WorldWideScience

Sample records for berkelium nitrides

  1. New berkelium isotope: 242Bk

    International Nuclear Information System (INIS)

    A new isotope of berkelium, 242Bk, was produced with a cross section of approx. 10 μb in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7 +- 1.3 minutes. The branching ratio for this isotope for alpha decay is less than 1% and that for spontaneous fission is less than 0.03%. 2 figures, 2 tables

  2. Characterization of berkelium(III) dipicolinate and borate compounds in solution and the solid state.

    Science.gov (United States)

    Silver, Mark A; Cary, Samantha K; Johnson, Jason A; Baumbach, Ryan E; Arico, Alexandra A; Luckey, Morgan; Urban, Matthew; Wang, Jamie C; Polinski, Matthew J; Chemey, Alexander; Liu, Guokui; Chen, Kuan-Wen; Van Cleve, Shelley M; Marsh, Matthew L; Eaton, Teresa M; van de Burgt, Lambertus J; Gray, Ashley L; Hobart, David E; Hanson, Kenneth; Maron, Laurent; Gendron, Frédéric; Autschbach, Jochen; Speldrich, Manfred; Kögerler, Paul; Yang, Ping; Braley, Jenifer; Albrecht-Schmitt, Thomas E

    2016-08-26

    Berkelium is positioned at a crucial location in the actinide series between the inherently stable half-filled 5f(7) configuration of curium and the abrupt transition in chemical behavior created by the onset of a metastable divalent state that starts at californium. However, the mere 320-day half-life of berkelium's only available isotope, (249)Bk, has hindered in-depth studies of the element's coordination chemistry. Herein, we report the synthesis and detailed solid-state and solution-phase characterization of a berkelium coordination complex, Bk(III)tris(dipicolinate), as well as a chemically distinct Bk(III) borate material for comparison. We demonstrate that berkelium's complexation is analogous to that of californium. However, from a range of spectroscopic techniques and quantum mechanical calculations, it is clear that spin-orbit coupling contributes significantly to berkelium's multiconfigurational ground state. PMID:27563098

  3. Boron nitride composites

    Science.gov (United States)

    Kuntz, Joshua D.; Ellsworth, German F.; Swenson, Fritz J.; Allen, Patrick G.

    2016-02-16

    According to one embodiment, a composite product includes hexagonal boron nitride (hBN), and a plurality of cubic boron nitride (cBN) particles, wherein the plurality of cBN particles are dispersed in a matrix of the hBN. According to another embodiment, a composite product includes a plurality of cBN particles, and one or more borate-containing binders.

  4. Boron Nitride Nanotubes

    Science.gov (United States)

    Smith, Michael W. (Inventor); Jordan, Kevin (Inventor); Park, Cheol (Inventor)

    2012-01-01

    Boron nitride nanotubes are prepared by a process which includes: (a) creating a source of boron vapor; (b) mixing the boron vapor with nitrogen gas so that a mixture of boron vapor and nitrogen gas is present at a nucleation site, which is a surface, the nitrogen gas being provided at a pressure elevated above atmospheric, e.g., from greater than about 2 atmospheres up to about 250 atmospheres; and (c) harvesting boron nitride nanotubes, which are formed at the nucleation site.

  5. Nitrogen Availability Of Nitriding Atmosphere In Controlled Gas Nitriding Processes

    Directory of Open Access Journals (Sweden)

    Michalski J.

    2015-06-01

    Full Text Available Parameters which characterize the nitriding atmosphere in the gas nitriding process of steel are: the nitriding potential KN, ammonia dissociation rate α and nitrogen availabilitymN2. The article discusses the possibilities of utilization of the nitriding atmosphere’s nitrogen availability in the design of gas nitriding processes of alloyed steels in atmospheres derived from raw ammonia, raw ammonia diluted with pre-dissociated ammonia, with nitrogen, as well as with both nitrogen and pre-dissociated ammonia. The nitriding processes were accomplished in four series. The parameters selected in the particular processes were: process temperature (T, time (t, value of nitriding potential (KN, corresponding to known dissociation rate of the ammonia which dissociates during the nitriding process (α. Variable parameters were: nitrogen availability (mN2, composition of the ingoing atmosphere and flow rate of the ingoing atmosphere (FIn.

  6. Metal Nitrides for Plasmonic Applications

    DEFF Research Database (Denmark)

    Naik, Gururaj V.; Schroeder, Jeremy; Guler, Urcan;

    2012-01-01

    Metal nitrides as alternatives to metals such as gold could offer many advantages when used as plasmonic material. We show that transition metal nitrides can replace metals providing equally good optical performance for many plasmonic applications.......Metal nitrides as alternatives to metals such as gold could offer many advantages when used as plasmonic material. We show that transition metal nitrides can replace metals providing equally good optical performance for many plasmonic applications....

  7. Gallium nitride electronics

    Science.gov (United States)

    Rajan, Siddharth; Jena, Debdeep

    2013-07-01

    In the past two decades, there has been increasing research and industrial activity in the area of gallium nitride (GaN) electronics, stimulated first by the successful demonstration of GaN LEDs. While the promise of wide band gap semiconductors for power electronics was recognized many years before this by one of the contributors to this issue (J Baliga), the success in the area of LEDs acted as a catalyst. It set the field of GaN electronics in motion, and today the technology is improving the performance of several applications including RF cell phone base stations and military radar. GaN could also play a very important role in reducing worldwide energy consumption by enabling high efficiency compact power converters operating at high voltages and lower frequencies. While GaN electronics is a rapidly evolving area with active research worldwide, this special issue provides an opportunity to capture some of the great advances that have been made in the last 15 years. The issue begins with a section on epitaxy and processing, followed by an overview of high-frequency HEMTs, which have been the most commercially successful application of III-nitride electronics to date. This is followed by review and research articles on power-switching transistors, which are currently of great interest to the III-nitride community. A section of this issue is devoted to the reliability of III-nitride devices, an area that is of increasing significance as the research focus has moved from not just high performance but also production-worthiness and long-term usage of these devices. Finally, a group of papers on new and relatively less studied ideas for III-nitride electronics, such as interband tunneling, heterojunction bipolar transistors, and high-temperature electronics is included. These areas point to new areas of research and technological innovation going beyond the state of the art into the future. We hope that the breadth and quality of articles in this issue will make it

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

    Science.gov (United States)

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

    2016-08-01

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

  9. Optical characterization of gallium nitride

    NARCIS (Netherlands)

    Kirilyuk, Victoria

    2002-01-01

    Group III-nitrides have been considered a promising system for semiconductor devices since a few decades, first for blue- and UV-light emitting diodes, later also for high-frequency/high-power applications. Due to the lack of native substrates, heteroepitaxially grown III-nitride layers are usually

  10. Functionalized boron nitride nanotubes

    Science.gov (United States)

    Sainsbury, Toby; Ikuno, Takashi; Zettl, Alexander K

    2014-04-22

    A plasma treatment has been used to modify the surface of BNNTs. In one example, the surface of the BNNT has been modified using ammonia plasma to include amine functional groups. Amine functionalization allows BNNTs to be soluble in chloroform, which had not been possible previously. Further functionalization of amine-functionalized BNNTs with thiol-terminated organic molecules has also been demonstrated. Gold nanoparticles have been self-assembled at the surface of both amine- and thiol-functionalized boron nitride Nanotubes (BNNTs) in solution. This approach constitutes a basis for the preparation of highly functionalized BNNTs and for their utilization as nanoscale templates for assembly and integration with other nanoscale materials.

  11. Effects of Aqueous Vapour Consistence in Nitriding Furnace on the Quality of the Sintered Nitride

    Institute of Scientific and Technical Information of China (English)

    WANGZijiang

    1998-01-01

    If the aqueous vapour consistence is too high(>0.7%),it is very disadvantageous to the sintered products in the nitriding furnace,when silcon nitride bonded silicon carbide products are synthesized by nitridation of silicon.

  12. Hard carbon nitride and method for preparing same

    Science.gov (United States)

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

    1992-01-01

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

  13. Study of the Active Screen Plasma Nitriding

    Institute of Scientific and Technical Information of China (English)

    Zhao Cheng; C. X. Li; H. Dong; T. Bell

    2004-01-01

    Active screen plasma nitriding (ASPN) is a novel nitriding process, which overcomes many of the practical problems associated with the conventional DC plasma nitriding (DCPN). Experimental results showed that the metallurgical characteristics and hardening effect of 722M24 steel nitrided by ASPN at both floating potential and anodic (zero) potential were similar to those nitrided by DCPN. XRD and high-resolution SEM analysis indicated that iron nitride particles with sizes in sub-micron scale were deposited on the specimen surface in AS plasma nitriding. These indicate that the neutral iron nitride particles, which are sputtered from the active screen and transferred through plasma to specimen surface, are considered to be the dominant nitrogen carder in ASPN. The OES results show that NH could not be a critical species in plasma nitriding.

  14. Boron nitride converted carbon fiber

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-04-05

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

  15. Microstructural investigation of iron nitride layers formed by low-temperature gaseous nitriding

    NARCIS (Netherlands)

    Inia, DK; Vredenberg, AM; Boerma, DO; Tichelaar, FD; Schut, H; van Veen, A

    1999-01-01

    Iron nitride layers were formed by a novel low-temperature gaseous nitriding process. Nitriding occurs at a temperature of 325 degrees C through NH3 decomposition at the surface of Ni (25 nm) coated Fe, followed by N transport through the Ni film into the underlying Fe, where nitride precipitation t

  16. Plasmonic titanium nitride nanostructures for perfect absorbers

    DEFF Research Database (Denmark)

    Guler, Urcan; Li, Wen-Wei; Kinsey, Nathaniel;

    2013-01-01

    We propose a metamaterial based perfect absorber in the visible region, and investigate the performance of titanium nitride as an alternative plasmonic material. Numerical and experimental results reveal that titanium nitride performs better than gold as a plasmonic absorbing material...

  17. Ion nitridation - physical and technological aspects

    International Nuclear Information System (INIS)

    Ion nitridation, is a technique which allows the formation of a controlled thickness of nitrides in the surface of the material, using this material as the cathode in a low pressure glow discharge, which presents many advantages over the conventional method. A brief review of the ion nitriding technique, the physical fenomena involved, and we discuss technological aspects of this method, are presented. (Author)

  18. Mathematical Modelling of Nitride Layer Growth of Low Temperature Gas and Plasma Nitriding of AISI 316L

    Directory of Open Access Journals (Sweden)

    Triwiyanto A.

    2014-07-01

    Full Text Available This paper present mathematical model which developed to predict the nitrided layer thickness (case depth of gas nitrided and plasma nitrided austenitic stainless steel according to Fick’s first law for pure iron by adapting and manipulating the Hosseini’s model to fit the diffusion mechanism where nitrided structure formed by nitrided AISI 316L austenitic stainless steel. The mathematical model later tested against various actual gas nitriding and plasma nitriding experimental results with varying nitriding temperature and nitriding duration to see whether the model managed to successfully predict the nitrided layer thickness. This model predicted the coexistence of ε-Fe2-3N and γ΄-Fe4N under the present nitriding process parameters. After the validation process, it is proven that the mathematical model managed to predict the nitrided layer growth of the gas nitrided and plasma nitrided of AISI 316L SS up to high degree of accuracy.

  19. Hydrodenitrogenation of pyridine over transition metal nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Milad, I.K.; Smith, K.J. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical Engineering

    1997-11-01

    The use of transition metal nitrides (TMN) as catalysts for hydrodenitrogenation (HDN) was discussed. A study was conducted in which a series of unsupported and supported Mo, Fe, W, Co, Nb, Cr, V and Ti nitrides were examined as catalysts for the HDN of pyridine at atmospheric pressure and 350 degrees C. The catalysts were prepared by temperature programmed nitridation of the metal oxide with NH{sub 3}. It was shown that a single nitride phase was present in each of the catalysts. The Mo nitride showed the greatest activity per gram of catalyst. Co and Fe nitrides showed the highest activities per surface area of the unsupported catalyst. Metal nitrides with lower heats of formation showed higher HDN activity. 1 tab.

  20. Synthesis of ternary nitrides by mechanochemical alloying

    DEFF Research Database (Denmark)

    Jacobsen, C.J.H.; Zhu, J.J.; Lindelov, H.;

    2002-01-01

    Ternary metal nitrides ( of general formula MxM'N-y(z)) attract considerable interest because of their special mechanical, electrical, magnetic, and catalytic properties. Usually they are prepared by ammonolysis of ternary oxides (MxM'O-y(m)) at elevated temperatures. We show that ternary...... transition metal nitrides are also obtained by nitridation of the corresponding ternary carbide at 823 K. This transformation appears to occur by solid-state diffusion of carbide and nitride ions. To establish more general synthesis schemes for ternary nitrides, we have focused on the preparation of ternary...... nitrides by mechanochemical alloying of a binary transition metal nitride (MxN) with an elemental transition metal. In this way, we have been able to prepare Fe3Mo3N and Co3Mo3N by ball-milling of Mo2N with Fe and Co, respectively. The transformation sequence from the starting materials ( the binary...

  1. Internal nitride formation during gas-phase thermal nitridation of titanium

    OpenAIRE

    Ajikumar, PK; M. Kamruddin; Shankar, P; Gouda, Ramakrishna; Balamurugan, AK; Nithya, R.; Tyagi, AK; Jayaram, V; Biswas, SK; Raj, Baldev

    2009-01-01

    Titanium nitride surface layers were prepared by gas-phase thermal nitridation of pure titanium in an ammonia atmosphere at 1373 K for different times. In addition to the surface nitride layer, nitride/hydride formation was observed in the bulk of the specimen. The cross-section of the specimen was characterized by various techniques such as optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, secondary ion mass spectrometry and nanomechanical testing, ...

  2. A Novel kind of Air Cooling Bainite Nitriding Steel and Plasma Nitriding Test

    Institute of Scientific and Technical Information of China (English)

    LI Xin-sheng; LIANG Shu-rong

    2004-01-01

    In order to avoid serious distortion and cracking that may occur with nitrided parts while quenching and tempering, a novel kind of air cooling bainite nitriding steel consisting of Ct, Mo, Mn and Si was developed. After normalized and high temperature tempered, the tested steel has satisfactory strength, toughness and microstructure as well as good nitriding properties.

  3. Silicon nitride-fabrication, forming and properties

    International Nuclear Information System (INIS)

    This article, which is a literature survey of the recent years, includes description of several methods for the formation of silicone nitride, and five methods of forming: Reaction-bonded silicon nitride, sintering, hot pressing, hot isostatic pressing and chemical vapour deposition. Herein are also included data about mechanical and physical properties of silicon nitride and the relationship between the forming method and the properties. (author)

  4. Property database of TRU nitride fuel

    OpenAIRE

    西 剛史; 荒井 康夫; 高野 公秀; 倉田 正輝

    2014-01-01

    The purpose of this study is to prepare a property database of nitride fuel needed for the fuel design of accelerator-driven system (ADS) for transmutation of minor actinide (MA). Nitride fuel of ADS is characterized by high content of Pu and MA as principal components, and addition of a diluent material such as ZrN. Experimental data or evaluated values from the raw data on properties Pu and MA nitrides, and nitride solid solutions containing ZrN are collected and summarized, which cover the...

  5. Nucleation of iron nitrides during gaseous nitriding of iron; the effect of a preoxidation treatment

    DEFF Research Database (Denmark)

    Friehling, Peter B.; Poulsen, Finn Willy; Somers, Marcel A.J.

    2001-01-01

    grains. On prolonged nitriding, immediate nucleation at the surface of iron grains becomes possible. Calculated incubation times for the nucleation of gamma'-Fe4N1-x during nitriding are generally longer than those observed experimentally in the present work. The incubation time is reduced dramatically......The nucleation of iron nitrides during gaseous nitriding has been investigated using light microscopy and X-ray diffraction. Initially, the nucleation of gamma'-Fe4N1-x on a pure iron surface starts at grain boundaries meeting the surface, from where the nitride grains grow laterally into the iron...

  6. Low temperature anodic bonding to silicon nitride

    DEFF Research Database (Denmark)

    Weichel, Steen; Reus, Roger De; Bouaidat, Salim;

    2000-01-01

    Low-temperature anodic bonding to stoichiometric silicon nitride surfaces has been performed in the temperature range from 3508C to 4008C. It is shown that the bonding is improved considerably if the nitride surfaces are either oxidized or exposed to an oxygen plasma prior to the bonding. Both bulk...

  7. PECVD silicon nitride diaphragms for condenser microphones

    NARCIS (Netherlands)

    Scheeper, P.R.; Voorthuyzen, J.A.; Bergveld, P.

    1991-01-01

    The application of plasma-enhanced chemical vapour deposited (PECVD) silicon nitride as a diaphragm material for condenser microphones has been investigated. By means of adjusting the SiH4/NH3 gas-flow composition, silicon-rich silicon nitride films have been obtained with a relatively low tensile s

  8. Method of preparation of uranium nitride

    Science.gov (United States)

    Kiplinger, Jaqueline Loetsch; Thomson, Robert Kenneth James

    2013-07-09

    Method for producing terminal uranium nitride complexes comprising providing a suitable starting material comprising uranium; oxidizing the starting material with a suitable oxidant to produce one or more uranium(IV)-azide complexes; and, sufficiently irradiating the uranium(IV)-azide complexes to produce the terminal uranium nitride complexes.

  9. Atomic Resolution Microscopy of Nitrides in Steel

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson

    2014-01-01

    MN and CrMN type nitride precipitates in 12%Cr steels have been investigated using atomic resolution microscopy. The MN type nitrides were observed to transform into CrMN both by composition and crystallography as Cr diffuses from the matrix into the MN precipitates. Thus a change from one...

  10. Thermodynamics, kinetics and process control of nitriding

    DEFF Research Database (Denmark)

    Mittemeijer, Eric J.; Somers, Marcel A. J.

    1997-01-01

    , the nitriding result is determined largely by kinetics. Nitriding kinetics are shown to be characterised by local near equilibria and stationary states at surfaces and interfaces, and the diffusion coefficient of nitrogen in the various phases, for which new data are presented. The necessary background...

  11. Thermodynamics, kinetics and process control of nitriding

    DEFF Research Database (Denmark)

    Mittemeijer, Eric J.; Somers, Marcel A. J.

    1999-01-01

    , the nitriding result is determined largely by the kinetics of the process. The nitriding kinetics have been shown to be characterised by the occurring local near-equilibria and stationary states at surfaces and interfaces, and the diffusion coefficient of nitrogen in the various phases, for which new data have...

  12. High hardness of alloyed ferrite after nitriding

    International Nuclear Information System (INIS)

    Detailed layer-by layer structure and phase analyses of the diffusion layer of nitrided binary alloys of iron with aluminium, chromium, vanadium and titanium have been carried out by means of a complex technique. Transition d-metals (chromium, vanadium and titanium) raise to a greater degree the solubility of nitrogen in the α solid solution, sharply increases the hardness of ferrite and decrease the depth of the layer. Nitrided binary alloys of iron with chromium, vanadium and titanium are strengthened through precipitation from the nitrogen-saturated α-solid solution of nitrides of alloying elements TiN, VN and CrN of a structure B1. A maximum hardness of ferrite alloyed by chromium, vanadium and titanium is observed after nitriding at 550 deg C when the precipitated special nitrides are fully coherent with the α matrix

  13. Cathodic Cage Plasma Nitriding: An Innovative Technique

    Directory of Open Access Journals (Sweden)

    R. R. M. de Sousa

    2012-01-01

    Full Text Available Cylindrical samples of AISI 1020, AISI 316, and AISI 420 steels, with different heights, were simultaneously treated by a new technique of ionic nitriding, entitled cathodic cage plasma nitriding (CCPN, in order to evaluate the efficiency of this technique to produce nitrided layers with better properties compared with those obtained using conventional ionic nitriding technique. This method is able to eliminate the edge effect in the samples, promoting a better uniformity of temperature, and consequently, a smaller variation of the thickness/height relation can be obtained. The compound layers were characterized by X-ray diffraction, optical microscopy, and microhardness test profile. The results were compared with the properties of samples obtained with the conventional nitriding, for the three steel types. It was verified that samples treated by CCPN process presented, at the same temperature, a better uniformity in the thickness and absence of the edge effect.

  14. Solvothermal synthesis: a new route for preparing nitrides

    CERN Document Server

    Demazeau, G; Denis, A; Largeteau, A

    2002-01-01

    Solvothermal synthesis appears to be an interesting route for preparing nitrides such as gallium nitride and aluminium nitride, using ammonia as solvent. A nitriding additive is used to perform the reaction and, in the case of gallium nitride, is encapsulated by melt gallium. The syntheses are performed in the temperature range 400-800 deg. C and in the pressure range 100-200 MPa. The synthesized powders are characterized by x-ray diffraction and scanning electron microscopy. Finely divided gallium nitride GaN and aluminium nitride AlN, both with wurtzite-type structure, can be obtained by this route.

  15. Electron spectroscopy of dilute nitrides

    International Nuclear Information System (INIS)

    The application of electron spectroscopies in dilute nitride semiconductor research for both chemical analysis and the determination of electronic and lattice vibrational properties is described. X-ray photoelectron spectroscopy of the nitrogen bonding configurations in dilute InNxSb1-x and InNxAs1-x alloys is presented. High resolution electron-energy-loss spectroscopy (HREELS) of the plasmon excitations in InNxSb1-x is shown to provide information on the electronic properties of the material, before and after annealing. HREELS is also used to investigate the GaN-like phonon modes in GaNxAs1-x alloys

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

    OpenAIRE

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

    2014-01-01

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

  17. Kinetic process of nitridation on the α-sapphire surface

    Institute of Scientific and Technical Information of China (English)

    Tang Xingzhou; Li Shuping; Kang Junyong; Chen Jiaqi

    2014-01-01

    We established a model to simulate the growth process of nitridation and clarified the inner mechanisms of nitridation and over-nitridation by combining the kinetic Monte Carlo and molecular dynamics methods.Supported by reflection high-energy electron diffraction results with growth in an MBE system,the tendency of nitridation on α-sapphire in different conditions was observed and analyzed.The best conditions for nitridation on the α-sapphire surface are found by our simulation.

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

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  19. Process for the production of metal nitride sintered bodies and resultant silicon nitride and aluminum nitride sintered bodies

    Science.gov (United States)

    Yajima, S.; Omori, M.; Hayashi, J.; Kayano, H.; Hamano, M.

    1983-01-01

    A process for the manufacture of metal nitride sintered bodies, in particular, a process in which a mixture of metal nitrite powders is shaped and heated together with a binding agent is described. Of the metal nitrides Si3N4 and AIN were used especially frequently because of their excellent properties at high temperatures. The goal is to produce a process for metal nitride sintered bodies with high strength, high corrosion resistance, thermal shock resistance, thermal shock resistance, and avoidance of previously known faults.

  20. Friction Characteristics of Nitrided Layers on AISI 430 Ferritic Stainless Steel Obtained by Various Nitriding Processes

    Directory of Open Access Journals (Sweden)

    Hakan AYDIN

    2013-03-01

    Full Text Available The influence of plasma, gas and salt-bath nitriding techniques on the friction coefficient of AISI 430 ferritic stainless steel was studied in this paper. Samples were plasma nitrided in 80 % N2 + 20 % H2 atmosphere at 450 °C and 520 °C for 8 h at a pressure of 2 mbar, gas nitrided in NH3 and CO2 atmosphere at 570 °C for 13 h and salt-bath nitrided in a cyanide-cyanate salt-bath at 570 °C for 1.5 h. Characterisation of nitrided layers on the ferritic stainless steel was carried out by means of microstructure, microhardness, surface roughness and friction coefficient measurements. Friction characteristics of the nitrided layers on the 430 steel were investigated using a ball-on-disc friction-wear tester with a WC-Co ball as the counter-body under dry sliding conditions. Analysis of wear tracks was carried out by scanning electron microscopy. Maximum hardness and maximum case depth were achieved on the plasma nitrided sample at 520 ºC for 8 h. The plasma and salt-bath nitriding techniques significantly decreased the average surface roughness of the 430 ferritic stainless steel. The friction test results showed that the salt-bath nitrided layer had better friction-reducing ability than the other nitrided layers under dry sliding conditions. Furthermore, the friction characteristic of the plasma nitrided layer at 520 ºC was better than that of the plasma nitrided layer at 450 °C.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3819

  1. Plasma Nitriding of Low Alloy Sintered Steels

    Institute of Scientific and Technical Information of China (English)

    Shiva Mansoorzadeh; Fakhreddin Ashrafizadeh; Xiao-Ying Li; Tom Bell

    2004-01-01

    Fe-3Cr-0.5Mo-0.3C and Fe-3Cr-1.4Mn-0.5Mo-0.367C sintered alloys were plasma nitrided at different temperatures. Characterization was performed by microhardness measurement, optical microscopy, SEM and XRD. Both materials had similar nitriding case properties. 1.4% manganese did not change the as-sintered microstructure considerably.It was observed that monophase compound layer, γ, formed with increasing temperature. Compound layer thickness increased with increasing temperature while nitriding depth increased up to a level and then decreased. Core softening was more pronounced at higher temperature owing to cementite coarsening.

  2. Internal nitride formation during gas-phase thermal nitridation of titanium

    International Nuclear Information System (INIS)

    Titanium nitride surface layers were prepared by gas-phase thermal nitridation of pure titanium in an ammonia atmosphere at 1373 K for different times. In addition to the surface nitride layer, nitride/hydride formation was observed in the bulk of the specimen. The cross-section of the specimen was characterized by various techniques such as optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, secondary ion mass spectrometry and nanomechanical testing, and the mechanism of formation of these phases is discussed.

