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1

Behavior of Boron Doped Graphites and Boron Carbide under Ion Beam and Plasma Irradiation  

Microsoft Academic Search

\\u000a The paper shortly describes the methods of boron carbide coating deposition and presents the experimental results characterizing\\u000a the properties of boron carbide coatings and of boron doped graphites important to their application as the plasma facing\\u000a materials of fusion devices and other plasma apparatus dealing with dense and high temperature plasma. Conclusion is made\\u000a that thick renewable boron carbide coating

L. B. Begrambekov; O. I. Buzhinsky; A. Zakharovi

2011-01-01

2

Behavior of Boron Doped Graphites and Boron Carbide under Ion Beam and Plasma Irradiation  

NASA Astrophysics Data System (ADS)

The paper shortly describes the methods of boron carbide coating deposition and presents the experimental results characterizing the properties of boron carbide coatings and of boron doped graphites important to their application as the plasma facing materials of fusion devices and other plasma apparatus dealing with dense and high temperature plasma. Conclusion is made that thick renewable boron carbide coating can successfully be used as the protecting coating of plasma facing elements of ITER.

Begrambekov, L. B.; Buzhinsky, O. I.; Zakharovi, A.

3

Graphitized boron-doped carbon foams: Performance as anodes in lithium-ion batteries  

Microsoft Academic Search

The electrochemical performance as potential anodes in lithium-ion batteries of several boron-doped and non-doped graphitic foams with different degree of structural order was investigated by galvanostatic cycling. The boron-doped foams were prepared by the co-pyrolysis of a coal and two boron sources (boron oxide and a borane–pyridine complex), followed by heat treatment in the 2400–2800°C temperature interval. The extent of

Elena Rodríguez; Ignacio Cameán; Roberto García; Ana B. García

2011-01-01

4

11B NMR of boron-doped graphite as the negative electrode of a lithium secondary battery  

Microsoft Academic Search

Boron-doped graphite used as a negative electrode for a lithium rechargeable battery is known to have higher discharge capacity than undoped graphite. Herein, the graphites were mixed with 1, 2.5, 5, and 7 wt.% of boron carbide during the graphitizing process. The structural states of boron in those boron-doped graphites were successfully identified by solid-state 11B NMR spectroscopy. For 1

Youngil Lee; Duk-Young Han; Donghoon Lee; Ae Ja Woo; Sam Hyeon Lee; Daeho Lee; Young Kyu Kim

2002-01-01

5

Structure and electrochemical applications of boron-doped graphitized carbon nanofibers.  

PubMed

Boron-doped graphitized carbon nanofibers (CNFs) were prepared by optimizing CNFs preparation, surface treatment, graphitization and boron-added graphitization. The interlayer spacing (d???) of the boron-doped graphitized CNFs reached 3.356 ?, similar to that of single-crystal graphite. Special platelet CNFs (PCNFs), for which d??? is less than 3.400 ?, were selected for further heat treatment. The first heat treatment of PCNFs at 2800?°C yielded a d??? between 3.357 and 3.365 ?. Successive nitric acid treatment and a second heat treatment with boric acid reduced d??? to 3.356 ?. The resulting boron-doped PCNFs exhibited a high discharge capacity of 338 mAh g?¹ between 0 and 0.5 V versus Li/Li? and 368 mAh g?¹ between 0 and 1.5 V versus Li/Li?. The first-cycle Coulombic efficiency was also enhanced to 71-80%. Such capacity is comparable to that of natural graphite under the same charge/discharge conditions. The boron-doped PCNFs also exhibited improved rate performance with twice the capacity of boron-doped natural graphite at a discharge rate of 5 C. PMID:22797214

Yeo, Jae-Seong; Jang, Sang-Min; Miyawaki, Jin; An, Bai; Mochida, Isao; Rhee, Choong Kyun; Yoon, Seong-Ho

2012-07-13

6

Chemical sputtering of pyrolytic graphite and boron doped graphite USB15 at energies between 10 and 1000 eV  

Microsoft Academic Search

The chemical sputtering of pyrolytic graphite and boron doped graphite USB15 at ion energies down to 10 eV is presented in this paper. Hydrocarbon formation under deuterium bombardment as a function of target temperature up to 1000 K as well as thermal desorption of D2 and CD4 after room temperature implantation have been measured for different energies. The results are

C. García-Rosales; J. Roth

1992-01-01

7

Comparison of beryllium oxide and pyrolytic graphite crucibles for boron doped silicon epitaxy  

SciTech Connect

This article reports on the comparison of beryllium oxide and pyrolytic graphite as crucible liners in a high-temperature effusion cell used for boron doping in silicon grown by molecular beam epitaxy. Secondary ion mass spectroscopy analysis indicates decomposition of the beryllium oxide liner, leading to significant incorporation of beryllium and oxygen in the grown films. The resulting films are of poor crystal quality with rough surfaces and broad x-ray diffraction peaks. Alternatively, the use of pyrolytic graphite crucible liners results in higher quality films.

Ali, Dyan; Richardson, Christopher J. K. [Laboratory for Physical Sciences, University of Maryland, College Park, Maryland 20740 (United States)

2012-11-15

8

Boron-Doped Nanocrystalline Diamond.  

National Technical Information Service (NTIS)

A conductive boron doped nanocrystalline diamond is described. The boron doped diamond has a conductivity which uses the boron in the crystals as a charge carrier. The diamond is particularly useful for electrochemical electrodes in oxidation-reduction re...

G. M. Swain M. Witek P. Sonthalia Y. Show

2004-01-01

9

Boron doped graphene nanoribbons  

Microsoft Academic Search

We will present a detailed study of the electronic, magnetic and transport properties of boron doped graphene nanoribbons, for various widths. The electronic structures and the equilibrium geometries were obtained through ab initio total energy DFT calculations. The transport properties were investigated using nonequilibrium Green's functions. Our results reveal that the substitutional boron atoms occupy the edge sites of nanoribbons,

Thiago Martins; Hiroki Miwa; Antonio J. R. da Silva; A. Fazzio

2007-01-01

10

Graphite/Epoxy, Boron-Graphite/Epoxy Hybrid and Boron/Aluminum Design Allowables.  

National Technical Information Service (NTIS)

The results of a study to develop a reliable set of design allowables for type AS GRAPHITE/EPOXY; A HYBRID CONSISTING OF 4.0 MIL BORON/EPOXY AND TYPE AS graphite/epoxy; and boron/aluminum at room temperature and 350 F are presented. Classic lamination the...

R. P. Cairo R. D. Torczyner

1972-01-01

11

Boron doped nanostructured diamond films  

Microsoft Academic Search

A chemical vapor deposition hydrogen\\/methane\\/nitrogen feed-gas mixture with unconventionally high methane (15% CH4 by volume) normally used to grow ultra-hard and smooth nanostructured diamond films on Ti-6Al-4V alloy substrates was modified to include diborane B2H6 for boron-doping of diamond films. The flow rates for B2H 6 and N2 were varied to investigate their effect on plasma chemistry, film structure, boron

Qi Liang

2004-01-01

12

Boron doped nanostructured diamond films  

NASA Astrophysics Data System (ADS)

A chemical vapor deposition hydrogen/methane/nitrogen feed-gas mixture with unconventionally high methane (15% CH4 by volume) normally used to grow ultra-hard and smooth nanostructured diamond films on Ti-6Al-4V alloy substrates was modified to include diborane B2H6 for boron-doping of diamond films. The flow rates for B2H 6 and N2 were varied to investigate their effect on plasma chemistry, film structure, boron incorporation, and mechanical properties. It was found that boron atoms can easily be incorporated into diamond films and change the lattice constant and film structure. Nitrogen, on the other hand, competes with boron in the plasma and acts to prevent boron incorporation into the diamond structure. In addition, with the appropriate choice of deposition conditions, the film structure can be tailored to range from highly crystalline, well faceted diamond to nanocrystalline diamond. Glancing angle X-ray diffraction and Micro-Raman were used as the main tools to investigate the relation between processing and structure. An optimal N2/CH4 ratio of 0.4 was found to result in a film with a minimum in grain size and surface roughness, along with high boron incorporation (˜4 x 1020 cm-3). Mechanical properties and thermal stability of boron doped nanostructured diamond films were examined by means of nanoindentation, open air thermal annealing, and nanotribometry. It was found that the films have high hardness close to that of undoped nanostructured diamond films. Thermal stability of these films was evaluated by heating in an oxygen environment above 700°C. Improved thermal stability of boron doped nanostructured diamond films was observed. Tribological tests show that although both undoped and boron doped nanostructured diamond films show extremely low coefficient of friction and wear rate as compared with uncoated titanium alloys (Ti-6Al-4V) and cobalt chrome alloy (Co-Cr-Mo), a critical failure max stress of 2.2 GPa was observed for boron doped nanostructured diamond films. A FORTRAN Chemical Kinetics Package for the Analysis of Gas Phase Chemical Kinetics, gas-phase thermodynamic equilibrium calculations involving H 2/CH4/N2/B2H6 mixtures was employed to investigate the chemical interactions leading to boron incorporation and crystalline structure variations. The strong influence of the BH 3 in causing the boron incorporation and the role of CN radical in causing the nanocrystallinity are confirmed by the correlation of their modeled compositions in the gas phase with boron content and degree of nanocrystallinity as determined experimentally. A good degree of agreement was obtained between the theoretically predicted gas phase concentration of species and the experimental concentration trends as measured by the optical emission spectroscopy of the microwave plasma. Overall, high film hardness and toughness, combined with good thermal stability and low surface roughness, indicate that nanostructured boron doped diamond films can be used as wear resistant coatings that are able to withstand high temperature oxidizing environments.

Liang, Qi

13

Boron coatings on graphite for fusion reactor applications  

Microsoft Academic Search

This study is an experimental investigation of boron coatings on graphite and the preliminary determination of some of their physical and nuclear related properties. The boron was obtained by the decomposition of diborane in argon at 500°C and one atm. Adhesion to the graphite (POCO AXF-5Q) was good if a slightly abraded surface was provided. The boron was pseudo-amorphous, had

H. O. Pierson; A. W. Mullendore

1979-01-01

14

Low temperature boron doped diamond  

NASA Astrophysics Data System (ADS)

Low temperature boron doped diamond (LT-BDD) film deposited under 600 °C (460 °C minimum) has been reported. Study reveals that the deposition temperature and boron dopant cause nanocrystalline diamond (NCD) instead of ultrananocrystalline diamond (UNCD®). Unlike conventional NCD, LT-BDD has faster renucleation rate, which ensures a low surface roughness (approximately 10 nm at 0.6 ?m thickness). The overall characteristics of LT-BDD are mixed with the characteristics of conventional NCD and UNCD. Raman spectrum and electrochemical characterization prove that the quality of LT-BDD is similar to those grown under 650-900 °C. LT-BDD enables diamond applications on microelectromechanical systems, bio- and optical technologies.

Zeng, Hongjun; Arumugam, Prabhu U.; Siddiqui, Shabnam; Carlisle, John A.

2013-06-01

15

Structure and functionality of bromine doped graphite  

NASA Astrophysics Data System (ADS)

First-principles calculations are used to study the enhanced in-plane conductivity observed experimentally in Br-doped graphite, and to study the effect of external stress on the structure and functionality of such systems. The model used in the numerical calculations is that of stage two doped graphite. The band structure near the Fermi surface of the doped systems with different bromine concentrations is compared to that of pure graphite, and the charge transfer between carbon and bromine atoms is analyzed to understand the conductivity change along different high symmetry directions. Our calculations show that, for large interlayer separation between doped graphite layers, bromine is stable in the molecular form (Br2). However, with increased compression (decreased layer-layer separation) Br2 molecules tend to dissociate. While in both forms, bromine is an electron acceptor. The charge exchange between the graphite layers and Br atoms is higher than that with Br2 molecules. Electron transfer to the Br atoms increases the number of hole carriers in the graphite sheets, resulting in an increase of conductivity.

Hamdan, Rashid; Kemper, A. F.; Cao, Chao; Cheng, H. P.

2013-04-01

16

Method for wetting a boron alloy to graphite  

DOEpatents

A method is provided for wetting a graphite substrate and spreading a a boron alloy over the substrate. The wetted substrate may be in the form of a needle for an effective ion emission source. The method may also be used to wet a graphite substrate for subsequent joining with another graphite substrate or other metal, or to form a protective coating over a graphite substrate. A noneutectic alloy of boron is formed with a metal selected from the group consisting of nickel (Ni), palladium (Pd), and platinum (Pt) with excess boron, i.e., and atomic percentage of boron effective to precipitate boron at a wetting temperature of less than the liquid-phase boundary temperature of the alloy. The alloy is applied to the substrate and the graphite substrate is then heated to the wetting temperature and maintained at the wetting temperature for a time effective for the alloy to wet and spread over the substrate. The excess boron is evenly dispersed in the alloy and is readily available to promote the wetting and spreading action of the alloy. 1 fig.

Storms, E.K.

1987-08-21

17

Self-doping in Boron Nanostructures  

NASA Astrophysics Data System (ADS)

Boron nanotubes have attracted much attention since their first fabrication in experiments. Boron nanotubes with large radii (R >= 10 å) are predicted to be metallic with large densities of states at their Fermi energies, which may provide excellent conducting systems for one-dimensional electronics. In previous work [1], we have shown a class of stable boron sheets, composed of mixtures of triangular and hexagonal motifs, that are likely to be the precursors of boron nanotubes. These sheets are stabilized by a balance of 2-center and 3-center bonding. Here, using density functional theory and Maximally Localized Wannier Functions, we show that adding a boron atom to a boron sheet is equivalent to doping the boron sheet with all three valence electrons of the added atom. Based on this self-doping picture, we propose a simple counting scheme to construct stable boron nanostructures, e.g. from corresponding carbon ones. We also apply this knowledge to study Mg-doped boron sheets and discuss the possible stable structures of MgB2 nanotubes. [1] H. Tang, and S. Ismail-Beigi, Phys. Rev. Lett. 99, 115501 (2007).

Tang, Hui; Ismail-Beigi, Sohrab

2009-03-01

18

The mechanism of spontaneous doping of boron atoms into graphene  

NASA Astrophysics Data System (ADS)

The mechanism of spontaneous doping of boron atoms into graphene is proposed from ab-initio calculations. When boron and oxygen atoms are placed beside the graphene plane, boron can substitute spontaneously carbon atom in graphene without any energy barrier. More interestingly, the mechanism of spontaneous boron doping is reversible, i.e., the boron dopant also can be removed by the similar barrier-free process. Therefore, the mechanism of doping and contra-doping in this paper should be very useful to control boron doping of graphene.

Deng, Xiaohui; Zhang, Dengyu; Deng, Mingsen; Qu, Xilong

2012-07-01

19

Recombination Activity of Iron in Boron Doped Silicon  

NASA Astrophysics Data System (ADS)

The charge carrier lifetime in iron contaminated boron doped silicon wafers was determined by surface photovoltage, SPV, and microwave photoconductive decay, µPCD, techniques. Our results show that the charge carrier lifetime in boron doped silicon wafers depends on the boron concentration when the lifetime is limited by iron-boron pairs.

Yli-Koski, M.; Palokangas, M.; Sokolov, V.; Storgårds, J.; Väinölä, H.; Holmberg, H.; Sinkkonen, J.

20

Structural analysis of the B-doped mesophase pitch-based graphite fibers by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Milled B-doped mesophase pitch-based carbon fibers (mMPCF's) prepared from a melt-blown petroleum mesophase pitch precursor material have been developed for enhanced Li uptake capacity in Li ion batteries. Raman spectroscopy has been used to investigate the structure of graphitized and B-doped mMPCF's using 632.8-nm HeNe laser excitation. The B-doped mMPCF's show a strong Raman peak near 1330 cm-1, a well-defined peak at 1620 cm-1, and the disappearance of the second-order 2660 cm-1 band. Furthermore, it is shown that the E2g2 graphite Raman band at 1580 cm-1 is shifted to 1590 cm-1 due to B doping. The appearance of a new weak Raman band in the B-doped mMPCF's near 1320 cm-1 is closely related to the B-C stretching mode in the graphite lattice. These results are associated with the breakdown of the k=0 selection rules by a local distortion of the graphite lattice due to substitutional boron doping. On the basis of the integrated intensity ratio R of the disorder-induced line near 1330 cm-1 to the Raman line near 1590 cm-1 after 2.66 at. % boron doping, it is suggested that the substitutional boron in the mMPCF's is homogeneously distributed within the graphene layer in the fiber form. The crystallite domain size La parallel and perpendicular to the fiber axis on the surface of the fiber is estimated to be about 60 Å, which could correspond to the distance between boron atoms substituted for C atoms in a graphene layer of the fibers.

Endo, M.; Kim, C.; Karaki, T.; Tamaki, T.; Nishimura, Y.; Matthews, M. J.; Brown, S. D. M.; Dresselhaus, M. S.

1998-10-01

21

Local atomic and electronic structure of boron chemical doping in monolayer graphene.  

PubMed

We use scanning tunneling microscopy and X-ray spectroscopy to characterize the atomic and electronic structure of boron-doped and nitrogen-doped graphene created by chemical vapor deposition on copper substrates. Microscopic measurements show that boron, like nitrogen, incorporates into the carbon lattice primarily in the graphitic form and contributes ?0.5 carriers into the graphene sheet per dopant. Density functional theory calculations indicate that boron dopants interact strongly with the underlying copper substrate while nitrogen dopants do not. The local bonding differences between graphitic boron and nitrogen dopants lead to large scale differences in dopant distribution. The distribution of dopants is observed to be completely random in the case of boron, while nitrogen displays strong sublattice clustering. Structurally, nitrogen-doped graphene is relatively defect-free while boron-doped graphene films show a large number of Stone-Wales defects. These defects create local electronic resonances and cause electronic scattering, but do not electronically dope the graphene film. PMID:24032458

Zhao, Liuyan; Levendorf, Mark; Goncher, Scott; Schiros, Theanne; Pálová, Lucia; Zabet-Khosousi, Amir; Rim, Kwang Taeg; Gutiérrez, Christopher; Nordlund, Dennis; Jaye, Cherno; Hybertsen, Mark; Reichman, David; Flynn, George W; Park, Jiwoong; Pasupathy, Abhay N

2013-09-16

22

Interactions of bulk-boronized graphites with deuterium plasmas in the Pisces-B facility  

Microsoft Academic Search

Newly developed bulk-boronized graphites and boronized carbon-carbon composites, with a total boron concentration ranging from 3 to 30 wt %, have been bombarded with steady-state deuterium plasmas at temperatures between 200 and 1600°C in the PISCES-B facility. The erosion yield of bulk-boronized graphite is smaller than that of pyrolytic graphite by a factor of 2 to 3 in regimes of

Y. Hirooka; R. W. Conn; M. J. Khandagle; G. Chevalier; T. Sogabe; T. Marsuda; H. Ogura; H. Toyoda; H. Sugai

1991-01-01

23

Ground-state properties of boron-doped diamond  

SciTech Connect

Boron-doped diamond undergoes an insulator-metal or even a superconducting transition at some critical value of the dopant concentration. We study the equilibrium lattice parameter and bulk modulus of boron-doped diamond experimentally and in the framework of the density functional method for different levels of boron doping. We theoretically consider the possibility for the boron atoms to occupy both substitutional and interstitial positions and investigate their influence on the electronic structure of the material. The data suggest that boron softens the lattice, but softening due to substitutions of carbon with boron is much weaker than due to incorporation of boron into interstitial positions. Theoretical results obtained for substitution of carbon are in very good agreement with our experiment. We present a concentration dependence of the lattice parameter in boron-doped diamond, which can be used for to identify the levels of boron doping in future experiments.

Zarechnaya, E. Yu., E-mail: ezarechnaya@yahoo.com; Isaev, E. I. [Moscow State Institute of Steel and Alloys (Technological University) (Russian Federation)], E-mail: eyvaz_isaev@yahoo.com; Simak, S. I. [Linkoeping University, Department of Physics, Chemistry, and Biology (IFM) (Sweden); Vekilov, Yu. Kh. [Moscow State Institute of Steel and Alloys (Technological University) (Russian Federation); Dubrovinsky, L. S. [University of Bayreuth, Bayerisches Geoinstitut (Germany); Dubrovinskaia, N. A. [University of Heidelberg, Mineralogisches Institut (Germany); Abrikosov, I. A. [Linkoeping University, Department of Physics, Chemistry, and Biology (IFM) (Sweden)

2008-04-15

24

Boron and nitrogen co-doping of diamond-like carbon film for transparent conductive films  

NASA Astrophysics Data System (ADS)

We demonstrate boron and nitrogen co-doping of diamond-like carbon (DLC) film by vaporizing borane ammonia for applications in anti-scratch and extremely robust transparent conductive films. This method allows for facile fabrication of boron and nitrogen co-doped DLC (BNDLC) film with ultra-flat surface and uniform thickness. The simultaneous occurrence of graphitization and boron and nitrogen co-doping of DLC film induced by increasing the co-doping temperature was observed and lead to a significant decrease in the sheet resistance. As a result, the sheet resistance and optical transmittance at 550 nm of the BNDLC were 3.53 ± 0.19 k?/sq and 81.25%, respectively.

Song, Wooseok; Kim, Yooseok; Jung, Dae Sung; Lee, Su Il; Jung, Woosung; Kwon, O.-Jin; Kim, Heun Ku; Kim, Mi Sun; An, Ki-Seok; Park, Chong-Yun

2013-11-01

25

Anode performance of a Li ion battery based on graphitized and B-doped milled mesophase pitch-based carbon fibers  

Microsoft Academic Search

The structures and anode performance of graphitized and boron-doped milled mesophase pitch-based carbon fibers (mMPCFs) have been comparatively studied and the results obtained by X-ray diffraction (XRD), SEM, Raman spectroscopy and electrochemical measurements are discussed. The boron doping at the level of 2.66 at.% (2.4 wt.%) enhances the growth of the crystallite thickness, Lc(002), of the host mMPCF. The B-doped

M. Endo; C. Kim; T. Karaki; Y. Nishimura; M. J. Matthews; S. D. M. Brown; M. S. Dresselhaus

1999-01-01

26

Electronic band structure of graphite-boron nitride alloys  

Microsoft Academic Search

Extended-Hueckel crystal orbital band calculations, frontier crystal orbital analysis, and degenerate-level perturbation theory are used to explore the electronic structure of several graphite-boron nitride alloys: BCâ, CâN, BCâN, and their structural isomers. These materials are treated as two-dimensional solids, and the effect of crystal relaxation on the bandgap is considered. Similarities and differences between the band diagrams of the structurally

John P. LaFemina

1990-01-01

27

Formation of p-Type Semiconducting Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films by Boron Doping  

NASA Astrophysics Data System (ADS)

p-Type ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite films were fabricated by pulsed laser deposition using boron-doped graphite targets. Thermal analysis confirmed the occurrence of p-type conduction. The electrical conductivity increased with the doped amount of boron. An activation energy estimated from the Arrhenius plot was approximately 0.1 eV. Near-edge X-ray absorption fine structure spectra revealed that the ?*C-H peak weakened and the ?*C-B peak strengthened with an increase in the doped amount of boron. Fourier transform infrared spectroscopy showed that the sp3 C-H peak weakened with the doped amount of boron. These probably indicate that the hydrogen atoms that terminate the dangling bonds of UNCD crystallites are partially replaced with boron atoms.

Shinya Ohmagari,; Tsuyoshi Yoshitake,; Akira Nagano,; Ryota Ohtani,; Hiroyuki Setoyama,; Eiichi Kobayashi,; Takeshi Hara,; Kunihito Nagayama,

2010-03-01

28

Electronic band structure of graphite-boron nitride alloys  

SciTech Connect

Extended-Hueckel crystal orbital band calculations, frontier crystal orbital analysis, and degenerate-level perturbation theory are used to explore the electronic structure of several graphite-boron nitride alloys: BC{sub 3}, C{sub 3}N, BC{sub 2}N, and their structural isomers. These materials are treated as two-dimensional solids, and the effect of crystal relaxation on the bandgap is considered. Similarities and differences between the band diagrams of the structurally similar materials are discussed and understood in a simple crystal orbital framework.

LaFemina, J.P. (Pacific Northwest Lab., Richland, WA (USA))

1990-05-17

29

Mineralization of paracetamol in aqueous medium by anodic oxidation with a boron-doped diamond electrode  

Microsoft Academic Search

The degradation of 100ml of solutions with paracetamol (N-(4-hydroxyphenyl)acetamide) up to 1gl?1 in the pH range 2.0–12.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a graphite cathode, both of 3-cm2 area, by applying a current of 100, 300 and 450mA between 25 and 45°C. Complete mineralization is always achieved due to

Enric Brillas; Ignasi Sirés; Conchita Arias; Pere Lluís Cabot; Francesc Centellas; Rosa María Rodríguez; José Antonio Garrido

2005-01-01

30

Lithium intercalation in graphites precipitated from pig iron melts  

Microsoft Academic Search

The structural and electrochemical properties of graphitic materials precipitated from supersaturated solutions of carbon in pig iron melts were investigated. Doping of the graphite with boron was accomplished by adding ferroboron to the iron melt. X-ray diffraction patterns showed that all the products were highly crystalline graphites, and that doping with boron generally reduced the d002 values, which indicated that

Y. H Lee; K. C Pan; Y. Y Lin; T Prem Kumar; G. T. K Fey

2003-01-01

31

Electrical conductivity of ion-doped graphite\\/polyethersulphone composites  

Microsoft Academic Search

The electrical conductivity of polyethersulphone (PES) insulating polymer was improved by incorporation of electrically conductive graphite and ions. An initial conducting pathway of the PES\\/graphite composites was formed at lower than 3wt.% of the filler content. LiCl was found to be an effective dopant for the improvement of the electrical conductivities of the PES\\/graphite composites. By doping with 0.06wt.% of

J. Jin; S. Leesirisan; M. Song

2010-01-01

32

Efficient method for Li doping of alpha-rhombohedral boron  

Microsoft Academic Search

Li doping is a promising method for achieving metallization of alpha-rhombohedral boron (alpha-boron for short), which is a potential candidate for a high-Tc superconducting material. Toward this end, a serious drawback has been the difficulty of doping alpha-boron, even though there are theoretical predictions claiming that it should be easy. This discrepancy has been systematically studied by the ab initio

H. Dekura; K. Shirai; A. Yanase

2011-01-01

33

Electronic and Transport Properties of Boron-Doped Graphene Nanoribbons  

Microsoft Academic Search

We report a spin polarized density functional theory study of the electronic and transport properties of graphene nanoribbons doped with boron atoms. We considered hydrogen terminated graphene (nano)ribbons with width up to 3.2 nm. The substitutional boron atoms at the nanoribbon edges (sites of lower energy) suppress the metallic bands near the Fermi level, giving rise to a semiconducting system.

T. B. Martins; R. H. Miwa; Antônio J. R. da Silva; A. Fazzio

2007-01-01

34

Elemental boron doping behavior in silicon molecular beam epitaxy  

Microsoft Academic Search

Boron-doped Si epilayers were grown by molecular beam epitaxy (MBE) using an elemental boron source, at levels up to 2×1020 cm?3, to elucidate profile control and electrical activation over the growth temperature range 450–900 °C. Precipitation and surface segregation effects were observed at doping levels of 2×1020 cm?3 for growth temperatures above 600 °C. At growth temperatures below 600 °C,

C. P. Parry; S. M. Newstead; R. D. Barlow; P. Augustus; R. A. A. Kubiak; M. G. Dowsett; T. E. Whall; E. H. C. Parker

1991-01-01

35

Synthesis and characterization of boron doped alumina stabilized zirconia fibers  

Microsoft Academic Search

Boron doped PVA\\/Zr-Al acetate nanofibers were prepared by electrospinning using PVA as a precursor. The effect of calcination\\u000a temperature on morphology and crystal structure was investigated at 250, 500, and 800 °C. The study also establishes the effect\\u000a of boron doping on the morphology of PVA\\/Zr-Al acetate nanofibers at various calcination temperatures. The measurements showed\\u000a that the conductivity, pH, viscosity

?. Uslu; T. Tunç; S. Keskin; M. K. Öztürk

2011-01-01

36

Atomic hydrogen adsorption on lithium-doped graphite surfaces  

SciTech Connect

The effects of lithium doping of pristine and defective graphite surfaces on hydrogen adsorption are studied by the first-principles Plane-Wave Density Functional Theory. The surface defects are simulated by a single atomic vacancy. The DFT calculation is corrected for long-range effects through semi-empirical London terms for each constituent of the system. The lithium doping of the graphite surfaces notably reinforces hydrogen atom binding. Qualitative comparison with experimental results is given using the lithium 1s energy level shifts induced by the atomic vacancy and/or hydrogen trapping.

Allouche, Alain [CNRS/Univ. de Provence (France); Krstic, Predrag S [ORNL

2012-01-01

37

CRITICALITY STUDY ON TREAT REACTOR--CAUSE OF EXCESS BORON IMPURITY IN GRAPHITE  

Microsoft Academic Search

Criticality calculations for the TREAT Reactor indicated a critical ; radius of 59 cm. However, TREAT became critical at a radius of 67.8 cm. The ; discrepancy was found to be due tc boron impurity in the graphite in excess of ; 1.0 ppm allowed in the original specifications. Studies seemed to indicate that ; the excess boron was picked

Iskenderian

1960-01-01

38

Deposition from gas-phase of boron-carbide on graphite.  

National Technical Information Service (NTIS)

Deposition of boron-carbide on graphite was investigated, as a step in the development of carbon fibers/boron-carbide composite. Experiment were first conducted in a 'hot-wall' reactor, then in a 'cold-wall' reactor, which enables better process control a...

D. Edelstein M. Dariel O. Leibovits S. Agam

1990-01-01

39

Determination of boron isotope ratios by Zeeman effect background correction-graphite furnace atomic absorption spectrometry  

Microsoft Academic Search

A new method for the determination of isotopic ratio of boron using Zeeman effect background correction-graphite furnace atomic absorption spectrometry with conventional atomizer and natural-boron hollow cathode source is described. The isotope-shift Zeeman effect at 208.9 nm is utilized for isotopic ratio determination. At a given concentration of total boron, the net absorbance decreases linearly with increasing 10B\\/11B ratio. The absorbances

S. Thangavel; S. V. Rao; K. Dash; J. Arunachalam

2006-01-01

40

Enhanced Growth of Diamond Grains in Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films by Pulsed Laser Deposition with Boron-Blended Graphite Targets  

NASA Astrophysics Data System (ADS)

Ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon composite films were prepared by pulsed laser deposition with boron-blended graphite targets and the effects of the boron-doping on the growth of UNCD grains were investigated. With an increase in the boron content, the grain size was increased from 5 to 23 nm accompanied by the lattice constant approaching that of bulk diamond. The sp3/(sp3+ sp2) ratio estimated from the X-ray photoemission spectra was enhanced by the boron-doping, which might be predominantly attributable to the enlarged grains. The near-edge X-ray absorption fine-structure spectroscopic measurement revealed that boron atoms are preferentially distributed into grain boundaries. On the basis of the results, the roles of the boron atoms in the enhanced crystalline growth are discussed. We consider that the crystalline growth posterior to the nucleation is facilitated by boron atoms neighboring UNCD grains or by boron-containing energetic species in plasma.

Ohmagari, Shinya; Katamune, Y?ki; Ichinose, Hikaru; Yoshitake, Tsuyoshi

2012-02-01

41

The Effects of Boron Content in the Target of Pulsed Laser Deposition on the Properties of Boron Doped Amorphous Carbon Thin Films  

NASA Astrophysics Data System (ADS)

The effects of boron content in camphoric carbon (CC) and graphite target of pulsed laser deposition (PLD) prepared in vacuum at room temperature on the properties of boron doped amorphous carbon (a-C:B) thin films has been studied. Deposited a-C:B films have been investigated using standard measurement techniques and the effects of B weight percentages (Bwt%) in the target are discussed. The variation of surface morphology, bonding and structural properties, as well as the optical gap (Eg) and electrical resistivity (?) of a-C:B films deposited using a CC target are related to the successful doping of B for low B content in the amorphous carbon (a-C) films as the structure and Eg remain almost unchanged, and the ? decreased for the film deposited using graphite target with B powder up to 10 Bwt%. Since both Eg and ? decreased sharply with higher Bwt%, this phenomenon may be due to graphitization. For a-C:B films deposited using graphite target with low B content at 1 and 3 Bwt%, as the Eg is observed to increase only slightly when compared with undoped a-C films and with the decrease of ?, we speculated that the B incorporation induced successful of doping is responsible for the decrease in ?.

Rusop, M.; Tian, X. M.; Kinugawa, T.; Soga, T.; Jimbo, T.; Umeno, M.

42

Boron-doped back-surface fields using an aluminum-alloy process  

SciTech Connect

Boron-doped back-surface fields (BSF`s) have potentially superior performance compared to aluminum-doped BSF`s due to the higher solid solubility of boron compared to aluminum. However, conventional boron diffusions require a long, high temperature step that is both costly and incompatible with many photovoltaic-grade crystalline-silicon materials. We examined a process that uses a relatively low-temperature aluminum-alloy process to obtain a boron-doped BSF by doping the aluminum with boron. In agreement with theoretical expectations, we found that thicker aluminum layers and higher boron doping levels improved the performance of aluminum-alloyed BSF`s.

Gee, J.M.; Bode, M.D.; Silva, B.L.

1997-10-01

43

Improved optical transmittance of boron doped ZnO thin films by low pressure chemical vapor deposition with pulse boron doping  

Microsoft Academic Search

A pulse doping technique is introduced to obtain boron doped ZnO thin films with high conductivity and improved transmittance. The ZnO thin films were deposited by low pressure chemical vapor deposition and boron was doped into the ZnO thin films by the pulse supply of B2H6 gas. The pulse boron doped ZnO thin films exhibited a well textured surface morphology

Chang-Soo Lee; B. T. Ahn

2011-01-01

44

Characterization of oxidized boron-doped carbon fiber anodes for Li-ion batteries by analysis of heat of immersion  

Microsoft Academic Search

Surface oxidation treatment in the temperature range of 500–1400°C was applied to a graphitized boron-doped mesophase-pitch-based carbon fiber (B-MCF), anode material for Li-ion battery. The correlation between physical properties and lithium intercalation of B-MCF was investigated from measurement of heat of immersion. The surface analysis of heat of immersion and X-ray photoelectron spectroscopy (XPS) indicated that the strength of surface

Tomokazu Morita; Norio Takami

2004-01-01

45

Fabrication and characterization of thermomechanically processed sulfur and boron doped amorphous carbon films  

NASA Astrophysics Data System (ADS)

Small scale, high power density, reliable, and long-life power supplies would be useful or even critical for space missions or the growing number of microdetectors, microsensors, and miniature vehicles. Alpha or beta particle voltaic devices could satisfy these requirements but have been shown to degrade quickly due to radiation damage. Amorphous carbon (a-C) PN junctions or PIN devices could provide radiation hardness and sufficiently high efficiency. As the range of alpha and beta particles in a-C is ˜20-120microm, much thicker films than are typical are needed to maximize collection of the particle energy. In this work, the fabrication of thermomechanically processed p- and n-type doped a-C films were investigated as a first step in the future development of radiation hard voltaic devices. Boron carbide (B4C) powder was mixed with a-C nanopowders as a possible p-type dopant with sulfur powder utilized as a possible n-type dopant. Doping levels of 2.5at%, 5.0at%, and 10.0at% were investigated for both dopants with films pressed at 109°C over a pressure range of 0.3-5.0GPa. Initial attempts to fabricate rectifying PN junctions and PIN devices was unsuccessful. Bonding properties were characterized using Raman spectroscopy with electronic properties primarily assessed using the van der Pauw method. Undoped a-C and boron-doped films were found to be slightly p-type with sulfur-doped films converting to n-type. All films were found to consist almost entirely of nano-graphitic sp2 rings with only slight changes in disorder at different pressures. Sulfur doped films were less brittle which is indicative of crosslinking. Boron doping did not significantly change the film electronic properties and is not an effective dopant at these temperatures and pressures. Sulfur doping had a greater effect and could likely be utilized as basis for an n-type material in a device. Initial irradiation studies using alpha particles showed that boron and undoped films became more p-type with sulfur films converting to p-type. The sulfur doped films returned to n-type after isothermal annealing.

Carlson, Lonnie

46

Influence of Si Co-doping on electrical transport properties of magnesium-doped boron nanoswords  

SciTech Connect

Magnesium-doped boron nanoswords were synthesized via a thermoreduction method. The as-prepared nanoswords are single crystalline and {beta}-rhombohedral ({beta}-rh) phase. Electrical transport measurements show that variable range hopping conductivity increases with temperature, and carrier mobility has a greater influence than carrier concentration. These results are consistent with the three dimensional Mott's model (M. Cutler and N. F. Mott, Phys. Rev. 181, 1336 (1969)) besides a high density of localized states at the Fermi level compared with bulk {beta}-rh boron. Conductivity of Mg-doped boron nanoswords is significantly lower than that of ''pure'' (free of magnesium) boron nanoswords. Electron energy loss spectroscopy studies confirm that the poorer conductivity arises from silicon against magnesium doping.

Tian Yuan; Lu Hongliang; Tian Jifa; Li Chen; Hui Chao; Shi Xuezhao; Huang Yuan; Shen Chengmin; Gao Hongjun [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

2012-03-05

47

APPLICATION OF BORON-DOPED DIAMOND ELECTRODES FOR WASTEWATER TREATMENT  

Microsoft Academic Search

Boron-doped diamond (BDD) thin film is a new electrode material that has received great attention recently because it possesses several technologically important characteristics such as an inert surface with low adsorption properties, remarkable corrosion stability, even in strong acidic media, and an extremely wide potential window in aqueous and non-aqueous electrolytes. Due to these properties, diamond electrodes are promising anodes

Marco Panizza; Enric Brillas; Christos Comninellis

48

Synthesis and thermoluminescence of boron-doped germanium nanowires  

NASA Astrophysics Data System (ADS)

Boron doped germanium nanowires were synthesized using chemical vapor deposition (CVD) with Au nanoparticles as nucleating centers, germanium tetrachloride as the source of germanium and B2H6 gas as source of boron impurity. Au nanoparticles were deposited on Si using 3-aminopropyltriethylsilane (APTES). The single crystal Ge nanowires with diameters ranging from 19 to 200 nm were grown in a controllable manner. Effects of Au nanoparticle size, argon gas flow, temperature and duration of growth on diameter and length of nanowires were investigated. This is the first report on thermoluminescence (TL) properties of boron doped germanium nanowires. Glow curves were fitted using computerized glow curve deconvolution program and seven overlapped peaks were obtained. Further the response of synthesized nanowires to different dose levels of UV was studied and linear response regime was determined.

Zahedifar, M.; Hosseinmardi, F.; Eshraghi, L.; Ganjipour, B.

2011-03-01

49

Metallographic Evaluation of the Reactions Between Boronated Graphite and Fe-Ni-Cr Alloys.  

National Technical Information Service (NTIS)

The compatibility of boronated graphite with alloy 800H and type 316 stainless steel was evaluated metallographically after exposures at 700 and 810 exp 0 C for up to 10,000 h. At 700 exp 0 C, the principal reaction with both alloys was limited oxidation....

P. F. Tortorelli J. R. Mayotte T. J. Henson J. H. DeVan

1984-01-01

50

Can doping graphite trigger room temperature superconductivity? Evidence for granular high-temperature superconductivity in water-treated graphite powder.  

PubMed

Granular superconductivity in powders of small graphite grains (several tens of micrometers) is demonstrated after treatment with pure water. The temperature, magnetic field and time dependence of the magnetic moment of the treated graphite powder provides evidence for the existence of superconducting vortices with some similarities to high-temperature granular superconducting oxides but even at temperatures above 300 K. Room temperature superconductivity in doped graphite or at its interfaces appears to be possible. PMID:22949348

Scheike, T; Böhlmann, W; Esquinazi, P; Barzola-Quiquia, J; Ballestar, A; Setzer, A

2012-09-05

51

Carrier doping into boron nanobelts by neutron transmutation  

SciTech Connect

We report the effects of a neutron-capture reaction of isotope {sup 10}B on the structure and electrical transport of {sup 10}B-enriched single-crystalline boron nanobelts. Partial amorphization, particularly at the surface of the nanobelt, was observed after thermal neutron irradiation with a dose of 2x10{sup 19} cm{sup -2}. Carrier doping into the nanobelts by neutron transmutation is expected after postannealing. The change in conductance is discussed based on the distribution of localized states in the band gap of {alpha}-tetragonal boron.

Kirihara, Kazuhiro; Shimizu, Yoshiki; Sasaki, Takeshi; Koshizaki, Naoto [Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565 (Japan); Yamada, Yoichi [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Esaka, Fumitaka [Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Yamamoto, Hiroyuki; Shamoto, Shin-ichi [Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), Tokai, Ibaraki 319-1195 (Japan); Kimura, Kaoru [Department of Advanced Materials Science, The University of Tokyo, Kashiwa, Chiba 277-8561 (Japan)

2010-11-22

52

Effects of High Temperature Treatment on Curl And Microstructure of Heavily Boron Doped Silicon.  

National Technical Information Service (NTIS)

An experimental study was performed to investigate the effects of high temperature treatment on the microstructure and curling behavior of heavily boron-doped silicon structures. Cantilever structures were created from p++ boron diffused silicon wafers. T...

D. M. Bruce

1997-01-01

53

Infrared luminescence from silicon nanostructures heavily doped with boron  

SciTech Connect

Intense highly polarized radiation from silicon nanostructures heavily doped with boron to 5 Multiplication-Sign 10{sup 21} cm{sup -3} is studied as a function of temperature, forward current, and an additional lateral electric field. The features of the radiation intensity and degree of polarization suggest that an important role in the formation of the luminescence spectra is played by the ordered system of B{sup +}-B{sup -} dipoles, formed as a result of the reconstruction of shallow boron acceptors as centers with negative correlation energy. The results obtained are interpreted within a proposed model based on two-electron adiabatic potentials, according to which radiation results from donor-acceptor recombination via boron dipole center states, involving shallow phosphorus donors.

Bagraev, N. T.; Klyachkin, L. E.; Kuzmin, R. V., E-mail: roman.kuzmin@mail.ioffe.ru; Malyarenko, A. M. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Mashkov, V. A. [Saint Petersburg State Polytechnical University (Russian Federation)

2012-03-15

54

Retardation in the chemical-mechanical polish of the boron-doped polysilicon and silicon  

Microsoft Academic Search

This letter reports on the chemical-mechanical polishing (CMP) of boron-doped polysilicon and silicon. Successive polishing was carried out to investigate how the removal rate correlates to the boron concentration as a function of depth in the polysilicon and crystalline silicon. It is found that the removal of boron-doped samples is significantly retarded and strongly correlated with the doping concentration. To

Wen Luh Yang; Chih-Yuan Cheng; Ming-Shih Tsai; Don-Gey Liu; Ming-Sun Shieh

2000-01-01

55

Electrochemical hydrogen termination of boron-doped diamond  

SciTech Connect

Boron-doped diamond is a promising transducer material for numerous devices which are designed for contact with electrolytes. For optimized electron transfer the surface of diamond needs to be hydrogen terminated. Up to now H-termination of diamond is done by plasma chemical vapor deposition techniques. In this paper, we show that boron-doped diamond can be H-terminated electrochemically by applying negative voltages in acidic solutions. Electrochemical H-termination generates a clean surface with virtually no carbon-oxygen bonds (x-ray photoelectron spectroscopy), a reduced electron affinity (scanning electron microscopy), a highly hydrophobic surface (water contact angle), and a fast electron exchange with Fe(CN){sub 6}{sup -3/-4} (cyclic voltammetry).

Hoffmann, Rene; Kriele, Armin; Obloh, Harald; Hees, Jakob; Wolfer, Marco; Smirnov, Waldemar; Yang Nianjun; Nebel, Christoph E. [Fraunhofer Institute for Applied Solid State Physics (IAF), Tullastrasse 72, Freiburg 79108 (Germany)

2010-08-02

56

Photoelectron Spectroscopy of Aluminum Doped Boron Clusters  

NASA Astrophysics Data System (ADS)

Anionic boron clusters have been shown to be planar or quasi-planar up to B21- from a series of combined photoelectron spectroscopy and theoretical studies. All these boron clusters consist of a peripheral ring characterized by strong two-center-two-electron (2c-2e) B-B bonds and one or more interior atoms. The propensity for planarity is due to ? - and ? -electron delocalizations throughout the molecular plane, giving rise to concepts of ? - and ? -aromaticity. The quasi-planarity, on the other hand, can be mechanical in nature - the circumference of the cluster is too small to fit the inner atoms - even for doubly aromatic clusters. Two questions arise: firstly, can isoelectronic substitution by a single aluminum atom on the outer ring enhance the planarity of quasi-planar structures, and, secondly, can the interior boron atoms be replaced by aluminum? A series of aluminum isoelectronic substitution of boron clusters have been investigated ranging from B7- to B12-. Aluminum turns out to avoid the central position in the all these clusters and enhance the planarity of AlB6- and AlB11- clusters by expanding the peripheral ring. References: [1] C. Romanescu, A. P. Sergeeva, W. L. Li, A. I. Boldyrev and L. S. Wang, {J. Am. Chem. Soc}. {133} (22), 8646-8653 (2011) [2] T. R. Galeev, C. Romanescu, W. L. Li, L. S. Wang and A. I. Boldyrev, {J. Chem. Phys.} {135}, (8) 104301 (2011) [3] W. L. Li, C. Romanescu, T. R. Galeev, L. S. Wang and A. I. Boldyrev, {J. Phys. Chem. A} {115} (38), 10391-10397 (2011)

Li, Wei-Li; Romanescu, Constantin; Wang, Lai-Sheng

2012-06-01

57

Electrochemical oxidation of phenol at boron-doped diamond electrode  

Microsoft Academic Search

The electrochemical oxidation of phenol at synthetic boron-doped diamond thin film electrode (BDD) has been studied in acid media by cyclic voltammetry, chronoamperometry and bulk electrolysis. The results have shown that in the potential region of water stability (E<2.3 V vs. SHE) they can occur direct electron transfer reactions on BDD surface that results in electrode fouling due to the

J. Iniesta; P. A. Michaud; M. Panizza; G. Cerisola; A. Aldaz; Ch. Comninellis

2001-01-01

58

Detection of phenol at boron-doped nanocrystalline diamond electrodes  

Microsoft Academic Search

The phenol quantification using boron-doped nanocrystalline diamond (BDND) from electroanalytical technique of square wave voltammetry (SWV) is reported. BDND depositions were performed using Hot Filament Chemical Vapor Deposition reactor, where it was possible to grow films with statics substrate-holder (sample S1) or with spinning substrate-holder (sample S2). The variation of this growth parameter induced significant changes on the electrode properties.

A. F. Azevedo; F. A. Souza; J. T. Matsushima; M. R. Baldan; N. G. Ferreira

2011-01-01

59

Direct amination of hydrogen-terminated boron doped diamond surfaces  

Microsoft Academic Search

This paper reports on direct amination of hydrogen-terminated polycrystalline boron doped electrode. The technique consists of NH3 plasma treatment of hydrogenated diamond substrate to generate surface terminal amino groups. The aminated diamond surface was further investigated for its ability to bind gold nanoparticles. Homogeneous and well-distributed gold nanoparticles were obtained by simple exposure of the amine-terminated surface to an aqueous

Sabine Szunerits; Charafeddine Jama; Yannick Coffinier; Bernadette Marcus; Didier Delabouglise; Rabah Boukherroub

2006-01-01

60

Surface passivation of boron doped a-Si:H  

NASA Astrophysics Data System (ADS)

The kinetics of contact potential, conductivity and material relaxation of B doped a-Si:H are studied by an in-situ Kelvin probe and ellipsometry. During annealing B is passivated on the surface and reactivated in the bulk. Results are analyzed in the framework of H diffusion induced boron deactivation. A time-dependent activation energy is proposed to explain its dispersive diffusion in a-Si:H.

Zongyan, Wu; Equer, B.; Lloret, A.; Amokrane, R.

1991-04-01

61

Minority carrier lifetime degradation in boron-doped Czochralski silicon  

NASA Astrophysics Data System (ADS)

The minority carrier lifetime in boron-doped oxygen-contaminated Czochralski (Cz) silicon is strongly reduced under illumination or carrier injection. This process can be fully reversed by a 200 °C anneal step. In several recent studies it was shown that boron and oxygen are the major components of the underlying metastable Cz-specific defect. The energy level of the defect in its active state A was determined to be around midgap [Schmidt et al., J. Appl. Phys. 86, 3175 (1999)] while the energy level of the defect in its passive state P is very shallow. The Cz-specific defect in its passive state can be identified with the shallow thermal donor. The kinetics of the excess carrier-induced transformation from state P to state A can be described using recombination-enhanced defect reaction theory. On the basis of these experimental facts different solutions for the reduction or elimination of the metastable defect are suggested. Two promising solutions are discussed in more detail: the use of gallium-doped Cz silicon and the introduction of high-temperature anneals into the process sequence. Gallium-doped Cz silicon shows no degradation and excellent lifetimes over a wide resistivity range, although the concentration of interstitial oxygen is in the same range as in standard Cz silicon. Stable solar cell efficiencies comparable to FZ silicon have been achieved. If standard boron-doped Cz silicon is used, the defect concentration can be reduced permanently by a high-temperature anneal using conventional tube or rapid thermal processing. This leads to an improvement of the carrier lifetime by a factor of 2-3. Nevertheless, it is always necessary to use an optimized set of process parameters because otherwise the lifetime of all oxygen-contaminated materials (including gallium-doped Cz silicon) is severely reduced

Glunz, S. W.; Rein, S.; Lee, J. Y.; Warta, W.

2001-09-01

62

Determination of boron isotope ratios by Zeeman effect background correction-graphite furnace atomic absorption spectrometry  

NASA Astrophysics Data System (ADS)

A new method for the determination of isotopic ratio of boron using Zeeman effect background correction-graphite furnace atomic absorption spectrometry with conventional atomizer and natural-boron hollow cathode source is described. The isotope-shift Zeeman effect at 208.9 nm is utilized for isotopic ratio determination. At a given concentration of total boron, the net absorbance decreases linearly with increasing 10B/11B ratio. The absorbances are recorded at the field strength of 1.0 T. The isotope ratios measured by the proposed method were in good agreement with the results obtained by inductively coupled plasma-quadruple mass spectrometry or thermal ionization mass spectrometry. The present method is fairly fast and less expensive compared to the above techniques and is quite suitable for plant environments.

Thangavel, S.; Rao, S. V.; Dash, K.; Arunachalam, J.

2006-03-01

63

Electrostatic doping of graphene through ultrathin hexagonal boron nitride films.  

PubMed

When combined with graphene, hexagonal boron nitride (h-BN) is an ideal substrate and gate dielectric with which to build metal|h-BN|graphene field-effect devices. We use first-principles density functional theory (DFT) calculations for Cu|h-BN|graphene stacks to study how the graphene doping depends on the thickness of the h-BN layer and on a potential difference applied between Cu and graphene. We develop an analytical model that describes the doping very well, allowing us to identify the key parameters that govern the device behavior. A predicted intrinsic doping of graphene is particularly prominent for ultrathin h-BN layers and should be observable in experiment. It is dominated by novel interface terms that we evaluate from DFT calculations for the individual materials and for interfaces between h-BN and Cu or graphene. PMID:21936569

Bokdam, Menno; Khomyakov, Petr A; Brocks, Geert; Zhong, Zhicheng; Kelly, Paul J

2011-09-30

64

Improvement of the electrochemical properties of “as-grown” boron-doped polycrystalline diamond electrodes deposited on tungsten wires using ethanol  

Microsoft Academic Search

The electrochemical properties of boron-doped diamond (BDD) polycrystalline films grown on tungsten wire substrates using\\u000a ethanol as a precursor are described. The results obtained show that the use of ethanol improves the electrochemistry properties\\u000a of “as-grown” BDD, as it minimizes the graphitic phase upon the surface of BDD, during the growth process. The BDD electrodes\\u000a were characterized by Raman spectroscopy,

Reinaldo F. Teófilo; Helder J. Ceragioli; Alfredo C. Peterlevitz; Leonardo M. Da Silva; Flavio S. Damos; Márcia M. C. Ferreira; Vitor Baranauskas; Lauro T. Kubota

2007-01-01

65

Mineralization of salicylic acid in acidic aqueous medium by electrochemical advanced oxidation processes using platinum and boron-doped diamond as anode and cathodically generated hydrogen peroxide  

Microsoft Academic Search

Solutions containing 164mgL?1 salicylic acid of pH 3.0 have been degraded by electrochemical advanced oxidation processes such as anodic oxidation, anodic oxidation with electrogenerated H2O2, electro-Fenton, photoelectro-Fenton and solar photoelectro-Fenton at constant current density. Their oxidation power has been comparatively studied in a one-compartment cell with a Pt or boron-doped diamond (BDD) anode and a graphite or O2-diffusion cathode. In

Elena Guinea; Conchita Arias; Pere Lluís Cabot; José Antonio Garrido; Rosa María Rodríguez; Francesc Centellas; Enric Brillas

2008-01-01

66

Thermal and optical properties of high purity CVD-diamond discs doped with boron and nitrogen  

Microsoft Academic Search

The effect of nitrogen and boron doping on the thermal and optical properties of high purity CVD-diamond grown by microwave plasma (MW-CVD) and DC arc-jet chemical vapor deposition (DCAJ-CVD) is investigated. Boron and nitrogen doping was carried out by adding to the process gas trimethylborate and nitrogen, respectively. Secondary ion mass spectrometry (SIMS) was used to quantify the incorporated boron

E. Wörner; E. Pleuler; C. Wild; P. Koidl

2003-01-01

67

Controlled in situ boron doping of diamond thin films using solution phase  

Microsoft Academic Search

Controlled boron doping of diamond film using nontoxic reagents is a challenge in itself. During the present study, attempts have been made to dope diamond films in situ with boron from a solution of boric acid (H3BO3) in methanol (CH3OH) using a specially designed bubbler that ensured continuous and controlled flow of vapors of boron precursors during deposition. The samples

M. Roy; A. K. Dua; J. Nuwad; K. G. Girija; A. K. Tyagi; S. K. Kulshreshtha

2006-01-01

68

Electronic structure and optical property of boron doped semiconducting graphene nanoribbons  

NASA Astrophysics Data System (ADS)

We present a system study on the electronic structure and optical property of boron doped semiconducting graphene nanoribbons using the density functional theory. Energy band structure, density of states, deformation density, Mulliken popular and optical spectra are considered to show the special electronic structure of boron doped semiconducting graphene nanoribbons. The C-B bond form is discussed in detail. From our analysis it is concluded that the Fermi energy of boron doped semiconducting graphene nanoribbons gets lower than that of intrinsic semiconducting graphene nanoribbons. Our results also show that the boron doped semiconducting graphene nanoribbons behave as p-type semiconducting and that the absorption coefficient of boron doped armchair graphene nanoribbons is generally enhanced between 2.0 eV and 3.3 eV. Therefore, our results have a great significance in developing nano-material for fabricating the nano-photovoltaic devices.

