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Sample records for boron doped graphite

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    Boron-doped graphitized carbon nanofibers (CNFs) were prepared by optimizing CNFs preparation, surface treatment, graphitization and boron-added graphitization. The interlayer spacing (d002) of the boron-doped graphitized CNFs reached 3.356 Å, similar to that of single-crystal graphite. Special platelet CNFs (PCNFs), for which d002 is less than 3.400 Å, were selected for further heat treatment. The first heat treatment of PCNFs at 2800 °C yielded a d002 between 3.357 and 3.365 Å. Successive nitric acid treatment and a second heat treatment with boric acid reduced d002 to 3.356 Å. 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.

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

    PubMed

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

    2012-08-10

    Boron-doped graphitized carbon nanofibers (CNFs) were prepared by optimizing CNFs preparation, surface treatment, graphitization and boron-added graphitization. The interlayer spacing (d₀₀₂) of the boron-doped graphitized CNFs reached 3.356 Å, similar to that of single-crystal graphite. Special platelet CNFs (PCNFs), for which d₀₀₂ is less than 3.400 Å, were selected for further heat treatment. The first heat treatment of PCNFs at 2800 °C yielded a d₀₀₂ between 3.357 and 3.365 Å. Successive nitric acid treatment and a second heat treatment with boric acid reduced d₀₀₂ to 3.356 Å. 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

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

    SciTech Connect

    Ali, Dyan; Richardson, Christopher J. K.

    2012-11-15

    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.

  4. Interaction of boron with graphite: A van der Waals density functional study

    NASA Astrophysics Data System (ADS)

    Liu, Juan; Wang, Chen; Liang, Tongxiang; Lai, Wensheng

    2016-08-01

    Boron doping has been widely investigated to improve oxidation resistance of graphite. In this work the interaction of boron with graphite is investigated by a van der Waals density-functional approach (vdW-DF). The traditional density-functional theory (DFT) is well accounted for the binding in boron-substituted graphite. However, to investigate the boron atom on graphite surface and the interstitial impurities require use of a description of graphite interlayer binding. Traditional DFT cannot describe the vdW physics, for instance, GGA calculations show no relevant binding between graphite sheets. LDA shows some binding, but they fail to provide an accurate account of vdW forces. In this paper, we compare the calculation results of graphite lattice constant and cohesive energy by several functionals, it shows that vdW-DF such as two optimized functionals optB88-vdW and optB86b-vdW give much improved results than traditional DFT. The vdW-DF approach is then applied to study the interaction of boron with graphite. Boron adsorption, substitution, and intercalation are discussed in terms of structural parameters and electronic structures. When adsorbing on graphite surface, boron behaves as π electron acceptor. The π electron approaches boron atom because of more electropositive of boron than carbon. For substitution situation, the hole introduced by boron mainly concentrates on boron and the nearest three carbon atoms. The B-doped graphite system with the hole has less ability to offer electrons to oxygen, ultimately resulted in the inhibition of carbon oxidation. For interstitial doping, vdW-DFs show more accurate formation energy than LDA. PBE functional cannot describe the interstitial boron in graphite reasonably because of the ignoring binding of graphite sheets. The investigation of electron structures of boron doped graphite will play an important role in understanding the oxidation mechanism in further study.

  5. Microstructure and electrochemical properties of boron-doped mesocarbon microbeads

    SciTech Connect

    Kim, C.; Fujino, T.; Miyashita, K.; Hayashi, T.; Endo, M.; Dresselhaus, M.S.

    2000-04-01

    The microstructure and electrochemical properties of pristine and boron-doped mesocarbon microbeads (MCMBs) were comparatively studied by X-ray diffraction, field-emission scanning electron microscopy, Raman spectroscopy, and electrochemical measurements. The authors examined the correlation between the boron-doping effect and the electrochemical properties of boron-doped MCMBs prepared at different heat-treatment temperatures. It was found that boron doping in MCMBs starts above 1,800 C, and then the substitution reaction proceeds with increasing heat-treatment temperature. The effect of boron doping is to accelerate graphitization of MCMBs for heat-treatment temperatures in the range from 1,800 to 2,500 C. Electrochemical lithium intercalation takes place at a higher potential in boron-doped MCMBs than in undoped MCMBs, presumably because the substitutional boron acts as an electron acceptor in the MCMBs.

  6. Boron doping a semiconductor particle

    SciTech Connect

    Stevens, G.D.; Reynolds, J.S.; Brown, L.K.

    1998-06-09

    A method of boron doping a semiconductor particle using boric acid to obtain a p-type doped particle. Either silicon spheres or silicon powder is mixed with a diluted solution of boric acid having a predetermined concentration. The spheres are dried, with the boron film then being driven into the sphere. A melt procedure mixes the driven boron uniformly throughout the sphere. In the case of silicon powder, the powder is metered out into piles and melted/fused with an optical furnace. Both processes obtain a p-type doped silicon sphere with desired resistivity. Boric acid is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirements. 2 figs.

  7. Boron doping a semiconductor particle

    DOEpatents

    Stevens, Gary Don; Reynolds, Jeffrey Scott; Brown, Louanne Kay

    1998-06-09

    A method (10,30) of boron doping a semiconductor particle using boric acid to obtain a p-type doped particle. Either silicon spheres or silicon powder is mixed with a diluted solution of boric acid having a predetermined concentration. The spheres are dried (16), with the boron film then being driven (18) into the sphere. A melt procedure mixes the driven boron uniformly throughout the sphere. In the case of silicon powder, the powder is metered out (38) into piles and melted/fused (40) with an optical furnace. Both processes obtain a p-type doped silicon sphere with desired resistivity. Boric acid is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirements.

  8. Boron doping of graphene-pushing the limit.

    PubMed

    Chaban, Vitaly V; Prezhdo, Oleg V

    2016-08-25

    Boron-doped derivatives of graphene have been intensely investigated because of their electronic and catalytic properties. The maximum experimentally observed concentration of boron atoms in graphite was 2.35% at 2350 K. By employing quantum chemistry coupled with molecular dynamics, we identified the theoretical doping limit for single-layer graphene at different temperatures, demonstrating that it is possible to achieve much higher boron doping concentrations. According to the calculations, 33.3 mol% of boron does not significantly undermine thermal stability, whereas 50 mol% of boron results in critical backbone deformations, which occur when three or more boron atoms enter the same six-member ring. Even though boron is less electro-negative than carbon, it tends to act as an electron acceptor in the vicinity of C-B bonds. The dipole moment of B-doped graphene depends strongly on the distribution of dopant atoms within the sheet. Compared with N-doped graphene, the dopant-dopant bonds are less destructive in the present system. The reported results motivate efforts to synthesize highly B-doped graphene for semiconductor and catalytic applications. The theoretical predictions can be validated through direct chemical synthesis. PMID:27533648

  9. Development and evaluation of graphite and boron polyimide composites.

    NASA Technical Reports Server (NTRS)

    Scheck, W. G.; Stuckey, J. M.

    1972-01-01

    This paper covers the development and evaluation of the HT-S/710 graphite/polyimide system and initial evaluations of high modulus graphite and boron reinforced polyimide systems. Detail design properties of the HT-S/710 graphite/polyimide systems, test results of test sheet stringer components, and initial test evaluations of high modulus graphite and boron reinforced polyimide composites are presented. Preliminary design applications utilizing the basic processing and design data from this development program are presented as to their utilization in aircraft and space applications.

  10. Ultratough single crystal boron-doped diamond

    DOEpatents

    Hemley, Russell J [Carnegie Inst. for Science, Washington, DC ; Mao, Ho-Kwang [Carnegie Inst. for Science, Washington, DC ; Yan, Chih-Shiue [Carnegie Inst. for Science, Washington, DC ; Liang, Qi [Carnegie Inst. for Science, Washington, DC

    2015-05-05

    The invention relates to a single crystal boron doped CVD diamond that has a toughness of at least about 22 MPa m.sup.1/2. The invention further relates to a method of manufacturing single crystal boron doped CVD diamond. The growth rate of the diamond can be from about 20-100 .mu.m/h.

  11. Stabilization of boron carbide via silicon doping

    NASA Astrophysics Data System (ADS)

    Proctor, J. E.; Bhakhri, V.; Hao, R.; Prior, T. J.; Scheler, T.; Gregoryanz, E.; Chhowalla, M.; Giulani, F.

    2015-01-01

    Boron carbide is one of the lightest and hardest ceramics, but its applications are limited by its poor stability against a partial phase separation into separate boron and carbon. Phase separation is observed under high non-hydrostatic stress (both static and dynamic), resulting in amorphization. The phase separation is thought to occur in just one of the many naturally occurring polytypes in the material, and this raises the possibility of doping the boron carbide to eliminate this polytype. In this work, we have synthesized boron carbide doped with silicon. We have conducted a series of characterizations (transmission electron microscopy, scanning electron microscopy, Raman spectroscopy and x-ray diffraction) on pure and silicon-doped boron carbide following static compression to 50 GPa non-hydrostatic pressure. We find that the level of amorphization under static non-hydrostatic pressure is drastically reduced by the silicon doping.

  12. Method for wetting a boron alloy to graphite

    DOEpatents

    Storms, E.K.

    1987-08-21

    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.

  13. Characterisation of graphite using boron as a marker element

    SciTech Connect

    Kamble, Granthali S.; Pandey, Shailaja; Thakur, Neha; Kumar, Sanjukta A.; Venkatesh, K.; Kumar, Sangita D.; Kameswaran, R.; Reddy, A. V. R.

    2013-06-12

    Graphite has many industrial applications. Two of the most important applications are as electrodes in industries and as moderator in nuclear industry. Determination of the Boron Equivalent of the impurity elements in graphite is the most important parameter for certifying the grade of graphite electrode [1]. The use of a suitable method with low limits of determination of boron is therefore necessary. A method has been standardised in Analytical Chemistry Division, BARC for determining trace amounts of boron in graphite electrodes. It involves controlled dissolution of graphite sample powder and measurement of boron by Inductively Coupled Plasma Mass Spectrometer (ICP-MS) using matrix matched standards. The method detection limit is 1 {mu}g g{sup -1}. The method Relative Standard Deviation was 5%. The method was verified by spike recovery experiments. Recoveries were found to be within 100{+-}2% in the concentration range of 1 to 100 {mu}g g{sup -1}. The developed method has been adopted for the compositional characterization of several graphite electrode samples.

  14. Catalyst-free synthesis of crumpled boron and nitrogen co-doped graphite layers with tunable bond structure for oxygen reduction reaction.

    PubMed

    Jin, Jutao; Pan, Fuping; Jiang, Luhua; Fu, Xiaogang; Liang, Aiming; Wei, Zhiyang; Zhang, Junyan; Sun, Gongquan

    2014-04-22

    Two-dimensional materials based on ternary system of B, C and N are useful ranging from electric devices to catalysis. The bonding arrangement within these BCN nanosheets largely determines their electronic structure and thus chemical and (or) physical properties, yet it remains a challenge to manipulate their bond structures in a convenient and controlled manner. Recently, we developed a synthetic protocol for the synthesis of crumpled BCN nanosheets with tunable B and N bond structure using urea, boric acid and polyethylene glycol (PEG) as precursors. By carefully selecting the synthesis condition, we can tune the structure of BCN sheets from s-BCN with B and N bond together to h-BCN with B and N homogenously dispersed in BCN sheets. Detailed experiments suggest that the final bond structure of B and N in graphene depends on the preferentially doped N structure in BCN nanosheets. When N substituted the in-plane carbon atom with all its electrons configured into the π electron system of graphene, it facilitates the formation of h-BCN with B and N in separated state. On the contrary, when nitrogen substituted the edge-plane carbon with the nitrogen dopant surrounded with the lone electron pairs, it benefits for the formation of B-N structure. Specially, the compound riched with h-BCN shows excellent ORR performance in alkaline solution due to the synergistic effect between B and N, while s-BCN dominant BCN shows graphite-like activity for ORR, suggesting the intrinsic properties differences of BCN nanosheets with different dopants bond arrangement. PMID:24601550

  15. Structure and functionality of bromine doped graphite.

    PubMed

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

    2013-04-28

    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. PMID:23635160

  16. Structure and functionality of bromine doped graphite

    SciTech Connect

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

    2013-04-28

    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 (Br{sub 2}). However, with increased compression (decreased layer-layer separation) Br{sub 2} 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 Br{sub 2} molecules. Electron transfer to the Br atoms increases the number of hole carriers in the graphite sheets, resulting in an increase of conductivity.

  17. Thermal diffusion boron doping of single-crystal natural diamond

    NASA Astrophysics Data System (ADS)

    Seo, Jung-Hun; Wu, Henry; Mikael, Solomon; Mi, Hongyi; Blanchard, James P.; Venkataramanan, Giri; Zhou, Weidong; Gong, Shaoqin; Morgan, Dane; Ma, Zhenqiang

    2016-05-01

    With the best overall electronic and thermal properties, single crystal diamond (SCD) is the extreme wide bandgap material that is expected to revolutionize power electronics and radio-frequency electronics in the future. However, turning SCD into useful semiconductors requires overcoming doping challenges, as conventional substitutional doping techniques, such as thermal diffusion and ion implantation, are not easily applicable to SCD. Here we report a simple and easily accessible doping strategy demonstrating that electrically activated, substitutional doping in SCD without inducing graphitization transition or lattice damage can be readily realized with thermal diffusion at relatively low temperatures by using heavily doped Si nanomembranes as a unique dopant carrying medium. Atomistic simulations elucidate a vacancy exchange boron doping mechanism that occurs at the bonded interface between Si and diamond. We further demonstrate selectively doped high voltage diodes and half-wave rectifier circuits using such doped SCD. Our new doping strategy has established a reachable path toward using SCDs for future high voltage power conversion systems and for other novel diamond based electronic devices. The novel doping mechanism may find its critical use in other wide bandgap semiconductors.

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

    PubMed

    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

    2013-10-01

    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

  19. Ni doping of semiconducting boron carbide

    SciTech Connect

    Hong, Nina; Liu Jing; Adenwalla, S.; Langell, M. A.; Kizilkaya, Orhan

    2010-01-15

    The wide band gap, temperature stability, high resistivity, and robustness of semiconducting boron carbide make it an attractive material for device applications. Undoped boron carbide is p type; Ni acts as a n-type dopant. Here we present the results of controlled doping of boron carbide with Ni on thin film samples grown using plasma enhanced chemical vapor deposition. The change in the dopant concentration within the thin film as a function of the dopant flow rate in the precursor gas mixture was confirmed by x-ray photoelectron spectroscopy measurements; with increasing dopant concentration, current-voltage (I-V) curves clearly establish the trend from p-type to n-type boron carbide.

  20. Measured Enthalpies of Adsorption of Boron-Doped Activated Carbons

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

    There is significant interest in the properties of boron-doped activated carbons for their potential to improve hydrogen storage.ootnotetextMultiply Surface-Functionalized Nanoporous Carbon for Vehicular Hydrogen Storage, P. Pfeifer et al. DOE Hydrogen Program 2011 Annual Progress Report, IV.C.3, 444-449 (2011). Boron-doped activated carbons have been produced using a process involving the pyrolysis of decaborane (B10H14) 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' structure, hydrogen sorption, and surface chemistry. Initial room temperature experiments show a 20% increase in the hydrogen excess adsorption per surface area compared to the undoped material. Experimental enthalpies of adsorption will be presented for comparison to theoretical predictions for boron-doped carbon materials. Additionally, results from a modified version of the doping process will be presented.

  1. Green synthesis of boron doped graphene and its application as high performance anode material in Li ion battery

    SciTech Connect

    Sahoo, Madhumita; Sreena, K.P.; Vinayan, B.P.; Ramaprabhu, S.

    2015-01-15

    Graphical abstract: Boron doped graphene (B-G), synthesized by simple hydrogen induced reduction technique using boric acid as boron precursor, have more uneven surface as a result of smaller bonding distance of boron compared to carbon, showed high capacity and high rate capability compared to pristine graphene as an anode material for Li ion battery application. - Abstract: The present work demonstrates a facile route for the large-scale, catalyst free, and green synthesis approach of boron doped graphene (B-G) and its use as high performance anode material for Li ion battery (LIB) application. Boron atoms were doped into graphene framework with an atomic percentage of 5.93% via hydrogen induced thermal reduction technique using graphite oxide and boric acid as precursors. Various characterization techniques were used to confirm the boron doping in graphene sheets. B-G as anode material shows a discharge capacity of 548 mAh g{sup −1} at 100 mA g{sup −1} after 30th cycles. At high current density value of 1 A g{sup −1}, B-G as anode material enhances the specific capacity by about 1.7 times compared to pristine graphene. The present study shows a simplistic way of boron doping in graphene leading to an enhanced Li ion adsorption due to the change in electronic states.

  2. Boron-doped graphene as a promising anode for Na-ion batteries.

    PubMed

    Ling, Chen; Mizuno, Fuminori

    2014-06-14

    The Na-ion battery has recently gained a lot of interest as a low-cost alternative to the current Li-ion battery technology. Its feasibility strongly depends on the development of suitable electrode materials. In the present work we propose a novel anode candidate, boron-doped graphene, for the Na-ion battery. Our first-principles calculations demonstrate that the sodiation of boron-doped graphene well preserves its structural integrity. The 2D-BC3 anode has the average sodiation voltage of 0.44 V in an appropriate range to avoid the safety concerns caused by the formation of dendritic deposits. The capacity of the 2D-BC3 anode reaches ∼2.04 times that of the graphite anode in a Li-ion battery and ∼2.52 times that of hard carbon in a Na-ion battery. The high electronic mobility and Na mobility on boron-doped graphene indicates that it has a high potential to reach good rate performance. These suggest the promising potential of boron-doped graphene to serve as an anode for a rechargeable Na-ion battery. PMID:24760182

  3. Terahertz emission from silicon nanostructures heavily doped with boron

    NASA Astrophysics Data System (ADS)

    Bagraev, Nikolay T.; Danilovskii, Eduard Yu; Gets, Dmitrii S.; Kaveev, Andrey K.; Klyachkin, Leonid E.; Kropotov, Grigorii I.; Kudryavtsev, Andrey A.; Kuzmin, Roman V.; Malyarenko, Anna M.; Mashkov, Vladimir A.; Tsibizov, Ivan A.; Tsypishka, Dmitrii I.; Vinerov, Ilya A.

    2014-03-01

    We present the first findings of the terahertz emission from the ultra-narrow p-type silicon quantum well confined by the δ-barriers heavily doped with boron on the n-type Si (100) surface. The THz spectra revealed by the voltage applied along the Si-QW plane appear to result from the radiation of the dipole boron centers.

  4. Spontaneous Boron-doping of Graphene at Room Temperature

    NASA Astrophysics Data System (ADS)

    Pan, Lida; Que, Yande; Du, Shixuan; Gao, Hongjun; Pantelides, Sokrates T.

    2015-03-01

    Doping graphene with boron or nitrogen is an effective way to modify its electronic properties. However, the reaction barrier for introducing these impurities is quite high, making the doping process difficult. In this work, we propose a low-energy reaction route derived from first-principles calculations and subsequently validated by experiments. The calculations show that, when graphene is placed on a ruthenium substrate and exposed to atomic boron, boron atoms can incorporate substitutionally into the graphene sheet with an energy barrier about 0.1 eV, displacing carbon atoms below the graphene sheet where they migrates away. This result suggests that spontaneous doping by boron can take place at room temperature. Following the prediction, we grew high-quality graphene on the Ru(0001) surface and then expose it to B2H6 which decomposes into atomic boron. XPS and STM results indicate that boron dopes graphene substantially without disturbing the graphene lattice, confirming the theoretical predictions. Doping by nitrogen and co-doping by B and N will also be discussed.

  5. Flexible Boron-Doped Laser-Induced Graphene Microsupercapacitors.

    PubMed

    Peng, Zhiwei; Ye, Ruquan; Mann, Jason A; Zakhidov, Dante; Li, Yilun; Smalley, Preston R; Lin, Jian; Tour, James M

    2015-06-23

    Heteroatom-doped graphene materials have been intensely studied as active electrodes in energy storage devices. Here, we demonstrate that boron-doped porous graphene can be prepared in ambient air using a facile laser induction process from boric acid containing polyimide sheets. At the same time, active electrodes can be patterned for flexible microsupercapacitors. As a result of boron doping, the highest areal capacitance of as-prepared devices reaches 16.5 mF/cm(2), 3 times higher than nondoped devices, with concomitant energy density increases of 5-10 times at various power densities. The superb cyclability and mechanical flexibility of the device are well-maintained, showing great potential for future microelectronics made from this boron-doped laser-induced graphene material. PMID:25978090

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

    SciTech Connect

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

    1997-10-01

    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.

  7. Efficient method for Li doping of α-rhombohedral boron

    NASA Astrophysics Data System (ADS)

    Dekura, H.; Shirai, K.; Yanase, A.

    2011-09-01

    Li doping is a promising method for achieving metallization of α-rhombohedral boron (α-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 α-boron, even though there are theoretical predictions claiming that it should be easy. This discrepancy has been systematically studied by the ab initio pseudopotential method through calculations of various structural and phonon properties of the material. For this study, a comparison with β-boron is important because experimental data are available in this case. The present results demonstrate that while Li doping is difficult for α-boron under normal conditions, it is easy for β-boron, which is completely consistent with experiments. The difference between these crystals originates from the contrasting characteristics of the bonding. For α-boron, the bonding requirement of the host crystal is fulfilled so well that the only way for a Li atom to enter the crystal is through the antibonding states. Electronically, this is favorable because it causes an almost perfect rigid-band shift without modifying the bonding nature of the host crystal. In terms of structural effects, Li doping causes a slight decrease in the cell angle αrh as well as softening of the elastic properties. A striking effect of Li doping is manifested in substantial phonon softening of the librational mode. These changes can be regarded as reliable criteria for the experimental detection of Li inclusion. On the other hand, β-boron can be characterized as a frustrated system, and the crystal has a propensity to welcome guest atoms in order to eliminate ill-connected bonds. As a result, even though Li is easily incorporated into β-boron, the carriers are not activated for electrical conduction. The remaining problem is how to overcome the difficulty of Li doping of α-boron. The most important contribution of this study lies in demonstrating the

  8. Boron doped polycrystalline diamond films for strain sensing applications

    SciTech Connect

    Wur, D.; Davidson, J.L.; Kang, W.P.

    1995-12-31

    It has been recently established in our work and others that boron-doped polycrystalline diamond films (PDF) have piezoresistivity (PZR). This property opens PDF to the field of sensor applications using strain sensing. Polycrystalline diamond films have been prepared with microwave plasma enhanced chemical vapor deposition (CVD) method and boron-doped to p-type semiconductors. In addition, by combining the piezoresistive effect in doped PDF and the insulating property of undoped PDF, whereby doped diamond resistors reside on a dielectric diamond substrate diaphragm, a monolithic all-diamond microstructure for examining the strain response of patterned p-doped diamond PZRs was fabricated and characterized. This work examines some critical issues of diamond for strain sensing applications such as its rupture stress and edge stress of diamond diaphragm and the high temperature responses of a diamond strain sensor.

  9. Pairwise cobalt doping of boron carbides with cobaltocene

    NASA Astrophysics Data System (ADS)

    Ignatov, A. Yu.; Losovyj, Ya. B.; Carlson, L.; LaGraffe, D.; Brand, J. I.; Dowben, P. A.

    2007-10-01

    We have performed Co K-edge x-ray absorption fine structure and x-ray absorption near edge structure measurements of Co-doped plasma enhanced chemical vapor phase deposition (PECVD) grown "C2B10Hx" semiconducting boron carbides, using cobaltocene. Cobalt does not dope PECVD grown boron carbides as a random fragment of the cobaltocene source gas. The Co atoms are fivefold boron coordinated (R=2.10±0.02Å) and are chemically bonded to the icosahedral cages of B10CHx or B9C2Hy. Pairwise Co doping occurs, with the cobalt atoms favoring sites some 5.28±0.02Å apart.

  10. Pairwise cobalt doping of boron carbides with cobaltocene

    SciTech Connect

    Ignatov, A. Yu.; Losovyj, Ya. B.; Carlson, L.; LaGraffe, D.; Brand, J. I.; Dowben, P. A.

    2007-10-15

    We have performed Co K-edge x-ray absorption fine structure and x-ray absorption near edge structure measurements of Co-doped plasma enhanced chemical vapor phase deposition (PECVD) grown 'C{sub 2}B{sub 10}H{sub x}' semiconducting boron carbides, using cobaltocene. Cobalt does not dope PECVD grown boron carbides as a random fragment of the cobaltocene source gas. The Co atoms are fivefold boron coordinated (R=2.10{+-}0.02 A) and are chemically bonded to the icosahedral cages of B{sub 10}CH{sub x} or B{sub 9}C{sub 2}H{sub y}. Pairwise Co doping occurs, with the cobalt atoms favoring sites some 5.28{+-}0.02 A apart.

  11. Transforming chitosan into N-doped graphitic carbon electrocatalysts.

    PubMed

    Wu, T X; Wang, G Z; Zhang, X; Chen, C; Zhang, Y X; Zhao, H J

    2015-01-25

    Chitosan, the only alkaline polysaccharide in nature with rich nitrogen content, is used as the sole precursor to obtain N-doped graphitic carbon-based ORR electrocatalysts. The findings of this work demonstrate that cheap, plentiful and renewable biomasses can be transformed into high value functional carbon materials. PMID:25486248

  12. Boron and nitrogen doping in graphene antidot lattices

    NASA Astrophysics Data System (ADS)

    Brun, Søren J.; Pereira, Vitor M.; Pedersen, Thomas G.

    2016-06-01

    Bottom-up fabrication of graphene antidot lattices (GALs) has previously yielded atomically precise structures with subnanometer periodicity. Focusing on this type of experimentally realized GAL, we perform density functional theory calculations on the pristine structure as well as GALs with edge carbon atoms substituted with boron or nitrogen. We show that p - and n -type doping levels emerge with activation energies that depend on the level of hydrogenation at the impurity. Furthermore, a tight-binding parametrization together with a Green's function method are used to describe more dilute doping. Finally, random configurations of impurities in moderately doped systems are considered to show that the doping properties are robust against disorder.

  13. Boron-doped superlattices and Bragg mirrors in diamond

    SciTech Connect

    Fiori, A.; Bousquet, J.; Eon, D.; Omnès, F.; Bustarret, E.; Bellet-Amalric, E.

    2014-08-25

    A periodic modulation of the boron doping level of single crystal diamond multilayers over more than three orders of magnitude during epitaxial growth by microwave plasma-enhanced chemical vapor deposition is shown to yield Bragg mirrors in the visible. The thicknesses and doping level of the individual layers were controlled by in situ spectroscopic ellipsometry, enabling to tune the reflectance peak to the wavelength range of diamond color centers, such as NV{sup 0} or NV{sup −}. The crystalline quality, periodicity, and sharpness of the doping transitions in these doping superlattices over tens of periods were confirmed by high resolution X-ray diffraction.

  14. Temperature admittance spectroscopy of boron doped chemical vapor deposition diamond

    NASA Astrophysics Data System (ADS)

    Zubkov, V. I.; Kucherova, O. V.; Bogdanov, S. A.; Zubkova, A. V.; Butler, J. E.; Ilyin, V. A.; Afanas'ev, A. V.; Vikharev, A. L.

    2015-10-01

    Precision admittance spectroscopy measurements over wide temperature and frequency ranges were carried out for chemical vapor deposition epitaxial diamond samples doped with various concentrations of boron. It was found that the experimentally detected boron activation energy in the samples decreased from 314 meV down to 101 meV with an increase of B/C ratio from 600 to 18000 ppm in the gas reactants. For the heavily doped samples, a transition from thermally activated valence band conduction to hopping within the impurity band (with apparent activation energy 20 meV) was detected at temperatures 120-150 K. Numerical simulation was used to estimate the impurity DOS broadening. Accurate determination of continuously altering activation energy, which takes place during the transformation of conduction mechanisms, was proposed by numerical differentiation of the Arrhenius plot. With increase of boron doping level the gradual decreasing of capture cross section from 3 × 10-13 down to 2 × 10-17 cm2 was noticed. Moreover, for the hopping conduction the capture cross section becomes 4 orders of magnitude less (˜2 × 10-20 cm2). At T > Troom in doped samples the birth of the second conductance peak was observed. We attribute it to a defect, related to the boron doping of the material.

  15. Temperature admittance spectroscopy of boron doped chemical vapor deposition diamond

    SciTech Connect

    Zubkov, V. I. Kucherova, O. V.; Zubkova, A. V.; Ilyin, V. A.; Afanas'ev, A. V.; Bogdanov, S. A.; Vikharev, A. L.; Butler, J. E.

    2015-10-14

    Precision admittance spectroscopy measurements over wide temperature and frequency ranges were carried out for chemical vapor deposition epitaxial diamond samples doped with various concentrations of boron. It was found that the experimentally detected boron activation energy in the samples decreased from 314 meV down to 101 meV with an increase of B/C ratio from 600 to 18000 ppm in the gas reactants. For the heavily doped samples, a transition from thermally activated valence band conduction to hopping within the impurity band (with apparent activation energy 20 meV) was detected at temperatures 120–150 K. Numerical simulation was used to estimate the impurity DOS broadening. Accurate determination of continuously altering activation energy, which takes place during the transformation of conduction mechanisms, was proposed by numerical differentiation of the Arrhenius plot. With increase of boron doping level the gradual decreasing of capture cross section from 3 × 10{sup −13} down to 2 × 10{sup −17} cm{sup 2} was noticed. Moreover, for the hopping conduction the capture cross section becomes 4 orders of magnitude less (∼2 × 10{sup −20} cm{sup 2}). At T > T{sub room} in doped samples the birth of the second conductance peak was observed. We attribute it to a defect, related to the boron doping of the material.

  16. Boron doping of diamond powder by enhanced diffusion and forced diffusion: Diffusion concentrations, mechanical, chemical and optical properties

    NASA Astrophysics Data System (ADS)

    Golshani, Fariborz

    Diamond, with its unique mechanical properties, is an excellent material for a wide range of applications. However, there exist some problems. One such problem is integration of diamond of diamond into tool's (usually tungsten-carbide) lattice matrix for the purpose of increasing its performance. The presence of cobalt in the matrix, which acts as a poison for diamond, causes graphitization and degradation of diamond. In addition, diamond graphitizes at sintering temperatures (1770 K). The results of this work suggest that boron has produced a protective layer for diamond, thus reducing the effects of annealing at high temperatures. Boron has been introduced into single crystal high pressure, high temperature diamond powder by enhanced diffusion and forced diffusion techniques. Enhanced diffusion resulted in higher concentrations of boron in diamond powder. Total boron concentrations of 500 to 600 ppm, and 10sp{20} cmsp{-3} at a depth of 0.5 micrometer, have been achieved. Hardness tests performed on doped samples reveal that diamond did not lose its strength due to diffusion at elevated temperatures. Raman spectroscopy and X-ray diffraction analysis did not show any change in the "quality" of diamond due to doping. Oxidation experiments performed on doped and undoped samples revealed that the samples with the highest boron concentrations had superior performance and resistance to oxidation. Final weight loss in these samples was much less than in undoped samples and samples with low boron concentrations. Scanning electron microscopy of these samples showed that degradation due to oxidation of heavily doped diamond samples was significantly less than other samples.

  17. Synthesis and thermoluminescence of boron-doped germanium nanowires

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    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 B 2H 6 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.

  18. Room-Temperature, Low-Barrier Boron Doping of Graphene.

    PubMed

    Pan, Lida; Que, Yande; Chen, Hui; Wang, Dongfei; Li, Jun; Shen, Chengmin; Xiao, Wende; Du, Shixuan; Gao, Hongjun; Pantelides, Sokrates T

    2015-10-14

    Doping graphene with boron has been difficult because of high reaction barriers. Here, we describe a low-energy reaction route derived from first-principles calculations and validated by experiments. We find that a boron atom on graphene on a ruthenium(0001) substrate can replace a carbon by pushing it through, with substrate attraction helping to reduce the barrier to only 0.1 eV, implying that the doping can take place at room temperature. High-quality graphene is grown on a Ru(0001) surface and exposed to B2H6. Scanning tunneling microscopy/spectroscopy and X-ray photoelectron spectroscopy confirmed that boron is indeed incorporated substitutionally without disturbing the graphene lattice. PMID:26348981

  19. Oxidation Resistant Graphite Studies

    SciTech Connect

    W. Windes; R. Smith

    2014-07-01

    The Very High Temperature Reactor (VHTR) Graphite Research and Development Program is investigating doped nuclear graphite grades exhibiting oxidation resistance. During a oxygen ingress accident the oxidation rates of the high temperature graphite core region would be extremely high resulting in significant structural damage to the core. Reducing the oxidation rate of the graphite core material would reduce the structural effects and keep the core integrity intact during any air-ingress accident. Oxidation testing of graphite doped with oxidation resistant material is being conducted to determine the extent of oxidation rate reduction. Nuclear grade graphite doped with varying levels of Boron-Carbide (B4C) was oxidized in air at nominal 740°C at 10/90% (air/He) and 100% air. The oxidation rates of the boronated and unboronated graphite grade were compared. With increasing boron-carbide content (up to 6 vol%) the oxidation rate was observed to have a 20 fold reduction from unboronated graphite. Visual inspection and uniformity of oxidation across the surface of the specimens were conducted. Future work to determine the remaining mechanical strength as well as graphite grades with SiC doped material are discussed.

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

    NASA Astrophysics Data System (ADS)

    Carlson, Lonnie

    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

  1. Phase transformations of nano-sized cubic boron nitride to white graphene and white graphite

    SciTech Connect

    Dang, Hongli; Liu, Yingdi; Xue, Wenhua; Anderson, Ryan S.; Sewell, Cody R.; Xue, Sha; Crunkleton, Daniel W.; Shen, Yaogen; Wang, Sanwu

    2014-03-03

    We report quantum-mechanical investigations that predict the formation of white graphene and nano-sized white graphite from the first-order phase transformations of nano-sized boron nitride thin-films. The phase transformations from the nano-sized diamond-like structure, when the thickness d > 1.4 nm, to the energetically more stable nano-sized white graphite involve low activation energies of less than 1.0 eV. On the other hand, the diamond-like structure transforms spontaneously to white graphite when d ≤ 1.4 nm. In particular, the two-dimensional structure with single-layer boron nitride, the so-called white graphene, could be formed as a result of such transformation.

  2. Water dispersible, highly graphitic and nitrogen-doped carbon nanobubbles.

    PubMed

    Soll, Sebastian; Fellinger, Tim-Patrick; Wang, Xinchen; Zhao, Qiang; Antonietti, Markus; Yuan, Jiayin

    2013-12-20

    Dispersible, highly graphitic, and nitrogen-doped carbon hollow nanospheres (25-90 nm), termed 'nanobubbles', are prepared via confined carbonization through a silica nanocasting technique. Poly(ionic liquid) nanoparticles are employed as easy-to-make and multifunctional templates, which simultaneously act as both the carbon and nitrogen source. The promising potential of the nanobubbles in oxygen reduction reactions for fuel cells is demonstrated. PMID:23847129

  3. Chemical mechanical polishing of boron-doped polycrystalline silicon

    NASA Astrophysics Data System (ADS)

    Pirayesh, Hamidreza; Cadien, Kenneth

    2014-03-01

    Chemical mechanical polishing (CMP) is a technique which helps to print a smaller depth of focus and smoother surface in micro fabrication industry. In this project, boron doped polysilicon is used as a fill material for Through Silicon Vias (TSV) creating a 3D package. It is shown that the presence of boron as dopant suppresses the polysilicon polish rate. To increase the polish rate, understanding the mechanism of polish rate retardation is essential. We believe that the electrical effects play the major role in this phenomenon and by reducing this effect we are able to increase the polish rate.

  4. Carrier doping into boron nanobelts by neutron transmutation

    SciTech Connect

    Kirihara, Kazuhiro; Shimizu, Yoshiki; Sasaki, Takeshi; Koshizaki, Naoto; Yamada, Yoichi; Esaka, Fumitaka; Yamamoto, Hiroyuki; Shamoto, Shin-ichi; Kimura, Kaoru

    2010-11-22

    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.

  5. Peculiarities of boron distribution in as-grown boron-doped diamond

    NASA Astrophysics Data System (ADS)

    Blank, V. D.; Kulnitskiy, B. A.; Perezhogin, I. A.; Terentiev, S. A.; Nosukhin, S. A.; Kuznetsov, M. S.

    2014-09-01

    Boron doped diamond (BDD) single crystals have been grown under conditions of high isostatic pressure by the temperature gradient method. Numerous equilateral triangles were found on the fluorescence images of {111}-diamond facets. Structural peculiarities of BDD were investigated by JEM-2010 transmission electron microscope with GIF Quantum attachment for electron energy loss spectroscopy (EELS). High resolution image of diamond lattice revealed some distorted {111}-layers. EELS testifies the presence of boron in distorted regions of diamond lattice. The crystallographic features of BDD and their connection with the superconductivity are discussed.

  6. Photoelectron Spectroscopy of Aluminum Doped Boron Clusters

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    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 σ - and π -electron delocalizations throughout the molecular plane, giving rise to concepts of σ - and π -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)

  7. Co-doping of CVD diamond with boron and sulfur

    NASA Astrophysics Data System (ADS)

    Eaton, Sally Catherine

    Boron is well-established as a p-type dopant in diamond, but attempts to find a viable n-type dopant remain unsuccessful. In 1999, sulfur was reported to give n-type conductivity. However, later measurements indicated that the samples contained boron and were p-type. Recently, we showed that diamond co-doped with sulfur and small quantities of boron shows n-type conductivity, which was established by Mott-Schottky analyses, thermoelectric effect, Hall measurements, scanning tunneling spectroscopy (STS), and UV open-circuit photo-potential. At higher boron concentrations, a transition to p-type behavior is observed due to overcompensation. Experiments performed without boron in the feed gas or without residual boron in the reactor chamber showed no sulfur incorporation and no change in conductivity. There is evidence that the excess sulfur concentration in the near-surface region is not stable. At room temperature and below, the activation energies range from 0.06 to 0.12 eV. Above 400K there is an irreversible loss in conductivity and the activation energy increases to approximately 1.3 eV. Additionally, we observed by SIMS that there exists a concentration gradient in sulfur with film depth. This sulfur concentration gradient is also observed in our electrical measurements. STS shows a decrease in conductivity with film depth and Hall effect measurements show both p-type and n-type coefficients for samples which are n-type in the near-surface region. The flat-band potential obtained from the Mott-Schottky experiments is only 1 to 1.5 V more negative on the electrochemical scale than that for boron-doped diamond. This implies that the Fermi level is only 1 to 1.5 eV higher than the Fermi level in boron-doped diamond. This observation implies that the n-type conductivity is not by excitation of electrons to the conduction band, but by an alternate mechanism that occurs in the middle of the band gap. One such possibility is an acceptor impurity band. Electrons from

  8. Electrochemical hydrogen termination of boron-doped diamond

    SciTech Connect

    Hoffmann, Rene; Kriele, Armin; Obloh, Harald; Hees, Jakob; Wolfer, Marco; Smirnov, Waldemar; Yang Nianjun; Nebel, Christoph E.

    2010-08-02

    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).

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

    PubMed

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

    2012-11-14

    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

  10. Chemical reaction of hexagonal boron nitride and graphite nanoclusters in mechanical milling systems

    SciTech Connect

    Muramatsu, Y.; Grush, M.; Callcott, T.A.

    1997-04-01

    Synthesis of boron-carbon-nitride (BCN) hybrid alloys has been attempted extensively by many researchers because the BCN alloys are considered an extremely hard material called {open_quotes}super diamond,{close_quotes} and the industrial application for wear-resistant materials is promising. A mechanical alloying (MA) method of hexagonal boron nitride (h-BN) with graphite has recently been studied to explore the industrial synthesis of the BCN alloys. To develop the MA method for the BCN alloy synthesis, it is necessary to confirm the chemical reaction processes in the mechanical milling systems and to identify the reaction products. Therefore, the authors have attempted to confirm the chemical reaction process of the h-BN and graphite in mechanical milling systems using x-ray absorption near edge structure (XANES) methods.

  11. Atomically controlled substitutional boron-doping of graphene nanoribbons

    PubMed Central

    Kawai, Shigeki; Saito, Shohei; Osumi, Shinichiro; Yamaguchi, Shigehiro; Foster, Adam S.; Spijker, Peter; Meyer, Ernst

    2015-01-01

    Boron is a unique element in terms of electron deficiency and Lewis acidity. Incorporation of boron atoms into an aromatic carbon framework offers a wide variety of functionality. However, the intrinsic instability of organoboron compounds against moisture and oxygen has delayed the development. Here, we present boron-doped graphene nanoribbons (B-GNRs) of widths of N=7, 14 and 21 by on-surface chemical reactions with an employed organoboron precursor. The location of the boron dopant is well defined in the centre of the B-GNR, corresponding to 4.8 atom%, as programmed. The chemical reactivity of B-GNRs is probed by the adsorption of nitric oxide (NO), which is most effectively trapped by the boron sites, demonstrating the Lewis acid character. Structural properties and the chemical nature of the NO-reacted B-GNR are determined by a combination of scanning tunnelling microscopy, high-resolution atomic force microscopy with a CO tip, and density functional and classical computations. PMID:26302943

  12. Atomically controlled substitutional boron-doping of graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Kawai, Shigeki; Saito, Shohei; Osumi, Shinichiro; Yamaguchi, Shigehiro; Foster, Adam S.; Spijker, Peter; Meyer, Ernst

    2015-08-01

    Boron is a unique element in terms of electron deficiency and Lewis acidity. Incorporation of boron atoms into an aromatic carbon framework offers a wide variety of functionality. However, the intrinsic instability of organoboron compounds against moisture and oxygen has delayed the development. Here, we present boron-doped graphene nanoribbons (B-GNRs) of widths of N=7, 14 and 21 by on-surface chemical reactions with an employed organoboron precursor. The location of the boron dopant is well defined in the centre of the B-GNR, corresponding to 4.8 atom%, as programmed. The chemical reactivity of B-GNRs is probed by the adsorption of nitric oxide (NO), which is most effectively trapped by the boron sites, demonstrating the Lewis acid character. Structural properties and the chemical nature of the NO-reacted B-GNR are determined by a combination of scanning tunnelling microscopy, high-resolution atomic force microscopy with a CO tip, and density functional and classical computations.

  13. New synthesis and physical property of low resistivity boron-doped multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ishii, S.; Watanabe, T.; Ueda, S.; Tsuda, S.; Yamaguchi, T.; Takano, Y.

    2008-09-01

    A novel growth technique of boron-doped multi-walled carbon nanotubes (MWNTs) was developed. Our new technique uses a methanol solution of boric acid as a source material. Resistivity of the boron-doped MWNTs was successfully reduced independently of chirality by our technique. Temperature dependence of resistivity in each individual boron-doped MWNT was measured by using small-sized four-point contacts, which were fabricated by electron beam (EB) lithography technique. Conduction carriers were introduced into the MWNT effectively by boron-doping.

  14. Magnesium doping of boron nitride nanotubes

    DOEpatents

    Legg, Robert; Jordan, Kevin

    2015-06-16

    A method to fabricate boron nitride nanotubes incorporating magnesium diboride in their structure. In a first embodiment, magnesium wire is introduced into a reaction feed bundle during a BNNT fabrication process. In a second embodiment, magnesium in powder form is mixed into a nitrogen gas flow during the BNNT fabrication process. MgB.sub.2 yarn may be used for superconducting applications and, in that capacity, has considerably less susceptibility to stress and has considerably better thermal conductivity than these conventional materials when compared to both conventional low and high temperature superconducting materials.

  15. Laser doping of boron-doped Si paste for high-efficiency silicon solar cells

    NASA Astrophysics Data System (ADS)

    Tomizawa, Yuka; Imamura, Tetsuya; Soeda, Masaya; Ikeda, Yoshinori; Shiro, Takashi

    2015-08-01

    Boron laser doping (LD) is a promising technology for high-efficiency solar cells such as p-type passivated locally diffused solar cells and n-type Si-wafer-based solar cells. We produced a printable phosphorus- or boron-doped Si paste (NanoGram® Si paste/ink) for use as a diffuser in the LD process. We used the boron LD process to fabricate high-efficiency passivated emitter and rear locally diffused (PERL) solar cells. PERL solar cells on Czochralski Si (Cz-Si) wafers yielded a maximum efficiency of 19.7%, whereas the efficiency of a reference cell was 18.5%. Fill factors above 79% and open circuit voltages above 655 mV were measured. We found that the boron-doped area effectively performs as a local boron back surface field (BSF). The characteristics of the solar cell formed using NanoGram® Si paste/ink were better than those of the reference cell.

  16. Ab initio study of electron-phonon coupling in boron-doped SiC

    NASA Astrophysics Data System (ADS)

    Margine, E. R.; Blase, X.

    2008-11-01

    Density functional theory calculations have been used to study the electronic structure, lattice dynamics, and electron-phonon coupling in boron-doped silicon carbide in the cubic phase. Our results provide evidence that the recently discovered superconducting transition in boron-doped silicon carbide can be explained within a standard phonon-mediated mechanism. For the same doping rate, the coupling constant λ in B-doped SiC is very close to that of doped diamond and twice as large as that of B-doped silicon. However, doped silicon carbide differs from its diamond counterpart as most of the electron-phonon coupling originates from low energy vibrational modes.

  17. ESR and Microwave Absorption in Boron Doped Diamond Single Crystals

    NASA Astrophysics Data System (ADS)

    Timms, Christopher

    2015-03-01

    Superconductivity has been reportedly found in boron-doped diamond. Most research to date has only studied superconductivity in polycrystalline and thin film boron-diamonds, as opposed to a single crystal. In fact, only one other group has examined a macro scale boron-doped diamond crystal. Our group has successfully grown large single crystals by using the High Temperature High Pressure method (HTHP) and observed a transition to metallic and superconducting states for high B concentrations. For the present, we are studying BDD crystal using Electron Spin Resonance. We conducted our ESR analysis over a range of temperatures (2K to 300K) and found several types of signals, proving the existence of charge carriers with spin 1/2 in BDD. Moreover, we have found that with increasing B concentrations, from n ~ 1018 cm-3 to n of over 1020 cm-3, the ESR signal changes from that of localized spins to the Dysonian shape of free carriers. The low magnetic field microwave absorption has also been studied in BDD samples at various B concentrations and the clear transition to superconducting state has been found below Tc that ranges from 2K to 4 K depending on concentration and quality of crystal. Sergey Polyakov, Victor Denisov, Vladimir Blank, Ray Baughman, Anvar Zakhidov.

  18. Boron doping of diamond via solid state diffusion

    NASA Astrophysics Data System (ADS)

    Tsai, W.; Delfino, M.; Ching, L.-Y.; Reynolds, G.; Hodul, D.; Cooper, C. B., III

    Boron was diffused into diamond and simultaneously electrically activated by a rapid thermal annealing technique using a cubic boron nitride planar diffusion source in an argon atmosphere. Type IIa diamonds of 100 line orientation were precleaned in an ammonium persulfate/sulfuric acid solution at 200 C before processing in a rapid thermal processor. Annealing temperature was 1370 C for 20 sec. Electrical contacts of Ti/Au were made on diamond via evaporation, and subsequent ohmic annealing was carried out for 30 min at 800 C. The current-voltage characteristics of boron-doped diamond was found to be ohmic with a resistance of 170 mega-ohm from -5 to 5 volts as compared with the high resistivity (greater than 10 exp 15 ohm-cm) of the unprocessed IIa diamond. Boron concentrations as high as 3.5 x 10 exp 19 atoms/cc were detected at a depth of 500 A in the diamond substrate using secondary ion mass spectrometry.

  19. Growth and characterization of boron doped graphene by Hot Filament Chemical Vapor Deposition Technique (HFCVD)

    NASA Astrophysics Data System (ADS)

    Jafari, A.; Ghoranneviss, M.; Salar Elahi, A.

    2016-03-01

    Large-area boron doped graphene was synthesized on Cu foil (as a catalyst) by Hot Filament Chemical Vapor Deposition (HFCVD) using boron oxide powder and ethanol vapor. To investigate the effect of different boron percentages, grow time and the growth mechanism of boron-doped graphene, scanning electron microscopy (SEM), Raman scattering and X-ray photoelectron spectroscopy (XPS) were applied. Also in this experiment, the I-V characteristic carried out for study of electrical property of graphene with keithley 2361 system. Nucleation of graphene domains with an average domain size of ~20 μm was observed when the growth time is 9 min that has full covered on the Cu surface. The Raman spectroscopy show that the frequency of the 2D band down-shifts with B doping, consistent with the increase of the in-plane lattice constant, and a weakening of the B-C in-plane bond strength relative to that of C-C bond. Also the shifts of the G-band frequencies can be interpreted in terms of the size of the C-C ring and the changes in the electronic structure of graphene in the presence of boron atoms. The study of electrical property shows that by increasing the grow time the conductance increases which this result in agree with SEM images and graphene grain boundary. Also by increasing the boron percentage in gas mixer the conductance decreases since doping graphene with boron creates a band-gap in graphene band structure. The XPS results of B doped graphene confirm the existence of boron in doped graphene, which indicates the boron atoms doped in the graphene lattice are mainly in the form of BC3. The results showed that boron-doped graphene can be successfully synthesized using boron oxide powder and ethanol vapor via a HFCVD method and also chemical boron doping can be change the electrical conductivity of the graphene.

  20. Evidence of superconductivity in doped graphite and graphene

    NASA Astrophysics Data System (ADS)

    Larkins, Grover; Vlasov, Yuriy; Holland, Kiar

    2016-01-01

    We have observed evidence of superconductivity at temperatures in the vicinity of 260 K in phosphorus-doped graphite and graphene. This evidence includes transport current, magnetic susceptibility, Hall effect and (pancake) vortex state measurements. All of these measurements indicate a transition which is that of a type II superconductor with no type I phase until below the limits of our measurement capabilities. Vortex states are inferred from periodically repeated steps in the resistance versus temperature characteristics of highly oriented pyrolytic graphite and exfoliated doped multilayer graphene. Magnetic susceptibility measurements have shown results qualitatively similar to those expected (and experimentally observed by others) for ultra-thin (thickness ≪λ L) films. The magnetization is negative for field-cooled and zero-field-cooled measurements. The magnetization for field cooled and zero-field-cooled measurements begin to diverge at approximately 260 K. Hall effect measurements show a sign reversal in the Hall voltage as the temperature is reduced from 300 K to 78 K.

  1. The boron doping of single crystal diamond for high power diode applications

    NASA Astrophysics Data System (ADS)

    Nicley, Shannon Singer

    Diamond has the potential to revolutionize the field of high power and high frequency electronic devices as a superlative electronic material. The realization of diamond electronics depends on the control of the growth process of both lightly and heavily boron doped diamond. This dissertation work is focused on furthering the state of the art of boron doped diamond (BDD) growth toward the realization of high power diamond Schottky barrier diodes (SBDs). The achievements of this work include the fabrication of a new dedicated reactor for lightly boron doped diamond deposition, the optimization of growth processes for both heavily and lightly boron doped single crystal diamond (SCD), and the proposal and realization of the corner architecture SBD. Boron doped SCD is grown in microwave plasma-assisted chemical vapor deposition (MPACVD) plasma disc bell-jar reactors, with feedgas mixtures including hydrogen, methane, carbon dioxide, and diborane. Characterization methods for the analysis of BDD are described, including Fourier-transformed infrared spectroscopy (FTIR), Secondary Ion Mass Spectroscopy (SIMS) and temperature-dependent four point probe conductivity for activation energy. The effect of adding carbon dioxide to the plasma feedgas for lightly boron doped diamond is investigated. The effect of diborane levels and other growth parameters on the incorporated boron levels are reported, and the doping efficiency is calculated over a range of boron concentrations. The presence of defects is shown to affect the doping uniformity. The substrate growth temperature dependence of the plasma gas-phase to solid-phase doping efficiency in heavily boron doped SCD deposition is investigated. The substrate temperature during growth is shown to have a significant effect on the grown sample defect morphology, and a temperature dependence of the doping efficiency is also shown. The effect of the growth rate on the doping efficiency is discussed, and the ratio of the boron

  2. Resistivity reduction of boron-doped multiwalled carbon nanotubes synthesized from a methanol solution containing boric acid

    NASA Astrophysics Data System (ADS)

    Ishii, Satoshi; Watanabe, Tohru; Ueda, Shinya; Tsuda, Shunsuke; Yamaguchi, Takahide; Takano, Yoshihiko

    2008-05-01

    Boron-doped multiwalled carbon nanotubes (MWNTs) were synthesized using a methanol solution of boric acid as a source material. Accurate measurements of the electrical resistivity of an individual boron-doped MWNT was performed with a four-point contact, which was fabricated using an electron beam lithography technique. The doped boron provides conduction carriers, which reduces the resistivity of the MWNT.

  3. Effect of Catalytic Graphitization on the Thermo-Mechanical Properties of Isotropic Graphite Doped with Metallic Carbides

    NASA Astrophysics Data System (ADS)

    OrdA~¡s, N.; GarcA~­-Rosales, C.; Lindig, S.; Balden, M.; Wang, H.

    The influence of several graphitization parameters (temperature, dwell time, HIPing subsequent to graphitization) on the final properties of doped isotropic graphite has been investigated. The aim of this work is to obtain doped isotropic graphite with reduced chemical erosion by hydrogen bombardment, high thermal conductivity and large thermal shock resistance. As starting material, a self-sintering mesophase carbon powder and different metallic carbides (TiC, VC, ZrC and WC) as dopants has been used. Longer dwell time results in a remarkable increase of thermal conductivity, depending on the dopant and on the graphitization temperature. However, it leads also to carbide coarsening and local carbide agglomeration and thus to degradation of the mechanical properties. HIPing subsequent to graphitization leads to a significant reduction of porosity for the materials doped with VC and WC and thus to an improvement of their mechanical properties. A solid–liquid–solid model for metal catalysts can be applied to our experimental observations of graphitization in the presence of metallic carbides.

  4. Facile Synthesis of Boron-Doped rGO as Cathode Material for High Energy Li-O2 Batteries.

    PubMed

    Wu, Feng; Xing, Yi; Li, Li; Qian, Ji; Qu, Wenjie; Wen, Jianguo; Miller, Dean; Ye, Yusheng; Chen, Renjie; Amine, Khalil; Lu, Jun

    2016-09-14

    To improve the electrochemical performance of the high energy Li-O2 batteries, it is important to design and construct a suitable and effective oxygen-breathing cathode. Herein, a three-dimensional (3D) porous boron-doped reduction graphite oxide (B-rGO) material with a hierarchical structure has been prepared by a facile freeze-drying method. In this design, boric acid as the boron source helps to form the 3D porous structure, owing to its cross-linking and pore-forming function. This architecture facilitates the rapid oxygen diffusion and electrolyte penetration in the electrode. Meanwhile, the boron-oxygen functional groups linking to the carbon surface or edge serve as additional reaction sites to activate the ORR process. It is vital that boron atoms have been doped into the carbon lattices to greatly activate the electrons in the carbon π system, which is beneficial for fast charge under large current densities. Density functional theory calculation demonstrates that B-rGO exhibits much stronger interactions with Li5O6 clusters, so that B-rGO more effectively activates Li-O bonds to decompose Li2O2 during charge than rGO does. With B-rGO as a catalytic substrate, the Li-O2 battery achieves a high discharge capacity and excellent rate capability. Moreover, catalysts could be added into the B-rGO substrate to further lower the overpotential and enhance the cycling performance in future. PMID:27549204

  5. Electronic structure and optical property of boron doped semiconducting graphene nanoribbons

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    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.

  6. Percolation exponents and thresholds obtained from the nearly ideal continuum percolation system graphite-boron nitride

    SciTech Connect

    Wu, J.; McLachlan, D.S.

    1997-07-01

    Compressed disks made from graphite and, its mechanical but not electrical isomorph, boron nitride as well as graphite-boron nitride powders, undergoing compression, are nearly ideal continuum percolation systems, as the ratio of their conductivities is nearly 10{sup {minus}18} and the scatter of the experimental points near the critical volume fraction {phi}{sub c} is very small. The following measurements, with the characteristic exponent(s) in brackets, are made on some or all of the samples in (axial) and at right angles (radial) to the direction of compression, as a function of the volume fraction of graphite ({phi}); dc conductivity (s and t), dielectric constant (s), magnetoresistivity (t{sub {perpendicular}}), and noise power (K). The noise power is also measured as function of resistance (w) and volume (b{sup {prime}}). The {phi}{sub c}{close_quote}s obtained for all measurements are consistent and explicable. The results for the exponents are less well understood but, where possible, these results are compared with theoretical predictions and previous experiments. The reasons for the nonuniversality of t are clarified. {copyright} {ital 1997} {ital The American Physical Society}

  7. Boron doped simulated graphene field effect transistor model

    NASA Astrophysics Data System (ADS)

    Sharma, Preetika; Kaur, Inderpreet; Gupta, Shuchi; Singh, Sukhbir

    2016-05-01

    Graphene based electronic devices due to its unique properties has transformed electronics. A Graphene Field Effect Transistor (GNRFET) model is simulated in Virtual Nano Lab (VNL) and the calculations are based on density functional theory (DFT). Simulations were performed on this pristine GNRFET model and the transmission spectrum was observed. The graph obtained showed a uniform energy gap of +1 to -1eV and the highest transmission peak at -1.75 eV. To this pristine model of GNRFET, doping was introduced and its effect was seen on the Fermi level obtained in the transmission spectrum. Boron as a dopant was used which showed variations in both the transmission peaks and the energy gap. In this model, first the single boron was substituted in place of carbon and Fermi level showed an energy gap of 1.5 to -0.5eV with the highest transmission peak at -1.3 eV. In another variation in the model, two carbon atoms were replaced by two boron atoms and Fermi level shifted from 2 to 0.25eV. In this observation, the highest transmission peak was observed at -1(approx.). The use of nanoelectronic devices have opened many areas of applications as GFET is an excellent building block for electronic circuits, and is being used in applications such as high-performance frequency doublers and mixers, digital modulators, phase detectors, optoelectronics and spintronics.

  8. Enhanced diffusion of oxygen depending on Fermi level position in heavily boron-doped silicon

    SciTech Connect

    Torigoe, Kazuhisa Fujise, Jun; Ono, Toshiaki; Nakamura, Kozo

    2014-11-21

    The enhanced diffusivity of oxygen in heavily boron doped silicon was obtained by analyzing oxygen out-diffusion profile changes found at the interface between a lightly boron-doped silicon epitaxial layer and a heavily boron-doped silicon substrate by secondary ion mass spectrometry. It was found that the diffusivity is proportional to the square root of boron concentration in the range of 10{sup 18 }cm{sup −3}–10{sup 19 }cm{sup −3} at temperatures from 750 °C to 950 °C. The model based on the diffusion of oxygen dimers in double positive charge state could explain the enhanced diffusion. We have concluded that oxygen diffusion enhanced in heavily boron-doped silicon is attributed to oxygen dimers ionized depending on Fermi level position.

  9. B and N isolate-doped graphitic carbon nanosheets from nitrogen-containing ion-exchanged resins for enhanced oxygen reduction

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Yu, Peng; Zhao, Lu; Tian, Chungui; Zhao, Dongdong; Zhou, Wei; Yin, Jie; Wang, Ruihong; Fu, Honggang

    2014-06-01

    B,N-codoped carbon nanostructures (BNCS) can serve as alternative low-cost metal-free electrocatalysts for oxygen reduction reactions (ORR). However, the compensation effect between the p- (B atoms) and n-type (N atoms) dopants would make the covalent boron-nitride (BN) easily formed during the synthesis of BNCS, leading to a unsatisfactory ORR activity. Therefore, it has been challenging to develop facile and rapid synthetic strategies for highly active BNCS without forming the direct covalent BN. Here, a facile method is developed to prepare B and N isolate-doped graphitic nanosheets (BNGS) by using iron species for saving N element and simultaneous doping the B element from nitrogen-containing ion-exchanged resins (NR). The resulting BNGS exhibits much more onset potential (Eonset) compared with the B-doped graphitic carbon nanosheets (BGS), N-doped graphitic carbon nanosheets (NGS), as well as B,N-codoped disorder carbon (BNC). Moreover, the BNGS shows well methanol tolerance propery and excellent stability (a minimal loss of activity after 5,000 potential cycles) compared to that of commercial Pt/C catalyst. The goog performance for BNGS towards ORR is attributed to the synergistic effect between B and N, and the well electrons transport property of graphitic carbon in BNGS.

  10. B and N isolate-doped graphitic carbon nanosheets from nitrogen-containing ion-exchanged resins for enhanced oxygen reduction

    PubMed Central

    Wang, Lei; Yu, Peng; Zhao, Lu; Tian, Chungui; Zhao, Dongdong; Zhou, Wei; Yin, Jie; Wang, Ruihong; Fu, Honggang

    2014-01-01

    B,N-codoped carbon nanostructures (BNCS) can serve as alternative low-cost metal-free electrocatalysts for oxygen reduction reactions (ORR). However, the compensation effect between the p- (B atoms) and n-type (N atoms) dopants would make the covalent boron-nitride (BN) easily formed during the synthesis of BNCS, leading to a unsatisfactory ORR activity. Therefore, it has been challenging to develop facile and rapid synthetic strategies for highly active BNCS without forming the direct covalent BN. Here, a facile method is developed to prepare B and N isolate-doped graphitic nanosheets (BNGS) by using iron species for saving N element and simultaneous doping the B element from nitrogen-containing ion-exchanged resins (NR). The resulting BNGS exhibits much more onset potential (Eonset) compared with the B-doped graphitic carbon nanosheets (BGS), N-doped graphitic carbon nanosheets (NGS), as well as B,N-codoped disorder carbon (BNC). Moreover, the BNGS shows well methanol tolerance propery and excellent stability (a minimal loss of activity after 5,000 potential cycles) compared to that of commercial Pt/C catalyst. The goog performance for BNGS towards ORR is attributed to the synergistic effect between B and N, and the well electrons transport property of graphitic carbon in BNGS. PMID:24898033

  11. The fabrication, testing and delivery of boron/epoxy and graphite/epoxy nondestructive test standards

    NASA Technical Reports Server (NTRS)

    Pless, W. M.; Lewis, W. H.

    1971-01-01

    A description is given of the boron/epoxy and graphite/epoxy nondestructive test standards which were fabricated, tested and delivered to the National Aeronautics and Space Administration. Detailed design drawings of the standards are included to show the general structures and the types and location of simulated defects built into the panels. The panels were laminates with plies laid up in the 0 deg, + or - 45 deg, and 90 deg orientations and containing either titanium substrates or interlayered titanium perforated shims. Panel thickness was incrementally stepped from 2.36 mm (0.093 in.) to 12.7 mm (0.500 in.) for the graphite/epoxy standards, and from 2.36 mm (0.093 in.) to 6.35 mm (0.25 in.) for the boron/epoxy standards except for the panels with interlayered shims which were 2.9 mm (0.113 in.) maximum thickness. The panel internal conditions included defect free regions, resin variations, density/porosity variations, cure variations, delaminations/disbonds at substrate bondlines and between layers, inclusions, and interlayered shims. Ultrasonic pulse echo C-scan and low-kilovoltage X-ray techniques were used to evaluate and verify the internal conditions of the panels.

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

    DOEpatents

    Zidan, Ragaiy; Ritter, James A.; Ebner, Armin D.; Wang, Jun; Holland, Charles E.

    2008-06-10

    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.

  13. Fluorosulfates of graphite and boron nitride and other high oxidation state studies

    SciTech Connect

    Biagioni, R.N.

    1980-10-01

    The adduct XeF/sub 2/.AsF/sub 5/ was re-examined and assessed to be intermediate between the salt formulation (FXe)/sup +/AsF/sub 6//sup -/ and the fluorine bridged molecular adduct. A series of graphite fluorosulfates were prepared, using as the oxidizing agent S/sub 2/O/sub 6/F/sub 2/, and the effects of incorporating varying amounts of fluorosulfonic acid were studied. Physical data indicated that the S/sub 2/O/sub 6/F/sub 2/ was incorported as SO/sub 3/F/sup -/, and the HSO/sub 3/F was bound tightly, probably due to hydrogen bonding. The c-spacings of HSO/sub 3/F containing materials were larger than those of acid free materials, and the influences of charging, guest size and guest orientation were examined. X-ray diffractometer studies of graphite slabs intercalated with SO/sub 3/F/HSO/sub 3/F and IrF/sub 6/ indicated structures consistent with the characterization of these materials as containing tetrahedral SO/sub 3/F and octahedral IrF/sub 6/. Boron nitride reacted with S/sub 2/O/sub 6/F/sub 2/ to yield a deep blue, conducting intercalation compound. This material was in many respects similar to its graphite analog, but chemically more labile.