  3. Plasma nitriding of AISI 52100 ball bearing steel and effect of heat treatment on nitrided layer

    Indian Academy of Sciences (India)

    Ravindra Kumar; J Alphonsa; Ram Prakash; K S Boob; J Ghanshyam; P A Rayjada; P M Raole; S Mukherjee

    2011-02-01

    In this paper an effort has been made to plasma nitride the ball bearing steel AISI 52100. The difficulty with this specific steel is that its tempering temperature (∼170–200°C) is much lower than the standard processing temperature (∼460–580°C) needed for the plasma nitriding treatment. To understand the mechanism, effect of heat treatment on the nitrided layer steel is investigated. Experiments are performed on three different types of ball bearing races i.e. annealed, quenched and quench-tempered samples. Different gas compositions and process temperatures are maintained while nitriding these samples. In the quenched and quench-tempered samples, the surface hardness has decreased after plasma nitriding process. Plasma nitriding of annealed sample with argon and nitrogen gas mixture gives higher hardness in comparison to the hydrogen–nitrogen gas mixture. It is reported that the later heat treatment of the plasma nitrided annealed sample has shown improvement in the hardness of this steel. X-ray diffraction analysis shows that the dominant phases in the plasma nitrided annealed sample are (Fe2−3N) and (Fe4N), whereas in the plasma nitrided annealed sample with later heat treatment only -Fe peak occurs.

  4. Titanium nitride nanoparticles for therapeutic applications

    DEFF Research Database (Denmark)

    Guler, Urcan; Kildishev, Alexander V.; Boltasseva, Alexandra;

    2014-01-01

    Titanium nitride nanoparticles exhibit plasmonic resonances in the biological transparency window where high absorption efficiencies can be obtained with small dimensions. Both lithographic and colloidal samples are examined from the perspective of nanoparticle thermal therapy. © 2014 OSA....

  5. Progress in molecular uranium-nitride chemistry

    OpenAIRE

    King, David M.; Liddle, Stephen T

    2014-01-01

    The coordination, organometallic, and materials chemistry of uranium nitride has long been an important facet of actinide chemistry. Following matrix isolation experiments and computational characterisation, molecular, solution-based uranium chemistry has developed significantly in the last decade or so culminating most recently in the isolation of the first examples of long-sought terminal uranium nitride linkages. Herein, the field is reviewed with an emphasis on well-defined molecular spec...

  6. Innovative boron nitride-doped propellants

    OpenAIRE

    Thelma Manning; Richard Field; Kenneth Klingaman; Michael Fair; John Bolognini; Robin Crownover; Carlton P. Adam; Viral Panchal; Eugene Rozumov; Henry Grau; Paul Matter; Michael Beachy; Christopher Holt; Samuel Sopok

    2016-01-01

    The U.S. military has a need for more powerful propellants with balanced/stoichiometric amounts of fuel and oxidants. However, balanced and more powerful propellants lead to accelerated gun barrel erosion and markedly shortened useful barrel life. Boron nitride (BN) is an interesting potential additive for propellants that could reduce gun wear effects in advanced propellants (US patent pending 2015-026P). Hexagonal boron nitride is a good lubricant that can provide wear resistance and lower ...

  7. The Nitrogen-Nitride Anode.

    Energy Technology Data Exchange (ETDEWEB)

    Delnick, Frank M.

    2014-10-01

    Nitrogen gas N 2 can be reduced to nitride N -3 in molten LiCl-KCl eutectic salt electrolyte. However, the direct oxidation of N -3 back to N 2 is kinetically slow and only occurs at high overvoltage. The overvoltage for N -3 oxidation can be eliminated by coordinating the N -3 with BN to form the dinitridoborate (BN 2 -3 ) anion which forms a 1-D conjugated linear inorganic polymer with -Li-N-B-N- repeating units. This polymer precipitates out of solution as Li 3 BN 2 which becomes a metallic conductor upon delithiation. Li 3 BN 2 is oxidized to Li + + N 2 + BN at about the N 2 /N -3 redox potential with very little overvoltage. In this report we evaluate the N 2 /N -3 redox couple as a battery anode for energy storage.

  8. Direct access to macroporous chromium nitride and chromium titanium nitride with inverse opal structure.

    Science.gov (United States)

    Zhao, Weitian; DiSalvo, Francis J

    2015-03-21

    We report a facile synthesis of single-phase, nanocrystalline macroporous chromium nitride and chromium titanium nitride with an inverse opal morphology. The material is characterized using XRD, SEM, HR-TEM/STEM, TGA and XPS. Interconversion of macroporous CrN to Cr2O3 and back to CrN while retaining the inverse opal morphology is also demonstrated.

  9. Synthesis of Vanadium Nitride by a One Step Method

    Institute of Scientific and Technical Information of China (English)

    Sansan YU; Nianxin FU; Feng GAO; Zhitong SUI

    2007-01-01

    Vanadium nitrides were prepared via one step method of carbothermal reduction and nitridation of vanadium trioxide. Thermalgravimetric analysis (TGA) and X-ray diffraction were used to determine the reaction paths of vanadium carbide, namely the following sequential reaction: V2O3→V8C7 in higher temperature stage, the rule of vanadium nitride synthesized was established, and defined conditions of temperature for the production of the carbides and nitrides were determined. Vanadium oxycarbide may consist in the front process of carbothermal reduction of vanadium trioxide. In one step method for vanadium nitride by carbothermal reduction and nitridation of vanadium trioxide, the nitridation process is simultaneous with the carbothermal reduction. A one-step mechanism of the carbothermal reduction with simultaneous nitridation leaded to a lower terminal temperature in nitridation process for vanadium nitride produced, compared with that of carbothermal reduction process without nitridation. The grain size and shape of vanadium nitride were uniform, and had the shape of a cube. The one step method combined vacuum carborization and nitridation (namely two step method) into one process. It simplified the technological process and decreased the costs.

  10. Growth of epitaxial iron nitride ultrathin film on zinc-blende gallium nitride

    International Nuclear Information System (INIS)

    The authors report the growth of iron nitride on zinc-blende gallium nitride using molecular beam epitaxy. First, zinc-blende GaN is grown on a magnesium oxide substrate having (001) orientation; second, an ultrathin layer of FeN is grown on top of the GaN layer. In situ reflection high-energy electron diffraction is used to monitor the surface during growth, and a well-defined epitaxial relationship is observed. Cross-sectional transmission electron microscopy is used to reveal the epitaxial continuity at the gallium nitride-iron nitride interface. Surface morphology of the iron nitride, similar to yet different from that of the GaN substrate, can be described as plateau valley. The FeN chemical stoichiometry is probed using both bulk and surface sensitive methods, and the magnetic properties of the sample are revealed.

  11. Nitriding and Nitrocarburizing; Current Status and Future Challenges

    DEFF Research Database (Denmark)

    Somers, Marcel A. J.

    This contribution addresses the current understanding of gaseous nitriding and nitrocarburizing. Aspects of thermodynamics, kinetics and microstructure development in iron and heat treatable steel will be explained. In these materials the nitrided/ nitrocarburized case can be subdivided...

  12. Method of manufacture of atomically thin boron nitride

    Science.gov (United States)

    Zettl, Alexander K

    2013-08-06

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

  13. Colloidal Plasmonic Titanium Nitride Nanoparticles: Properties and Applications

    DEFF Research Database (Denmark)

    Guler, Urcan; Suslov, Sergey; Kildishev, Alexander V.;

    2015-01-01

    Optical properties of colloidal plasmonic titanium nitride nanoparticles are examined with an eye on their photothermal and photocatalytic applications via transmission electron microscopy and optical transmittance measurements. Single crystal titanium nitride cubic nanoparticles with an average ...

  14. Advancing liquid metal reactor technology with nitride fuels

    International Nuclear Information System (INIS)

    A review of the use of nitride fuels in liquid metal fast reactors is presented. Past studies indicate that both uranium nitride and uranium/plutonium nitride possess characteristics that may offer enhanced performance, particularly in the area of passive safety. To further quantify these effects, the analysis of a mixed-nitride fuel system utilizing the geometry and power level of the US Advanced Liquid Metal Reactor as a reference is described. 18 refs., 2 figs., 2 tabs

  15. Diffusion kinetics of nitrogen in tantalum during plasma-nitriding

    Institute of Scientific and Technical Information of China (English)

    张德元; 林勤; 曾卫军; 李放; 许兰萍; 付青峰

    2001-01-01

    The activation energies of nitrogen in tantalum on plasma nitriding conditions were calculated according to the experimental data of hardness of plasma-nitriding of tantalum vs time and temperature. The activation energy calculated is 148.873±0.390  kJ/mol. The depth increasing of nitriding layer with time follows square root relation. The nitriding process of tantalum is controlled by diffusion of nitrogen atoms in tantalum solid solution.

  16. Studies on Dielectric Properties of Silicon Nitride at High Temperature

    Institute of Scientific and Technical Information of China (English)

    Ting Zhang; Shu-Ren Zhang; Meng-Qiang Wu; Wei-Jun Sang; Zheng-Ping Gao; Zhong-Ping Li

    2007-01-01

    In this paper, the dielectric properties of silicon nitride are studied using the dielectric polarization theories. According to the developed dielectric models, the temperature dependence of dielectric constant and loss of silicon nitride is mainly analyzed. In addition, the impact of Li+, K+, Ca2+, Al3+ and Mg2+ doping on the dielectric properties of silicon nitride are also estimated.

  17. Ion nitriding in 316=L stainless steel

    International Nuclear Information System (INIS)

    Ion nitriding is a glow discharge process that is used to induce surface modification in metals. It has been applied to 316-L austenitic stainless steel looking for similar benefits already obtained in other steels. An austenitic stainless steel was selected because is not hardenable by heat treatment and is not easy to nitride by gas nitriding. The samples were plastically deformed to 10, 20, 40, 50 AND 70% of their original thickness in order to obtain bulk hardening and to observe nitrogen penetration dependence on it. The results were: an increase of one to two rockwell hardness number (except in 70% deformed sample because of its thickness); an increase of even several hundreds per cent in microhardness knoop number in nitrided surface. The later surely modifies waste resistance which would be worth to quantify in further studies. Microhardness measured in an internal transversal face to nitrided surface had a gradual diminish in its value with depth. Auger microanalysis showed a higher relative concentration rate CN/CFe near the surface giving evidence of nitrogen presence till 250 microns deep. The color metallography etchant used, produced faster corrosion in nitrited regions. Therefore, corrosion studies have to be done before using ion nitrited 316-L under these chemicals. (Author)

  18. Innovative boron nitride-doped propellants

    Directory of Open Access Journals (Sweden)

    Thelma Manning

    2016-04-01

    Full Text Available The U.S. military has a need for more powerful propellants with balanced/stoichiometric amounts of fuel and oxidants. However, balanced and more powerful propellants lead to accelerated gun barrel erosion and markedly shortened useful barrel life. Boron nitride (BN is an interesting potential additive for propellants that could reduce gun wear effects in advanced propellants (US patent pending 2015-026P. Hexagonal boron nitride is a good lubricant that can provide wear resistance and lower flame temperatures for gun barrels. Further, boron can dope steel, which drastically improves its strength and wear resistance, and can block the formation of softer carbides. A scalable synthesis method for producing boron nitride nano-particles that can be readily dispersed into propellants has been developed. Even dispersion of the nano-particles in a double-base propellant has been demonstrated using a solvent-based processing approach. Stability of a composite propellant with the BN additive was verified. In this paper, results from propellant testing of boron nitride nano-composite propellants are presented, including closed bomb and wear and erosion testing. Detailed characterization of the erosion tester substrates before and after firing was obtained by electron microscopy, inductively coupled plasma and x-ray photoelectron spectroscopy. This promising boron nitride additive shows the ability to improve gun wear and erosion resistance without any destabilizing effects to the propellant. Potential applications could include less erosive propellants in propellant ammunition for large, medium and small diameter fire arms.

  19. Innovative boron nitride-doped propellants

    Institute of Scientific and Technical Information of China (English)

    Thelma MANNING; Henry GRAU; Paul MATTER; Michael BEACHY; Christopher HOLT; Samuel SOPOK; Richard FIELD; Kenneth KLINGAMAN; Michael FAIR; John BOLOGNINI; Robin CROWNOVER; Carlton P. ADAM; Viral PANCHAL; Eugene ROZUMOV

    2016-01-01

    The U.S. military has a need for more powerful propellants with balanced/stoichiometric amounts of fuel and oxidants. However, balanced and more powerful propellants lead to accelerated gun barrel erosion and markedly shortened useful barrel life. Boron nitride (BN) is an interesting potential additive for propellants that could reduce gun wear effects in advanced propellants (US patent pending 2015-026P). Hexagonal boron nitride is a good lubricant that can provide wear resistance and lower flame temperatures for gun barrels. Further, boron can dope steel, which drastically improves its strength and wear resistance, and can block the formation of softer carbides. A scalable synthesis method for producing boron nitride nano-particles that can be readily dispersed into propellants has been developed. Even dispersion of the nano-particles in a double-base propellant has been demonstrated using a solvent-based processing approach. Stability of a composite propellant with the BN additive was verified. In this paper, results from propellant testing of boron nitride nano-composite propellants are presented, including closed bomb and wear and erosion testing. Detailed characterization of the erosion tester substrates before and after firing was obtained by electron microscopy, inductively coupled plasma and x-ray photoelectron spectroscopy. This promising boron nitride additive shows the ability to improve gun wear and erosion resistance without any destabilizing effects to the propellant. Potential applications could include less erosive propellants in propellant ammunition for large, medium and small diameter fire arms.

  20. Fusion bonding of silicon nitride surfaces

    DEFF Research Database (Denmark)

    Reck, Kasper; Østergaard, Christian; Thomsen, Erik Vilain;

    2011-01-01

    While silicon nitride surfaces are widely used in many micro electrical mechanical system devices, e.g. for chemical passivation, electrical isolation or environmental protection, studies on fusion bonding of two silicon nitride surfaces (Si3N4–Si3N4 bonding) are very few and highly application...... results on bonding of thin and thick Si3N4 layers. The new results include high temperature bonding without any pretreatment, along with improved bonding ability achieved by thermal oxidation and chemical pretreatment. The bonded wafers include both unprocessed and processed wafers with a total silicon...... nitride thickness of up to 440 nm. Measurements of bonding strength, void characterization, oxidation rate and surface roughness are also presented. Bonding strengths for stoichiometric low pressure chemical vapor deposition Si3N4–Si3N4 direct fusion bonding in excess of 2 J cm−2 are found...

  1. Nitride Fuel Development at the INL

    Energy Technology Data Exchange (ETDEWEB)

    W.E. Windes

    2007-06-01

    A new method for fabricating nitride-based fuels for nuclear applications is under development at the Idaho National Laboratory (INL). A primary objective of this research is the development of a process that could be operated as an automated or semi-automated technique reducing costs, worker doses, and eventually improving the final product form. To achieve these goals the fabrication process utilizes a new cryo-forming technique to produce microspheres formed from sub-micron oxide powder to improve material handling issues, yield rapid kinetics for conversion to nitrides, and reduced material impurity levels within the nitride compounds. The microspheres are converted to a nitride form within a high temperature particle fluidizing bed using a carbothermic process that utilizes a hydrocarbon – hydrogen - nitrogen gas mixture. A new monitor and control system using differential pressure changes in the fluidizing gas allows for real-time monitoring and control of the spouted bed reactor during conversion. This monitor and control system can provide real-time data that is used to control the gas flow rates, temperatures, and gas composition to optimize the fluidization of the particle bed. The small size (0.5 µm) of the oxide powders in the microspheres dramatically increases the kinetics of the conversion process yielding reduced process times and temperatures. Initial studies using surrogate ZrO2 powder have yielded conversion efficiencies of 90 -95 % nitride formation with only small levels of oxide and carbide contaminants present. Further studies are being conducted to determine optimal gas mixture ratios, process time, and temperature range for providing complete conversion to a nitride form.

  2. Nitride Fuel Development at the INL

    International Nuclear Information System (INIS)

    A new method for fabricating nitride-based fuels for nuclear applications is under development at the Idaho National Laboratory (INL). A primary objective of this research is the development of a process that could be operated as an automated or semi-automated technique reducing costs, worker doses, and eventually improving the final product form. To achieve these goals the fabrication process utilizes a new cryo-forming technique to produce microspheres formed from sub-micron oxide powder to improve material handling issues, yield rapid kinetics for conversion to nitrides, and reduced material impurity levels within the nitride compounds. The microspheres are converted to a nitride form within a high temperature particle fluidizing bed using a carbothermic process that utilizes a hydrocarbon-hydrogen-nitrogen gas mixture. A new monitor and control system using differential pressure changes in the fluidizing gas allows for real-time monitoring and control of the spouted bed reactor during conversion. This monitor and control system can provide real-time data that is used to control the gas flow rates, temperatures, and gas composition to optimize the fluidization of the particle bed. The small size (0.5 (micro)m) of the oxide powders in the microspheres dramatically increases the kinetics of the conversion process yielding reduced process times and temperatures. Initial studies using surrogate ZrO2 powder have yielded conversion efficiencies of 90-95% nitride formation with only small levels of oxide and carbide contaminants present. Further studies are being conducted to determine optimal gas mixture ratios, process time, and temperature range for providing complete conversion to a nitride form

  3. Precipitate-Accommodated Plasma Nitriding for Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    Patama Visittipitukul; Tatsuhiko Aizawa; Hideyuki Kuwahara

    2004-01-01

    Reliable surface treatment has been explored to improve the strength and wear resistance of aluminum alloy parts in automotives. Long duration time as well as long pre-sputtering time are required for plasma nitriding of aluminum or its alloys only with the thickness of a few micrometers. New plasma inner nitriding is proposed to realize the fast-rate nitriding of aluminum alloys. Al-6Cu alloy is employed as a targeting material in order to demonstrate the effectiveness of this plasma nitriding. Mechanism of fast-rate nitriding process is discussed with consideration of the role of Al2Cu precipitates.

  4. Local heating with titanium nitride nanoparticles

    DEFF Research Database (Denmark)

    Guler, Urcan; Ndukaife, Justus C.; Naik, Gururaj V.;

    2013-01-01

    We investigate the feasibility of titanium nitride (TiN) nanoparticles as local heat sources in the near infrared region, focusing on biological window. Experiments and simulations provide promising results for TiN, which is known to be bio-compatible.......We investigate the feasibility of titanium nitride (TiN) nanoparticles as local heat sources in the near infrared region, focusing on biological window. Experiments and simulations provide promising results for TiN, which is known to be bio-compatible....

  5. Alkaline Capacitors Based on Nitride Nanoparticles

    Science.gov (United States)

    Aldissi, Matt

    2003-01-01

    High-energy-density alkaline electrochemical capacitors based on electrodes made of transition-metal nitride nanoparticles are undergoing development. Transition- metal nitrides (in particular, Fe3N and TiN) offer a desirable combination of high electrical conductivity and electrochemical stability in aqueous alkaline electrolytes like KOH. The high energy densities of these capacitors are attributable mainly to their high capacitance densities, which, in turn, are attributable mainly to the large specific surface areas of the electrode nanoparticles. Capacitors of this type could be useful as energy-storage components in such diverse equipment as digital communication systems, implanted medical devices, computers, portable consumer electronic devices, and electric vehicles.

  6. Boron Nitride Nanotubes for Spintronics

    Directory of Open Access Journals (Sweden)

    Kamal B. Dhungana

    2014-09-01

    Full Text Available With the end of Moore’s law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed the boundary of conventional, all metallic, solid state multi-layered structures to reach a new frontier, where nanostructures provide a pathway for the spin-carriers. Different materials such as organic and inorganic nanostructures are explored for possible applications in spintronics. In this short review, we focus on the boron nitride nanotube (BNNT, which has recently been explored for possible applications in spintronics. Unlike many organic materials, BNNTs offer higher thermal stability and higher resistance to oxidation. It has been reported that the metal-free fluorinated BNNT exhibits long range ferromagnetic spin ordering, which is stable at a temperature much higher than room temperature. Due to their large band gap, BNNTs are also explored as a tunnel magneto resistance device. In addition, the F-BNNT has recently been predicted as an ideal spin-filter. The purpose of this review is to highlight these recent progresses so that a concerted effort by both experimentalists and theorists can be carried out in the future to realize the true potential of BNNT-based spintronics.

  7. Boron nitride nanotubes for spintronics.

    Science.gov (United States)

    Dhungana, Kamal B; Pati, Ranjit

    2014-01-01

    With the end of Moore's law in sight, researchers are in search of an alternative approach to manipulate information. Spintronics or spin-based electronics, which uses the spin state of electrons to store, process and communicate information, offers exciting opportunities to sustain the current growth in the information industry. For example, the discovery of the giant magneto resistance (GMR) effect, which provides the foundation behind modern high density data storage devices, is an important success story of spintronics; GMR-based sensors have wide applications, ranging from automotive industry to biology. In recent years, with the tremendous progress in nanotechnology, spintronics has crossed the boundary of conventional, all metallic, solid state multi-layered structures to reach a new frontier, where nanostructures provide a pathway for the spin-carriers. Different materials such as organic and inorganic nanostructures are explored for possible applications in spintronics. In this short review, we focus on the boron nitride nanotube (BNNT), which has recently been explored for possible applications in spintronics. Unlike many organic materials, BNNTs offer higher thermal stability and higher resistance to oxidation. It has been reported that the metal-free fluorinated BNNT exhibits long range ferromagnetic spin ordering, which is stable at a temperature much higher than room temperature. Due to their large band gap, BNNTs are also explored as a tunnel magneto resistance device. In addition, the F-BNNT has recently been predicted as an ideal spin-filter. The purpose of this review is to highlight these recent progresses so that a concerted effort by both experimentalists and theorists can be carried out in the future to realize the true potential of BNNT-based spintronics. PMID:25248070

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

    Science.gov (United States)

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

    2014-04-01

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

  9. Study of the nitrides formation in the ionic nitriding process of zircaloy-2 zirconium alloy

    International Nuclear Information System (INIS)

    Zircaloy and Zr-Sn alloys are used in nuclear techniques because they show a very low effective absorption section for neutrons and a high corrosion resistance. This paper shows that by ionic nitriding of Zircaloy type alloys, a structure is obtained that enhances the wear resistance. From the study of the N2/H2 ratio on the nitride quantity formed by ion nitriding of Zircaloy-2 alloy, it can be concluded that the gaseous mixtures with high nitrogen and hydrogen content used in discharge are not favourable in the nitride forming process. The optimum ratio is 1/1. The ZrN superficial layer hardness was checked according to the exposure time and to the layer thickness. (J.S.). 6 refs., 4 figs., 2 tabs

  10. Optimization of processing temperature in the nitridation process for the synthesis of iron nitride nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rohith Vinod, K.; Sakar, M.; Balakumar, S., E-mail: balasuga@yahoo.com [National Centre for Nanoscience and Nanotechnology, University of Madras, Chennai-600025 (India); Saravanan, P. [Defence Metallurgical Research Laboratory, Hyderabad-500058 (India)

    2015-06-24

    We have demonstrated an effective strategy on the nitridation process to synthesize ε-Fe{sub 3}N nanoparticles (NPs) from the zero valent iron NPs as a starting material. The transformation of iron into iron nitride phase was systematically studied by performing the nitridation process at different processing temperatures. The phase, crystal structure was analyzed by XRD. Morphology and size of the ZVINPs and ε-Fe{sub 3}N NPs were analyzed by field emission scanning electron microscope. Further, their room temperature magnetic properties were studied by using vibrating sample magnetometer and it revealed that the magnetic property of ε-Fe{sub 3}N is associated with ratio of Fe-N in the iron nitride system.

  11. Residual Stress Induced by Nitriding and Nitrocarburizing

    DEFF Research Database (Denmark)

    Somers, Marcel A.J.

    2005-01-01

    The present chapter is devoted to the various mechanisms involved in the buildup and relief of residual stress in nitrided and nitrocarburized cases. The work presented is an overview of model studies on iron and iron-based alloys. Subdivision is made between the compound (or white) layer...

  12. Styrene Aziridination by Iron(IV) Nitrides.

    Science.gov (United States)

    Muñoz, Salvador B; Lee, Wei-Tsung; Dickie, Diane A; Scepaniak, Jeremiah J; Subedi, Deepak; Pink, Maren; Johnson, Michael D; Smith, Jeremy M

    2015-09-01

    Thermolysis of the iron(IV) nitride complex [PhB(tBuIm)3Fe≡N] with styrene leads to formation of the high-spin iron(II) aziridino complex [PhB(tBuIm)3Fe-N(CH2CHPh)]. Similar aziridination occurs with both electron-rich and electron-poor styrenes, while bulky styrenes hinder the reaction. The aziridino complex [PhB(tBuIm)3Fe-N(CH2CHPh)] acts as a nitride synthon, reacting with electron-poor styrenes to generate their corresponding aziridino complexes, that is, aziridine cross-metathesis. Reaction of [PhB(tBuIm)3Fe-N(CH2CHPh)] with Me3SiCl releases the N-functionalized aziridine Me3SiN(CH2CHPh) while simultaneously generating [PhB(tBuIm)3FeCl]. This closes a synthetic cycle for styrene azirdination by a nitride complex. While the less hindered iron(IV) nitride complex [PhB(MesIm)3Fe≡N] reacts with styrenes below room temperature, only bulky styrenes lead to tractable aziridino products. PMID:26179563

  13. Local residual stress measurements on nitride layers

    NARCIS (Netherlands)

    Mansilla, C.; Ocelik, V.; De Hosson, J. Th. M.