Chen, Aqing; Shao, Qingyi; Wang, Li; Deng, Feng

2011-08-01

69

Effect of Boron Weight Percentages in the Target of Pulsed Laser Deposition on the Preparation of Boron-Doped Amorphous Carbon Films  

NASA Astrophysics Data System (ADS)

The effect of boron weight percentage in the camphoric carbon target of pulsed laser deposition on the preparation of boron-doped amorphous carbon (a-C:B) films has been studied using standard measurement techniques. XPS results showed the a-C:B films bonding properties almost unchanged at lower Bwt% up to 10 Bwt%, after which it changes with the increase of Bwt%, indicating increasing doping concentration with increase of Bwt% in the target. This phenomenon is further supported by FTIR and Visible-Raman spectroscopy analyses. The variation of bonding and structural properties are also correlated with the optical gap (Eg) and electrical resistivity (?) characteristics which are related to successful doping of B for low content of B in the amorphous carbon (a-C) films as the bonding, structural and Eg remain almost unchanged, and the ? decreased untill the film deposited at 10 Bwt%. Since both the Eg and ? decrease sharply with higher Bwt%, this phenomenon can be related to the graphitization.

Rusop, M.; Kinugawa, T.; Soga, T.; Jimbo, T.

70

Boron-doping controlled peculiar transport properties of graphene nanoribbon p-n junctions  

NASA Astrophysics Data System (ADS)

We construct two kinds of p-n junctions based on graphene nanoribbons with different doping concentration. The left part of junction is Boron-doped at the edge of zigzag-edge graphene nanoribbon, and the right part is Boron-doped at the center. The transport properties, calculated by nonequilibrium Green's function method combined with the density functional theory under external bias, show obvious rectification effect and interesting negative differential resistance phenomenon depending on Boron-doping density and position. Considering the interaction of charge carriers with impurity and the correlation between charges at the edges and center, the excellent nanoscale electronic devices have been achieved.

Yao, Wei; Yao, K. L.; Gao, G. Y.; Fu, H. H.; Zhu, S. C.

2013-01-01

71

Direct cytochrome c electrochemistry at boron-doped diamond electrodes  

Microsoft Academic Search

Highly boron-doped diamond electrodes are characterized voltammetrically employing Ru(NH3)63+\\/2+, Fe(CN)63?\\/4?, benzoquinone\\/hydroquinone, and cytochrome c redox systems. The diamond electrodes, which are polished to nanometer finish, are initially `activated' electrochemically and then pretreated by oxidation, reduction, or polishing. All electrodes give reversible cyclic voltammetric responses for the reduction of Ru(NH3)63+ in aqueous solution.Redox systems other than Ru(NH3)63+\\/2+ show characteristic electrochemical behavior

Frank Marken; Christopher A Paddon; Dhinesh Asogan

2002-01-01

72

Hydrogen storage material and process using graphite additive with metal-doped complex hydrides  

DOEpatents

A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH.sub.4. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

Zidan, Ragaiy (Aiken, SC); Ritter, James A. (Lexington, SC); Ebner, Armin D. (Lexington, SC); Wang, Jun (Columbia, SC); Holland, Charles E. (Cayce, SC)

2008-06-10

73

Analysis of hydrogen sorption characteristics of boron-doped activated carbons  

NASA Astrophysics Data System (ADS)

There is significant interest in the properties of boron-doped activated carbons for their potential to improve hydrogen storage.ootnotetextSee http://all-craft.missouri.edu Boron-doped activated carbons have been produced using a novel process involving the pyrolysis of a boron containing compound and subsequent high-temperature annealing. In this talk we will present a systematic study of the effect of different boron doping processes on the samples' surface area, micropore structure, and hydrogen sorption. Experimental results include boron content from prompt gamma neutron activation analysis, boron-carbon chemistry from Fourier transform infrared spectroscopy (FTIR), nitrogen subcritical adsorption, and 80K and 90K hydrogen adsorption isotherms which allow us to evaluate the hydrogen binding energy for each sorptive material.

Beckner, M.; Romanos, J.; Stalla, D.; Dohnke, E.; Singh, A.; Lee, M.; Suppes, G.; Hawthorne, M. F.; Yu, P.; Wexler, C.; Pfeifer, P.

2011-03-01

74

Magnetic and electrical characterization of heavily boron-doped diamond  

SciTech Connect

For a heavily boron-doped diamond (BDD) film, temperature variations of the electrical conductivity {sigma} and magnetic susceptibility {chi} are reported. The room temperature {sigma} {approx_equal}143 ({omega}-cm){sup -1} corresponds to a carrier concentration {approx_equal}10{sup 3} ppm, and its temperature variation yields an activation energy E{sub a} {approx_equal}28 meV from 140 to 300 K and E{sub a}{approx_equal}0.88 meV from 40 to 80 K. It is argued that larger boron doping leads to lower magnitudes of E{sub a}. The {chi} vs. T data (1.8-350 K) fits the Curie-Weiss law, with the concentration of paramagnetic species {approx_equal}120 ppm and a diamagnetic susceptibility {approx_equal}-0.4x10{sup -6} emu/g Oe. The results obtained from the measurements of {sigma} and {chi} are discussed and compared.

Manivannan, A.; Underwood, S.; Morales, Erie H.; Seehra, M.S

2003-12-15

75

Boron ?-doped (111) diamond solution gate field effect transistors.  

PubMed

A solution gate field effect transistor (SGFET) using an oxidised boron ?-doped channel on (111) diamond is presented for the first time. Employing an optimised plasma chemical vapour deposition (PECVD) recipe to deposit ?-layers, SGFETs show improved current-voltage (I-V) characteristics in comparison to previous similar devices fabricated on (100) and polycrystalline diamond, where the device is shown to operate in the enhancement mode of operation, achieving channel pinch-off and drain-source current saturation within the electrochemical window of diamond. A maximum gain and transconductance of 3 and 200?S/mm are extracted, showing comparable figures of merit to hydrogen-based SGFET. The oxidised device shows a site-binding model pH sensitivity of 36 mV/pH, displaying fast temporal responses. Considering the biocompatibility of diamond towards cells, the device's highly mutable transistor characteristics, pH sensitivity and stability against anodic oxidation common to hydrogen terminated diamond SGFET, oxidised boron ?-doped diamond SGFETs show promise for the recording of action potentials from electrogenic cells. PMID:22317833

Edgington, Robert; Ruslinda, A Rahim; Sato, Syunsuke; Ishiyama, Yuichiro; Tsuge, Kyosuke; Ono, Tasuku; Kawarada, Hiroshi; Jackman, Richard B

2012-01-08

76

Structural studies of ceramics based on detonation-wave-treated graphite-like boron nitride  

SciTech Connect

The formation of a structure during pressureless sintering of graphite-like boron nitride (BN) powders pretreated in detonation waves was studied. The treated powders contained 10-12% wurtzite BN phase and 2-3% sphalerite phase. During sintering at just 1200{degrees}C a reverse transformation from dense BN phases to graphite-like phases and primary recrystallization of highly fragmented BN{sub g} occur as a result of the pretreatment. Accretive recrystallization of BN{sub g} begins at 1500{degrees}C and at T = 1700-1950{degrees}C platy grains with a size of 1-3 {mu}m are formed in the developed surface. At 1700{degrees}C the density of the specimens reach 0.95 of the theoretical value. The specimens produced at 1950{degrees}C have a higher compressive strength and radiation resistance than do those made without pretreatment.

Savvakin, G.I.; Dubovik, T.V.; Oleinik, G.S. [Inst. of Materials Science, Kiev (Ukraine)

1995-11-01

77

Metallographic evaluation of the reactions between boronated graphite and Fe-Ni-Cr alloys  

SciTech Connect

The compatibility of boronated graphite with alloy 800H and type 316 stainless steel was evaluated metallographically after exposures at 700 and 810/sup 0/C for up to 10,000 h. At 700/sup 0/C, the principal reaction with both alloys was limited oxidation. At 810/sup 0/C, three types of reactions were observed: localized reactions at sites where the B/sub 4/C particles were in contact with the alloys' surfaces, intergranular penetration (much more prevalent for alloy 800H), and carburization.

Tortorelli, P.F.; Mayotte, J.R.; Henson, T.J.; DeVan, J.H.

1984-01-01

78

Effect of boron-doping on transparent conducting Al doped ZnO films for thin film solar cells  

Microsoft Academic Search

Al-doped ZnO (AZO) films with different boron (B) content have been prepared on glass substrates by co-sputtering of AZO (2wt. % Al2O3) and B-doped ZnO (BZO, 3wt. % B2O3) targets at room temperature. The B content in the B-doped AZO (BAZO) film was controlled by DC power on BZO target. X-ray diffraction analysis indicated that the B-doping improved the crystalline

Dong-Won Kang; Seung-Hee Kuk; Sung-Hwan Choi; Tae-Ho Moon; Heon-Min Lee; Min-Koo Han

2010-01-01

79

Effect of Boron doping on the electronic properties of the fullerenes of different sizes  

SciTech Connect

We report the results of the effect of Boron doping in C{sub n}; n = 28, 32, 36, 40, 44, 50 and 60 using the first principle calculation based on density functional theory. The HOMO-LUMO gap changes significantly with the decreasing fullerene size below C{sub 60}, with maximum gap observed for C{sub 32}. The HOMO-LUMO gap of Boron doped fullerenes varies significantly w.r.t. pure fullerenes. Also, the gap decreases for C{sub n-m}B{sub m}X, the boron doped fullerenes with exohedral alkali metals for n = 28, 32, 36, 40, 44, 50 and 60; m = 1 to 4; X = Li, Na and K. The Mulliken charge transfer from the exohedral alkali metals towards the various fullerene cages is altered marginally by the boron doping in fullerenes and follows the order K>Na>Li.

Agnihotri, Deepak [Department of Applied Sciences, Rayat and Bahra Institute of Engg. and Biotechnology, Sahauran, Mohali, Punjab 140104 (India); Sharma, Hitesh [Department of Physics, Punjab Technical University, Jalandhar, Punjab 144601 (India)

2011-12-12

80

Adsorption of hydrogen on boron-doped graphene: A first-principles prediction  

SciTech Connect

The doping effects of boron on the atomic adsorption of hydrogen on graphene have been investigated using density functional theory calculations. The hydrogen adsorption energies and electronic structures have been considered for pristine and B-doped graphene with the adsorption of hydrogen on top of carbon or boron atom. It is found that the B-doping forms an electron-deficient structure, and decreases the hydrogen adsorption energy dramatically. For the adsorption of hydrogen on top of other sites, similar results also have been found. These results indicate that the hydrogen storage capacity is improved by the doping of B atom.

Zhou, Yungang; Zu, Xiaotao T.; Gao, Fei; Nie, JL; Xiao, H. Y.

2009-01-01

81

Gold intercalation of boron-doped graphene on Ni(111): XPS and DFT study.  

PubMed

The intercalation of a graphene layer adsorbed on a metal surface by gold or other metals is a standard procedure. While it was previously shown that pristine, i.e., undoped, and nitrogen-doped graphene sheets can be decoupled from a nickel substrate by intercalation with gold atoms in order to produce quasi-free-standing graphene, we find the gold intercalation behavior for boron-doped graphene on a Ni(111) surface to be more complex: for low boron contents (2-5%) in the graphene lattice only partial gold intercalation occurs and for higher boron contents (up to 20%) no intercalation is observed. In order to understand this different behavior, a density functional theory investigation is carried out, comparing undoped as well as substitutional nitrogen- and boron-doped graphene on Ni(111). We identify the stronger binding of the boron atoms to the nickel substrate as the factor responsible for the different intercalation behavior in the case of boron doping. However, the calculations predict that this energetic effect prevents the intercalation process only for large boron concentrations and that it can be overcome for smaller boron coverages, in line with our x-ray photoelectron spectroscopy experiments. PMID:24056002

Zhao, W; Gebhardt, J; Gotterbarm, K; Höfert, O; Gleichweit, C; Papp, C; Görling, A; Steinrück, H-P

2013-09-20

82

Gold intercalation of boron-doped graphene on Ni(111): XPS and DFT study  

NASA Astrophysics Data System (ADS)

The intercalation of a graphene layer adsorbed on a metal surface by gold or other metals is a standard procedure. While it was previously shown that pristine, i.e., undoped, and nitrogen-doped graphene sheets can be decoupled from a nickel substrate by intercalation with gold atoms in order to produce quasi-free-standing graphene, we find the gold intercalation behavior for boron-doped graphene on a Ni(111) surface to be more complex: for low boron contents (2-5%) in the graphene lattice only partial gold intercalation occurs and for higher boron contents (up to 20%) no intercalation is observed. In order to understand this different behavior, a density functional theory investigation is carried out, comparing undoped as well as substitutional nitrogen- and boron-doped graphene on Ni(111). We identify the stronger binding of the boron atoms to the nickel substrate as the factor responsible for the different intercalation behavior in the case of boron doping. However, the calculations predict that this energetic effect prevents the intercalation process only for large boron concentrations and that it can be overcome for smaller boron coverages, in line with our x-ray photoelectron spectroscopy experiments.

Zhao, W.; Gebhardt, J.; Gotterbarm, K.; Höfert, O.; Gleichweit, C.; Papp, C.; Görling, A.; Steinrück, H.-P.

2013-11-01

83

Induction annealing and subsequent quenching : effect on the thermoelectric properties of boron-doped nanographite ensembles.  

SciTech Connect

Boron-doped nanographite ensembles (NGEs) are interesting thermoelectric nanomaterials for high temperature applications. Rapid induction annealing and quenching has been applied to boron-doped NGEs using a relatively low-cost, highly reliable, laboratory built furnace to show that substantial improvements in thermoelectric power factors can be achieved using this methodology. Details of the design and performance of this compact induction furnace as well as results of the thermoelectric measurements will be reported here.

Xie, M.; Lee, C. H.; Wang, J.; Yap, Y. K.; Bruno, P.; Gruen, D.; Singh, D.; Routbort, J.; Michigan Technological Univ.

2010-01-01

84

Structure and Mn 2+ adsorption properties of boron-doped goethite  

Microsoft Academic Search

Two kinds of boron-doped goethites were synthesized, one was called ad-B-goethite prepared by reacting the original goethite with borax solution and the other called oc-B-goethite prepared in the presence of boric acid solution. The goethites were characterized by IR and XRD. The IR bands of FeOHFe in-plane bending and free OH of the boron-doped goethites were weak compared with the

Shuijiao Liao; Juan Wang; Duanwei Zhu; Liying Ren; Jianwei Lu; Mingjian Geng; Alan Langdon

2007-01-01

85

Amperometric determination of sodium thiosulphate using boron-doped diamond electrodes applied to flow injection analysis  

Microsoft Academic Search

A boron-doped diamond (BDD) was used for the first time to study the electroanalysis of sodium thiosulphate in phosphate buffer (pH 6.7) using cyclic voltammetry and flow injection analysis (FIA). Glassy carbon (GC) electrode was also used in order to compare the results under identical experimental conditions. Thiosulphate was found to undergo irreversible electrooxidation on both electrodes. Boron-doped diamond showed

V. Suryanarayanan; Y. Zhang; S. Yoshihara; T. Shirakashi

2004-01-01

86

Boron-Doped Diamond Film Electrodes—New Tool for Voltammetric Determination of Organic Substances  

Microsoft Academic Search

This review with 194 references summarizes the recent progress in the development and applications of boron-doped diamond film electrodes in electroanalysis of organic compounds. It is based on the survey of 106 papers listed in a comprehensive table devoted to batch voltammetric and liquid flow amperometric methods using boron-doped diamond electrodes. The varieties in their construction, surface pre-treatment and electroanalytical

Karolina Pecková; Jana Musilová; Ji?í Barek

2009-01-01

87

Graphite.  

National Technical Information Service (NTIS)

Natural graphite is a mineral form of elemental carbon crystallized predominantly in the hexagonal system. Silicate minerals varying in kind and percentage are usually associated with graphite ore. The uses of natural graphite are dependent upon its physi...

H. A. Taylor

1985-01-01

88

Structure and superconductivity of isotope-enriched boron-doped diamond  

SciTech Connect

Superconducting boron-doped diamond samples were synthesized with isotopes of {sup 10}B, {sup 11}B, {sup 13}C and {sup 12}C. We claim the presence of a carbon isotope effect on the superconducting transition temperature, which supports the 'diamond-carbon'-related nature of superconductivity and the importance of the electron-phonon interaction as the mechanism of superconductivity in diamond. Isotope substitution permits us to relate almost all bands in the Raman spectra of heavily boron-doped diamond to the vibrations of carbon atoms. The 500 cm{sup 01} Raman band shifts with either carbon or boron isotope substitution and may be associated with vibrations of paired or clustered boron. The absence of a superconducting transition (down to 1.6 K) in diamonds synthesized in the Co-C-B system at 1900 K correlates with the small boron concentration deduced from lattice parameters.

Thompson, Joe D [Los Alamos National Laboratory; Ekimov, E A [INSTIT OF HIGH PRESSURE; Sidorov, V A [INSTIT OF HIGH PRESSURE; Zoteev, A [MOSCOW SU; Lebed, Y [INST FOR NUCI RES; Stishov, S M [INST FOR HIGH PRESSURE

2008-01-01

89

The influence of boron doping level on quality and stability of diamond film on Ti substrate  

NASA Astrophysics Data System (ADS)

In this study, we investigate the influence of boron doping level on film quality and stability of boron doped diamond (BDD) film deposited on titanium substrate (Ti/BDD) using microwave plasma chemical vapor deposition system. The results demonstrate that high boron concentration will improve the film conductivity, whereas the diamond film quality and adhesion are deteriorated obviously. The increase of total internal stress in the film and the variation of components within the interlayer will weaken the coating adhesion. According to the analysis of electrode inactivation mechanism, high boron doping level will be harmful to the electrode stability in the view of diamond quality and adhesion deterioration. In this study, 5000 ppm B/C ratio in the reaction gas is optimized for Ti/BDD electrode preparation.

Wei, J. J.; Li, Ch. M.; Gao, X. H.; Hei, L. F.; Lvun, F. X.

2012-07-01

90

Electrochemically modulated liquid chromatography using a boron-doped diamond particle stationary phase  

PubMed Central

This paper reports on preliminary tests of the performance of boron-doped diamond powder (BDDP) as a stationary phase in electrochemically modulated liquid chromatography (EMLC). EMLC manipulates retention through changes in the potential applied (Eappl) to a conductive packing. Porous graphitic carbon (PGC) has routinely been utilized as a material in EMLC separations. Herein the utility of BDDP as a stationary phase in EMLC was investigated and its stability, both compositionally and microstructurally, relative to PGC was compared. The results show that BDDP is stable over a wide range of Eappl values (i.e., ?1.2 to +1.2 V vs. Ag/AgCl, sat’d NaCl). The data also reveal that electrostatics play a key role in the adsorption of the aromatic sulfonates on the BDDP stationary phase, and that these analytes are more weakly retained in comparison to the PGC support. The potential for this methodology to provide a means to advance the understanding of molecular adsorption and retention mechanisms on carbonaceous materials is briefly discussed.

Muna, Grace W.; Swope, Vernon M.; Swain, Greg M.; Porter, Marc D.

2011-01-01

91

Graphitic electrodes modified with boron and nitrogen for electrochemical energy storage enhancement  

NASA Astrophysics Data System (ADS)

Electrodes based on carbon nanomaterials (carbon nanotubes or graphitic nanopetals) have been modified with boron (B) and nitrogen (N) through a facile microwave heating cycle. During the microwave heating, the electrodes are immersed in a precursor solution consisting of urea and boric acid dissolved in either water or methanol. After microwave heating and overnight vacuum drying, the electrodes are again heated in nitrogen to remove unreacted chemicals and to form CxBN. Hydrogen plasma was then used to remove any residual boron oxide from the surface of the electrodes. Carbon nanotubes modified with B and N exhibited higher lithium storage capacity as compared to pure carbon nanotube electrodes. We note that the modification appears to produce a highly unexpected and substantial cycle-to-cycle improvement in battery capacity as the electrode cycles through hundreds of charge-discharge iterations. This process can be applied to other carbon-based electrodes, which themselves are recognized for their high performance, to add further improvements.

Xiong, Guoping; Paul, Rajib; Reifenberger, Ron; Fisher, Timothy

2013-03-01

92

X-ray magnetic circular dichroism studies of Fe doped fullerene and highly oriented pyrolytic graphite  

Microsoft Academic Search

We report the x-ray magnetic circular dichroism (XMCD) studies on Fe doped fullerene thin film and bulk highly oriented pyrolytic graphite. The element-specific hysteresis curves were recorded by measuring the XMCD at the Fe L3 edge as a function of the applied field strength at different temperatures. These investigations suggest that Fe doped fullerene is ferromagnetic at room temperature, while

Amit Kumar; P. Thakur; N. B. Brookes; D. K. Avasthi

2009-01-01

93

Electrical properties of boron-doped diamond films synthesized by MPCVD on an iridium substrate  

Microsoft Academic Search

Boron-doped diamond films were synthesized on an iridium substrate by microwave plasma-assisted chemical vapor deposition, using trimethylboron as the dopant source. The Ir substrate was bias-treated by the constant-current mode to permit the formation of oriented diamond nuclei. In order to isolate the B-doped diamond layer electrically from the Ir substrate, the non-doped diamond particles that were formed were grown

Katsuki Kusakabe; Akira Sobana; Ken-Ichiro Sotowa; Toshihiko Imato; Toshiki Tsubota

2003-01-01

94

Cyclic voltammetry measurements on boron- and nitrogen-doped diamond layers  

Microsoft Academic Search

Diamond layers with different amounts of boron and nitrogen were deposited on silicon substrates in a hot-filament CVD reactor. These layers are characterized by the simultaneous deposition of diamond and graphite. Electrochemical properties were measured in acid and basic solutions to gain knowledge about their potential application as electrodes for industrial wastewater treatment or for other fields of electrochemistry. While

I. Gerger; R. Haubner

2005-01-01

95

Metallic and semimetallic properties of doped graphene and boron nitride planes  

NASA Astrophysics Data System (ADS)

This is a study on the effects of impurity doping on the density of states of the graphene plane as well as hexagonal boron nitride sheet within the random tight-binding model and Green's function technique. We consider dopants as boron and nitrogen atoms in graphene and carbon atoms in boron nitride plane. We find that the band width of graphene increases in the presence of impurity atoms. Furthermore, appearing a finite density of states at zero energy due to doping by both boron and nitrogen atoms leads to metallic property in the graphene sheet. Our results also show that doping by carbon reduces the band gap of the boron nitride system. In high concentration of carbon atoms, the density of states of boron nitride plane becomes similar to that of graphene sheet, resulting in semimetallic behavior. We also recognize that the van-Hove singularities in the density of states of both systems are broadened. Moreover, all effects of impurities on their density of states depend on doping concentrations.

Mousavi, Hamze; Moradian, Rostam

2013-01-01

96

Measurements of Increased Enthalpies of Adsorption for Boron-Doped Activated Carbons  

NASA Astrophysics Data System (ADS)

Boron-doping of activated carbons has been shown to increase the enthalpies of adsorption for hydrogen as compared to their respective undoped precursors (>10kJ/mol compared to ca. 5kJ/mol). This has brought significant interest to boron-doped carbons for their potential to improve hydrogen storage. Boron-doped activated carbons have been produced using a process involving the deposition of decaborane (B10H14) and high-temperature annealing resulting in boron contents up to 15%. In this talk, we will present a systematic study of the effect that boron content has on the samples' structure, hydrogen sorption, and surface chemistry. Measurements have shown a significant increase in the areal hydrogen excess adsorption and binding energy. Experimental enthalpies of adsorption will be presented for comparison to theoretical predictions. Additionally, samples have been characterized by thermal gravimetric analysis, gas chromatography-mass spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. TGA and GC-MS results investigated the decomposition of the decaborane in the carbon. Boron-carbon bonds are shown in the FTIR and XPS spectra, indicating that boron has been incorporated into the carbon matrix.

Gillespie, Andrew; Beckner, Matthew; Chada, Nagaraju; Schaeperkoetter, Joseph; Singh, Anupam; Lee, Mark; Wexler, Carlos; Burress, Jacob; Pfeifer, Peter

2013-03-01

97

Tribological properties of undoped and boron-doped nanocrystalline diamond films  

PubMed Central

Undoped and boron-doped nanocrystalline (NCD) diamond films were deposited on mirror polished Ti–6Al–4V substrates in a Microwave Plasma Assisted Chemical Vapor Deposition system. Sliding wear tests were conducted in ambient air with a nanotribometer. A systematic study of the tribological properties for both undoped and boron-doped NCD films were carried out. It was found for diamond/diamond sliding, coefficient of friction decreases with increasing normal loads. It was also found that the wear rate of boron-doped NCD films is about 10 times higher than that of undoped films. A wear rate of ~5.2×10?9 mm3/Nm was found for undoped NCD films. This value is comparable to the best known value of that of polished polycrystalline diamond films. Although no surface deformation, film delamination or micro-cracking were observed for undoped films, boron-doped NCD film undergoes a critical failure at a normal stress of 2.2 GPa, above which surface deformation is evident. Combined with high hardness and modulus, tunable conductivity and improved open air thermal stability, boron-doped nanocrystalline diamond film has tremendous potentials for applications such as Atomic Force Microscope probes, Micro-Electro-Mechanical System devices and biomedical sensors.

Liang, Qi; Stanishevsky, Andrei; Vohra, Yogesh K.

2009-01-01

98

Tribological properties of undoped and boron-doped nanocrystalline diamond films.  

PubMed

Undoped and boron-doped nanocrystalline (NCD) diamond films were deposited on mirror polished Ti-6Al-4V substrates in a Microwave Plasma Assisted Chemical Vapor Deposition system. Sliding wear tests were conducted in ambient air with a nanotribometer. A systematic study of the tribological properties for both undoped and boron-doped NCD films were carried out. It was found for diamond/diamond sliding, coefficient of friction decreases with increasing normal loads. It was also found that the wear rate of boron-doped NCD films is about 10 times higher than that of undoped films. A wear rate of ~5.2×10(-9) mm(3)/Nm was found for undoped NCD films. This value is comparable to the best known value of that of polished polycrystalline diamond films. Although no surface deformation, film delamination or micro-cracking were observed for undoped films, boron-doped NCD film undergoes a critical failure at a normal stress of 2.2 GPa, above which surface deformation is evident. Combined with high hardness and modulus, tunable conductivity and improved open air thermal stability, boron-doped nanocrystalline diamond film has tremendous potentials for applications such as Atomic Force Microscope probes, Micro-Electro-Mechanical System devices and biomedical sensors. PMID:19946362

Liang, Qi; Stanishevsky, Andrei; Vohra, Yogesh K

2009-11-28

99

Electrochemically induced surface modifications of boron-doped diamond electrodes: an X-ray photoelectron spectroscopy study  

Microsoft Academic Search

The activity of diamond electrodes depends on the chemical state of the diamond surface, and the present work is focussed on understanding how chemical changes either produced in situ electrochemically, or by ex situ plasma treatments, influence the electrochemical properties. Conductive boron-doped diamond electrodes were produced by depositing adherent boron-doped diamond films on tungsten substrates using a hot filament reactor

Christiaan H. Goeting; Frank Marken; Aurora Gutiérrez-Sosa; Richard G. Compton; John S. Foord

2000-01-01

100

Electrical properties of homoepitaxial boron-doped diamond thin films grown by chemical vapor deposition using trimethylboron as dopant  

Microsoft Academic Search

Boron-doped diamond was synthesized homoepitaxially on (100) diamond by microwave plasma-assisted chemical vapor deposition (MPCVD), using methane as the carbon source and trimethylboron as the boron source. The Hall mobility of the boron-doped films increased with increasing total reaction pressure under the conditions employed. The highest mobility at room temperature was achieved at a total pressure of 10.6kPa and was

Shigeharu Morooka; Terumi Fukui; Kiyohiko Semoto; Toshiki Tsubota; Takeyasu Saito; Katsuki Kusakabe; Hideaki Maeda; Yasunori Hayashi; Tanemasa Asano

1999-01-01

101

Room-temperature dissociative hydrogen chemisorption on boron-doped fullerenes  

NASA Astrophysics Data System (ADS)

Using first-principles electronic structure calculations, we show that trapping-mediated dissociative chemisorption of H2 molecules may occur on boron-doped fullerenes. Employing the Polanyi-Wigner equation and the van’t Hoff-Arrhenius law parameterized by the results of first-principles calculations, we find that a H2 molecule adsorbed on boron-doped fullerenes can be dissociated without additional catalysts. The dissociation occurs in ˜0.5ps at room temperature, which is also supported by independent molecular dynamics simulations. Our findings indicate that boron-doped fullerenes can be used as an atomic hydrogen storage material, but not a molecular hydrogen one, at ambient conditions.

Lee, Hoonkyung; Li, Jia; Zhou, Gang; Duan, Wenhui; Kim, Gunn; Ihm, Jisoon

2008-06-01

102

Atomistic boron-doped graphene field-effect transistors: a route toward unipolar characteristics.  

PubMed

We report fully quantum simulations of realistic models of boron-doped graphene-based field-effect transistors, including atomistic details based on DFT calculations. We show that the self-consistent solution of the three-dimensional (3D) Poisson and Schrödinger equations with a representation in terms of a tight-binding Hamiltonian manages to accurately reproduce the DFT results for an isolated boron-doped graphene nanoribbon. Using a 3D Poisson/Schrödinger solver within the non-equilibrium Green's function (NEGF) formalism, self-consistent calculations of the gate-screened scattering potentials induced by the boron impurities have been performed, allowing the theoretical exploration of the tunability of transistor characteristics. The boron-doped graphene transistors are found to approach unipolar behavior as the boron concentration is increased and, by tuning the density of chemical dopants, the electron-hole transport asymmetry can be finely adjusted. Correspondingly, the onset of a mobility gap in the device is observed. Although the computed asymmetries are not sufficient to warrant proper device operation, our results represent an initial step in the direction of improved transfer characteristics and, in particular, the developed simulation strategy is a powerful new tool for modeling doped graphene nanostructures. PMID:22876866

Marconcini, Paolo; Cresti, Alessandro; Triozon, François; Fiori, Gianluca; Biel, Blanca; Niquet, Yann-Michel; Macucci, Massimo; Roche, Stephan

2012-08-21

103

Barrier-free substitutional doping of graphene sheets with boron atoms: Ab initio calculations  

NASA Astrophysics Data System (ADS)

Using ab initio methods, we propose a simple and effective way to substitutionally dope graphene sheets with boron. The method consists of selectively exposing each side of the graphene sheet to different elements. We first expose one side of the membrane to boron while the other side is exposed to nitrogen. Proceeding this way, the B atoms will be spontaneously incorporated into the graphene membrane without any activation barrier. In a second step, the system should be exposed to a H-rich environment, which will remove the CN radical from the layer and form HCN, leading to a perfect substitutional doping.

Pontes, Renato B.; Fazzio, A.; Dalpian, Gustavo M.

2009-01-01

104

Synthesis of ultrathin nitrogen-doped graphitic carbon nanocages as advanced electrode materials for supercapacitor.  

PubMed

Synthesis of nitrogen-doped carbons with large surface area, high conductivity, and suitable pore size distribution is highly desirable for high-performance supercapacitor applications. Here, we report a novel protocol for template synthesis of ultrathin nitrogen-doped graphitic carbon nanocages (CNCs) derived from polyaniline (PANI) and their excellent capacitive properties. The synthesis of CNCs involves one-pot hydrothermal synthesis of Mn3O4@PANI core-shell nanoparticles, carbonization to produce carbon coated MnO nanoparticles, and then removal of the MnO cores by acidic treatment. The CNCs prepared at an optimum carbonization temperature of 800 °C (CNCs-800) have regular frameworks, moderate graphitization, high specific surface area, good mesoporosity, and appropriate N doping. The CNCs-800 show high specific capacitance (248 F g(-1) at 1.0 A g(-1)), excellent rate capability (88% and 76% capacitance retention at 10 and 100 A g(-1), respectively), and outstanding cycling stability (~95% capacitance retention after 5000 cycles) in 6 M KOH aqueous solution. The CNCs-800 can also exhibit great pseudocapacitance in 0.5 M H2SO4 aqueous solution besides the large electrochemical double-layer capacitance. The excellent capacitance performance coupled with the facile synthesis of ultrathin nitrogen-doped graphitic CNCs indicates their great application potential in supercapacitors. PMID:23425031

Tan, Yueming; Xu, Chaofa; Chen, Guangxu; Liu, Zhaohui; Ma, Ming; Xie, Qingji; Zheng, Nanfeng; Yao, Shouzhuo

2013-03-06

105

Controlled in situ boron doping of diamond thin films using solution phase  

NASA Astrophysics Data System (ADS)

Controlled boron doping of diamond film using nontoxic reagents is a challenge in itself. During the present study, attempts have been made to dope diamond films in situ with boron from a solution of boric acid (H3BO3) in methanol (CH3OH) using a specially designed bubbler that ensured continuous and controlled flow of vapors of boron precursors during deposition. The samples are thoroughly characterized using a host of techniques comprising of x-ray photoelectron spectroscopy, Raman, x-ray diffraction, and current-voltage measurements (I-V). Cross-sectional micro-Raman spectroscopy has been used to obtain depth profile of boron in diamond films. Boron concentration ([B]) in the films is found to vary linearly on a semilog scale with molarity (M) of H3BO3 in CH3OH. Lattice constant of our samples is smaller than the reported American society for testing and materials (ASTM) values due to oxygen incorporation and it increases with [B] in the diamond samples. Heavily boron doped samples exhibit Fano deformation of the Raman line shape and negative and/zero activation barrier in temperature dependent I-V measurements that indicate the formation of metallic phase in the samples. The present study illustrates the feasibility of safe and controlled boron doping of diamond films using a solution of H3BO3 in CH3OH over a significant range of [B] from semiconductor to metallic regime but with a little adverse effect due to unintentional but unavoidable incorporation of oxygen.

Roy, M.; Dua, A. K.; Nuwad, J.; Girija, K. G.; Tyagi, A. K.; Kulshreshtha, S. K.

2006-12-01

106

The electrochemical activity of boron-doped polycrystalline diamond thin film electrodes  

SciTech Connect

The electrochemical activity of [open quotes]as grown[close quotes] boron-doped polycrystalline diamond thin film electrodes has been studied using cyclic voltammetry, chronoamperometry, and ac impedance without external illumination. The resistivity of these materials after doping is ca. 10 ohm-cm. The diamond electrodes possess a low double layer capacitance and a relatively high polarization resistance toward surface oxidation. Slow electrode kinetics are observed for Fe(CN)[sub 6][sup 3[minus]/4[minus

Swain, G.M.; Ramesham, R. (Auburn Univ., AL (United States))

1993-02-15

107

The electrochemical activity of boron-doped polycrystalline diamond thin film electrodes  

Microsoft Academic Search

The electrochemical activity of [open quotes]as grown[close quotes] boron-doped polycrystalline diamond thin film electrodes has been studied using cyclic voltammetry, chronoamperometry, and ac impedance without external illumination. The resistivity of these materials after doping is ca. 10 ohm-cm. The diamond electrodes possess a low double layer capacitance and a relatively high polarization resistance toward surface oxidation. Slow electrode kinetics are

Greg M. Swain; Rajeshuni. Ramesham

1993-01-01

108

Formation of graphitic structures in cobalt- and nickel-doped carbon aerogels.  

PubMed

We have prepared carbon aerogels (CAs) doped with cobalt or nickel through sol-gel polymerization of formaldehyde with the potassium salt of 2,4-dihydroxybenzoic acid, followed by ion exchange with M(NO3)2 (where M = Co2+ or Ni2+), supercritical drying with liquid CO2, and carbonization at temperatures between 400 and 1050 degrees C under a N2 atmosphere. The nanostructures of these metal-doped carbon aerogels were characterized by elemental analysis, nitrogen adsorption, high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Metallic nickel and cobalt nanoparticles are generated during the carbonization process at about 400 and 450 degrees C, respectively, forming nanoparticles that are approximately 4 nm in diameter. The sizes and size dispersion of the metal particles increase with increasing carbonization temperatures for both materials. The carbon frameworks of the Ni- and Co-doped aerogels carbonized below 600 degrees C mainly consist of interconnected carbon particles with a size of 15-30 nm. When the samples are pyrolyzed at 1050 degrees C, the growth of graphitic nanoribbons with different curvatures is observed in the Ni- and Co-doped carbon aerogel materials. The distance of graphite layers in the nanoribbons is approximately 0.38 nm. These metal-doped CAs retain the overall open cell structure of metal-free CAs, exhibiting high surface areas and pore diameters in the micro- and mesoporic region. PMID:15779927

Fu, Ruowen; Baumann, Theodore F; Cronin, Steve; Dresselhaus, Gene; Dresselhaus, Mildred S; Satcher, Joe H

2005-03-29

109

Magnetism of Co doped graphitic ZnO layers adsorbed on Si and Ag surfaces  

NASA Astrophysics Data System (ADS)

The effect of the substrate on Co doped graphitic ZnO layers adsorbed on metallic and semiconductor surfaces are investigated. The first principles results reveal that the magnetic interactions are strongly affected by the substrate. While graphitic layers of ZnO:Co on the well controlled metallic Ag(111) surface present weak ferromagnetic stability, on the semiconductor Si(111) surface they are strongly ferromagnetic coupled. The presence of metallic states in ZnO:Co adsorbed on Ag(111) surface favors a superexchange mechanism, weakening the ferromagnetic interaction. On the other hand, the magnetism of few layers of ZnO:Co on Si(111) surface is governed by a direct exchange mechanism, favoring a ferromagnetic coupling. This confined II-VI system doped with transition metal on a semiconductor surface presents higher magnetic stability than III-V nanostructures, and it is desired for nanostructured oxide/semiconductor room temperature ferromagnetism, using silicon technology.

Fernandes, Marcelo; Schmidt, Tome M.

2013-09-01

110

Conductivity enhancement by fluorine doping in boron-doped ZnO thin films deposited by the electrospraying method  

NASA Astrophysics Data System (ADS)

ZnO thin films co-doped with boron and fluorine (B, F-ZnO) were deposited by the electrospraying method onto a heated glass substrate. The characteristics of the films were investigated as a function of dopant concentrations in the solution. X-ray diffraction studies revealed that all the prepared films were polycrystalline in nature and exhibited the ZnO hexagonal wurtzite structure with preferential orientation along the (002) crystal plane. In addition, shift in the XRD patterns was observed and the crystal orientation was changed at a certain amount of fluorine (>6 at%) in the starting solution. Analyses of X-ray diffraction and X-ray energy dispersive patterns demonstrate that fluorine and boron have been successfully doped into the ZnO thin films. Like these studies, the scanning electron micrographs showed that the grain size tends to decrease by the addition of fluorine. It was also observed that 2 at% boron and 6 at% fluorine was the optimal amount in order to achieve the minimum resistivity and maximum transmittance. The minimum value of resistivity of about 1.01×10-4 ? cm and high optical transmittance of 98% in the visible region were obtained for 2 at% boron and 6 at% fluorine co-doped ZnO films. Moreover, the present values of resistivities are closest to the lowest resistivity values among the doped ZnO films and also closer to the indium tin oxide (ITO) resistivities that were previously reported. We confirmed that the boron and fluorine atoms substitution in the ZnO lattice imparts positive effects in terms of enhancing the free carrier concentration and density of films, which will further improve the electrical and optical properties. The films produced at optimum conditions are suitable for optical and electrical applications owing to their low resistivity and high optical transmittance in the visible range.

Mahmood, Khalid; Park, Seung Bin

2012-12-01

111

Intergranular fracture tendency in NiAl doped with boron and carbon  

SciTech Connect

Near-stoichiometric NiAl alloys produced by powder metallurgy, or by conventional casting and fabrication, exhibit mainly intergranular fracture at ambient temperatures. NiAl doped with 300 wt ppm C also shows grain boundary fracture at room temperature, whereas NiAl doped with 300 wt ppm B exhibits mainly transgranular fracture. George and Liu concluded that boron segregation increases grain boundary cohesion and suppresses intergranular fracture in near-stoichiometric NiAl. In addition to suppressing intergranular fracture, boron additions dramatically increase the yield strength and reduce plastic deformation in NiAl at room temperature. The purpose of this study is to further examine these two factors, i.e., enhancement of grain boundary cohesion and reduction of strain incompatibility, by compression tests of near-stoichiometric NiAl alloys doped separately with 300 wt ppm B and C at room temperature. These alloys were chosen because both carbon and boron increase strength significantly, but only boron suppresses grain boundary fracture. Compression tests were used in this study to obtain plastic deformation beyond yielding and thus ensure strain incompatibility at the grain-boundary region. The results obtained so far provide additional evidence that grain boundaries in NiAl are relatively weak and that boron segregation increases grain boundary cohesion in NiAl.

Liu, C.T.; Lee, E.H.; George, E.P.; Duncan, A.J. (Oak Ridge National Lab., TN (United States))

1994-02-15

112

Effect of nitrogen addition on the morphology and structure of boron-doped nanostructured diamond films  

NASA Astrophysics Data System (ADS)

A chemical vapor deposition hydrogen/methane/nitrogen feedgas mixture with unconventional high methane (15% CH4 by volume) normally used to grow ultrahard and smooth nanostructured diamond films on Ti-6Al-4V alloy substrates was modified to include diborane (10% B2H6 in hydrogen) for boron doping. The flow rates of N2 were varied to investigate its effect on plasma chemistry, film morphology, and mechanical properties. As expected, boron is readily incorporated into the diamond film and results in a change in the lattice parameter. Nitrogen, on the other hand, competes with boron in the plasma and acts to prevent boron incorporation into the diamond structure. Glancing angle x-ray diffraction indicates a decrease of diamond lattice parameter with increasing N2/CH4 flow rate ratio. A critical N2/CH4 ratio of 0.4 was found to result in a film with a minimum in grain size and surface roughness, along with high boron incorporation (~4×1020 cm-3). As shown from this critical limit, experimental conditions can be optimized to produce ultrahard, boron doped nanostructured diamond films with the potential for high temperature applications.

Liang, Qi; Catledge, Shane A.; Vohra, Yogesh K.

2003-12-01

113

Electrochemical degradation of the dye indigo carmine at boron-doped diamond anode for wastewaters remediation  

Microsoft Academic Search

Here we demonstrate that anodic oxidation with a boron-doped diamond (BDD) electrode can be applied to the remediation of wastewaters containing indigo carmine. This environmentally friendly method decontaminates completely acid and alkaline aqueous solutions of this dye. The degradation rate increases with increasing current and dye concentration. Indigo carmine is more rapidly removed in alkaline than in acid medium, but

Salah Ammar; Ridha Abdelhedi; Cristina Flox; Conchita Arias; Enric Brillas

2006-01-01

114

Influence of Surface Termination of Boron-Doped Diamond on Superconducting Property  

NASA Astrophysics Data System (ADS)

In 2004, a heavily boron-doped diamond was found to be a superconductor Since then, a superconducting diamond has attracted considerable attention, mainly explored for fundamental properties and a theoretical basis. Meanwhile, it is known that the surface of diamond is easily modified by a chemical treatment, and the physical properties, such as surface conductivity, could be modulated through the surface modification. Here, we report modulation of superconducting properties of a heavily boron-doped diamond by tuning the surface electronic state. A heavily boron-doped diamond was prepared onto a silicon wafer substrate by a microwave plasma-assisted chemical vapor deposition method. The surface of a boron-doped diamond was changed between hydrogen- and oxygen-termination by thermal and electrochemical reactions, respectively. As a result, the critical current and the diamagnetic magnetization value could be modulated in a reversible manner between the hydrogen- and oxygen-terminated diamonds with maintenance of the superconducting transition temperature. It is assumed that the carrier density at grain boundaries would change due to the induced dipole moment via surface modification, resulting in modulation of the magnetic flux pinning effect at grain boundaries.

Natsui, Keisuke; Yamamoto, Takashi; Watanabe, Takeshi; Einaga, Yasuaki

2012-02-01

115

Electrochemical detection of tricyclic antidepressant drugs by HPLC using highly boron-doped diamond electrodes  

Microsoft Academic Search

Boron-doped diamond (BDD) electrodes have been examined for the electrochemical detection of six tricyclic antidepressant drugs (TCAs): imipramine, desipramine, clomipramine, amitriptyline, nortriptyline, and doxepin. Cyclic voltammetry, flow injection analysis (FIA) and HPLC with electrochemical detection have been used to study the oxidation reactions and to detect the TCAs. At diamond electrodes, well-defined and highly reproducible voltammograms were obtained for all

T. A. Ivandini; B. V. Sarada; C. Terashima; T. N. Rao; D. A. Tryk; H. Ishiguro; Y. Kubota; A. Fujishima

2002-01-01

116

Oxidation at boron doped diamond electrodes: an effective method to mineralise triazines  

Microsoft Academic Search

The electrochemical oxidation of cyanuric acid (CA) is examined by bulk electrolyses at boron doped diamond (BDD) electrode. The influence of operating conditions on the reaction trend is investigated and suitable conditions for oxidative demolition of CA are individuated. In particular a strong effect of current density and pH is evidenced, being neutral pH and high current the most favourable

Anna Maria Polcaro; Annalisa Vacca; Michele Mascia; Simonetta Palmas

2005-01-01

117

Conversion of carbon dioxide to peroxycarbonate at boron-doped diamond electrode  

Microsoft Academic Search

An electrochemical method has been developed for the efficient conversion of carbon dioxide to peroxycarbonate on a boron-doped diamond electrode under mild conditions. The process could be carried out in a batch operation as well as in a flow-system operation. The current efficiency for producing peroxycarbonate decreased significantly with increasing the temperature. A current efficiency of ca. 70% can be

Madhu Sudan Saha; Tsuneto Furuta; Yoshinori Nishiki

2004-01-01

118

The electrooxidation of organic acids at boron-doped diamond electrodes  

Microsoft Academic Search

The electrooxidation of citric acid, malic acid, alanine and cysteine at boron-doped diamond (BDD) electrodes and glassy carbon (GC) electrodes was investigated by use of cyclic voltammetry. Well-defined, irreversible peaks were obtained for the oxidation of citric acid and cysteine. Malic acid and alanine exhibit discernible responses. This preliminary study has shown that BDD has better sensitivity than GC for

O Chailapakul; E Popa; H Tai; B. V Sarada; D. A Tryk; A Fujishima

2000-01-01

119

TOPICAL REVIEW: Selected topics related to the transport and superconductivity in boron-doped diamond  

NASA Astrophysics Data System (ADS)

This contribution deals with a few topics closely related to the superconductivity in the heavily boron-doped diamond which are, in our opinion, not properly treated in the current literature. Attention is paid especially to the classification of metallic and insulating state, selection of pairing mechanism, limits of weak coupling approximation and to the influence of granularity on the superconducting transition.

Mareš, Ji?íJ; Hubík, Pavel; Krištofik, Jozef; Nesládek, Miloš

2008-12-01

120

Sintering Kinetics of Pure and Doped Boron Carbide. Final Technical Report.  

National Technical Information Service (NTIS)

The sintering of pure and doped boron carbide was investigated over the temperature range 1898 exp 0 to 2380 exp 0 K and at additive levels ranging from 0.75 to 10.0 wt%. The addition of 0.75 and 3.8 wt% of AlF sub 3 , Ni, Fe, and Cu resulted in a deactiv...

R. G. Lange Z. A. Munir

1976-01-01

121

Mineralization of bisphenol A (BPA) by anodic oxidation with boron-doped diamond (BDD) electrode  

Microsoft Academic Search

Anodic oxidation of bisphenol A (BPA), a representative endocrine disrupting chemical, was carried out using boron-doped diamond (BDD) electrode at galvanostatic mode. The electro-oxidation behavior of BPA at BDD electrode was investigated by means of cyclic voltammetric technique. The extent of degradation and mineralization of BPA were monitored by HPLC and total organic carbon (TOC) value, respectively. The results obtained,

M. Murugananthan; S. Yoshihara; T. Rakuma; T. Shirakashi

2008-01-01

122

Growth and electrical characterisation of ?-doped boron layers on (111) diamond surfaces  

NASA Astrophysics Data System (ADS)

A plasma enhanced chemical vapor deposition protocol for the growth of ?-doping of boron in diamond is presented, using the (111) diamond plane as a substrate for diamond growth. AC Hall effect measurements have been performed on oxygen terminated ?-layers and desirable sheet carrier densities (~1013 cm-2) for field-effect transistor application are reported with mobilities in excess of what would expected for equivalent but thicker heavily boron-doped diamond films. Temperature-dependent impedance spectroscopy and secondary ion mass spectroscopy measurements show that the grown layers have metallic-like electrical properties with high cut-off frequencies and low thermal impedance activation energies with estimated boron concentrations of approximately 1020 cm-3.

Edgington, Robert; Sato, Syunsuke; Ishiyama, Yuichiro; Morris, Richard; Jackman, Richard B.; Kawarada, Hiroshi

2012-02-01

123

Compressive behavior of kinking nonlinear elastic solids: Titanium silicon carbide, graphite, mica and boron nitride  

NASA Astrophysics Data System (ADS)

Dislocation-based deformation in crystalline solids is almost always plastic. Once dislocations are generated they entangle and render the process irreversible. In our recent work we show that this does not apply to a new class of materials, best characterized as kinking nonlinear elastic (KNE) solids. KNE solids include the MAX phases, mica, graphite, boron nitride, so called nonlinear mesoscopic elastic (NME) solids discussed in geological literature and most probably ice. The MAX phases are a new class of layered machinable ternary carbides and nitrides, with the chemical formula M n+1AXn, where M is an early transition metal, A is an A-group element (mostly IIIA and IVA) and X is C or N. The compressive loading-unloading stress-strain curves of KNE solids in the elastic regime outline nonlinear, fully reversible, reproducible, rate-independent, closed hysteresis loops whose shape and extent of energy dissipated are strongly influenced by grain size with the energy dissipated being significantly larger in the coarse-grained material. This unique property is attributed to the formation and annihilation of incipient kink bands (IKBs), defined to be thin plates of sheared material bounded by opposite walls of dislocations. As long as the dislocation walls remain attached, the response is fully reversible. Furthermore, because the dislocations are confined to the basal planes work hardening does not occur and the dislocations can move reversibly over relatively large distances. This kind of dislocation motion renders KNE solids potentially high damping material. The loss factor for Ti3SiC2, a prime member of KNE solids, is higher than most woods, and comparable to polypropylene and nylon. At higher temperatures or stress, since the IKB dissociate and coalesce to form regular irreversible kink bands. The close hystesis loops are open, the response is strain-rate dependent, and cyclic hardening is observed even at 1200°C.

Zhen, Tiejun

124

Direct visualization of boron dopant distribution and coordination in individual chemical vapor deposition nanocrystalline B-doped diamond grains  

NASA Astrophysics Data System (ADS)

The boron dopant distribution in individual heavily boron-doped nanocrystalline diamond film grains, with sizes ranging from 100 to 350 nm in diameter, has been studied using a combination of high resolution annular dark field scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy. Using these tools, the boron distribution and local boron coordination have been determined. Quantification results reveal embedding of B dopants in the diamond lattice, and a preferential enrichment of boron at defective areas and twin boundaries. Coordination mapping reveals a distinct difference in coordination of the B dopants in ``pristine'' diamond areas and in defective regions.

Lu, Ying-Gang; Turner, Stuart; Verbeeck, Johan; Janssens, Stoffel D.; Wagner, Patrick; Haenen, Ken; Van Tendeloo, Gustaaf

2012-07-01

125

Transition-Metal Strings Templated on Boron-Doped Carbon Nanotubes: A DFT Investigation  

SciTech Connect

The binding nature, magnetic, and electronic properties of transition-metal (TM) monatomic chains anchored on boron-doped single-walled carbon nanotubes (B-SWCNTs) are studied using density-functional theory. The TM systems studied here include Au, Pt, Ru, Pd, Ag, Co, Ni, Cu, W, and Ti, which are well-known for their technical importance. In conjunction, prototype semiconducting SWCNT(8,0) and metallic SWCNT(6,6) were chosen to model the general features of B-doped SWCNTs. It is found that the TM-strings exhibit well-defined covalent bonds with the boron-doped SWCNTs, in contrast to the pristine SWCNTs. The TMstring/ B-SWCNT composites exhibit high stability and unexpected electronic properties, which are relevant to applications in nanoelectronics, spintronics, nanocatalysis, and sensor devices.

