in good agreement with the four-level valence-exchange model proposed by Clogston. The model yields...

  12. Transverse mode instability in high-power ytterbium doped fiber ampliers

    DEFF Research Database (Denmark)

    Hansen, Kristian Rymann

    the otherwise nearly diffraction-limited beam quality of fiber amplifiers, was discovered. The latter effect has impeded the further power scaling of fiber lasers, since the mode instability sets in when the average power exceeds a certain threshold. The purpose of the research presented in this thesis...... based on the beam propagation method, and the second is by a formulation of a coupled-mode model of thermally induced mode instability. The former approach is used to study the effect of quantum defect heating on the guiding properties of the fiber, while the latter provides a simplified description......The last couple of decades have brought an impressive growth in the output power of rare-earth doped fiber lasers and amplifiers, reaching the kW average power regime in both CW and pulsed systems. As a result, even though fiber lasers have excellent heat dissipation properties, thermal effects due...

  13. A high-performance broadband terahertz absorber based on sawtooth-shape doped-silicon

    Directory of Open Access Journals (Sweden)

    Liang-Hui Du

    2016-05-01

    Full Text Available Perfect absorbers with broadband absorption of terahertz (THz radiation are promising for applications in imaging and detection to enhance the contrast and sensitivity, as well as to provide concealment. Different from previous two-dimensional structures, here we put forward a new type of THz absorber based on sawtooth-shape doped-silicon with near-unit absorption across a broad spectral range. Absorbance over 99% is observed numerically from 1.2 to 3 THz by optimizing the geometric parameters of the sawtooth structure. Our absorbers can operate over a wide range of incident angle and are polarization insensitive. The underlying mechanisms due to the combination of an air-cavity mode and mode-matching resonance on the air-sawtooth interface are analyzed in terms of the field patterns and electromagnetic power loss features.

  14. 1-MHz high power femtosecond Yb-doped fiber chirped-pulse amplifier

    Science.gov (United States)

    Hu, Zhong-Qi; Yang, Pei-Long; Teng, Hao; Zhu, Jiang-Feng; Wei, Zhi-Yi

    2018-01-01

    A practical femtosecond polarization-maintaining Yb-doped fiber amplifier enabling 153 fs transform-limited pulse duration with 32 μJ pulse energy at 1 MHz repetition rate corresponding to a peak power of 0.21 GW is demonstrated. The laser system based on chirped-pulse amplification (CPA) technique is seeded by a dispersion managed, nonlinear polarization evolution (NPE) mode-locked oscillator with spectrum bandwidth of 31 nm at 1040 nm and amplified by three fiber pre-amplifying stages and a rod type fiber main amplifying stage. The laser works with beam quality of M2 of 1.3 and power stability of 0.63% (root mean square, RMS) over 24 hours will be stable sources for industrial micromachining, medical therapy and scientific research.

  15. Ag{sup II} doped MIL-101 and its adsorption of iodine with high speed in solution

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Ping; Qi, Bingbing; Liu, Ying [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Zhao, Lei [Lianyungang Institute of Nanjing University of Science and Technology, Lianyungang 222006 (China); Jiao, Yan [Jiangsu Engineering Technology Research Center of Environmental Cleaning Materials (CEM), School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology (China); Zhang, Yi; Jiang, Zheng; Li, Qiang [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Wang, Jinfeng [Nanjing Chemical Industries Co., Ltd., SINOPEC, Nanjing 210048 (China); Chen, Shouwen [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Yi, E-mail: yyi301@163.com [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2016-05-15

    In order to improve the adsorption speed of iodine from water, MIL-101 with extra-large specific surface area (3054 m{sup 2}/g) was chosen as a base material, and then, Ag was doped into MIL-101 to enhance its adsorption capacity through an incipient-wetness impregnation method. With the characterization of SEM-EDS, TEM, XRD, XPS, TGA, IR, and BET techniques, the resulting Ag was identified to be stay in the framework of MIL-101 stably in the form of Ag{sup II} (generally, Ag{sup II} cation is not stable). However, after the adsorption of I{sup −} anions, Ag{sup II} stay in the cages of MIL-101 in the form of AgI/AgI{sub 3}. It is important to note that, all adsorbents show high adsorption speed of iodine in solution. The equilibrium adsorption time of the adsorbents were acquired by only a few minutes, which can be attributed to its large BET surface area. An interesting note is that, when the doping amount of Ag is less than 9%, the iodine anions adsorption capacity of Ag@MIL-101 is greater than its theoretical adsorption capacity. It shows that both physical adsorption and chemical adsorption are existed in the adsorption process. This study hopefully leads to a new and highly efficient Ag-based adsorbent for iodide adsorb from solutions. - Graphical abstract: Ag{sup II} stay in the framework of MIL-101 stably because of F{sup -}, after the adsorption of I{sup -} anions, Ag{sup I}I /Ag{sup I}I{sub 3} stay in the cages of MIL-101. The equilibrium adsorption time of Ag@MIL-101 were acquired by only a few minutes. - Highlights: • Ag{sup II} was doped into MIL-101 by an incipient-wetness impregnation method. • Both physical adsorption and chemical adsorption are verified in the adsorption process. • Ag@MIL-101 exhibits high adsorption speed and adsorption capacity. • Ag@MIL-101 can be effectively applied to the removal of radioactive iodide anions from water in acidic and neutral medium.

  16. A high-performance doped photocatalysts for inactivation of total coliforms in superficial waters using different sources of radiation.

    Science.gov (United States)

    Claro, Elis Marina Turini; Bidoia, Ederio Dino; de Moraes, Peterson Bueno

    2016-07-15

    Photocatalytic water treatment has a currently elevated electricity demand and maintenance costs, but the photocatalytic water treatment may also assist in overcoming the limitations and drawbacks of conventional water treatment processes. Among the Advanced Oxidation Processes, heterogeneous photocatalysis is one of the most widely and efficiently used processes to degrade and/or remove a wide range of polluting compounds. The goal of this work was to find out a highly efficient photocatalytic disinfection process in superficial water with different doped photocatalysts and using three sources of radiation: mercury vapor lamp, solar simulator and UV-A LED. Three doped photocatalysts were prepared, SiZnO, NSiZnO and FNSiZnO. The inactivation efficiency of each synthesized photocatalysts was compared to a TiO2 P25 (Degussa(®)) 0.5 g L(-1) control. Photolysis inactivation efficiency was 85% with UV-A LED, which is considered very high, demanding low electricity consumption in the process, whereas mercury vapor lamp and solar simulator yielded 19% and 13% inactivation efficiency, respectively. The best conditions were found with photocatalysts SiZnO, FNSiZnO and NSiZnO irradiated with UV-A LED, where efficiency exceeded 95% that matched inactivation of coliforms using the same irradiation and photocatalyst TiO2. All photocatalysts showed photocatalytic activity with all three radiation sources able to inactivate total coliforms from river water. The use of UV-A LED as the light source without photocatalyst is very promising, allowing the creation of cost-effective and highly efficient water treatment plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Facile Synthesis of Highly Water-Soluble Lanthanide-Doped t-LaVO4 NPs for Antifake Ink and Latent Fingermark Detection

    KAUST Repository

    Chen, Cailing

    2017-11-08

    In the information age, it is important to protect the security and integrity of the information. As a result, the fluorescent ink as an antifake technology and the fingermark as an information carrier have aroused great interest. In this work, highly water-soluble lanthanide (Ln3+ )-doped tetragonal phase (t-) LaVO4 nanoparticles (NPs) are successfully obtained via a simple, fast, and green microwave-assisted hydrothermal method. The average size of t-LaVO4 NPs is about 43 nm. The aqueous solutions of Ln3+ -doped t-LaVO4 exhibit excellent fluorescence properties under ultraviolet light (UV) excitation (t-LaVO4 :10%Eu is bright red and t-LaVO4 :0.5%Dy is close to white). Some superb antifake fluorescent patterns are printed using Ln3+ -doped t-LaVO4 aqueous solution as ink, which indicates the as-prepared Ln3+ -doped t-LaVO4 NPs as fluorescent ink can meet the various antifake requirements. Notably, the designed convenient antifake fluorescent codes with improved security could be directly scanned and decoded by a smart phone. What\\'s more, the as-prepared NPs can be used for the development of latent fingermark on various substrates and the second-level detail information can be clearly obtained from the magnification of a fingermark. These results indicate that the as-prepared Ln3+ -doped t-LaVO4 fluorescent NPs have great potential in security application.

  18. Synthesis, characterization and degradation of Bisphenol A using Pr, N co-doped TiO 2 with highly visible light activity

    Science.gov (United States)

    Yang, Juan; Dai, Jun; Li, Jiantong

    2011-08-01

    Praseodymium and nitrogen co-doped titania (Pr/N-TiO 2) photocatalysts, which could degrade Bisphenol A (BPA) under visible light irradiation, were prepared by the modified sol-gel process. Tetrabutyl titanate, urea and praseodymium nitrate were used as the sources of titanium, nitrogen and praseodymium, respectively. The resulting materials were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), UV-vis absorbance spectroscopy, X-ray photoelectron spectroscopy (XPS), N 2 adsorption-desorption isotherm and Fourier transform infrared spectra (FTIR). It was found that Pr doping inhibited the growth of crystalline size and the transformation from anatase to rutile. The degradation of BPA under visible light illumination was taken as probe reaction to evaluate the photo-activity of the co-doped photocatalyst. In our experiments, the optimal dopant amount of Pr was 1.2 mol% and the calcination temperature was 500 °C for the best photocatalytic activity. Pr/N-TiO 2 samples exhibited enhanced visible-light photocatalytic activity compared to N-TiO 2, undoped TiO 2 and commercial P25. The nitrogen atoms were incorporated into the crystal of titania and could narrow the band gap energy. Pr doping could slow the radiative recombination of photogenerated electrons and holes in TiO 2. The improvement of photocatalytic activity was ascribed to the synergistic effects of nitrogen and Pr co-doping.

  19. Template-free synthesis of three-dimensional nanoporous N-doped graphene for high performance fuel cell oxygen reduction reaction in alkaline media

    International Nuclear Information System (INIS)

    Tang, Sheng; Zhou, Xuejun; Xu, Nengneng; Bai, Zhengyu; Qiao, Jinli; Zhang, Jiujun

    2016-01-01

    Highlights: • 3-D porous N-doped graphene was prepared using one-step silica template-free method. • High specific surface area of 920 m 2 g −1 was achieved for 3-D porous N-doped graphene. • Much higher ORR activity was observed for N-doped graphene than S-doped one in 0.1 M KOH. • The as-prepared catalyst gave a peak power density of 275 mW cm −2 as zinc–air battery cathode. - Abstract: Three-dimensional nanoporous nitrogen-doped graphene (3D-PNG) has been synthesized through a facial one-step synthesis method without additional silica template. The as-prepared 3D-PNGwas used as an electrocatalyst for the oxygen reduction reaction (ORR), which shows excellent electrochemistry performance, demonstrated by half-cell electrochemical evaluation in 0.1 M KOH including prominent ORR activity, four electron-selectivity and remarkable methanol poisoning stability compared to commercial 20%Pt/C catalyst. The physical and surface properties of 3D-PNG catalyst were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and BET surface area analysis. The experiments show that 3D-PNG catalyst possesses super-large specific surface area reaching 920 m 2 g −1 , which is superior to our most recently reported 3D-PNG synthesized by silica template (670 m 2 g −1 ) and other doped graphene catalysts in literature. When used for constructing a zinc–air battery cathode, such an 3D-PNG catalyst can give a discharge peak power density of 275 mW cm −2 . All the results announce a unique procedure to product high-efficiency graphene-based non-noble metal catalyst materials for electrochemical energy devices including both fuel cells and metal–air batteries.

  20. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction

    OpenAIRE

    Cramer, A.J.; Cole, J.M.; FitzGerald, V.; Honkimaki, V.; Roberts, M.A.; Brennan, T.; Martin, R.A.; Saunders, G.A.; Newport, Robert J.

    2013-01-01

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3) x(R�2O3)y(P2O 5)1-(x+y), where (R, R�) denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP 5O14. Thereupon, the effects of rare-earth co-dopin...

  1. Development of Nano-crystalline Doped-Ceramic Enabled Fiber Sensors for High Temperature In-Situ Monitoring of Fossil Fuel Gases

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Hai [Missouri Univ. of Science and Technology, Rolla, MO (United States); Dong, Junhang [Univ. of Cincinnati, OH (United States); Lin, Jerry [Arizona State Univ., Tempe, AZ (United States); Romero, Van [New Mexico Institute of Mining and Technology, Socorro, NM (United States)

    2012-03-01

    This is a final technical report for the first project year from July 1, 2005 to Jan 31, 2012 for DoE/NETL funded project DE-FC26-05NT42439: Development of Nanocrystalline Doped-Ceramic Enabled Fiber Sensors for High Temperature In-Situ Monitoring of Fossil Fuel Gases. This report summarizes the technical progresses and achievements towards the development of novel nanocrystalline doped ceramic material-enabled optical fiber sensors for in situ and real time monitoring the gas composition of flue or hot gas streams involved in fossil-fuel based power generation and hydrogen production.

  2. 1018 nm Yb-doped high-power fiber laser pumped by broadband pump sources around 915 nm with output power above 100 W

    DEFF Research Database (Denmark)

    Midilli, Yakup; Efunbajo, Oyewole Benjamin; Şimşek, Bartu

    2017-01-01

    We demonstrate a 1018 nm ytterbium-doped all-fiber laser pumped by tunable pump sources operating in the broad absorption spectrum around 915 nm. In the experiment, two different pump diodes were tested to pump over a wide spectrum ranging from 904 to 924 nm by altering the cooling temperature...... of the pump diodes. Across this so-called pump wavelength regime having a 20 nm wavelength span, the amplified stimulated emission (ASE) suppression of the resulting laser was generally around 35 dB, showing good suppression ratio. Comparisons to the conventional 976 nm-pumped 1018 nm ytterbium-doped fiber...... laser were also addressed in this study. Finally, we have tested this system for high power experimentation and obtained 67% maximum optical-to-optical efficiency at an approximately 110 W output power level. To the best of our knowledge, this is the first 1018 nm ytterbium-doped all-fiber laser pumped...

  3. Morphology-controlled synthesis and novel microwave electromagnetic properties of hollow urchin-like chain Fe-doped MnO 2 under 10 T high magnetic field

    Science.gov (United States)

    Yuping, Duan; Jia, Zhang; Hui, Jing; Shunhua, Liu

    2011-05-01

    Fe-doped MnO 2 with a hollow sea urchin-like ball chain shape was first synthesized under a high magnetic field of 10 T. The formation mechanism was investigated and discussed in detail. The synthesized samples were characterized by XRD, SEM, TEM, EMPA, and vector network analysis. By doping MnO 2 with Fe, the relative complex permittivity of MnO 2 and its corresponding loss tangent clearly decreases, but its relative complex permeability and its corresponding loss tangent markedly increases. Moreover, the theoretically calculated values of reflection loss show that with increasing the Fe content, the as-prepared Fe-doped MnO 2 exhibits good microwave absorption capability.

  4. Enhanced High-Temperature Cyclic Stability of Al-Doped Manganese Dioxide and Morphology Evolution Study Through in situ NMR under High Magnetic Field.

    Science.gov (United States)

    Huang, Shenggen; Sun, Jian; Yan, Jian; Liu, Jiaqin; Wang, Weijie; Qin, Qingqing; Mao, Wenping; Xu, Wei; Wu, Yucheng; Wang, Junfeng

    2018-03-21

    In this work, Al-doped MnO 2 (Al-MO) nanoparticles have been synthesized by a simple chemical method with the aim to enhance cycling stability. At room temperature and 50 °C, the specific capacitances of Al-MO are well-maintained after 10 000 cycles. Compared with pure MnO 2 nanospheres (180.6 F g -1 at 1 A g -1 ), Al-MO also delivers an enhanced specific capacitance of 264.6 F g -1 at 1 A g -1 . During the cycling test, Al-MO exhibited relatively stable structure initially and transformed to needlelike structures finally both at room temperature and high temperature. In order to reveal the morphology evolution process, in situ NMR under high magnetic field has been carried out to probe the dynamics of structural properties. The 23 Na spectra and the SEM observation suggest that the morphology evolution may follow pulverization/reassembling process. The Na + intercalation/deintercalation induced pulverization, leading to the formation of tiny MnO 2 nanoparticles. After that, the pulverized tiny nanoparticles reassembled into new structures. In Al-MO electrodes, doping of Al 3+ could slow down this structure evolution process, resulting in a better electrochemical stability. This work deepens the understanding on the structural changes in faradic reaction of pseudocapacitive materials. It is also important for the practical applications of MnO 2 -based supercapacitors.

  5. La-doped Al2O3 supported Au nanoparticles: highly active and selective catalysts for PROX under PEMFC operation conditions.

    Science.gov (United States)

    Lin, Qingquan; Qiao, Botao; Huang, Yanqiang; Li, Lin; Lin, Jian; Liu, Xiao Yan; Wang, Aiqin; Li, Wen-Cui; Zhang, Tao

    2014-03-14

    La-doped γ-Al2O3 supported Au catalysts show high activity and selectivity for the PROX reaction under PEMFC operation conditions. The superior performance is attributed to the formation of LaAlO3, which suppresses H2 oxidation and strengthens CO adsorption on Au sites, thereby improving competitive oxidation of CO at elevated temperature.

  6. Generic sample preparation combined with high-resolution liquid chromatography- time-of-flight mass spectrometry for unification of urine screening in doping-control laboratories

    NARCIS (Netherlands)

    Peters, R.J.B.; Oosterink, J.E.; Stolker, A.A.M.; Georgakopoulos, C.G.; Nielen, M.W.F.

    2010-01-01

    A unification of doping-control screening procedures of prohibited small molecule substances—including stimulants, narcotics, steroids, ß2-agonists and diuretics—is highly urgent in order to free resources for new classes such as banned proteins. Conceptually this may be achieved by the use of a

  7. High-performance thermal sensitive W-doped VO{sub 2}(B) thin film and its identification by first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Dongyun; Xiong, Ping; Chen, Lanli [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Shi, Siqi, E-mail: sqshi@shu.edu.cn [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Ishaq, Ahmad [National Center for Physics, Quaid-I-Azam University, Islamabad 44000 (Pakistan); Luo, Hongjie [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Gao, Yanfeng, E-mail: yfgao@shu.edu.cn [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China)

    2017-03-01

    Graphical abstract: VO{sub 2}(B) thin films with high TCR and suitable resistance were first achieved by W doping. The mechanism for performance improvement was studied by first-principles calculations. The two-dimensional octahedral structure of VO{sub 2}(B) favors the strain control with W-doping for achieving a large TCR, which overcomes the contradiction between the high conductivity and large TCR generated by dopants in VO{sub 2}(M). - Highlights: • High performance W-doped VO{sub 2}(B) thin films were first achieved by co-sputtering. • Mechanism for performance improvement was studied by first-principles calculations. • The two-dimensional octahedral structure of VO{sub 2} (B) favors the strain control. • Achieved VO{sub 2} films possess high thermal sensitivity (TCR: −3.9%/K & R{sub 0}: 32.7 kΩ). - Abstract: VO{sub 2}(B) is currently a preferred phase structure for the application as bolometer material, which, however, suffers from low temperature-coefficient-of-resistance (TCR) values and large resistances. Here we present the combined experimental and first-principles calculations study on both doped and undoped VO{sub 2}(B) thin films enabling us to attain high TCR (−3.9%/k) and suitable square-resistance (32.7 kΩ) by controlled W doping employing the widely used magnetron sputtering technique. The TCR value is 50% larger than reported ones at the similar resistance. The underlying microscopic mechanism for the performance improvement was studied and results indicated that the introduction of extra electrons and the variation in the band structure resulting from the incorporation of W{sup 6+} ions in the VO{sub 2}(B) crystal lattice contribute to the enhancement of the electronic conductivity. Moreover, the special two-dimensional octahedral structure of monoclinic (C2/m) B-phase VO{sub 2} favors the strain control with W-doping for achieving a large TCR, which overcomes the analogous predicament between the high conductivity and large TCR

  8. Highly sensitive room temperature ammonia gas sensor based on Ir-doped Pt porous ceramic electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenlong [College of pharmacy and biological engineering, Chengdu University, Chengdu, 610106 (China); Department of chemical and materials engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan (China); Liu, Yen-Yu [Department of chemical and materials engineering, Tunghai University, Taichung 407, Taiwan (China); Do, Jing-Shan, E-mail: jsdo@ncut.edu.tw [Department of chemical and materials engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan (China); Li, Jing, E-mail: lijing@cdu.edu.cn [College of pharmacy and biological engineering, Chengdu University, Chengdu, 610106 (China)

    2016-12-30

    Highlights: • Water vapors seem to hugely improve the electrochemical activity of the Pt and Pt-Ir porous ceramic electrodes. • The gas sensors based on the Pt and Pt-Ir alloy electrodes possess good sensing performances. • The reaction path of the ammonia on platinum has been discussed. - Abstract: Room temperature NH{sub 3} gas sensors based on Pt and Pt-Ir (Ir doping Pt) porous ceramic electrodes have been fabricated by both electroplating and sputtering methods. The properties of the gaseous ammonia sensors have been examined by polarization and chronoamperometry techniques. The influence of humidity on the features of the resulting sensors in the system has also been discussed, and the working potential was optimized. Water vapors seem to hugely improve the electrochemical activity of the electrode. With increasing the relative humidity, the response of the Pt-Ir(E)/Pt(S)/PCP sensor to NH{sub 3} gas could be enhanced remarkably, and the sensitivity increases from 1.14 to 12.06 μA ppm{sup −1} cm{sup −2} .Then we have also discussed the sensing mechanism of the Pt-Ir sensor and the result has been confirmed by X-ray photoelectron spectroscopy of the electrode surface before and after reaction in the end.

  9. High quality factor Er-doped Fabry-Perot microcavities by sol-gel processing

    Energy Technology Data Exchange (ETDEWEB)

    Li Yigang; Fortes, Luis M; Almeida, Rui M [Departamento de Engenharia de Materiais/ICEMS, Instituto Superior Tecnico/TULisbon, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Chiappini, Andrea; Ferrari, Maurizio, E-mail: yigang.li@ist.utl.p, E-mail: rui.almeida@ist.utl.p [CNR-IFN, Istituto di Fotonica e Nanotecnologie, CSMFO Lab., Via alla Cascata 56/C, Povo, 38123 Trento (Italy)

    2009-10-21

    An optimized sol-gel process was developed to fabricate 1D photonic bandgap structures. Several erbium-doped Fabry-Perot microcavities were prepared and characterized. The thickest sample contained two Bragg mirrors, each having 12 distributed Bragg reflector periods of alternating silicate glass and titania layers. The total thickness of this sample reached {approx}12 {mu}m. The Er{sup 3+} photoluminescence spectra at 1.5 {mu}m were measured for the microcavities. A quality factor of 250 and an Er{sup 3+} photoluminescence enhancement of 96 times at 1.5 {mu}m have been reached. The sol-gel processing details, the crystallization of the titania films and the refractive index of the deposited materials are discussed in detail. The simulated optical spectra of the microcavities were found to agree well with the actually measured curves. These results demonstrate that the present sol-gel processing technique is of potential interest for low cost fabrication of 1D photonic bandgap devices.