    2015-01-01

    In this work, local stresses in different nitrided maraging steel samples of high practical interest for industrial applications were studied through the so-called micro-slit milling method using a focused ion beam. The nitrogen concentration profiles were acquired by glow discharge optical emission

  14. Ammonothermal Growth of Gallium Nitride

    Science.gov (United States)

    Pimputkar, Siddha

    Bulk, single crystal Gallium Nitride (GaN) crystals are essential for enabling high performance electronic and optoelectronic devices by providing arbitrarily oriented, high quality, large, single crystal GaN substrates. Methods of producing single crystals of sufficient size and quality at a rate that would enable successful commercialization has been a major focus for research groups and companies worldwide. Recent advances have demonstrated remarkable improvements, though high cost and lack of high volume production remain key challenges. Major investments in bulk GaN growth were made at UCSB with particular focus on the ammonothermal method. The existing lab was upgraded and a new facility was designed and built with improved experimental setups for ammonothermal growth of GaN. The facilities can simultaneously operate up to 15 reactors of differing designs and capabilities with the ability to grow crystals up to 2 inches in diameter. A novel in-situ technique was devised to investigate the growth chemistry which occurs at typical operating conditions of 3,000 atm and 600 °C. Improvements in ammonothermal GaN include improved growth rates for c-plane by a factor of four to 344 μm/day with an overall record growth rate of 544 μm/day achieved for the (112¯2) plane. Crystal qualities comparable to that of the seed crystal were achieved. Impurity concentrations for transition metals were consistently reduced by a factor of 100 to concentrations below 1017 atoms/cm3. Optical transparency was improved by significantly reducing the yellow coloration typically seen for ammonothermal GaN. Single crystal GaN was successfully grown on large seeds and a 1 inch x ½ inch x ½ inch GaN crystal was demonstrated. To better understand the growth chemistry, models were created for the decomposition of ammonia under growth conditions, with initial experiments performed using the designed in-situ setup to verify the model's accuracy. To investigate the surface morphology and

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

    DEFF Research Database (Denmark)

    2000-01-01

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

  16. Metal surface nitriding by laser induced plasma

    Science.gov (United States)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  17. Nitriding of Co–Cr–Mo alloy in nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Ning, E-mail: ningtang@imr.tohoku.ac.jp; Li, Yunping, E-mail: lyping@imr.tohoku.ac.jp; Koizumi, Yuichiro; Chiba, Akihiko, E-mail: a.chiba@imr.tohoku.ac.jp

    2014-06-01

    Using the results of a thermodynamic analysis, a Co–Cr–Mo alloy was successfully nitrided in nitrogen at temperatures of 1073–1473 K. The near-surface microstructure of the treated Co–Cr–Mo alloy was characterized using X-ray diffraction, field-emission scanning electron microscopy, electron probe micro-analyzer, and transmission electron microscopy equipped with energy-dispersive X-ray spectroscopy. The results indicated that the highest nitriding efficiency was achieved at the treatment temperature of 1273 K, with the size and coverage of the nitride particles on sample's surface increasing with an increase in the treatment duration. After nitriding at 1273 K for 2 h, numerous nitride particles, consisting of an outer Cr{sub 2}N layer and an inner π phase layer, were formed on top of the nitrogen-containing γ phase, and some π phase also precipitated in the alloy matrix at the sub-surface level. - Highlights: • A Co–Cr–Mo alloy was successfully nitrided in nitrogen at 1073–1473 K. • The highest nitriding efficiency of the Co–Cr–Mo alloy was achieved at 1273 K. • Numerous nitride particles formed on sample's surface during nitriding at 1273 K. • The nitride particles consist of an outer Cr{sub 2}N layer and an inner π phase layer.

  18. Nitriding behavior of Ni and Ni-based binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fonovic, Matej

    2015-01-15

    Gaseous nitriding is a prominent thermochemical surface treatment process which can improve various properties of metallic materials such as mechanical, tribological and/or corrosion properties. This process is predominantly performed by applying NH{sub 3}+H{sub 2} containing gas atmospheres serving as the nitrogen donating medium at temperatures between 673 K and 873 K (400 C and 600 C). NH{sub 3} decomposes at the surface of the metallic specimen and nitrogen diffuses into the surface adjacent region of the specimen whereas hydrogen remains in the gas atmosphere. One of the most important parameters characterizing a gaseous nitriding process is the so-called nitriding potential (r{sub N}) which determines the chemical potential of nitrogen provided by the gas phase. The nitriding potential is defined as r{sub N} = p{sub NH{sub 3}}/p{sub H{sub 2}{sup 3/2}} where p{sub NH{sub 3}} and p{sub H{sub 2}} are the partial pressures of the NH{sub 3} and H{sub 2} in the nitriding atmosphere. In contrast with nitriding of α-Fe where the nitriding potential is usually in the range between 0.01 and 1 atm{sup -1/2}, nitriding of Ni and Ni-based alloys requires employing nitriding potentials higher than 100 atm{sup -1/2} and even up to ∞ (nitriding in pure NH{sub 3} atmosphere). This behavior is compatible with decreased thermodynamic stability of the 3d-metal nitrides with increasing atomic number. Depending on the nitriding conditions (temperature, nitriding potential and treatment time), different phases are formed at the surface of the Ni-based alloys. By applying very high nitriding potential, formation of hexagonal Ni{sub 3}N at the surface of the specimen (known as external nitriding) leads to the development of a compound layer, which may improve tribological properties. Underneath the Ni{sub 3}N compound layer, two possibilities exist: (i) alloying element precipitation within the nitrided zone (known as internal nitriding) and/or (ii) development of metastable and

  19. Examination of Plasma Nitriding Microstructure with Addition of Rare Earths

    Institute of Scientific and Technical Information of China (English)

    张津

    2004-01-01

    Medium-carbon alloy steel was plasma nitrided with rare earths La,Ce and Nd into the nitriding chamber respectively.The nitriding layer microstructures with and without rare earths were compared using optical microscope,normal SEM and high resolution SEM,as well as TEM.It was found that the extent of the influence on plasma nitriding varies with different contents of rare earth.The effect of plasma nitriding is benefit from adding of Ce or Nd.The formation of hard and brittle phase Fe2-3N can be prevented and the butterfly-like structure can be improved by adding Ce or Nd.However,pure La may prevent the diffusion of nitrogen and the formation of iron nitride,and reduce the depth of diffusion layer.

  20. Liquid flow cells having graphene on nitride for microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Adiga, Vivekananda P.; Dunn, Gabriel; Zettl, Alexander K.; Alivisatos, A. Paul

    2016-09-20

    This disclosure provides systems, methods, and apparatus related to liquid flow cells for microscopy. In one aspect, a device includes a substrate having a first and a second oxide layer disposed on surfaces of the substrate. A first and a second nitride layer are disposed on the first and second oxide layers, respectively. A cavity is defined in the first oxide layer, the first nitride layer, and the substrate, with the cavity including a third nitride layer disposed on walls of the substrate and the second oxide layer that define the cavity. A channel is defined in the second oxide layer. An inlet port and an outlet port are defined in the second nitride layer and in fluid communication with the channel. A plurality of viewports is defined in the second nitride layer. A first graphene sheet is disposed on the second nitride layer covering the plurality of viewports.

  1. The Study of Plasma Nitriding of AISI304 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    WANG Liang; JI Shi-jun; GAO Yu-zhou; SUN Jun-cai

    2004-01-01

    This paper presents results on the plasma nitriding of AISI 304 stainless steel at different temperatures in NH 3 gas. The working pressure was 100~200 Pa and the discharge voltage was 700~800V. The phase of nitrided layer formed on the surface was confirmed by X-ray diffraction. The hardness of the samples was measured by using a Vickers microhardness tester with the load of 50g. After nitriding at about 400 ℃ for two hours a nitrided layer consisting of single γN phase with thickness of 5μm was obtained. Microhardness measurements showed significant increase in the hardness from 240 HV (for untreated samples) up to 950 HV (for nitrided samples at temperature of 420℃). The phase composition, the thickness, the microstructure and the surface topography of the nitrided layer as well as its properties depend essentially on the process parameters.

  2. An assessment of the thermodynamic properties of uranium nitride, plutonium nitride and uranium-plutonium mixed nitride

    International Nuclear Information System (INIS)

    Thermodynamic properties such as vapour pressures, heat capacities and enthalpies of formation for UN(s), PuN(s) and (U, Pu)N(s) are critically evaluated. The equations of the vapour pressures and the heat capacities for the three nitrides are assessed. Thermal functions, and thermodynamic functions for the formation of UN(s), PuN(s) and (U, Pu)N(s), are calculated

  3. Intragranular Chromium Nitride Precipitates in Duplex and Superduplex Stainless Steel

    OpenAIRE

    Iversen, Torunn Hjulstad

    2012-01-01

    Intragranular chromium nitrides is a phenomenon with detrimental effects on material properties in superduplex stainless steels which have not received much attention. Precipitation of nitrides occurs when the ferritic phase becomes supersaturated with nitrogen and there is insufficient time during cooling for diffusion of nitrogen into austenite. Heat treatment was carried out at between 1060◦C and 1160◦C to study the materials susceptibility to nitride precipitation with...

  4. Synthesis of Uranium nitride powders using metal uranium powders

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jae Ho; Kim, Dong Joo; Oh, Jang Soo; Rhee, Young Woo; Kim, Jong Hun; Kim, Keon Sik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-10-15

    Uranium nitride (UN) is a potential fuel material for advanced nuclear reactors because of their high fuel density, high thermal conductivity, high melting temperature, and considerable breeding capability in LWRs. Uranium nitride powders can be fabricated by a carbothermic reduction of the oxide powders, or the nitriding of metal uranium. The carbothermic reduction has an advantage in the production of fine powders. However it has many drawbacks such as an inevitable engagement of impurities, process burden, and difficulties in reusing of expensive N{sup 15} gas. Manufacturing concerns issued in the carbothermic reduction process can be solved by changing the starting materials from oxide powder to metals. However, in nitriding process of metal, it is difficult to obtain fine nitride powders because metal uranium is usually fabricated in the form of bulk ingots. In this study, a simple reaction method was tested to fabricate uranium nitride powders directly from uranium metal powders. We fabricated uranium metal spherical powder and flake using a centrifugal atomization method. The nitride powders were obtained by thermal treating those metal particles under nitrogen containing gas. We investigated the phase and morphology evolutions of powders during the nitriding process. A phase analysis of nitride powders was also a part of the present work.

  5. Low temperature gaseous nitriding and carburising of stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Somers, Marcel A.J.

    2005-01-01

    The response of various austenitic and duplex stainless steel grades to low temperature gaseous nitriding and carburising was investigated. Gaseous nitriding was performed in ammonia/hydrogen mixtures at temperatures ,723 K; gaseous carburising was carried out in carbon monoxide/hydrogen mixtures...... for temperatures (783 K. The case developed by thermochemical treatment was examined using reflected light microscopy, X-ray diffraction analysis and microhardness testing. Both nitriding and carburising led to the development of expanded austenite in the surface adjacent zone, irrespective of the phase...... constitution of the substrate. A two step process, consisting of carburising followed by nitriding, provides great flexibility with regard to adjusting the hardness–depth profile....

  6. Quantum chemistry and atomistic simulations of solid nitrides

    OpenAIRE

    Eck, Bernhard

    2000-01-01

    The present thesis covers, at first, the binary nitrides of the the 3d transition metals. Based on their electronic band structures and bonding analyses for the sodium chloride as well as the zinc blend structure type it is then determined why the early nitrides crystallize in the NaCl structure while Fe- and Co-nitride adopt the ZnS structure. Thereafter all stoichiometrically well-defined iron nitrides are theoretically investigated, in particular with respect to the influence of the nitrog...

  7. Review of actinide nitride properties with focus on safety aspects

    Energy Technology Data Exchange (ETDEWEB)

    Albiol, Thierry [CEA Cadarache, St Paul Lez Durance Cedex (France); Arai, Yasuo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-12-01

    This report provides a review of the potential advantages of using actinide nitrides as fuels and/or targets for nuclear waste transmutation. Then a summary of available properties of actinide nitrides is given. Results from irradiation experiments are reviewed and safety relevant aspects of nitride fuels are discussed, including design basis accidents (transients) and severe (core disruptive) accidents. Anyway, as rather few safety studies are currently available and as many basic physical data are still missing for some actinide nitrides, complementary studies are proposed. (author)

  8. Investigation of surface properties of high temperature nitrided titanium alloys

    OpenAIRE

    Koyuncu, E.; F. Kahraman; Ö. Karadeniz

    2009-01-01

    Purpose: The purpose of paper is to investigate surface properties of high temperature nitrided titanium alloys.Design/methodology/approach: In this study, surface modification of Ti6Al4V titanium alloy was made at various temperatures by plasma nitriding process. Plasma nitriding treatment was performed in 80% N2-20% H2 gas mixture, for treatment times of 2-15 h at the temperatures of 700-1000°C. Surface properties of plasma nitrided Ti6Al4V alloy were examined by metallographic inspection, ...

  9. Low Temperature Gaseous Nitriding of Ni-based Superalloys

    DEFF Research Database (Denmark)

    Eliasen, K.M.; Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2009-01-01

    In the present work the nitriding response of selected Ni-based superalloys at low temperatures is addressed. The alloys investigated are Nimonic series no. 80, 90, 95 and 100 and Nichrome (Ni:Cr » 80:20). Systematic nitriding experiments at different temperatures were carried out in a thermo...... balance. The morphology of the “case” developed upon low temperature nitriding of Ni-based superalloys was characterised with reflected light microscopy, scanning electron microscopy and X-ray diffraction analysis. The alloy composition proved to have a major influence on the nitriding response...

  10. Atomic-layer deposition of silicon nitride

    CERN Document Server

    Yokoyama, S; Ooba, K

    1999-01-01

    Atomic-layer deposition (ALD) of silicon nitride has been investigated by means of plasma ALD in which a NH sub 3 plasma is used, catalytic ALD in which NH sub 3 is dissociated by thermal catalytic reaction on a W filament, and temperature-controlled ALD in which only a thermal reaction on the substrate is employed. The NH sub 3 and the silicon source gases (SiH sub 2 Cl sub 2 or SiCl sub 4) were alternately supplied. For all these methods, the film thickness per cycle was saturated at a certain value for a wide range of deposition conditions. In the catalytic ALD, the selective deposition of silicon nitride on hydrogen-terminated Si was achieved, but, it was limited to only a thin (2SiO (evaporative).

  11. Aluminum Reduction and Nitridation of Bauxite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhikuan; ZHANG Dianwei; XU Enxia; HOU Xinmei; DONG Yanling

    2007-01-01

    The application of bauxite with low Al2O3 content has been studied in this paper and β-SiAlON has been obtained from two kinds of bauxites (Al203 content 68.08 mass% and 46.30 mass% respectively) by aluminum reduction and nitridation method.The sequence of reactions has been studied using thermal analysis (TG-DTA),X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) with EDS.Compared with carbon thermal reduction and nitridation of aluminosilicates employed presently,the reaction in the system of bauxite-Al-N2 occurs at lower temperature.β-SiAlON appears as one of the main products from 1573K and exists' stably in the range of the present experimental temperature.The microstructure of β-SiAlON obtained at 1773 K is short column with 5-10μm observed by SEM.

  12. Local residual stress measurements on nitride layers

    Energy Technology Data Exchange (ETDEWEB)

    Mansilla, C.; Ocelík, V.; De Hosson, J.Th.M., E-mail: j.t.m.de.hosson@rug.nl

    2015-06-11

    In this work, local stresses in different nitrided maraging steel samples of high practical interest for industrial applications were studied through the so-called micro-slit milling method using a focused ion beam. The nitrogen concentration profiles were acquired by glow discharge optical emission spectroscopy. The residual stress state was measured on the surface and also in cross-section, i.e. examining effects of the nitrogen concentration gradient. It is shown that an enhanced lateral resolution can be achieved when a novel multiple fitting approach is employed. The results presented show an overall agreement with stress profiles obtained by X-ray diffraction. Finite Element Modeling is used to explain the apparent discrepancies. A clear correlation between the residual stress and nitriding profiles has been found and the applicability of this method is shown in particular when stress gradients are present.

  13. Sheath Characteristic in ECR Plasma Nitriding

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The sheath plasma characteristics changing with the negative bias applied to the substrate during electron cyclotron resonance plasma nitriding are studied. The sheath characteristics obtained by a Langmuir single probe and an ion energy analyzer show that when the negative bias applied to the substrate is increasing, the most probable energy of ions in the sheath and the full width of half maximum of ions energy distribution increase, the thickness of the sheath also increases, whereas the saturation current of ion decreases. It has been found from the optical emission spectrum that there are strong lines of N2 and N2+. Based on our experiment results the mechanism of plasma nitriding is discussed.

  14. Silicon Nitride Balls For Cryogenic Bearings

    Science.gov (United States)

    Butner, Myles F.; Ng, Lillian W.

    1990-01-01

    Resistance to wear greater than that of 440C steel. Experiments show lives of ball bearings immersed in liquid nitrogen or liquid oxygen increased significantly when 440C steel balls (running on 440C steel races) replaced by balls of silicon nitride. Developed for use at high temperatures, where lubrication poor or nonexistent. Best wear life of any bearing tested to date and ball material spalls without fracturing. Plans for future tests call for use of liquid oxygen as working fluid.

  15. Magnetron sputtering of thin nitride films

    OpenAIRE

    Kola, Prashanthi V

    1995-01-01

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

  16. Nitride phosphors and solid-state lighting

    CERN Document Server

    Xie, Rong-Jun; Hirosaki, Naoto

    2011-01-01

    Introduction to Solid-State LightingBasics of Solid-State LightingBasics of White Light-Emitting Diodes (LEDs)Applications of Solid-State LightingIntroduction to LuminescenceClassification of Optical ProcessesFundamentals of LuminescenceLuminescent CentersMeasurement of LuminescenceTraditional Phosphors in White LEDsRequirements for Phosphors in White LEDsClassification of PhosphorsPhotoluminescent Properties of Traditional PhosphorsNitride Phosphors i

  17. Amorphous Carbon-Boron Nitride Nanotube Hybrids

    Science.gov (United States)

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

    2016-01-01

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

  18. Formation and Structure of Boron Nitride Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Jiang ZHANG; Zongquan LI; Jin XU

    2005-01-01

    Boron nitride (BN) nanotubes were simply synthesized by heating well-mixed boric acid, urea and iron nitrate powders at 1000℃. A small amount of BN nanowires was also obtained in the resultants. The morphological and structural characters of the BN nanostructures were studied using transmission electron microscopy. Other novel BN nanostructures, such as Y-junction nanotubes and bamboo-like nanotubes, were simultaneously observed. The growth mechanism of the BN nanotubes was discussed briefly.

  19. Boron Nitride Nanosheets for Metal Protection

    OpenAIRE

    Li, Lu Hua; Xing, Tan; Chen, Ying; Jones, Rob

    2015-01-01

    Although the high impermeability of graphene makes it an excellent barrier to inhibit metal oxidation and corrosion, graphene can form a galvanic cell with the underlying metal that promotes corrosion of the metal in the long term. Boron nitride (BN) nanosheets which have a similar impermeability could be a better choice as protective barrier, because they are more thermally and chemically stable than graphene and, more importantly, do not cause galvanic corrosion due to their electrical insu...

  20. Anomalous thermal conductivity of monolayer boron nitride

    Science.gov (United States)

    Tabarraei, Alireza; Wang, Xiaonan

    2016-05-01

    In this paper, we use nonequilibrium molecular dynamics modeling to investigate the thermal properties of monolayer hexagonal boron nitride nanoribbons under uniaxial strain along their longitudinal axis. Our simulations predict that hexagonal boron nitride shows an anomalous thermal response to the applied uniaxial strain. Contrary to three dimensional materials, under uniaxial stretching, the thermal conductivity of boron nitride nanoribbons first increases rather than decreasing until it reaches its peak value and then starts decreasing. Under compressive strain, the thermal conductivity of monolayer boron nitride ribbons monolithically reduces rather than increasing. We use phonon spectrum and dispersion curves to investigate the mechanism responsible for the unexpected behavior. Our molecular dynamics modeling and density functional theory results show that application of longitudinal tensile strain leads to the reduction of the group velocities of longitudinal and transverse acoustic modes. Such a phonon softening mechanism acts to reduce the thermal conductivity of the nanoribbons. On the other hand, a significant increase in the group velocity (stiffening) of the flexural acoustic modes is observed, which counteracts the phonon softening effects of the longitudinal and transverse modes. The total thermal conductivity of the ribbons is a result of competition between these two mechanisms. At low tensile strain, the stiffening mechanism overcomes the softening mechanism which leads to an increase in the thermal conductivity. At higher tensile strain, the softening mechanism supersedes the stiffening and the thermal conductivity slightly reduces. Our simulations show that the decrease in the thermal conductivity under compressive strain is attributed to the formation of buckling defects which reduces the phonon mean free path.

  1. Silicon Nitride Antireflection Coatings for Photovoltaic Cells

    Science.gov (United States)

    Johnson, C.; Wydeven, T.; Donohoe, K.

    1984-01-01

    Chemical-vapor deposition adapted to yield graded index of refraction. Silicon nitride deposited in layers, refractive index of which decreases with distance away from cell/coating interface. Changing index of refraction allows adjustment of spectral transmittance for wavelengths which cell is most effective at converting light to electric current. Average conversion efficiency of solar cells increased from 8.84 percent to 12.63 percent.

  2. Nitride inclusions in titanium-containing high-nitrogen steel after solid-phase nitriding

    Science.gov (United States)

    Lysenkova, E. V.; Kadach, M. V.; Butskii, E. V.; Dorofievich, I. V.; Stomakhin, A. Ya.

    2015-09-01

    The principal possibility of production of sheet titanium-containing high-nitrogen steels without extreme harmful coarse nitride inclusions and their aggregates, which are characteristic of these compositions even at a relatively low (impurity) nitrogen content, is studied. To this end, the nitrogen content in the initial metal before its solidification is limited to the calculation level at which titanium nitrides are thermally unstable. Nitrogen is introduced in metal (08Cr18Ni12Ti steel) during its chemical thermal treatment in a nitrogen atmosphere at 1200°C. The nitrogen content in the finished metal is 0.4% (at 0.31% Ti). Studies in this direction are thought to be promising, since it is evident that the production of a metal of such a composition using the standard method of nitrogen introduction (in melt) is impossible. Scanning electron microscopy shows that titanium nitride particles in the finished metal are ≤0.5 μm in size.

  3. Heavy ion bombardment of silicates and nitrides

    International Nuclear Information System (INIS)

    Several silicates, including α-quartz, zirconium silicate, thorium silicate, LiAlSiO4, a silicate glass and several nitrides, α and β Si3N4, AlN, ZrN as well as Si2N2O and ThO2, have been irradiated by 1019 to 1021 Krypton (3 MeV) ions/m2. The damaged powders of original particle size less than 5 μm, have been examined by x-ray diffraction and electron microscope methods. The silicates and Si2N2O become non-crystalline by 10 x 1019 ions/m2. The particles change shape, extending and bloating under prolonged irradiations of the order of 100 x 1019 ions/m2. Silicate glass also undergoes this irradiation creep process. The nitrides and ThO2 behave quite differently and even at fluences of 200 x 1019 x ions/m-2 the powders remain crystalline, retaining relatively sharp edges to the particles without exhibiting irradiation creep. This difference in behavior can be related to the nature of the framework crystal structures, flexible for the silicates with variable bond angles, rigid for the nitrides with fixed bond angles. This may explain the behavior of radioactive minerals not found in a metamict condition. (author)

  4. Microscopic modeling of nitride intersubband absorbance

    Science.gov (United States)

    Montano, Ines; Allerman, A. A.; Wierer, J. J.; Moseley, M.; Skogen, E. J.; Tauke-Pedretti, A.; Vawter, G. A.

    III-nitride intersubband structures have recently attracted much interest because of their potential for a wide variety of applications ranging from electro-optical modulators to terahertz quantum cascade lasers. To overcome present simulation limitations we have developed a microscopic absorbance simulator for nitride intersubband devices. Our simulator calculates the band structure of nitride intersubband systems using a fully coupled 8x8 k.p Hamiltonian and determines the material response of a single period in a density-matrix-formalism by solving the Heisenberg equation including many-body and dephasing contributions. After calculating the polarization due to intersubband transitions in a single period, the resulting absorbance of a superlattice structure including radiative coupling between the different periods is determined using a non-local Green's-function formalism. As a result our simulator allows us to predict intersubband absorbance of superlattice structures with microscopically determined lineshapes and linewidths accounting for both many-body and correlation contributions. This work is funded by Sandia National Laboratories Laboratory Directed Research and Development program. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin.

  5. Development of compound layer of iron (carbo)nitrides during nitriding of steel

    DEFF Research Database (Denmark)

    Ratajski, J.; Tacikowski, J.; Somers, Marcel A.J.

    2003-01-01

    The composition and phase constitution of a compound layer developing during gaseous nitriding was investigated at 853 K for three commercial steels (AISI 120, 4340 and 1090) and Armco iron. The compound layers were characterised by light optical microscopy, X-ray diffraction and electron probe...... microanalysis. The formation of the compound layer occurs along two distinct sequences: alpha-gamma prime-epsilon and/or alpha(theta)-epsilon2-gamma prime-epsilon1. The preferred sequence depends mainly on the chemical composition of steel and on the nitriding potential....

  6. New amorphous interface for precipitate nitrides in steel

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Kadkhodazadeh, Shima; Grumsen, Flemming Bjerg;

    2014-01-01

    during electron beam exposure. The amorphous shells were observed around Ta- and Nb-based nitrides, which are considered to have a high interfacial energy with the ferrite matrix. They were not observed around V-based nitrides which have a Baker–Nutting relationship with low-misfit to the matrix....