An, Wei; Turner, C. H.

2009-08-27

126

Fabrication of vertically aligned diamond whiskers from highly boron-doped diamond by oxygen plasma etching.  

PubMed

Conductive diamond whiskers were fabricated by maskless oxygen plasma etching on highly boron-doped diamond substrates. The effects of the etching conditions and the boron concentration in diamond on the whisker morphology and overall substrate coverage were investigated. High boron-doping levels (greater than 8.4 × 10(20) cm(-3)) are crucial for the formation of the nanosized, densely packed whiskers with diameter of ca. 20 nm, length of ca. 200 nm, and density of ca. 3.8 × 10(10) cm(-2) under optimal oxygen plasma etching conditions (10 min at a chamber pressure of 20 Pa). Confocal Raman mapping and scanning electron microscopy illustrate that the boron distribution in the diamond surface region is consistent with the distribution of whisker sites. The boron dopant atoms in the diamond appear to lead to the initial fine column formation. This simple method could provide a facile, cost-effective means for the preparation of conductive nanostructured diamond materials for electrochemical applications as well as electron emission devices. PMID:21214209

Terashima, Chiaki; Arihara, Kazuki; Okazaki, Sohei; Shichi, Tetsuya; Tryk, Donald A; Shirafuji, Tatsuru; Saito, Nagahiro; Takai, Osamu; Fujishima, Akira

2011-01-07

127

Influence of oxygen on defect production in electron-irradiated, boron-doped silicon  

NASA Astrophysics Data System (ADS)

Deep level transient spectroscopy (DLTS) measurements were made on float-zone and crucible-grown, boron-doped silicon irradiated with 1-MeV electrons. The minority carrier trap attributed to a boron-related state, was not seen in low-resistivity, float-zone silicon. However, a new majority carrier trap was observed in these samples. In the case of more lightly doped material the minority carrier trap was present, and its introduction rate was lower in float-zone than in crucible-grown silicon. For 1- and 10-ohm-cm float-zone material that was oxidized during processing, the introduction rates for this trap were comparable to those for crucible-grown silicon. This behavior indicates that the minority carrier trap involves oxygen and that it may be due to a boron-oxygen complex. The majority carrier trap seen in heavily doped, float-zone silicon may also involve boron but not oxygen. Observed trap concentrations suggest that oxygen content in the regions examined by DLTS is affected by processing techniques. Other differences were observed in defect production and annealing behavior of electron-irradiated, float-zone and crucible-grown silicon.

Deangelis, H. M.; Drevinsky, P. J.

128

Defect-induced Symmetry Distortions in Doped Cubic Boron Nitride  

NASA Astrophysics Data System (ADS)

We have studied the substitution of silicon and beryllium for boron in cubic boron nitride with several first-principles methods. The Be and Si defects are proto-typical p- and n-type dopants respectively.(O. Mishima, S. Yamoka, and O. Fukunaga, Science 238), 181 (1987). The substitutionals have orbitally degenerate ground states leading to symmetry-lowering distortions of the Td point-group symmetry about the boron sites. Calculated IR absorption modes associated with the defects are compared with recent experimental determination of bulk modes.(M. I. Eremets, M. Gauthier, A. Polian, J. C. Chervin, J. M. Besson, G. A. Dubitskii, and Y. Y. Semenova, Phys. Rev. B 52), 8854 (1995). Changes in Fermi contact interaction terms as an effect of the distortions are discussed as a possible way of characterizing the distortions experimentally.

Patton, David C.; Harrison, Joseph G.

1996-03-01

129

Determination of trace impurities in boron nitride by graphite furnace atomic absorption spectrometry and electrothermal vaporization inductively coupled plasma optical emission spectrometry using solid sampling  

Microsoft Academic Search

Two digestion-free methods for trace analysis of boron nitride based on graphite furnace atomic absorption spectrometry (GFAAS) and electrothermal vaporization inductively coupled plasma spectrometry optical emission (ETV-ICP-OES) using direct solid sampling have been developed and applied to the determination of Al, Ca, Cr, Cu, Fe, Mg, Mn, Si, Ti and Zr in four boron nitride materials in concentration intervals of

P. Barth; J. Hassler; I. Kudrik; V. Krivan

2007-01-01

130

Tracer diffusion in pure and boron-doped Ni/sub 3/Al  

SciTech Connect

Diffusion of /sup 63/Ni has been measured in polycrystalline Ni/sub 3/Al as a function of temperature, Al concentration, and boron doping. Volume and grain-boundary diffusion of /sup 60/Co and /sup 68/Ge has been measured in undoped Ni/sub 3/Al. The results are discussed in terms of the defect structure of Ni/sub 3/Al, and it is shown that the vacancy behavior in the bulk is not responsible for the increased segregation of boron to the grain boundaries in hypostoichiometric alloys. 11 refs., 4 figs., 1 tab.

Hoshino, K.; Rothman, S.J.; Averback, R.S.

1987-01-01

131

Electronic and transport properties of boron and nitrogen doped graphene nanoribbons: an ab initio approach  

NASA Astrophysics Data System (ADS)

Graphene nanoribbons (GNRs) are expected to display extraordinary properties in the form of nanostructures. The effect of boron and nitrogen substitutional doping at four successive positions on electronic and transport properties of zigzag graphene nanoribbons (ZGNRs) is studied using spin-unpolarized density functional theory. It has been observed that the electronic structures of the doped ZGNRs are different from those of pristine ZGNRs. We have also calculated the transformation energy in the form of total energy. The substitutional boron atom at the nanoribbons edges suppresses the energy band near Fermi level by changing properties of material from metallic to semi-metallic in ZGNRs which can be explained as a consequence of the edge polarization effects. At all doping positions, N-doped ZGNRs are n-type while B-doped ZGNRs are p-type semiconductors. These substitutionally B- and N-doped impurities act as scattering centers for transport in GNRs. Due to unusual properties of these nanomaterials, they can be used in carbon-based nanoelectronics devices.

Chauhan, Satyendra Singh; Srivastava, Pankaj; Shrivastava, Ashwani Kumar

2013-04-01

132

Plasma Synthesized Doped Boron Nanopowder for MgB2 Superconductors. Phase II SBIR Final Scientific/Technical Report.  

National Technical Information Service (NTIS)

Under this program, a process to synthesize nano-sized doped boron powder by a plasma synthesis process was developed and scaled up from 20 gram batches at program start to over 200 grams by program end. Over 75 batches of boron nanopowder were made by RF...

J. V. Marzik

2012-01-01

133

Electrochemical behaviour of SnO 2 doped with boron and indium in anodes for lithium secondary batteries  

Microsoft Academic Search

Nanoparticles of SnO2 were doped with boron and indium for use as active anode materials in non-aqueous lithium batteries. The cells thus obtained were found to exhibit between 1.0 and 0.0 V their best cycling properties. Undoped SnO2 and particularly low boron-doped samples exhibited the best electrochemical characteristics, as reflected in an increased specific capacity and in improved cycling properties.

Julián Morales; Luis Sánchez

1999-01-01

134

Cobalt monoxide-doped porous graphitic carbon microspheres for supercapacitor application  

NASA Astrophysics Data System (ADS)

A novel design and facile synthesis process for carbon based hybrid materials, i.e., cobalt monoxide (CoO)-doped graphitic porous carbon microspheres (Co-GPCMs), have been developed. With the synthesis strategy, the mixture of cobalt gluconate, ?-cyclodextrin and poly (ethylene oxide)106-poly (propylene oxide)70-poly (ethylene oxide)106 is treated hydrothermally, followed by pyrolysis in argon. The resultant Co-GPCMs exhibits a porous carbon matrix with localized graphitic structure while CoO nanodots are embedded in the carbon frame. Thus, the Co-GPCMs effectively combine the electric double-layer capacitance and pseudo-capacitance when used as the electrode in supercapacitor, which lead to a higher operation voltage (1.6 V) and give rise to a significantly higher energy density. This study provides a new research strategy for electrode materials in high energy density supercapacitors.

Yang, Zheng-Chun; Tang, Chun-Hua; Zhang, Yu; Gong, Hao; Li, Xu; Wang, John

2013-10-01

135

Cobalt monoxide-doped porous graphitic carbon microspheres for supercapacitor application.  

PubMed

A novel design and facile synthesis process for carbon based hybrid materials, i.e., cobalt monoxide (CoO)-doped graphitic porous carbon microspheres (Co-GPCMs), have been developed. With the synthesis strategy, the mixture of cobalt gluconate, ?-cyclodextrin and poly (ethylene oxide)106-poly (propylene oxide)70-poly (ethylene oxide)106 is treated hydrothermally, followed by pyrolysis in argon. The resultant Co-GPCMs exhibits a porous carbon matrix with localized graphitic structure while CoO nanodots are embedded in the carbon frame. Thus, the Co-GPCMs effectively combine the electric double-layer capacitance and pseudo-capacitance when used as the electrode in supercapacitor, which lead to a higher operation voltage (1.6?V) and give rise to a significantly higher energy density. This study provides a new research strategy for electrode materials in high energy density supercapacitors. PMID:24113335

Yang, Zheng-Chun; Tang, Chun-Hua; Zhang, Yu; Gong, Hao; Li, Xu; Wang, John

2013-10-11

136

Cobalt monoxide-doped porous graphitic carbon microspheres for supercapacitor application  

PubMed Central

A novel design and facile synthesis process for carbon based hybrid materials, i.e., cobalt monoxide (CoO)-doped graphitic porous carbon microspheres (Co-GPCMs), have been developed. With the synthesis strategy, the mixture of cobalt gluconate, ?-cyclodextrin and poly (ethylene oxide)106-poly (propylene oxide)70-poly (ethylene oxide)106 is treated hydrothermally, followed by pyrolysis in argon. The resultant Co-GPCMs exhibits a porous carbon matrix with localized graphitic structure while CoO nanodots are embedded in the carbon frame. Thus, the Co-GPCMs effectively combine the electric double-layer capacitance and pseudo-capacitance when used as the electrode in supercapacitor, which lead to a higher operation voltage (1.6?V) and give rise to a significantly higher energy density. This study provides a new research strategy for electrode materials in high energy density supercapacitors.

Yang, Zheng-Chun; Tang, Chun-Hua; Zhang, Yu; Gong, Hao; Li, Xu; Wang, John

2013-01-01

137

Gallium doped in armchair and zigzag models of boron phosphide nanotubes (BPNTs): A NMR study  

NASA Astrophysics Data System (ADS)

The electrical properties and NMR parameters of the pristine and Ga-doped structures of two representative (8, 0) zigzag and (4, 4) armchair of boron phosphide nanotubes (BPNTs) have been investigated. The structural geometries of above nanotubes have been allowed to relax by optimization and then the isotropic and anisotropic chemical shielding parameters (CSI and CSA) of 11B and 31P have been calculated based on DFT theory. The results reveal that the influence of Ga-doping was more significant on the geometries of the zigzag model than the armchair one. The difference of band gap energies between the pristine and Ga-doped armchair BPNTs was larger than the zigzag model. Significant differences of NMR parameters of those nuclei directly contributed to the Ga-doping atoms have been observed.

Rezaei-Sameti, M.

2012-09-01

138

Tuning the electronic and magnetic properties of triangular boron nitride quantum dots via carbon doping  

NASA Astrophysics Data System (ADS)

The energetic stability, electronic and magnetic properties of carbon-doped triangular boron nitride quantum dots (BNQDs) were investigated using first principle calculation within density functional theory (DFT). Different edge structures, doping positions, and carbon concentrations are considered. We found that the substitutional C atom energetically prefers to reside in the minority sublattice of the BNQDs, and the planner structures of the BNQDs are well preserved. When the carbon dopant moves from the inner to the outer region of the BNQDs, the HOMO-LUMO gap decreases in an oscillating way, which is even smaller than that of graphene quantum dots. After carbon doping, BNQDs have non-zero magnetic moment ground states. There is an impurity state above or below the Fermi level of C-doped BNQDs, depending on substituting majority or minority sublattice. This offers a promising way of tuning the electronic and magnetic properties of BNQDs.

Xi, Yan; Zhao, Xiaoyang; Wang, Aizhu; Wang, Xiaopeng; Bu, Hongxia; Zhao, Mingwen

2013-03-01

139

Capacitance performance enhancement of TiO 2 doped with Ni and graphite  

Microsoft Academic Search

Nano-amorphous TiO2 was prepared by a sol-gel method. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) show that\\u000a the composite electrode material (TiO2-NiO-C) is made of powder with a grain size of 36.2 nm. Doping of nickel and graphite can increase the electrical conductivity\\u000a and the specific surface area of nano-amorphous TiO2. The electrochemical properties of TiO2-NiO-C,

Hong Wang; Zhiyuan Tang; Lei Sun; Yanbing He; Yaxian Wu; Zhongyan Li

2009-01-01

140

Room temperature photoluminescence property of boron-doped sol-gel silica  

SciTech Connect

Room temperature photoluminescence (PL) of boron-doped silica synthesized by a combined sol-gel and heating process has been investigated. The broad PL band has been resolved into three components centered at 3.7, 3.35 and 2.7 eV, which are assigned to non-bridging oxygen hole centers (NBOHC), carbon-related impurity, and two-fold coordinated silicon atoms, respectively. The intensities of the 3.35 and 2.7 eV bands decrease with the heating temperature increasing, due to oxidation of the corresponding luminescent centers. The effect of boron doping on the formation of intrinsic defects in silica is discussed.

He Haiping; Wang Yuxia; Zou Youming

2004-05-05

141

Magnetic states and optical properties of single-layer carbon-doped hexagonal boron nitride  

NASA Astrophysics Data System (ADS)

We show that carbon-doped hexagonal boron nitride (h-BN) has extraordinary properties with many possible applications. We demonstrate that the substitution-induced impurity states, associated with carbon atoms, and their interactions dictate the electronic structure and properties of C-doped h-BN. Furthermore, we show that stacking of localized impurity states in small C clusters embedded in h-BN forms a set of discrete energy levels in the wide gap of h-BN. The electronic structures of these C clusters have a plethora of applications in optics, magneto-optics, and opto-electronics.

Park, Hyoungki; Wadehra, Amita; Wilkins, John W.; Castro Neto, Antonio H.

2012-06-01

142

Analysis of Hybrid Type Boron-Doped Carbon Stripper Foils in J-PARC RCS  

NASA Astrophysics Data System (ADS)

J-PARC (Japan-Proton Accelerator Research Complex) requires a carbon stripper foil to strip electrons from the H- beam supplied by the linac before injection into the Rapid Cycling Synchrotron (RCS) [1]. The foil thickness is about ?m (200?g/cm2) corresponding to conversion efficiency of 99.7% from the primary H- beams of 181MeV energy to H+. We have successfully developed the Hybrid type thick Boron-doped Carbon (HBC) stripper foil, which showed a drastic improvement the lifetime without thickness reduction and shrinkage at the irradiated area. We started to study carbon stripper foils microscopically why carbon foils have considerable endurance for the beam impact by boron-doped. At first step, we made a comparison of ion irradiation effect between normal carbon and HBC by the electric microscope, ion-induced analysis. In particular, it seems that grain size of boron-rich area became much larger by irradiation for HBC. It was also observed that the boron-rich grain grew up by taking around material and generated pinholes more than 100 nm near itself consequently.

Yamazaki, Y.; Yoshimoto, M.; Takeda, O.; Kinsho, M.; Taguchi, T.; Yamamoto, S.; Kurihara, T.; Sugai, I.

2013-03-01

143

On the exceptional negative Seebeck effect in 3d-doped ?-rhombohedral boron  

Microsoft Academic Search

Interstitial doping with 3d-elements impact the electronic properties of ?-rhombohedral boron significantly; in some cases high negative Seebeck coefficients occur. The explanation by simple charge transfer is excluded. We attribute these effects to the correlation among the diluted 3d atoms generating a specific system of electronic states in the band gap. The interaction with Ogitsu’s antiferromagnetic Ising model, describing the

H. Werheit

2011-01-01

144

Electron field emission from composite electrodes of carbon nanotubes-boron-doped diamond and carbon felts  

Microsoft Academic Search

The electron field emission of carbon nanotube (CNT)\\/boron-doped diamond (BDD)\\/carbon felt electrodes (CNT\\/BDD\\/felt) have been investigated. The composite electrode was initially prepared with the growth of BDD on carbon felt and the subsequent growth of CNT by chemical decomposition of methanol. The composite electrodes were characterised using scanning electron microscopy and transmission electron microscopy. For the CNT\\/BDD\\/felt samples, the electron

J. Mauricio Rosolen; Simone Tronto; Marcel S. Marchesin; Erica C. Almeida; Neidenei G. Ferreira; C. H. Patrick Poa´; S. Ravi P. Silva

2006-01-01

145

Electrochemical oxidation of phenolic wastes with boron-doped diamond anodes  

Microsoft Academic Search

The electrochemical oxidation of several phenolic aqueous wastes has been studied using a bench-scale plant with a single-compartment electrochemical flow cell. Boron-doped diamond materials were used as the anode. Complete mineralization of the waste was obtained in the treatment of phenols not substituted with chlorine or nitrogen. Chlorinated phenolic compounds were transformed into carbon dioxide; volatile organochlorinated compounds and nitro-substituted

P. Cañizares; J. Lobato; R. Paz; M. A. Rodrigo; C. Sáez

2005-01-01

146

Influence of cations during Orange-II degradation on boron-doped diamond electrode  

Microsoft Academic Search

This paper reports a comparative study on the anodic oxidation of 50mg\\/L Acid Orange II in the presence of different supporting electrolytes. Experiments have been performed with a batch recirculation reactor containing one-compartment cell equipped with boron-doped diamond anode and Pt cathode. Specifically, the effect of cation is examined among a series of inorganic salts while keeping the anion constant.

Chunyong Zhang; Jinliang Wang; Taketoshi Murakami; Akira Fujishima; Degang Fu; Zhongze Gu

2010-01-01

147

Development of Highly Conductive Boron-Doped Microcrystalline Silicon Films for Application in Solar Cells  

Microsoft Academic Search

We have examined the deposition of highly conductive boron-doped microcrystalline silicon (muc-Si:H) films for application in solar cells. Depositions were conducted in a very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) chamber. In the deposition processes, various substrate temperatures (TS) were applied. Highly conductive p-type microcrystalline silicon films were obtained at substrate temperature lower than 210°C. The factors

Qing-Song Lei; Zhi-Meng Wu; Jian-Ping Xi; Xin-Hua Geng; Ying Zhao; Jian Sun

2006-01-01

148

Improving corrosion-resistance of polysilicon using boron doping and self-induced galvanic bias  

Microsoft Academic Search

In this paper we report upon two novel methods for improving the corrosion resistance of silicon-glass micropackages in high temperature saline soak tests. By using boron doping and\\/or galvanic biasing, we have shown that the dissolution of polysilicon can be reduced from more that 1 ?m \\/day to less than 90 Å\\/day. Physical mechanisms for polysilicon corrosion are also presented.

Brian H. Stark; Mehmet R. Dokmeci; Khalil Najafi

2003-01-01

149

Production and characterization of boron- and silicon-doped carbon clusters  

Microsoft Academic Search

Boron- and silicon-doped carbon clusters of the type BmCn (m = 1?4) and SimCn (m = 1, 2) have been produced via the laser-vaporization cluster beam technique. The observed features of the intensity distribution in mass spectra suggest that B atoms can be incorporated into the clusters with much higher efficiency than Si atoms. The mass spectral evidence is also

Takumi Kimura; Toshiki Sugai; Hisanori Shinohara

1996-01-01

150

Electrochemical oxidation of perfluorobutane sulfonate using boron-doped diamond film electrodes  

Microsoft Academic Search

This research investigated oxidation of perfluorobutane sulfonate (PFBS) at a boron-doped diamond (BDD) film anode. PFBS oxidation\\u000a produced carbon dioxide, sulfate, fluoride, and trace amounts of trifluoroacetic acid (TFA). Rate constants for PFBS oxidation\\u000a as a function of current density and temperature were measured using a rotating disk electrode (RDE) reactor. Reaction rates\\u000a in the RDE reactor were zeroth order

Zhaohui Liao; James Farrell

2009-01-01

151

Electrochemical incineration of dimethyl phthalate by anodic oxidation with boron-doped diamond electrode  

Microsoft Academic Search

The anodic oxidation of aqueous solutions containing dimethyl phthalate (DMP) up to 125 mg\\/L with sodium sulfate (Na2SO4) as supporting electrolyte within the pH range 2.0–10.0 was studied using a one-compartment batch reactor employing a boron-doped diamond (BDD) as anode. Electrolyses were carried out at constant current density (1.5–4.5 mA\\/cm2). Complete mineralization was always achieved owing to the great concentration

Yining HOU; Jiuhui QU; Xu ZHAO; Huijuan LIU

2009-01-01

152

Effects of boron-doping on the morphology and magnetic property of carbon nanotubes  

Microsoft Academic Search

Boron carbide nanotubes (nano-fibers) was prepared by B powder and carbon nanotubes (CNTs) at high temperature in a vacuumed\\u000a quartz tube. The morphology, microstructure, component and magnetic property of samples were characterized by transmission\\u000a electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and magnetic property measurement\\u000a system (MPMS) controller. The results showed that B-doping CNTs have great difference

Qi Jiang; Lan Qian; Jing Yi; Xiaotong Zhu; Yong Zhao

2007-01-01

153

Kinetics of ultrasound-enhanced electrochemical oxidation of diuron on boron-doped diamond electrodes  

Microsoft Academic Search

Freshwater polluted with herbicides is an environmental problem of concern due to the high toxicity and non-biodegradability of these compounds. This work analyses for the first time the degradation and mineralization of diuron (N-(3,4-dichlorophenyl)-N,N-dimethyl-urea), considered priority substance by the European Commission, by electrochemical oxidation (EO) at a boron-doped diamond anode enhanced by low frequency (20kHz) ultrasound (US). A synergistic analysis

Eugenio Bringas; Juan Saiz; Inmaculada Ortiz

2011-01-01

154

Boron-doped diamond anodic treatment of olive mill wastewaters: Statistical analysis, kinetic modeling and biodegradability  

Microsoft Academic Search

The electrochemical treatment of olive mill wastewaters (OMW) over boron-doped diamond (BDD) electrodes was investigated. A factorial design methodology was implemented to evaluate the statistically important operating parameters, amongst initial COD load (1000–5000mg\\/L), treatment time (1–4h), current intensity (10–20A), initial pH (4–6) and the use of 500mg\\/L H2O2 as an additional oxidant, on treatment efficiency; the latter was assessed in

Efthalia Chatzisymeon; Nikolaos P. Xekoukoulotakis; Evan Diamadopoulos; Alexandros Katsaounis; Dionissios Mantzavinos

2009-01-01

155

Electrodeposition of metal adlayers on boron-doped diamond thin-film electrodes  

Microsoft Academic Search

A preliminary investigation of the electrochemical deposition of Pt, Pb, and Hg adlayers on conductive diamond thin-film surfaces ha been made using cyclic voltammetry and scanning electron microscopy. The diamond thin films employed were polycrystalline, grown on conductive Si substrates (1 cm²) to a thickness of ca. 14 μm, and doped with boron at a nominal atomic concentration ranging between

Mohamad Awada; J. W. Strojek; G. M. Swain

1995-01-01

156

Oxidation of carboxylic acids at boron-doped diamond electrodes for wastewater treatment  

Microsoft Academic Search

Thin boron-doped diamond films have been prepared by HF CVD (hot filament chemical vapour deposition technique) on conductive p-Si substrate (Si\\/Diamond). The morphology of these Si\\/diamond electrodes has been investigated by SEM and Raman spectroscopy. The electrochemical behaviour of the Si\\/diamond electrodes in 1 M H2SO4 and in 1 M H2SO4 + carboxylic acids has been investigated by cyclic voltammetry.

D. Gandini; E. Mahé; P. A. Michaud; W. Haenni; A. Perret; Ch. Comninellis

2000-01-01

157

Tyrosinase-modified boron-doped diamond electrodes for the determination of phenol derivatives  

Microsoft Academic Search

Highly boron-doped diamond (BDD) electrodes were modified covalently with tyrosinase for the determination of estrogenic phenol derivatives. BDD was anodically polarized for the introduction of hydroxyl groups onto its surface, then treated with (3-aminopropyl)triethoxysilane and finally coated with a tyrosinase film cross-linked with glutaraldehyde. The modified electrodes responded amperometrically to phenol derivatives including estrogenic derivatives, bisphenol-A and 17?-estradiol, at ?0.3

Hideo Notsu; Tetsu Tatsuma; Akira Fujishima

2002-01-01

158

The electrooxidation of sulfur-containing compounds at boron-doped diamond electrode  

Microsoft Academic Search

The electrooxidation of homocysteine, glutathione (GSH), 2-mercapto ethanesulfonic acid and cephalexin at boron-doped diamond (BDD) electrodes and glassy carbon (GC) electrodes was investigated by cyclic voltammetry. The oxidation of these sulfur-containing compounds exhibited well-defined irreversible responses. This preliminary study has shown that BDD has better sensitivity than GC. Concentration dependence has been studied and indicated the promise of using BDD

O. Chailapakul; P. Aksharanandana; T. Frelink; Y. Einaga; A. Fujishima

2001-01-01

159

Anodic oxidation of 2-naphthol at boron-doped diamond electrodes  

Microsoft Academic Search

The anodic oxidation of 2-naphthol in acid media was investigated at a synthetic boron-doped diamond thin film electrode (BDD) using cyclic voltammetry and bulk electrolysis. The results have shown that in the potential region, where the supporting electrolyte is stable, reactions involving simple electron transfer, such as oxidation of 2-naphthol to naphthoxy radical and 1,4-naphthoquinone occur. Polymeric materials, which lead

M. Panizza; P. A. Michaud; G. Cerisola; Ch. Comninellis

2001-01-01

160

Temperature-dependent mechanical and electrical properties of boron-doped piezoresistive nanocantilevers  

NASA Astrophysics Data System (ADS)

In this paper, the temperature-dependent mechanical and electrical properties of boron-doped silicon piezoresistive nanocantilevers are reported. The surfaces of the 100 nm thick nanocantilevers are doped with boron using a spin-on diffusion method and fabricated using nano-machining technology. The frequency responses of piezoresistive nanocantilevers at room temperature are measured by both optical detection and piezoresistive detection methods. Reduction of the temperature leads to an increase in the resonant frequency and the Q factor. The temperature coefficient of the resonant frequency is found to be as high as 210 ppm K-1 in the range of 140-240 K. The high temperature coefficient compared to that of single crystal silicon cantilevers originates from the residual stress after boron doping. The increase in the Q factor by decreasing the temperature is considered to be due to some surface dissipation mechanisms. A maximum value for the longitudinal piezoresistance coefficient is observed in the range of 80-90 K, whilst it was considered that the piezoresistive coefficient increases monotonically with decreasing temperature.

Jiang, Yonggang; Ono, Takahito; Esashi, Masayoshi

2009-06-01

161

Boron carbide spherical particles encapsulated in graphite prepared by pulsed laser irradiation of boron in liquid medium  

Microsoft Academic Search

B4C submicron particles were obtained by laser irradiation of B particles in ethyl acetate under atmospheric pressure and room temperature. Absorbed laser energy brought about B melting and decomposition of surrounding liquid medium molecules, leading to a reaction between the melted B and carbon species to form B4C. Moreover, the obtained B4C particles were encapsulated in a graphite layer. Such

Yoshie Ishikawa; Yoshiki Shimizu; Takeshi Sasaki; Naoto Koshizaki

2007-01-01

162

Wavelength dependence of the Brillouin spectral width of boron doped germanosilicate optical fibers.  

PubMed

Boron co-doped germanosilicate fibers are investigated via the Brillouin light scattering technique using two wavelengths, 1534 nm and 1064 nm. Several fibers are investigated, including four drawn from the same preform but at different draw temperatures. The Stokes' shifts and the Brillouin spectral widths are found to increase with increasing fiber draw temperature. A frequency-squared law has adequately described the wavelength dependence of the Brillouin spectral width of conventional Ge-doped fibers. However, it is found that unlike conventional Ge-doped fibers these fibers do not follow the frequency-squared law. This is explained through a frequency-dependent dynamic viscosity that modifies this law. PMID:20940778

Law, Pi-Cheng; Dragic, Peter D

2010-08-30

163

Effects of magnesium doping on growth and electric conductivity of nanocrystalline cubic boron nitride thin films  

NASA Astrophysics Data System (ADS)

We have achieved in situ magnesium doping into nanocrystalline cubic boron nitride thin films during sputter deposition. It was clarified, through x-ray diffraction, Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy, that less than 1 at% magnesium doping does not significantly affect the growth of the cubic phase. Magnesium-doped films deposited in pure argon showed electric conductivity up to 104 times higher than the undoped film. Although the Hall voltage was not reproduced reliably for most of the cases, the films containing 2.1 at% magnesium clearly revealed p-type conduction with carrier concentration and mobility of 4 × 1014 cm-3 and 6 cm2 V-1 s-1, respectively, at 380 K. It was also found that the increase in electric conductivity with magnesium concentration was accompanied by the decrease in the relative amount of nitrogen in the film.

Kojima, K.; Nose, K.; Kambara, M.; Yoshida, T.

2009-03-01

164

Surface chemistry of boron-doped SiO(sub 2) CVD: Enhanced uptake of tetraethyl orthosilicate by hydroxyl groups bonded to boron.  

National Technical Information Service (NTIS)

Insight into how dopants can enhance deposition rates has been obtained by comparing reactivities of tetraethyl orthosilicate (TEOS, Si(OCH(sub 2)CH(sub 3))(sub 4)) with silanol and boranol groups on SiO(sub 2). This comparison is relevant for boron-doped...

M. E. Bartram H. K. Moffat

1993-01-01

165

Electronic level scheme in boron- and phosphorus-doped silicon nanowires.  

PubMed

We report the first observation of the electronic level scheme in boron (B)- and phosphorus (P)-doped nanowires (NWs). The NWs' morphology dramatically depends on the doping impurity while a few deep electronic levels appear in both kinds of nanowires, independently of the doping type. We demonstrate that the doping impurities induce the same shallow levels as in bulk silicon. The presence of two donor levels in the lower half-bandgap is also revealed. In both kinds of NWs, B- and P-doped, the donor level (0/+) at E(v) + 0.36 eV of the gold-hydrogen complex is observed. This means that the gold diffusion from the NW tip introduces an electronically active level, which might negatively affects the electrical characteristics of the NWs. In P-doped NWs, we observed a further donor level at 0.26 eV above the valence band due to the phosphorus-vacancy pairs, the E-center, well-known in bulk silicon. These findings seriously question both diffusion modeling of impurities in NWs and the technological aspects arising from this. PMID:22545949

Sato, Keisuke; Castaldini, Antonio; Fukata, Naoki; Cavallini, Anna

2012-05-03

166

Experimental evaluation of neutron performance in boron-doped low activation concrete.  

PubMed

Reaction rate distribution in concrete with/without boron dopant up to a thickness of 60 cm was measured using Yayoi fast reactor located at University of Tokyo. The 7 reaction rates such as (197)Au(n,gamma), (59)Co(n,gamma), (115)In(n,n'), (55)Mn(n,gamma), (23)Na(n,gamma), (94)Zr(n,gamma) and (96)Zr(n,gamma) were measured at 12 different depths, and the reduction of the reaction rate as a result of boron doping was quantitatively analysed. These reaction rates were also used to determine epithermal neutron spectrum shape parameter. Monte Carlo simulations of the experimental setup were performed using the MCNP-5 code. Simulated depth profiles of reaction rates and the epithermal neutron spectrum shape parameter agreed with the experimental results with fair accuracy. This experimental results provide useful data to benchmark the accuracy of neutron transport codes in the prediction of transmission and neutron spectrum distortion in boron-doped concrete. PMID:20172934

Ogawa, T; Morev, M N; Abe, T; Iimoto, T; Kosako, T; Kimura, K; Kinno, M

2010-02-19

167

Photoluminescence investigations of cubic boron nitride doped with neodymium during high-pressure synthesis  

NASA Astrophysics Data System (ADS)

Micropowders of cubic boron nitride doped with neodymium are prepared under high-pressure and high-temperature conditions. The phase composition of the micropowders is studied using X-ray diffractometry and X-ray fluorescence analysis. The photoluminescence, photoluminescence excitation spectra, and the life-time of the 4 F 3/2 excited state of Nd ions introduced into cubic boron nitride are investigated. In photoluminescence spectra of the micropowders, structured bands are recorded in the range of the 4 F 3/2 ? 4 I 9/2 and 4 F 3/2 ? 4 I 11/2 electronic transitions. A higher intensity of the first structured band indicates that the corresponding photoluminescence in cubic boron nitride doped with neodymium is excited by the “three-level scheme.” It is demonstrated that an increase in the concentration of the neodymium compound in the growth batch leads to the formation of two luminescence centers Nd1 and Nd2 formed by neodymium ions located in different low-symmetry crystal fields in the micropowders. This is confirmed by X-ray diffraction investigations and the study of the photoluminescence decay curves. The 4 F 3/2 short-lived state is assigned to the Nd ions forming the Nd1 centers, and the long-lived state is attributed to the Nd ions forming the Nd2 centers.

Shishonok, E. M.; Leonchik, S. V.; Bodiou, L.; Braud, A.

2009-09-01

168

Ion-exchanged route synthesis of Fe2N-N-doped graphitic nanocarbons composite as advanced oxygen reduction electrocatalyst.  

PubMed

Fe2N nanoparticles and nitrogen-doped graphitic nanosheet composites (Fe2N-NGC) have been synthesized by an ion-exchanged route, which can serve as an efficient non-precious metal electrocatalyst with a 4e(-) reaction pathway for oxygen reduction reactions (ORR). PMID:23462844

Wang, Lei; Yin, Jie; Zhao, Lu; Tian, Chungui; Yu, Peng; Wang, Jianqiang; Fu, Honggang

2013-04-14

169

Surface modification of thick SiC gradient coatings on doped graphite under long pulse plasma irradiation  

NASA Astrophysics Data System (ADS)

Selection of candidate plasma facing materials (PFM) in experimental fusion device is very important due to its direct influence on the plasma performance. To meet the requirements of high power and steady state operation, one kind of multi-element doped graphite GBST1308 (1%B4C, 2.5%Si, 7.5%Ti) with thick SiC gradient coatings was chosen as the main limiter materials for the HT-7 device. Surface modification of the SiC coatings on doped graphite under long pulse plasma irradiation was carefully investigated by examining the surface morphology, structure, and atomic composition. The obtained results showed the crystal structure of SiC was replaced by lamellar matter or film with plentiful oxygen and some other elements existed in the surface of graphite tiles after the plasma irradiation.

Xie, C. Y.; Chen, J. L.; Li, J. G.; Fang, Q. F.

2007-06-01

170

Diamond ultraviolet photovoltaic cell obtained by lithium and boron doping  

SciTech Connect

Polycrystalline high quality freestanding 300-{mu}m-thick diamond films were doped by diffusion of B and Li under electric bias in order to fabricate vertical p-n junctions. Circular contacts were obtained by high dose ion implantation of B and Li. The I{endash}V characteristics were rectifying. When illuminated by deuterium lamp, an open circuit voltage was 2.6 eV. The shape of the I{endash}V characteristic under illumination points to the existence of shunt and series resistances. The obtained structure is most probably a p-n junction with bad contacts. {copyright} {ital 1997 American Institute of Physics.}

Popovici, G. [Nuclear Engineering Department, University of Missouri-Columbia, Columbia, Missouri 65211 (United States); Melnikov, A.; Varichenko, V.V. [Physics Department, Minsk State University, Minsk (Belarus); Sung, T.; Prelas, M.A. [Nuclear Engineering Department, University of Missouri-Columbia, Columbia, Missouri 65211 (United States); Wilson, R.G. [Hughes Research Laboratories, Malibu, California 90265 (United States); Loyalka, S.K. [Particulate Systems Research Center, University of Missouri-Columbia, Columbia, Missouri 65211 (United States)

1997-03-01

171

Electrical properties and far infrared optical conductivity of boron-doped single-walled carbon nanotube films.  

PubMed

Here we report a new approach for producing clean and homogeneous boron-doped single-walled carbon nanotubes. This approach combines the homogeneous dispersion of B(n)O(m)(+) ionic molecules over the nanotube surfaces in a liquid solution, with a high temperature chemical reaction that incorporates the boron atoms into the sp(2) carbon network of the nanotube wall. A comparative study of sheet resistance versus optical transmission in nanotube network films with and without boron-doping is also presented. Although electron energy loss spectroscopy revealed very low B-doping levels (<1 at.%), the dc conductivity of doped samples was raised by a factor of 3.4. Changes in the free carrier contribution to the optical conductivity of single-walled carbon nanotube (SWCNT) films induced by boron-doping was also studied via optical transmission in the far-infrared (IR) (50-7000 cm(-1)). A Drude model was fitted to the changes in the far-IR conductivity to quantify the additional free carrier concentration induced by the B-doping. PMID:21386503

Liu, X M; Gutiérrez, H R; Eklund, P C

2010-08-04

172

Specific heat and electronic states of superconducting boron-doped silicon carbide  

NASA Astrophysics Data System (ADS)

The discoveries of superconductivity in the heavily-boron doped semiconductors diamond (C:B) in 2004 [Ekimov , Nature (London)NATUAS10.1038/nature02449 428, 542 (2004)] and silicon (Si:B) in 2006 [Bustarret , Nature (London)NATUAS10.1038/nature05340 444, 465 (2006)] have renewed the interest in the physics of the superconducting state of doped semiconductors. Recently, we discovered superconductivity in the closely related “mixed” system heavily boron-doped silcon carbide (SiC:B) [Ren , J. Phys. Soc. Jpn.JUPSAU10.1143/JPSJ.76.103710 76, 103710 (2007)]. Interestingly, the latter compound is a type-I superconductor whereas the two aforementioned materials are type II. In this paper, we present an extensive analysis of our recent specific-heat study, as well as the band structure and expected Fermi surfaces. We observe an apparent quadratic temperature dependence of the electronic specific heat in the superconducting state. Possible reasons are a nodal gap structure or a residual density of states due to nonsuperconducting parts of the sample. The basic superconducting parameters are estimated in a Ginzburg-Landau framework. We compare and discuss our results with those reported for C:B and Si:B. Finally, we comment on possible origins of the difference in the superconductivity of SiC:B compared to the two “parent” materials C:B and Si:B.

Kriener, M.; Maeno, Y.; Oguchi, T.; Ren, Z.-A.; Kato, J.; Muranaka, T.; Akimitsu, J.

2008-07-01

173

Hydrogen hosting on aluminum-doped boron clusters: Density functional theory  

NASA Astrophysics Data System (ADS)

The geometries, stabilities, and energetics of aluminum doped boron clusters, up to 13-atom, and their various hydrogenated complexes have been investigated via the density functional theory (DFT). The geometry optimizations have been carried out by using B3LYP functional and 6-311++G11 basis set. Up to 5-atom clusters arrangements of the atoms, in the most stable structures, have two-dimensional forms. From 6- to 13-atom clusters three-dimensional forms are favored by the lowest energy structures. Hydrogen hosting effects the structures of AlBn clusters. Adding an Al atom to the cage B12 leads structural changes but hydrogenated boron, B12H12 can resist to Al effect.

Böyükata, Mustafa; Güvenç, Ziya B.

2009-11-01

174

Litteraturstudie av Interkalering i Grafit och Bornitrid (Literature Survey of Intercalation in Graphite and Boron Nitride).  

National Technical Information Service (NTIS)

In an article of R.D. Bardo (J. de Phys. IV (1995) C4-561), an explosive with a lower sensitivity than TATB and an energy content of 6.57 MJ/kg, is suggested to be formed when HNO(sub 3) is intercalated in hexagonal boron nitride. No description of how to...

E. Bemm

2000-01-01

175

Density functional investigation of CO adsorption on Ni-doped single-walled armchair (5,5) boron nitride nanotubes.  

PubMed

The adsorption of CO onto Ni-doped boron nitride nanotubes (BNNTs) was investigated using density functional theory at the B3LYP/LanL2DZ level of theory. The structures of the Ni-doped BNNTs and their CO-adsorbed configurations were obtained. It was found that the strength of adsorption of CO onto Ni-doped perfect BNNTs is higher than that on defective BNNTs. The electronic properties of all of the adsorption configurations of CO on Ni-doped BNNTs are reported. PMID:22864627

Tontapha, Sarawut; Ruangpornvisuti, Vithaya; Wanno, Banchob

2012-08-04

176

Plasma Synthesized Doped Boron Nanopowder for MgB2 Superconductors  

SciTech Connect

Under this program, a process to synthesize nano-sized doped boron powder by a plasma synthesis process was developed and scaled up from 20 gram batches at program start to over 200 grams by program end. Over 75 batches of boron nanopowder were made by RF plasma synthesis. Particle sizes were typically in the 20-200 nm range. The powder was synthesized by the reductive pyrolysis of BCl{sub 3} in hydrogen in an RF plasma. A wide range of process parameters were investigated including plasma power, torch geometry, gas flow rates, and process pressure. The powder-in-tube technique was used to make monofilament and multifilament superconducting wires. MgB{sub 2} wire made with Specialty Materials plasma synthesized boron nanopowder exhibited superconducting properties that significantly exceeded the program goals. Superconducting critical currents, J{sub c}, in excess of 10{sup 5} A cm{sup -2} at magnetic fields of 8 tesla were reproducibly achieved. The upper critical magnetic field in wires fabricated with program boron powder were H{sub c2}(0) = 37 tesla, demonstrating the potential of these materials for high field magnet applications. T{sub c} in carbon-doped MgB{sub 2} powder showed a systematic decrease with increasing carbon precursor gas flows, indicating the plasma synthesis process can give precise control over dopant concentrations. Synthesis rates increased by a factor of 400% over the course of the program, demonstrating the scalability of the powder synthesis process. The plasma synthesis equipment at Specialty Materials has successfully and reproducibly made high quality boron nanopowder for MgB{sub 2} superconductors. Research and development from this program enabled Specialty Materials to successfully scale up the powder synthesis process by a factor of ten and to double the size of its powder pilot plant. Thus far the program has been a technical success. It is anticipated that continued systematic development of plasma processing parameters, dopant chemistry and concentration, wire processing technology, and collection technology will lead to the commercialization of boron nanopowder as a precursor for MgB{sub 2} superconductors. Potential commercial applications include magnets for magnetic resonance imaging (MRI), fault current limiters, wind turbine generators.

James V. Marzik

2012-03-26

177

Electrochemical analysis of nucleic acids at boron-doped diamond electrodes.  

PubMed

Highly conductive boron-doped diamond (BDD) electrodes are well suited for performing electrochemical measurements of nucleic acids in aqueous solution under diffusion-only control. The advantageous properties of this electrodic material in this context include reproducibility and the small background currents observed at very positive potentials, along with its robustness under extreme conditions so offering promising capabilities in future applications involving thermal heating or ultrasonic treatment. tRNA, single and double stranded DNA and 2'-deoxyguanosine 5'-monophosphate (dGMP) have been studied and well defined peaks were observed in all cases, directly assignable to the electro-oxidation of deoxyguanosine monophosphate. PMID:11996354

Prado, César; Flechsig, Gerd-Uwe; Gründler, Peter; Foord, John S; Markenc, Frank; Compton, Richard G

2002-03-01

178

Electrochemical oxidation of saline industrial wastewaters using boron-doped diamond anodes  

Microsoft Academic Search

Similarly to other catalytic advanced oxidation processes electro-oxidation by means of boron-doped diamond (BDD) anodes generates a very efficient oxidant media containing, among others, hydroxyl radicals. In this work BDD electro-oxidation is demonstrated to be an efficient alternative to treat a wide variety of saline industrial effluents, which main properties were as follows: TOC=266–4479mg\\/L; [N-NH3]=61–1150mg\\/L; [Cl?]=1996–37,645mg\\/L; conductivity=5.6–64mS\\/cm. Experiments were conducted

Angela Anglada; Raquel Ibañez; Ane Urtiaga; Inmaculada Ortiz

2010-01-01

179

Chemisorption of Transition-Metal Atoms on Boron- and Nitrogen-Doped Carbon Nanotubes: Energetics and Geometric and Electronic Structures  

SciTech Connect

The well-defined binding between transition-metals (TM) and the sidewall of carbon nanotubes (CNTs) plays a key role in the performance of CNT-based anoelectronics, as well as the stability of catalysts used in either heterogeneous catalysis or fuel-cell electrocatalysis. Spin-polarized density functional theory calculations demonstrate that either boron or nitrogen doping can increase the binding strength of TM atoms with singlewall carbon nanotubes (SWCNTs), and comparatively, boron doping is more effective. The binding nature can be identified as chemisorption, based on the magnitude of the binding energy and the formation of multiple bonds. The chemisorbed TM atoms can modify the electronic structure of the doped nanotubes in various ways, depending upon the TM and helicity of the CNT, rendering the TM/doped-SWCNT composite viable for a wide range of applications. A total of 11 technologically relevant TMs adsorbed on two distinct and stable doped-SWCNT models have been investigated in this study. The doping sites are arranged in either a locally concentrated or uniform fashion within semiconducting SWCNT(8,0) and metallic SWCNT(6,6). The results serve as a starting point for studying larger, more complex TM nanostructures anchored on the sidewall of boron- or nitrogen-doped CNTs.

An, Wei; Turner, C. H.

2009-04-30

180

Boron  

MedlinePLUS

... who do not get much magnesium in their diet. Among younger women, the effect appears to be greater in women ... mg of boron per 2000 kcal per day. Diets considered to be low in boron provide ... pregnant or breast-feeding women over 19 years of age. For adolescents 14 ...

181

Magnetic behavior and clustering effects in Mn-doped boron nitride sheets.  

PubMed

Ab initio calculations are performed in the framework of density functional theory on Mn-doped boron nitride sheets, which are candidates for two-dimensional diluted magnetic semiconductors (DMSs). Each type of substitution reveals a qualitatively different magnetic behavior encompassing ferromagnetic, anti-ferromagnetic and spin glass ordering. The ability of formation of these defects is also discussed. We analyze the dependence of the exchange couplings on the distance between impurities and the typical range and distribution are extracted. Multiple-impurity configurations are considered and the results are mapped on an Ising-type Hamiltonian with higher order exchange interactions, revealing deviations from the standard two-spin models. The percolation of interacting magnetic moments is discussed and the critical concentration is determined for the underlying transition from a ferromagnetic to a super-paramagnetic state. We conclude our study by providing the optimal conditions for doping in order to obtain a ferromagnetic DMS. PMID:22785224

Mitran, T L; Nicolaev, Adela; Nemnes, G A; Ion, L; Antohe, S

2012-07-12

182

Structure formation patterns in carbamide synthesis of nanocrystalline graphite-like boron nitride  

Microsoft Academic Search

We have used chemical analysis, x-ray diffractometry, transmission and scanning electron microscopy, and also measurement\\u000a of the specific surface area to study the characteristic patterns of nitriding and structure formation in graphite-like BN\\u000a powders synthesized by the carbamide method under various conditions. We have studied the effect on the synthesis process\\u000a from the ratio of boric acid to carbamide in

A. V. Kurdyumov; T. S. Bartnitskaya; V. I. Lyashenko; V. F. Britun; T. R. Balan; S. N. Gromyko; A. I. Danilenko; V. B. Zelyavskii

2005-01-01

183

Half-Metallicity in Undoped and Boron Doped Graphene Nanoribbons in the Presence of Semilocal Exchange-Correlation Interactions  

Microsoft Academic Search

We perform density functional calculations on one-dimensional zigzag edge graphene nano-ribbons (ZGNRs) of different widths, with and without edge doping including semi-local exchange-correlations. Our study reveals that, although the ground state of edge passivated (with hydrogen) ZGNRs prefers to be anti-ferromagnetic, the doping of both the edges with Boron atoms stabilizes the system in a ferromagnetic ground state. Both the

Sudipta Dutta; Swapan K. Pati

2008-01-01

184

Gel-hydrothermal synthesis of carbon and boron co-doped TiO 2 and evaluating its photocatalytic activity  

Microsoft Academic Search

Carbon and boron co-doped TiO2 photocatalysts were prepared firstly by the gel-hydrothermal method, that is, synthesized through sol–gel process followed by hydrothermal in the glucose solution. The prepared photocatalysts were characterized by XRD, Raman spectra, TEM, N2 physical adsorption, XPS, and UV–vis absorption spectra. It was found that the co-doped TiO2 has a larger BET surface areas and a narrower

Yongmei Wu; Mingyang Xing; Jinlong Zhang

2011-01-01

185

Morphological and microstructural stability of boron-doped diamond thin film electrodes in an acidic chloride medium at high anodic current densities  

SciTech Connect

Boron-doped diamond thin films have been examined before and after high-current-density electrolysis to investigate the morphological and microstructural stability of this new electrode material. The diamond thin films were used to generate chlorine from a solution of 1.0 M HNO{sub 3} + 2.0 M NaCl at current densities of 0.05 and 0.5 A/cm{sup 2} for times up to 20 h. Comparative studies were made using common graphitic electrodes including highly oriented pyrolytic graphite, glassy carbon, and Grafoil{reg_sign}. The electrodes were characterized using four-point probe resistivity measurements, atomic force microscopy, scanning electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, and cyclic voltammetry. In all cases, no severe morphological or microstructural damage (i.e., corrosion) was observed on films exposed to the highest current density. There were surface compositional changes in the forms of oxygenation and non-diamond carbon impurity etching that produced an increase in the reaction overpotential. Specifically, the overpotential was supposed to result from a combination of decreased surface conductivity due to the formation of carbon-oxygen functional groups and loss of kinetically active redox sites due to the oxidative etching of nondiamond carbon impurities.

Chen, Q.; Granger, M.C.; Lister, T.E.; Swain, G.M. [Utah State Univ., Logan, UT (United States). Dept. of Chemistry and Biochemistry

1997-11-01

186

Raman studies of ultra-clean graphene on hexagonal boron nitride with controlled doping  

NASA Astrophysics Data System (ADS)

Graphene prepared by exfoliation on hexagonal boron nitride (h-BN) provides an ideal platform for studies of the intrinsic properties of Dirac electrons because of its unprecedented charge homogeneity. With this system, many of the fascinating phenomena hidden by charge inhomogeneity in conventional graphene samples have recently been revealed. Here we describe progress in examining both electron-phonon and electron-electron interactions by means of Raman scattering by the G- and the 2D-modes. In our studies, we were able to observe a symmetric energy shift in the Raman 2D peak at low doping levels when the Fermi level was tuned from the electron side to the hole side. This shift is understood as a change in the double-resonance condition induced by the renormalization of the electron and phonon band structures. At the same time, the 2D peak is broadened under electron or hole doping. Additionally, we observed very weak doping dependence of the G peak (both position and width) at Fermi energies less than half of the phonon energy and the subsequent usual removal of non-adiabatic Kohn anomaly with increased doping, which reflects again the extremely homogeneous charge distribution in our samples.

Li, Yilei; Meric, Inanc; Mak, Kin Fai; Malard, Leandro; Dean, Cory; Kim, Philip; Shepard, Kenneth; Heinz, Tony

2012-02-01

187

Boron-doped diamond electrode: synthesis, characterization, functionalization and analytical applications.  

PubMed

In recent years, conductive diamond electrodes for electrochemical applications have been a major focus of research and development. The impetus behind such endeavors could be attributed to their wide potential window, low background current, chemical inertness, and mechanical durability. Several analytes can be oxidized by conducting diamond compared to other carbon-based materials before the breakdown of water in aqueous electrolytes. This is important for detecting and/or identifying species in solution since oxygen and hydrogen evolution do not interfere with the analysis. Thus, conductive diamond electrodes take electrochemical detection into new areas and extend their usefulness to analytes which are not feasible with conventional electrode materials. Different types of diamond electrodes, polycrystalline, microcrystalline, nanocrystalline and ultrananocrystalline, have been synthesized and characterized. Of particular interest is the synthesis of boron-doped diamond (BDD) films by chemical vapor deposition on various substrates. In the tetrahedral diamond lattice, each carbon atom is covalently bonded to its neighbors forming an extremely robust crystalline structure. Some carbon atoms in the lattice are substituted with boron to provide electrical conductivity. Modification strategies of doped diamond electrodes with metallic nanoparticles and/or electropolymerized films are of importance to impart novel characteristics or to improve the performance of diamond electrodes. Biofunctionalization of diamond films is also feasible to foster several useful bioanalytical applications. A plethora of opportunities for nanoscale analytical devices based on conducting diamond is anticipated in the very near future. PMID:19768202

Luong, John H T; Male, Keith B; Glennon, Jeremy D

2009-08-07

188

Development of Highly Conductive Boron-Doped Microcrystalline Silicon Films for Application in Solar Cells  

NASA Astrophysics Data System (ADS)

We have examined the deposition of highly conductive boron-doped microcrystalline silicon (?c-Si:H) films for application in solar cells. Depositions were conducted in a very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) chamber. In the deposition processes, various substrate temperatures (TS) were applied. Highly conductive p-type microcrystalline silicon films were obtained at substrate temperature lower than 210°C. The factors that affect the conductivity of the films were investigated. Results suggest that the dark conductivity, which was determined by the Hall mobility and carrier concentration, is influenced by the structure. The properties of the films are strongly dependent on the substrate temperature. With TS increasing, the dark conductivity (?d) increases initially; reach the maximum values at certain TS and then decrease. Also, we applied the boron-doped ?c-Si:H as p-layers to the solar cells. An efficiency of about 8.5% for a solar cell with ?c-Si:H p-layer was obtained.