  10. Highly nitrogen and boron doped nanotubes: a route to synthesis and study of their properties by spatially resolved EELS

    Science.gov (United States)

    Loiseau, Annick

    2005-03-01

    Doping C-nanotubes with B and/or N is expected to be a particular interesting way for tuning electronic and mechanical properties. BN nanotubes are predicted to behave as insulators whereas B(N) doped C-nanotubes are expected to be metallic, independent of their structure. In this framework, we have developped, both at Onera and GDPC, original routes to the synthesis of BN singlewall nanotubes (BN-SWNTs) and to highly doped nitrogen multi wall nanotubes (CNx-MWNTs). CNx-MWNTs were produced by a CVD method, using an aerosol injector which sprays in the reactor, heated at 950 C, a liquid mixture of organic compounds with a controlled N/C ratio and suitable metal complexes as the catalyst precursors^1. This procedure leads to dense amounts of MWNTs with controlled N/C ratios which can exceed 15-20% in average. Upon doping, tubes get a characteristic compartimentalized structure with a reduced number of layers identified in transmission electron microscopy. Using spatially resolved electron energy loss spectroscopy (EELS), N is found to be preferentially localized in inner layers and in the compartiments where the concentration can exceed 40 at.%. Structure of core losses in EELS reveals a high dependance of the N environment to the local concentration :chemical bonding of N can be graphitic, pyridinic or pyrrolic, this latter case being found for highest N concentrations. Relationships between these structural properties and formation mechanism will be discussed^2. BN-SWNTs are issued from the vaporization of a BN target by a continuous CO2 laser under a N2 atmosphere^3. We present here the first investigation on their electronic properties by two ways: first, analysis of the dielectric response of low loss EELS recorded on individual tubes provides the first identification of plasmons and of interband transitions in these tubes and the first measure of their gap found to be close to 5.8eV^4. Second, optical absorption spectra measured on macroscopic samples strongly

  11. Nitrogen-doped two-dimensional porous carbon sheets derived from clover biomass for high performance supercapacitors

    Science.gov (United States)

    Wang, Cunjing; Wu, Dapeng; Wang, Hongju; Gao, Zhiyong; Xu, Fang; Jiang, Kai

    2017-09-01

    Highly porous carbon sheets were prepared from fresh clover stems under air atmosphere via a facile potassium chloride salt-sealing technique, which not only avoids using the high cost inert gas protection but also spontaneously introduce multi-level porosity into the carbon structure taking advantage of the trace of oxygen in the molten salt system. The as-obtained porous carbon sheets possess high specific surface area of 2244 m2 g-1 and interconnected hierarchical pore structures from micro-to macro-scale, which provide abundant storage active sites and fast ion diffusion channels. In addition, the spontaneously formed N (2.55 at%) and O (6.94 at%) doping sites not only improve the electron conductivity of the electrode but also enhance the specific capacitance by introducing pseudocapacitance. When employed as supercapacitor electrodes, a high specific capacitance of 436 F g-1 at 1 A g-1 and an excellent rate capacity with capacitance remaining 290 F g-1 at 50 A g-1 are demonstrated. Furthermore, the assembled symmetric supercapacitor delivers a high specific capacitance of 420 F g-1 at 0.5 A g-1, excellent energy density of 58.4 Wh kg-1 and good cycling stability which retains 99.4% of the initial capacitance at 5 A g-1 after 30,000 cycles.

  12. High mobility La-doped BaSnO3 on non-perovskite MgO substrate

    Science.gov (United States)

    Kim, Youjung; Shin, Juyeon; Kim, Young Mo; Char, Kookrin

    (Ba,La)SnO3 is a transparent perovskite oxide with high electron mobility and excellent oxygen stability. Field effect device with (Ba,La)SnO3 channel was reported to show good output characteristics on STO substrate. Here, we fabricated (Ba,La)SnO3\\ films and field effect devices with (Ba,La)SnO3 channel on non-perovskite MgO substrates, which are available in large size wafers. X-ray diffraction and transmission electron microscope (TEM) images of (Ba,La)SnO3\\ films on MgO substrates show that the films are epitaxial with many threading dislocations. (Ba,La)SnO3 exhibits the high mobility with 97.2 cm2/Vs at 2 % La doping on top of 150 nm thick BaSnO3 buffer layer. Excellent carrier modulation was observed in field effect devices. FET performances on MgO substrates are slightly better than those on SrTiO3 substrates in spite of the higher dislocation density on MgO than on SrTiO3 substrates. These high mobility BaSnO3 thin films and transistors on MgO substrates will accelerate development for applications in high temperature and high power electronics. Samsung Science and Technology Foundation.

  13. A highly efficient electrocatalyst for oxygen reduction reaction: phosphorus and nitrogen co-doped hierarchically ordered porous carbon derived from an iron-functionalized polymer

    Science.gov (United States)

    Deng, Chengwei; Zhong, Hexiang; Li, Xianfeng; Yao, Lan; Zhang, Huamin

    2016-01-01

    Heteroatom-doped carbon materials have shown respectable activity for the oxygen reduction reaction (ORR) in alkaline media. However, the performances of these materials are not satisfactory for energy conversion devices, such as fuel cells. Here, we demonstrate a new type of phosphorus and nitrogen co-doped hierarchically ordered porous carbon (PNHOPC) derived from an iron-functionalized mesoporous polymer through an evaporation-induced self-assembly process that simultaneously combines the carbonization and nitrogen doping processes. The soft template and the nitrogen doping process facilitate the formation of the hierarchically ordered structure for the PNHOPC. The catalyst possesses a large surface area (1118 cm2 g-1) and a pore volume of 1.14 cm3 g-1. Notably, it exhibits excellent ORR catalytic performance, superior stability and methanol tolerance in acidic electrolytes, thus making the catalyst promising for fuel cells. The correlations between the unique pore structure and the nitrogen and phosphorus configuration of the catalysts with high catalytic activity are thoroughly investigated.Heteroatom-doped carbon materials have shown respectable activity for the oxygen reduction reaction (ORR) in alkaline media. However, the performances of these materials are not satisfactory for energy conversion devices, such as fuel cells. Here, we demonstrate a new type of phosphorus and nitrogen co-doped hierarchically ordered porous carbon (PNHOPC) derived from an iron-functionalized mesoporous polymer through an evaporation-induced self-assembly process that simultaneously combines the carbonization and nitrogen doping processes. The soft template and the nitrogen doping process facilitate the formation of the hierarchically ordered structure for the PNHOPC. The catalyst possesses a large surface area (1118 cm2 g-1) and a pore volume of 1.14 cm3 g-1. Notably, it exhibits excellent ORR catalytic performance, superior stability and methanol tolerance in acidic

  14. Biomass-Derived Oxygen and Nitrogen Co-Doped Porous Carbon with Hierarchical Architecture as Sulfur Hosts for High-Performance Lithium/Sulfur Batteries.

    Science.gov (United States)

    Zhao, Yan; Wang, Li; Huang, Lanyan; Maximov, Maxim Yu; Jin, Mingliang; Zhang, Yongguang; Wang, Xin; Zhou, Guofu

    2017-11-21

    In this work, a facile strategy to synthesize oxygen and nitrogen co-doped porous carbon (ONPC) is reported by one-step pyrolysis of waste coffee grounds. As-prepared ONPC possesses highly rich micro/mesopores as well as abundant oxygen and nitrogen co-doping, which is applied to sulfur hosts as lithium/sulfur batteries' appropriate cathodes. In battery testing, the sulfur/oxygen and nitrogen co-doped porous carbon (S/ONPC) composite materials reveal a high initial capacity of 1150 mAh·g -1 as well as a reversible capacity of 613 mAh·g -1 after the 100th cycle at 0.2 C. Furthermore, when current density increases to 1 C, a discharge capacity of 331 mAh·g -1 is still attainable. Due to the hierarchical porous framework and oxygen/nitrogen co-doping, the S/ONPC composite exhibits a high utilization of sulfur and good electrochemical performance via the immobilization of the polysulfides through strong chemical binding.

  15. Biomass-Derived Oxygen and Nitrogen Co-Doped Porous Carbon with Hierarchical Architecture as Sulfur Hosts for High-Performance Lithium/Sulfur Batteries

    Directory of Open Access Journals (Sweden)

    Yan Zhao

    2017-11-01

    Full Text Available In this work, a facile strategy to synthesize oxygen and nitrogen co-doped porous carbon (ONPC is reported by one-step pyrolysis of waste coffee grounds. As-prepared ONPC possesses highly rich micro/mesopores as well as abundant oxygen and nitrogen co-doping, which is applied to sulfur hosts as lithium/sulfur batteries’ appropriate cathodes. In battery testing, the sulfur/oxygen and nitrogen co-doped porous carbon (S/ONPC composite materials reveal a high initial capacity of 1150 mAh·g−1 as well as a reversible capacity of 613 mAh·g−1 after the 100th cycle at 0.2 C. Furthermore, when current density increases to 1 C, a discharge capacity of 331 mAh·g−1 is still attainable. Due to the hierarchical porous framework and oxygen/nitrogen co-doping, the S/ONPC composite exhibits a high utilization of sulfur and good electrochemical performance via the immobilization of the polysulfides through strong chemical binding.

  16. Lowell Observatory's 24-inch Clark Refractor: Its History and Renovation

    Science.gov (United States)

    Schindler, Kevin; Nye, Ralph; Rosenthal, Peter

    2016-01-01

    In 1895, Percival Lowell hired eminent telescope maker Alvan G. Clark to build a 24-inch refractor. Lowell intended the telescope intitally for observing Mars in support of his controversial theories about life on that planet. Clark finished the telescope within a year and at a cost of $20,000. Lowell and his staff of assistants and astronomers began observing through it on July 23, 1896, setting off a long and productive career for the telescope.While Lowell's Mars studies dominated early work with the Clark, V.M. Slipher by the 1910s was using it to observe planetary rotations and atmospheric compositions. He soon revolutionized spectroscopic studies, gathering excruciatingly long spectra - some in excess of 40 hours - of the so-called white nebula and determining startling radial velocities, evidence of an expanding universe. In the 1960s, scientists and artists teamed up on the Clark and created detailed lunar maps in support of the Apollo program.In recent decades, the Clark has played a central role in the education programs at Lowell, with general public audiences, students, and private groups all taking advantage of this unique resource.With this nearly 120 years of contant use, the Clark had been wearing down in recent years. The telescope was becoming more difficult to move, old electrical wiring in the dome was a fire hazard, and many of the telescope's parts needed to be repaired or replaced.In 2013, Lowell Observatory began a fundraising campaign, collecting $291,000 to cover the cost of dome and telescope renovation. Workers removed the entire telescope mount and tube assembly from the dome, examining every part from tube sections to individuals screws. They also stabilized the dome, adding a water vapor barrier and new outer wall while reinforcing the upper dome. The project lasted from January, 2014 through August, 2015. The facility reopened for daytime tours in September, 2015 and evening viewing the following month.

  17. Anomalous behavior of B{sub 1g} mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, Subodh K., E-mail: subodhkgtm@gmail.com, E-mail: fouran@gmail.com; Ojha, S.; Singh, Fouran, E-mail: subodhkgtm@gmail.com, E-mail: fouran@gmail.com [Material Science Group, Inter University Accelerator Centre, New Delhi -110067 (India); Gautam, Naina [Department of Electronic Science, University of Delhi South Campus, New Delhi - 110023 (India); Singh, R. G. [Department of Physics, Bhagini Nivedita College, Delhi University, Delhi– 110043 (India); Shukla, D. K. [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017 (India)

    2015-12-15

    The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO) thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO{sub 2} lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb{sup +5} in the TiO{sub 2} lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR) spectra of films with small size crystallites shows stiffening of about 4 cm{sup −1} for the E{sub g(1)} mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B{sub 1g} mode exhibits a large anomalous softening of 20 cm{sup −1} with asymmetrical broadening; which was not reported for the case of pure TiO{sub 2} crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb{sup 5+} doping induced reduction of Ti{sup 4+} ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS) and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

  18. Erbium and nitrogen co-doped SrTiO3 with highly visible light photocatalytic activity and stability by solvothermal synthesis

    International Nuclear Information System (INIS)

    Xu, Jing; Wei, Yuelin; Huang, Yunfang; Wang, Jing; Zheng, Xuanqing; Sun, Zhixian; Wu, Ying; Tao, Xinling; Fan, Leqing; Wu, Jihuai

    2015-01-01

    Highlights: • Er/N co-doped SrTiO 3 was prepared by a solvothermal process at low temperature. • The co-doping induces the band gap narrowing and prominent absorbance in visible light region. • The samples show excellent catalytic activity and stability under visible light irradiation. - Abstract: Erbium–nitrogen co-doped SrTiO 3 photocatalysts have been synthesized by a facile solvothermal method. The resulting samples were analyzed by FE-SEM, XRD, BET-surface area and UV–vis. The UV–vis absorption spectra of these powders indicated that erbium–nitrogen co-doped SrTiO 3 possessed stronger absorption bands in the visible light region in comparison with that of pure SrTiO 3 . The occurrence of the erbium–nitrogen co-doped cubic SrTiO 3 induced the higher photocatalytic activities for the degradation of methyl orange (MO) under irradiation by ultraviolet light and visible light, respectively, being superior to that of pure SrTiO 3 and commercial TiO 2 (P-25) powders. In addition, the Er–N co-doped SrTiO 3 (initial molar ratios of Sr/Er/N = 1:0.015:0.1, designated as S5) sample showed the best photocatalytic activity with the degradation rate as high as 98% after 30 min under the visible light irradiation. After five cycles, the photocatalytic activity of the S5 catalyst showed no significant decrease, which indicated that the photocatalysts were stable under visible light irradiation

  19. Hierarchical N-Doped Carbon as CO2 Adsorbent with High CO2 Selectivity from Rationally Designed Polypyrrole Precursor.

    Science.gov (United States)

    To, John W F; He, Jiajun; Mei, Jianguo; Haghpanah, Reza; Chen, Zheng; Kurosawa, Tadanori; Chen, Shucheng; Bae, Won-Gyu; Pan, Lijia; Tok, Jeffrey B-H; Wilcox, Jennifer; Bao, Zhenan

    2016-01-27

    Carbon capture and sequestration from point sources is an important component in the CO2 emission mitigation portfolio. In particular, sorbents with both high capacity and selectivity are required for reducing the cost of carbon capture. Although physisorbents have the advantage of low energy consumption for regeneration, it remains a challenge to obtain both high capacity and sufficient CO2/N2 selectivity at the same time. Here, we report the controlled synthesis of a novel N-doped hierarchical carbon that exhibits record-high Henry's law CO2/N2 selectivity among physisorptive carbons while having a high CO2 adsorption capacity. Specifically, our synthesis involves the rational design of a modified pyrrole molecule that can co-assemble with the soft Pluronic template via hydrogen bonding and electrostatic interactions to give rise to mesopores followed by carbonization. The low-temperature carbonization and activation processes allow for the development of ultrasmall pores (d CO2 affinity. Furthermore, our described work provides a strategy to initiate developments of rationally designed porous conjugated polymer structures and carbon-based materials for various potential applications.

  20. Nitrogen doped carbon derived from polyimide/multiwall carbon nanotube composites for high performance flexible all-solid-state supercapacitors

    Science.gov (United States)

    Kim, Dae Kyom; Kim, Nam Dong; Park, Seung-Keun; Seong, Kwang-dong; Hwang, Minsik; You, Nam-Ho; Piao, Yuanzhe

    2018-03-01

    Flexible all-solid-state supercapacitors are desirable as potential energy storage systems for wearable technologies. Herein, we synthesize aminophenyl multiwall carbon nanotube (AP-MWCNT) grafted polyimide precursor by in situ polymerization method as a nitrogen-doped carbon precursor. Flexible supercapacitor electrodes are fabricated via a coating of carbon precursor on carbon cloth surface and carbonization at high temperature directly. The as-obtained electrodes, which can be directly used without any binders or additives, can deliver a high specific capacitance of 333.4 F g-1 at 1 A g-1 (based on active material mass) and excellent cycle stability with 103% capacitance retention after 10,000 cycles in a three-electrode system. The flexible all-solid-state supercapacitor device exhibits a high volumetric capacitance of 3.88 F cm-3 at a current density of 0.02 mA cm-3. And also the device can deliver a maximum volumetric energy density of 0.50 mWh cm-3 and presents good cycling stability with 85.3% capacitance retention after 10,000 cycles. This device cell can not only show extraordinary mechanical flexibilities allowing folding, twisting, and rolling but also demonstrate remarkable stable electrochemical performances under their forms. This work provides a novel approach to obtain carbon textile-based flexible supercapacitors with high electrochemical performance and mechanical flexibility.

  1. Rapid microwave-assisted synthesis of highly luminescent nitrogen-doped carbon dots for white light-emitting diodes

    Science.gov (United States)

    Wang, Yaling; Zheng, Jingxia; Wang, Junli; Yang, Yongzhen; Liu, Xuguang

    2017-11-01

    Highly luminescent nitrogen-doped carbon dots (N-CDs) were synthesized rapidly by one-step microwave-assisted hydrothermal method using citric acid as carbon source and ethylenediamine as dopant. The influences of reaction temperature, reaction time and raw material ratio on the fluorescence performance of N-CDs were investigated. Then N-CDs with the highest quantum yield were selected as fluorescent materials for fabricating white light-emitting diodes (LEDs). Highly luminescent N-CDs with the quantum yield of 75.96% and blue-to-red spectral composition of 51.48% were obtained at the conditions of 180 °C, 8 min and the molar ratio of citric acid to ethylenediamine 2:1. As-prepared highly luminescent N-CDs have an average size of 6.06 nm, possess extensive oxygen- and nitrogen-containing functional groups on their surface, and exhibit strong absorption in ultraviolet region. White LEDs based on the highly luminescent N-CDs emit warm white light with color coordinates of (0.42, 0.40) and correlated color temperature of 3416 K.

  2. Nitrogen-Doped Carbon Nanoparticles for Oxygen Reduction Prepared via a Crushing Method Involving a High Shear Mixer

    Directory of Open Access Journals (Sweden)

    Lei Shi

    2017-09-01

    Full Text Available The disposal of agricultural wastes such as fresh banana peels (BPs is an environmental issue. In this work, fresh BPs were successfully transformed into nitrogen-doped carbon nanoparticles (N-CNPs by using a high shear mixer facilitated crushing method (HSM-FCM followed by carbonization under Ar atmosphere. Ammonia-activated N-CNPs (N-CNPs-NH3 were prepared via subsequent ammonia activation treatments at a high temperature. The as-prepared N-CNPs and N-CNPs-NH3 materials both exhibited high surface areas (above 700 m2/g and mean particle size of 50 nm. N-CNPs-NH3 showed a relatively higher content of pyridinic and graphitic N compared to N-CNPs. In alkaline media, N-CNPs-NH3 showed superior performances as an oxygen reduction reaction (ORR catalyst (E0 = −0.033 V, J = 2.4 mA/cm2 compared to N-CNPs (E0 = 0.07 V, J = 1.8 mA/cm2. In addition, N-CNPs-NH3 showed greater oxygen reduction stability and superior methanol crossover avoidance than a conventional Pt/C catalyst. This study provides a novel, simple, and scalable approach to valorize biomass wastes by synthesizing highly efficient electrochemical ORR catalysts.

  3. Current use of high-resolution mass spectrometry in drug screening relevant to clinical and forensic toxicology and doping control.

    Science.gov (United States)

    Ojanperä, Ilkka; Kolmonen, Marjo; Pelander, Anna

    2012-05-01

    Clinical and forensic toxicology and doping control deal with hundreds or thousands of drugs that may cause poisoning or are abused, are illicit, or are prohibited in sports. Rapid and reliable screening for all these compounds of different chemical and pharmaceutical nature, preferably in a single analytical method, is a substantial effort for analytical toxicologists. Combined chromatography-mass spectrometry techniques with standardised reference libraries have been most commonly used for the purpose. In the last ten years, the focus has shifted from gas chromatography-mass spectrometry to liquid chromatography-mass spectrometry, because of progress in instrument technology and partly because of the polarity and low volatility of many new relevant substances. High-resolution mass spectrometry (HRMS), which enables accurate mass measurement at high resolving power, has recently evolved to the stage that is rapidly causing a shift from unit-resolution, quadrupole-dominated instrumentation. The main HRMS techniques today are time-of-flight mass spectrometry and Orbitrap Fourier-transform mass spectrometry. Both techniques enable a range of different drug-screening strategies that essentially rely on measuring a compound's or a fragment's mass with sufficiently high accuracy that its elemental composition can be determined directly. Accurate mass and isotopic pattern acts as a filter for confirming the identity of a compound or even identification of an unknown. High mass resolution is essential for improving confidence in accurate mass results in the analysis of complex biological samples. This review discusses recent applications of HRMS in analytical toxicology.

  4. Doping control using high and ultra-high resolution mass spectrometry based non-targeted metabolomics-a case study of salbutamol and budesonide abuse.

    Directory of Open Access Journals (Sweden)

    Agneta Kiss

    Full Text Available We have detected differences in metabolite levels between doped athletes, clean athletes, and volunteers (non athletes. This outcome is obtained by comparing results of measurements from two analytical platforms: UHPLC-QTOF/MS and FT-ICR/MS. Twenty-seven urine samples tested positive for glucocorticoids or beta-2-agonists and twenty samples coming from volunteers and clean athletes were analyzed with the two different mass spectrometry approaches using both positive and negative electrospray ionization modes. Urine is a highly complex matrix containing thousands of metabolites having different chemical properties and a high dynamic range. We used multivariate analysis techniques to unravel this huge data set. Thus, the several groups we created were studied by Principal Components Analysis (PCA and Partial Least Square regression (PLS-DA and OPLS in the search of discriminating m/z values. The selected variables were annotated and placed on pathway by using MassTRIX.

  5. Low-Temperature Sol-Gel Synthesis of Nitrogen-Doped Anatase/Brookite Biphasic Nanoparticles with High Surface Area and Visible-Light Performance

    Directory of Open Access Journals (Sweden)

    Liang Jiang

    2017-12-01

    Full Text Available Nitrogen doping in combination with the brookite phase or a mixture of TiO2 polymorphs nanomaterials can enhance photocatalytic activity under visible light. Generally, nitrogen-dopedanatase/brookite mixed phases TiO2 nanoparticles obtained by hydrothermal or solvothermal method need to be at high temperature and with long time heating treatment. Furthermore, the surface areas of them are low (<125 m2/g. There is hardly a report on the simple and direct preparation of N-doped anatase/brookite mixed phase TiO2 nanostructures using sol-gel method at low heating temperature. In this paper, the nitrogen-doped anatase/brookite biphasic nanoparticles with large surface area (240 m2/g were successfully prepared using sol-gel method at low temperature (165 °C, and with short heating time (4 h under autogenous pressure. The obtained sample without subsequent annealing at elevated temperatures showed enhanced photocatalytic efficiency for the degradation of methyl orange (MO with 4.2-, 9.6-, and 7.5-fold visible light activities compared to P25 and the amorphous samples heated in muffle furnace with air or in tube furnace with a flow of nitrogen at 165 °C, respectively. This result was attributed to the synergistic effects of nitrogen doping, mixed crystalline phases, and high surface area.

  6. Ultrasmall Tin Nanodots Embedded in Nitrogen-Doped Mesoporous Carbon: Metal-Organic-Framework Derivation and Electrochemical Application as Highly Stable Anode for Lithium Ion Batteries

    International Nuclear Information System (INIS)

    Dai, Ruoling; Sun, Weiwei; Wang, Yong

    2016-01-01

    Highlights: • Sn-based metal-organic-framework (MOF) is prepared. • Ultrasmall tin nanodots (2–3 nm) are embedded in nitrogen-doped mesoporous carbon. • The Sn/C composite anode shows high capacity and ultralong cycle life. - Abstract: This work reports a facile metal-organic-framework based approach to synthesize Sn/C composite, in which ultrasmall Sn nanodots with typical size of 2–3 nm are uniformly embedded in the nitrogen-doped porous carbon matrix (denoted as Sn@NPC). The effect of thermal treatment and nitrogen doping are also explored. Owing to the delicate size control and confined volume change within carbon matrix, the Sn@NPC composite can exhibit reversible capacities of 575 mAh g −1 (Sn contribution: 1091 mAh g −1 ) after 500 cycles at 0.2 A g −1 and 507 mAh g −1 (Sn contribution: 1077 mAh g −1 ) after 1500 cycles at 1 A g −1 . The excellent long-life electrochemical stability of the Sn@NPC anode has been mainly attributed to the uniform distribution of ultrasmall Sn nanodots and the highly-conductive and flexible N-doped carbon matrix, which can effectively facilitate lithium ion/electron diffusion, buffer the large volume change and improve the structure stability of the electrode during repetitive cycling with lithium ions.

  7. 16 CFR 460.20 - R-value per inch claims.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false R-value per inch claims. 460.20 Section 460.20 Commercial Practices FEDERAL TRADE COMMISSION TRADE REGULATION RULES LABELING AND ADVERTISING OF HOME INSULATION § 460.20 R-value per inch claims. In labels, fact sheets, ads, or other promotional...

  8. Orthopedic stretcher with average-sized person can pass through 18-inch opening

    Science.gov (United States)

    Lothschuetz, F. X.