  7. Synthesis of metal-nitrides using high pressures and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Guillaume, C; Serghiou, G [University of Edinburgh, School of Engineering and Electronics, Kings Buildings, Mayfield Road, EH9 3JL UK (United Kingdom); Morniroli, J P [Laboratoire de Metallurgie Physique et Genie des Materiaux, UMR CNRS 8517, Universite des Sciences et Technologies de Lille et Ecole Nationale Superieure de Chimie de Lille, Cite Scientifique, 59655 Villeneuve d' Ascq Cedex (France); Frost, D J [Bayerisches Geoinstitut, Universitat Bayreuth, D-95440, Bayreuth (Germany)], E-mail: george.serghiou@ed.ac.uk

    2008-07-15

    Technologically, high density nitrides are showing promise for both ceramic and electronic applications. In a laser-heated diamond cell we prepare high density metal-nitrides by reaction of the nitrogen pressure medium with an elemental substrate. Two of our objectives are to develop criteria governing whether denser than ambient nitride phases will form, and to in particular establish the parameters required for synthesis in a multianvil press using elemental starting materials. We have already synthesized transition metal nitrides in a multianvil press using elemental starting materials, including hexagonal nickel nitride and alkali rhenium nitrides. Unlike previous metals, we also report that Cu does not form a nitride after heating with NaN{sub 3} at 2000 K and 20 GPa. Notably, Cu{sub 3}N is a semiconductor exhibiting weak directional bonds, whereas the immediately adjacent lower atomic number systems are metallic interstitial nitrides. We also briefly mention our work on processing high pressure and temperature recovered reaction products with focused ion beam methods for tailored characterization using electron microscopy.

  8. EXAFS investigation of low temperature nitrided stainless steel

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas; Ståhl, Kenny;

    2008-01-01

    Low temperature nitrided stainless steel AISI 316 flakes were investigated with EXAFS and X-ray diffraction analysis. The stainless steel flakes were transformed into a mixture of nitrogen expanded austenite and nitride phases. Two treatments were carried out yielding different overall nitrogen...

  9. Composition and microhardness of CAE boron nitride films

    International Nuclear Information System (INIS)

    The paper deals with boron nitride produced by cathodic arc evaporation techniques.The films were applied on titanium and cemented carbide substrates. Their characterization was carried out using X-ray diffraction and Knoop microhardness tests. Demonstrated are the high properties of two-phase films, containing β (cubic) and γ (wurtzitic) modifications of boron nitride. (author). 7 refs., 1 fig., 3 tabs

  10. Epitaxial aluminum nitride tunnel barriers grown by nitridation with a plasma source

    NARCIS (Netherlands)

    Zijlstra, T.; Lodewijk, C.F.J.; Vercruyssen, N.; Tichelaar, F.D.; Loudkov, D.N.; Klapwijk, T.M.

    2007-01-01

    High critical current-density (10 to 420 kA/cm2) superconductor-insulator-superconductor tunnel junctions with aluminum nitride barriers have been realized using a remote nitrogen plasma from an inductively coupled plasma source operated in a pressure range of 10−3–10−1 mbar. We find a much better r

  11. Low Temperature Gaseous Nitriding of a Stainless Steel Containing Strong Nitride Formers

    DEFF Research Database (Denmark)

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

    Low temperature thermochemical surface hardening of the precipitation hardening austenitic stainless steel A286 in solution treated state was investigated. A286 contains, besides high amounts of Cr, also substantial amounts of strong nitride formers as Ti, Al and V. It is shown that simultaneous...

  12. Facile Solid-State Synthesis Route to Metal Nitride Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Yinxiao DU; Ming LEI; Hui YANG

    2008-01-01

    By a facile and efficient solid-state reaction route using an organic reagent cyanamide (CN2H2) as a precursor with another one being metal oxides, we successfully synthesized seven technologically important metal nitrides including cubic VN, CrN, NbN, hexagonal GaN, AIN, BN, and WN at moderate temperatures. The experimental results show that cyanamide (CN2H2) is a powerfully reducing and nitridizing reagent and the metal oxides are completely converted into the corresponding nitride nanoparticles at lower temperatures than that reported in the conventional methods. It is found that CN2H2 can exhibit some interesting condensation processes, and the final products, highly active carbon nitride species, play a crucial role in the reducing and nitridizing processes.

  13. Safety Assessment of Boron Nitride as Used in Cosmetics.

    Science.gov (United States)

    Fiume, Monice M; Bergfeld, Wilma F; Belsito, Donald V; Hill, Ronald A; Klaassen, Curtis D; Liebler, Daniel C; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2015-01-01

    The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of boron nitride which functions in cosmetics as a slip modifier (ie, it has a lubricating effect). Boron nitride is an inorganic compound with a crystalline form that can be hexagonal, spherical, or cubic; the hexagonal form is presumed to be used in cosmetics. The highest reported concentration of use of boron nitride is 25% in eye shadow formulations. Although boron nitride nanotubes are produced, boron nitride is not listed as a nanomaterial used in cosmetic formulations. The Panel reviewed available chemistry, animal data, and clinical data and concluded that this ingredient is safe in the present practices of use and concentration in cosmetic formulations.

  14. Gaseous Nitriding Process of Surface Nanocrystallized (SNCed) Steel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The behavior of gaseous nitriding on the surface nanocrystallized (SNCed) steel was investigated. The mild steel discs were SNCed on one side by using the method of ultrasonic shot peening. The opposite side of the discs maintained the original coarse-grained condition. The gaseous nitriding was subsequently carried out at three different temperatures:460, 500 and 560℃. The compound layer growth and diffusion behavior were then studied. It was revealed that SNC pretreatment greatly enhances both diffusion coefficient D and surface reaction rate. As a result, nitriding time could be reduced to the half. It was also found that the growth of compound layer with nitriding time conformed with parabolic relationship from the start of nitriding process in the SNCed samples.

  15. Design of nitride semiconductors for solar energy conversion

    Energy Technology Data Exchange (ETDEWEB)

    Zakutayev, Andriy

    2016-01-01

    Nitride semiconductors are a promising class of materials for solar energy conversion applications, such as photovoltaic and photoelectrochemical cells. Nitrides can have better solar absorption and electrical transport properties than the more widely studied oxides, as well as the potential for better scalability than other pnictides or chalcogenides. In addition, nitrides are also relatively unexplored compared to other chemistries, so they provide a great opportunity for new materials discovery. This paper reviews the recent advances in the design of novel semiconducting nitrides for solar energy conversion technologies. Both binary and multinary nitrides are discussed, with a range of metal chemistries (Cu3N, ZnSnN2, Sn3N4, etc.) and crystal structures (delafossite, perovskite, spinel, etc.), including a brief overview of wurtzite III-N materials and devices. The current scientific challenges and promising future directions in the field are also highlighted.

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

    Science.gov (United States)

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

    2015-08-11

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

  17. Effect of Plasma Nitriding on the Performance of WC-Co Cutting Tools

    Science.gov (United States)

    Hamzaoglu, Ebru; Yilmaz, Safak; Gulmez, Turgut

    2011-04-01

    This paper presents the effect of nitriding process parameters on the cutting performance of WC-Co tools. The cutting performance was measured by CNC machining of GG25 cast iron parts. The hardness and phase composition of nitrided layer were determined for different plasma nitriding temperatures and times. The hardness of the nitrided layer increased at all plasma nitrided conditions investigated. However, the machining performance of the cutting inserts varied in the range between a 60% increase and a 40% decrease after plasma nitriding. The maximum number of machined parts was seen when the insert was nitrided at 600 °C-4 h and at 500 °C-4 h.

  18. Ballistic thermoelectric properties in boron nitride nanoribbons

    Science.gov (United States)

    Xie, Zhong-Xiang; Tang, Li-Ming; Pan, Chang-Ning; Chen, Qiao; Chen, Ke-Qiu

    2013-10-01

    Ballistic thermoelectric properties (TPs) in boron nitride nanoribbons (BNNRs) are studied using the nonequilibrium Green's function atomistic simulation of electron and phonon transport. A comparative analysis for TPs between BNNRs and graphene nanoribbons (GNRs) is made. Results show that the TPs of BNNRs are better than those of GNRs stemming from the higher power factor and smaller thermal conductance of BNNRs. With increasing the ribbon width, the maximum value of ZT (ZTmax) of BNNRs exhibits a transformation from the monotonic decrease to nonlinear increase. We also show that the lattice defect can enhance the ZTmax of these nanoribbons strongly depending on its positions and the edge shape.

  19. Low-dimensional boron nitride nanomaterials

    Directory of Open Access Journals (Sweden)

    Amir Pakdel

    2012-06-01

    Full Text Available In this review, a concise research history of low-dimensional boron nitride (BN nanomaterials followed by recent developments in their synthesis, morphology, properties, and applications are presented. Seventeen years after the initial synthesis of BN nanotubes, research on BN nanomaterials has developed far enough to establish them as one of the most promising inorganic nanosystems. In this regard, it is envisaged that the unique properties of low-dimensional BN systems, such as superb mechanical stiffness, high thermal conductivity, wide optical bandgap, strong ultraviolet emission, thermal stability and chemical inertness will play a key role in prospective developments.

  20. Nitride Semiconductors Handbook on Materials and Devices

    CERN Document Server

    Ruterana, Pierre; Neugebauer, Jörg

    2003-01-01

    Semiconductor components based on silicon have been used in a wide range of applications for some time now. These elemental semiconductors are now well researched and technologically well developed. In the meantime the focus has switched to a new group of materials: ceramic semiconductors based on nitrides are currently the subject of research due to their optical and electronic characteristics. They open up new industrial possibilities in the field of photosensors, as light sources or as electronic components. This collection of review articles provides a systematic and in-depth overview of t

  1. Magnesium doping of boron nitride nanotubes

    Science.gov (United States)

    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.

  2. Method for exfoliation of hexagonal boron nitride

    Science.gov (United States)

    Lin, Yi (Inventor); Connell, John W. (Inventor)

    2012-01-01

    A new method is disclosed for the exfoliation of hexagonal boron nitride into mono- and few-layered nanosheets (or nanoplatelets, nanomesh, nanoribbons). The method does not necessarily require high temperature or vacuum, but uses commercially available h-BN powders (or those derived from these materials, bulk crystals) and only requires wet chemical processing. The method is facile, cost efficient, and scalable. The resultant exfoliated h-BN is dispersible in an organic solvent or water thus amenable for solution processing for unique microelectronic or composite applications.

  3. Novel nanoscroll structures from carbon nitride layers.

    Science.gov (United States)

    Perim, Eric; Galvao, Douglas S

    2014-08-01

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

  4. Boron nitride nanomaterials for thermal management applications.

    Science.gov (United States)

    Meziani, Mohammed J; Song, Wei-Li; Wang, Ping; Lu, Fushen; Hou, Zhiling; Anderson, Ankoma; Maimaiti, Halidan; Sun, Ya-Ping

    2015-05-18

    Hexagonal boron nitride nanosheets (BNNs) are analogous to their two-dimensional carbon counterparts in many materials properties, in particular, ultrahigh thermal conductivity, but also offer some unique attributes, including being electrically insulating, high thermal stability, chemical and oxidation resistance, low color, and high mechanical strength. Significant recent advances in the production of BNNs, understanding of their properties, and the development of polymeric nanocomposites with BNNs for thermally conductive yet electrically insulating materials and systems are highlighted herein. Major opportunities and challenges for further studies in this rapidly advancing field are also discussed. PMID:25652360

  5. Ab Initio Study on Hypothetical Silver Nitride

    Institute of Scientific and Technical Information of China (English)

    DELIGOZ Engin; COLAKOGLU Kemal; CIFTCI Yasemin Oztekin

    2008-01-01

    We perform the ab initio calculations based on norm-conserving pseudopotentials and density functional theory to investigate the structural, elastic, and thermodynamical properties for silver nitride (AgN) compound that is a member of the 4d transition metal group and has not been synthesized yet. The obtained results are compared with the other available theoretical data, and the agreement is, generally, quite good. We also present the pressure-dependent behaviour of some mechanical and thermodynamical properties for the same compounds.

  6. Ammonia Decomposition over Bimetallic Nitrides Supported on γ-Al2O3

    Institute of Scientific and Technical Information of China (English)

    Chun Shan LU; Xiao Nian LI; Yi Feng ZHU; Hua Zhang LIU; Chun Hui ZHOU

    2004-01-01

    A series of monometallic nitrides and bimetallic nitrides were prepared by temperature-programmed reaction with NH3. The effects of Co, Ni and Fe additives and the synergic action between Fe, Co, Ni and Mo on the ammonia decomposition activity were investigated. TPR-MS, XRD were also carried out to obtain better insight into the structure of the bimetallic nitride. The results of ammonia decomposition activity show that bimetallic nitrides are more active than monometallic nitrides or bimetallic oxides.

  7. Hard and low friction nitride coatings and methods for forming the same

    Science.gov (United States)

    Erdemir, Ali; Urgen, Mustafa; Cakir, Ali Fuat; Eryilmaz, Osman Levent; Kazmanli, Kursat; Keles, Ozgul

    2007-05-01

    An improved coating material possessing super-hard and low friction properties and a method for forming the same. The improved coating material includes the use of a noble metal or soft metal homogeneously distributed within a hard nitride material. The addition of small amounts of such metals into nitrides such as molybdenum nitride, titanium nitride, and chromium nitride results in as much as increasing of the hardness of the material as well as decreasing the friction coefficient and increasing the oxidation resistance.

  8. Investigation of surface properties of high temperature nitrided titanium alloys

    Directory of Open Access Journals (Sweden)

    E. Koyuncu

    2009-12-01

    Full Text Available Purpose: The purpose of paper is to investigate surface properties of high temperature nitrided titanium alloys.Design/methodology/approach: In this study, surface modification of Ti6Al4V titanium alloy was made at various temperatures by plasma nitriding process. Plasma nitriding treatment was performed in 80% N2-20% H2 gas mixture, for treatment times of 2-15 h at the temperatures of 700-1000°C. Surface properties of plasma nitrided Ti6Al4V alloy were examined by metallographic inspection, X-Ray diffraction and Vickers hardness.Findings: Two layers were determined by optic inspection on the samples that were called the compound and diffusion layers. Compound layer contain TiN and Ti2N nitrides, XRD results support in this formations. Maximum hardness was obtained at 10h treatment time and 1000°C treatment temperature. Micro hardness tests showed that hardness properties of the nitrided samples depend on treatment time and temperature.Practical implications: Titanium and its alloys have very attractive properties for many industries. But using of titanium and its alloys is of very low in mechanical engineering applications because of poor tribological properties.Originality/value: The nitriding of titanium alloy surfaces using plasma processes has already reached the industrial application stage in the biomedical field.

  9. Characterization of plasma nitrided layers produced on sintered iron

    Directory of Open Access Journals (Sweden)

    Marcos Alves Fontes

    2014-07-01

    Full Text Available Plasma nitriding is a thermo-physical-chemical treatment process, which promotes surface hardening, caused by interstitial diffusion of atomic nitrogen into metallic alloys. In this work, this process was employed in the surface modification of a sintered ferrous alloy. Scanning electron microscopy (SEM, X-ray diffraction (XRD analyses, and wear and microhardness tests were performed on the samples submitted to ferrox treatment and plasma nitriding carried out under different conditions of time and temperature. The results showed that the nitride layer thickness is higher for all nitrided samples than for ferrox treated samples, and this layer thickness increases with nitriding time and temperature, and temperature is a more significant variable. The XRD analysis showed that the nitrided layer, for all samples, near the surface consists in a mixture of γ′-Fe4N and ɛ-Fe3N phases. Both wear resistance and microhardness increase with nitriding time and temperature, and temperature influences both the characteristics the most.

  10. Solvothermal synthesis of crystalline carbon nitrides

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

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

  11. High efficiency III-nitride light-emitting diodes

    Science.gov (United States)

    Crawford, Mary; Koleske, Daniel; Cho, Jaehee; Zhu, Di; Noemaun, Ahmed; Schubert, Martin F; Schubert, E. Fred

    2013-05-28

    Tailored doping of barrier layers enables balancing of the radiative recombination among the multiple-quantum-wells in III-Nitride light-emitting diodes. This tailored doping enables more symmetric carrier transport and uniform carrier distribution which help to reduce electron leakage and thus reduce the efficiency droop in high-power III-Nitride LEDs. Mitigation of the efficiency droop in III-Nitride LEDs may enable the pervasive market penetration of solid-state-lighting technologies in high-power lighting and illumination.

  12. Preparation of Ultra-fine Aluminum Nitride in Thermal Plasma

    Institute of Scientific and Technical Information of China (English)

    漆继红; 罗义文; 印永祥; 代晓雁

    2002-01-01

    Ultra-fine aluminum nitride has been synthesized by the evaporation of aluminum powder at atmospheric-pressure nitrogen plasma in a hot-wall reactor. The average size of aluminum nitride particle is 0.11μm measured by scanning electric mirror (SEM), and the purity is at least over 90% evaluated by X-Ray diffraction (XRD). The conversion of Al powder to aluminum nitride is strongly depended on the injection of NH3. Typical experimental parameters such as the feed rate of raw material, the flow rate of ammonia and the position of injecting aluminum powder into the reactor are given.

  13. Local Heating with Lithographically Fabricated Plasmonic Titanium Nitride Nanoparticles

    DEFF Research Database (Denmark)

    Guler, Urcan; Ndukaife, Justus C.; Naik, Gururaj V.;

    2013-01-01

    Titanium nitride is considered a promising alternative plasmonic material and is known to exhibit localized surface plasmon resonances within the near-infrared biological transparency window. Here, local heating efficiencies of disk-shaped nanoparticles made of titanium nitride and gold...... are compared in the visible and near-infrared regions numerically and experimentally with samples fabricated using e-beam lithography. Results show that plasmonic titanium nitride nanodisks are efficient local heat sources and outperform gold nanodisks in the biological transparency window, dispensing the need...

  14. Conductive and robust nitride buffer layers on biaxially textured substrates

    Science.gov (United States)

    Sankar, Sambasivan [Chicago, IL; Goyal, Amit [Knoxville, TN; Barnett, Scott A [Evanston, IL; Kim, Ilwon [Skokie, IL; Kroeger, Donald M [Knoxville, TN

    2009-03-31

    The present invention relates to epitaxial, electrically conducting and mechanically robust, cubic nitride buffer layers deposited epitaxially on biaxially textured substrates such as metals and alloys. The invention comprises of a biaxially textured substrate with epitaxial layers of nitrides. The invention also discloses a method to form such epitaxial layers using a high rate deposition method as well as without the use of forming gases. The invention further comprises epitaxial layers of oxides on the biaxially textured nitride layer. In some embodiments the article further comprises electromagnetic devices which may have superconducting properties.

  15. A high Tc superconductor bolometer on a silicon nitride membrane

    OpenAIRE

    Sanchez, Stefan; Elwenspoek, Miko; Gui, Chengqun; Nivelle, de, M.J.M.E.; De, Vries; Korte, de, N.; Bruijn, Marcel P.; Wijnbergen, Jan J.; Michalke, Wolfgang; Steinbeiss, Erwin; Heidenblut, Torsten; Schwierzi, Bernard

    1998-01-01

    In this paper, we describe the design, fabrication, and performance of a high-Tc GdBa2Cu3O7-¿ superconductor bolometer positioned on a 2× 2-mm2 1-¿m-thick silicon nitride membrane. The bolometer structure has an effective area of 0.64 mm2 and was grown on a specially developed silicon-on-nitride (SON) layer. This layer was made by direct bonding of silicon nitride to silicon after chemical mechanical polishing. The operation temperature of the bolometer is 85 K. A thermal conductance G=3.3·10...

  16. Application Of Active Screen Method For Ion Nitriding Efficiency Improvement

    Directory of Open Access Journals (Sweden)

    Ogórek M.

    2015-06-01

    Full Text Available Paper presents the research of austenitic steel AISI 304 after ion nitriding at 400°C and at t =4h, for the two different variants of samples distribution in the working plasma reactive chamber tube. In order to assess the effectiveness of ion nitriding variants emission spectroscopy – GDOES, surface hardness tests, microstructure research (LM of nitrided layers were made. It has been found that the use of active screens increases the surface layer thickness and depth of nitrogen diffusion into austenitic steel 304.

  17. Limitations to band gap tuning in nitride semiconductor alloys

    DEFF Research Database (Denmark)

    Gorczyca, I.; Suski, T.; Christensen, Niels Egede;

    2010-01-01

    Relations between the band gaps of nitride alloys and their lattice parameters are presented and limits to tuning of the fundamental gap in nitride semiconductors are set by combining a large number of experimental data with ab initio theoretical calculations. Large band gap bowings obtained...... theoretically for GaxAl1-xN, InxGa1-xN, and InxAl1-xN for uniform as well as clustered arrangements of the cation atoms are considered in the theoretical analysis. It is shown that indium plays a particular role in nitride alloys being responsible for most of the observed effects....

  18. Characteristics of Au/PZT/TiO2/Nitride/Si structure capacitors with ICP nitride treatments

    International Nuclear Information System (INIS)

    In this study, the characteristics of PZT/TiO2 ferroelectric gate stack capacitors with Inductively Coupled Plasma (ICP) nitridation were investigated for field effect transistor (FET)-type Ferroelectric Random Access Memory (FeRAM) applications. If a high accumulation capacitance is to be had, the ICP nitridation time needs to be optimized. While a short ICP treatment time results in thermal oxide growth due to lack of nitrogen, a long nitridation time causes a nitride layer which is too thick. Au/PZT(200 nm)/TiO2(40 nm)/Nitride/Si (MeFINS) structure capacitors show a memory window (ΔV) of 1.6 V under ±3-V operation while Au/PZT(200 nm)/TiO2(40 nm)/Si (MeFIS) capacitors without nitride treatment exhibit a small memory window of 0.6 V. At the same time, the capacitance of the MeFINS device is almost twice that of the MeFIS capacitor. This result implies that the ICP nitride treatment suppresses the formation of a low dielectric constant interfacial SiOx layer and alleviates the series capacitance problem

  19. Characteristics of Au/PZT/TiO{sub 2}/Nitride/Si structure capacitors with ICP nitride treatments

    Energy Technology Data Exchange (ETDEWEB)

    Min, Hyung Seob; Kim, Tae Ho; Jeon, Chang Bae; Lee, Jae Gab; Kim, Ji Young [Kookmin Univ., Seoul (Korea, Republic of)

    2002-01-01

    In this study, the characteristics of PZT/TiO{sub 2} ferroelectric gate stack capacitors with Inductively Coupled Plasma (ICP) nitridation were investigated for field effect transistor (FET)-type Ferroelectric Random Access Memory (FeRAM) applications. If a high accumulation capacitance is to be had, the ICP nitridation time needs to be optimized. While a short ICP treatment time results in thermal oxide growth due to lack of nitrogen, a long nitridation time causes a nitride layer which is too thick. Au/PZT(200 nm)/TiO{sub 2}(40 nm)/Nitride/Si (MeFINS) structure capacitors show a memory window ({delta}V) of 1.6 V under {+-}3-V operation while Au/PZT(200 nm)/TiO{sub 2}(40 nm)/Si (MeFIS) capacitors without nitride treatment exhibit a small memory window of 0.6 V. At the same time, the capacitance of the MeFINS device is almost twice that of the MeFIS capacitor. This result implies that the ICP nitride treatment suppresses the formation of a low dielectric constant interfacial SiO{sub x} layer and alleviates the series capacitance problem.

  20. Beryllium decorated armchair boron nitride nanoribbon: A new planar tetracoordinate nitride containing system with enhanced conductivity

    Science.gov (United States)

    Xiao, Bo; Yu, Xuefang; Hu, Hong; Ding, Yihong

    2014-07-01

    In this Letter, a new kind of planar tetracoordinate nitride (ptN) structure is obtained via Be-decorated armchair boron nitride nanoribbon (aBNNR). The high stability of such a ptN system is confirmed by both global minimization and molecular dynamical simulation at 1500 K. The results suggest that this Be-decorated aBNNR will be a thermally stable material. The electronic property of aBNNR is significantly increased after the addition of Be atoms to the edges and the band gap decreases as the width of the ribbon decreases. Our Letter posits a new and potentially stable and useful BNNR and augments the literature on ptN.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-05-15

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

  2. High Temperature Oxidation of Boron Nitride. Part 1; Monolithic Boron Nitride

    Science.gov (United States)

    Jacobson, Nathan; Farmer, Serene; Moore, Arthur; Sayir, Haluk

    1997-01-01

    High temperature oxidation of monolithic boron nitride (BN) is examined. Hot pressed BN and both low and high density CVD BN were studied. It is shown that oxidation rates are quite sensitive to microstructural factors such as orientation, porosity, and degree of crystallinity. In addition small amounts of water vapor lead to volatilization of the B2O3 oxide as H(x)B(y)O(z). For these reasons, very different oxidation kinetics were observed for each type of BN.

  3. Fabrication of Aluminum Gallium Nitride/Gallium Nitride MESFET And It's Applications in Biosensing

    Science.gov (United States)

    Alur, Siddharth

    Gallium Nitride has been researched extensively for the past three decades for its application in Light Emitting Diodes (LED's), power devices and UV photodetectors. With the recent developments in crystal growth technology and the ability to control the doping there has been an increased interest in heterostructures formed between Gallium nitride and it's alloy Aluminium Gallium Nitride. These heterostructures due to the combined effect of spontaneous and piezoelectric effect can form a high density and a high mobility electron gas channel without any intentional doping. This high density electron gas makes these heterostructures ideal to be used as sensors. Gallium Nitride is also chemically very stable. Detection of biomolecules in a fast and reliable manner is very important in the areas of food safety and medical research. For biomolecular detection it is paramount to have a robust binding of the probes on the sensor surface. Therefore, in this dissertation, the fabrication and application of the AlGaN/GaN heterostructures as biological sensors for the detection of DNA and Organophosphate hydrolase enzyme is discussed. In order to use these AlGaN/GaN heterostructures as biological sensors capable of working in a liquid environment photodefinable polydimethyl-siloxane is used as an encapsulant. The immobilization conditions for a robust binding of thiolated DNA and the catalytic receptor enzyme organophosphate hydrolase on gold surfaces is developed with the help of X-ray photoelectron spectroscopy. DNA and OPH are detected by measuring the change in the drain current of the device as a function of time.