Lei, Qing-Song; Wu, Zhi-Meng; Xi, Jian-Ping; Geng, Xin-Hua; Zhao, Ying; Sun, Jian

189

Amperometric Determination of Sulfite by Gas Diffusion-Sequential Injection with Boron-Doped Diamond Electrode  

PubMed Central

A gas diffusion sequential injection system with amperometric detection using a boron-doped diamond electrode was developed for the determination of sulfite. A gas diffusion unit (GDU) was used to prevent interference from sample matrices for the electrochemical measurement. The sample was mixed with an acid solution to generate gaseous sulfur dioxide prior to its passage through the donor channel of the GDU. The sulfur dioxide diffused through the PTFE hydrophobic membrane into a carrier solution of 0.1M phosphate buffer (pH 8)/0.1% sodium dodecyl sulfate in the acceptor channel of the GDU and turned to sulfite. Then the sulfite was carried to the electrochemical flow cell and detected directly by amperometry using the boron-doped diamond electrode at 0.95 V (versus Ag/AgCl). Sodium dodecyl sulfate was added to the carrier solution to prevent electrode fouling. This method was applicable in the concentration range of 0.2-20 mg SO32?/L and a detection limit (S/N = 3) of 0.05 mg SO32?/L was achieved. This method was successfully applied to the determination of sulfite in wines and the analytical results agreed well with those obtained by iodimetric titration. The relative standard deviations for the analysis of sulfite in wines were in the range of 1.0-4.1 %. The sampling frequency was 65 h?1.

Chinvongamorn, Chakorn; Pinwattana, Kulwadee; Praphairaksit, Narong; Imato, Toshihiko; Chailapakul, Orawon

2008-01-01

190

Electrochemical behavior of triflusal, aspirin and their metabolites at glassy carbon and boron doped diamond electrodes.  

PubMed

The electrochemical behavior of triflusal (TRF) and aspirin (ASA), before and after hydrolysis in water and in alkaline medium using two different electrode surfaces, glassy carbon and boron doped diamond, was study by differential pulse voltammetry over a wide pH range. The hydrolysis products are 2-(hydroxyl)-4-(trifluoromethyl)-benzoic acid (HTB) for triflusal and salicylic acid (SA) for aspirin, which in vivo represent their main metabolites. The hydrolysis processes were also followed by spectrophotometry. The UV results showed complete hydrolysis after one hour for TRF and after two hours for ASA in alkaline solution. The glassy carbon electrode enables only indirect determination of TRF and ASA through the electrochemical detection of their hydrolysis products HTB and SA, respectively. The oxidation processes of HTB and SA are pH dependent and involve different numbers of electrons and protons. Moreover, the difference between the oxidation peak potential of SA and HTB was equal to 100 mV in the studied pH range from 1 to 8 due to the CF3 of the aromatic ring of HTB molecule. Due to its wider oxidation potential range, the boron doped diamond electrode was used to study the direct oxidation of TRF and ASA, as well as of their respective metabolites HTB and SA. PMID:20402644

Enache, Teodor Adrian; Fatibello-Filho, Orlando; Oliveira-Brett, Ana Maria

2010-08-01

191

Modal interferometric sensor based in a birefringent boron-doped microstructured fiber  

NASA Astrophysics Data System (ADS)

Microstructured optical fibers (MOFs) have been widely studied owing to their potential for obtaining novel transmission, nonlinear and sensing characteristics. Sensing applications of MOFs cover various types of devices for measurements of different physical and specific chemical compounds in gases and liquids employing evanescent field techniques. Such fibers can also be used as active and passive elements in fiber-optic polarimetric and interferometric sensors. We present an in-line fiber modal interferometer fabricated in boron-doped highly birefringent microstructured fiber. The boron-doped region located in the middle of the core decreases the effective index of the fundamental mode and facilitates coupling between the fundamental and the first order mode. The coupling regions have the form of fiber narrowings fabricated using CO2 laser and are distant by a few millimeters. The spectral intensity at the sensor output is modulated only by intermodal interference produced by a short piece of fiber between the two coupling points. Moreover, as the fiber is highly birefringence, each pair of polarization modes produces its own intermodal fringes, which results in the contrast modulation of the overall interference signal observed at the fiber output, and provides an additional degree of freedom to measure simultaneously a pair of measurands.

Statkiewicz-Barabach, G.; Carvalho, J. P.; Frazão, O.; Olszewski, J.; Mergo, P.; Santos, J. L.; Urbanczyk, W.

2011-05-01

192

Generation and annihilation of boron-oxygen related defects in boron-doped Czochralski-grown Si solar cells  

NASA Astrophysics Data System (ADS)

Defects that reduce the minority-carrier lifetime in silicon crystal are produced by minority-carrier injection (forward bias or light illumination) when the boron-doped Czochralski-grown silicon (Cz-Si) is used as a solar cell material. The number of induced defects is determined from changes in open-circuit voltage (VOC) of the cells. It increases with the carrier injection time, and then becomes saturated. The saturated value increases as the ambient temperature increases, during the carrier injection. These defects are observed to be vanished by thermal annealing at 200 °C for 20 min, indicating that they are in an unstable state and that some of them are annihilated even during the carrier injection. Therefore, the total number of induced defects to be determined by the difference between the generation and the annihilation rates. The activation energies for the generation process and annihilation process are evaluated to be 0.77 eV and 0.32 eV, respectively.

Vu, Tuong Khanh; Ohshita, Yoshio; Araki, Kenji; Yamaguchi, Masafumi

2002-04-01

193

Electronic properties of light-induced recombination centers in boron-doped Czochralski silicon  

NASA Astrophysics Data System (ADS)

In order to study the electronic properties of the recombination centers responsible for the light-induced carrier lifetime degradation commonly observed in high-purity boron-doped Czochralski (Cz) silicon, injection-level dependent carrier lifetime measurements are performed on a large number of boron-doped p-type Cz silicon wafers of various resistivities (1-31 ? cm) prior to and after light degradation. The measurement technique used is the contactless quasi-steady-state photoconductance method, allowing carrier lifetime measurements over a very broad injection range between 1012 and 1017 cm-3. To eliminate all recombination channels not related to the degradation effect, the difference of the inverse lifetimes measured after and before light degradation is evaluated. A detailed analysis of the injection level dependence of the carrier lifetime change using the Shockley-Read-Hall theory shows that the fundamental recombination center created during illumination has an energy level between Ev+0.35 and Ec-0.45 eV and an electron/hole capture time constant ratio between 0.1 and 0.2. This deep-level center is observed in all samples and is attributed to a new type of boron-oxygen complex. Besides this fundamental defect, in some samples an additional shallow-level recombination center at 0.15 eV below Ec or above Ev is found to be activated during light exposure. This second center dominates the light-degraded carrier lifetime only under high-injection conditions and is hence only of minor importance for low-injection operated devices.

Schmidt, Jan; Cuevas, Andrés

1999-09-01

194

Boron and nitrogen co-doped titania with enhanced visible-light photocatalytic activity for hydrogen evolution  

NASA Astrophysics Data System (ADS)

A visible-light boron and nitrogen co-doped titania (B-N-TiO 2) photocatalyst was prepared by sol-gel method with titanium tetra- n-butyl oxide, urea and boric acid as precursors. The photocatalyst was characterized by Fourier Transform Infrared (FT-IR), UV-vis diffusive reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), BET and electrochemistry method. Photocatalytic activity for hydrogen production over platinized B-N-TiO 2 under visible-light ( ? ? 420 nm) irradiation was investigated. In nitrogen doped titania (N-TiO 2) N sbnd Ti sbnd O bond is formed, which extends the absorption edge to the visible-light region. A part of doping boron enters into titania lattice and most of the boron exists at the surface of the catalyst. The crystallite size of B-N-TiO 2 decreases compared to N-TiO 2, while its photocurrent and the surface hydroxyl group increase. Furthermore, doping boron could act as shallow traps for photoinduced electrons to prolong the life of the electrons and holes. Therefore, the visible-light activity of B-N-iO 2 increases greatly compared with that of N-TiO 2.

Li, Yuexiang; Ma, Gangfeng; Peng, Shaoqin; Lu, Gongxuan; Li, Shuben

2008-08-01

195

Electrochemical treatment of simulated copper CMP wastewater using boron doped diamond thin film electrodes-a feasibility study  

Microsoft Academic Search

The overall goal of this research was to develop a single treatment process that will economically treat wastewater generated during chemical-mechanical planarization (CMP) processing of integrated circuits. Present treatment technologies require multiple steps, are expensive, and generate secondary waste streams requiring further treatment or disposal. This research investigated the feasibility of electrochemical treatment of CMP wastewater using boron doped diamond

Subramanian Tamilmani; Wayne H. Huang; Srini Raghavan; James Farrell

2004-01-01

196

Investigation of Boron and Nitrogen-doped CNTs by Dispersive Micro-Raman BackScattering Spectroscopy  

Microsoft Academic Search

Raman scattering studies reveal the remarkable structure and the unusual electronic and phonon properties of carbon nanotubes, CNTs. In this study, we directly produced boron-, B, and nitrogen-, N, doped CNTs by using the DC-arc discharge method which normally can be employed for producing CNTs. We performed a series of experiments with and without Fe element as the catalyst and

R. Malekfar; S. Hosseini; B. Fakhraei; M. Khanlary; H. Asadi; S. Babanejad

2007-01-01

197

Enhanced electrochemical response of boron-doped diamond electrodes brought on by a cathodic surface pre-treatment  

Microsoft Academic Search

The effect of surface pre-treatment on the electrochemical response of boron-doped diamond (BDD) electrodes is reported. Initially, several examples from published works illustrate the dramatic changes observed when a cathodic polarisation is applied before measurements instead of the classically adopted anodic treatment. In particular, electroanalytical determinations of pesticides in pure and contaminated waters could only be possible after holding the

Hugo B. Suffredini; Valber A. Pedrosa; Lúcia Codognoto; Sérgio A. S. Machado; Romeu C. Rocha-Filho; Luis A. Avaca

2004-01-01

198

Electrochemical oxidation of 3-methylpyridine at a boron-doped diamond electrode: application to electroorganic synthesis and wastewater treatment  

Microsoft Academic Search

The electrochemical oxidation of 3-methylpyridine (3-MP) at synthetic boron-doped diamond (BDD) thin film electrode has been studied in acid media by cyclic voltammetry and bulk electrolysis. The results have shown that in the potential region of water stability there can occur direct electron transfer reactions on BDD surface that result in electrode fouling due to the formation of a polymeric

J. Iniesta; P. A. Michaud; M. Panizza; Ch. Comninellis

2001-01-01

199

Standard electrochemical behavior of high-quality, boron-doped polycrystalline diamond thin-film electrodes  

PubMed

Standard electrochemical data for high-quality, boron-doped diamond thin-film electrodes are presented. Films from two different sources were compared (NRL and USU) and both were highly conductive, hydrogen-terminated, and polycrystalline. The films are acid washed and hydrogen plasma treated prior to use to remove nondiamond carbon impurity phases and to hydrogen terminate the surface. The boron-doping level of the NRL film was estimated to be in the mid 1019 B/cm3 range, and the boron-doping level of the USU films was approximately 5 x 10(20) B/cm(-3) based on boron nuclear reaction analysis. The electrochemical response was evaluated using Fe-(CN)6(3-/4-), Ru(NH3)6(3+/2+), IrCl6(2-/3-), methyl viologen, dopamine, ascorbic acid, Fe(3+/2+), and chlorpromazine. Comparisons are made between the apparent heterogeneous electron-transfer rate constants, k0(app), observed at these high-quality diamond films and the rate constants reported in the literature for freshly activated glassy carbon. Ru(NH3)6(3+/2+), IrCl6(2-/3-), methyl viologen, and chlorpromazine all involve electron transfer that is insensitive to the diamond surface microstructure and chemistry with k0(app) in the 10(-2)-10(-1) cm/s range. The rate constants are mainly influenced by the electronic properites of the films. Fe(CN)6(3-/4-) undergoes electron transfer that is extremely sensitive to the surface chemistry with k0(app) in the range of 10(-2)-10(-1) cm/s at the hydrogen-terminated surface. An oxygen surface termination severely inhibits the rate of electron transfer. Fe(3+/2+) undergoes slow electron transfer at the hydrogen-terminated surface with k0(app) near 10(-5) cm/s. The rate of electron transfer at sp2 carbon electrodes is known to be mediated by surface carbonyl functionalities; however, this inner-sphere, catalytic pathway is absent on diamond due to the hydrogen termination. Dopamine, like other catechol and catecholamines, undergoes sluggish electron transfer with k0(app) between 10(-4) and 10(-5) cm/s. Converting the surface to an oxygen termination has little effect on k0(app). The slow kinetics may be related to weak adsorption of these analytes on the diamond surface. Ascorbic acid oxidation is very sensitive to the surface termination with the most negative Ep(ox) observed at the hydrogen-terminated surface. An oxygen surface termination shifts Ep(ox) positive by some 250 mV or more. An interfacial energy diagram is proposed to explain the electron transfer whereby the midgap density of states results primarily from the boron doping level and the lattice hydrogen. The films were additionally characterized by scanning electron microscopy and micro-Raman imaging spectroscopy. The cyclic voltammetric and kinetic data presented can serve as a benchmark for research groups evaluating the electrochemical properties of semimetallic (i.e., conductive), hydrogen-terminated, polycrystalline diamond. PMID:10959965

Granger; Witek; Xu; Wang; Hupert; Hanks; Koppang; Butler; Lucazeau; Mermoux; Strojek; Swain

2000-08-15

200

Sulfur doping effects on the electronic and geometric structures of graphitic carbon nitride photocatalyst: insights from first principles.  

PubMed

We present here results of our first-principles studies of the sulfur doping effects on the electronic and geometric structures of graphitic carbon nitride (g-C(3)N(4)). Using the ab initio thermodynamics approach combined with some kinetic analysis, we reveal the favorable S-doping configurations. By analyzing the valence charge densities of the doped and undoped systems, we find that sulfur partially donates its p(x)- and p(y)- electrons to the system with some back donation to the S p(z)-states. To obtain an accurate description of the excited electronic states, we calculate the electronic structure of the systems using the GW method. The band gap width calculated for g-C(3)N(4) is found to be equal to 2.7 eV, which is in agreement with experiment. We find the S doping causes a significant narrowing of the gap. Furthermore, the electronic states just above the gap become occupied upon doping, making the material a conductor. Analysis of the projected local density of states provides an insight into the mechanism underlying such changes in the electronic structure of g-C(3)N(4) upon S doping. Based on our results, we propose a possible explanation for the S-doping effect on the photocatalytic properties of g-C(3)N(4) observed in experiments. PMID:23363533

Stolbov, Sergey; Zuluaga, Sebastian

2013-01-30

201

Atmospheric pressure chemical vapour deposition of boron doped titanium dioxide for photocatalytic water reduction and oxidation.  

PubMed

Boron-doped titanium dioxide (B-TiO2) films were deposited by atmospheric pressure chemical vapour deposition of titanium(iv) chloride, ethyl acetate and tri-isopropyl borate on steel and fluorine-doped-tin oxide substrates at 500, 550 and 600 °C, respectively. The films were characterised using powder X-ray diffraction (PXRD), which showed anatase phase TiO2 at lower deposition temperatures (500 and 550 °C) and rutile at higher deposition temperatures (600 °C). X-ray photoelectron spectroscopy (XPS) showed a dopant level of 0.9 at% B in an O-substitutional position. The ability of the films to reduce water was tested in a sacrificial system using 365 nm UV light with an irradiance of 2 mW cm(-2). Hydrogen production rates of B-TiO2 at 24 ?L cm(-2) h(-1) far exceeded undoped TiO2 at 2.6 ?L cm(-2) h(-1). The B-TiO2 samples were also shown to be active for water oxidation in a sacrificial solution. Photocurrent density tests also revealed that B-doped samples performed better, with an earlier onset of photocurrent. PMID:23999866

Carmichael, Penelope; Hazafy, David; Bhachu, Davinder S; Mills, Andrew; Darr, Jawwad A; Parkin, Ivan P

2013-09-02

202

Scanning tunneling microscopy simulations of nitrogen- and boron-doped graphene and single-walled carbon nanotubes.  

PubMed

We report on studies of electronic properties and scanning tunneling microscopy (STM) of the most common configurations of nitrogen- or boron-doped graphene and carbon nanotubes using density functional theory. Charge transfer, shift of the Fermi level, and localized electronic states are analyzed as a function of the doping configurations and concentrations. The theoretical STM images show common fingerprints for the same doping type for graphene, and metallic or semiconducting nanotubes. In particular, nitrogen is not imaged in contrast to boron. STM patterns are mainly shaped by local density of states of the carbon atoms close to the defect. STM images are not strongly dependent on the bias voltage when scanning the defect directly. However, the scanning of the defect-free side of the tube displays a perturbation compared to the pristine tube depending on the applied bias. PMID:20552993

Zheng, Bing; Hermet, Patrick; Henrard, Luc

2010-07-27

203

Growth of boron-doped ZnTe homoepitaxial layer by metalorganic vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

We have investigated boron (B) as a n-type dopant for ZnTe homoepitaxial layer by atmospheric pressure metalorganic vapor phase epitaxy using triethylboron (TEB). The introduction of TEB induces considerable change in the photoluminescence spectrum of the layer. Two distinctive luminescence peaks associated with excitons bound to neutral dononor and donor-acceptor pair (DAP) transition are emerged in the spectrum, implying that the incorporated B acts as donor impurity in ZnTe. From the temperature dependence of the PL intensity of DAP recombination, the value of donor level was estimated to be 18 meV. This value seems to be reasonable, comparing with the previous studies on Cl and Al doping of ZnTe.

Saito, Katsuhiko; Yamashita, Tetsuo; Tanaka, Tooru; Nishio, Mitsuhiro; Guo, Qixin; Ogawa, Hiroshi

2006-03-01

204

Fabrication of cone-shaped boron doped diamond and gold nanoelectrodes for AFM-SECM.  

PubMed

We demonstrate a reliable microfabrication process for a combined atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM) measurement tool. Integrated cone-shaped sensors with boron doped diamond (BDD) or gold (Au) electrodes were fabricated from commercially available AFM probes. The sensor formation process is based on mature semiconductor processing techniques, including focused ion beam (FIB) machining, and highly selective reactive ion etching (RIE). The fabrication approach preserves the geometry of the original AFM tips resulting in well reproducible nanoscaled sensors. The feasibility and functionality of the fully featured tips are demonstrated by cyclic voltammetry, showing good agreement between the measured and calculated currents of the cone-shaped AFM-SECM electrodes. PMID:21368355

Avdic, A; Lugstein, A; Wu, M; Gollas, B; Pobelov, I; Wandlowski, T; Leonhardt, K; Denuault, G; Bertagnolli, E

2011-03-03

205

Cell adhesion properties on chemically micropatterned boron-doped diamond surfaces.  

PubMed

The adhesion properties of living cells were investigated on a range of chemically modified boron-doped diamond (BDD) surfaces. We studied the influence of oxidized, H-, amine- (NH(2)-), methyl- (CH(3)-), trifluoromethyl- (CF(3)-) and vinyl- (CH(2)?CH-) terminated BDD surfaces on human osteosarcoma U2OS and mouse fibroblast L929 cells behavior. Cell-surface interactions were analyzed by fluorescence microscopy in terms of cell attachment, spreading and proliferation. U2OS cells poorly adhered on hydrophobic surfaces and their growth was blocked. In contrast, L929 cells were mainly influenced by the presence of perfluoroalkyl chains in regard to their morphology. The results were subsequently applied to selectively micropattern U2OS cells on dual hydrophobic/hydrophilic surfaces prepared by a UV/ozone lithographic approach. U2OS cells colonized preferentially hydrophilic (oxide-terminated) motifs, forming confluent arrays with distinguishable edges separating the alkyl regions. PMID:20715878

Marcon, Lionel; Spriet, Corentin; Coffinier, Yannick; Galopin, Elisabeth; Rosnoblet, Claire; Szunerits, Sabine; Héliot, Laurent; Angrand, Pierre-Olivier; Boukherroub, Rabah

2010-10-01

206

Photochemical immobilization of proteins and peptides on benzophenone-terminated boron-doped diamond surfaces.  

PubMed

The successful covalent linking of green fluorescence protein and streptavidin to patterned benzophenone-modified boron-doped diamond (BDD) electrodes is demonstrated. Photoreactive benzophenone moieties were covalently grafted to oxidized diamond surfaces via an esterification reaction. Patterned BDD surfaces were obtained using a UV/ozone lithographic approach either on hydrogen-terminated BDD or on poly(ethylene)-glycol-modified BDD surfaces. UV light (lambda = 365 nm) irradiation of the patterned BDD surfaces in the presence of green fluorescence protein (GFP) or streptavidin resulted in the covalent immobilization of the proteins. The presence of poly(ethylene) glycol chains reduces significantly the nonspecific adsorption of the proteins. The success of the photoimmobilization of streptavidin was evidenced through biomolecular interaction with avidin. The preservation of the biological activity was furthermore underlined by photoimmobilization of peptides directly onto benzophenone modified BDD using a photomask. PMID:19821607

Marcon, Lionel; Wang, Mei; Coffinier, Yannick; Le Normand, Francois; Melnyk, Oleg; Boukherroub, Rabah; Szunerits, Sabine

2010-01-19

207

Fabrication of cone-shaped boron doped diamond and gold nanoelectrodes for AFM-SECM  

NASA Astrophysics Data System (ADS)

We demonstrate a reliable microfabrication process for a combined atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM) measurement tool. Integrated cone-shaped sensors with boron doped diamond (BDD) or gold (Au) electrodes were fabricated from commercially available AFM probes. The sensor formation process is based on mature semiconductor processing techniques, including focused ion beam (FIB) machining, and highly selective reactive ion etching (RIE). The fabrication approach preserves the geometry of the original AFM tips resulting in well reproducible nanoscaled sensors. The feasibility and functionality of the fully featured tips are demonstrated by cyclic voltammetry, showing good agreement between the measured and calculated currents of the cone-shaped AFM-SECM electrodes.

Avdic, A.; Lugstein, A.; Wu, M.; Gollas, B.; Pobelov, I.; Wandlowski, T.; Leonhardt, K.; Denuault, G.; Bertagnolli, E.

2011-04-01

208

Simultaneous detection of iodine and iodide on boron doped diamond electrodes.  

PubMed

Individual and simultaneous electrochemical detection of iodide and iodine has been performed via cyclic voltammetry on boron doped diamond (BDD) electrodes in a 1M NaClO(4) (pH 8) solution, representative of typical environmental water conditions. It is feasible to compute accurate calibration curve for both compounds using cyclic voltammetry measurements by determining the peak current intensities as a function of the concentration. A lower detection limit of about 20 ?M was obtained for iodide and 10 ?M for iodine. Based on the comparison between the peak current intensities reported during the oxidation of KI, it is probable that iodide (I(-)) is first oxidized in a single step to yield iodine (I(2)). The latter is further oxidized to obtain IO(3)(-). This technique, however, did not allow for a reasonably accurate detection of iodate (IO(3)(-)) on a BDD electrode. PMID:23200355

Fierro, Stéphane; Comninellis, Christos; Einaga, Yasuaki

2012-10-23

209

In vivo assessment of cancerous tumors using boron doped diamond microelectrode  

NASA Astrophysics Data System (ADS)

The in vitro and in vivo electrochemical detection of the reduced form of glutathione (L-?-glutamyl-L-cysteinyl-glycine, GSH) using boron doped diamond (BDD) microelectrode for potential application in the assessment of cancerous tumors is presented. Accurate calibration curve for the determination of GSH could be obtained by the in vitro electrochemical measurements. Additionally, it was shown that it was possible to separate the detection of GSH from the oxidized form of glutathione (GSSG) using chronoamperometry measurements. In vivo GSH detection measurements have been performed in human cancer cells inoculated in immunodeficient mice. These measurements have shown that the difference of GSH level between cancerous and normal tissues can be detected. Moreover, GSH detection measurements carried out before and after X-ray irradiation have proved that it is possible to assess in vivo the decrease in GSH concentration in the tumor after a specific treatment.

Fierro, Stéphane; Yoshikawa, Momoko; Nagano, Osamu; Yoshimi, Kenji; Saya, Hideyuki; Einaga, Yasuaki

2012-11-01

210

Electron transfer kinetics on composite diamond (sp 3)–graphite (sp 2) electrodes  

Microsoft Academic Search

The concept of non-diamond sp2 impurity states as charge transfer mediators on boron-doped diamond (BDD) surface was suggested as an explanation for the electrochemical behavior of synthetic diamond based electrodes. In order to verify this concept, graphite particles (sp2) were deposited on diamond electrodes (sp3) by mechanical abrasion. The behavior of the so prepared diamond–graphite composite electrodes were compared with

I Duo; A Fujishima; Ch Comninellis

2003-01-01

211

Local bond length variations in boron-doped nanocrystalline diamond measured by spatially resolved electron energy-loss spectroscopy  

NASA Astrophysics Data System (ADS)

Variations in local bond length and coordination in boron-doped nanocrystalline diamond (NCD) films have been studied through changes in the fine structure of boron and carbon K-edges in electron energy-loss spectra, acquired in a scanning transmission electron microscope. The presence of high concentrations of B in pristine diamond regions and enrichment of B at defects in single NCD grains is demonstrated. Local bond length variations are evidenced through an energy shift of the carbon 1s --> ?* edge at B-rich defective regions within single diamond grains, indicating an expansion of the diamond bond length at sites with local high B content.

Lu, Ying-Gang; Turner, Stuart; Verbeeck, Johan; Janssens, Stoffel D.; Haenen, Ken; Van Tendeloo, Gustaaf

2013-07-01

212

Surface chemistry of boron-doped SiO{sub 2} CVD: Enhanced uptake of tetraethyl orthosilicate by hydroxyl groups bonded to boron  

SciTech Connect

Insight into how dopants can enhance deposition rates has been obtained by comparing reactivities of tetraethyl orthosilicate (TEOS, Si(OCH{sub 2}CH{sub 3}){sub 4}) with silanol and boranol groups on SiO{sub 2}. This comparison is relevant for boron-doped SiO{sub 2} film growth from TEOS and trimethyl borate (TMB, B(OCH{sub 3}){sub 3}) sources since boranols and silanols are expected to be present on surface during the (CVD). A silica substrate having coadsorbed deuterated silanols (SIOD) and boranols (BOD) was reacted with TEOS in a cold-wall reactor in the mTorr pressure regime at 1000K. Reactions were followed with Fourier transform infrared spectroscopy. Use of deuterated hydroxyls allowed consumption of hydroxyls by TEOS chemisorption to be distinguished from concurrent formation of SIOH and BOH that results from TEOS decomposition. It was found that TEOS reacts with BOD at twice the rate observed for SIOD demonstrating that hydroxyl groups bonded to boron increase the rate of TEOS chemisorption. Surface ethoxy groups produced by chemisorption of TEOS decompose at a slower rate in the presence of TMB decomposition products. Possible dependencies on reactor geometries and other deposition conditions may determine which of these two competing effects will control deposition rates. This may explain (in part) why the rate enhancement effect is not always observed in boron-doped SiO{sub 2} CVD processes.

Bartram, M.E.; Moffat, H.K.

1993-12-31

213

Surface morphology and electrical properties of boron-doped diamond films synthesized by microwave-assisted chemical vapor deposition using trimethylboron on diamond (100) substrate  

Microsoft Academic Search

Prime novelty: The smoothness of the synthesized boron-doped diamond was improved by the pre-treatment of a hydrogen plasma. Moreover, the Hall mobility also increased with this pre-treatment.Surface morphology and electrical properties, such as electrical conductivity, hole concentration and Hall mobility, were investigated for boron-doped diamond films, which were synthesized by microwave-assisted chemical vapor deposition (MPCVD) on a (100) diamond substrate.

T Tsubota; T Fukui; T Saito; K Kusakabe; S Morooka; H Maeda

2000-01-01

214

PURIFYING ROUTE TO NUCLEAR-GRADE GRAPHITE  

Microsoft Academic Search

A flowsheet for production of high-purity graphite is presented. Low-; boiling; impurities are removed by graphitization at 5000 to 5400 F. To free ; the graphite of the high-boiling impurities such as boron and vandium, Freon-12 ; gas is forced through the graphitizing-furnace bed. The freon decomposes to form ; free chlorine and fluorine which react with the boron and

Cronan

1959-01-01

215

Electronic structure and ferromagnetism of boron doped bulk and surface CdSe: By generalized gradient approximation and generalized gradient approximation plus modified Becke and Johnson calculations  

NASA Astrophysics Data System (ADS)

Using the full potential linearized augment plane wave method with the generalized gradient approximation (GGA) and GGA plus modified Becke and Johnson (GGA+mBJ) potential, the electronic structures and ferromagnetism for the boron doped bulk and surface CdSe are investigated. Calculations show that the substitutional boron for selenium in CdSe could induce spin polarized localized states in the gap and generate local magnetic moments 3.00 ?B with one dopant atom. Energy difference between the antiferromagnetic and ferromagnetic phase suggests that BSe favors the ferromagnetic ground state. Electronic structures indicate the magnetic moments mainly provided by the doped boron atoms, and carriers mediated double exchange mechanism plays crucial role in forming the ferromagnetism. Ferromagnetic boron doped CdSe (100) films could be realized by using the high energy boron ions injection to form the non-surface doped configurations. The cadmium vacancy would reduce the ferromagnetism and lead the boron doped CdSe to magnetic metallicity. Formation energy for the four high symmetry doped configurations indicates BSe could be realized by using Cd-rich condition.

Fan, S. W.; Ding, L. J.; Yao, K. L.

2013-09-01

216

Formation and Transport Properties of Defects in Boron-Doped Silicon Studied Through Tight Binding Bond Models.  

NASA Astrophysics Data System (ADS)

The formation and transport properties of point defects in boron-doped silicon have been studied at the atomic level. Robust continuum models of boron diffusion require a knowledge of equilibrium concentrations and diffusivities of self-interstitials, vacancies, boron-defect pairs, and small boron clusters that cannot easily be obtained experimentally. Such thermodynamic and transport properties can, however, be estimated through statistical mechanical and Transition State theories, provided energies and vibrational entropies of point defect formation and migration are known. These energies and entropies have been determined in this work using an empirical quantum mechanical model called Tight Binding (ETB) to describe Si-Si, Si-B, and B-B bonding. Classical models (via the Stillinger-Weber potential) are used to estimate entropies. Defects were identified using "scramble -relaxation" computer runs in which starting positions of atoms were randomly varied and then relaxed to yield stable defect structures. The ETB results for formation energies are generally consistent with LDA ab initio results, to within approximately 0.3eV. C_ {EQ}(I) values determined via the ETB model agree with Au, Pt, and Zn in-diffusion-derived estimates, and contrast with those obtained through modeling of OED and stacking-fault experiments. The negative-U behavior of vacancies and boron interstitials is reproduced by the ETB model, and the correct charge states (0 and -1 for V, and +1 for B_{S }I and B_{i} ) are obtained. Several new di-interstitial clusters, with and without boron, have been obtained which have formation energies 1-2eV/atom lower than isolated interstitials. Although the accuracy limits of the ETB and Stillinger-Weber models make it impossible to determine whether interstitials or vacancies dominate in the mediation of boron transport at equilibrium, it is concluded that, because the migration energy of B_{i} in a direct-interstitial mechanism is very low (0.15eV), boron should have a high effective diffusion coefficient in cases where boron interstitials are super-saturated (e.g., for OED and TED). The ETB model predicts that B _{n} (n from 1 to 4) substitutional clusters decrease in stability with increasing n, but that the inclusion of an interstitial (B_{n}I) makes larger clusters increasingly more stable. This may help explain how boron precipitates nucleate in highly-doped silicon.

Rasband, Paul Brent

217

Homoepitaxial Boron Doped Diamond Anvil as Heating Element in a Diamond Anvil Cell  

NASA Astrophysics Data System (ADS)

Recent advances in designer-diamond technology have allowed for the use of electrically and thermally conducting homoepitaxially-grown layers of boron-doped diamond (grown at 1200 C with a 2% mixture of CH4 in H, resulting in extremely high doping levels ˜ 10^20/cm^3) to be used as heating elements in a diamond anvil cell (DAC). These diamonds allow for precise control of the temperature inside of the diamond anvil itself, particularly when coupled with a cryostat. Furthermore, the unmatched thermally conducting nature of diamond ensures that no significant spatial gradient in temperature occurs across the culet area. Since a thermocouple can easily be attached anywhere on the diamond surface, we can also measure diamond temperatures directly. With two such heaters, one can raise sample temperatures uniformly, or with any desired gradient along the pressure axis while preserving optical access. In our initial experiments with these diamond anvils we report on the measurement of the thermal conductivity of copper-beryllium using a single diamond heater and two thermocouples. We augment these measurements with measurements of sample pressure via ruby fluorescence and electrical resistance of the sample and diamond heater.

Montgomery, Jeffrey; Samudrala, Gopi; Vohra, Yogesh

2012-02-01

218

TiO2 nanopowders doped with boron and nitrogen for photocatalytic applications  

NASA Astrophysics Data System (ADS)

TiO2-based systems have attracted an increasing interest for their potential use as photocatalysts under visible-light irradiation. In this context, the present work was dedicated to the tailored synthesis of TiO2 nanopowders doped with boron, nitrogen or both species for the photocatalytic degradation of organic dyes. In particular, the systems were synthesized by a sol gel route starting from titanium(IV) butoxide as a Ti source and thoroughly characterized by the combined use of N2 physisorption, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV Vis reflectance spectroscopy and temperature-programmed oxidation (TPO). Finally, the photocatalytic performances in the decomposition of the azo-dye methyl orange (MO) were investigated. The obtained results suggest that both dopants promote the photocatalytic activity with respect to pure TiO2 systems. Nevertheless, while our surface N-doping does not appreciably modify the titania structure and texture, B incorporation inhibits the TiO2 crystallite growth and induces an increase in the surface area. As regards the codoped systems, a remarkable reactivity improvement was observed only when B is present in excess with respect to N. A rational interpretation of the observed behaviour was attempted by calculations based on the density functional theory (DFT). We suggest that the presence of B in molar excess with respect to N generates reactive Ti(III) sites, which, in turn, might induce the formation of reactive superoxide species.

Gombac, V.; de Rogatis, L.; Gasparotto, A.; Vicario, G.; Montini, T.; Barreca, D.; Balducci, G.; Fornasiero, P.; Tondello, E.; Graziani, M.

2007-10-01

219

Enhanced photocatalytic performance of boron doped Bi?WO? nanosheets under simulated solar light irradiation.  

PubMed

Bi?WO6 doped with different amounts of boron atoms (0.1, 0.5, 1.0, 5.0 and 10% B) were synthesized using hydrothermal method and their photocatalytic activities to degrade rhodamine B (RhB) under simulated solar light was investigated. The successful incorporation of B atoms in Bi?WO? was proved by FT-IR, Raman spectra and XPS. Doping with B could affect the pore structure and volume. 0.5% B/Bi?WO? displayed more mesopores with higher total pore volume than pure Bi?W?; while the pores of 10% B/Bi?WO? mainly distributed in microporous range with much less total pore volume. As a result, 0.5% B/Bi?WO? displayed stronger adsorption capacity to RhB, favoring the photodegradation. In addition, the doped B atoms could act as electron traps and facilitate the separation of photogenerated electron-hole pairs due to its electron deficient and oxytropic characteristics. 0.5% B/Bi?WO? displayed the highest photocatalytic activity under simulated solar light with rate constant (kobs) 8.8 times of that using pure Bi?WO?. Its photoactivity was affected by solution pH and the optimum was achieved at pH 7. At this condition, around 100% of RhB (10(-5)mol/L) was degraded in 180 min. The photogenerated holes were the main active species responsible for the photodegradation of RhB by B/Bi?WO?. PMID:23618657

Fu, Yu; Chang, Chun; Chen, Peng; Chu, Xiaolong; Zhu, Lingyan

2013-03-27

220

Influence of boron doping and hydrogen passivation on recombination of photoexcited charge carriers in silicon nanocrystal/SiC multilayers  

NASA Astrophysics Data System (ADS)

The influence of boron (B)-doping and remote plasma hydrogen passivation on the photoexcited charge carrier recombination in silicon nanocrystal/SiC multilayers was investigated in detail. The samples were prepared by high temperature annealing of amorphous (intrinsic and B-doped) Si1-xCx/SiC superlattices. The photoluminescence (PL) intensity of samples with B-doped silicon rich carbide layers was found to be up to two orders of magnitude larger and spectrally red shifted in comparison with that of the other samples. Hydrogen passivation leads to an additional increase in PL intensities. The PL decay can be described well by a mono-exponential function with a characteristic decay time of a few microseconds. This behavior agrees well with the picture of localized PL centers (surface states) together with the passivation of non-radiative defects by boron. The samples with B-doped SiC layers exhibit an additional PL band in the green spectral region that is quenched by hydrogen passivation. Its origin is attributed to defects due to suppression of crystallization of amorphous SiC layers as a result of B-doping. Measurement of ultrafast transient transmission allowed us to study the initial (picosecond) carrier dynamics. It was found to be dependent of pump intensity and interpreted in terms of multiparticle electron-hole recombination.

Ko?ínek, M.; Schnabel, M.; Canino, M.; Kozák, M.; Trojánek, F.; Salava, J.; Löper, P.; Janz, S.; Summonte, C.; Malý, P.

2013-08-01

221

Influence of boron concentration on growth characteristic and electro-catalytic performance of boron-doped diamond electrodes prepared by direct current plasma chemical vapor deposition  

Microsoft Academic Search

A series of boron-doped diamond (BDD) electrodes were prepared by direct current plasma chemical vapor deposition (DC-PCVD) with different compositions of CH4\\/H2\\/B(OCH3)3 gas mixture. A maximum growth rate of 0.65mgcm?2h?1 was obtained with CH4\\/H2\\/B(OCH3)3 radio of 4\\/190\\/10 and this growth condition was also a turning point for discharge plasma stability which arose from the addition of B(OCH3)3 that changed electron

Yujie Feng; Jiangwei Lv; Junfeng Liu; Na Gao; Hongyan Peng; Yuqiang Chen

2011-01-01

222

Facile electrocatalytic redox of hemoglobin by flower-like gold nanoparticles on boron-doped diamond surface  

Microsoft Academic Search

The flower-like gold nanoparticles together with spherical and convex polyhedron gold nanoparticles were fabricated on boron-doped diamond (BDD) surface by one-step and simple electrochemical method through easily controlling the applied potential and the concentration of HAuCl4. The recorded X-ray diffraction (XRD) patterns confirmed that these three shapes of gold nanoparticles were dominated by different crystal facets. The cyclic voltammetric results

Mingfang Li; Guohua Zhao; Rong Geng; Huikang Hu

2008-01-01

223

Synthesis of Boron-Doped C60 Film Using Plasma-Assisted Thermal Evaporation Technique and its Electrochemical Characterizations  

Microsoft Academic Search

Boron doped C60 (B:C60) thin films were synthesized by a plasma-assisted thermal evaporation system. Scanning electron microscope (SEM), Raman spectroscopy, Fourier transform infra red (FTIR) and X-ray photo electron spectroscopy (XPS) were used to investigate the morphology and structural characteristics of the films, respectively. The electrochemical characterization of B:C60 films was then introduced as a coating layer for silicon film

Arenst Andreas Arie; Joong Kee Lee

2012-01-01

224

Sonoelectrochemistry at highly boron-doped diamond electrodes: silver oxide deposition and electrocatalysis in the presence of ultrasound  

Microsoft Academic Search

The use of boron-doped diamond has a considerable impact in electrochemistry owing to the wide potential range accessible,\\u000a low background currents, extreme hardness, and the ease of chemical modification of diamond surfaces. It is shown here that,\\u000a although the electrodeposition of silver metal is known to yield very poorly adhering films with a poor electrical contact,\\u000a a silver oxysalt deposit

Andrew J. Saterlay; Shelley J. Wilkins; Christiaan H. Goeting; John S. Foord; Richard G. Compton; Frank Marken

2000-01-01

225

Fluorine and boron co-doped diamond-like carbon films deposited by pulsed glow discharge plasma immersion ion processing  

Microsoft Academic Search

Fluorine (F) and boron (B) co-doped diamond-like carbon (FB-DLC) films were prepared on different substrates by the plasma immersion ion processing (PIIP) technique. A pulse glow discharge plasma was used for the PIIP deposition and was produced at a pressure of 1.33 Pa from acetylene (C2H2), diborane (B2H6), and hexafluoroethane (C2F6) gas. Films of FB-DLC were deposited with different chemical

Xiao-Ming He; M. Hakovirta; A. M. Peters; B. Taylor; M. Nastasi

2002-01-01

226

Periodically arranged benzene-linker molecules on boron-doped single-crystalline diamond films for DNA sensing  

Microsoft Academic Search

Electrochemical surface modification via reduction of 4-nitrobenzene diazonium tetrafluoroborate in acetonitrile solution has been performed on highly boron-doped homoepitaxial single-crystalline CVD diamond films to build up surface functionalization for DNA hybridization. Due to significantly improved voltammetric resolution and regularly oriented arrangements, covalently bonded 4-nitrophenyl groups on single-crystalline diamond are characterized to have two successive reversible one-electron transfer reactions interacting with

Dongchan Shin; Norio Tokuda; Bohuslav Rezek; Christoph E. Nebel

2006-01-01

227

Electrochemical degradation of a real textile effluent using boron-doped diamond or ?-PbO 2 as anode  

Microsoft Academic Search

Constant current electrolyses are carried out in a filter-press reactor using a boron-doped diamond (Nb\\/BDD) or a Ti–Pt\\/?-PbO2 anode, varying current density (j) and temperature. The degradation of the real textile effluent is followed by its decolorization and chemical oxygen demand (COD) abatement. The effect of adding NaCl (1.5gL?1) on the degradation of the effluent is also investigated. The Nb\\/BDD

José M. Aquino; Gabriel F. Pereira; Romeu C. Rocha-Filho; Nerilso Bocchi; Sonia R. Biaggio

2011-01-01

228

Electrochemical incineration of cresols: A comparative study between PbO 2 and boron-doped diamond anodes  

Microsoft Academic Search

The electrooxidation of aqueous solutions containing 5mM of o-, m- and p-cresol at pH 4.0 has been investigated using a flow filter-press reactor with a boron-doped diamond (BDD) under galvanostatic electrolysis. All cresols are degraded at similar rate up to attaining overall mineralization. Comparable treatment of the m-cresol effluent on PbO2 leads to partial electrochemical incineration. However, this pollutant is

Cristina Flox; Conchita Arias; Enric Brillas; André Savall; Karine Groenen-Serrano

2009-01-01

229

Comparative mineralization of textile dye indigo by photo-Fenton process and anodic oxidation using boron-doped diamond anode  

Microsoft Academic Search

In the present study, we applied two advanced oxidation processes (AOPs); photo-Fenton and anodic oxidation (using a boron doped diamond (BDD) anode) processes, to oxidative degradation and mineralization of the textile dye Indigo in sodium dithionite aqueous media. The effect of key parameters, such as H2O2 dosage for photo-Fenton process and initial pH for anodic oxidation, on the degradation and

Samiha Hammami; Mehmet A. Oturan; Nihal Oturan; Nizar Bellakhal; Mohamed Dachraoui

2012-01-01

230

ELECTROCHEMICAL ADVANCED OXIDATION TREATMENTS OF ACIDIC AQUEOUS SOLUTIONS CONTAINING THE AMINOACID ?-METHYLPHENYLGLYCINE USING A BORON-DOPED DIAMOND ANODE  

Microsoft Academic Search

The degradation of a solution containing 500 mg L-1 of the aminoacid ?-methylphenylglycine, 10 mg L-1 Fe2+ and 0.05 M Na2O4 at pH 3.0 has been studied by means of electrochemical advanced oxidation processes like electro-Fenton (EF) and solar photoelectro-Fenton (SPEF) using an undivided electrolytic cell with a boron-doped diamond (BDD) anode and an O2-diffusion cathode. Under these conditions, very

Anna Serra; Xavier Domènech; José Peral; Conchita Arias; Enric Brillas

231

Fabricating random arrays of boron doped diamond nano-disc electrodes: Towards achieving maximum Faradaic current with minimum capacitive charging  

Microsoft Academic Search

We report the first construction of a random array of boron doped diamond (BDD) nano-disc electrodes (RAN BDD), formed by a simple three-step method. First molybdenum(IV) dioxide nanoparticles are electrodeposited onto a BDD substrate. Second the electrode surface is covered in an insulating polymer film by the electropolymerization of a 4-nitrophenyldiazonium salt. Third the molybdenum dioxide nanoparticles are dissolved from

Lei Xiao; Ian Streeter; Gregory G. Wildgoose; Richard G. Compton

2008-01-01

232

Electrochemical analysis of d-penicillamine using a boron-doped diamond thin film electrode applied to flow injection system  

Microsoft Academic Search

The electroanalysis of d-penicillamine in 0.1 phosphate buffer (pH 7) was studied at a boron-doped diamond thin film (BDD) electrode using cyclic voltammetry as a function of concentration of analyte and pH of analyte solution. Comparison experiments were performing using a glassy carbon (GC) electrode. The BDD electrode exhibited a well-resolved and irreversible oxidation voltammogram, but the GC electrode provided

Nattakarn Wangfuengkanagul; Orawon Chailapakul

2002-01-01

233

Electrochemical incineration of chloromethylphenoxy herbicides in acid medium by anodic oxidation with boron-doped diamond electrode  

Microsoft Academic Search

The electrochemical degradation of saturated solutions of herbicides 4-chloro-2-methylphenoxyacetic acid, 2-(4-chlorophenoxy)-2-methylpropionic acid and 2-(4-chloro-2-methylphenoxy)propionic acid in 1M HClO4 on a boron-doped diamond (BDD) thin film anode has been studied by chronoamperometry, cyclic voltammetry and bulk electrolysis. At low anodic potentials polymeric products are formed causing the fouling and deactivation of BDD. This is reactivated at high potentials when water decomposes

Birame Boye; Enric Brillas; Beatrice Marselli; Pierre-Alain Michaud; Christos Comninellis; Giuseppe Farnia; Giancarlo Sandonà

2006-01-01

234

Mineralization of the recalcitrant oxalic and oxamic acids by electrochemical advanced oxidation processes using a boron-doped diamond anode  

Microsoft Academic Search

Oxalic and oxamic acids are the ultimate and more persistent by-products of the degradation of N-aromatics by electrochemical advanced oxidation processes (EAOPs). In this paper, the kinetics and oxidative paths of these acids have been studied for several EAOPs using a boron-doped diamond (BDD) anode and a stainless steel or an air-diffusion cathode. Anodic oxidation (AO-BDD) in the presence of

Sergi Garcia-Segura; Enric Brillas

2011-01-01

235

Electrochemistry of vanadium-doped tetragonal and monoclinic ZrO 2 attached to graphite\\/polyester composite electrodes  

Microsoft Academic Search

.   The electrochemistry of monoclinic and tetragonal vanadium-doped zirconias (VZrO2), prepared from gel precursors with vanadium loadings ranging from 0.5 to 15 mol%, has been studied using abrasive-conditioned\\u000a graphite\\/polyester composite electrodes immersed in aqueous HCl and HClO4 solutions. Isolated vanadium centers form a solid solution in the zirconia lattice with a solubility limit close to 5 mol%.\\u000a Above 5 mol%, finely dispersed V2O5

Antonio Doménech; Javier Alarcón

2002-01-01

236

Improvements in the Formation of Boron-Doped Diamond Coatings on Platinum Wires Using the Novel Nucleation Process (NNP)  

PubMed Central

In order to increase the initial nucleation density for the growth of boron-doped diamond on platinum wires, we employed the novel nucleation process (NNP) originally developed by Rotter et al. and discussed by others [1–3]. This pretreatment method involves (i) the initial formation of a thin carbon layer over the substrate followed by (ii) ultrasonic seeding of this “soft” carbon layer with nanoscale particles of diamond. This two-step pretreatment is followed by the deposition of boron-doped diamond by microwave plasma-assisted CVD. Both the diamond seed particles and sites on the carbon layer itself function as the initial nucleation zones for diamond growth from an H2-rich source gas mixture. We report herein on the characterization of the pre-growth carbon layer formed on Pt as well as boron-doped films grown for 2, 4 and 6 h post NNP pretreatment. Results from scanning electron microscopy, Raman spectroscopy and electrochemical studies are reported. The NNP method increases the initial nucleation density on Pt and leads to the formation of a continuous diamond film in a shorter deposition time than is typical for wires pretreated by conventional ultrasonic seeding. The results indicate that the pregrowth layer itself consists of nanoscopic domains of diamond and functions well to enhance the initial nucleation of diamond without any diamond powder seeding.

Fhaner, Mathew; Zhao, Hong; Bian, Xiaochun; Galligan, James J.; Swain, Greg M.

2010-01-01

237

Electroanalytical investigation and determination of pefloxacin in pharmaceuticals and serum at boron-doped diamond and glassy carbon electrodes.  

PubMed

The anodic behavior and determination of pefloxacin on boron-doped diamond and glassy carbon electrodes were investigated using cyclic, linear sweep, differential pulse and square wave voltammetric techniques. In cyclic voltammetry, pefloxacin shows one main irreversible oxidation peak and additional one irreversible ill-defined wave depending on pH values for both electrodes. The results indicate that the process of pefloxacin is irreversible and diffusion controlled on boron-doped diamond electrode and irreversible but adsorption controlled on glassy carbon electrode. The peak current is found to be linear over the range of concentration 2x10(-6) to 2x10(-4)M in 0.5M H(2)SO(4) at about +1.20V (versus Ag/AgCl) for differential pulse and square wave voltammetric technique using boron-doped diamond electrode. The repeatability, reproducibility, precision and accuracy of the methods in all media were investigated. Selectivity, precision and accuracy of the developed methods were also checked by recovery studies. The procedures were successfully applied to the determination of the drug in pharmaceutical dosage forms and humans serum samples with good recovery results. No electroactive interferences from the excipients and endogenous substances were found in the pharmaceutical dosage forms and biological samples, respectively. PMID:18371769

Uslu, Bengi; Topal, Burcu Dogan; Ozkan, Sibel A

2007-08-30

238

Tunable doping and band gap of graphene on functionalized hexagonal boron nitride with hydrogen and fluorine.  

PubMed

First-principles calculations have been used to investigate the structural and electronic properties of graphene supported on functionalized hexagonal boron nitride (h-BN) with hydrogen and fluorine atoms. Our results show that the hydrogenation and fluorination of the h-BN substrate modify the electronic properties of graphene. Interactions of graphene with fully hydrogenated or fully fluorinated h-BN and half-hydrogenated and half-fluorinated h-BN with H at N sites and F at the B sites can lead to n- or p-type doping of graphene. The different doping effect may be attributed to the significant charge transfer from graphene to the substrate. Interestingly, when graphene is supported on the functionalized h-BN with H at B sites and F at N sites (G/HBNF), a finite band gap of 79 meV in graphene is opened due to the equivalence breaking of two sublattices of graphene, and can be effectively modulated by changing the interlayer spacing, increasing the number of functionalized BN layers, and applying an external electric field. More importantly, the modification of the band gap in G/HBNF with a functionalized BN bilayer by the electric field is more pronounced than that of the single-layer h-BN, which is increased to 408 meV with 0.8 V Å(-1). Thus, graphene on chemically modified h-BN with a tunable and sizeable band gap may provide a novel way for fabricating high-performance graphene-based nanodevices. PMID:23450178

Tang, Shaobin; Yu, Jianping; Liu, Liangxian

2013-04-14

239

Determination of trace impurities in boron nitride by graphite furnace atomic absorption spectrometry and electrothermal vaporization inductively coupled plasma optical emission spectrometry using solid sampling  

NASA Astrophysics Data System (ADS)

Two digestion-free methods for trace analysis of boron nitride based on graphite furnace atomic absorption spectrometry (GFAAS) and electrothermal vaporization inductively coupled plasma spectrometry optical emission (ETV-ICP-OES) using direct solid sampling have been developed and applied to the determination of Al, Ca, Cr, Cu, Fe, Mg, Mn, Si, Ti and Zr in four boron nitride materials in concentration intervals of 1 23, 54 735, 0.05 21, 0.005 1.3, 1.6 112, 4.5 20, 0.03 1.8, 6 46, 38 170 and 0.4 2.3 ?g g- 1, respectively. At optimized experimental conditions, with both methods, effective in-situ analyte/matrix separation was achieved and calibration could be performed using calibration curves measured with aqueous standard solutions. In solid sampling GFAAS, before sampling, the platform was covered with graphite powder and, for determination of Si, also the Pd/Mg(NO3)2 modifier was used. In the determination of all analyte elements by solid sampling ETV-ICP-OES, Freon R12 was added to argon carrier gas. For solid sampling GFAAS and ETV-ICP-OES, the achievable limits of detection were within 5 (Cu) 130 (Si) ng g- 1 and 8 (Cu) 200 (Si) ng g- 1, respectively. The results obtained by these two methods for four boron nitride materials of different purity grades are compared each with the other and with those obtained in analysis of digests by ICP-OES. The performance of the two solid sampling methods is compared and discussed.