  14. Dirac cones in transition metal doped boron nitride

    SciTech Connect

    Feng, Min; Cao, Xuewei; Shao, Bin; Zuo, Xu

    2015-05-07

    The transition metal (TM) doped zinc blende boron nitride (c-BN) is studied by using the first principle calculation. TM atoms fill in the interstitials in c-BN and form two-dimensional honeycomb lattice. The generalized gradient approximation and projector augmented wave method are used. The calculated density of states and band structures show that d electrons of TM atoms form impurity bands in the gap of c-BN. When the TM-BN system is in ferromagnetic or non-magnetic state, Dirac cones emerge at the K point in Brillouin zone. When TM is Ti and Co, the Dirac cones are spin polarized and very close to the Fermi level, which makes them promising candidates of Dirac half-metal [H. Ishizuka and Y. Motome, Phys. Rev. Lett. 109, 237207 (2012)]. While TM is Ni and Cu, the system is non-magnetic and Dirac cones located above the Fermi level.

  15. Controlling the Bandgap of Boron Nitride Nanotubes with Carbon Doping

    NASA Astrophysics Data System (ADS)

    Mousavi, Hamze; Bagheri, Mehran

    2015-08-01

    This study explores the effects of doping by carbon (C) atoms on electronic properties of (10,10) and (16,0) boron nitride (BN) nanotubes (NTs). We exploit the random tight-binding model with Green's function technique and coherent potential approximation to show that the C dopant causes a decrease in the bandgap of the BN NTs, and their matching Van Hove singularities (VHS) in the density of states (DOS) are broadened. When the impurity concentration is large enough, the form of the DOS of the BN NTs becomes similar to that of metallic (10,10) and semiconducting (16,0) C NTs and their VHS get sharpened. This work might provide opportunities for creating new optoelectronic devices based on BN honeycomb nanosystems.

  16. Chemical vapor deposition of boron-doped hydrogenated amorphous silicon

    SciTech Connect

    Ellis F.B. Jr.; Delahoy, A.E.

    1985-07-15

    Deposition conditions and film properties for a variety of boron-doped hydrogenated amorphous silicon films and silicon-carbon films produced by chemical vapor deposition (CVD) are discussed. Deposition gases include monosilane, disilane, trisilane, and acetylene. Two types of optically wide band-gap p layers are obtained. One of these window p layers (without carbon) has been extensively tested in photovoltaic devices. Remarkably, this p layer can be deposited between about 200 to 300 /sup 0/C. A typical open circuit voltage in an all CVD p-i-n device is 0.70--0.72 V, and in a hybrid device where the i and n layers are deposited by glow discharge, 0.8--0.83 V.

  17. The crystal structure of aluminum doped β-rhombohedral boron

    NASA Astrophysics Data System (ADS)

    Bykova, Elena; Parakhonskiy, Gleb; Dubrovinskaia, Natalia; Chernyshov, Dmitry; Dubrovinsky, Leonid

    2012-10-01

    A crystal structure of aluminum doped β-rhombohedral boron was studied by single-crystal X-ray diffraction at 80 K. The crystals were synthesized using high-pressure high temperature technique at 3 GPa and 2100 K. The structure is based on three-dimensional framework made of B12 icosahedra with voids occupied by the B28-B-B28 units, it has the R-3m space group with a=10.9014(3), c=23.7225(7) Å lattice dimensions in hexagonal setting. Aluminum atoms are located in A1 and D special positions of the β-B structure with occupancies of 82.7(6)% and 11.3(4)%, respectively. Additional boron atoms are located near the D-site. Their possible distribution is discussed. Finally we have found two appropriate structural models whose refinement suggests two possible chemical compositions, AlB44.8(5) and AlB37.8(5), which are in a good agreement with the chemical analysis data obtained from EDX. The crystal structure of AlB44.8(5) is described in detail.

  18. X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms

    PubMed Central

    Pichler, Thomas; Ayala, Paola

    2015-01-01

    Summary X-ray photoelectron spectroscopy (XPS) is one of the best tools for studying the chemical modification of surfaces, and in particular the distribution and bonding of heteroatom dopants in carbon nanomaterials such as graphene and carbon nanotubes. Although these materials have superb intrinsic properties, these often need to be modified in a controlled way for specific applications. Towards this aim, the most studied dopants are neighbors to carbon in the periodic table, nitrogen and boron, with phosphorus starting to emerge as an interesting new alternative. Hundreds of studies have used XPS for analyzing the concentration and bonding of dopants in various materials. Although the majority of works has concentrated on nitrogen, important work is still ongoing to identify its precise atomic bonding configurations. In general, care should be taken in the preparation of a suitable sample, consideration of the intrinsic photoemission response of the material in question, and the appropriate spectral analysis. If this is not the case, incorrect conclusions can easily be drawn, especially in the assignment of measured binding energies into specific atomic configurations. Starting from the characteristics of pristine materials, this review provides a practical guide for interpreting X-ray photoelectron spectra of doped graphitic carbon nanomaterials, and a reference for their binding energies that are vital for compositional analysis via XPS. PMID:25671162

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

    SciTech Connect

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

    2009-01-01

    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.

  20. Development of finely dispersed Ti- and Zr-doped isotropic graphites for the divertor of next step fusion devices

    NASA Astrophysics Data System (ADS)

    López-Galilea, I.; García-Rosales, C.; Pintsuk, G.; Linke, J.

    2007-03-01

    Finely dispersed Ti- and Zr-doped isotropic graphites have been manufactured using three different starting raw materials. The aim is to obtain doped fine grain isotropic graphites with reduced chemical erosion, high thermal shock resistance and low cost, which aim to be competitive with present carbon-based candidate materials for next step fusion devices. First ITER relevant thermal shock loads were applied on test specimens of these materials. The brittle destruction behaviour of graphite is greatly improved by doping with Ti or Zr, most probably due to a significant increase of thermal conductivity related to the catalytic effect of TiC and ZrC on the graphitization. Doped graphites manufactured with the synthetic mesophase pitch 'AR' as raw material showed the best performance from the three investigated raw materials due to its higher graphitability. The eroded surfaces of doped graphites exhibit a thin solidified carbide layer, probably caused by the segregation of liquid carbide during the thermal shot.

  1. Laser annealing of neutron irradiated boron-10 isotope doped diamond

    SciTech Connect

    Jagannadham, K.; Butler, J. E.

    2011-01-01

    10B isotope doped p-type diamond epilayer grown by chemical vapor deposition on (110) oriented type IIa diamond single crystal substrate was subjected to neutron transmutation at a fluence of 2.4 9 1020 thermal and 2.4 9 1020 fast neutrons. After neutron irradiation, the epilayer and the diamond substrate were laser annealed using Nd YAG laser irradiation with wave length, 266 nm and energy, 150 mJ per pulse. The neutron irradiated diamond epilayer and the substrate were characterized before and after laser annealing using different techniques. The characterization techniques include optical microscopy, secondary ion mass spectrometry, X-ray diffraction, Raman, photoluminescence and Fourier Transform Infrared spectroscopy, and electrical sheet conductance measurement. The results indicate that the structure of the irradiation induced amorphous epilayer changes to disordered graphite upon laser annealing. The irradiated substrate retains the (110) crystalline structure with neutron irradiation induced defects.

  2. Phase change in terahertz waves emitted from differently doped graphite: The role of carrier drift

    SciTech Connect

    Irfan, Muhammad; Yim, Jong-Hyuk; Jho, Young-Dahl; Kim, Changyoung; Wook Lee, Sang

    2013-11-11

    We investigate characteristics of THz waves radiated from differently doped graphite samples excited by femtosecond laser pulses. Between n-type single-crystalline graphite and p-type polycrystalline graphite films, we observe the phase reversal of THz waves regardless of excitation energy variations around K-valley. In addition, variations in other parameters such as excitation fluence and azimuthal angle produce no changes in the phase of THz waves, which correlate well with the opposite dipole polarization between differently doped samples rather than unidirectional diffusive transport.

  3. Cytotoxicity of Boron-Doped Nanocrystalline Diamond Films Prepared by Microwave Plasma Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Liu, Dan; Gou, Li; Ran, Junguo; Zhu, Hong; Zhang, Xiang

    2015-07-01

    Boron-doped nanocrystalline diamond (NCD) exhibits extraordinary mechanical properties and chemical stability, making it highly suitable for biomedical applications. For implant materials, the impact of boron-doped NCD films on the character of cell growth (i.e., adhesion, proliferation) is very important. Boron-doped NCD films with resistivity of 10-2 Ω·cm were grown on Si substrates by the microwave plasma chemical vapor deposition (MPCVD) process with H2 bubbled B2O3. The crystal structure, diamond character, surface morphology, and surface roughness of the boron-doped NCD films were analyzed using different characterization methods, such as X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The contact potential difference and possible boron distribution within the film were studied with a scanning kelvin force microscope (SKFM). The cytotoxicity of films was studied by in vitro tests, including fluorescence microscopy, SEM and MTT assay. Results indicated that the surface roughness value of NCD films was 56.6 nm and boron was probably accumulated at the boundaries between diamond agglomerates. MG-63 cells adhered well and exhibited a significant growth on the surface of films, suggesting that the boron-doped NCD films were non-toxic to cells. supported by the Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices (University of Electronic Science and Technology of China) (No. KFJJ201313)

  4. Toward deep blue nano hope diamonds: heavily boron-doped diamond nanoparticles.

    PubMed

    Heyer, Steffen; Janssen, Wiebke; Turner, Stuart; Lu, Ying-Gang; Yeap, Weng Siang; Verbeeck, Jo; Haenen, Ken; Krueger, Anke

    2014-06-24

    The production of boron-doped diamond nanoparticles enables the application of this material for a broad range of fields, such as electrochemistry, thermal management, and fundamental superconductivity research. Here we present the production of highly boron-doped diamond nanoparticles using boron-doped CVD diamond films as a starting material. In a multistep milling process followed by purification and surface oxidation we obtained diamond nanoparticles of 10-60 nm with a boron content of approximately 2.3 × 10(21) cm(-3). Aberration-corrected HRTEM reveals the presence of defects within individual diamond grains, as well as a very thin nondiamond carbon layer at the particle surface. The boron K-edge electron energy-loss near-edge fine structure demonstrates that the B atoms are tetrahedrally embedded into the diamond lattice. The boron-doped diamond nanoparticles have been used to nucleate growth of a boron-doped diamond film by CVD that does not contain an insulating seeding layer. PMID:24738731

  5. Plasma-induced highly efficient synthesis of boron doped reduced graphene oxide for supercapacitors.

    PubMed

    Li, Shaobo; Wang, Zhaofeng; Jiang, Hanmei; Zhang, Limei; Ren, Jingzheng; Zheng, Mingtao; Dong, Lichun; Sun, Luyi

    2016-09-21

    In this work, we presented a novel route to synthesize boron doped reduced graphene oxide (rGO) by using the dielectric barrier discharge (DBD) plasma technology under ambient conditions. The doping of boron (1.4 at%) led to a significant improvement in the capacitance of rGO and supercapacitors based on the as-synthesized B-rGO exhibited an outstanding specific capacitance. PMID:27534806

  6. Electrical Characterization of Diamond/Boron Doped Diamond Nanostructures for Use in Harsh Environment Applications

    NASA Astrophysics Data System (ADS)

    Gołuński, Ł.; Zwolski, K.; Płotka, P.

    2016-01-01

    The polycrystalline boron doped diamond (BDD) shows stable electrical properties and high tolerance for harsh environments (e.g. high temperature or aggressive chemical compounds) comparing to other materials used in semiconductor devices. In this study authors have designed electronic devices fabricated from non-intentionally (NiD) films and highly boron doped diamond structures. Presented semiconductor devices consist of highly boron doped structures grown on NiD diamond films. Fabricated structures were analyzed by electrical measurements for use in harsh environment applications. Moreover, the boron-doping level and influence of oxygen content on chemical composition of diamond films were particularly investigated. Microwave Plasma Enhanced Chemical Vapour Deposition (MW PE CVD) has been used for thin diamond films growth. Non-intentionally doped diamond (0 ppm [B]/[C]) films have been deposited on the Si/SiO2 wafers with different content of carbon, boron and oxygen in the gas phase. Then, the shape of the highly doped diamond structures were obtained by pyrolysis of SiO2 on NiD film and standard lithography process. The highly doped structures were obtained for different growth time and [B]/[C] ratio (4000 - 10000 ppm). The narrowest distance between two highly doped structures was 5pm. The standard Ti/Au ohmic contacts were deposited using physical vapour deposition for electrical characterization of NiD/BDD devices. The influence of diffusion boron from highly doped diamond into non-doped/low-doped diamond film was investigated. Surface morphology of designed structures was analyzed by Scanning Electron Microscope and optical microscope. The resistivity of the NiD and film was studied using four-point probe measurements also DC studies were done.

  7. Properties of boron-doped thin films of polycrystalline silicon

    SciTech Connect

    Merabet, Souad

    2013-12-16

    The properties of polycrystalline-silicon films deposited by low pressure chemical vapor deposition and doped heavily in situ boron-doped with concentration level of around 2×10{sup 20}cm{sup −3} has been studied. Their properties are analyzed using electrical and structural characterization means by four points probe resistivity measurements and X-ray diffraction spectra. The thermal-oxidation process are performed on sub-micron layers of 200nm/c-Si and 200nm/SiO{sub 2} deposited at temperatures T{sub d} ranged between 520°C and 605°C and thermally-oxidized in dry oxygen ambient at 945°C. Compared to the as-grown resistivity with silicon wafers is known to be in the following sequence <ρ{sub 200nm/c−Si}> < <ρ{sub 200nm/SiO2}> and <ρ{sub 520}> < <ρ{sub 605}>. The measure X-ray spectra is shown, that the Bragg peaks are marked according to the crystal orientation in the film deposited on bare substrates (poly/c-Si), for the second series of films deposited on bare oxidized substrates (poly/SiO{sub 2}) are clearly different.

  8. Improvement of thermal shock resistance of isotropic graphite by Ti-doping

    NASA Astrophysics Data System (ADS)

    López-Galilea, I.; Ordás, N.; García-Rosales, C.; Lindig, S.

    2009-04-01

    Ti-doped isotropic graphite is a promising candidate material for the strike point area of the ITER divertor due to its reduced chemical erosion by hydrogen bombardment and its high thermal shock resistance, mainly due the catalytic effect of TiC on the graphitization leading to an increase of thermal conductivity and to higher mechanical strength. Several manufacturing parameters such as oxidative stabilization treatment, carbonization cycle, graphitization temperature and dwell time during graphitization have been investigated in order to establish a relationship between these parameters and the final properties.

  9. Electronic and optical properties of boron-doped nanocrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Gajewski, W.; Achatz, P.; Williams, O. A.; Haenen, K.; Bustarret, E.; Stutzmann, M.; Garrido, J. A.

    2009-01-01

    We report on the electronic and optical properties of boron-doped nanocrystalline diamond (NCD) thin films grown on quartz substrates by CH4/H2 plasma chemical vapor deposition. Diamond thin films with a thickness below 350 nm and with boron concentration ranging from 1017 to 1021cm-3 have been investigated. UV Raman spectroscopy and atomic force microscopy have been used to assess the quality and morphology of the diamond films. Hall-effect measurements confirmed the expected p -type conductivity. At room temperature, the conductivity varies from 1.5×10-8Ω-1cm-1 for a nonintentionally doped film up to 76Ω-1cm-1 for a heavily B -doped film. Increasing the doping level results in a higher carrier concentration while the mobility decreases from 1.8 down to 0.2cm2V-1s-1 . For NCD films with low boron concentration, the conductivity strongly depends on temperature. However, the conductivity and the carrier concentration are no longer temperature dependent for films with the highest boron doping and the NCD films exhibit metallic properties. Highly doped films show superconducting properties with critical temperatures up to 2 K. The critical boron concentration for the metal-insulator transition is in the range from 2×1020 up to 3×1020cm-3 . We discuss different transport mechanisms to explain the influence of the grain boundaries and boron doping on the electronic properties of NCD films. Valence-band transport dominates at low boron concentration and high temperatures, whereas hopping between boron acceptors is the dominant transport mechanism for boron-doping concentration close to the Mott transition. Grain boundaries strongly reduce the mobility for low and very high doping levels. However, at intermediate doping levels where hopping transport is important, grain boundaries have a less pronounced effect on the mobility. The influence of boron and the effect of grain boundaries on the optoelectronic properties of the NCD films are examined using spectrally

  10. Experimental studies of graphite-epoxy and boron-epoxy angle ply laminates in shear

    NASA Technical Reports Server (NTRS)

    Weller, T.

    1977-01-01

    The nonlinear/inelastic response under inplane shear of a large variety of graphite-epoxy and boron-epoxy angle-ply laminates was tested. Their strength allowables were obtained and the mechanisms which govern their mode of failure were determined. Two types of specimens for the program were chosen, tested, and evaluated: shear panels stabilized by an aluminum honeycomb core and shear tubes. A modified biaxially compression/tension loaded picture frame was designed and utilized in the test program with the shear panels. The results obtained with this test technique categorically prefer the shear panels, rather than the tubes, for adequate and satisfactory experimental definition of the objectives. Test results indicate the existence of a so-called core-effect which ought to be considered when reducing experimental data for weak in shear laminates.

  11. Nitrogen-doped graphene by ball-milling graphite with melamine for energy conversion and storage

    NASA Astrophysics Data System (ADS)

    Xue, Yuhua; Chen, Hao; Qu, Jia; Dai, Liming

    2015-12-01

    N-doped graphene was prepared by ball milling of graphite with melamine. It was found that ball-milling reduced the size of graphite particles from 30 to 1 μm and facilitated the exfoliation of the resultant small particles into few-layer N-doped graphene nanosheets under ultrasonication. The as-prepared N-doped graphene nanoplatelets (NGnPs) exhibited a nitrogen content as high as 11.4 at.%, making them attractive as efficient electrode materials in supercapacitors for energy storage and as highly-active metal-free catalysts for oxygen reduction in fuel cells for energy conversion.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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. AFOSR MURI No. 105800

  13. Fabrication and characterization of boron-doped nanocrystalline diamond-coated MEMS probes

    NASA Astrophysics Data System (ADS)

    Bogdanowicz, Robert; Sobaszek, Michał; Ficek, Mateusz; Kopiec, Daniel; Moczała, Magdalena; Orłowska, Karolina; Sawczak, Mirosław; Gotszalk, Teodor

    2016-04-01

    Fabrication processes of thin boron-doped nanocrystalline diamond (B-NCD) films on silicon-based micro- and nano-electromechanical structures have been investigated. B-NCD films were deposited using microwave plasma assisted chemical vapour deposition method. The variation in B-NCD morphology, structure and optical parameters was particularly investigated. The use of truncated cone-shaped substrate holder enabled to grow thin fully encapsulated nanocrystalline diamond film with a thickness of approx. 60 nm and RMS roughness of 17 nm. Raman spectra present the typical boron-doped nanocrystalline diamond line recorded at 1148 cm-1. Moreover, the change in mechanical parameters of silicon cantilevers over-coated with boron-doped diamond films was investigated with laser vibrometer. The increase of resonance to frequency of over-coated cantilever is attributed to the change in spring constant caused by B-NCD coating. Topography and electrical parameters of boron-doped diamond films were investigated by tapping mode AFM and electrical mode of AFM-Kelvin probe force microscopy (KPFM). The crystallite-grain size was recorded at 153 and 238 nm for boron-doped film and undoped, respectively. Based on the contact potential difference data from the KPFM measurements, the work function of diamond layers was estimated. For the undoped diamond films, average CPD of 650 mV and for boron-doped layer 155 mV were achieved. Based on CPD values, the values of work functions were calculated as 4.65 and 5.15 eV for doped and undoped diamond film, respectively. Boron doping increases the carrier density and the conductivity of the material and, consequently, the Fermi level.

  14. Photodegradation of rhodamine B and methyl orange over boron-doped g-C3N4 under visible light irradiation.

    PubMed

    Yan, S C; Li, Z S; Zou, Z G

    2010-03-16

    Graphitic carbon nitride (g-C(3)N(4)) and boron-doped g-C(3)N(4) were prepared by heating melamine and the mixture of melamine and boron oxide, respectively. X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis spectra were used to describe the properties of as-prepared samples. The electron paramagnetic resonance was used to detect the active species for the photodegradation reaction over g-C(3)N(4). The photodegradation mechanisms for two typical dyes, rhodamine B (Rh B) and methyl orange (MO), are proposed based on our comparison experiments. In the g-C(3)N(4) photocatalysis system, the photodegradation of Rh B and MO is attributed to the direct hole oxidation and overall reaction, respectively; however, for the MO photodegradation the reduction process initiated by photogenerated electrons is a major photocatalytic process compared with the oxidation process induced by photogenerated holes. Boron doping for g-C(3)N(4) can promote photodegradation of Rh B because the boron doping improves the dye adsorption and light absorption of catalyst. PMID:20175583

  15. Structure and superconductivity of isotope-enriched boron-doped diamond

    SciTech Connect

    Thompson, Joe D; Ekimov, E A; Sidorov, V A; Zoteev, A; Lebed, Y; Stishov, S M

    2008-01-01

    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.

  16. Synthesis and Raman Characterization of Boron Doped Single Walled Carbon Nanotubes (SWNTs)

    NASA Astrophysics Data System (ADS)

    McGuire, K.; Gothard, N.; Gai, P. L.; Chou, S. G.; Dresselhaus, M. S.; Rao, A. M.

    2003-03-01

    Boron-doped SWNTs were prepared by pulsed laser vaporization of carbon targets containing boron with concentrations ranging between 0.5 - 10 at%. As-prepared samples were characterized using Raman spectroscopy and HRTEM measurements. Above a threshold boron concentration of 3 at%, the growth of SWNT bundles ceases due to the low solubility of boron in carbon at ˜1200 ^oC. Interestingly, a few ˜0.5 nm diameter single walled tubes are found, along with nanographitic material in the soot generated from a target with a boron concentration of ˜7 at%. As expected, the intensity of the ˜1350 cm-1 D-band increases with increasing boron concentration due to boron substitution into the honeycomb lattice. Both the radial breathing mode and tangential G- bands were observed in the Raman spectra in samples with <3 at % boron at ˜186 cm-1 and ˜1591 cm-1, respectively. Implications of boron doping in the nanotube shell will be discussed.

  17. Synthesis and Raman Characterization of Boron Doped Single Walled Carbon Nanotubes (SWNTs)

    NASA Astrophysics Data System (ADS)

    McGuire, K.; Gothard, N.; Gai, P. L.; Chao, S. G.; Dresselhaus, M. S.; Rao, A. M.

    2003-11-01

    Boron-doped SWNTs were prepared by pulsed laser vaporization of carbon targets containing boron with concentrations ranging between 0.5 - 10 at%. As-prepared samples were characterized using Raman spectroscopy and HRTEM measurements. Above a threshold boron concentration of 3 at%, the growth of SWNT bundles ceases due to the low solubility of boron in carbon at ˜1200 ^oC. Interestingly, a few ˜0.5 nm diameter single walled tubes are found, along with nanographitic material in the soot generated from a target with a boron concentration of ˜7 at%. As expected, the intensity of the ˜1350 cm-1 D-band increases with increasing boron concentration due to boron substitution into the honeycomb lattice. Both the radial breathing mode and tangential G- bands were observed in the Raman spectra in samples with <3 at % boron at ˜186 cm-1 and ˜1591 cm-1, respectively. Implications of boron doping in the nanotube shell will be discussed.

  18. The effect of substrate temperature and growth rate on the doping efficiency of single crystal boron doped diamond

    SciTech Connect

    Demlow, SN; Rechenberg, R; Grotjohn, T

    2014-10-01

    The substrate growth temperature dependence of the plasma gas-phase to solid-phase doping efficiency in single crystal, boron doped diamond (BDD) deposition is investigated. Single crystal diamond (SCD) is grown by microwave plasma assisted chemical vapor deposition (MPACVD) on high pressure, high temperature (HPHT) type Ib substrates. Samples are grown at substrate temperatures of 850-950 degrees C for each of five doping concentration levels, to determine the effect of the growth temperature on the doping efficiency and defect morphology. The substrate temperature during growth is shown to have a significant effect on the grown sample defect morphology, and a temperature dependence of the doping efficiency is also shown. The effect of the growth rate on the doping efficiency is discussed, and the ratio of the boron concentration in the gas phase to the flux of carbon incorporated into the solid diamond phase is shown to be a more predictive measure of the resulting boron concentration than the gas phase boron to carbon ratio that is more commonly reported. (C) 2014 Elsevier B.V. All rights reserved.

  19. Suppression of boron-oxygen defects in Czochralski silicon by carbon co-doping

    SciTech Connect

    Wu, Yichao; Yu, Xuegong He, Hang; Chen, Peng; Yang, Deren

    2015-03-09

    We have investigated the influence of carbon co-doping on the formation of boron-oxygen defects in Czochralski silicon. It is found that carbon can effectively suppress the formation of boron-oxygen defects. Based on our experiments and first-principle theoretical calculations, it is believed that this effect is attributed to the formation of more energetically favorable carbon-oxygen complexes. Moreover, the diffusion of oxygen dimers in carbon co-doped silicon also becomes more difficult. All these phenomena should be associated with the tensile stress field induced by carbon doping in silicon.

  20. Boron- and phosphorus-doped polycrystalline silicon thin films prepared by silver-induced layer exchange

    SciTech Connect

    Antesberger, T.; Wassner, T. A.; Jaeger, C.; Algasinger, M.; Kashani, M.; Scholz, M.; Matich, S.; Stutzmann, M.

    2013-05-27

    Intentional boron and phosphorus doping of polycrystalline silicon thin films on glass prepared by the silver-induced layer exchange is presented. A silver/(titanium) oxide/amorphous silicon stack is annealed at temperatures below the eutectic temperature of the Ag/Si system, leading to a complete layer exchange and simultaneous crystallization of the amorphous silicon. Intentional doping of the amorphous silicon prior to the exchange process results in boron- or phosphorus-doped polycrystalline silicon. Hall effect measurements show carrier concentrations between 2 Multiplication-Sign 10{sup 17} cm{sup -3} and 3 Multiplication-Sign 10{sup 20} cm{sup -3} for phosphorus and 4 Multiplication-Sign 10{sup 18} cm{sup -3} to 3 Multiplication-Sign 10{sup 19} cm{sup -3} for boron-doped layers, with carrier mobilities up to 90 cm{sup 2}/V s.

  1. Optical and electrical properties of undoped and boron doped zinc oxide synthesized by chemical route

    SciTech Connect

    Bhattacharjee, Snigdha; Basu, Moumita; Roy, Asim

    2015-08-28

    We have synthesized and studied the boron doped ZnO nanostructure thin films. The crystallinity of undoped and boron (B) doped ZnO (BZO) has been studied from XRD results. Using the Debye-Scherrer Formula, the grain size has been evaluated, which was found to decrease with increased doping concentration. The optical and electrical properties of (1, 3, 5 wt%) B-doped ZnO (BZO) has been investigated with reference to the undoped counterpart. The UV-VIS spectroscopic analysis revealed that the transmittance for undoped ZnO is maximum and it decreases with doping up to 3% but increases for 5% BZO. The dark as well as photo current–voltage (I–V) characteristics have been investigated in details and the changes occurred in the I-V characteristics with doping concentration as well as under illumination are also quite significant.

  2. Synthesis of boron-doped graphene monolayers using the sole solid feedstock by chemical vapor deposition.

    PubMed

    Wang, Huan; Zhou, Yu; Wu, Di; Liao, Lei; Zhao, Shuli; Peng, Hailin; Liu, Zhongfan

    2013-04-22

    Substitutionally boron-doped monolayer graphene film is grown on a large scale by using a sole phenylboronic acid as the source in a low-pressure chemical vapor deposition system. The B-doped graphene film is a homogeneous monolayer with high crystalline quality, which exhibits a stable p-type doping behavior with a considerably high room-temperature carrier mobility of about 800 cm(2) V(-1) s(-1) . PMID:23463717

  3. Focused ion beam fabrication of boron-doped diamond ultramicroelectrodes.

    PubMed

    Hu, Jingping; Holt, Katherine B; Foord, John S

    2009-07-15

    The fabrication of ultramicroelectrodes (UMEs) for analytical electrochemical applications has been explored, using boron-doped diamond as the active electrode material in an insulating coating formed by deposition of electrophoretic paint. Because of the rough nature of the diamond film, the property of such coatings that is normally exploited in the fabrication of UMEs, namely the tendency to retract automatically from sharp protrusions, cannot be used in the present instance. Instead focused ion beam (FIB) sputtering was employed to controllably produce UMEs with well-defined geometry, critical dimension of a few micrometers, and very thin insulating coatings. If the FIB machining is carried out at normal incidence to the diamond electrode surface, significant ion beam damage reduces the yield of successful electrodes. However, if a parallel machining geometry is employed, high yields of ultramicroelectrodes with a flat disk geometry can be obtained very reliably. The electrochemical properties of diamond UMEs are characterized. They show much lower background currents than the equivalent Pt or carbon fiber electrodes but more varied electrochemical response than macroscopic diamond electrodes. PMID:19545137

  4. Boron doped defective graphene as a potential anode material for Li-ion batteries.

    PubMed

    Hardikar, Rahul P; Das, Deya; Han, Sang Soo; Lee, Kwang-Ryeol; Singh, Abhishek K

    2014-08-21

    Graphene with large surface area and robust structure has been proposed as a high storage capacity anode material for Li ion batteries. While the inertness of pristine graphene leads to better Li kinetics, poor adsorption leads to Li clustering, significantly affecting the performance of the battery. Here, we show the role of defects and doping in achieving enhanced adsorption without compromising on the high diffusivity of Li. Using first principles density functional theory (DFT) calculations, we carry out a comprehensive study of diffusion kinetics of Li over the plane of the defective structures and calculate the change in the number of Li atoms in the vicinity of defects, with respect to pristine graphene. Our results show that the Li-C interaction, storage capacity and the energy barriers depend sensitively on the type of defects. The un-doped and boron doped mono-vacancy, doped di-vacancy up to two boron, one nitrogen doped di-vacancy, and Stone-Wales defects show low energy barriers that are comparable to pristine graphene. Furthermore, boron doping at mono-vacancy enhances the adsorption of Li. In particular, the two boron doped mono-vacancy graphene shows both a low energy barrier of 0.31 eV and better adsorption, and hence can be considered as a potential candidate for anode material. PMID:24986702

  5. High-concentration boron doping of graphene nanoplatelets by simple thermal annealing and their supercapacitive properties

    PubMed Central

    Yeom, Da-Young; Jeon, Woojin; Tu, Nguyen Dien Kha; Yeo, So Young; Lee, Sang-Soo; Sung, Bong June; Chang, Hyejung; Lim, Jung Ah; Kim, Heesuk

    2015-01-01

    For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000 °C show a maximum boron concentration of 6.04 ± 1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448 F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment. PMID:25940534

  6. Impact resistance of composite fan blades. [fiber reinforced graphite and boron epoxy blades for STOL operating conditions

    NASA Technical Reports Server (NTRS)

    Premont, E. J.; Stubenrauch, K. R.

    1973-01-01

    The resistance of current-design Pratt and Whitney Aircraft low aspect ratio advanced fiber reinforced epoxy matrix composite fan blades to foreign object damage (FOD) at STOL operating conditions was investigated. Five graphite/epoxy and five boron/epoxy wide chord fan blades with nickel plated stainless steel leading edge sheath protection were fabricated and impact tested. The fan blades were individually tested in a vacuum whirlpit under FOD environments. The FOD environments were typical of those encountered in service operations. The impact objects were ice balls, gravel, stralings and gelatin simulated birds. Results of the damage sustained from each FOD impact are presented for both the graphite boron reinforced blades. Tests showed that the present design composite fan blades, with wrap around leading edge protection have inadequate FOD impact resistance at 244 m/sec (800 ft/sec) tip speed, a possible STOL operating condition.

  7. Surface passivation of heavily boron or phosphorus doped crystalline silicon utilizing amorphous silicon

    NASA Astrophysics Data System (ADS)

    Carstens, K.; Dahlinger, M.

    2016-05-01

    Excellent surface passivation of heavily boron or phosphorus doped crystalline silicon is presented utilizing undoped hydrogenated amorphous silicon (a-Si:H). For passivating boron doped crystalline silicon surfaces, amorphous silicon needs to be deposited at low temperatures 150°C ≤Tdep≤200°C , leading to a high bandgap. In contrast, low bandgap amorphous silicon causes an inferior surface passivation of highly boron doped crystalline silicon. Boron doping in crystalline silicon leads to a shift of the Fermi energy towards the valence band maximum in the undoped a-Si:H. A simulation, implementing dangling bond defects according to the defect pool model, shows this shift in the undoped a-Si:H passivation to be more pronounced if the a-Si:H has a lower bandgap. Hence, the inferior passivation of boron doped surfaces with low bandgap amorphous silicon stems from a lower silicon-hydrogen bond energy due to this shift of the Fermi energy. Hydrogen effusion and ellipsometry measurements support our interpretation.

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

    PubMed Central

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

    2009-01-01

    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. PMID:19946362

  9. Boron deactivation in heavily boron-doped Czochralski silicon during rapid thermal anneal: Atomic level understanding

    SciTech Connect

    Gao, Chao; Dong, Peng; Yi, Jun; Ma, Xiangyang E-mail: mxyoung@zju.edu.cn; Yang, Deren; Lu, Yunhao E-mail: mxyoung@zju.edu.cn

    2014-01-20

    The changes in hole concentration of heavily boron (B)-doped Czochralski silicon subjected to high temperature rapid thermal anneal (RTA) and following conventional furnace anneal (CFA) have been investigated. It is found that decrease in hole concentration, namely, B deactivation, is observed starting from 1050 °C and increases with RTA temperature. The following CFA at 300–500 °C leads to further B deactivation, while that at 600–800 °C results in B reactivation. It is supposed that the interaction between B atoms and silicon interstitials (I) thus forming BI pairs leads to the B deactivation during the high temperature RTA, and, moreover, the formation of extended B{sub 2}I complexes results in further B deactivation in the following CFA at 300–500 °C. On the contrary, the dissociation of BI pairs during the following CFA at 600–800 °C enables the B reactivation. Importantly, the first-principles calculation results can soundly account for the above-mentioned supposition.

  10. Ti-doped isotropic graphite: A promising armour material for plasma-facing components

    NASA Astrophysics Data System (ADS)

    García-Rosales, C.; López-Galilea, I.; Ordás, N.; Adelhelm, C.; Balden, M.; Pintsuk, G.; Grattarola, M.; Gualco, C.

    2009-04-01

    Finely dispersed Ti-doped isotropic graphites with 4 at.% Ti have been manufactured using synthetic mesophase pitch 'AR' as raw material. These new materials show a thermal conductivity at room temperature of ˜200 W/mK and flexural strength close to 100 MPa. Measurement of the total erosion yield by deuterium bombardment at ion energies and sample temperatures for which pure carbon shows maximum values, resulted in a reduction of at least a factor of 4, mainly due to dopant enrichment at the surface caused by preferential erosion of carbon. In addition, ITER relevant thermal shock loads were applied with an energetic electron beam at the JUDITH facility. The results demonstrated a significantly improved performance of Ti-doped graphite compared to pure graphite. Finally, Ti-doped graphite was successfully brazed to a CuCrZr block using a Mo interlayer. These results let assume that Ti-doped graphite can be a promising armour material for divertor plasma-facing components.

  11. The crystal structure of aluminum doped {beta}-rhombohedral boron

    SciTech Connect

    Bykova, Elena; Materialphysik und Technologie, Lehrstuhl fuer Kristallographie, Physikalisches Institut, Universitaet Bayreuth, Universitaetsstrasse 30, D-95440 Bayreuth ; Parakhonskiy, Gleb; Materialphysik und Technologie, Lehrstuhl fuer Kristallographie, Physikalisches Institut, Universitaet Bayreuth, Universitaetsstrasse 30, D-95440 Bayreuth ; Dubrovinskaia, Natalia; Chernyshov, Dmitry; Dubrovinsky, Leonid

    2012-10-15

    A crystal structure of aluminum doped {beta}-rhombohedral boron was studied by single-crystal X-ray diffraction at 80 K. The crystals were synthesized using high-pressure high temperature technique at 3 GPa and 2100 K. The structure is based on three-dimensional framework made of B{sub 12} icosahedra with voids occupied by the B{sub 28}-B-B{sub 28} units, it has the R-3m space group with a=10.9014(3), c=23.7225(7) A lattice dimensions in hexagonal setting. Aluminum atoms are located in A1 and D special positions of the {beta}-B structure with occupancies of 82.7(6)% and 11.3(4)%, respectively. Additional boron atoms are located near the D-site. Their possible distribution is discussed. Finally we have found two appropriate structural models whose refinement suggests two possible chemical compositions, AlB{sub 44.8(5)} and AlB{sub 37.8(5)}, which are in a good agreement with the chemical analysis data obtained from EDX. The crystal structure of AlB{sub 44.8(5)} is described in detail. - Graphical abstract: The atomic distribution near the B(15) atom (non-labeled atom in the center of the picture) shown along the c axis. Anisotropic displacement ellipses for Al(2) (D-site) and B(15) are shown with 50 % probability level. The mirror plane with Miller indices (1 1 0) and related to it (-1 2 0) and (-2 1 0) generated by the 3-fold rotation-inversion axis parallel to the c axis splits the position of B(16) over two sites. Highlights: Black-Right-Pointing-Pointer The crystal structure of the AlB{sub 44.8(5)} has been refined. Black-Right-Pointing-Pointer Aluminum atoms partially fill certain types of voids (the A1- and D-sites). Black-Right-Pointing-Pointer We have got two possible models of atomic distribution near the D-site.

  12. Effect of nitrogen on the growth of boron doped single crystal diamond

    SciTech Connect

    Karna, Sunil; Vohra, Yogesh

    2013-11-18

    Boron-doped single crystal diamond films were grown homoepitaxially on synthetic (100) Type Ib diamond substrates using microwave plasma assisted chemical vapor deposition. A modification in surface morphology of the film with increasing boron concentration in the plasma has been observed using atomic force microscopy. Use of nitrogen during boron doping has been found to improve the surface morphology and the growth rate of films but it lowers the electrical conductivity of the film. The Raman spectra indicated a zone center optical phonon mode along with a few additional bands at the lower wavenumber regions. The change in the peak profile of the zone center optical phonon mode and its downshift were observed with the increasing boron content in the film. Furthermore, sharpening and upshift of Raman line was observed in the film that was grown in presence of nitrogen along with diborane in process gas.

  13. Effect of nitrogen on the growth of boron doped single crystal diamond

    DOE PAGESBeta

    Karna, Sunil; Vohra, Yogesh

    2013-11-18

    Boron-doped single crystal diamond films were grown homoepitaxially on synthetic (100) Type Ib diamond substrates using microwave plasma assisted chemical vapor deposition. A modification in surface morphology of the film with increasing boron concentration in the plasma has been observed using atomic force microscopy. Use of nitrogen during boron doping has been found to improve the surface morphology and the growth rate of films but it lowers the electrical conductivity of the film. The Raman spectra indicated a zone center optical phonon mode along with a few additional bands at the lower wavenumber regions. The change in the peak profilemore » of the zone center optical phonon mode and its downshift were observed with the increasing boron content in the film. Furthermore, sharpening and upshift of Raman line was observed in the film that was grown in presence of nitrogen along with diborane in process gas.« less

  14. Formation of Boron-Carbon Nanosheets and Bilayers in Boron-Doped Diamond: Origin of Metallicity and Superconductivity.

    PubMed

    Polyakov, S N; Denisov, V N; Mavrin, B N; Kirichenko, A N; Kuznetsov, M S; Martyushov, S Yu; Terentiev, S A; Blank, V D

    2016-12-01

    The insufficient data on a structure of the boron-doped diamond (BDD) has frustrated efforts to fully understand the fascinating electronic properties of this material and how they evolve with doping. We have employed X-ray diffraction and Raman scattering for detailed study of the large-sized BDD single crystals. We demonstrate a formation of boron-carbon (B-C) nanosheets and bilayers in BDD with increasing boron concentration. An incorporation of two boron atoms in the diamond unit cell plays a key role for the B-C nanosheets and bilayer formation. Evidence for these B-C bilayers which are parallel to {111} planes is provided by the observation of high-order, super-lattice reflections in X-ray diffraction and Laue patterns. B-C nanosheets and bilayers minimize the strain energy and affect the electronic structure of BDD. A new shallow acceptor level associated with B-C nanosheets at ~37 meV and the spin-orbit splitting of the valence band of ~6 meV are observed in electronic Raman scattering. We identified that the superconducting transitions occur in the (111) BDD surfaces only. We believe that the origin of Mott and superconducting transitions is associated with the two-dimensional (2D) misfit layer structure of BDD. A model for the BDD crystal structure, based on X-ray and Raman data, is proposed and confirmed by density functional theoretical calculation. PMID:26754937

  15. Formation of Boron-Carbon Nanosheets and Bilayers in Boron-Doped Diamond: Origin of Metallicity and Superconductivity

    NASA Astrophysics Data System (ADS)

    Polyakov, S. N.; Denisov, V. N.; Mavrin, B. N.; Kirichenko, A. N.; Kuznetsov, M. S.; Martyushov, S. Yu; Terentiev, S. A.; Blank, V. D.

    2016-01-01

    The insufficient data on a structure of the boron-doped diamond (BDD) has frustrated efforts to fully understand the fascinating electronic properties of this material and how they evolve with doping. We have employed X-ray diffraction and Raman scattering for detailed study of the large-sized BDD single crystals. We demonstrate a formation of boron-carbon (B-C) nanosheets and bilayers in BDD with increasing boron concentration. An incorporation of two boron atoms in the diamond unit cell plays a key role for the B-C nanosheets and bilayer formation. Evidence for these B-C bilayers which are parallel to {111} planes is provided by the observation of high-order, super-lattice reflections in X-ray diffraction and Laue patterns. B-C nanosheets and bilayers minimize the strain energy and affect the electronic structure of BDD. A new shallow acceptor level associated with B-C nanosheets at 37 meV and the spin-orbit splitting of the valence band of 6 meV are observed in electronic Raman scattering. We identified that the superconducting transitions occur in the (111) BDD surfaces only. We believe that the origin of Mott and superconducting transitions is associated with the two-dimensional (2D) misfit layer structure of BDD. A model for the BDD crystal structure, based on X-ray and Raman data, is proposed and confirmed by density functional theoretical calculation.

  16. Properties and electrochemical characteristics of boron-doped multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Tsierkezos, Nikos G.; Ritter, Uwe; Nugraha Thaha, Yudi; Krischok, Stefan; Himmerlich, Marcel; Downing, Clive

    2015-10-01

    Boron-doped multi-walled carbon nanotubes were synthesized upon decomposition of ethyl alcohol and boric acid via chemical vapor deposition. The boron-doped nanotubes were treated with hydrochloric acid and were characterized by means of scanning electron and transmission electron microscopy in conjunction with energy-dispersive X-ray spectrometry and X-ray photoelectron spectroscopy. The electrochemistry of ferrocyanide/ferricyanide on boron-doped nanotubes was studied in temperature range of 283.15-303.15 K. The findings exhibit an improvement of films' current response and kinetics of electron transfer with the rise in temperature. The kinetics for electron transfer enhances and the redox process occurs slightly more spontaneously upon acid treatment.

  17. Boron doping effects in electrochromic properties of NiO films prepared by sol-gel

    SciTech Connect

    Lou, Xianchun; Zhao, Xiujian; He, Xin

    2009-12-15

    In this paper, NiO films doped with B{sub 2}O{sub 3} were first prepared by sol-gel. The effects of boron content on the structure and electrochromic properties of NiO films were studied with X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetric (CV) and UV-vis spectrophotometer, respectively. In addition, the roughness and phase of the bleached/colored were studied by atom force microscopy (AFM). B-doped prevent the crystallization of the films. The colored state transmittance could be significantly lowered when the boron added. The NiO film doped with boron exhibited a noticeable electrochromism with a variation of transmittance up to {proportional_to}60% at the wavelength range of 300-500 nm. (author)

  18. Critical boron-doping levels for generation of dislocations in synthetic diamond

    SciTech Connect

    Alegre, M. P. Araújo, D.; Pinero, J. C.; Lloret, F.; Villar, M. P.; Fiori, A.; Achatz, P.; Chicot, G.; Bustarret, E.; Jomard, F.

    2014-10-27

    Defects induced by boron doping in diamond layers were studied by transmission electron microscopy. The existence of a critical boron doping level above which defects are generated is reported. This level is found to be dependent on the CH{sub 4}/H{sub 2} molar ratios and on growth directions. The critical boron concentration lied in the 6.5–17.0 × 10{sup 20}at/cm{sup 3} range in the 〈111〉 direction and at 3.2 × 10{sup 21 }at/cm{sup 3} for the 〈001〉 one. Strain related effects induced by the doping are shown not to be responsible. From the location of dislocations and their Burger vectors, a model is proposed, together with their generation mechanism.

  19. An insight into what superconducts in polycrystalline boron-doped diamonds based on investigations of microstructure

    PubMed Central

    Dubrovinskaia, N.; Wirth, R.; Wosnitza, J.; Papageorgiou, T.; Braun, H. F.; Miyajima, N.; Dubrovinsky, L.

    2008-01-01

    The discovery of superconductivity in polycrystalline boron-doped diamond (BDD) synthesized under high pressure and high temperatures [Ekimov, et al. (2004) Nature 428:542–545] has raised a number of questions on the origin of the superconducting state. It was suggested that the heavy boron doping of diamond eventually leads to superconductivity. To justify such statements more detailed information on the microstructure of the composite materials and on the exact boron content in the diamond grains is needed. For that we used high-resolution transmission electron microscopy and electron energy loss spectroscopy. For the studied superconducting BDD samples synthesized at high pressures and high temperatures the diamond grain sizes are ≈1–2 μm with a boron content between 0.2 (2) and 0.5 (1) at %. The grains are separated by 10- to 20-nm-thick layers and triangular-shaped pockets of predominantly (at least 95 at %) amorphous boron. These results render superconductivity caused by the heavy boron doping in diamond highly unlikely. PMID:18697937

  20. Phonon characteristics and photoluminescence of bamboo structured silicon-doped boron nitride multiwall nanotubes

    NASA Astrophysics Data System (ADS)

    Xu, Shifeng; Fan, Yi; Luo, Jingsong; Zhang, Ligong; Wang, Wenquan; Yao, Bin; An, Linan

    2007-01-01

    Bamboo structured silicon-doped boron nitride multiwall nanotubes are synthesized via catalyst-assisted pyrolysis of a boron-containing polymeric precursor. The nanotubes are characterized using transmission electron microscopy, x-ray diffraction, Raman, and Fourier-transformed infrared spectroscope. The results suggest that the Si dopants cause significant changes in the structure and phonon characteristics of the nanotubes as compared to pure boron nitride nanotubes. A broad photoluminescence band ranging between 500 and 800nm is observed from the nanotubes, which is attributed to Si dopants. Study on temperature dependence of emission intensity suggests that the thermal activation energy of the nonradiative recombination process is 35meV.

  1. Characteristic Study of Boron Doped Carbon Nanowalls Films Deposited by Microwave Plasma Enhanced Chemical Vapor Deposition.

    PubMed

    Lu, Chunyuan; Dong, Qi; Tulugan, Kelimu; Park, Yeong Min; More, Mahendra A; Kim, Jaeho; Kim, Tae Gyu

    2016-02-01

    In this research, catalyst-free vertically aligned boron doped carbon nanowalls films were fabricated on silicon (100) substrates by MPECVD using feeding gases CH4, H2 and B2H6 (diluted with H2 to 5% vol) as precursors. The substrates were pre-seeded with nanodiamond colloid. The fabricated CNWs films were characterized by Scanning Electron Microscopy (SEM) and Raman Spectroscopy. The data obtained from SEM confirms that the CNWs films have different density and wall thickness. From Raman spectrum, a G peak around 1588 cm(-1) and a D band peak at 1362 cm(-1) were observed, which indicates a successful fabrication of CNWs films. The EDX spectrum of boron doped CNWs film shows the existence of boron and carbon. Furthermore, field emission properties of boron doped carbon nanowalls films were measured and field enhancement factor was calculated using Fowler-Nordheim plot. The result indicates that boron doped CNWs films could be potential electron emitting materials. PMID:27433646

  2. Note: Novel diamond anvil cell for electrical measurements using boron-doped metallic diamond electrodes.

    PubMed

    Matsumoto, R; Sasama, Y; Fujioka, M; Irifune, T; Tanaka, M; Yamaguchi, T; Takeya, H; Takano, Y

    2016-07-01

    A novel diamond anvil cell suitable for electrical transport measurements under high pressure has been developed. A boron-doped metallic diamond film was deposited as an electrode on a nano-polycrystalline diamond anvil using a microwave plasma-assisted chemical vapor deposition technique combined with electron beam lithography. The maximum pressure that can be achieved by this assembly is above 30 GPa. We report electrical transport measurements of Pb up to 8 GPa. The boron-doped metallic diamond electrodes showed no signs of degradation after repeated compression. PMID:27475610

  3. Note: Novel diamond anvil cell for electrical measurements using boron-doped metallic diamond electrodes

    NASA Astrophysics Data System (ADS)

    Matsumoto, R.; Sasama, Y.; Fujioka, M.; Irifune, T.; Tanaka, M.; Yamaguchi, T.; Takeya, H.; Takano, Y.

    2016-07-01

    A novel diamond anvil cell suitable for electrical transport measurements under high pressure has been developed. A boron-doped metallic diamond film was deposited as an electrode on a nano-polycrystalline diamond anvil using a microwave plasma-assisted chemical vapor deposition technique combined with electron beam lithography. The maximum pressure that can be achieved by this assembly is above 30 GPa. We report electrical transport measurements of Pb up to 8 GPa. The boron-doped metallic diamond electrodes showed no signs of degradation after repeated compression.

  4. Detecting CO, NO and NO2 gases by Boron-doped graphene nanoribbon molecular devices

    NASA Astrophysics Data System (ADS)

    Xie, Zhen; Zuo, Xi; Zhang, Guang-Ping; Li, Zong-Liang; Wang, Chuan-Kui

    2016-07-01

    Combining nonequilibrium Green's function method and density functional theory, an azulene-like dipole molecule sandwiched between two graphene nanoribbon (GNR) electrodes are explored to gas sensors. Both the pristine zigzag edged GNR and Boron-doped armchair-edged GNR are considered in this study. It shows that certain specific toxic molecules CO, NO and NO2 would adsorb on the doped Boron atoms of the GNR, resulting in a dramatic change in the current-voltage profile. Changes in the subbands of electrodes, induced by gas adsorption, are responsible for the variation of current. The devices are thus demonstrated to be sensitive nanosensors for these toxic gases.

  5. Boron-Doped Silicon Diatom Frustules as a Photocathode for Water Splitting.

    PubMed

    Chandrasekaran, Soundarrajan; Macdonald, Thomas J; Gerson, Andrea R; Nann, Thomas; Voelcker, Nicolas H

    2015-08-12

    An effective solar-powered silicon device for hydrogen production from water splitting is a priority in light of diminishing fossil fuel vectors. There is increasing demand for nanostructuring in silicon to improve its antireflective properties for efficient solar energy conversion. Diatom frustules are naturally occurring biosilica nanostructures formed by biomineralizing microalgae. Here, we demonstrate magnesiothermic conversion of boron-doped silica diatom frustules from Aulacoseira sp. into nanostructured silicon with retention of the original shape. Hydrogen production was achieved for boron-doped silicon diatom frustules coated with indium phosphide nanocrystal layers and an iron sulfur carbonyl electrocatalyst. PMID:26192101

  6. Structural and electronic properties of boron-doped double-walled silicon carbide nanotubes

    NASA Astrophysics Data System (ADS)

    Behzad, Somayeh; Moradian, Rostam; Chegel, Raad

    2010-12-01

    The effects of boron doping on the structural and electronic properties of (6,0)@(14,0) double-walled silicon carbide nanotube (DWSiCNT) are investigated by using spin-polarized density functional theory. It is found that boron atom could be more easily doped in the inner tube. Our calculations indicate that a Si site is favorable for B under C-rich condition and a C site is favorable under Si-rich condition. Additionally, B-substitution at either single carbon or silicon atom site in DWSiCNT could induce spontaneous magnetization.

  7. Boron

    MedlinePlus

    Boron is a mineral that is found in food and the environment. People take boron supplements as medicine. Boron is used for building ... to affect the way the body handles other minerals such as magnesium and phosphorus. It also seems ...

  8. Dynamics of formation of Ru, Os, Ir and Au metal nanocrystals on doped graphitic surfaces.

    PubMed

    Pitto-Barry, Anaïs; Sadler, Peter J; Barry, Nicolas P E

    2016-03-11

    The fabrication of precious metal (ruthenium, osmium, gold, and iridium) nanocrystals from single atoms has been studied in real-time. The dynamics of the first stage of the metal nanocrystallisation on a doped (B,S)-graphitic surface are identified, captured, and reported. PMID:26698913

  9. Synthesis of ultra dispersed graphite-like structures doped with nitrogen in supersonic carbon plasma flow

    NASA Astrophysics Data System (ADS)

    Sivkov, A.; Pak, A.; Shanenkov, I.; Kolganova, J.; Shatrova, K.

    2014-10-01

    In this paper the synthesis of ultra dispersed graphite-like structures doped with nitrogen by using a magneto plasma accelerator is shown. The synthesis of such structures is realized during supersonic carbon plasma jet flowing into the chamber filled with the nitrogen atmosphere. Plasma jet is generated by coaxial magneto plasma accelerator (CMPA) based on graphite electrode system. The CMPA is supplied from the pulsed capacitive energy storage with the maximum value of stored energy of 360 kJ. Electrical and energy parameters of plasma flow are recorded during experiment. According to X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) methods obtained particles with well seen triangle sectors are graphite-like carbon structures doped with nitrogen atoms. This is confirmed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy analyses in which carbon- nitrogen bonding configurations have been identified.

  10. Study of the roles of chemical modifiers in determining boron using graphite furnace atomic absorption spectrometry and optimization of the temperature profile during atomization.

    PubMed

    Yamamoto, Yuhei; Shirasaki, Toshihiro; Yonetani, Akira; Imai, Shoji

    2015-01-01

    The measurement conditions for determining boron using graphite furnace-atomic absorption spectrometry (GF-AAS) were investigated. Differences in the boron absorbance profiles were found using three different commercially available GF-AAS instruments when the graphite atomizers in them were not tuned. The boron absorbances found with and without adjusting the graphite atomizers suggested that achieving an adequate absorbance for the determination of boron requires a sharp temperature profile that overshoots the target temperature during the atomization process. Chemical modifiers that could improve the boron absorbance without the need for using coating agents were tested. Calcium carbonate improved the boron absorbance but did not suppress variability in the peak height. Improvement of boron absorbance was comparatively less using iron nitrate or copper nitrate than using calcium carbonate, but variability in the peak height was clearly suppressed using iron nitrate or copper nitrate. The limit of detection was 0.0026 mg L(-1) when iron nitrate was used. It appears that iron nitrate is a useful new chemical modifier for the quick and simple determination of boron using GF-AAS. PMID:25958863

  11. DFT study on the structural and electronic properties of Pt-doped boron nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Vessally, E.; Dehbandi, B.; Edjlali, Ladan

    2016-06-01

    First-principles calculations based on density functional theory were carried out to investigate the structural and electronic properties of Pt substitution-doped boron nitride (BN) nanotubes. The electronic and structural properties were studied for substituted Pt in the boron and the nitrogen sites of the (BN) nanotube. The band gap significantly diminishes to 2.095 eV for Pt doping at the B site while the band gap diminishes to 2.231 eV for Pt doping at the N site. The band density increases in both the valence band and the conduction band after doping. The effects of the hardness and softness group 17 (halogen elements) were calculated by density functional theory (DFT).

  12. New Pathways and Metrics for Enhanced, Reversible Hydrogen Storage in Boron-Doped Carbon Nanospaces

    SciTech Connect

    Pfeifer, Peter; Wexler, Carlos; Hawthorne, M. Frederick; Lee, Mark W.; Jalistegi, Satish S.

    2014-08-14

    This project, since its start in 2007—entitled “Networks of boron-doped carbon nanopores for low-pressure reversible hydrogen storage” (2007-10) and “New pathways and metrics for enhanced, reversible hydrogen storage in boron-doped carbon nanospaces” (2010-13)—is in support of the DOE's National Hydrogen Storage Project, as part of the DOE Hydrogen and Fuel Cells Program’s comprehensive efforts to enable the widespread commercialization of hydrogen and fuel cell technologies in diverse sectors of the economy. Hydrogen storage is widely recognized as a critical enabling technology for the successful commercialization and market acceptance of hydrogen powered vehicles. Storing sufficient hydrogen on board a wide range of vehicle platforms, at energy densities comparable to gasoline, without compromising passenger or cargo space, remains an outstanding technical challenge. Of the main three thrust areas in 2007—metal hydrides, chemical hydrogen storage, and sorption-based hydrogen storage—sorption-based storage, i.e., storage of molecular hydrogen by adsorption on high-surface-area materials (carbons, metal-organic frameworks, and other porous organic networks), has emerged as the most promising path toward achieving the 2017 DOE storage targets of 0.055 kg H2/kg system (“5.5 wt%”) and 0.040 kg H2/liter system. The objective of the project is to develop high-surface-area carbon materials that are boron-doped by incorporation of boron into the carbon lattice at the outset, i.e., during the synthesis of the material. The rationale for boron-doping is the prediction that boron atoms in carbon will raise the binding energy of hydro- gen from 4-5 kJ/mol on the undoped surface to 10-14 kJ/mol on a doped surface, and accordingly the hydro- gen storage capacity of the material. The mechanism for the increase in binding energy is electron donation from H2 to electron-deficient B atoms, in the form of sp2 boron-carbon bonds. Our team is proud to have

  13. Cat-doping: Novel method for phosphorus and boron shallow doping in crystalline silicon at 80 °C

    NASA Astrophysics Data System (ADS)

    Matsumura, Hideki; Hayakawa, Taro; Ohta, Tatsunori; Nakashima, Yuki; Miyamoto, Motoharu; Thi, Trinh Cham; Koyama, Koichi; Ohdaira, Keisuke

    2014-09-01

    Phosphorus (P) or boron (B) atoms can be doped at temperatures as low as 80 to 350 °C, when crystalline silicon (c-Si) is exposed only for a few minutes to species generated by catalytic cracking reaction of phosphine (PH3) or diborane (B2H6) with heated tungsten (W) catalyzer. This paper is to investigate systematically this novel doping method, "Cat-doping", in detail. The electrical properties of P or B doped layers are studied by the Van der Pauw method based on the Hall effects measurement. The profiles of P or B atoms in c-Si are observed by secondary ion mass spectrometry mainly from back side of samples to eliminate knock-on effects. It is confirmed that the surface of p-type c-Si is converted to n-type by P Cat-doping at 80 °C, and similarly, that of n-type c-Si is to p-type by B Cat-doping. The doping depth is as shallow as 5 nm or less and the electrically activated doping concentration is 1018 to 1019 cm-3 for both P and B doping. It is also found that the surface potential of c-Si is controlled by the shallow Cat-doping and that the surface recombination velocity of minority carriers in c-Si can be enormously lowered by this potential control.

  14. Resonance of graphene nanoribbons doped with nitrogen and boron: a molecular dynamics study.

    PubMed

    Wei, Ye; Zhan, Haifei; Xia, Kang; Zhang, Wendong; Sang, Shengbo; Gu, Yuantong

    2014-01-01

    Based on its enticing properties, graphene has been envisioned with applications in the area of electronics, photonics, sensors, bio-applications and others. To facilitate various applications, doping has been frequently used to manipulate the properties of graphene. Despite a number of studies conducted on doped graphene regarding its electrical and chemical properties, the impact of doping on the mechanical properties of graphene has been rarely discussed. A systematic study of the vibrational properties of graphene doped with nitrogen and boron is performed by means of a molecular dynamics simulation. The influence from different density or species of dopants has been assessed. It is found that the impacts on the quality factor, Q, resulting from different densities of dopants vary greatly, while the influence on the resonance frequency is insignificant. The reduction of the resonance frequency caused by doping with boron only is larger than the reduction caused by doping with both boron and nitrogen. This study gives a fundamental understanding of the resonance of graphene with different dopants, which may benefit their application as resonators. PMID:24991509

  15. Ultrasensitive gas detection of large-area boron-doped graphene

    PubMed Central

    Lv, Ruitao; Chen, Gugang; Li, Qing; McCreary, Amber; Botello-Méndez, Andrés; Morozov, S. V.; Declerck, Xavier; Perea-López, Nestor; Cullen, David A.; Feng, Simin; Elías, Ana Laura; Cruz-Silva, Rodolfo; Fujisawa, Kazunori; Endo, Morinobu; Kang, Feiyu; Charlier, Jean-Christophe; Meunier, Vincent; Pan, Minghu; Harutyunyan, Avetik R.; Novoselov, Konstantin S.; Terrones, Mauricio

    2015-01-01

    Heteroatom doping is an efficient way to modify the chemical and electronic properties of graphene. In particular, boron doping is expected to induce a p-type (boron)-conducting behavior to pristine (nondoped) graphene, which could lead to diverse applications. However, the experimental progress on atomic scale visualization and sensing properties of large-area boron-doped graphene (BG) sheets is still very scarce. This work describes the controlled growth of centimeter size, high-crystallinity BG sheets. Scanning tunneling microscopy and spectroscopy are used to visualize the atomic structure and the local density of states around boron dopants. It is confirmed that BG behaves as a p-type conductor and a unique croissant-like feature is frequently observed within the BG lattice, which is caused by the presence of boron-carbon trimers embedded within the hexagonal lattice. More interestingly, it is demonstrated for the first time that BG exhibits unique sensing capabilities when detecting toxic gases, such as NO2 and NH3, being able to detect extremely low concentrations (e.g., parts per trillion, parts per billion). This work envisions that other attractive applications could now be explored based on as-synthesized BG. PMID:26575621

  16. Biophotonic low-coherence sensors with boron-doped diamond thin layer

    NASA Astrophysics Data System (ADS)

    Milewska, D.; Karpienko, K.; Sobaszek, M.; Jedrzejewska-Szczerska, M.

    2016-03-01

    Low-coherence sensors using Fabry-Perot interferometers are finding new applications in biophotonic sensing, especially due to the rapid technological advances in the development of new materials. In this paper we discuss the possibility of using boron-doped nanodiamond layers to protect mirror in a Fabry-Perot interferometer. A low-coherence sensor using Fabry-Perot interferometer with a boron-doped nanodiamond (B-NCD) thin protective layer has been developed. B-NCD layers with different boron doping level were investigated. The boron level, expressed as the boron to carbon (/[C]) ratio in the gas phase, was: 0, 2000, 5000 or 10000 ppm. B-NCD layers were grown by chemical vapor deposition (CVD). The sensing Fabry-Perot interferometer, working in the reflective mode, was connected to the source and to the optical processor by single-mode fibers. Superluminescent diodes with Gaussian spectral density were used as sources, while an optical spectrum analyzer was used as an optical processor. The design of the sensing interferometer was optimized to attain the maximum interference contrast. The experiment has shown that B-NCD thin layers can be successfully used in biophotonic sensors.

  17. Biocompatibility of nanostructured boron doped diamond for the attachment and proliferation of human neural stem cells

    NASA Astrophysics Data System (ADS)

    Taylor, Alice C.; Vagaska, Barbora; Edgington, Robert; Hébert, Clément; Ferretti, Patrizia; Bergonzo, Philippe; Jackman, Richard B.