    1966-01-01

    Modified Robinson stretcher for vertical lifting and carrying, will pass through an opening 18 inches in diameter, while containing a person of average height and weight. A subject 6 feet tall and weighing 200 pounds was lowered and raised out of an 18 inch diameter opening in a tank to test the stretcher.

  9. Comparison of silicon strip tracker module size using large sensors from 6 inch wafers

    CERN Multimedia

    Honma, Alan

    1999-01-01

    Two large silicon strip sensor made from 6 inch wafers are placed next to each other to simulate the size of a CMS outer silicon tracker module. On the left is a prototype 2 sensor CMS inner endcap silicon tracker module made from 4 inch wafers.

  10. Development and characterization of a CCD camera system for use on six-inch manipulator systems

    International Nuclear Information System (INIS)

    Logory, L.M.; Bell, P.M.; Conder, A.D.; Lee, F.D.

    1996-01-01

    The Lawrence Livermore National Laboratory has designed, constructed, and fielded a compact CCD camera system for use on the Six Inch Manipulator (SIM) at the Nova laser facility. The camera system has been designed to directly replace the 35 mm film packages on all active SIM-based diagnostics. The unit's electronic package is constructed for small size and high thermal conductivity using proprietary printed circuit board technology, thus reducing the size of the overall camera and improving its performance when operated within the vacuum environment of the Nova laser target chamber. The camera has been calibrated and found to yield a linear response, with superior dynamic range and signal-to-noise levels as compared to T-Max 3200 optic film, while providing real-time access to the data. Limiting factors related to fielding such devices on Nova will be discussed, in addition to planned improvements of the current design

  11. N- and O-doped hollow carbonaceous spheres with hierarchical porous structure for potential application in high-performance capacitance

    Science.gov (United States)

    Chen, Ze; Cao, Rui; Ge, Yuanhang; Tu, Yingfeng; Xia, Yu; Yang, Xiaoming

    2017-09-01

    Hollow carbonaceous spheres (HCSs) have been extensively investigated due to their valuable potentials in the applications of energy storage devices such as solar cells, fuel cells, and supercapacitors. It is highly desirable to develop abundant pore structures and introduce heteroatoms in the resultant HCSs to improve capacitance of the devices. Herein, N-, and O-doped HCSs with macro/micro/mesoporous structures are successfully prepared by one-step carbonization of polypyrrole coated polystyrene nanoparticles followed by chemical activation with KOH. The huge specific surface area (up to 935 m2 g-1) and hierarchical porous structures can effectively facilitate the transportation and exchange of ions and electrons. Besides, high heteroatom content (∼30%) are believed to provide pseudocapacitance contributed from the redox faradic reactions of these electrochemically active functional groups. The as-prepared activated HCSs possess a high capacitance of 535 F g-1 at a current density of 0.2 A g-1, and maintains 55% of the highest capacitance even at a current density of 10 A g-1. The newly prepared HCSs thus show great potential as the electrode materials of supercapacitors.

  12. A high energy and power sodium-ion hybrid capacitor based on nitrogen-doped hollow carbon nanowires anode

    Science.gov (United States)

    Li, Dongdong; Ye, Chao; Chen, Xinzhi; Wang, Suqing; Wang, Haihui

    2018-04-01

    The sodium ion hybrid capacitor (SHC) has been attracting much attention. However, the SHC's power density is significantly confined to a low level due to the sluggish ion diffusion in the anode. Herein, we propose to use an electrode with a high double layer capacitance as the anode in the SHC instead of insertion anodes. To this aim, nitrogen doped hollow carbon nanowires (N-HCNWs) with a high specific surface area are prepared, and the high capacitive contribution during the sodium ion storage process is confirmed by a series of electrochemical measurements. A new SHC consisting of a N-HCNW anode and a commercial active carbon (AC) cathode is fabricated for the first time. Due to the hybrid charge storage mechanism combining ion insertion and capacitive process, the as-fabricated SHC strikes a balance between the energy density and power density, a energy density of 108 Wh kg-1 and a power density of 9 kW kg-1 can be achieved, which overwhelms the electrochemical performances of most reported AC-based SHCs.

  13. Test procedure for the Master-Lee and the modified Champion four inch hydraulic cutters

    International Nuclear Information System (INIS)

    Crystal, J.B.

    1995-01-01

    The Master-Lee and the modified Champion 4 Inch hydraulic cutters are being retested to gather and document information related to the following: determine if the Master-Lee cutters will cut the trunnions of an Aluminum fuel canister and a Stainless Steel fuel canister; determine if the Master-Lee cutters will cut 1 1/2 inch diameter fire hose; determine if the modified Champion 4 inch blade will cut sections of piping; and determine the effectiveness of the centering device for the Champion 4 Inch cutters. Determining the limitations of the hydraulic cutter will aid in the process of debris removal in the K-Basin. Based on a previous test, the cutters were returned to the manufacturer for modifications. The modifications to the Champion 4 Inch Cutter and further testing of the Master-Lee Cutter are the subjects of these feature tests

  14. Highly Cost-Effective Nitrogen-Doped Porous Coconut Shell-Based CO2 Sorbent Synthesized by Combining Ammoxidation with KOH Activation.

    Science.gov (United States)

    Yang, Mingli; Guo, Liping; Hu, Gengshen; Hu, Xin; Xu, Leqiong; Chen, Jie; Dai, Wei; Fan, Maohong

    2015-06-02

    The objective of this research is to develop a cost-effective carbonaceous CO2 sorbent. Highly nanoporous N-doped carbons were synthesized with coconut shell by combining ammoxidation with KOH activation. The resultant carbons have characteristics of highly developed porosities and large nitrogen loadings. The prepared carbons exhibit high CO2 adsorption capacities of 3.44-4.26 and 4.77-6.52 mmol/g at 25 and 0 °C under atmospheric pressure, respectively. Specifically, the sample NC-650-1 prepared under very mild conditions (650 °C and KOH/precursor ratio of 1) shows the CO2 uptake 4.26 mmol/g at 25 °C, which is among the best of the known nitrogen-doped porous carbons. The high CO2 capture capacity of the sorbent can be attributed to its high microporosity and nitrogen content. In addition, the CO2/N2 selectivity of the sorbent is as high as 29, higher than that of many reported CO2 sorbents. Finally, this N-doped carbon exhibits CO2 heats of adsorption as high as 42 kJ/mol. The multiple advantages of these cost-effective coconut shell-based carbons demonstrate that they are excellent candidates for CO2 capture.

  15. Polyoxometalate and Resin-Derived P-Doped Mo2C@N-Doped Carbon as a Highly Efficient Hydrogen-Evolution Reaction Catalyst at All pH Values.

    Science.gov (United States)

    Yan, Gang; Feng, Xiaojia; Khan, Shifa Ullah; Xiao, Liguang; Xi, Wenguang; Tan, Huaqiao; Ma, Yuanyuan; Zhang, Lunan; Li, Yangguang

    2018-01-18

    A new type of P-doped Mo 2 C coated by N-doped carbon (P-Mo 2 C@NC) has been successfully prepared by calcining a mixture of H 3 [PMo 12 O 40 ] polyoxometalates (POMs) and urea-formaldehyde resin under an N 2 atmosphere. Urea-formaldehyde resin not only serves as the carbon source to ensure carbonization but also facilitates the uniform distribution of POM precursors, which efficiently avoid the aggregation of Mo 2 C particles at high temperatures. TEM analysis revealed that the average diameter of the Mo 2 C particles was about 10 nm, which is coated by a few-layer N-doped carbon sheet. The as-prepared P-Mo 2 C@NC displayed excellent hydrogen-evolution reaction (HER) performance and long-term stability in all pH environments. To reach a current density of 10 mA cm -2 , only 109, 159, and 83 mV were needed for P-Mo 2 C@NC in 0.5 m H 2 SO 4 (pH 0), 0.1 m phosphate buffer (pH 7), and 1 m KOH (pH 14), respectively. This could provide a high-yield and low-cost method to prepare uniform nanosized molybdenum carbides with highly efficient and stable HER performance. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. High photocatalytic activity of hierarchical SiO2@C-doped TiO2hollow spheres in UV and visible light towards degradation of rhodamine B.

    Science.gov (United States)

    Zhang, Ying; Chen, Juanrong; Hua, Li; Li, Songjun; Zhang, Xuanxuan; Sheng, Weichen; Cao, Shunsheng

    2017-10-15

    Ongoing research activities are targeted to explore high photocatalytic activity of TiO 2 -based photocatalysts for the degradation of environmental contaminants under UV and visible light irradiation. In this work, we devise a facile, cost-effective technique to in situ synthesize hierarchical SiO 2 @C-doped TiO 2 (SCT) hollow spheres for the first time. This strategy mainly contains the preparation of monodisperse cationic polystyrene spheres (CPS), sequential deposition of inner SiO 2 , the preparation of the sandwich-like CPS@SiO 2 @CPS particles, and formation of outer TiO 2 . After the one-step removal of CPS templates by calcination at 450°C, hierarchical SiO 2 @C-doped TiO 2 hollow spheres are in situ prepared. The morphology, hierarchical structure, and properties of SCT photocatalyst were characterized by TEM. SEM, STEM Mapping, BET, XRD, UV-vis spectroscopy, and XPS. Results strongly confirm the carbon doping in the outer TiO 2 lattice of SCT hollow spheres. When the as-synthesized SCT hollow spheres were employed as a photocatalyst for the degradation of Rhodamine B under visible-light and ultraviolet irradiation, the SCT photocatalyst exhibits a higher photocatalytic activity than commercial P25, effectively overcoming the limitations of poorer UV activity for many previous reported TiO 2 -based photocatalysts due to doping. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. General Synthesis of Transition-Metal Oxide Hollow Nanospheres/Nitrogen-Doped Graphene Hybrids by Metal-Ammine Complex Chemistry for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Chen, Jiayuan; Wu, Xiaofeng; Gong, Yan; Wang, Pengfei; Li, Wenhui; Mo, Shengpeng; Peng, Shengpan; Tan, Qiangqiang; Chen, Yunfa

    2018-02-09

    We present a general and facile synthesis strategy, on the basis of metal-ammine complex chemistry, for synthesizing hollow transition-metal oxides (Co 3 O 4 , NiO, CuO-Cu 2 O, and ZnO)/nitrogen-doped graphene hybrids, potentially applied in high-performance lithium-ion batteries. The oxygen-containing functional groups of graphene oxide play a prerequisite role in the formation of hollow transition-metal oxides on graphene nanosheets, and a significant hollowing process occurs only when forming metal (Co 2+ , Ni 2+ , Cu 2+ , or Zn 2+ )-ammine complex ions. Moreover, the hollowing process is well correlated with the complexing capacity between metal ions and NH 3 molecules. The significant hollowing process occurs for strong metal-ammine complex ions including Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ions, and no hollow structures formed for weak and/or noncomplex Mn 2+ and Fe 3+ ions. Simultaneously, this novel strategy can also achieve the direct doping of nitrogen atoms into the graphene framework. The electrochemical performance of two typical hollow Co 3 O 4 or NiO/nitrogen-doped graphene hybrids was evaluated by their use as anodic materials. It was demonstrated that these unique nanostructured hybrids, in contrast with the bare counterparts, solid transition-metal oxides/nitrogen-doped graphene hybrids, perform with significantly improved specific capacity, superior rate capability, and excellent capacity retention. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Composite films of metal doped CoS/carbon allotropes; efficient electrocatalyst counter electrodes for high performance quantum dot-sensitized solar cells.

    Science.gov (United States)

    Khalili, Seyede Sara; Dehghani, Hossein; Afrooz, Malihe

    2017-05-01

    This study reports the enhanced catalytic ability of metal ions-doped CoS and CoS/carbon allotrope counter electrodes (CEs) (synthesized using a successive ionic layer adsorption and reaction (SILAR) method) to improve the power conversion efficiency (η) in quantum dot-sensitized solar cells (QDSSCs). Firstly, doping effects of different metal ions (Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+ ) in the CoS CE on the QDSSCs performance have been investigated. Overall, among the different metal doped CoS CEs, the best energy conversion efficiency of 2.19%, achieved for Sr, is the highest reported for QDSSCs constructed with metal doped CoS. A sandwich structural Sr- and Ba-CoS/carbon allotrope (graphene sheet (GS), graphene oxide (GO) and carbon nanotube (CNT)) composite CEs have been prepared by repeating electrophoretic deposition (EPD) of carbon materials and deposition of CoS nanoparticles. Dramatic enhancements of η have been observed with the Sr- and Ba-CoS/GO CEs based QDSSCs (∼76% and ∼41%, respectively), which is higher than that of the bare CoS CE. Because of the large specific surface area and superior electrical conductivity of GS, GO and CNT and the high electrocatalytic activity of CoS, these CEs show an improvement in the photocurrent density in the cells, as revealed from electrochemical and spectral data. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. N/S/B-doped graphitized carbon encased Fe species as a highly active and durable catalyst towards oxygen reduction reaction.

    Science.gov (United States)

    Li, Guang-Lan; Cheng, Guang-Chun; Chen, Wen-Wen; Liu, Cai-Di; Yuan, Li-Fang; Yang, Bei-Bei; Hao, Ce

    2018-03-15

    Exploring cost-effective, high-performance and durable non-precious metal catalysts is of great significance for the acceleration of sluggish oxygen reduction reaction (ORR). Here, we report an intriguing heteroatom-doped graphitized carbon encased Fe species composite by introducing N, S and B sequentially. The experimental approach was designed ingeniously for that the FeCl 3 ·6H 2 O could catalyze thiourea to synthesize N, S co-doped carbon materials which would further react with H 3 BO 3 and NH 3 (emerged at the heat-treatment process) to prepare N, S and B co-doped carbon materials (Fe-N/S/B-C). The Fe-N/S/B-C exhibits an impressive ORR activity for its half-wave potential of -0.1 V, which is 36 mV or 19 mV higher than that of the corresponding single or dual doped counterparts (Fe-N-C or Fe-N/S-C) and 31 mV positive than that of Pt/C catalyst, respectively. Further chronoamperometric measurement and accelerated aging test confirm the excellent electrochemical durability of Fe-N/S/B-C with the stable core-shell structure. The remarkable ORR performance and facile preparation method enable Fe-N/S/B-C as a potential candidate in electrochemical energy devices. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Non-Doped Sky-Blue OLEDs Based on Simple Structured AIE Emitters with High Efficiencies at Low Driven Voltages.

    Science.gov (United States)

    Islam, Amjad; Zhang, Dongdong; Peng, Ruixiang; Yang, Rongjuan; Hong, Ling; Song, Wei; Wei, Qiang; Duan, Lian; Ge, Ziyi

    2017-09-05

    Blue organic light-emitting diodes (OLEDs) are necessary for flat-panel display technologies and lighting applications. To make more energy-saving, low-cost and long-lasting OLEDs, efficient materials as well as simple structured devices are in high demand. However, a very limited number of blue OLEDs achieving high stability and color purity have been reported. Herein, three new sky-blue emitters, 1,4,5-triphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEI), 1-(4-methoxyphenyl)-4,5-diphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEMeOPhI) and 1-phenyl-2,4,5-tris(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (3TPEI), with a combination of imidazole and tetraphenylethene groups, have been developed. High photoluminescence quantum yields are obtained for these materials. All derivatives have demonstrated aggregation-induced emission (AIE) behavior, excellent thermal stability with high decomposition and glass transition temperatures. Non-doped sky-blue OLEDs with simple structure have been fabricated employing these materials as emitters and realized high efficiencies of 2.41 % (4.92 cd A -1 , 2.70 lm W -1 ), 2.16 (4.33 cd A -1 , 2.59 lm W -1 ) and 3.13 % (6.97 cd A -1 , 4.74 lm W -1 ) for TPEI, TPEMeOPhI and 3TPEI, with small efficiency roll-off. These are among excellent results for molecules constructed from the combination of imidazole and TPE reported so far. The high performance of a 3TPEI-based device shows the promising potential of the combination of imidazole and AIEgen for synthesizing efficient electroluminescent materials for OLED devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Fullerene-Structured MoSe2 Hollow Spheres Anchored on Highly Nitrogen-Doped Graphene as a Conductive Catalyst for Photovoltaic Applications.

    Science.gov (United States)

    Bi, Enbing; Chen, Han; Yang, Xudong; Ye, Fei; Yin, Maoshu; Han, Liyuan

    2015-08-17

    A conductive catalyst composed of fullerene-structured MoSe2 hollow spheres and highly nitrogen-doped graphene (HNG-MoSe2) was successfully synthesized via a wet chemical process. The small molecule diethylenetriamine, which was used during the process, served as a surfactant to stabilize the fullerene-structured MoSe2 hollow spheres and to provide a high content of nitrogen heteroatoms for graphene doping (ca. 12% N). The superior synergistic effect between the highly nitrogen-doped graphene and the high surface-to-volume ratio MoSe2 hollow spheres afforded the HNG-MoSe2 composite high conductivity and excellent catalytic activity as demonstrated by cyclic voltammetry, electrochemical impedance spectroscopy and Tafel measurements. A dye-sensitized solar cell (DSSC) prepared with HNG-MoSe2 as a counter electrode exhibited a conversion efficiency of 10.01%, which was close to that of a DSSC with a Pt counter electrode (10.55%). The synergy between the composite materials and the resulting highly efficient catalysis provide benchmarks for preparing well-defined, graphene-based conductive catalysts for clean and sustainable energy production.

  2. Synthesis of highly fluorescent silica nanoparticles in a reverse microemulsion through double-layered doping of organic fluorophores

    International Nuclear Information System (INIS)

    Yoo, Hyojong; Pak, Joonsung

    2013-01-01

    Water-soluble, highly fluorescent double-layered silica nanoparticles (FL-DLSN) have been successfully synthesized through a reverse (water-in-oil) microemulsion method. The microemulsion was prepared by mixing a surfactant (Brij35), co-surfactant, organic solvent, water, and fluorescein as an organic fluorophore. The sizes of the silica nanoparticles were successfully controlled in the reverse microemulsion using Brij35 by changing the water-to-Brij35 ratio and by adding HCl. Initially, tetraethylorthosilicate was hydrolyzed by adding NH 4 OH as a catalyst and then polymerized to generate core fluorescent silica nanoparticles with fluorescein. 3-(Aminopropyl)triethoxysilane (APTS) was sequentially added into the reaction mixture, and reacted on the surface of pre-generated core silica nanoparticles to form the second layer in the form of a shell. The second silica layer that was derived from the condensation of APTS effectively protected the fluorescein dye within the silica matrix. This is a novel and simple synthetic approach to generate highly fluorescent, monodispersed silica nanoparticles by doping organic molecules into a silica matrix.Graphical Abstract

  3. Effects of improved process for CuO-doped NKN lead-free ceramics on high-power piezoelectric transformers.

    Science.gov (United States)

    Yang, Song-Ling; Tsai, Cheng-Che; Liou, Yi-Cheng; Hong, Cheng-Shong; Li, Bing-Jing; Chu, Sheng-Yuan

    2011-12-01

    In this paper, the effects of the electrical proper- ties of CuO-doped (Na(0.5)K(0.5))NbO(3) (NKN) ceramics prepared separately using the B-site oxide precursor method (BO method) and conventional mixed-oxide method (MO method) on high-power piezoelectric transformers (PTs) were investigated. The performances of PTs made with these two substrates were compared. Experimental results showed that the output power and temperature stability of PTs could be enhanced because of the lower resonant impedance of the ceramics prepared using the BO method. In addition, the output power of PTs was more affected by the resonant impedance than by the mechanical quality factor (Q(m)) of the ceramics. The PTs fabricated with ceramics prepared using the BO method showed a high efficiency of more than 94% and a maximum output power of 8.98 W (power density: 18.3 W/cm(3)) with temperature increase of 3°C under the optimum load resistance (5 kΩ) and an input voltage of 150 V(pp). This output power of the lead-free disk-type PTs is the best reported so far.

  4. Highly efficient transition metal and nitrogen co-doped carbide-derived carbon electrocatalysts for anion exchange membrane fuel cells

    Science.gov (United States)

    Ratso, Sander; Kruusenberg, Ivar; Käärik, Maike; Kook, Mati; Puust, Laurits; Saar, Rando; Leis, Jaan; Tammeveski, Kaido

    2018-01-01

    The search for an efficient electrocatalyst for oxygen reduction reaction (ORR) to replace platinum in fuel cell cathode materials is one of the hottest topics in electrocatalysis. Among the many non-noble metal catalysts, metal/nitrogen/carbon composites made by pyrolysis of cheap materials are the most promising with control over the porosity and final structure of the catalyst a crucial point. In this work we show a method of producing a highly active ORR catalyst in alkaline media with a controllable porous structure using titanium carbide derived carbon as a base structure and dicyandiamide along with FeCl3 or CoCl2 as the dopants. The resulting transition metal-nitrogen co-doped carbide derived carbon (M/N/CDC) catalyst is highly efficient for ORR electrocatalysis with the activity in 0.1 M KOH approaching that of commercial 46.1 wt.% Pt/C. The catalyst materials are also investigated by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy to characterise the changes in morphology and composition causing the raise in electrochemical activity. MEA performance of M/N/CDC cathode materials in H2/O2 alkaline membrane fuel cell is tested with the highest power density reached being 80 mW cm-2 compared to 90 mW cm-2 for Pt/C.

  5. Mn doped FeCO3/reduced graphene composite as anode material for high performance lithium-ion batteries

    Science.gov (United States)

    Zhang, Congcong; Cai, Xin; Xu, Donghui; Chen, Wenyan; Fang, Yueping; Yu, Xiaoyuan

    2018-01-01

    FeCO3 (FCO), FeCO3/rGO (FCOG) and Fe0.8Mn0.2CO3/rGO (MFCOG) nanocomposites are synthesized via a facile and controllable one-step hydrothermal process. XRD, SEM and TEM characterizations show that Mn ions can successfully substitute for partial iron atoms in FeCO3 nanocrystals without any crystal structure changes. Applied as anodes for lithium-ion batteries (LIBs), MFCOG delivers optimal electrochemical performance with a reversible capacity of 1223 mAh g-1 at a current density of 0.2 A g-1 after 120 cycles. Furthermore, MFCOG maintains a specific capacity of 613 mAh g-1 at a high current density of 1.6 A g-1, showing the enhanced rate capabilities and stable cycling performance. It indicates that the excellent lithium storage performance of MFCOG is mainly related to its well-designed nanostructure of doped metal carbonates and rGO nanosheets with high electrical conductivity which can work as effective conductive matrix and restrain the agglomeration of FeCO3, leading to synergistic effects on improving the structural integrity and accommodating the volume changes of MFCOG during the process of lithium intercalation/deintercalation.

  6. Decoration of nitrogen-doped reduced graphene oxide with cobalt tungstate nanoparticles for use in high-performance supercapacitors

    Science.gov (United States)

    Naderi, Hamid Reza; Sobhani-Nasab, Ali; Rahimi-Nasrabadi, Mehdi; Ganjali, Mohammad Reza

    2017-11-01

    A composite of cobalt tungstate nanoparticles coated on nitrogen-doped reduced graphene oxide (CoWO4/NRGO) was prepared through an in situ sonochemical approach. The composite was next evaluated as an electrode material for use supercapacitors electrodes. The characterization of the various CoWO4/NRGO nanocomposite samples was carried out through field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), Brunauer-Emmett-Teller (BET) method and Raman spectroscopy. Complementary studies were also performed through cyclic voltammetry (CV), galvanostatic charge/discharge, electrochemical impedance spectroscopy (EIS), and continues cyclic voltammetry (CCV). The electrochemical evaluations were carried out in a 2 M H2SO4 solution as the electrolyte. The electrochemical evaluations on the nano-composite samples indicated that CoWO4/NRGO-based electrodes reveal enhanced supercapacitive characteristics (i.e. a high specific capacitance (SC) of 597 F g-1 at a scan rate of 5 mV s-1, an energy density (ED) value of 67.9 W h kg-1, and high rate capability). CCV studies indicated that CoWO4/NRGO-based electrodes keep 97.1% of their original capacitance after 4000 cycles. The results led to the conclusion that CoWO4/NRGO effectively merge the merits of CoWO4 and CoWO4/RGO in one new nanocomposite material.