Barth, P.; Hassler, J.; Kudrik, I.; Krivan, V.

2007-09-01

240

Growth of n-Si layers by molecular-beam epitaxy on the substrates heavily doped with boron  

SciTech Connect

Epitaxial n-Si layers doped with phosphorus or erbium have been grown by sublimation molecularbeam epitaxy at 500{sup o}C on heavily boron-doped p{sup +}-type substrates with resistivity {rho} = 0.005 {omega} cm. Distribution profiles of the B, Er, and O impurity concentrations in the samples were determined by secondary-ion mass spectrometry. A thermal annealing of the substrate in vacuum at 1300{sup o}C for 10 min and growth at a very low substrate temperature made it possible to obtain an extremely abrupt profile for doping impurities at the layer-substrate interface. This method for growth of n-p{sup +} junctions considerably improves their electrical and luminescent characteristics.

Shengurov, V. G.; Chalkov, V. Yu. [Lobachevsky State University, Research Physicotechnical Institute (Russian Federation)], E-mail: chalkov@nifti.unn.ru; Shengurov, D. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Denisov, S. A. [Lobachevsky State University, Research Physicotechnical Institute (Russian Federation)

2009-02-15

241

Oxidative destruction of perfluorooctane sulfonate using boron-doped diamond film electrodes.  

PubMed

This research investigated the oxidative destruction of perfluorooctane sulfonate at boron-doped diamond film electrodes. Experiments measuring oxidation rates of PFOS were performed over a range in current densities and temperatures using a rotating disk electrode (RDE) reactor and a parallel plate flow-through reactor. The oxidation of PFOS yielded sulfate, fluoride, carbon dioxide, and trace levels of trifluoroacetic acid. Reaction rates in the RDE reactor were zeroth order in PFOS concentration. Reaction rates in the flow-through reactor were mass-transfer-limited and were pseudo-first-order in PFOS concentration, with a half-life of 5.3 min at a current density of 20 mA/cm2. Eyring analysis of the zeroth order rate constants at a fixed electrode potential yielded an apparent activation energy of 4.2 kJ/mol for PFOS oxidation. Density functional theory (DFT) simulations were used to calculate activation barriers for different possible reaction mechanisms, including oxidation by hydroxyl radicals at different sites on the PFOS molecule, and direct electron transfer. A comparison of the experimentally measured apparent activation energy with those calculated using DFT indicated that the most likely rate-limiting step for PFOS oxidation was direct electron transfer. PMID:18767674

Carter, Kimberly E; Farrell, James

2008-08-15

242

Development of electrolyte-free ozone sensors using boron-doped diamond electrodes.  

PubMed

The electrochemical detection of dissolved ozone in water was examined using boron-doped diamond (BDD) electrodes. A well-defined reduction peak was observed at ~380 mV for H-terminated BDD, whereas it was observed at ~200 mV in the case of O-terminated BDD for an ozone solution in a 0.1 M phosphate buffer solution at pH 7. The peak potential for ozone reduction was selective with respect to oxygen reduction at both H- and O-terminated BDD electrodes, whereas it occurred at approximately the same potential as oxygen reduction at other types of solid electrodes, including glassy-carbon, platinum, and gold electrodes. Interference from chlorine was not observed in lower concentration than 300 ?M ClO(-). Furthermore, in order to apply the detection technique to electrolyte-free media, BDD microelectrodes were also used. A linear calibration curve for dissolved ozone in water could be achieved between concentrations of 0.49 and 740 ?M, with an estimated detection limit (S/N = 3) of 0.185 ?M (S/N = 3). Excellent stability was demonstrated for repetitions of these calibration curves performed in 3 consecutive days. PMID:23544430

Ishii, Yuya; Ivandini, Tribidasari A; Murata, Kazutaka; Einaga, Yasuaki

2013-04-16

243

Comparison of electrocatalytic characterization of boron-doped diamond and SnO2 electrodes  

NASA Astrophysics Data System (ADS)

Boron-doped diamond (BDD) and SnO2 electrodes were prepared by direct current plasma chemical vapor deposition (DC-PCVD) and sol–gel method, respectively. Electrochemical characterization of the two electrodes were investigated by phenol electrochemical degradation, accelerated service life test, cyclic voltammetry (CV) in phenol solution, polarization curves in H2SO4. The surface morphology and crystal structure of two electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The results showed a considerable difference between the two electrodes in their electrocatalytic activity, electrochemical stability and surface properties. Phenol was readily mineralized to CO2 at BDD electrode, favoring electrochemical combustion, but its degradation was much slower at SnO2 electrode. The service life of BDD electrode was 10 times longer than that of SnO2. Higher electrocatalytic activity and electrochemical stability of BDD electrode arise from its high oxygen evolution potential and the physically absorbed hydroxyl radicals (OH) on electrode surface.

Lv, Jiangwei; Feng, Yujie; Liu, Junfeng; Qu, Youpeng; Cui, Fuyi

2013-10-01

244

Bioelectrochemical degradation of urea at platinized boron doped diamond electrodes for bioregenerative systems  

NASA Astrophysics Data System (ADS)

The recovery of potable water from space mission wastewater is critical for the life support and environmental health of crew members in long-term missions. NASA estimates reveal that at manned space missions 1.91 kg/person day of urine is produced, with urea and various salts as its main components. In this research we explore the utilization of urease (EC 3.5.1.5, 15,000 U/g) along with a platinized boron doped diamond electrode (Pt-BDD) to degrade urea. Urea is directly degraded to nitrogen by the in situ utilization of the reaction products as a strategy to increase the amount of clean water in future space expeditions. The biochemical reaction of urease produces ammonia and carbon dioxide from urea. Thereafter, ammonia is electrooxidized at the interface of the Pt-BDD producing molecular nitrogen. The herein presented system has been proven to have 20% urea conversion efficiency. This research has potential applications for future long-term space missions since the reaction byproducts could be used for a biomass subsystem (in situ resource recovery), while generating electricity from the same process.

Nicolau, Eduardo; González-González, Ileana; Flynn, Michael; Griebenow, Kai; Cabrera, Carlos R.

2009-10-01

245

Electrical properties of boron doped p-SiGeC grown on n--Si substrate  

NASA Astrophysics Data System (ADS)

The electrical properties of very thin (200 nm) boron doped (1018 cm-3) Si0.90 -yGe0.10Cy layers grown on n--Si substrates by low pressure chemical vapor deposition have been investigated as a function of carbon content (y=0.2 1.5data measured from the p-Si0.90 -yGe0.10Cy layers show that the carrier concentrations remain constant below 100 K for all samples, then the hole carriers gradually increase with temperature, and finally an unexpected changing sign of Hall coefficient occurs at about 375 K. In order to explain the observed Hall data, it requires a three conducting-layer model, which consists of a p-SiGeC layer, an n-Si substrate, and possibly a degenerate p-type region at the SiGeC/Si interface. Apparently, both the Si substrate and the degenerate interfacial layer affected significantly the Hall measurements of the SiGeC layer. The electrical properties extracted through the three-conducting layer model for the p-Si0.90-yGe0.10Cy layers alone are as follows. At room temperature, the carrier concentrations and mobilities are 6.8 x 1017 cm-3 and 490 cm2/V-s for y = 0.2 cm2/V-s and 350 cm2/V-s for y = 1.5

Ahoujja, M.; Yeo, Y. K.; Hengehold, R. L.; Pomrenke, G. S.

1999-10-01

246

Effect of substrate temperature on the growth and properties of boron-doped microcrystalline silicon films  

NASA Astrophysics Data System (ADS)

Highly conductive boron-doped hydrogenated microcrystalline silicon (?c-Si:H) films are prepared by very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at the substrate temperatures (TS) ranging from 90°C to 270°C. The effects of TS on the growth and properties of the films are investigated. Results indicate that the growth rate, the electrical (dark conductivity, carrier concentration and Hall mobility) and structural (crystallinity and grain size) properties are all strongly dependent on TS. As TS increases, it is observed that 1) the growth rate initially increases and then arrives at a maximum value of 13.3 nm/min at TS=210°C, 2) the crystalline volume fraction (Xc) and the grain size increase initially, then reach their maximum values at TS=140°C and finally decrease, 3) the dark conductivity (?d), carrier concentration and Hall mobility have a similar dependence on TS and arrive at their maximum values at TS=190°C. In addition, it is also observed that at a lower substrate temperature TS, a higher dopant concentration is required in order to obtain a maximum ?d.

Lei, Qing-Song; Wu, Zhi-Meng; Geng, Xin-Hua; Zhao, Ying; Sun, Jian; Xi, Jian-Ping

2006-01-01

247

Multichannel Boron Doped Nanocrystalline Diamond Ultramicroelectrode Arrays: Design, Fabrication and Characterization  

PubMed Central

We report on the fabrication and characterization of an 8 × 8 multichannel Boron Doped Diamond (BDD) ultramicro-electrode array (UMEA). The device combines both the assets of microelectrodes, resulting from conditions in mass transport from the bulk solution toward the electrode, and of BDD's remarkable intrinsic electrochemical properties. The UMEAs were fabricated using an original approach relying on the selective growth of diamond over pre-processed 4 inches silicon substrates. The prepared UMEAs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrated that the electrodes have exhibited a very fast electrode transfer rate (k0) up to 0.05 cm·s?1 (in a fast redox couple) and on average, a steady state limiting current (in a 0.5 M potassium chloride aqueous solution containing 1 mM Fe(CN)64? ion at 100 mV·s?1) of 1.8 nA. The UMEAs are targeted for electrophysiological as well as analytical applications.

Kiran, Raphael; Rousseau, Lionel; Lissorgues, Gaelle; Scorsone, Emmanuel; Bongrain, Alexandre; Yvert, Blaise; Picaud, Serge; Mailley, Pascal; Bergonzo, Philippe

2012-01-01

248

Electrochemical incineration of sulfanilic acid at a boron-doped diamond anode.  

PubMed

The anodic oxidation of sulfanilic acid solutions has been studied in acidic medium using a divided cell with a boron-doped diamond (BDD) anode and a stainless steel cathode. Overall mineralization was achieved under all experimental conditions tested due to the efficient destruction of sulfanilic acid and all its by-products with hydroxyl radicals generated at the BDD anode from water oxidation. The alternative use of an undivided cell with the same electrodes gave rise to the coating of the cathode with polymeric compounds, thus preventing the complete electrochemical incineration of sulfanilic acid. The solutions treated in the anodic compartment of the divided cell were degraded at similar rate under pH regulation within the pH interval 2.0-6.0. The mineralization current efficiency was enhanced when the applied current decreased and the initial substrate concentration increased. The decay of sulfanilic acid was followed by reversed-phase HPLC, showing a pseudo first-order kinetics. Hydroquinone and p-benzoquinone were identified as aromatic intermediates by gas chromatography-mass spectrometry and/or reversed-phase HPLC. Maleic, acetic, formic, oxalic and oxamic acids were detected as generated carboxylic acids by ion-exclusion HPLC. Ionic chromatographic analysis of electrolyzed solutions revealed that the N content of sulfanilic acid was mainly released as NH(4)(+) ion and in much smaller proportion as NO(3)(-) ion. PMID:22365277

El-Ghenymy, Abdellatif; Arias, Conchita; Cabot, Pere Lluís; Centellas, Francesc; Garrido, José Antonio; Rodríguez, Rosa María; Brillas, Enric

2012-02-25

249

Electrochemical oxidation of N-nitrosodimethylamine with boron-doped diamond film electrodes.  

PubMed

This research investigated NDMA oxidation by boron-doped diamond (BDD) film electrodes. Oxidation rates were measured as a function of electrode potential, current density, and temperature using rotating disk and flow-through reactors. Final NDMA reaction products were carbon dioxide, ammonium, and nitrate, with dimethylamine and methylamine as intermediate products. Reaction rates were first-order with respect to NDMA concentration and surface area normalized oxidation rates as high as 850 +/- 50 L/m(2)-hr were observed at a current density of 10 mA/cm(2). The flow-through reactor yielded mass transfer limited reaction rates that were first-order in NDMA concentration, with a half-life of 2.1 +/- 0.1 min. Experimental evidence indicates that NDMA oxidation proceeds via a direct electron transfer at potentials >1.8 V/SHE with a measured apparent activation energy of 3.1 +/- 0.5 kJ/mol at a potential of 2.5 V/SHE. Density functional theory calculations indicate that a direct two-electron transfer can produce a stable NDMA((+2)) species that is stabilized by forming an adduct with water. The transfer of two electrons from NDMA to the electrode allows an activation-less attack of hydroxyl radicals on the NDMA((+2)) water adduct. At higher overpotentials the oxidation of NDMA occurs by a combination of direct electron transfer and hydroxyl radicals produced via water electrolysis. PMID:19924960

Chaplin, Brian P; Schrader, Glenn; Farrell, James

2009-11-01

250

Understanding reductive dechlorination of trichloroethene on boron-doped diamond film electrodes.  

PubMed

This research investigated reduction of trichloroethylene (TCE) at boron-doped diamond (BDD) film cathodes using a rotating disk electrode reactor. Rates of TCE reduction were determined as functions of the electrode potential and TCE concentration over a temperature range between 2 and 32 degrees C. Reduction of TCE resulted in production of acetate and chloride ions with no detectable intermediate products. At a current density of 15 mA/cm2 and concentrations below 0.75 mM, reaction rates were first order with respect to TCE concentration, with surface area normalized rate constants 2 orders of magnitude greater than those for iron electrodes. Density functional theory (DFT) simulations were used to evaluate activation barriers for reduction by direct electron transfer, and for reaction with four functional groups commonly found on BDD surfaces. The DFT calculated activation barrier for direct electron transfer was more than 4 times greater than the experimentally measured value of 22 kJ/mol. In contrast, the DFT activation barrier for reaction at a deprotonated hydroxyl site on a tertiary carbon atom (triple bond C-O(-)) of 24 kJ/mol was in close agreement with the experimental value. Both experiments and quantum mechanical simulations support a TCE reduction mechanism that involves chemically adsorbed intermediates. PMID:19174914

Mishra, Dhananjay; Liao, Zhaohui; Farrell, James

2008-12-15

251

Electrochemical incineration of dimethyl phthalate by anodic oxidation with boron-doped diamond electrode.  

PubMed

The anodic oxidation of aqueous solutions containing dimethyl phthalate (DMP) up to 125 mg/L with sodium sulfate (Na2SO4) as supporting electrolyte within the pH range 2.0-10.0 was studied using a one-compartment batch reactor employing a boron-doped diamond (BDD) as anode. Electrolyses were carried out at constant current density (1.5-4.5 mA/cm2). Complete mineralization was always achieved owing to the great concentration of hydroxyl radical (*OH) generated at the BDD surface. The effects of pH, apparent current density and initial DMP concentration on the degradation rate of DMP, the specific charge required for its total mineralization and mineralization current efficiency were investigated systematically. The mineralization rate of DMP was found to be pH-independent and to increase with increasing applied current density. Results indicated that this electrochemical process was subjected, at least partially, to the mass transfer of organics onto the BDD surface. Kinetic analysis of the temporal change of DMP concentration during electrolysis determined by High Performance Liquid Chromatography (HPLC) revealed that DMP decay under all tested conditions followed a pseudo first-order reaction. Aromatic intermediates and generated carboxylic acids were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and a general pathway for the electrochemical incineration of DMP on BDD was proposed. PMID:19999984

Hou, Yining; Qu, Jiuhui; Zhao, Xu; Liu, Huijuan

2009-01-01

252

Development of a biochemical oxygen demand sensor using gold-modified boron doped diamond electrodes.  

PubMed

Gold-modified boron doped diamond (BDD) electrodes were examined for the amperometric detection of oxygen as well as a detector for measuring biochemical oxygen demand (BOD) using Rhodotorula mucilaginosa UICC Y-181. An optimum potential of -0.5 V (vs Ag/AgCl) was applied, and the optimum waiting time was observed to be 20 min. A linear calibration curve for oxygen reduction was achieved with a sensitivity of 1.4 ?A mg(-1) L oxygen. Furthermore, a linear calibration curve in the glucose concentration range of 0.1-0.5 mM (equivalent to 10-50 mg L(-1) BOD) was obtained with an estimated detection limit of 4 mg L(-1) BOD. Excellent reproducibility of the BOD sensor was shown with an RSD of 0.9%. Moreover, the BOD sensor showed good tolerance against the presence of copper ions up to a maximum concentration of 0.80 ?M (equivalent to 50 ppb). The sensor was applied to BOD measurements of the water from a lake at the University of Indonesia in Jakarta, Indonesia, with results comparable to those made using a standard method for BOD measurement. PMID:23088708

Ivandini, Tribidasari A; Saepudin, Endang; Wardah, Habibah; Harmesa; Dewangga, Netra; Einaga, Yasuaki

2012-11-06

253

Interaction of copper impurity with radiation defects in silicon doped with boron  

SciTech Connect

The spectrum of deep levels formed in boron-doped Czochralski-grown silicon single crystals as a result of interaction of radiation defects with copper impurity is studied. It is shown that, irrespective of the order of introduction of defects (both in the case of low-temperature copper diffusion into crystals preliminarily irradiated with electrons and in the case of irradiation of the samples contaminated with copper), the same set of deep levels appears. In addition to conventional radiation defects, three types of levels have been detected in the band gap of copper-containing crystals. These levels include the level E{sub v} + 0.49 eV (already mentioned in available publications), the level E{sub v} + 0.51 eV (previously not related to copper), and a level close to the donor level of a vacancy. Based on the analysis of concentration profiles, the interstitial carbonoxygen pair is excluded from possible precursors of the copper-containing center with level E{sub v} + 0.49 eV.

Yarykin, N. A., E-mail: NAY@iptm.ru [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials (Russian Federation); Weber, J. [Technische Universitaet Dresden (Germany)

2010-08-15

254

Electrochemical oxidation of nitrogen-heterocyclic compounds at boron-doped diamond electrode.  

PubMed

Nitrogen-heterocyclic compounds (NHCs) are toxic and bio-refractory contaminants widely spread in environment. This study investigated electrochemical degradation of NHCs at boron-doped diamond (BDD) anode with particular attention to the effect of different number and position of nitrogen atoms in molecular structure. Five classical NHCs with similar structures including indole (ID), quinoline (QL), isoquinoline (IQL), benzotriazole (BT) and benzimidazole (BM) were selected as the target compounds. Results of bulk electrolysis showed that degradation of all NHCs was fit to a pseudo first-order equation. The five compounds were degraded with the following sequence: ID>QL>IQL>BT>BM in terms of their rates of oxidation. Quantum chemical calculation was combined with experimental results to describe the degradation character of NHCs at BDD anode. A linear relationship between degradation rate and delocalization energy was observed, which demonstrated that electronic charge was redistributed through the conjugation system and accumulated at the active sites under the attack of hydroxyl radicals produced at BDD anode. Moreover, atom charge was calculated by semi empirical PM3 method and active sites of NHCs were identified respectively. Analysis of intermediates by GC-MS showed agreement with calculation results. PMID:22071370

Xing, Xuan; Zhu, Xiuping; Li, Hongna; Jiang, Yi; Ni, Jinren

2011-11-08

255

Electrochemical oxidation of purine and pyrimidine bases based on the boron-doped nanotubes modified electrode.  

PubMed

Based on the excellent physicochemical properties of boron-doped carbon nanotubes (BCNTs), the electrochemical analysis of four free DNA bases at the BCNTs modified glassy carbon (GC) electrode was investigated. Herein, the BCNTs/GC electrode exhibited remarkable electrocatalytic activity towards the oxidation of purine bases (guanine (G), adenine (A)). More significantly, the direct oxidation of pyrimidine bases (thymine (T), cytosine (C)) was realized. It may be due to that BCNTs have the advantages of high electron transfer kinetics, large surface area, prominent antifouling ability and electrode activity. On basis of this, a novel and simple strategy for the determination of G, A, T and C was proposed. The BCNTs/GC electrode showed high sensitivity, wide linear range and capability of detection for the electrochemical determination of G, A, T, and C. On the other hand, the electrochemical oxidation of quaternary mixture of G, A, T, and C at the BCNTs/GC electrode was investigated. It was obtained that the peak separation between G and A, A and T, T and C were large enough for their potential recognition in mixture without any separation or pretreatment. The BCNTs/GC electrode also displayed good stability, reproducibility and excellent anti-interferent ability. Therefore, it can be believed that the BCNTs/GC electrode would provide a potential application for the electrochemical detection of DNA in the field of genetic-disease diagnosis. PMID:22154402

Deng, Chunyan; Xia, Yalin; Xiao, Chunhui; Nie, Zhou; Yang, Minghui; Si, Shihui

2011-11-20

256

Energy consumption of electrooxidation systems with boron-doped diamond electrodes in the pulse current mode  

NASA Astrophysics Data System (ADS)

A pulse current technique was conducted in a boron-doped diamond (BDD) anode system for electrochemical wastewater treatment. Due to the strong generation and weak absorption of hydroxyl radicals on the diamond surface, the BDD electrode possesses a powerful capability of electrochemical oxidation of organic compounds, especially in the pulse current mode. The influences of pulse current parameters such as current density, pulse duty cycle, and frequency were investigated in terms of chemical oxygen demand (COD) removal, average current efficiency, and specific energy consumption. The results demonstrated that the relatively high COD removal and low specific energy consumption were obtained simultaneously only if the current density or pulse duty cycle was adjusted to a reasonable value. Increasing the frequency slightly enhanced the COD removal and average current efficiency. A pulse-BDD anode system showed a stronger energy saving ability than a constant-BDD anode system when the electrochemical oxidation of phenol of the two systems was compared. The results prove that the pulse current technique is more cost-effective and more suitable for a BDD anode system for real wastewater treatment. A kinetic analysis was presented to explain the above results.

Wei, Jun-jun; Gao, Xu-hui; Hei, Li-fu; Askari, Jawaid; Li, Cheng-ming

2013-01-01

257

Ordering mechanisms of periodic stripe arrays on boron-doped Si(100)  

NASA Astrophysics Data System (ADS)

We have used low energy electron microscopy to determine the factors that control the degree of order in self-assembled periodic stripe arrays on the atomically flat Si(100) with high boron doping. The stripes consist of extremely elongated vacancy islands of single atomic height, formed at ˜900C, confined in micrometer-sized pits. ``Perfect'' arrays of parallel stripes (in pits of up to ˜10um in size) were formed by allowing various defects to heal over relatively long periods of time. Sublimation was compensated for by an external Si doser, allowing observation of stripe evolution over the course of hours, with no net loss or gain of Si from the area of interest. Stripe formation and ordering mechanisms include spontaneous nucleation and growth of new islands, longitudinal splitting, as well as coarsening due to surface diffusion. Stripe periodicity depends on temperature, allowing for control of this property. Stripes are stable in a range of ˜100C, outside of which they assume the familiar shape of elongated islands, shaped by the anisotropy in step energy. Stripe order can be preserved to room temperature by quenching. References: [1] J.-F. Nielsen et al., Appl. Phys. Lett. 79 (2001) 3857

Ermanoski, Ivan; Kellogg, Gary; Bartelt, Norman

2009-03-01

258

Diamond-modified AFM probes: from diamond nanowires to atomic force microscopy-integrated boron-doped diamond electrodes.  

PubMed

In atomic force microscopy (AFM), sharp and wear-resistant tips are a critical issue. Regarding scanning electrochemical microscopy (SECM), electrodes are required to be mechanically and chemically stable. Diamond is the perfect candidate for both AFM probes as well as for electrode materials if doped, due to diamond's unrivaled mechanical, chemical, and electrochemical properties. In this study, standard AFM tips were overgrown with typically 300 nm thick nanocrystalline diamond (NCD) layers and modified to obtain ultra sharp diamond nanowire-based AFM probes and probes that were used for combined AFM-SECM measurements based on integrated boron-doped conductive diamond electrodes. Analysis of the resonance properties of the diamond overgrown AFM cantilevers showed increasing resonance frequencies with increasing diamond coating thicknesses (i.e., from 160 to 260 kHz). The measured data were compared to performed simulations and show excellent correlation. A strong enhancement of the quality factor upon overgrowth was also observed (120 to 710). AFM tips with integrated diamond nanowires are shown to have apex radii as small as 5 nm and where fabricated by selectively etching diamond in a plasma etching process using self-organized metal nanomasks. These scanning tips showed superior imaging performance as compared to standard Si-tips or commercially available diamond-coated tips. The high imaging resolution and low tip wear are demonstrated using tapping and contact mode AFM measurements by imaging ultra hard substrates and DNA. Furthermore, AFM probes were coated with conductive boron-doped and insulating diamond layers to achieve bifunctional AFM-SECM probes. For this, focused ion beam (FIB) technology was used to expose the boron-doped diamond as a recessed electrode near the apex of the scanning tip. Such a modified probe was used to perform proof-of-concept AFM-SECM measurements. The results show that high-quality diamond probes can be fabricated, which are suitable for probing, manipulating, sculpting, and sensing at single digit nanoscale. PMID:21534601

Smirnov, Waldemar; Kriele, Armin; Hoffmann, René; Sillero, Eugenio; Hees, Jakob; Williams, Oliver A; Yang, Nianjun; Kranz, Christine; Nebel, Christoph E

2011-05-18

259

Electronic structure of the paramagnetic boron oxygen hole center in B-doped SiO2  

NASA Astrophysics Data System (ADS)

We have studied the ground-state properties of boron-related dia- and paramagnetic point defects in B-doped silica. Hartree-Fock and density functional theory calculations have been performed to determine the structure, charge, and spin distribution of the boron oxygen hole center (BOHC). The currently accepted model of the BOHC is that of a hole localized on a nonbonding 2p orbital of an O atom in a bridge position between a B and a Si atom, ?B-O.-Si?. Our calculations do not support this model and show that the structure is not stable and spontaneously evolves into a planar trigonal diamagnetic boron center, >B-, and a nonbridging oxygen, ?Si-O.. The results of this study suggest that the BOHC consists of a three-coordinated B atom bound to a non bridging oxygen, >B-O.. The computed hyperfine coupling constants for this model are in quantitative agreement with those measured experimentally for B-doped silica. This assignment is consistent with recent magnetic resonance studies on borosilicates and alkali borate glasses.

Pacchioni, Gianfranco; Vezzoli, Marco; Fanciulli, Marco

2001-10-01

260

Growth of polycrystalline diamond over glassy carbon and graphite electrode Materials  

SciTech Connect

Boron-doped polycrystalline diamond thin films were grown over glassy carbon electrode material and POCO graphite by a microwave plasma-assisted chemical vapor deposition (CVD) using a gas mixture of methane and hydrogen. As-deposited films were analyzed by scanning electron microscopy (SEM) and Raman spectroscopy for their morphology and chemical nature, respectively the diamond films grown over glassy carbon and graphite electrode material may have some use in electroanalysis since the doped diamond films are electrically conductive, erosion resistant, and chemically inert.

Ramesham, R.; Askew, R.F.; Rose, M.F. (Auburn Univ., AL (United States). Space Power Inst.); Loo, B.H. (Univ. of Alabama, Huntsville, AL (United States). Dept. of Chemistry)

1993-10-01

261

Efficient oxygen evolution reaction catalyzed by low-density Ni-doped Co3O4 nanomaterials derived from metal-embedded graphitic C3N4.  

PubMed

A synthetic route to low-density porous Ni-doped Co3O4 nanomaterials that show stable and superior electrocatalytic activity for O2 evolution reaction is reported. The materials are prepared via thermal treatment of "pre-synthesized" metal ions-embedded graphitic C3N4-based polymers. PMID:23863982

Zou, Xiaoxin; Su, Juan; Silva, Rafael; Goswami, Anandarup; Sathe, Bhaskar R; Asefa, Tewodros

2013-09-01

262

Injection level dependence of the defect-related carrier lifetime in light-degraded boron-doped Czochralski silicon  

NASA Astrophysics Data System (ADS)

The carrier recombination lifetime in light-degraded boron-doped 1 ? cm Czochralski-grown silicon wafers is measured as a function of the bulk excess carrier concentration ?n. The measurements are performed with the quasi-steady state photoconductance method and cover a large injection level range between 1013 and 1.5×1017 cm-3. We observe a very strong increase of the carrier lifetime in the ?n range between 1014 and 2×1016 cm-3, which is attributed to boron-oxygen (BiOi) defect pairs. The observed strong increase of the defect-related carrier lifetime allows us to determine the previously unknown hole capture cross section ?p of the BiOi pair. Our analysis gives a ?p value of (0.45-1.2)×10-15 cm2, which is 2-3 orders of magnitude smaller than the corresponding electron capture cross section.

Schmidt, Jan; Berge, Christopher; Aberle, Armin G.

1998-10-01

263

Electrical transport properties of the Si-doped cubic boron nitride thin films prepared by in situ cosputtering  

SciTech Connect

Si-doped cubic boron nitride (c-BN) films with various Si concentrations were achieved by in situ cosputtering during ion beam assisted deposition. Effects of the Si concentration and rapid thermal annealing (RTA) conditions on the electrical transport properties of Si-doped c-BN thin films were investigated systematically. The results suggest that the optimum RTA condition is at the temperature of 1000 deg. C for 3 min. The resistance of Si-doped c-BN films gradually decreases as the Si concentration increases, indicating an electrical doping effect of the Si impurity. The temperature dependent electrical conductivity of the Si-doped c-BN films suggests that different conduction mechanisms are dominant over the different temperature ranges. Based on the Davis-Mott model, we propose that the extended-state conduction, band tail-state conduction and short-range hopping conduction are responsible for the respective temperature ranges. In addition, the reduction in activation energy of Si impurities is observed as the Si concentration increases.

Ying, J.; Zhang, X. W.; Yin, Z. G.; Tan, H. R.; Zhang, S. G.; Fan, Y. M. [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2011-01-15

264

Electrical and structural properties of low temperature boron- and phosphorus-doped polycrystalline silicon thin films prepared by ECR-CVD  

Microsoft Academic Search

Boron-doped and phosphorus-doped polycrystalline silicon thin films were deposited on glass and SiO2 substrates at a rather low temperature of 250°C by electron cyclotron resonance chemical vapor deposition (ECR-CVD) using SiH4\\/Ar\\/H2\\/B2H6 and SiH4\\/Ar\\/H2\\/PH3 downstream plasma technique. The effects of in situ doping concentration and hydrogen dilution on the structural and electrical properties of heavily doped polycrystalline silicon thin films have

H. L Hsiao; Y. Y Shieh; R. S Lee; R. Y Wang; K. C Wang; H. L Hwang; A. B Yang

1999-01-01

265

Mechanism of perchlorate formation on boron-doped diamond film anodes.  

PubMed

This research investigated the mechanism of perchlorate (ClO(4)(-)) formation from chlorate (ClO(3)(-)) on boron-doped diamond (BDD) film anodes by use of a rotating disk electrode reactor. Rates of ClO(4)(-) formation were determined as functions of the electrode potential (2.29-2.70 V/standard hydrogen electrode, SHE) and temperature (10-40 °C). At all applied potentials and a ClO(3)(-) concentration of 1 mM, ClO(4)(-) production rates were zeroth-order with respect to ClO(4)(-) concentration. Experimental and density functional theory (DFT) results indicate that ClO(3)(-) oxidation proceeds via a combination of direct electron transfer and hydroxyl radical oxidation with a measured apparent activation energy of 6.9 ± 1.8 kJ·mol(-1) at a potential of 2.60 V/SHE. DFT simulations indicate that the ClO(4)(-) formation mechanism involves direct oxidation of ClO(3)(-) at the BDD surface to form ClO(3)(•), which becomes activationless at potentials > 0.76 V/SHE. Perchloric acid is then formed via the activationless homogeneous reaction between ClO(3)(•) and OH(•) in the diffuse layer next to the BDD surface. DFT simulations also indicate that the reduction of ClO(3)(•) can occur at radical sites on the BDD surface to form ClO(3)(-) and ClO(2), which limits the overall rate of ClO(4)(-) formation. PMID:22029642

Azizi, Orchideh; Hubler, David; Schrader, Glenn; Farrell, James; Chaplin, Brian P

2011-11-16

266

Boron-doped diamond electrodes for the electrochemical oxidation and cleavage of peptides.  

PubMed

Electrochemical oxidation of peptides and proteins is traditionally performed on carbon-based electrodes. Adsorption caused by the affinity of hydrophobic and aromatic amino acids toward these surfaces leads to electrode fouling. We compared the performance of boron-doped diamond (BDD) and glassy carbon (GC) electrodes for the electrochemical oxidation and cleavage of peptides. An optimal working potential of 2000 mV was chosen to ensure oxidation of peptides on BDD by electron transfer processes only. Oxidation by electrogenerated OH radicals took place above 2500 mV on BDD, which is undesirable if cleavage of a peptide is to be achieved. BDD showed improved cleavage yield and reduced adsorption for a set of small peptides, some of which had been previously shown to undergo electrochemical cleavage C-terminal to tyrosine (Tyr) and tryptophan (Trp) on porous carbon electrodes. Repeated oxidation with BDD electrodes resulted in progressively lower conversion yields due to a change in surface termination. Cathodic pretreatment of BDD at a negative potential in an acidic environment successfully regenerated the electrode surface and allowed for repeatable reactions over extended periods of time. BDD electrodes are a promising alternative to GC electrodes in terms of reduced adsorption and fouling and the possibility to regenerate them for consistent high-yield electrochemical cleavage of peptides. The fact that OH-radicals can be produced by anodic oxidation of water at elevated positive potentials is an additional advantage as they allow another set of oxidative reactions in analogy to the Fenton reaction, thus widening the scope of electrochemistry in protein and peptide chemistry and analytics. PMID:23763302

Roeser, Julien; Alting, Niels F A; Permentier, Hjalmar P; Bruins, Andries P; Bischoff, Rainer

2013-06-25

267

Bioelectrochemical degradation of urea at platinized boron doped diamond electrodes for bioregenerative applications  

NASA Astrophysics Data System (ADS)

The recovery of potable water from space mission wastewater is critical for the life support and environmental health of crew members in long-term missions. NASA estimates reveal that at manned space missions 0.06 kg/person·day of urine is produced, with urea and various salts as its main components. Current spacecraft water reclamation strategies include the utilization of not only multifiltration systems (MF) and reverse osmosis (RO), but also biological components to deal with crew urine streams. In this research we explore the utilization of urease (EC 3.5.1.5) to convert urea directly to nitrogen by the in-situ utilization of the reaction products, to increase the amount of clean water in future space expeditions. First of all, platinum was electrodeposited on boron doped diamond electrodes by cycling the potential between -0.2 V and 1.0 V in metal/0.5 M H2SO4 solution. SEM images of the electrodes showed a distribution of platinum nanoparticles ranging between 50 nm and 300 nm. The biochemical reaction of urease in nature produces ammonia and carbon dioxide from urea. Based on this, Cyclic Voltammetry experiments of an ammonium acetate solution at pH 10 were performed showing an anodic peak at -0.3 V vs. Ag/AgCl due to the ammonia oxidation. Then, a urease solution (Jack Bean) was poured into the electrochemical cell and subsequent additions of urea were performed with the potential held at -0.3 V in order to promote ammonia oxidation. Chronoamperometry data shows that with more than five urea additions the enzyme still responding by producing ammonia, which is being subsequently oxidized at the electrode surface and producing molecular nitrogen. This research has tremendous applications for future long-term space missions since the reaction byproducts could be used for a biomass subsystem (in-situ resource recovery), while generating electricity from the same process.

Nicolau, Eduardo; Gonzalez, Ileana; Nicolau, Eduardo; Cabrera, Carlos R.

268

Electrochemical detection of sugar-related compounds using boron-doped diamond electrodes.  

PubMed

Electrochemical detection of sugar-related compounds was conducted using a boron-doped diamond (BDD) electrode as a detector for flow-injection analysis (FIA). Sugar-related compounds oxidize at high applied potentials, for which the BDD electrode is suitable for electrochemical measurements. Conditions for an FIA system with a BDD detector were optimized, and the following detection limits were achieved for sugar-related compounds: monosaccharides, 25-100 pmol; sugar alcohols, 10 pmol; and oligosaccharides, 10 pmol. The detection limit for monosaccharide D-glucose (Glu) was 105 pmol (S/N = 3). A linear range was acquired from the detection limit to 50 nmol, and the relative standard deviation was 0.65% (20 nmol, n = 6). A high-performance liquid chromatography (HPLC) column was added to the system between the sample injector and the detector and detection limits to the picomole level were achieved, which is the same for the HPLC system and the FIA system. The electrochemical oxidation reaction of Glu was examined using cyclic voltammetry with the BDD detector. The reaction proved to be irreversible, and proceeded according to the following two-step mechanism: (1) application of a high potential (2.00 V vs. Ag/AgCl) to the electrode causes water to electrolyze on the electrode surface with the simultaneous generation of a hydroxyl radical on the surface, and (2) the hydroxyl radical indirectly oxidizes Glu. Thus, Glu can be detected by an increase in the oxidation current caused by reactions with hydroxy radicals. PMID:22322804

Hayashi, Tomohisa; Sakurada, Ikuo; Honda, Kensuke; Motohashi, Shigeyasu; Uchikura, Kazuo

2012-01-01

269

Electrochemical combustion of herbicide mecoprop in aqueous medium using a flow reactor with a boron-doped diamond anode  

Microsoft Academic Search

The anodic oxidation of 1.8l of solutions with mecoprop (2-(4-chloro-2-methylphenoxy)-propionic acid or MCPP) up to 0.64gl?1 in Na2SO4 as background electrolyte within the pH range 2.0–12.0 has been studied using a flow plant containing a one-compartment filter-press electrolytic reactor with a boron-doped diamond (BDD) anode and a stainless steel cathode, both of 20-cm2 area. Electrolyses carried out in batch under

Cristina Flox; Pere Lluís Cabot; Francesc Centellas; José Antonio Garrido; Rosa María Rodríguez; Conchita Arias; Enric Brillas

2006-01-01

270

Solar photoelectro-Fenton degradation of cresols using a flow reactor with a boron-doped diamond anode  

Microsoft Academic Search

The solar photoelectro-Fenton degradation of 2.5l of acidic solutions containing o-cresol, m-cresol and p-cresol up to ca. 1gl?1, 0.05M Na2SO4 and Fe2+ as catalyst has been studied using a flow plant with a one-compartment filter-press electrolytic reactor with a boron-doped diamond (BDD) anode and an O2-diffusion cathode, both of 20-cm2 area, coupled to a solar photoreactor. In this environmentally friendly

Cristina Flox; Pere-Lluís Cabot; Francesc Centellas; José Antonio Garrido; Rosa María Rodríguez; Conchita Arias; Enric Brillas

2007-01-01

271

Pressure sensitivity of dual resonant long-period gratings written in boron co-doped optical fiber  

NASA Astrophysics Data System (ADS)

The paper presents a pressure sensor based on a long-period grating (LPG) written in boron co-doped photosensitive fiber and operating at the phase-matching turning point. It is shown that the pressure sensitivity can be tuned by varying the UV exposure time during the LPG fabrication process. The achieved pressure sensitivity can reach over 1 nm•bar-1, and is at least four times higher than for previously presented gratings working away from the double-resonance regime. In terms of intensity-based measurement, the sensitivity at the turning point can reach 0.212 dB•bar-1.

Smietana, Mateusz; Bock, Wojtek J.; Mikulic, Predrag; Chen, Jiahua; Wisniewski, Roland

2011-05-01

272

Electrochemical destruction of chlorophenoxy herbicides by anodic oxidation and electro-Fenton using a boron-doped diamond electrode  

Microsoft Academic Search

The degradation of herbicides 4-chlorophenoxyacetic acid (4-CPA), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in aqueous medium of pH 3.0 has been comparatively studied by anodic oxidation and electro-Fenton using a boron-doped diamond (BDD) anode. All solutions are totally mineralized by electro-Fenton, even at low current, being the process more efficient with 1mM Fe2+ as catalyst. This

Enric Brillas; Birame Boye; Ignasi Sirés; José Antonio Garrido; Rosa Mar??a Rodr??guez; Conchita Arias; Pere-Llu??s Cabot; Christos Comninellis

2004-01-01

273

Gas-assisted growth of boron-doped nickel nanotube arrays: rapid synthesis, growth mechanisms, tunable magnetic properties, and super-efficient reduction of 4-nitrophenol  

NASA Astrophysics Data System (ADS)

Highly ordered noncrystalline boron-doped nickel nanotube arrays are rapidly synthesized within 150 s by template-based electroless deposition. The as-prepared nanotubes have tunable magnetic properties and exhibit super efficient catalytic activity (~70 s) for the reduction of 4-nitrophenol.Highly ordered noncrystalline boron-doped nickel nanotube arrays are rapidly synthesized within 150 s by template-based electroless deposition. The as-prepared nanotubes have tunable magnetic properties and exhibit super efficient catalytic activity (~70 s) for the reduction of 4-nitrophenol. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00411b

Li, Xiang-Zi; Wu, Kong-Lin; Ye, Yin; Wei, Xian-Wen

2013-04-01

274

MnTe semiconductor-sensitized boron-doped TiO2 and ZnO photoelectrodes for solar cell applications.  

PubMed

We report a new tailoring MnTe semiconductor-sensitized solar cells (MnTe SSCs) using successive ionic layer adsorption and reaction (SILAR) technique. X-ray diffraction and SAED patterns reveal the orthorhombic MnTe and cubic MnTe2 phases were grown on boron-doped TiO2 and ZnO nanoparticles. The diameter of MnTe NPs ranged from 15 to 30nm on both B-doped metal oxide structures. The energy gaps of metal oxide become narrower after boron doping, which have an advantage for enhancing the light absorption from UV to visible region. Also, the energy gap of MnTe NPs on B-doped metal oxide was determined ~1.27-1.30eV. The best power conversion efficiency (?) of 0.033% and 0.030% yielded from B-doped TiO2/MnTe(7) and B-doped ZnO/MnTe(9), respectively. The reduction in power conversion efficiency by 103% and 91% was due to the absence of boron doping into TiO2 and ZnO nanostructures, respectively. PMID:23786831

Tubtimtae, Auttasit; Arthayakul, Khanittha; Teekwang, Bussayanee; Hongsith, Kritsada; Choopun, Supab

2013-05-31

275

Raman spectroscopy of graphene and graphite: Disorder, electron–phonon coupling, doping and nonadiabatic effects  

Microsoft Academic Search

We review recent work on Raman spectroscopy of graphite and graphene. We focus on the origin of the D and G peaks and the second order of the D peak. The G and 2D Raman peaks change in shape, position and relative intensity with number of graphene layers. This reflects the evolution of the electronic structure and electron–phonon interactions. We

Andrea C. Ferrari

2007-01-01

276

Phosphorous and boron doping of nc-Si:H thin films deposited on plastic substrates at 150 °C by Hot-Wire Chemical Vapor Deposition  

Microsoft Academic Search

Gas-phase phosphorous and boron doping of hydrogenated nanocrystalline thin films deposited by HWCVD at a substrate temperature of 150 °C on flexible-plastic (polyethylene naphthalate, polyimide) and rigid-glass substrates is reported. The influence of the substrate, hydrogen dilution, dopant concentration and film thickness on the structural and electrical properties of the films was investigated. The dark conductivity of B- and P-doped films

S. A. Filonovich; M. Ribeiro; A. G. Rolo; P. Alpuim

2008-01-01

277

Molecular beam epitaxy of boron doped p-type BaSi2 epitaxial films on Si(111) substrates for thin-film solar cells  

NASA Astrophysics Data System (ADS)

We have successfully grown a-axis-oriented p-type BaSi2 films on Si(111) by in situ boron (B) doping using molecular beam epitaxy (MBE). The hole concentration in B-doped BaSi2 was controlled in the range between 1017 and 1019cm-3 at room temperature by changing the temperature of the B Knudsen cell crucible. The acceptor level was estimated to be approximately 23meV.

Ajmal Khan, M.; Hara, Kosuke O.; Nakamura, Kotaro; Du, Weijie; Baba, Masakazu; Toh, Katsuaki; Suzuno, Mitsushi; Toko, Kaoru; Usami, Noritaka; Suemasu, Takashi

2013-09-01

278

Lithium-doped (4,4) Boron nitride nanotube: Density functional theory study of N and B nuclear magnetic shielding and electric field gradient tensors  

Microsoft Academic Search

First principle values of nuclear magnetic shieldings and nuclear quadrupole coupling constants of B and N nuclei via density functional theory (DFT) were calculated for a hydrogen-capped (4,4) single-walled boron nitride nanotube (BNNT) (raw model) and a lithium-doped derivative of it (Li-doped model). The models were first fully relaxed and then the CQ and nuclear magnetic shielding tensor calculations were

Ahmad Seif; Asadollah Boshra; Majid Seif

2009-01-01

279

Mineralization of salicylic acid in acidic aqueous medium by electrochemical advanced oxidation processes using platinum and boron-doped diamond as anode and cathodically generated hydrogen peroxide.  

PubMed

Solutions containing 164 mg L(-1) salicylic acid of pH 3.0 have been degraded by electrochemical advanced oxidation processes such as anodic oxidation, anodic oxidation with electrogenerated H(2)O(2), electro-Fenton, photoelectro-Fenton and solar photoelectro-Fenton at constant current density. Their oxidation power has been comparatively studied in a one-compartment cell with a Pt or boron-doped diamond (BDD) anode and a graphite or O(2)-diffusion cathode. In the three latter procedures, 0.5mM Fe(2+) is added to the solution to form hydroxyl radical (()OH) from Fenton's reaction between Fe(2+) and H(2)O(2) generated at the O(2)-diffusion cathode. Total mineralization is attained for all methods with BDD and for photoelectro-Fenton and solar photoelectro-Fenton with Pt. The poor decontamination achieved in anodic oxidation and electro-Fenton with Pt is explained by the slow removal of most pollutants by ()OH formed from water oxidation at the Pt anode in comparison to their quick destruction with ()OH produced at BDD. ()OH generated from Fenton's reaction oxidizes rapidly all aromatic pollutants, but it cannot destroy final Fe(III)-oxalate complexes. Solar photoelectro-Fenton treatments always yield quicker degradation rate due to the very fast photodecarboxylation of these complexes by UVA irradiation supplied by solar light. The effect of current density on the degradation rate, efficiency and energy cost of all methods is examined. The salicylic acid decay always follows a pseudo-first-order kinetics. 2,3-Dihydroxybenzoic, 2,5-dihydroxybenzoic, 2,6-dihydroxybenzoic, alpha-ketoglutaric, glycolic, glyoxylic, maleic, fumaric, malic, tartronic and oxalic acids are detected as oxidation products. A general reaction sequence for salicylic acid mineralization considering all these intermediates is proposed. PMID:17692891

Guinea, Elena; Arias, Conchita; Cabot, Pere Lluís; Garrido, José Antonio; Rodríguez, Rosa María; Centellas, Francesc; Brillas, Enric

2007-08-01

280

CE with a boron-doped diamond electrode for trace detection of endocrine disruptors in water samples.  

PubMed

Off-line SPE and CE coupled with electrochemical detection have been used for the determination of bisphenol A (BPA), bisphenol F, 4-ethylphenol, and bisphenol A diglycidyl ether in bottled drinking water. The use of boron-doped diamond electrode as an electrochemical detector in amperometric mode that provides a favorable analytical performance for detecting these endocrine-disrupting compounds, such as lower noise levels, higher peak resolution with enhanced sensitivity, and improved resistance against electrode passivation. The oxidative electrochemical detection of the endocrine-disrupting compounds was accomplished by boron-doped diamond electrode poised at +1.4 V versus Ag/AgCl without electrode pretreatment. An off-line SPE procedure (Bond Elut® C18 SPE cartridge) was utilized to extract and preconcentrate the compounds prior to separation and detection. The minimum concentration detectable for all four compounds ranged from 0.01 to 0.06 ?M, having S/N equal to three. After exposing the plastic bottle water container under sunlight for 7 days, the estimated concentration of BPA in the bottled drinking water was estimated to be 0.03 ?M. This proposed approach has great potential for rapid and effective determination of BPA content present in water packaging of plastic bottles that have been exposed to sunlight for an extended period of time. PMID:23172695

Browne, Damien J; Zhou, Lin; Luong, John H T; Glennon, Jeremy D

2013-02-21

281

Assessment of Electrodes Prepared from Wafers of Boron-doped Diamond for the Electrochemical Oxidation of Waste Lubricants  

SciTech Connect

Electrochemical oxidation using boron-doped diamond electrodes is being investigated as a treatment process for radioactively contaminated oily wastes. Previously, it was shown that electrodes coated with a thin film of diamond were able to oxidise a cutting oil but not a mineral oil. These tests were inconclusive, because the electrodes lost their diamond coating during operation. Accordingly, an electrode prepared from a 'solid' wafer of boron-doped diamond is being investigated to determine whether it will oxidise mineral oils. The electrode has been tested with sucrose, a cutting oil and an emulsified mineral oil. Before and after each test, the state of the electrode was assessed by cyclic voltammetry with the ferro/ferricyanide redox couple. Analysis of the cyclic voltammogram suggested that material accumulated on the surface of the electrode during the tests. The magnitude of the effect was in the order: - emulsified mineral oil > cutting oil > sucrose. Despite this, the results indicated that the electrode was capable of oxidising the emulsified mineral oil. Confirmatory tests were undertaken in the presence of alkali to trap the carbon dioxide, but they had to be abandoned when the adhesive holding the diamond in the electrode was attacked by the alkali. Etching of the diamond wafer was also observed at the end of the tests. Surface corrosion is now regarded as an intrinsic part of the electrochemical oxidation on diamond, and it is expected that the rate of attack will determine the service life of the electrodes. (authors)

Taylor, G.T.; Sullivan, I.A.; Newey, A.W.E. [AWE, Aldermaston, Reading, RG7 4PR (United Kingdom)

2006-07-01

282

Catalytic graphitization of Mo-B-doped polyacrylonitrile (PAN)-based carbon fibers  

Microsoft Academic Search

A novel carbon fiber pretreatment was proposed. Polyacrylonitrile (PAN)-based carbon fibers were first anodized in H3PO4 electrolyte to achieve an active surface, and then coated with Mo-B catalysts by immersed the carbon fibers in a uniformly\\u000a dispersed Mo-B sol. The as-treated carbon fibers were then graphitized at 2 400 °C for 2 h. The structural changes were characterized\\u000a by X-ray

Shi-hai Xu; Feng-ying Zhang; Shao-huan Liu; Dong-mei He; Qing-yun Cai

2010-01-01

283

Magnetization Study of Sulfur-doped Graphitic Nano-platelets and Single Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Recently we investigated the magnetic behavior of as-prepared and sulfur doped chemically exfoliated graphene nano-platelets (GNPs) and single walled carbon nanotubes (SWCNTs). The doping was achieved by annealing desired carbon nanostructures with 0, 1.0, 1.5 and 3 at% sulfur in an evacuated quartz tube at 1000 ^oC for 1 day, followed by multiple rinsing in alcohol and drying in vacuum to remove excess sulfur. The isothermal M vs. H as well as the temperature-dependent M vs. T measurements were obtained using a vibrating sample magnetometer. We found that sulfur doping drastically changes the magnetic behavior of the as-prepared samples (both SWCNTs and GNPs). The results of zero-field-cooling (ZFC) and field-cooling (FC) in M vs. T measurements indicated the existence of large amount of coupled super-paramagnetic domains, along with antiferromagnetic domains. The saturation magnetization decreased in S doped GNPs, while a contrasting trend was observed in S doped SWCNTs. The role of edge states and structural defects in carbon nanostructures in the observed magnetic properties will be discussed.

Zhu, J.; Oliveira, L.; Podila, R.; Neeleshwar, S.; Chen, Y. Y.; He, J.; Skove, M.; Rao, A. M.

2013-03-01

284

Gas-assisted growth of boron-doped nickel nanotube arrays: rapid synthesis, growth mechanisms, tunable magnetic properties, and super-efficient reduction of 4-nitrophenol.  

PubMed

Highly ordered noncrystalline boron-doped nickel nanotube arrays are rapidly synthesized within 150 s by template-based electroless deposition. The as-prepared nanotubes have tunable magnetic properties and exhibit super efficient catalytic activity (?70 s) for the reduction of 4-nitrophenol. PMID:23546439

Li, Xiang-Zi; Wu, Kong-Lin; Ye, Yin; Wei, Xian-Wen

2013-04-02

285

Electrochemical treatment of wastewaters containing organic pollutants on boron-doped diamond electrodes: Prediction of specific energy consumption and required electrode area  

Microsoft Academic Search

A theoretical analysis is presented for the prediction of the specific energy consumption and the required electrode surface for the electrochemical combustion of organic compounds on synthetic boron-doped diamond (BDD) thin film electrodes. The model is formulated for a perfect mixed electrochemical reactor operated as a batch recirculation system under galvanostatic conditions. The anodic oxidation of organics is assumed to

M. Panizza; P. A. Michaud; G. Cerisola; Ch Comninellis

2001-01-01

286

Application of a boron doped diamond (BDD) electrode as an anode for the electrolytic reduction of UO2 in Li2O-LiCl-KCl molten salt  

NASA Astrophysics Data System (ADS)

A boron doped diamond thin film electrode was employed as an inert anode to replace a platinum electrode in a conventional electrolytic reduction process for UO2 reduction in Li2O-LiCl molten salt at 650 °C. The molten salt was changed into Li2O-LiCl-KCl to decrease the operation temperature to 550 °C at which the boron doped diamond was chemically stable. The potential for oxygen evolution on the boron doped diamond electrode was determined to be approximately 2.2 V vs. a Li-Pb reference electrode whereas that for Li deposition was around -0.58 V. The density of the anodic current was low compared to that of the cathodic current. Thus the potential of the cathode might not reach the potential for Li deposition if the surface area of the cathode is too wide compared to that of the anode. Therefore, the ratio of the surface areas of the cathode and anode should be precisely controlled. Because the reduction of UO2 is dependent on the reaction with Li, the deposition of Li is a prerequisite in the reduction process. In a consecutive reduction run, it was proved that the boron doped diamond could be employed as an inert anode.