    2015-12-01

    Objective. We quantitatively investigate the biocompatibility of chemical vapour deposited (CVD) nanocrystalline diamond (NCD) after the inclusion of boron, with and without nanostructuring. The nanostructuring method involves a novel approach of growing NCD over carbon nanotubes (CNTs) that act as a 3D scaffold. This nanostructuring of BNCD leads to a material with increased capacitance, and this along with wide electrochemical window makes BNCD an ideal material for neural interface applications, and thus it is essential that their biocompatibility is investigated. Approach. Biocompatibility was assessed by observing the interaction of human neural stem cells (hNSCs) with a variety of NCD substrates including un-doped ones, and NCD doped with boron, which are both planar, and nanostructured. hNSCs were chosen due to their sensitivity, and various methods including cell population and confluency were used to quantify biocompatibility. Main results. Boron inclusion into NCD film was shown to have no observable effect on hNSC attachment, proliferation and viability. Furthermore, the biocompatibility of nanostructured boron-doped NCD is increased upon nanostructuring, potentially due to the increased surface area. Significance. Diamond is an attractive material for supporting the attachment and development of cells as it can show exceptional biocompatibility. When boron is used as a dopant within diamond it becomes a p-type semiconductor, and at high concentrations the diamond becomes quasi-metallic, offering the prospect of a direct electrical device-cell interfacing system.

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

    NASA Astrophysics Data System (ADS)

    Zhen, Tiejun

    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.

  19. Visible and Infra-red Light Emission in Boron-Doped Wurtzite Silicon Nanowires

    PubMed Central

    Fabbri, Filippo; Rotunno, Enzo; Lazzarini, Laura; Fukata, Naoki; Salviati, Giancarlo

    2014-01-01

    Silicon, the mainstay semiconductor in microelectronic circuitry, is considered unsuitable for optoelectronic applications owing to its indirect electronic band gap, which limits its efficiency as a light emitter. Here we show the light emission properties of boron-doped wurtzite silicon nanowires measured by cathodoluminescence spectroscopy at room temperature. A visible emission, peaked above 1.5 eV, and a near infra-red emission at 0.8 eV correlate respectively to the direct transition at the Γ point and to the indirect band-gap of wurtzite silicon. We find additional intense emissions due to boron intra-gap states in the short wavelength infra-red range. We present the evolution of the light emission properties as function of the boron doping concentration and the growth temperature. PMID:24398782

  20. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOEpatents

    Corman, Gregory Scot; Luthra, Krishan Lal

    2002-01-01

    A fiber-reinforced silicon-silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon-silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  1. Anodic coupling of guaiacol derivatives on boron-doped diamond electrodes.

    PubMed

    Kirste, Axel; Schnakenburg, Gregor; Waldvogel, Siegfried R

    2011-06-17

    The anodic treatment of guaiacol derivatives on boron-doped diamond electrodes (BDD) provides a direct access to nonsymmetrical biphenols, which would require a multistep sequence by conventional methods. Despite the destructive nature of BDD anodes they can be exploited for chemical synthesis. PMID:21608986

  2. A hydrophobic three-dimensionally networked boron-doped diamond electrode towards electrochemical oxidation.

    PubMed

    He, Yapeng; Lin, Haibo; Wang, Xue; Huang, Weimin; Chen, Rongling; Li, Hongdong

    2016-06-28

    A boron-doped diamond electrode with a three-dimensional network was fabricated on a mesh titanium substrate. Properties such as higher surface area, enhanced mass transfer and a hydrophobic surface endowed the prepared electrode with excellent electrochemical oxidation ability towards contaminants. PMID:27264247

  3. The atomic and electronic structure of nitrogen- and boron-doped phosphorene.

    PubMed

    Boukhvalov, Danil W

    2015-10-28

    First principles modeling of nitrogen- and boron-doped phosphorene demonstrates the tendency toward the formation of highly ordered structures. Nitrogen doping leads to the formation of -N-P-P-P-N- lines. Further transformation into -P-N-P-N- lines across the chains of phosphorene occurs with increasing band gap and increasing nitrogen concentration, which coincides with the decreasing chemical activity of N-doped phosphorene. In contrast to the case of nitrogen, boron atoms prefer to form -B-B- pairs with the further formation of -P-P-B-B-P-P- patterns along the phosphorene chains. The low concentration of boron dopants converts the phosphorene from a semiconductor into a semimetal with the simultaneous enhancement of its chemical activity. Co-doping of phosphorene by both boron and nitrogen starts from the formation of -B-N- pairs, which provides flat bands and further transformation of these pairs into hexagonal BN lines and ribbons across the phosphorene chains. PMID:26417893

  4. Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

    DOEpatents

    Corman, Gregory Scot; Luthra, Krishan Lal

    1999-01-01

    A fiber-reinforced silicon--silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon--silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

  5. Controlled in situ boron doping of short silicon nanowires grown by molecular beam epitaxy

    SciTech Connect

    Das Kanungo, Pratyush; Zakharov, Nikolai; Bauer, Jan; Breitenstein, Otwin; Werner, Peter; Goesele, Ulrich

    2008-06-30

    Epitaxial silicon nanowires (NWs) of short heights ({approx}280 nm) on Si <111> substrate were grown and doped in situ with boron on a concentration range of 10{sup 15}-10{sup 19} cm{sup -3} by coevaporation of atomic Si and B by molecular beam epitaxy. Transmission electron microscopy revealed a single-crystalline structure of the NWs. Electrical measurements of the individual NWs confirmed the doping. However, the low doped (10{sup 15} cm{sup -3}) and medium doped (3x10{sup 16} and 1x10{sup 17} cm{sup -3}) NWs were heavily depleted by the surface states while the high doped (10{sup 18} and 10{sup 19} cm{sup -3}) ones showed volume conductivities expected for the corresponding intended doping levels.

  6. Heavily boron-doped Si layers grown below 700 C by molecular beam epitaxy using a HBO2 source

    NASA Technical Reports Server (NTRS)

    Lin, T. L.; Fathauer, R. W.; Grunthaner, P. J.

    1989-01-01

    Boron doping in Si layers grown by molecular beam epitaxy (MBE) at 500-700 C using an HBO2 source has been studied. The maximum boron concentration without detectable oxygen incorporation for a given substrate temperature and Si growth rate has been determined using secondary-ion mass spectrometry analysis. Boron present in the Si MBE layers grown at 550-700 C was found to be electrically active, independent of the amount of oxygen incorporation. By reducing the Si growth rate, highly boron-doped layers have been grown at 600 C without detectable oxygen incorporation.

  7. Sulfur-doped graphene via thermal exfoliation of graphite oxide in H2S, SO2, or CS2 gas.

    PubMed

    Poh, Hwee Ling; Šimek, Petr; Sofer, Zdeněk; Pumera, Martin

    2013-06-25

    Doping of graphene with heteroatoms is an effective way to tailor its properties. Here we describe a simple and scalable method of doping graphene lattice with sulfur atoms during the thermal exfoliation process of graphite oxides. The graphite oxides were first prepared by Staudenmaier, Hofmann, and Hummers methods followed by treatments in hydrogen sulfide, sulfur dioxide, or carbon disulfide. The doped materials were characterized by scanning electron microscopy, high-resolution X-ray photoelectron spectroscopy, combustible elemental analysis, and Raman spectroscopy. The ζ-potential and conductivity of sulfur-doped graphenes were also investigated in this paper. It was found that the level of doping is more dramatically influenced by the type of graphite oxide used rather than the type of sulfur-containing gas used during exfoliation. Resulting sulfur-doped graphenes act as metal-free electrocatalysts for an oxygen reduction reaction. PMID:23656223

  8. Cat-doping: Novel method for phosphorus and boron shallow doping in crystalline silicon at 80 °C

    SciTech Connect

    Matsumura, Hideki; Hayakawa, Taro; Ohta, Tatsunori; Nakashima, Yuki; Miyamoto, Motoharu; Thi, Trinh Cham; Koyama, Koichi; Ohdaira, Keisuke

    2014-09-21

    Phosphorus (P) or boron (B) atoms can be doped at temperatures as low as 80 to 350 °C, when crystalline silicon (c-Si) is exposed only for a few minutes to species generated by catalytic cracking reaction of phosphine (PH₃) or diborane (B₂H₆) with heated tungsten (W) catalyzer. This paper is to investigate systematically this novel doping method, “Cat-doping”, in detail. The electrical properties of P or B doped layers are studied by the Van der Pauw method based on the Hall effects measurement. The profiles of P or B atoms in c-Si are observed by secondary ion mass spectrometry mainly from back side of samples to eliminate knock-on effects. It is confirmed that the surface of p-type c-Si is converted to n-type by P Cat-doping at 80 °C, and similarly, that of n-type c-Si is to p-type by B Cat-doping. The doping depth is as shallow as 5 nm or less and the electrically activated doping concentration is 10¹⁸ to 10¹⁹cm⁻³ for both P and B doping. It is also found that the surface potential of c-Si is controlled by the shallow Cat-doping and that the surface recombination velocity of minority carriers in c-Si can be enormously lowered by this potential control.

  9. Boosting the Boron Dopant Level in Monolayer Doping by Carboranes.

    PubMed

    Ye, Liang; González-Campo, Arántzazu; Núñez, Rosario; de Jong, Michel P; Kudernac, Tibor; van der Wiel, Wilfred G; Huskens, Jurriaan

    2015-12-16

    Monolayer doping (MLD) presents an alternative method to achieve silicon doping without causing crystal damage, and it has the capability of ultrashallow doping and the doping of nonplanar surfaces. MLD utilizes dopant-containing alkene molecules that form a monolayer on the silicon surface using the well-established hydrosilylation process. Here, we demonstrate that MLD can be extended to high doping levels by designing alkenes with a high content of dopant atoms. Concretely, carborane derivatives, which have 10 B atoms per molecule, were functionalized with an alkene group. MLD using a monolayer of such a derivative yielded up to ten times higher doping levels, as measured by X-ray photoelectron spectroscopy and dynamic secondary mass spectroscopy, compared to an alkene with a single B atom. Sheet resistance measurements showed comparably increased conductivities of the Si substrates. Thermal budget analyses indicate that the doping level can be further optimized by changing the annealing conditions. PMID:26595856

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

    PubMed

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

    2013-03-01

    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

  11. Carbon doping in molecular beam epitaxy of GaAs from a heated graphite filament

    NASA Technical Reports Server (NTRS)

    Malik, R. J.; Nottenberg, R. N.; Schubert, E. F.; Walker, J. F.; Ryan, R. W.

    1988-01-01

    Carbon doping of GaAs grown by molecular beam epitaxy has been obtained for the first time by use of a heated graphite filament. Controlled carbon acceptor concentrations over the range of 10 to the 17th-10 to the 20th/cu cm were achieved by resistively heating a graphite filament with a direct current power supply. Capacitance-voltage, p/n junction and secondary-ion mass spectrometry measurements indicate that there is negligible diffusion of carbon during growth and with postgrowth rapid thermal annealing. Carbon was used for p-type doping in the base of Npn AlGaAs/GaAs heterojunction bipolar transistors. Current gains greater than 100 and near-ideal emitter heterojunctions were obtained in transistors with a carbon base doping of 1 x 10 to the 19th/cu cm. These preliminary results indicate that carbon doping from a solid graphite source may be an attractive substitute for beryllium, which is known to have a relatively high diffusion coefficient in GaAs.

  12. Isolated boron and nitrogen sites on porous graphitic carbon synthesized from nitrogen-containing chitosan for supercapacitors.

    PubMed

    Sun, Li; Fu, Yu; Tian, Chungui; Yang, Ying; Wang, Lei; Yin, Jie; Ma, Jing; Wang, Ruihong; Fu, Honggang

    2014-06-01

    Separated boron and nitrogen porous graphitic carbon (BNGC) is fabricated by a facile hydrothermal coordination/ZnCl2-activation process from renewable and inexpensive nitrogen-containing chitosan. In this synthetic pathway, chitosan, which has a high nitrogen content, first coordinates with Fe(3+) ions to form chitosan-Fe that subsequently reacts with boric acid (boron source) to generate the BNGC precursor. After simultaneous carbonization and ZnCl2 activation followed by removal of the Fe catalyst, BNGC, containing isolated boron and nitrogen centers and having a high surface area of 1567 m(2)  g(-1) and good conductivity, can be obtained. Results indicate that use of chitosan as a nitrogen-containing carbon source effectively prevents nitrogen atoms from direct combination with boron atoms. In addition, the incorporation of Fe(3+) ions not only endows BNGC with high graphitization, but also favors for nitrogen fixation. Remarkably, the unique microstructure of BNGC enables its use as an advanced electrode material for energy storage. As electrode material for supercapacitors, BNGC shows a high capacitance of 313 F g(-1) at 1 A g(-1), and also long-term durability and coulombic efficiency of >99.5 % after 5000 cycles. Notably, in organic electrolytes, the energy density could be up to 50.1 Wh kg(-1) at a power density of 10.5 kW kg(-1). The strategy developed herein opens a new avenue to prepare BNGC without inactive BN bonds from commercially available chitosan for high-performance supercapacitors. PMID:24692324

  13. Adsorption of sugars on Al- and Ga-doped boron nitride surfaces: A computational study

    NASA Astrophysics Data System (ADS)

    Darwish, Ahmed A.; Fadlallah, Mohamed M.; Badawi, Ashraf; Maarouf, Ahmed A.

    2016-07-01

    Molecular adsorption on surfaces is a key element for many applications, including sensing and catalysis. Non-invasive sugar sensing has been an active area of research due to its importance to diabetes care. The adsorption of sugars on a template surface study is at the heart of matter. Here, we study doped hexagonal boron nitride sheets (h-BNNs) as adsorbing and sensing template for glucose and glucosamine. Using first principles calculations, we find that the adsorption of glucose and glucosamine on h-BNNs is significantly enhanced by the substitutional doping of the sheet with Al and Ga. Including long range van der Waals corrections gives adsorption energies of about 2 eV. In addition to the charge transfer occurring between glucose and the Al/Ga-doped BN sheets, the adsorption alters the size of the band gap, allowing for optical detection of adsorption. We also find that Al-doped boron nitride sheet is better than Ga-doped boron nitride sheet to enhance the adsorption energy of glucose and glucosamine. The results of our work can be potentially utilized when designing support templates for glucose and glucosamine.

  14. Nickel doping of boron carbide grown by plasma enhanced chemical vapor deposition

    SciTech Connect

    Hwang, S.; Remmes, N.B.; Dowben, P.A.; McIlroy, D.N.

    1996-07-01

    We have nickel doped boron carbide grown by plasma enhanced chemical vapor deposition. The source gas closo-1,2-dicarbadodecaborane (ortho-carborane) was used to grow the boron carbide, while nickelocene [Ni(C{sub 5}H{sub 5}){sub 2}] was used to introduce nickel into the growing film. The doping of nickel transformed a {ital p}-type, B{sub 5}C material, relative to lightly doped {ital n}-type silicon, to an {ital n}-type material. Both {ital n}-{ital n} heterojunction diodes and {ital n}-{ital p} heterojunction diodes were constructed, using as substrates {ital n}- and {ital p}-type Si(111), respectively. With sufficient partial pressures of nickelocene in the plasma reactor, diodes with characteristic tunnel diode behavior can be successfully fabricated. {copyright} {ital 1996 American Vacuum Society}

  15. Transport properties of boron-doped single-walled silicon carbide nanotubes

    NASA Astrophysics Data System (ADS)

    Yang, Y. T.; Ding, R. X.; Song, J. X.

    2011-01-01

    The doped boron (B) atom in silicon carbide nanotube (SiCNT) can substitute carbon or silicon atom, forming two different structures. The transport properties of both B-doped SiCNT structures are investigated by the method combined non-equilibrium Green’s function with density functional theory (DFT). As the bias ranging from 0.8 to 1.0 V, the negative differential resistance (NDR) effect occurs, which is derived from the great difficulty for electrons tunneling from one electrode to another with the increasing of localization of molecular orbital. The high similar transport properties of both B-doped SiCNT indicate that boron is a suitable impurity for fabricating nano-scale SiCNT electronic devices.

  16. Boron doping to diamond and DLC using plasma immersion ion implantation

    SciTech Connect

    Ikegami, T.; Grotjohn; Reinhard, D.; Asmussen, J.

    1997-12-31

    Controlling carriers in diamond by doping is important to realize diamond electronic devices with advanced electrical characteristics. As a doping method the Plasma Immersion Ion Implantation (PIII) has been gathering attention due to its excellence in making shallow, highly doped regions over large areas, and its high dose rate, good dose controllability and isotropic doping properties. The authors have begun to investigate boron doping of diamond, silicon and diamond-like carbon films using PIII. As a doping source they use the plasma sputtering of a solid boron carbide (B{sub 4}C) target instead of toxic gas source like diborane (B{sub 2}H{sub 6}). The B{sub 4}C target of 1-in. diameter and a substrate (Si, diamond or diamond-like carbon film) are located in the downtown region of an ECR plasma produced by the microwave plasma disc reactor (MPDR) filled with 1--5 mTorr Ar gas. In order to sputter the target a negative self bias from {minus}400V to {minus}700V is induced by applying RF (13.56 MHz) power of 50--200W to the target holder. For boron ion implantation, negative pulses of {minus}1kV to {minus}8kV, 1--5{micro}s pulse duration, 1--200Hz repetition rate are applied to the substrate holder using a voltage pulser which consists of high voltage capacitors and MOSFETs. After thermal treatment of the doped materials their electrical resistivity are measured using the four-probe method. Details of both the PIII source and substrate doping experimental results are shown at the meeting.

  17. Boron-Doped Strontium-Stabilized Bismuth Cobalt Oxide Thermoelectric Nanocrystalline Ceramic Powders Synthesized via Electrospinning

    NASA Astrophysics Data System (ADS)

    Koçyiğit, Serhat; Aytimur, Arda; Çınar, Emre; Uslu, İbrahim; Akdemir, Ahmet

    2014-01-01

    Boron-doped strontium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by using a polymeric precursor technique. The powders were characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), and physical properties measurement system (PPMS) techniques. The XRD results showed that these patterns have a two-phase mixture. The phases are face-centered cubic (fcc) and body-centered cubic (bcc). Values of the crystallite size, dislocation density, and microstrain were calculated by using the Scherrer equation. The lattice parameters were calculated for fcc and bcc phases. The SEM results showed that needle-like grains are formed in boron-undoped composite materials, but the needle-like grains changed to the plate-like grains with the addition of boron. The distribution of the nanofiber diameters was calculated and the average diameter of the boron-doped sample is smaller than the boron-undoped one. PPMS values showed that the electrical resistivity values decreased, but the thermal conductivity values, the Seebeck coefficients, and figure of merit ( ZT) increased with increasing temperature for the two samples.

  18. Spatial Control of Laser-Induced Doping Profiles in Graphene on Hexagonal Boron Nitride.

    PubMed

    Neumann, Christoph; Rizzi, Leo; Reichardt, Sven; Terrés, Bernat; Khodkov, Timofiy; Watanabe, Kenji; Taniguchi, Takashi; Beschoten, Bernd; Stampfer, Christoph

    2016-04-13

    We present a method to create and erase spatially resolved doping profiles in graphene-hexagonal boron nitride heterostructures. The technique is based on photoinduced doping by a focused laser beam and does neither require masks nor photoresists. This makes our technique interesting for rapid prototyping of unconventional electronic device schemes, where the spatial resolution of the rewritable, long-term stable doping profiles is limited by only the laser spot size (≈600 nm) and the accuracy of sample positioning. Our optical doping method offers a way to implement and to test different, complex doping patterns in one and the very same graphene device, which is not achievable with conventional gating techniques. PMID:26986938

  19. Photo-induced Modulation Doping in Graphene/Boron nitride Heterostructures

    NASA Astrophysics Data System (ADS)

    Velasco, Jairo, Jr.; Ju, Long; Hwang, Edwin; Kahn, Salman; Nosiglia, Casey; Tsai, Hsin-Zon; Yang, Wei; Zhang, Guangyu; Taniguchi, Takashi; Watanabe, Kenji; Zhang, Yuanbo; Crommie, Michael; Zettl, Alex; Wang, Feng

    2014-03-01

    Van der Waals heterostructures (VDH) provide an exciting new platform for materials engineering, where a variety of layered materials with different electrical, optical and mechanical responses can be stacked together to enable new physics and novel functionalities. We report an emerging optoelectronic phenomenon (i.e. photo-induced modulation doping) in the graphene-boron nitride VDH (G/BN heterostructure). We find it enables flexible and repeatable writing and erasing of charge doping in graphene with optical light. We show that the photo-induced modulation doping maintains the remarkable carrier mobility of the G/BN heterostructure, and it can be used to generate spatially varying doping profiles like pn junctions. Our work contributes towards understanding light matter interactions in VDHs, and introduces a simple technique for creating inhomogeneous doping in high mobility graphene devices. J. Velasco Jr. acknowledges support from UC President's Postdoctoral Fellowship.

  20. Observation of Landau levels on nitrogen-doped flat graphite surfaces without external magnetic fields

    NASA Astrophysics Data System (ADS)

    Kondo, Takahiro; Guo, Donghui; Shikano, Taishi; Suzuki, Tetsuya; Sakurai, Masataka; Okada, Susumu; Nakamura, Junji

    2015-11-01

    Under perpendicular external magnetic fields, two-dimensional carriers exhibit Landau levels (LLs). However, it has recently been reported that LLs have been observed on graphene and graphite surfaces without external magnetic fields being applied. These anomalous LLs have been ascribed primarily to a strain of graphene sheets, leading to in-plane hopping modulation of electrons. Here, we report the observation of the LLs of massive Dirac fermions on atomically flat areas of a nitrogen-doped graphite surface in the absence of external magnetic fields. The corresponding magnetic fields were estimated to be as much as approximately 100 T. The generation of the LLs at the area with negligible strain can be explained by inequivalent hopping of π electrons that takes place at the perimeter of high-potential domains surrounded by positively charged substituted graphitic-nitrogen atoms.

  1. Observation of Landau levels on nitrogen-doped flat graphite surfaces without external magnetic fields

    PubMed Central

    Kondo, Takahiro; Guo, Donghui; Shikano, Taishi; Suzuki, Tetsuya; Sakurai, Masataka; Okada, Susumu; Nakamura, Junji

    2015-01-01

    Under perpendicular external magnetic fields, two-dimensional carriers exhibit Landau levels (LLs). However, it has recently been reported that LLs have been observed on graphene and graphite surfaces without external magnetic fields being applied. These anomalous LLs have been ascribed primarily to a strain of graphene sheets, leading to in-plane hopping modulation of electrons. Here, we report the observation of the LLs of massive Dirac fermions on atomically flat areas of a nitrogen-doped graphite surface in the absence of external magnetic fields. The corresponding magnetic fields were estimated to be as much as approximately 100 T. The generation of the LLs at the area with negligible strain can be explained by inequivalent hopping of π electrons that takes place at the perimeter of high-potential domains surrounded by positively charged substituted graphitic-nitrogen atoms. PMID:26549618

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

    PubMed

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

    2005-03-29

    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

  3. Effects of hole doping by neutron irradiation of magnetic field induced electronic phase transitions in graphite

    SciTech Connect

    Singleton, John; Yaguchi, Hiroshi

    2008-01-01

    We have investigated effects of hole doping by fast-neutron irradiation on the magnetic-field induced phase transitions in graphite using specimens irradiated with fast neutrons. Resistance measurements have been done in magnetic fields of up to above 50 T and at temperatures down to about 1.5 K. The neutron irradiation creates lattice defects acting as acceptors, affecting the imbalance of the electron and hole densities and the Fermi level. We have found that the reentrant field from the field induced state back to the normal state shifts towards a lower field with hole doping, suggestive of the participation of electron subbands in the magnetic-field induced state.

  4. Influence of the boron precursor and drying method on surface properties and electrochemical behavior of boron-doped carbon gels.

    PubMed

    Zapata-Benabihe, Zulamita; Moreno-Castilla, Carlos; Carrasco-Marín, Francisco

    2014-02-18

    Two series of B-doped carbon gels were prepared by the polymerization of resorcinol and formaldehyde in water using either boric acid or phenyl boronic acid as dopants. Both organic hydrogels were dried by four methods: supercritical, freeze, microwave oven, and vacuum oven drying. The effects of the boron precursor and drying method on the surface characteristics were studied by N2 and CO2 adsorption at -196 and 0 °C, respectively, immersion calorimetry into benzene and water, temperature-programmed desorption coupled with mass spectrometry, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Electrochemical characterization was carried out in a three-electrode cell, using Ag/AgCl as a reference electrode and a Pt wire as a counter electrode. The surface area obtained from immersion calorimetry into benzene was more realistic than that yielded by the Brunauer-Emmett-Teller (BET) equation. The hydrophobicity of the samples decreased linearly with a higher oxygen content. In addition, the oxygen content of the B-doped carbon gels increased linearly with a higher B content, and the interfacial or areal capacitance decreased linearly with a larger surface area. The capacitance was increased by B addition because of the pseudocapacitance effects of the higher oxygen content of the samples. The cryogel and vacuum-dried xerogel obtained from the boric acid series, Bc and Bv, respectively, showed the largest gravimetric and volumetric capacitances, around 140 F/g and 95 F/cm(3), respectively. PMID:24460055

  5. Boron

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Boron is an essential micronutrient element required for plant growth. Boron deficiency is wide-spread in crop plants throughout the world especially in coarse-textured soils in humid areas. Boron toxicity can also occur, especially in arid regions under irrigation. Plants respond directly to the...

  6. Catalytic doping of phosphorus and boron atoms on hydrogenated amorphous silicon films

    NASA Astrophysics Data System (ADS)

    Seto, Junichi; Ohdaira, Keisuke; Matsumura, Hideki

    2016-04-01

    We investigate the low-temperature doping of phosphorus (P) and boron (B) atoms on hydrogenated amorphous silicon (a-Si:H) films by catalytic doping (Cat-doping). The conductivity of a-Si:H films increases as catalyzer temperature (T cat) increases, and the increase in conductivity is accompanied by a significant reduction in activation energy obtained from the Arrhenius plot of the conductivity. Secondary ion mass spectrometry (SIMS) measurement reveals that Cat-doped P and B atoms exist within ˜10-15 nm from the a-Si:H film surface, indicating that the shallow doping of P and B atoms is realized on a-Si:H films similarly to the case of Cat-doping on crystalline Si (c-Si) wafers. We also confirm no additional film deposition during Cat-doping. These results suggest that decomposed species are effectively doped on a-Si:H films similarly to the case of Cat-doping on c-Si.

  7. Effects of Oxidation on Oxidation-Resistant Graphite

    SciTech Connect

    Windes, William; Smith, Rebecca; Carroll, Mark

    2015-05-01

    The Advanced Reactor Technology (ART) Graphite Research and Development Program is investigating doped nuclear graphite grades that exhibit oxidation resistance through the formation of protective oxides on the surface of the graphite material. In the unlikely event of an oxygen ingress accident, graphite components within the VHTR core region are anticipated to oxidize so long as the oxygen continues to enter the hot core region and the core temperatures remain above 400°C. For the most serious air-ingress accident which persists over several hours or days the continued oxidation can result in significant structural damage to the core. Reducing the oxidation rate of the graphite core material during any air-ingress accident would mitigate the structural effects and keep the core intact. Previous air oxidation testing of nuclear-grade graphite doped with varying levels of boron-carbide (B4C) at a nominal 739°C was conducted for a limited number of doped specimens demonstrating a dramatic reduction in oxidation rate for the boronated graphite grade. This report summarizes the conclusions from this small scoping study by determining the effects of oxidation on the mechanical strength resulting from oxidation of boronated and unboronated graphite to a 10% mass loss level. While the B4C additive did reduce mechanical strength loss during oxidation, adding B4C dopants to a level of 3.5% or more reduced the as-fabricated compressive strength nearly 50%. This effectively minimized any benefits realized from the protective film formed on the boronated grades. Future work to infuse different graphite grades with silicon- and boron-doped material as a post-machining conditioning step for nuclear components is discussed as a potential solution for these challenges in this report.

  8. Effects of helium on void swelling in boron doped V 5Fe alloys

    NASA Astrophysics Data System (ADS)

    Iwai, Takeo; Sekimura, Naoto; Garner, F. A.

    1998-10-01

    The effects of helium on void swelling in V-5Fe were investigated with natural boron-doping techniques during FFTF/MOTA (Fast Flux Test Facility/Materials Open Test Assembly) irradiation. Microstructural observation was carried out to understand the swelling behavior obtained from density measurements. The cavity size distribution in V-5Fe- xB ( x=0, 100, and 500 appm) irradiated at temperatures lower than 713 K indicates a suppressant effect of helium on void growth, and an enhancing effect on cavity nucleation. Since the chemical effect of boron addition is competitive with the transmutation effect, the results have been compared with that of the dual ion irradiation experiments to allow separation of the effect of helium from the effect of boron.

  9. Bottom-up fabrication and characterization of boron doped N =7 armchair graphene nanoribbons

    NASA Astrophysics Data System (ADS)

    Nguyen, Giang D.; Omrani, Arash A.; Tsai, Hsin-Zon; Rizzo, Daniel J.; Joshi, Trinity; Bronner, Christopher; Cloke, Ryan R.; Marangoni, Tomas; Cao, Ting; Rodgers, Griffin F.; Choi, Won-Woo; Louie, Steven G.; Fischer, Felix R.; Crommie, Michael F.

    Graphene nanoribbons (GNRs) have recently attracted great interest because of their novel electronic and magnetic properties, as well as the significant potential they have for device applications. Although several top-down techniques exist for fabricating GNRs, only bottom-up synthesis of GNRs from molecular precursors yields nanoribbons with atomic-scale structural control. Here we report the successful bottom-up fabrication boron doped N =7 armchair graphene nanoribbons. Substitutional boron atoms were incorporated into the GNRs' central backbone, thus placing boron's empty p-orbital in conjugation with the extended pi system of the GNR. Topographic and local electronic structure characterization was performed via STM and CO-tip-functionalized nc-AFM, and compared to DFT simulations.

  10. Optoelectronic studies of boron-doped and gamma-irradiated diamond thin films

    NASA Astrophysics Data System (ADS)

    Chapagain, Puskar; Nemashkalo, Anastasiia; Peters, Raul; Farmer, John; Gupta, Sanju; Strzhemechny, Yuri M.

    2011-10-01

    Elucidation of microscopic properties of a synthetic diamond, such as formation and evolution of bulk and surface defects, chemistry of dopants, etc. is necessary for a reliable quality control and reproducibility in applications. Employing surface photovoltage (SPV) and photoluminescence (PL) spectroscopic probes we studied diamond thin films grown on silicon by microwave plasma-assisted chemical vapor deposition with different levels of boron doping in conjunction with gamma irradiation. SPV measurements showed that while the increase of boron concentration leads to a semiconductor-metal transition, subsequent intense gamma irradiation reverts back the quasi-metallic samples to semiconducting state via compensating electrical activity of boron by hydrogen. One of the most pronounced common transitions in the SPV spectra was observed at ˜3.1 eV, also present in most of the PL spectra. We argue that this is a signature of the sp^2-C clusters/layers in the vicinity of grain boundaries.

  11. Effect of boron doping on optical properties of sol-gel based nanostructured zinc oxide films on glass

    SciTech Connect

    Jana, Sunirmal; Vuk, Angela Surca; Mallick, Aparajita; Orel, Boris; Biswas, Prasanta Kumar

    2011-12-15

    Graphical abstract: Room temperature fine structured UV-vis PL emissions (a) as phonon replicas in 1 at.% boron doped film originated from LO phonon evidenced from Near Grazing Incidence Angle (NGIA) IR spectral study (b). Highlights: Black-Right-Pointing-Pointer Sol-gel based boron doped nanostructured ZnO thin films deposited on pure silica glass using crystalline boric acid as boron source. Black-Right-Pointing-Pointer Observed first time, room temperature fine structured PL emissions in 1 at.% doped film as phonon replicas originated from LO phonon (both IR and Raman active). Black-Right-Pointing-Pointer Boron doping controls the LO phonon energy in addition to visible reflection, band gap and grain size. Black-Right-Pointing-Pointer The films possessed mixed crystal phases with hexagonal as major phase. -- Abstract: Boron doped zinc oxide thin films ({approx}80 nm) were deposited onto pure silica glass by sol-gel dip coating technique from the precursor sol/solution of 4.0 wt.% equivalent oxide content. The boron concentration was varied from 0 to 2 at.% w.r.t. Zn using crystalline boric acid. The nanostructured feature of the films was visualized by FESEM images and the largest cluster size of ZnO was found in 1 at.% boron doped film (B1ZO). The presence of mixed crystal phases with hexagonal as major phase was identified from XRD reflections of the films. Particle size, optical band gap, visible specular reflection, room temperature photoluminescence (PL) emissions (3.24-2.28 eV), infra-red (IR) and Raman active longitudinal optical (LO) phonon vibration were found to be dependent on dopant concentration. For the first time, we report the room temperature fine structured PL emissions as phonon replicas originated from the LO phonon (both IR and Raman active) in 1 at.% boron doped zinc oxide film.

  12. Communication: Towards catalytic nitric oxide reduction via oligomerization on boron doped graphene

    NASA Astrophysics Data System (ADS)

    Cantatore, Valentina; Panas, Itai

    2016-04-01

    We use density functional theory to describe a novel way for metal free catalytic reduction of nitric oxide NO utilizing boron doped graphene. The present study is based on the observation that boron doped graphene and O—N=N—O- act as Lewis acid-base pair allowing the graphene surface to act as a catalyst. The process implies electron assisted N=N bond formation prior to N—O dissociation. Two N2 + O2 product channels, one of which favoring N2O formation, are envisaged as outcome of the catalytic process. Besides, we show also that the N2 + O2 formation pathways are contrasted by a side reaction that brings to N3O3- formation and decomposition into N2O + NO2-.

  13. Electrochemical mineralization pathway of quinoline by boron-doped diamond anodes.

    PubMed

    Wang, Chunrong; Ma, Keke; Wu, Tingting; Ye, Min; Tan, Peng; Yan, Kecheng

    2016-04-01

    Boron-doped diamond anodes were selected for quinoline mineralization, and the resulting intermediates, phenylpropyl aldehyde, phenylpropionic acid, and nonanal were identified and followed during quinoline oxidation by gas chromatography-mass spectrometry and high-performance liquid chromatography. The evolutions of formic acid, acetic acid, oxalic acid, NO2(-), NO3(-), and NH4(+) were quantified. A new reaction pathway for quinoline mineralization by boron-doped diamond anodes has been proposed, where the pyridine ring in quinoline is cleaved by a hydroxyl radical giving phenylpropyl aldehyde and NH4(+). Phenylpropyl aldehyde is quickly oxidized into phenylpropionic acid, and the benzene ring is cleaved giving nonanal. This is further oxidized to formic acid, acetic acid, and oxalic acid. Finally, these organic intermediates are mineralized to CO2 and H2O. NH4(+) is also oxidized to NO2(-) and on to NO3(-). The results will help to gain basic reference for clearing intermediates and their toxicity. PMID:26855227

  14. Electrical properties of boron-doped MWNTs synthesized by hot-filament chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ishii, S.; Nagao, M.; Watanabe, T.; Tsuda, S.; Yamaguchi, T.; Takano, Y.

    2009-10-01

    We have synthesized a large amount of boron-doped multiwalled carbon nanotubes (MWNTs) by hot-filament chemical vapor deposition. The synthesis was carried out in a flask using a methanol solution of boric acid as a source material. The scanning electron microscopy, transmission electron microscopy, and micro-Raman spectroscopy were performed to evaluate the structural properties of the obtained MWNTs. In order to evaluate the electrical properties, temperature dependence of resistivity was measured in an individual MWNTs with four metal electrodes. The Raman shifts suggest carrier injection into the boron-doped MWNTs, but the resistivity of the MWNTs was high and increased strongly with decreasing temperature. Defects induced by the plasma may cause this enhanced resistivity.

  15. Clean and metal-doped bundles of boron-carbide nanotubes: A density functional study

    NASA Astrophysics Data System (ADS)

    Ponomarenko, O.; Radny, M. W.; Smith, P. V.

    2007-07-01

    Carbon nanotubes and many types of inorganic nanotubes can be produced in the form of hexagonal arrays or bundles. In this paper, we discuss results of ab initio density functional theory calculations on the stability, and atomic and electronic structure, of bundles of narrow, clean, and Li- and Cu-doped, boron-carbide nanotubes related to LiBC and CuBC layered compounds. We find that covalent bonding arises between neighboring tubes in the bundles which results in the formation of complex structures. We show that a high concentration of dopant Li atoms in the bundles can be achieved by a combination of in-tube and interstitial doping. A high concentration of Li atoms involving only in-tube doping is energetically unfavorable due to repulsive interaction between the Li atoms. By contrast, increased doping with Cu atoms can produce a metallic wirelike structure along the longitudinal axis of each tube within the bundle.

  16. Synthesis of boron, nitrogen co-doped porous carbon from asphaltene for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhou, Ying; Wang, Dao-Long; Wang, Chun-Lei; Jin, Xin-Xin; Qiu, Jie-Shan

    2014-08-01

    Oxidized asphaltene (OA), a thermosetting material with plenty of functional groups, is synthesized from asphaltene (A) using HNO3/H2SO4 as the oxidizing agent. Boron, nitrogen co-doped porous carbon (BNC—OA) is prepared by carbonization of the mixture of boric acid and OA at 1173 K in an argon atmosphere. X-ray photoelectron spectroscopy (XPS) characterization reveals that the BNC—OA has a nitrogen content of 3.26 at.% and a boron content of 1.31 at.%, while its oxidation-free counterpart (BNC—SA) has a nitrogen content of 1.61 at.% and a boron content of 3.02 at.%. The specific surface area and total pore volume of BNC—OA are 1103 m2·g-1 and 0.921 cm3·g-1, respectively. At a current density of 0.1 A·g-1, the specific capacitance of BNC-OA is 335 F·g-1 and the capacitance retention can still reach 83% at 1 A·g-1. The analysis shows that the superior electrochemical performance of the BNC—OA is attributed to the pseudocapacitance behavior of surface heteroatom functional groups and an abundant pore-structure. Boron, nitrogen co-doped porous carbon is a promising electrode material for supercapacitors.

  17. Local impedance imaging of boron-doped polycrystalline diamond thin films

    SciTech Connect

    Zieliński, A.; Ryl, J.; Burczyk, L.; Darowicki, K.

    2014-09-29

    Local impedance imaging (LII) was used to visualise surficial deviations of AC impedances in polycrystalline boron-doped diamond (BDD). The BDD thin film electrodes were deposited onto the highly doped silicon substrates via microwave plasma-enhanced CVD. The studied boron dopant concentrations, controlled by the [B]/[C] ratio in plasma, ranged from 1 × 10{sup 16} to 2 × 10{sup 21} atoms cm{sup −3}. The BDD films displayed microcrystalline structure, while the average size of crystallites decreased from 1 to 0.7 μm with increasing [B]/[C] ratios. The application of LII enabled a direct and high-resolution investigation of local distribution of impedance characteristics within the individual grains of BDD. Such an approach resulted in greater understanding of the microstructural control of properties at the grain level. We propose that the obtained surficial variation of impedance is correlated to the areas of high conductance which have been observed at the grain boundaries by using LII. We also postulate that the origin of high conductivity is due to either preferential boron accumulation, the presence of defects, or sp{sup 2} regions in the intragrain regions. The impedance modulus recorded by LII was in full agreement with the bulk impedance measurements. Both variables showed a decreasing trend with increasing [B]/[C] ratios, which is consistent with higher boron incorporation into BDD film.

  18. Boron doped ZnO embedded into reduced graphene oxide for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Alver, Ü.; Tanrıverdi, A.

    2016-08-01

    In this work, reduced graphene oxide/boron doped zinc oxide (RGO/ZnO:B) composites were fabricated by a hydrothermal process and their electrochemical properties were investigated as a function of dopant concentration. First, boron doped ZnO (ZnO:B) particles was fabricated with different boron concentrations (5, 10, 15 and 20 wt%) and then ZnO:B particles were embedded into RGO sheets. The physical properties of sensitized composites were characterized by XRD and SEM. Characterization indicated that the ZnO:B particles with plate-like structure in the composite were dispersed on graphene sheets. The electrochemical properties of the RGO/ZnO:B composite were investigated through cyclic voltammetry, galvanostatic charge/discharge measurements in a 6 M KOH electrolyte. Electrochemical measurements show that the specific capacitance values of RGO/ZnO:B electrodes increase with increasing boron concentration. RGO/ZnO:B composite electrodes (20 wt% B) display the specific capacitance as high as 230.50 F/g at 5 mV/s, which is almost five times higher than that of RGO/ZnO (52.71 F/g).

  19. Large gauge factor of hot wire chemical vapour deposition in-situ boron doped polycrystalline silicon

    NASA Astrophysics Data System (ADS)

    Grech, David; Tarazona, Antulio; De Leon, Maria Theresa; Kiang, Kian S.; Zekonyte, Jurgita; Wood, Robert J. K.; Chong, Harold M. H.

    2016-04-01

    Polysilicon piezoresistors with a large longitudinal gauge factor (GF) of 44 have been achieved using in-situ boron doped hot-wire chemical vapour deposition (HWCVD). This GF is a consequence of a high quality p-type doped polysilicon with a crystal volume of 97% and an average grain size of 150 nm, estimated using Raman spectroscopy and atomic force microscopy (AFM) respectively. The measured minimum Hooge factor associated to the 1/f noise of the polysilicon piezoresistors is 1.4 × 10‑3. These results indicate that HWCVD polysilicon is a suitable piezoresistive material for micro-electro-mechanical systems (MEMS) applications.

  20. Hydrogenation effects on carrier transport in boron-doped ultrananocrystalline diamond/amorphous carbon films prepared by coaxial arc plasma deposition

    SciTech Connect

    Katamune, Yūki Takeichi, Satoshi; Ohmagari, Shinya; Yoshitake, Tsuyoshi

    2015-11-15

    Boron-doped ultrananocrystalline diamond/hydrogenated amorphous carbon composite (UNCD/a-C:H) films were deposited by coaxial arc plasma deposition with a boron-blended graphite target at a base pressure of <10{sup −3} Pa and at hydrogen pressures of ≤53.3 Pa. The hydrogenation effects on the electrical properties of the films were investigated in terms of chemical bonding. Hydrogen-scattering spectrometry showed that the maximum hydrogen content was 35 at. % for the film produced at 53.3-Pa hydrogen pressure. The Fourier-transform infrared spectra showed strong absorptions by sp{sup 3} C–H bonds, which were specific to the UNCD/a-C:H, and can be attributed to hydrogen atoms terminating the dangling bonds at ultrananocrystalline diamond grain boundaries. Temperature-dependence of the electrical conductivity showed that the films changed from semimetallic to semiconducting with increasing hydrogen pressure, i.e., with enhanced hydrogenation, probably due to hydrogenation suppressing the formation of graphitic bonds, which are a source of carriers. Carrier transport in semiconducting hydrogenated films can be explained by a variable-range hopping model. The rectifying action of heterojunctions comprising the hydrogenated films and n-type Si substrates implies carrier transport in tunneling.

  1. Critical role of intercalated water for electrocatalytically active nitrogen-doped graphitic systems

    DOE PAGESBeta

    Martinez, Ulises; Dumont, Joseph H.; Holby, Edward F.; Artyushkova, Kateryna; Purdy, Geraldine M.; Singh, Akhilesh; Mack, Nathan H.; Atanassov, Plamen; Cullen, David A.; More, Karren L.; et al

    2016-03-18

    Graphitic materials are very essential in energy conversion and storage because of their excellent chemical and electrical properties. The strategy for obtaining functional graphitic materials involves graphite oxidation and subsequent dissolution in aqueous media, forming graphene-oxide nanosheets (GNs). Restacked GNs contain substantial intercalated water that can react with heteroatom dopants or the graphene lattice during reduction. We demonstrate that removal of intercalated water using simple solvent treatments causes significant structural reorganization, substantially affecting the oxygen reduction reaction (ORR) activity and stability of nitrogen-doped graphitic systems. Amid contrasting reports describing the ORR activity of GN-based catalysts in alkaline electrolytes, we demonstratemore » superior activity in an acidic electrolyte with an onset potential of ~0.9 V, a half-wave potential (E½) of 0.71 V, and a selectivity for four-electron reduction of >95%. Finally and further, durability testing showed E½ retention >95% in N2- and O2-saturated solutions after 2000 cycles, demonstrating the highest ORR activity and stability reported to date for GN-based electrocatalysts in acidic media.« less

  2. Critical role of intercalated water for electrocatalytically active nitrogen-doped graphitic systems.

    PubMed

    Martinez, Ulises; Dumont, Joseph H; Holby, Edward F; Artyushkova, Kateryna; Purdy, Geraldine M; Singh, Akhilesh; Mack, Nathan H; Atanassov, Plamen; Cullen, David A; More, Karren L; Chhowalla, Manish; Zelenay, Piotr; Dattelbaum, Andrew M; Mohite, Aditya D; Gupta, Gautam

    2016-03-01

    Graphitic materials are essential in energy conversion and storage because of their excellent chemical and electrical properties. The strategy for obtaining functional graphitic materials involves graphite oxidation and subsequent dissolution in aqueous media, forming graphene-oxide nanosheets (GNs). Restacked GNs contain substantial intercalated water that can react with heteroatom dopants or the graphene lattice during reduction. We demonstrate that removal of intercalated water using simple solvent treatments causes significant structural reorganization, substantially affecting the oxygen reduction reaction (ORR) activity and stability of nitrogen-doped graphitic systems. Amid contrasting reports describing the ORR activity of GN-based catalysts in alkaline electrolytes, we demonstrate superior activity in an acidic electrolyte with an onset potential of ~0.9 V, a half-wave potential (E ½) of 0.71 V, and a selectivity for four-electron reduction of >95%. Further, durability testing showed E ½ retention >95% in N2- and O2-saturated solutions after 2000 cycles, demonstrating the highest ORR activity and stability reported to date for GN-based electrocatalysts in acidic media. PMID:27034981

  3. Critical role of intercalated water for electrocatalytically active nitrogen-doped graphitic systems

    PubMed Central

    Martinez, Ulises; Dumont, Joseph H.; Holby, Edward F.; Artyushkova, Kateryna; Purdy, Geraldine M.; Singh, Akhilesh; Mack, Nathan H.; Atanassov, Plamen; Cullen, David A.; More, Karren L.; Chhowalla, Manish; Zelenay, Piotr; Dattelbaum, Andrew M.; Mohite, Aditya D.; Gupta, Gautam

    2016-01-01

    Graphitic materials are essential in energy conversion and storage because of their excellent chemical and electrical properties. The strategy for obtaining functional graphitic materials involves graphite oxidation and subsequent dissolution in aqueous media, forming graphene-oxide nanosheets (GNs). Restacked GNs contain substantial intercalated water that can react with heteroatom dopants or the graphene lattice during reduction. We demonstrate that removal of intercalated water using simple solvent treatments causes significant structural reorganization, substantially affecting the oxygen reduction reaction (ORR) activity and stability of nitrogen-doped graphitic systems. Amid contrasting reports describing the ORR activity of GN-based catalysts in alkaline electrolytes, we demonstrate superior activity in an acidic electrolyte with an onset potential of ~0.9 V, a half-wave potential (E½) of 0.71 V, and a selectivity for four-electron reduction of >95%. Further, durability testing showed E½ retention >95% in N2- and O2-saturated solutions after 2000 cycles, demonstrating the highest ORR activity and stability reported to date for GN-based electrocatalysts in acidic media. PMID:27034981

  4. Boron-doped cadmium oxide composite structures and their electrochemical measurements

    SciTech Connect

    Lokhande, B.J.; Ambare, R.C.; Mane, R.S.; Bharadwaj, S.R.

    2013-08-01

    Graphical abstract: Conducting nano-fibrous 3% boron doped cadmium oxide thin films were prepared by SILAR and its super capacitive properties were studied. - Highlights: • Samples are of nanofibrous nature. • All samples shows pseudocapacitive behavior. • 3% B doped CdO shows good specific capacitance. • 3% B doped CdO shows maximum 74.93% efficiency at 14 mA/cm{sup 2}. • 3% B doped CdO shows 0.8 Ω internal resistance. - Abstract: Boron-doped and undoped cadmium oxide composite nanostructures in thin film form were prepared onto stainless steel substrates by a successive ionic layer adsorption and reaction method using aqueous solutions of cadmium nitrate, boric acid and 1% H{sub 2}O{sub 2}. As-deposited films were annealed at 623 K for 1 h. The X-ray diffraction study shows crystalline behavior for both doped and undoped films with a porous topography and nano-wires type architecture, as observed in SEM image. Wettability test confirms the hydrophilic surface with 58° contact angle value. Estimated band gap energy is around 1.9 eV. Electrochemical behavior of the deposited films is attempted in 1 M KOH electrolyte using cyclic voltammetry (CV), electrochemical impedance spectroscopy and galvanostatic charge–discharge tests. Maximum values of the specific capacitance, specific energy and specific power obtained for 3% B doped CdO film at 2 mV/s scan rate are 20.05 F/g, 1.22 Wh/kg and 3.25 kW/kg, respectively.

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

    PubMed

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

    2016-08-15

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

  6. Analytical and experimental studies of graphite-epoxy and boron-epoxy angle ply laminates in shear

    NASA Technical Reports Server (NTRS)

    Weller, T.

    1977-01-01

    The results of a comparison study between a test program on the inelastic response under inplane shear over a wide range of graphite-epoxy and boron-epoxy angle-ply laminates are reported. This investigation was aimed at evaluating the applicability and adequacy of these analyses to predict satisfactorily the responses of angle-ply laminates. It was observed that these analytical tools are inadequate for this purpose as they fail to predict with sufficient confidence the shape of response and in particular the strength values associated with a given laminate configuration. Consequently, they do not provide the sought-after information about failure mechanisms which trigger failure of a particular designed laminate.

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

    PubMed Central

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

    2013-01-01

    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, α-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

  8. Lewis Basicity of Nitrogen-Doped Graphite Observed by CO2 Chemisorption.

    PubMed

    Kiuchi, Hisao; Shibuya, Riku; Kondo, Takahiro; Nakamura, Junji; Niwa, Hideharu; Miyawaki, Jun; Kawai, Maki; Oshima, Masaharu; Harada, Yoshihisa

    2016-12-01

    The characteristics of CO2 adsorption sites on a nitrogen-doped graphite model system (N-HOPG) were investigated by X-ray photoelectron and absorption spectroscopy and infrared reflection absorption spectroscopy. Adsorbed CO2 was observed lying flat on N-HOPG, stabilized by a charge transfer from the substrate. This demonstrated that Lewis base sites were formed by the incorporation of nitrogen via low-energy nitrogen-ion sputtering. The possible roles of twofold coordinated pyridinic N and threefold coordinated valley N (graphitic N) sites in Lewis base site formation on N-HOPG are discussed. The presence of these nitrogen species focused on the appropriate interaction strength of CO2 indicates the potential to fine-tune the Lewis basicity of carbon-based catalysts. PMID:26951127

  9. Lewis Basicity of Nitrogen-Doped Graphite Observed by CO2 Chemisorption

    NASA Astrophysics Data System (ADS)

    Kiuchi, Hisao; Shibuya, Riku; Kondo, Takahiro; Nakamura, Junji; Niwa, Hideharu; Miyawaki, Jun; Kawai, Maki; Oshima, Masaharu; Harada, Yoshihisa

    2016-03-01

    The characteristics of CO2 adsorption sites on a nitrogen-doped graphite model system (N-HOPG) were investigated by X-ray photoelectron and absorption spectroscopy and infrared reflection absorption spectroscopy. Adsorbed CO2 was observed lying flat on N-HOPG, stabilized by a charge transfer from the substrate. This demonstrated that Lewis base sites were formed by the incorporation of nitrogen via low-energy nitrogen-ion sputtering. The possible roles of twofold coordinated pyridinic N and threefold coordinated valley N (graphitic N) sites in Lewis base site formation on N-HOPG are discussed. The presence of these nitrogen species focused on the appropriate interaction strength of CO2 indicates the potential to fine-tune the Lewis basicity of carbon-based catalysts.

  10. Effect of diborane on the microstructure of boron-doped silicon nanowires

    NASA Astrophysics Data System (ADS)

    Pan, Ling; Lew, Kok-Keong; Redwing, Joan M.; Dickey, Elizabeth C.

    2005-04-01

    Boron-doped silicon (Si) nanowires, with nominal diameters of 80 nm, were grown via the vapor-liquid-solid (VLS) mechanism using gold (Au) as a catalyst and silane (SiH 4) and diborane (B 2H 6) as precursors. The microstructure of the nanowires was studied by scanning electron microscopy, transmission electron microscopy and electron energy-loss spectroscopy. At lower B 2H 6 partial pressure and thus lower doping levels (⩽1×10 18 cm -3), most of the boron-doped Si nanowires exhibited high crystallinity. At higher B 2H 6 partial pressure (˜2×10 19 cm -3 doping level), the majority of the wires exhibited a core-shell structure with an amorphous Si shell (20-30 nm thick) surrounding a crystalline Si core. Au nanoparticles on the outer surface of the nanowires were also observed in structures grown with high B/Si gas ratios. The structural changes are believed to result from an increase in the rate of Si thin-film deposition on the outer surface of the nanowire at high B 2H 6 partial pressure, which produces the amorphous coating and also causes an instability at the liquid/solid interface resulting in a loss of Au during nanowire growth.

  11. Radiation tolerance of boron doped dendritic web silicon solar cells

    NASA Technical Reports Server (NTRS)

    Rohatgi, A.

    1980-01-01

    The potential of dendritic web silicon for giving radiation hard solar cells is compared with the float zone silicon material. Solar cells with n(+)-p-P(+) structure and approximately 15% (AMl) efficiency were subjected to 1 MeV electron irradiation. Radiation tolerance of web cell efficiency was found to be at least as good as that of the float zone silicon cell. A study of the annealing behavior of radiation-induced defects via deep level transient spectroscopy revealed that E sub v + 0.31 eV defect, attributed to boron-oxygen-vacancy complex, is responsible for the reverse annealing of the irradiated cells in the temperature range of 150 to 350 C.

  12. Thermoelectric properties of heavily boron- and phosphorus-doped silicon

    NASA Astrophysics Data System (ADS)

    Ohishi, Yuji; Xie, Jun; Miyazaki, Yoshinobu; Aikebaier, Yusufu; Muta, Hiroaki; Kurosaki, Ken; Yamanaka, Shinsuke; Uchida, Noriyuki; Tada, Tetsuya

    2015-07-01

    In recent years, nanostructured thermoelectric materials have attracted much attention. However, despite this increasing attention, available information on the thermoelectric properties of single-crystal Si is quite limited, especially for high doping concentrations at high temperatures. In this study, the thermoelectric properties of heavily doped (1018-1020 cm-3) n- and p-type single-crystal Si were studied from room temperature to above 1000 K. The figures of merit, ZT, were calculated from the measured data of electrical conductivity, Seebeck coefficient, and thermal conductivity. The maximum ZT values were 0.015 for n-type and 0.008 for p-type Si at room temperature. To better understand the carrier and phonon transport and to predict the thermoelectric properties of Si, we have developed a simple theoretical model based on the Boltzmann transport equation with the relaxation-time approximation.

  13. Enhanced thermal conductivity of CVD SiC via beryllium and boron dopings

    SciTech Connect

    Kowbel, W.; Gao, F.; Withers, J.C.

    1995-10-01

    SiC-SiC composites exhibit excellent mechanical and corrosion properties, which are desired for a variety of advanced applications including fusion reactors, heat exchangers and advanced turbine engines. However, SiC-SiC composites fabricated by the CVI methods have unacceptably low through-the-thickness thermal conductivity, which limits their use in these applications. CVD SiC co-deposition with either beryllium or boron compounds significantly enhanced the thermal conductivity of CVD SiC at temperatures up to 1,000 C. Results pertinent to the doping processes and the measured thermal conductivity of doped CVD SiC are reported. Mechanisms for the enhanced thermal conductivity of the CVD SiC are discussed based on the microstructural characteristics of the doped specimens.

  14. Boron laser doping using spin-on dopant for textured crystalline silicon solar cell

    NASA Astrophysics Data System (ADS)

    Nishimura, Hideki; Manabe, Mitsuaki; Sakagawa, Hideki; Fuyuki, Takashi

    2015-06-01

    A novel precursor layer, polyboron film (PBF), was applied in the laser doping (LD) process. Localized LD using PBF was applied to a high-efficiency solar cell structure as a selective emitter (SE). Interface adhesion was improved by using an organic-polymer-based doping precursor, PBF. A strongly adhered interface contributed to the preservation of textured formations after disruption by LD, and to the homogeneous introduction of impurities. Surface geometries were retained almost completely even after LD. Sheet resistances were decreased by additional boron doping by LD. The photovoltaic characteristics were improved by SE formation using PBF with an optimum average laser power. Consequently, the SE formed by LD showed an increase in fill factor (FF), which contributed to the improvement in solar cell efficiency.

  15. Study of different thermal processes on boron-doped PERL cells

    NASA Astrophysics Data System (ADS)

    Li, Wenjia; Wang, Zhenjiao; Han, Peiyu; Lu, Hongyan; Yang, Jian; Guo, Ying; Shi, Zhengrong; Li, Guohua

    2014-08-01

    In this paper, three kinds of thermal processes for boron-doped PERL cells were investigated. These are the forming gas annealing (FGA), the rapid thermal (RTP) and the low temperature annealing processes. FGA was introduced after laser ablation and doping in order to increase minority carrier lifetime by hydrogenating the trapping centers. Subsequent evaluation revealed considerable enhancement of minority carrier lifetime (from 150 μs to 240 μs) and the implied Voc (from 660 mV to 675 mV). After aluminum sputtering, three actual peak temperatures (370 °C, 600 °C and 810 °C) of RTP (as it occurs in the compressed air environment used in our experiment) were utilized to form a contact between the metal and the semi-conductor. It is concluded that only low temperature (lower than 600 °C) firing could create boron back surface field and high quality rear reflector. Lastly, a method of improving the performance of finished PERL cells which did not experience high temperature (over 800 °C) firing was investigated. Finished cells undergone low temperature annealing in N2 atmosphere at 150 °C for 15 min produced 0.44% absolute increase in PERL cells. The enhancement of low temperature annealing originally comes from the activation of passivated boron which is deactivated during FGA.

  16. Large-Scale Sublattice Asymmetry in Pure and Boron-Doped Graphene.

    PubMed

    Usachov, Dmitry Yu; Fedorov, Alexander V; Vilkov, Oleg Yu; Petukhov, Anatoly E; Rybkin, Artem G; Ernst, Arthur; Otrokov, Mikhail M; Chulkov, Evgueni V; Ogorodnikov, Ilya I; Kuznetsov, Mikhail V; Yashina, Lada V; Kataev, Elmar Yu; Erofeevskaya, Anna V; Voroshnin, Vladimir Yu; Adamchuk, Vera K; Laubschat, Clemens; Vyalikh, Denis V

    2016-07-13

    The implementation of future graphene-based electronics is essentially restricted by the absence of a band gap in the electronic structure of graphene. Options of how to create a band gap in a reproducible and processing compatible manner are very limited at the moment. A promising approach for the graphene band gap engineering is to introduce a large-scale sublattice asymmetry. Using photoelectron diffraction and spectroscopy we have demonstrated a selective incorporation of boron impurities into only one of the two graphene sublattices. We have shown that in the well-oriented graphene on the Co(0001) surface the carbon atoms occupy two nonequivalent positions with respect to the Co lattice, namely top and hollow sites. Boron impurities embedded into the graphene lattice preferably occupy the hollow sites due to a site-specific interaction with the Co pattern. Our theoretical calculations predict that such boron-doped graphene possesses a band gap that can be precisely controlled by the dopant concentration. B-graphene with doping asymmetry is, thus, a novel material, which is worth considering as a good candidate for electronic applications. PMID:27248659

  17. Tuning dissociation using isoelectronically doped graphene and hexagonal boron nitride: Water and other small molecules

    NASA Astrophysics Data System (ADS)

    Al-Hamdani, Yasmine S.; Alfè, Dario; von Lilienfeld, O. Anatole; Michaelides, Angelos

    2016-04-01

    Novel uses for 2-dimensional materials like graphene and hexagonal boron nitride (h-BN) are being frequently discovered especially for membrane and catalysis applications. Still however, a great deal remains to be understood about the interaction of environmentally and industrially relevant molecules such as water with these materials. Taking inspiration from advances in hybridising graphene and h-BN, we explore using density functional theory, the dissociation of water, hydrogen, methane, and methanol on graphene, h-BN, and their isoelectronic doped counterparts: BN doped graphene and C doped h-BN. We find that doped surfaces are considerably more reactive than their pristine counterparts and by comparing the reactivity of several small molecules, we develop a general framework for dissociative adsorption. From this a particularly attractive consequence of isoelectronic doping emerges: substrates can be doped to enhance their reactivity specifically towards either polar or non-polar adsorbates. As such, these substrates are potentially viable candidates for selective catalysts and membranes, with the implication that a range of tuneable materials can be designed.

  18. Carbon doping induced peculiar transport properties of boron nitride nanoribbons p-n junctions

    SciTech Connect

    Liu, N.; Gao, G. Y.; Zhu, S. C.; Ni, Y.; Wang, S. L.; Yao, K. L.; Liu, J. B.

    2014-07-14

    By applying nonequilibrium Green's function combined with density functional theory, we investigate the electronic transport properties of carbon-doped p-n nanojunction based on hexagonal boron nitride armchair nanoribbons. The calculated I-V curves show that both the center and edge doping systems present obvious negative differential resistance (NDR) behavior and excellent rectifying effect. At low positive bias, the edge doping systems possess better NDR performance with larger peak-to-valley ratio (∼10{sup 5}), while at negative bias, the obtained peak-to-valley ratio for both of the edge and center doping systems can reach the order of 10{sup 7}. Meanwhile, center doping systems present better rectifying performance than the edge doping ones, and giant rectification ratio up to 10{sup 6} can be obtained in a wide bias range. These outstanding transport properties are explained by the evolution of the transmission spectra and band structures with applied bias, together with molecular projected self-consistent Hamiltonian eigenvalues and eigenstates.

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

    NASA Astrophysics Data System (ADS)

    Zhao, Jiannan; Ma, Lin; Wang, Haoying; Zhao, Yanfeng; Zhang, Jian; Hu, Shaozheng

    2015-03-01

    Novel band gap-tunable K-Na co-doped graphitic carbon nitride was prepared by molten salt method using melamine, KCl, and NaCl as precursor. X-ray diffraction (XRD), N2 adsorption, Scanning electron microscope (SEM), UV-vis spectroscopy, Photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared catalysts. The CB and VB potentials of graphitic carbon nitride could be tuned from -1.09 and +1.55 eV to -0.29 and +2.25 eV by controlling the weight ratio of eutectic salts to melamine. Besides, ions doping inhibited the crystal growth of graphitic carbon nitride, enhanced the surface area, and increased the separation rate of photogenerated electrons and holes. The visible-light-driven Rhodamine B (RhB) photodegradation and mineralization performances were significantly improved after K-Na co-doping.

  20. Synthesis of boron and nitrogen doped graphene supporting PtRu nanoparticles as catalysts for methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Lu, Jiming; Zhou, Yingke; Tian, Xiaohui; Xu, Xiao; Zhu, Hongxi; Zhang, Shaowei; Yuan, Tao

    2014-10-01

    In this study, we demonstrate a single-step heat treatment approach to synthesize boron and nitrogen doped graphene supporting PtRu electrocatalysts for methanol electro-oxidation reaction. The reduction of graphene oxide, boron or nitrogen doping of graphene and loading of PtRu nanoparticles happened simultaneously during the reaction process. The morphologies and microstructures of the as-prepared catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electrocatalytic methanol oxidation activity and durability of the obtained catalysts were evaluated by the cyclic voltammetry and chronoamperometric techniques. The results reveal that the boron and nitrogen doped graphene supporting PtRu electrocatalysts can be successfully prepared by the single step heat treatment technique, and the introduction of boron or nitrogen containing function groups into the reduced graphene sheets could modulate the particle size and dispersion of the supporting PtRu nanoparticles and improve the electrocatalytic performance of methanol oxidation reaction. The optimal annealing temperature is 800 °C, the preferable heat treatment time is 60 min for the nitrogen-doped catalysts and 90 min for the boron-doped catalysts, and the catalysts prepared under such conditions present superior catalytic activities for methanol oxidation than those prepared under other heat treatment conditions.