  4. Plasma nitriding monitoring reactor: A model reactor for studying plasma nitriding processes using an active screen

    Science.gov (United States)

    Hamann, S.; Börner, K.; Burlacov, I.; Spies, H.-J.; Strämke, M.; Strämke, S.; Röpcke, J.

    2015-12-01

    A laboratory scale plasma nitriding monitoring reactor (PLANIMOR) has been designed to study the basics of active screen plasma nitriding (ASPN) processes. PLANIMOR consists of a tube reactor vessel, made of borosilicate glass, enabling optical emission spectroscopy (OES) and infrared absorption spectroscopy. The linear setup of the electrode system of the reactor has the advantages to apply the diagnostic approaches on each part of the plasma process, separately. Furthermore, possible changes of the electrical field and of the heat generation, as they could appear in down-scaled cylindrical ASPN reactors, are avoided. PLANIMOR has been used for the nitriding of steel samples, achieving similar results as in an industrial scale ASPN reactor. A compact spectrometer using an external cavity quantum cascade laser combined with an optical multi-pass cell has been applied for the detection of molecular reaction products. This allowed the determination of the concentrations of four stable molecular species (CH4, C2H2, HCN, and NH3). With the help of OES, the rotational temperature of the screen plasma could be determined.

  5. Plasma nitriding monitoring reactor: A model reactor for studying plasma nitriding processes using an active screen

    Energy Technology Data Exchange (ETDEWEB)

    Hamann, S., E-mail: hamann@inp-greifswald.de; Röpcke, J. [INP-Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Börner, K.; Burlacov, I.; Spies, H.-J. [TU Bergakademie Freiberg, Institute of Materials Engineering, Gustav-Zeuner-Str. 5, 09599 Freiberg (Germany); Strämke, M.; Strämke, S. [ELTRO GmbH, Arnold-Sommerfeld-Ring 3, 52499 Baesweiler (Germany)

    2015-12-15

    A laboratory scale plasma nitriding monitoring reactor (PLANIMOR) has been designed to study the basics of active screen plasma nitriding (ASPN) processes. PLANIMOR consists of a tube reactor vessel, made of borosilicate glass, enabling optical emission spectroscopy (OES) and infrared absorption spectroscopy. The linear setup of the electrode system of the reactor has the advantages to apply the diagnostic approaches on each part of the plasma process, separately. Furthermore, possible changes of the electrical field and of the heat generation, as they could appear in down-scaled cylindrical ASPN reactors, are avoided. PLANIMOR has been used for the nitriding of steel samples, achieving similar results as in an industrial scale ASPN reactor. A compact spectrometer using an external cavity quantum cascade laser combined with an optical multi-pass cell has been applied for the detection of molecular reaction products. This allowed the determination of the concentrations of four stable molecular species (CH{sub 4}, C{sub 2}H{sub 2}, HCN, and NH{sub 3}). With the help of OES, the rotational temperature of the screen plasma could be determined.

  6. Microstructure and Hardness of High Temperature Gas Nitrided AISI 420 Martensitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    Ibrahim Nor Nurulhuda Md.

    2014-07-01

    Full Text Available This study examined the microstructure and hardness of as-received and nitrided AISI 420 martensitic stainless steels. High temperature gas nitriding was employed to treat the steels at 1200°C for one hour and four hours using nitrogen gas, followed by furnace cooled. Chromium nitride and iron nitride were formed and concentrated at the outmost surface area of the steels since this region contained the highest concentration of nitrogen. The grain size enlarged at the interior region of the nitrided steels due to nitriding at temperature above the recrystallization temperature of the steel and followed by slow cooling. The nitrided steels produced higher surface hardness compared to as-received steel due to the presence of nitrogen and the precipitation of nitrides. Harder steel was produced when nitriding at four hours compared to one hour since more nitrogen permeated into the steel.

  7. Physics of wurtzite nitrides and oxides passport to devices

    CERN Document Server

    Gil, Bernard

    2014-01-01

    This book gives a survey of the current state of the art of a special class of nitrides semiconductors, Wurtzite Nitride and Oxide Semiconductors. It includes properties, growth and applications. Research in the area of nitrides semiconductors is still booming although some basic materials sciences issues were solved already about 20 years ago. With the advent of modern technologies and the successful growth of nitride substrates, these materials currently experience a second birth. Advanced new applications like light-emitters, including UV operating LEDs, normally on and normally off high frequency operating transistors are expected. With progress in clean room technology, advanced photonic and quantum optic applications are envisioned in a close future. This area of research is fascinating for researchers and students in materials science, electrical engineering, chemistry, electronics, physics and biophysics. This book aims to be the ad-hoc instrument to this active field of research.

  8. Thermal Effect of Ceramic Nanofiller Aluminium Nitride on Polyethylene Properties

    Directory of Open Access Journals (Sweden)

    Omer Bin Sohail

    2012-01-01

    Full Text Available Ethylene polymerization was done to form polyethylene nano-composite with nanoaluminum nitride using zirconocene catalysts. Results show that the catalytic activity is maximum at a filler loading of 15 mg nanoaluminum nitride. Differential scanning calorimeter (DSC and X-ray diffraction (XRD results show that percentage crystallinity was also marginally higher at this amount of filler. Thermal behavior of polyethylene nanocomposites (0, 15, 30, and 45 mg was studied by DSC and thermal gravimetric analyzer (TGA. Morphology of the component with 15 mg aluminium nitride is more fibrous as compared to 0 mg aluminium nitride and higher filler loading as shown by SEM images. In order to understand combustibility behavior, tests were performed on microcalorimeter. Its results showed decrease in combustibility in polyethylene nanocomposites as the filler loading increases.

  9. Plasma-nitriding of tantalum at relatively low temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Deyuan; LIN Qin; ZHAO Haomin; FEI Qinyong; GENG Man

    2004-01-01

    The combined quadratic orthogonal regression method of experiment design was employed to explore the effects of process parameters of plasma nitriding of tantalum such as total pressure, temperature and original hydrogen molar fraction on the hardness, roughness and structure of nitriding surfaces. The regression equations of hardness, roughness and structure were given according to the results of regression and statistic analysis. And the diffusion activation energy of nitrogen in tantalum on plasma nitriding conditions was calculated according to the experimental data of hardness of plasma-nitriding of tantalum vs time and temperature. The diffusion activation energy calculated belongs to (155.49 + 10.51)kJ/mol (783-983 K).

  10. Research of functional properties of nitride ion-plasma coatings

    Science.gov (United States)

    Vaulina, O. Yu; Ovechkin, B. B.; Papchenko, A. V.; Shvagrukova, E. V.

    2016-02-01

    This paper considers the influence of ion-plasma coatings with the use of nitrogen (N), zirconium nitride (ZrN), titanium-aluminum nitride (Ti,Al)N and titanium nitride and zirconium nitride by-layer (TiN+ZrN - eight layers) on the properties of steel 65X13. The main functional properties of the coatings are determined: microhardness, nanohardness, Young's modulus and corrosion resistance. It is shown that all the types of coatings allow increasing the physical and mechanical characteristics of instrument steel 65X13. Hardness and wear-resistance, depending on the type of the deposited coating, increase from 1, 5 to 4 times, corrosion resistance increases by tens times.

  11. Infrared Dielectric Properties of Low-stress Silicon Nitride

    Science.gov (United States)

    Cataldo, Giuseppe; Beall, James A.; Cho, Hsiao-Mei; McAndrew, Brendan; Niemack, Michael D.; Wollack, Edward J.

    2012-01-01

    Silicon nitride thin films play an important role in the realization of sensors, filters, and high-performance circuits. Estimates of the dielectric function in the far- and mid-IR regime are derived from the observed transmittance spectra for a commonly employed low-stress silicon nitride formulation. The experimental, modeling, and numerical methods used to extract the dielectric parameters with an accuracy of approximately 4% are presented.

  12. LASER GAS NITRIDING OF TITANIUM AND TITANIUM ALLOYS

    OpenAIRE

    J. J. DAI; Hou, S. Q.

    2009-01-01

    Titanium and titanium alloys are widely used in many fields due to some of their characteristics such as light density, high strength, and excellent corrosion resistance. However, poor mechanical performances limit their practical applications. Laser gas nitriding is a promising method used to improve the surface properties of components. Recent developments on laser gas nitriding of titanium and titanium alloys are reviewed. The processing parameters have important effects on the resulting c...

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

    Directory of Open Access Journals (Sweden)

    Z. Yang

    2016-01-01

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

  14. Platinum group metal nitrides and carbides: synthesis, properties and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Ivanovskii, Alexander L [Institute of Solid State Chemistry, Urals Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation)

    2009-04-30

    Experimental and theoretical data on new compounds, nitrides and carbides of the platinum group 4d and 5d metals (ruthenium, rhodium, palladium, osmium, iridium, platinum), published over the past five years are summarized. The extreme mechanical properties of platinoid nitrides and carbides, i.e., their high strength and low compressibility, are noted. The prospects of further studies and the scope of application of these compounds are discussed.

  15. Research of nanocomposite structure of boron nitride at proton radiation

    OpenAIRE

    Borodin, Yuri Viktorovich; Ermolaev, D. S.; Pak, V.; Zhang, K.

    2016-01-01

    Using roentgen diffraction and electron microscopy, the influence of nanosecond irradiation by ion beams of high energy on forming of self-organized nanoblocks in near surface's layers of boron nitride (BN) has been studied. It was shown that low temperature transitions from hexagonal to wrutz boron nitrides is associated with changes of shape and sizes of self-organized particles consisting the nanoblocks. We have calculated the parameters of nanoblocks using the meanings of interplane dista...

  16. Corrosion behavior of tantalum and its nitride in alkali solution

    Institute of Scientific and Technical Information of China (English)

    ZHANG Deyuan; LIN Qin; FEI Qinyong; ZHAO Haomin; KANG Guangyu; GENG Man

    2003-01-01

    The corrosion behavior of tantalum and its nitrides in stirring NaOH solutions was researched by potenfiostatic method, cyclic voltammetry and XPS. The results showed that the corrosion products were composed of Ta2O5 and NaTaO3.The corrosion reaction formula of tantalum and its nitrides was written according to cyclic volt-ampere curves. The electric charge transfer coefficient and the electric charge transfer number were calculated.

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

    OpenAIRE

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

    2014-01-01

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

  18. Cubic boron nitride- a new material for ultracold neutron application

    International Nuclear Information System (INIS)

    For the first time, the Fermi potential of cubic boron nitride (cBN) was measured at the ultra cold neutron source at the TRIGA reactor, Mainz using the time of flight method (TOF). The investigated samples have a Fermi potential of about 300 neV. Because of its good dielectric characteristics, cubic boron nitride could be used as suitable coating for insulator in storage chambers of future EDM projects. This talk presents recent results and an outlook on further investigations.

  19. Study on Titanium Nitride Film Modified for Intraocular Lens

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Objective:To study the characteristics of the intraocular lens using ion beam sputtering depositing titanium nitride thin film on the intraocular lens(IOLs).Methods:To deposite titanium nitride thin film on the top of intraocular lens by ion beam sputtering depositing.We analyzed the surface morphology of intraocular lens through SEM and AFM.We detected intraocular lens resolution through the measurement of intraocular lens.Biocompatibility of intraocular lens is preliminary evaluated in this test.Results:T...

  20. Apparatus for the production of boron nitride nanotubes

    Science.gov (United States)

    Smith, Michael W; Jordan, Kevin

    2014-06-17

    An apparatus for the large scale production of boron nitride nanotubes comprising; a pressure chamber containing; a continuously fed boron containing target; a source of thermal energy preferably a focused laser beam; a cooled condenser; a source of pressurized nitrogen gas; and a mechanism for extracting boron nitride nanotubes that are condensed on or in the area of the cooled condenser from the pressure chamber.

  1. Vertical transport in graphene-hexagonal boron nitride heterostructure devices

    OpenAIRE

    Samantha Bruzzone; Demetrio Logoteta; Gianluca Fiori; Giuseppe Iannaccone

    2015-01-01

    Research in graphene-based electronics is recently focusing on devices based on vertical heterostructures of two-dimensional materials. Here we use density functional theory and multiscale simulations to investigate the tunneling properties of single- and double-barrier structures with graphene and few-layer hexagonal boron nitride (h-BN) or hexagonal boron carbon nitride (h-BC2N). We find that tunneling through a single barrier exhibit a weak dependence on energy. We also show that in double...

  2. Performance of chromium nitride based coatings under plastic processing conditions

    OpenAIRE

    Cunha, l.; Andritschky, M.; Pischow, K.; Wang, Z.(Institute of High Energy Physics, Beijing, China); Zarychta, A.; Miranda, A. S.; A.M. Cunha

    2000-01-01

    Chromium nitride based coatings were produced in the form of monolithic and multilayer coatings, by DC and RF reactive magnetron sputtering. These coatings were deposited onto stainless steel and tool steel substrates. Chromium nitride coatings have;proved to be wear and corrosion resistant. The combination of these characteristics was necessary to protect surfaces during plastic processing. In order to select the best coatings, some mechanical and tribological tests were performed. Har...

  3. Optical loss analysis of silicon rich nitride waveguides

    DEFF Research Database (Denmark)

    Mertens, Hans; Andersen, Karin Nordström; Svendsen, Winnie Edith

    2002-01-01

    An analysis of the propagation loss in high-index LPCVD-grown silicon rich nitride (SRN) slab waveguides and channel waveguides is presented. A propagation loss as low as 0.6 dB/cm has been achieved.......An analysis of the propagation loss in high-index LPCVD-grown silicon rich nitride (SRN) slab waveguides and channel waveguides is presented. A propagation loss as low as 0.6 dB/cm has been achieved....

  4. Low temperature gaseous nitriding of Ni based superalloys

    DEFF Research Database (Denmark)

    Eliasen, K. M.; Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2010-01-01

    In the present work the nitriding response of selected Ni based superalloys at low temperatures is addressed. The alloys investigated are nimonic series nos. 80, 90, 95 and 100 and nichrome (Ni/Cr......In the present work the nitriding response of selected Ni based superalloys at low temperatures is addressed. The alloys investigated are nimonic series nos. 80, 90, 95 and 100 and nichrome (Ni/Cr...

  5. Four-Wave Mixing in Silicon-Rich Nitride Waveguides

    DEFF Research Database (Denmark)

    Mitrovic, Miranda; Guan, Xiaowei; Ji, Hua;

    2015-01-01

    We demonstrate four-wave mixing wavelength conversion in silicon-rich nitride waveguides which are a promising alternative to silicon for nonlinear applications. The obtained conversion efficiency reaches -13.6 dB while showing no significant nonlinear loss.......We demonstrate four-wave mixing wavelength conversion in silicon-rich nitride waveguides which are a promising alternative to silicon for nonlinear applications. The obtained conversion efficiency reaches -13.6 dB while showing no significant nonlinear loss....

  6. Nitrogen Atom Transfer From High Valent Iron Nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Michael D. [New Mexico State Univ., Las Cruces, NM (United States); Smith, Jeremy M. [Indiana Univ., Bloomington, IN (United States)

    2015-10-14

    This report describes the synthesis and reactions of high valent iron nitrides. Organonitrogen compounds such as aziridines are useful species for organic synthesis, but there are few efficient methods for their synthesis. Using iron nitrides to catalytically access these species may allow for their synthesis in an energy-and atom-efficient manner. We have developed a new ligand framework to achieve these goals as well as providing a method for inducing previously unknown reactivity.

  7. Laser ablation of molecular carbon nitride compounds

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

  8. Pure and doped boron nitride nanotubes

    Directory of Open Access Journals (Sweden)

    M. Terrones

    2007-05-01

    Full Text Available More than ten years ago, it was suggested theoretically that boron nitride (BN nanotubes could be produced. Soon after, various reports on their synthesis appeared and a new area of nanotube science was born. This review aims to cover the latest advances related to the synthesis of BN nanotubes. We show that these tubes can now be produced in larger amounts and, in particular, that the chemistry of BN tubes appears to be very important to the production of reinforced composites with insulating characteristics. From the theoretical standpoint, we also show that (BN-C heteronanotubes could have important implications for nanoelectronics. We believe that BN nanotubes (pure and doped could be used in the fabrication of novel devices in which pure carbon nanotubes do not perform very efficiently.

  9. Thermal Conductivity of Uranium Nitride and Carbide

    Directory of Open Access Journals (Sweden)

    B. Szpunar

    2014-01-01

    Full Text Available We investigate the electronic thermal conductivity of alternative fuels like uranium nitride and uranium carbide. We evaluate the electronic contribution to the thermal conductivity, by combining first-principles quantum-mechanical calculations with semiclassical correlations. The electronic structure of UN and UC was calculated using Quantum Espresso code. The spin polarized calculations were performed for a ferromagnetic and antiferromagnetic ordering of magnetic moments on uranium lattice and magnetic moment in UC was lower than in UN due to stronger hybridization between 2p electrons of carbon and 5f electrons of uranium. The nonmagnetic electronic structure calculations were used as an input to BolzTrap code that was used to evaluate the electronic thermal conductivity. It is predicted that the thermal conductivity should increase with the temperature increase, but to get a quantitative agreement with the experiment at higher temperatures the interaction of electrons with phonons (and electron-electron scattering needs to be included.

  10. Quantum emission from hexagonal boron nitride monolayers.

    Science.gov (United States)

    Tran, Toan Trong; Bray, Kerem; Ford, Michael J; Toth, Milos; Aharonovich, Igor

    2016-01-01

    Artificial atomic systems in solids are widely considered the leading physical system for a variety of quantum technologies, including quantum communications, computing and metrology. To date, however, room-temperature quantum emitters have only been observed in wide-bandgap semiconductors such as diamond and silicon carbide, nanocrystal quantum dots, and most recently in carbon nanotubes. Single-photon emission from two-dimensional materials has been reported, but only at cryogenic temperatures. Here, we demonstrate room-temperature, polarized and ultrabright single-photon emission from a colour centre in two-dimensional hexagonal boron nitride. Density functional theory calculations indicate that vacancy-related defects are a probable source of the emission. Our results demonstrate the unprecedented potential of van der Waals crystals for large-scale nanophotonics and quantum information processing. PMID:26501751

  11. Boron nitride: A new photonic material

    Energy Technology Data Exchange (ETDEWEB)

    Chubarov, M., E-mail: mihcu@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Pedersen, H., E-mail: henke@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Högberg, H., E-mail: hanho@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Filippov, S., E-mail: stafi@ifm.liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Engelbrecht, J.A.A., E-mail: Japie.Engelbrecht@nmmu.ac.za [Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); O' Connel, J., E-mail: jacques.oconnell@gmail.com [Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Henry, A., E-mail: anne.henry@liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden)

    2014-04-15

    Rhombohedral boron nitride (r-BN) layers were grown on sapphire substrate in a hot-wall chemical vapor deposition reactor. Characterization of these layers is reported in details. X-ray diffraction (XRD) is used as a routine characterization tool to investigate the crystalline quality of the films and the identification of the phases is revealed using detailed pole figure measurements. Transmission electron microscopy reveals stacking of more than 40 atomic layers. Results from Fourier Transform InfraRed (FTIR) spectroscopy measurements are compared with XRD data showing that FTIR is not phase sensitive when various phases of sp{sup 2}-BN are investigated. XRD measurements show a significant improvement of the crystalline quality when adding silicon to the gas mixture during the growth; this is further confirmed by cathodoluminescence which shows a decrease of the defects related luminescence intensity.

  12. Hexagonal boron nitride and water interaction parameters

    Science.gov (United States)

    Wu, Yanbin; Wagner, Lucas K.; Aluru, Narayana R.

    2016-04-01

    The study of hexagonal boron nitride (hBN) in microfluidic and nanofluidic applications at the atomic level requires accurate force field parameters to describe the water-hBN interaction. In this work, we begin with benchmark quality first principles quantum Monte Carlo calculations on the interaction energy between water and hBN, which are used to validate random phase approximation (RPA) calculations. We then proceed with RPA to derive force field parameters, which are used to simulate water contact angle on bulk hBN, attaining a value within the experimental uncertainties. This paper demonstrates that end-to-end multiscale modeling, starting at detailed many-body quantum mechanics and ending with macroscopic properties, with the approximations controlled along the way, is feasible for these systems.

  13. Boron nitride: A new photonic material

    International Nuclear Information System (INIS)

    Rhombohedral boron nitride (r-BN) layers were grown on sapphire substrate in a hot-wall chemical vapor deposition reactor. Characterization of these layers is reported in details. X-ray diffraction (XRD) is used as a routine characterization tool to investigate the crystalline quality of the films and the identification of the phases is revealed using detailed pole figure measurements. Transmission electron microscopy reveals stacking of more than 40 atomic layers. Results from Fourier Transform InfraRed (FTIR) spectroscopy measurements are compared with XRD data showing that FTIR is not phase sensitive when various phases of sp2-BN are investigated. XRD measurements show a significant improvement of the crystalline quality when adding silicon to the gas mixture during the growth; this is further confirmed by cathodoluminescence which shows a decrease of the defects related luminescence intensity.

  14. Thermal tuners on a Silicon Nitride platform

    CERN Document Server

    Pérez, Daniel; Baños, Rocío; Doménech, José David; Sánchez, Ana M; Cirera, Josep M; Mas, Roser; Sánchez, Javier; Durán, Sara; Pardo, Emilio; Domínguez, Carlos; Pastor, Daniel; Capmany, José; Muñoz, Pascual

    2016-01-01

    In this paper, the design trade-offs for the implementation of small footprint thermal tuners on silicon nitride are presented, and explored through measurements and supporting simulations of a photonic chip based on Mach-Zehnder Interferometers. Firstly, the electrical properties of the tuners are assessed, showing a compromise between compactness and deterioration. Secondly, the different variables involved in the thermal efficiency, switching power and heater dimensions, are analysed. Finally, with focus on exploring the limits of this compact tuners with regards to on chip component density, the thermal-cross talk is also investigated. Tuners with footprint of 270x5 {\\mu}m 2 and switching power of 350 mW are reported, with thermal-cross talk, in terms of induced phase change in adjacent devices of less than one order of magnitude at distances over 20 {\\mu}m. Paths for the improvement of thermal efficiency, power consumption and resilience of the devices are also outlined

  15. Carbon nitride frameworks and dense crystalline polymorphs

    Science.gov (United States)

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

    2016-09-01

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

  16. Gallium Nitride Room Temperature α Particle Detectors

    International Nuclear Information System (INIS)

    Gallium Nitride (GaN) room temperature α particle detectors are fabricated and characterized, whose device structure is Schottky diode. The current-voltage (I – V) measurements reveal that the reverse breakdown voltage of the detectors is more than 200 V owing to the consummate fabrication processes, and that the Schottky barrier and ideal factor of the detectors are 0.64 eV and 1.02, respectively, calculated from the thermionic transmission model. 241Am α particles pulse height spectra from the GaN detectors biased at −8 V is obviously one Gauss peak located at channel 44 with the full width at half maximum (FWHM) of 15.87 in channel. One of the main reasons for the relatively wider FWHM is that the air between the detectors and isotope could widen the spectrum

  17. Mechanical Hysteresis of Hexagonal Boron Nitride

    Institute of Scientific and Technical Information of China (English)

    ZHOU Aiguo; LI Haoran

    2011-01-01

    Hexagonal boron nitride (h-BN) is an important structural material with layered microstructure.Because of the plastic anisotropy,this material shows obvious mechanical hysteresis (nonlinear elastic deformation).There are hysteretic loops at the cyclical load-unload stress-strain curves of h-BN.Consequently,two hot-pressed h-BN cylinders with different textures were studied.The mechanical hysteresis is heavily texture-dependent.The area of hysteretic loop is linearly related with the square of loading stresslevel.Two minor loops attached on the hysteretic loops with the same extreme stresses have congruent shapes.It can be concluded that the mechanical hysteresis of h-BN can he explained by a Kink Nonlinear Elastic model developed from the study of a ternary carbide Ti3SiC2.

  18. Synthesis and characterization of boron nitrides nanotubes

    International Nuclear Information System (INIS)

    This paper presents a new synthesis for the production of boron nitride nanotubes (BNNT) from boron powder, ammonium nitrate and hematite tube furnace CVD method. The samples were subjected to some characterization techniques as infrared spectroscopy, thermal analysis, X-ray diffraction and scanning electron microscopy and transmission. By analyzing the results can explain the chemical reactions involved in the process and confirm the formation of BNNT with several layers and about 30 nanometers in diameter. Due to excellent mechanical properties and its chemical and thermal stability this material is promising for various applications. However, BNNT has received much less attention than carbon nanotubes, it is because of great difficulty to synthesize appreciable quantities from the techniques currently known, and this is one of the main reasons this work.(author)

  19. Excitons in boron nitride single layer

    Science.gov (United States)

    Galvani, Thomas; Paleari, Fulvio; Miranda, Henrique P. C.; Molina-Sánchez, Alejandro; Wirtz, Ludger; Latil, Sylvain; Amara, Hakim; Ducastelle, François

    2016-09-01

    Boron nitride single layer belongs to the family of two-dimensional materials whose optical properties are currently receiving considerable attention. Strong excitonic effects have already been observed in the bulk and still stronger effects are predicted for single layers. We present here a detailed study of these properties by combining ab initio calculations and a tight-binding Wannier analysis in both real and reciprocal space. Due to the simplicity of the band structure with single valence (π ) and conduction (π*) bands the tight-binding analysis becomes quasiquantitative with only two adjustable parameters and provides tools for a detailed analysis of the exciton properties. Strong deviations from the usual hydrogenic model are evidenced. The ground-state exciton is not a genuine Frenkel exciton, but a very localized tightly bound one. The other ones are similar to those found in transition-metal dichalcogenides and, although more localized, can be described within a Wannier-Mott scheme.