  7. Polyelectrolyte-assisted preparation of gold nanocluster-doped silica particles with high incorporation efficiency and improved stability

    Science.gov (United States)

    Wang, Haonan; Huang, Zhenzhen; Guo, Zilong; Yang, Wensheng

    2017-07-01

    In this paper, we reported an approach for efficient incorporation of glutathione-capped gold nanoclusters (GSH-Au NCs) into silica particles with the assistance of a polyelectrolyte, poly-diallyldimethyl-ammoniumchloride (PDDA). In this approach, the negatively charged GSH-Au NCs were firstly mixed with the positively charged PDDA to form PDDA-Au NC complexes. Then, the complexes were added into a pre-hydrolyzed Stöber system to get the Au NCs-doped silica particles. With increased ratio of PDDA in the complexes, the negative charges on surface of the Au NCs were neutralized gradually and finally reversed to positive in presence of excess PDDA, which facilitated the incorporation of the Au NCs into the negatively charged silica matrix. Under the optimal amount of PDDA in the complexes, the incorporation efficiency of Au NCs could be as high as 88%. After being incorporated into the silica matrix, the Au NCs become much robust against pH and heavy metal ions attributed to the protection effect of silica and PDDA. This approach was also extendable to highly efficient incorporation of other negatively charged metal nanoclusters, such as bovine serum albumin-capped Cu nanoclusters, into silica matrix.

  8. Seaweed-derived heteroatom-doped highly porous carbon as an electrocatalyst for the oxygen reduction reaction.

    Science.gov (United States)

    Song, Min Young; Park, Hyean Yeol; Yang, Dae-Soo; Bhattacharjya, Dhrubajyoti; Yu, Jong-Sung

    2014-06-01

    We report the template-free pyrolysis of easily available natural seaweed, Undaria pinnatifida, as a single precursor, which results in "seaweed carbon" (SCup). Interestingly, thus-obtained SCup not only contains heteroatoms such as nitrogen and sulfur in its framework, but it also possesses a well-developed porous structure with high surface area. The heteroatoms in SCup originate from the nitrogen- and sulfur-containing ingredients in seaweed, whereas the porosity is created by removal of salts inherently present in the seaweed. These essential and fundamental properties make seaweed a prime choice as a precursor for heteroatom-containing highly porous carbon as a metal-free efficient electrocatalyst. As-synthesized SCup showed excellent electrocatalytic activity in the oxygen reduction reaction (ORR) in alkaline medium, which can be addressed in terms of the presence of the nitrogen and sulfur heteroatoms, the well-developed porosity, and the electrical conductivity in the carbon framework. The pyrolysis temperature was a key controlling parameter that determined the trade-off between heteroatom doping, surface properties, and electrical conductivity. In particular, SCup prepared at 1000 °C showed the best ORR performance. Additionally, SCup exhibited enhanced durability and methanol tolerance relative to the state of the art commercial Pt catalyst, which demonstrates that SCup is a promising alternative to costly Pt-based catalysts for the ORR. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Exploiting the natural doping gradient of Nd:YLF crystals for high-power end pumped lasers

    CSIR Research Space (South Africa)

    Bollig, C

    2008-01-01

    Full Text Available ignored. In collaboration, VLOC estimated the doping gradient of a specially manufactured boule (Fig. 2) and maintained the crystal orientation information during the manufacturing process of the 45 mm long, 6 mm diameter crystals. Initial thermal...

  10. MnO2Nanofilms on Nitrogen-Doped Hollow Graphene Spheres as a High-Performance Electrocatalyst for Oxygen Reduction Reaction.

    Science.gov (United States)

    Yu, Qiangmin; Xu, Jiaoxing; Wu, Chuxin; Zhang, Jianshuo; Guan, Lunhui

    2016-12-28

    Platinum is commonly chosen as an electrocatalyst used for oxygen reduction reaction (ORR). In this study, we report an active catalyst composed of MnO 2 nanofilms grown directly on nitrogen-doped hollow graphene spheres, which exhibits high activity toward ORR with positive onset potential (0.94 V vs RHE), large current density (5.2 mA cm -2 ), and perfect stability. Significantly, when it was used as catalyst for air electrode, a zinc-air battery exhibited a high power density (82 mW cm -2 ) and specific capacities (744 mA h g -1 ) comparable to that with Pt/C (20 wt %) as air cathode. The enhanced activity is ascribed to the synergistic interaction between MnO 2 and the doped hollow carbon nanomaterials. This easy and cheap method paves a way of synthesizing high-performance electrocatalysts for ORR.

  11. Screening and confirmation of myo-inositol trispyrophosphate (ITPP) in human urine by hydrophilic interaction liquid chromatography high resolution / high accuracy mass spectrometry for doping control purposes.

    Science.gov (United States)

    Görgens, Christian; Guddat, Sven; Schänzer, Wilhelm; Thevis, Mario

    2014-01-01

    Myo-inositol trispyrophosphate (ITPP) is a novel allosteric effector of haemoglobin with high permeation selectivity across the red blood cell plasma membrane. Due to its potential to reduce the oxygen affinity of haemoglobin, ITPP application results in an enhanced oxygen release in hypoxic tissues. Therefore, ITPP is being examined for the treatment of numerous illnesses that involve hypoxia, such as cardiovascular diseases, cancer or Alzheimer's disease. Similar to the prohibited substance Efaproxiral®, ITPP increases maximal exercise capacity in mice, providing high potential to be misused in sports. To keep up with cheating athletes, a fast and reliable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for screening and confirmation of ITPP in human urine for doping control purposes was developed. According to the molecule's distinct hydrophilic properties, extraction from complex biological matrices is challenging and conventional reversed phase liquid chromatography (RPLC) separations are not suitable for its detection. Therefore an approach based on hydrophilic interaction liquid chromatography (HILIC) Orbitrap mass spectrometry was established. The methodology was fully validated for qualitative purposes. Screening and confirmation assay are characterized by satisfactory specificity and robustness, adequate intra-day (screening: 4.9-8.1%; confirmation: 2.0-6.7%) and inter-day precision (screening: 4.6-9.1%; confirmation: 1.8-6.6%), excellent linear correlations (>0.99) with sufficient LLOD in the sub ng/mL range (screening: 15 ng/mL; confirmation: 1 ng/mL). In addition it could be shown that ITPP is stable in human urine under the mandatory storage period and conditions for doping control laboratories. To our knowledge, this is the first validated 'dilute-and-inject' LC-MS/MS method for the reliable detection of ITPP in human urine. Copyright © 2014 John Wiley & Sons, Ltd.

  12. Electrostatic Doping in Semiconductor Devices

    NARCIS (Netherlands)

    Gupta, Gaurav; Rajasekharan, Bijoy; Hueting, Raymond J.E.

    2017-01-01

    To overcome the limitations of chemical doping in nanometer-scale semiconductor devices, electrostatic doping (ED) is emerging as a broadly investigated alternative to provide regions with a high electron or hole density in a semiconductor device. In this paper, we review various reported ED

  13. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction.

    Science.gov (United States)

    Cramer, Alisha J; Cole, Jacqueline M; FitzGerald, Vicky; Honkimaki, Veijo; Roberts, Mark A; Brennan, Tessa; Martin, Richard A; Saunders, George A; Newport, Robert J

    2013-06-14

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3)x(R'2O3)y(P2O5)(1-(x+y)), where (R, R') denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP5O14. Thereupon, the effects of rare-earth co-doping on the local structure are assessed at the atomic level. Pair-distribution function analysis of high-energy X-ray diffraction data (Q(max) = 28 Å(-1)) is employed to make this assessment. Results reveal a stark structural invariance to rare-earth co-doping which bears testament to the open-framework and rigid nature of these glasses. A range of desirable attributes of these glasses unfold from this finding; in particular, a structural simplicity that will enable facile molecular engineering of rare-earth phosphate glasses with 'dial-up' lasing properties. When considered together with other factors, this finding also demonstrates additional prospects for these co-doped rare-earth phosphate glasses in nuclear waste storage applications. This study also reveals, for the first time, the ability to distinguish between P-O and P[double bond, length as m-dash]O bonding in these rare-earth phosphate glasses from X-ray diffraction data in a fully quantitative manner. Complementary analysis of high-energy X-ray diffraction data on single rare-earth phosphate glasses of similar rare-earth composition to the co-doped materials is also presented in this context. In a technical sense, all high-energy X-ray diffraction data on these glasses are compared with analogous low-energy diffraction data; their salient differences reveal distinct advantages of high-energy X-ray diffraction data for the study of amorphous materials.

  14. Peapod-like Li3VO4/N-Doped Carbon Nanowires with Pseudocapacitive Properties as Advanced Materials for High-Energy Lithium-Ion Capacitors.

    Science.gov (United States)

    Shen, Laifa; Lv, Haifeng; Chen, Shuangqiang; Kopold, Peter; van Aken, Peter A; Wu, Xiaojun; Maier, Joachim; Yu, Yan

    2017-07-01

    Lithium ion capacitors are new energy storage devices combining the complementary features of both electric double-layer capacitors and lithium ion batteries. A key limitation to this technology is the kinetic imbalance between the Faradaic insertion electrode and capacitive electrode. Here, we demonstrate that the Li 3 VO 4 with low Li-ion insertion voltage and fast kinetics can be favorably used for lithium ion capacitors. N-doped carbon-encapsulated Li 3 VO 4 nanowires are synthesized through a morphology-inheritance route, displaying a low insertion voltage between 0.2 and 1.0 V, a high reversible capacity of ≈400 mAh g -1 at 0.1 A g -1 , excellent rate capability, and long-term cycling stability. Benefiting from the small nanoparticles, low energy diffusion barrier and highly localized charge-transfer, the Li 3 VO 4 /N-doped carbon nanowires exhibit a high-rate pseudocapacitive behavior. A lithium ion capacitor device based on these Li 3 VO 4 /N-doped carbon nanowires delivers a high energy density of 136.4 Wh kg -1 at a power density of 532 W kg -1 , revealing the potential for application in high-performance and long life energy storage devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Biomass-derived nitrogen-doped porous carbons with tailored hierarchical porosity and high specific surface area for high energy and power density supercapacitors

    Science.gov (United States)

    Sun, Junting; Niu, Jin; Liu, Mengyue; Ji, Jing; Dou, Meiling; Wang, Feng

    2018-01-01

    Porous carbon materials with hierarchical structures attract intense interest for the development of high-performance supercapacitors. Herein, we demonstrate a facile and efficient strategy to synthesize nitrogen-doped hierarchically porous carbons with tailored porous structure combined with high specific surface area (SSA), which involves a pre-carbonization and a subsequent carbonization combined with KOH activation of silkworm cocoon precursors. Through adjusting the mass ratio of the activator (KOH) to pre-carbonized precursor in the activation process, the hierarchically porous carbon prepared at the mass ratio of 2 (referred to as NHPC-2) possesses a high defect density and a high SSA of 3386 m2 g-1 as well as the relatively high volumetric proportion of mesopores and macropores (45.5%). As a result, the energy density and power density of the symmetric supercapacitor based on NHPC-2 electrode are as high as 34.41 Wh kg-1 and 31.25 kW kg-1 in organic-solvent electrolyte, and are further improved to 112.1 Wh kg-1 and 23.91 kW kg-1 in ionic-liquid electrolyte.

  16. High electrical resistivity Nd-Fe-B die-upset magnet doped with eutectic DyF3–LiF salt mixture

    Directory of Open Access Journals (Sweden)

    K. M. Kim

    2017-05-01

    Full Text Available Nd-Fe-B-type die-upset magnet with high electrical resistivity was prepared by doping of eutectic DyF3–LiF salt mixture. Mixture of melt-spun Nd-Fe-B flakes (MQU-F: Nd13.6Fe73.6Co6.6Ga0.6B5.6 and eutectic binary (DyF3–LiF salt (25 mol% DyF3 – 75 mol% LiF was hot-pressed and then die-upset. By adding the eutectic salt mixture (> 4 wt%, electrical resistivity of the die-upset magnet was enhanced to over 400 μΩ.cm compared to 190 μΩ.cm of the un-doped magnet. Remarkable enhancement of the electrical resistivity was attributed to homogeneous and continuous coverage of the interface between flakes by the easily melted eutectic salt dielectric mixture. It was revealed that active substitution of the Nd atoms in neighboring flakes by the Dy atoms from the added (DyF3–LiF salt mixture had occurred during such a quick thermal processing of hot-pressing and die-upsetting. This Dy substitution led to coercivity enhancement in the die-upset magnet doped with the eutectic (DyF3–LiF salt mixture. Coercivity and remanence of the die-upset magnet doped with (DyF3–LiF salt mixture was as good as those of the DyF3-doped magnet.

  17. Mesostructured niobium-doped titanium oxide-carbon (Nb-TiO2-C) composite as an anode for high-performance lithium-ion batteries

    Science.gov (United States)

    Hwang, Keebum; Sohn, Hiesang; Yoon, Songhun

    2018-02-01

    Mesostructured niobium (Nb)-doped TiO2-carbon (Nb-TiO2-C) composites are synthesized by a hydrothermal process for application as anode materials in Li-ion batteries. The composites have a hierarchical porous structure with the Nb-TiO2 nanoparticles homogenously distributed throughout the porous carbon matrix. The Nb content is controlled (0-10 wt%) to investigate its effect on the physico-chemical properties and electrochemical performance of the composite. While the crystalline/surface structure varied with the addition of Nb (d-spacing of TiO2: 0.34-0.36 nm), the morphology of the composite remained unaffected. The electrochemical performance (cycle stability and rate capability) of the Nb-TiO2-C composite anode with 1 wt% Nb doping improved significantly. First, a full cut-off potential (0-2.5 V vs. Li/Li+) of Nb-doped composite anode (1 wt%) provides a higher energy utilization than that of the un-doped TiO2-C anode. Second, Nb-TiO2-C composite anode (1 wt%) exhibits an excellent long-term cycle stability (100% capacity retention, 297 mAh/g at 0.5 C after 100 cycles and 221 mAh/g at 2 C after 500 cycles) and improved rate-capability (192 mAh/g at 5 C), respectively (1 C: 150 mA/g). The superior electrochemical performance of Nb-TiO2-C (1 wt%) could be attributed to the synergistic effect of improved electronic conductivity induced by optimal Nb doping (1 wt%) and lithium-ion penetration (high diffusion kinetics) through unique pore structures.

  18. A novel Ni{sup 2+}-doped Ag{sub 3}PO{sub 4} photocatalyst with high photocatalytic activity and enhancement mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Song, Limin, E-mail: songlmnk@sohu.com [College of Environment and Chemical Engineering, State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Chen, Zewen; Li, Tongtong [College of Environment and Chemical Engineering, State Key Laboratory of Hollow-Fiber Membrane Materials and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387 (China); Zhang, Shujuan, E-mail: zhangshujuan@tust.edu.cn [College of Science, Tianjin University of Science & Technology, Tianjin, 300457 (China)

    2017-01-15

    Ni{sup 2+}-doped Ag{sub 3}PO{sub 4} (Ni{sup 2+}-Ag{sub 3}PO{sub 4}) photocatalysts with superhigh activity for photodegradation of organic pollutants were prepared by a simple hydrothermal method. The photocatalysts were characterized with X-ray powder diffractometry, transmission electron microscopy, ultraviolet–visible absorption spectroscopy, X-ray photoelectron spectroscopy, measurement of total organic carbon, and electron paramagnetic resonance spectrometry. The photocatalysts were evaluated by methyl orange (MO) photodegradation experiments under visible light irradiation (λ > 420 nm). Comparative analysis showed the optimal doping dosage was 0.05 mol/L Ni{sup 2+}. The optimal Ni{sup 2+}-Ag{sub 3}PO{sub 4} has an MO photodegradation rate constant four times larger than pure Ag{sub 3}PO{sub 4}. The photocatalytic ratio of 40 mg/L MO over the optimal Ni{sup 2+}-Ag{sub 3}PO{sub 4} after 10 min is 89%, which indicates excellent photocatalytic ability in high-concentration MO solutions. The Ni{sup 2+} doping into Ag{sub 3}PO{sub 4} can increase the level of band gap, and accelerate the utilization of photons and the separation of photo-generated charges. Therefore, the Ni{sup 2+} doping into Ag{sub 3}PO{sub 4} is responsible for the enhancement of photocatalytic ability. - Highlights: • Ni{sup 2+}-modified with higher photodegradation ability was synthesized. • ·OH radicals were the main active species in the oxidation of MO. • The doping of Ni{sup 2+} in Ag{sub 3}PO{sub 4} is responsible for the enhanced activity.

  19. Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Murawski, Caroline, E-mail: caroline.murawski@iapp.de; Fuchs, Cornelius; Hofmann, Simone; Leo, Karl [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Str. 1, 01062 Dresden (Germany); Gather, Malte C. [Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Str. 1, 01062 Dresden (Germany); SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS Scotland (United Kingdom)

    2014-09-15

    We investigate the properties of N,N′-[(Diphenyl-N,N′-bis)9,9,-dimethyl-fluoren-2-yl]-benzidine (BF-DPB) as hole transport material (HTL) in organic light-emitting diodes (OLEDs) and compare BF-DPB to the commonly used HTLs N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD), 2,2′,7,7′-tetrakis(N,N′-di-p-methylphenylamino)-9,9′-spirobifluorene (Spiro-TTB), and N,N′-di(naphtalene-1-yl)-N,N′-diphenylbenzidine (NPB). The influence of 2,2′-(perfluoronaphthalene-2,6-diylidene)dimalononitrile (F6-TCNNQ p-dopant) concentration in BF-DPB on the operation voltage and efficiency of red and green phosphorescent OLEDs is studied; best results are achieved at 4 wt. % doping. Without any light extraction structure, BF-DPB based red (green) OLEDs achieve a luminous efficacy of 35 .1 lm/W (74 .0 lm/W) at 1000 cd/m{sup 2} and reach a very high brightness of 10 000 cd/m{sup 2} at a very low voltage of 3.2 V (3.1 V). We attribute this exceptionally low driving voltage to the high ionization potential of BF-DPB which enables more efficient hole injection from BF-DPB to the adjacent electron blocking layer. The high efficiency and low driving voltage lead to a significantly lower luminous efficacy roll-off compared to the other compounds and render BF-DPB an excellent HTL material for highly efficient OLEDs.

  20. Self-organized multi-layered graphene-boron-doped diamond hybrid nanowalls for high-performance electron emission devices.

    Science.gov (United States)

    Sankaran, Kamatchi Jothiramalingam; Ficek, Mateusz; Kunuku, Srinivasu; Panda, Kalpataru; Yeh, Chien-Jui; Park, Jeong Young; Sawczak, Miroslaw; Michałowski, Paweł Piotr; Leou, Keh-Chyang; Bogdanowicz, Robert; Lin, I-Nan; Haenen, Ken

    2018-01-18

    Carbon nanomaterials such as nanotubes, nanoflakes/nanowalls, and graphene have been used as electron sources due to their superior field electron emission (FEE) characteristics. However, these materials show poor stability and short lifetimes, which prevent their use in practical device applications. The aim of this study was to find an innovative nanomaterial possessing both high robustness and reliable FEE behavior. Herein, a hybrid structure of self-organized multi-layered graphene (MLG)-boron doped diamond (BDD) nanowall materials with superior FEE characteristics was successfully synthesized using a microwave plasma enhanced chemical vapor deposition process. Transmission electron microscopy reveals that the as-prepared carbon clusters have a uniform, dense, and sharp nanowall morphology with sp 3 diamond cores encased by an sp 2 MLG shell. Detailed nanoscale investigations conducted using peak force-controlled tunneling atomic force microscopy show that each of the core-shell structured carbon cluster fields emits electrons equally well. The MLG-BDD nanowall materials show a low turn-on field of 2.4 V μm -1 , a high emission current density of 4.2 mA cm -2 at an applied field of 4.0 V μm -1 , a large field enhancement factor of 4500, and prominently high lifetime stability (lasting for 700 min), which demonstrate the superiority of these materials over other hybrid nanostructured materials. The potential of these MLG-BDD hybrid nanowall materials in practical device applications was further illustrated by the plasma illumination behavior of a microplasma device with these materials as the cathode, where a low threshold voltage of 330 V (low threshold field of 330 V mm -1 ) and long plasma stability of 358 min were demonstrated. The fabrication of these hybrid nanowalls is straight forward and thereby opens up a pathway for the advancement of next-generation cathode materials for high brightness electron emission and microplasma-based display devices.

  1. Studies on the oxygen precipitation in highly boron doped silicon; Untersuchungen zur Sauerstoffausscheidung in hoch bordotiertem Silicium

    Energy Technology Data Exchange (ETDEWEB)

    Zschorsch, Markus

    2007-12-14

    The aim of this thesis was the getting of new knowledge on the elucidation of the oxygen precipitation in highly doped silicon. In the study of the early phases of the oxygen precipitation boron-oxygen complexes and their kinetics could be indirectly detected. These arise already during the cooling of the crystal and can be destroyed by subsequent temperature processes. The formation of the here as BO assumed species during the cooling after the silicon crystal fabrication could be numerically reproduced. Furthermore the study of early precipitation phases by means of neutron small angle scattering a maximum of the oxygen precipitation at {rho}=9 m{omega}cm. It could be shown that the decreasing of this at increasing boron concentration can be most probably reduced to boron precipitations. Furthermore it could be shown that after a tempering time of 24 hours at 700 C in silicon with {rho}=9 m{omega}cm platelet-shaped precipitates form. By the study of the precipitate growth could be shown that also in this phase the oxygen precipitation in silicon is strongest with a specific resistance of {rho}=9 m{omega}cm. By means of FTIR spectroscopy a new absorption band at a wave number of 1038 cm{sup -1} was found, which could be assigned to a boron species. By different experiments it is considered as probable that at this species it deals with BI respectively B{sub 2}I complexes.

  2. Antimony Anchored with Nitrogen-Doping Porous Carbon as a High-Performance Anode Material for Na-Ion Batteries.

    Science.gov (United States)

    Wu, Tianjing; Hou, Hongshuai; Zhang, Chenyang; Ge, Peng; Huang, Zhaodong; Jing, Mingjun; Qiu, Xiaoqing; Ji, Xiaobo

    2017-08-09

    Antimony represents a class of unique functional materials in sodium-ion batteries with high theoretical capacity (660 mA h g -1 ). The utilization of carbonaceous materials as a buffer layer has been considered an effective approach to alleviate rapid capacity fading. Herein, the antimony/nitrogen-doping porous carbon (Sb/NPC) composite with polyaniline nanosheets as a carbon source has been successfully achieved. In addition, our strategy involves three processes, a tunable organic polyreaction, a thermal annealing process, and a cost-effective reduction reaction. The as-prepared Sb/NPC electrode demonstrates a great reversible capacity of 529.6 mA h g -1 and an outstanding cycling stability with 97.2% capacity retention after 100 cycles at 100 mA g -1 . Even at 1600 mA g -1 , a superior rate capacity of 357 mA h g -1 can be retained. Those remarkable electrochemical performances can be ascribed to the introduction of a hierarchical porous NPC material to which tiny Sb nanoparticles of about 30 nm were well-wrapped to buffer volume expansion and improve conductivity.

  3. High quality aluminium doped zinc oxide target synthesis from nanoparticulate powder and characterisation of sputtered thin films

    Energy Technology Data Exchange (ETDEWEB)

    Isherwood, P.J.M., E-mail: P.J.M.Isherwood@lboro.ac.uk [Centre for Renewable Energy Systems Technology, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom); Neves, N. [Innovnano, S. A., Rua Coimbra Inovação Parque, IParque Lote 13, 3040-570 Antanhol, Coimbra (Portugal); Bowers, J.W. [Centre for Renewable Energy Systems Technology, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom); Newbatt, P. [Innovnano, S. A., Rua Coimbra Inovação Parque, IParque Lote 13, 3040-570 Antanhol, Coimbra (Portugal); Walls, J.M. [Centre for Renewable Energy Systems Technology, Loughborough University, Loughborough, Leicestershire LE11 3TU (United Kingdom)

    2014-09-01

    Nanoparticulate aluminium-doped zinc oxide powder was synthesised through detonation and subsequent rapid quenching of metallic precursors. This technique allows for precise compositional control and rapid nanoparticle production. The resulting powder was used to form sputter targets, which were used to deposit thin films by radio frequency sputtering. These films show excellent sheet resistance and transmission values for a wide range of deposition temperatures. Crystal structure analysis shows that crystals in the target have a random orientation, whereas the crystals in the films grow perpendicular to the substrate surface and propagate preferentially along the (002) axis. Higher temperature deposition reduces crystal quality with a corresponding decrease in refractive index and an increase in sheet resistance. Films deposited between room temperature and 300 °C were found to have sheet resistances equivalent to or better than indium tin oxide films for a given average transmission value. - Highlights: • Nanoparticulate AZO powder was used to produce sputter targets. • The powder synthesis technique allows for precise compositional control. • Sputtered films show excellent optical, electronic and structural properties. • High temperature films show reduced electrical and structural quality. • For a given transmission, films show equivalent sheet resistances to ITO.