  1. Photodegradation of aniline by goethite doped with boron under ultraviolet and visible light irradiation

    SciTech Connect

    Liu, Guanglong; Liao, Shuijiao; Zhu, Duanwei; Liu, Linghua; Cheng, Dongsheng; Zhou, Huaidong

    2011-08-15

    Highlights: {yields} Goethite modified by boron was prepared by sol-gel method in presence of boron acid at the low temperature. {yields} B-goethite has slight red shift in the band gap transition beside their stronger light absorption compared with pristine goethite. {yields} The results showed that semiconductor photocatalytic reaction mechanism should exist in the process of aniline degradation with goethite and B-goethite as photocatalyst. -- Abstract: In the present study, goethite and goethite doped with boron (B-goethite) were employed to detect the presence or absence of semiconductor photocatalytic reaction mechanism in the reaction systems. B-goethite was prepared by sol-gel method in presence of boron acid in order to improve its photocatalystic efficiency under the ultraviolet and visible light irradiation. The optical properties of goethite and B-goethite were characterized by ultraviolet and visible absorption spectra and the result indicated that B-goethite has slight red shift in the band gap transition beside their stronger light absorption compared with pristine goethite. Degradation of aniline was investigated in presence of goethite and B-goethite in aqueous solution. It was found that the B-goethite photocatalyst exhibited enhanced ultraviolet and visible light photocatalytic activity in degradation of aniline compared with the pristine goethite. The photocatalytic degradation mechanism of B-goethite was discussed.

  2. Molecular chemisorption on passivated and defective boron doped silicon surfaces: a "forced" dative bond.

    PubMed

    Boukari, Khaoula; Duverger, Eric; Sonnet, Philippe

    2014-12-01

    We investigate the adsorption mechanism of a single trans 4-pyridylazobenzene molecule (denoted by PAB) on a doped boron Si(111)√3×√3R30° surface (denoted by SiB) with or without boron-defects, by means of density functional theory calculations. The semiempirical approach proposed by Grimme allows us to take the dispersion correction into account. The role of the van der Waals correction in the adsorption geometries and energies is presented. In particular, two adsorption configurations are electronically studied. In the first one, the molecule is parallel to the surface and interacts with the SiB surface via the -N=N- bond. In the presence of a boron-defect, a Si-N chemical bond between the molecule and the surface is then formed, while electrostatic or/and van der Waals interactions are observed in the defectless surface. In the second adsorption configuration, the molecule presents different orientations with respect to the surface and interacts via the nitrogen atom of the pyridyl part of the PAB molecule. If the molecule is perpendicular to the perfect SiB surface, the lone-pair electrons associated with the heterocyclic nitrogen atom fill the empty dangling bond of a silicon adatom via a dative bond. Finally, in the presence of one boron-defect, the possibility of a "forced" dative bond, corresponding to a chemical bond formation between the PAB molecule and the silicon electron occupied dangling bond, is emphasized. PMID:25318974

  3. Theoretical study on Si-doped hexagonal boron nitride (h-BN) sheet: Electronic, magnetic properties, and reactivity

    NASA Astrophysics Data System (ADS)

    Liu, Yue-jie; Gao, Bo; Xu, Duo; Wang, Hong-mei; Zhao, Jing-xiang

    2014-08-01

    The properties and reactivity of Si-doped hexagonal boron nitride (h-BN) sheets were studied using density functional theory (DFT) methods. We find that Si impurity is more likely to substitute the boron site (SiB) due to the low formation energy. Si-doping severely deforms h-BN sheet, resulting in the local curvature changes of h-BN sheet. Moreover, Si-doping introduces two spin localized states within the band gap of h-BN sheet, thus rendering the two doped systems exhibit acceptor properties. The band gap of h-BN sheet is reduced from ˜4.70 eV to 1.24 (for SiB) and 0.84 eV (for SiN), respectively. In addition, Si-doped one exhibits higher activity than pristine one, endowing them wider application potential.

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

    NASA Astrophysics Data System (ADS)

    Böyükata, Mustafa; Güvenç, Ziya B.

    2009-11-01

    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.

  5. Modeling and simulation of boron-doped nanocrystalline silicon carbide thin film by a field theory.

    PubMed

    Xiong, Liming; Chen, Youping; Lee, James D

    2009-02-01

    This paper presents the application of a multiscale field theory in modeling and simulation of boron-doped nanocrystalline silicon carbide (B-SiC). The multiscale field theory was briefly introduced. Based on the field theory, numerical simulations show that intergranular glassy amorphous films (IGFs) and nano-sized pores exist in triple junctions of the grains for nanocrystalline B-SiC. Residual tensile stress in the SiC grains and compressive stress on the grain boundaries (GBs) were observed. Under tensile loading, it has been found that mechanical response of 5 wt% boron-SiC exhibits five characteristic regimes. Deformation mechanism at atomic scale has been revealed. Tensile strength and Young's modulus of nanocrystalline SiC were accurately reproduced. PMID:19441448

  6. Boron, graphite, glass, metal and aramid fiber reinforced plastics. January, 1973-May, 1981 (Citations from the Rubber and Plastics Research Association Data Base). Report for January 1973-May 1981

    SciTech Connect

    Not Available

    1981-05-01

    The citations cover information about advanced reinforced composites such as boron, graphite, glass, metal, and aramid. Topics include applications, fabrication processes, proerties, nondestructive testing, and economics of composite materials. (Contains 90 citations fully indexed and including a title list.)

  7. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively

    PubMed Central

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-01-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50–15000 μmoL L−1 (cubic SiC NWs) and 5–8000 μmoL L−1 (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L−1 respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility. PMID:27109361

  8. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively.

    PubMed

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-01-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50-15000 μmoL L(-1) (cubic SiC NWs) and 5-8000 μmoL L(-1) (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L(-1) respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility. PMID:27109361

  9. Magnetic and resistance measurements on boron-doped and undoped Ni(3)Al thin films*

    NASA Astrophysics Data System (ADS)

    Henry, L. L.; Patterson, Edward C.

    2000-03-01

    We report preliminary results of magnetization and I-V measurements of the effects of boron doping on the magnetic and electron transport properties of Ni3Al thin films. Magnetization and resistance measurements in magnetic fields up to 5 T were performed on 500 Ånominal) thick films that were fabricated by ion beam sputtering of compound targets. Both a doped ( ~200 ppm B) and undoped film were investigated. For the boron-doped film, the magnetization is enhanced with a broad transition that occurs in several stages over the temperature range from 27 K to 56 K. Further, as the temperature is increased through the transition range dM/dT fluctuates between negative and positive values, and the magnetization changes from positive to negative near T = 52 K. Results of I-V measurements performed on the samples with the current in the plane of the film, and an applied magnetic field parallel to the plane of the film, are consistent with these results. *Work supported by the LEQSF and the Dept. of Physics, Southern U. and A&M College, Baton Rouge campus.

  10. Bare and boron-doped cubic silicon carbide nanowires for electrochemical detection of nitrite sensitively

    NASA Astrophysics Data System (ADS)

    Yang, Tao; Zhang, Liqin; Hou, Xinmei; Chen, Junhong; Chou, Kuo-Chih

    2016-04-01

    Fabrication of eletrochemical sensors based on wide bandgap compound semiconductors has attracted increasing interest in recent years. Here we report for the first time electrochemical nitrite sensors based on cubic silicon carbide (SiC) nanowires (NWs) with smooth surface and boron-doped cubic SiC NWs with fin-like structure. Multiple techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS) were used to characterize SiC and boron-doped SiC NWs. As for the electrochemical behavior of both SiC NWs electrode, the cyclic voltammetric results show that both SiC electrodes exhibit wide potential window and excellent electrocatalytic activity toward nitrite oxidation. Differential pulse voltammetry (DPV) determination reveals that there exists a good linear relationship between the oxidation peak current and the concentration in the range of 50–15000 μmoL L‑1 (cubic SiC NWs) and 5–8000 μmoL L‑1 (B-doped cubic SiC NWs) with the detection limitation of 5 and 0.5 μmoL L‑1 respectively. Compared with previously reported results, both as-prepared nitrite sensors exhibit wider linear response range with comparable high sensitivity, high stability and reproducibility.

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

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

    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.

  12. Unraveling the formation mechanism of graphitic nitrogen-doping in thermally treated graphene with ammonia

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Fei; Lian, Ke-Yan; Liu, Lingling; Wu, Yingchao; Qiu, Qi; Jiang, Jun; Deng, Mingsen; Luo, Yi

    2016-03-01

    Nitrogen-doped graphene (N-graphene) has attractive properties that has been widely studied over the years. However, its possible formation process still remains unclear. Here, we propose a highly feasible formation mechanism of the graphitic-N doing in thermally treated graphene with ammonia by performing ab initio molecular dynamic simulations at experimental conditions. Results show that among the commonly native point defects in graphene, only the single vacancy 5–9 and divacancy 555–777 have the desirable electronic structures to trap N-containing groups and to mediate the subsequent dehydrogenation processes. The local structure of the defective graphene in combining with the thermodynamic and kinetic effect plays a crucial role in dominating the complex atomic rearrangement to form graphitic-N which heals the corresponding defect perfectly. The importance of the symmetry, the localized force field, the interaction of multiple trapped N-containing groups, as well as the catalytic effect of the temporarily formed bridge-N are emphasized, and the predicted doping configuration agrees well with the experimental observation. Hence, the revealed mechanism will be helpful for realizing the targeted synthesis of N-graphene with reduced defects and desired properties.

  13. Unraveling the formation mechanism of graphitic nitrogen-doping in thermally treated graphene with ammonia

    PubMed Central

    Li, Xiao-Fei; Lian, Ke-Yan; Liu, Lingling; Wu, Yingchao; Qiu, Qi; Jiang, Jun; Deng, Mingsen; Luo, Yi

    2016-01-01

    Nitrogen-doped graphene (N-graphene) has attractive properties that has been widely studied over the years. However, its possible formation process still remains unclear. Here, we propose a highly feasible formation mechanism of the graphitic-N doing in thermally treated graphene with ammonia by performing ab initio molecular dynamic simulations at experimental conditions. Results show that among the commonly native point defects in graphene, only the single vacancy 5–9 and divacancy 555–777 have the desirable electronic structures to trap N-containing groups and to mediate the subsequent dehydrogenation processes. The local structure of the defective graphene in combining with the thermodynamic and kinetic effect plays a crucial role in dominating the complex atomic rearrangement to form graphitic-N which heals the corresponding defect perfectly. The importance of the symmetry, the localized force field, the interaction of multiple trapped N-containing groups, as well as the catalytic effect of the temporarily formed bridge-N are emphasized, and the predicted doping configuration agrees well with the experimental observation. Hence, the revealed mechanism will be helpful for realizing the targeted synthesis of N-graphene with reduced defects and desired properties. PMID:27002190

  14. Structural stability of nitrogen-doped ultrathin single-walled boron nanotubes: an ab initio study

    NASA Astrophysics Data System (ADS)

    Jain, Sandeep Kumar; Srivastava, Pankaj

    2012-09-01

    Ab initio calculations have been performed for determining structural stabilities of nitrogen-doped ultrathin single-walled boron nanotube. We have considered ultrathin boron nanotubes of diameters <0.5 nm, which include mainly three conformations of BNTs viz. zigzag (5,0), armchair (3,3) and chiral (4,2) with diameters 4.60, 4.78 and 4.87 Å, respectively. It has been investigated that α-BNTs are highly stable, while hexagonal BNTs are found to be least stable. In view of increasing structural stability of hexagonal BNTs, substitutional doping of foreign atoms, i.e. nitrogen is chosen. The nitrogen atoms substitute the host atoms at the middle of the tubes. The substitution doping is made with all the three conformations. The structural stabilities of BNTs have been investigated by using density functional theory (DFT). Subsequently, the cohesive energy is calculated, which directly measures the structural stability. The cohesive energy of BNTs has been calculated for different nitrogen concentrations. We found that the structures get energetically more stable with increasing nitrogen concentration. Moreover, it is also revealed that all the three BNTs are almost equally stable for single-atom doping, while the armchair BNT (3,3) is highly stable followed by zigzag (5,0) and chiral (4,2) BNTs for two- and three-atom doping. The structural stability is an important factor for realization of any physical device. Thus, these BNTs can be used for field emission, semiconducting and highly conducting devices at nanoscale.

  15. Thermodynamic and kinetic studies of laser thermal processing of heavily boron-doped amorphous silicon using molecular dynamics

    NASA Astrophysics Data System (ADS)

    Wang, Liguo; Clancy, Paulette; Thompson, Michael O.; Murthy, Cheruvu S.

    2002-09-01

    Laser thermal processing (LTP) has been proposed as a means to avoid unwanted transient enhanced diffusion and deactivation of dopants, especially boron and arsenic, during the formation of ultrashallow junctions. Although experimental studies have been carried out to determine the efficacy of LTP for pure Si and lightly B-doped junctions, the effects of high concentrations of dopants (above 2% B) on the thermodynamic and kinetic properties of the regrown film are unknown. In this study, a classical interatomic potential model [Stillinger-Weber (SW)] is used with a nonequilibrium molecular dynamics computer simulation technique to study the laser thermal processing of heavily B-doped Si in the range 2-10 at. % B. We observe only a small effect of boron concentration on the congruent melting temperature of the B:Si alloy, and thus the narrowing of the "process window" for LTP is predicted to be small. No significant tendency for boron to segregate was observed at either the regrowth front or the buried c-Si interface during fast regrowth. The B-doped region regrew as defect-free crystal with full activation of the boron atoms at low boron concentrations (2%), in good agreement with experiments. As the concentration of boron increased, the number of intrinsic Si defects and boron interstitials in the regrown materials increased, with a minor amount of boron atoms in clusters (<2%). An instability limit for crystal regrowth was observed at around 8%-10% boron atoms during fast regrowth; systems with 10% B showed partial amorphization during regrowth. Comparison with tight-binding quantum mechanical calculations showed that the SW model gives similar diffusivities in the liquid and tendency to cluster, but the lifetimes of the SW clusters are considerably too long (>150 ps, compared to 5 ps in tight binding). The importance of adequate system size is discussed.

  16. Synthesis and properties of boron doped ZnO nanorods on silicon substrate by low-temperature hydrothermal reaction

    NASA Astrophysics Data System (ADS)

    Yu, Qi; Li, Liuan; Li, Hongdong; Gao, Shiyong; Sang, Dandan; Yuan, Jujun; Zhu, Pinwen

    2011-05-01

    Boron doped ZnO nanorods were fabricated by hydrothermal technique on silicon substrate covered with a ZnO seed layer. It is found that the concentration of boric acid in the reaction solution plays a key role in varying the morphology and properties of the products. The growth rate along the [0 0 0 1] orientation (average size in diameter) of the doped ZnO nanorods decreased (increased) with the increase of boric acid concentration. Based on the results of XRD, EDX and XPS, it is demonstrated that the boron dopants tend to occupy the octahedral interstice sites. The photoluminescence of the ZnO nanorods related to boron doping are investigated.

  17. Nitrogen-Doped Carbon Nanotube/Graphite Felts as Advanced Electrode Materials for Vanadium Redox Flow Batteries.

    PubMed

    Wang, Shuangyin; Zhao, Xinsheng; Cochell, Thomas; Manthiram, Arumugam

    2012-08-16

    Nitrogen-doped carbon nanotubes have been grown, for the first time, on graphite felt (N-CNT/GF) by a chemical vapor deposition approach and examined as an advanced electrode for vanadium redox flow batteries (VRFBs). The unique porous structure and nitrogen doping of N-CNT/GF with increased surface area enhances the battery performance significantly. The enriched porous structure of N-CNTs on graphite felt could potentially facilitate the diffusion of electrolyte, while the N-doping could significantly contribute to the enhanced electrode performance. Specifically, the N-doping (i) modifies the electronic properties of CNT and thereby alters the chemisorption characteristics of the vanadium ions, (ii) generates defect sites that are electrochemically more active, (iii) increases the oxygen species on CNT surface, which is a key factor influencing the VRFB performance, and (iv) makes the N-CNT electrochemically more accessible than the CNT. PMID:26295765

  18. Plasma Synthesized Doped Boron Nanopowder for MgB2 Superconductors

    SciTech Connect

    James V. Marzik

    2012-03-26

    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

  19. Nanoscale Control of Rewriteable Doping Patterns in Pristine Graphene/Boron Nitride Heterostructures.

    PubMed

    Velasco, Jairo; Ju, Long; Wong, Dillon; Kahn, Salman; Lee, Juwon; Tsai, Hsin-Zon; Germany, Chad; Wickenburg, Sebastian; Lu, Jiong; Taniguchi, Takashi; Watanabe, Kenji; Zettl, Alex; Wang, Feng; Crommie, Michael F

    2016-03-01

    Nanoscale control of charge doping in two-dimensional (2D) materials permits the realization of electronic analogs of optical phenomena, relativistic physics at low energies, and technologically promising nanoelectronics. Electrostatic gating and chemical doping are the two most common methods to achieve local control of such doping. However, these approaches suffer from complicated fabrication processes that introduce contamination, change material properties irreversibly, and lack flexible pattern control. Here we demonstrate a clean, simple, and reversible technique that permits writing, reading, and erasing of doping patterns for 2D materials at the nanometer scale. We accomplish this by employing a graphene/boron nitride heterostructure that is equipped with a bottom gate electrode. By using electron transport and scanning tunneling microscopy (STM), we demonstrate that spatial control of charge doping can be realized with the application of either light or STM tip voltage excitations in conjunction with a gate electric field. Our straightforward and novel technique provides a new path toward on-demand graphene p-n junctions and ultrathin memory devices. PMID:26852622

  20. Self-compensation property of β-rhombohedral boron doped with high Li concentration

    NASA Astrophysics Data System (ADS)

    Hyodo, H.; Nezu, A.; Soga, K.; Kimura, K.

    2012-11-01

    A high concentration of Li (up to LiB5.8; 18 Li/cell) was doped into β-rhombohedral boron (β-B), which has a crystalline structure built up from B12 icosahedral clusters, by sealing the raw materials in a stainless-steel tube. The relation between the structure and the electronic properties was clarified and a self-compensation property of Li- or Mg-doped β-B was discussed. The Li concentration was analyzed by atomic absorption spectrometry. The changes in the structure and the electronic properties were investigated by X-ray diffraction using the Rietveld method and by electrical conductivity measurements, respectively. Li occupies the A1, D, E and F sites, and the occupancies of the B sites (B13, B16 and B4) decrease with increasing Li doping. In Li- or Mg-doped β-B, electron doping is compensated by the removal of interstitial B atoms at the B16 site and by the generation of vacancies at the B13 and B4 sites. There have been no reports of self-compensation in other crystalline elemental semiconductors.

  1. Effect of rapid thermal annealing on recombination centres in boron-doped Czochralski-grown silicon

    SciTech Connect

    Walter, D. C. Lim, B.; Bothe, K.; Schmidt, J.; Voronkov, V. V.; Falster, R.

    2014-01-27

    Rapid thermal annealing in a belt furnace results in a dramatic change of the recombination properties of boron-doped Czochralski silicon: (1) the lifetime degraded by applying a prolonged illumination at room temperature was significantly improved, (2) after subsequent dark recovery, the lifetime has a remarkably high value, and (3) the permanent recovery, by annealing at 185 °C under illumination, is enormously accelerated, and the finally achieved stable lifetime acquires a record value of 1.5 ms, as compared to 110 μs after permanent recovery of not-annealed reference samples.

  2. Photovoltaic Device Including A Boron Doping Profile In An I-Type Layer

    DOEpatents

    Yang, Liyou

    1993-10-26

    A photovoltaic cell for use in a single junction or multijunction photovoltaic device, which includes a p-type layer of a semiconductor compound including silicon, an i-type layer of an amorphous semiconductor compound including silicon, and an n-type layer of a semiconductor compound including silicon formed on the i-type layer. The i-type layer including an undoped first sublayer formed on the p-type layer, and a boron-doped second sublayer formed on the first sublayer.

  3. Visible-light sensitization of boron-doped nanocrystalline diamond through non-covalent surface modification.

    PubMed

    Krysova, Hana; Vlckova-Zivcova, Zuzana; Barton, Jan; Petrak, Vaclav; Nesladek, Milos; Cigler, Petr; Kavan, Ladislav

    2015-01-14

    A novel simple and versatile synthetic strategy is developed for the surface modification of boron-doped diamond. In a two-step procedure, polyethyleneimine is adsorbed on the hydrogenated diamond surface and subsequently modified with a model light-harvesting donor-π-bridge-acceptor molecule (coded P1). The sensitized diamond exhibits stable cathodic photocurrents under visible-light illumination in aqueous electrolyte solution with dimethylviologen serving as an electron mediator. In spite of the simplicity of the surface sensitization protocol, the photoelectrochemical performance is similar to or better than that of other sensitized diamond electrodes which were reported in previous studies (2008-2014). PMID:25418375

  4. Localized electropolymerization on oxidized boron-doped diamond electrodes modified with pyrrolyl units.

    PubMed

    Actis, Paolo; Manesse, Mael; Nunes-Kirchner, Carolina; Wittstock, Gunther; Coffinier, Yannick; Boukherroub, Rabah; Szunerits, Sabine

    2006-11-14

    This paper describes the functionalization of oxidized boron-doped diamond (BDD) electrodes with N-(3-trimethoxysilylpropyl)pyrrole (TMPP) and the influence of this layer on the electrochemical transfer kinetics as well as on the possibility of forming strongly adhesive polypyrrole films on the BDD interface through electropolymerization. Furthermore, localized polymer formation was achieved on the TMPP-modified BDD interface using the direct mode of a scanning electrochemical microscope (SECM) as well as an electrochemical scanning near-field optical microscope (E-SNOM). Depending on the method used polypyrrole dots with diameters in the range of 1-250 microm are electrogenerated. PMID:17066183

  5. Boron- and Nitrogen-Doped Phenalenyls: Unexpected 2e/ and 4e/all-sites pi-pi Covalency and Genuine Pancake Double Bonding

    DOE PAGESBeta

    Tian, Yong-Hui; Huang, Jingsong; Sumpter, Bobby G

    2015-01-01

    Phenalenyl is an important neutral pi-radical due to its capability to form unconventional pancake pi-pi bonding interactions, whereas its analogues with graphitic boron (B) or nitrogen (N)-doping have been regarded as closed-shell systems and therefore received much less attention. By using high-level quantum chemistry calculations, we show that the B- and N-doped closed-shell phenalenyls unexpectedly form open-shell singlet pi-dimers with diradicaloid character featuring 2e/all-sites double pi-pi bonding. Moreover, by proper substitutions, the doped phenalenyl derivatives can be made open-shell species that form closed shell singlet pi-dimers bound by stronger 4e/all-sites double pi-pi bonding. The covalent pi-pi bonding overlap is distributedmore » on all of the atomic sites giving robust and genuine pancake-shaped pi-dimers which, depending on the number of electrons available in the bonding interactions, are equally or more stable than the pi-dimers of the pristine phenalenyl.« less

  6. Pancake π–π Bonding Goes Double: Unexpected 4e/All-Sites Bonding in Boron- and Nitrogen-Doped Phenalenyls

    SciTech Connect

    Tian, Yong-Hui; Sumpter, Bobby G.; Du, Shiyu; Huang, Jingsong

    2015-06-03

    Phenalenyl is an important neutral pi-radical due to its capability to form unconventional pancake pi-pi bonding interactions, whereas its analogues with graphitic boron (B) or nitrogen (N)-doping have been regarded as closed-shell systems and therefore received much less attention. By using high-level quantum chemistry calculations, we also show that the B- and N-doped closed-shell phenalenyls unexpectedly form open-shell singlet pi-dimers with diradicaloid character featuring 2e/all-sites double pi-pi bonding. Moreover, by proper substitutions, the doped phenalenyl derivatives can be made open-shell species that form closed shell singlet pi-dimers bound by stronger 4e/all-sites double pi-pi bonding. Moreover, covalent pi-pi bonding overlap is distributed on all of the atomic sites giving robust and genuine pancake-shaped pi-dimers which, depending on the number of electrons available in the bonding interactions, are equally or more stable than the pi-dimers of the pristine phenalenyl.

  7. Pancake π–π Bonding Goes Double: Unexpected 4e/All-Sites Bonding in Boron- and Nitrogen-Doped Phenalenyls

    DOE PAGESBeta

    Tian, Yong-Hui; Sumpter, Bobby G.; Du, Shiyu; Huang, Jingsong

    2015-06-03

    Phenalenyl is an important neutral pi-radical due to its capability to form unconventional pancake pi-pi bonding interactions, whereas its analogues with graphitic boron (B) or nitrogen (N)-doping have been regarded as closed-shell systems and therefore received much less attention. By using high-level quantum chemistry calculations, we also show that the B- and N-doped closed-shell phenalenyls unexpectedly form open-shell singlet pi-dimers with diradicaloid character featuring 2e/all-sites double pi-pi bonding. Moreover, by proper substitutions, the doped phenalenyl derivatives can be made open-shell species that form closed shell singlet pi-dimers bound by stronger 4e/all-sites double pi-pi bonding. Moreover, covalent pi-pi bonding overlap ismore » distributed on all of the atomic sites giving robust and genuine pancake-shaped pi-dimers which, depending on the number of electrons available in the bonding interactions, are equally or more stable than the pi-dimers of the pristine phenalenyl.« less

  8. Effect of Boron-Doping on the Graphene Aerogel Used as Cathode for the Lithium-Sulfur Battery.

    PubMed

    Xie, Yang; Meng, Zhen; Cai, Tingwei; Han, Wei-Qiang

    2015-11-18

    A porous interconnected 3D boron-doped graphene aerogel (BGA) was prepared via a one-pot hydrothermal treatment. The BGA material was first loaded with sulfur to serve as cathode in lithium-sulfur batteries. Boron was positively polarized on the graphene framework, allowing for chemical adsorption of negative polysufide species. Compared with nitrogen-doped and undoped graphene aerogel, the BGA-S cathode could deliver a higher capacity of 994 mA h g(-1) at 0.2 C after 100 cycles, as well as an outstanding rate capability, which indicated the BGA was an ideal cathode material for lithium-sulfur batteries. PMID:26544917

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

    PubMed

    Tontapha, Sarawut; Ruangpornvisuti, Vithaya; Wanno, Banchob

    2013-01-01

    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

  10. Tight-binding studies of the tendency for boron to cluster in c-Si. II. Interaction of dopants and defects in boron-doped Si

    NASA Astrophysics Data System (ADS)

    Luo, Weiwei; Rasband, Paul B.; Clancy, Paulette; Roberts, Bruce W.

    1998-09-01

    Clusters containing up to five boron atoms were considered as extended defects within a crystalline Si matrix. Tight-binding calculations suggest that a cluster containing two boron atoms occupying substitutional sites is stable, unlike any other small boron cluster that we studied. The formation energy increases when a third and fourth substitutional boron atom is added to the cluster. Estimates of the equilibrium concentration, using tight-binding-derived formation energies and formation entropies from the Stillinger-Weber model, indicate that B2 clusters become important when the boron doping level is ˜1018cm-3, well below the solubility limit. In contrast, the formation energy of defect clusters involving an interstitial (BnI clusters, n=1-5, in their preferred charge states) decreases with increasing cluster size, down to 0.6 eV for B5I in a -5 charge state. None had formation energies that would lead to stable bound clusters. Several BnI clusters were found to be considerably more stable than isolated Si self-interstitials (by 1-2 eV), the BSBI cluster, assumed in some continuum modeling codes to be important, was not a particular interesting defect structure (a formation energy in the -2 charge state, EF-2, of 2.8 eV). There seemed to be little energetic penalty for creating clusters larger than about B5I, in good agreement with Sinno and Brown's Stillinger-Weber studies of self-interstitial clusters in Si [Mater. Res. Soc. Symp. Proc. 378, 95 (1997)]. Some support was found for the suggestion of Pelaz et al. [Appl. Phys. Lett. 70, 2285 (1997)] that BI2 is a nucleation site for boron clustering. Boron clusters involving a boron interstitial were generally found to be less likely to form than analogous clusters involving a Si self-interstitial. B2 clusters involving vacancies are not energetically favored, confirming the known tendency for boron to diffuse via an interstitial mechanism rather than vacancies. These results suggest that boron clusters could

  11. Boron-Doped Anatase TiO2 as a High-Performance Anode Material for Sodium-Ion Batteries.

    PubMed

    Wang, Baofeng; Zhao, Fei; Du, Guodong; Porter, Spencer; Liu, Yong; Zhang, Peng; Cheng, Zhenxiang; Liu, Hua Kun; Huang, Zhenguo

    2016-06-29

    Pristine and boron-doped anatase TiO2 were prepared via a facile sol-gel method and the hydrothermal method for application as anode materials in sodium-ion batteries (SIBs). The sol-gel method leads to agglomerated TiO2, whereas the hydrothermal method is conducive to the formation of highly crystalline and discrete nanoparticles. The structure, morphology, and electrochemical properties were studied. The crystal size of TiO2 with boron doping is smaller than that of the nondoped crystals, which indicates that the addition of boron can inhibit the crystal growth. The electrochemical measurements demonstrated that the reversible capacity of the B-doped TiO2 is higher than that for the pristine sample. B-doping also effectively enhances the rate performance. The capacity of the B-doped TiO2 could reach 150 mAh/g at the high current rate of 2C and the capacity decay is only about 8 mAh/g over 400 cycles. The remarkable performance could be attributed to the lattice expansion resulting from B doping and the shortened Li(+) diffusion distance due to the nanosize. These results indicate that B-doped TiO2 can be a good candidate for SIBs. PMID:27258029

  12. Structural and electronic properties of cubic boron nitride doped with zinc

    SciTech Connect

    Li, Yubo; Cheng, Tianyuan; Wang, Xiao; Jiang, Huaxing; Yang, Hangsheng; Nose, Kenji

    2014-07-28

    Structural and electronic properties of Zn-doped cubic boron nitride (cBN) were investigated via first principle calculation based on density functional theory. Our simulation suggests that Zn can substitute for both B (Zn{sub B}) and N (Zn{sub N}) atom; Zn{sub B} is energetically favorable, and Zn{sub N} can only be prepared under B-rich conditions. Zn{sub B} induced a shallow acceptor level; however, the large difference in electronegativity between Zn and N makes the acceptor level strongly localized, which reduces effective carrier density. In the case of Zn{sub N}, both deep acceptor levels within band gap and shallow acceptor levels at the top of valence band were induced, which produced more free carriers than Zn{sub B}. The calculated results account for experimental results of enhanced electric conductivity of Zn-doped cBN films prepared under B-rich conditions.

  13. Complex Boron Redistribution in P+ Doped-polysilicon / Nitrogen Doped Silicon Bi-layers during Activation Annealing

    NASA Astrophysics Data System (ADS)

    Abadli, S.; Mansour, F.; Perrera, E. Bedel

    We have investigated and modeled the complex phenomenon of boron (B) redistribution process in strongly doped silicon bilayers structure. A one-dimensional two stream transfer model well adapted to the particular structure of bi- layers and to the effects of strong-concentrations has been developed. This model takes into account the instantaneous kinetics of B transfer, trapping, clustering and segregation during the thermal B activation annealing. The used silicon bi-layers have been obtained by low pressure chemical vapor deposition (LPCVD) method, using in-situ nitrogen- doped-silicon (NiDoS) layer and strongly B doped polycrystalline-silicon (P+) layer. To avoid long redistributions, thermal annealing was carried out at relatively lowtemperatures (600 °C and 700 °C) for various times ranging between 30 minutes and 2 hours. The good adjustment of the simulated profiles with the experimental secondary ion mass spectroscopy (SIMS) profiles allowed a fundamental understanding about the instantaneous physical phenomena giving and disturbing the complex B redistribution profiles-shoulders kinetics.

  14. Optoelectronic surface-related properties in boron-doped and irradiated diamond thin films

    SciTech Connect

    Nemashkalo, A.; Chapagain, P. R.; Strzhemechny, Y. M.; Peters, R. M.; Farmer, J.; Gupta, S.

    2012-01-15

    Elucidation of microscopic properties of synthetic diamond films, such as formation and evolution of bulk and surface defects, chemistry of dopants, is necessary for a reliable quality control and reproducibility in applications. Surface photovoltage (SPV) spectroscopy and photoluminescence (PL) spectroscopy were employed to study diamond thin films grown on silicon by microwave plasma-assisted chemical vapor deposition and hot-filament chemical vapor deposition with different levels of boron doping in conjunction with gamma irradiation. SPV experiments showed that while the increase of boron concentration leads to a semiconductor-metal transition, subsequent gamma irradiation reverts quasi-metallic samples back to a semiconducting state by compensating electrical activity of boron possibly via hydrogen. One of the most pronounced common transitions observed at {approx}3.1-3.2 eV in the SPV spectra was also present in all of the PL spectra. It is likely that this is a signature of the sp{sup 2}-hybridized carbon clusters in or in the vicinity of grain boundaries.

  15. Defect charge states in Si doped hexagonal boron-nitride monolayer

    NASA Astrophysics Data System (ADS)

    Mapasha, R. E.; Molepo, M. P.; Andrew, R. C.; Chetty, N.

    2016-02-01

    We perform ab initio density functional theory calculations to investigate the energetics, electronic and magnetic properties of isolated stoichiometric and non-stoichiometric substitutional Si complexes in a hexagonal boron-nitride monolayer. The Si impurity atoms substituting the boron atom sites SiB giving non-stoichiometric complexes are found to be the most energetically favourable, and are half-metallic and order ferromagnetically in the neutral charge state. We find that the magnetic moments and magnetization energies increase monotonically when Si defects form a cluster. Partial density of states and standard Mulliken population analysis indicate that the half-metallic character and magnetic moments mainly arise from the Si 3p impurity states. The stoichiometric Si complexes are energetically unfavorable and non-magnetic. When charging the energetically favourable non-stoichiometric Si complexes, we find that the formation energies strongly depend on the impurity charge states and Fermi level position. We also find that the magnetic moments and orderings are tunable by charge state modulation q  =  -2, -1, 0, +1, +2. The induced half-metallic character is lost (retained) when charging isolated (clustered) Si defect(s). This underlines the potential of a Si doped hexagonal boron-nitride monolayer for novel spin-based applications.

  16. Optoelectronic surface-related properties in boron-doped and irradiated diamond thin films

    NASA Astrophysics Data System (ADS)

    Nemashkalo, A.; Chapagain, P. R.; Peters, R. M.; Farmer, J.; Gupta, S.; Strzhemechny, Y. M.

    2012-01-01

    Elucidation of microscopic properties of synthetic diamond films, such as formation and evolution of bulk and surface defects, chemistry of dopants, is necessary for a reliable quality control and reproducibility in applications. Surface photovoltage (SPV) spectroscopy and photoluminescence (PL) spectroscopy were employed to study diamond thin films grown on silicon by microwave plasma-assisted chemical vapor deposition and hot-filament chemical vapor deposition with different levels of boron doping in conjunction with gamma irradiation. SPV experiments showed that while the increase of boron concentration leads to a semiconductor-metal transition, subsequent gamma irradiation reverts quasi-metallic samples back to a semiconducting state by compensating electrical activity of boron possibly via hydrogen. One of the most pronounced common transitions observed at ˜3.1-3.2 eV in the SPV spectra was also present in all of the PL spectra. It is likely that this is a signature of the sp2-hybridized carbon clusters in or in the vicinity of grain boundaries.

  17. Improving performance of armchair graphene nanoribbon field effect transistors via boron nitride doping

    NASA Astrophysics Data System (ADS)

    Goharrizi, A. Yazdanpanah; Sanaeepur, M.; Sharifi, M. J.

    2015-09-01

    Device performance of 10 nm length armchair graphene nanoribbon field effect transistors with 1.5 nm and 4 nm width (13 and 33 atoms in width respectively) are compared in terms of Ion /Ioff , trans-conductance, and sub-threshold swing. While narrow devices suffer from edge roughness wider devices are subject to more substrate surface roughness and reduced bandgap. Boron Nitride doping is employed to compensate reduced bandgap in wider devices. Simultaneous effects of edge and substrate surface roughness are considered. Results show that in the presence of both the edge and substrate surface roughness the 4 nm wide device with boron nitride doping shows improved performance with respect to the 1.5 nm one (both of which incorporate the same bandgap AGNR as channel material). Electronic simulations are performed via NEGF method along with tight-binding Hamiltonian. Edge and surface roughness are created by means of one and two dimensional auto correlation functions respectively. Electronic characteristics are averaged over a large number of devices due to statistic nature of both the edge and surface roughness.

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

    PubMed

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

    2010-08-01

    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

  19. Fabrication and Characterization of N-Type Zinc Oxide/P-Type Boron Doped Diamond Heterojunction

    NASA Astrophysics Data System (ADS)

    Marton, Marián; Mikolášek, Miroslav; Bruncko, Jaroslav; Novotný, Ivan; Ižák, Tibor; Vojs, Marian; Kozak, Halyna; Varga, Marián; Artemenko, Anna; Kromka, Alexander

    2015-09-01

    Diamond and ZnO are very promising wide-bandgap materials for electronic, photovoltaic and sensor applications because of their excellent electrical, optical, physical and electrochemical properties and biocompatibility. In this contribution we show that the combination of these two materials opens up the potential for fabrication of bipolar heterojunctions. Semiconducting boron doped diamond (BDD) thin films were grown on Si and UV grade silica glass substrates by HFCVD method with various boron concentration in the gas mixture. Doped zinc oxide (ZnO:Al, ZnO:Ge) thin layers were deposited by diode sputtering and pulsed lased deposition as the second semiconducting layer on the diamond films. The amount of dopants within the films was varied to obtain optimal semiconducting properties to form a bipolar p-n junction. Finally, different ZnO/BDD heterostructures were prepared and analyzed. Raman spectroscopy, SEM, Hall constant and I-V measurements were used to investigate the quality, structural and electrical properties of deposited heterostructures, respectively. I-V measurements of ZnO/BDD diodes show a rectifying ratio of 55 at ±4 V. We found that only very low dopant concentrations for both semiconducting materials enabled us to fabricate a functional p-n junction. Obtained results are promising for fabrication of optically transparent ZnO/BDD bipolar heterojunction.

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

    PubMed Central

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

    2008-01-01

    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.

  1. Development of neuraminidase detection using gold nanoparticles boron-doped diamond electrodes.

    PubMed

    Wahyuni, Wulan T; Ivandini, Tribidasari A; Saepudin, Endang; Einaga, Yasuaki

    2016-03-15

    Gold nanoparticles-modified boron-doped diamond (AuNPs-BDD) electrodes, which were prepared with a self-assembly deposition of AuNPs at amine-terminated boron-doped diamond, were examined for voltammetric detection of neuraminidase (NA). The detection method was performed based on the difference of electrochemical responses of zanamivir at gold surface before and after the reaction with NA in phosphate buffer solution (PBS, pH 5.5). A linear calibration curve for zanamivir in 0.1 M PBS in the absence of NA was achieved in the concentration range of 1 × 10(-6) to 1 × 10(-5) M (R(2) = 0.99) with an estimated limit of detection (LOD) of 2.29 × 10(-6) M. Furthermore, using its reaction with 1.00 × 10(-5) M zanamivir, a linear calibration curve of NA can be obtained in the concentration range of 0-12 mU (R(2) = 0.99) with an estimated LOD of 0.12 mU. High reproducibility was shown with a relative standard deviation (RSD) of 1.14% (n = 30). These performances could be maintained when the detection was performed in mucin matrix. Comparison performed using gold-modified BDD (Au-BDD) electrodes suggested that the good performance of the detection method is due to the stability of the gold particles position at the BDD surface. PMID:26717895

  2. Pure and carbon-doped boron phosphide (6,0) zigzag nanotube: A computational NMR study

    NASA Astrophysics Data System (ADS)

    Arshadi, S.; Bekhradnia, A. R.; Alipour, F.; Abedini, S.

    2015-11-01

    Calculations were performed for investigation of the properties of the electronic structure of Carbon- Doped Boron Phosphide Nanotube (CDBPNT). Pristine and three models of C-doped structures of (6,0) zigzag BPNT were studied at density functional theory (DFT) in combination with 6-311G* basis set using Gaussian package of program. The calculated parameters reveal that various 11B and 31P nuclei are divided into some layers with equivalent electrostatic properties. The electronic structure properties are highly influenced by replacement of 11B and 31P atoms by 12C atoms in pristine model. Furthermore, the HOMO-LUMO gap energy for suggested doped models (I), (II) and (III) were lower than pure BPNT pristine systems. The dipole moment values of models (II) and (III) were decreased to 1.788 and 1.789, respectively while the dipole moments of model (I) were enhanced to 4.373, in compare to pure pristine one (2.586). The magnitude of changes in Chemical Shielding (CS) tensor parameters revealed that the electron density at the site of 31P was higher than that at the site of 11B due to carbon doping.

  3. Tuning dissociation using isoelectronically doped graphene and hexagonal boron nitride: Water and other small molecules.

    PubMed

    Al-Hamdani, Yasmine S; Alfè, Dario; von Lilienfeld, O Anatole; Michaelides, Angelos

    2016-04-21

    Novel uses for 2-dimensional materials like graphene and hexagonal boron nitride (h-BN) are being frequently discovered especially for membrane and catalysis applications. Still however, a great deal remains to be understood about the interaction of environmentally and industrially relevant molecules such as water with these materials. Taking inspiration from advances in hybridising graphene and h-BN, we explore using density functional theory, the dissociation of water, hydrogen, methane, and methanol on graphene, h-BN, and their isoelectronic doped counterparts: BN dopedgraphene and C doped h-BN. We find that dopedsurfaces are considerably more reactive than their pristine counterparts and by comparing the reactivity of several small molecules, we develop a general framework for dissociative adsorption. From this a particularly attractive consequence of isoelectronic doping emerges: substrates can be doped to enhance their reactivity specifically towards either polar or non-polar adsorbates. As such, these substrates are potentially viable candidates for selective catalysts and membranes, with the implication that a range of tuneable materials can be designed. PMID:27389233

  4. Iron-boron pairing kinetics in illuminated p-type and in boron/phosphorus co-doped n-type silicon

    SciTech Connect

    Möller, Christian; Bartel, Til; Gibaja, Fabien; Lauer, Kevin

    2014-07-14

    Iron-boron (FeB) pairing is observed in the n-type region of a boron and phosphorus co-doped silicon sample which is unexpected from the FeB pair model of Kimerling and Benton. To explain the experimental data, the existing FeB pair model is extended by taking into account the electronic capture and emission rates at the interstitial iron (Fe{sub i}) trap level as a function of the charge carrier densities. According to this model, the charge state of the Fe{sub i} may be charged in n-type making FeB association possible. Further, FeB pair formation during illumination in p-type silicon is investigated. This permits the determination of the charge carrier density dependent FeB dissociation rate and in consequence allows to determine the acceptor concentration in the co-doped n-type silicon by lifetime measurement.

  5. Hierarchically controlled helical graphite films prepared from iodine-doped helical polyacetylene films using morphology-retaining carbonization.

    PubMed

    Matsushita, Satoshi; Kyotani, Mutsumasa; Akagi, Kazuo

    2011-11-01

    One-handed helical graphite films with a hierarchically controlled morphology were prepared from iodine-doped helical polyacetylene (H-PA) films using the recently developed morphology-retaining carbonization method. Results from scanning electron microscopy indicate that the hierarchical helical morphology of the H-PA film remains unchanged even after carbonization at 800 °C. The weight loss of the film due to carbonization was very small; only 10-29% of the weight of the film before doping was lost. Furthermore, the graphite film prepared by subsequent heating at 2600 °C retained the same morphology as that of the original H-PA film and that of the helical carbon film prepared at 800 °C. The screwed direction, twisted degree, and vertical or horizontal alignment of the helical graphite film were well controlled by changing the helical sense, helical pitch, and orientation state of the chiral nematic liquid crystal (N*-LC) used as an asymmetric LC reaction field. X-ray diffraction and Raman scattering measurements showed that graphitic crystallization proceeds in the carbon film during heat treatment at 2600 °C. Transmission electron microscopy measurements indicate that ultrasonication of the helical graphite film in ethanol for several hours gives rise to a single helical graphite fibril. The profound potentiality of the present graphite films is exemplified in their electrical properties. The horizontally aligned helical graphite film exhibits an enhancement in electrical conductivity and an evolution of electrical anisotropy in which conductivity parallel to the helical axis of the fibril bundle is higher than that perpendicular to the axis. PMID:21970653

  6. Free-standing nano-scale graphite saturable absorber for passively mode-locked erbium doped fiber ring laser Free-standing nano-scale graphite saturable absorber

    NASA Astrophysics Data System (ADS)

    Lin, Y.-H.; Lin, G.-R.

    2012-05-01

    The free-standing graphite nano-particle located between two FC/APC fiber connectors is employed as the saturable absorber to passively mode-lock the ring-type Erbium-doped fiber laser (EDFL). The host-solvent-free graphite nano-particles with sizes of 300 - 500 nm induce a comparable modulation depth of 54%. The interlayer-spacing and lattice fluctuations of polished graphite nano-particles are observed from the weak 2D band of Raman spectrum and the azimuth angle shift of -0.32° of {002}-orientation dependent X-ray diffraction peak. The graphite nano-particles mode-locked EDFL generates a 1.67-ps pulsewidth at linearly dispersion-compensated regime with a repetition rate of 9.1 MHz. The time-bandwidth product of 0.325 obtained under a total intra-cavity group-delay-dispersion of -0.017 ps2 is nearly transform-limited. The extremely high stability of the nano-scale graphite saturable absorber during mode-locking is observed at an intra-cavity optical energy density of 7.54 mJ/cm2. This can be attributed to its relatively high damage threshold (one order of magnitude higher than the graphene) on handling the optical energy density inside the EDFL cavity. The graphite nano-particle with reduced size and sufficient coverage ratio can compete with other fast saturable absorbers such as carbon nanotube or graphene to passively mode-lock fiber lasers with decreased insertion loss and lasing threshold.

  7. Pros and cons of nickel- and boron-doping to study helium effects in ferritic/martensitic steels

    NASA Astrophysics Data System (ADS)

    Hashimoto, N.; Klueh, R. L.; Shiba, K.

    2002-12-01

    In the absence of a 14 MeV neutron source, the effect of helium on structural materials for fusion must be simulated using fission reactors. Helium effects in ferritic/martensitic steels have been studied by adding nickel and boron and irradiating in a mixed-spectrum reactor. Although the nickel- and boron-doping techniques have limitations and difficulties to estimate helium effects on the ferritic/martensitic steels, past irradiation experiments using these techniques have demonstrated similar effects on the swelling and Charpy impact properties that are indicative of a helium effect. Although both techniques have disadvantages, it should be possible to plan experiments using the nickel- and boron-doping techniques to develop an understanding of the effects of helium on mechanical properties.

  8. ortho-Selective phenol-coupling reaction by anodic treatment on boron-doped diamond electrode using fluorinated alcohols.

    PubMed

    Kirste, Axel; Nieger, Martin; Malkowsky, Itamar M; Stecker, Florian; Fischer, Andreas; Waldvogel, Siegfried R

    2009-01-01

    Enlarged scope by fluorinated mediators: Oxyl radicals are easily formed on boron-doped diamond (BDD) electrodes and can be exploited for the ortho-selective coupling to the corresponding biphenols (see scheme). At partial conversion, a clean transformation is achieved that can be applied to electron-rich as well as fluorinated phenols. PMID:19180606

  9. Boron-doped graphene as promising support for platinum catalyst with superior activity towards the methanol electrooxidation reaction

    NASA Astrophysics Data System (ADS)

    Sun, Yongrong; Du, Chunyu; An, Meichen; Du, Lei; Tan, Qiang; Liu, Chuntao; Gao, Yunzhi; Yin, Geping

    2015-12-01

    We report the synthesis of boron-doped graphene by thermally annealing the mixture of graphene oxide and boric acid, and its usage as the support of Pt catalyst towards the methanol oxidation reaction. The composition, structure and morphology of boron-doped graphene and its supported Pt nanoparticles (Pt/BG) are characterized by transmission electron microscopy, inductively coupled plasma mass spectrometry, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. It is revealed that boron atoms are doped into graphene network in the form of BC2O and BCO2 bonds, which lead to the increase in defect sites and facilitate the subsequent deposition of Pt nanoparticles. Therefore, the Pt/BG catalyst presents smaller particle size and narrower size distribution than the graphene supported Pt (Pt/G) catalyst. When evaluated as the electrocatalyst for the methanol oxidation reaction, the Pt/BG catalyst exhibits excellent electrochemical activity and stability demonstrated by cyclic voltammetry and chronoamperometry tests. The enhanced activity is mainly ascribed to the electronic interaction between boron-doped graphene and Pt nanoparticles, which lowers the d-band center of Pt and thus weakens the absorption of the poisoning intermediate CO. Our work provides an alternative approach of improving the reaction kinetics for the oxidation of small organic molecules.

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

    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 ( λ ≥ 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.

  11. Theoretical study of the adsorption of pentachlorophenol on the pristine and Fe-doped boron nitride nanotubes.

    PubMed

    Wang, Ruo-xi; Zhang, Dong-ju; Zhu, Rong-xiu; Liu, Cheng-bu

    2014-02-01

    To explore the novel application of boron nitride nanotubes (BNNTs), we investigated the interaction of pentachlorophenol (PCP) pollutant with the pristine and Fe doped (Fe-doped) (8, 0) single-walled BNNTs by performing density functional theory calculations. Compared with the weak physisorption on the pristine BNNT, PCP molecule presents strong chemisorption on the Fe-doped BNNT. The calculated data for the electronic properties indicate that doping Fe atom into the BNNT significantly improves the electronic transport property of BNNT, induces magnetism in the BNNT, and increases its adsorption sensitivity toward PCP molecule. It is suggested that doping BNNTs with Fe is an available strategy for improving the properties of BNNTs, and that Fe-doped BNNT would be a potential resource for adsorbing PCP pollutant in environments. PMID:24504454

  12. Boron concentration profiling by high angle annular dark field-scanning transmission electron microscopy in homoepitaxial δ-doped diamond layers

    SciTech Connect

    Araújo, D.; Alegre, M. P.; Piñero, J. C.; Fiori, A.; Bustarret, E.; Jomard, F.

    2013-07-22

    To develop further diamond related devices, the concentration and spatial location of dopants should be controlled down to the nanometer scale. Scanning transmission electron microscopy using the high angle annular dark field mode is shown to be sensitive to boron doping in diamond epilayers. An analytical procedure is described, whereby local boron concentrations above 10{sup 20} cm{sup −3} were quantitatively derived down to nanometer resolution from the signal dependence on thickness and boron content. Experimental boron local doping profiles measured on diamond p{sup −}/p{sup ++}/p{sup −} multilayers are compared to macroscopic profiles obtained by secondary ion mass spectrometry, avoiding reported artefacts.

  13. Effects of boron and glass hybrid epoxy-composites on graphite-fiber release in an aircraft fire

    NASA Technical Reports Server (NTRS)

    Tompkins, S. S.; Brewer, W. D.

    1979-01-01

    Recent studies have shown that the benefits gained by using graphite-epoxy composite structures may not be realized without some risk. The graphite fibers are very good electrical conductors and fibers released into the environment during a fire create a possible hazard to electrical equipment. Several graphite-epoxy hybrids were exposed to a fire and simulated explosion and their graphite fiber retention characteristics were examined. Several low melting-temperature glasses which wet and clump graphite-fibers and a glass/graphite fabric which reduced impact damage were identified as promising hybridizing components to minimize graphite fiber release.

  14. Can trans-polyacetylene be formed on single-walled carbon-doped boron nitride nanotubes?

    PubMed

    Chen, Ying; Wang, Hong-xia; Zhao, Jing-xiang; Cai, Qing-hai; Wang, Xiao-guang; Wang, Xuan-zhang

    2012-07-01

    Recently, the grafting of polymer chains onto nanotubes has attracted increasing attention as it can potentially be used to enhance the solubility of nanotubes and in the development of novel nanotube-based devices. In this article, based on density functional theory (DFT) calculations, we report the formation of trans-polyacetylene on single-walled carbon-doped boron nitride nanotubes (BNNTs) through their adsorption of a series of C(2)H(2) molecules. The results show that, rather than through [2 + 2] cycloaddition, an individualmolecule would preferentially attach to a carbon-doped BNNT via "carbon attack" (i.e., a carbon in the C(2)H(2) attacks a site on the BNNT). The adsorption energy gradually decreases with increasing tube diameter. The free radical of the carbon-doped BNNT is almost completely transferred to the carbon atom at the end of the adsorbed C(2)H(2) molecule. When another C(2)H(2) molecule approaches the carbon-doped BNNT, it is most energetically favorable for this C(2)H(2) molecule to be adsorbed at the end of the previously adsorbed C(2)H(2) molecule, and so on with extra C(2)H(2) molecules, leading to the formation of polyacetylene on the nanotube. The spin of the whole system is always localized at the tip of the polyacetylene formed, which initiates the adsorption of the incoming species. The present results imply that carbon-doped BNNT is an effective "metal-free" initiator for the formation of polyacetylene. PMID:22271098

  15. Determination of active doping in highly resistive boron doped silicon nanocrystals embedded in SiO2 by capacitance voltage measurement on inverted metal oxide semiconductor structure

    NASA Astrophysics Data System (ADS)

    Zhang, Tian; Puthen-Veettil, Binesh; Wu, Lingfeng; Jia, Xuguang; Lin, Ziyun; Yang, Terry Chien-Jen; Conibeer, Gavin; Perez-Wurfl, Ivan

    2015-10-01

    We investigate the Capacitance-Voltage (CV) measurement to study the electrically active boron doping in Si nanocrystals (ncSi) embedded in SiO2. The ncSi thin films with high resistivity (200-400 Ω cm) can be measured by using an inverted metal oxide semiconductor (MOS) structure (Al/ncSi (B)/SiO2/Si). This device structure eliminates the complications from the effects of lateral current flow and the high sheet resistance in standard lateral MOS structures. The characteristic MOS CV curves observed are consistent with the effective p-type doping. The CV modeling method is presented and used to evaluate the electrically active doping concentration. We find that the highly boron doped ncSi films have electrically active doping of 1018-1019 cm-3 despite their high resistivity. The saturation of doping at about 1.4 × 1019 cm-3 and the low doping efficiency less than 5% are observed and discussed. The calculated effective mobility is in the order of 10-3 cm2/V s, indicating strong impurity/defect scattering effect that hinders carriers transport.

  16. Determination of active doping in highly resistive boron doped silicon nanocrystals embedded in SiO{sub 2} by capacitance voltage measurement on inverted metal oxide semiconductor structure

    SciTech Connect

    Zhang, Tian Puthen-Veettil, Binesh; Wu, Lingfeng; Jia, Xuguang; Lin, Ziyun; Yang, Terry Chien-Jen; Conibeer, Gavin; Perez-Wurfl, Ivan

    2015-10-21

    We investigate the Capacitance-Voltage (CV) measurement to study the electrically active boron doping in Si nanocrystals (ncSi) embedded in SiO{sub 2}. The ncSi thin films with high resistivity (200–400 Ω cm) can be measured by using an inverted metal oxide semiconductor (MOS) structure (Al/ncSi (B)/SiO{sub 2}/Si). This device structure eliminates the complications from the effects of lateral current flow and the high sheet resistance in standard lateral MOS structures. The characteristic MOS CV curves observed are consistent with the effective p-type doping. The CV modeling method is presented and used to evaluate the electrically active doping concentration. We find that the highly boron doped ncSi films have electrically active doping of 10{sup 18}–10{sup 19 }cm{sup −3} despite their high resistivity. The saturation of doping at about 1.4 × 10{sup 19 }cm{sup −3} and the low doping efficiency less than 5% are observed and discussed. The calculated effective mobility is in the order of 10{sup −3} cm{sup 2}/V s, indicating strong impurity/defect scattering effect that hinders carriers transport.

  17. Investigation on cubic boron nitride crystals doped with Si by high temperature thermal diffusion

    NASA Astrophysics Data System (ADS)

    Li, Xinlu; Feng, Shuang; Liu, Xiuhuan; Hou, Lixin; Gao, Yanjun; Wang, Qi; Liu, Nian; Zhang, Hai; Chen, Zhanguo; Zheng, Jie; Jia, Gang

    2014-07-01

    The method of high temperature thermal diffusion was successfully applied for doping Si impurities into cubic boron nitride (cBN) crystals. X-ray photoelectron spectra (XPS) and the current-voltage (I-V) characteristics at different temperatures were respectively used for analyzing the chemical states and the activation energy of Si impurity in cBN. According to the XPS results, Si impurities mainly replace B atoms bonding with the adjacent N atoms and become donors in cBN. Without surface cleaning, there are a lot of C and O contaminations on the surface of cBN, so a small quantity of C-Si and Si-N-O bonds also exist at the surface of cBN. Most Si impurities distribute in the shallow layer underneath the surface of cBN. Based on the electric measurement, Si impurities in cBN usually have the activation energy beyond 0.4 eV, and they can only be slightly ionized at room temperature, therefore the resistivity of Si-doped cBN is still high, and the space charge limited current becomes the main conductive mechanism in cBN. However, the conductivity of Si-doped cBN can rapidly increase with the temperature. In addition, the activation energy and the concentration of Si impurity in cBN can be affected by the temperature and the time of thermal diffusion, which needs to be verified further.

  18. Electronic and physico-chemical properties of nanometric boron delta-doped diamond structures

    SciTech Connect

    Chicot, G. Fiori, A.; Tran Thi, T. N.; Bousquet, J.; Delahaye, J.; Grenet, T.; Eon, D.; Omnès, F.; Bustarret, E.; Volpe, P. N.; Tranchant, N.; Mer-Calfati, C.; Arnault, J. C.; Gerbedoen, J. C.; Soltani, A.; De Jaeger, J. C.; Alegre, M. P.; Piñero, J. C.; Araújo, D.; Jomard, F.; and others

    2014-08-28

    Heavily boron doped diamond epilayers with thicknesses ranging from 40 to less than 2 nm and buried between nominally undoped thicker layers have been grown in two different reactors. Two types of [100]-oriented single crystal diamond substrates were used after being characterized by X-ray white beam topography. The chemical composition and thickness of these so-called delta-doped structures have been studied by secondary ion mass spectrometry, transmission electron microscopy, and spectroscopic ellipsometry. Temperature-dependent Hall effect and four probe resistivity measurements have been performed on mesa-patterned Hall bars. The temperature dependence of the hole sheet carrier density and mobility has been investigated over a broad temperature range (6 K < T < 450 K). Depending on the sample, metallic or non-metallic behavior was observed. A hopping conduction mechanism with an anomalous hopping exponent was detected in the non-metallic samples. All metallic delta-doped layers exhibited the same mobility value, around 3.6 ± 0.8 cm{sup 2}/Vs, independently of the layer thickness and the substrate type. Comparison with previously published data and theoretical calculations showed that scattering by ionized impurities explained only partially this low common value. None of the delta-layers showed any sign of confinement-induced mobility enhancement, even for thicknesses lower than 2 nm.

  19. Boron-doped, carbon-coated SnO2/graphene nanosheets for enhanced lithium storage.

    PubMed

    Liu, Yuxin; Liu, Ping; Wu, Dongqing; Huang, Yanshan; Tang, Yanping; Su, Yuezeng; Zhang, Fan; Feng, Xinliang

    2015-03-27

    Heteroatom doping is an effective method to adjust the electrochemical behavior of carbonaceous materials. In this work, boron-doped, carbon-coated SnO2 /graphene hybrids (BCTGs) were fabricated by hydrothermal carbonization of sucrose in the presence of SnO2/graphene nanosheets and phenylboronic acid or boric acid as dopant source and subsequent thermal treatment. Owing to their unique 2D core-shell architecture and B-doped carbon shells, BCTGs have enhanced conductivity and extra active sites for lithium storage. With phenylboronic acid as B source, the resulting hybrid shows outstanding electrochemical performance as the anode in lithium-ion batteries with a highly stable capacity of 1165 mA h g(-1) at 0.1 A g(-1) after 360 cycles and an excellent rate capability of 600 mA h g(-1) at 3.2 A g(-1), and thus outperforms most of the previously reported SnO2-based anode materials. PMID:25694249

  20. Evaluation of freestanding boron-doped diamond grown by chemical vapour deposition as substrates for vertical power electronic devices

    NASA Astrophysics Data System (ADS)

    Issaoui, R.; Achard, J.; Tallaire, A.; Silva, F.; Gicquel, A.; Bisaro, R.; Servet, B.; Garry, G.; Barjon, J.

    2012-03-01

    In this study, 4 × 4 mm2 freestanding boron-doped diamond single crystals with thickness up to 260 μm have been fabricated by plasma assisted chemical vapour deposition. The boron concentrations measured by secondary ion mass spectroscopy were 1018 to 1020 cm-3 which is in a good agreement with the values calculated from Fourier transform infrared spectroscopy analysis, thus indicating that almost all incorporated boron is electrically active. The dependence of lattice parameters and crystal mosaicity on boron concentrations have also been extracted from high resolution x-ray diffraction experiments on (004) planes. The widths of x-ray rocking curves have globally shown the high quality of the material despite a substantial broadening of the peak, indicating a decrease of structural quality with increasing boron doping levels. Finally, the suitability of these crystals for the development of vertical power electronic devices has been confirmed by four-point probe measurements from which electrical resistivities as low as 0.26 Ω cm have been obtained.

  1. Decomposition of nitrous oxide on Fe-doped boron nitride nanotubes: the ligand effect.

    PubMed

    Injan, Natcha; Sirijaraensre, Jakkapan; Limtrakul, Jumras

    2014-11-14

    N2O decomposition on iron-doped boron nitride nanotubes (Fe-BNNTs) was investigated by means of the density functional theory (M06-L). Two different forms of Fe-BNNTs, which are substitutions of the Fe atom into the boron-vacancy and nitrogen-vacancy sites of BNNTs, were used as the catalyst. Influence of the support plays a crucial role in the electronic configuration and catalytic reactivity of the iron atom. With the nitrogen surrounding (Fe(B)-BNNT), the iron behaves as a Lewis acid for accepting an electron from the lone-pair orbital of the N2O oxygen atom (η(1)-O complex). The catalytic process over this one at the transition state involves a synergistic σ-donation from the HOMO of N2O into a LUMO of the catalyst and the π-back-bonding from the metal d orbital into the π* orbital of N2O, leading to the cleavage of the N-O bond. The activation for this step is 22.5 kcal mol(-1). With the boron surrounding (Fe(N)-BNNT), the iron acting as a Lewis base plays a different role as compared with the iron in the case of Fe(B)-BNNTs. The HOMO of Fe(N)-BNNTs promotes the side-on binding mode of N2O on the iron center (η(2)-O,N complex), leading to the weakening of the N-O bond at the adsorption state. As a result, the decomposition over the Fe(N)-BNNTs takes place easily without an energy barrier. PMID:25254314

  2. Electron spin-polarization and spin lattices in the boron- and nitrogen-doped organic framework COF-5.

    PubMed

    Liu, Xiaobiao; Tan, Jie; Wang, Aizhu; Zhang, Xiaoming; Zhao, Mingwen

    2014-11-14

    Covalent organic frameworks (COFs) hold great promise in several applications, such as sieves, catalytic supports and gas storage because of their unique structures and electronic properties. However, most of these metal-free COFs are nonmagnetic and cannot be directly used in spintronics. Here, based on first-principles calculations, we predict that substitutional doping of COF-5 with nitrogen and boron atoms can modify the electronic structures, inducing stable electron spin-polarization in the framework. The preferability of the different doping sites is checked. The electronic structures of the doped COF-5 are dependent on the doping sites and doping atoms, which offer high degrees of freedom to tune the electronic properties. Kagome lattices of S = 1/2 spins can be achieved in the COF-5, suggesting a promising candidate for spin-liquid materials. PMID:25255699

  3. Optically detected cyclotron resonance in heavily boron-doped silicon nanostructures on n-Si (100)

    SciTech Connect

    Bagraev, N. T. Kuzmin, R. V.; Gurin, A. S.; Klyachkin, L. E.; Malyarenko, A. M.; Mashkov, V. A.

    2014-12-15

    Electron and hole cyclotron resonance at a frequency of 94 GHz is detected by a change in the intensity of photoluminescence lines whose positions are identical to those of dislocation luminescence lines D1 and D2 in single-crystal silicon and in heavily boron-doped silicon nanostructures on the Si (100) surface. The angular dependence of the spectrum of the optically detected cyclotron resonance corresponds to the tensor of the electron and hole effective mass in single-crystal silicon, and the resonance-line width indicates long carrier free-path times close to 100 ps. The results obtained are discussed within the framework of the interrelation of the electron-vibration coupling to charge and spin correlations in quasi-one-dimensional chains of dangling bonds in silicon.

  4. Pulsed-laser crystallized highly conductive boron-doped microcrystalline silicon

    SciTech Connect

    Nebel, C.E.; Dahlheimer, B.; Karrer, U.; Stutzmann, M.