  20. Hexagonal boron nitride and water interaction parameters.

    Science.gov (United States)

    Wu, Yanbin; Wagner, Lucas K; Aluru, Narayana R

    2016-04-28

    The study of hexagonal boron nitride (hBN) in microfluidic and nanofluidic applications at the atomic level requires accurate force field parameters to describe the water-hBN interaction. In this work, we begin with benchmark quality first principles quantum Monte Carlo calculations on the interaction energy between water and hBN, which are used to validate random phase approximation (RPA) calculations. We then proceed with RPA to derive force field parameters, which are used to simulate water contact angle on bulk hBN, attaining a value within the experimental uncertainties. This paper demonstrates that end-to-end multiscale modeling, starting at detailed many-body quantum mechanics and ending with macroscopic properties, with the approximations controlled along the way, is feasible for these systems. PMID:27131542

  1. Optical processes in dilute nitrides Semiconductors; Alloys

    CERN Document Server

    Potter, R J

    2003-01-01

    This thesis is concerned with the narrow bandgap semiconductor alloys known as dilute nitrides. The initial part of this project was concerned with characterisation of chemical beam epitaxy (CBE) grown samples so that growth techniques could be refined. Early samples show evidence of structural/compositional disorder resulting from the large miscibility gap induced by nitrogen. Non-equilibrium growth was employed to overcome this, eventually resulting in improved material. In the second part of this project, steady-state and time-resolved photoluminescence, along with photomodulated reflectance were employed to investigate the optical properties of molecular beam epitaxy (MBE) grown GalnNAs, GaNAs and InGaAs quantum wells (QWs). Low temperature results show evidence of carrier localization, which was interpreted in terms of structural/compositional fluctuations induced by the nitrogen incorporation. Poor photoluminescence efficiency and rapid decay of emission kinetics indicate the presence of strong non-radi...

  2. Boron Nitride Nanotube: Synthesis and Applications

    Science.gov (United States)

    Tiano, Amanda L.; Park, Cheol; Lee, Joseph W.; Luong, Hoa H.; Gibbons, Luke J.; Chu, Sang-Hyon; Applin, Samantha I.; Gnoffo, Peter; Lowther, Sharon; Kim, Hyun Jung; Danehy, Paul M.; Inman, Jennifer A.; Jones, Stephen B.; Kang, Jin Ho; Sauti, Godfrey; Thibeault, Sheila A.; Yamakov, Vesselin; Wise, Kristopher E.; Su, Ji; Fay, Catharine C.

    2014-01-01

    Scientists have predicted that carbon's immediate neighbors on the periodic chart, boron and nitrogen, may also form perfect nanotubes, since the advent of carbon nanotubes (CNTs) in 1991. First proposed then synthesized by researchers at UC Berkeley in the mid 1990's, the boron nitride nanotube (BNNT) has proven very difficult to make until now. Herein we provide an update on a catalyst-free method for synthesizing highly crystalline, small diameter BNNTs with a high aspect ratio using a high power laser under a high pressure and high temperature environment first discovered jointly by NASA/NIA JSA. Progress in purification methods, dispersion studies, BNNT mat and composite formation, and modeling and diagnostics will also be presented. The white BNNTs offer extraordinary properties including neutron radiation shielding, piezoelectricity, thermal oxidative stability (> 800 C in air), mechanical strength, and toughness. The characteristics of the novel BNNTs and BNNT polymer composites and their potential applications are discussed.

  3. Gallium Nitride Schottky betavoltaic nuclear batteries

    International Nuclear Information System (INIS)

    Research highlights: → Gallium Nitride nuclear batteries with Ni-63 are demonstrated for the first time. → Open circuit voltage of 0.1 V and conversion efficiency of 0.32% have been obtained. → The limited performance is due to thin effective energy deposition layer. → The output power is expected to greatly increase with growing thick GaN films. -- Abstract: Gallium Nitride (GaN) Schottky betavoltaic nuclear batteries (GNBB) are demonstrated in our work for the first time. GaN films are grown on sapphire substrates by metalorganic chemical vapor deposition (MOCVD), and then GaN Schottky diodes are fabricated by normal micro-fabrication process. Nickel with mass number of 63 (63Ni), which emits β particles, is loaded on the GaN Schottky diodes to achieve GNBB. X-ray diffraction (XRD) and photoluminescence (PL) are carried out to investigate the crystal quality for the GaN films as grown. Current-voltage (I-V) characteristics shows that the GaN Schottky diodes are not jet broken down at -200 V due to consummate fabrication processes, and the open circuit voltage of the GNBB is 0.1 V and the short circuit current density is 1.2 nA cm-2. The limited performance of the GNBB is due to thin effective energy deposition layer, which is only 206 nm to absorb very small partial energy of the β particles because of the relatively high dislocation density and carrier concentration. However, the conversion efficiency of 0.32% and charge collection efficiency (CCE) of 29% for the GNBB have been obtained. Therefore, the output power of the GNBB are expected to greatly increase with growing high quality thick GaN films.

  4. Improvement in Corrosion Resistance of Anchor Steel by Low Temperature Plasma Nitriding

    Institute of Scientific and Technical Information of China (English)

    NIU Shaoqing; YANG Shuangsuo; LI Yi

    2014-01-01

    Plasma nitriding was used to improve the corrosion performance of anchor steel. The microstructure, phase constitution, microhardness and corrosion resistance of the nitrided layer were systematically studied. The results show that the nitrided layer is continuous and dense, and consists of Fe4N and Fe3N in the outmost surface. The microhardness of the nitrided sample is improved because of the formation of nitrides in the outer side continuous layer and the inner parts. The nitrided layer on the surface of anchor steel can effectively improve the corrosion resistance of the anchor steel.

  5. Modeling the kinetics of the nitriding and nitrocarburizing of iron

    DEFF Research Database (Denmark)

    Somers, Marcel A. J.; Mittemeijer, Eric J.

    1998-01-01

    The growth kinetics of the iron-nitride compound layer during nitriding and nitrocarburizing of pure iron has been investigated for various temperatures and various combinations of imposed nitrogen and carbon activities. The results indicate that no local equilibrium occurs at the gas/solid inter......The growth kinetics of the iron-nitride compound layer during nitriding and nitrocarburizing of pure iron has been investigated for various temperatures and various combinations of imposed nitrogen and carbon activities. The results indicate that no local equilibrium occurs at the gas....../solid interface during nitriding/nitrocarburizing, due to the slow kinetics of ammonia dissociation, the development and subsequent desorption of molecular nitrogen gas at the surface and, for the case of nitrocarburizing, the fast initial carbon uptake. The kinetics of gaseous nitriding of pure iron can...... be adequately described by a model that adopts local equilibrium at the solid/solid interfaces and a composition-weighted intrinsic diffusion coefficient of nitrogen in the Fe-N phases. For nitrocarburizing modeling appears not possible yet, due to compositions at gas/solid and solid/solid interfaces which...

  6. High-temperature nitridation of Ni-Cr alloys

    Science.gov (United States)

    Kodentsov, A. A.; Gülpen, J. H.; Cserháti, C.; Kivilahti, J. K.; van Loo, F. J. J.

    1996-01-01

    The nitriding behavior of nickel-chromium alloys was investigated at 1398 K over the range 1 to 6000 bar of external nitrogen pressure. The morphology of the nitrided zone depends on the concentration of chromium in the initial alloy and the N2 pressure (fugacity) applied upon the system. The transition from CrN to Cr2N precipitation was observed within the reaction zone after nitriding at 100 to 6000 bar of N2 when the chromium content in the initial alloys was 28.0 at. pct or higher. It is shown that the ternary phase π (Cr10Ni7N3) is formed in this system at 1273 K. through a peritectoid reaction between Cr2N and nickel solid solution and becomes unstable above 1373 K. The thermodynamic evaluation of the Ni-Cr-N system was performed and phase equilibria calculated. Evidence for “up hill” diffusion of nitrogen near the reaction front during the internal nitridation of Ni-Cr alloys at 1398 K was found. It was attributed to the relative instability of chromium nitrides and strong Cr-N interaction in the matrix of the Ni-based solid solution within the nitrided zone.

  7. The prospect of uranium nitride (UN) and mixed nitride fuel (UN-PuN) for pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Syarifah, Ratna Dewi, E-mail: syarifah.physics@gmail.com; Suud, Zaki, E-mail: szaki@fi.itb.ac.id [Nuclear Physics and Biophysics Research Division, Physics Department, Faculty of Mathematics and Natural Science, Bandung Institute of Technology Jalan Ganesha 10, Bandung 40132 (Indonesia)

    2015-09-30

    Design study of small Pressurized Water Reactors (PWRs) core loaded with uranium nitride fuel (UN) and mixed nitride fuel (UN-PuN), Pa-231 as burnable poison, and Americium has been performed. Pa-231 known as actinide material, have large capture cross section and can be converted into fissile material that can be utilized to reduce excess reactivity. Americium is one of minor actinides with long half life. The objective of adding americium is to decrease nuclear spent fuel in the world. The neutronic analysis results show that mixed nitride fuel have k-inf greater than uranium nitride fuel. It is caused by the addition of Pu-239 in mixed nitride fuel. In fuel fraction analysis, for uranium nitride fuel, the optimum volume fractions are 45% fuel fraction, 10% cladding and 45% moderator. In case of UN-PuN fuel, the optimum volume fractions are 30% fuel fraction, 10% cladding and 60% coolant/ moderator. The addition of Pa-231 as burnable poison for UN fuel, enrichment U-235 5%, with Pa-231 1.6% has k-inf more than one and excess reactivity of 14.45%. And for mixed nitride fuel, the lowest value of reactivity swing is when enrichment (U-235+Pu) 8% with Pa-231 0.4%, the excess reactivity value 13,76%. The fuel pin analyze for the addition of Americium, the excess reactivity value is lower than before, because Americium absorb the neutron. For UN fuel, enrichment U-235 8%, Pa-231 1.6% and Am 0.5%, the excess reactivity is 4.86%. And for mixed nitride fuel, when enrichment (U-235+Pu) 13%, Pa-231 0.4% and Am 0.1%, the excess reactivity is 11.94%. For core configuration, it is better to use heterogeneous than homogeneous core configuration, because the radial power distribution is better.

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

    KAUST Repository

    Alhajri, Nawal Saad

    2016-02-22

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

  9. EDITORIAL: Non-polar and semipolar nitride semiconductors Non-polar and semipolar nitride semiconductors

    Science.gov (United States)

    Han, Jung; Kneissl, Michael

    2012-02-01

    Throughout the history of group-III-nitride materials and devices, scientific breakthroughs and technological advances have gone hand-in-hand. In the late 1980s and early 1990s, the discovery of the nucleation of smooth (0001) GaN films on c-plane sapphire and the activation of p-dopants in GaN led very quickly to the realization of high-brightness blue and green LEDs, followed by the first demonstration of GaN-based violet laser diodes in the mid 1990s. Today, blue InGaN LEDs boast record external quantum efficiencies exceeding 80% and the emission wavelength of the InGaN-based laser diode has been pushed into the green spectral range. Although these tremenduous advances have already spurred multi-billion dollar industries, there are still a number of scientific questions and technological issues that are unanswered. One key challenge is related to the polar nature of the III-nitride wurtzite crystal. Until a decade ago all research activities had almost exclusively concentrated on (0001)-oriented polar GaN layers and heterostructures. Although the device characteristics seem excellent, the strong polarization fields at GaN heterointerfaces can lead to a significant deterioration of the device performance. Triggered by the first demonstration non-polar GaN quantum wells grown on LiAlO2 by Waltereit and colleagues in 2000, impressive advances in the area of non-polar and semipolar nitride semiconductors and devices have been achieved. Today, a large variety of heterostructures free of polarization fields and exhibiting exceptional electronic and optical properties have been demonstrated, and the fundamental understanding of polar, semipolar and non-polar nitrides has made significant leaps forward. The contributions in this Semiconductor Science and Technology special issue on non-polar and semipolar nitride semiconductors provide an impressive and up-to-date cross-section of all areas of research and device physics in this field. The articles cover a wide range of

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

    Science.gov (United States)

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

    2014-07-23

    A method to directly electrolessly plate silicon-rich silicon nitride with thin gold films was developed and characterized. Films with thicknesses coating planar, curved, and line-of-sight-obscured silicon nitride surfaces. PMID:24999923

  11. Evaluation of plasma nitriding efficiency of titanium alloys for medical applications

    OpenAIRE

    Frączek, T.; Olejnik, M.; Tokarz, A.

    2009-01-01

    The surface layers obtained on selected titanium alloys, used in medicine, by the nitriding under glow discharge condition were investigated. The results concern of: α- titanium alloy Grade 2 and α + β alloys Grade 5 and Grade 5 ELI nitrided in temperature below 873 K. The nitriding experiments were performed in a current glow-discharge furnace JON-600 with assisting of unconventional methods. After nitriding surface layers were characterised by surface microhardness measuremen...

  12. Molecular dynamics studies of the bonding properties of amorphous silicon nitride coatings on crystalline silicon

    OpenAIRE

    Butler, K.T.; Lamers, M.P.W.E.; Weeber, A. W.; Harding, J. H.

    2011-01-01

    In this paper we present molecular dynamics simulations of silicon nitride, both in bulk and as an interface to crystalline silicon. We investigate, in particular, the bonding structure of the silicon nitride and analyze the simulations to search for de- fective geometries which have been identified as potential charge carrier traps when silicon nitride forms an interface with silicon semiconductors. The simulations reveal how the bonding patterns in silicon nitride are dependent upon the sto...

  13. Effect of Treatment Temperature on Iron Nitride Foils Irradiated with Nitrogen Plasma

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    We investigated the effect of treatment temperature on the magnetic property of iron nitride foils irradiated with nitrogen plasma. The iron nitride foils irradiated with nitrogen plasma were composed of ε-Fe2~3N, γ′-Fe4N and γ nitrogen austenite in α-Fe of the matrix. The saturation magnetization of the iron nitride foils decreased with increasing the surface temperature. The coercive force of the iron nitride foils increased with increasing the surface temperature.

  14. Technical assistance for development of thermally conductive nitride filler for epoxy molding compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Ho Jin; Song, Kee Chan; Jung, In Ha

    2005-07-15

    Technical assistance was carried out to develop nitride filler for thermally conductive epoxy molding compounds. Carbothermal reduction method was used to fabricate silicon nitride powder from mixtures of silica and graphite powders. Microstructure and crystal structure were observed by using scanning electron microscopy and x-ray diffraction technique. Thermal properties of epoxy molding compounds containing silicon nitride were measured by using laser flash method. Fabrication process of silicon nitride nanowire was developed and was applied to a patent.

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

    Institute of Scientific and Technical Information of China (English)

    YAN Ming; HUANG Chun-Hui

    2005-01-01

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

  16. Nitriding of iron-based alloys : residual stresses and internal strain fields

    OpenAIRE

    Vives Díaz, Nicolás

    2007-01-01

    Different iron-chromium alloys (4, 8, 13 and 20 wt.% Cr) were nitrided in NH3/H2 gas mixtures at 580 ºC. The nitrided microstructure was investigated by X-ray diffraction, light microscopy, hardness measurements and scanning electron microscopy. Composition depth-profiles of the nitrided zone were determined by electron probe microanalysis. Various microstructures develop, depending on the nitriding conditions and the alloy composition (chromium content). The initial development of coherent, ...

  17. Microstructure and Mechanical Propertiesof a Nitride-Strengthened Reduced ActivationFerritic/Martensitic Steel

    OpenAIRE

    Zhou, Qiangguo; Zhang, Wenfeng; Yan, Wei; Wang, Wei; SHA, WEI; Shan, Yiyin; Yang, Ke

    2012-01-01

    Nitride-strengthened reduced activation ferritic/martensitic (RAFM) steels are developed taking advantage of the high thermal stability of nitrides. In the current study, the microstructure and mechanical properties of a nitride-strengthened RAFM steel with improved composition were investigated. Fully martensitic microstructure with fine nitrides dispersion was achieved in the steel. In all, 1.4 pct Mn is sufficient to suppress delta ferrite and assure the steel of the full martensitic micro...

  18. Turbostratic boron nitride coated on high-surface area metal oxide templates

    DEFF Research Database (Denmark)

    Klitgaard, Søren Kegnæs; Egeblad, Kresten; Brorson, M.;

    2007-01-01

    Boron nitride coatings on high-surface area MgAl2O4 and Al2O3 have been synthesized and characterized by transmission electron microscopy and by X-ray powder diffraction. The metal oxide templates were coated with boron nitride using a simple nitridation in a flow of ammonia starting from ammoniu...

  19. Mathematical Models and Computer Simulation of Nitrogen Concentration Profiles in Pulse Plasma Nitrided Layers

    Institute of Scientific and Technical Information of China (English)

    Mufu YAN; Qingchang MENG; Jihong YAN

    2003-01-01

    Two materials, pure Fe and pure Al, were nitrided in a pulse plasma nitriding facility. The nitrogen profiles in surface layers and the surface phase structures of specimens nitrided at 500℃ for 8 h for Fe and for 6 h for Al were measured using the glow

  20. UN{sub 2−x} layer formed on uranium metal by glow plasma nitriding

    Energy Technology Data Exchange (ETDEWEB)

    Long, Zhong [China Academy of Engineering Physics, P.O. Box 919-71, Mianyang 621907 (China); Hu, Yin [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China); Chen, Lin [China Academy of Engineering Physics, P.O. Box 919-71, Mianyang 621907 (China); Luo, Lizhu [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China); Liu, Kezhao, E-mail: liukz@hotmail.com [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China); Lai, Xinchun, E-mail: lai319@yahoo.com [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China)

    2015-01-25

    Highlights: • We used a very simple method to prepare nitride layer on uranium metal surface. • This modified layer is nitrogen-rich nitride, which should be written as UN{sub 2−x}. • TEM images show the nitride layer is composed of nano-sized grains. • XPS analysis indicates there is uranium with abnormal low valence in the nitride. - Abstract: Glow plasma nitriding is a simple and economical surface treatment method, and this technology was used to prepare nitride layer on the surface of uranium metal with thickness of several microns. The composition and structure of the nitride layer were analyzed by AES and XRD, indicating that this modified layer is nitrogen-rich uranium nitride, which should be written as UN{sub 2−x}. TEM images show the nitride layer is composed of nano-sized grains, with compact structure. And XPS analysis indicates there is uranium with abnormal low valence existing in the nitride. After the treated uranium storage in air for a long time, oxygen just entered the surface several nanometers, showing the nitride layer has excellent oxidation resistance. The mechanism of nitride layer formation and low valence uranium appearance is discussed.

  1. Corrosion behaviour of the 42CrMo4 Steel Nitrided by Plasma

    Directory of Open Access Journals (Sweden)

    Okba Belahssen

    2014-01-01

    Full Text Available This paper presents corrosion behaviour of alloy 42CrMo4 steel nitrided by plasma. Different samples were tested: untreated and plasma nitrided samples. The corrosion behaviour was evaluated by electrochemical techniques (potentiodynamic curves and electrochemical impedance spectroscopy. The corrosion tests were carried out in acid chloride solution 1M. The best corrosion protection was observed for samples nitrided.

  2. Effective Duration of Gas Nitriding Process on AISI 316L for the Formation of a Desired Thickness of Surface Nitrided Layer

    Directory of Open Access Journals (Sweden)

    Mahmoud Hassan R. S.

    2014-07-01

    Full Text Available High temperature gas nitriding performed on AISI 316L at the temperature of 1200°C. The microstructure of treated AISI 316L samples were observed to identify the formation of the microstructure of nitrided surface layer. The grain size of austenite tends to be enlarged when the nitriding time increases, but the austenite single phase structure is maintained even after the long-time solution nitriding. Using microhardness testing, the hardness values drop to the center of the samples. The increase in surface hardness is due to the high nitrogen concentration at or near the surface. At 245HV, the graph of the effective duration of nitriding process was plotted to achieve the maximum depth of nitrogen diffuse under the surface. Using Sigma Plot software best fit lines of the experimental result found and plotted to find out effective duration of nitriding equation as Y=1.9491(1-0.7947x, where Y is the thickness of nitrided layer below the surface and X is duration of nitriding process. Based on this equation, the duration of gas nitriding process can be estimated to produce desired thickness of nitrided layer.

  3. The melting parameters of high-temperature nonmetallic nitrides

    International Nuclear Information System (INIS)

    The ranges of temperatures and pressures for the existence of condensed boron, aluminum, and silicon nonmetallic nitrides in thermodynamic equilibrium with an ambient gas were calculated on the basis of reference data. The melting parameters of the high-temperature nitrides mentioned above were investigated experimentally in the nitrogen pressure range of 5200 MPa. The 99% purity nitride samples were prepared in the form of 4 x 4-mm plates with a thickness of 1 mm. The surfaces of samples were heated with stationary laser beam and analyzed by X-ray technique. The brightness temperature of nonmetallic nitrides was measured at 0.633-μm wavelength using the optical pyrometry method. The apparent melting temperatures were found from the analysis of heating and cooling thermograms. Based on the available literature data on normal spectral emmissivity, the true melting temperatures of nonmetallic nitrides were estimated as 3370 K for BN, 3025 K for AlN, and 2775 K for Si3N4

  4. Formation and nitridation of vanadium-aluminum intermetallic compounds.

    Science.gov (United States)

    Lewalter, H; Bock, W; Kolbesen, B O

    2002-10-01

    V(5)Al(8) and V(3)Al intermetallics have been formed by interdiffusion, by annealing of sputtered V/Al-multilayers at 700 degrees C in vacuo; sapphire (102) was used as substrate. The V/Al intermetallics were nitridated in NH(3) at 900 degrees C for 1 min by RTP (rapid thermal processing). The samples were investigated with XRD (X-ray diffraction), SNMS (secondary neutral mass spectrometry), and AFM (atomic force microscopy). A 5-10 nm thick AlN film (001 textured) was formed by nitridation of V(5)Al(8) (110 textured) and 2-3% nitrogen was incorporated in the V(5)Al(8) bulk. Nitridation of V(3)Al resulted in the formation of VN and AlN. Direct nitridation of V/Al-multilayers showed that near the surface nitridation is faster than intermixing of the V and Al layers. The capability of VN as diffusion barrier for Al could also be shown. PMID:12397502

  5. Surface properties of nitrided layer on AISI 316L austenitic stainless steel produced by high temperature plasma nitriding in short time

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang, E-mail: metalytu@163.com [Department of Materials Science and Engineering, Yantai University, Qingquan Road 32, Yantai 264005 (China); Wang, Zhuo [Department of Materials Science and Engineering, Yantai University, Qingquan Road 32, Yantai 264005 (China); Wang, Liang [Department of Materials Science and Engineering, Dalian Maritime University, Linghai Road 1, Dalian 116026 (China)

    2014-04-01

    Graphical abstract: - Highlights: • The 8 μm nitrided layer was produced on the surface of AISI 316L stainless steel by plasma nitrided at high temperatures (540 °C) within 1 h. • The nitrided layer consisted of nitrogen expanded austenite and possibly a small amount of free-CrN and iron nitrides. • It could critically reduce processing time compared with low temperature nitriding. • High temperature plasma nitriding could improve pitting corrosion resistance of the substrate in 3.5% NaCl solution. - Abstract: It has generally been believed that the formation of the S phase or expanded austenite γ{sub N} with enough thickness depends on the temperature (lower than 480 °C) and duration of the process. In this work, we attempt to produce nitrogen expanded austenite layer at high temperature in short time. Nitriding of AISI 316L austenitic stainless steel was carried out at high temperatures (>520 °C) for times ranging from 5 to 120 min. The microstructures, chemical composition, the thickness and the morphology of the nitrided layer, as well as its surface hardness, were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, optical microscopy, scanning electron microscopy, and microhardness tester. The corrosion properties of the untreated and nitrided samples were evaluated using anodic polarization tests in 3.5% NaCl solution. The results confirmed that nitrided layer was shown to consist of γ{sub N} and a small amount of free-CrN and iron nitrides. High temperature plasma nitriding not only increased the surface hardness but also improved the corrosion resistance of the austenitic stainless steel, and it can critically reduce processing time compared with low temperature nitriding.

  6. Preparation of graphitic carbon nitride by electrodeposition

    Institute of Scientific and Technical Information of China (English)

    LI Chao; CAO Chuanbao; ZHU Hesun

    2003-01-01

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

  7. Fluorescent lighting with aluminum nitride phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Cherepy, Nerine J.; Payne, Stephen A.; Seeley, Zachary M.; Srivastava, Alok M.

    2016-05-10

    A fluorescent lamp includes a glass envelope; at least two electrodes connected to the glass envelope; mercury vapor and an inert gas within the glass envelope; and a phosphor within the glass envelope, wherein the phosphor blend includes aluminum nitride. The phosphor may be a wurtzite (hexagonal) crystalline structure Al.sub.(1-x)M.sub.xN phosphor, where M may be drawn from beryllium, magnesium, calcium, strontium, barium, zinc, scandium, yttrium, lanthanum, cerium, praseodymium, europium, gadolinium, terbium, ytterbium, bismuth, manganese, silicon, germanium, tin, boron, or gallium is synthesized to include dopants to control its luminescence under ultraviolet excitation. The disclosed Al.sub.(1-x)M.sub.xN:Mn phosphor provides bright orange-red emission, comparable in efficiency and spectrum to that of the standard orange-red phosphor used in fluorescent lighting, Y.sub.2O.sub.3:Eu. Furthermore, it offers excellent lumen maintenance in a fluorescent lamp, and does not utilize "critical rare earths," minimizing sensitivity to fluctuating market prices for the rare earth elements.

  8. Hexagonal boron-nitride nanomesh magnets

    Science.gov (United States)

    Ohata, C.; Tagami, R.; Nakanishi, Y.; Iwaki, R.; Nomura, K.; Haruyama, J.