Park, Wooshin; Kim, Jong-Kook; Hur, Jin-Mok; Choi, Eun-Young; Im, Hun Suk; Hong, Sun-Seok

2013-01-01

287

Highly efficient and energy-saving sectional treatment of landfill leachate with a synergistic system of biochemical treatment and electrochemical oxidation on a boron-doped diamond electrode  

Microsoft Academic Search

In this paper, a synergistic combination of the biochemical treatment and electrochemical oxidation (SBEO) of landfill leachate with sectional treatment on a boron-doped diamond (BDD) electrode is proposed. The first stage involves the synergistic system of biochemical treatment and electrochemical oxidation. Then, the second stage is followed by individual biochemical treatment. Comparisons among the SBEO, electrochemical oxidation, biochemical treatment and

Guohua Zhao; Yaning Pang; Lei Liu; Junxia Gao; Baoying Lv

2010-01-01

288

Neutron detector employing doped pyrolytic boron nitride and method of making thereof  

US Patent & Trademark Office Database

A system for measuring a thermal neutron emission from a neutron source is provided. The system employs a detector utilizing a plurality of doped pBN layers, wherein the doped pBN layers are doped with at least one dopant across an a-b plane of the layers for an electrical resistivity of 10.sup.14 ohm-cm or less.

Sane; Ajit Yeshwant (Medina, OH); Leist; Jon Russsell (North Olmsted, OH); Moore; Arthur William (Strongsville, OH)

2006-04-25

289

Dielectric properties of binary BaTiO3\\/PVDF and graphite doped GN\\/BaTiO3\\/PVDF nanocomposites  

Microsoft Academic Search

Binary BaTiO3\\/PVDF nanocomposites and its nanographite (GN) doped ternary hybrids were fabricated using simple solution casting and hot compression molding. The dielectric behavior of such hybrids over a wide frequency range was studied. Additions of graphite nanosheets with their concentrations close to percolation threshold were found to be very effective to enhance the dielectric permittivity of GN\\/BaTiO3\\/PVDF nanocomposites. Furthermore, both

Yuchao Li; R. K. Y. Li; Sie Chin Tjong

2010-01-01

290

A comparative study of the electrochemical oxidation of the herbicide tebuthiuron using boron-doped diamond electrodes.  

PubMed

The thiadiazolylurea derivative tebuthiuron (TBH) is commonly used as an herbicide even though it is highly toxic to humans. While various processes have been proposed for the removal of organic contaminants of this type from wastewater, electrochemical degradation has shown particular promise. The aim of the present study was to investigate the electrochemical degradation of TBH using anodes comprising boron-doped (5000 and 30,000 ppm) diamond (BDD) films deposited onto Ti substrates operated at current densities in the range 10-200 mA cm(-2). Both anodes removed TBH following a similar pseudo first-order reaction kinetics with k(app) close to 3.2 × 10(-2) min(-1). The maximum mineralization efficiency obtained was 80%. High-pressure liquid chromatography with UV-VIS detection established that both anodes degraded TBH via similar intermediates. Ion chromatography revealed that increasing concentrations of nitrate ions (up to 0.9 ppm) were formed with increasing current density, while the formation of nitrite ions was observed with both anodes at current densities ? 150 mA cm(-2). The BDD film prepared at the lower doping level (5000 ppm) was more efficient in degrading TBH than its more highly doped counterpart. This unexpected finding may be explained in terms of the quantity of impurities incorporated into the diamond lattice during chemical vapor deposition. PMID:22406242

Alves, S A; Ferreira, T C R; Sabatini, N S; Trientini, A C A; Migliorini, F L; Baldan, M R; Ferreira, N G; Lanza, M R V

2012-03-09

291

Hollow shells of high surface area graphitic N-doped carbon composites nanocast using zeolite templates  

Microsoft Academic Search

Hollow shells of porous nitrogen-doped carbon materials with high surface area have been prepared using zeolite templates (zeolite ? or silicalite-I) and acetonitrile as carbon source via chemical vapour deposition (CVD) performed at between 800 and 1000°C. The nitrogen content varies between 3.0 and 7.9wt.% depending on the zeolite template and CVD temperature. The carbon materials generally retain the particle

Zhuxian Yang; Yongde Xia; Robert Mokaya

2005-01-01

292

Electrical transport properties of boron-doped single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The transport properties of B-doped single-walled carbon nanotubes (SWNTs) are studied from both experimental and theoretical standpoints. Experimentally, it is found that the semiconducting behavior of SWNTs is drastically changed after B-doping, and the unusual abrupt current drops are observed at low temperatures, which may imply the possibility of superconducting transition in B-doped SWNTs. Using the density-functional tight-binding calculation, it is observed that B-doping induces the presence of density of state peaks near the Fermi level which shifts toward the valence band region, showing a clear charge-transfer characteristic, which agrees well with the experimental observations.

Li, Y. F.; Wang, Y.; Chen, S. M.; Wang, H. F.; Kaneko, T.; Hatakeyama, R.

2013-02-01

293

Voltammetric determination of mixtures of caffeine and chlorogenic acid in beverage samples using a boron-doped diamond electrode.  

PubMed

Herein, a boron-doped diamond (BDD) electrode that is anodically pretreated was used for the simultaneous determination of caffeine (CAF) and chlorogenic acid (CGA) by cyclic and adsorptive stripping voltammetry. The dependence of peak current and potential on pH, scan rate, accumulation parameters and other experimental variables were studied. By using square-wave stripping mode after 60s accumulation under open-circuit voltage, the BDD electrode was able to separate the oxidation peak potentials of CAF and CGA present in binary mixtures by about 0.4V in Britton-Robinson buffer at pH 1.0. The limits of detection were 0.107µgmL(-1) (5.51×10(-7)M) for CAF, and 0.448µgmL(-1) (1.26×10(-6)M) for CGA. The practical applicability of this methodology was tested in commercially available beverage samples. PMID:24148509

Yard?m, Yavuz; Keskin, Ertugrul; Sentürk, Zühre

2013-08-23

294

Electrochemical oxidation of phenolic and other organic compounds at boron doped diamond electrodes for wastewater treatment: effect of mass transfer.  

PubMed

The paper presents the results of an experimental study on oxidation at boron doped diamond electrodes (BDD) of some phenolic compounds: phenol (PH), para-hydroxibenzoic acid (PHB), cathecole (CT), hydroquinone (HQ) are considered, singularly contained in aqueous solutions or in the presence of glucose (G), which was selected to represent the class of biodegradable compounds. Oxidation of benzoquinone (BQ) and maleic acid (MA), generally detected as intermediates products from phenol degradation, is also investigated. Great attention is paid to verify the feasibility of a selective process in which the oxidation is specifically addressed to the phenolic fraction up to non toxic intermediate products which are more biodegradable than the original phenols. PMID:14756252

Polcaro, Anna Maria; Mascia, Michele; Palmas, Simonetta; Vacca, Annalisa

2003-12-01

295

Controlling the diffusion profile of electroactive species for selective anodic stripping voltammetry of cadmium at boron-doped diamond electrodes.  

PubMed

Selective anodic stripping voltammetry of trace metal ions in a mixture solution with another interfering metal was developed based on Fick's law concerning the diffusion profile of interfering metals at the electrode surface after electrolysis treatment. A boron-doped diamond film was used as the sensing electrode, while a perforated carbon sheet was used for the interference-depleting electrode. The influence of the electrode distance and the time of electrolysis on the formation of the diffusion profile was studied. As a working model, the detection of cadmium with copper interference was investigated. The advantage of the method in comparison to general electrolysis was also discussed. The method offers a new perspective for improving the selective detection of metal ions by analyzing the diffusion profiles of the interfering species at the surface of electrodes. PMID:23147907

Sugitani, Ai; Watanabe, Takeshi; Ivandini, Tribidasari A; Iguchi, Tatsuo; Einaga, Yasuaki

2012-11-13

296

Simultaneous voltammetric determination of synthetic colorants in food using a cathodically pretreated boron-doped diamond electrode.  

PubMed

Differential pulse voltammetry (DPV) and a cathodically pretreated boron-doped diamond (BDD) electrode were used to simultaneously determine two pairs of synthetic food colorants commonly found mixed in food products: tartrazine (TT) and sunset yellow (SY) or brilliant blue (BB) and sunset yellow (SY). In the DPV measurements using the BDD electrode, the reduction peak potentials of TT and SY or BB and SY were separated by about 150 mV. The detection limit values obtained for the simultaneous determination of TT and SY or BB and SY were 62.7 nmol L(-1) and 13.1 nmol L(-1) or 143 nmol L(-1) and 25.6 nmol L(-1), respectively. The novel proposed voltammetric method was successfully applied in the simultaneous determination of these synthetic colorants in food products, with results similar to those obtained using a HPLC method at 95% confidence level. PMID:22841082

Medeiros, Roberta A; Lourencao, Bruna C; Rocha-Filho, Romeu C; Fatibello-Filho, Orlando

2012-04-26

297

Extraordinary pressure sensitivity of long-period gratings written in a boron co-doped optical fiber  

NASA Astrophysics Data System (ADS)

The paper presents novel pressure sensor based on the long period gratings written with an arc-induced method in a boron co-doped photosensitive fiber. The achieved pressure sensitivity is at least 5 times higher than for the gratings written in other fibers and presented to date. It was found that the incorporation of B2O3 in the core of the fiber is responsible for its higher pressure sensitivity. This conclusion has been achieved after considering the variations of the elastic properties of the glass versus its composition. The sensitivity of the structure to temperature and to external refractive index was also discussed. It was proven that the experiment was conducted in a way that the measured pressure sensitivity was not affected by the temperature or by the external refractive index variations.

Smietana, Mateusz; Bock, Wojtek J.; Chen, Jiahua; Mikulic, Predrag

2009-10-01

298

Electrocatalytic and photocatalytic activity of Pt-TiO2 films on boron-doped diamond substrate  

NASA Astrophysics Data System (ADS)

In the present work boron-doped diamond (BDD) polycrystalline films were used as support for direct anodic deposition of hydrous titanium oxide, and continuous TiO2 coatings were obtained by appropriately adjusting the deposition charge. The photoelectrochemical activity of the TiO2/BDD electrodes was investigated and it was found that, in terms of charge carriers separation efficiency, conductive diamond is a much better support for TiO2, compared to traditional carbonaceous materials such as glassy carbon. Further electrochemical deposition of platinum particles on the oxide-coated conductive diamond enabled the formation of a composite with enhanced electrochemically active surface area. The electrocatalytic and photocatalytic properties of the Pt/TiO2/BDD electrodes thus obtained were also scrutinized and it appeared that these hybrid systems also exhibit promising features for methanol anodic oxidation.

Sp?taru, Tan?a; Marcu, Maria; Sp?taru, Nicolae

2013-03-01

299

Electronic properties of the metastable defect in boron-doped Czochralski silicon: Unambiguous determination by advanced lifetime spectroscopy  

NASA Astrophysics Data System (ADS)

By combining data from temperature- and injection-dependent lifetime spectroscopy (TDLS and IDLS) measured by means of the microwave-detected photoconductance decay technique and the quasi-steady state photoconductance technique, respectively, the exact electronic structure of the metastable defect in standard boron-doped Czochralski (Cz) silicon has been determined. A detailed Shockley-Read-Hall analysis of the entire TDLS curve reveals that the Cz-specific defect acts as an attractive Coulomb center [?n(T)=?n0T-2] which is localized in the upper band-gap half at EC-Et=0.41 eV and has an electron/hole capture cross section ratio k=?n/?p=9.3. The accuracy of this determination manifests itself by the fact that the corresponding IDLS curve can be simulated with the same parameter set.

Rein, S.; Glunz, S. W.

2003-02-01

300

Cathodic and anodic pre-treated boron doped diamond with different sp2 content: Morphological, structural, and impedance spectroscopy characterizations  

NASA Astrophysics Data System (ADS)

In this work, the influence of cathodic (Red) and anodic (Ox) pre-treatment on boron doped diamond (BDD) films grown with different sp2/sp3 ratios was systematically studied. The sp2/sp3 ratios were controlled by the addition of CH4 of 1,3,5 and 7 sccm in the gas inlet during the growth process. The electrodes were treated in 0.5 mol L-1 H2SO4 at -3 and 3 V vs Ag/AgCl, respectively, for 30 min. The electrochemical response of BDD films was investigated using electrochemical impedance spectroscopy (EIS) and Mott-Schottky Plot (MSP) measurements. Four film sample sets were produced in a hot filament chemical vapor deposition reactor. During the growth process, an additional H2 line passing through a bubbler containing the B2O3 dissolved in methanol was used to carry the boron. The scanning electron microscopy morphology showed well faced films with a small decrease in their grain size as the CH4 concentration increased. The Raman spectra depicted a pronounced sp2 band, mainly for films with 5 and 7 sccm of CH4. MSP showed a decrease in the acceptor concentration as the CH4 increased indicating the CH4 influence on the doping process for Red-BDD and Ox-BDD samples. Nonetheless, an apparent increase in the acceptor concentrations for both Ox-BDD samples was observed compared to that for Red-BDD samples, mainly attributed to the surface conductive layer (SCL) formation after this strong oxidation process. The EIS Nyquist plots for Red-BDD showed a capacitance increase for the films with higher sp2 content (5 and 7 sccm). On the other hand, the Nyquist plots for Ox-BDD can be described as semicircles near the origin, at high frequencies, where their charge transfer resistance strongly varied with the sp2 increase in such films.

Baldan, M. R.; Azevedo, A. F.; Couto, A. B.; Ferreira, N. G.

2013-12-01

301

Low-Temperature Softening Due to Vacancy Orbital with ?8 Quartet Ground State in Boron-Doped Floating Zone Silicon  

NASA Astrophysics Data System (ADS)

We have carried out low-temperature ultrasonic measurements using shear-mode ultrasound to clarify the quantum state of a vacancy orbital in boron-doped silicon grown by the floating zone (FZ) method. The elastic constants (C11-C12)/2 and C44 of the transverse mode exhibit considerable softening below 2 and 5 K down to the base temperature of 30 mK, respectively. The elastic constant C44 measured by the three ultrasonic modes (kx,uy), (kz,ux), and (kx,uz) shows the different magnetic field dependences among the configurations under applied magnetic fields along the z-axis. The elastic softening and the magnetic field dependence of the elastic constants are accounted for by the quadrupole susceptibility based on the energy level scheme of the vacancy orbital with a ?8 quartet ground state and ?7 doublet excited state located at an energy of 1 K. The difference in C44 between the two ultrasonic modes (kz,ux) and (kx,uz) at fields along the z-axis indicates that the ?8 quartet ground state is slightly split by local strain in the silicon sample. The quantum state of the vacancy orbital is expected to be sensitive to strain because of the extremely large quadrupole-strain coupling energy of g?? 105 K due to the extensively spreading orbital radius of r? 1 nm. The differences in variation of the low-temperature softening and magnetic field dependence among eight samples cut out from different locations of the present boron-doped FZ silicon ingot evidence the inhomogeneous distribution of the vacancy concentration.

Baba, Shotaro; Akatsu, Mitsuhiro; Mitsumoto, Keisuke; Komatsu, Satoru; Horie, Kunihiko; Nemoto, Yuichi; Yamada-Kaneta, Hiroshi; Goto, Terutaka

2013-08-01

302

ELECTROLYTIC PRODUCTION OF BORON  

Microsoft Academic Search

Elemental boron was produced by the fused salt electrolysis of potassium ; fluoborate. A study was made of anode and cathode materials of construction, ; particularly the effect of various grades of graphite as anode material. The ; effect of additives to the electrolyte (including potassium, aluminum, calcium, ; vanadium, nickel, Inconel, water, and sulfate ion) on boron yield and

George T. Miller

1959-01-01

303

Electric field effect on the electronic properties of double-walled carbon-doped boron-nitride nanotubes  

NASA Astrophysics Data System (ADS)

Carbon (C) doped zigzag (8, 0)@(16, 0) and armchair (5, 5)@(10, 10) double-walled boron-nitride nanotubes (DWBNNTs), under the influence of external electric fields applied in different directions are studied through first-principles calculations. We have considered the substitution of a B and a N (one species at each wall—inner or outer) by C atoms, generating a type-n inside a type-p semiconductor ((type-n)@(type-p)) and vice-versa. The resulting doped DWBNNT can be thought as a p-n junction. The obtained formation energies and structural properties results indicate that these structures present good stability and are not affected by the electric field application. For the electronic structure, it was observed that external fields can be used to modulate these systems energy gaps. Also, there is a preferred field direction which minimizes the gap values, and the gap increase or decrease is related to the reverse and direct polarization of the p-n junction, respectively.

Freitas, A.; Azevedo, S.; Kaschny, J.; Machado, M.

2013-09-01

304

Highly sensitive pressure sensor based on long-period gratings written in a boron co-doped optical fiber  

NASA Astrophysics Data System (ADS)

The paper presents a novel pressure sensor based on long-period gratings (LPGs) written with an arc-induced method in a boron co-doped photosensitive fiber. The achieved pressure sensitivity for these gratings is at least four to eight times higher than for gratings written in other fibers which have been presented to date. The sensitivity is strongly dependent on the investigated order of modes, and for the 7th cladding mode can reach ??/?p = 78 pm bar-1. It was found that the incorporation of B2O3 in the core of the fiber is responsible for the higher pressure sensitivity of these LPGs. This conclusion is based on consideration of variations in the elastic properties of the glass versus its composition. According to our simulations, the pressure-optic coefficient of the B/Ge-doped core of the fiber is 2.03 RIU bar-1. The sensitivity of the structure to temperature and to external refractive index is discussed from the point of view of the possible indirect influence of these conditions on the pressure response. It is proven that the experiment was conducted in such a way that the measured pressure sensitivity was not significantly affected by variations in either the temperature or the external refractive index.

Smietana, M.; Bock, W. J.; Chen, J.; Mikulic, P.

2010-09-01

305

Investigation of film formation properties during electrochemical oxidation of serotonin (5-HT) at polycrystalline boron doped diamond.  

PubMed

The change in surface morphology of oxygen-terminated polycrystalline boron doped diamond (pBDD) during electrochemical oxidation of the neurotransmitter serotonin (5-HT), resulting in a corresponding deterioration of the current signal, is investigated for the first time using both high resolution ex situ and in situ microscopy under a range of different electrochemical conditions. In situ electrochemical-atomic force microscopy (EC-AFM) reveals the formation of a granular film over the surface, which grows faster at higher-doped regions of the electrode surface and increases in thickness with repetitive potential cycles. The film properties were investigated using both cyclic voltammetry, with a range of redox species varying in charge, and conducting-AFM. These studies reveal the film to be positively charged and electrically insulating. The extent to which the film forms during 5-HT oxidation could be significantly minimised using different electrochemical procedures, as verified by voltammetry and in situ EC-AFM. Finally, even after extensive film formation, the original current signal could be recovered simply by leaving the electrode at open circuit potential for a short period of time, highlighting the suitability of BDD electrodes for neurotransmitter detection. PMID:24060971

Patel, Anisha N; Unwin, Patrick R; Macpherson, Julie V

2013-10-01

306

Remarkably low turn-on field emission in undoped, nitrogen-doped, and boron-doped graphene  

NASA Astrophysics Data System (ADS)

Field emission studies have been carried out on undoped as well as N- and B-doped graphene samples prepared by arc-discharge method in a hydrogen atmosphere. These graphene samples exhibit very low turn-on fields. N-doped graphene shows the lowest turn-on field of 0.6 V/?m, corresponding to emission current density of 10 ?A/cm2. These characteristics are superior to the other types of nanomaterials reported in the literature. Furthermore, emission currents are stable over the period of more than 3 h for the graphene samples. The observed emission behavior has been explained on the basis of nanometric features of graphene and resonance tunneling phenomenon.

Palnitkar, U. A.; Kashid, Ranjit V.; More, Mahendra A.; Joag, Dilip S.; Panchakarla, L. S.; Rao, C. N. R.

2010-08-01

307

Evidence for substitutional boron in doped single-walled carbon nanotubes  

SciTech Connect

Precise determination of acceptors in the laser ablation grown B doped single-walled carbon nanotubes (SWCNTs) has been elusive. Photoemission spectroscopy finds evidence for subpercent substitutional B in this material, which leads to superconductivity in thin film SWNT samples.

Ayala, P.; Pichler, T. [Faculty of Physics, University of Vienna, 1090 Wien (Austria); Reppert, J.; Rao, A. M. [Department of Physics and Astronomy and COMSET, Clemson University (United States); Grobosch, M.; Knupfer, M. [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany)

2010-05-03

308

Brazing graphite to graphite  

DOEpatents

Graphite is joined to graphite by employing both fine molybdenum powder as the brazing material and an annealing step that together produce a virtually metal-free joint exhibiting properties similar to those found in the parent graphite. Molybdenum powder is placed between the faying surfaces of two graphite parts and melted to form molybdenum carbide. The joint area is thereafter subjected to an annealing operation which diffuses the carbide away from the joint and into the graphite parts. Graphite dissolved by the dispersed molybdenum carbide precipitates into the joint area, replacing the molybdenum carbide to provide a joint of virtually graphite.

Peterson, George R. (Andersonville, TN)

1976-01-01

309

DFT-D studies of single porphyrin molecule on doped boron silicon surfaces.  

PubMed

We present a theoretical study in the framework of density functional calculations, taking into account the van der Waals interactions (DFT-D) of isolated Cu-5,10,15,20-tetrakis(3,5-di-tert-butyl-phenyl) porphyrin (Cu-TBPP) molecules in a C2v conformation adsorbed on a Si(111)?3x?3R30°-boron surface [denoted Si(111)-B]. With this approach, we investigate interactions between perfect or boron-defect Si(111)-B substrates and the Cu-TBPP molecule as well as the consequences of demetallation of Cu-TBPP. For each model, we determine the structural equilibrium, the spatial charge-density distribution and the electronic properties of the ground state. We conclude that there is potential for Si adatom capture by a porphyrin without strong modification of the porphyrin response, as seen from simulated scanning tunneling microscopy (STM) images. PMID:23055297

Boukari, Khaoula; Sonnet, Philippe; Duverger, Eric

2012-10-10

310

Dynamics of the processes of electron-hole recombination and capture of charge carriers in anatase doped with boron, carbon, or nitrogen  

NASA Astrophysics Data System (ADS)

The first-principles investigation of the processes of nonradiative recombination of electron-hole pairs and binding of excited charge carriers with impurity atoms in anatase doped with boron, carbon, or nitrogen has been carried out using the perturbation theory method. The perturbation is provided by a dynamically screened electron-electron interaction potential calculated in the random phase approximation. It has been shown that the most probable processes occurring upon doping with boron and carbon are exchange processes in which electrons are bound with the impurity atom, whereas the most probable processes observed upon doping with nitrogen are exchange processes in which holes are bound with the impurity atom. These processes occur within a time interval of shorter than 2 fs. The next in probability are the processes of energy losses by unbound electrons and holes due to the generation of phonons. For the case of nitrogen doping, the time of this process is estimated at approximately 300 fs. For excitons formed in this case, the luminescence photon energy and the binding energy of electrons or holes with the impurity atom are estimated. The agreement between the calculated data and the results of experiments on the photocatalysis proceeding on the surface of N-doped anatase is discussed.

Zhukov, V. P.; Chulkov, E. V.

2013-09-01

311

Effect of total reaction pressure on electrical properties of boron doped homoepitaxial (100) diamond films formed by microwave plasma-assisted chemical vapor deposition using trimethylboron  

Microsoft Academic Search

Boron was doped into diamond films which were synthesized homoepitaxially on polished (100) diamond substrates by means of microwave plasma-assisted chemical vapor deposition (MPCVD) using trimethylboron as the dopant at a constant substrate temperature of 1073K. The morphologies and electrical properties of the synthesized diamond films were dependent on the total reaction pressure. A maximum Hall mobility, 760cm2V?1s?1, was obtained

T Tsubota; T Fukui; M Kameta; T Saito; K Kusakabe; S Morooka; H Maeda

1999-01-01

312

Low temperature deposition of boron-doped microcrystalline Si:H thin film and its application in silicon based thin film solar cells  

Microsoft Academic Search

Boron-doped hydrogenated microcrystalline silicon thin films (p-?c-Si:H) have been deposited by RF-PECVD method at different temperature, and the temperature dependence of growth kinetics and optoelectronic properties of p-?c-Si:H thin films have been studied. Both the deposition rate and the dark-conductivity of the p-?c-Si:H thin films drop down when the substrate temperature decreases. XRD and Raman measurements are used to characterize

Ke Tao; Dexian Zhang; Jingfang Zhao; Linshen Wang; Hongkun Cai; Yun Sun

2010-01-01

313

Surface structure and surface barrier characteristics of boron-doped diamond in electrolytes after CF 4 plasma treatment in RF-barrel reactor  

Microsoft Academic Search

We report on the effects of CF4 plasma process in technical RF barrel reactor on surface termination and the resulting electronic surface barrier of boron-doped diamond in electrolytes. The surface characteristics were evaluated for epitaxial single crystalline layers with sub-nm roughness. The capacitance–voltage characteristics of the processes electrodes implied a low electronic barrier at the fluorine-terminated areas, comparable to hydrogen

A. Denisenko; A. Romanyuk; C. Pietzka; J. Scharpf; E. Kohn

2010-01-01

314

Methanol and ethanol electro-oxidation on Pt–SnO 2 and Pt–Ta 2O 5 sol–gel-modified boron-doped diamond surfaces  

Microsoft Academic Search

The search for more efficient anode catalyst than platinum to be used in direct alcohol fuel cell systems is an important challenge. In this study, boron-doped diamond film surfaces were modified with Pt, Pt–SnO2 and Pt–Ta2O5 nano-crystalline deposits by the sol–gel method to study the methanol and ethanol electro-oxidation reactions in acidic medium. Electrochemical experiments carried out in steady-state conditions

Giancarlo R. Salazar-Banda; Hugo B. Suffredini; Luis A. Avaca; Sergio A. S. Machado

2009-01-01

315

Electrochemical treatment of phenolic waters in presence of chloride with boron-doped diamond (BDD) anodes: Experimental study and mathematical model  

Microsoft Academic Search

This work deals with an experimental and numerical study on the electrochemical treatment of waters containing phenolic compounds with boron-doped diamond (BDD) anodes.Anodic oxidation of m-cresol, as a model of phenolic compound, was investigated by galvanostatic electrolyses. The electrolyses were carried out under different experimental conditions by using an impinging-jet flow cell inserted in a hydraulic circuit in a closed

Michele Mascia; Annalisa Vacca; Anna Maria Polcaro; Simonetta Palmas; Jesus Rodriguez Ruiz; Anna Da Pozzo

2010-01-01

316

Mineralization of clofibric acid by electrochemical advanced oxidation processes using a boron-doped diamond anode and Fe 2+ and UVA light as catalysts  

Microsoft Academic Search

This work shows that aqueous solutions of clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid), the bioactive metabolite of various lipid-regulating drugs, up to saturation at pH 3.0 are efficiently and completely degraded by electrochemical advanced oxidation processes such as electro-Fenton and photoelectro-Fenton with Fe2+ and UVA light as catalysts using an undivided electrolytic cell with a boron-doped diamond (BDD) anode and an O2-diffusion

Ignasi Sirés; Francesc Centellas; José Antonio Garrido; Rosa María Rodríguez; Conchita Arias; Pere-Lluís Cabot; Enric Brillas

2007-01-01

317

Degradation of Acid Orange 7 by electrochemically generated •OH radicals in acidic aqueous medium using a boron-doped diamond or platinum anode: A mechanistic study  

Microsoft Academic Search

A comparative study of the degradation of Acid Orange 7 (AO 7) aqueous solutions in acidic medium of pH 3.0 by electro-Fenton process using Pt or boron-doped diamond (BDD) anode was reported. The oxidative degradation of AO 7 by electrochemically generated hydroxyl radicals follows a pseudo-first order kinetic with a similar rate constant with BDD or Pt anode. The absolute

Samiha Hammami; Nizar Bellakhal; Nihal Oturan; Mehmet A. Oturan; Mohamed Dachraoui

2008-01-01

318

Mineralization of desmetryne by electrochemical advanced oxidation processes using a boron-doped diamond anode and an oxygen-diffusion cathode  

Microsoft Academic Search

The mineralization of acidic aqueous solutions of the herbicide desmetryne has been studied by electrochemical advanced oxidation processes (EAOPs) such as anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF) with UVA light. Electrolyses were conducted in an open and cylindrical cell with a boron-doped diamond (BDD) anode and an O2-diffusion cathode for H2O2 generation. The main oxidizing

Núria Borràs; Conchita Arias; Ramon Oliver; Enric Brillas

2011-01-01

319

The improvement of boron-doped diamond anode system in electrochemical degradation of p-nitrophenol by zero-valent iron  

Microsoft Academic Search

Boron-doped diamond (BDD) electrodes are promising anode materials in electrochemical treatment of wastewaters containing bio-refractory organic compounds due to their strong oxidation capability and remarkable corrosion stability. In order to further improve the performance of BDD anode system, electrochemical degradation of p-nitrophenol were initially investigated at the BDD anode in the presence of zero-valent iron (ZVI). The results showed that

Xiuping Zhu; Jinren Ni

320

Conduction processes in boron- and nitrogen-doped diamond-like carbon films prepared by mass-separated ion beam deposition  

Microsoft Academic Search

Boron- and nitrogen-doped diamond-like amorphous carbon (DLC) films were prepared by alternating direct deposition of low energy mass-separated 12C+ and dopant ions. Concentration vs. depth profiles for N and B dopants were determined by neutron depth profiling. The measured current-voltage characteristics of these films, which were deposited on polished stainless steel, are explained best by Frenkel-Poole emission for high electric

C. Ronning; U. Griesmeier; M. Gross; H. C. Hofsäss; R. G. Downing; G. P. Lamaze

1995-01-01

321

Morphological and microstructural stability of boron-doped diamond thin film electrodes in an acidic chloride medium at high anodic current densities  

Microsoft Academic Search

Boron-doped diamond thin films have been examined before and after high-current-density electrolysis to investigate the morphological and microstructural stability of this new electrode material. The diamond thin films were used to generate chlorine from a solution of 1.0 M HNOâ + 2.0 M NaCl at current densities of 0.05 and 0.5 A\\/cm² for times up to 20 h. Comparative studies

Qingyun Chen; M. C. Granger; T. E. Lister; G. M. Swain

1997-01-01

322

Is the boron-doped diamond electrode a suitable substitute for mercury in pesticide analyses? A comparative study of 4-nitrophenol quantification in pure and natural waters  

Microsoft Academic Search

A comparison between the analytical performance of a hanging mercury drop electrode (HMDE) and a boron-doped diamond (BDD) electrode for the quantification of 4-nitrophenol (4-NP) in spiked pure and natural waters is reported in this work. Square wave voltammetry (SWV) was chosen as the electroanalytical technique and Britton–Robinson buffer as the electrolyte. For the reduction process, the quantification limits varied

Valber A. Pedrosa; Lucia Codognoto; Sergio A. S. Machado; Luis A. Avaca

2004-01-01

323

Relative deactivation of boron-doped diamond (BDD) and glassy carbon (GC) electrodes in different electrolyte media containing substituted phenols – Voltammetric and surface morphologic studies  

Microsoft Academic Search

The relative deactivation of boron-doped diamond (BDD) and glassy carbon (GC) electrodes during the anodic oxidation of three different substituted phenols namely 2,6-dichlorophenol (DCP), 2,6-dimethylphenol (DMP) and 2,6-dimethoxyphenol (DMeoP) in aqueous acidic, acidic methanol and neutral\\/acidic microemulsion media were investigated using cyclic voltammetry (CV). Voltammetric analysis reveals that the anodic potential limit for the BDD electrode is higher than the

M. Narmadha; M. Noel; V. Suryanarayanan

2011-01-01

324

A facile route to n-type TiO(2)-nanotube/p-type boron-doped-diamond heterojunction for highly efficient photocatalysts.  

PubMed

Anatase TiO(2) nanotube (TiNT) arrays have been fabricated on a p-type boron-doped diamond substrate by a liquid phase deposition method using a ZnO nanorod template. The n-type TiNT/p-type diamond heterojunction structures which are realized show significantly enhanced photocatalytic activities with good recyclable behavior, with respect to the cases of sole TiNTs. PMID:20424751

Yuan, Jvjun; Li, Hongdong; Gao, Shiyong; Lin, Yanhong; Li, Haiyan

2010-03-30

325

Electrochemical oxidation of benzoic acid in water over boron-doped diamond electrodes: Statistical analysis of key operating parameters, kinetic modeling, reaction by-products and ecotoxicity  

Microsoft Academic Search

The electrochemical oxidation of benzoic acid over boron-doped diamond electrodes was studied. Experiments were conducted in a flow-through electrolytic cell at current intensities ranging from 11 to 24A, an electrolyte concentration of 0.05M and initial substrate concentrations ranging from 16 to 185mg L?1. Liquid chromatography (LC) coupled to diode array detector was employed to follow benzoic acid concentration profiles, while

Theodora Velegraki; George Balayiannis; Evan Diamadopoulos; Alexandros Katsaounis; Dionissios Mantzavinos

2010-01-01

326

Bulk-bronzied graphites for plasma-facing components in ITER (International Thermonuclear Experimental Reactor)  

Microsoft Academic Search

Newly developed bulk-boronized graphites and boronized C-C composites with a total boron concentration ranging from 1 wt % to 30 wt % have been evaluated as plasma-facing component materials for the International Thermonuclear Experimental Reactor (ITER). Bulk-boronized graphites have been bombarded with high-flux deuterium plasmas at temperatures between 200 and 1600°C. Plasma interaction induced erosion of bulk-boronized graphites is observed

Y. Hirooka; R. W. Conn; R. Doerner; M. Khandagle; R. Causey; K. Wilson; D. Croessmann; J. Whitley; D. Holland; G. Smolik; T. Matsuda; T. Sogabe

1990-01-01

327

Studies on distribution of element contents in transient layer at interface between boron-doped diamond film electrode and tantalum substrate  

NASA Astrophysics Data System (ADS)

The boron-doped diamond film (BDD) grown on tantalum (Ta) substrate as an electrode (BDD/Ta) was prepared by hot filament chemical vapor deposition method. The experimental results demonstrated that our BDD/Ta had high current efficiency, strong ability to degrade wastewater, good corrosion stability and long lifetime. These excellent characteristics of BDD/Ta have been explained in terms of Rutherford backscattering (RBS) experiments. RBS investigation revealed that the continuous transient layer at the interface between boron-doped diamond film and Ta-substrate was formed and the microstructure of the continuous transient layer given by the continuous distribution of all element contents at the interface was obtained. The thicknesses of boron-doped diamond film and the continuous transient layer were about equal to 8000 × 10 15 atoms/cm 2 and 5800 × 10 15 atoms/cm 2, respectively. The formation of the continuous transient layer at the interface can eliminate the mismatch of thermal expansion coefficients (TEC) at the interface and only lead to the slow change of TEC because of the continuous distribution of element contents of the film and substrate in the transient layer at the interface. Thus, there is no residual stress to concentrate on the interface and the stress-corrosion delamination of the film disappears. Therefore, the corrosion stability and lifetime of BDD/Ta increase and last well, that have been verified by X-ray diffraction (XRD) experiments.

Liang, Jiachang; Gao, Chengyao; Zhang, Liping; Jiang, Lihui; Yang, Zhengquan; Wang, Zhiping; Ji, Chaohui; Le, Xiaoyun; Rong, Cuihua; Zhang, Jian

2011-05-01

328

Layered structure of anodic SiO{sub 2} films doped with phosphorus or boron  

SciTech Connect

It is shown that anodic silicon oxide films deposited by reanodization (repeated anodic oxidation) of p- and n-type silicon in phosphate (1.5 M H{sub 3}PO{sub 4}), borate (1.5 M H{sub 3}BO{sub 3}), and nitrate (0.04 M NH{sub 4}NO{sub 3}) electrolytes based on tetrahydrofurfuryl alcohol have a three- or four-layer structure both before and after high-temperature annealing. It is assumed that this circumstance accounts for the nonuniform distribution of phosphorus and boron across the thickness of anodic SiO{sub 2}.

Mileshko, L. P., E-mail: mil@fib.tsure.ru [Southern Federal University, Technological Institute (Russian Federation)

2009-12-15

329

Deposition temperature independent excellent passivation of highly boron doped silicon emitters by thermal atomic layer deposited Al2O3  

NASA Astrophysics Data System (ADS)

In this work, we demonstrate that by using H2O based thermal atomic layer deposited (ALD) Al2O3 films, excellent passivation (emitter saturation current density of ~28 fA/cm2) on industrial highly boron p+-doped silicon emitters (sheet resistance of ~62 ?/sq) can be achieved. The surface passivation of the Al2O3 film is activated by a fast industrial high-temperature firing step identical to the one used for screen printed contact formation. Deposition temperatures in the range of 100-300 °C and peak firing temperatures of ~800 °C (set temperature) are investigated, using commercial-grade 5'' Cz silicon wafers (~5 ? cm n-type). It is found that the level of surface passivation after activation is excellent for the whole investigated deposition temperature range. These results are explained by advanced computer simulations indicating that the obtained emitter saturation current densities are quite close to their intrinsic limit value where the emitter saturation current is solely ruled by Auger recombination. The process developed is industrially relevant and robust.

Liao, Baochen; Stangl, Rolf; Ma, Fajun; Hameiri, Ziv; Mueller, Thomas; Chi, Dongzhi; Aberle, Armin G.; Bhatia, Charanjit S.; Hoex, Bram

2013-09-01

330

Electrochemical Sensing and Assessment of Parabens in Hydro-Alcoholic Solutions and Water Using a Boron-Doped Diamond Electrode  

PubMed Central

In this paper, the electrochemical behaviour of several parabens preservatives, i.e. esters of p-hydroxybenzoic acid, methyl-, ethyl- and propyl-4-hydroxybenzoates as methyl-, ethyl- and propyl-parabens (MB, EB, and PB), has been investigated at a commercial boron-doped diamond electrode (BDDE), especially in the anodic potential range, in both hydro-alcoholic and aqueous media. The cyclic voltammetric and chronoamperometric measurements yielded calibration plots with very good linearity (R2 between 0.990 and 0.998) and high sensitivity, useful for detection and analytical applications. The determination of the characteristics of individual compounds, of an “overall paraben index”, the assessment of the stability and the saturation solubility in water, and the amperometric sensing and determination in double distilled, tap and river water matrix of the relatively slightly soluble investigated parabens have been carried out using electrochemical alternative. Estimated water solubility was correlated with the octanol-water partition coefficient. Several ideas regarding stability and persistence of the presumptive eco-toxic investigated preservatives in the environment or water systems have been adjacently discussed.

Radovan, Ciprian; Cinghita, Dan; Manea, Florica; Mincea, Manuela; Cofan, Codruta; Ostafe, Vasile

2008-01-01

331

Structural, Electronic, and Magnetic Features of Platinum Alloy Strings Templated on A Boron-Doped Carbon Nanotube  

SciTech Connect

We present density-functional-theory calculations of structural, electronic, and magnetic properties of platinum-alloy strings templated on a boron-doped single-wall carbon nanotube (6,6) model, B-SWCNT(6,6). Our calculations show that the alloy strings demonstrate strong molecular recognition, forming well-defined covalent bonds with the substrate and lead to the self-assembly of stable monatomic chains. The electronic and magnetic features of the Pt-alloy string/B-SWCNT(6,6)composite systems are mainly controlled by the presence of a magnetic alloying element (i.e., Fe, Co, and Ru). By changing the composition of the Pt alloy, the easy magnetization axis of the system can oscillate between the directions parallel and perpendicular to the tube axis. Our studies suggest that pure transition-metal (TM) or TM-alloy strings anchored on a substrate via strong molecular interactions can still possess sizable magnetic anisotropy due to spin-orbital coupling effects.

An, Wei; Turner, C. H.

2010-05-25

332

Electrophoretic analysis of biomarkers using capillary modification with gold nanoparticles embedded in a polycation and boron doped diamond electrode.  

PubMed

Field-amplified sample stacking using a fused silica capillary coated with gold nanoparticles (AuNPs) embedded in poly(diallyl dimethylammonium) chloride (PDDA) has been investigated for the electrophoretic separation of indoxyl sulfate, homovanillic acid (HVA), and vanillylmandelic acid (VMA). AuNPs (27 nm) exhibit ionic and hydrophobic interactions, as well as hydrogen bonding with the PDDA network to form a stable layer on the internal wall of the capillary. This approach reverses electro-osmotic flow allowing for fast migration of the analytes while retarding other endogenous compounds including ascorbic acid, uric acid, catecholamines, and indoleamines. Notably, the two closely related biomarkers of clinical significance, HVA and VMA, displayed differential interaction with PDDA-AuNPs which enabled the separation of this pair. The detection limit of the three analytes obtained by using a boron doped diamond electrode was approximately 75 nM, which was significantly below their normal physiological levels in biological fluids. This combined separation and detection scheme was applied to the direct analysis of these analytes and other interfering chemicals including uric and ascorbic acids in urine samples without off-line sample treatment or preconcentration. PMID:20704378

Zhou, Lin; Glennon, Jeremy D; Luong, John H T

2010-08-15

333

Treatment of ink effluents from flexographic printing by lime precipitation and boron-doped diamond (BDD) electrochemical oxidation.  

PubMed

Effluent treatment from flexographic printing was investigated by precipitation/coagulation and electrochemical oxidation over boron-doped diamond electrodes. Precipitation with 3 g/L of lime led to complete removal of effluent turbidity (initial value of about 410 NTU) but only about 20% chemical oxygen demand (COD) decrease (initial value of about 1,900 mg/L). Higher lime dosages (up to 15 g/L) had no effect on separation. On the other hand, coagulation with alum in the range 0.05-1 mM failed to enhance the extent of solids separation achieved by gravity settling alone (i.e. about 60%). Preliminary electrochemical oxidation experiments in the presence of sulphuric acid as supporting electrolyte showed that treatment performance (in terms of COD removal and decrease in sample absorbance at 300 nm) increased with increasing applied current. The latter was more efficiently utilized at shorter treatment times and lower currents with efficiency reaching 30%. Following lime precipitation, the effluent was electrochemically oxidized at alkaline conditions for 360 min yielding 64% absorbance reduction and 50% COD removal (this corresponds to 60% overall COD removal for the combined process). The rather low electrochemical treatment performance may be attributed to limestone deposition and fouling of electrodes and other electrochemical reactor components as evidenced by the gradual drop in conductivity/current throughout the operation. PMID:19923752

Diamadopoulos, Evan; Barndõk, Helen; Xekoukoulotakis, Nikolaos P; Mantzavinos, Dionissios

2009-01-01

334

Electrochemical degradation of a real textile effluent using boron-doped diamond or ?-PbO2 as anode.  

PubMed

Constant current electrolyses are carried out in a filter-press reactor using a boron-doped diamond (Nb/BDD) or a Ti-Pt/?-PbO(2) anode, varying current density (j) and temperature. The degradation of the real textile effluent is followed by its decolorization and chemical oxygen demand (COD) abatement. The effect of adding NaCl (1.5 g L(-1)) on the degradation of the effluent is also investigated. The Nb/BDD anode yields much higher decolorization (attaining the DFZ limit) and COD-abatement rates than the Ti-Pt/?-PbO(2) anode, at any experimental condition. The best conditions are j = 5 mA cm(-2) and 55 °C, for the system's optimized hydrodynamic conditions. The addition of chloride ions significantly increases the decolorization rate; thus a decrease of more than 90% of the effluent relative absorbance is attained using an applied electric charge per unit volume of the electrolyzed effluent (Q(ap)) of only about 2 kA h m(-3). Practically total abatement of the effluent COD is attained with the Nb/BDD anode using a Q(ap) value of only 7 kA h m(-3), with an energy consumption of about 30 kW h m(-3). This result allows to conclude that the Nb/BDD electrode might be an excellent option for the remediation of textile effluents. PMID:21742436

Aquino, José M; Pereira, Gabriel F; Rocha-Filho, Romeu C; Bocchi, Nerilso; Biaggio, Sonia R

2011-07-13

335

Electrochemical incineration of cresols: a comparative study between PbO2 and boron-doped diamond anodes.  

PubMed

The electrooxidation of aqueous solutions containing 5mM of o-, m- and p-cresol at pH 4.0 has been investigated using a flow filter-press reactor with a boron-doped diamond (BDD) under galvanostatic electrolysis. All cresols are degraded at similar rate up to attaining overall mineralization. Comparable treatment of the m-cresol effluent on PbO(2) leads to partial electrochemical incineration. However, this pollutant is more rapidly removed with PbO(2) than with BDD. The decay kinetics of all cresols follows a pseudo-first-order reaction. Aromatic intermediates such as 2-methylhydroquinone and 2-methyl-p-benzoquinone and carboxylic acids such as maleic, fumaric, pyruvic, malonic, tartronic, glycolic, glyoxylic, acetic, oxalic and formic, have been identified and followed during the m-cresol treatment by chromatographic techniques. From these oxidation by-products, a plausible reaction sequence for m-cresol mineralization on both anodes is proposed. The energy consumption for the corresponding electrochemical process is also calculated. PMID:19118859

Flox, Cristina; Arias, Conchita; Brillas, Enric; Savall, André; Groenen-Serrano, Karine

2008-12-31

336

Oxidation of carbon monoxide, hydrogen peroxide and water at a boron doped diamond electrode: the competition for hydroxyl radicals.  

PubMed

Boron doped diamond (BDD) electrodes have an extremely high over-voltage for oxygen evolution from water, which favours its use in oxidation processes of other compounds at high potentials. We used a rotating ring disc (RRDE) assembly and differential electrochemical mass spectrometry (DEMS) in order to monitor the consumption or the production of species in the course of the electrode processes. By intercepting the intermediate of the electrochemical water oxidation with chemical reactions we demonstrate clearly, albeit indirectly, that in the water oxidation process at BDD above 2.5 V the first step is the formation of ?OH radicals. The electro-oxidation of CO to CO2 at BDD electrodes proceeds only via a first attack by ?OH radicals followed by a further electron transfer to the electrode. At potentials below the onset of oxygen evolution from water, H2O2 is oxidised by a direct electron transfer to the BDD electrode, while at higher potentials, two different reactions paths compete for the ?OH radicals formed in the first electron transfer from water: one, where these ?OH radicals react with each other followed by further electron transfers leading to O2 on the one hand and one, where ?OH radicals react with other species like H2O2 or CO with subsequent electron transfers on the other hand. PMID:23422949

Kisacik, Izzet; Stefanova, Ana; Ernst, Siegfried; Baltruschat, Helmut

2013-04-01

337

Electrochemical boron-doped diamond film microcells micromachined with femtosecond laser: application to the determination of water framework directive metals.  

PubMed

Planar electrochemical microcells were micromachined in a microcrystalline boron-doped diamond (BDD) thin layer using a femtosecond laser. The electrochemical performances of the new laser-machined BDD microcell were assessed by differential pulse anodic stripping voltammetry (DPASV) determinations, at the nanomolar level, of the four heavy metal ions of the European Water Framework Directive (WFD): Cd(II), Ni(II), Pb(II), Hg(II). The results are compared with those of previously published BDD electrodes. The calculated detection limits are 0.4, 6.8, 5.5, and 2.3 nM, and the linearities go up to 35, 97, 48, and 5 nM for, respectively, Cd(II), Ni(II) Pb(II), and Hg(II). The detection limits meet with the environmental quality standard of the WFD for three of the four metals. It was shown that the four heavy metals could be detected simultaneously in the concentration ratio usually measured in sewage or runoff waters. PMID:22510091

Sbartai, Amel; Namour, Philippe; Errachid, Abdelhamid; Krej?i, Jan; Šejnohová, Romana; Renaud, Louis; Hamlaoui, Mohamed Larbi; Loir, Anne-Sophie; Garrelie, Florence; Donnet, Christophe; Soder, Hervé; Audouard, Eric; Granier, Julien; Jaffrezic-Renault, Nicole

2012-05-11

338

Simultaneous detection of monoamine and purine molecules using high-performance liquid chromatography with a boron-doped diamond electrode.  

PubMed

A recently available boron-doped diamond (BDD) working electrode has been developed for use with high-performance liquid chromatography (HPLC) to aid in the detection of molecules with high redox potentials. In this work, we developed a method using a commercially available BDD working electrode for detecting neurotransmitters from two different families with large oxidation potential differences, namely, dopamine (DA) and adenosine (Ado). Hydrodynamic voltammograms were constructed for DA and Ado, and the optimal potentials for the detection of DA and Ado were determined to be +740 and +1200 mV versus a palladium reference electrode, respectively. A working potential of +840 mV was chosen, and the detection range achieved with the BDD electrode for DA and Ado was from low nanomolar to high millimolar levels. To determine the practical function of the BDD electrode, tissue content was analyzed for seven monoamine and two purine molecules, which were resolved in a single run in less than 28 min. Our results demonstrate that the BDD electrode is sensitive and robust enough to detect monoamine and purine molecules from frontal cortex and striatal mouse samples. Using a BDD electrode opens the possibility of exploring multiple classes of neurotransmitters in a single run using electrochemical detection to probe their interactions. PMID:23815757

Birbeck, Johnna A; Mathews, Tiffany A

2013-07-10

339

Square-wave voltammetric determination of bezafibrate in pharmaceutical formulations using a cathodically pretreated boron-doped diamond electrode.  

PubMed

The determination of bezafibrate (BZF) using square-wave voltammetry (SWV) and a cathodically pretreated boron-doped diamond electrode is proposed. Cyclic voltammetry results showed one irreversible oxidation peak for BZF at 1.20 V (vs. Ag/AgCl (3.0 mol L(-1) KCl)) in a 0.04 mol L(-1) Britton-Robinson (BR) buffer solution (pH 2.0). Under optimized SWV conditions, a linear analytical curve is obtained for the BZF concentration range 0.10-9.1 ?mol L(-1) in the BR buffer solution (pH 2.0), with a detection limit of 0.098 ?mol L(-1). The obtained recoveries range from 93.4 to 108%. The proposed novel method was successfully applied in the determination of the BZF content in several pharmaceutical formulations (tablets) and the results are in close agreement (at a 95% confidence level) with those obtained using a comparative spectrophotometric method. PMID:23200378

Ardila, Jorge Armando; Sartori, Elen Romão; Rocha-Filho, Romeu C; Fatibello-Filho, Orlando

2012-10-16

340

Experimental approach to controllably vary protein oxidation while minimizing electrode adsorption for boron-doped diamond electrochemical surface mapping applications.  

PubMed

Oxidative protein surface mapping has become a powerful approach for measuring the solvent accessibility of folded protein structures. A variety of techniques exist for generating the key reagent (i.e., hydroxyl radicals) for these measurements; however, these approaches range significantly in their complexity and expense of operation. This research expands upon earlier work to enhance the controllability of boron-doped diamond (BDD) electrochemistry as an easily accessible tool for producing hydroxyl radicals in order to oxidize a range of intact proteins. Efforts to modulate the oxidation level while minimizing the adsorption of protein to the electrode involved the use of relatively high flow rates to reduce protein residence time inside the electrochemical flow chamber. Additionally, a different cell activation approach using variable voltage to supply a controlled current allowed us to precisely tune the extent of oxidation in a protein-dependent manner. In order to gain perspective on the level of protein adsorption onto the electrode surface, studies were conducted to monitor protein concentration during electrolysis and gauge changes in the electrode surface between cell activation events. This report demonstrates the successful use of BDD electrochemistry for greater precision in generating a target number of oxidation events upon intact proteins. PMID:23210708

McClintock, Carlee S; Hettich, Robert L

2012-12-17

341

Quasi-real time quantification of uric acid in urine using boron doped diamond microelectrode with in situ cleaning.  

PubMed

We report herein an innovative electrochemical (EC) technique based on boron doped diamond (BDD) microelectrodes which enable the fast determination of uric acid (UA) concentrations in urine. On the basis of fast cyclic voltammetry (CV), the technique was assessed in human urine samples and compared successfully using routine spectrophotometric diagnosis. The approach relies on the use of BDD's superior properties such as low background current, low adsorption of species, long-term stability, and antifouling capabilities using electrochemical reactivation. Moreover, the article also describes an in situ activation technique, where the electrodes were reactivated within human urine, thereby opening the way toward automatic quantification of UA with in situ cleaning. The time taken to quantify UA concentration and cleaning remains below 0.5 s. Two analytic models were derived, based on different concentrations of ascorbic acid (AA) and uric acid, consisting of 2 s order calibration curves. Solving the second order equation enables the direct estimation of UA concentration, and values demonstrated good accuracy when compared with spectrophotometric measurements. PMID:23126450

Kiran, Raphael; Scorsone, Emmanuel; Mailley, Pascal; Bergonzo, Philippe

2012-11-13

342

Determination of vanillin in commercial food product by adsorptive stripping voltammetry using a boron-doped diamond electrode.  