    1997-07-01

    The preparation of seed lattices, using three interfering beams (TIB) from a pulsed Nd:YAG laser in a-Si layers of 100 to 400 nm thickness is introduced and applied for seeded laser or thermally induced crystallization of a-Si on Corning 7059 glass. The structural and electronic properties of the {micro}c-Si layers are investigated by X-ray, electron- and atomic force microscopy, Hall and conductivity measurements. In highly boron-doped {micro}c-Si, grains up to 1.3 {micro}m in diameter are detected, giving rise to conductivities of {approx}2,000 S/cm and hole mobilities of {approx}10 cm{sup 2}/Vs.

  5. Excitonic luminescence of SiGe/Si quantum wells δ-doped with boron

    SciTech Connect

    Bagaev, V. S.; Nikolaev, S. N.; Onishchenko, E. E.; Pruchkina, A. A.; Krivobok, V. S.; Novikov, A. V.

    2015-05-14

    Low-temperature photoluminescence of undoped and moderately δ-doped Si{sub 1−x}Ge{sub x}/Si (x < 0.1) quantum wells has been studied. The influence of boron δ-layer on the excitonic luminescence and the luminescence caused by a dense electron plasma was demonstrated. The conditions under which the luminescence spectra of quantum wells are dominated by impurity-bound excitons (BE) have been established. Some unusual properties of these BE are explained in terms of type II band-offset in Si{sub 1−x}Ge{sub x}/Si (x < 0.1) quantum wells, which favors a spatial separation of electrons and holes. It is shown that the temperature dependence of an excitonic emission in the quantum wells allows to calculate the BE-related density of states and, thus, can be used for contactless estimation of the impurity concentration in quantum wells.

  6. Relaxation of the resistive superconducting state in boron-doped diamond films

    NASA Astrophysics Data System (ADS)

    Kardakova, A.; Shishkin, A.; Semenov, A.; Goltsman, G. N.; Ryabchun, S.; Klapwijk, T. M.; Bousquet, J.; Eon, D.; Sacépé, B.; Klein, Th.; Bustarret, E.

    2016-02-01

    We report a study of the relaxation time of the restoration of the resistive superconducting state in single crystalline boron-doped diamond using amplitude-modulated absorption of (sub-)THz radiation (AMAR). The films grown on an insulating diamond substrate have a low carrier density of about 2.5 ×1021cm-3 and a critical temperature of about 2 K . By changing the modulation frequency we find a high-frequency rolloff which we associate with the characteristic time of energy relaxation between the electron and the phonon systems or the relaxation time for nonequilibrium superconductivity. Our main result is that the electron-phonon scattering time varies clearly as T-2, over the accessible temperature range of 1.7 to 2.2 K. In addition, we find, upon approaching the critical temperature Tc, evidence for an increasing relaxation time on both sides of Tc.

  7. Boron-Doped Nanocrystalline Diamond Electrodes for Neural Interfaces: In vivo Biocompatibility Evaluation

    PubMed Central

    Alcaide, María; Taylor, Andrew; Fjorback, Morten; Zachar, Vladimir; Pennisi, Cristian P.

    2016-01-01

    Boron-doped nanocrystalline diamond (BDD) electrodes have recently attracted attention as materials for neural electrodes due to their superior physical and electrochemical properties, however their biocompatibility remains largely unexplored. In this work, we aim to investigate the in vivo biocompatibility of BDD electrodes in relation to conventional titanium nitride (TiN) electrodes using a rat subcutaneous implantation model. High quality BDD films were synthesized on electrodes intended for use as an implantable neurostimulation device. After implantation for 2 and 4 weeks, tissue sections adjacent to the electrodes were obtained for histological analysis. Both types of implants were contained in a thin fibrous encapsulation layer, the thickness of which decreased with time. Although the level of neovascularization around the implants was similar, BDD electrodes elicited significantly thinner fibrous capsules and a milder inflammatory reaction at both time points. These results suggest that BDD films may constitute an appropriate material to support stable performance of implantable neural electrodes over time. PMID:27013949

  8. Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis.

    PubMed

    Gan, Patrick; Foord, John S; Compton, Richard G

    2015-10-01

    Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur. PMID:26491640

  9. Boron-Doped Nanocrystalline Diamond Electrodes for Neural Interfaces: In vivo Biocompatibility Evaluation.

    PubMed

    Alcaide, María; Taylor, Andrew; Fjorback, Morten; Zachar, Vladimir; Pennisi, Cristian P

    2016-01-01

    Boron-doped nanocrystalline diamond (BDD) electrodes have recently attracted attention as materials for neural electrodes due to their superior physical and electrochemical properties, however their biocompatibility remains largely unexplored. In this work, we aim to investigate the in vivo biocompatibility of BDD electrodes in relation to conventional titanium nitride (TiN) electrodes using a rat subcutaneous implantation model. High quality BDD films were synthesized on electrodes intended for use as an implantable neurostimulation device. After implantation for 2 and 4 weeks, tissue sections adjacent to the electrodes were obtained for histological analysis. Both types of implants were contained in a thin fibrous encapsulation layer, the thickness of which decreased with time. Although the level of neovascularization around the implants was similar, BDD electrodes elicited significantly thinner fibrous capsules and a milder inflammatory reaction at both time points. These results suggest that BDD films may constitute an appropriate material to support stable performance of implantable neural electrodes over time. PMID:27013949

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

    PubMed

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

    2011-04-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

    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.

  12. Chemical Modification of Boron-Doped Diamond Electrodes for Applications to Biosensors and Biosensing.

    PubMed

    Svítková, Jana; Ignat, Teodora; Švorc, Ľubomír; Labuda, Ján; Barek, Jiří

    2016-05-01

    Boron-doped diamond (BDD) is a prospective electrode material that possesses many exceptional properties including wide potential window, low noise, low and stable background current, chemical and mechanical stability, good biocompatibility, and last but not least exceptional resistance to passivation. These characteristics extend its usability in various areas of electrochemistry as evidenced by increasing number of published articles over the past two decades. The idea of chemically modifying BDD electrodes with molecular species attached to the surface for the purpose of creating a rational design has found promising applications in the past few years. BDD electrodes have appeared to be excellent substrate materials for various chemical modifications and subsequent application to biosensors and biosensing. Hence, this article presents modification strategies that have extended applications of BDD electrodes in electroanalytical chemistry. Different methods and steps of surface modification of this electrode material for biosensing and construction of biosensors are discussed. PMID:26337147

  13. Grain-boundary contamination and ductility loss in boron-doped Ni3Al

    NASA Astrophysics Data System (ADS)

    Takeyama, M.; Liu, C. T.

    1989-10-01

    The effect of heat treatment on ductility loss in a boron-doped Ni3Al was studied by tensile tests of alloy specimens exposed to contaminated environments. Specimens heat-treated extensively in evacuated quartz capsules at 1323 K exhibit only 3.3 pct ductility at 1033 K, whereas a previous study reported a tensile ductility of about 24 pet for specimens heat-treated in a high vacuum system. Aluminum oxide and silicon-contaminated regions were observed at and near external surfaces of capsule-annealed specimens. The reactions occurring during heat treatment are interpreted in terms of thermodynamics. An Auger electron spectroscopy study revealed oxygen penetration along grain boundaries during capsule annealing. Although the surface oxide layer and silicon contamination both contribute to some reductions in ductility, the major cause for embrittlement comes from oxygen penetration along grain boundaries.

  14. Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis

    PubMed Central

    Gan, Patrick; Foord, John S; Compton, Richard G

    2015-01-01

    Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur. PMID:26491640

  15. Theoretical study of intermolecular interactions in nanoporous networks on boron doped silicon surface

    NASA Astrophysics Data System (ADS)

    Boukari, Khaoula; Duverger, Eric; Hanf, Marie-Christine; Stephan, Régis; Sonnet, Philippe

    2014-11-01

    Supramolecular networks on a doped boron silicon surface under ultra high vacuum (UHV) have been recently obtained (Makoudi et al., 2013). The used molecule contains different end-groups, bearing either bromine, iodine or hydrogen atoms denoted 1,3,5-tri(4‧-bromophenyl)benzene (TBB), 1,3,5-tri(4-iodophenyl)benzene (TIB) and 1,3,5-triphenyl-benzene (THB). To explain the formation of the nanoporous structures, interactions of the type aryl-X⋯H hydrogen bonds (X being a halogen atom) have been proposed. In order to obtain a complete insight of the stabilizing interaction in these networks adsorbed on the Si(1 1 1)√3x√3R30°-boron surface, we present a full density-functional-theory study taking the van der Waals interactions into account. We investigated the energetic and structural properties of three different nanoporous networks constituted by TBB, TIB and THB molecules. The electronic studies allow us to identify hydrogen bond and dipole-dipole intermolecular interactions in the supramolecular halogen networks, whereas only dipole-dipole interactions are present in the 1,3,5-triphenyl-benzene nanoporous network.

  16. Semiconducting properties of zinc-doped cubic boron nitride thin films

    SciTech Connect

    Nose, K.; Yoshida, T.

    2007-09-15

    We have examined the electronic properties of zinc-doped cubic boron nitride (cBN) thin films prepared by sputter deposition. The electric conductivity of films deposited in pure Ar increased as the concentration of zinc dopant increased, and hole conduction was identified by the measurement of thermoelectric currents. It was also found that the conductivity increment in such films was accompanied by a linear increase in the B/(B+N) ratio. At the same time, no modification of the composition and the conductivity by incorporated zinc was observed when film growth took place in presence of nitrogen gas. The effect of the excess boron on the conductivity emerged only when films show semi-insulating behavior. These results suggest that Zn substitution for nitrogen causes high electric conductivity of cBN. The electric contact between Ti electrode and semiconducting cBN was examined by the transfer length method, and Ohmic conduction was observed in the Ti/cBN contact. The specific contact resistance was affected by the specific resistance of cBN films, and it was reduced from 10{sup 5} to 100 {omega} cm{sup 2} by increasing the concentration of incorporated Zn.

  17. Cathodoluminescence measurements on heavily boron doped homoepitaxial diamond films and their interfaces with their Ib substrates

    NASA Astrophysics Data System (ADS)

    Baron, C.; Deneuville, A.; Wade, M.; Jomard, F.; Chevallier, J.

    2006-02-01

    Heavily boron doped 1.8 to 2.4 μm thick homoepitaxial diamond films with 1.5 × 1021 cm-3 [B] 1.75 × 1021 cm-3 have been deposited directly on their (100) Ib substrates at 830 °C. Their cathodoluminescence spectra probe the controlled thicknesses from 0.28 to 2.8 μm, therefore the bulk of the films as well as their interfaces with their substrates. The bulk of these films exhibit a band with shoulders ascribed to BETO (5.036 eV), FETO (5.094 eV) and BENP (5.184 eV) excitons whose energies are downward shifted by about 180 meV in comparison with monocrystalline diamond with low [B] < 5 × 1018 cm-3. This large shift allows the appearance of narrow peaks around 5.216, 5.271 and 5.357 eV ascribed to BETO, FETO and BENP from interfacial layers with low [B]. From their BETO to FETO ratio, their concentration of boron on isolated substitutional sites is significantly lower than their total low [B] content measured by SIMS. A tentative model is proposed to explain the characteristics of these 40 to 160 quasihomogeneous interfacial layers.

  18. Synthesis and characterization of aluminum–boron co-doped ZnO nanostructures

    SciTech Connect

    Kumar, Vinod; Singh, R.G.; Singh, Neetu; Kapoor, Avinashi; Mehra, R.M.; Purohit, L.P.

    2013-02-15

    Graphical abstract: In this paper, we have reported the development of aluminum boron co-doped ZnO (AZB) nanostructures deposited by sol–gel method using spin coating technique. The structure of AZB nanostructure films has been found to exhibit the hexagonal wurtzite structure. The shape of nanostructures has been changed from seed structure to tetra-pods, tetra-pods to nanorods and finally nanorods to nanofiber with variation in Al concentration. The structural, electrical and optical properties of AZB nanostructures are tuned with shape and size of the nanostructures. The effect of Al concentration on the resistivity (ρ), carrier concentration (n) and mobility (μ) of nanostructure films is shown in graph below. A minimum resistivity of 6.8 × 10{sup −4} Ω cm is obtained in AZB films at doping concentration of B 0.6 at.% and Al 0.4 at.% with a sheet resistance of 24 Ω/□ and transmittance of ∼88% for nanorods structure. These nanostructures could be applicable for a various nano-regime devices such as photovolatics, gas sensing and field emission device. Display Omitted Highlights: ► Synthesis of Al and B co-doped ZnO (AZB) nanostructures. ► Minimum resistivity (ρ) of 6.8 × 10{sup −4} Ω cm in AZB films. ► Minimum sheet resistance (R{sub s}) 24 Ω/□ in nanorods (NRs). ► Maximum transmittance ∼88% in NRs. ► Application in nano-electronic devices. -- Abstract: In this paper, we have reported the development of aluminum boron co-doped ZnO (AZB) nanostructures deposited by sol–gel method using spin coating technique. The structure of AZB nanostructure films has been found to exhibit the hexagonal wurtzite structure. The shape of AZB nanostructures has changed from seed structure to tetra-pods, tetra-pods to nanorods and finally to nanofibers with increase in aluminum concentration. The structural, electrical and optical properties of AZB films are tuned with shape and size of the nanostructures. These AZB nanostructures could be

  19. Batch fabrication of mesoporous boron-doped nickel oxide nanoflowers for electrochemical capacitors

    SciTech Connect

    Yang, Jing-He; Yu, Qingtao; Li, Yamin; Mao, Liqun; Ma, Ding

    2014-11-15

    Highlights: • A new facile liquid-phase method has been employed for synthesis boron-doped NiO nanoflowers. • The specific surface area of NiO is as high as 200 m{sup 2} g{sup −1}. • NiO nanoflowers exhibit a high specific capacitance of ∼1309 F g{sup −1} at a charge and discharge current density of 3 A g{sup −1}. • NiO nanoflowers have excellent cycling ability and even after 2500 cycles there is no significant reduction in specific capacitance. - Abstract: Boron-doped nickel oxide (B-NiO) nanoflowers are prepared by simple thermal decomposition of nickel hydroxide. B-NiO is porous sphere with a diameter of about 400 nm. B-NiO nanoflowers are composed of approximately 30 nm nanoplates and the thickness of the nanosheets is approximately 3 nm. The specific surface area of the material is as high as 200 m{sup 2} g{sup −1} and the pore size distribution curves of B-NiO has three typical peaks in the range of mesoporous (5 nm, 13 nm and 18 nm). As an electrode for supercapacitors, the crystalline B-NiO nanoflowers have favorable characteristics, for instance, a specific capacitance of 1309 F g{sup −1} at a current density of 3 A g{sup −1} and no significant reduction in Coulombic efficiency after 2500 cycles at 37.5 A g{sup −1}. This remarkable electrochemical performance will make B-NiO nanoflowers a promising electrode material for high performance supercapacitors.

  20. Boron-silicon solid solution: synthesis and crystal structure of a carbon-doped boron-rich SiB{sub n} (n{approx}30) compound

    SciTech Connect

    Roger, Jerome; Babizhetskyy, Volodymyr; Halet, Jean-Francois; Guerin, Roland . E-mail: roland.guerin@univ-rennes1.fr

    2004-11-01

    The carbon-doped SiB{sub 3}{approx}{sub 30} compound was obtained during attempts to synthesize by arc-melting boron-rich binaries belonging to the SiB{sub n} solid solution (13n<32). Its crystal structure was determined from X-ray single-crystal intensity data (R-3m, Z=1, a=11.0152(3)A, and c=23.8625(8)A) and led to the final formula SiB{sub {approx}}{sub 30}C{sub 0.35}. Carbon is incorporated fortuitously in the structure. The boron framework of these phases slightly differs from that encountered in {beta}-boron. The salient characteristic is the partial occupancy of three interstitial boron sites by silicon and one by carbon atoms. This is in contrast with the structurally related compounds such as SiB{sub {approx}}{sub 36}, CrB{sub {approx}}{sub 41}, or FeB{sub {approx}}{sub 40}, in which only two interstitial sites are partially occupied.

  1. Synergistic effect on the visible light activity of Ti3+ doped TiO2 nanorods/boron doped graphene composite

    PubMed Central

    Xing, Mingyang; Li, Xiao; Zhang, Jinlong

    2014-01-01

    TiO2/graphene (TiO2-x/GR) composites, which are Ti3+ self-doped TiO2 nanorods decorated on boron doped graphene sheets, were synthesized via a simple one-step hydrothermal method using low-cost NaBH4 as both a reducing agent and a boron dopant on graphene. The resulting TiO2 nanorods were about 200 nm in length with exposed (100) and (010) facets. The samples were characterized by X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy, X-band electron paramagnetic resonance (EPR), X-ray photoelectron spectra (XPS), transmission electron microscope (TEM), Raman, and Fourier-transform infrared spectroscopy (FTIR). The XRD results suggest that the prepared samples have an anatase crystalline structure. All of the composites tested exhibited improved photocatalytic activities as measured by the degradation of methylene blue and phenol under visible light irradiation. This improvement was attributed to the synergistic effect of Ti3+ self-doping on TiO2 nanorods and boron doping on graphene. PMID:24974890

  2. Nitrogen-doped porous graphitic carbon as an excellent electrode material for advanced supercapacitors.

    PubMed

    Sun, Li; Tian, Chungui; Fu, Yu; Yang, Ying; Yin, Jie; Wang, Lei; Fu, Honggang

    2014-01-01

    An advanced supercapacitor material based on nitrogen-doped porous graphitic carbon (NPGC) with high a surface area was synthesized by means of a simple coordination-pyrolysis combination process, in which tetraethyl orthosilicate (TEOS), nickel nitrate, and glucose were adopted as porogent, graphitic catalyst precursor, and carbon source, respectively. In addition, melamine was selected as a nitrogen source owing to its nitrogen-enriched structure and the strong interaction between the amine groups and the glucose unit. A low-temperature treatment resulted in the formation of a NPGC precursor by combination of the catalytic precursor, hydrolyzed TEOS, and the melamine-glucose unit. Following pyrolysis and removal of the catalyst and porogent, the NPGC material showed excellent electrical conductivity owing to its high crystallinity, a large Brunauer-Emmett-Teller surface area (SBET =1027 m(2)  g(-1) ), and a high nitrogen level (7.72 wt %). The unusual microstructure of NPGC materials could provide electrochemical energy storage. The NPGC material, without the need for any conductive additives, showed excellent capacitive behavior (293 F g(-1) at 1 A g(-1) ), long-term cycling stability, and high coulombic efficiency (>99.9 % over 5000 cycles) in KOH when used as an electrode. Notably, in a two-electrode symmetric supercapacitor, NPGC energy densities as high as 8.1 and 47.5 Wh kg(-1) , at a high power density (10.5 kW kg(-1) ), were achieved in 6 M KOH and 1 M Et4 NBF4 -PC electrolytes, respectively. Thus, the synthesized NPGC material could be a highly promising electrode material for advanced supercapacitors and other conversion devices. PMID:24307432

  3. Removal of azo dye by a highly graphitized and heteroatom doped carbon derived from fish waste: Adsorption equilibrium and kinetics.

    PubMed

    Liu, Zhengang; Zhang, Fang; Liu, Tingting; Peng, Nana; Gai, Chao

    2016-11-01

    A highly graphitized and heteroatom doped porous carbon was prepared from fish waste in the present study. The morphology and chemical composition of the resultant porous carbon were characterized by SEM-EDS, TEM, BET, XRD and Raman measurement. The prepared porous carbon was employed as an adsorbent for acid orange 7, a typical azo dye, removal from aqueous solution. The results showed that the porous carbon had ultrahigh surface area of 2146 m(2)/g, a high degree of graphitization structure and naturally doped with nitrogen and phosphorous. The maximum adsorption capacity of acid orange 7 reached 285.71 mg/g due to unique property of the prepared porous carbon. In addition, acid orange 7 adsorption onto the porous carbon well followed pseudo-second-order kinetics model and acid orange 7 diffusion in micropores was the potential rate controlling step. PMID:27526082

  4. Resistance to protein adsorption and adhesion of fibroblasts on nanocrystalline diamond films: the role of topography and boron doping.

    PubMed

    Alcaide, María; Papaioannou, Stavros; Taylor, Andrew; Fekete, Ladislav; Gurevich, Leonid; Zachar, Vladimir; Pennisi, Cristian Pablo

    2016-05-01

    Boron-doped nanocrystalline diamond (BNCD) films exhibit outstanding electrochemical properties that make them very attractive for the fabrication of electrodes for novel neural interfaces and prosthetics. In these devices, the physicochemical properties of the electrode materials are critical to ensure an efficient long-term performance. The aim of this study was to investigate the relative contribution of topography and doping to the biological performance of BNCD films. For this purpose, undoped and boron-doped NCD films were deposited on low roughness (LR) and high roughness (HR) substrates, which were studied in vitro by means of protein adsorption and fibroblast growth assays. Our results show that BNCD films significantly reduce the adsorption of serum proteins, mostly on the LR substrates. As compared to fibroblasts cultured on LR BNCD films, cells grown on the HR BNCD films showed significantly reduced adhesion and lower growth rates. The mean length of fibronectin fibrils deposited by the cells was significantly increased in the BNCD coated substrates, mainly in the LR surfaces. Overall, the largest influence on protein adsorption, cell adhesion, proliferation, and fibronectin deposition was due to the underlying sub-micron topography, with little or no influence of boron doping. In perspective, BNCD films displaying surface roughness in the submicron range may be used as a strategy to reduce the fibroblast growth on the surface of neural electrodes. PMID:26975747

  5. The Effect of Boron Doping on Structure and Electrochemical Performance of Lithium-Rich Layered Oxide Materials.

    PubMed

    Liu, Jiatu; Wang, Shuangbao; Ding, Zhengping; Zhou, Ruiqi; Xia, Qingbing; Zhang, Jinfang; Chen, Libao; Wei, Weifeng; Wang, Peng

    2016-07-20

    Polyanion doping shows great potential to improve electrochemical performance of Li-rich layered oxide (LLO) materials. Here, by optimizing the doping content and annealing temperature, we obtained boron-doped LLO materials Li1.2Mn0.54Ni0.13Co0.13BxO2 (x = 0.04 and 0.06) with comprehensively improved performance (94% capacity retention after 100 cycles at 60 mA/g current density and a rate capability much higher compared to that of the pristine sample) at annealing temperatures of 750 and 650 °C, respectively, which are much lower than the traditional annealing temperature of similar material systems without boron. The scenario of the complex crystallization process was captured using Cs-corrected high-angle annular dark field scanning transmission electron microscopic (HAADF-STEM) imaging techniques. The existence of layered, NiO-type, and spinel-like structures in a single particle induced by boron doping and optimization of annealing temperature is believed to contribute to the remarkable improvement of cycling stability and rate capability. PMID:27337243

  6. TiO 2 nanopowders doped with boron and nitrogen for photocatalytic applications

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

    TiO 2-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 TiO 2 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 N 2 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 TiO 2 systems. Nevertheless, while our surface N-doping does not appreciably modify the titania structure and texture, B incorporation inhibits the TiO 2 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.

  7. Self- and dopant diffusion in extrinsic boron doped isotopically controlled silicon multilayer structures

    SciTech Connect

    Sharp, Ian D.; Bracht, Hartmut A.; Silvestri, Hughes H.; Nicols, Samuel P.; Beeman, Jeffrey W.; Hansen, John L.; Nylandsted Larsen, Arne; Haller, Eugene E.

    2002-04-01

    Isotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. {sup 30}Si was used as a tracer through a multilayer structure of alternating natural Si and enriched {sup 28}Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850 C and 1100 C. A specially designed ion- implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self- and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

  8. Doping, strain engineering, and interlayer interaction in bilayer hexagonal boron nitride sheets

    NASA Astrophysics Data System (ADS)

    Saito, Susumu; Fujimoto, Yoshitaka

    We study electronic properties of bilayer hexagonal boron nitride (h-BN) sheets with different stacking sequences in the framework of the density-functional theory. The bulk h-BN material usually takes the so-called AA (or AA') stacking, corresponding to the ''non-polar'' bilayer h-BN sheet. On the other hand, the rhombohedral BN takes the ABC stacking, and the corresponding bilayer sheet has ''upper'' and ''lower'' layers which are not equivalent with each other. Interestingly, the energetics of stacking sequences for bilayer h-BN sheets is found to be different from that for bulk h-BN materials. We report that strain engineering for bilayer h-BN sheets can possess much wider possibilities than that for monolayer h-BN due to the modification of the interlayer interaction. We also study the substitutional C doping into bilayer h-BN sheets, and report the energetics and the strain effect for these C-doped sheets. Finally we discuss the similarities and differences between bilayer h-BN sheets and double-wall h-BN nanotubes. This work was partly supported by the MEXT Elements Strategy Initiative to Form Core Research Center, Grant in Aid for Scientific Research, MEXT Japan, ``Science of Atomic Layers'', and JSPS KAKENHI Grant No. 26390062.

  9. Homoepitaxial Boron Doped Diamond Anvils as Heating Elements in a Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Montgomery, Jeffrey; Samudrala, Gopi; Smith, Spencer; Tsoi, Georgiy; Vohra, Yogesh; Weir, Samuel

    2013-03-01

    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 ~ 1020/cm3) 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 lateral 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 continuing set of benchmark experiments, we use two newly created matching heater anvils with 500 μm culets to analyze the various fluorescence emission lines of ruby microspheres, which show more complicated behavior than traditional ruby chips. We also report on the temperature dependence of the high-pressure Raman modes of paracetamol (C8H9NO2) up to 20 GPa.

  10. Dibenzothiophene adsorption at boron doped carbon nanoribbons studied within density functional theory

    SciTech Connect

    López-Albarrán, P.; Navarro-Santos, P.; Garcia-Ramirez, M. A.; Ricardo-Chávez, J. L.

    2015-06-21

    The adsorption of dibenzothiophene (DBT) on bare and boron-doped armchair carbon nanoribbons (ACNRs) is being investigated in the framework of the density functional theory by implementing periodic boundary conditions that include corrections from dispersion interactions. The reactivity of the ACNRs is characterized by using the Fukui functions as well as the electrostatic potential as local descriptors. Non-covalent adsorption mechanism is found when using the local Perdew-Becke-Ernzerhof functional, regardless of the DBT orientation and adsorption location. The dispersion interactions addition is a milestone to describe the adsorption process. The charge defects introduced in small number (i.e., by doping with B atoms), within the ACNRs increases the selectivity towards sulfur mainly due to the charge depletion at B sites. The DBT magnitude in the adsorption energy shows non-covalent interactions. As a consequence, the configurations where the DBT is adsorbed on a BC{sub 3} island increase the adsorption energy compared to random B arrangements. The stability of these configurations can be explained satisfactorily in terms of dipole interactions. Nevertheless, from the charge-density difference analysis and the weak Bader charge-distribution interactions cannot be ruled out completely. This is why the electronic properties of the ribbons are analyzed in order to elucidate the key role played by the B and DBT states in the adsorbed configurations.

  11. Boron doped g-C3N4 with enhanced photocatalytic UO22+ reduction performance

    NASA Astrophysics Data System (ADS)

    Lu, Changhai; Chen, Rongyue; Wu, Xi; Fan, Meifeng; Liu, Yunhai; Le, Zhanggao; Jiang, Shujuan; Song, Shaoqing

    2016-01-01

    Tuning the band gap and absorption intensity of visible-light by element doping is an attractive strategy to enhance the photocatalytic activity of semiconductor materials. Here we doped boron into g-C3N4 to construct highly efficient photocatalysts (B-g-C3N4) for the photocatalytic reduction of UO22+. Characterization and photocatalysis tests showed the band gap of B-g-C3N4 was narrowed, and the absorption intensity of visible-light was enhanced with increasing the formed N-B-C (BCN) of B-g-C3N4, which is consistent with the trend of the photocatalytic performance of B-g-C3N4. The optimized B-g-C3N4 photocatalyst with BCN content of 1.01 at.% exhibited excellent removal efficiency of UO22+ and good photocatalytic stability. Therefore, these results may lead to a new strategy for exploring the advanced photocatalysts based on the carbon nanomaterials with abundant BCN for the photocatalytic reduction of U(VI) pollutant.

  12. Performance of Graphite Pastes Doped with Various Materials as Back Contact for CdS/CdTe Solar Cell

    NASA Astrophysics Data System (ADS)

    Hanafusa, Akira; Aramoto, Tetsuya; Morita, Akikatsu

    2001-12-01

    To date the problem of developing a suitable back contact for CdS/CdTe solar cells has yet to be resolved. The Cu-doped graphite paste that is widely used as a back contact is associated with degradation problems due to possible Cu diffusion across the CdS/CdTe junction. This study was designed to find ways to improve the graphite paste for superior electrical contacts. Mixtures of graphite paste with various material constituents and dopants consisting of silver-, lead-, nickel-, antimony-, bismuth-, or phosphor-based compounds, were studied. Results show that the performances of solar cells fabricated from these graphite pastes vary with the change in the composition. In the cases of Ag2Te and Ni2P, we studied their relationship with the solar cell characteristics with regard to dopant quantity, and furthermore in the case of Ag2Te, with regard to the sintering temperature of the graphite electrode. A fill factor (F.F.) of over 0.65 and efficiencies over 13% were obtained with Ag2Te, Ag3PO4, Ag2MoO4, and NiTe, and efficiencies over 12% were obtained with AgF, AgCl, Ni2P, and Ni3P.

  13. Binary and ternary doping of nitrogen, boron, and phosphorus into carbon for enhancing electrochemical oxygen reduction activity.

    PubMed

    Choi, Chang Hyuck; Park, Sung Hyeon; Woo, Seong Ihl

    2012-08-28

    N-doped carbon, a promising alternative to Pt catalyst for oxygen reduction reactions (ORRs) in acidic media, is modified in order to increase its catalytic activity through the additional doping of B and P at the carbon growth step. This additional doping alters the electrical, physical, and morphological properties of the carbon. The B-doping reinforces the sp(2)-structure of graphite and increases the portion of pyridinic-N sites in the carbon lattice, whereas P-doping enhances the charge delocalization of the carbon atoms and produces carbon structures with many edge sites. These electrical and physical alternations of the N-doped carbon are more favorable for the reduction of the oxygen on the carbon surface. Compared with N-doped carbon, B,N-doped or P,N-doped carbon shows 1.2 or 2.1 times higher ORR activity at 0.6 V (vs RHE) in acidic media. The most active catalyst in the reaction is the ternary-doped carbon (B,P,N-doped carbon), which records -6.0 mA/mg of mass activity at 0.6 V (vs RHE), and it is 2.3 times higher than that of the N-doped carbon. These results imply that the binary or ternary doping of B and P with N into carbon induces remarkable performance enhancements, and the charge delocalization of the carbon atoms or number of edge sites of the carbon is a significant factor in deciding the oxygen reduction activity in carbon-based catalysts. PMID:22769428

  14. Highly graphitized nitrogen-doped porous carbon nanopolyhedra derived from ZIF-8 nanocrystals as efficient electrocatalysts for oxygen reduction reactions

    NASA Astrophysics Data System (ADS)

    Zhang, Linjie; Su, Zixue; Jiang, Feilong; Yang, Lingling; Qian, Jinjie; Zhou, Youfu; Li, Wenmu; Hong, Maochun

    2014-05-01

    Nitrogen-doped graphitic porous carbons (NGPCs) have been synthesized by using a zeolite-type nanoscale metal-organic framework (NMOF) as a self-sacrificing template, which simultaneously acts as both the carbon and nitrogen sources in a facile carbonization process. The NGPCs not only retain the nanopolyhedral morphology of the parent NMOF, but also possess rich nitrogen, high surface area and hierarchical porosity with well-conducting networks. The promising potential of NGPCs as metal-free electrocatalysts for oxygen reduction reactions (ORR) in fuel cells is demonstrated. Compared with commercial Pt/C, the optimized NGPC-1000-10 (carbonized at 1000 °C for 10 h) catalyst exhibits comparable electrocatalytic activity via an efficient four-electron-dominant ORR process coupled with superior methanol tolerance as well as cycling stability in alkaline media. Furthermore, the controlled experiments reveal that the optimum activity of NGPC-1000-10 can be attributed to the synergetic contributions of the abundant active sites with high graphitic-N portion, high surface area and porosity, and the high degree of graphitization. Our findings suggest that solely MOF-derived heteroatom-doped carbon materials can be a promising alternative for Pt-based catalysts in fuel cells.Nitrogen-doped graphitic porous carbons (NGPCs) have been synthesized by using a zeolite-type nanoscale metal-organic framework (NMOF) as a self-sacrificing template, which simultaneously acts as both the carbon and nitrogen sources in a facile carbonization process. The NGPCs not only retain the nanopolyhedral morphology of the parent NMOF, but also possess rich nitrogen, high surface area and hierarchical porosity with well-conducting networks. The promising potential of NGPCs as metal-free electrocatalysts for oxygen reduction reactions (ORR) in fuel cells is demonstrated. Compared with commercial Pt/C, the optimized NGPC-1000-10 (carbonized at 1000 °C for 10 h) catalyst exhibits comparable

  15. Enhanced photocatalytic performance of boron doped Bi₂WO₆ nanosheets under simulated solar light irradiation.

    PubMed

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

    2013-06-15

    Bi₂WO6 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 Bi₂WO₆ was proved by FT-IR, Raman spectra and XPS. Doping with B could affect the pore structure and volume. 0.5% B/Bi₂WO₆ displayed more mesopores with higher total pore volume than pure Bi₂W₆; while the pores of 10% B/Bi₂WO₆ mainly distributed in microporous range with much less total pore volume. As a result, 0.5% B/Bi₂WO₆ 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/Bi₂WO₆ displayed the highest photocatalytic activity under simulated solar light with rate constant (kobs) 8.8 times of that using pure Bi₂WO₆. 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/Bi₂WO₆. PMID:23618657

  16. Elemental boron-doped p(+)-SiGe layers grown by molecular beam epitaxy for infrared detector applications

    NASA Technical Reports Server (NTRS)

    Lin, T. L.; George, T.; Jones, E. W.; Ksendzov, A.; Huberman, M. L.

    1992-01-01

    SiGe/Si heterojunction internal photoemission (HIP) detectors have been fabricated utilizing molecular beam epitaxy of p(+)-SiGe layers on p(-)-Si substrates. Elemental boron from a high-temperature effusion cell was used as the dopant source during MBE growth, and high doping concentrations have been achieved. Strong infrared absorption, mainly by free-carrier absorption, was observed for the degenerately doped SiGe layers. The use of elemental boron as the dopant source allows a low MBE growth temperature, resulting in improved crystalline quality and smooth surface morphology of the Si(0.7)Ge(0.3) layers. Nearly ideal thermionic emission dark current characteristics have been obtained. Photoresponse of the HIP detectors in the long-wavelength infrared regime has been demonstrated.

  17. Investigation of catalytic activity towards oxygen reduction reaction of Pt dispersed on boron doped graphene in acid medium.

    PubMed

    Pullamsetty, Ashok; Sundara, Ramaprabhu

    2016-10-01

    Boron doped graphene was prepared by a facile method and platinum (Pt) decoration over boron doped graphene was done in various chemical reduction methods such as sodium borohydride (NaBH4), polyol and modified polyol. X-ray diffraction analysis indicates that the synthesized catalyst particles are present in a nanocrystalline structure and transmission and scanning electron microscopy were employed to investigate the morphology and particle distribution. The electrochemical properties were investigated with the help of the rotating disk electrode (RDE) technique and cyclic voltammetry. The results show that the oxygen reduction reaction (ORR) takes place by a four-electron process. The kinetics of the ORR was evaluated using K-L and Tafel plots. The electrocatalyst obtained in modified polyol reduction method has shown the better catalytic activity compared to other two electrocatalysts. PMID:27393888

  18. A first principles study of pristine and Al-doped boron nitride nanotubes interacting with platinum-based anticancer drugs

    NASA Astrophysics Data System (ADS)

    Shakerzadeh, Ehsan; Noorizadeh, Siamak

    2014-03-01

    Interaction of cis-platin and neda-platin, two conventional platinum-based anticancer drugs, with pristine [8,8] and Al-doped [8,0] boron nitride nanotubes (BNNTs) are investigated using the density functional theory (DFT) method. The obtained results indicate that cis-platin and neda-platin weakly interact with pristine zig zag or armchair BNNTs with a little dependency on the adsorbing positions; while both cis-platin and neda-platin are preferentially adsorbed onto the Al atom of the Al-doped BNNT with considerable adsorption energies. Therefore the Al-doped-BNNT might be an efficient carrier for delivery of these drugs in nanomedicine domain. The electronic structures of the stable configurations are also investigated through both DOS and PDOS spectra. The obtained results introduce the Al-doped-BNNT as an efficient carrier for delivery of cis-platin and neda-platin in nanomedicine domain.

  19. Boron-Filled Hybrid Carbon Nanotubes

    PubMed Central

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  20. Boron-Filled Hybrid Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Patel, Rajen B.; Chou, Tsengming; Kanwal, Alokik; Apigo, David J.; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-07-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs.

  1. Boron-Filled Hybrid Carbon Nanotubes.

    PubMed

    Patel, Rajen B; Chou, Tsengming; Kanwal, Alokik; Apigo, David J; Lefebvre, Joseph; Owens, Frank; Iqbal, Zafar

    2016-01-01

    A unique nanoheterostructure, a boron-filled hybrid carbon nanotube (BHCNT), has been synthesized using a one-step chemical vapor deposition process. The BHCNTs can be considered to be a novel form of boron carbide consisting of boron doped, distorted multiwalled carbon nanotubes (MWCNTs) encapsulating boron nanowires. These MWCNTs were found to be insulating in spite of their graphitic layered outer structures. While conventional MWCNTs have great axial strength, they have weak radial compressive strength, and do not bond well to one another or to other materials. In contrast, BHCNTs are shown to be up to 31% stiffer and 233% stronger than conventional MWCNTs in radial compression and have excellent mechanical properties at elevated temperatures. The corrugated surface of BHCNTs enables them to bond easily to themselves and other materials, in contrast to carbon nanotubes (CNTs). BHCNTs can, therefore, be used to make nanocomposites, nanopaper sheets, and bundles that are stronger than those made with CNTs. PMID:27460526

  2. Boron/nitrogen co-doped helically unzipped multiwalled carbon nanotubes as efficient electrocatalyst for oxygen reduction.

    PubMed

    Zehtab Yazdi, Alireza; Fei, Huilong; Ye, Ruquan; Wang, Gunuk; Tour, James; Sundararaj, Uttandaraman

    2015-04-15

    Bamboo structured nitrogen doped multiwalled carbon nanotubes have been helically unzipped, and nitrogen doped graphene oxide nanoribbons (CNx-GONRs) with a multifaceted microstructure have been obtained. CNx-GONRs have then been codoped with nitrogen and boron by simultaneous thermal annealing in ammonia and boron oxide atmospheres, respectively. The effects of the codoping time and temperature on the concentration of the dopants and their functional groups have been extensively investigated. X-ray photoelectron spectroscopy results indicate that pyridinic and BC3 are the main nitrogen and boron functional groups, respectively, in the codoped samples. The oxygen reduction reaction (ORR) properties of the samples have been measured in an alkaline electrolyte and compared with the state-of-the-art Pt/C (20%) electrocatalyst. The results show that the nitrogen/boron codoped graphene nanoribbons with helically unzipped structures (CNx/CBx-GNRs) can compete with the Pt/C (20%) electrocatalyst in all of the key ORR properties: onset potential, exchange current density, four electron pathway selectivity, kinetic current density, and stability. The development of such graphene nanoribbon-based electrocatalyst could be a harbinger of precious metal-free carbon-based nanomaterials for ORR applications. PMID:25793636

  3. Spin-polarized electron current from carbon-doped open armchair boron nitride nanotubes: Implication for nano-spintronic devices

    NASA Astrophysics Data System (ADS)

    Zhou, Gang; Duan, Wenhui

    2007-03-01

    Spin-polarized density functional calculations show that the substitutional doping of carbon (C) atom at the mouth changes the atomic and spin configurations of open armchair boron nitride nanotubes (BNNTs). The occupied/unoccupied deep gap states are observed with the significant spin-splitting. The structures and spin-polarized properties are basically stable under the considerable electric field, which is important for practical applications. The magnetization mechanism is attributed to the interactions of s, p states between the C and its neighboring B or N atoms. Ultimately, advantageous geometrical and electronic effects mean that C-doped open armchair BNNTs would have promising applications in nano-spintronic devices.

  4. Effect of heavily doping with boron on electronic structures and optical properties of β-SiC

    NASA Astrophysics Data System (ADS)

    Feng, Gui-Ying; Fang, Xiao-Yong; Wang, Jun-Jun; Zhou, Yan; Lu, Ran; Yuan, Jie; Cao, Mao-Sheng

    2010-06-01

    The electronic structures and optical properties of heavily boron (B)-doped zinc blende silicon carbide (β-SiC) have been investigated using the plane-wave pseudo-potential method with the generalized gradient approximation (GGA) based on density functional theory. The doped models Si nBC n-1 ( n=4, 32) have been constructed by β-SiC unit cell. The calculated results show that the band gap of β-SiC transforms from indirect band gap to direct band gap with band gap shrink after carbon atom is replaced by boron atom. The dielectric constant of heavily B-doped β-SiC in low frequency is found to be remarkably larger, so it may act as a new dielectric material. Furthermore, after B doping, absorption peaks appear in the ultra-violet band (5-20 eV) and infrared band (0-2 eV). The ultra-violet absorption is similar to the undoped β-SiC. The infrared absorption would intensify with the increase of doping concentration, and absorption edge emerges redshift.

  5. Cathodic reductive coupling of methyl cinnamate on boron-doped diamond electrodes and synthesis of new neolignan-type products.

    PubMed

    Kojima, Taiki; Obata, Rika; Saito, Tsuyoshi; Einaga, Yasuaki; Nishiyama, Shigeru

    2015-01-01

    The electroreduction reaction of methyl cinnamate on a boron-doped diamond (BDD) electrode was investigated. The hydrodimer, dimethyl 3,4-diphenylhexanedioate (racemate/meso = 74:26), was obtained in 85% yield as the major product, along with small amounts of cyclic methyl 5-oxo-2,3-diphenylcyclopentane-1-carboxylate. Two new neolignan-type products were synthesized from the hydrodimer. PMID:25815070

  6. Modification of birefringence properties of nanostructured silicon with a change in the level of substrate doping with boron

    SciTech Connect

    Piskunov, N. A. Zabotnov, S. V.; Mamichev, D. A.; Golovan', L. A.; Timoshenko, V. Yu.; Kashkarov, P. K.

    2007-07-15

    Birefringence of porous-silicon films prepared by electrochemical etching of boron-doped Si(110) wafers with a resistivity of 25-45 m{theta} cm has been studied. The samples are found to exhibit the properties of a negative uniaxial crystal with the optical axis oriented along the [11-bar0] crystallographic direction. The possibility of using porous-silicon films as phase plates for light-polarization control in the near and mid-IR ranges is demonstrated.

  7. Kinetics and mechanism of the deep electrochemical oxidation of sodium diclofenac on a boron-doped diamond electrode

    NASA Astrophysics Data System (ADS)

    Vedenyapina, M. D.; Borisova, D. A.; Rosenwinkel, K.-H.; Weichgrebe, D.; Stopp, P.; Vedenyapin, A. A.

    2013-08-01

    The kinetics and mechanism of the deep oxidation of sodium diclofenac on a boron-doped diamond electrode are studied to develop a technique for purifying wastewater from pharmaceutical products. The products of sodium diclofenac electrolysis are analyzed using cyclic voltammetry and nuclear magnetic resonance techniques. It is shown that the toxicity of the drug and products of its electrolysis decreases upon its deep oxidation.

  8. Highly selective electrosynthesis of biphenols on graphite electrodes in fluorinated media.

    PubMed

    Kirste, Axel; Hayashi, Shotaro; Schnakenburg, Gregor; Malkowsky, Itamar M; Stecker, Florian; Fischer, Andreas; Fuchigami, Toshio; Waldvogel, Siegfried R

    2011-12-01

    The direct and selective phenol coupling reaction that provides biphenols still represents a challenge in organic synthesis. The recently developed electrosynthesis on boron-doped diamond anodes with fluorinated additives was developed further to allow the application to less-expensive electrodes and fluorinated media. This advanced protocol allows the highly selective anodic phenol coupling reaction on graphite with a broad scope. PMID:22109730

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

    PubMed Central

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

    2010-01-01

    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. PMID:21617759

  10. Optical and electronic properties of SO2 molecule adsorbed on Si-doped (8, 0) boron nitride nanotube

    NASA Astrophysics Data System (ADS)

    Guo, Shuang-Shuang; Wei, Xiu-Mei; Zhang, Jian-Min; Zhu, Gang-Qiang; Guo, Wan-Jin

    2016-09-01

    The study of the optical properties of pristine BNNT, Si-doped BNNTs and SO2 molecule adsorption on Si-doped BNNTs is that, to our knowledge, few relevant research have ever been found. In this paper, the adsorption behaviors of Sulfur dioxide (SO2) molecule on Si-doped Boron nitride nanotubes (BNNTs) are investigated applying the first-principles calculations. The main contribution of this paper is that the foremost investigation for the optical properties of the pristine BNNT, Si-doped BNNTs and SO2 adsorption on Si-doped BNNTs. Additionally, the electronic properties and the structural properties are also presented. In our calculations of optical properties, the dielectric constant, the refractive index and the absorption coefficient are obtained. Comparing the pristine BNNT, our results indicate that, the blue-shifts (in the main peaks of the dielectric constant of SiB -BNNT and SO2-SiB -BNNT), and the red-shifts (in the main peaks of the refractive index of SiN -BNNT and SO2-SiN -BNNT) are appeared. Under these conditions, Si-doped BNNT and Si-doped BNNT with SO2 adsorption, the gaps are reduced both for the speculated optical band gaps and the electronic structure band gaps.

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

    PubMed

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

    2014-04-01

    Graphitic carbon nitrides are investigated for developing highly durable Pt electrocatalyst supports for polymer electrolyte fuel cells (PEFCs). Three different graphitic carbon nitride materials were synthesized with the aim to address the effect of crystallinity, porosity, and composition on the catalyst support properties: polymeric carbon nitride (gCNM), poly(triazine) imide carbon nitride (PTI/Li(+)Cl(-)), and boron-doped graphitic carbon nitride (B-gCNM). Following accelerated corrosion testing, all graphitic carbon nitride materials are found to be more electrochemically stable compared to conventional carbon black (Vulcan XC-72R) with B-gCNM support showing the best stability. For the supported catalysts, Pt/PTI-Li(+)Cl(-) catalyst exhibits better durability with only 19% electrochemical surface area (ECSA) loss versus 36% for Pt/Vulcan after 2000 scans. Superior methanol oxidation activity is observed for all graphitic carbon nitride supported Pt catalysts on the basis of the catalyst ECSA. PMID:24748912

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

    PubMed Central

    2014-01-01

    Graphitic carbon nitrides are investigated for developing highly durable Pt electrocatalyst supports for polymer electrolyte fuel cells (PEFCs). Three different graphitic carbon nitride materials were synthesized with the aim to address the effect of crystallinity, porosity, and composition on the catalyst support properties: polymeric carbon nitride (gCNM), poly(triazine) imide carbon nitride (PTI/Li+Cl–), and boron-doped graphitic carbon nitride (B-gCNM). Following accelerated corrosion testing, all graphitic carbon nitride materials are found to be more electrochemically stable compared to conventional carbon black (Vulcan XC-72R) with B-gCNM support showing the best stability. For the supported catalysts, Pt/PTI-Li+Cl– catalyst exhibits better durability with only 19% electrochemical surface area (ECSA) loss versus 36% for Pt/Vulcan after 2000 scans. Superior methanol oxidation activity is observed for all graphitic carbon nitride supported Pt catalysts on the basis of the catalyst ECSA. PMID:24748912

  13. Osmium Atoms and Os2 Molecules Move Faster on Selenium-Doped Compared to Sulfur-Doped Boronic Graphenic Surfaces.

    PubMed

    Barry, Nicolas P E; Pitto-Barry, Anaïs; Tran, Johanna; Spencer, Simon E F; Johansen, Adam M; Sanchez, Ana M; Dove, Andrew P; O'Reilly, Rachel K; Deeth, Robert J; Beanland, Richard; Sadler, Peter J

    2015-07-28

    We deposited Os atoms on S- and Se-doped boronic graphenic surfaces by electron bombardment of micelles containing 16e complexes [Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-diselenate/dithiolate)] encapsulated in a triblock copolymer. The surfaces were characterized by energy-dispersive X-ray (EDX) analysis and electron energy loss spectroscopy of energy filtered TEM (EFTEM). Os atoms moved ca. 26× faster on the B/Se surface compared to the B/S surface (233 ± 34 pm·s(-1) versus 8.9 ± 1.9 pm·s(-1)). Os atoms formed dimers with an average Os-Os distance of 0.284 ± 0.077 nm on the B/Se surface and 0.243 ± 0.059 nm on B/S, close to that in metallic Os. The Os2 molecules moved 0.83× and 0.65× more slowly than single Os atoms on B/S and B/Se surfaces, respectively, and again markedly faster (ca. 20×) on the B/Se surface (151 ± 45 pm·s(-1) versus 7.4 ± 2.8 pm·s(-1)). Os atom motion did not follow Brownian motion and appears to involve anchoring sites, probably S and Se atoms. The ability to control the atomic motion of metal atoms and molecules on surfaces has potential for exploitation in nanodevices of the future. PMID:26525180

  14. Osmium Atoms and Os2 Molecules Move Faster on Selenium-Doped Compared to Sulfur-Doped Boronic Graphenic Surfaces

    PubMed Central

    2015-01-01

    We deposited Os atoms on S- and Se-doped boronic graphenic surfaces by electron bombardment of micelles containing 16e complexes [Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-diselenate/dithiolate)] encapsulated in a triblock copolymer. The surfaces were characterized by energy-dispersive X-ray (EDX) analysis and electron energy loss spectroscopy of energy filtered TEM (EFTEM). Os atoms moved ca. 26× faster on the B/Se surface compared to the B/S surface (233 ± 34 pm·s–1versus 8.9 ± 1.9 pm·s–1). Os atoms formed dimers with an average Os–Os distance of 0.284 ± 0.077 nm on the B/Se surface and 0.243 ± 0.059 nm on B/S, close to that in metallic Os. The Os2 molecules moved 0.83× and 0.65× more slowly than single Os atoms on B/S and B/Se surfaces, respectively, and again markedly faster (ca. 20×) on the B/Se surface (151 ± 45 pm·s–1 versus 7.4 ± 2.8 pm·s–1). Os atom motion did not follow Brownian motion and appears to involve anchoring sites, probably S and Se atoms. The ability to control the atomic motion of metal atoms and molecules on surfaces has potential for exploitation in nanodevices of the future. PMID:26525180

  15. Intermodal interferometer for strain and temperature sensing fabricated in birefringent boron doped microstructured fiber.

    PubMed

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

    2011-07-20

    We present a compact in-line fiber interferometric sensor fabricated in a boron doped two-mode highly birefringent microstructured fiber using a CO(2) laser. The intermodal interference arises at the fiber output due to coupling between the fundamental and the first order modes occurring at two fiber tapers distant by a few millimeters. The visibility of intermodal interference fringes is modulated by a polarimetric differential signal and varies in response to measurand changes. The proposed interferometer was tested for measurements of the strain and temperature, respectively, in the range of 20-700 °C and 0-17 mstrain. The sensitivity coefficients corresponding to fringe displacement and contrast variations are equal respectively for strain -2.51 nm/mstrain and -0.0256 1/mstrain and for temperature 16.7 pm/°C and 5.74×10(-5) 1/°C. This allows for simultaneous measurements of the two parameters by interrogation of the visibility and the displacement of interference fringes. PMID:21772355

  16. Use of seawater for the boron-doped diamond electrochemical treatment of diluted vinasse wastewater.

    PubMed

    Daskalaki, V M; Marakas, H; Mantzavinos, D; Katsaounis, A; Gikas, P

    2013-01-01

    Vinasse wastewater of high organic content (COD = 131,000 mg/L) and low biodegradability (BOD5/COD = 0.11) cannot be easily managed and usually require several consecutive treatment steps. The objective of this work was to dilute vinasse wastewater with seawater and then subject them to electrochemical oxidation over boron-doped diamond (BDD) electrodes. The use of seawater is a rational and novel approach for plants close to the seashore since it may achieve the desirable levels of effluent concentration and conductivity without consuming other water resources and extra electrolytes. Experiments were conducted at initial COD values of 830-8,400 mg/L, NaCl concentrations of 34-200 mM and current densities of 70-200 mA/cm(2) for up to 5 hours. The effect of current density and NaCl concentration was marginal on the electrochemical treatment, while the single most important parameter was the initial COD concentration. The order of reaction for COD reduction appears to be 'first' at low effluent concentrations and it decreases to 'zero' at higher concentrations, denoting the importance of the ratio of organics to reactive radicals concentration. Based on COD and total organic carbon data, it is postulated that degradation occurs predominantly through total oxidation (i.e. mineralization) to carbon dioxide and water, which is characteristic of BDD anodes. PMID:24334881

  17. QUANTIFICATION OF MERCURY IN FLUE GAS EMISSION USING BORON-DOPED DIAMOND ELECTROCHEMISTRY

    SciTech Connect

    A. Manivannan; M.S. Seehra

    2003-08-19

    In this project, we have attempted to develop a new technique utilizing Boron-doped diamond (BDD) films to electrochemically detect mercury dissolved in solution via the initial deposition of metallic mercury, followed by anodic linear sweep voltammetry in the range from 10-10{sup -10} M to 10{sup -5} M. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were employed. The extremely low background current for BDD electrodes compared to glassy carbon (GC) provides a strong advantage in trace metal detection. CV peak currents showed good linearity in the micromolar range. A detection level of 6.8 x 10{sup -10} M was achieved with DPV in 0.1 M KNO{sub 3} (pH = 1) for a deposition time of 20 minutes. Reproducible stripping peaks were obtained, even for the low concentration range. A comparison with GC shows that BDD is superior. Linear behavior was also obtained in the mercury concentration range from 10{sup -10} M to 10{sup -9} M.

  18. Boron-doped diamond nano/microelectrodes for bio-sensing and in vitro measurements

    PubMed Central

    Dong, Hua; Wang, Shihua; Galligan, James J.; Swain, Greg M.

    2015-01-01

    Since the fabrication of the first diamond electrode in the mid 1980s, repid progress has been made on the development and application of this new type of electrode material. Boron-doped diamond (BDD) electrodes exhibit outstanding properties compared to oxygen-containing sp2 carbon electrodes. These properties make BDD electrodes an ideal choice for use in complex samples. In recent years, BDD microelectrodes have been applied to in vitro and in vivo measurements of biological molecules in animals, tissues and cells. This review will summarize recent progress in the development and applications of BDD electrodes in bio-sensing and in vitro measurements of biomolecules. In the first section, the methods for BDD nanocrystalline diamond film deposition and BDD microelectrodes preparation are described. This is followed by a description and discussion of several approaches for characterization of the BDD electrode surface structure, morphology, and electrochemical activity. Further, application of BDD microelectrodes for use in the in vitro analysis of norepinephrine (NE), serotonin (5-HT), nitric oxide (NO), histamine, and adenosine from tissues are summarized and finally some of the remaining challenges are discussed. PMID:21196394

  19. Microfluidic platform for environmental contaminants sensing and degradation based on boron-doped diamond electrodes.

    PubMed

    Medina-Sánchez, Mariana; Mayorga-Martinez, CarmenC; Watanabe, Takeshi; Ivandini, TribidasariA; Honda, Yuki; Pino, Flavio; Nakata, Kazuya; Fujishima, Akira; Einaga, Yasuaki; Merkoçi, Arben

    2016-01-15

    We have developed a lab-on-a-chip (LOC) platform for electrochemical detection and degradation of the pesticide atrazine (Atz). It is based on boron-doped diamond (BDD) electrodes and a competitive magneto-enzyme immunoassay (EIA) that enables high sensitivity. To detect the enzymatic reaction, we employed a BDD electrode modified with platinum nanoparticles (PtNPs), as a highly conductive catalytic transducer. Chronoamperometry revealed a limit of detection (LOD) of 3.5 pM for atrazine, which, to the best of our knowledge, is one of the lowest value published to date. Finally, we degraded Atz in the same platform, using a bare BDD electrode that features remarkable corrosion stability, a wide potential window, and much higher O2 overvoltage as compared to conventional electrodes. These characteristics enable the electrode to produce a greater amount of HO• on the anode surface than do conventional electrodes and consequently, to destroy the pollutant more rapidly. Our new LOC platform might prove interesting as a smart system for detection and remediation of diverse pesticides and other contaminants. PMID:26339934

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

    PubMed

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

    2012-11-20

    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 μA 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 μM (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

  1. Yeast-based Biochemical Oxygen Demand Sensors Using Gold-modified Boron-doped Diamond Electrodes.

    PubMed

    Ivandini, Tribidasari A; Harmesa; Saepudin, Endang; Einaga, Yasuaki

    2015-01-01

    A gold nanoparticle modified boron-doped diamond electrode was developed as a transducer for biochemical oxygen demand (BOD) measurements. Rhodotorula mucilaginosa UICC Y-181 was immobilized in a sodium alginate matrix, and used as a biosensing agent. Cyclic voltammetry was applied to study the oxygen reduction reaction at the electrode, while amperometry was employed to detect oxygen, which was not consumed by the microorganisms. The optimum waiting time of 25 min was observed using 1-mm thickness of yeast film. A comparison against the system with free yeast cells shows less sensitivity of the current responses with a linear dynamic range (R(2) = 0.99) of from 0.10 mM to 0.90 mM glucose (equivalent to 10 - 90 mg/L BOD) with an estimated limit of detection of 1.90 mg/L BOD. However, a better stability of the current responses could be achieved with an RSD of 3.35%. Moreover, less influence from the presence of copper ions was observed. The results indicate that the yeast-immobilized BOD sensors is more suitable to be applied in a real condition. PMID:26179128

  2. Adsorption properties of boroxol ring doped zigzag boron nitride nanotube toward NO molecule using DFT

    NASA Astrophysics Data System (ADS)

    Zahedi, Ehsan; Babaie, Mahsa; Bahmanpour, Hooman

    2016-05-01

    In previous researches it is demonstrated that reactivity and sensitivity of boron nitride nanotubes (BNNTs) toward gas molecules can be modified by impurity. In this work, oxygen defect for three nitrogen sites was used to study the adsorption of NO molecule through the surface of boroxol ring of oxygen doped BNNT (7,0) with different adsorption patterns, including side-on and end-on. All calculations are performed using the DFT-B3LYP/6-31G∗ level of theory, and their electronic energies are corrected by gCP and D3 correction terms. High binding energies indicate that NO molecule undergoes chemical adsorption with large charge transfer from the tube which can significantly change electronic properties of the tube. Density of state (DOS) and partial DOS (PDOS) analyses revealed that adsorption of NO molecule on the boroxol ring position is covalent in nature with significant effect on the electronic properties of tube. The Laplacian of electron density, Lagrangian kinetic energy density, Hamiltonian kinetic energy density and potential energy density at bond critical points between the tube and NO indicate that the interaction between the tube and NO molecule is covalent in nature. Topological analysis of the electron localization function shows that electrons in the new formed bonds are approximately localized, meaning that the nature of adsorption process is chemical covalent. The studied nanotube is a suitable candidate to filter and eliminate NO gas molecule.

  3. Electrochemical degradation of chlorobenzene on boron-doped diamond and platinum electrodes.

    PubMed

    Liu, Lei; Zhao, Guohua; Wu, Meifen; Lei, Yanzhu; Geng, Rong

    2009-08-30

    In this paper the electrochemical degradation of chlorobenzene (CB) was investigated on boron-doped diamond (BDD) and platinum (Pt) anodes, and the degradation kinetics on these two electrodes was compared. Compared with the total mineralization with a total organic carbon (TOC) removal of 85.2% in 6h on Pt electrode, the TOC removal reached 94.3% on BDD electrode under the same operate condition. Accordingly, the mineralization current efficiency (MCE) during the mineralization on BDD electrode was higher than that on the Pt electrode. Besides TOC, the conversion of CB, the productions and decay of intermediates were also monitored. Kinetic study indicated that the decay of CB on BDD and Pt electrodes were both pseudo-first-order reactions, and the reaction rate constant (k(s)) on BDD electrode was higher than that on Pt electrode. The different reaction mechanisms on the two electrodes were investigated by the variation of intermediates concentrations. Two different reaction pathways for the degradation of CB on BDD electrode and Pt electrode involving all these intermediates were proposed. PMID:19264395

  4. Electrochemical oxidation of biological pretreated and membrane separated landfill leachate concentrates on boron doped diamond anode

    NASA Astrophysics Data System (ADS)

    Zhou, Bo; Yu, Zhiming; Wei, Qiuping; Long, HangYu; Xie, Youneng; Wang, Yijia

    2016-07-01

    In the present study, the high quality boron-doped diamond (BDD) electrodes with excellent electrochemical properties were deposited on niobium (Nb) substrates by hot filament chemical vapor deposition (HFCVD) method. The electrochemical oxidation of landfill leachate concentrates from disc tube reverse osmosis (DTRO) process over a BDD anode was investigated. The effects of varying operating parameters, such as current density, initial pH, flow velocity and cathode material on degradation efficiency were also evaluated following changes in chemical oxygen demand (COD) and ammonium nitrogen (NH3sbnd N). The instantaneous current efficiency (ICE) was used to appraise different operating conditions. As a result, the best conditions obtained were as follows, current density 50 mA cm-2, pH 5.16, flow velocity 6 L h-1. Under these conditions, 87.5% COD and 74.06% NH3sbnd N removal were achieved after 6 h treatment, with specific energy consumption of 223.2 kWh m-3. In short, these results indicated that the electrochemical oxidation with BDD/Nb anode is an effective method for the treatment of landfill leachate concentrates.