    2016-09-01

    The formation of magnetic and spintronic devices using two-dimensional (2D) atom-thin layers has attracted attention. Ferromagnetisms (FMs) arising from zigzag-type atomic structure of edges of 2D atom-thin materials have been experimentally observed in graphene nanoribbons, hydrogen (H)-terminated graphene nanomeshes (NMs), and few-layer oxygen (O)-terminated black phosphorus NMs. Herein, we report room-temperature edge FM in few-layer hexagonal boron-nitride (hBN) NMs. O-terminated hBNNMs annealed at 500 °C show the largest FM, while it completely disappears in H-terminated hBNNMs. When hBNNMs are annealed at other temperatures, amplitude of the FM significantly decreases. These are highly in contrast to the case of graphene NMs but similar to the cases of black phosphorus NM and suggest that the hybridization of the O atoms with B(N) dangling bonds of zigzag pore edges, formed at the 500 °C annealing, strongly contribute to this edge FM. Room-temperature FM realizable only by exposing hBNNMs into air opens the way for high-efficiency 2D flexible magnetic and spintronic devices without the use of rare magnetic elements.

  9. Polymeric photocatalysts based on graphitic carbon nitride.

    Science.gov (United States)

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

    2015-04-01

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

  10. Plasmonic enhancement of photoluminescence from aluminium nitride

    Science.gov (United States)

    Flynn, Chris; Stewart, Matthew

    2016-03-01

    Aluminium nitride (AlN) films were grown on c-plane sapphire wafers by molecular beam epitaxy (MBE) under aluminium-rich conditions. The excess aluminium (Al) accumulated on the surface of the films as micro-scale droplets 1-10 μm in size, and as Al nanoparticles with diameters in the range 10-110 nm. Photoluminescence (PL) measurements were performed on the AlN samples using a 193 nm Excimer laser as the excitation source. Prior to PL measurements the wafers were cleaved in half. One half of each wafer was submitted to a 10 min treatment in H3PO4 heated to 70 °C to remove the excess Al from the film surface. The remaining half was left in the as-deposited condition. The mean intensities of the near-band-edge PL peaks of the as-deposited samples were 2.0-3.4 times higher compared to the samples subjected to the H3PO4 Al-removal treatment. This observation motivated calculations to determine the optimal Al surface nanosphere size for plasmonic enhancement of PL from AlN. The PL enhancement was found to peak for an Al nanosphere radius of 15 nm, which is within the range of the experimentally-observed Al nanoparticle sizes.

  11. Fully CMOS-compatible titanium nitride nanoantennas

    International Nuclear Information System (INIS)

    CMOS-compatible fabrication of plasmonic materials and devices will accelerate the development of integrated nanophotonics for information processing applications. Using low-temperature plasma-enhanced atomic layer deposition (PEALD), we develop a recipe for fully CMOS-compatible titanium nitride (TiN) that is plasmonic in the visible and near infrared. Films are grown on silicon, silicon dioxide, and epitaxially on magnesium oxide substrates. By optimizing the plasma exposure per growth cycle during PEALD, carbon and oxygen contamination are reduced, lowering undesirable loss. We use electron beam lithography to pattern TiN nanopillars with varying diameters on silicon in large-area arrays. In the first reported single-particle measurements on plasmonic TiN, we demonstrate size-tunable darkfield scattering spectroscopy in the visible and near infrared regimes. The optical properties of this CMOS-compatible material, combined with its high melting temperature and mechanical durability, comprise a step towards fully CMOS-integrated nanophotonic information processing

  12. Fully CMOS-compatible titanium nitride nanoantennas

    Energy Technology Data Exchange (ETDEWEB)

    Briggs, Justin A., E-mail: jabriggs@stanford.edu [Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305 (United States); Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305 (United States); Naik, Gururaj V.; Baum, Brian K.; Dionne, Jennifer A. [Department of Materials Science and Engineering, Stanford University, 496 Lomita Mall, Stanford, California 94305 (United States); Petach, Trevor A.; Goldhaber-Gordon, David [Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305 (United States)

    2016-02-01

    CMOS-compatible fabrication of plasmonic materials and devices will accelerate the development of integrated nanophotonics for information processing applications. Using low-temperature plasma-enhanced atomic layer deposition (PEALD), we develop a recipe for fully CMOS-compatible titanium nitride (TiN) that is plasmonic in the visible and near infrared. Films are grown on silicon, silicon dioxide, and epitaxially on magnesium oxide substrates. By optimizing the plasma exposure per growth cycle during PEALD, carbon and oxygen contamination are reduced, lowering undesirable loss. We use electron beam lithography to pattern TiN nanopillars with varying diameters on silicon in large-area arrays. In the first reported single-particle measurements on plasmonic TiN, we demonstrate size-tunable darkfield scattering spectroscopy in the visible and near infrared regimes. The optical properties of this CMOS-compatible material, combined with its high melting temperature and mechanical durability, comprise a step towards fully CMOS-integrated nanophotonic information processing.

  13. Conductivity of materials made of aluminum nitride and silicon nitride mixtures

    Science.gov (United States)

    Gorbatov, A. G.; Kamyshov, V. M.

    1978-01-01

    To establish the possible mechanism for conductivity in aluminum nitride a study was made of the electric conductivity of pure AlN and its mixtures with silicon nitride at different temperatures and partial pressures of nitrogen in the gas phase. The thermoelectromotive force was also measured. The experiments used polycrystalline samples of cylindrical shape 18 mm in diameter made of powders by hot pressing in graphite press molds at a temperature of 1973-2273 K and pressure 1,470,000 n/sqm. The items obtained by this method had porosity not over 5%. After pressing, the samples were machined to remove carbon from the surface, and were annealed in a stream of dry ammonia for 10 h at a temperature of 1273-1373 K. Electric conductivity was measured according to the bridge scheme on an alternating current of frequency 10 kHz. In order to guarantee close contact of the platinum electrodes with the surface of the samples, a thin layer of platinum was sprayed on them. Experiments were conducted in the temperature interval 1273-1573 K with a half hour delay at each assigned temperature with heating and cooling.

  14. Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding

    Energy Technology Data Exchange (ETDEWEB)

    Czarnowska, Elżbieta [Children' s Memorial Health Institute, Pathology Department, Al. Dzieci Polskich 20, 04-730 Warsaw (Poland); Borowski, Tomasz [Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw (Poland); Sowińska, Agnieszka [Children' s Memorial Health Institute, Pathology Department, Al. Dzieci Polskich 20, 04-730 Warsaw (Poland); Lelątko, Józef [Silesia University, Faculty of Computer Science and Materials Science, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland); Oleksiak, Justyna; Kamiński, Janusz; Tarnowski, Michał [Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw (Poland); Wierzchoń, Tadeusz, E-mail: twierz@inmat.pw.edu.pl [Warsaw University of Technology, Faculty of Materials Science and Engineering, Wołoska 141, 02-507 Warsaw (Poland)

    2015-04-15

    Highlights: • Low temperature plasma nitriding process of NiTi shape memory alloy is presented. • The possibility of treatment details of sophisticated shape. • TiN surface layer has diffusive character. • TiN surface layer increases corrosion resistance of NiTi alloy. • Produced TiN layer modify the biological properties of NiTi alloy. - Abstract: NiTi shape memory alloys are used for bone and cardiological implants. However, on account of the metallosis effect, i.e. the release of the alloy elements into surrounding tissues, they are subjected to various surface treatment processes in order to improve their corrosion resistance and biocompatibility without influencing the required shape memory properties. In this paper, the microstructure, topography and morphology of TiN surface layer on NiTi alloy, and corrosion resistance, both before and after nitriding in low-temperature plasma at 290 °C, are presented. Examinations with the use of the potentiodynamic and electrochemical impedance spectroscopy methods were carried out and show an increase of corrosion resistance in Ringer's solution after glow-discharge nitriding. This surface titanium nitride layer also improved the adhesion of platelets and the proliferation of osteoblasts, which was investigated in in vitro experiments with human cells. Experimental data revealed that nitriding NiTi shape memory alloy under low-temperature plasma improves its properties for bone implant applications.

  15. Elastic properties of indium nitrides grown on sapphire substrates determined by nano-indentation: In comparison with other nitrides

    Directory of Open Access Journals (Sweden)

    Ichiro Yonenaga

    2015-07-01

    Full Text Available The hardness of wurtzite indium nitride (α-InN films of 0.5 to 4 μm in thickness was measured by the nano-indentation method at room temperature. After investigation of crystalline quality by x-ray diffraction, the hardness and Young’s modulus were determined to be 8.8 ± 0.4 and 184 ± 5 GPa, respectively, for the In (0001- and N ( 000 1 ̄ -growth faces of InN films. The bulk and shear moduli were then derived to be 99 ± 3 and 77 ± 2 GPa, respectively. The Poisson’s ratio was evaluated to be 0.17 ± 0.03. The results were examined comprehensively in comparison with previously reported data of InN as well as those of other nitrides of aluminum nitride and gallium nitride. The underlying physical process determining the moduli and hardness was examined in terms of atomic bonding and dislocation energy of the nitrides and wurtzite zinc oxide.

  16. Electronic Biosensors Based on III-Nitride Semiconductors.

    Science.gov (United States)

    Kirste, Ronny; Rohrbaugh, Nathaniel; Bryan, Isaac; Bryan, Zachary; Collazo, Ramon; Ivanisevic, Albena

    2015-01-01

    We review recent advances of AlGaN/GaN high-electron-mobility transistor (HEMT)-based electronic biosensors. We discuss properties and fabrication of III-nitride-based biosensors. Because of their superior biocompatibility and aqueous stability, GaN-based devices are ready to be implemented as next-generation biosensors. We review surface properties, cleaning, and passivation as well as different pathways toward functionalization, and critically analyze III-nitride-based biosensors demonstrated in the literature, including those detecting DNA, bacteria, cancer antibodies, and toxins. We also discuss the high potential of these biosensors for monitoring living cardiac, fibroblast, and nerve cells. Finally, we report on current developments of covalent chemical functionalization of III-nitride devices. Our review concludes with a short outlook on future challenges and projected implementation directions of GaN-based HEMT biosensors.

  17. Active Control of Nitride Plasmonic Dispersion in the Far Infrared.

    Energy Technology Data Exchange (ETDEWEB)

    Shaner, Eric A.; Dyer, Gregory Conrad; Seng, William Francis; Bethke, Donald Thomas; Grine, Albert Dario,; Baca, Albert G.; Allerman, Andrew A.

    2014-11-01

    We investigate plasmonic structures in nitride-based materials for far-infrared (IR) applications. The two dimensional electron gas (2DEG) in the GaN/AlGaN material system, much like metal- dielectric structures, is a patternable plasmonic medium. However, it also permits for direct tunability via an applied voltage. While there have been proof-of-principle demonstrations of plasma excitations in nitride 2DEGs, exploration of the potential of this material system has thus far been limited. We recently demonstrated coherent phenomena such as the formation of plasmonic crystals, strong coupling of tunable crystal defects to a plasmonic crystal, and electromagnetically induced transparency in GaAs/AlGaAs 2DEGs at sub-THz frequencies. In this project, we explore whether these effects can be realized in nitride 2DEG materials above 1 THz and at temperatures exceeding 77 K.

  18. Electron microscopy of gallium nitride growth on polycrystalline diamond

    International Nuclear Information System (INIS)

    Transmission and scanning electron microscopy were used to examine the growth of gallium nitride (GaN) on polycrystalline diamond substrates grown by metalorganic vapour phase epitaxy with a low-temperature aluminium nitride (AlN) nucleation layer. Growth on unmasked substrates was in the (0001) orientation with threading dislocation densities ≈7 × 109 cm−2. An epitaxial layer overgrowth technique was used to reduce the dislocation densities further, by depositing silicon nitride stripes on the surface and etching the unmasked regions down to the diamond substrate. A re-growth was then performed on the exposed side walls of the original GaN growth, reducing the threading dislocation density in the overgrown regions by two orders of magnitude. The resulting microstructures and the mechanisms of dislocation reduction are discussed. (paper)

  19. Low-Temperature Nitriding by Means of SMAT

    Institute of Scientific and Technical Information of China (English)

    W.P. Tong; H.W. Zhang; N.R. Tao; Z.B. Wang; J. Lu; K. Lu

    2004-01-01

    The microstructure in the surface layer of iron and steel samples can be refined at the nanometer scale by means of a surface mechanical attrition treatment (SMAT) that generates repetitive severe plastic deformation to the surface layer.The subsequent nitriding kinetics of the as-treated samples with the nanostructured surface layer is greatly enhanced so that the nitriding temperatures can be reduce to 300 ~ 400 ℃ regions. This enhanced processing method demonstrates both the technological significance of nanomaterials in advancing the traditional processing techniques, and provides a new approach for selective surface reactions in solids. This article reviews the present state of the art in this field. The microstructure and properties of SMAT samples nitrided will be summarized. Further considerations of the development and applications of this new technique will also be presented.

  20. Nanoparticle plasmonics: going practical with transition metal nitrides

    Directory of Open Access Journals (Sweden)

    Urcan Guler

    2015-05-01

    Full Text Available Promising designs and experimental realizations of devices with unusual properties in the field of plasmonics have attracted a great deal of attention over the past few decades. However, the high expectations for realized technology products have not been met so far. The main complication is the absence of robust, high performance, low cost plasmonic materials that can be easily integrated into already established technologies such as microelectronics. This review provides a brief discussion on alternative plasmonic materials for localized surface plasmon applications and focuses on transition metal nitrides, in particular, titanium nitride, which has recently been shown to be a high performance refractory plasmonic material that could replace and even outperform gold in various plasmonic devices. As a material compatible with biological environments and the semiconductor industry, titanium nitride possesses superior properties compared to noble metals such as high temperature durability, chemical stability, corrosion resistance, low cost and mechanical hardness.

  1. Thermally grown thin nitride films as a gate dielectric

    CERN Document Server

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

    1998-01-01

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

  2. Symmetric organization of self-assembled carbon nitride

    International Nuclear Information System (INIS)

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

  3. Pressureless sintered silicon carbide tailored with aluminium nitride sintering agent

    International Nuclear Information System (INIS)

    This study reports the influence of aluminium nitride on the pressureless sintering of cubic phase silicon carbide nanoparticles (β-SiC). Pressureless sintering was achieved at 2000 degrees C for 5 min with the additions of boron carbide together with carbon of 1 wt% and 6 wt%, respectively, and a content of aluminium nitride between 0 and 10 wt%. Sintered samples present relative densities higher than 92%. The sintered microstructure was found to be greatly modified by the introduction of aluminium nitride, which reflects the influence of nitrogen on the β-SiC to α-SiC transformation. The toughness of sintered sample was not modified by AlN incorporation and is relatively low (around 2.5 MPa m1/2). Materials exhibited transgranular fracture mode, indicating a strong bonding between SiC grains. (authors)

  4. Kinetic modelling of chlorination of nitrided ilmenite using MATLAB

    Science.gov (United States)

    Ramakrishnan, Sivakumar; Kwok, Teong Chen; Hamid, Sheikh Abdul Rezan Sheikh Abdul

    2016-07-01

    In the present study, chlorination of nitride ilmenite using 2k factorial design was investigated. The reduction experiments were carried out in a temperature range of 400°C to 500°C, chlorination duration from 1 hour to 3 hours and using different type of carbon reactant. Phases of raw materials and reduced samples were analyzed by X-ray diffraction (XRD). Ilmenite was reduced to TiOxCyNz through carbothermal and nitridation for further chlorination into titanium tetrachloride. The Design of Experiment analysis suggested that the types of carbon reactant contribute most influence to the extent of chlorination of nitride ilmenite. The extent of chlorination was highest at 500°C with 3 hours chlorination time and carbon nanotube as carbon reactant.

  5. Design, Control and in Situ Visualization of Gas Nitriding Processes

    Directory of Open Access Journals (Sweden)

    Jerzy Ratajski

    2009-12-01

    Full Text Available The article presents a complex system of design, in situ visualization and control of the commonly used surface treatment process: the gas nitriding process. In the computer design conception, analytical mathematical models and artificial intelligence methods were used. As a result, possibilities were obtained of the poly-optimization and poly-parametric simulations of the course of the process combined with a visualization of the value changes of the process parameters in the function of time, as well as possibilities to predict the properties of nitrided layers. For in situ visualization of the growth of the nitrided layer, computer procedures were developed which make use of the results of the correlations of direct and differential voltage and time runs of the process result sensor (magnetic sensor, with the proper layer growth stage. Computer procedures make it possible to combine, in the duration of the process, the registered voltage and time runs with the models of the process.

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

    Science.gov (United States)

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

    2014-09-01

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

  7. Characterization of nitrided silicon-silicon dioxide interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Polignano, M.L.; Alessandri, M.; Brazzelli, D. [and others

    2000-07-01

    A newly-developed technique for the simultaneous characterization of the oxide-silicon interface properties and of bulk impurities was used for a systematic study of the nitridation process of thin oxides. This technique is based upon surface recombination velocity measurements, and does not require the formation of a capacitor structure, so it is very suitable for the characterization of as-grown interfaces. Oxides grown both in dry and in wet environments were considered, and nitridation processes in N{sub 2}O and in NO were compared to N{sub 2} annealing processes. The effect of nitridation temperature and duration were also studied, and RTO/RTN processes were compared to conventional furnace nitridation processes. Surface recombination velocity was correlated with nitrogen concentration at the oxide-silicon interface obtained by Secondary Ion Mass Spectroscopy (SIMS) measurements. Surface recombination velocity (hence surface state density) decreases with increasing nitrogen pile-up at the oxide-silicon interface, indicating that in nitrided interfaces surface state density is limited by nitridation. NO treatments are much more effective than N{sub 2}O treatments in the formation of nitrogen-rich interface layer and, as a consequence, in surface state reduction. Surface state density was measured in fully processed wafers before and after constant current stress. After a complete device process surface states are annealed out by hydrogen passivation, however they are reactivated by the electrical stress, and surface state results after stress were compared with data of surface recombination velocity in as-processed wafers.

  8. Formation of niobium nitride by rapid thermal processing

    Science.gov (United States)

    Angelkort, C.; Lewalter, H.; Warbichler, P.; Hofer, F.; Bock, W.; Kolbesen, B. O.

    2001-09-01

    The formation of group V transition metal nitride films by means of rapid thermal processing (RTP) has been investigated. Here we focus on the nitridation of niobium films of 200-500 nm thickness in the temperature range from 500 to 1100°C under laminar flow of molecular nitrogen or ammonia. The nitride phases formed were characterized by X-ray diffraction (XRD). Secondary neutral mass spectrometry (SNMS) and transmission electron microscopy (TEM) in combination with electron energy loss spectroscopy (EELS) were carried out on samples of selected experiments to provide more detailed information about the initial stages of nitride formation and the microstructure of the films. A classical formation sequence of nitride phases was observed with increasing nitrogen content in the order: α-Nb(N)→β-Nb 2N→γ-Nb 4N 3→δ'-NbN→Nb 5N 6. Furthermore, oxide enriched regions were discovered inside the metal films. These turned out to be formed mainly in the nitride sequence between the a-αNb(N) and β-Nb 2N-phases at the Nb/SiO 2 interface due to a reaction of the Nb with the SiO 2 layer of the silicon substrates on which the films had been deposited. The SiO 2 layer acts as diffusion barrier for nitrogen but also as source for oxygen, according to SNMS and TEM/EELS studies, resulting in the formation of Nb-oxides and/or oxynitrides at the Nb/SiO 2 interface.

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

    Science.gov (United States)

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

    2016-09-01

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

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

    International Nuclear Information System (INIS)

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

  11. The influence of nitride thickness variations on the switching speed of MNOS memory transistors

    DEFF Research Database (Denmark)

    Bruun, Erik

    1978-01-01

    The influence of nitride thickness variations on the switching speed of MNOS memory transistors is examined. The switching time constant is calculated as a function of the nitride thickness using a model of modified Fowler-Nordheim injection. The calculated characteristics compare well with measu...... with measured characteristics and show a strong dependence on the nitride thickness.......The influence of nitride thickness variations on the switching speed of MNOS memory transistors is examined. The switching time constant is calculated as a function of the nitride thickness using a model of modified Fowler-Nordheim injection. The calculated characteristics compare well...

  12. Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Drryl P. Butt; Brian Jaques

    2009-03-31

    Research conducted for this NERI project has advanced the understanding and feasibility of nitride nuclear fuel processing. In order to perform this research, necessary laboratory infrastructure was developed; including basic facilities and experimental equipment. Notable accomplishments from this project include: the synthesis of uranium, dysprosium, and cerium nitrides using a novel, low-cost mechanical method at room temperature; the synthesis of phase pure UN, DyN, and CeN using thermal methods; and the sintering of UN and (Ux, Dy1-x)N (0.7 ≤ X ≤ 1) pellets from phase pure powder that was synthesized in the Advanced Materials Laboratory at Boise State University.

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

    Science.gov (United States)

    Rinaldo, Steven G.

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

  14. Process for producing wurtzitic or cubic boron nitride

    International Nuclear Information System (INIS)

    Disclosed is a process for producing wurtzitic or cubic boron nitride comprising the steps of: [A] preparing an intimate mixture of powdered boron oxide, a powdered metal selected from the group consisting of magnesium or aluminum, and a powdered metal azide; [B] igniting the mixture and bringing it to a temperature at which self-sustaining combustion occurs; [C] shocking the mixture at the end of the combustion thereof with a high pressure wave, thereby forming as a reaction product, wurtzitic or cubic boron nitride and occluded metal oxide; and, optionally [D] removing the occluded metal oxide from the reaction product. Also disclosed are reaction products made by the process described

  15. Wear monitoring of protective nitride coatings using image processing

    DEFF Research Database (Denmark)

    Rasmussen, Inge Lise; Guibert, M.; Belin, M.;

    2010-01-01

    A double-layer model system, consisting of a thin layer of tribological titanium aluminum nitride (TiAlN) on 17 top of titanium nitride (TiN), was deposited on polished 100Cr6 steel substrates. The TiAlN top-coatings 18 were exposed to abrasive wear by a reciprocating wear process in a linear tribo...... processing by color detection is a potential technique for early 25 warning or determination of residual thickness of tribological tool coatings prior to complete wear....

  16. Fabrication of sinterable silicon nitride by injection molding

    Science.gov (United States)

    Quackenbush, C. L.; French, K.; Neil, J. T.

    1982-01-01

    Transformation of structural ceramics from the laboratory to production requires development of near net shape fabrication techniques which minimize finish grinding. One potential technique for producing large quantities of complex-shaped parts at a low cost, and microstructure of sintered silicon nitride fabricated by injection molding is discussed and compared to data generated from isostatically dry-pressed material. Binder selection methodology, compounding of ceramic and binder components, injection molding techniques, and problems in binder removal are discussed. Strength, oxidation resistance, and microstructure of sintered silicon nitride fabricated by injection molding is discussed and compared to data generated from isostatically dry-pressed material.

  17. Inter-layer potential for hexagonal boron nitride

    Science.gov (United States)

    Leven, Itai; Azuri, Ido; Kronik, Leeor; Hod, Oded

    2014-03-01

    A new interlayer force-field for layered hexagonal boron nitride (h-BN) based structures is presented. The force-field contains three terms representing the interlayer attraction due to dispersive interactions, repulsion due to anisotropic overlaps of electron clouds, and monopolar electrostatic interactions. With appropriate parameterization, the potential is able to simultaneously capture well the binding and lateral sliding energies of planar h-BN based dimer systems as well as the interlayer telescoping and rotation of double walled boron-nitride nanotubes of different crystallographic orientations. The new potential thus allows for the accurate and efficient modeling and simulation of large-scale h-BN based layered structures.

  18. CONFIRM: Collaboration on Nitride Fuel Irradiation and Modelling

    International Nuclear Information System (INIS)

    Uranium free nitride fuels are investigated as a potential fuel applied to waste transmutation in accelerator driven systems. In the European 5. FP CONFIRM project, four (Pu,Zr)N helium bonded fuel pins will be fabricated at PSI and then irradiated to high burnup at Studsvik in 2003/2004. (Am,Zr)N pellets will be manufactured and characterised at ITU. In addition, nitride safety analysis and fuel modelling is performed at KTH, AEA-T, CEA and BNFL. In the present contribution, the work program of CONFIRM is reviewed. Some initial results from activities on safety analysis and fuel modelling are also presented. (author)

  19. Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

    International Nuclear Information System (INIS)

    Research conducted for this NERI project has advanced the understanding and feasibility of nitride nuclear fuel processing. In order to perform this research, necessary laboratory infrastructure was developed; including basic facilities and experimental equipment. Notable accomplishments from this project include: the synthesis of uranium, dysprosium, and cerium nitrides using a novel, low-cost mechanical method at room temperature; the synthesis of phase pure UN, DyN, and CeN using thermal methods; and the sintering of UN and (Ux, Dy1-x)N (0.7 (le) X (le) 1) pellets from phase pure powder that was synthesized in the Advanced Materials Laboratory at Boise State University.

  20. Communication: Water on hexagonal boron nitride from diffusion Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamdani, Yasmine S.; Ma, Ming; Michaelides, Angelos, E-mail: angelos.michaelides@ucl.ac.uk [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Alfè, Dario [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT (United Kingdom); Lilienfeld, O. Anatole von [Institute of Physical Chemistry and National Center for Computational Design and Discovery of Novel Materials, Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Argonne Leadership Computing Facility, Argonne National Laboratories, 9700 S. Cass Avenue Argonne, Lemont, Illinois 60439 (United States)

    2015-05-14

    Despite a recent flurry of experimental and simulation studies, an accurate estimate of the interaction strength of water molecules with hexagonal boron nitride is lacking. Here, we report quantum Monte Carlo results for the adsorption of a water monomer on a periodic hexagonal boron nitride sheet, which yield a water monomer interaction energy of −84 ± 5 meV. We use the results to evaluate the performance of several widely used density functional theory (DFT) exchange correlation functionals and find that they all deviate substantially. Differences in interaction energies between different adsorption sites are however better reproduced by DFT.