  4. Nitrogen–doped graphitized carbon shell encapsulated NiFe nanoparticles: A highly durable oxygen evolution catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Du, Lei; Luo, Langli; Feng, Zhenxing; Engelhard, Mark; Xie, Xiaohong; Han, Binghong; Sun, Junming; Zhang, Jianghao; Yin, Geping; Wang, Chongmin; Wang, Yong; Shao, Yuyan

    2017-09-01

    Oxygen evolution reaction (OER) plays a crucial role in various energy conversion devices such as water electrolyzers and metal–air batteries. Precious metal catalysts such as Ir, Ru and their oxides are usually used for enhancing reaction kinetics but are limited by their scarce resource. The challenges associated with alternative non–precious metal catalysts such as transition metal oxides and (oxy)hydroxides etc. are their low electronic conductivity and durability. Herein, we report a highly active (360 mV overpotential at 10 mA cm–2GEO) and durable (no degradation after 20000 cycles) OER catalyst derived from bimetallic metal–organic frameworks (MOFs) precursors. This catalyst consists of NiFe nanoparticles encapsulated by nitrogen–doped graphitized carbon shells. The electron-donation/deviation from Fe and tuned electronic structure of metal cores by Ni are revealed to be primary contributors to the enhanced OER activity, whereas N concentration contributes negligibly. We further demonstrated that the structure and morphology of encapsulating carbon shells, which are the key factors influencing the durability, are facilely controlled by the chemical state of precursors.

  5. Scandium doped Ge2Sb2Te5 for high-speed and low-power-consumption phase change memory

    Science.gov (United States)

    Wang, Yong; Zheng, Yonghui; Liu, Guangyu; Li, Tao; Guo, Tianqi; Cheng, Yan; Lv, Shilong; Song, Sannian; Ren, Kun; Song, Zhitang

    2018-03-01

    To bridge the gap of access time between memories and storage systems, the concept of storage class memory has been put forward based on emerging nonvolatile memory technologies. For all the nonvolatile memory candidates, the unpleasant tradeoff between operation speed and retention seems to be inevitable. To promote both the write speed and the retention of phase change memory (PCM), Sc doped Ge2Sb2Te5 (SGST) has been proposed as the storage medium. Octahedral Sc-Te motifs, acting as crystallization precursors to shorten the nucleation incubation period, are the possible reason for the high write speed of 6 ns in PCM cells, five-times faster than that of Ge2Sb2Te5 (GST) cells. Meanwhile, an enhanced 10-year data retention of 119 °C has been achieved. Benefiting from both the increased crystalline resistance and the inhibited formation of the hexagonal phase, the SGST cell has a 77% reduction in power consumption compared to the GST cell. Adhesion of the SGST/SiO2 interface has been strengthened, attributed to the reduced stress by forming smaller grains during crystallization, guaranteeing the reliability of the device. These improvements have made the SGST material a promising candidate for PCM application.

  6. Size-Dependent Electrocatalytic Activity of Gold Nanoparticles on HOPG and Highly Boron-Doped Diamond Surfaces

    Directory of Open Access Journals (Sweden)

    Tine Brülle

    2011-12-01

    Full Text Available Gold nanoparticles were prepared by electrochemical deposition on highly oriented pyrolytic graphite (HOPG and boron-doped, epitaxial 100-oriented diamond layers. Using a potentiostatic double pulse technique, the average particle size was varied in the range from 5 nm to 30 nm in the case of HOPG as a support and between < 1 nm and 15 nm on diamond surfaces, while keeping the particle density constant. The distribution of particle sizes was very narrow, with standard deviations of around 20% on HOPG and around 30% on diamond. The electrocatalytic activity towards hydrogen evolution and oxygen reduction of these carbon supported gold nanoparticles in dependence of the particle sizes was investigated using cyclic voltammetry. For oxygen reduction the current density normalized to the gold surface (specific current density increased for decreasing particle size. In contrast, the specific current density of hydrogen evolution showed no dependence on particle size. For both reactions, no effect of the different carbon supports on electrocatalytic activity was observed.

  7. Integration and High-Temperature Characterization of Ferroelectric Vanadium-Doped Bismuth Titanate Thin Films on Silicon Carbide

    Science.gov (United States)

    Ekström, Mattias; Khartsev, Sergiy; Östling, Mikael; Zetterling, Carl-Mikael

    2017-07-01

    4H-SiC electronics can operate at high temperature (HT), e.g., 300°C to 500°C, for extended times. Systems using sensors and amplifiers that operate at HT would benefit from microcontrollers which can also operate at HT. Microcontrollers require nonvolatile memory (NVM) for computer programs. In this work, we demonstrate the possibility of integrating ferroelectric vanadium-doped bismuth titanate (BiTV) thin films on 4H-SiC for HT memory applications, with BiTV ferroelectric capacitors providing memory functionality. Film deposition was achieved by laser ablation on Pt (111)/TiO2/4H-SiC substrates, with magnetron-sputtered Pt used as bottom electrode and thermally evaporated Au as upper contacts. Film characterization by x-ray diffraction analysis revealed predominately (117) orientation. P- E hysteresis loops measured at room temperature showed maximum 2 P r of 48 μC/cm2, large enough for wide read margins. P- E loops were measurable up to 450°C, with losses limiting measurements above 450°C. The phase-transition temperature was determined to be about 660°C from the discontinuity in dielectric permittivity, close to what is achieved for ceramics. These BiTV ferroelectric capacitors demonstrate potential for use in HT NVM applications for SiC digital electronics.

  8. Synthesis of nitrogen-doped mesoporous carbon from polyaniline with an F127 template for high-performance supercapacitors

    Science.gov (United States)

    Xin, Guoxiang; Wang, Yanhui; Jia, Shaopei; Tian, Pengfei; Zhou, Shuyu; Zang, Jianbing

    2017-11-01

    N-doped mesoporous carbons (N-MCs) were synthesized via the oxypolymerization of aniline with a Pluronic F127 template, sintering at 850 °C in N2 atmosphere, and activation in a KOH solution. The contrast experiments were carried out without the addition of F127 and the obtained sample was defined as N-Cs. The Brunaner-Emmett-Teller measurement, pore size distribution measurements, transmission electron microscopy, and X-ray photoelectron spectroscopy of N-MCs and N-Cs were performed. The specific areas of the N-MCs and N-Cs reached 721 and 394 m2 g-1, respectively. The specific capacitances of the N-MCs and N-Cs were as high as 318 and 106 F g-1 at 0.2 A g-1. The cycle life of N-MCs at different current densities was above 96% after 5000 cycles of charging and discharging, indicating that the N-MCs had excellent cycle stability.

  9. Mo-doped Na3V2(PO4)3@C composites for high stable sodium ion battery cathode

    Science.gov (United States)

    Wang, Xiaoxiao; Wang, Wanwan; Zhu, Baichuan; Qian, Fangfang; Fang, Zhen

    2018-03-01

    NASICON-type Na3V2(PO4)3 (NVP) with superior electrochemical performance has attracted enormous attention with the development of sodium ion batteries. The structural aggregation as well as poor conductivity of NVP hinder its application in high rate perforamance cathode with long stablity. In this paper, Na3V2- x Mo x (PO4)3@C was successfully prepared through two steps method, including sol-gel and solid state thermal reduction. The optimal doping amount of Mo was defined by experiment. When x was 0.15, the Na3V1.85Mo0.15(PO4)3@C sample has the best cycle performance and rate performance. The discharge capacity of Na3V1.85Mo0.15(PO4)3@C could reach 117.26 mA·h·g-1 at 0.1 C. The discharge capacity retention was found to be 94.5% after 600 cycles at 5 C.

  10. Nitrogen-Doped Carbon Nanofiber/Molybdenum Disulfide Nanocomposites Derived from Bacterial Cellulose for High-Efficiency Electrocatalytic Hydrogen Evolution Reaction.

    Science.gov (United States)

    Lai, Feili; Miao, Yue-E; Huang, Yunpeng; Zhang, Youfang; Liu, Tianxi

    2016-02-17

    To remit energy crisis and environmental deterioration, non-noble metal nanocomposites have attracted extensive attention, acting as a fresh kind of cost-effective electrocatalysts for hydrogen evolution reaction (HER). In this work, hierarchically organized nitrogen-doped carbon nanofiber/molybdenum disulfide (pBC-N/MoS2) nanocomposites were successfully prepared via the combination of in situ polymerization, high-temperature carbonization process, and hydrothermal reaction. Attributing to the uniform coating of polyaniline on the surface of bacterial cellulose, the nitrogen-doped carbon nanofiber network acts as an excellent three-dimensional template for hydrothermal growth of MoS2 nanosheets. The obtained hierarchical pBC-N/MoS2 nanocomposites exhibit excellent electrocatalytic activity for HER with small overpotential of 108 mV, high current density of 8.7 mA cm(-2) at η = 200 mV, low Tafel slope of 61 mV dec(-1), and even excellent stability. The greatly improved performance is benefiting from the highly exposed active edge sites of MoS2 nanosheets, the intimate connection between MoS2 nanosheets and the highly conductive nitrogen-doped carbon nanofibers and the three-dimensional networks thus formed. Therefore, this work provides a novel strategy for design and application of bacterial cellulose and MoS2-based nanocomposites as cost-effective HER eletrocatalysts.

  11. Homologous Catalysts Based on Fe-Doped CoP Nanoarrays for High-Performance Full Water Splitting under Benign Conditions.

    Science.gov (United States)

    Ma, Min; Zhu, Guilei; Xie, Fengyu; Qu, Fengli; Liu, Zhiang; Du, Gu; Asiri, Abdullah M; Yao, Yadong; Sun, Xuping

    2017-08-24

    The design and development of earth-abundant electrocatalysts for efficient full water splitting under mild conditions are highly desired, yet remain a challenging task. A homologous Fe-doped Co-based nanoarray incorporating complementary catalysts is shown to effect high-performance and durable water splitting in near-neutral media. Iron-doped cobalt phosphate borate nanoarray on carbon cloth (Fe-Co-Pi-Bi/CC) derived from iron-doped cobalt phosphide on CC (Fe-CoP/CC) through oxidative polarization behaves as a highly active bimetallic electrocatalyst for water oxidation with an overpotential of 382 mV to afford a catalytic current density of 10 mA cm -2 in 0.1 m potassium borate (K-Bi, pH 9.2). Fe-CoP/CC is also highly active for the hydrogen evolution reaction, capable of driving 10 mA cm -2 at an overpotential of only 175 mV in 0.1 m K-Bi. A two-electrode water electrolyzer incorporating Fe-Co-Pi-Bi/CC as anode and Fe-CoP/CC as cathode achieves 10 mA cm -2 water-splitting current at a cell voltage of 1.95 V with strong long-term electrochemical durability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Characterization of a fiber Bragg grating in pure-silica-core and Ge-doped-core optical fiber under high-temperature strain

    Science.gov (United States)

    Zhang, Yumin; Ding, Xudong; Song, Yanming; Dong, Mingli; Zhu, Lianqing

    2018-03-01

    The characterization of a fiber Bragg grating in pure-silica-core and Ge-doped-core optical fiber is demonstrated under tensile strain at different temperatures. The peak wavelength of the fiber Bragg grating increases slowly under tensile strain of 1000 µε when the temperature exceeds a certain value. The wavelength response of the pure-silica-core fiber Bragg grating is less sensitive under the same high-temperature strain as compared with the Ge-doped-core one. The results show a little predominance for the pure-silica-core fiber Bragg grating in high-temperature strain sensing. The two kinds of fiber Bragg grating are capable of measuring temperatures of up to 800 °C, but it is recommended that strain measurements are conducted below 500 °C to ensure good stability and repeatability.

  13. Influence of B4C-doping and high-energy ball milling on phase formation and critical current density of (Bi,Pb)-2223 HTS

    Science.gov (United States)

    Margiani, N. G.; Mumladze, G. A.; Adamia, Z. A.; Kuzanyan, A. S.; Zhghamadze, V. V.

    2018-05-01

    In this paper, the combined effects of B4C-doping and planetary ball milling on the phase evolution, microstructure and transport properties of Bi1.7Pb0.3Sr2Ca2Cu3Oy(B4C)x HTS with x = 0 ÷ 0.125 were studied through X-ray diffraction (XRD), scanning electron microscopy (SEM), resistivity and critical current density measurements. Obtained results have shown that B4C additive leads to the strong acceleration of high-Tc phase formation and substantial enhancement in Jc. High-energy ball milling seems to produce a more homogeneous distribution of refined doped particles in the (Bi,Pb)-2223 HTS which results in an improved intergranular flux pinning and better self-field Jc performance.

  14. Tm3+-doped barium gallo-germanate glass single-mode fiber with high gain per unit length for ultracompact 1.95 µm laser

    Science.gov (United States)

    Tang, Guowu; Wen, Xin; Huang, Kaimin; Qian, Guoquan; Lin, Wei; Cheng, Huihui; Jiang, Licheng; Qian, Qi; Yang, Zhongmin

    2018-03-01

    Heavily Tm3+-doped barium gallo-germanate glass single-mode (SM) fibers were successfully drawn. A gain per unit length of 3.6 dB/cm at 1.95 µm was obtained. To the best of our knowledge, this is the highest gain per unit length reported for Tm3+-doped germanate glass SM fibers. A single-frequency fiber laser operating at 1.95 µm has been built using a 1.5-cm-long active fiber pumped by a 1568 nm fiber laser. The direct output power from the ultracompact laser cavity is 227 mW. The results show that the fibers are highly promising for high-power and ultracompact single-frequency laser applications.

  15. Toward Highly Efficient Electrocatalyst for Li–O 2 Batteries Using Biphasic N-Doping Cobalt@Graphene Multiple-Capsule Heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Guoqiang; Chong, Lina; Amine, Rachid; Lu, Jun; Liu, Cong; Yuan, Yifei; Wen, Jianguo [Center; He, Kun; Bi, Xuanxuan; Guo, Yuanyuan; Wang, Hsien-Hau; Shahbazian-Yassar, Reza; Al Hallaj, Said; Miller, Dean J. [Center; Liu, Dijia; Amine, Khalil

    2017-04-10

    For the promotion of lithium oxygen batteries available for :practical applications, the development of advanced cathode catalysts with low-high activity, and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@grapbene Multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium oxygen cells. 'The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electroactive zones possible; furthermore the colander-like porous electrode facilitates the oxygen diffusion, catalytic reaction,and stable deposition of discharge products. As a result, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.

  16. Ga-Doped Pt-Ni Octahedral Nanoparticles as a Highly Active and Durable Electrocatalyst for Oxygen Reduction Reaction.

    Science.gov (United States)

    Lim, JeongHoon; Shin, Hyeyoung; Kim, MinJoong; Lee, Hoin; Lee, Kug-Seung; Kwon, YongKeun; Song, DongHoon; Oh, SeKwon; Kim, Hyungjun; Cho, EunAe

    2018-04-11

    Bimetallic PtNi nanoparticles have been considered as a promising electrocatalyst for oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs) owing to their high catalytic activity. However, under typical fuel cell operating conditions, Ni atoms easily dissolve into the electrolyte, resulting in degradation of the catalyst and the membrane-electrode assembly (MEA). Here, we report gallium-doped PtNi octahedral nanoparticles on a carbon support (Ga-PtNi/C). The Ga-PtNi/C shows high ORR activity, marking an 11.7-fold improvement in the mass activity (1.24 A mg Pt -1 ) and a 17.3-fold improvement in the specific activity (2.53 mA cm -2 ) compared to the commercial Pt/C (0.106 A mg Pt -1 and 0.146 mA cm -2 ). Density functional theory calculations demonstrate that addition of Ga to octahedral PtNi can cause an increase in the oxygen intermediate binding energy, leading to the enhanced catalytic activity toward ORR. In a voltage-cycling test, the Ga-PtNi/C exhibits superior stability to PtNi/C and the commercial Pt/C, maintaining the initial Ni concentration and octahedral shape of the nanoparticles. Single cell using the Ga-PtNi/C exhibits higher initial performance and durability than those using the PtNi/C and the commercial Pt/C. The majority of the Ga-PtNi nanoparticles well maintain the octahedral shape without agglomeration after the single cell durability test (30,000 cycles). This work demonstrates that the octahedral Ga-PtNi/C can be utilized as a highly active and durable ORR catalyst in practical fuel cell applications.

  17. Core-shell N-doped active carbon fiber@graphene composites for aqueous symmetric supercapacitors with high-energy and high-power density

    Science.gov (United States)

    Xie, Qinxing; Bao, Rongrong; Xie, Chao; Zheng, Anran; Wu, Shihua; Zhang, Yufeng; Zhang, Renwei; Zhao, Peng

    2016-06-01

    Graphene wrapped nitrogen-doped active carbon fibers (ACF@GR) of a core-shell structure were successfully prepared by a simple dip-coating method using natural silk as template. Compared to pure silk active carbon, the as-prepared ACF@GR composites exhibit high specific surface area in a range of 1628-2035 m2 g-1, as well as superior energy storage capability, an extremely high single-electrode capacitance of 552.8 F g-1 was achieved at a current density of 0.1 A g-1 in 6 M KOH aqueous electrolyte. The assembled aqueous symmetric supercapacitors are capable of deliver both high energy density and high power density, for instance, 17.1 Wh kg-1 at a power density of 50.0 W kg-1, and 12.2 Wh kg-1 at 4.7 kW kg-1 with a retention rate of 71.3% for ACF@GR1-based supercapacitor.

  18. Highly Efficient Electrocatalysts for Oxygen Reduction Reaction Based on 1D Ternary Doped Porous Carbons Derived from Carbon Nanotube Directed Conjugated Microporous Polymers

    KAUST Repository

    He, Yafei

    2016-10-11

    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.One-dimensional (1D) porous materials have shown great potential for gas storage and separation, sensing, energy storage, and conversion. However, the controlled approach for preparation of 1D porous materials, especially porous organic materials, still remains a great challenge due to the poor dispersibility and solution processability of the porous materials. Here, carbon nanotube (CNT) templated 1D conjugated microporous polymers (CMPs) are prepared using a layer-by-layer method. As-prepared CMPs possess high specific surface areas of up to 623 m2 g-1 and exhibit strong electronic interactions between p-type CMPs and n-type CNTs. The CMPs are used as precursors to produce heteroatom-doped 1D porous carbons through direct pyrolysis. As-produced ternary heteroatom-doped (B/N/S) 1D porous carbons possess high specific surface areas of up to 750 m2 g-1, hierarchical porous structures, and excellent electrochemical-catalytic performance for oxygen reduction reaction. Both of the diffusion-limited current density (4.4 mA cm-2) and electron transfer number (n = 3.8) for three-layered 1D porous carbons are superior to those for random 1D porous carbon. These results demonstrate that layered and core-shell type 1D CMPs and related heteroatom-doped 1D porous carbons can be rationally designed and controlled prepared for high performance energy-related applications.

  19. Inverted Planar Perovskite Solar Cells with a High Fill Factor and Negligible Hysteresis by the Dual Effect of NaCl-Doped PEDOT:PSS.

    Science.gov (United States)

    Hu, Lijun; Sun, Kuan; Wang, Ming; Chen, Wei; Yang, Bo; Fu, Jiehao; Xiong, Zhuang; Li, Xinyi; Tang, Xiaosheng; Zang, Zhigang; Zhang, Shupeng; Sun, Lidong; Li, Meng

    2017-12-20

    The performance of inverted perovskite solar cells is highly dependent on hole extraction and surface properties of hole transport layers. To highlight the important role of hole transport layers, a facile and simple method is developed by adding sodium chloride (NaCl) into poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The average power conversion efficiency of the perovskite solar cells prepared on NaCl-doped PEDOT:PSS is 17.1% with negligible hysteresis, compared favorably to the control devices (15.1%). Particularly, they exhibit markedly improved V oc and fill factor (FF), with the best FF as high as 81.9%. The enhancement of photovoltaic performance is ascribed to two effects. Better conductivity and hole extraction of PEDOT:PSS are observed after NaCl doping. More intriguingly, the perovskite polycrystalline film shows a preferred orientation along the (001) direction on NaCl-doped PEDOT:PSS, leading to a more uniform thin film. The comparison of the crystal structure between NaCl and MAPbCl 3 indicates a lattice constant mismatch less than 2% and a matched chlorine atom arrangement on the (001) surface, which implies that the NaCl crystallites on the top surface of PEDOT:PSS might serve as seeds guiding the growth of perovskite crystals. This simple method is fully compatible with printing technologies to mass-produce perovskite solar cells with high efficiency and tunable crystal orientations.

  20. Hydrothermal synthesis of Mn-doped ZnCo2O4 electrode material for high-performance supercapacitor

    Science.gov (United States)

    Mary, A. Juliet Christina; Bose, A. Chandra

    2017-12-01

    Mn-doped ZnCo2O4 nanoparticle has been synthesized by hydrothermal method without adding any surfactants. Structural, morphological and electrochemical performances have been studied for the pure and various concentration of Mn-doped ZnCo2O4 nanoparticles. XRD and Raman studies demonstrate the crystalline structure of the material. Specific capacitance of the 10 wt% Mn doped ZnCo2O4 nanomaterial is analysed using the three-electrode system. 10 wt% Mn-doped ZnCo2O4 has a maximum capacitance of 707.4 F g-1 at a current density of 0.5 A g-1. Coulombic efficiency of the material is 96.3% for 500 cycles in the KOH electrolyte medium. A two-electrode device using 10 wt% Mn-doped ZnCo2O4 exhibits the highest specific capacitance of 6.5 F g-1 at a current density of 0.03 A g-1 which is the suitable material for supercapacitor application.