PubMed

A method for the determination of food additive vanillin was developed by adsorptive stripping voltammetry. Its determination was carried out at the anodically pre-treated boron-doped diamond electrode in aqueous solutions. Using square-wave stripping mode, the compound yielded a well-defined voltammetric response in phosphate buffer, pH 2.5 at +1.14 V (vs. Ag/AgCl) (a pre-concentration step being carried out at open-circuit condition for 60s). A linear calibration graph was obtained in the concentration range of 0.5-15.0 ?g mL(-1) (3.3×10(-6)-9.8×10(-5) mol L(-1)) with a detection limit of 0.024 ?g mL(-1) (1.6×10(-7) mol L(-1)). As an example, the practical applicability of the proposed method was tested for the determination of this flavouring agent in commercial pudding powder of Keshkule (Turkish milk pudding with almond flour). PMID:23870896

Yard?m, Yavuz; Gülcan, Mehmet; ?entürk, Zühre

2013-05-03

343

Destination of organic pollutants during electrochemical oxidation of biologically-pretreated dye wastewater using boron-doped diamond anode.  

PubMed

Electrochemical oxidation of biologically-pretreated dye wastewater was performed in a boron-doped diamond (BDD) anode system. After electrolysis of 12h, the COD was decreased from 532 to 99 mg L(-1) (<100 mg L(-1), the National Discharge Standard of China). More importantly, the destination of organic pollutants during electrochemical oxidation process was carefully investigated by molecular weight distribution measurement, resin fractionation, ultraviolet-visible spectroscopy, HPLC and GC-MS analysis, and toxicity test. As results, most organic pollutants were completely removed by electrochemical oxidation and the rest was primarily degraded to simpler compounds (e.g., carboxylic acids and short-chain alkanes) with less toxicity, which demonstrated that electrochemical oxidation of biologically-pretreated dye wastewater with BDD anode was very effective and safe. Especially, the performance of BDD anode system in degradation of large molecular organics such as humic substances makes it very promising in practical applications as an advanced treatment of biologically-pretreated wastewaters. PMID:21377794

Zhu, Xiuping; Ni, Jinren; Wei, Junjun; Xing, Xuan; Li, Hongna

2011-03-05

344

The effect of SiO2-doped boron nitride multiple coatings on mechanical properties of quartz fibers  

NASA Astrophysics Data System (ADS)

SiO2-doped boron nitride multiple coatings (SiO2/BN multiple coatings) were prepared on quartz fibers surface at 700 °C. Single fiber tensile test was employed to evaluate fiber tensile strength; Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were employed to evaluate morphology and structure of the fibers. Fiber tensile test results indicated that the strength of quartz fibers with SiO2/BN multiple coatings was about twice of the fibers with BN coatings and original fibers which were heated at 700 °C for 10 h. The SiO2/BN multiple coatings would provide compressive stress on quartz fibers, which would help to seal the defects on fiber surface. Furthermore, TEM images showed that the nano-SiO2 powders crystallized in advance of quartz fibers, which would suppress crystallization of quartz fibers and reduce damage from crystallization. Thus, nano-SiO2 powders would help to keep mechanical properties of quartz fibers.

Zheng, Yu; Wang, Shubin

2012-01-01

345

Doping of SiC by Implantation of Boron and Aluminum  

NASA Astrophysics Data System (ADS)

Experimental studies on aluminum (Al) and boron (B) implantation in 4H/6H SiC are reported; the implantation is conducted at room temperature or elevated temperatures (500 to 700 °C). Both Al and B act as shallow acceptors in SiC. The ionization energy of these acceptors, the hole mobility and the compensation in the implanted layers are obtained from Hall effect investigations. The degree of electrical activity of implanted Al/B atoms is determined as a function of the annealing temperature. Energetically deep centers introduced by the Al+/B+ implantation are investigated. The redistribution of implanted Al/B atoms subsequent to anneals and extended lattice defects are monitored. The generation of the B-related D-center is studied by coimplantation of Si/B and C/B, respectively.

Troffer, T.; Schadt, M.; Frank, T.; Itoh, H.; Pensl, G.; Heindl, J.; Strunk, H. P.; Maier, M.

1997-07-01

346

Simultaneous electrochemical determination of nitrate and nitrite in aqueous solution using Ag-doped zeolite-expanded graphite-epoxy electrode.  

PubMed

In this work a new electrochemical sensor based on an Ag-doped zeolite-expanded graphite-epoxy composite electrode (AgZEGE) was evaluated as a novel alternative for the simultaneous quantitative determination of nitrate and nitrite in aqueous solutions. Cyclic voltammetry was used to characterize the electrochemical behavior of the electrode in the presence of individual or mixtures of nitrate and nitrite anions in 0.1M Na(2)SO(4) supporting electrolyte. Linear dependences of current versus nitrate and nitrite concentrations were obtained for the concentration ranges of 1-10mM for nitrate and 0.1-1mM for nitrite using cyclic voltammetry (CV), chronoamperometry (CA), and multiple-pulsed amperometry (MPA) procedures. The comparative assessment of the electrochemical behavior of the individual anions and mixtures of anions on this modified electrode allowed determining the working conditions for the simultaneous detection of the nitrite and nitrate anions. Applying MPA allowed enhancement of the sensitivity for direct and indirect nitrate detection and also for nitrite detection. The proposed sensor was applied in tap water samples spiked with known nitrate and nitrite concentrations and the results were in agreement with those obtained by a comparative spectrophotometric method. This work demonstrates that using multiple-pulse amperometry with the Ag-doped zeolite-expanded graphite-epoxy composite electrode provides a real opportunity for the simultaneous detection of nitrite and nitrate in aqueous solutions. PMID:21035645

Manea, Florica; Remes, Adriana; Radovan, Ciprian; Pode, Rodica; Picken, Stephen; Schoonman, Joop

2010-09-20

347

Study of High Resistance Inorganic Coatings on Graphite Fibers.  

National Technical Information Service (NTIS)

Coatings made of boron, silicon carbide, silica, and silica-like materials were studied to determine their ability to increase resistance of graphite fibers. The most promising results were attained by chemical vapor depositing silicon carbide on graphite...

F. S. Galasso R. D. Veltri D. A. Scola

1979-01-01

348

Hydrogen Diffusion and Microstructure in Undoped and Boron-Doped Hydrogenated Amorphous Silicon: AN IR and SIMS STUDY*  

NASA Astrophysics Data System (ADS)

Hydrogenated amorphous silicon (a-Si:H) prepared by rf sputtering of a polycrystalline Si target at various rf powers 50 <= P <= 550 W (0.27-2.97 W/cm^2), target to substrate distance 1 <= d <= 2^{' '}, and varying hydrogen partial pressures. Doping was accomplished by introducing diborane (B_2H_6) in the plasma. Hydrogen diffusion was studied from the depth profiles obtained from the SIMS on multilayered a -Si:H/a-Si:(H,D)/a-Si:H samples. The properties of the samples were characterized by IR absorption, optical gap measurements and ESR. IR yielded quantitative and qualitative information total hydrogen content and the nature of hydrogen bonding, respectively. Hence the hydrogen microstructure of the samples could be varied in a systematic manner and monitored from the hydrogen vibrational modes. The ESR gave information on the number of paramagnetic defects per unit volume in the samples. The IR absorption of both as-deposited and annealed samples were closely monitored and the results clearly demonstrate a strong correlation between hydrogen diffusion and its microstructure. It is shown that microvoids in a-Si:H play a critical role in the process of diffusion by inducing deep hydrogen trapping sites that render them immobile. Consequently, as the microvoid density increases beyond a critical density (corresponding to N_ {rm d} >= 6.5 at. %) hydrogen diffusion is totally quenched. The diffusion results are discussed both in the context of multiple trapping transport of hydrogen in an exponential distribution of trapping sites and the floating bond model. As expected the hydrogen diffusion in boron-doped a-Si:H is faster than undoped material by a few orders of magnitude. The diffusion results have shown a significant departure from the power-law time dependence upon prolonged annealing. Such a departure has not been reported before. It is suspected that this deviation is caused by structural relaxations of the silicon network. ftn*DOE Report IS -T-1506. This work was performed under contract No W-7405 -Eng-82 with US Department of Energy.

Mitra, Saibal

349

Electrochemical combustion of herbicide mecoprop in aqueous medium using a flow reactor with a boron-doped diamond anode.  

PubMed

The anodic oxidation of 1.8l of solutions with mecoprop (2-(4-chloro-2-methylphenoxy)-propionic acid or MCPP) up to 0.64 g l(-1) in Na2SO4 as background electrolyte within the pH range 2.0-12.0 has been studied using a flow plant containing a one-compartment filter-press electrolytic reactor with a boron-doped diamond (BDD) anode and a stainless steel cathode, both of 20-cm2 area. Electrolyses carried out in batch under steady conditions and operating at constant current density between 50 and 150 mA cm(-2) always yield complete mineralization due to the great concentration of hydroxyl radical generated at the BDD anode. The degradation rate is practically independent of pH and Na2SO4 concentration, but it becomes faster with increasing MCPP concentration, current density, temperature and liquid flow rate. The effect of these parameters on current efficiency and energy cost has also been investigated. Generated weak oxidants such as H2O2 and peroxodisulfate ion have little influence on the mineralization process. The kinetics for the herbicide decay follows a pseudo first-order reaction with a higher rate constant when current density increases. Aromatic products such as 4-chloro-o-cresol, 2-methylhydroquinone and 2-methyl-p-benzoquinone, and generated carboxylic acids such as maleic, fumaric, lactic, pyruvic, tartronic, acetic and oxalic, have been identified as intermediates by chromatographic techniques. The initial chlorine is completely released in the form of chloride ion, which is slowly oxidized to Cl2 at the BDD anode. A reaction pathway for MCPP mineralization involving all products detected is proposed. PMID:16516266

Flox, Cristina; Cabot, Pere Lluís; Centellas, Francesc; Garrido, José Antonio; Rodríguez, Rosa María; Arias, Conchita; Brillas, Enric

2006-03-03

350

Mineralization of the recalcitrant oxalic and oxamic acids by electrochemical advanced oxidation processes using a boron-doped diamond anode.  

PubMed

Oxalic and oxamic acids are the ultimate and more persistent by-products of the degradation of N-aromatics by electrochemical advanced oxidation processes (EAOPs). In this paper, the kinetics and oxidative paths of these acids have been studied for several EAOPs using a boron-doped diamond (BDD) anode and a stainless steel or an air-diffusion cathode. Anodic oxidation (AO-BDD) in the presence of Fe(2+) (AO-BDD-Fe(2+)) and under UVA irradiation (AO-BDD-Fe(2+)-UVA), along with electro-Fenton (EF-BDD), was tested. The oxidation of both acids and their iron complexes on BDD was clarified by cyclic voltammetry. AO-BDD allowed the overall mineralization of oxalic acid, but oxamic acid was removed much more slowly. Each acid underwent a similar decay in AO-BDD-Fe(2+) and EF-BDD, as expected if its iron complexes were not attacked by hydroxyl radicals in the bulk. The faster and total mineralization of both acids was achieved in AO-BDD-Fe(2+)-UVA due to the high photoactivity of their Fe(III) complexes that were continuously regenerated by oxidation of their Fe(II) complexes. Oxamic acid always released a larger proportion of NH(4)(+) than NO(3)(-) ion, as well as volatile NO(x) species. Both acids were independently oxidized at the anode in AO-BDD, but in AO-BDD-Fe(2+)-UVA oxamic acid was more slowly degraded as its content decreased, without significant effect on oxalic acid decay. The increase in current density enhanced the oxidation power of the latter method, with loss of efficiency. High Fe(2+) contents inhibited the oxidation of Fe(II) complexes by the competitive oxidation of Fe(2+) to Fe(3+). Low current densities and Fe(2+) contents are preferable to remove more efficiently these acids by the most potent AO-BDD-Fe(2+)-UVA method. PMID:21477836

Garcia-Segura, Sergi; Brillas, Enric

2011-03-21

351

Mineralization of Acid Yellow 36 azo dye by electro-Fenton and solar photoelectro-Fenton processes with a boron-doped diamond anode  

Microsoft Academic Search

The degradation of the Acid Yellow 36 (AY36) azo dye is studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF) using a recirculation flow plant with an undivided cell containing a boron-doped diamond anode and an air-diffusion cathode for H2O2 electrogeneration, coupled with a solar photoreactor. A solution of 2.5L with 108mgL?1 of the dye and 0.5mM Fe2+ at pH 3.0

Edgar J. Ruiz; Conchita Arias; Enric Brillas; Aracely Hernández-Ramírez; J. M. Peralta-Hernández

2011-01-01

352

Effect of the mediator in feedback mode-based SECM interrogation of indium tin-oxide and boron-doped diamond electrodes  

Microsoft Academic Search

Indium tin-oxide (ITO) and polycrystalline boron-doped diamond (BDD) have been examined in detail using the scanning electrochemical microscopy technique in feedback mode. For the interrogation of electrodes made from these materials, the choice of mediator has been varied. Using$${\\\\text{Ru}}{\\\\left( {{\\\\text{CN}}} \\\\right)}^{{4 - }}_{{{\\\\text{6 }}{\\\\left( {{\\\\text{aq}}} \\\\right)}}} ,$$ ferrocene methanol (FcMeOH),$${\\\\text{Fe}}{\\\\left( {{\\\\text{CN}}} \\\\right)}^{{{\\\\text{3}} - }}_{{{\\\\text{6 }}{\\\\left( {{\\\\text{aq}}} \\\\right)}}} $$ and$${\\\\text{Ru}}{\\\\left( {{\\\\text{NH}}_{{\\\\text{3}}}

A. K. Neufeld; A. P. O’Mullane

2006-01-01

353

Mercury-free sono-electroanalytical detection of lead in human blood by use of bismuth-film-modified boron-doped diamond electrodes  

Microsoft Academic Search

We report the electroanalytical determination of lead by anodic stripping voltammetry at in-situ-formed, bismuth-film-modified, boron-doped diamond electrodes. Detection limits in 0.1 mol L –1 nitric acid solution of 9.6x10 -8 mol L –1 (0.2 ppb) and 1.1x10 -8 mol L –1 (2.3 ppb) were obtained after 60 and 300 s deposition times, respectively. An acoustically assisted deposition procedure was also investigated and found to result in

Jaanus Kruusma; Craig E. Banks; Richard G. Compton

2004-01-01

354

On the performances of lead dioxide and boron-doped diamond electrodes in the anodic oxidation of simulated wastewater containing the Reactive Orange 16 dye  

Microsoft Academic Search

The performances of the Ti–Pt\\/?-PbO2 and boron-doped diamond (BDD) electrodes in the electrooxidation of simulated wastewaters containing 85mgL?1 of the Reactive Orange 16 dye were investigated using a filter-press reactor. The electrolyses were carried out at the flow rate of 7Lmin?1, at different current densities (10–70mAcm?2), and in the absence or presence of chloride ions (10–70mM NaCl). In the absence

Leonardo S. Andrade; Thiago T. Tasso; Diogo L. da Silva; Romeu C. Rocha-Filho; Nerilso Bocchi; Sonia R. Biaggio

2009-01-01

355

Degradation of the beta-blocker propranolol by electrochemical advanced oxidation processes based on Fenton's reaction chemistry using a boron-doped diamond anode  

Microsoft Academic Search

The electro-Fenton (EF) and photoelectro-Fenton (PEF) degradation of solutions of the beta-blocker propranolol hydrochloride with 0.5mmoldm?3 Fe2+ at pH 3.0 has been studied using a single cell with a boron-doped diamond (BDD) anode and an air diffusion cathode (ADE) for H2O2 electrogeneration and a combined cell containing the above BDD\\/ADE pair coupled in parallel to a Pt\\/carbon felt (CF) cell.

Eloy Isarain-Chávez; Rosa María Rodríguez; José Antonio Garrido; Conchita Arias; Francesc Centellas; Pere Lluís Cabot; Enric Brillas

2010-01-01

356

Degradation of the herbicide 2,4DP by anodic oxidation, electro-Fenton and photoelectro-Fenton using platinum and boron-doped diamond anodes  

Microsoft Academic Search

This paper reports the degradation of 2,4-DP (2-(2,4-dichlorophenoxy)-propionic acid) solutions of pH 3.0 by environmentally friendly electrochemical methods such as anodic oxidation, electro-Fenton and photoelectro-Fenton with a Pt or boron-doped diamond (BDD) anode. In the two latter techniques an O2-diffusion cathode was used and 1.0mM Fe2+ was added to the solution to give hydroxyl radical (OH) from Fenton’s reaction between

Enric Brillas; Miguel Ángel Baños; Marcel Skoumal; Pere Lluís Cabot; José Antonio Garrido; Rosa María Rodríguez

2007-01-01

357

The influence of surface interactions on the reversibility of ferri\\/ferrocyanide at boron-doped diamond thin-film electrodes  

Microsoft Academic Search

The electrochemistry of four redox analytes [Fe(CN)â⁻³⁻⁴, Ru(NHâ)â{sup +2\\/+3}, IrClâ⁻²⁻³, and methyl viologen, MV{sup +2\\/+\\/0}] was investigated at polycrystalline, boron-doped diamond thin-film electrodes before and after anodic polarization and hydrogen plasma treatment. The as-deposited diamond surface is predominantly hydrogen treatment, and quasi-reversible cyclic voltammograms (ÎE{sub p} of 60--80 mV) were observed for all of these couples at 0.1 V\\/s. After

Michael C. Granger; G. M. Swain

1999-01-01

358

Atomistic Modeling for Retardation of Boron Diffusion and Dominant BmInClusters in Pre-doped Silicon  

Microsoft Academic Search

In this paper, we present a simple atomistic model for describing the kinetic Monte Carlo (KMC) evolution of interstitial clusters during boron diffusion. It has been known that clusters generated after ion implantation play a decisive role in the enhanced boron diffusion at the tail region in contrast to the immobile property at the peak region. Our model, which is

Jae-Hyun Yoo; Taeyoung Won; Chi-Ok Hwang; Byeong-Jun Kim

2005-01-01

359

The effect of doping three Al and N atoms on the chemical shielding tensor parameters of the boron phosphide nanotubes: A DFT study  

NASA Astrophysics Data System (ADS)

In this work, an armchair model of the (4,4) boron phosphide nanotubes (BPNTs) with a 1-nm length and consisting of 32 B and 32 P atoms is considered to study the influence of doping three atoms of aluminum in sites of boron (B3AlPNTs) and three atoms of nitrogen in sites of phosphors (BP3NNTs) on the electrostatic structure properties. The mouths of nanotubes are capped by hydrogen atoms in order to saturate the dangling bonds of the boundaries and to decrease the calculation time. The structures of BPNTs, B3AlPNTs and BP3NNTs are optimized by performing the level of density functional theory (DFT) using 6-31G* basis set. The optimized structures are used for calculating the chemical shielding (CS) tensors and nuclear magnetic resonance parameters such as isotropic chemical shielding (CSI) and anisotropic chemical shielding (CSA). The results reveal that in both models of B3AlPNTs and BP3NNTs by doping N atoms the chemical shielding parameters of P and B atoms, which are directly connected to the Al and N atoms decreased and the other sites significantly changed.

Rezaei-Sameti, Mahdi

2012-01-01

360

Factors controlling stripping voltammetry of lead at polycrystalline boron doped diamond electrodes: new insights from high-resolution microscopy.  

PubMed

We report wide-ranging studies to elucidate the factors and issues controlling stripping voltammetry of metal ions on solid electrodes using the well-known Pb/Pb(2+) couple on polycrystalline boron doped diamond (pBDD) as an exemplar system. Notably, high-resolution microscopy techniques have revealed new insights into the features observed in differential pulse anodic stripping voltammetry (DPV-ASV) which provide a deeper understanding of how best to utilize this technique. DPV-ASV was employed in an impinging wall-jet configuration to detect Pb(2+) in the nanomolar to micromolar concentration range at a pBDD macrodisk electrode. The deposition process was driven to produce a grain-independent homogeneous distribution of Pb nanoparticles (NPs) on the electrode surface; this resulted in the observation of narrow stripping peaks. Lower calibration gradients of current or charge versus concentration were found for the low concentrations, correlating with a lower than expected (from consideration of the simple convective-diffusive nature of the deposition process) amount of Pb deposited on the surface. This was attributed to the complex nature of nucleation and growth at solid surfaces in this concentration regime, complicating mass transport. Furthermore, a clear shift negative in the stripping peak potential with decreasing concentration was seen correlating with a change in the size of the deposited NP, suggesting an NP size-dependent redox potential for the Pb/Pb(2+) couple. At high concentrations a nonlinear response was observed, with less Pb detected than expected, in addition to the observation of a second stripping peak. Atomic force microscopy (AFM) and field emission scanning electron microscopy revealed the second peak to be due to a change in deposition morphology from isolated NPs to grain-independent heterogeneous structures comprising both thin films and NPs; the second peak is associated with stripping from the thin-film structures. AFM also revealed a substantial amount of Pb remaining on the surface after stripping at high concentration, explaining the nonlinear relationship between stripping peak current (or charge) and concentration. Finally, the use of an in situ cleaning procedure between each measurement was advocated to ensure a clean Pb-free surface (verified by AFM and X-ray photoelectron spectroscopy analysis) between each run. The studies herein highlight important and complex physicochemical processes involved in the electroanalysis of heavy metals at solid electrodes, such as pBDD, that need to be accounted for when using stripping voltammetry methods. PMID:21214184

Hutton, Laura A; Newton, Mark E; Unwin, Patrick R; Macpherson, Julie V

2011-01-07

361

Electrochemical oxidation of reverse osmosis concentrate on boron-doped diamond anodes at circumneutral and acidic pH.  

PubMed

Electrochemical processes have been widely investigated for degrading organic contaminants present in wastewater. This study evaluated the performance of electrochemical oxidation using boron-doped diamond (BDD) electrodes by forming OH() for the treatment of reverse osmosis concentrate (ROC) from secondary-treated wastewater effluents. Since oxidation by OH() and active chlorine species (HClO/ClO(-)) is influenced by pH, the electrochemical oxidation of ROC was evaluated at controlled pH 6-7 and at pH 1-2 (no pH adjustment). A high concentration of chloride ions in the ROC enhanced the oxidation, and 7-11% of Coulombic efficiency for chemical oxygen demand (COD) removal was achieved with 5.2 Ah L(-1) of specific electrical charge. Complete COD removal was observed after 5.2 and 6.6 Ah L(-1), yet the corresponding dissolved organic carbon (DOC) removal was only 48% (at acidic pH) and 59% (at circumneutral pH). Although a higher operating pH seemed to enhance the participation of OH() in oxidation mechanisms, high concentrations of chloride resulted in the formation of significant concentrations of adsorbable organic chlorine (AOCl) after electrochemical oxidation at both pH. While adsorbable organic bromine (AOBr) was degraded at a higher applied electrical charge, a continuous increase in AOCl concentration (up to 0.88 mM) was observed until the end of the experiments (i.e. 10.9 Ah L(-1)). In addition, total trihalomethanes (tTHMs) and total haloacetic acids (tHAAs) were further degraded with an increase in electrical charge under both pH conditions, to final total concentrations of 1 and 4 ?M (tTHMs), and 12 and 22 ?M (tHAAs), at acidic and circumneutral pH, respectively. In particular, tHAAs were still an order of magnitude above their initial concentration in ROC after further electrooxidation. Where high chloride concentrations are present, it was found to be necessary to separate chloride from ROC prior to electrochemical oxidation in order to avoid the formation of chlorinated by-products. PMID:22995242

Bagastyo, Arseto Y; Batstone, Damien J; Kristiana, Ina; Gernjak, Wolfgang; Joll, Cynthia; Radjenovic, Jelena

2012-09-06

362

Undoped and boron doped diamond nanoparticles as platinum and platinum-ruthenium catalyst support for direct methanol fuel cell application  

NASA Astrophysics Data System (ADS)

Nanoparticular diamond is a promising material that can be used as a robust and chemically stable catalytic support. It has been studied and characterized physically and electrochemically, in its powder and thin film forms. This thesis work intends to demonstrate that undoped diamond nanoparticles (DNPs) and boron-doped diamond nanoparticles (BDDNPs) can be used as an electrode and a catalytic support material for platinum and ruthenium catalysts. The electrochemical properties of diamond nanoparticle electrodes, fabricated using the ink paste method, were investigated. As an initial step, we carried out chemical purification of commercially available undoped DNPs by refluxing in aqueous HNO3 as well as of BDDNPs which were doped through a collaborative work with the University of Missouri. The purified material was characterized by spectroscopic and surface science techniques. The reversibility of reactions such as ferricyanide/ferrocyanide (Fe(CN) 63-/Fe(CN)64-) and hexaamineruthenium (III) chloride complexes as redox probes were evaluated by cyclic voltammetry at the undoped DNPs and BDDNPs surface. These redox probes showed limited peak currents and presented linear relationships between current (i) and the square root of the potential scan rate (v1/2). However, compared to conventional electrodes, the peak currents were smaller. BDDNPs show an improvement in charge transfer currents when compared to undoped DNPs. Platinum and ruthenium nanoparticles were chemically deposited on undoped DNPs and BDDNPs through the use of the excess of a mild reducing agent such NaBH4. In order to improve the nanoparticle dispersion sodium dodecyl benzene sulfonate (SDBS), a surfactant agent, was used. Percentages of platinum and ruthenium metals were varied as well as the stoichiometric amount of the reducing agent to determine adequate parameters for optimum performance in methanol oxidation. Both before and after the reducing process the samples were characterized by scanning electron microscopy (SEM), energy dispersive analysis (EDX), infrared spectroscopy (IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), prompt gamma neutron activation analysis (PGNAA), and X-ray photoelectron spectroscopy (XPS). In order to demonstrate the utility of the catalyst obtained, the samples were tested in an electrochemical cell using methanol as a probe solution. As was performed with the undoped DNPs and BDDNPs, the ink paste method was used to prepare the electrodes with Pt/DNP, Pt-Ru/DNP, Pt/BDDNP and Pt-Ru/BDDNP catalytic systems, to perform the electrochemical experiments. The Pt and Pt-Ru modified diamond electrodes were tested with cyclic voltammetry in 0.5 M H2SO4 as electrolyte support showing hydrogen adsorption/desorption at platinum surfaces. CO gas adsorption/desorption experiments were also performed to determine the active surface area of Pt when Ru is present. Methanol oxidation current peaks were obtained when the electrodes were tested in a 1.0 M methanol/0.5 M H2SO4 solution. The experimental results demonstrated that diamond nanoparticles are useful as an electrode material. A fuel cell is a device which transforms the chemical energy of a fuel directly into electrical energy. As previously mentioned, the aim of this research is to demonstrate the utility of undoped DNPs and BDDNPs as catalytic supports, which was performed by testing the catalytic systems obtained in a single fuel cell station at different temperatures to observe the cell performance.

La Torre Riveros, Lyda

363

Boron and phosphorus doping of aSiC:H thin films by means of ion implantation  

Microsoft Academic Search

A detailed study of the structural and optoelectronic properties of boron- and phosphorus-implanted a-SiC:H thin films is presented. The films have been deposited by ultra high vacuum plasma-enhanced chemical vapour deposition and have energy gap values of about 2 eV. The effects of varying carbon content, boron-and phosphorus-implanted dose and annealing temperatures are reported. It is found that ion implantation

F. Demichelis; G. Crovini; C. F. Pirri; E. Tresso; R. Galloni; C. Summonte; R. Rizzoli; F. Zignani; P. Rava

1995-01-01

364

Highly efficient and energy-saving sectional treatment of landfill leachate with a synergistic system of biochemical treatment and electrochemical oxidation on a boron-doped diamond electrode.  

PubMed

In this paper, a synergistic combination of the biochemical treatment and electrochemical oxidation (SBEO) of landfill leachate with sectional treatment on a boron-doped diamond (BDD) electrode is proposed. The first stage involves the synergistic system of biochemical treatment and electrochemical oxidation. Then, the second stage is followed by individual biochemical treatment. Comparisons among the SBEO, electrochemical oxidation, biochemical treatment and biochemical treatment with the pretreatment of electrochemical oxidation are made systematically, which show that this method is both highly efficient and energy-saving. The higher TOC removal and low energy cost on the BDD electrode can be explained by the conversion of the bio-refractory pollutants to biodegradable organics in the electrochemical oxidation process, improving the current efficiency and reducing the energy cost. The treated wastewater is degraded only with biochemical treatment in the second stage, which further improves efficiency and reduced the energy cost. PMID:20413218

Zhao, Guohua; Pang, Yaning; Liu, Lei; Gao, Junxia; Lv, Baoying

2010-04-02

365

Use of 'split waves' for the measurement of electrocatalytic kinetics: methyl viologen mediated oxygen reduction on a boron-doped diamond electrode.  

PubMed

The mediated reduction of oxygen via the reduced form of methyl viologen is studied voltammetrically. The investigation is facilitated through the use of a boron-doped diamond electrode, allowing the catalytic response to be clearly delineated from that of the direct oxygen reduction process at the electrode surface. From simulation a high homogeneous electron transfer rate (6 × 10(9) M(-1) s(-1)) is found for the one-electron reduction of oxygen to superoxide. This value is in close agreement with that found using non-electrochemical methods and is significantly higher than the values previously reported in electrochemical studies. In the latter case it is demonstrated that the underestimation of the electron transfer rate arises due to oversimplification of the reaction mechanism. PMID:23598364

Lin, Qianqi; Li, Qian; Batchelor-McAuley, Christopher; Compton, Richard G

2013-04-19

366

Effect of ion bombardment on deep photoluminescence bands in p-type boron-modulation-doped Si layers grown by molecular-beam epitaxy  

NASA Astrophysics Data System (ADS)

Broad photoluminescence (PL) bands (about 100 meV full width at half maximum) in the energy range between 0.70 and 1.03 eV are shown to be a frequently occurring feature in p-type boron-modulation-doped Si epilayers grown at low temperature by molecular-beam epitaxy. It is shown that the presence of a particular broad band (BB) is critically determined by the bias applied to the substrate during the growth. This gives evidence that these deep PL bands are at least partly induced by ion bombardment during the growth. To clarify their origin, the effect of the hydrogenation and the influence of a magnetic field on the PL bands are studied. The results obtained indicate the existence of at least four types of radiative centers. The observed correlation between x-ray-diffraction and PL measurements suggests that some of the BB's could be related to macrodefects, such as defect clusters. The optically detected cyclotron resonance (ODCR) technique is used to specify the spatial location of the BB-related defects in the structures. Information on the dependence of the electron mobility on the growth conditions is also obtained by ODCR. An active role of the boron dopants in the formation of the defects giving rise to the BB's is clearly demonstrated by comparing results from undoped Si epilayers grown under similar conditions.

Buyanova, I. A.; Chen, W. M.; Henry, A.; Ni, W.-X.; Hansson, G. V.; Monemar, B.

1995-10-01

367

Effect of boronizing and shot peening in ferrous based FeCu–Graphite powder metallurgy material on wear, microstructure and mechanical properties  

Microsoft Academic Search

Ferrous based materials manufactured by powder metallurgy (P\\/M) method are widely used in industry. These materials are very important because they do not require machining, have self-lubricated properties as journal bearing material, find applications in medical industry. In this study, powder metal parts were manufactured from ferrous based FeCu–Graphite composites by P\\/M method. Wear and mechanical test samples were manufactured

Selim Sarper Yilmaz; Bekir Sad?k Ünlü; Remzi Varol

2010-01-01

368

Thermoelectric Properties of beta -Boron and Some Boron Compounds. Final Report, August 1981-September 1984.  

National Technical Information Service (NTIS)

The thermoelectric properties, that is the Seebeck coefficient, and electrical and thermal conductivity, of doped beta -boron have been measured from 300 to 1600 K. Most of the useful doping elements are transition metals and occupy interstitial sites in ...

G. A. Slack J. H. Rosolowski M. L. Miller I. C. Huseby

1984-01-01

369

Initial boronization of PBX-M using ablation from solid boronized probes  

SciTech Connect

Boronization was performed by plasma ablation of two solid boronized target probes. Probe-1, in a mushroom shape, consisted of a 10.7% boronized two-dimensional carbon-carbon composite containing 3.6 g of boron in a B[sub 4]C binder. Probe-2, in a rectangular shape, consisted of an 86% boronized graphite felt composite containing 19.5 g of 40-[mu]m boron particles. Probe-1 boronization deposited [approximately]26 monolayers of boron. After boronization with Probe-1, the loop voltage in 1-MW neutral-beam-heated plasmas decreased 27%, and volt-second consumption decreased 20%. Strong peripheral spectral lines from low-Z elements decreased by factors of [approximately]5. The central oxygen density decreased 15 to 20%. Carbon levels initially increased during boronization but were significantly reduced after boronization. The total radiated power during neutral beam injection decreased by 43%. Probe-2 boronization deposited [approximately]70 monolayers. Probe-2 boronization exhibited similar improved plasma conditions, but for some parameters, a smaller percentage change occurred because of the previous boronization with Probe-1. The ablation rates of both probes were consistent with front-face temperatures above the boron melting point. The results demonstrate the performance of two different boronized probe materials and the relative simplicity and effectiveness of solid target boronization as a convenient, real-time impurity control technique. 20 refs., 10 figs., 1 tab.

Kugel, H.W.; Timberlake, J.; Bell, R.; Kaita, R.; Kaye, S.; Okabayashi, M.; Paul, S.; Takahashi, H.; Tighe, W.; Von Goeler, S. (Princeton Univ., NJ (United States)) (and others)

1994-07-01

370

Influence of boron doping on magnetic properties and microwave characteristics of MnIr/FeCoB multilayers  

NASA Astrophysics Data System (ADS)

A detailed investigation of the influence of B doping on the magnetic properties and high frequency characteristics of FeCoB/MnIr multilayered thin films was carried out. Exchange bias was found to decrease monotonically with B doping possibly due to less favorable of AF phase of MnIr in the samples with rich B concentration. However, with small amount of doping up to 9% of B concentration, the MnIr fcc (111) peaks become more prominent and the real part of permeability enhanced. Our results suggest no correlation between the structural phase of MnIr and the exchange bias. Also, the influences of B doping on several static and dynamic parameters, such as rotational magnetic anisotropy field, coercivity, saturation magnetization, resonance frequency, and effective damping factor are presented and discussed. Our results support the claim that the coercivity enhancement and the arising of rotational anisotropy may have the same physical origin.

Phuoc, Nguyen N.; Ong, C. K.

2012-04-01

371

Influence of boron doping on magnetic properties and microwave characteristics of MnIr/FeCoB multilayers  

SciTech Connect

A detailed investigation of the influence of B doping on the magnetic properties and high frequency characteristics of FeCoB/MnIr multilayered thin films was carried out. Exchange bias was found to decrease monotonically with B doping possibly due to less favorable of AF phase of MnIr in the samples with rich B concentration. However, with small amount of doping up to 9% of B concentration, the MnIr fcc (111) peaks become more prominent and the real part of permeability enhanced. Our results suggest no correlation between the structural phase of MnIr and the exchange bias. Also, the influences of B doping on several static and dynamic parameters, such as rotational magnetic anisotropy field, coercivity, saturation magnetization, resonance frequency, and effective damping factor are presented and discussed. Our results support the claim that the coercivity enhancement and the arising of rotational anisotropy may have the same physical origin.

Phuoc, Nguyen N. [Temasek Laboratories, National University of Singapore, 5 A Engineering Drive 2, Singapore 117411 (Singapore); Ong, C. K. [Department of Physics, Center for Superconducting and Magnetic Materials, National University of Singapore, 2 Science Drive3, Singapore 117542 (Singapore)

2012-04-15

372

Characterization of boron-doped diamonds using 11B high-resolution NMR at high magnetic fields  

Microsoft Academic Search

11B static\\/magic-angle spinning (MAS) NMR experiments are applied to four different B-doped diamond samples prepared by either high-pressure and high-temperature (HPHT) or CVD methods with various starting materials. Application of MAS enhances the spectral resolution appreciably and differences of the four B-doped diamond samples are well reflected in the corresponding MAS spectra. From the comparison among the MAS spectra, and

M. Murakami; T. Shimizu; M. Tansho; Y. Takano; S. Ishii; E. A. Ekimov; V. A. Sidorov; H. Sumiya; H. Kawarada; K. Takegoshi

2008-01-01

373

Tuneable anisotropic transport in nitrogen-doped nanocrystalline diamond films: Evidence of a graphite-diamond hybrid superlattice  

NASA Astrophysics Data System (ADS)

We show strong evidence of superlattice-like carbon layered structures in heavily nitrogen-doped ultrananocrystalline diamond (UNCD) films through the experimental demonstration of temperature-dependent anisotropic diffusive transport. The superlattice periodicity, in the range of several nanometers, is derived from the analysis of both magneto-resistance and the temperature-dependent conductivity based on the generalized diffusive Fermi surface model. The effect of quasi-two-dimensionality on the magneto-transport of these films yields a weak temperature dependence of the electron dephasing length. These results explain a reasonably strong coupling between the conducting carbon layers separated by the insulating nanodiamond grains producing the anisotropic transport in UNCD films controlled by the level of nitrogen incorporation.

Churochkin, Dmitry; Bhattacharyya, Somnath

2012-12-01

374

The effect of boron-doped on capacity of carbon cathode of rechargeable lithium-ion batteries  

Microsoft Academic Search

Purpose – To focus on the development of negative materials with a large Li ion capacity. Design\\/methodology\\/approach – All calculations were performed using the Own N-layered Integrated molecular Orbital and molecular Mechanics method with Becke 3-parameter, Lee, Yang, Parr for high-level treatment and with the universal force field for low-level treatment. Findings – It was found that boron substitution created

S. R. Ma; Z. H. Huang; C. B. Li; G. X. Yang; C. Wang

2007-01-01

375

Graphite Lubrication  

Microsoft Academic Search

The slipperiness of graphite is not inherent in the crystal structure alone but depends upon adsorption films, especially water, which cover the carbon atoms and provide surfaces of low cohesion. In vacuum graphite rods or brushes seize upon a moving base (copper or graphite) and wear away as a fine dust. This wear and accompanying high friction are instantly stopped

Robert H. Savage

1948-01-01

376

Self-assembled fabrication of a polycrystalline boron-doped diamond surface supporting Pt (or Pd)\\/Au-shell\\/core nanoparticles on the (111) facets and Au nanoparticles on the (100) facets  

Microsoft Academic Search

Modified boron-doped diamond (BDD) surfaces supporting different, carefully selected types of metal nanoparticles on different types of crystal facets were fabricated via a self-assembly method. A hydrogen plasma-treated BDD surface was treated with UV\\/ozone for 10s followed by immersion in a Au nanoparticle (AuNP) solution to fabricate a BDD surface selectively and densely supporting AuNPs on the (111) facet (AuNP111-BDD).

Takeshi Kondo; Kousuke Hirata; Takeshi Kawai; Makoto Yuasa

2011-01-01

377

Boron-deuterium complexes in diamond: How inhomogeneity leads to incorrect carrier type identification  

Microsoft Academic Search

The electrical properties of boron doped diamond layers after deuterium diffusion have been investigated by Hall effect and capacitance voltage measurements. It is found that (i) the deuterated boron doped diamond layers are inhomogeneous after the deuterium diffusion, resulting in conducting and insulating areas; (ii) negative and positive Hall voltages are measured on the same boron doped sample after deuterium

A. Kumar; J. Pernot; P. Muret; A. Traore´; L. Magaud; A. Deneuville; N. Habka; J. Barjon; F. Jomard; M. A. Pinault; J. Chevallier; C. Mer-Calfati; J. C. Arnault; P. Bergonzo

2011-01-01

378

Electron energy-loss spectroscopy of boron-doped layers in amorphous thin film silicon solar cells  

NASA Astrophysics Data System (ADS)

Electron energy-loss spectroscopy (EELS) is used to study p-doped layers in n-i-p amorphous thin film Si solar cells grown on steel foil substrates. For a solar cell in which an intrinsic amorphous hydrogenated Si (a-Si-H) layer is sandwiched between 10-nm-thick n-doped and p-doped a-Si:H layers, we assess whether core-loss EELS can be used to quantify the B concentration. We compare the shape of the measured B K edge with real space ab initio multiple scattering calculations and show that it is possible to separate the weak B K edge peak from the much stronger Si L edge fine structure by using log-normal fitting functions. The measured B concentration is compared with values obtained from secondary ion mass spectrometry, as well as with EELS results obtained from test samples that contain ~200-nm-thick a-Si:H layers co-doped with B and C. We also assess whether changes in volume plasmon energy can be related to the B concentration and/or to the density of the material and whether variations of the volume plasmon line-width can be correlated with differences in the scattering of valence electrons in differently doped a-Si:H layers.

Duchamp, M.; Boothroyd, C. B.; Moreno, M. S.; van Aken, B. B.; Soppe, W. J.; Dunin-Borkowski, R. E.

2013-03-01

379

Boron-doped peroxo-zirconium oxide dielectric for high-performance, low-temperature, solution-processed indium oxide thin-film transistor.  

PubMed

We developed a solution-processed indium oxide (In2O3) thin-film transistor (TFT) with a boron-doped peroxo-zirconium (ZrO2:B) dielectric on silicon as well as polyimide substrate at 200 °C, using water as the solvent for the In2O3 precursor. The formation of In2O3 and ZrO2:B films were intensively studied by thermogravimetric differential thermal analysis (TG-DTA), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT IR), high-resolution X-ray diffraction (HR-XRD), and X-ray photoelectron spectroscopy (XPS). Boron was selected as a dopant to make a denser ZrO2 film. The ZrO2:B film effectively blocked the leakage current at 200 °C with high breakdown strength. To evaluate the ZrO2:B film as a gate dielectric, we fabricated In2O3 TFTs on the ZrO2:B dielectrics with silicon substrates and annealed the resulting samples at 200 and 250 °C. The resulting mobilities were 1.25 and 39.3 cm(2)/(V s), respectively. Finally, we realized a flexible In2O3 TFT with the ZrO2:B dielectric on a polyimide substrate at 200 °C, and it successfully operated a switching device with a mobility of 4.01 cm(2)/(V s). Our results suggest that aqueous solution-processed In2O3 TFTs on ZrO2:B dielectrics could potentially be used for low-cost, low-temperature, and high-performance flexible devices. PMID:23883390

Park, Jee Ho; Yoo, Young Bum; Lee, Keun Ho; Jang, Woo Soon; Oh, Jin Young; Chae, Soo Sang; Lee, Hyun Woo; Han, Sun Woong; Baik, Hong Koo

2013-08-08

380

Boron acceptor concentration in diamond from excitonic recombination intensities  

Microsoft Academic Search

Excitonic recombinations are investigated by cathodoluminescence in a series of homoepitaxial diamond layers doped with boron in the range (2×1016)-(5×1018)atcm-3. As opposed to earlier observations made on polycrystalline boron-doped diamond, we show that the ratio between the neutral-boron bound exciton and the free-exciton recombination intensities is proportional to the boron content up to 6×1017cm-3 and starts to saturate above this

J. Barjon; T. Tillocher; N. Habka; O. Brinza; J. Achard; R. Issaoui; F. Silva; C. Mer; P. Bergonzo

2011-01-01

381

Electrochemical measurements of serotonin (5-HT) release from the guinea pig mucosa using continuous amperometry with a boron-doped diamond microelectrode.  

PubMed

Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder characterized by chronic abdominal discomfort, including pain, bloating and changes in bowel habits. The exact cause of IBS is not entirely understood. Recent studies have shown that IBS may be associated with altered serotonin (5-hydroxytryptamine, 5-HT) levels within the GI tract. About 90% of 5-HT in the human body is produced and stored in enterochromaffin (EC) cells that reside in the mucosal layer of the intestine. Measurements of serotonin availability locally in the mucosa can provide insight on the functionality of these cells and potentially the pathophysiology of the disease. In this study, we used continuous amperometry with a diamond microelectrode to record serotonin levels in vitro in the ileum mucosa as an oxidation current. The boron-doped diamond (BDD) microelectrode is quite practical for these measurements because if its low background signal, low sensitivity to solution pH changes, and excellent resistance to fouling by adsorbed serotonin oxidation reaction products. In fact, the measurements are only possible because of the unique properties of diamond. We present electrochemical data that demonstrate the diamond microelectrode's utility for assessment of enterochromaffin cell function. Confirmation that the oxidation current was associated with indogenous serotonin release came from pharmacological studies. We are hopeful that these types of in vitro electrochemical measurements will lead to a better understanding of the pathophysiology of IBS. PMID:20209031

Zhao, Hong; Bian, Xiaochun; Galligan, James J; Swain, Greg M

2010-02-01

382

Development of solar-driven electrochemical and photocatalytic water treatment system using a boron-doped diamond electrode and TiO2 photocatalyst.  

PubMed

A high-performance, environmentally friendly water treatment system was developed. The system consists mainly of an electrochemical and a photocatalytic oxidation unit, with a boron-doped diamond (BDD) electrode and TiO(2) photocatalyst, respectively. All electric power for the mechanical systems and the electrolysis was able to be provided by photovoltaic cells. Thus, this system is totally driven by solar energy. The treatment ability of the electrolysis and photocatalysis units was investigated by phenol degradation kinetics. An observed rate constant of 5.1 x 10(-3)dm(3)cm(-2)h(-1) was calculated by pseudo-first-order kinetic analysis for the electrolysis, and a Langmuir-Hinshelwood rate constant of 5.6 microM(-1)min(-1) was calculated by kinetic analysis of the photocatalysis. According to previous reports, these values are sufficient for the mineralization of phenol. In a treatment test of river water samples, large amounts of chemical and biological contaminants were totally wet-incinerated by the system. This system could provide 12L/day of drinking water from the Tama River using only solar energy. Therefore, this system may be useful for supplying drinking water during a disaster. PMID:19863989

Ochiai, Tsuyoshi; Nakata, Kazuya; Murakami, Taketoshi; Fujishima, Akira; Yao, Yanyan; Tryk, Donald A; Kubota, Yoshinobu

2009-10-01

383

Electrochemical treatment of phenolic waters in presence of chloride with boron-doped diamond (BDD) anodes: experimental study and mathematical model.  

PubMed

This work deals with an experimental and numerical study on the electrochemical treatment of waters containing phenolic compounds with boron-doped diamond (BDD) anodes. Anodic oxidation of m-cresol, as a model of phenolic compound, was investigated by galvanostatic electrolyses. The electrolyses were carried out under different experimental conditions by using an impinging-jet flow cell inserted in a hydraulic circuit in a closed loop. On the basis of the experimental results a mathematical model was implemented to simulate the effect of the chemistry of organic compounds and solution on the process, in particular the effect of chlorides on the kinetics of m-cresol oxidation. The effect of hydrodynamics of the cell on the mass transfer towards the electrode surface was also considered. The model was validated through comparison with experimental data: the results showed that the proposed model well interpreted the complex effect on removal efficiency of such operative parameters as current density, hydrodynamic of the reactor and chemistry of the solution. The model predictions were utilised to obtain quantitative information on the reaction mechanism, as well as to predict the performance of the process under different operative conditions, by calculating some relevant figures of merit. PMID:19815340

Mascia, Michele; Vacca, Annalisa; Polcaro, Anna Maria; Palmas, Simonetta; Ruiz, Jesus Rodriguez; Da Pozzo, Anna

2009-09-17

384

High-performance liquid chromatographic method with amperometric detection employing boron-doped diamond electrode for the determination of sildenafil, vardenafil and their main metabolites in plasma.  

PubMed

A simple, fast and sensitive HPLC method with electrochemical detection employing boron-doped diamond electrode (BDD) for the determination of sildenafil (Viagra™), vardenafil (Levitra™) and their main metabolites, N-desmethyl sildenafil and N-desethyl vardenafil in human plasma is presented. The assay involved drug extraction by tert-butyl methyl ether and isocratic reversed-phase liquid chromatography with amperometric detection. Complete separation of all analytes was achieved within 12 min. The mobile phase consisted of 20mM sodium dihydrogen phosphate with 40 mM sodium perchlorate/acetonitrile (70:30, v/v), pH 3.5. The electrode working potential was +1520 mV (vs. Pd/H(2)). Calibration curves were linear over the concentration range of 10-400 ng mL(-1). Phloretin was used as an internal standard. The limits of detection (LOD) and quantification (LOQ) for the studied analytes were within the range of 2-4 ng mL(-1) and 7.0-13.4 ng mL(-1), respectively. The developed method was applied to human plasma samples spiked with analytes at therapeutic concentrations. The study confirms the method's suitability for both pharmacokinetic studies and therapeutic monitoring. PMID:21943935

Bartošová, Zdenka; Jirovský, David; Horna, Aleš

2011-09-08

385

Comparative study of long-period gratings written in a boron co-doped fiber by an electric arc and UV irradiation  

NASA Astrophysics Data System (ADS)

The paper presents for the first time a comparative study of long-period gratings (LPGs) written by point-by-point UV irradiation and by electrical arc discharges. These gratings were inscribed in a highly photosensitive boron co-doped fiber that can be considered as a suitable platform for LPG writing using either technology. The experimental transmission data for the manufactured LPG devices fit well when compared to the simulations we carried out in parallel. As a result of each of these writing processes, we were able to obtain a remarkably good quality of grating. Two reasons could explain the observed small differences between the spectra: a slight mismatch of the period of the gratings and an unintentional tapering of the fiber during the arc-based processes. We also found that the UV irradiation at ? = 248 nm can cause clearly visible damage to the fiber's surface. As a result of the UV writing, a coupling to the asymmetrical cladding modes can take place. Moreover, the gratings written using the two technologies show a very similar refractive index and temperature-sensing properties. The only differences between them can come from a physical deformation of the fiber induced by the electric arc discharges.

Smietana, M.; Bock, W. J.; Mikulic, P.

2010-02-01

386

Electro-fenton and photoelectro-fenton degradation of sulfanilic acid using a boron-doped diamond anode and an air diffusion cathode.  

PubMed

The mineralization of sulfanilic acid has been studied by electro-Fenton (EF) and photoelectro-Fenton (PEF) reaction with UVA light using an undivided electrochemical cell with a boron-doped diamond (BDD) anode and an air diffusion cathode able to generate H(2)O(2). Organics were then oxidized by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton's reaction between generated H(2)O(2) and added Fe(2+). The UVA irradiation in PEF enhanced the production of hydroxyl radicals in the bulk, accelerating the removal of organics and photodecomposed intermediates like Fe(III)-carboxylate complexes. Partial decontamination of 1.39 mM sulfanilic acid solutions was achieved by EF until 100 mA cm(-2) at optimum conditions of 0.4 mM Fe(2+) and pH 3.0. The increase in current density and substrate content led to an almost total mineralization. In contrast, the PEF process was more powerful, yielding almost complete mineralization in less electrolysis time under comparable conditions. The kinetics for sulfanilic acid decay always followed a pseudo-first-order reaction. Hydroquinone and p-benzoquinone were detected as aromatic intermediates, whereas acetic, maleic, formic, oxalic, and oxamic acids were identified as generated carboxylic acids. NH(4)(+) ion was preferentially released in both treatments, along with NO(3)(-) ion in smaller proportion. PMID:22404230

El-Ghenymy, Abdellatif; Garrido, José Antonio; Centellas, Francesc; Arias, Conchita; Cabot, Pere Lluís; Rodríguez, Rosa María; Brillas, Enric

2012-03-21

387

Label-free sequence-specific DNA sensing using copper-enhanced anodic stripping of purine bases at boron-doped diamond electrodes.  

PubMed

Stripping voltammetric determination of purine bases in the presence of copper ions at mercury, amalgam, or carbon-based electrodes has recently been utilized in analysis of DNA or synthetic oligodeoxynucleotides (ODNs). Here we report on copper-enhanced label-free anodic stripping detection of guanine and adenine bases in acid-hydrolyzed DNA at anodically oxidized boron-doped diamond electrode (AO-BDDE). The AO-BDDE was successfully applied in a three-electrode microcell in which an approximately 50 microL drop of the analyte solution can be efficiently stirred during the accumulation step by streaming of an inert gas. Accelerated mass transport due to the solution motion in the presence of copper resulted in enhancement of the guanine oxidation signal by about 2 orders of magnitude (compared to accumulation of the analyte from still solution not containing copper), allowing an easy detection of approximately 25 fmol of the ODNs. The proposed technique is shown to be suitable for a determination of purine (particularly guanine) content in DNA samples. Applications of the technique in magnetic bead-based DNA assays (such as hybridization with DNA sequences exhibiting asymmetrical distribution of purine/pyrimidine nucleotides between the complementary strands or monitoring of amplification of specific DNA fragments in a duplex polymerase chain reaction) are demonstrated. PMID:18321078

Hason, Stanislav; Pivonkova, Hana; Vetterl, Vladimír; Fojta, Miroslav

2008-03-06

388

Evolution of flow pattern defects in boron-doped ?1 0 0? Czochralski silicon crystals during secco etching procedure  

Microsoft Academic Search

Flow pattern defects (FPDs) is one kind of grown-in defects in large diameter Czochralski silicon (Cz-Si) crystals. The evolution of FPDs in lightly doped Cz-Si crystals during secco etchant (50% HF: 0.15molL?1K2Cr2O7=2:1) etching process, was studied in detail firstly. The results also showed that the outline of FPDs became larger and the void on the tip of FPDs changed into

Jianfeng Zhang; Caichi Liu; Qigang Zhou; Jing Wang; Qiuyan Hao; Hongdi Zhang; Yangxian Li

2004-01-01

389

Effects of heat treatment and irradiation on mechanical properties in F82H steel doped with boron and nitrogen  

Microsoft Academic Search

Effects of heat treatment and irradiation on mechanical properties and microstructures have been studied for martensitic steel F82H co-doped with 60ppm B and 200ppm N (F82H+B+N) to evaluate fundamental mechanical properties and irradiation response before irradiation at JMTR and HFIR facilities. The specimens were firstly normalized at 1150°C and tempered at 700°C, secondly normalized at 1000°C and tempered at 700,

N. Okubo; E. Wakai; S. Matsukawa; T. Sawai; S. Kitazawa; S. Jitsukawa

2007-01-01

390

Micro Extrinsic Fiber-Optic Fabry-Perot Interferometric Sensor Based on Erbium and Boron-Doped Fibers  

Microsoft Academic Search

Micro extrinsic Fabry-Perot interferometers (MEFPIs), with cavity lengths of up to ~ 9 mum and maximum fringe contrast of ~ 19 dB, are fabricated by chemically etching Er- and B-doped optical fibers and then splicing the etched fiber to a single-mode fiber, for the first time to the best of our knowledge. The strain and temperature responses of the MEFPI

Yun-Jiang Rao; Bing Xu; Zeng-Ling Ran; Yuan Gong

2010-01-01

391

20% Efficient Passivated Large-Area Metal Wrap Through Solar Cells on Boron-Doped Cz Silicon  

Microsoft Academic Search

We present metal wrap through passivated emitter and rear solar cells (MWT-PERC) on monocrystalline p-type silicon featuring laser-doped selective emitter structures in com- bination with either screen-printed (SP) or more advanced dis- pensed front side contacts. Thermally grown silicon oxide layers serve as emitter and rear surface passivation. Laser-fired contacts connect the SP aluminum rear contact to the silicon base.