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

    PubMed

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

    2008-06-15

    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, indicate that the BPA removal at BDD depends on the applied current density (Iappl), initial concentration of BPA, pH of electrolyte and supporting medium. Galvanostatic electrolysis at BDD anode cause concomitant generation of hydroxyl radical that leads to the BPA destruction. The kinetics for the BPA degradation follows a pseudo-first order reaction with a higher rate constant 12.8x10(-5) s(-1) for higher Iappl value 35.7 mA cm(-2), indicating that the oxidation reaction is limited by Iappl control. Complete mineralization of BPA was achieved regardless of the variables and accordingly the mineralization current efficiency was calculated from the TOC removal measurements. Considering global oxidation process, the effect of supporting electrolytes has been discussed in terms of the electro generated inorganic oxidants. The better performance of BDD anode was proved on a comparative study with Pt and glassy carbon under similar experimental conditions. A possible reaction mechanism for BPA degradation involving three main aromatic intermediates, identified by GC-MS analysis, was proposed. PMID:18023975

  6. Boron-doped diamond nano/microelectrodes for biosensing and in vitro measurements.

    PubMed

    Dong, Hua; Wang, Shihua; Galligan, James J; Swain, Greg M

    2011-01-01

    Since the fabrication of the first diamond electrode in the mid 1980s, repid progress has been made on the development and application of this new type of electrode material. Boron-doped diamond (BDD) electrodes exhibit outstanding properties compared to oxygen-containing sp2 carbon electrodes. These properties make BDD electrodes an ideal choice for use in complex samples. In recent years, BDD microelectrodes have been applied to in vitro measurements of biological molecules in tissues and cells. This review will summarize recent progress in the development and applications of BDD electrodes in bio-sensing and in vitro measurements of biomolecules. In the first section, the methods for BDD diamond film deposition and BDD microelectrodes preparation are described. This is followed by a description and discussion of several approaches for characterization of the BDD electrode surface structure, morphology, and electrochemical activity. Further, application of BDD microelectrodes for use in the in vitro analysis of norepinephrine (NE), serotonin (5-HT), nitric oxide (NO), histamine, and adenosine from tissues are summarized and finally some of the remaining challenges are discussed. PMID:21196394

  7. Continuous and selective measurement of oxytocin and vasopressin using boron-doped diamond electrodes.

    PubMed

    Asai, Kai; Ivandini, Tribidasari A; Einaga, Yasuaki

    2016-01-01

    The electrochemical detection of oxytocin using boron-doped diamond (BDD) electrodes was studied. Cyclic voltammetry of oxytocin in a phosphate buffer solution exhibits an oxidation peak at +0.7 V (vs. Ag/AgCl), which is attributable to oxidation of the phenolic group in the tyrosyl moiety. Furthermore, the linearity of the current peaks obtained in flow injection analysis (FIA) using BDD microelectrodes over the oxytocin concentration range from 0.1 to 10.0 μM with a detection limit of 50 nM (S/N = 3) was high (R(2) = 0.995). Although the voltammograms of oxytocin and vasopressin observed with an as-deposited BDD electrode, as well as with a cathodically-reduced BDD electrode, were similar, a clear distinction was observed with anodically-oxidized BDD electrodes due to the attractive interaction between vasopressin and the oxidized BDD surface. By means of this distinction, selective measurements using chronoamperometry combined with flow injection analysis at an optimized potential were demonstrated, indicating the possibility of making selective in situ or in vivo measurements of oxytocin. PMID:27599852

  8. Semiconducting polymers with nanocrystallites interconnected via boron-doped carbon nanotubes.

    PubMed

    Yu, Kilho; Lee, Ju Min; Kim, Junghwan; Kim, Geunjin; Kang, Hongkyu; Park, Byoungwook; Ho Kahng, Yung; Kwon, Sooncheol; Lee, Sangchul; Lee, Byoung Hun; Kim, Jehan; Park, Hyung Il; Kim, Sang Ouk; Lee, Kwanghee

    2014-12-10

    Organic semiconductors are key building blocks for future electronic devices that require unprecedented properties of low-weight, flexibility, and portability. However, the low charge-carrier mobility and undesirable processing conditions limit their compatibility with low-cost, flexible, and printable electronics. Here, we present significantly enhanced field-effect mobility (μ(FET)) in semiconducting polymers mixed with boron-doped carbon nanotubes (B-CNTs). In contrast to undoped CNTs, which tend to form undesired aggregates, the B-CNTs exhibit an excellent dispersion in conjugated polymer matrices and improve the charge transport between polymer chains. Consequently, the B-CNT-mixed semiconducting polymers enable the fabrication of high-performance FETs on plastic substrates via a solution process; the μFET of the resulting FETs reaches 7.2 cm(2) V(-1) s(-1), which is the highest value reported for a flexible FET based on a semiconducting polymer. Our approach is applicable to various semiconducting polymers without any additional undesirable processing treatments, indicating its versatility, universality, and potential for high-performance printable electronics. PMID:25372930

  9. Electrochemical decolorization of dye wastewater by surface-activated boron-doped nanocrystalline diamond electrode.

    PubMed

    Chen, Chienhung; Nurhayati, Ervin; Juang, Yaju; Huang, Chihpin

    2016-07-01

    Complex organics contained in dye wastewater are difficult to degrade and often require electrochemical advanced oxidation processes (EAOPs) to treat it. Surface activation of the electrode used in such treatment is an important factor determining the success of the process. The performance of boron-doped nanocrystalline diamond (BD-NCD) film electrode for decolorization of Acid Yellow (AY-36) azo dye with respect to the surface activation by electrochemical polarization was studied. Anodic polarization found to be more suitable as electrode pretreatment compared to cathodic one. After anodic polarization, the originally H-terminated surface of BD-NCD was changed into O-terminated, making it more hydrophilic. Due to the oxidation of surface functional groups and some portion of sp(2) carbon in the BD-NCD film during anodic polarization, the electrode was successfully being activated showing lower background current, wider potential window and considerably less surface activity compared to the non-polarized one. Consequently, electrooxidation (EO) capability of the anodically-polarized BD-NCD to degrade AY-36 dye was significantly enhanced, capable of nearly total decolorization and chemical oxygen demand (COD) removal even after several times of re-using. The BD-NCD film electrode favored acidic condition for the dye degradation; and the presence of chloride ion in the solution was found to be more advantageous than sulfate active species. PMID:27372123

  10. Amperometric oxygen sensor based on a platinum nanoparticle-modified polycrystalline boron doped diamond disk electrode.

    PubMed

    Hutton, Laura; Newton, Mark E; Unwin, Patrick R; Macpherson, Julie V

    2009-02-01

    Pt nanoparticle (NP)-modified polycrystalline boron-doped diamond (pBDD) disk electrodes have been fabricated and employed as amperometric sensors for the determination of dissolved oxygen concentration in aqueous solution. pBDD columns were cut using laser micromachining techniques and sealed in glass, in order to make disk electrodes which were then characterized electrochemically. Electrodeposition of Pt onto the diamond electrodes was optimized so as to give the maximum oxygen reduction peak current with the lowest background signal. Pt NPs, >0-10 nm diameter, were found to deposit randomly across the pBDD electrode, with no preference for grain boundaries. The more conductive grains were found to promote the formation of smaller nanoparticles at higher density. With the use of potential step chronoamperometry, in which the potential was stepped to a diffusion-limited value, a four electron oxygen reduction process was found to occur at the Pt NP-modified pBDD electrode. Furthermore the chronoamperometric response scaled linearly with dissolved oxygen concentration, varied by changing the oxygen/nitrogen ratio of gas flowed into solution. The sensor was used to detect dissolved oxygen concentrations with high precision over the pH range 4-10. PMID:19117391

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

    NASA Astrophysics Data System (ADS)

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

    2006-01-01

    Highly conductive boron-doped hydrogenated microcrystalline silicon (μc-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 (σd), 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 σd.

  12. Rapid-thermal-processing-based internal gettering for heavily boron-doped Czochralski silicon

    NASA Astrophysics Data System (ADS)

    Fu, Liming; Yang, Deren; Ma, Xiangyang; Tian, Daxi; Que, Duanlin

    2006-11-01

    The effect of rapid-thermal processing (RTP) ambients on the formation of oxygen precipitates and denuded zone (DZ) in heavily boron-doped (HB) Czochralski (Cz) silicon by a low-high (L-H) two-step annealing (800°C/4h+1000°C/16h) has been investigated. It was found that after the L-H two-step annealing, there was a high density of bulk microdefects (BMDs) and no observable DZ was formed near the surface in HB Cz silicon wafers preannealed by the RTP in Ar ambient, while the BMD density was quite low in HB Cz silicon wafers preannealed by the RTP in O2 ambient. However, applying the preannealing of RTP sequentially in Ar and O2 ambients allowed us to obtain a high density of BMDs in combination with a sufficient DZ by the subsequent L-H two-step annealing. This approach offers a pathway to optimize internal gettering for HB Cz silicon.

  13. Simultaneous hydrogen production and electrochemical oxidation of organics using boron-doped diamond electrodes.

    PubMed

    Jiang, Juyuan; Chang, Ming; Pan, Peng

    2008-04-15

    This paper presents advantages of using a boron-doped diamond (BDD) electrode for hydrogen production and wastewater treatment in a single electrochemical cell. Results indicated that the BDD electrode possessed the widest known electrochemical window, allowing new possibilities for both anodic and cathodic reactions to simultaneously take place. The BDD electrode exhibited high anodic potential, generating high oxidation state radicals that facilitated oxidation of toxic waste organic compounds such as 4-nitrophenols. In contrast, because of widening of potential windows, the rate of hydrogen evolution at the cathode was significantly increased. Time-on-stream concentrations of reaction intermediates were monitored to elucidate mechanism involved in 4-nitrophenol oxidation. Spalling, fouling, or reduction in the thickness of thin-film diamond coating was not observed. Overall, the BDD electrode exhibits unique properties including chemical inertness, anticorrosion, and extended service life. These properties are especially important in wastewater treatment. Economic advantages were attributed to the low cost and long duration BDD electrode and the valuable hydrogen byproduct produced. Analysis has shown that technology associated with the BDD electrode could be effectively implemented with minimum energy input and capital requirements. When combined with solar energy and fuel cells, electrochemical wastewater processing can become energy efficient and cost-effective. PMID:18497166

  14. Sub-bandgap analysis of boron doped InSe single crystals by constant photocurrent method

    NASA Astrophysics Data System (ADS)

    Bacıoğlu, A.; Ertap, H.; Karabulut, M.; Mamedov, G. M.

    2014-11-01

    Sub-bandgap absorption properties of indium selenide doped with boron atoms within a range of [B] = 0-1.8 at.% have been investigated. From the absorption coefficient spectra measured by using constant photocurrent method (CPM) at 300 K, we observed that the disorder in the structure increases. The calculated Urbach parameters, quantifying the disorder, vary from 17 to 53 meV, as [B] is increased from 0 to 1 at.%. Also the calculated optical gaps decrease from 1.28 eV to 1.17 eV for the same range of [B]. From temperature dependent dark conductivity measurements, the characteristic activation energies are calculated to range from 0.25 to 0.18 eV for vertical (to c-axis) direction; to stay almost constant for parallel (c-axis) direction. At a temperature of 12 K, the absorption coefficient spectra by using CPM and the radiative recombination spectra by photoluminescence (PL) have been taken for the samples with [B] = 0 and 0.5 at.%. Three main PL bands are observed at photon energies of ∼1.24, 1.306 and 1.337 eV. The PL bands are interpreted by corresponding absorption bands detected at 12 K and at the photon energies of ∼1.24, ∼1.31 and ∼1.35 eV.

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

    PubMed

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

    2012-06-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

    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.

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

    PubMed Central

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

    2012-01-01

    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. PMID:22969367

  18. Structural modification of boron-doped ZnO layers caused by hydrogen outgassing

    NASA Astrophysics Data System (ADS)

    Lovics, R.; Csik, A.; Takáts, V.; Hakl, J.; Vad, K.

    2015-07-01

    Results of annealing experiments of boron-doped zinc oxide (ZnO:B) layers prepared by low pressure chemical vapor deposition method on polished Si, soda-lime glass for windows, and AF45 Schott alkali free thin glass substrates are presented. It is shown that short annealing of samples at 150 °C and 300 °C in air causes serious surface degradation of samples prepared on Si and soda-lime glass substrate. The characteristic feature of degradation is the creation of bubbles and craters on the sample surface which fully destroy the continuity of zinc oxide layers. The results of depth distribution mapping of elements indicate that the formation of bubbles is linked to increase in hydrogen concentration in the layer. The surface degradation was not noticed on samples deposited on AF45 Schott alkali free thin glass which has a SiO2 diffusion barrier layer on the surface, only much fewer and smaller bubbles were visible. The results indicate the important role of hydrogen outgassing from the substrate induced by a thermal shock.

  19. Boron and nitrogen co-doped porous carbon and its enhanced properties as supercapacitor

    NASA Astrophysics Data System (ADS)

    Guo, Hongliang; Gao, Qiuming

    Boron and nitrogen co-doped porous carbons (BNCs) were prepared through a facile procedure using citric acid, boric acid and nitrogen as C, B and N precursors, respectively. The BNC samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and nitrogen sorption at 77 K. Cyclic voltammetry and galvanostatic charge/discharge experiments were adopted to investigate their electrochemical behaviors. The BNC-9 and BNC-15 samples with high specific surface areas of 894 and 726 m 2 g -1 showed the large specific capacitance up to 268 and 173 F g -1, respectively, with the current of 0.1 A g -1. When the current was set as 1 A g -1, the energy densities were 3.8 and 3.0 Wh kg -1 and the power densities were 165 and 201 W kg -1 for BNC-9 and BNC-15, respectively. Thus, BNC-15 is more suitable to apply in high-power-demanded occasion, while BNC-9 tends to store more energy.

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

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

    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.

  1. Hydrogen passivation of interstitial iron in boron-doped multicrystalline silicon during annealing

    SciTech Connect

    Liu, AnYao; Sun, Chang; Macdonald, Daniel

    2014-11-21

    Effective hydrogenation of interstitial iron in boron-doped multicrystalline silicon wafers is reported. The multicrystalline silicon wafers were annealed with plasma-enhanced chemical vapour deposited silicon nitride films, at temperatures of 400 °C – 900 °C and for times from minutes to hours. At low temperatures where a combined effect of hydrogenation and precipitation of dissolved Fe is expected, results show that the hydrogenation process dominates the effect of precipitation. The concentrations of dissolved interstitial iron reduce by more than 90% after a 30-min anneal at temperatures between 600 and 900 °C. The most effective reduction occurs at 700 °C, where 99% of the initial dissolved iron is hydrogenated after 30 min. The results show that the observed reductions in interstitial Fe concentrations are not caused by the internal gettering of Fe at structural defects or by an enhanced diffusivity of Fe due to the presence of hydrogen. The hydrogenation process is conjectured to be the pairing of positively charged iron with negatively charged hydrogen, forming less recombination active Fe-H complexes in silicon.

  2. Continuous and selective measurement of oxytocin and vasopressin using boron-doped diamond electrodes

    PubMed Central

    Asai, Kai; Ivandini, Tribidasari A.; Einaga, Yasuaki

    2016-01-01

    The electrochemical detection of oxytocin using boron-doped diamond (BDD) electrodes was studied. Cyclic voltammetry of oxytocin in a phosphate buffer solution exhibits an oxidation peak at +0.7 V (vs. Ag/AgCl), which is attributable to oxidation of the phenolic group in the tyrosyl moiety. Furthermore, the linearity of the current peaks obtained in flow injection analysis (FIA) using BDD microelectrodes over the oxytocin concentration range from 0.1 to 10.0 μM with a detection limit of 50 nM (S/N = 3) was high (R2 = 0.995). Although the voltammograms of oxytocin and vasopressin observed with an as-deposited BDD electrode, as well as with a cathodically-reduced BDD electrode, were similar, a clear distinction was observed with anodically-oxidized BDD electrodes due to the attractive interaction between vasopressin and the oxidized BDD surface. By means of this distinction, selective measurements using chronoamperometry combined with flow injection analysis at an optimized potential were demonstrated, indicating the possibility of making selective in situ or in vivo measurements of oxytocin. PMID:27599852

  3. Functionalization of boron-doped nanocrystalline diamond with N3 dye molecules.

    PubMed

    Yeap, W S; Liu, X; Bevk, D; Pasquarelli, A; Lutsen, L; Fahlman, M; Maes, W; Haenen, K

    2014-07-01

    N3 dye molecules [cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylato)ruthenium(II)] are covalently attached to boron-doped nanocrystalline diamond (B:NCD) thin films through a combination of coupling chemistries, i.e., diazonium, Suzuki, and EDC-NHS. X-ray and ultraviolet photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy are used to verify the covalent bonding of the dye on the B:NCD surface (compared to a hydrogen-terminated reference). The spectroscopic results confirm the presence of a dense N3 chromophore layer, and the positions of the frontier orbitals of the dye relative to the band edge of the B:NCD thin film are inferred as well. Proof-of-concept photoelectrochemical measurements show a strong increase in the photocurrent compared to non-dye-functionalized B:NCD films. This study opens up the possibility of applying N3-sensitized B:NCD thin films as hole conductors in dye-sensitized solar cells. PMID:24915549

  4. Photoluminescence properties of thermographic phosphors YAG:Dy and YAG:Dy, Er doped with boron and nitrogen

    NASA Astrophysics Data System (ADS)

    Chepyga, Liudmyla M.; Jovicic, Gordana; Vetter, Andreas; Osvet, Andres; Brabec, Christoph J.; Batentschuk, Miroslaw

    2016-08-01

    This paper investigates Dy3+-doped and Dy3+, Er3+-co-doped yttrium aluminum garnets (YAG) with the admixture of boron nitride with the aim of using them as efficient thermographic phosphors at high temperatures. The phosphors were synthesized using a conventional high-temperature solid-state method. The influence of two fluxes, B2O3 and LiF/NH4F, and the effect of activator and coactivator concentrations were investigated. Additionally, the effect of B3+ and N3- substituting for Al3+ and O2- ions, respectively, in the YAG:Dy3+ co-doped with Er3+ was studied for the first time. The changes in the host lattice led to a much stronger photoluminescence compared with the samples without B3+ and N3- substitution. The admixture of BN also improves the thermal sensitivity of the YAG:Dy and YAG:Dy, Er thermographic phosphors.

  5. Thin layer of ordered boron-doped TiO2 nanotubes fabricated in a novel type of electrolyte and characterized by remarkably improved photoactivity

    NASA Astrophysics Data System (ADS)

    Siuzdak, Katarzyna; Szkoda, Mariusz; Lisowska-Oleksiak, Anna; Grochowska, Katarzyna; Karczewski, Jakub; Ryl, Jacek

    2015-12-01

    This paper reports a novel method of boron doped titania nanotube arrays preparation by electrochemical anodization in electrolyte containing boron precursor - boron trifluoride diethyl etherate (BF3 C4H10O), simultaneously acting as an anodizing agent. A pure, ordered TiO2 nanotubes array, as a reference sample, was also prepared in solution containing a standard etching compound: ammonium fluoride. The doped and pure titania were characterized by scanning electron microscopy, UV-vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, photoluminescence emission spectroscopy and by means of electrochemical methods. The B-doping decidedly shifts the absorption edge of TiO2 nanotubes towards the visible light region and significantly inhibits the radiative recombination processes. Despite the fact that the doped sample is characterized by 4.6 lower real surface area when compared to pure titania, it leads to the decomposition of methylene blue in 93%, that is over 2.3 times higher than the degradation efficiency exhibited by the undoped material. The formation rate of hydroxyl radicals (rad OH) upon illumination significantly favours boron doped titania as a photocatalytic material. Moreover, the simple doping of TiO2 nanotubes array results in the enhancement of generated photocurrent from 120 μA/cm2 to 350 μA/cm2 registered for undoped and doped electrode, respectively.

  6. Hard magnetic property enhancement of Co{sub 7}Hf-based ribbons by boron doping

    SciTech Connect

    Chang, H. W.; Liao, M. C.; Shih, C. W.; Chang, W. C.; Yang, C. C.; Hsiao, C. H.; Ouyang, H.

    2014-11-10

    Hard magnetic property enhancement of melt spun Co{sub 88}Hf{sub 12} ribbons by boron doping is demonstrated. B-doping could not only remarkably enhance the magnetic properties from energy product ((BH){sub max}) of 2.6 MGOe and intrinsic coercivity ({sub i}H{sub c}) of 1.5 kOe for B-free Co{sub 88}Hf{sub 12} ribbons to (BH){sub max} = 7.7 MGOe and {sub i}H{sub c} = 3.1 kOe for Co{sub 85}Hf{sub 12}B{sub 3} ribbons but also improve the Curie temperature (T{sub C}) of 7:1 phase. The (BH){sub max} value achieved in Co{sub 85}Hf{sub 12}B{sub 3} ribbons is the highest in Co-Hf alloy ribbons ever reported, which is about 15% higher than that of Co{sub 11}Hf{sub 2}B ribbons spun at 16 m/s [M. A. McGuire, O. Rios, N. J. Ghimire, and M. Koehler, Appl. Phys. Lett. 101, 202401 (2012)]. The structural analysis confirms that B enters the orthorhombic Co{sub 7}Hf (7:1) crystal structure as interstitial atoms, forming Co{sub 7}HfB{sub x}, in the as-spun state. Yet B may diffuse out from the 7:1 phase after post-annealing, leading to the reduction of Curie temperature and the magnetic properties. The uniformly refined microstructure with B-doping results in high remanence (B{sub r}) and improves the squareness of demagnetization curve. The formation of interstitial-atom-modified Co{sub 7}HfB{sub x} phase and the microstructure refinement are the main reasons to give rise to the enhancement of hard magnetic properties in the B-containing Co{sub 7}Hf-based ribbons.

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

    PubMed

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

    2011-06-15

    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

  8. Empirical determination of the energy band gap narrowing in p{sup +} silicon heavily doped with boron

    SciTech Connect

    Yan, Di Cuevas, Andres

    2014-11-21

    In the analysis of highly doped silicon, energy band gap narrowing (BGN) and degeneracy effects may be accounted for separately, as a net BGN in conjunction with Fermi-Dirac statistics, or lumped together in an apparent BGN used with Boltzmann statistics. This paper presents an experimental study of silicon highly doped with boron, with the aim of evaluating the applicability of previously reported BGN models. Different boron diffusions covering a broad range of dopant densities were prepared, and their characteristic recombination current parameters J{sub 0} were measured using a contactless photoconductance technique. The BGN was subsequently extracted by matching theoretical simulations of carrier transport and recombination in each of the boron diffused regions and the measured J{sub 0} values. An evaluation of two different minority carrier mobility models indicates that their impact on the extraction of the BGN is relatively small. After considering possible uncertainties, it can be concluded that the BGN is slightly larger in p{sup +} silicon than in n{sup +} silicon, in qualitative agreement with theoretical predictions by Schenk. Nevertheless, in quantitative terms that theoretical model is found to slightly underestimate the BGN in p{sup +} silicon. With the two different parameterizations derived in this paper for the BGN in p{sup +} silicon, both statistical approaches, Boltzmann and Fermi-Dirac, provide a good agreement with the experimental data.

  9. Boron Substitution in Disordered Graphene-like Carbon

    NASA Astrophysics Data System (ADS)

    Schaeperkoetter, Joe; Gillespie, Andrew; Wexler, Carlos; Pfeifer, Peter; Materials Research Institute-Missouri S&T Collaboration; Paul Rulis Collaboration

    2015-03-01

    X-ray photoelectron spectroscopy was used to determine both the elemental composition of boron doped carbons as well as gain insight into the arrangement of atoms in the material. The hypothesized arrangement of atoms is a direct substitution of boron for carbon into a graphene like sheet, maintaining the hexagonal honeycomb lattice of sp2 sigma bonds. Such a boron atom would have an electronic configuration of 1s2(sp2)3 . With a graphitic carbon atom, the pz orbitals are maintained and participate in mobile pi bonds with neighboring carbon atoms, as understood in the aromatic model. Boron, however, would require a charge donation to fill its pz orbital. Thus, three possible models are proposed for the out of plane electron density: (1) the orbital remains unoccupied and the boron is a free radical, (2) charge is donated from a neighboring atom and the boron atom is ionic, (3) the delocalization of charge in the aromatic system results in a partial charge transfer with an effective charge somewhere between neutral and anionic. Our results suggest that boron is not in an anionic state, and, by doing a quantitative and simultaneous analysis from multiple elemental spectra, we conclude that no more than 2 wt% of boron is being substitutionally doped into the system.

  10. Diffusion-driven precipitate growth and ripening of oxygen precipitates in boron doped silicon by dynamical x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Will, J.; Gröschel, A.; Bergmann, C.; Spiecker, E.; Magerl, A.

    2014-03-01

    X-ray Pendellösung fringes from three silicon single crystals measured at 900 °C are analyzed with respect to density and size of oxygen precipitates within a diffusion-driven growth model and compared with TEM investigations. It appears that boron doped (p+) material shows a higher precipitate density and a higher strain than moderately (p-) boron crystals. In-situ diffraction reveals a diffusion-driven precipitate growth followed by a second growth regime in both materials. An interpretation of the second growth regime in terms of Ostwald ripening yields surface energy values (around 70 erg/cm2) similar to published data. Further, an increased nucleation rate by a factor of ˜13 is found in the p+ sample as compared to a p- sample at a nucleation temperature of 450 °C.

  11. Reagentless polyol detection by conductivity increase in the course of self-doping of boronate-substituted polyaniline.

    PubMed

    Andreyev, Egor A; Komkova, Maria A; Nikitina, Vita N; Zaryanov, Nikolay V; Voronin, Oleg G; Karyakina, Elena E; Yatsimirsky, Anatoly K; Karyakin, Arkady A

    2014-12-01

    We report on the novel reagentless and label-free detection principle based on electroactive (conducting) polymers considering sensors for polyols, particularly, saccharides and hydroxy acids. Unlike the majority of impedimetric and conductometric (bio)sensors, which specific and unspecific signals are directed in the same way (resistance increase), making doubtful their real applications, the response of the reported system results in resistance decrease, which is directed oppositely to the background. The mechanism of the resistance decrease is the polyaniline self-doping, i.e., as an alternative to proton doping, an appearance of the negatively charged aromatic ring substituents in polymer chain. Negative charge "freezing" at the boron atom is indeed a result of complex formation with di- and polyols, specific binding. Changes in Raman spectra of boronate-substituted polyaniline after addition of glucose are similar to those caused by proton doping of the polymer. Thermodynamic data on interaction of the electropolymerized 3-aminophenylboronic acid with saccharides and hydroxy acids also confirm that the observed resistance decrease is due to polymer interaction with polyols. The first reported conductivity increase as a specific signal opens new horizons for reagentless affinity sensors, allowing the discrimination of specific affinity bindings from nonspecific interactions. PMID:25363870

  12. Improved electrochemical performance of boron-doped SiO negative electrode materials in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Woo, Jihoon; Baek, Seong-Ho; Park, Jung-Soo; Jeong, Young-Min; Kim, Jae Hyun

    2015-12-01

    We introduce a one-step process that consists of thermal disproportionation and impurity doping to enhance the reversible capacity and electrical conductivity of silicon monoxide (SiO)-based negative electrode materials in Li-ion batteries. Transmission electron microscope (TEM) results reveal that thermally treated SiO at 900 °C (H-SiO) consists of uniformly dispersed nano-crystalline Si (nc-Si) in an amorphous silicon oxide (SiOx) matrix. Compared to that of prinstine SiO, the electrochemical performance of H-SiO shows improved specific capacity, due mainly to the increased reversible capacity by nc-Si and to the reduced volume expansion by thermally disproportionated SiOx matrix. Further electrochemical improvements can be obtained by boron-doping on SiO (HB-SiO) using solution dopant during thermal disproportionation. HB-SiO electrode without carbon coating exhibits significantly enhanced specific capacity superior to that of undoped H-SiO electrode, having 947 mAh g-1 at 0.5C rate and excellent capacity retention of 93.3% over 100 cycles. Electrochemical impedance spectroscopy (EIS) measurement reveals that the internal resistance of the HB-SiO electrode is significantly reduced by boron doping.

  13. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Siuzdak, K.; Bogdanowicz, R.; Sawczak, M.; Sobaszek, M.

    2014-12-01

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (~200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm-2 at a scan rate of 10 mV s-1 for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  14. In Situ Activation of Nitrogen-Doped Graphene Anchored on Graphite Foam for a High-Capacity Anode.

    PubMed

    Ji, Junyi; Liu, Jilei; Lai, Linfei; Zhao, Xin; Zhen, Yongda; Lin, Jianyi; Zhu, Yanwu; Ji, Hengxing; Zhang, Li Li; Ruoff, Rodney S

    2015-08-25

    We report the fabrication of a three-dimensional free-standing nitrogen-doped porous graphene/graphite foam by in situ activation of nitrogen-doped graphene on highly conductive graphite foam (GF). After in situ activation, intimate "sheet contact" was observed between the graphene sheets and the GF. The sheet contact produced by in situ activation is found to be superior to the "point contact" obtained by the traditional drop-casting method and facilitates electron transfer. Due to the intimate contact as well as the use of an ultralight GF current collector, the composite electrode delivers a gravimetric capacity of 642 mAh g(-1) and a volumetric capacity of 602 mAh cm(-3) with respect to the whole electrode mass and volume (including the active materials and the GF current collector). When normalized based on the mass of the active material, the composite electrode delivers a high specific capacity of up to 1687 mAh g(-1), which is superior to that of most graphene-based electrodes. Also, after ∼90 s charging, the anode delivers a capacity of about 100 mAh g(-1) (with respect to the total mass of the electrode), indicating its potential use in high-rate lithium-ion batteries. PMID:26258909

  15. Sulfate-mediated electrooxidation of X-ray contrast media on boron-doped diamond anode.

    PubMed

    Radjenovic, Jelena; Petrovic, Mira

    2016-05-01

    Recently, electrochemical activation of sulfate ions to sulfate radical species and nonradically activated persulfate has been demonstrated at boron-doped diamond (BDD) anode, which enhanced the electrooxidation kinetics of several persistent contaminants. In this study, we investigated the transformation pathways of two X-ray contrast media (ICM), diatrizoate and iopromide, in electrooxidation at BDD anode using sulfate and inert nitrate anolyte. Sulfate anolyte yielded a seven-fold increase in apparent rate constants for ICM oxidation compared to inert nitrate anolyte, and a two-fold increase for the removal of organic carbon. Higher iodine release was observed in electrooxidation of diatrizoate compared to iopromide. In the case of diatrizoate, around 80% of deiodination efficiency was achieved in both anolytes. Deiodination efficiency of iopromide was somewhat lower in nitrate anolyte (≤75%) and significantly reduced in sulfate anolyte (≤46%) due to a larger steric hindrance of alkyl side chains. Moreover, a considerable lag phase of iopromide deiodination was observed in sulfate anolyte, indicating that initial oxidation reactions took place almost exclusively at the alkyl side chains. Several transformation products (TPs) of ICM were identified in electrooxidation in sulfate anolyte, and only three TPs in the case of nitrate anolyte. The main mechanistic steps in the oxidation of iopromide were H-abstraction and bond cleavage in the alkyl side chains. Diatrizoate was mainly transformed through oxidative cleavage of iodine substituent and inter-molecular cyclization. Two hydroxylamine derivatives of iopromide and a nitro-derivative of diatrizoate were observed in sulfate anolyte. These products have not been reported previously for hydroxyl radical-mediated oxidation of ICM. Given that electron-transfer mechanism is more typical for sulfate than for hydroxyl radicals, formation of hydroxylamine and nitro-derivatives of ICM was assigned to one

  16. Kinetics of the electrochemical mineralization of perfluorooctanoic acid on ultrananocrystalline boron doped conductive diamond electrodes.

    PubMed

    Urtiaga, Ane; Fernández-González, Carolina; Gómez-Lavín, Sonia; Ortiz, Inmaculada

    2015-06-01

    This work deals with the electrochemical degradation and mineralization of perfluorooctanoic acid (PFOA). Model aqueous solutions of PFOA (100mg/L) were electro-oxidized under galvanostatic conditions in a flow-by undivided cell provided with a tungsten cathode and an anode formed by a commercial ultrananocrystalline boron doped diamond (BDD) coating on a niobium substrate. A systematic experimental study was conducted in order to analyze the influence of the following operation variables: (i) the supporting electrolyte, NaClO4 (1.4 and 8.4g/L) and Na2SO4 (5g/L); (ii) the applied current density, japp, in the range 50-200 A/m(2) and (iii) the hydrodynamic conditions, in terms of flowrate in the range 0.4×10(-4)-1.7×10(-4)m(3)/s and temperature in the range 293-313K. After 6h of treatment and at japp 200A/m(2), PFOA removal was higher than 93% and the mineralization ratio, obtained from the decrease of the total organic carbon (TOC) was 95%. The electrochemical generation of hydroxyl radicals in the supporting electrolyte was experimentally measured based on their reaction with dimethyl sulfoxide. The enhanced formation of hydroxyl radicals at higher japp was related to the faster kinetics of PFOA removal. The fitting of experimental data to the proposed kinetic model provided the first order rate constants of PFOA degradation, kc(1) that moved from 2.06×10(-4) to 15.58×10(-4)s(-1), when japp varied from 50 to 200A/m(2). PMID:24981910

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

    NASA Astrophysics Data System (ADS)

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

    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.

  18. Toward a Boron-Doped Ultrananocrystalline Diamond Electrode-Based Dielectrophoretic Preconcentrator.

    PubMed

    Zhang, Wenli; Radadia, Adarsh D

    2016-03-01

    This paper presents results on immunobeads-based isolation of rare bacteria and their capture at a boron-doped ultrananocrystalline diamond (BD-UNCD) electrode in a microfluidic dielectrophoretic preconcentrator. We systematically vary the bead surface chemistry and the BD-UNCD surface chemistry and apply dielectrophoresis to improve the specific and the nonspecific capture of bacteria or beads. Immunobeads were synthesized by conjugating antibodies to epoxy-/sulfate, aldehyde-/sulfate, or carboxylate-modified beads with or without poly(ethylene glycol) (PEG) coimmobilization. The carboxylate-modified beads with PEG provided the highest capture efficiency (∼65%) and selectivity (∼95%) in isolating live Escherichia coli O157:H7 from cultures containing 1000 E. coli O157:H7 colony-forming units (cfu)/mL, or ∼500 E. coli O157:H7 and ∼500 E. coli K12 cfu/mL. Higher specificity was achieved with the addition of PEG to the antibody-functionalized bead surface, highest with epoxy-/sulfate beads (85-86%), followed by carboxylate-modified beads (76-78%) and aldehyde-/sulfate beads (74-76%). The bare BD-UNCD electrodes of the preconcentrator successfully withstood 240 kV/m for 100 min that was required for the microfluidic dielectrophoresis of 1 mL of sample. As expected, the application of dielectrophoresis increased the specific and the nonspecific capture of immunobeads at the BD-UNCD electrodes; however, the capture specificity remained unaltered. The addition of PEG to the antibody-functionalized BD-UNCD surface had little effect on the specificity in immunobeads capture. These results warrant the fabrication of electrical biosensors with BD-UNCD so that dielectrophoretic preconcentration can be performed directly at the biosensing electrodes. PMID:26829879

  19. Use of B{sub 2}O{sub 3} films grown by plasma-assisted atomic layer deposition for shallow boron doping in silicon

    SciTech Connect

    Kalkofen, Bodo Amusan, Akinwumi A.; Bukhari, Muhammad S. K.; Burte, Edmund P.; Garke, Bernd; Lisker, Marco; Gargouri, Hassan

    2015-05-15

    Plasma-assisted atomic layer deposition (PALD) was carried for growing thin boron oxide films onto silicon aiming at the formation of dopant sources for shallow boron doping of silicon by rapid thermal annealing (RTA). A remote capacitively coupled plasma source powered by GaN microwave oscillators was used for generating oxygen plasma in the PALD process with tris(dimethylamido)borane as boron containing precursor. ALD type growth was obtained; growth per cycle was highest with 0.13 nm at room temperature and decreased with higher temperature. The as-deposited films were highly unstable in ambient air and could be protected by capping with in-situ PALD grown antimony oxide films. After 16 weeks of storage in air, degradation of the film stack was observed in an electron microscope. The instability of the boron oxide, caused by moisture uptake, suggests the application of this film for testing moisture barrier properties of capping materials particularly for those grown by ALD. Boron doping of silicon was demonstrated using the uncapped PALD B{sub 2}O{sub 3} films for RTA processes without exposing them to air. The boron concentration in the silicon could be varied depending on the source layer thickness for very thin films, which favors the application of ALD for semiconductor doping processes.

  20. Electrochemical treatment of wastewater polluted by nitrate: selective reduction to N2 on boron-doped diamond cathode.

    PubMed

    Georgeaud, V; Diamand, A; Borrut, D; Grange, D; Coste, M

    2011-01-01

    Electrochemical tests of nitrate reduction on Boron-Doped Diamond cathode are investigated through a Design of Experiments (DOE) method. The results show good reduction of nitrate into almost exclusively N2. In the studied domain, the best experimental conditions are high initial nitrate content, low acidic pH values and low working current densities. The application of DOE conclusions on an agro-industrial wastewater gives really satisfying results: final nitrate contents lower than 50 mg/L without nitrite or ammonium formation, and with low energy consumption (under 25 kWh/kgNO3). PMID:21252421

  1. Oxidative synthesis of highly fluorescent boron/nitrogen co-doped carbon nanodots enabling detection of photosensitizer and carcinogenic dye.

    PubMed

    Jahan, Shanaz; Mansoor, Farrukh; Naz, Shagufta; Lei, Jianping; Kanwal, Shamsa

    2013-11-01

    Current research efforts have demonstrated the facile hydrothermal oxidative synthetic route to develop highly fluorescent boron/nitrogen co-doped carbon nanodots (CNDs). During this process, N-(4-hydroxyphenyl)glycine served as a source of N doping and a carbon precursor as well, while boric acid H3BO3 is used as an oxidizing agent in the N2 environment. Surface passivation through ultrasonic treatment of CNDs was performed to induce modifications by using various surface passivating agents. Polyethyleneimine (PEI) remarkably enhanced the fluorescence performance and monodispersity of polymerized carbon nanodots (P-CNDs) in aqueous phase with an enhanced quantum yield of 23.71%, along with an increase in size from ~3 nm to ~200 nm. For characterization of CNDs and P-CNDs, UV, infrared, photoluminescence, transmission electron microscopy, x-ray photoelectron spectra, and atomic force microscopy techniques were utilized. Application potentials of synthesized P-CNDs were developed via introduction of protoporphyrin (PPD, a photosensitizer) which has great doping affinity with polymer PEI to switch-off the fluorescence of P-CNDs, leading to the production of dye-doped nanoprobes. Fluorescence resonance energy transfer (FRET) was also observed during dye-doping, and PPD was detected with a limit of detection (LOD, 3σ) of 15 pM. The fluorescence recovery of this switched-off nanoprobe was made possible by using Sudan red III (carcinogenic dye), which was oxidized by PPD doped in P-CNDs. Sudan red III was detected in the concentration range of 9.9 pM-0.37 nM. Meanwhile, it was also confirmed that the dye-doped nanoprobe is highly selective and exceptionally sensitive to detect this carcinogenic agent in commercial products with a LOD (3σ) of 90 fM. PMID:24083490

  2. Boron-doped bismuth oxybromide microspheres with enhanced surface hydroxyl groups: Synthesis, characterization and dramatic photocatalytic activity.

    PubMed

    Liu, ZhangSheng; Liu, JinLong; Wang, HaiYang; Cao, Gang; Niu, JiNan

    2016-02-01

    B-doped BiOBr photocatalysts were successfully synthesized via a facile solvothermal method with boric acid used as boron source. As-obtained products consist of novel hierarchical microspheres, whose nanosheet building units were formed by nanoparticles splicing. They showed dramatic photocatalytic efficiency toward the degradation of Rhodamine B (RhB) and phenol under the visible-light irradiation and the highest activity was achieved by 0.075B-BiOBr. The enhanced photocatalytic activity could be attributed to the enriched surface hydroxyl groups on B-doped BiOBr samples, which not only improved the adsorption of pollutant on the photocatalyst but also promoted the separation of photogenerated electron-hole pairs. In addition, it was found that the main reactive species responsible for the degradation of organic pollutant were h(+) and O2(-) radicals, instead of OH radicals. PMID:26590875

  3. Strain-induced programmable half-metal and spin-gapless semiconductor in an edge-doped boron nitride nanoribbon

    NASA Astrophysics Data System (ADS)

    Zhu, Shuze; Li, Teng

    2016-03-01

    The search for half-metals and spin-gapless semiconductors has attracted extensive attention in material design for spintronics. Existing progress in such a search often requires peculiar atomistic lattice configuration and also lacks active control of the resulting electronic properties. Here we reveal that a boron nitride nanoribbon with a carbon-doped edge can be made a half-metal or a spin-gapless semiconductor in a programmable fashion. The mechanical strain serves as the on/off switches for functions of half-metal and spin-gapless semiconductor to occur. Our findings shed light on how the edge doping combined with strain engineering can affect electronic properties of two-dimensional materials.

  4. High density and taper-free boron doped Si{sub 1−x}Ge{sub x} nanowire via two-step growth process

    SciTech Connect

    Periwal, Priyanka; Salem, Bassem; Bassani, Franck; Baron, Thierry; Barnes, Jean-Paul

    2014-07-01

    The authors study Au catalyzed chemical vapor growth of Si{sub 1−x}Ge{sub x} alloyed nanowires in the presence of diborane, serving as a dopant precursor. Our experiments reveal that introduction of diborane has a significant effect on doping and morphology. Boron exposure poisons the Au catalyst surface, suppresses catalyst activity, and causes significantly tapered wires, as a result of conformal growth. The authors develop here a two-step method to obtain high density and taper-free boron doped Si{sub 1−x}Ge{sub x} alloy nanowires. The two-step process consists of: (1) growth of a small undoped Si{sub 1−x}Ge{sub x} section and (2) introduction of diborane to form a boron doped Si{sub 1−x}Ge{sub x} section. The catalyst preparation step remarkably influences wire yield, quality and morphology. The authors show that dopant-ratio influences wire resistivity and morphology. Resistivity for high boron doped Si{sub 1−x}Ge{sub x} nanowire is 6 mΩ-cm. Four probe measurements show that it is possible to dope Si{sub 1−x}Ge{sub x} alloy nanowires with diborane.

  5. A Drude model analysis of conductivity and free carriers in boron-doped diamond films and investigations of their internal stress and strain.

    PubMed

    Manciu, Felicia S; Manciu, Marian; Durrer, William G; Salazar, Jessica G; Lee, Kendall H; Bennet, Kevin E

    2014-08-01

    Boron-doped diamond (BDD) has seen a substantial increase in interest for use as electrode coating material for electrochemistry and studies of deep brain stimulation mechanism. In this study, we present an alternative method for determining important characteristics, including conductivity, carrier concentration, and time constant, of such material by the signature of Drude-like metallic behavior in the far-infrared (IR) spectral range. Unlike the direct determination of conductivity from the four-point probe method, using far-IR transmittance provides additional information, such as whether the incorporation of boron results in a large concentration of carriers or in inducing defects in the diamond lattice. The slightly doped to medium-doped BDD samples that were produced using chemical vapor deposition and analyzed in this work show conductivities ranging between 5.5 and 11 (Ω cm)(-1). Different growth conditions demonstrate that increasing boron concentration results in an increase in the carrier concentration, with values between 7.2 × 10(16) and 2.5 × 10(17) carriers/cm(3). Addition of boron, besides leading to a decrease in the resistivity, also resulted in a decrease in the time constant, limiting BDD conductivity. Investigations, by confocal Raman mapping, of the induced stress in the material due to interaction with the substrate or to the amount of doping are also presented and discussed. The induced tensile stress, which was distributed closer to the film-substrate interface decreased slightly with doping. PMID:25328245

  6. One-Pot Synthesis of Hydrophilic and Hydrophobic N-Doped Graphene Quantum Dots via Exfoliating and Disintegrating Graphite Flakes

    PubMed Central

    Kuo, Na-Jung; Chen, Yu-Syuan; Wu, Chien-Wei; Huang, Chun-Yuan; Chan, Yang-Hsiang; Chen, I-Wen Peter

    2016-01-01

    Graphene quantum dots (GQDs) have drawn tremendous attention on account of their numerous alluring properties and a wide range of application potentials. Here, we report that hydrophilic and hydrophobic N-doped GQDs can be prepared via exfoliating and disintegrating graphite flakes. Various spectroscopic characterizations including TEM, AFM, FTIR, PL, XPS, and Raman spectroscopy demonstrated that the hydrophilic N-doped GQDs (IN-GQDs) and the hydrophobic N-doped GQDs (ON-GQDs) are mono-layered and multi-layered, respectively. In terms of practical aspects, the supercapacitor of an ON-GQDs/SWCNTs composite paper electrode was fabricated and exhibited an areal capacitance of 114 mF/cm2, which is more than 250% higher than the best reported value to date for a GQDs/carbon nanotube hybrid composite. For IN-GQDs applications, bio-memristor devices of IN-GQDs-albumen combination exhibited on/off current ratios in excess of 104 accompanied by stable switching endurance of over 250 cycles. The resistance stability of the high resistance state and the low resistance state could be maintained for over 104 s. Moreover, the IN-GQDs exhibited a superior quantum yield (34%), excellent stability of cellular imaging, and no cytotoxicity. Hence, the solution-based method for synchronized production of IN-GQDs and ON-GQDs is a facile and processable route that will bring GQDs-based electronics and composites closer to actualization. PMID:27452118

  7. One-Pot Synthesis of Hydrophilic and Hydrophobic N-Doped Graphene Quantum Dots via Exfoliating and Disintegrating Graphite Flakes

    NASA Astrophysics Data System (ADS)

    Kuo, Na-Jung; Chen, Yu-Syuan; Wu, Chien-Wei; Huang, Chun-Yuan; Chan, Yang-Hsiang; Chen, I.-Wen Peter

    2016-07-01

    Graphene quantum dots (GQDs) have drawn tremendous attention on account of their numerous alluring properties and a wide range of application potentials. Here, we report that hydrophilic and hydrophobic N-doped GQDs can be prepared via exfoliating and disintegrating graphite flakes. Various spectroscopic characterizations including TEM, AFM, FTIR, PL, XPS, and Raman spectroscopy demonstrated that the hydrophilic N-doped GQDs (IN-GQDs) and the hydrophobic N-doped GQDs (ON-GQDs) are mono-layered and multi-layered, respectively. In terms of practical aspects, the supercapacitor of an ON-GQDs/SWCNTs composite paper electrode was fabricated and exhibited an areal capacitance of 114 mF/cm2, which is more than 250% higher than the best reported value to date for a GQDs/carbon nanotube hybrid composite. For IN-GQDs applications, bio-memristor devices of IN-GQDs-albumen combination exhibited on/off current ratios in excess of 104 accompanied by stable switching endurance of over 250 cycles. The resistance stability of the high resistance state and the low resistance state could be maintained for over 104 s. Moreover, the IN-GQDs exhibited a superior quantum yield (34%), excellent stability of cellular imaging, and no cytotoxicity. Hence, the solution-based method for synchronized production of IN-GQDs and ON-GQDs is a facile and processable route that will bring GQDs-based electronics and composites closer to actualization.

  8. One-Pot Synthesis of Hydrophilic and Hydrophobic N-Doped Graphene Quantum Dots via Exfoliating and Disintegrating Graphite Flakes.

    PubMed

    Kuo, Na-Jung; Chen, Yu-Syuan; Wu, Chien-Wei; Huang, Chun-Yuan; Chan, Yang-Hsiang; Chen, I-Wen Peter

    2016-01-01

    Graphene quantum dots (GQDs) have drawn tremendous attention on account of their numerous alluring properties and a wide range of application potentials. Here, we report that hydrophilic and hydrophobic N-doped GQDs can be prepared via exfoliating and disintegrating graphite flakes. Various spectroscopic characterizations including TEM, AFM, FTIR, PL, XPS, and Raman spectroscopy demonstrated that the hydrophilic N-doped GQDs (IN-GQDs) and the hydrophobic N-doped GQDs (ON-GQDs) are mono-layered and multi-layered, respectively. In terms of practical aspects, the supercapacitor of an ON-GQDs/SWCNTs composite paper electrode was fabricated and exhibited an areal capacitance of 114 mF/cm(2), which is more than 250% higher than the best reported value to date for a GQDs/carbon nanotube hybrid composite. For IN-GQDs applications, bio-memristor devices of IN-GQDs-albumen combination exhibited on/off current ratios in excess of 10(4) accompanied by stable switching endurance of over 250 cycles. The resistance stability of the high resistance state and the low resistance state could be maintained for over 10(4) s. Moreover, the IN-GQDs exhibited a superior quantum yield (34%), excellent stability of cellular imaging, and no cytotoxicity. Hence, the solution-based method for synchronized production of IN-GQDs and ON-GQDs is a facile and processable route that will bring GQDs-based electronics and composites closer to actualization. PMID:27452118

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

    PubMed

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

    2013-07-01

    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 μM, 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 μM. 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

  10. Retention of enzyme activity with a boron-doped diamond electrode in the electro-oxidative nitration of lysozyme

    PubMed Central

    Iniesta, Jesús; Esclapez-Vicente, María Deseada; Heptinstall, John; Walton, David J.; Peterson, Ian R.; Mikhailov, Victor A.; Cooper, Helen J.

    2010-01-01

    In this paper we report the successful use of a non-metallic electrode material, boron-doped diamond (BDD), for the anodic electro-oxidative modification of hen egg white lysozyme (HEWL). Platinum electrodes can give rise to loss of activity of HEWL in electrosynthetic studies, whereas activity is retained on boron-doped diamond which is proposed as an effective substitute material for this purpose. We also compare literature methods of electrode pre-treatment to determine the most effective in electrosynthesis. Our findings show a decrease in total nitroprotein yield with decreasing nitrite concentration and an increase with increasing solution pH, confirming that, at a BDD electrode, the controlling factor remains the concentration of tyrosine phenolate anion. Purification of mono- and bis-nitrated HEWL and assay of enzymic activity showed better retention of activity at BDD electrode surfaces when compared to platinum. The products from electro-oxidation of HEWL at BDD were confirmed by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FT-ICR) mass spectrometry, which revealed unique mass increases of +45 and +90 Da for the mono- and bis-nitrated lysozyme, respectively, corresponding to nitration at tyrosine residues. The nitration sites were confirmed as Tyr23 and Tyr20. PMID:21760652

  11. High-pressure high-temperature phase diagram of gadolinium studied using a boron-doped heater anvil

    DOE PAGESBeta

    Montgomery, J. M.; Samudrala, G. K.; Velisavljevic, N.; Vohra, Y. K.

    2016-04-07

    A boron-doped designer heater anvil is used in conjunction with powder x-ray diffraction to collect structural information on a sample of quasi-hydrostatically loaded gadolinium metal up to pressures above 8GPa and 600K. The heater anvil consists of a natural diamond anvil that has been surface modified with a homoepitaxially grown chemical-vapor-deposited layer of conducting boron-doped diamond, and is used as a DC heating element. Internally insulating both diamond anvils with sapphire support seats allows for heating and cooling of the high-pressure area on the order of a few tens of seconds. This device is then used to scan the phasemore » diagram of the sample by oscillating the temperature while continuously increasing the externally applied pressure and collecting in situ time-resolved powder diffraction images. In the pressure-temperature range covered in this experiment, the gadolinium sample is observed in its hcp, αSm, and dhcp phases. Under this temperature cycling, the hcp → αSm transition proceeds in discontinuous steps at points along the expected phase boundary. From these measurements (representing only one hour of synchrotron x-ray collection time), a single-experiment equation of state and phase diagram of each phase of gadolinium is presented for the range of 0–10GPa and 300–650K« less

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

    SciTech Connect

    Taylor, G.T.; Sullivan, I.A.; Newey, A.W.E.

    2006-07-01

    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)

  13. High-pressure high-temperature phase diagram of gadolinium studied using a boron-doped heater anvil

    NASA Astrophysics Data System (ADS)

    Montgomery, J. M.; Samudrala, G. K.; Velisavljevic, N.; Vohra, Y. K.

    2016-04-01

    A boron-doped designer heater anvil is used in conjunction with powder x-ray diffraction to collect structural information on a sample of quasi-hydrostatically loaded gadolinium metal up to pressures above 8 GPa and 600 K. The heater anvil consists of a natural diamond anvil that has been surface modified with a homoepitaxially grown chemical-vapor-deposited layer of conducting boron-doped diamond, and is used as a DC heating element. Internally insulating both diamond anvils with sapphire support seats allows for heating and cooling of the high-pressure area on the order of a few tens of seconds. This device is then used to scan the phase diagram of the sample by oscillating the temperature while continuously increasing the externally applied pressure and collecting in situ time-resolved powder diffraction images. In the pressure-temperature range covered in this experiment, the gadolinium sample is observed in its hcp, αSm, and dhcp phases. Under this temperature cycling, the hcp → αSm transition proceeds in discontinuous steps at points along the expected phase boundary. From these measurements (representing only one hour of synchrotron x-ray collection time), a single-experiment equation of state and phase diagram of each phase of gadolinium is presented for the range of 0-10 GPa and 300-650 K.

  14. Boron doped diamond and glassy carbon electrodes comparative study of the oxidation behaviour of cysteine and methionine.

    PubMed

    Enache, T A; Oliveira-Brett, A M

    2011-04-01

    The electrochemical oxidation behaviour at boron doped diamond and glassy carbon electrodes of the sulphur-containing amino acids cysteine and methionine, using cyclic and differential pulse voltammetry over a wide pH range, was compared. The oxidation reactions of these amino acids are irreversible, diffusion-controlled pH dependent processes, and occur in a complex cascade mechanism. The amino acid cysteine undergoes similar three consecutive oxidation reactions at both electrodes. The first step involves the oxidation of the sulfhydryl group with radical formation, that undergoes nucleophilic attack by water to give an intermediate species that is oxidized in the second step to cysteic acid. The oxidation of the sulfhydryl group leads to a disulfide bridge between two similar cysteine moieties forming cysteine. The subsequent oxidation of cystine occurs at a higher potential, due to the strong disulfide bridge covalent bond. The electro-oxidation of methionine at a glassy carbon electrode occurs in two steps, corresponding to the formation of sulfoxide and sulfone, involving the adsorption and protonation/deprotonation of the thiol group, followed by electrochemical oxidation. Methionine undergoes a one-step oxidation reaction at boron doped diamond electrodes due to the negligible adsorption, and the oxidation also leads to the formation of methionine sulfone. PMID:21377428

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

    NASA Astrophysics Data System (ADS)

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

    2002-05-01

    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 compositions by varying the flow ratios of the C2H2, B2H6, and C2F6 source gases. The incorporation of B2H6 and C2F6 into PIIP deposited DLC resulted in the formation of F-C and B-C hybridized bonding structures. The levels of the F and B concentrations effected the chemical bonding and the physical properties as was evident from the changes observed in density, hardness, stress, friction coefficient, and contact angle of water on films. Compared to B-doped or F-doped DLC films, the F and B co-doping of DLC during PIIP deposition resulted in the formation of films that possessed a reduced hydrogen concentration and stress, while maintaining a high hardness, low friction coefficient, and high wetting contact angle.

  16. Study of Nitrogen Effect on the Boron Diffusion during Heat Treatment in Polycrystalline Silicon/Nitrogen-Doped Silicon Thin Films

    NASA Astrophysics Data System (ADS)

    Saci, Lynda; Mahamdi, Ramdane; Mansour, Farida; Boucher, Jonathan; Collet, Maéva; Bedel Pereira, Eléna; Temple-Boyer, Pierre

    2011-05-01

    The present paper studies the boron (B) diffusion in nitrogen (N) doped amorphous silicon (a-Si) layer in original bi-layer B-doped polycrystalline silicon (poly-Si)/in-situ N-doped Si layers (NIDOS) thin films deposited by low pressure chemical vapor deposition (LPCVD) technique. The B diffusion in the NIDOS layer was investigated by secondary ion mass spectrometry (SIMS) and Fourier transform infrared spectroscopy (FTIR) analysis. A new extended diffusion model is proposed to fit the SIMS profile of the bi-layer films. This model introduces new terms which take into account the effect of N concentration on the complex diffusion phenomena of B atoms in bi-layer films. SIMS results show that B diffusion does not exceed one third of NIDOS layer thickness after annealing. The reduction of the B diffusion in the NIDOS layer is due to the formation of complex B-N as shown by infrared absorption measurements. Electrical measurements using four-probe and Hall effect techniques show the good conductivity of the B-doped poly-Si layer after annealing treatment.

  17. 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

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

    2008-01-01

    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

  18. Boron-doped diamond microelectrodes for use in capillary electrophoresis with electrochemical detection.

    PubMed

    Cvacka, Josef; Quaiserová, Veronika; Park, JinWoo; Show, Yoshiyuki; Muck, Alexander; Swain, Greg M

    2003-06-01

    The fabrication and characterization of boron-doped diamond microelectrodes for use in electrochemical detection coupled with capillary electrophoresis (CE-EC) is discussed. The microelectrodes were prepared by coating thin films of polycrystalline diamond on electrochemically sharpened platinum wires (76-, 25-, and 10-microm diameter), using microwave-assisted chemical vapor deposition (CVD). The diamond-coated wires were attached to copper wires (current collectors), and several methods were explored to insulate the cylindrical portion of the electrode: nail polish, epoxy, polyimide, and polypropylene coatings. The microelectrodes were characterized by scanning electron microscopy, Raman spectroscopy, and cyclic voltammetry. They exhibited low and stable background currents and sigmoidally shaped voltammetric curves for Ru(NH3)6(3+/2+) and Fe(CN)6(3-/4-) at low scan rates. The microelectrodes formed with the large diameter Pt and sealed in polypropylene pipet tips were employed for end-column detection in CE. Evaluation of the CE-EC system and the electrode performance were accomplished using a 10 mM phosphate buffer, pH 6.0, run buffer, and a 30-cm-long fused-silica capillary (75-microm i.d.) with dopamine, catechol, and ascorbic acid serving as test analytes. The background current (approximately 100 pA) and noise (approximately 3 pA) were measured at different detection potentials and found to be very stable with time. Reproducible separation (elution time) and detection (peak current or area) of dopamine, catechol, and ascorbic acid were observed with response precisions of 4.1% or less. Calibration curves constructed from the peak area were linear over 4 orders of magnitude, up to a concentration between 0.1 and 1 mM. Mass limits of detection for dopamine and catechol were 1.7 and 2.6 fmol, respectively (S/N = 3). The separation efficiency was approximately 33,000, 56,000, and 98,000 plates/m for dopamine, catechol, and ascorbic acid, respectively. In

  19. Chirality-dependent boron-mediated growth of nitrogen-doped single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Wiltshire, Joseph G.; Li, Lain-Jong; Herz, Laura M.; Nicholas, Robin J.; Glerup, Marianne; Sauvajol, Jean-Louis; Khlobystov, Andrei N.

    2005-11-01

    A change in the relative abundance of single-walled carbon nanotubes, due to the presence of both nitrogen and boron during synthesis, has been identified through Raman and absorption spectroscopy. Raman spectroscopy shows that for two specific branches boron mediates the growth of smaller-diameter zigzag or near-zigzag nanotubes. We combine our experimental results with an improved Kataura model to identify two of the preferentially grown species as (16,0) and (14,1).

  20. Rapid thermal chemical vapor deposition of in situ boron-doped polycrystalline silicon-germanium films on silicon dioxide for complimentary-metal-oxide-semiconductor applications

    NASA Astrophysics Data System (ADS)

    Li, V. Z.-Q.; Mirabedini, M. R.; Kuehn, R. T.; Wortman, J. J.; Öztürk, M. C.; Batchelor, D.; Christensen, K.; Maher, D. M.

    1997-12-01

    In situ boron-doped polycrystalline Si1-xGex (x>0.4) films have been formed on the thermally grown oxides in a rapid thermal chemical vapor deposition processor using SiH4-GeH4-B2H6-H2 gas system. Our results showed that in situ boron-doped Si1-xGex films can be directly deposited on the oxide surface, in contrast to the rapid thermal deposition of undoped silicon-germanium (Si1-xGex) films on oxides which is a partially selective process and requires a thin silicon film pre-deposition to form a continuous film. For the in situ boron-doped Si1-xGex films, we observed that with the increase of the germane percentage in the gas source, the Ge content and the deposition rate of the film are increased, while its resistivity is decreased down to 0.66 mΩ cm for a Ge content of 73%. Capacitance-voltage characteristics of p-type metal-oxide-semiconductor capacitors with p+-Si1-xGex gates showed negligible polydepletion effect for a 75 Å gate oxide, indicating that a high doping level of boron at the poly-Si1-xGex/oxide interface was achieved.

  1. In vitro evaluation of the tribological response of Mo-doped graphite-like carbon film in different biological media.

    PubMed

    Huang, Jinxia; Wang, Liping; Liu, Bin; Wan, Shanhong; Xue, Qunji

    2015-02-01

    Complicated tribochemical reactions with the surrounding media often occur at the prosthesis material, which is a dominant factor causing the premature failure in revision surgery. Graphite-like carbon (GLC) film has been proven to be an excellent tribological adaption to water-based media, and this work focused on the friction and wear behavior of Mo-doped GLC (Mo-GLC)-coated poly(aryl ether ether ketone) sliding against Al2O3 counterpart in physiological saline, simulated body fluid, and fetal bovine serum (FBS), which mainly emphasized the interface interactions of the prosthetic materials/lubricant. Results showed different tribological responses of Mo-GLC/Al2O3 pairs strongly correlated with the interfacial reactions of the contacting area. Particularly, a transfer layer was believed to be responsible for the excellent wear reduction of Mo-GLC/Al2O3 pair in FBS medium, in which graphitic carbon and protein species were contained. The wear mechanisms are tentatively discussed according to the morphologies and chemical compositions of the worn surfaces examined by scanning electron microscope as well as X-ray photoelectron spectroscopy. PMID:25580834

  2. Influence of Boron doping on the structural, optical and electrical properties of CdO thin films by spray pyrolysis technique

    SciTech Connect

    Velusamy, P. Babu, R. Ramesh; Ramamurthi, K.

    2014-04-24

    Cadmium oxide and Boron (B) doped Cadmium oxide thin films were deposited using spray pyrolysis technique. The structural, morphological, electrical and optical properties of undoped and B doped CdO films are analyzed by varying the dopant concentration in the solution. The structural study shows the polycrystalline nature and cubic structure of undoped and B doped CdO thin films. Surface morphological study reveals that the grains are spherical in shape. Optical and electrical studies showed n-type semiconducting nature and optical band gap of 2.44 eV of deposited thin films.

  3. Plasma-assisted Recoil Implantation for Shallow Boron Doping in Silicon

    NASA Astrophysics Data System (ADS)

    Liu, H. L.; Gearhart, S. S.; Booske, J. H.; Wang, W.

    1997-10-01

    An ion beam mixing technique is used to fabricate ultra-shallow p+/n junctions for the application of sub-micron CMOS source/drain formation. In this method, a thin boron layer is first sputtered onto the Si wafer. Then -3kV argon Plasma Source Ion Implantation (PSII) drives the boron atoms into the Si substrate by means of ion beam mixing. This process avoids the hazardous toxic gases, undesirable F co-implantation and F etching effects. Sub-100nm deep p+/n junctions have been formed with this method. Numerical simulations were performed to predict the recoiled boron profiles, which are in agreement with the experimental data. The boron sputter deposition process has been optimized. Auger electron spectroscopy (AES) confirms high purity of the deposited boron films. Numerical Simulations show that the B films with thickness ranging from 5nm to 10nm result in very similar recoiled B profiles. The thickness of 7.5nm is chosen for the deposited B layer to make the entire process more reproducible. Moreover, a part of the implantation damage will be contained in the B layer, which will be removed prior to the annealing step. This should help to alleviate the transient enhanced B diffusion. The research for the recoil implantation of 7.5nm thick B layer is currently underway.

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

    SciTech Connect

    Zhang, Ligang; Chen, Xiufang; Guan, Jing; Jiang, Yijun; Hou, Tonggang; Mu, Xindong

    2013-09-01

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

  5. Electrochemical anchoring of dual doping polypyrrole on graphene sheets partially exfoliated from graphite foil for high-performance supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Song, Yu; Xu, Jun-Li; Liu, Xiao-Xia

    2014-03-01

    Partial exfoliation of graphene from graphite foil (GF) is achieved by a convenient one-step electrochemical exfoliation method to afford partially exfoliated graphene electrode (Ex-GF) with graphene sheets standing on GF matrix stably. Electropolymerization of pyrrole is carried out on Ex-GF with 1,5-naphthalene disulfonate (NDS) and 2-naphthalene sulfonate (NMS) as the 'permanent' doping anions to prepare Ex-GF/PPy-NDS and Ex-GF/PPy-NMS, respectively, in which the polymer is anchoring on the surfaces of graphene sheets. The PPy displays an opened structure due to the facilitated homogeneous nucleation on Ex-GF and so exhibits enhanced specific capacitance compared to the polymers deposited on pristine GF (to afford GF/PPy-NDS and GF/PPy-NMS). Specifically, Ex-GF/PPy-NDS film maintains 79% of its specific capacitance when the discharge current density increases from 1 to 20 A g-1. Moreover, discharge potential window of the polymer is enlarged to 1.3 V (from -0.8 to 0.5 V vs. SCE) due to the dual doping mode. Ex-GF/PPy-NDS film displays a high energy density of 82.4 Wh kg-1 at the power density of 650 W kg-1 and 65.1 Wh kg-1 at the power density of 13 kW kg-1. The cyclic charge/discharge stability of the polymer is also improved due to synergistic effect with partially exfoliated graphene.

  6. Molecular dynamics investigation of separation of hydrogen sulfide from acidic gas mixtures inside metal-doped graphite micropores.

    PubMed

    Huang, Pei-Hsing

    2015-09-21

    The separation of poisonous compounds from various process fluids has long been highly intractable, motivating the present study on the dynamic separation of H2S in acidic-gas-mixture-filled micropores. The molecular dynamics approach, coupled with the isothermal-isochoric ensemble, was used to model the molecular interactions and adsorption of H2S/CO2/CO/H2O mixtures inside metal-doped graphite slits. Due to the difference in the adsorption characteristics between the two distinct adsorbent materials, the metal dopant in the graphitic micropores leads to competitive adsorption, i.e. the Au and graphite walls compete to capture free adsorbates. The effects of competitive adsorption, coupled with changes in the gas temperature, concentration, constituent ratio and slit width on the constituent separation of mixtures were systematically studied. The molecule-wall binding energies calculated in this work (those of H2S, H2O and CO on Au walls and those of H2O, CO and CO2 on graphite walls) show good agreement with those obtained using density functional theory (DFT) and experimental results. The z-directional self-diffusivities (Dz) for adsorbates inside the slit ranged from 10(-9) to 10(-7) m(2) s(-1) as the temperature was increased from 10 to 500 K. The values are comparable with those for a typical microporous fluid (10(-8)-10(-9) m(2) s(-1) in a condensed phase and 10(-6)-10(-7) m(2) s(-1) in the gaseous state). The formation of H-bonding networks and hydrates of H2S is disadvantageous for the separation of mixtures. The results indicate that H2S can be efficiently separated from acidic gas mixtures onto the Au(111) surface by (i) reducing the mole fraction of H2S and H2O in the mixtures, (ii) raising the gas temperature to the high temperature limit (≥400 K), and (iii) lowering the slit width to below the threshold dimension (≤23.26 Å). PMID:26256825

  7. Growth of boric acid crystallites on the surface of boron-doped silicon carbide samples

    SciTech Connect

    Vassen, R.; Stoever, D.