  1. Fabrication of water-dispersible and highly conductive PSS-doped PANI/graphene nanocomposites using a high-molecular weight PSS dopant and their application in H2S detection

    Science.gov (United States)

    Cho, Sunghun; Lee, Jun Seop; Jun, Jaemoon; Kim, Sung Gun; Jang, Jyongsik

    2014-11-01

    This work describes the fabrication of poly(4-styrenesulfonic acid)-doped polyaniline/graphene (PSS-doped PANI/graphene) nanocomposites and their use as sensing elements for hydrogen sulfide (H2S) detection. PSS with a weight-average molecular weight (Mw) of 1.96 × 106 was synthesized using low-temperature free-radical polymerization. The PSS was used as both a doping agent and a binding agent for the polymerization of aniline monomers in a biphasic system (water-chloroform) at -50 °C. The high Mw of PSS resulted in relatively large particle sizes and smooth surfaces of the PSS-doped PANI. These physical characteristics, in turn, resulted in low interparticle resistance and high conductivity. In addition, the PSS allowed homogeneous dispersion of reduced graphene sheets through electrostatic repulsion. The prepared PSS-doped PANI/graphene solutions showed good compatibility with flexible poly(ethylene terephthalate) (PET) substrates, making them suitable for flexible sensor electrodes. Changes in the charge-transport properties, such as protonation level, conjugation length, crystalline structure, and charge-transfer resistance, of the electrode materials were the main factors influencing the electrical and sensor performance of the PSS-doped PANI-based electrodes. PSS-doped PANI/graphene composites containing 30 wt% graphene showed the highest conductivity (168.4 S cm-1) and the lowest minimum detection level (MDL) for H2S gas (1 ppm). This result is consistent with the observed improvements in charge transport in the electrode materials via strong π-π stacking interactions between the PANI and the graphene sheets.This work describes the fabrication of poly(4-styrenesulfonic acid)-doped polyaniline/graphene (PSS-doped PANI/graphene) nanocomposites and their use as sensing elements for hydrogen sulfide (H2S) detection. PSS with a weight-average molecular weight (Mw) of 1.96 × 106 was synthesized using low-temperature free-radical polymerization. The PSS was

  2. Capacitance–voltage and current–voltage characteristics for the study of high background doping and conduction mechanisms in GaAsN grown by chemical beam epitaxy

    International Nuclear Information System (INIS)

    Bouzazi, Boussairi; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi

    2013-01-01

    Highlights: ► The cause of high background doping was confirmed and characterized. ► The current–voltage characteristics deviate from the thermionic emission. ► The recombination current is attributed to a hole trap (E V + 0.52 eV). ► The hole trap (E V + 0.52 eV) was confirmed by DLTS measurements. -- Abstract: The temperature dependence of capacitance–voltage (C–V) and current voltage (I–V) characteristics were used to study the cause of high background doping and the underlying current transport mechanisms in GaAsN Schottky diode grown by chemical beam epitaxy (CBE). In one hand, a nitrogen-related sigmoid increase of junction capacitance and ionized acceptor concentration was observed in the temperature range 70–100 K and was attributed to the thermal ionization of a nitrogen–hydrogen-related deep acceptor-state, with thermal activation energy of approximately 0.11 eV above the valence band maximum (VBM) of GaAsN. This acceptor state is mainly responsible for the high background doping in unintentionally doped GaAsN grown by CBE. On the other hand, the I–V characteristics at different temperatures were found to deviate from the well known pure thermionic-emission mechanism. Based on their fitting at each temperature, the recombination current in the space charge region of GaAsN Schottky diode was mainly attributed to a hole trap, localized at 0.51 eV above the VBM. Given the accuracy of measurements, this result was confirmed by deep level transient spectroscopy measurements. Nevertheless, considering the Shockley–Read–Hall model of generation-recombination, the recombination activity of this defect was quantified and qualified to be weak compared with the markedly degradation of minority carrier lifetime in GaAsN material

  3. MT. BIGELOW 61-INCH IMAGES OF 9P/TEMPEL 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains 6 images of 9P/Tempel 1 obtained on five nights in 1994 using a visual CCD mounted on the 61-inch Kuiper telescope of the Mt. Bigelow...

  4. Project W320 52-inch diameter equipment container load test: Test report

    International Nuclear Information System (INIS)

    Bellomy, J.R.

    1995-01-01

    This test report summarizes testing activities and documents the results of the load tests performed on-site and off-site to structural qualify the 52-inch equipment containers designed and fabricated under Project W-320

  5. Enhancement of Upper Shelf Energy through Delamination Fracture in 0.05 pct P Doped High-Strength Steel

    Science.gov (United States)

    Jafari, Meysam; Kimura, Yuuji; Tsuzaki, Kaneaki

    2012-07-01

    An ultrafine elongated grain (UFEG) structure with strong //rolling direction (RD) fiber deformation texture was produced by warm-caliber rolling at 773 K (500 °C) and final tempering at 823 K (550 °C), namely tempforming in the 1200 MPa-class, medium-carbon, low-alloy steel with phosphorus (P) content of 0.053 wt pct. Charpy impact tests and tensile tests were performed at a temperature range of 77 K (-196 °C) to 623 K (350 °C) on the tempformed (TF) samples along with a conventional quenched and tempered (QT) samples. The QT structure showed a low upper shelf energy of 70 J and a high ductile-to-brittle transition temperature (DBTT) of 373 K (100 °C) as a result of P segregation and intergranular fracture. A remarkable increase in the upper shelf energy to 150 J from 70 J and a low DBTT of approximately 103 K (-170 °C) were obtained in the UFEG structure. P segregation embrittlement disappeared completely in the UFEG structure, and ductile fracture on the planes normal to RD along with delamination fracture on the planes along RD were observed at a temperature range of 123 K (-150 °C) to 423 K (150 °C). The enhanced delamination occurred because of the microstructural anisotropy of the UFEG structure, a strong //RD fiber deformation texture, and interfaces ( i.e. ferrite grain boundaries and cementite particles-ferrite matrix interfaces) weakened by P segregation as feasible crack propagation paths. We studied the delamination (crack-arrester-type) fracture in 0.053 pct P doped high-strength steel along with upper shelf energy and DBTT obtained from the UFEG structure.

  6. High-Performance Spray-Deposited Indium Doped ZnO Thin Film: Structural, Morphological, Electrical, Optical, and Photoluminescence Study

    Science.gov (United States)

    Asl, Hassan Zare; Rozati, Seyed Mohammad

    2018-03-01

    In this study, high-quality indium doped zinc oxide thin films were deposited using the spray pyrolysis technique, and the substrate temperature varied from 450°C to 550°C with steps of 25°C with the aim of investigating the effect of substrate temperature. It was found that as the temperature increased, the resistivity of the films decreased to the extent that it was as low as 5.34 × 10-3 Ω cm for the one deposited at 500°C; however, it slightly increased for the resulting film at 550°C. Although the carrier concentration mostly increased with temperature, it appeared that the carrier mobility was the parameter mainly governing the conductivity variation. In addition, the average transparency of the deposited films at 500°C, 525°C and 550°C was around 87% (400-800 nm), which makes them outstanding transparent conductive oxide films. Moreover, the crystallite size and strain of the resulting films were estimated via the Williamson-Hall method. The results revealed a considerable reduction in the crystallite size and strain up to 500°C followed by a rise at higher substrate temperature. Based on both the surface and cross-section field emission scanning electron microscope images, the film resulting at 500°C was highly compacted and crack free, which can explain the enlargement of the carrier mobility (10.9 cm2 V-1 s-1) in this film. Finally, a detailed photoluminescence study revealed several peaks in the spectrum and the variation of the two major peaks appeared to have correlation with the carrier concentration.

  7. Highly Yb-doped KGd(WO4)2 thin-film amplifier

    NARCIS (Netherlands)

    Yong, Yean Sheng; Aravazhi, S.; Vázquez-Córdova, Sergio Andrés; García Blanco, Sonia Maria; Pollnau, Markus

    We report record-high small-signal gain of 1050 dB/cm at 981 nm wavelength in a KGd0.425Yb0.575(WO4)2 thin film. The sensitivity of gain to the shift of beam-focus position, which is critical under non-waveguiding conditions, is investigated.

  8. High rate performance of LiFePO4 cathode materials co-doped with ...

    Indian Academy of Sciences (India)

    Administrator

    100 nm) for high rate lithium-ion battery cathode application was obtained by microwave heating and using citric acid as carbon source. The ... an interesting cathode material for lithium-ion batteries since it was first proposed by Padhi ... The electrolyte used consisted of a 1 M solution of LiPF6 in a mixture 1: 1 by volume of ...

  9. The high-flux effect on deuterium retention in TiC and TaC doped tungsten at high temperatures

    Science.gov (United States)

    Zibrov, Mikhail; Bystrov, Kirill; Mayer, Matej; Morgan, Thomas W.; Kurishita, Hiroaki

    2017-10-01

    Samples made of tungsten (W) doped either with titanium carbide (W-1.1TiC) or tantalum carbide (W-3.3TaC) were exposed to a low-energy (40 eV/D), high-flux (1.8-5 × 1023 D/m2s) deuterium (D) plasma at temperatures of about800 K, 1050 K, and 1250 K to a fluence of about1 × 1027 D/m2. The deuterium (D) inventory in the samples was examined by nuclear reaction analysis and thermal desorption spectroscopy. At 800 K the D bulk concentrations and total D inventories in W-1.1TiC and W-3.3TaC were more than one order of magnitude higher compared to that in pure polycrystalline W. At 1050 K and 1250 K the D concentrations in all types of samples were very low (≤10-5 at. fr.); however the D inventories in W-1.1TiC were significantly higher compared to those in W-3.3TaC and pure W. It is suggested that D trapping inside the carbide precipitates and at their boundaries is essential at high temperatures and high incident fluxes, especially in W-1.1TiC.

  10. High sensitivity ethanol gas sensor based on Sn - doped ZnO under visible light irradiation at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Peishuo; Pan, Guofeng; Zhang, Bingqiang; Zhen, Jiali; Sun, Yicai, E-mail: pgf@hebut.edu.cn [Institute of Microelectronic, Hebei University of Technology, Tianjin (China)

    2014-07-15

    Pure ZnO and 5at%, 7at%, 9at% Sn - doped ZnO materials are prepared by the chemical co - precipitation method. They were annealed by furnace at temperature range of 300 - 700ºC in air for 1h. The ZnO materials are characterized by X - ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the Sn - doped ZnO materials appear rough porous structures. The maximum sensitivity can be achieved by doping the amount of 7 at%. It has much better sensing performance towards ethanol vapor under visible light irradiation. The response and recovery time are ~1s and ~5s, respectively. The mechanism for the improvement in the sensing properties can be explained with the surface adsorption theory and the photoactivation theory. (author)

  11. Sr-doped Lanthanum Nickelate Nanofibers for High Energy Density Supercapacitors

    International Nuclear Information System (INIS)

    Cao, Yi; Lin, Baoping; Sun, Ying; Yang, Hong; Zhang, Xueqin

    2015-01-01

    Highlights: • The electrode made by LNF-0.7 possessed excellent performance (719 F g −1 ) at Na 2 SO 4 electrolyte • LNF-0.7//LNF-0.7 symmetric supercapacitor device were firstly prepared • The maximum energy density of 81.4 Wh·kg −1 are achieved at a power density of 500W·kg −1 • This symmetric supercapacitor also shows an excellent cycling life - Abstract: The series La x Sr 1−x NiO 3−δ (0.3≤x≤1) nanofibers (LNF-x) samples are prepared by using electrospun method. We investigate the structure and the electrochemical properties of LNF-x in detail. As a result, LNF-x nanofibers present a perovskite structure, and the LNF-0.7 sample with high specific surface area display remarkable performance as an electrode material for supercapacitors. The maximum specific capacitance value of 719 F·g −1 at a current density of 2 A·g −1 , which retains 505 F·g −1 at a high current density of 20 A·g −1 , is obtained for LNF-0.7 electrode in 1 M Na 2 SO 4 aqueous electrolyte. Moreover, the LNF-0.7//LNF-0.7 symmetric supercapacitor device using 1 M Na 2 SO 4 aqueous solution is successfully demonstrated. The capacitor device can operate at a cell voltage as high as 2 V, and it exhibits an energy density of 30.5 Wh·kg −1 at a high power density of 10 kW·kg −1 and a high energy density of 81.4 Wh·kg −1 at a low power density of 500 W·kg −1 . More importantly, this symmetric supercapacitor also shows an excellent cycling performance with 90% specific capacitance retention after 2000 charging and discharging cycles. Those results offer a suitable design of electrode materials for high-performance supercapacitors

  12. A tunable narrow-line-width multi-wavelength Er-doped fiber laser based on a high birefringence fiber ring mirror and an auto-tracking filter

    Science.gov (United States)

    Jia, Xiu-jie; Liu, Yan-ge; Si, Li-bin; Guo, Zhan-cheng; Fu, Sheng-gui; Kai, Gui-yun; Dong, Xiao-yi

    2008-01-01

    A novel multi-wavelength erbium-doped fiber laser operating in C-band is proposed and successfully demonstrated. The wavelength interval between the wavelengths is about 0.22 nm. The 3 dB bandwidth of the laser is about 0.012 nm, and the output power reaches 4.8 mW. By using a high birefringence fiber ring mirror (HiBi-FLM) and a tunable FBG, the laser realizes switchable and tunable characteristic. The mode hopping can be effectively prevented. Moreover, this laser can improve wavelength stability significantly by taking advantage of an un-pumped Er3+-doped fiber at the standing-wave section. The laser can operate in stable narrow-line-width with single-, dual-wavelength, and unstable triple-wavelength output at room temperature.

  13. Rod-like polyaniline supported on three-dimensional boron and nitrogen-co-doped graphene frameworks for high-performance supercapacitors

    Science.gov (United States)

    Liao, Kexuan; Gao, Jialu; Fan, Jinchen; Mo, Yao; Xu, Qunjie; Min, Yulin

    2017-12-01

    In this work, novel three-dimensional (3D) boron and nitrogen-co-doped three-dimensional (3D) graphene frameworks (BN-GFs) supporting rod-like polyaniline (PANI) are facilely prepared and used as electrodes for high-performance supercapacitors. The results demonstrated that BN-GFs with tuned electronic structure can not only provide a large surface area for rod-like PANI to anchor but also effectively facilitate the ion transfer and charge storage in the electrode. The PANI/BN-GF composite with wrinkled boron and nitrogen-co-doped graphene sheets interconnected by rod-like PANI exhibits excellent capacitive properties with a maximum specific capacitance of 596 F/g at a current density of 0.5 A/g. Notably, they also show excellent cycling stability with more than 81% capacitance retention after 5000 charge-discharge cycles.

  14. Sol-Gel to Prepare Nitrogen Doped TiO2 Nanocrystals with Exposed {001} Facets and High Visible-Light Photocatalytic Performance

    Directory of Open Access Journals (Sweden)

    Hui-Ying Ai

    2014-01-01

    Full Text Available A series of N-doped TiO2 nanocrystals with exposed {001} facets was prepared successfully by sol-gel method for the first time. The physicochemical properties of these resultant photocatalysts were characterized by XRD, TEM, XPS, and DRS, and their photocatalytic performances were evaluated by photocatalytic decoloration of methylene blue solution under visible light (λ>420 nm irradiation. The results showed that the N-doped TiO2 nanocrystals with exposed {001} facets showed higher photocatalytic activity than P25. The enhanced photocatalytic performance can be attributed to synergistic effects of several factors, such as good crystallinity, better light response characteristic, and high reactivity of {001} facets.

  15. Partially Hydrogenated Graphene Materials Exhibit High Electrocatalytic Activities Related to Unintentional Doping with Metallic Impurities.

    Science.gov (United States)

    Jankovský, Ondřej; Libánská, Alena; Bouša, Daniel; Sedmidubský, David; Matějková, Stanislava; Sofer, Zdeněk

    2016-06-13

    Partially hydrogenated graphene materials, synthesized by the chemical reduction/hydrogenation of two different graphene oxides using zinc powder in acidic environment or aluminum powder in alkaline environment, exhibit high electrocatalytic activities, as well as electrochemical sensing properties. The starting graphene oxides and the resultant hydrogenated graphenes were characterized in detail. Their electrocatalytic activity was examined in the oxygen reduction reaction, whereas sensing properties towards explosives were tested by using picric acid as a redox probe. Findings indicate that the high electrocatalytic performance originates not only from the hydrogenation of graphene, but also from unintentional contamination of graphene with manganese and other metals during synthesis. A careful evaluation of the obtained data and a detailed chemical analysis are necessary to identify the origin of this anomalous electrocatalytic activity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Comprehensive growth and characterization study on highly n-doped InGaAs as a contact layer for quantum cascade laser applications

    Science.gov (United States)

    Demir, Ilkay; Altuntas, Ismail; Bulut, Baris; Ezzedini, Maher; Ergun, Yuksel; Elagoz, Sezai

    2018-05-01

    We present growth and characterization studies of highly n-doped InGaAs epilayers on InP substrate by metal organic vapor phase epitaxy to use as an n-contact layer in quantum cascade laser applications. We have introduced quasi two-dimensional electrons between 10 s pulsed growth n-doped InGaAs epilayers to improve both carrier concentration and mobility of structure by applying pulsed growth and doping methods towards increasing the Si dopant concentration in InGaAs. Additionally, the V/III ratio optimization under fixed group III source flow has been investigated with this new method to understand the effects on both crystalline quality and electrical properties of n-InGaAs epilayers. Finally, we have obtained high crystalline quality of n-InGaAs epilayers grown by 10 s pulsed as a contact layer with 2.8 × 1019 cm‑3 carrier concentration and 1530 cm2 V‑1 s‑1 mobility.

  17. Effect of paramagnetic manganese ions doping on frequency and high temperature dependence dielectric response of layered Na1.9Li0.1Ti3O7 ceramics

    International Nuclear Information System (INIS)

    Pal, Dharmendra; Pandey, J.L.

    2010-01-01

    The manganese doped layered ceramic samples (Na 1.9 Li 0.1 )Ti 3 O 7 : XMn (0.01 ≤ X ≤ 0.1) have been prepared using high temperature solid state reaction. The room temperature electron paramagnetic resonance (EPR) investigations exhibit that at lower percentage of doping the substitution of manganese ions occur as Mn 3+ at Ti 4+ sites, whereas for higher percentage of doping Mn 2+ ions occupy the two different interlayer sodium/lithium sites. In both cases, the charge compensation mechanism should operate to maintain the overall charge neutrality of the lattice. The manganese doped derivatives of layered Na 1.9 Li 0. 1Ti 3 O 7 (SLT) ceramics have been investigated through frequency dependence dielectric spectroscopy in this work. The results indicate that the dielectric losses in these ceramics are the collective contribution of electric conduction, dipole orientation and space charge polarization. Smeared peaks in temperature dependence of permittivity plots suggest diffuse nature of high temperature ferroelectric phase transition. The light manganese doping in SLT enhances the dielectric constant. However, manganese doping decreases dielectric loss due to inhibition of domain wall motion, enhances electron-hopping conduction, and impedes the interlayer ionic conduction as well. Manganese doping also gives rise to contraction of interlayer space. (author)

  18. High rate performance of LiFePO4 cathode materials co-doped with ...

    Indian Academy of Sciences (India)

    100 nm) for high rate lithium-ion battery cathode application was obtained by microwave heating and using citric acid as carbon source. ... with 5% C and 1% Ti4+ resulted in a specific capacity of 114.95 mAh.g-1 and 102.4 mAh.g-1 at discharge rates of 0.3C and 1C, respectively, and the cycle performance is very good.

  19. A high-resolution neutron powder diffraction study of neodymium doping in barium cerate

    DEFF Research Database (Denmark)

    Knight, K.S.; Bonanos, N.

    1995-01-01

    High-resolution neutron powder diffraction data have been collected on 6 perovskites of composition BaCe1-xNdxO3-x/(2), with 0 less than or equal to x less than or equal to 0.2, in which structural phase transitions Pmcn-->P4/mbm at x=0.05, and P4/mbm-->Pm3m at x=0.1, were inferred from a recent ...

  20. Study of high mobility carriers in Ni-doped CdO films

    Indian Academy of Sciences (India)

    ZnO, SnO2, In2O3 and NiO (Morales and Sanchez 1999;. Hanamoto et al 2001; Lou et al 2009; Gao et al 2011). .... with increasing Ni incorporation attaining a stable value. Figure 4 can be considered as a scale of .... tant finding in the present measurements is the high values of mobility (∼120 cm2/V·s) especially at light ...

  1. Cobalt Doping To Boost the Electrochemical Properties of Ni@Ni3S2Nanowire Films for High-Performance Supercapacitors.

    Science.gov (United States)

    Xu, Shusheng; Wang, Tao; Ma, Yujie; Jiang, Wenkai; Wang, Shuai; Hong, Min; Hu, Nantao; Su, Yanjie; Zhang, Yafei; Yang, Zhi

    2017-10-23

    Metal sulfides have aroused great interest for energy storage. However, their low specific capacities and inferior rate capabilities hinder their practical applications. In this work, a facile cobalt-doping process is used to boost the electrochemical performance of Ni@Ni 3 S 2 core-sheath nanowire film electrodes for high-performance electrochemical energy storage. Co ions are doped successfully and uniformly into Ni 3 S 2 nanosheets through a facile ion-exchange process. The electrochemical properties of film electrodes are improved greatly, and an ultrahigh volumetric capacity (increased from 105 to 730 C cm -3 at 0.25 A cm -3 ) and excellent rate capability are obtained after Co is doped into Ni@Ni 3 S 2 core-sheath nanowires. A hybrid asymmetric supercapacitor with Co-doped Ni@Ni 3 S 2 as the positive electrode and graphene-carbon nanotubes as the negative electrode is assembled and exhibits an ultrahigh volumetric capacitance of 142 F cm -3 (based on the total volume of both electrodes) at 0.5 A cm -3 and excellent cycling stability (only 3 % capacitance decrease after 5000 cycles). Moreover, the volumetric energy density can reach 44.5 mWh cm -3 , which is much larger than those of thin-film lithium batteries (1-10 mWh cm -3 ). These results may provide useful insights for the fabrication of high-performance film electrodes for energy-storage applications. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Relaxation of the Shallow Acceptor Center Magnetic Moment in a Highly Doped Silicon

    CERN Document Server

    Mamedov, T N; Herlach, D; Gorelkin, V N; Gritsaj, K I; Duginov, V N; Kormann, O; Major, J V; Stoikov, A V; Zimmermann, U

    2001-01-01

    Results on the temperature dependence of the residual polarization of negative muons in crystalline silicon with germanium, boron and phosphorus impurities are presented. The measurements were carried out in a magnetic field of 0.1 T transverse to the direction of the muon spin in the temperature range 4.2-300 K. It is found that in a silicon sample with a high concentration of germanium impurity (9\\cdot 10^{19} cm^{-3}), as in the samples of n- and p-type silicon with impurity concentrations up to \\sim 10^{17} cm^{-3}, the relaxation rate \

  3. Monolithic Highly Stable Yb-Doped Femtosecond Fiber Lasers for Applications in Practical Biophotonics

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Turchinovich, Dmitry

    2012-01-01

    Operational and environmental stability of ultrafast laser systems is critical for their applications in practical biophotonics. Mode-locked fiber lasers show great promise in applications such as supercontinuum sources or multiphoton microscopy systems. Recently, substantial progress has been made...... in the development of all-fiber nonlinear-optical laser control schemes, which resulted in the demonstration of highly stable monolithic, i.e., not containing any free-space elements, lasers with direct fiber-end delivery of femtosecond pulses. This paper provides an overview of the progress in the development...

  4. High-Performance Flexible Solid-State Carbon Cloth Supercapacitors Based on Highly Processible N-Graphene Doped Polyacrylic Acid/Polyaniline Composites.

    Science.gov (United States)

    Wang, Yongguang; Tang, Shaochun; Vongehr, Sascha; Syed, Junaid Ali; Wang, Xiangyu; Meng, Xiangkang

    2016-02-17

    Improving the solubility of conductive polymers to facilitate processing usually decreases their conductivity, and they suffer from poor cycling stability due to swelling-shrinking during charging cycles. We circumvent these problems with a novel preparation method for nitrogen-doped graphene (NG) enhanced polyacrylic acid/polyaniline (NG-PAA/PANI) composites, ensuring excellent processibility for scalable production. The content of PANI is maximized under the constraint of still allowing defect-free coatings on filaments of carbon cloth (CC). The NG content is then adjusted to optimize specific capacitance. The optimal CC electrodes have 32 wt.% PANI and 1.3 wt.% NG, thus achieving a high capacitance of 521 F/g at 0.5 F/g. A symmetric supercapacitor made from 20 wt.% PANI CC electrodes has more than four times the capacitance (68 F/g at 1 A/g) of previously reported flexible capacitors based on PANI-carbon nanotube composites, and it retains the full capacitance under large bending angles. The capacitor exhibits high energy and power densities (5.8 Wh/kg at 1.1 kW/kg), a superior rate capability (still 81% of the 1 A/g capacitance at 10 A/g), and long-term electrochemical stability (83.2% retention after 2000 cycles).