E. Lohmuller; B. Thaidigsmann; M. Pospischil; U. Jager; S. Mack; J. Specht; J. Nekarda; M. Retzlaff; A. Krieg; F. Clement; A. Wolf; D. Biro; R. Preu

2011-01-01

392

Pre-irradiation spatial distribution and stability of boride particles in rapidly solidified boron-doped stainless steels  

SciTech Connect

The time temperature behavior of boride particles has been studied in rapidly solidified ultra low carbon and nitrogen modified 316 stainless steel with 0.088% boron and 0.45% zirconium. The results show that the as-splat-cooled specimens exhibit precipitates at the grain boundaries and triple junctions. For temperatures up to about 750/sup 0/C no significant microstructural changes occur for short heat treatment times. In the temperature range of 750 to 950/sup 0/C, however, particles typically 100 to 500 A in diameter containing Zr and B are formed within the grains. Higher temperatures enhance the formation of such particles and give rise to particle networks. The results show that a fine and uniform distribution of the boride particles almost exclusively within the grains can be achieved if proper annealing conditions are chosen. This type of distribution is an important requirement for the homogeneous production of helium during neutron irradiation in fast reactors.

Kanani, N.; Arnberg, L.; Harling, O.K.

1981-01-01

393

Electrochemical Response of Biomolecules on Carbon Substrates: Comparison between Oxidized HOPG and O-Terminated Boron-Doped CVD Diamond  

NASA Astrophysics Data System (ADS)

In this work, two types of electroactive proteins, namely azurin and ferrocene-labeled papain, were adsorbed on differently oxidized diamond and investigated by cyclic voltammetry. A comparison was made with oxidized highly oriented pyrolytic graphite (HOPG). A direct electron transfer to the biomolecules was confirmed for all oxidized carbon electrodes. A strong influence of the oxygen termination process of diamond on the charge transfer through the interface has been observed. This effect has been attributed to different defects and electronic states at the interface, as confirmed by capacitance-voltage measurements in electrolyte, electrical characterisation and X-ray photoemission spectroscopy (XPS). Wet chemical oxidized diamond was proved to be the most effective electrode material for biomolecule anchoring with an electron transfer rate higher by factor of three than that of HOPG.

Baier, Claudia; Sternschulte, Hadwig; Denisenko, Andrej; Schlichtiger, Alice; Stimming, Ulrich

394

Graphite Dispersion.  

National Technical Information Service (NTIS)

The method relates to a uniform dispersion of oxide ceramic-coated nuclear reactor spheres within a matrix essentially of graphite. The method involves tumbling the spheres, spraying with benzene and a slurry of graphite in a solution of medium coal-tar p...

M. C. Brockway

1965-01-01

395

Micro Extrinsic Fiber-Optic Fabry-Perot Interferometric Sensor Based on Erbium- and Boron-Doped Fibers  

NASA Astrophysics Data System (ADS)

Micro extrinsic Fabry-Perot interferometers (MEFPIs), with cavity lengths of up to ~ 9 ?m and maximum fringe contrast of ~ 19 dB, are fabricated by chemically etching Er- and B-doped optical fibers and then splicing the etched fiber to a single-mode fiber, for the first time to the best of our knowledge. The strain and temperature responses of the MEFPI sensors are investigated experimentally. Good linearity and high sensitivity are achieved. Such a type of MEFPI sensor is cost-effective and suitable for mass production, indicating its great potential for a wide range of applications.

Rao, Yun-Jiang; Xu, Bing; Ran, Zeng-Ling; Gong, Yuan

2010-02-01

396

Isothermal and cyclic oxidation resistance of boron-modified and germanium-doped silicide coatings for titanium alloys  

SciTech Connect

Since titanium alloys with an adequate balance of mechanical properties and high-temperature oxidation resistance have not been developed, protective coatings are required. In the authors previous paper, B-modified and Ge-doped silicide diffusion coatings grown on Cp Ti, Ti-24Al-11Nb, Ti-22Al-27Nb, and Ti-20Al-22Nb by the halide-activated, pack-cementation method were described. In this study, isothermal and cyclic oxidation were used to evaluate the oxidation performance of these coatings in comparison to uncoated substrates. The rate-controlling mechanism for isothermal oxidation at high temperature was solid-state diffusion through a SiO{sub 2} scale, while the mechanism for low-temperature oxidation involved grain-boundary diffusion through TiO{sub 2}. Both isothermal and cyclic oxidation rates for the B-modified and Ge-doped silicide coatings were much slower than for pure TiSi{sub 2}. Oxygen contamination was not detected by microhardness measurements in the coated substrates after 200 oxidation cycles at 500-1000{degrees}C for the Ti-Al-Nb alloys, or at 500-875{degrees}C for Cp Ti. The excellent oxidation resistance for the optimum coating compositions is discussed.

Cockeram, B.; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States)

1996-06-01

397

Analysis of Pseudomonas quinolone signal and other bacterial signalling molecules using capillaries coated with highly charged polyelectrolyte monolayers and boron doped diamond electrode.  

PubMed

Coated capillary electrophoresis equipped with a boron doped diamond (BDD) electrode was developed for analysis of chemically synthesised 2-heptyl-3-hydroxy-4-quinolone (HHQ), 2-heptyl-3-hydroxy-4-quinolone (PQS), and 2-methyl analogues. Detection was then extended to biological samples. PQS and its biological precursor, HHQ, are two key regulators of bacterial cooperative behaviour known as quorum sensing in the nosocomial pathogen Pseudomonas aeruginosa. The fused silica capillary was coated with a thin layer of poly (diallyldimethylammonium) chloride to reverse the electroosmosis, allowing fast migration of PQS and HHQ with improved selectivity. The four model compounds were baseline resolved using a 50 mM H(3)PO(4)-Tris, pH 2.0 buffer with 20% (v/v) acetonitrile as buffer additive. With an injection time of 3 s, the detection limits of four analytes ranging from 60 to 100 nM (S/N=3) were observed when the BDD electrode was poised at +1.5 V vs. 3 M Ag/AgCl. As expected, no PQS or HHQ was detected from the supernatant of the P. aeruginosa (pqsA) mutant. A concentration of HHQ of 247 ?M was detected from the supernatant of the pqsH mutant, which catalyses the conversion of HHQ to PQS in the presence of molecular oxygen by monooxygenase. The separation and detection scheme was applicable to follow the conversion of HHQ to PQS in P. aeruginosa when entering the stationary phase of growth. The results obtained by coated capillary electrophoresis with BDD detection were validated and compared well with LC-MS data. PMID:22771070

Zhou, Lin; Reen, F Jerry; O'Gara, Fergal; McSweeney, Christina M; Clarke, Sarah L; Glennon, Jeremy D; Luong, John H T; McGlacken, Gerard P

2012-06-26

398

Infrared Response of Impurity Doped Silicon MOSFET's (IRFET's): Fabrication and Characterization of the Gallium Doped Infrared Sensing MOSFET.  

National Technical Information Service (NTIS)

Fabrication and characterization of the gallium doped infrared sensing MOSFET is described. Gallium doped MOSFET device structures have been fabricated by diffusion of gallium from doped oxide sources into n-channel MOSFET's fabricated on a normal boron p...

L. Forbes

1976-01-01

399

Mesophase Graphite.  

National Technical Information Service (NTIS)

This report contains results and discussions related to the investigation of the materials and process parameters associated with the development of the mesophase- graphite process. Three starting materials are investigated as precursors for preparing mes...

M. P. Whittaker H. P. Gilliam

1973-01-01

400

Direct electrochemistry and electrocatalysis of anthraquinone-monosulfonate/polyaniline hybrid film synthesized by a novel electrochemical doping-dedoping-redoping method on pre-activated spectroscopically pure graphite surface.  

PubMed

Polyaniline (PANI) film in the form of emeraldine salt (ES) doped with anthraquinone-2-sulfonate (AQS) was synthesized by a novel electrochemical doping-dedoping-redoping method on pre-activated spectroscopically pure graphite electrode surface. SEM showed the highly porous microstructure with sponge-like morphology of the AQS/PANI hybrid film, which has more available active sites for facilitating electron transfer and energy efficiency of redox reactions. FTIR and UV-vis spectra demonstrated the incorporation of AQS into the conductive PANI matrix. Cyclic voltammetric (CV), electrochemical impedance spectroscope (EIS), rotating ring-disk electrode (RRDE) and chronoamperometry (CA) techniques indicated that the AQS/PANI composite has high electrocatalytic activity and remarkable stability for the two-electron reduction of oxygen via an electrochemical-chemical mechanism at the base of the porous PANI film. The acid centers of PANI (protonated imine group) played an important role not only in two internal redox transform processes, but also in an external charge transfer reaction during the electrocatalytic reduction of oxygen. The incorporation of anionic AQS groups into PANI matrix to prepare electroactive PANI using the electrochemical doping-dedoping-redoping method is conceptually new, and may be extended to the development of new functional materials from many other conducting polymers and quinonoid compounds for wide applications in catalysis, sensors, molecular electronics, and so on. PMID:21212886

Zhang, Guoquan; Yang, Fenglin

2011-01-07

401

First-Principles Investigation on Boron Nanostructures  

NASA Astrophysics Data System (ADS)

First-principles calculations based on density functional theory are employed to study and predict the properties of boron and Mg boride nanostructures. For boron nanostructures, two-dimensional boron sheets are found to be metallic and made of mixtures of triangles and hexagons which benefit from the balance of two-center bonding and three-center bonding. This unusual bonding in boron sheets results in a self-doping picture where adding atoms to the hexagon centers does not change the number of bonding states but merely increases the electron count. Boron sheets can be either flat or buckled depending on the ratio between hexagons and triangles. Formed by stacking two identical boron sheets, double-layered boron sheets can form interlayer bonds, and the most stable one is semiconducting. Built from single-layered boron sheets, single-walled boron nanotubes have smaller curvature energies than carbon nanotubes and undergo a metal-to-semiconductor transition once the diameter is smaller than ˜20 A. Optimal double-walled boron nanotubes with inter-walled bonds formed are metallic and always more stable than single-walled ones. For Mg boride nanostructures, certain Mg boride sheets prefer to curve themselves into nanotubes, which is explained via Mg-Mg interactions governed by the charge state of Mg. In addition, optimal Mg boride sheet structures are explored with a genetic algorithm. Phase diagrams for Mg boride sheet structures are constructed and stable phases under boron-rich environments are identified. Curvature effects on the phase diagram of Mg boride nanotubes are also discussed. As a natural extension to boron sheets, layered boron crystals based on boron sheets are then presented and are shown to be stable under high pressure. Finally, this thesis ends with an investigation of hydrogen-storage properties of pristine and metal doped boron nanostructures.

Tang, Hui

402

Initial boronization of PBX-M using ablation of solid boronized probes  

SciTech Connect

The initial boronization of PBX-M was performed using the sequential ablation of two types of solid target probes. Probe-1 in a mushroom shape consisted of a 10.7% boronized 2-D C-C composite containing 3.6 g of boron in a B[sub 4]C binder. Probe-2 in a rectangular shape consisted of an 86% boronized graphite felt composite containing 19.5 g of 40 [mu] boron particles. After boronization with Probe-1, the loop voltage during 1 MW neutral beam heated plasmas decreased 27% and volt-sec consumption decreased 20%. Strong peripheral spectral lines from low-Z elements decreased by factors of about 5. The central oxygen density decreased 15--20%. The total radiated power during neutral beam injection decreased by 43%. Probe-2 boronization exhibited improved operating conditions similar to Probe-1, but for some parameters, a smaller percentage change occurred due to the residual boron from the previous boronization using Probe-1. The ablation rates of both probes were consistent with front face temperatures at or slightly above the boron melting point. These results confirm the effectiveness of the solid target boronization (STB) technique as a real-time impurity control method for replenishing boron depositions without the use of hazardous borane compounds.

Kugel, H.W.; Hirooka, Y.; Kaita, R.; Kaye, S.; Khandagle, M. (California Univ., Los Angeles, CA (United States). Inst. of Plasma and Fusion Research); Timberlake, J.; Bell, R.; England, A.; Isler, R.; Okabayashi, M.; Paul, S.; Takahashi, H.; Tighe, W.; von Goeler, S.; Post-Zwicker, A.P. (Oak Ridge National Lab., TN (United States)); Jones, S. (Massachusetts Inst. of Tech., Cambridge, MA (United States))

1993-05-01

403

Icosahedral B{sub 12}, macropolyhedral boranes, {beta}-rhombohedral boron and boron-rich solids  

SciTech Connect

The preference for icosahedral B{sub 12} amongst polyhedral boranes and elemental boron is explained based on an optimization of overlap model. The ingenious ways in which elemental boron and boron-rich solids achieve icosahedron-related structures are explained by a fragment approach. The Jemmis mno rules are used to get the electron requirements. The extra occupancies and vacancies in {beta}-rhombohedral structures are shown to be inevitable results of electron requirements. The detailed understanding of the structure suggests ways of doping {beta}-rhombohedral boron with metals for desired properties. Theoretical studies of model {beta}-rhombohedral solids with metal dopings provide support for the analysis. - Graphical abstract: A short legend: Principal building blocks B{sub 12}, B{sub 57}, and B{sub 84} of elemental boron and boron-rich solids.

Jemmis, Eluvathingal D. [School of Chemistry, University of Hyderabad, Hyderabad 500046 (India) and Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012 (India)]. E-mail: jemmis@ipc.iisc.ernet.in; Prasad, Dasari L.V.K. [School of Chemistry, University of Hyderabad, Hyderabad 500046 (India); Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012 (India)

2006-09-15

404

Mechanism of Enhanced Electrochemical Oxidation of 2,4-dichlorophenoxyacetic Acid with in situ Microwave Activated Boron-doped Diamond and Platinum Anodes  

NASA Astrophysics Data System (ADS)

Remarkable enhancement in degradation effect is achieved at in situ activated boron-doped diamond (BDD) and Pt anodes with different extent through electrochemical oxidation (EC) of 2,4-dichlorophenoxyacetic acid (2,4-D) with microwave (MW) radiation in a flow system. Results show that when EC is activated with MW radiation, the complete mineralization time of 2,4-D at the BDD is reduced quickly from 10 to 4 h while Chemical oxygen demand (COD) removal at Pt is increased from 37.7 to 58.3% at 10 h; the initial current efficiency is both improved about 1.5 times while the pseudo-first-order rate constant is increased by 153 and 119% at the BDD and Pt, respectively. To gain insight into the higher efficiency in microwave activated EC, the mechanism has therefore been systematically evaluated from the essence of electrochemical reaction and the accumulated hydroxyl radical concentration. 2,4-Dichlorophenol, catechol, benquinone, and maleic and oxalic acids are the main intermediates on the Pt anode measured by high performance liquid chromatography (HPLC), while the intermediates on the BDD electrode include 2,4-dichlorophenol, hydroquinone, and maleic and oxalic acids. The reaction pathway with microwave radiation is the same as that in a conventional electrochemical oxidation on both electrodes. While less and lower aromatic intermediates produce at the BDD with MW, which suggests the higher ring-open ratio and the faster oxidation of carboxylic acids. With microwave radiation, the ring-open ratio at the BDD is increased to 98.8% from 85.6%; the value at Pt is increased to 67.3% from 35.9%. So microwave radiation can activate the electrochemical oxidation, which leads to the higher efficiency. This promotion is mainly due to the higher accumulated hydroxyl radical concentration and the effects by microwave radiation. All the results prove that the BDD electrode presents much better mineralization performance with MW. To the best of our knowledge, it is the first time the systematic analysis of the mechanism of microwave activated EC has been reported.

Gao, Junxia; Zhao, Guohua; Liu, Meichuan; Li, Dongming

2009-09-01

405

Assessment of lithium ion doping into low crystallized carbonaceous materials using molecular orbital calculations  

Microsoft Academic Search

Using molecular orbital calculation, the Li doping reaction in low crystallized carbonaceous material was investigated. As the Li doping reaction occurs on the surface of the graphite layer, the influence on the electric charge of the graphite layer was examined with graphitic models attached with functional groups (-OH, -CHO). As a result, it is suggested that Li was doped at

Satoru Komoda; Mikio Watanabe; Shinichi Komaba; Tetsuya Osaka; Susumu Kikuyama; Kohji Yuasa

1998-01-01

406

Proceedings of the conference on electrochemistry of carbon allotropes: Graphite, fullerenes and diamond  

SciTech Connect

This conference provided an opportunity for electrochemists, physicists, materials scientists and engineers to meet and exchange information on different carbon allotropes. The presentations and discussion among the participants provided a forum to develop recommendations on research and development which are relevant to the electrochemistry of carbon allotropes. The following topics which are relevant to the electrochemistry of carbon allotropes were addressed: Graphitized and disordered carbons, as Li-ion intercalation anodes for high-energy-density, high-power-density Li-based secondary batteries; Carbons as substrate materials for catalysis and electrocatalysis; Boron-doped diamond film electrodes; and Electrochemical characterization and electrosynthesis of fullerenes and fullerene-type materials. Abstracts of the presentations are presented.

Kinoshita, K. [ed.] [Lawrence Berkeley National Lab., CA (United States); Scherson, D. [ed.] [Case Western Reserve Univ., Cleveland, OH (United States)

1998-02-01

407

Preparation and Properties of Using Carbon Chemical Vapor Coated Boron  

Microsoft Academic Search

Promising initial results on bulk Mg(B1-xCx)2 prepared with carbon doped boron are presented. Carbon doping is achieved by reaction of ethylene gas on boron powder using a stainless steel tube furnace, a technique suitable for industrial scale processing. The nominal amount of doping was controlled by varying the reaction time with a fixed volume of ethylene gas, and the actual

E. A. Young; Y. Yang

2007-01-01

408

The boron acceptor in diamond  

NASA Astrophysics Data System (ADS)

To date, the only dopant available for bulk diamond with good controllability is boron, which acts as an acceptor and can be incorporated in relatively high concentrations, allowing the design of devices for electronic applications. This paper summarizes data on doping procedures and on optical and electrical properties.

Thonke, Klaus

2003-03-01

409

Boron Doped Plastic Scintillator Efficiency  

NASA Astrophysics Data System (ADS)

This talk will describe the progress made in an interdisciplinary development project aimed at cost-effective, neutron sensitive, plastic scintillator. Colorado School of Mines researchers with backgrounds in Physics, Chemistry, and Chemical Engineering have worked on the incorporation of ^10B in plastics through extrusion. First results on transparent samples using fluorescent spectroscopy and beta excitation will be presented.

Mahl, Adam; Chouinard-Dussault, Pascale; Pecinovsky, Cory; Potter, Andrew; Remedes, Tyler; Dorgan, John; Greife, Uwe

2013-04-01

410

Boron-doped diamond microdisc arrays: electrochemical characterisation and their use as a substrate for the production of microelectrode arrays of diverse metals (Ag, Au, Cu)via electrodeposition.  

PubMed

A novel boron-doped diamond (BDD) microelectrode array is characterised with electrochemical and atomic force microscopic techniques. The array consists of 40 micron-diameter sized BDD discs which are separated by 250 microns from their nearest neighbour in a hexagonal arrangement. The conducting discs can be electroplated to produce arrays of copper, silver or gold for analytical purposes in addition to operating as an array of BDD-microelectrodes. Proof-of-concept is shown for four separate examples; a gold plated array for arsenic detection, a copper plated array for nitrate analysis, a silver plated array for hydrogen peroxide monitoring and last, cathodic stripping voltammetry for lead at the bare BDD-array. PMID:16096678

Simm, Andrew O; Banks, Craig E; Ward-Jones, Sarah; Davies, Trevor J; Lawrence, Nathan S; Jones, Timothy G J; Jiang, Li; Compton, Richard G

2005-08-01

411

Raman Spectrum of Graphite  

Microsoft Academic Search

Raman spectra are reported from single crystals of graphite and other graphite materials. Single crystals of graphite show one single line at 1575 cm?1. For the other materials like stress-annealed pyrolitic graphite, commercial graphites, activated charcoal, lampblack, and vitreous carbon another line is detected at 1355 cm?1. The Raman intensity of this band is inversely proportional to the crystallite size

F. Tuinstra; J. L. Koenig

1970-01-01

412

Minerals Yearbook 1989: Graphite  

SciTech Connect

Amorphous graphite was mined domestically in 1989. Graphite supplies, particularly of fine crystalline flake, lagged behind industrial demand, which increased substantially from the previous year. Prices of the major imported graphites generally increased from those of 1988. Production of manufactured graphite and graphite fibers decreased slightly and increased by 21% respectively.

Taylor, H.A.

1989-01-01

413

Boron-carbide and boron rich rhobohedral based transistors and tunnel diodes  

US Patent & Trademark Office Database

The present invention relates to the fabrication of a boron carbide/boron semiconductor devices. The results suggest that with respect to the approximately 2 eV band gap pure boron material, 0.9 eV band gap boron carbide (B.sub.5 C) acts as a p-type material. Both boron and boron carbide (B.sub.5 C) thin films were fabricated from single source borane cage molecules using plasma enhanced chemical vapor deposition (PECVD). Epitaxial growth does not appear to be a requirement. We have doped boron carbide grown by plasma enhanced chemical vapor deposition. The source gas close-1,2-dicarbadecaborane (orthocarborane) was used to grow the boron carbide while nickelocene (Ni(C.sub.5 H.sub.5)2) was used to introduce nickel into the growing film. The doping of nickel transformed a B.sub.5 C material p-type relative to lightly doped n-type silicon to an n-type material. Both p-n heterojunction diodes and n-p heterojunction diodes with n- and p-type Si [1,1,1] respectively. With sufficient partial pressures of nickelocene in the plasma reactor diodes with characteristic tunnel diode behavior can be successfully fabricated.

2002-08-27

414

Field emission of doped carbon nanotubes  

Microsoft Academic Search

We calculated field-emission currents from nitrogen- and boron-doped single-walled (5,5) carbon nanotubes by integrating time-dependent Schrödinger equations. Nitrogen doping increased the emission current owing to a shift in the energy level of a localized state to the Fermi level, and the creation of coupled states that have characteristics of both localized and extended states. On the other hand, boron doping

Hyo-Shin Ahn; Kwang-Ryeol Lee; Doh-Yeon Kim; Seungwu Han

2006-01-01

415

Boron alloy  

SciTech Connect

This paper describes a ferro-boron alloy produced in situ in a basic oxygen furnace, an induction furnace, or an electric furnace, or in combination with a mixing vessel. It comprises: 1.4% to 15% by weight boron; less than 0.002% by weight nitrogen; less than about 0.2% by weight carbon; less than about 0.01% by weight aluminum; and the balance iron with minute amounts of residuals.

Sussman, R.C.; Evans, L.G.

1990-06-26

416

Irradiation creep of graphite  

Microsoft Academic Search

Displacement damage of graphite by neutron irradiation causes graphite to change dimensions. This dimensional instability requires careful attention when graphite is used as as moderator and reflector material in nuclear devices. Natural gradients in flux and temperature result in time-varying differential growth generating stresses similar to thermal stresses with an ever increasing temperature gradient. Graphite, however, does have the ability

1990-01-01

417

Electronic Doping of Amorphous Carbon Thin Films  

NASA Astrophysics Data System (ADS)

This paper reports on the successful deposition of boron (B)-doped p-type (p-C:B) and phosphorus (P)-doped n-type (p-C:P) carbon (C) films, and the fabrication of p-C:B on silicon (Si) substrate (p-C:B/n-Si) and n-C:P/p-Si cells by a pulsed laser deposition (PLD) technique using a graphite target at room temperature. The boron and phosphorus atoms incorporated in the films were determined by X-ray photoelectron spectroscopy (XPS) to be in the range of 0.2-1.75 and 0.22-1.77 atomic percentages, respectively. The cells performances have been given in the dark I-V rectifying curve and I-V working curve under illumination when exposed to AM 1.5 illumination conditions (100 mW/cm2, 25°C). The open circuit voltage (Voc) and short circuit current density (Jsc) for p-C:B/n-Si are observed to vary from 230 to 250 mV and from 1.5 to 2.2 mA/cm2, respectively; they vary from 215 to 265 mV and from 7.5 to 10.5 mA/cm2, respectively, for n-C:P/p-Si cells. The p-C:B/n-Si cell fabricated using the target with the amount of boron by 3 weight percentages (Bwt%) showed the highest energy conversion efficiency, ? = 0.20% and fill factor, FF = 45%. The n-C:P/p-Si cell fabricated using the target with the amount of 7 Pwt% showed the highest ? = 1.14% and FF = 41%. The quantum efficiency (QE) of the p-C:B/n-Si and n-C:P/p-Si cells were observed to improve with Bwt% and Pwt%, respectively. The contribution of QE in the lower wavelength region (below 750 nm) may be due to photon absorption by the carbon layer, in the higher wavelength region it was due to the Si substrates. In this paper, the dependence of the boron and phosphorus content on the electrical and optical properties of the deposited films and the photovoltaic characteristics of the respective p-C:B/n-Si and n-C:P/p-Si heterojunction solar cells are discussed.

Rusop, M.; Soga, T.; Jimbo, T.; Umeno, M.; Sharon, M.

418

Decontamination of nuclear graphite  

Microsoft Academic Search

Graphite is used in gas-cooled reactors (e.g. AGR, MAGNOX, HTR) and Russian RMBK reactors as a moderator and reflector. About 250,000Mg of irradiated graphite (i-graphite) has to be considered as radioactive waste in the next few centuries. Fission products and activation of impurities in the graphite contaminate this graphite during reactor operation. Key nuclides for waste management are Co-60 during

Johannes Fachinger; Werner von Lensa; Tatjana Podruhzina

2008-01-01

419

Doping dependence of optical properties of solid-phase crystallized evaporated poly-Si thin films on glass  

Microsoft Academic Search

Boron and phosphorus doped polycrystalline silicon films with moderate and heavy doping of ~5times1017cm-3 and ~1times1019 cm-3 respectively are investigated to observe the impacts of doping on the optical properties, with \\

Song He; Alistair B. Sproul; Armin G. Aberle

2008-01-01

420

Edge-plane-rich nitrogen-doped carbon nanoneedles and efficient metal-free electrocatalysts.  

PubMed

CNN news: N-doped carbon nanoneedles (CNNs) are synthesized by self-assembling core-shell nanostructures and nanoreactors around cellulose nanoneedles, and subsequent graphitization. The resulting graphitic nanoneedles (see picture) have well-organized graphitic multi-layers and large proportions of N-doped edge planes. The materials serve as efficient metal-free electrocatalysts for hydrazine oxidation. PMID:22684734

Silva, Rafael; Al-Sharab, Jafar; Asefa, Tewodros

2012-06-08

421

Boron in silicon carbide: a metastable shallow acceptor  

NASA Astrophysics Data System (ADS)

Alongside boron doping of silicon carbide a technologically and physically important effect is observed: a reduced doping efficiency(H. Itoh et al.), Appl. Phys. Lett. 73, 1427 (1998).. Experiments indicate that intrinsic point defects, most likely interstitials, affect the boron activity. Yet the role played by the different defects and their boron-related complexes is an open question. We approach this issue by investigating the energetics of relevant defect reactions in 3C-SiC by an ab initio method. We have found that substitutional boron may trap vacancies. On the other hand it may undergo a kick-out reaction with intrinsic interstitials. The resulting boron-vacancy complexes and boron interstitials are deep mobile defects. Hence the shallow acceptor is metastable with respect to reactions with vacancies and interstitials. Additionally, boron at carbon sites is metastable to leave its lattice site, creating a boron interstitial-vacancy complex and thereby reducing its energy. Such a behaviour is not found for boron at silicon sites. This explains why experimentally only boron at silicon sites has been observed.

Bockstedte, Michel; Mattausch, Alexander; Pankratov, Oleg

2000-03-01

422

Method for sputtering a PIN microcrystalline/amorphous silicon semiconductor device with the P and N-layers sputtered from boron and phosphorous heavily doped targets  

DOEpatents

A silicon PIN microcrystalline/amorphous silicon semiconductor device is constructed by the sputtering of N, and P layers of silicon from silicon doped targets and the I layer from an undoped target, and at least one semi-transparent ohmic electrode.

Moustakas, Theodore D. (Annandale, NJ); Maruska, H. Paul (Annandale, NJ)

1985-04-02

423

The influence of isotopically controlled boron addition on void swelling of nickel irradiated in FFTF  

NASA Astrophysics Data System (ADS)

Pure nickel specimens doped with several levels of boron-10 (10B) and natural boron (nB) were irradiated in the Materials Open Test Assembly of the Fast Flux Test Facility (FFTF/MOTA) for the purpose of examining the applicability of boron addition to the study of helium production effects. It was shown that the boron addition enhances void nucleation as its transmulation effect and suppresses as its chemical effect. The former effect is dominant at higher temperatures.

Muroga, T.; Yoshida, N.

1992-09-01

424

Excellent electrical conductivity of the exfoliated and fluorinated hexagonal boron nitride nanosheets.  

PubMed

The insulator characteristic of hexagonal boron nitride limits its applications in microelectronics. In this paper, the fluorinated hexagonal boron nitride nanosheets were prepared by doping fluorine into the boron nitride nanosheets exfoliated from the bulk boron nitride in isopropanol via a facile chemical solution method with fluoboric acid; interestingly, these boron nitride nanosheets demonstrate a typical semiconductor characteristic which were studied on a new scanning tunneling microscope-transmission electron microscope holder. Since this property changes from an insulator to a semiconductor of the boron nitride, these nanosheets will be able to extend their applications in designing and fabricating electronic nanodevices. PMID:23347409

Xue, Yafang; Liu, Qian; He, Guanjie; Xu, Kaibing; Jiang, Lin; Hu, Xianghua; Hu, Junqing

2013-01-24

425

Excellent electrical conductivity of the exfoliated and fluorinated hexagonal boron nitride nanosheets  

PubMed Central

The insulator characteristic of hexagonal boron nitride limits its applications in microelectronics. In this paper, the fluorinated hexagonal boron nitride nanosheets were prepared by doping fluorine into the boron nitride nanosheets exfoliated from the bulk boron nitride in isopropanol via a facile chemical solution method with fluoboric acid; interestingly, these boron nitride nanosheets demonstrate a typical semiconductor characteristic which were studied on a new scanning tunneling microscope-transmission electron microscope holder. Since this property changes from an insulator to a semiconductor of the boron nitride, these nanosheets will be able to extend their applications in designing and fabricating electronic nanodevices.

2013-01-01

426

Formation of cBN nanoparticles by helium, lithium and boron ion implantation  

Microsoft Academic Search

Ion induced phase transformation from the soft graphitic hexagonal boron nitride (h-BN) to ultrahard cubic boron nitride (c-BN) nanoparticles is presented in the work herein. Ion implantation was used as a technique to introduce boron lithium and helium ions, at the energy of 150keV and fluences ranging from 1×1014 to 1×1016ions\\/cm2, into hot pressed, polycrystalline h-BN. Analyses using Raman Spectroscopy

Emily Aradi; Rudolph M. Erasmus; Trevor E. Derry

427

Proton irradiation results of p+/n-/n+ Cz-Si detectors processed on p-type boron-doped substrates with thermal donor-induced space charge sign inversion  

NASA Astrophysics Data System (ADS)

When processing boron-doped p-type high-resistivity Czochralski Silicon (Cz-Si), the Thermal Donor (TD) generation process can be utilized in order to produce p+/n-/n+ detectors. The last thermal process step, i.e. the sintering of aluminum, is intentionally carried out at the temperature where TDs are created. Due to the generated donors the p-type bulk will eventually be compensated to n-type bulk. With this method it is possible, with low costs and with a process of low thermal budget, to fabricate detectors with high oxygen concentration. Moreover, the full depletion voltage of detectors could be tailored between a wide range from 30 V up to almost 1000 V by changing heat treatment duration at 400 450 °C from 20 to 80 min. The Space Charge Sign Inversion (SCSI) in the TD generated devices has been verified by the Transient Current Technique (TCT). The results of 24 GeV/c proton irradiation to fluences up to 5×1014 p/cm2 show a very small increase of full depletion voltage.

Härkönen, J.; Tuovinen, E.; Luukka, P.; Kauppinen, L.; Li, Z.; Moll, M.; Bates, A.; Kaska, K.

2005-10-01

428

Role of electrode materials for the anodic oxidation of a real landfill leachate--comparison between Ti-Ru-Sn ternary oxide, PbO(2) and boron-doped diamond anode.  

PubMed

In this paper the electrocatalytic properties of Ti-Ru-Sn ternary oxide (TiRuSnO(2)), PbO(2) and boron-doped diamond (BDD) anodes have been compared for the electrochemical oxidation of a real landfill leachate from an old municipal solid waste landfill (average values of COD 780 mg dm(-3) and NH(4)(+)-N266 mg dm(-3)). The experiments have been performed using an undivided flow cell equipped with a stainless steel cathode, under constant current of 2 A and flow-rate of 420 dm(3) h(-1). The performance of the electrodes has been compared measuring the time evolution of aromatic compounds, COD, ammonium, colour removal, current efficiency and energy consumption. The experimental results indicated that after 8 h of electrolyses TiRuSnO(2) anode yields only 35% COD, 52% colour and 65% ammonium removal. Using PbO(2) ammonium and colour were completely removed but a residual COD (i.e. 115 mg dm(-3)) was present. On the contrary BDD enables complete COD, colour and ammonium removal due to the electrogeneration of hydroxyl radicals from water discharge and active chlorine from chloride ions oxidation. BDD also exhibits greater current efficiency along with a significantly lower energy cost than other electrodes. These results indicated that the electrochemical oxidation with BDD anode is an effective process for the treatment of landfill leachate. PMID:23026163

Panizza, Marco; Martinez-Huitle, Carlos A

2012-09-29

429

Silicon LEDs with room-temperature dislocation-related luminescence, fabricated by erbium ion implantation and chemical-vapor deposition of polycrystalline silicon layers heavily doped with boron and phosphorus  

SciTech Connect

Light-emitting diodes (LEDs) have been fabricated in which optically active centers are formed by implantation of erbium ions into silicon and subsequent high-temperature annealing in an oxidizing atmosphere and the p-n junction and the ohmic contact are formed by chemical vapor deposition of polycrystalline silicon layers doped with boron and phosphorus, respectively. The luminescent properties of the LEDs have been studied. Use of polycrystalline layers makes it possible to eliminate the losses in the bulk of the light-emitting Si:Er layer. These losses are inevitable if the conventional ion implantation and diffusion methods are employed. At 80 K, the variation of electroluminescence spectra in the spectral range of the dislocation-related luminescence with the drive current is well described if the spectrum is decomposed into three Gaussian components whose peak positions and widths are current-independent and amplitudes linearly increase with the current. At 300 K, a single peak is observed in the spectral range of the dislocation-related luminescence at {approx}1.6 {mu}m.

Sobolev, N. A., E-mail: nick@sobolev.ioffe.rssi.ru; Emel'yanov, A. M.; Zabrodskii, V. V.; Zabrodskaya, N. V.; Sukhanov, V. L.; Shek, E. I. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2007-05-15

430

Why boron?  

Microsoft Academic Search

It is now more than 80 years since boron was convincingly demonstrated to be essential for normal growth of higher plants. However, its biochemical role is not well understood at the moment. Several recent reviews propose that B is implicated in three main processes: keeping cell wall structure, maintaining membrane function, and supporting metabolic activities. However, in the absence of conclusive

Luis Bolaños; Krystyna Lukaszewski; Ildefonso Bonilla; Dale Blevins

2004-01-01

431

Electron and hole trapping in doped oxides  

Microsoft Academic Search

An electron paramagnetic resonance, thermally stimulated current, and capacitance-voltage study has been carried out on phosphorus (PSG), boron (BSG), and boron and phosphorus (BPSG) co-doped oxide films on Si. The principal spin-active defects are the phosphorus-oxygen-bole-center (POHC) and the boron-oxygen-hole-center (BOHC), which are unpaired electrons on oxygen atoms with P or B in the near vicinity. The centers are activated

W. L. Warren; M. R. Shaneyfelt; D. M. Fleetwood; P. S. Winokur; S. Montague

1995-01-01

432

Radiation Effects in Graphite  

Microsoft Academic Search

The requirements for a solid moderator are reviewed and the reasons that graphite has become the solid moderator of choice discussed. The manufacture and properties of some currently available near-isotropic and isotropic grades are described. The major features of a graphite moderated reactors are briefly outlined. Displacement damage and the induced structural and dimensional changes in graphite are described. Recent

Timothy D

2012-01-01

433

Optical properties and electrical resistivity of boron-doped ZnO thin films grown by sol-gel dip-coating method  

NASA Astrophysics Data System (ADS)

Sol-gel dip-coating was used to grow ZnO thin films doped with various concentrations of B ranging from 0 to 2.5 at.% on quartz substrates. The effects of B doping on the absorption coefficient (?), optical band gap (Eg), Urbach energy (EU), refractive index (n), refractive index at infinite wavelength (n?), extinction coefficient (k), single-oscillator energy (Eo), dispersion energy (Ed), average oscillator strength (So), average oscillator wavelength (?o), moments M-1 and M-3, dielectric constant (?), optical conductivity (?), and electrical resistivity (?) of the BZO thin films were investigated. The transmittance spectra of the ZnO and BZO thin films show that the transmittance of the BZO thin films was significantly higher than that of the ZnO thin films in the visible region of the spectrum and that the absorption edge of the BZO thin films was blue-shifted. The BZO thin films exhibited higher Eg, EU, and Eo and lower Ed, ?o, M-1 and M-3 moments, So, n?, and ? than the ZnO thin films.

Kim, Soaram; Yoon, Hyunsik; Kim, Do Yeob; Kim, Sung-O.; Leem, Jae-Young

2013-10-01

434

Graphitized carbon on GaAs(100) substrates  

SciTech Connect

We report on the formation of graphitized carbon on GaAs(100) surfaces by molecular beam epitaxy. We grew highly carbon-doped GaAs on AlAs, which was then thermally etched in situ leaving behind carbon atoms on the surface. After thermal etching, Raman spectra revealed characteristic phonon modes for sp{sup 2}-bonded carbon, consistent with the formation of graphitic crystallites. We estimate that the graphitic crystallites are 1.5-3 nm in size and demonstrate that crystallite domain size can be increased through the use of higher etch temperatures.

Simon, J.; Simmonds, P. J.; Lee, M. L. [Department of Electrical Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut 06520-8284 (United States); Woodall, J. M. [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907-2035 (United States)

2011-02-14

435

"White Graphenes": Boron Nitride Nanoribbons via Boron Nitride Nanotube Unwrapping.  

PubMed

Inspired by rich physics and functionalities of graphenes, scientists have taken an intensive interest in two-dimensional (2D) crystals of h-BN (analogue of graphite, so-called "white" graphite). Recent calculations have predicted the exciting potentials of BN nanoribbons in spintronics due to tunable magnetic and electrical properties; however no experimental evidence has been provided since fabrication of such ribbons remains a challenge. Here, we show that few- and single-layered BN nanoribbons, mostly terminated with zigzag edges, can be produced under unwrapping multiwalled BN nanotubes through plasma etching. The interesting stepwise unwrapping and intermediate states were observed and analyzed. Opposed to insulating primal tubes, the nanoribbons become semiconducting due to doping-like conducting edge states and vacancy defects, as revealed by structural analyses and ab initio simulations. This study paves the way for BN nanoribbon production and usage as functional semiconductors with a wide range of applications in optoelectronics and spintronics. PMID:21028887

Zeng, Haibo; Zhi, Chunyi; Zhang, Zhuhua; Wei, Xianlong; Wang, Xuebin; Guo, Wanlin; Bando, Yoshio; Golberg, Dmitri

2010-10-28

436

Influence of silver and graphite on zinc oxide nanostructures for optical application  

NASA Astrophysics Data System (ADS)

Silver and graphite doped zinc oxide (ZnO) nanostructures were fabricated by facile and efficient direct sublimation process by employing thermal evaporation. Silver and graphite were incorporated to modify ZnO tetrapod structures for optical applications. Scanning and transmission electron microscopy techniques were used to investigate micro and nanostructures variation with doping in bare ZnO. Electrical measurements have been performed to study the conducting nature of these fascinating nanoobjects. Silver in ZnO results into flower shape multipod structure and graphite doping in ZnO results into tetrapods constituted with multiple rods like structure. Photoluminescence measurements revealed the alteration in emission towards near band edge peak with different excitation wavelength. Similar changes have been noted in UV graph by influencing the absorbance properties of the bare-ZnO with doping of silver and graphite.

Tawale, J. S.; Kumar, A.; Mohan, A.; Srivastava, A. K.

2013-05-01

437

Voltammetric behavior of benzo[a]pyrene at boron-doped diamond electrode: a study of its determination by adsorptive transfer stripping voltammetry based on the enhancement effect of anionic surfactant, sodium dodecylsulfate.  

PubMed

Benzo[a]pyrene (BaP), a member of the polycyclic aromatic hydrocarbon (PAH) class, is one of the most potent PAH carcinogens. The electrochemical oxidation of BaP was first studied by cyclic voltammetry at the boron-doped diamond electrode in non-aqueous solvent (dimethylsulphoxide with lithium perchlorate). The compound was irreversibly oxidized in a single step at high positive potential, resulting in the well-resolved formation of a couple with a reduction and re-oxidation wave at much lower potentials. Special attention was given to the use of adsorptive stripping voltammetry together with a medium exchange procedure in aqueous and aqueous/surfactant solutions over the pH range of 2.0-8.0. The technique in aqueous solutions had little value in practice because of too small oxidation peak current. This problem was solved when surfactants were added into the sample solution, by which the oxidation peak currents of BaP were found enhanced dramatically. The employed surfactants were sodium dodecylsulfate (anionic, SDS), cetyltrimethylammonium bromide (cationic, CTAB) and Tween 80 (non-ionic). Using square-wave stripping mode, the compound yielded a well-defined voltammetric response in Britton-Robinson buffer, pH 2.0 containing 2.5×10(-4)M SDS at +1.07 V (vs. Ag/AgCl) (after 120s accumulation at +0.10 V). The process could be used to determine BaP in the concentration range of 16-200 nM (4.04-50.46 ng mL(-1)), with a detection limit of 2.86 nM (0.72 ng mL(-1)). This method was also applied to determine BaP in model water sample prepared by adding its different concentrations into tap water. PMID:21645723

Yard?m, Yavuz; Levent, Abdulkadir; Keskin, Ertu?rul; Sentürk, Zühre

2011-04-08

438

Reversible Surface Two-Electron Transfer Reactions in Square Wave Voltcoulommetry: Application to the Study of the Reduction of Polyoxometalate [PMo12O40](3-) Immobilized at a Boron Doped Diamond Electrode.  

PubMed

Reversible surface two-electrons transfer reactions (stepwise processes) are analyzed using square wave voltcoulommetry (SWVC), which is a variety of square wave techniques based on the measurement of the transferred charge. Such reversible surface redox processes are exhibited by many two-redox center and multicenter biomolecules (proteins, enzymes, ...) and inorganic molecules like polyoxometalates (POMs), which have very interesting applications, mainly as electrocatalysts. Because of the stationary character of the response obtained, the key parameters that govern the cooperativity degree of the two reversible electron transfers (ETs) are the difference between their formal potentials, ?E(0), and the square wave amplitude, |ESW|, whose combined effect sets the two peaks ? one peak transition in the response. Working curves based on the variation of the peak parameters (peak potentials, half-peak widths, and peak heights) with ?E(0) and |ESW| are given, from which the formal potentials and the total surface excess can be accurately determined. SWVC has been applied to the study of the reduction of polyoxometalate [PMo12O40](3-) adsorbed at a boron doped diamond electrode (BDD), for which three stable and well-defined reversible charge peaks, corresponding to three cooperative EE processes, are obtained in the interval (0.6, -0.2) V by using low square wave frequencies. From the analysis of these peaks, the values of the total surface excess and the formal potentials of the six ETs have been obtained in aqueous media for two electrolytes: HClO4 and LiClO4. PMID:23980575

Gonzalez, Joaquin; Molina, Angela; Lopez-Tenes, Manuela; Karimian, Fereshteh

2013-08-27

439

A graphite nanoeraser  

NASA Astrophysics Data System (ADS)

We present here a method for cleaning intermediate-size (up to 50 nm) contamination from highly oriented pyrolytic graphite and graphene. Electron-beam-induced deposition of carbonaceous material on graphene and graphite surfaces inside a scanning electron microscope, which is difficult to remove by conventional techniques, can be removed by direct mechanical wiping using a graphite nanoeraser, thus drastically reducing the amount of contamination. We discuss potential applications of this cleaning procedure.

Liu, Ze; Bøggild, Peter; Yang, Jia-rui; Cheng, Yao; Grey, Francois; Liu, Yi-lun; Wang, Li; Zheng, Quan-shui

2011-07-01

440

Three-dimensional B,N-doped graphene foam as a metal-free catalyst for oxygen reduction reaction.  

PubMed

Using a modified chemical vapor deposition (CVD) method, we have prepared a class of new graphene foams (GFs) doped with nitrogen, boron or both. Nitrogen-doped graphene foams (N-GFs) with a nitrogen doping level of 3.1 atom% were prepared by CVD of CH4 in the presence of NH3 while boron-doped graphene foams (B-GFs) with a boron doping level of 2.1 atom% were produced by using toluene and triethyl borate as a carbon and a boron source. On the other hand, graphene foams co-doped with nitrogen (4.5 atom%) and boron (3 atom%) (BN-GFs) were prepared by CVD using melamine diborate as the precursor. In all cases, scanning electron microscope (SEM) images revealed well-defined foam-like microstructures, while electrochemical measurements showed much higher electrocatalytic activities toward oxygen reduction reaction for the doped graphene foams than their undoped counterparts. PMID:23770584

Xue, Yuhua; Yu, Dingshan; Dai, Liming; Wang, Ruigang; Li, Dingqiang; Roy, Ajit; Lu, Fan; Chen, Hao; Liu, Yong; Qu, Jia

2013-06-17

441

GUM Analysis for SIMS Isotopic Ratios in BEP0 Graphite Qualification Samples, Round 2  

SciTech Connect

This report describes GUM calculations for TIMS and SIMS isotopic ratio measurements of reactor graphite samples. These isotopic ratios are used to estimate reactor burn-up, and currently consist of various ratios of U, Pu, and Boron impurities in the graphite samples. The GUM calculation is a propagation of error methodology that assigns uncertainties (in the form of standard error and confidence bound) to the final estimates.

Gerlach, David C.; Heasler, Patrick G.; Reid, Bruce D.

2009-01-01

442

Method for producing dustless graphite spheres from waste graphite fines  

SciTech Connect

A method for producing graphite spheres from graphite fines by charging a quantity of spherical media into a rotatable cylindrical overcoater, charging a quantity of graphite fines into the overcoater thereby forming a first mixture of spherical media and graphite fines, rotating the overcoater at a speed such that the first mixture climbs the wall of the overcoater before rolling back down to the bottom thereby forming a second mixture of spherical media, graphite fines, and graphite spheres, removing the second mixture from the overcoater, sieving the second mixture to separate graphite spheres, charging the first mixture back into the overcoater, charging an additional quantity of graphite fines into the overcoater, adjusting processing parameters like overcoater dimensions, graphite fines charge, overcoater rotation speed, overcoater angle of rotation, and overcoater time of rotation, before repeating the steps until graphite fines are converted to graphite spheres.

Pappano, Peter J (Oak Ridge, TN); Rogers, Michael R (Clinton, TN)

2012-05-08

443

Coating method for graphite  

Microsoft Academic Search

A method of limiting carbon contamination from graphite ware used in induction melting of uranium alloys is provided. The graphite surface is coated with a suspension of YâOâ particles in water containing about 1.5 to 4 percent by weight sodium carboxymethylcellulose.

J. G. Banker; C. E. Jr. Holcombe

1975-01-01

444

Coating method for graphite  

Microsoft Academic Search

A method of limiting carbon contamination from graphite ware used in induction melting of uranium alloys is provided comprising coating the graphite surface with a suspension of YâOâ particles in water containing about 1.5 to 4 percent by weight sodium carboxymethylcellulose. 1 table.

J. G. Banker; C. E. Jr. Holcombe

1977-01-01

445

Coating method for graphite  

DOEpatents

A method of limiting carbon contamination from graphite ware used in induction melting of uranium alloys is provided comprising coating the graphite surface with a suspension of Y.sub.2 O.sub.3 particles in water containing about 1.5 to 4% by weight sodium carboxymethylcellulose.

Banker, John G. (Kingston, TN); Holcombe, Jr., Cressie E. (Knoxville, TN)

1977-01-01

446

Free radicals and graphite  

Microsoft Academic Search

The basal faces of crystalline graphite do not react with molecular oxygen at ambient or moderately raised temperatures. Free radicals, however, react with exposed graphene layers of graphites and carbon materials. Such reactions can be exploited for the functionalization of carbon surfaces. Disordered carbons, e.g. activated carbons, are slowly oxidized also at room temperature when water vapor is present. Surface

H. P. Boehm

447

THE BRAZING OF GRAPHITE  

Microsoft Academic Search

A program was conducted to develop techniques for brazing graphite to ; graphite and to metals for reactor applications. Prime difficulties are those ; associated with differences in thermal expansion coefficients. In addition, the ; requirements of acceptable wetting, high strength, and adequate compatibility ; with reactor environments must be considered. An experimental brazing alloy ; containing titanium and zirconium

R. G. Donnelly; G. M. Slaughter

1962-01-01

448

Anodic oxidation with doped diamond electrodes: a new advanced oxidation process  

Microsoft Academic Search

Boron-doped diamond anodes allow to directly produce OH radicals from water electrolysis with very high current efficiencies. This has been explained by the very high overvoltage for oxygen production and many other anodic electrode processes on diamond anodes. Additionally, the boron-doped diamond electrodes exhibit a high mechanical and chemical stability. Anodic oxidation with diamond anodes is a new advanced oxidation

Alexander Kraft; Manuela Stadelmann; Manfred Blaschke

2003-01-01

449

High Effective Gummel Number of CVD Boron Layers in Ultrashallow Diode Configurations  

Microsoft Academic Search

Deposited boron layers fabricated by exposing silicon to diborane (B2H6) gas in an atmospheric-pressure chemical vapor deposition reactor are investigated with respect to their electrical properties. At the applied temperatures from 500°C to 700°C, the deposition forms a nanometer-thick layer stack of amorphous boron (?-B) and boron-silicon compound (BxSiy), whereas the crystalline Si substrate is p-doped to depths below 10

Francesco Sarubbi; Lis K. Nanver; Tom L. M. Scholtes

2010-01-01

450

The effects of boron penetration on p+ polysilicon gated PMOS devices  

Microsoft Academic Search

The penetration of boron into and through the gate oxides of PMOS devices which employ p+ doped polysilicon gates is studied. Boron penetration results in large positive shifts in VFB , increased PMOS subthreshold slope and electron trapping rate, and decreased low-field mobility and interface trap density. Fluorine-related effects caused by BF2 implantations into the polysilicon gate are shown to

JAMES R. PFIESTER; FRANK K. BAKER; T. C. Mele; H.-H. Tseng; P. J. Tobin; J. D. Hayden; J. W. Miller; C. D. Gunderson; L. C. Parrillo

1990-01-01

451

Chemical mechanical polishing of PSG and BPSG dielectric films: the effect of phosphorus and boron concentration  

Microsoft Academic Search

Chemical-mechanical polishing of blanket and patterned oxide films doped with phosphorus and boron has been studied. FTIR was used to characterize the film microstructure. Experimental results show that an increase of phosphorus level promoted the polish rate of PSG film. We also found that increasing the boron content enhanced the polish rate of BPSG films although phosphorus contents is decreased.

Chi-Wen Liu; Bau-Tong Dai; Ching-Fa Yeh