    1996-06-01

    White crystallites were visually observed on fractured or polished surfaces of SiC samples (grain sizes below {approx}500 nm) during exposure to air at room temperature for several days. Characterization of the crystallites by scanning electron microscopy, secondary ion mass spectroscopy, and X-ray diffraction identified B(OH){sub 3} crystals with a strong (002) texture. The rate of boric acid formation was determined by a gravimetric experiment. The rate of weight gain increased significantly after an incubation period of 1 week. Nucleation is initially the rate-limiting process. Subsequently small B(OH){sub 3} crystals form on the surface, whose growth rate is determined by grain boundary diffusion of boron to the SiC surface. An estimated grain boundary boron to the SiC surface. An estimated grain boundary diffusion coefficient of boron in SiC was many orders of magnitude higher than extrapolated literature values.

  8. All-inorganic colloidal silicon nanocrystals—surface modification by boron and phosphorus co-doping

    NASA Astrophysics Data System (ADS)

    Fujii, Minoru; Sugimoto, Hiroshi; Imakita, Kenji

    2016-07-01

    Si nanocrystals (Si-NCs) with extremely heavily B- and P-doped shells are developed and their structural and optical properties are studied. Unlike conventional Si-NCs without doping, B and P co-doped Si-NCs are dispersible in alcohol and water perfectly without any surface functionalization processes. The colloidal solution of co-doped Si-NCs is very stable and no precipitates are observed for more than 5 years. The co-doped colloidal Si-NCs exhibit size-controllable photoluminescence (PL) in a very wide energy range covering 0.85 to 1.85 eV. In this paper, we summarize the structural and optical properties of co-doped Si-NCs and demonstrate that they are a new type of environmentally-friendly nano-light emitter working in aqueous environments in the visible and near infrared (NIR) ranges.

  9. All-inorganic colloidal silicon nanocrystals-surface modification by boron and phosphorus co-doping.

    PubMed

    Fujii, Minoru; Sugimoto, Hiroshi; Imakita, Kenji

    2016-07-01

    Si nanocrystals (Si-NCs) with extremely heavily B- and P-doped shells are developed and their structural and optical properties are studied. Unlike conventional Si-NCs without doping, B and P co-doped Si-NCs are dispersible in alcohol and water perfectly without any surface functionalization processes. The colloidal solution of co-doped Si-NCs is very stable and no precipitates are observed for more than 5 years. The co-doped colloidal Si-NCs exhibit size-controllable photoluminescence (PL) in a very wide energy range covering 0.85 to 1.85 eV. In this paper, we summarize the structural and optical properties of co-doped Si-NCs and demonstrate that they are a new type of environmentally-friendly nano-light emitter working in aqueous environments in the visible and near infrared (NIR) ranges. PMID:27189818

  10. Enhanced Growth and Osteogenic Differentiation of Human Osteoblast-Like Cells on Boron-Doped Nanocrystalline Diamond Thin Films

    PubMed Central

    Grausova, Lubica; Kromka, Alexander; Burdikova, Zuzana; Eckhardt, Adam; Rezek, Bohuslav; Vacik, Jiri; Haenen, Ken; Lisa, Vera; Bacakova, Lucie

    2011-01-01

    Intrinsic nanocrystalline diamond (NCD) films have been proven to be promising substrates for the adhesion, growth and osteogenic differentiation of bone-derived cells. To understand the role of various degrees of doping (semiconducting to metallic-like), the NCD films were deposited on silicon substrates by a microwave plasma-enhanced CVD process and their boron doping was achieved by adding trimethylboron to the CH4:H2 gas mixture, the B∶C ratio was 133, 1000 and 6700 ppm. The room temperature electrical resistivity of the films decreased from >10 MΩ (undoped films) to 55 kΩ, 0.6 kΩ, and 0.3 kΩ (doped films with 133, 1000 and 6700 ppm of B, respectively). The increase in the number of human osteoblast-like MG 63 cells in 7-day-old cultures on NCD films was most apparent on the NCD films doped with 133 and 1000 ppm of B (153,000±14,000 and 152,000±10,000 cells/cm2, respectively, compared to 113,000±10,000 cells/cm2 on undoped NCD films). As measured by ELISA per mg of total protein, the cells on NCD with 133 and 1000 ppm of B also contained the highest concentrations of collagen I and alkaline phosphatase, respectively. On the NCD films with 6700 ppm of B, the cells contained the highest concentration of focal adhesion protein vinculin, and the highest amount of collagen I was adsorbed. The concentration of osteocalcin also increased with increasing level of B doping. The cell viability on all tested NCD films was almost 100%. Measurements of the concentration of ICAM-1, i.e. an immunoglobuline adhesion molecule binding inflammatory cells, suggested that the cells on the NCD films did not undergo significant immune activation. Thus, the potential of NCD films for bone tissue regeneration can be further enhanced and tailored by B doping and that B doping up to metallic-like levels is not detrimental for cells. PMID:21695172

  11. Nitrogen- and boron-co-doped core-shell carbon nanoparticles as efficient metal-free catalysts for oxygen reduction reactions in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Zhong, Shengkui; Zhou, Lihua; Wu, Ling; Tang, Lianfeng; He, Qiyi; Ahmed, Jalal

    2014-12-01

    The most severe bottleneck hindering the widespread application of fuel cell technologies is the difficulty in obtaining an inexpensive and abundant oxygen reduction reaction (ORR) catalyst. The concept of a heteroatom-doped carbon-based metal-free catalyst has recently attracted interest. In this study, a metal-free carbon nanoparticles-based catalyst hybridized with dual nitrogen and boron components was synthesized to catalyze the ORR in microbial fuel cells (MFCs). Multiple physical and chemical characterizations confirmed that the synthetic method enabled the incorporation of both nitrogen and boron dopants. The electrochemical measurements indicated that the co-existence of nitrogen and boron could enhance the ORR kinetics by reducing the overpotential and increasing the current density. The results from the kinetic studies indicated that the nitrogen and boron induced an oxygen adsorption mechanism and a four-electron-dominated reaction pathway for the as-prepared catalyst that was very similar to those induced by Pt/C. The MFC results showed that a maximum power density of ∼642 mW m-2 was obtained using the as-prepared catalyst, which is comparable to that obtained using expensive Pt catalyst. The prepared nitrogen- and boron-co-doped carbon nanoparticles might be an alternative cathode catalyst for MFC applications if large-scale applications and price are considered.

  12. Adsorption of SO2 molecule on doped (8, 0) boron nitride nanotube: A first-principles study

    NASA Astrophysics Data System (ADS)

    Deng, Zun-Yi; Zhang, Jian-Min; Xu, Ke-Wei

    2016-02-01

    Adsorptions of SO2 on Al-, Ca-, Co-, Cu-, Ge-, Ni-, and Si-doped (8, 0) boron nitride nanotube (BNNT) have been studied using first-principles approach based on density functional theory in order to exploit their potential applications as SO2 gas sensors. The electronic properties of the BNNT-molecule adsorption adducts are strongly dependent on the dopants. The most stable adsorption geometries, adsorption energies, charge transfers, and density of states of these systems are thoroughly discussed. This work reveals that the sensitivity of (8, 0) BNNT based chemical gas sensors for SO2 can be drastically improved by introducing appropriate dopant. Si is found to be the best choice among all the dopants.

  13. Modification of the surface morphology of the silicon substrate for boron-doped diamond electrodes in electrochemical wastewater treatment applications

    NASA Astrophysics Data System (ADS)

    Bak, Ji-Yoon; Lee, Choong-Hyun; Kim, Jung-Do; Lim, Dae-Soon

    2016-01-01

    For electrochemical wastewater treatment applications, textured boron-doped diamond (BDD) electrodes were fabricated by using a simple and cost-effective etching process. On the basis of the surface area measurement, the etching time was optimized in order to achieve higher electrochemical wastewater treatment performance. The surface structure, electrochemical properties, and electrochemical oxidation performance of the electrodes were characterized by using Raman spectroscopy and atomic force microscopy, in addition to electrochemical techniques. The textured BDD electrode demonstrated a dense and large surface area with no change in the film's properties. The effective surface area of the textured BDD electrode was approximately twice as large as that of the planar BDD electrode. The electrochemical results clearly demonstrate that the enhanced surface area of the BDD electrode achieves a higher current efficiency and much lower energy consumption in the electrochemical oxidation of methyl-orange.

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

    NASA Astrophysics Data System (ADS)

    Spătaru, Tanţa; Marcu, Maria; Spătaru, Nicolae

    2013-03-01

    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.

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

    PubMed

    Yardım, Yavuz; Keskin, Ertugrul; Şentürk, Zühre

    2013-11-15

    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 60 s 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 0.107 µg mL(-1) (5.51×10(-7) M) for CAF, and 0.448 µg mL(-1) (1.26×10(-6) M) for CGA. The practical applicability of this methodology was tested in commercially available beverage samples. PMID:24148509

  16. Development of Sensitive Analytical Approach for the Quantification of α-Lipoic Acid Using Boron Doped Diamond Electrode.

    PubMed

    Stankovic, Dalibor M; Mehmeti, Eda; Kalcher, Kurt

    2016-01-01

    A boron doped diamond (BDD) electrode was investigated for use as an electrochemical sensor for α-lipoic acid (LA) using amperometric and differential pulse voltammetric detection. LA displays a well expressed oxidation peak at +0.9 V vs. Ag/AgCl in solutions with a pH value of 3. It was found that signals obtained are linearly related to the concentration range from 0.3 to 105 μM with detection limit of 0.088 μM. Interferences by common compounds such as ascorbic acid, uric acid and dopamine were tested and the method was successfully applied to the determination of LA in human body fluids where it gave recoveries in the range from 95 to 97%. PMID:27506710

  17. Chemometric study on the electrochemical incineration of nitrilotriacetic acid using platinum and boron-doped diamond anode.

    PubMed

    Zhang, Chunyong; He, Zhenzhu; Wu, Jingyu; Fu, Degang

    2015-07-01

    This study investigated the electrochemical incineration of nitrilotriacetic acid (NTA) at boron-doped diamond (BDD) and platinum (Pt) anodes. Trials were performed in the presence of sulfate electrolyte media under recirculation mode. The parameters that influence the degradation efficiency were investigated, including applied current density, flow rate, supporting electrolyte concentration and reaction time. To reduce the number of experiments, the system had been managed under chemometric technique named Doehlert matrix. As a consequence, the mineralization of NTA demonstrated similar behavior upon operating parameters on these two anodes. Further kinetic study indicated that the degradations followed pseudo-first-order reactions for both BDD and Pt anodes, and the reaction rate constant of the former was found to be higher than that of the latter. Such difference could be interpreted by results from fractal analysis. In addition, a reaction sequence for NTA mineralization considering all the detected intermediates was also proposed. PMID:25747300

  18. Enhanced field emission characteristics of boron doped diamond films grown by microwave plasma assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Koinkar, Pankaj M.; Patil, Sandip S.; Kim, Tae-Gyu; Yonekura, Daisuke; More, Mahendra A.; Joag, Dilip S.; Murakami, Ri-ichi

    2011-01-01

    Boron doped diamond films were synthesized on silicon substrates by microwave plasma chemical vapor deposition (MPCVD) technique. The effect of B 2O 3 concentration varied from 1000 to 5000 ppm on the field emission characteristics was examined. The surface morphology and quality of films were characterized by scanning electron microscope (SEM) and Raman spectroscopy. The surface morphology obtained by SEM showed variation from facetted microcrystal covered with nanometric grains to cauliflower of nanocrystalline diamond (NCD) particles with increasing B 2O 3 concentration. The Raman spectra confirm the formation of NCD films. The field emission properties of NCD films were observed to improve upon increasing boron concentration. The values of the onset field and threshold field are observed to be as low as 0.36 and 0.08 V/μm, respectively. The field emission current stability investigated at the preset value of ˜1 μA is observed to be good, in each case. The enhanced field emission properties are attributed to the better electrical conductivity coupled with the nanometric features of the diamond films.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  20. Effect of reaction conditions on methyl red degradation mediated by boron and nitrogen doped TiO2

    NASA Astrophysics Data System (ADS)

    Galenda, A.; Crociani, L.; Habra, N. El; Favaro, M.; Natile, M. M.; Rossetto, G.

    2014-09-01

    Nowadays the employment of renewable and sustainable energy sources, and solar light as main option, becomes an urgent need. Photocatalytic processes received great attention in wastewater treatment due to their cheapness, environmental compatibility and optimal performances. Despite the general low selectivity of the photocatalysts, an accurate optimisation of the operational parameters needs to be carried out in order to maximise the process yield. Because of this reason, the present contribution aims to deepen either the knowledge in boron and/or nitrogen doped TiO2-based systems and their employment in methyl red removal from aqueous solutions. The samples were obtained by coprecipitation and characterised by XRD, SEM, BET specific surface area, UV-vis and XPS techniques. The catalytic activity was for the first time carefully evaluated with respect to methyl red photodegradation in different conditions as a function of working pH, counter-ions and pre-adsorption time. An ad-hoc study was performed on the importance of the pre-adsorption of the dye, suggesting that an extended adsorption is useless for the catalyst photoactivity, while a partial coverage is preferable. The photocatalytic tests demonstrate the positive influence of boron doping in photo-activated reactions and the great importance of the operational parameters with respect to the simple methyl red bleaching rather than the overall pollutant mineralisation. It is proved, indeed, that different working pH, acidifying means and substrate pre-adsorption time can enhance or limit the catalyst performances with respect to the complete pollutant degradation rather than its partial breakage.

  1. First-principles study on the adsorption properties of phenylalanine on carbon graphitic structures

    NASA Astrophysics Data System (ADS)

    Kang, Seoung-Hun; Kwon, Dae-Gyeon; Park, Sora; Kwon, Young-Kyun

    2015-12-01

    Using ab-initio density functional theory, we investigate the binding properties of phenylalanine, an amino acid, on graphitic carbon structures, such as graphene, nanotubes, and their modified structures. We focus especially on the effect of the adsorbate on the geometrical and the electronic structures of the absorbents. The phenylalanine molecule is found to bind weakly on pristine graphitic structures with a binding energy of 40-70 meV and not to change the electronic configuration of the graphitic structures, implying that the phenylalanine molecule may not be detected on pristine graphitic structures. On the other hand, the phenylalanine molecule exhibits a substantial increase in its binding energy up to ~2.60 eV on the magnesium-decorated boron-doped graphitic structures. We discover that the Fermi level of the system, which was shifted below the Dirac point of the graphitic structures due to p-doping by boron substitution, can be completely restored to the Dirac point because of the amino acid adsorption. This behavior implies that such modified structures can be utilized to detect phenylalanine molecules.

  2. Molecular dynamics investigations of boron doping in a-Si:H

    SciTech Connect

    Fedders, P.A.; Drabold, D.A.

    1997-07-01

    The rather low doping efficiency of B in a-Si:H is almost always explained by the argument that almost all of the B is incorporated into three-fold coordinated sites and that B is inert or non-doping in this configuration. Using ab initio molecular dynamics, the authors have studied the energetics and doping (electronic structure) consequences of B incorporation into a-Si:H both with and without H passivation. Their results suggest that the conventional view is in error and that the low doping efficiency is primarily due to H passivation. These results are consistent with the low doping efficiency of B as well as NMR studies on the large electric field gradients experienced by the B atoms and on NMR double resonance studies of B-H neighboring distances.

  3. Control of Rewriteable Doping Patterns in Graphene/Boron Nitride Heterostructures

    NASA Astrophysics Data System (ADS)

    Kahn, Salman; Velasco, Jairo, Jr.; Wong, Dillon; Lee, Juwon; Tsai, Hsin Zon; Ju, Long; Jiang, Lili; Shi, Zhiwen; Ashby, Paul; Taniguchi, Takashi; Watanabe, Kenji; Zettl, Alex; Wang, Feng; Crommie, Michael

    Spatial control of charge doping in 2D materials is a promising technique for designing future electronic devices and understanding novel physics. Electrostatic gating and chemical doping are common methods to achieve control of charge doping in 2D materials. However, these approaches suffer from complicated fabrication processes that introduce impurities, change material properties irreversibly, and lack flexibility. Here, we introduce a new method for patterning rewriteable doping profiles with local interface charge transfer from defects in a tunable BN substrate into an adjacent layer of graphene. We characterize these spatial doping patterns through local probe and transport techniques. This technique enables many novel device designs for 2D materials, including atomically thin p-n junctions and rewriteable memory devices.

  4. Physics and modeling of ion implantation induced transient deactivation and diffusion processes in boron doped silicon

    NASA Astrophysics Data System (ADS)

    Chakravarthi, Srinivasan

    The economics of silicon processing requires predictive modeling capabilities for the continued rapid advancement of semiconductor technology. This is because it has become prohibitively expensive to develop a new process by running a large series of test lots through multi-billion dollar fabrication facilities. Effective process modeling requires an accurate physical understanding of the various interacting processes. The complexity of this problem is compounded by highly non-equilibrium phenomena associated with IC fabrication processes such as implantation annealing. Point defect supersaturations of many orders of magnitude are introduced following ion implantation, which is used to introduce the dopants into silicon. Such supersaturations dramatically alter the diffusion of dopants and reduce the electrical activation during the initial phase of the anneal. Boron is the primary p-type dopant used in silicon and thus understanding and modeling its deactivation/activation and diffusion is critical to predictive process simulation. Since boron is smaller than silicon, boron agglomerates with interstitials becoming electrically inactive. Modeling of boron clusters is complicated, as there is a huge array of potential boron-interstitial cluster compositions. A physical model for boron clustering is derived by identifying dominant clusters and rate limiting steps via atomistic calculations performed at Lawrence Livermore National Labs. The model is then used successfully to match a wide variety of chemical and electrical data. We further apply this model to understand and successfully predict ultra shallow junction formation. We find it is possible to explain some intriguing phenomenon observed during the formation of ultra shallow junctions, like saturation in junction depth despite increasing ramp-up rates. Researchers are exploring novel experimental processing steps like high energy Si pre-implants to produce highly active and shallow B junctions. To understand

  5. Precipitation control and activation enhancement in boron-doped p+-BaSi2 films grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Khan, M. Ajmal; Nakamura, K.; Du, W.; Toko, K.; Usami, N.; Suemasu, T.

    2014-06-01

    Precipitation free boron (B)-doped as-grown p+-BaSi2 layer is essential for the BaSi2 p-n junction solar cells. In this article, B-doped p-BaSi2 layers were grown by molecular beam epitaxy on Si(111) substrates, and the influence of substrate growth temperature (TS) and B temperature (TB) in the Knudsen cell crucible were investigated on the formation of B precipitates and the activation efficiency. The hole concentration, p, reached 1.0 × 1019 cm-3 at room temperature for TS = 600 and TB = 1550 °C. However, the activation rate of B was only 0.1%. Furthermore, the B precipitates were observed by transmission electron microscopy (TEM). When the TS was raised to 650 °C and the TB was decreased to 1350 °C, the p reached 6.8 × 1019 cm-3, and the activation rate increased to more than 20%. No precipitation of B was also confirmed by TEM.

  6. Use of zirconium-phosphate-carbonate chemistry to immobilize polycyclic aromatic hydrocarbons on boron-doped diamond.

    PubMed

    Mazur, Maciej; Krysiński, Paweł; Blanchard, G J

    2005-09-13

    We report on the formation of monomolecular layers of perylene- and pyrene-alkanoic acids on boron-doped diamond (BDD) substrates. The carboxylic acid layers are bound by coordination to zirconium phosphate (ZP) functionalities on the BDD substrate surface. The resulting Zr-phosphate-carbonate (ZPC) linkages between the substrate and the adlayer are asymmetric, of the form -(OPO3(2-) Zr4+-O2C-R)+ X-. Pyrene and perylene are well-established optical probes of polarity and viscosity at interfaces. We have used electrochemical and steady-state fluorescence techniques to study the loading density and behavior of these monomolecular films, allowing comparison of BDD and indium-doped tin oxide (ITO) substrates. Electrochemical data suggest that the pyrene chromophores are positioned roughly at the same distance from the surface, regardless of the length of the anchoring alkanoic acid chain, a finding that can be explained by the pyrene lying on the substrate surface. Such a conformation is plausible given the surface coverage (5 x 10(-11) mol/cm2, ca. 0.1 monolayer) we measure for these systems. PMID:16142963

  7. Thermodynamical and thermoelectric properties of boron doped YPd3 and YRh3

    NASA Astrophysics Data System (ADS)

    Dwivedi, Shalini; Sharma, Ramesh; Sharma, Yamini

    2016-05-01

    The structural, electronic, thermal, and optical properties of borides of cubic non-magnetic YX3 (X=Rh, Pd) compounds and their borides which crystallize in the AuCu3 structure have been studied using the density functional theory (DFT). The flat bands in the vicinity of EF which are associated with superconductivity appear in YPd3 and YRh3 band structures. However, the B s-states enhance the flat band only in YRh3B. The optical properties clearly show that boron insertion modifies the absorption and transmittance. The YX3 alloys and their borides exhibit valuable changes in the thermopower and ZT. It is observed that the properties of the Y-X intermetallics change significantly for the Y-Rh and Y-Pd alloys and the presence of single boron atom modifies the properties to a great extent.

  8. Hydrogenation kinetics in oxidized boron-doped silicon irradiated by keV electrons

    NASA Astrophysics Data System (ADS)

    Lin, Wallace Wan-Li; Sah, Chih-Tang

    1988-08-01

    Hydrogenation kinetics of boron acceptors in oxidized silicon during and after repeated 8-keV electron irradiation (225-2700-μC/cm2 stresses and 10-168-h interirradiation anneals) at room temperature are reported. Hydrogenation proceeds rapidly during irradiation but continues for many hours after the 8-keV electron beam is removed. Postoxidation process dependencies show that postoxidation and postmetallization annealing processes reduce the hydrogenation effect during the 8-keV electron irradiation, while exposure of the oxide to water prior to aluminum electrode deposition enhances it. The data can be interpreted by our two-reaction model consisting of the hydrogen capture reaction by the boron acceptor and the hydrogen recombination reaction to form hydrogen molecule.

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

    PubMed

    Boukari, Khaoula; Sonnet, Philippe; Duverger, Eric

    2012-12-01

    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

  10. Control of Rewriteable Doping Patterns in Graphene/Boron Nitride Heterostructures

    NASA Astrophysics Data System (ADS)

    Kahn, Salman; Velasco, Jairo, Jr.; Wong, Dillon; Lee, Juwon; Tsai, Hsin Zon; Ju, Long; Jiang, Lili; Shi, Zhiwen; Ashby, Paul; Taniguchi, Takashi; Watanabe, Kenji; Zettl, Alex; Wang, Feng; Crommie, Michael

    Spatial control of charge doping in 2D materials is a prerequisite for designing future electronic devices and understanding novel physics. Electrostatic gating and chemical doping are two of the most common methods to achieve this. However, these approaches suffer from complicated fabrication processes that introduce impurities, change material properties irreversibly, and lack flexibility. Here we introduce a new method for patterning rewriteable doping profiles using an STM tip by way of local tip-voltage-induced ionization of defects in a BN substrate. We characterize these spatial doping patterns through local probe and transport techniques. This technique enables many novel device designs for 2D materials, including atomically thin p-n junctions and rewriteable memory devices.

  11. Evidence for substitutional boron in doped single-walled carbon nanotubes

    SciTech Connect

    Ayala, P.; Pichler, T.; Reppert, J.; Rao, A. M.; Grobosch, M.; Knupfer, M.

    2010-05-03

    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.

  12. Electrical properties and hyperfine interactions of boron doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Amir, Md; Ünal, B.; Geleri, M.; Güngüneş, H.; Shirsath, Sagar E.; Baykal, A.

    2015-12-01

    The single spinel phase nano-structured particles of FeBxFe2-xO4 (x = 0.1, 0.2, 0.3, 0.4 and 0.5) were synthesized by the glycothermal method and the effect of B3+ substitution on structural and dielectric properties of Fe3O4 were studied. From 57Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values on B3+ substitution have been determined. The hyperfine field values at B- and A-sites gradually decrease with increasing B3+ ion concentration (x). The cation distributions obtained from Bertaut method are in line with Mössbauer results. Complex impedance analysis of boron-substituted spinel ferrites have been made extensively in order to investigate the significant changes in ac and dc conductivity as well as complex permittivity when the boron composition ratio varies from 0.1 to 0.5. It is found that both ac and dc conductivity are also dependent on the boron content in addition to both temperature and applied frequency. The dc conductivity tendency does not purely obey the Arrhenius plots. The dielectric constant and loss of complex permittivity, in general, show similar attitudes as seen in some nanocomposites containing spinel ferrites except for some fluctuations and shifts along the characteristics of the curves. Furthermore, their imaginary components of both permittivity and modulus are almost found to obey the power law with any exponent values varying between 0.5 and 2 in accordance with the level of boron concentrations.

  13. Boron Doped Nanocrystalline Film with Improved Work Function as a Buffer Layer in Thin Film Silicon Solar Cells.

    PubMed

    Park, Jinjoo; Shin, Chonghoon; Park, Hyeongsik; Jung, Junhee; Lee, Youn-Jung; Bong, Sungjae; Dao, Vinh Ai; Balaji, Nagarajan; Yi, Junsin

    2015-03-01

    We investigated thin film silicon solar cells with boron doped hydrogenated nanocrystalline silicon/ hydrogenated amorphous silicon oxide [p-type nc-Si:H/a-SiOx:H] layer. First, we researched the bandgap engineering of diborane (B2H6) doped wide bandgap hydrogenated nanocryslline silicon (p-type nc-Si:H) films, which have excellent electrical properties of high dark conductivity, and low activation energy. The films prepared with lower doping ratio and higher hydrogen dilution ratio had higher optical gap (Eg), with higher dark conductivity (σ(d)), and lower activation energy (Ea). We controlled Eg from 2.10 eV to 1.75 eV, with σ(d) from 1.1 S/cm to 7.59 x 10(-3) S/cm, and Ea from 0.040 eV to 0.128 eV. Next, we focused on the fabrication of thin film silicon solar cells. By inserting p-type nc-Si:H film into the thin film silicon solar cells, we achieved a remarkable increase in the built-in potential from 0.803 eV to 0.901 eV. By forming p-type nc-Si:H film between SnO2:F/ZnO:Al (30 nm) and p-type a-SiOx:H layer, the solar cell properties of open circuit voltage (Voc), short circuit current density (Jsc), and efficiency (η) were improved by 3.7%, 9.2%, and 9.8%, respectively. PMID:26413646

  14. Roughness-based monitoring of transparency and conductivity in boron-doped ZnO thin films prepared by spray pyrolysis

    SciTech Connect

    Gaikwad, Rajendra S.; Bhande, Sambhaji S.; Mane, Rajaram S.; Pawar, Bhagwat N.; Gaikwad, Sanjay L.; Han, Sung-Hwan; Joo, Oh-Shim

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► We report surface roughness dependent transparency and conductivity in ZnO films. ► The surface roughness with respected to boron doping concentrations is studied. ► Boron doped and pristine Zinc oxide thin films have showed ≥95% transmittance. ► Increased carrier concentration of 9.21 × 10{sup 21} cm{sup −3} revealed from Hall measurement. -- Abstract: Sprayed polycrystalline ZnO and boron-doped ZnO thin films composed of spherical grains of 25–32 nm in diameters are used in roughness measurement and further correlated with the transparency and the conductivity characteristics. The surface roughness is increased up to Zn{sub 0.98}B{sub 0.02}O and then declined at higher boron concentrations. The sprayed ZnO films revealed ≥95% transmittance in the visible wavelength range, 1.956 × 10{sup −4} Ω cm electrical resistivity, 46 cm{sup 2}/V s Hall mobility and 9.21 × 10{sup 21} cm{sup −3} charge carrier concentration. The X-ray photoelectron spectroscopy study has confirmed 0.15 eV binding energy change for Zn 2p{sub 3/2} when 2 at% boron content is mixed without altering electro-optical properties substantially. Finally, using soft modeling importance of these textured ZnO over non-textured films for enhancing the solar cells performance is explored.

  15. Adsorption of diazinon and hinosan molecules on the iron-doped boron nitride nanotubes surface in gas phase and aqueous solution: A computational study

    NASA Astrophysics Data System (ADS)

    Farmanzadeh, Davood; Rezainejad, Hamid

    2016-02-01

    In this study, the geometric structures and electronic properties of two widely used organophosphorus pesticides, diazinon and hinosan, boron nitride nanotubes (BNNTs) and Fe doped boron nitride nanotubes (FeBNNTs) as adsorbents of these pesticides are studied by density functional theory calculation as well as dispersion correction by Grimme method. The results show that Fe doping in boron nitride nanotubes structures increases the potency of nanotubes to adsorb mentioned pesticides, especially when Fe atom located instead of N atom. Comparing the adsorption energies of diazinon on FeBNNTs with ones for hinosan demonstrate that the adsorption of hinosan is energetically more favorable by FeBNNTs. Assessment of adsorption energies in aqueous solution confirmed significant decrease in their values compared to ones in gaseous phase. However, the adsorption of diazinon and hinosan on both BNNTs and FeBNNTs are exothermic. So, BNNTs and FeBNNTs may be promising candidates as appropriate adsorbents for adsorbing diazinon and hinosan. Also, the results of calculations have revealed that van der Waals interaction energies are remarkably large in adsorption of diazinon and hinosan on all boron nitride nanotubes.

  16. Nitrogen-Doped Hollow Amorphous Carbon Spheres@Graphitic Shells Derived from Pitch: New Structure Leads to Robust Lithium Storage.

    PubMed

    Ma, Qingtao; Wang, Luxiang; Xia, Wei; Jia, Dianzeng; Zhao, Zongbin

    2016-02-12

    Nitrogen-doped mesoporous hollow carbon spheres (NHCS) consisting of hybridized amorphous and graphitic carbon were synthesized by chemical vapor deposition with pitch as raw material. Treatment with HNO3 vapor was performed to incorporate oxygen-containing groups on NHCS, and the resulting NHCS-O showed excellent rate capacity, high reversible capacity, and excellent cycling stability when tested as the anode material in lithium-ion batteries. The NHCS-O electrode maintained a reversible specific capacity of 616 mAh g(-1) after 250 cycles at a current rate of 500 mA g(-1) , which is an increase of 113 % compared to the pristine hollow carbon spheres. In addition, the NHCS-O electrode exhibited a reversible capacity of 503 mAh g(-1) at a high current density of 1.5 A g(-1) . The superior electrochemical performance of NHCS-O can be attributed to the hybrid structure, high N and O contents, and rich surface defects. PMID:26751009

  17. Effective performance for undoped and boron-doped double-layered nanoparticles-copper telluride and manganese telluride on tungsten oxide photoelectrodes for solar cell devices.

    PubMed

    Srathongluan, Pornpimol; Vailikhit, Veeramol; Teesetsopon, Pichanan; Choopun, Supab; Tubtimtae, Auttasit

    2016-11-01

    This work demonstrates the synthesis of a novel double-layered Cu2-xTe/MnTe structure on a WO3 photoelectrode as a solar absorber for photovoltaic devices. Each material absorber is synthesized using a successive ionic layer adsorption and reaction (SILAR) method. The synthesized individual particle sizes are Cu2-xTe(17) ∼5-10nm and MnTe(3) ∼2nm, whereas, the aggregated particle sizes of undoped and boron-doped Cu2-xTe(17)/MnTe(11) are ∼50 and 150nm, respectively. The larger size after doping is due to the interconnecting of nanoparticles as a network-like structure. A new alignment of the energy band is constructed after boron/MnTe(11) is coated on boron/Cu2-xTe nanoparticles (NPs), leading to a narrower Eg equal to 0.58eV. Then, the valence band maximum (VBM) and conduction band minimum (CBM) with a trap state are also up-shifted to near the CBM of WO3, leading to the shift of a Fermi level for ease of electron injection. The best efficiency of 1.41% was yielded for the WO3/boron-doped [Cu2-xTe(17)/MnTe(11)] structure with a photocurrent density (Jsc)=16.43mA/cm(2), an open-circuit voltage (Voc)=0.305V and a fill factor (FF)=28.1%. This work demonstrates the feasibility of this double-layered structure with doping material as a solar absorber material. PMID:27451035

  18. An intensified π-hole in beryllium-doped boron nitride meshes: its determinant role in CO2 conversion into hydrocarbon fuels.

    PubMed

    Azofra, Luis Miguel; MacFarlane, Douglas R; Sun, Chenghua

    2016-02-28

    DFT investigations on beryllium-doped boron nitride meshes or sheets (BNs) predict the existence of a very reactive kind of novel material capable of spontaneously reducing the first hydrogenation step in the CO2 conversion mechanism. This impressive behaviour appears as a result of the very deep π-hole generated by the beryllium moieties, and also determines its selectivity towards the production of CH4. PMID:26841973

  19. Synthesis, Characterization, and Tribological Evaluation of TiO2-Reinforced Boron and Nitrogen co-Doped Reduced Graphene Oxide Based Hybrid Nanomaterials as Efficient Antiwear Lubricant Additives.

    PubMed

    Jaiswal, Vinay; Kalyani; Umrao, Sima; Rastogi, Rashmi B; Kumar, Rajesh; Srivastava, Anchal

    2016-05-11

    The microwave-synthesized reduced graphene oxide (MRG), boron-doped reduced graphene oxide (B-MRG), nitrogen-doped reduced graphene oxide (N-MRG), boron-nitrogen-co-doped reduced graphene oxide (B-N-MRG), and TiO2-reinforced B-N-MRG (TiO2-B-N-MRG) nanomaterials have been synthesized and characterized by various state-of-the-art techniques, like Raman spectroscopy, powder X-ray diffraction, scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Furthermore, the tribological properties of prepared nanomaterials as antiwear additives in neutral paraffin oil have been evaluated using a four-ball machine at an optimized additive concentration (0.15% w/v). The tribological parameters, like mean wear scar diameter, coefficient of friction, and wear rates, revealed that these nanomaterials have potential to be developed as environmentally friendly sulfated-ash-, phosphorus-, and sulfur-free antiwear lubricant additives. The friction- and wear-reducing behavior of MRG increased upon successive doping of nitrogen, boron, and both nitrogen and boron. Among these additives, B-N-co-doped MRG shows superior tribological behavior in paraffin base oil. Besides this, the load-carrying properties of B-N-co-doped MRG have significantly improved after its reinforcement with TiO2 nanoparticles. A comparative study of the surface morphology of a lubricated track in the presence of various additives has been assessed by SEM and contact-mode atomic force microscopy. The X-ray photoelectron spectroscopy studies have proved that the excellent lubrication properties of TiO2-B-N-MRG are due to the in situ formation of a tribofilm composed of boron nitride, adsorbed graphene layers, and tribosintered TiO2 nanoparticles during the tribocontact. Being sulfur-, halogen-, and phosphorus-free, these graphene-based nanomaterials act as green antiwear additives, protecting interacting

  20. Simultaneous voltammetric determination of paracetamol and ascorbic acid using a boron-doped diamond electrode modified with Nafion and lead films.

    PubMed

    Tyszczuk-Rotko, Katarzyna; Bęczkowska, Ilona; Wójciak-Kosior, Magdalena; Sowa, Ireneusz

    2014-11-01

    The paper describes the fabrication and application of a novel sensor (a boron-doped diamond electrode modified with Nafion and lead films) for the simultaneous determination of paracetamol and ascorbic acid by differential pulse voltammetry. The main advantage of the lead film and polymer covered boron-doped diamond electrode is that the sensitivity of the stripping responses is increased and the separation of paracetamol and ascorbic acid signals is improved due to the modification of the boron-doped diamond surface by the lead layer. Additionally, the repeatability of paracetamol and ascorbic acid signals is improved by the application of the Nafion film coating. In the presence of oxygen, linear calibration curves were obtained in a wide concentration range from 5×10(-7) to 2×10(-4) mol L(-1) for paracetamol and from 1×10(-6) to 5×10(-4) mol L(-1) for ascorbic acid. The analytical utility of the differential pulse voltammetric method elaborated was tested in the assay of paracetamol and ascorbic acid in commercially available pharmaceutical formulations and the method was validated by high performance liquid chromatography coupled with diode array detector. PMID:25127609

  1. Theoretical Studies of Oxygen Reactivity of Free-Standing and Supported Boron-Doped Graphene.

    PubMed

    Di Valentin, Cristiana; Ferrighi, Lara; Fazio, Gianluca

    2016-05-23

    Graphene inertness towards chemical reactivity can be considered as an accepted postulate by the research community. This limit has been recently overcome by chemically and physically modifying graphene through non-metal doping or interfacing with acceptor/donor materials (metals or semiconductors). As a result, outstanding performances as catalytic, electrocatalytic, and photocatalytic material have been observed. In this critical Review we report computational work performed, by our group, on the reactivity of free-standing, metal- and semiconductor-supported B-doped graphene towards oxygen, which is at the basis of extremely important energy-related chemical processes, such as the oxygen reduction reaction. It appears that a combination of doping and interfacing approaches for the activation of graphene can open unconventional and unprecedented reaction paths, thus boosting the potential of modified graphene in many chemical applications. PMID:27031193

  2. Effects of glucose doping on the MgB2 superconductors using cheap crystalline boron

    NASA Astrophysics Data System (ADS)

    Parakkandy, Jafar Meethale; Shahabuddin, Mohammed; Shah, M. Shahabuddin; Alzayed, Nasser S.; Qaid, Salem A. S.; Madhar, Niyaz Ahmad; Ramay, Shahid M.; Shar, Muhammad Ali

    2015-12-01

    We report the effect of glucose (C6H12O6) doping on the structural and electromagnetic properties of MgB2 superconductor fabricated by dry mixing using planetary ball milling. Herein, as-prepared bulk polycrystalline Mg (B1-xCx) 2 samples with different doping levels (x = 0, 2, 4, and 6 at. %) were systematically studied by X-ray diffraction, magnetic and resistivity measurements, and microstructure analysis. When carbon doped, the reduction in critical transition temperature and shrinkage in a-lattice were obviously observed. This resulted in structural distortion of the MgB2 lattice, and thereby, enhanced an impurity scattering. In addition to these, upper critical field and high-field critical current densities were also enhanced. On the other hand, both pinning force and low-field critical current density are decreased. The high field enhancement and low field degradation are due to increase in impurity scattering and decrease in pinning force respectively.

  3. A new assisted molecular cycloaddition on boron doped silicon surfaces: a predictive DFT-D study.

    PubMed

    Boukari, Khaoula; Duverger, Eric; Stauffer, Louise; Sonnet, Philippe

    2014-06-28

    In the framework of the Density Functional Theory (DFT-D), we investigate the phthalocyanine (H2Pc) molecule adsorption on SiC(0001)3 × 3 and Si(111)√3 × √3R30°-B (SiB) surfaces, and particularly compare the involved molecular adsorptions. In the H2Pc-SiC(0001)3 × 3 system, the molecular adsorption can be ascribed to a [10+2] cycloaddition. The H2Pc-SiB system is considered in three cases: defectless SiB surface (denoted SiB-0D) and SiB surfaces presenting one or two boron defects (denoted SiB-1D and SiB-2D respectively). The SiB-0D surface is passivated by a charge transfer from the Si adatoms to the boron atoms and therefore no chemical bond between the molecule and the substrate is observed. A similar molecular adsorption as already evidenced in the H2Pc-SiC(0001)3 × 3 system is involved in the SiB-2D case. In the case of the SiB-1D surface, two Si-N bonds (Si1-N1 and Si2-N2) are observed. One of them, Si1-N1, is nearly similar to that found in the H2Pc-SiB-2D system, but the Si2-N2 bond is unexpected. The Bader charge analysis suggests that, in the presence of the H2Pc molecule, the boron atoms behave like an electron reservoir whose availability varies following the involved molecular adsorption process. In the SiB-1D case, charges are transferred from the substrate to the molecule, allowing the Si2-N2 bond formation. Such a kind of molecular adsorption, not yet observed, could be designed by "assisted pseudo cycloaddition". PMID:24817040

  4. Layered structure of anodic SiO{sub 2} films doped with phosphorus or boron

    SciTech Connect

    Mileshko, L. P.

    2009-12-15

    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}.

  5. Thermodynamical study of boron doped CeX3 (X=Pd, Rh)

    NASA Astrophysics Data System (ADS)

    Sharma, Ramesh; Dwivedi, Shalini; Sharma, Yamini

    2016-05-01

    The structural, electronic, thermal, and optical properties of cubic non magnetic CeX3(X=Pd, Rh) compounds which crystallize in the Au3Cu structure have been studied using the projected augmented wave (PAW) method within the density functional theory (DFT) with generalized gradient approximation (GGA) for exchange correlation potential. In this paper we have calculated the band structure which are interpreted using the density of states. The optical properties such as extinction coefficients clearly illustrate the changes in CeX3 due to intercalation of boron. Lattice instability is observed in CePd3B from the calculated dynamical properties.

  6. Templated self-assembly and local doping of molecules on epitaxial hexagonal boron nitride.

    PubMed

    Schulz, Fabian; Drost, Robert; Hämäläinen, Sampsa K; Liljeroth, Peter

    2013-12-23

    Using low-temperature scanning tunneling microscopy, we show that monolayer hexagonal boron nitride (h-BN) on Ir(111) acts as ultrathin insulating layer for organic molecules, while simultaneously templating their self-assembly. Tunneling spectroscopy experiments on cobalt phthalocyanine (CoPC) reveal narrow molecular resonances and indicate that the charge state of CoPC is periodically modulated by the h-BN moiré superstructure. Molecules in the second layer show site-selective adsorption behavior, allowing the synthesis of molecular dimers that are spatially ordered and inaccessible by usual chemical means. PMID:24152095

  7. Ab initio study of phase transition of boron nitride between zinc-blende and rhombohedral structures

    SciTech Connect

    Nishida, S.; Funashima, H.; Sato, K.; Katayama-Yoshida, H.

    2013-12-04

    Boron nitride has polymorphs such as zinc-blende (c-BN), wurtzite (w-BN), rhombohedral (r-BN), and graphite-like (h-BN) forms. We simulate the direct conversion of r-BN to c-BN through electronic excitation. In our calculation, the conversion is made possible by increasing the hole concentration to over 0.06/atom. This conversion should be experimentally possible by hole-doping via an electric double layer transistor (EDLT) or capacitor.

  8. Brazing graphite to graphite

    DOEpatents

    Peterson, George R.

    1976-01-01

    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.

  9. Electron and photon degradation in aluminum, gallium and boron doped float zone silicon solar cells

    NASA Technical Reports Server (NTRS)

    Rahilly, W. P.; Scott-Monck, J.; Anspaugh, B.; Locker, D.

    1976-01-01

    Solar cells fabricated from Al, Ga and B doped Lopex silicon over a range of resistivities were tested under varying conditions of 1 MeV electron fluence, light exposures and thermal cycling. Results indicate that Al and Ga can replace B as a P type dopant to yield improved solar cell performance.

  10. Evidence of loss of active lithium in titanium-doped LiNi0.5Mn1.5O4/graphite cells

    NASA Astrophysics Data System (ADS)

    Höweling, Andres; Glatthaar, Sven; Nötzel, Dorit; Binder, Joachim R.

    2015-01-01

    Lithium-ion batteries require higher energy densities to meet with a broad acceptance in the fields of electric vehicles and grid storage solutions. LiNi0.5Mn1.5O4 (LNMO) can fulfill this goal due to its high operating voltage. Cycling of LNMO is known to be stable vs. lithium metal anode. Cycling in an LNMO/graphite configuration leads to severe capacity fade. Ti-doped LNMO (LNMTO)/graphite cells experience a lower, but still strong loss of capacity. In order to understand capacity fade, cycling tests of LNMTO vs. graphite and vs. lithium metal were carried out and additionally, three electrode tests were performed. Both cell configurations showed similar Coulombic efficiencies correlating with the applied C-rate. Experimental data and mathematical modeling indicated that loss of active lithium with a constant reaction rate of (3.76 ± 0.46) · 10-8 mol Li h-1 is responsible for capacity fade in LNMTO/graphite cells and that no degradation of the active material occurs. It was concluded that lithium loss also occurs when lithium metal anodes are used. Here, the lithium metal anode can compensate for lithium consumption, as a result of which the capacity is not influenced. Further support for lithium consumption is given by a three-electrode cell with a lithiated graphite anode. The lithium in the graphite anode can compensate the lithium loss for 120 cycles. During this time, the cell experienced hardly any capacity fade and the voltage profile was similar to that of a cell with LNMTO/Li configuration.

  11. Effective catalytic media using graphitic nitrogen-doped site in graphene for a non-aqueous Li-O2 battery: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Yun, Kyung-Han; Hwang, Yubin; Chung, Yong-Chae

    2015-03-01

    The cell performance of lithium-oxygen batteries using nitrogen doped graphene as a catalytic cathode has been validated in recent research, but the cathode reaction mechanism of lithium and oxygen still remains unclear. Since the oxygen reduction reaction (ORR) mechanism by ionic lithium and catalytic surface is predicted to be distinct for different defective sites such as graphitic, pyridinic, and pyrrolic, it is necessary to observe the behavior of ionic lithium and oxygen gas at each defective site in nitrogen doped graphene. In this study, density functional theory (DFT) calculations are adopted to analyze at an atomic scale how effectively each defective site acts as a catalytic cathode. Interestingly, unlike pyridinic or pyrrolic N is known to be the most effective catalytic site for ORR in fuel cells. Among the other defective sites, it is found that the graphitic N site is the most effective catalytic media activating ORR by ionic lithium in lithium-oxygen batteries due to the electron accepting the reaction of Li-O formation by the graphitic N site.

  12. A rapid and sensitive method for hydroxyl radical detection on a microfluidic chip using an N-doped porous carbon nanofiber modified pencil graphite electrode.

    PubMed

    Ouyang, Jun; Li, Zhong-Qiu; Zhang, Jing; Wang, Chen; Wang, Jiong; Xia, Xing-Hua; Zhou, Guo-Jun

    2014-07-01

    Hydroxyl radicals (˙OH) play an important role in human diseases. Traditional detection methods are time consuming and require expensive instruments. Here, we present a simple and sensitive method for the detection of hydroxyl radicals on a microfluidic chip using an electrochemical technique. Aniline monomer is electrochemically polymerized on the surface of a pencil graphite electrode and carbonized at 800 °C. The resulting N-doped porous carbon nanofiber-modified pencil graphite electrode is embedded into a microfluidic chip directly as a working electrode. 4-Hydroxybenzoic acid (4-HBA) is selected as the trapping agent owing to its unique 3,4-DHBA product and high trapping efficiency. A low detection limit of 1.0 × 10(-6) M is achieved on the microfluidic chip. As a demonstration, the microfluidic chip is successfully utilized for the detection of ˙OH in cigarette smoke. The strong π-π stacking and hydrophobic interactions between the nitrogen-doped carbon materials and the pencil graphite make the modified electrode well-suited for the microfluidic chip. PMID:24834984

  13. Optical Properties and Boron Doping-Induced Conduction-Type Change in SnO2 Thin Films

    NASA Astrophysics Data System (ADS)

    Tran, Quang-Phu; Fang, Jau-Shiung; Chin, Tsung-Shune

    2016-01-01

    Boron-doped tin oxide (BTO) films, 0-5 at.% B, were prepared by sol-gel dip coating on a glass substrate. Dried precursor films were post-annealed at a temperature between 400°C and 750°C for 2 h. The obtained BTO thin films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible light (UV-Vis) spectrometry, a four-point probe, and Hall-effect and Seebeck-effect measurements. Optimal optical transmittance was achieved for post-annealed BTO thin film at 700°C. XRD results show a rutile SnO2 structure with a preferred (110) orientation for all the films. The grain size is 47-21 nm, which reduces with increasing B contents. The optical transmittance is 84.6-88.5% at a wavelength of 550 nm and optical band gap of 3.52-3.75 eV. Electrical resistivity is (3.4-8.2) × 10-3 Ω cm, and figure of merit (0.9-4.3) × 10-3 Ω-1. Carrier concentration is (0.97-7.4) × 1020 cm-3 and mobility (2.5-7.8) cm2 V-1 s-1. BTO film with 4 at.% B shows an optimal combination of properties. Conduction type changes from n- (undoped) to p- (1-4 at.% B), then to n-types (5 at.% B), as evidenced from Hall-effect and Seebeck-effect measurements. This is explained by doping-generated defects and phase separations of Sn3O4 and B2O3.

  14. Assessments of the Effect of Increasingly Severe Cathodic Pretreatments on the Electrochemical Activity of Polycrystalline Boron-Doped Diamond Electrodes.

    PubMed

    Brocenschi, Ricardo F; Hammer, Peter; Deslouis, Claude; Rocha-Filho, Romeu C

    2016-05-17

    The electrochemical response of many redox species on boron-doped diamond (BDD) electrodes can be strongly dependent on the type of chemical termination on their surface, hydrogen (HT-BDD) or oxygen (OT-BDD). For instance, on an HT-BDD electrode the [Fe(CN)6](3-/4-) redox system presents a reversible voltammetric behavior, whereas the oxidation overpotential of ascorbic acid (AA) is significantly decreased. Moreover, the electrochemical activity of BDD electrodes can be significantly affected by electrochemical pretreatments, with cathodic pretreatments (CPTs) leading to redox behaviors associated with HT-BDD. Here we report on the effect of increasingly severe CPTs on the electrochemical activity of a highly doped BDD electrode, assessed with the [Fe(CN)6](3-/4-) and AA redox probes, and on the atomic bonding structure on the BDD surface, assessed by XPS. The hydrogenation level of the BDD surface was increased by CPTs, leading to decreases of the total relative level of oxidation of the BDD surface of up to 36%. Contrary to what is commonly assumed, we show that BDD surfaces do not need to be highly hydrogenated to ensure that a reversible voltammetric behavior is obtained for Fe(CN)6](3-/4-); after a CPT, this was attained even when the total relative level of oxidation on the BDD surface was about 15%. At the same time, the overpotential for AA oxidation was confirmed as being very sensitive to the level of oxidation of the BDD surface, a behavior that might allow the use of AA as a secondary indicator of the relative atomic bonding structure on the BDD surface. PMID:27101534

  15. Effect of Polishing on the Friction Behaviors and Cutting Performance of Boron-Doped Diamond Films on WC-Co Inserts

    NASA Astrophysics Data System (ADS)

    Wang, Liang; Shen, Bin; Sun, Fanghong; Zhang, Zhiming

    2014-04-01

    Boron doped (B-doped) diamond films are deposited onto WC-Co inserts by HFCVD with the mixture of acetone, trimethyl borate (C3H9BO3) and H2. The as-deposited B-doped diamond films are characterized with scanning electron microscope (SEM), X-ray diffraction (XRD) spectroscopy, Raman spectroscopy, 3D surface topography based on white-light interferometry and Rockwell hardness tester. The effects of mechanical polishing on the friction behavior and cutting performance of B-doped diamond are evaluated by ball-on-plate type reciprocating tribometer and turning of aluminum alloy 7075 materials, respectively. For comparison, the same tests are also conducted for the bare WC-Co inserts with smooth surface. Friction tests suggest that the unpolished and polished B-doped diamond films possess relatively low fluctuation of friction coefficient than as-received bare WC-Co samples. The average stable friction coefficient for B-doped diamond films decreases apparently after mechanical polishing. The values for WC-Co sample, unpolished and polished B-doped diamond films are approximately 0.38, 0.25 and 0.11, respectively. The cutting results demonstrate that the low friction coefficient and high adhesive strength of B-doped diamond films play an essential role in the cutting performance enhancement of the WC-Co inserts. However, the mechanical polishing process may lower the adhesive strength of B-doped diamond films. Consequently, the polished B-doped diamond coated inserts show premature wear in the machining of adhesive aluminum alloy materials.

  16. Comparative study of the effects of phosphorus and boron doping in vapor-liquid-solid growth with fixed flow of silicon gas

    NASA Astrophysics Data System (ADS)

    Islam, Md. Shofiqul; Mehedi, Ibrahim Mustafa

    2016-04-01

    This work was carried out to investigate the comparative effects of phosphorus and boron doing in vapor-liquid-solid (VLS) growth. Doped Si microneedles were grown by VLS mechanism at the temperature of 700 °C or less using Au as the catalyst. VLS growth using in-situ doping with the mixed gas of Si2H6 and PH3 produced phosphorus doped n-Si microneedles at Au dot sites, whereas, the mixed gas of Si2H6 and B2H6 produced boron doped p-Si microneedles. The variation of growth rate, diameter, resistivity, impurity concentration and carrier (electron, hole) mobility of these n-Si and p-Si microneeedles were investigated and compared with the variation of dopant gas (PH3 or B2H6) flow, with a fixed flow of Si gas (Si2H6). This comparative study shall be helpful while fabricating devices by growing n-Si and p-Si microneedles one above another by multistep (2-step or 3-step) VLS growth.

  17. Synthesis of Low-Density, Carbon-Doped, Porous Hexagonal Boron Nitride Solids.

    PubMed

    Gautam, Chandkiram; Tiwary, Chandra Sekhar; Jose, Sujin; Brunetto, Gustavo; Ozden, Sehmus; Vinod, Soumya; Raghavan, Prasanth; Biradar, Santoshkumar; Galvao, Douglas Soares; Ajayan, Pulickel M

    2015-12-22

    Here, we report the scalable synthesis and characterization of low-density, porous, three-dimensional (3D) solids consisting of two-dimensional (2D) hexagonal boron nitride (h-BN) sheets. The structures are synthesized using bottom-up, low-temperature (∼300 °C), solid-state reaction of melamine and boric acid giving rise to porous and mechanically stable interconnected h-BN layers. A layered 3D structure forms due to the formation of h-BN, and significant improvements in the mechanical properties were observed over a range of temperatures, compared to graphene oxide or reduced graphene oxide foams. A theoretical model based on Density Functional Theory (DFT) is proposed for the formation of h-BN architectures. The material shows excellent, recyclable absorption capacity for oils and organic solvents. PMID:26580810

  18. Optically transparent boron-doped nanocrystalline diamond films for spectroelectrochemical measurements on different substrates

    NASA Astrophysics Data System (ADS)

    Sobaszek, M.; Siuzdak, K.; Skowroński, Ł.; Bogdanowicz, R.; Pluciński, J.

    2016-01-01

    Fabrication process of optically transparent boron nanocrystalline diamond (B- NCD) electrode on silicon and quartz substrate was shown. The B-NCD films were deposited on the substrates using Microwave Plasma Assisted Chemical Vapor Deposition (MWPACVD) at glass substrate temperature of 475 °C. A homogenous, continuous and polycrystalline surface morphology with high sp3 content in B-NCD films and film thickness depending from substrate in the range of 60-300 nm was obtained. The high refraction index and transparency in visible (VIS) wavelength range was achieved. Moreover, cyclic voltammograms (CV) were recorded to determine reaction reversibility at the B-NCD electrode. CV measurements in aqueous media consisting of 1 mM K3[Fe(CN)6] in 0.5 M Na2SO4 demonstrated relatively fast kinetics expressed by a redox peak splitting below 503 mV for B-NCD/silicon and 110 mv for B-NCD/quartz.

  19. Lithium decoration of three dimensional boron-doped graphene frameworks for high-capacity hydrogen storage

    SciTech Connect

    Wang, Yunhui; Meng, Zhaoshun; Liu, Yuzhen; You, Dongsen; Wu, Kai; Lv, Jinchao; Wang, Xuezheng; Deng, Kaiming; Lu, Ruifeng E-mail: rflu@njust.edu.cn; Rao, Dewei E-mail: rflu@njust.edu.cn

    2015-02-09

    Based on density functional theory and the first principles molecular dynamics simulations, a three-dimensional B-doped graphene-interconnected framework has been constructed that shows good thermal stability even after metal loading. The average binding energy of adsorbed Li atoms on the proposed material (2.64 eV) is considerably larger than the cohesive energy per atom of bulk Li metal (1.60 eV). This value is ideal for atomically dispersed Li doping in experiments. From grand canonical Monte Carlo simulations, high hydrogen storage capacities of 5.9 wt% and 52.6 g/L in the Li-decorated material are attained at 298 K and 100 bars.

  20. Evidence for the role of hydrogen in the stabilization of minority carrier lifetime in boron-doped Czochralski silicon

    SciTech Connect

    Nampalli, N. Hallam, B.; Chan, C.; Abbott, M.; Wenham, S.

    2015-04-27

    This study demonstrates that the presence of a hydrogen source during fast-firing is critical to the regeneration of B-O defects and that is it not a pure thermally based mechanism or due to plasma exposure. Boron-doped p-type wafers were fired with and without hydrogen-rich silicon nitride (SiN{sub x}:H) films present during the fast-firing process. After an initial light-induced degradation step, only wafers fired with the SiN{sub x}:H films present were found to undergo permanent and complete recovery of lifetime during subsequent illuminated annealing. In comparison, wafers fired bare, i.e., without SiN{sub x}:H films present during firing, were found to demonstrate no permanent recovery in lifetime. Further, prior exposure to hydrogen-rich plasma processing was found to have no impact on permanent lifetime recovery in bare-fired wafers. This lends weight to a hydrogen-based model for B-O defect passivation and casts doubt on the role of non-hydrogen species in the permanent passivation of B-O defects in commercial-grade p-type Czochralski silicon wafers.

  1. Mechanistic proposal for the electrochemical and sonoelectrochemical oxidation of thiram on a boron-doped diamond anode.

    PubMed

    Steter, Juliana R; Kossuga, Miriam H; Motheo, Artur J

    2016-01-01

    A comparative study was carried out of sonochemical (SCh), electrochemical (ECh) and sonoelectrochemical (SECh) strategies for the degradation of the fungicide thiram in dilute aqueous solution. The SCh and SECh studies were performed using a sonicator equipped with an 11 mm titanium-alloy probe and operated at 20 kHz with a power intensity of 523 W cm(-2). In the ECh and SECh investigations, galvanostatic electrolyses were implemented using a single compartment electrochemical cell with a boron-doped diamond electrode as anode and applied current densities in the range 10-50 mA cm(-2). For these processes, the decrease in concentration of thiram was monitored by high performance liquid chromatographic (HPLC) analysis and values of current efficiency and energy consumption were determined. The results showed that the rate of degradation of thiram and the amount of energy consumed were directly proportional to the applied current density, while current efficiency was inversely related to current density. The kinetics of thiram degradation followed a pseudo first order model with apparent rate constants in the region of 10(-3)min(-1). Thiram in aqueous solution was subjected to "exhaustive" degradation by ECh and SECh processes for 5h at applied current densities of 35 mA cm(-2) and the intermediates/byproducts so-formed were identified by HPLC-mass spectrometry. Mechanisms of the degradation reactions have been proposed on the basis of the results obtained. PMID:26384879

  2. Application of electrochemical technology for removing petroleum hydrocarbons from produced water using lead dioxide and boron-doped diamond electrodes.

    PubMed

    Gargouri, Boutheina; Gargouri, Olfa Dridi; Gargouri, Bochra; Trabelsi, Souhel Kallel; Abdelhedi, Ridha; Bouaziz, Mohamed

    2014-12-01

    Although diverse methods exist for treating polluted water, the most promising and innovating technology is the electrochemical remediation process. This paper presents the anodic oxidation of real produced water (PW), generated by the petroleum exploration of the Petrobras plant-Tunisia. Experiments were conducted at different current densities (30, 50 and 100 mA cm(-2)) using the lead dioxide supported on tantalum (Ta/PbO2) and boron-doped diamond (BDD) anodes in an electrolytic batch cell. The electrolytic process was monitored by the chemical oxygen demand (COD) and the residual total petroleum hydrocarbon [TPH] in order to know the feasibility of electrochemical treatment. The characterization and quantification of petroleum wastewater components were performed by gas chromatography mass spectrometry. The COD removal was approximately 85% and 96% using PbO2 and BDD reached after 11 and 7h, respectively. Compared with PbO2, the BDD anode showed a better performance to remove petroleum hydrocarbons compounds from produced water. It provided a higher oxidation rate and it consumed lower energy. However, the energy consumption and process time make useless anodic oxidation for the complete elimination of pollutants from PW. Cytotoxicity has shown that electrochemical oxidation using BDD could be efficiently used to reduce more than 90% of hydrocarbons compounds. All results suggest that electrochemical oxidation could be an effective approach to treat highly concentrated organic pollutants present in the industrial petrochemical wastewater and significantly reduce the cost and time of treatment. PMID:25129707

  3. Photocarrier Radiometry Investigation of Light-Induced Degradation of Boron-Doped Czochralski-Grown Silicon Without Surface Passivation

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Li, Bincheng

    2016-04-01

    Light-induced degradation (LID) effects of boron-doped Cz silicon wafers without surface passivation are investigated in details by photocarrier radiometry (PCR). The resistivity of all samples is in the range of 0.006 Ω {\\cdot } {cm} to 38 Ω {\\cdot } {cm}. It is found that light-induced changes in surface state occupation have a great effect on LID under illumination. With the increasing contribution of light-induced changes in surface state occupation, the generation rate of the defect decreases. The light-induced changes in surface state occupation and light-induced degradation dominate the temporal behaviors of the excess carrier density of high- and low-resistivity Si wafers, respectively. Moreover, the temporal behaviors of PCR signals of these samples under laser illumination with different powers, energy of photons, and multiple illuminations were also analyzed to understand the light-induced change of material properties. Based on the nonlinear dependence of PCR signal on the excitation power, a theoretical model taking into account both light-induced changes in surface state occupation and LID processes was proposed to explain those temporal behaviors.

  4. XPS study of ruthenium tris-bipyridine electrografted from diazonium salt derivative on microcrystalline boron doped diamond.