  5. Hierarchical nitrogen-doped porous carbon with high surface area derived from endothelium corneum gigeriae galli for high-performance supercapacitor

    International Nuclear Information System (INIS)

    Hong, Xiaoting; Hui, K.S.; Zeng, Zhi; Hui, K.N.; Zhang, Luojiang; Mo, Mingyue; Li, Min

    2014-01-01

    Highlights: • Porous carbons were prepared using endothelium corneum gigeriae galli as precursor. • Surface and structural properties strongly depend on carbonization temperatures. • Resultant carbons possess nitrogen heteroatom and high surface areas. • ECGG-900 sample exhibits excellent electrochemical capacitive performances. - Abstract: Endothelium corneum gigeriae galli derived 3D hierarchical nitrogen-doped porous carbon was for the first time prepared by preliminary carbonization at 450 °C and final KOH activation at high temperatures. The surface and structural properties of the as-synthesized samples are analyzed with Brunauer–Emmett–Teller surface analyzer apparatus, X-Ray Diffractometer, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectrometer. The electrochemical performances are analyzed by cyclic voltammetry, galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy. The obtained results show that the sample carbonized at 900 °C possesses the SSA of 2149.9 m 2 g −1 , average micropore diameter of 1.78 nm, and exhibits the highest initial specific capacitance of 198.0 F g −1 at current density of 1 A g −1 in 6 M KOH solution. It retains good specific capacitance retention of 91.6% after 3000 charge/discharge cycles at current density of 2 A g −1

  6. Studies of performance degradation of a high temperature PEMFC based on H 3PO 4-doped PBI

    Science.gov (United States)

    Liu, Gang; Zhang, Huamin; Hu, Jingwei; Zhai, Yunfeng; Xu, Dongyan; Shao, Zhi-gang

    In this paper, a 600 h life test of a high temperature PEMFC based on phosphoric acid (H 3PO 4)-doped polybenzimidazole (PBI) (H 3PO 4/PBI HT-PEMFC) at a current density of 714 mA cm -2 (the beginning 510 h continuous test) and 300 mA cm -2 (the last 90 h intermittent test) was carried out. After the life test, degradation of the MEA occurred. The H 2 crossover rate through the PBI membrane and the open circuit voltage (OCV) of the cell were tested with time. The results showed that, at the beginning of 510 h continuous test, the PBI membrane did not show much physical degradation, but during the last 90 h test there was a remarkable physical degradation which resulted in a higher H 2 crossover. The catalysts, PBI membranes and the membrane electrode assemblies (MEAs) before and after the life test were comprehensively examined by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). TEM results showed that the particle size of the Pt/C catalysts in the anode and cathode increased from 3.72 to 7.40 and 8.39 nm, respectively. SEM images of MEA in cross-section revealed that the PBI membrane became thin after the life test. EDS analysis implied the leaching of H 3PO 4 from the PBI membrane had occurred. Therefore, we conclude that physical degradation of PBI membrane, agglomeration of the electrocatalysts (both anode and cathode) and the leaching of H 3PO 4 from the PBI membrane were responsible for the performance degradation of the H 3PO 4/PBI HT-PEMFC.

  7. Mechanical Stability of H3PO4-Doped PBI/Hydrophilic-Pretreated PTFE Membranes for High Temperature PEMFCs

    International Nuclear Information System (INIS)

    Park, Jaehyung; Wang, Liang; Advani, Suresh G.; Prasad, Ajay K.

    2014-01-01

    Graphical abstract: - Highlights: • PBI/PTFE membrane was prepared by porous PTFE with hydrophilic surface pretreatment. • The durability of the prepared PBI/PTFE membrane was compared with pure PBI, PBI with untreated PTFE, and PBI-Nafion with untreated PTFE membranes. • Accelerated durability tests and SEM showed improved durability based the PBI/PTFE membrane with pretreated PTFE. - Abstract: A novel polybenzimidazole (PBI)/poly(tetrafluoroethylene) (PTFE) composite membrane doped with phosphoric acid was fabricated for high temperature operation in a polymer electrolyte membrane (PEM) fuel cell. A hydrophilic surface pretreatment was applied to the porous PTFE matrix film to improve its interfacial adhesion to the PBI polymer, thereby avoiding the introduction of Nafion ionomer which is traditionally used as a coupling agent. The pretreated PTFE film was embedded within the composite membrane during solution-casting using 5wt% PBI/DMAc solution. The mechanical stability and durability of three types of MEAs assembled with PBI only, PBI with pretreated PTFE, and PBI-Nafion with untreated PTFE membranes were evaluated under an accelerated degradation testing protocol employing extreme temperature cycling. Degradation was characterized by recording polarization curves, hydrogen crossover, and proton resistance. Cross-sections of the membranes were examined before and after thermal cycling by scanning electron microscope. Energy-dispersive X-ray spectroscopy verified that the PBI is dispersed homogeneously in the porous PTFE matrix. Results show that the PBI composite membrane with pretreated PTFE has a lower degradation rate than the Nafion/PBI membrane with untreated PTFE. Thus, the hydrophilic pretreatment employed here greatly improved the mechanical stability of the composite membrane, which resulted in improved durability under an extreme thermal cycling regime

  8. Characterisation of sensitive Ge-doped silica flat fibre-based thermoluminescence detectors for high resolution radiotherapy dosimetry

    Science.gov (United States)

    Rahim, A. R. Abdul; Zahaimi, N. A.; Zin, H. M.; Bradley, D. A.; Mahdiraji, G. A.; Rahman, A. T. Abdul

    2017-05-01

    Present study focuses on characterisation of SiO2 optical fibers as a potential thermoluminescence (TL) system for radiation therapy dosimetry. Irradiations were made using 6 MV photon beams from a linear accelerator. Flat SiO2 optical fibers of various dimensions with 8% concentration of germanium doped were used. The dimensions of the flat fibers were 270×60 µm, 360×73 µm, 100×510 µm and 160×750 µm. Flat SiO2 optical fibers were characterised for TL dose response in terms of linearity, sensitivity, fading and reproducibility. The uncertainty measured was ±1 standard error of the mean and the coefficient variation was within ±4%, as required for clinical radiotherapy dosimetry. Results shown a good distribution of TL response measured by flat SiO2 optical fibers with uncertainties less than 4%. Linearity of TL comes out with a coefficient of determination (r2) of each fibers that is better than 99% which resulted in high percentage of confidence level. The loss of TL response due to fading, for photon irradiation at fixed energy and constant dose was found to be (20.4 ± 0.2)% over a post irradiation period of 30 days. The TL fading well, showing rapid loss in the first seven (7) days (17.8 ± 0.2)% followed by a more linear like loss subsequently the following day (3.2 ± 0.2)%. A perfect selection of fibers can enhance the accuracy of radiation dosimeter in order for better determination and measurement of radiation doses with a linear response over wide range therapeutic dose.

  9. Across plane ionic conductivity of highly oriented neodymium doped ceria thin films.

    Science.gov (United States)

    Baure, G; Kasse, R M; Rudawski, N G; Nino, J C

    2015-05-14

    A methodology to limit interfacial effects in thin films is proposed and explained. The strategy is to reduce the impact of the electrode interfaces and eliminate cross grain boundaries that impede ionic motion. To this end, highly oriented Nd0.1Ce0.9O2-δ (NDC) nanocrystalline thin films were grown using pulsed laser deposition (PLD) on platinized single crystal a-plane sapphire substrates. High resolution cross-sectional transmission electron microscopy (HR-XTEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) verified the films were textured with columnar grains. The average widths of the columns were approximately 40 nm and not significantly changed by film thickness between 100 and 300 nm. HR-XTEM and XRD determined the {111} planes of NDC were grown preferentially on top of the {111} planes of platinum despite the large lattice mismatch between the two planes. From the XRD patterns, the out of plane strains on the platinum and NDC layers were less than 1%. This can be explained by the coincident site lattice (CSL) theory. Rotating the {111} ceria planes 19.11° with respect to the {111} platinum planes forms a Σ7 boundary where 1 in 7 cerium lattice sites are coincident with the platinum lattice sites. This orientation lowers interfacial energy promoting the preferential alignment of those two planes. The across plane ionic conductivity was measured at low temperatures (<350 °C) for the various film thicknesses. It is here shown that columnar grain growth of ceria can be induced on platinized substrates allowing pathways that are clear of blocking grain boundaries that cause conductivities to diminish as film thickness decreases.

  10. Effects of phosphorous-doping and high temperature annealing on CVD grown 3C-SiC

    International Nuclear Information System (INIS)

    Rooyen, I.J. van; Neethling, J.H.; Henry, A.; Janzén, E.; Mokoduwe, S.M.; Janse van Vuuren, A.; Olivier, E.

    2012-01-01

    The integrity and property behavior of the SiC layer of the Tri-isotropic (TRISO) coated particle (CP) for high temperature reactors (HTR) are very important as the SiC layer is the main barrier for gaseous and metallic fission product release. This study describes the work done on un-irradiated SiC samples prepared with varying phosphorus levels to simulate the presence of phosphorus due to transmutation. 30 Si transmutes to phosphorous ( 31 P) and other transmutation products during irradiation, which may affect the integrity of the SiC layer. The P-doping levels of the SiC samples used in this study cover the range from 1.1 × 10 15 to 1.2 × 10 19 atom/cm 3 and are therefore relevant to the PBMR operating conditions. Annealing from 1000 °C to 2100 °C was performed to study the possible changes in nanostructures and various properties due to temperature. Characterization results by X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), are reported in this article. As grain boundary diffusion is identified as a possible mechanism by which 110m Ag, one of the fission activation products, might be released through intact SiC layer, grain size measurements is also included in this study. Temperature is evidently one of the factors/parameters amongst others known to influence the grain size of SiC and therefore it is important to investigate the effect of high temperature annealing on the SiC grain size. The ASTM E112 method as well as electron back scatter diffraction (EBSD) was used to determine the grain size of various commercial SiC samples and the SiC layer in experimental PBMR Coated Particles (CPs) after annealing at temperatures ranging from 1600 °C to 2100 °C. The HRTEM micrograph of the decomposition of SiC at 2100 °C are shown and discussed. Nanotubes were not identified during the TEM and HRTEM analysis

  11. Effects of phosphorous-doping and high temperature annealing on CVD grown 3C-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: Isabella.vanrooyen@inl.gov [CSIR, National Laser Centre, PO Box 395, Pretoria 0001 (South Africa); Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Fuel Design, PBMR, 1279 Mike Crawford Avenue, Centurion 0046 (South Africa); Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Henry, A.; Janzen, E. [Department of Physics, Chemistry and Biology, Semiconductor Materials, Linkoeping University, Linkoeping 58183 (Sweden); Mokoduwe, S.M. [Fuel Design, PBMR, 1279 Mike Crawford Avenue, Centurion 0046 (South Africa); Janse van Vuuren, A.; Olivier, E. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

    2012-10-15

    The integrity and property behavior of the SiC layer of the Tri-isotropic (TRISO) coated particle (CP) for high temperature reactors (HTR) are very important as the SiC layer is the main barrier for gaseous and metallic fission product release. This study describes the work done on un-irradiated SiC samples prepared with varying phosphorus levels to simulate the presence of phosphorus due to transmutation. {sup 30}Si transmutes to phosphorous ({sup 31}P) and other transmutation products during irradiation, which may affect the integrity of the SiC layer. The P-doping levels of the SiC samples used in this study cover the range from 1.1 Multiplication-Sign 10{sup 15} to 1.2 Multiplication-Sign 10{sup 19} atom/cm{sup 3} and are therefore relevant to the PBMR operating conditions. Annealing from 1000 Degree-Sign C to 2100 Degree-Sign C was performed to study the possible changes in nanostructures and various properties due to temperature. Characterization results by X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), are reported in this article. As grain boundary diffusion is identified as a possible mechanism by which {sup 110m}Ag, one of the fission activation products, might be released through intact SiC layer, grain size measurements is also included in this study. Temperature is evidently one of the factors/parameters amongst others known to influence the grain size of SiC and therefore it is important to investigate the effect of high temperature annealing on the SiC grain size. The ASTM E112 method as well as electron back scatter diffraction (EBSD) was used to determine the grain size of various commercial SiC samples and the SiC layer in experimental PBMR Coated Particles (CPs) after annealing at temperatures ranging from 1600 Degree-Sign C to 2100 Degree-Sign C. The HRTEM micrograph of the decomposition of Si

  12. In Vitro Biocompatibility and Mechanical Performance of Titanium Doped High Calcium Oxide Metaphosphate-Based Glasses

    Directory of Open Access Journals (Sweden)

    Ensanya A. Abou Neel

    2010-01-01

    Full Text Available This study challenged to produce phosphate-based glasses (PBG for the treatment of osseous defects. The glasses contained, among other components, 40 mol% CaO and 1–5 mol% TiO2. The mechanical performance and in vitro biocompatibility using both human osteosarcoma and primary osteoblasts were carried out. Incorporation of TiO2 into PBG had no significant effect on strength and modulus. These glasses encouraged attachment and maintained high viability of osteosarcoma cells similar to the positive control surface. Cells grown directly (on glasses or indirectly (in the presence of glass extracts showed similar proliferation pattern to the positive control cells with no significant effect of TiO2 detected. Increasing TiO2 content, however, has a profound effect on cytoskeleton organization and spreading and maturation of primary osteoblasts. It is believed that TiO2 might have acted as a chemical cue-modulating cells response, and hence the substrates supported maturation/mineralization of the primary osteoblasts.

  13. Nanostructured Phosphorus Doped Silicon/Graphite Composite as Anode for High-Performance Lithium-Ion Batteries.

    Science.gov (United States)

    Huang, Shiqiang; Cheong, Ling-Zhi; Wang, Deyu; Shen, Cai

    2017-07-19

    Silicon as the potential anode material for lithium-ion batteries suffers from huge volume change (up to 400%) during charging/discharging processes. Poor electrical conductivity of silicon also hinders its long-term cycling performance. Herein, we report a two-step ball milling method to prepare nanostructured P-doped Si/graphite composite. Both P-doped Si and coated graphite improved the conductivity by providing significant transport channels for lithium ions and electrons. The graphite skin is able to depress the volume expansion of Si by forming a stable SEI film. The as-prepared composite anode having 50% P-doped Si and 50% graphite exhibits outstanding cyclability with a specific capacity of 883.4 mAh/g after 200 cycles at the current density of 200 mA/g. The cost-effective materials and scalable preparation method make it feasible for large-scale application of the P-doped Si/graphite composite as anode for Li-ion batteries.

  14. Single-mode amplification in Yb-doped rod-type photonic crystal fibers for high brilliance lasers

    DEFF Research Database (Denmark)

    Poli, F.; Lægsgaard, Jesper; Passaro, D.

    2009-01-01

    to identify a proper ring characteristic that is width, position and refractive index. Then rod-type PCF designs have been optimized with a full-vector modal solver based on the finite-element method. Then, the amplification properties of the Yb-doped rod-type PCFs have been investigated by assuming a forward...

  15. Formation of the sodium 1-D structures in doped NaCl by high energy electron irradiation

    NARCIS (Netherlands)

    Cherkasov, FG; Mustafin, RG; L'vov, SG; Khaibullin, RI; den Hartog, HW; Vainshtein, DI; Vitol, AY; L’vov, S.G.

    1998-01-01

    An investigation of the formation and properties of linear sodium structures in electron-irradiated potassium doped NaCl crystals was carried out by means of electron spin resonance (ESR) and nuclear magnetic resonance (NMR). It has been found that the behavior of ESR and NMR signals depends on the

  16. Anchoring ZnO Nanoparticles in Nitrogen-Doped Graphene Sheets as a High-Performance Anode Material for Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Guanghui Yuan

    2018-01-01

    Full Text Available A novel binary nanocomposite, ZnO/nitrogen-doped graphene (ZnO/NG, is synthesized via a facile solution method. In this prepared ZnO/NG composite, highly-crystalline ZnO nanoparticles with a size of about 10 nm are anchored uniformly on the N-doped graphene nanosheets. Electrochemical properties of the ZnO/NG composite as anode materials are systematically investigated in lithium-ion batteries. Specifically, the ZnO/NG composite can maintain the reversible specific discharge capacity at 870 mAh g−1 after 200 cycles at 100 mA g−1. Besides the enhanced electronic conductivity provided by interlaced N-doped graphene nanosheets, the excellent lithium storage properties of the ZnO/NG composite can be due to nanosized structure of ZnO particles, shortening the Li+ diffusion distance, increasing reaction sites, and buffering the ZnO volume change during the charge/discharge process.

  17. Effective Construction of High-quality Iron Oxy-hydroxides and Co-doped Iron Oxy-hydroxides Nanostructures: Towards the Promising Oxygen Evolution Reaction Application.

    Science.gov (United States)

    Zhang, Xinyu; An, Li; Yin, Jie; Xi, Pinxian; Zheng, Zhiping; Du, Yaping

    2017-03-08

    Rational design of high efficient and low cost electrocatalysts for oxygen evolution reaction (OER) plays an important role in water splitting. Herein, a general gelatin-assisted wet chemistry method is employed to fabricate well-defined iron oxy-hydroxides and transitional metal doped iron oxy-hydroxides nanomaterials, which show good catalytic performances for OER. Specifically, the Co-doped iron oxy-hydroxides (Co 0.54 Fe 0.46 OOH) show the excellent electrocatalytic performance for OER with an onset potential of 1.52 V, tafel slope of 47 mV/dec and outstanding stability. The ultrahigh oxygen evolution activity and strong durability, with superior performance in comparison to the pure iron oxy-hydroxide (FeOOH) catalysts, originate from the branch structure of Co 0.54 Fe 0.46 OOH on its surface so as to provide many active edge sites, enhanced mass/charge transport capability, easy release oxygen gas bubbles, and strong structural stability, which are advantageous for OER. Meanwhile, Co-doping in FeOOH nanostructures constitutes a desirable four-electron pathway for reversible oxygen evolution and reduction, which is potentially useful for rechargeable metal-air batteries, regenerative fuel cells, and other important clean energy devices. This work may provide a new insight into constructing the promising water oxidation catalysts for practical clean energy application.

  18. Electronic Modulation of Electrocatalytically Active Center of Cu7S4 Nanodisks by Cobalt-Doping for Highly Efficient Oxygen Evolution Reaction.

    Science.gov (United States)

    Li, Qun; Wang, Xianfu; Tang, Kai; Wang, Mengfan; Wang, Chao; Yan, Chenglin

    2017-12-26

    Cu-based electrocatalysts have seldom been studied for water oxidation because of their inferior activity and poor stability regardless of their low cost and environmentally benign nature. Therefore, exploring an efficient way to improve the activity of Cu-based electrocatalysts is very important for their practical application. Modifying electronic structure of the electrocatalytically active center of electrocatalysts by metal doping to favor the electron transfer between catalyst active sites and electrode is an important approach to optimize hydrogen and oxygen species adsorption energy, thus leading to the enhanced intrinsic electrocatalytic activity. Herein, Co-doped Cu 7 S 4 nanodisks were synthesized and investigated as highly efficient electrocatalyst for oxygen evolution reaction (OER) due to the optimized electronic structure of the active center. Density-functional theory (DFT) calculations reveal that Co-engineered Cu 7 S 4 could accelerate electron transfer between Co and Cu sites, thus decrease the energy barriers of intermediates and products during OER, which are crucial for enhanced catalytic properties. As expected, Co-engineered Cu 7 S 4 nanodisks exhibit a low overpotential of 270 mV to achieve current density of 10 mA cm -2 as well as decreased Tafel slope and enhanced turnover frequencies as compared to bare Cu 7 S 4 . This discovery not only provides low-cost and efficient Cu-based electrocatalyst by Co doping, but also exhibits an in-depth insight into the mechanism of the enhanced OER properties.

  19. Effective Construction of High-quality Iron Oxy-hydroxides and Co-doped Iron Oxy-hydroxides Nanostructures: Towards the Promising Oxygen Evolution Reaction Application

    Science.gov (United States)

    Zhang, Xinyu; An, Li; Yin, Jie; Xi, Pinxian; Zheng, Zhiping; Du, Yaping

    2017-03-01

    Rational design of high efficient and low cost electrocatalysts for oxygen evolution reaction (OER) plays an important role in water splitting. Herein, a general gelatin-assisted wet chemistry method is employed to fabricate well-defined iron oxy-hydroxides and transitional metal doped iron oxy-hydroxides nanomaterials, which show good catalytic performances for OER. Specifically, the Co-doped iron oxy-hydroxides (Co0.54Fe0.46OOH) show the excellent electrocatalytic performance for OER with an onset potential of 1.52 V, tafel slope of 47 mV/dec and outstanding stability. The ultrahigh oxygen evolution activity and strong durability, with superior performance in comparison to the pure iron oxy-hydroxide (FeOOH) catalysts, originate from the branch structure of Co0.54Fe0.46OOH on its surface so as to provide many active edge sites, enhanced mass/charge transport capability, easy release oxygen gas bubbles, and strong structural stability, which are advantageous for OER. Meanwhile, Co-doping in FeOOH nanostructures constitutes a desirable four-electron pathway for reversible oxygen evolution and reduction, which is potentially useful for rechargeable metal-air batteries, regenerative fuel cells, and other important clean energy devices. This work may provide a new insight into constructing the promising water oxidation catalysts for practical clean energy application.

  20. Measurement of high frequency conductivity of oxide-doped anti-ferromagnetic thin film with a near-field scanning microwave microscope

    Directory of Open Access Journals (Sweden)

    Z. Wu

    2014-04-01

    Full Text Available In this manuscript, we describe how the map of high frequency conductivity distribution of an oxide-doped anti-ferromagnetic 200 nm thin film can be obtained from the quality factor (Q measured by a near-field scanning microwave microscope (NSMM. Finite element analysis (FEA is employed to simulate the NSMM tip-sample interaction and obtain a curve related between the simulated quality factor (Q and conductivity. The curve is calibrated by a standard Cu thin film with thickness of 200 nm, together with NSMM measured Q of Ag, Au, Fe, Cr and Ti thin films. The experimental conductivity obtained by the NSMM for IrMn thin films with various doped concentrations of Al2O3 is found consistent with conventional voltammetry measurement in the same tendency. That conductivity decreases as the content of doped Al2O3 increases. The results and images obtained demonstrate that NSMM can be employed in thin film analysis for characterization of local electrical properties of materials in a non-destructive manner and for obtaining a map of conductivity distribution on the same film.

  1. Crystal growth and temperature dependence of light output of Ce-doped (Gd, La, Y)2Si2O7 single crystals

    Science.gov (United States)

    Horiai, Takahiko; Kurosawa, Shunsuke; Murakami, Rikito; Shoji, Yasuhiro; Pejchal, Jan; Yamaji, Akihiro; Ohashi, Yuji; Kamada, Kei; Yokota, Yuui; Ishizu, Tomohiro; Ohishi, Yasuo; Nakaya, Taisuke; Yoshikawa, Akira

    2018-03-01

    Ce-doped (Gd, La)2Si2O7 scintillation crystals are expected to be used as gamma-ray detectors for high temperature measurement. To realize scintillators for high temperature environment, we investigated (Ce0.01 Gd0.59-x La0.40 Yx)2Si2O7 (x = 0.00, 0.05, 0.10, 0.15) single crystals grown by the micro-pulling-down method. The results showed that a 5% Y-admixed Ce-doped (Gd, La)2Si2O7 scintillator can yield higher light output when compared with Y-free Ce-doped (Gd, La)2Si2O7 scintillator. The light outputs at 25°C and 175°C were determined to be ∼43,000 and ∼40,000 photons/MeV, respectively. Moreover, 1 inch size 5% Y-admixed Ce-doped (Gd, La)2Si2O7 scintillator was grown by the Czochralski technique, and its light output at 175°C kept the value of around 95% of the value at 25°C.

  2. Synthesis of S/Cr doped mesoporous TiO2 with high-active visible light degradation property via solid state reaction route

    International Nuclear Information System (INIS)

    Liu Shaoyou; Tang Qunli; Feng Qingge

    2011-01-01

    S/Cr doped mesoporous TiO 2 (S-TiO 2 , Cr-TiO 2 , S-Cr-TiO 2 ) were successfully synthesized via a simple, effective and environmental benign solid state reaction route. The low angle XRD patterns demonstrated that the resulting samples possess mesostructures. The further characterizations via N 2 adsorption-desorption and XPS showed that the typical S/Cr co-doped mesoporous TiO 2 (S-Cr-TiO 2 (5S-5Cr)) possesses mesopore with the high specific surface area of 118.4 m 2 /g and narrow pore size distribution, and both S and Cr have been incorporated into the lattice of TiO 2 with the amounts of 4.16% sulfur and 7.88% chromium, respectively. And Raman spectroscopy shows that the surface of S-Cr-TiO 2 (5S-5Cr) material possesses stretching vibrational peaks at ∼709, ∼793 cm -1 are assignable to the Ti-O-Cr, O-Cr (Ti)-OH bonds, respectively. Interestingly, the UV-vis displayed that the absorption regions of S/Cr doped mesoporous TiO 2 cover the visible light region. As for the series of S-Cr-TiO 2 samples, the absorption region even extends to near infrared region with strong adsorption. Moreover, compared with the pure titanium dioxide (P25-TiO 2 ), the photodegradation properties of bromocresol green (BCG) on the S/Cr doped mesoporous TiO 2 showed excellent photocatalytic properties under visible light irradiation. Within 50 min visible light irradiation, 82.6% of the initial BCG was degraded for the S-Cr-TiO 2 (6S-4Cr) photocatalyst.