    PubMed

    Agnès, Charles; Arnault, Jean-Charles; Omnès, Franck; Jousselme, Bruno; Billon, Martial; Bidan, Gérard; Mailley, Pascal

    2009-12-28

    Boron doped diamond (BDD) functionalization has received an increasing interest during the last few years. Such an infatuation comes from the original properties of BDD, including chemical stability or an electrochemical window, that opens the way for the design of (bio)sensors or smart interfaces. In such a context, diazonium salts appear to be well suited for BDD functionalization as they enable covalent immobilization of functional entities such as enzymes or DNA. In this study we report microcrystalline BDD functionalization with a metallic complex, ruthenium tris(bipyridine), using the p-(tris(bipyridine)Ru(2+))phenyl diazonium salt. Electrografting using cyclic voltammetry (CV) allowed the formation of a ruthenium complex film that was finely characterized using electrochemistry and X-ray photoelectron spectroscopy (XPS). Moreover, we showed that chronopotentiometry (CP) is a convenient tool to monitor Ru complex film deposition through the control of the electrochemical pulse parameters (i.e. current density and pulse duration). Finally, such a control was demonstrated through the correlation between electrochemical and XPS characterizations. PMID:20024438

  5. Electrochemical oxidation of tramadol in low-salinity reverse osmosis concentrates using boron-doped diamond anodes.

    PubMed

    Lütke Eversloh, Christian; Schulz, Manoj; Wagner, Manfred; Ternes, Thomas A

    2015-04-01

    The electrochemical treatment of low-salinity reverse osmosis (RO) concentrates was investigated using tramadol (100 μM) as a model substance for persistent organic contaminants. Galvanostatic degradation experiments using boron-doped diamond electrodes at different applied currents were conducted in RO concentrates as well as in ultra-pure water containing either sodium chloride or sodium sulfate. Kinetic investigations revealed a significant influence of in-situ generated active chlorine besides direct anodic oxidation. Therefore, tramadol concentrations decreased more rapidly at elevated chloride content. Nevertheless, reduction of total organic carbon (TOC) was found to be comparatively low, demonstrating that transformation rather than mineralization was taking place. Early stage product formation could be attributed to both direct and indirect processes, including demethylation, hydroxylation, dehydration, oxidative aromatic ring cleavage and halogenation reactions. The latter led to various halogenated derivatives and resulted in AOX (adsorbable organic halogens) formation in the lower mg/L-range depending on the treatment conditions. Characterisation of transformation products (TPs) was achieved via MS(n) experiments and additional NMR measurements. Based on identification and quantification of the main TPs in different matrices and on additional potentiostatic electrolysis, a transformation pathway was proposed. PMID:25660808

  6. Synergetic antibacterial activity of reduced graphene oxide and boron doped diamond anode in three dimensional electrochemical oxidation system

    PubMed Central

    Qi, Xiujuan; Wang, Ting; Long, Yujiao; Ni, Jinren

    2015-01-01

    A 100% increment of antibacterial ability has been achieved due to significant synergic effects of boron-doped diamond (BDD) anode and reduced graphene oxide (rGO) coupled in a three dimensional electrochemical oxidation system. The rGO, greatly enhanced by BDD driven electric field, demonstrated strong antibacterial ability and even sustained its excellent performance during a reasonable period after complete power cut in the BDD-rGO system. Cell damage experiments and TEM observation confirmed much stronger membrane stress in the BDD-rGO system, due to the faster bacterial migration and charge transfer by the expanded electro field and current-carrying efficiency by quantum tunnel. Reciprocally the hydroxyl-radical production was eminently promoted with expanded area of electrodes and delayed recombination of the electron–hole pairs in presence of the rGO in the system. This implied a huge potential for practical disinfection with integration of the promising rGO and the advanced electrochemical oxidation systems. PMID:25994309

  7. Electrochemical incineration of cresols: a comparative study between PbO2 and boron-doped diamond anodes.

    PubMed

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

    2009-03-01

    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

  8. Synergetic antibacterial activity of reduced graphene oxide and boron doped diamond anode in three dimensional electrochemical oxidation system

    NASA Astrophysics Data System (ADS)

    Qi, Xiujuan; Wang, Ting; Long, Yujiao; Ni, Jinren

    2015-05-01

    A 100% increment of antibacterial ability has been achieved due to significant synergic effects of boron-doped diamond (BDD) anode and reduced graphene oxide (rGO) coupled in a three dimensional electrochemical oxidation system. The rGO, greatly enhanced by BDD driven electric field, demonstrated strong antibacterial ability and even sustained its excellent performance during a reasonable period after complete power cut in the BDD-rGO system. Cell damage experiments and TEM observation confirmed much stronger membrane stress in the BDD-rGO system, due to the faster bacterial migration and charge transfer by the expanded electro field and current-carrying efficiency by quantum tunnel. Reciprocally the hydroxyl-radical production was eminently promoted with expanded area of electrodes and delayed recombination of the electron-hole pairs in presence of the rGO in the system. This implied a huge potential for practical disinfection with integration of the promising rGO and the advanced electrochemical oxidation systems.

  9. Removal of organic contaminants from secondary effluent by anodic oxidation with a boron-doped diamond anode as tertiary treatment.

    PubMed

    Garcia-Segura, Sergi; Keller, Jürg; Brillas, Enric; Radjenovic, Jelena

    2015-01-01

    Electrochemical advanced oxidation processes (EAOPs) have been widely investigated as promising technologies to remove trace organic contaminants from water, but have rarely been used for the treatment of real waste streams. Anodic oxidation with a boron-doped diamond (BDD) anode was applied for the treatment of secondary effluent from a municipal sewage treatment plant containing 29 target pharmaceuticals and pesticides. The effectiveness of the treatment was assessed from the contaminants decay, dissolved organic carbon and chemical oxygen demand removal. The effect of applied current and pH was evaluated. Almost complete mineralization of effluent organic matter and trace contaminants can be obtained by this EAOP primarily due to the action of hydroxyl radicals formed at the BDD surface. The oxidation of Cl(-) ions present in the wastewater at the BDD anode gave rise to active chlorine species (Cl2/HClO/ClO(-)), which are competitive oxidizing agents yielding chloramines and organohalogen byproducts, quantified as adsorbable organic halogen. However, further anodic oxidation of HClO/ClO(-) species led to the production of ClO3(-) and ClO4(-) ions. The formation of these species hampers the application as a single-stage tertiary treatment, but posterior cathodic reduction of chlorate and perchlorate species may reduce the risks associated to their presence in the environment. PMID:25464295

  10. Experimental Approach to Controllably Vary Protein Oxidation While Minimizing Electrode Adsorption for Boron-Doped Diamond Electrochemical Surface Mapping Applications

    SciTech Connect

    McClintock, Carlee; Hettich, Robert {Bob} L

    2013-01-01

    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 hydroxyl radicals for these measurements; however, many of these approaches require use of radioactive sources or caustic oxidizing chemicals. The purpose of this research was to evaluate and optimize the use of boron-doped diamond (BDD) electrochemistry as a highly accessible tool for producing hydroxyl radicals as a means to induce a controllable level of oxidation on a range of intact proteins. These experiments utilize a relatively high flow rates to reduce protein residence time inside the electrochemical flow chamber, along with a unique cell activation approach to improve control over the intact protein oxidation yield. Studies were conducted to evaluate the level of protein adsorption onto the electrode surface. This report demonstrates a robust protocol for the use of BDD electrochemistry and high performance LC-MS/MS as a high-throughput experimental pipeline for probing higher order protein structure, and illustrates how it is complementary to predictive computational modeling efforts.

  11. Highly sensitive detection of influenza virus by boron-doped diamond electrode terminated with sialic acid-mimic peptide.

    PubMed

    Matsubara, Teruhiko; Ujie, Michiko; Yamamoto, Takashi; Akahori, Miku; Einaga, Yasuaki; Sato, Toshinori

    2016-08-01

    The progression of influenza varies according to age and the presence of an underlying disease; appropriate treatment is therefore required to prevent severe disease. Anti-influenza therapy, such as with neuraminidase inhibitors, is effective, but diagnosis at an early phase of infection before viral propagation is critical. Here, we show that several dozen plaque-forming units (pfu) of influenza virus (IFV) can be detected using a boron-doped diamond (BDD) electrode terminated with a sialic acid-mimic peptide. The peptide was used instead of the sialyloligosaccharide receptor, which is the common receptor of influenza A and B viruses required during the early phase of infection, to capture IFV particles. The peptide, which was previously identified by phage-display technology, was immobilized by click chemistry on the BDD electrode, which has excellent electrochemical characteristics such as low background current and weak adsorption of biomolecules. Electrochemical impedance spectroscopy revealed that H1N1 and H3N2 IFVs were detectable in the range of 20-500 pfu by using the peptide-terminated BDD electrode. Our results demonstrate that the BDD device integrated with the receptor-mimic peptide has high sensitivity for detection of a low number of virus particles in the early phase of infection. PMID:27457924

  12. Electrochemical degradation of the antihypertensive losartan in aqueous medium by electro-oxidation with boron-doped diamond electrode.

    PubMed

    Salazar, Claudio; Contreras, Nicole; Mansilla, Héctor D; Yáñez, Jorge; Salazar, Ricardo

    2016-12-01

    In this work the electrochemical oxidation of losartan, an emerging pharmaceutical pollutant, was studied. Electrochemical oxidation was carried out in batch mode, in an open and undivided cell of 100cm(3) using a boron-doped diamond (BDD)/stainless steel system. With Cl(-) medium 56% of mineralization was registered, while with the trials containing SO4(2-) as supporting electrolyte a higher mineralization yield of 67% was reached, even obtaining a total removal of losartan potassium at 80mAcm(-2) and 180min of reaction time at pH 7.0. Higher losartan potassium concentrations enhanced the mineralization degree and the efficiency of the electrochemical oxidation process. During the mineralization up to 4 aromatic intermediates were identified by ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Moreover, short-linear carboxylic acids, like oxalic, succinic and oxamic were detected and quantified by ion-exclusion HPLC. Finally, the ability of the electrochemical oxidation process to mineralize dissolved commercial tablets containing losartan was achieved, obtaining TOC removal up to 71% under optimized conditions (10mAcm(-2), 0.05M Na2SO4, pH 7.0 and 25°C and 360min of electrolysis). PMID:27180209

  13. Photovoltaic devices based on high density boron-doped single-walled carbon nanotube/n-Si heterojunctions

    SciTech Connect

    Saini, Viney; Li, Zhongrui; Bourdo, Shawn; Kunets, Vasyl P.; Trigwell, Steven; Couraud, Arthur; Rioux, Julien; Boyer, Cyril; Nteziyaremye, Valens; Dervishi, Enkeleda; Biris, Alexandru R.; Salamo, Gregory J.; Viswanathan, Tito; Biris, Alexandru S.

    2011-01-13

    A simple and easily processible photovoltaic device has been developed based on borondoped single-walled carbon nanotubes (B-SWNTs) and n-type silicon (n-Si) heterojunctions. The single-walled carbon nanotubes (SWNTs) were substitutionally doped with boron atoms by thermal annealing, in the presence of B2O3. The samples used for these studies were characterized by Raman spectroscopy, thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). The fully functional solar cell devices were fabricated by airbrush deposition that generated uniform B-SWNT films on top of the n-Si substrates. The carbon nanotube films acted as exciton-generation sites, charge collection and transportation, while the heterojunctions formed between B-SWNTs and n-Si acted as charge dissociation centers. The current-voltage characteristics in the absence of light and under illumination, as well as optical transmittance spectrum are reported here. It should be noted that the device fabrication process can be made amenable to scalability by depositing direct and uniform films using airbrushing, inkjet printing, or spin-coating techniques.

  14. Sensitive voltammetric determination of thymol in essential oil of Carum copticum seeds using boron-doped diamond electrode.

    PubMed

    Stanković, Dalibor M

    2015-10-01

    Essential oil of Carum copticum seeds, obtained from a local shop, was extracted and content of thymol was analyzed using square-wave voltammetry at boron-doped diamond electrode. The effect of various parameters, such as pH of supporting electrolyte and square-wave voltammetric parameters (modulation amplitude and frequency), was examined. In Britton-Robinson buffer solution (pH 4), thymol provided a single and oval-shaped irreversible oxidation peak at +1.13 V versus silver/silver chloride potassium electrode (3M). Under optimal experimental conditions, a plot of peak height against concentration of thymol was found to be linear over the range of 4 to 100μM consisting of two linear ranges: from 4 to 20μM (R(2)=0.9964) and from 20 to 100μM (R(2)=0.9993). The effect of potential interferences such as p-cymene and γ-terpinene (major components in essential oil of C. copticum seeds) was evaluated. Thus, the proposed method displays a sufficient selectivity toward thymol with a detection limit of 3.9μM, and it was successfully applied for the determination of thymol in essential oil of C. copticum seeds. The Prussian blue method was used for validation of the proposed electroanalytical method. PMID:26119334

  15. Electrochemical analysis of acetaminophen using a boron-doped diamond thin film electrode applied to flow injection system.

    PubMed

    Wangfuengkanagul, Nattakarn; Chailapakul, Orawon

    2002-06-01

    The electrochemistry of acetaminophen in phosphate buffer solution (pH 8) was studied at a boron-doped diamond (BDD) thin film electrode using cyclic voltammetry, hydrodynamic voltammetry, and flow injection with amperometric detection. Cyclic voltammetry was used to study the reaction as a function of concentration of analyte. Comparison experiments were performed using a polished glassy carbon (GC) electrode. Acetaminophen undergoes quasi-reversible reaction at both of these two electrodes. The BDD and GC electrodes provided well-resolved cyclic voltammograms but the voltammetric signal-to-background ratios obtained from the diamond electrode were higher than those obtained from the GC electrode. The diamond electrode provided a linear dynamic range from 0.1 to 8 mM and a detection of 10 microM (S/B approximately 3) for voltammetric measurement. The flow injection analysis results at the diamond electrode indicated a linear dynamic range from 0.5 to 50 microM and a detection limit of 10 nM (S/N approximately 4). Acetaminophen in syrup samples has also been investigated. The results obtained in the recovery study (24.68+/-0.26 mg/ml) were comparable to those labeled (24 mg/ml). PMID:12039625

  16. Treatment of ink effluents from flexographic printing by lime precipitation and boron-doped diamond (BDD) electrochemical oxidation.

    PubMed

    Diamadopoulos, Evan; Barndõk, Helen; Xekoukoulotakis, Nikolaos P; Mantzavinos, Dionissios

    2009-01-01

    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

  17. Simultaneous square-wave voltammetric determination of aspartame and cyclamate using a boron-doped diamond electrode.

    PubMed

    Medeiros, Roberta Antigo; de Carvalho, Adriana Evaristo; Rocha-Filho, Romeu C; Fatibello-Filho, Orlando

    2008-07-30

    A simple and highly selective electrochemical method was developed for the simultaneous determination of aspartame and cyclamate in dietary products at a boron-doped diamond (BDD) electrode. In square-wave voltammetric (SWV) measurements, the BDD electrode was able to separate the oxidation peak potentials of aspartame and cyclamate present in binary mixtures by about 400 mV. The detection limit for aspartame in the presence of 3.0x10(-4) mol L(-1) cyclamate was 4.7x10(-7) mol L(-1), and the detection limit for cyclamate in the presence of 1.0x10(-4) mol L(-1) aspartame was 4.2x10(-6) mol L(-1). When simultaneously changing the concentration of both aspartame and cyclamate in a 0.5 mol L(-1) sulfuric acid solution, the corresponding detection limits were 3.5x10(-7) and 4.5x10(-6) mol L(-1), respectively. The relative standard deviation (R.S.D.) obtained was 1.3% for the 1.0x10(-4) mol L(-1) aspartame solution (n=5) and 1.1% for the 3.0x10(-3) mol L(-1) cyclamate solution. The proposed method was successfully applied in the determination of aspartame in several dietary products with results similar to those obtained using an HPLC method at 95% confidence level. PMID:18585340

  18. The analysis of estrogenic compounds by flow injection analysis with amperometric detection using a boron-doped diamond electrode.

    PubMed

    Brocenschi, Ricardo F; Rocha-Filho, Romeu C; Duran, Boris; Swain, Greg M

    2014-08-01

    We report on the use of flow injection analysis with amperometric detection (FIA-EC) to evaluate the potential of using diamond electrodes for the analysis of three estrogenic compounds: estrone, 17-β-estradiol, and estriol. Amperometric detection was performed using a cathodically pretreated boron-doped diamond electrode that offered low background current, relatively low limits of detection, and good response reproducibility and stability. For all three compounds, response linearity was observed over the concentration range tested, 0.10 to 3.0μmol L(-1), the sensitivity was ca. 10mA L mol(-1), and the minimum concentration detection (S/N≥3) was 0.10μmol L(-1) (~27μg L(-1)). The response variability with multiple injections was ca. 10% (RSD) over 20 injections. For estrone, the oxidation reaction on diamond does not proceed through an adsorbed state like it does on glassy carbon. After an initial current attenuation, the diamond electrode exhibited a stable response (oxidation current) for 3 days of continuous use, indicative of minimal surface contamination or fouling by reaction intermediates and products. The method for estrone was assessed using spiked city tap and local river water. Estrone recoveries in spiked city and river water samples presented standard deviations of less than 10%. In summary, the FIA-EC method with a diamond electrode enables sensitive, reproducible, stable, quick, and inexpensive determination of estrogenic compounds in water samples. PMID:24881529

  19. Destination of organic pollutants during electrochemical oxidation of biologically-pretreated dye wastewater using boron-doped diamond anode.

    PubMed

    Zhu, Xiuping; Ni, Jinren; Wei, Junjun; Xing, Xuan; Li, Hongna

    2011-05-15

    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

  20. Surface Transfer Doping of Cubic Boron Nitride Films by MoO3 and Tetrafluoro-tetracyanoquinodimethane (F4-TCNQ).

    PubMed

    He, Bin; Ng, Tsz-Wai; Lo, Ming-Fai; Lee, Chun-Sing; Zhang, Wenjun

    2015-05-13

    Cubic boron nitride (cBN) has strong potential for the applications in high-temperature and high-power electronics and deep ultraviolet devices due to its outstanding combined physical and chemical properties. P-type surface transfer doping of heteroepitaxial cBN films was achieved by employing MoO3 and tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) as the surface dopants. The surface conductivities of hydrogenated cBN films increased by 3-6 orders after the deposition of surface dopants. The photoemission spectroscopy (PES) measurements revealed the variation of electronic structures at the interface regions, which suggested that the electron transfer from cBN films to the surface dopants induced hole accumulation at the cBN surface and the increase of surface conductivity. Based on the PES results, the energy level diagrams at MoO3/cBN and F4-TCNQ/cBN interfaces were determined. The achievement provided a potential approach for fabricating cBN-based electronic devices, especially on micrometer and nanometer scales. PMID:25915092

  1. Highly Sensitive Measurement of Bio-Electric Potentials by Boron-Doped Diamond (BDD) Electrodes for Plant Monitoring.

    PubMed

    Ochiai, Tsuyoshi; Tago, Shoko; Hayashi, Mio; Fujishima, Akira

    2015-01-01

    We describe a sensitive plant monitoring system by the detection of the bioelectric potentials in plants with boron-doped diamond (BDD) electrodes. For sensor electrodes, we used commercially available BDD, Ag, and Pt plate electrodes. We tested this approach on a hybrid species in the genus Opuntia (potted) and three different trees (ground-planted) at different places in Japan. For the Opuntia, we artificially induced bioelectric potential changes by the surface potential using the fingers. We detected substantial changes in bioelectric potentials through all electrodes during finger touches on the surface of potted Opuntia hybrid plants, although the BDD electrodes were several times more sensitive to bioelectric potential change compared to the other electrodes. Similarly for ground-planted trees, we found that both BDD and Pt electrodes detected bioelectric potential change induced by changing environmental factors (temperature and humidity) for months without replacing/removing/changing electrodes, BDD electrodes were 5-10 times more sensitive in this detection than Pt electrodes. Given these results, we conclude that BDD electrodes on live plant tissue were able to consistently detect bioelectrical potential changes in plants. PMID:26512663

  2. Highly Sensitive Measurement of Bio-Electric Potentials by Boron-Doped Diamond (BDD) Electrodes for Plant Monitoring

    PubMed Central

    Ochiai, Tsuyoshi; Tago, Shoko; Hayashi, Mio; Fujishima, Akira

    2015-01-01

    We describe a sensitive plant monitoring system by the detection of the bioelectric potentials in plants with boron-doped diamond (BDD) electrodes. For sensor electrodes, we used commercially available BDD, Ag, and Pt plate electrodes. We tested this approach on a hybrid species in the genus Opuntia (potted) and three different trees (ground-planted) at different places in Japan. For the Opuntia, we artificially induced bioelectric potential changes by the surface potential using the fingers. We detected substantial changes in bioelectric potentials through all electrodes during finger touches on the surface of potted Opuntia hybrid plants, although the BDD electrodes were several times more sensitive to bioelectric potential change compared to the other electrodes. Similarly for ground-planted trees, we found that both BDD and Pt electrodes detected bioelectric potential change induced by changing environmental factors (temperature and humidity) for months without replacing/removing/changing electrodes, BDD electrodes were 5–10 times more sensitive in this detection than Pt electrodes. Given these results, we conclude that BDD electrodes on live plant tissue were able to consistently detect bioelectrical potential changes in plants. PMID:26512663

  3. Determination of vanillin in commercial food product by adsorptive stripping voltammetry using a boron-doped diamond electrode.

    PubMed

    Yardım, Yavuz; Gülcan, Mehmet; Şentürk, Zühre

    2013-12-01

    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 μg mL(-1) (3.3×10(-6)-9.8×10(-5) mol L(-1)) with a detection limit of 0.024 μg 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

  4. Monitoring the evolution of boron doped porous diamond electrode on flexible retinal implant by OCT and in vivo impedance spectroscopy.

    PubMed

    Hébert, Clément; Cottance, Myline; Degardin, Julie; Scorsone, Emmanuel; Rousseau, Lionel; Lissorgues, Gaelle; Bergonzo, Philippe; Picaud, Serge

    2016-12-01

    Nanocrystalline Boron doped Diamond proved to be a very attractive material for neural interfacing, especially with the retina, where reduce glia growth is observed with respect to other materials, thus facilitating neuro-stimulation over long terms. In the present study, we integrated diamond microelectrodes on a polyimide substrate and investigated their performances for the development of neural prosthesis. A full description of the microfabrication of the implants is provided and their functionalities are assessed using cyclic voltammetry and electrochemical impedance spectroscopy. A porous structure of the electrode surface was thus revealed and showed promising properties for neural recording or stimulation. Using the flexible implant, we showed that is possible to follow in vivo the evolution of the electric contact between the diamond electrodes and the retina over 4months by using electrochemical impedance spectroscopy. The position of the implant was also monitored by optical coherence tomography to corroborate the information given by the impedance measurements. The results suggest that diamond microelectrodes are very good candidates for retinal prosthesis. PMID:27612691

  5. Transport Properties of p-n Junctions Formed in Boron/Nitrogen Doped Carbon Nanotubes and Graphene Nanoribbons

    NASA Astrophysics Data System (ADS)

    Hammouri, Mahmoud; Vasiliev, Igor

    2014-03-01

    We apply ab initio computational methods based on density functional theory to study the transport properties of p-n junctions made of single-walled carbon nanotubes and graphene nanoribbons. The p-n junctions are formed by doping the opposite ends of carbon nanostructures with boron and nitrogen atoms. Our calculations are carried out using the SIESTA electronic structure code combined with the generalized gradient approximation for the exchange-correlation functional. The transport properties are calculated using a self-consistent nonequilibrium Green's function method implemented in the TranSIESTA package. The modeled nanoscale p-n junctions exhibit linear I-V characteristics in the forward bias and nonlinear I-V characteristics with a negative differential resistance in the reverse bias. The computed transmission spectra and the I-V characteristics of the p-n junctions are compared to the results of other theoretical studies and to the available experimental data. Supported by NMSU GREG Award and by NSF CHE-1112388.

  6. Photovoltaic devices based on high density boron-doped single-walled carbon nanotube/n-Si heterojunctions

    DOE PAGESBeta

    Saini, Viney; Li, Zhongrui; Bourdo, Shawn; Kunets, Vasyl P.; Trigwell, Steven; Couraud, Arthur; Rioux, Julien; Boyer, Cyril; Nteziyaremye, Valens; Dervishi, Enkeleda; et al

    2011-01-13

    A simple and easily processible photovoltaic device has been developed based on borondoped single-walled carbon nanotubes (B-SWNTs) and n-type silicon (n-Si) heterojunctions. The single-walled carbon nanotubes (SWNTs) were substitutionally doped with boron atoms by thermal annealing, in the presence of B2O3. The samples used for these studies were characterized by Raman spectroscopy, thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy (XPS). The fully functional solar cell devices were fabricated by airbrush deposition that generated uniform B-SWNT films on top of the n-Si substrates. The carbon nanotube films acted as exciton-generation sites, charge collection and transportation, whilemore » the heterojunctions formed between B-SWNTs and n-Si acted as charge dissociation centers. The current-voltage characteristics in the absence of light and under illumination, as well as optical transmittance spectrum are reported here. It should be noted that the device fabrication process can be made amenable to scalability by depositing direct and uniform films using airbrushing, inkjet printing, or spin-coating techniques.« less

  7. Surface Roughness and Critical Exponent Analyses of Boron-Doped Diamond Films Using Atomic Force Microscopy Imaging: Application of Autocorrelation and Power Spectral Density Functions

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Vierkant, G. P.

    2014-09-01

    The evolution of the surface roughness of growing metal or semiconductor thin films provides much needed information about their growth kinetics and corresponding mechanism. While some systems show stages of nucleation, coalescence, and growth, others exhibit varying microstructures for different process conditions. In view of these classifications, we report herein detailed analyses based on atomic force microscopy (AFM) characterization to extract the surface roughness and growth kinetics exponents of relatively low boron-doped diamond (BDD) films by utilizing the analytical power spectral density (PSD) and autocorrelation function (ACF) as mathematical tools. The machining industry has applied PSD for a number of years for tool design and analysis of wear and machined surface quality. Herein, we present similar analyses at the mesoscale to study the surface morphology as well as quality of BDD films grown using the microwave plasma-assisted chemical vapor deposition technique. PSD spectra as a function of boron concentration (in gaseous phase) are compared with those for samples grown without boron. We find that relatively higher boron concentration yields higher amplitudes of the longer-wavelength power spectral lines, with amplitudes decreasing in an exponential or power-law fashion towards shorter wavelengths, determining the roughness exponent ( α ≈ 0.16 ± 0.03) and growth exponent ( β ≈ 0.54), albeit indirectly. A unique application of the ACF, which is widely used in signal processing, was also applied to one-dimensional or line analyses (i.e., along the x- and y-axes) of AFM images, revealing surface topology datasets with varying boron concentration. Here, the ACF was used to cancel random surface "noise" and identify any spatial periodicity via repetitive ACF peaks or spatially correlated noise. Periodicity at shorter spatial wavelengths was observed for no doping and low doping levels, while smaller correlations were observed for relatively

  8. Boron-doped amorphous diamondlike carbon as a new p-type window material in amorphous silicon p-i-n solar cells

    SciTech Connect

    Lee, C.H.; Lim, K.S.

    1998-01-01

    A boron-doped hydrogenated amorphous diamondlike carbon (a-DLC:H) was prepared using a mercury-sensitized photochemical vapor deposition (photo-CVD) method. The source gases were B{sub 2}H{sub 6} and C{sub 2}H{sub 4}. By increasing the boron doping ratio (B{sub 2}H{sub 6}/C{sub 2}H{sub 4}) from 0 to 12000 ppm, the dark conductivity increased from {approximately}10{sup {minus}9} to {approximately}10{sup {minus}7} S/cm. A boron-doped a-DLC:H with an energy band gap of 3.8 eV and a dark conductivity of 1.3{times}10{sup {minus}8} S/cm was obtained at a doping ratio of 3600 ppm. By using this film, amorphous silicon (a-Si) solar cells with a novel p-a-DLC:H/p-a-SiC double p-layer structure were fabricated using the photo-CVD method and the cell photovoltaic characteristics were investigated as a function of a-DLC:H layer thickness. The open circuit voltage increased from 0.766 V for the conventional cell with a 40-{Angstrom}-thick p-a-SiC to 0.865 V for the cell with a p-a-DLC:H (15 {Angstrom})/p-a-SiC (40 {Angstrom}) double p-layer structure. The thin ({lt}15 {Angstrom}) p-a-DLC:H layer proved to be an excellent hole emitter as a wide band gap window layer. {copyright} {ital 1998 American Institute of Physics.}

  9. The influence of Cu-doping on aluminum nitride, silicon carbide and boron nitride nanotubes’ ability to detect carbon dioxide; DFT study

    NASA Astrophysics Data System (ADS)

    Mahdavifar, Zabiollah; Abbasi, Nasibeh

    2014-02-01

    In this research, the potential use of Cu-functionalized [4,4] silicon carbide (SiC), aluminum nitride (AlN) and boron nitride (BN) single-walled nanotubes as nanodevices for CO2 monitoring is investigated. It is found that Cu-doping the different sites of the considered nanotubes and combining these nanotubes with CO2 gas molecules are both exothermic processes, and the relaxed geometries are stable. Our results reveal that the CO2 gas molecules can be strongly physisorbed on the Cu-doped nanotubes, accompanied by large adsorption energy. Compared with the weak adsorption of CO2 molecule onto pristine BNNT and SiCNT, the CO2 molecule tends to be strongly physisorbed onto Cu-decorated BNNT and SiCNT with an appreciable adsorption energy. Furthermore, the results indicate that Cu-functionalized SiCNT is more favorable than Cu-doped BNNT and AlNNT structures for CO2 adsorption. Natural bond orbital analysis indicates that the adsorption of a CO2 molecule onto Cu-doped nanotubes is influenced by the electronic conductance and mechanical properties of the nanotube, which could serve as a signal for a gas sensor. It appears that the considerable charge transfer from the Cu-doped nanotubes to a CO2 molecule reduces the energy gap. These observations suggest that the Cu-doped-SiCNT, -BNNT and -AlNNT can be introduced as promising candidates for gas sensor devices that detect CO2 molecules.

  10. Ultrathin graphitic carbon nitride nanosheets: a novel peroxidase mimetic, Fe doping-mediated catalytic performance enhancement and application to rapid, highly sensitive optical detection of glucose.

    PubMed

    Tian, Jingqi; Liu, Qian; Asiri, Abdullah M; Qusti, Abdullah H; Al-Youbi, Abdulrahman O; Sun, Xuping

    2013-12-01

    In this article, we demonstrate for the first time that ultrathin graphitic carbon nitride nanosheets (g-C3N4) possess peroxidase activity. Fe doping of the nanosheets leads to peroxidase mimetics with greatly enhanced catalytic performance and the mechanism involved is proposed. We further demonstrate the novel use of such Fe-g-C3N4 as a cheap nanosensor for simple, rapid, highly selective and sensitive optical detection of glucose with a pretty low detection limit of 0.5 μM. PMID:24121798

  11. Measuring the Terahertz Refractive Index of Boron-Doped Silicon Using a Photoconducting Antenna Terahertz Generator

    NASA Astrophysics Data System (ADS)

    McNamara, Brendan P.

    The frequency range commonly referred to as the terahertz gap occurs between the infrared and microwave regions of the electromagnetic spectrum. This range of frequencies is highly suited to investigating the free carrier interactions of materials, as the range is particularly sensitive to these interactions. Using terahertz time-domain spectroscopy (THz-TDS), it is possible to measure the effect these interactions have on a terahertz pulse and, using classical optical techniques, determine the terahertz refractive index of a given material, which is directly related to the free carrier spectrum of said material. Knowing the refractive index of a material in the THz range opens the possibility of future terahertz applications for said material, including a non-destructive dopant testing of silicon. In this work, a series of Silicon on Insulator (SOI) wafer samples are implanted with boron in a range of carrier concentrations. Using a photoconducting antenna (PCA), high-frequency laser pulses were converted to THz pulses and the complex terahertz refractive index of the samples was then measured in the 0.2-2 THz frequency range. This measurement is a direct examination of the free carrier spectrum through experimental methods. The results are compared with the predictions of the Drude model for the free carrier spectrum across this frequency range and are found to closely coincide at higher carrier concentrations, indicating that the behavior of free holes in p-type silicon can likely be described classically at high carrier densities, consistent with previous work on n-type silicon.

  12. Observation of d-p hybridized aromaticity in lanthanum-doped boron clusters.

    PubMed

    Cheng, Shi-Bo; Berkdemir, Cuneyt; Castleman, A W

    2014-01-14

    The concept of aromaticity has been advanced beyond the framework of organic chemistry, and multiple aromaticity (σ, π, and δ) has been observed to account for the highly symmetric structures or unusual stability of the clusters. In the present study, the electronic structures and chemical bonding of small monolanthanum boride clusters are investigated using photoelectron imaging spectroscopy and first principles electronic structure calculations. Accurate electron affinities of 1.32 ± 0.04 and 1.13 ± 0.06 eV for the neutral LaB2 and LaB3 clusters are obtained by the vibrationally-resolved photoelectron spectra of the LaB2(-) and LaB3(-) clusters, respectively. It is shown that LaB2(-) and LaB3 exhibit enhanced stability in their respective cluster series, as evidenced from the calculated removal energies and HOMO-LUMO gaps. Molecular orbital analysis discloses that these two clusters possess doubly aromatic characters (σ and π), responsible for their enhanced stability. Interestingly, unlike conventional σ-, π-, and δ-aromaticity formed by the delocalization of unhybridized p or d orbitals, the σ and π delocalized molecular orbitals shown here are formed through the effective overlap between the 5d atomic orbital of the La atom and the p orbitals of the remaining boron atoms, representing an intriguing d-p hybridized aromaticity. PMID:24141329

  13. Tensile properties of a boron/nitrogen-doped carbon nanotube–graphene hybrid structure

    PubMed Central

    Xia, Kang; Zhan, Haifei; Wei, Ye

    2014-01-01

    Summary Doping is an effective approach that allows for the intrinsic modification of the electrical and chemical properties of nanomaterials. Recently, a graphene and carbon nanotube hybrid structure (GNHS) has been reported, which extends the excellent properties of carbon-based materials to three dimensions. In this paper, we carried out a first-time investigation on the tensile properties of the hybrid structures with different dopants. It is found that with the presence of dopants, the hybrid structures usually exhibit lower yield strength, Young’s modulus, and earlier yielding compared to that of a pristine hybrid structure. For dopant concentrations below 2.5% no significant reduction of Young’s modulus or yield strength could be observed. For all considered samples, the failure is found to initiate at the region where the nanotubes and graphene sheets are connected. After failure, monatomic chains are normally observed around the failure region. Dangling graphene layers without the separation of a residual CNT wall are found to adhere to each other after failure with a distance of about 3.4 Å. This study provides a fundamental understanding of the tensile properties of the doped graphene–nanotube hybrid structures, which will benefit the design and also the applications of graphene-based hybrid materials. PMID:24778956

  14. Doping inhomogeneity and staging of ultra-thin graphite intercalation compound flakes probed by visible and near-infrared Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lu, Yan; Zhang, Xin; Wu, Jiang-Bin; Li, Xiao-Li; Li, Qiao-Qiao; Tan, Ping-Heng

    2015-07-01

    When ultra-thin graphite intercalation compounds (GICs) are deposited on the SiO2/Si substrate, it is found that their colors are dependent on the thickness of GIC flakes. The sample colors of ultrathin GIC flakes can no longer provide qualitative information on the stage index. Here, multi-wavelength Raman spectroscopy is thus applied to study the doping inhomogeneity and staging of ultra-thin GICs by FeCl3 intercalation. The G band intensity of stage-1 GIC flakes is strongly enhanced by 532-nm laser excitation, while that of stage-2 and stage-3 flakes exhibits strong intensity enhancement for 785-nm laser excitation. The near-infrared lasers are suggested to probe the doping inhomogeneity and staging of ultra-thin GIC flakes. Project supported by the National Natural Science Foundation of China (Grant Nos. 11225421, 11474277, and 11434010).

  15. A novel method to make boron-doped microcrystalline silicon thin films with optimal crystalline volume fraction for thin films solar cell applications.

    PubMed

    Shin, Chonghoon; Park, Jinjoo; Kim, Sangho; Park, Hyeongsik; Jung, Junhee; Bong, Sungjae; Lee, Youn-Jung; Yi, Junsin

    2014-12-01

    Highly conducting boron-doped microcrystalline silicon (p-type μc-Si:H) thin films have been prepared by radio frequency plasma-enhanced chemical-vapor deposition (RF-PECVD). In this work, the effects of hydrogen dilution, doping ratio, plasma power, deposition pressure and substrate temperature on the growth and the properties of boron-doped microcrystalline silicon (p-type μc-Si:H) thin films are investigated. The electrical, chemical and structural properties are improved with increasing crystallite, which depends on the plasma conditions. For various plasma parameters, the crystalline volume fraction (X(c)), dark conductivity (σ(d)), activation energy (E(a)), hydrogen content (C(H)), surface roughness (S(r)), and micro void fraction (R*) were measured, and they were 0-72%, 4.17-10(-4) S/cm-1.1 S/cm, 0.041-0.113 eV, 3.8-11.5 at.%, 3.2 nm-12.2 nm, and 0.47-0.80, respectively. The film with R* of 0.47 and C(H) of about 5 at.% belonged to a region of low disorder, and acted as a good passivation layer. PMID:25971071

  16. Comparing atrazine and cyanuric acid electro-oxidation on mixed oxide and boron-doped diamond electrodes.

    PubMed

    Malpass, Geoffroy R P; Salazar-Banda, Giancarlo R; Miwa, Douglas W; Machado, Sérgio A S; Motheo, Artur J

    2013-01-01

    The breakdown of pesticides has been promoted by many methods for clean up of contaminated soil and wastewaters. The main goal is to decrease the toxicity of the parent compound to achieve non-toxic compounds or even, when complete mineralization occurs, carbon dioxide and water. Therefore, electrochemical degradation (potentiostatic and galvanostatic) of both the pesticide atrazine and cyanuric acid (CA) at boron-doped diamond (BDD) and Ti/Ru0.3Ti0.7O2 dimensionally stable anode (DSA) electrodes, in different supporting electrolytes (NaCl and Na2SO4), is presented with the aim of establishing the influence of the operational parameters on the process efficiency. The results demonstrate that both the electrode material and the supporting electrolyte have a strong influence on the rate of atrazine removal. In the chloride medium, the rate of atrazine removal is always greater than in sulfate under all conditions employed. Furthermore, in the sulfate medium, atrazine degradation was significant only at the BDD electrode. The total organic carbon (TOC) load decreased by 79% and 56% at the BDD and DSA electrodes, respectively, in the chloride medium. This trend was maintained in the sulfate medium but the TOC removal was lower (i.e. 33% and 13% at BDD and DSA electrodes, respectively). CA, a stable atrazine degradation intermediate, was also studied and it is efficiently removed using the BDD electrode in both media, mainly when high current densities are employed. The use of the BDD electrode in the chloride medium not only degrades atrazine but also mineralized cyanuric acid leading to the higher TOC removal. PMID:23837356

  17. CO catalytic oxidation on Pt-doped single wall boron nitride nanotube: first-principles investigations

    NASA Astrophysics Data System (ADS)

    Abdel Aal, S.

    2016-02-01

    The catalytic oxidation of CO at Pt-doped BNNT (5,5) has been investigated theoretically using density functional theory. The electronic structures and thermochemical properties of CO and O2 that adsorbed on Pt embedded at the B- and N-vacancy sites of BNNTs are analyzed. It is demonstrated that the different BNNT substrates can modify the electronic structure of the Pt catalysts and cause different effects in the catalytic activities. With the N-vacancy (Pt(N)-BNNT), the Pt behaves as a Lewis acid for accepting an electron from the substrate, thus O2 binds stronger than CO molecules, thus alleviating the CO poisoning of the platinum catalysts. Coadsorption of CO and O2 on Pt(N)-BNNT results in additional charge transfer to O2. CO oxidation proceeds via the Eley-Rideal (ER) mechanism entails lower activation barrier and higher reaction rate than that of Langmuir-Hinshelwood (LH) mechanism suggesting the superiority of the ER mechanism for CO oxidation at Pt(N)-BNNT. Therefore, Pt(N)-BNNT might be a good candidate for low-cost, highly active, and stable catalysts for CO oxidation.

  18. On the recombination behaviour of iron in moderately boron-doped p-type silicon

    NASA Astrophysics Data System (ADS)

    Walz, D.; Joly, J.-P.; Kamarinos, G.

    1996-04-01

    The recombination lifetime and diffusion length of intentionally iron-contaminated samples were measured by the Surface Photo Voltage (SPV) and the Elymat technique. The lifetime results from these techniques for intentionally iron-contaminated samples were analysed, in particular for the aspect of the injection-level dependency of recombination lifetime. Based on theoretical considerations, a method for the analysis of deep-level parameters combining constant photon flux SPV and Elymat measurements has been developed. This method is based on a detailed numerical analysis of the Elymat technique, including the Dember electric field, the characteristics of the laser beam, the transport parameters of the semiconductor and multilevel Shockley-Read-Hall (SRH) recombination kinetics. The results of the numerical simulation are applied to the analysis of recombination lifetime measurements on intentionally iron-contaminated samples. We compared numerical simulations and experimental results from SPV and Elymat for p-type samples using the classical acceptor level at E v +0.1 eV and the donor level of FeB pairs at E c -0.3 eV as recombination centre. Better consistency in the interpretation of the results has been found in the doping range 1014 1016 cm-3 supposing the E c -0.3 eV level as predominant recombination centre. An attempt to extract the electron and hole capture cross-sections for this defect is made.

  19. Reactivity of boron- and nitrogen-doped carbon nanotubes functionalized by (Pt, Eu) atoms toward O2 and CO: A density functional study

    NASA Astrophysics Data System (ADS)

    Abdel Aal, S.

    2016-01-01

    The adsorption behavior and electronic properties of CO and O2 molecules at the supported Pt and Eu atoms on (5,5) armchair SWCNT have been systematically investigated within density functional theory (DFT). Fundamental aspects such as adsorption energy, natural bond orbital (NBO), charge transfer, frontier orbitals and the projected density of states (PDOS) are elucidated to analyze the adsorption properties of CO and O2 molecules. The results reveal that B- and N-doping CNTs can enhance the binding strength and catalytic activity of Pt (Eu) anchored on the doped-CNT, where boron-doping is more effective. The electronic structures of supported metal are strongly influenced by the presence of gases. After adsorption of CO and O2, the changes in binding energy, charge transfer and conductance may lead to the different response in the metal-doped CNT-based sensors. It is expected that these results could provide helpful information for the design and fabrication of the CO and O2 sensing devices. The high catalytic activity of Pt supported at doped-CNT toward the interaction with CO and O2 may be attributed to the electronic resonance particularly among Pt-5d, CO-2π* and O2-2π* antibonding orbitals. In contrast to the supported Eu at doped-CNT, the Eu atom becomes more positively charged, which leads to weaken the CO adsorption and promote the O2 adsorption, consequently enhancing the activity for CO oxidation and alleviating the CO poisoning of the europium catalysts. A notable orbital hybridization and electrostatic interaction between these two species in adsorption process being an evidence of strong interaction. The electronic structure of O2 adsorbed on Eu-doped CNT resembles that of O2‑, therefore the transferred charge weakens the O-O bonds and facilitates the dissociation process, which is the precondition for the oxygen reduction reaction (ORR).

  20. A First Principles study on Boron-doped Graphene decorated by Ni-Ti-Mg atoms for Enhanced Hydrogen Storage Performance

    NASA Astrophysics Data System (ADS)

    Nachimuthu, Santhanamoorthi; Lai, Po-Jung; Leggesse, Ermias Girma; Jiang, Jyh-Chiang

    2015-11-01

    We proposed a new solid state material for hydrogen storage, which consists of a combination of both transition and alkaline earth metal atoms decorating a boron-doped graphene surface. Hydrogen adsorption and desorption on this material was investigated using density functional theory calculations. We find that the diffusion barriers for H atom migration and desorption energies are lower than for the previously designed mediums and the proposed medium can reach the gravimetric capacity of ~6.5 wt % hydrogen, which is much higher than the DOE target for the year 2015. Molecular Dynamics simulations show that metal atoms are stably adsorbed on the B doped graphene surface without clustering, which will enhance the hydrogen storage capacity.

  1. In situ fabrication of three-dimensional nitrogen and boron co-doped porous carbon nanofibers for high performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Lijun; Xia, Guanglin; Guo, Zaiping; Sun, Dalin; Li, Xingguo; Yu, Xuebin

    2016-08-01

    This paper reports the fabrication of three-dimensional porous carbon nanofibers network with high doping level of nitrogen (N, 5.17 at.%) and boron (B, 6.87 at.%) through a general electrospinning strategy followed by a calcination process. The employed ammonia borane (NH3BH3, denote as AB) not only functions as a porogen reagent to generate porous structures but also as the heteroatoms source to induce N and B co-doping. Such highly unique nanoarchitectures offer remarkably improved Li storage performance including high reversible capacity (∼910 mAh g-1 at a current density of 100 mA g-1) with good cycling and rate performances.

  2. A First Principles study on Boron-doped Graphene decorated by Ni-Ti-Mg atoms for Enhanced Hydrogen Storage Performance

    PubMed Central

    Nachimuthu, Santhanamoorthi; Lai, Po-Jung; Leggesse, Ermias Girma; Jiang, Jyh-Chiang

    2015-01-01

    We proposed a new solid state material for hydrogen storage, which consists of a combination of both transition and alkaline earth metal atoms decorating a boron-doped graphene surface. Hydrogen adsorption and desorption on this material was investigated using density functional theory calculations. We find that the diffusion barriers for H atom migration and desorption energies are lower than for the previously designed mediums and the proposed medium can reach the gravimetric capacity of ~6.5 wt % hydrogen, which is much higher than the DOE target for the year 2015. Molecular Dynamics simulations show that metal atoms are stably adsorbed on the B doped graphene surface without clustering, which will enhance the hydrogen storage capacity. PMID:26577659

  3. Improved fiber retention by the use of fillers in graphite fiber/resin matrix composites

    NASA Technical Reports Server (NTRS)

    Gluyas, R. E.; Bowles, K. J.

    1980-01-01

    A variety of matrix fillers were tested for their ability to prevent loss of fiber from graphite fiber/PMR polyimide and graphite fiber/epoxy composites in a fire. The fillers tested included powders of boron, boron carbide lime glass, lead glass, and aluminum. Boron was the most effective and prevented any loss of graphite fiber during burning. Mechanical properties of composites containing boron filler were measured and compared to those of composites containing no filler.

  4. Nitrogen-doped Co/Co9S8/partly-graphitized carbon as durable catalysts for oxygen reduction in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Rui; Dai, Ying; Chen, Baibing; Zou, Jinlong; Jiang, BaoJiang; Fu, Honggang

    2016-03-01

    Durability of catalysts for oxygen reduction reaction (ORR) is the key factor for governing the performance of microbial fuel cells (MFCs). The cobalt (Co) chelated polyaniline (PANI) is used as the nitrogen and carbon sources to prepare the N-doped Co/Co9S8/partly-graphitized carbon (Co/Co9S8/NPGC) catalysts. Structure-activity correlations for Co/Co9S8/NPGC are explored by tuning the heating temperature (600-1000 °C) to investigate how the active components (Co/Co9S8) and N-doped functionalities (N-species) influence the ORR activity. As temperature increases, the gradual crystallization of Co originating from the reduction of Co9S8 is conducted to form the Co/Co9S8 heterojunction. MFCs with Co/Co9S8/NPGC (800 °C) cathode obtain the highest power density (1156 mW m-2) and the lowest charge transfer resistance (11.1 Ω) after 75 d running, which are better than commercial Pt/C (10 wt.%). Although the sole Co9S8 plays a limited role in ORR, the resulting Co/Co9S8 is found to be indispensable to achieve high activity and durability in MFCs cathodes. The dominant ORR pathways of Co/Co9S8/NPGC (800 and 900 °C) are the four-electron O2 reduction, which are attributed to the co-existence of pyridinic N, graphitic N and Co-Nx species. These new N-doped metal sulfide/PGC composites show promise for applications in MFCs.

  5. Carrier transport properties of the Group-IV ferromagnetic semiconductor Ge{sub 1-x}Fe{sub x} with and without boron doping

    SciTech Connect

    Ban, Yoshisuke Wakabayashi, Yuki; Akiyama, Ryota; Nakane, Ryosho; Tanaka, Masaaki

    2014-09-15

    We have investigated the transport and magnetic properties of group-IV ferromagnetic semiconductor Ge{sub 1-x}Fe{sub x} films (x = 1.0 and 2.3%) with and without boron doping grown by molecular beam epitaxy (MBE). In order to accurately measure the transport properties of 100-nm-thick Ge{sub 1-x}Fe{sub x} films, (001)-oriented silicon-on-insulator (SOI) wafers with an ultra-thin Si body layer (∼5 nm) were used as substrates. Owing to the low Fe content, the hole concentration and mobility in the Ge{sub 1-x}Fe{sub x} films were exactly estimated by Hall measurements because the anomalous Hall effect in these films was found to be negligibly small. By boron doping, we increased the hole concentration in Ge{sub 1-x}Fe{sub x} from ∼10{sup 18} cm{sup −3} to ∼10{sup 20} cm{sup −3} (x = 1.0%) and to ∼10{sup 19} cm{sup −3} (x = 2.3%), but no correlation was observed between the hole concentration and magnetic properties. This result presents a contrast to the hole-induced ferromagnetism in III-V ferromagnetic semiconductors.

  6. Structure, electronic and magnetic properties of hexagonal boron nitride sheets doped by 5d transition metal atoms: First-principles calculations and molecular orbital analysis

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaofu; Geng, Zhaohui; Cai, Danyun; Pan, Tongxi; Chen, Yixin; Dong, Liyuan; Zhou, Tiege

    2015-01-01

    A first-principles calculation based on density functional theory is carried out to reveal the geometry, electronic structures and magnetic properties of hexagonal boron nitride sheets (h-BNSs) doped by 5d transitional mental atoms (Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au and Hg) at boron-site (B5d) and nitrogen-site (N5d). Results of pure h-BNS, h-BNS with B vacancy (VB) and N vacancy (VN) are also given for comparison. It is shown that all the h-BNSs doped with 5d atoms possess a C3v local symmetry except for NLu and NHg which have a clear deviation. For the same 5d dopant, the binding energy of B5d is larger than that of N5d, which indicates the substitution of a 5d atom for B is preferred. The total densities of states are presented, where impurity energy levels exist. Besides, the total magnetic moments (TMMs) change regularly with the increment of the 5d atomic number. Theoretical analyses by molecular orbital under C3v symmetry explain the impurity energy levels and TMMs.

  7. Undoped and boron doped diamond nanoparticles as platinum and platinum-ruthenium catalyst support for direct methanol fuel cell application

    NASA Astrophysics Data System (ADS)

    La Torre Riveros, Lyda

    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

  8. The effect of boron doping on the Hall-Petch slope of FeAl (40 at. % Al)

    SciTech Connect

    Pike, L.M.; Liu, C.T. )

    1991-12-01

    This paper reports on the iron aluminide, FeAl, which has good oxidation resistance, low density, and low material cost. However, this aluminide shows limited ductility when tested in air at ambient temperatures. This embrittlement involves the reaction of the moisture in air with the aluminide and the generation of hydrogen at crack tips. By testing in dry oxygen, the environmental effect can be eliminated, but an intergranular fracture mode is still seen. This suggests that the grain boundaries of FeAl are intrinsically weak. It has been shown in both air and oxygen tests of FeAl that microapplying with boron suppresses intergranular fracture and subsequently increases ductility. For Ni{sub 3}Al, in which boron also suppresses intergranular fracture, two explanations of the beneficial effect of boron have been proposed. One claims that boron increases the cohesive strength of the grain boundaries. The other claims that boron enhances slip transfer at the grain boundaries. The primary experimental evidence for increased slip transfer was based on the observation that for powder-extruded (PE) Ni{sub 3}Al, the Hall-Petch slope, k{sub y}, was lowered by the addition of boron. The Hall-Petch equation, which relates yield stress, {sigma}{sub y} = {sigma}{sub o} + k{sub y}d{sup {minus} -.5}, where the intercept stress, {sigma}{sub o}, and the Hall-Petch slope, K{sub y}, are material constants.

  9. Fillers for improved graphite fiber retention by polymer matrix composites

    NASA Technical Reports Server (NTRS)

    House, E. E.; Sheppard, C. H.

    1981-01-01

    The results of a program designed to determine the extent to which elemental boron and boron containing fillers added to the matrix resin of graphite/epoxy composites prevent the release of graphite fibers when the composites are exposed to fire and impact conditions are described. The fillers evaluated were boron, boron carbide and aluminum boride. The conditions evaluated were laboratory simulations of those that could exist in the event of an aircraft crash and burn situation. The baseline (i.e., unfilled) laminates evaluated were prepared from commercially available graphite/epoxy. The baseline and filled laminates' mechanical properties, before and after isothermal and humidity aging, also were compared. It was found that a small amount of graphite fiber was released from the baseline graphite/epoxy laminates during the burn and impact conditions used in this program. However, the extent to which the fibers were released is not considered a severe enough problem to preclude the use of graphite reinforced composites in civil aircraft structure. It also was found that the addition of boron and boron containing fillers to the resin matrix eliminated this fiber release. Mechanical properties of laminates containing the boron and boron containing fillers were lower than those of the baseline laminates. These property degradations for two systems: boron (5 micron) at 2.5 percent filler loading, and boron (5 micron) at 5.0 percent filler loading do not appear severe enough to preclude their use in structural composite applications.

  10. A simple synthesis of nitrogen doped porous graphitic carbon: Electrochemical determination of paracetamol in presence of ascorbic acid and p-aminophenol.

    PubMed

    Biswas, Sudip; Chakraborty, Dipanjan; Das, Rashmita; Bandyopadhyay, Rajib; Pramanik, Panchanan

    2015-08-26

    Graphite paste electrode modified with nitrogen doped porous carbon (NDPC) is used for the detections of paracetamol (PCM), ascorbic acid (AA) and p-aminophenol (PAP) at relatively low concentration. NDPC is synthesized by direct carbonization of Zn(OAc)2 incorporated melamine-formaldehyde resin microsphere. The NDPC shows small pore diameters centered at 3.14 nm and 8.12 nm and has a pseudo graphitic structure with reasonable porous matrix. The lower limit of detections (S/N = 3) for PCM, AA, and PAP are found to be 30 nM, 720 nM and 10 nM respectively. Under optimized experimental condition, the linear ranges of determination for PCM and AA are 1-400 μM, 10-2700 μM respectively in mixture. Similarly for PCM and PAP mixture, the linear ranges of determination are found to be 1-90 μM. It is also used for the analysis of urine and pharmaceutical products with better sensitivity. PMID:26347171

  11. A Simple Synthesis of an N-Doped Carbon ORR Catalyst: Hierarchical Micro/Meso/Macro Porosity and Graphitic Shells.

    PubMed

    Eisenberg, David; Stroek, Wowa; Geels, Norbert J; Sandu, Cosmin S; Heller, Adam; Yan, Ning; Rothenberg, Gadi

    2016-01-11

    Replacing platinum as an oxygen reduction catalyst is an important scientific and technological challenge. Herein we report a simple synthesis of a complex carbon with very good oxygen reduction reaction (ORR) activity at pH 13. Pyrolysis of magnesium nitrilotriacetate yields a carbon with hierarchical micro/meso/macro porosity, resulting from in situ templating by spontaneously forming MgO nanoparticles and from etching by pyrolysis gases. The mesopores are lined with highly graphitic shells. The high ORR activity is attributed to a good balance between high specific surface area and mass transport through the hierarchical porosity, and to improved electronic conductivity through the graphitic shells. This novel carbon has a high surface area (1320 m(2) g(-1) ), and high nitrogen content for a single precursor synthesis (∼6 %). Importantly, its synthesis is both cheap and easily scalable. PMID:26574917

  12. The sonication of graphite in various solvents and surfactants to synthesize high quality graphene as well as the nitrogen doping of graphene

    NASA Astrophysics Data System (ADS)

    Soden, Daniel R.; Bai, Jincheng; Dong, Lifeng

    2014-03-01

    The emergence of graphene in the scientific community has been the cause of much excitement among material scientists due to its unusual physical and photovoltaic properties. However, the much sought after monolayer graphene has proven to be difficult to produce in sufficient quantities This experiment aims to correct some of these problems, concerning itself with the synthesis of high quality graphene through continuous sonication with surfactant or solvent added throughout, as well as the issue of graphene quality as a function of sonication time. This was accomplished through the creation and addition of a solvent or surfactant solution to a graphite suspension during sonication lasting for 50, 80, 110,140, 170, and 200 minutes. The resulting suspension was then filtrated to separate out the graphene. Following this, the graphene was then doped through various methods with nitrogen to alter its properties. This completely physical method of graphene synthesis and doping provides a much simpler and more environmentally safe way to achieve the highly desired few layer graphene, and will hopefully allow for greater use of the substance in industry and its implementation into new technology. L. F. Dong acknowledges the support of the National Science Foundation (DMR-1126375 and DMR-1126375), the Faculty Research Grant and the Sabbatical Leave Award from Missouri State University.

  13. Catalyst-free synthesis of nitrogen-doped graphene via thermal annealing graphite oxide with melamine and its excellent electrocatalysis.

    PubMed

    Sheng, Zhen-Huan; Shao, Lin; Chen, Jing-Jing; Bao, Wen-Jing; Wang, Feng-Bin; Xia, Xing-Hua

    2011-06-28

    The electronic and chemical properties of graphene can be modulated by chemical doping foreign atoms and functional moieties. The general approach to the synthesis of nitrogen-doped graphene (NG), such as chemical vapor deposition (CVD) performed in gas phases, requires transitional metal catalysts which could contaminate the resultant products and thus affect their properties. In this paper, we propose a facile, catalyst-free thermal annealing approach for large-scale synthesis of NG using low-cost industrial material melamine as the nitrogen source. This approach can completely avoid the contamination of transition metal catalysts, and thus the intrinsic catalytic performance of pure NGs can be investigated. Detailed X-ray photoelectron spectrum analysis of the resultant products shows that the atomic percentage of nitrogen in doped graphene samples can be adjusted up to 10.1%. Such a high doping level has not been reported previously. High-resolution N1s spectra reveal that the as-made NG mainly contains pyridine-like nitrogen atoms. Electrochemical characterizations clearly demonstrate excellent electrocatalytic activity of NG toward the oxygen reduction reaction (ORR) in alkaline electrolytes, which is independent of nitrogen doping level. The present catalyst-free approach opens up the possibility for the synthesis of NG in gram-scale for electronic devices and cathodic materials for fuel cells and biosensors. PMID:21574601

  14. Direct assessment of the mechanical modulus of graphene co-doped with low concentrations of boron-nitrogen by a non-contact approach

    NASA Astrophysics Data System (ADS)

    Pan, Shun-Hsien; Medina, Henry; Wang, Sheng-Bo; Chou, Li-Jen; Wang, Zhiming M.; Chen, Kuei-Hsien; Chen, Li-Chyong; Chueh, Yu-Lun

    2014-07-01

    Boron and nitrogen co-doping has been shown to be an effective way to induce a band gap in graphene for electrical applications but only a few theoretical studies have been done to understand the elastic and mechanical properties of the modified graphene. Until now, no experimental assessment of the mechanical modulus of boron-nitrogen-doped graphene (BNG) has been reported in the literature. Here, we demonstrate a novel non-contact approach to determine the in-plane stiffness of BNG at low BN concentrations. The in-plane stiffness of BNG with 2 at% BN concentration was estimated to be about 309 N m-1, which is lower than that of pristine graphene, in good agreement with some theoretical studies. Moreover, we correlated the conductivity of BNG with induced strain and found the BNG to be more sensitive than pristine graphene in response to externally applied strain. This result indicates that BNG is a more suitable material than graphene for strain sensor applications.Boron and nitrogen co-doping has been shown to be an effective way to induce a band gap in graphene for electrical applications but only a few theoretical studies have been done to understand the elastic and mechanical properties of the modified graphene. Until now, no experimental assessment of the mechanical modulus of boron-nitrogen-doped graphene (BNG) has been reported in the literature. Here, we demonstrate a novel non-contact approach to determine the in-plane stiffness of BNG at low BN concentrations. The in-plane stiffness of BNG with 2 at% BN concentration was estimated to be about 309 N m-1, which is lower than that of pristine graphene, in good agreement with some theoretical studies. Moreover, we correlated the conductivity of BNG with induced strain and found the BNG to be more sensitive than pristine graphene in response to externally applied strain. This result indicates that BNG is a more suitable material than graphene for strain sensor applications. Electronic supplementary

  15. Bulk-bronzied graphites for plasma-facing components in ITER (International Thermonuclear Experimental Reactor)

    SciTech Connect

    Hirooka, Y.; Conn, R.W.; Doerner, R.; Khandagle, M. . Inst. of Plasma and Fusion Research); Causey, R.; Wilson, K. ); Croessmann, D.; Whitley, J. ); Holland, D.; Smolik, G. ); Matsuda, T.; Sogabe, T. (Toyo Tanso Co. Ltd., O

    1990-06-01

    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{degree}C. Plasma interaction induced erosion of bulk-boronized graphites is observed to be a factor of 2--3 smaller than that of pyrolytic graphite, in regimes of physical sputtering, chemical sputtering and radiation enhanced sublimation. Postbombardment thermal desorption spectroscopy indicates that bulk-boronized graphites enhance recombinative desorption of deuterium, which leads to a suppression of the formation of deuterocarbon due to chemical sputtering. The tritium inventory in graphite has been found to decrease by an order of magnitude due to 10 wt % bulk-boronization at temperatures above 1000{degree}C. The critical heat flux to induce cracking for bulk-boronized graphites has been found to be essentially the same as that for non-boronized graphites. Also, 10 wt % bulk-boronization of graphite hinders air oxidation nearly completely at 800{degree}C and reduces the steam oxidation rate by a factor of 2--3 at around 1100 and 1350{degree}C. 38 refs., 5 figs.

  16. Coatings for graphite fibers

    NASA Technical Reports Server (NTRS)

    Galasso, F. S.; Scola, D. A.; Veltri, R. D.

    1980-01-01

    Graphite fibers released from composites during burning or an explosion caused shorting of electrical and electronic equipment. Silicon carbide, silica, silicon nitride and boron nitride were coated on graphite fibers to increase their electrical resistances. Resistances as high as three orders of magnitude higher than uncoated fiber were attained without any significant degradation of the substrate fiber. An organo-silicone approach to produce coated fibers with high electrical resistance was also used. Celion 6000 graphite fibers were coated with an organo-silicone compound, followed by hydrolysis and pyrolysis of the coating to a silica-like material. The shear and flexural strengths of composites made from high electrically resistant fibers were considerably lower than the shear and flexural strengths of composites made from the lower electrically resistant fibers. The lower shear strengths of the composites indicated that the coatings on these fibers were weaker than the coating on the fibers which were pyrolyzed at higher temperature.

  17. Metal-doped graphene layers composed with boron nitride-graphene as an insulator: a nano-capacitor.

    PubMed

    Monajjemi, Majid

    2014-11-01

    A model of a nanoscale dielectric capacitor composed of a few dopants has been investigated in this study. This capacitor includes metallic graphene layers which are separated by an insulating medium containing a few h-BN layers. It has been observed that the elements from group IIIA of the periodic table are more suitable as dopants for hetero-structures of the {metallic graphene/hBN/metallic graphene} capacitors compared to those from groups IA or IIA. In this study, we have specifically focused on the dielectric properties of different graphene/h-BN/graphene including their hetero-structure counterparts, i.e., Boron-graphene/h-BN/Boron-graphene, Al-graphene/h-BN/Al-graphene, Mg-graphene/h-BN/Mg-graphene, and Be-graphene/h-BN/Be-graphene stacks for monolayer form of dielectrics. Moreover, we studied the multi dielectric properties of different (h-BN)n/graphene hetero-structures of Boron-graphene/(h-BN)n/Boron-graphene. PMID:25359456

  18. Effect of nitrogen as co-dopant in carbon and boron-doped ZnO clusters

    NASA Astrophysics Data System (ADS)

    Kapila, Neha; Sharma, Gaurav; Mudahar, Isha; Sharma, Hitesh

    2016-05-01

    The effect of N as co-dopant have been investigated on magnetic properties of C and B-doped (ZnO)n clusters (n = 1 - 16) using spin-polarized density functional theory. Total energy calculations show that C and N more stable when substituted at O site, whereas B is more stable at the Zn site. The B:N co-doping is energetically more stable than C:N which is more stable than N:N doping. C and N atoms do not show tendency to form clusters when doped separately. The magnetic moment (MM) of C-doped ZnO clusters is enhanced significantly with N co-doping. The MM of 2 μB, 1 μB and 1 μB per atom is induced due to C, N and B respectively. The MM of 3 μB or 5 μB and 2 μB or 4 μB are observed for co-doping of 2C:N and C:2N respectively. In contrary, the MM in 2B:N and B:2N co-doped (ZnO)n remains 1 μB for n=2-4, 12 and 16. The results are in agreement with the available theoretical results.

  19. Graphite–boron composite heater in a Kawai-type apparatus: the inhibitory effect of boron oxide and countermeasures

    NASA Astrophysics Data System (ADS)

    Xie, Longjian; Yoneda, Akira; Yoshino, Takashi; Fei, Hongzhan; Ito, Eiji

    2016-04-01

    We have investigated the performance of a graphite-boron composite (GBC) with 3 wt % boron as a precursor for a boron-doped diamond heater in a Kawai-type apparatus at 15 GPa. We first tested a machinable cylinder of GBC sintered at 1000°C in Ar/H2 gas (99:1 molar ratio). Boron oxide (B2O3) formed during sintering frequently hindered the GBC heater from stable operation at temperatures higher than 1400°C by producing melt throughout the heater together with oxide and/or silicates. We then rinsed the GBC heater in hydrochloric acid to remove B2O3. After rinsing, we succeeded in stably generating temperatures higher than 2000°C. We also improved a molding process of different-sized GBC tubes for convenient use and tested the molded GBC heater. It was free from the B2O3 problem. The electromotive force of the W/Re thermocouple was successfully monitored up to 2400°C.

  20. Boron, bismuth co-doping of gallium arsenide and other compounds for photonic and heterojunction bipolar transistor devices

    SciTech Connect

    Mascarenhas, Angelo

    2015-07-07

    Isoelectronic co-doping of semiconductor compounds and alloys with acceptors and deep donors is sued to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. For example, Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, B and Bi, to customize solar cells, and other semiconductor devices. Isoelectronically co-doped Group II-VI compounds and alloys are also included.