  3. New Approach for High-Voltage Electrical Double-Layer Capacitors Using Vertical Graphene Nanowalls with and without Nitrogen Doping.

    Science.gov (United States)

    Chi, Yu-Wen; Hu, Chi-Chang; Shen, Hsiao-Hsuan; Huang, Kun-Ping

    2016-09-14

    Integrating various devices to achieve high-performance energy storage systems to satisfy various demands in modern societies become more and more important. Electrical double-layer capacitors (EDLCs), one kind of the electrochemical capacitors, generally provide the merits of high charge-discharge rates, extremely long cycle life, and high efficiency in electricity capture/storage, leading to a desirable device of electricity management from portable electronics to hybrid vehicles or even smart grid application. However, the low cell voltage (2.5-2.7 V in organic liquid electrolytes) of EDLCs lacks the direct combination of Li-ion batteries (LIBs) and EDLCs for creating new functions in future applications without considering the issue of a relatively low energy density. Here we propose a guideline, "choosing a matching pair of electrode materials and electrolytes", to effectively extend the cell voltage of EDLCs according to three general strategies. Based on the new strategy proposed in this work, materials with an inert surface enable to tolerate a wider potential window in commercially available organic electrolytes in comparison with activated carbons (ACs). The binder-free, vertically grown graphene nanowalls (GNW) and nitrogen-doped GNW (NGNW) electrodes respectively provide good examples for extending the upper potential limit of a positive electrode of EDLCs from 0.1 to 1.5 V (vs Ag/AgNO3) as well as the lower potential limit of a negative electrode of EDLCs from -2.0 V to ca. -2.5 V in 1 M TEABF4/PC (propylene carbonate) compared to ACs. This newly designed asymmetric EDLC exhibits a cell voltage of 4 V, specific energy of 52 Wh kg(-1) (ca. a device energy density of 13 Wh kg(-1)), and specific power of 8 kW kg(-1) and ca. 100% retention after 10,000 cycles charge-discharge, reducing the series number of EDLCs to enlarge the module voltage and opening the possibility for directly combining EDLCs and LIBs in advanced applications.

  4. Risk assessment of K Basin twelve-inch and four-inch drain valve failure from a postulated seismic initiating event

    Energy Technology Data Exchange (ETDEWEB)

    MORGAN, R.G.

    1999-06-23

    The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rate which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. Five four-inch drain valves are located in the north and south loadout pits (NLOP and SLOP), the weasel pit, the technical viewing pit, and the discharge chute pit. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations indicate that only the valve's bonnet and stem are exposed above the basin concrete floor for the twelve-inch drain valve and that much less of the valve's bonnet and stem are exposed above the basin concrete floor for the five four-inch drain valves. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this analysis are to: (1) evaluate the likelihood of damaging the three twelve-inch drain valves located along the north wall of the main basin and the five four-inch drain valves located in the pits from a seismic initiating event, and (2) determine the likelihood of exceeding a specific consequence (initial leak rate) from a damaged valve. The analysis process is a risk-based uncertainty analysis where each variable is modeled using available information and engineering judgement. The uncertainty associated with each variable is represented by a probability distribution (probability density function). Uncertainty exists because of the inherent

  5. Electronic and atomic structure of complex defects in Al- and Ga-highly doped ZnO films

    International Nuclear Information System (INIS)

    Menéndez-Proupin, Eduardo; Palacios, Pablo; Wahnón, Perla

    2015-01-01

    Point defects in Ga- and Al-doped ZnO thin films are studied by means of first principles electronic structure calculations. Candidate defects are identified to explain recently observed differences in electrical and spectroscopic behavior of both systems. Substitutional doping in Ga–ZnO explain the metallic behavior of the electrical properties. Complexes of interstitial oxygen with substitutional Ga can behave as acceptor and cause partial compensation, as well as gap states below the conduction band minimum as observed in photoemission experiments. Zn vacancies can also act as compensating acceptors. On the other hand, the semiconducting behavior of Al–ZnO and the small variation in the optical gap compared with pure ZnO, can be explained by almost complete compensation between acceptor Zn vacancies and substitutional Al donors. Interstitial Al can also be donor levels and can be the origin of the small band observed in photoemission experiments below the Fermi level. Combinations of substitutional Al with interstitial oxygen can act simultaneously as compensating acceptor and generator of the mentioned photoemission band. The theoretical calculations have been done using density functional theory (DFT) within the generalized gradient approximation with on-site Coulomb interaction. In selected cases, DFT calculations with semilocal-exact exchange hybrid functionals have been performed. Results explain photoelectron spectra of Ga–ZnO and Al–ZnO at the corresponding doping levels. - Highlights: • Defects in Ga- and Al-heavy-doped ZnO films are studied by quantum calculations. • Defects compatible with electrical, optical, and HAXPES spectra are proposed. • Doping efficiency is reduced by Zn vacancies and O interstitials. • HAXPES bands near the Fermi level are induced by Al i , and complexes Ga Zn -O i , and Al Zn -O i

  6. Electronic and atomic structure of complex defects in Al- and Ga-highly doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Menéndez-Proupin, Eduardo [Instituto de Energía Solar, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid (Spain); Departamento de Física, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 780-0003 Ñuñoa, Santiago (Chile); Palacios, Pablo, E-mail: pablo.palacios@upm.es [Instituto de Energía Solar, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid (Spain); Dpt. FAIAN, E.T.S.I. Aeronáutica y del Espacio, UPM, Pz. Cardenal Cisneros 3, 28040 Madrid (Spain); Wahnón, Perla [Instituto de Energía Solar, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid (Spain); Dpt. TFO, E.T.S.I. Telecomunicación, UPM, Ciudad Universitaria, 28040 Madrid (Spain)

    2015-06-15

    Point defects in Ga- and Al-doped ZnO thin films are studied by means of first principles electronic structure calculations. Candidate defects are identified to explain recently observed differences in electrical and spectroscopic behavior of both systems. Substitutional doping in Ga–ZnO explain the metallic behavior of the electrical properties. Complexes of interstitial oxygen with substitutional Ga can behave as acceptor and cause partial compensation, as well as gap states below the conduction band minimum as observed in photoemission experiments. Zn vacancies can also act as compensating acceptors. On the other hand, the semiconducting behavior of Al–ZnO and the small variation in the optical gap compared with pure ZnO, can be explained by almost complete compensation between acceptor Zn vacancies and substitutional Al donors. Interstitial Al can also be donor levels and can be the origin of the small band observed in photoemission experiments below the Fermi level. Combinations of substitutional Al with interstitial oxygen can act simultaneously as compensating acceptor and generator of the mentioned photoemission band. The theoretical calculations have been done using density functional theory (DFT) within the generalized gradient approximation with on-site Coulomb interaction. In selected cases, DFT calculations with semilocal-exact exchange hybrid functionals have been performed. Results explain photoelectron spectra of Ga–ZnO and Al–ZnO at the corresponding doping levels. - Highlights: • Defects in Ga- and Al-heavy-doped ZnO films are studied by quantum calculations. • Defects compatible with electrical, optical, and HAXPES spectra are proposed. • Doping efficiency is reduced by Zn vacancies and O interstitials. • HAXPES bands near the Fermi level are induced by Al{sub i}, and complexes Ga{sub Zn}-O{sub i}, and Al{sub Zn}-O{sub i}.

  7. The synthesis of nitrogen/sulfur co-doped TiO2 nanocrystals with a high specific surface area and a high percentage of {001} facets and their enhanced visible-light photocatalytic performance

    Science.gov (United States)

    2012-01-01

    Nitrogen/sulfur co-doped anatase TiO2 nanocrystals with a high specific surface area and a high percentage of {001} facets were synthesized by a solvent-thermal process followed by the calcination with thiourea at an optimum heat treatment temperature. Under current experimental conditions, the optimum heat treatment temperature was found at 300°C, which successfully introduced nitrogen and sulfur dopants into the anatase lattice to replace a small portion of oxygen atoms while preserving the geometry of these anatase TiO2 nanocrystals to maintain a high percentage of {001} facets. These nitrogen/sulfur co-doped anatase TiO2 nanocrystals demonstrated a largely enhanced light absorption in the whole visible-light range and exhibited much higher photocatalytic performance than both P25 TiO2 nanoparticles and anatase TiO2 nanocrystals with a high percentage of {001} facets under visible-light illumination. PMID:23095371

  8. Graphene oxide quantum dot-derived nitrogen-enriched hybrid graphene nanosheets by simple photochemical doping for high-performance supercapacitors

    Science.gov (United States)

    Xu, Yongjie; Li, Xinyu; Hu, Guanghui; Wu, Ting; Luo, Yi; Sun, Lang; Tang, Tao; Wen, Jianfeng; Wang, Heng; Li, Ming

    2017-11-01

    Nitrogen-enriched graphene was fabricated via a facile strategy. Graphene oxide (GO) nanosheets and graphene oxide quantum dots (GQDs) were used as a structure-directing agent and in situ activating agent, respectively, after photoreduction under NH3 atmosphere. The combination of photoreduction and NH3 not only reduced GO and GQD composites (GO/GQDs) within a shorter duration but also doped a high level of nitrogen on the composites (NrGO/GQDs). The nitrogen content of NrGO/GQDs reached as high as 18.86 at% within 5 min of irradiation. Benefiting from the nitrogen-enriched GO/GQDs hybrid structure, GQDs effectively prevent the agglomeration of GO sheets and increased the numbers of ion channels in the material. Meanwhile, the high levels of nitrogen improved electrical conductivity and strengthened the binding energy between GQD and GO sheets. Compared with reduced GO and low nitrogen-doped reduced GO, NrGO/GQD electrodes exhibited better electrochemical characteristics with a high specific capacitance of 344 F g-1 at a current density of 0.25 A g-1. Moreover, the NrGO/GQD electrodes exhibited 82% capacitance retention after 3000 cycles at a current density of 0.8 A g-1 in 6 M KOH electrolyte. More importantly, the NrGO/GQD electrodes deliver a high energy density of 43 Wh kg-1 at a power density of 417 W kg-1 in 1 M Li2SO4 electrolyte. The nitrogen-doped graphene and corresponding supercapacitor presented in this study are novel materials with potential applications in advanced energy storage systems.

  9. Hierarchically porous nitrogen-doped carbon derived from the activation of agriculture waste by potassium hydroxide and urea for high-performance supercapacitors

    Science.gov (United States)

    Zou, Kaixiang; Deng, Yuanfu; Chen, Juping; Qian, Yunqian; Yang, Yuewang; Li, Yingwei; Chen, Guohua

    2018-02-01

    Nitrogen-doped carbon with an ultra-high specific surface area and a hierarchically interconnected porous structure is synthesized in large scale from a green route, that is, the activation of bagasse via a one-step method using KOH and urea. KOH and urea play a synergistic effect for the enhancement of the specific surface area and the modification of pore size of the as-prepared material. Benefiting from the multiple synergistic roles originated from an ultra-high specific area (2905.4 m2 g-1), a high porous volume (2.05 mL g-1 with 75.6 vol% micropores, which is an ideal proportion of micropores for obtaining high specific capacitance), a suitable nitrogen content (2.63 wt%), and partial graphitization, the hierarchically interconnected porous N-doped carbon exhibits an excellent electrochemical performance with a high specific capacitance (350.8, 301.9, and 259.5 F g-1 at 1.0 A g-1 in acidic, alkaline, and neutral electrolytes, respectively), superior rate capability and excellent cycling stability (almost no capacitance loss up to 5000 cycles). Furthermore, the symmetric device assembled by this material achieves high energy densities of 39.1 and 23.5 Wh kg-1 at power densities of 1.0 and 20 kW kg-1, respectively, and exhibits an excellent long-term cycling stability (with capacitance retention above 95.0% after 10 000 cycles).

  10. Electrospun N-Doped Porous Carbon Nanofibers Incorporated with NiO Nanoparticles as Free-Standing Film Electrodes for High-Performance Supercapacitors and CO2 Capture.

    Science.gov (United States)

    Li, Qi; Guo, Jiangna; Xu, Dan; Guo, Jianqiang; Ou, Xu; Hu, Yin; Qi, Haojun; Yan, Feng

    2018-04-01

    Carbon nanofibers (CNF) with a 1D porous structure offer promising support to encapsulate transition-metal oxides in energy storage/conversion relying on their high specific surface area and pore volume. Here, the preparation of NiO nanoparticle-dispersed electrospun N-doped porous CNF (NiO/PCNF) and as free-standing film electrode for high-performance electrochemical supercapacitors is reported. Polyacrylonitrile and nickel acetylacetone are selected as precursors of CNF and Ni sources, respectively. Dicyandiamide not only improves the specific surface area and pore volume, but also increases the N-doping level of PCNF. Benefiting from the synergistic effect between NiO nanoparticles (NPs) and PCNF, the prepared free-standing NiO/PCNF electrodes show a high specific capacitance of 850 F g -1 at a current density of 1 A g -1 in 6 m KOH aqueous solution, good rate capability, as well as excellent long-term cycling stability. Moreover, NiO NPs dispersed in PCNF and large specific surface area provide many electroactive sites, leading to high CO 2 uptake, and high-efficiency CO 2 electroreduction. The synthesis strategy in this study provides a new insight into the design and fabrication of promising multifunctional materials for high-performance supercapacitors and CO 2 electroreduction. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Development of gamma spectroscopy employing NaI(Tl) detector 3 inch x 3 inch and readout electronic of flash-ADC/FPGA-based technology

    Energy Technology Data Exchange (ETDEWEB)

    Hai, Vo Hong [HCMC-National Univ., Hochiminh City (Viet Nam). Inst. of Nuclear Physics; Ton Duc Thang Univ., Ho Chi Minh City (Viet Nam). Div. of Nuclear Physics; Hung, Nguyen Quoc [HCMC-National Univ., Hochiminh City (Viet Nam). Inst. of Nuclear Physics; Khai, Bui Tuan [Osaka Univ. (Japan). Dept. of Physics

    2015-05-15

    n this article the development of a gamma spectroscopy system is described using a scintillation detector NaI(Tl) of 3 inch x 3 inch. The readout electronic for the spectroscopy is built from the fast analog-digital conversion of Flash Analog-Digital Converter (Flash-ADC) 250 MHz - 8 bits resolution, and the embedded Field-Programmable Gate Array (FPGA) technology. The embedded VHSIC Hardware Description Language (VHDL) code for FPGA is built in such a way that it works as a multi channel analyser (MCA) with 4096 Digital Charge Integration (DCI) channels. A pulse generator with frequency varying from Hz up to 12 kHz is used to evaluate the time response of the system. Two standard radioisotope sources of {sup 133}Ba and {sup 152}Eu with multi gamma energies ranging from several tens keV to MeV are used to evaluate the linearity and energy resolution of the system.

  12. Performance and Flowfield Measurements on a 10-inch Ducted Rotor VTOL UAV

    Science.gov (United States)

    Martin, Preston; Tung, Chee

    2004-01-01

    A ducted fan VTOL UAV with a 10-inch diameter rotor was tested in the US Army 7-by 10-Foot Wind Tunnel. The test conditions covered a range of angle of attack from 0 to 110 degrees to the freestream. The tunnel velocity was varied from 0 (simulating a hover condition) to 128 ft/sec in propeller mode. A six-component internal balance measured the aerodynamic loads for a range of model configurations. including the isolated rotor, the isolated duct, and the full configuration of the duct and rotor. For some conditions, hotwire velocity surveys were conducted along the inner and outer surface of the duct and across the downstream wake. In addition, fluorescent oil flow visualization allowed the flow separation patterns inside and outside of the duct to be mapped for a few test conditions. Two different duct shapes were tested to determine the performance effects of leading edge radius. For each duct, a range of rotor tip gap from 1%R to 4.5%R was tested to determine the performance penalty in hover and axial flight. Measured results are presented in terms of hover performance, hover performance in a crosswind, and high angle of attack performance in propeller mode. In each case, the effects of both tip gap and duct leading edge radius are illustrated using measurements. Some of the hover performance issues were also studied using a simple analytical method, and the results agreed with the measurements.

  13. Development of the Software for 30 inch Telescope Control System at KHAO

    Science.gov (United States)

    Mun, B.-S.; Kim, S.-J.; Jang, M.; Min, S.-W.; Seol, K.-H.; Moon, K.-S.

    2006-12-01

    Even though 30inch optical telescope at Kyung Hee Astronomy Observatory has been used to produce a series of scientific achievements since its first light in 1992, numerous difficulties in the operation of the telescope have hindered the precise observations needed for further researches. Since the currently used PC-TCS (Personal Computer based Telescope Control system) software based on ISA-bus type is outdated, it doesn't have a user friendly interface and make it impossible to scale. Also accumulated errors which are generated by discordance from input and output signals into a motion controller required new control system. Thus we have improved the telescope control system by updating software and modifying mechanical parts. We applied a new BLDC (brushless DC) servo motor system to the mechanical parts of the telescope and developed a control software using Visual Basic 6.0. As a result, we could achieve a high accuracy in controlling of the telescope and use the userfriendly GUI (Graphic User Interface).

  14. Am/Cm TTR testing - 3/8-inch glass beads evaluation in CIM5

    International Nuclear Information System (INIS)

    Witt, D. C.

    2000-01-01

    To facilitate the procurement and handling of the glass former for Am/Cm vitrification in the F-Canyon MPPF, 1/4 inch and 3/8 inch diameter glass beads were purchased from Corning for evaluation in the 5 inch Cylindrical Induction Melter (CIM5). Prior to evaluating the beads in the CIM5, tests were conducted in the Drain Tube Test Stand (DTTS) with 1/4 inch beads, 3/8 inch beads, and a 50/50 mixture to identify any process concerns. Results of the DTTS tests are summarized in Attachment 1. A somewhat larger volume expansion was experienced in all three DTTS runs as compared to a standard run using cullet. Further testing of the use of glass beads in the CIM5 was requested by the Design Authority as Task 1.02 of Technical Task Request 99-MNSS/SE-006. Since the Technical Task Plan was not yet approved, the completion of this task was conducted under an authorization request approved by the SRTC Laboratory Director, S. Wood. This request is included as Attachment 2

  15. High-efficiency green phosphorescent organic light-emitting diodes with double-emission layer and thick N-doped electron transport layer

    Energy Technology Data Exchange (ETDEWEB)

    Nobuki, Shunichiro, E-mail: shunichiro.nobuki.nb@hitachi.com [Hitachi Research Laboratory, Hitachi Ltd., 7-1-1 Omika-cho, Hitachi-city, Ibaraki 319-1292 (Japan); Wakana, Hironori; Ishihara, Shingo [Hitachi Research Laboratory, Hitachi Ltd., 7-1-1 Omika-cho, Hitachi-city, Ibaraki 319-1292 (Japan); Mikami, Akiyoshi [Dept. of Electrical Engineering, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichimachi, Ishikawa 921-8501 (Japan)

    2014-03-03

    We have developed green phosphorescent organic light-emitting diodes (OLEDs) with high external quantum efficiency of 59.7% and power efficiency of 243 lm/W at 2.73 V at 0.053 mA/cm{sup 2}. A double emission layer and a thick n-doped electron transport layer were adopted to improve the exciton recombination factor. A high refractive index hemispherical lens was attached to a high refractive index substrate for extracting light trapped inside the substrate and the multiple-layers of OLEDs to air. Additionally, we analyzed an energy loss mechanism to clarify room for the improvement of our OLEDs including the charge balance factor. - Highlights: • We developed high efficiency green phosphorescent organic light-emitting diode (OLED). • Our OLED had external quantum efficiency of 59.7% and power efficiency of 243 lm/W. • A double emission layer and thick n-doped electron transport layer were adopted. • High refractive index media (hemispherical lens and substrate) were also used. • We analyzed an energy loss mechanism to clarify the charge balance factor of our OLED.

  16. Fluorine-doped SnO2 nanoparticles anchored on reduced graphene oxide as a high-performance lithium ion battery anode

    Science.gov (United States)

    Cui, Dongming; Zheng, Zhong; Peng, Xue; Li, Teng; Sun, Tingting; Yuan, Liangjie

    2017-09-01

    The composite of fluorine-doped SnO2 anchored on reduced graphene oxide (F-SnO2/rGO) has been synthesized through a hydrothermal method. F-SnO2 particles with average size of 8 nm were uniformly anchored on the surfaces of rGO sheets and the resulting composite had a high loading of F-SnO2 (ca. 90%). Benefiting from the remarkably improved electrical conductivity and Li-ion diffusion in the electrode by F doping and rGO incorporation, the composite material exhibited high reversible capacity, excellent long-term cycling stability and superior rate capability. The electrode delivered a large reversible capacity of 1037 mAh g-1 after 150 cycles at 100 mA g-1 and high rate capacities of 860 and 770 mAh g-1 at 1 and 2 A g-1, respectively. Moreover, the electrode could maintain a high reversible capacities of 733 mAh g-1 even after 250 cycles at 500 mA g-1. The outstanding electrochemical performance of the as-synthesized composite make it a promising anode material for high-energy lithium ion batteries.

  17. Six virtual inches to the left: The problem with IPng

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, R. [Argonne National Lab., IL (United States); Ficarella, D. [Motorola (United States)

    1994-05-01

    This memo describes an Internet information track protocol for the Internet community. It proposes that a locator address (TA) be assigned to Transmission Control Protocol (TCP). The purpose of this TA is to uniquely identify an Internet node without specifing any routing information. This new version of TCP would contain support for high bandwidth-delay networks. Support for multiple network layer (Internet Protocol) protocols is also possible with this new TCP. Distribution of this document is unlimited. This RFC suggests that a new version of TCP be developed (TCPv11) and deployed. This version of TCP would contain a globally unique transport protocol address (TA). Assiging an address to TCP would allow for the support of multiple network layer protocols (IPng`s). The Ta would identify the location of an Internet node. The IPng layer would provide routing information to the Internet. Seperating the location and routing functions will greatly increase the versitily of the Internet.

  18. Analysis of New High-Q0 SRF Cavity Tests by Nitrogen Gas Doping at Jefferson Lab

    Energy Technology Data Exchange (ETDEWEB)

    Palczewski, Ari D. [JLAB; Geng, Rongli [JLAB; Reece, Charles E. [JLAB

    2014-12-01

    In order to refine systematic understanding and establish confident process control, Jefferson Lab has joined with partners to investigate and thoroughly characterize the dramatically higher Q0 of 1.3 GHz niobium cavities first reported by FNAL in 2013[1]. With partial support from the LCLS-II project, JLab has undertaken a parametric study of nitrogen doping in vacuum furnace at 800 °C followed by variable depth surface removal in the 5 - 20 μm range. Q0 above 3×1010 are typical at 2.0 K and 16 MV/m accelerating field. We report observations from the single cell study and current interpretations. In addition to the parametric single cell study, we also report on the ongoing serial testing of six nitrogen-doped 9-cell cavities as baseline prototypes for LCLS-II.

  19. Performance Degradation Tests of Phosphoric Acid Doped Polybenzimidazole Membrane Based High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2015-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2 and meth......Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2...... to the corrosion of carbon support in the catalyst layer and degradation of the PBI membrane. During the continuous test with methanol containing H2 as the fuel the reaction kinetic resistance and mass transfer resistance of both single cells increased, which may be caused by the adsorption of methanol...

  20. Electrochemistry and in situ Raman spectroelectrochemistry of low and high quality boron doped diamond layers in aqueous electrolyte solution

    Czech Academy of Sciences Publication Activity Database

    Vlčková Živcová, Zuzana; Frank, Otakar; Petrák, Václav; Tarábková, Hana; Vacík, Jiří; Nesládek, M.; Kavan, Ladislav

    2013-01-01

    Roč. 87, JAN 2013 (2013), s. 518-525 ISSN 0013-4686 R&D Projects: GA AV ČR IAA400400804; GA AV ČR KAN200100801 Grant - others:European Commission CORDIS(XE) FP7-ENERGY-2010-FET, projekt 256617 Institutional support: RVO:61389005 ; RVO:61388955 ; RVO:68378271 Keywords : boron doped diamond * electrochemistry * aqueous electrolyte solution Subject RIV: CG - Electrochemistry Impact factor: 4.086, year: 2013