  1. Hardness and thermal stability of cubic silicon nitride

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Kragh, Flemming; Frost, D. J.;

    2001-01-01

    The hardness and thermal stability of cubic spinel silicon nitride (c-Si3N4), synthesized under high-pressure and high-temperature conditions, have been studied by microindentation measurements, and x-ray powder diffraction and scanning electron microscopy, respectively The phase at ambient...... temperature has an average hardness of 35.31 GPa, slightly larger than SiO2 stishovite, which is often referred to as the third hardest material after diamond and cubic boron nitride. The cubic phase is stable up to 1673 K in air. At 1873 K, alpha -and beta -Si3N4 phases are observed, indicating a phase...

  2. Nanostructuring for nitride light-emitting diodes and opticalcavities

    OpenAIRE

    Li, Kwai-hei.; 李攜曦.

    2013-01-01

    The group of III-V semiconductors is emerging as highly attractive materials for a wide range of applications, particularly the gallium nitride family of alloys. Undoubtedly, the development of nitride-based light-emitting diodes (LEDs) and laser diodes (LDs) represented a quantum leap in the advancement of optoelectronics. The timely arrival of InGaN blue LEDs enable full-color mixing with existing red and green LEDs based on AlInGaP and GaP alloys respectively, promoting the progress of so...

  3. Discontinuous Inter-Granular Separations (DIGS) in the Gas Nitride Layer of ISS Race Rings

    Science.gov (United States)

    Figert, John; Dasgupta, Rajib; Martinez, James

    2010-01-01

    The starboard solar alpha rotary joint (SARJ) race ring on the International space station (ISS) failed due to severe spalling of the outer diameter, 45 degree (outer canted) nitrided surface. Subsequent analysis at NASA-KSC revealed that almost all of the debris generated due to the failure was nitrided 15-5 stainless steel. Subsequent analysis of the nitride control coupons (NCC) at NASA-JSC revealed the presence of discontinuous inter-granular separations (DIGS) in the gas nitride layer. These DIGS were present in the inter-granular networking located in the top 2 mils of the nitride layer. The manufacturer's specification requires the maximum white structure to be 0.0003 inches and intergranular networking below the allowable white structure depth to be cause for rejection; a requirement that the NCCs did not meet. Subsequent testing and analysis revealed that lower DIGS content significantly lowered the probability of nitride spalling in simulated, dry condition runs. One batch of nitride samples with DIGS content similar to the port SARJ (did not fail on orbit) which exhibited almost no nitride spalling after being run on one test rig. Another batch of nitride samples with DIGS content levels similar to the starboard SARJ exhibited significant nitride spalling on the same test rig with the same load under dry conditions. Although DIGS were not the root cause of starboard race ring failure, testing indicates that increased DIGS reduced the robustness of the gas nitride layer under dry operating conditions.

  4. ZeroFlow - new, environmentally friendly method of controlled gas nitriding used for selected car parts

    Science.gov (United States)

    Kowalska, J.; Małdziński, L.

    2016-09-01

    This article presents new method of controlled gas nitriding called ZeroFlow, which is used for nitriding of selected car parts, such as crankshafts, camshafts, piston rings, poppet valve springs and discs, piston pins or nozzles for unit injectors. This article will discuss the essence of controlled gas nitriding process, with an emphasis on the influence of process parameters on results of nitriding process. This information are the basis to understand the issue of the kinetics of nitrided layer growth, and as it follows - for its practical application in designing, regulation and control of nitriding processes using simulation models (simulator of the kinetics of nitrided layer growth). This article will also present the simulator of the kinetics of nitrided layer growth, which supports nitriding using ZeroFlow method - through the use of simulator layers are obtained in the shortest possible time, which is connected with the lowest energy consumption; therefore, nitriding process using ZeroFlow method and simulator of the kinetics of nitrided layer growth is both economical and environmentally friendly.

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

    Science.gov (United States)

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

    2015-11-18

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

  6. Nitriding of Fe–Cr–Al alloys: nitride precipitation and phase transformations

    OpenAIRE

    Clauß, Arno Rainer

    2008-01-01

    Nitriding of the ternary iron-based alloy Fe–1.5wt.%Cr–1.5wt.%Al (i.e. Fe–1.6at.%Cr–3.1at.%Al) leads to the precipitation of mixed, cubic, rock-salt structure type Cr1-xAlxN precipitates. These precipitates are not in thermodynamic equilibrium, which would involve precipitation of cubic, rock-salt structure type CrN and hexagonal, wurtzite structure type AlN. The mixed, cubic, rock-salt structure type Cr1-xAlxN precipitates develop because diffusion of Cr and Al in ferrite, as compared to dif...

  7. Development of Simplified Atmospheric-Pressure Plasma Nitriding

    Science.gov (United States)

    Yamamoto, Hirofumi; Ichiki, Ryuta; Maeda, Akihide; Yamanouchi, Kenta; Akamine, Shuichi; Kanazawa, Seiji; Oita University Team

    2015-09-01

    Nitriding treatment is one of the surface hardening technologies, applied to dies and automobile components. In recent industry, low-pressure nitriding treatment using vacuum system is mainstream. On the other hand, we have originally developed an atmospheric-pressure plasma nitriding which do not need vacuum system. However we needed an air-tight container to purge residual oxygen and external heater to control treatment temperature. To make this technique practical, we addressed to construct a simplified treatment system, where treatment temperature is controlled by thermal plasma itself and oxygen purging is achieved by a simple cover. This means that any air-tight container and external heater is not necessary. As a result, surface temperature is controlled by changing treatment gap from nozzle tip to steel surface. We succeeded in controlling well thickness of hardened layer by adjusting treatment temperature even in such a simplified system. In the conference, we also discuss experimental results for hardening complex shaped materials by using our simplified nitriding.

  8. Thermionic field emission in gold nitride Schottky nanodiodes

    Science.gov (United States)

    Spyropoulos-Antonakakis, N.; Sarantopoulou, E.; Kollia, Z.; Samardžija, Z.; Kobe, S.; Cefalas, A. C.

    2012-11-01

    We report on the thermionic field emission and charge transport properties of gold nitride nanodomains grown by pulsed laser deposition with a molecular fluorine laser at 157 nm. The nanodomains are sandwiched between the metallic tip of a conductive atomic force microscope and a thin gold layer forming thus a metal-semiconductor-metal junction. Although the limited existing data in the literature indicate that gold nitride was synthesized previously with low efficiency, poor stability, and metallic character; in this work, it is shown that gold nitride nanodomains exhibit semiconducting behavior and the metal-semiconductor-metal contact can be modeled with the back-to-back Schottky barrier model. From the experimental I-V curves, the main charge carrier transport process is found to be thermionic field emission via electron tunneling. The rectifying, near symmetric and asymmetric current response of nanocontacts is related to the effective contact area of the gold nitride nanodomains with the metals. A lower limit for the majority charge carriers concentration at the boundaries of nanodomains is also established using the full depletion approximation, as nanodomains with thickness as low as 6 nm were found to be conductive. Current rectification and charge memory effects are also observed in "quite small" conductive nanodomains (6-10 nm) due to stored charges. Indeed, charges near the surface are identified as inversion domains in the phase shift mapping performed with electrostatic force microscopy and are attributed to charge trapping at the boundaries of the nanodomains.

  9. Second-harmonic generation in substoichiometric silicon nitride layers

    Science.gov (United States)

    Pecora, Emanuele; Capretti, Antonio; Miano, Giovanni; Dal Negro, Luca

    2013-03-01

    Harmonic generation in optical circuits offers the possibility to integrate wavelength converters, light amplifiers, lasers, and multiple optical signal processing devices with electronic components. Bulk silicon has a negligible second-order nonlinear optical susceptibility owing to its crystal centrosymmetry. Silicon nitride has its place in the microelectronic industry as an insulator and chemical barrier. In this work, we propose to take advantage of silicon excess in silicon nitride to increase the Second Harmonic Generation (SHG) efficiency. Thin films have been grown by reactive magnetron sputtering and their nonlinear optical properties have been studied by femtosecond pumping over a wide range of excitation wavelengths, silicon nitride stoichiometry and thermal processes. We demonstrate SHG in the visible range (375 - 450 nm) using a tunable 150 fs Ti:sapphire laser, and we optimize the SH emission at a silicon excess of 46 at.% demonstrating a maximum SHG efficiency of 4x10-6 in optimized films. Polarization properties, generation efficiency, and the second order nonlinear optical susceptibility are measured for all the investigated samples and discussed in terms of an effective theoretical model. Our findings show that the large nonlinear optical response demonstrated in optimized Si-rich silicon nitride materials can be utilized for the engineering of nonlinear optical functions and devices on a Si chip.

  10. Gallium Nitride MMICs for mm-Wave Power Operation

    NARCIS (Netherlands)

    Quay, R.; Maroldt, S.; Haupt, C.; Heijningen, M. van; Tessmann, A.

    2009-01-01

    In this paper a Gallium Nitride MMIC technology for high-power amplifiers between 27 GHz and 101 GHz based on 150 nm- and 100 nm-gate technologies is presented. The GaN HEMT MMICs are designed using coplanar waveguide transmission-line-technology on 3-inch semi-insulating SiC substrates. The measure

  11. BORON NITRIDE CAPACITORS FOR ADVANCED POWER ELECTRONIC DEVICES

    Energy Technology Data Exchange (ETDEWEB)

    N. Badi; D. Starikov; C. Boney; A. Bensaoula; D. Johnstone

    2010-11-01

    This project fabricates long-life boron nitride/boron oxynitride thin film -based capacitors for advanced SiC power electronics with a broad operating temperature range using a physical vapor deposition (PVD) technique. The use of vapor deposition provides for precise control and quality material formation.

  12. Dispersion engineering silicon nitride waveguides for broadband nonlinear frequency conversion

    NARCIS (Netherlands)

    Epping, J.P.

    2015-01-01

    In this thesis, we investigated nonlinear frequency conversion of optical wavelengths using integrated silicon nitride (Si3N4) waveguides. Two nonlinear conversion schemes were considered: seeded four-wave mixing and supercontinuum generation. The first—seeded four-wave mixing—is investigated by a n

  13. Bond length variation in hydronitride molecules and nitride crystals

    Science.gov (United States)

    Buterakos, L. A.; Gibbs, G. V.; Boisen, M. B.

    1992-08-01

    Bond lengths calculated for the coordination polyhedra in hydronitride molecules match average values observed for XN bonds involving main group X-cations in nitride crystals to within ˜0.04 Å. As suggested for oxide and sulfide molecules and crystals, the forces that determine the average bond lengths recorded for coordinated polyhedra in hydronitride molecules and nitride crystals appear to be governed in large part by the atoms that comprise the polyhedra and those that induce local charge balance. The forces exerted on the coordinated polyhedra by other parts of the structure seem to play a small if not an insignificant role in governing bond length variations. Bonded radii for the nitride ion obtained from theoretical electron density maps calculated for the molecules increase linearly with bond length as observed for nitride crystals with the rock salt structure. Promolecule radii calculated for the molecules correlate with bonded and ionic radii, indicating that the electron density distributions in hydronitride molecules possess a significant atomic component, despite bond type.

  14. Single-layer graphene on silicon nitride micromembrane resonators

    DEFF Research Database (Denmark)

    Schmid, Silvan; Bagci, Tolga; Zeuthen, Emil;

    2014-01-01

    Due to their low mass, high quality factor, and good optical properties, silicon nitride (SiN) micromembrane resonators are widely used in force and mass sensing applications, particularly in optomechanics. The metallization of such membranes would enable an electronic integration with the prospect...

  15. Nitride RCLEDs grown by MBE for POF applications

    Energy Technology Data Exchange (ETDEWEB)

    Calle, F.; Naranjo, F.B.; Fernandez, S.; Sanchez-Garcia, M.A.; Calleja, E.; Munoz, E. [ISOM and Departamento de Ingenieria Electronica, ETSI de Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria, 28040 Madrid (Spain)

    2002-08-16

    Data links by means of plastic optical fibres (POF) demand efficient light emitting diodes (LEDs) at 510 nm, the most promising candidate being nitride-based resonant-cavity LEDs (RCLEDs). These devices include InGaN/GaN multiple-quantum-well (MQW) structures, and GaN/AlGaN distributed Bragg reflectors. Molecular beam epitaxy (MBE) offers some advantages for the fabrication of nitride RCLEDs, like high In incorporation in the active region, and control of the interface quality in the mirror. The main steps in the development of nitride-based RCLEDs using radio-frequency plasma-assisted MBE are addressed, with emphasis in a) p-type doping of GaN by MBE; b) the optimisation of growth, the design and characterisation of AlGaN/GaN stacks for a reflector in the micro-cavity; and c) the growth of InGaN layers, InGaN/GaN MQWs, and conventional InGaN LEDs, which are studied by structural, electrical and optical techniques. The design and fabrication of nitride RCLEDs, which satisfy spectral and thermal specifications for POF applications, are finally described. (Abstract Copyright[2002], Wiley Periodicals, Inc.)

  16. Crystallographic phases and magnetic properties of iron nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guo-Ke [Department of Physics, Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050024 (China); Department of Mathematics and Physics, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China); Liu, Yan; Zhao, Rui-Bin [Department of Physics, Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050024 (China); Shen, Jun-Jie [Department of Mathematics and Physics, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China); Wang, Shang; Shan, Pu-Jia; Zhen, Cong-Mian [Department of Physics, Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050024 (China); Hou, Deng-Lu, E-mail: houdenglu@mail.hebtu.edu.cn [Department of Physics, Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050024 (China)

    2015-08-31

    Iron nitride films, including single phase films of α-FeN (expanded bcc Fe), γ′-Fe{sub 4}N, ε-Fe{sub 3−x}N (0 ≤ x ≤ 1), and γ″-FeN, were sputtered onto AlN buffered glass substrates. It was found possible to control the phases in the films merely by changing the nitrogen partial pressure during deposition. The magnetization decreased with increased nitrogen concentration and dropped to zero when the N:Fe ratio was above 0.5. The experimental results, along with spin polarized band calculations, have been used to discuss and analyze the magnetic properties of iron nitrides. It has been demonstrated that in addition to influencing the lattice constant of the various iron nitrides, the nearest N atoms have a significant influence on the exchange splitting of the Fe atoms. Due to the hybridization of Fe-3d and N-2p states, the magnetic moment of Fe atoms decreases with an increase in the number of nearest neighbor nitrogen atoms. - Highlights: • Single phase γ′-Fe{sub 4}N, ε-Fe{sub 3−x}N, and γ″-FeN films were obtained using dc sputtering. • The phases in iron nitride films can be controlled by the nitrogen partial pressure. • The nearest N neighbors have a significant influence on the exchange splitting of Fe.

  17. Atomistic models of hydrogenated amorphous silicon nitride from first principles

    NARCIS (Netherlands)

    Jarolimek, K.; De Groot, R.A.; De Wijs, G.A.; Zeman, M.

    2010-01-01

    We present a theoretical study of hydrogenated amorphous silicon nitride (a-SiNx:H), with equal concentrations of Si and N atoms (x=1), for two considerably different densities (2.0 and 3.0 g/cm3). Densities and hydrogen concentration were chosen according to experimental data. Using first-principle

  18. Atomistic models of hydrogenated amorphous silicon nitride from first principles

    NARCIS (Netherlands)

    Jarolimek, K.; Groot, R.A. de; Wijs, G.A. de; Zeman, M.

    2010-01-01

    We present a theoretical study of hydrogenated amorphous silicon nitride (a-SiNx:H), with equal concentrations of Si and N atoms (x=1), for two considerably different densities (2.0 and 3.0 g/cm3). Densities and hydrogen concentration were chosen according to experimental data. Using first-principle

  19. The design, fabrication, and testing of corrugated silicon nitride diaphragms

    NARCIS (Netherlands)

    Scheeper, Patrick R.; Olthuis, Wouter; Bergveld, Piet

    1994-01-01

    Silicon nitride corrugated diaphragms of 2 mm×2 mm×1 ¿m have been fabricated with 8 circular corrugations, having depths of 4, 10, or 14 ¿m. The diaphragms with 4-¿m-deep corrugations show a measured mechanical sensitivity (increase in the deflection over the increase in the applied pressure) which

  20. Synthesis of Boron Nitride Nanotubes for Engineering Applications

    Science.gov (United States)

    Hurst, Janet; Hull, David; Gorican, Dan

    2005-01-01

    Boron Nitride nanotubes (BNNT) are of interest to the scientific and technical communities for many of the same reasons that carbon nanotubes (CNT) have attracted large amounts of attention. Both materials have potentially unique and significant properties which may have important structural and electronic applications in the future. However of even more interest than their similarities may be the differences between carbon and boron nanotubes. Whilt boron nitride nanotubes possess a very high modulus similaar to CNT, they are also more chemically and thermally inert. Additionally BNNT possess more uniform electronic properties, having a uniform band gap of approximately 5.5 eV while CNT vary from semi-conductin to conductor behavior. Boron Nitride nanotubes have been synthesized by a variety of methods such as chemical vapor deposition, arc discharge and reactive milling. Consistently producing a reliable product has proven difficult. Progress in synthesis of 1-2 gram sized batches of Boron Nitride nanotubes will be discussed as well as potential uses for this unique material.

  1. On production of niobium nitrides from steam and gas mixture

    International Nuclear Information System (INIS)

    The results of investigation of the process of high-pure niobium nitride production via reduction of niobium pentachloride by hydrogen in nitrogen presence are presented. Two types of units were used: one with heating of base by direct current transmission and other with high frequency heating of base by VChG-1/0.44 generator

  2. Microstructural evolution during nitriding, finite element simulation and experimental assessment

    Energy Technology Data Exchange (ETDEWEB)

    Hassani-Gangaraj, S.M. [Politecnico di Milano, Dipartimento di Meccanica, Via La Masa, 1, 20156 Milano (Italy); Guagliano, M., E-mail: mario.guagliano@polimi.it [Politecnico di Milano, Dipartimento di Meccanica, Via La Masa, 1, 20156 Milano (Italy)

    2013-04-15

    A finite element simulation of nitriding is proposed in this paper, using the analogy between diffusion and heat conduction, to overcome the shortcomings of the classical internal oxidation model in predicting the kinetics of layer growth and nitrogen distribution during nitriding. To verify the model, a typical gas nitriding has been carried out on an axisymmetric specimen. Treated specimen has been characterized using optical microscopy (OM), scanning electron microscopy (SEM), micro-hardness and X-Ray diffraction (XRD) measurements. It was found that the so-called diffusion zone can be divided into two parts with different influence on the mechanical characteristics including residual stress and hardening. First layer which is a two phase region of ferritic matrix and γ′ (Fe{sub 4}N) makes further improvement with respect to the second layer which is a solid solution of nitrogen in ferrite. The formation of that two phase region, which is not predicted by classical model, can be efficiently recognized by the proposed model. It is also proved that the model has the ability to consider the geometry dependency of layer growth and formation in nitriding.

  3. Size effects in band gap bowing in nitride semiconducting alloys

    DEFF Research Database (Denmark)

    Gorczyca, I.; Suski, T.; Christensen, Niels Egede;

    2011-01-01

    Chemical and size contributions to the band gap bowing of nitride semiconducting alloys (InxGa1-xN, InxAl1-xN, and AlxGa1-xN) are analyzed. It is shown that the band gap deformation potentials of the binary constituents determine the gap bowing in the ternary alloys. The particularly large gap...

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

    Directory of Open Access Journals (Sweden)

    Meziani Samir

    2016-06-01

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

  5. Proportional control valves integrated in silicon nitride surface channel technology

    NARCIS (Netherlands)

    Groen, Maarten S.; Groenesteijn, Jarno; Meutstege, Esken; Brookhuis, Robert A.; Brouwer, Dannis M.; Lötters, Joost C.; Wiegerink, Remco J.

    2015-01-01

    We have designed and realized two types of proportional microcontrol valves in a silicon nitride surface channel technology process. This enables on-die integration of flow controllers with other surface channel devices, such as pressure sensors or thermal or Coriolis-based (mass) flow sensors, to o

  6. Methods for improved growth of group III nitride buffer layers

    Science.gov (United States)

    Melnik, Yurity; Chen, Lu; Kojiri, Hidehiro

    2014-07-15

    Methods are disclosed for growing high crystal quality group III-nitride epitaxial layers with advanced multiple buffer layer techniques. In an embodiment, a method includes forming group III-nitride buffer layers that contain aluminum on suitable substrate in a processing chamber of a hydride vapor phase epitaxy processing system. A hydrogen halide or halogen gas is flowing into the growth zone during deposition of buffer layers to suppress homogeneous particle formation. Some combinations of low temperature buffers that contain aluminum (e.g., AlN, AlGaN) and high temperature buffers that contain aluminum (e.g., AlN, AlGaN) may be used to improve crystal quality and morphology of subsequently grown group III-nitride epitaxial layers. The buffer may be deposited on the substrate, or on the surface of another buffer. The additional buffer layers may be added as interlayers in group III-nitride layers (e.g., GaN, AlGaN, AlN).

  7. Boron nitride elastic and thermal properties. Irradiation effects

    International Nuclear Information System (INIS)

    The anisotropy of boron nitride (BN) and especially thermal and elastic properties were studied. Specific heat and thermal conductivity between 1.2 and 300K, thermal conductivity between 4 and 350K and elastic constants C33 and C44 were measured. BN was irradiated with electrons at 77K and with neutrons at 27K to determine properties after irradiation

  8. Bone tissue response to plasma-nitrided titanium implant surfaces

    Directory of Open Access Journals (Sweden)

    Emanuela Prado FERRAZ

    2015-02-01

    Full Text Available A current goal of dental implant research is the development of titanium (Ti surfaces to improve osseointegration. Plasma nitriding treatments generate surfaces that favor osteoblast differentiation, a key event to the process of osteogenesis. Based on this, it is possible to hypothesize that plasma-nitrided Ti implants may positively impact osseointegration. Objective The aim of this study was to evaluate the in vivo bone response to Ti surfaces modified by plasma-nitriding treatments. Material and Methods Surface treatments consisted of 20% N2 and 80% H2, 450°C and 1.5 mbar during 1 h for planar and 3 h for hollow cathode. Untreated surface was used as control. Ten implants of each surface were placed into rabbit tibiae and 6 weeks post-implantation they were harvested for histological and histomorphometric analyses. Results Bone formation was observed in contact with all implants without statistically significant differences among the evaluated surfaces in terms of bone-to-implant contact, bone area between threads, and bone area within the mirror area. Conclusion Our results indicate that plasma nitriding treatments generate Ti implants that induce similar bone response to the untreated ones. Thus, as these treatments improve the physico-chemical properties of Ti without affecting its biocompatibility, they could be combined with modifications that favor bone formation in order to develop new implant surfaces.

  9. Development of compound layer during nitriding and nitrocarburising

    DEFF Research Database (Denmark)

    Somers, Marcel A. J.

    2010-01-01

    The development of the compound layer during gaseous nitriding and nitrocarburising of Fe-based material is described. The first nucleation of the compound layer at the surface depends on the competition between dissociation of ammonia and the removal nitrogen from the surface by solid state...

  10. Quantum Cavity Optomechanics with Phononic Bandgap Shielded Silicon Nitride Membranes

    DEFF Research Database (Denmark)

    Nielsen, William Hvidtfelt Padkær

    .In this work, we report on the progress of bringing a cavity optomechanicalsystem “up to speed” for the later integration into a hybrid atomic-opticalmechanicalentanglement experiment. The optomechanical system in considerationconsists of a highly stressed stoichiometric silicon-nitride membrane placedbetween...

  11. MEASUREMENT OF THERMAL DIFFUSIVITY OF REACTION BONDED SILICON NITRIDE

    OpenAIRE

    Serra, J.-J.; Jaymes, M.; Cantarel, M.

    1986-01-01

    The thermal diffusivity of samples of reaction bonded silicon nitride from different sources, was measured using the ETCA solar furnace. Two measurement methods, suitable for use with this type of equipment, allowed the different material origins to be determined. This installation accepts relatively large samples which are therefore representative of the bulk material.

  12. Continuous Fiber Ceramic Composite (CFCC) Program: Gaseous Nitridation

    Energy Technology Data Exchange (ETDEWEB)

    R. Suplinskas G. DiBona; W. Grant

    2001-10-29

    Textron has developed a mature process for the fabrication of continuous fiber ceramic composite (CFCC) tubes for application in the aluminum processing and casting industry. The major milestones in this project are System Composition; Matrix Formulation; Preform Fabrication; Nitridation; Material Characterization; Component Evaluation

  13. MEMS Aluminum Nitride Technology for Inertial Sensors

    Science.gov (United States)

    Vigevani, Gabriele

    2011-12-01

    The design and fabrication of MEMS Inertial Sensors (both accelerometers and gyroscopes) made of Aluminum Nitride (AlN) is described in this dissertation. The goal of this work is to design and fabricate inertial sensors based on c-axis oriented AlN polycrystalline thin films. AlN is a post-CMOS compatible piezoelectric material widely used for acoustic resonators, such Bulk Acoustic Wave (BAW) and Lamb Wave Resonators (LWR). In this work we develop the design techniques necessary to obtain inertial sensors with AlN thin film technology. Being able to use AlN as structural material for both acoustic wave resonator and sensing elements is key to achieve the three level integration of RF-MEMS components, sensing elements and CMOS in the same chip. Using AlN as integration platform is particularly suitable for large consumer emerging markets where production costs are the major factor that determine a product success. In order to achieve a platform integration, the first part of this work focuses on the fabrication process: starting from the fabrication technology used for LWR devices, this work shows that by slightly modifying some of the fabrication steps it is possible to obtain MEMS accelerometers and gyroscopes with the same structural layers used for LWR. In the second part of this work, an extensive analysis, performed with analytical and Finite Element Models (FEM), is developed for beam and ring based structures. These models are of great importance as they provide tools to understand the physics of lateral piezoelectric beam actuation and the major limitations of this technology. Based on the models developed for beam based resonators, we propose two designs for Double Ended Tuning Fork (DETF) based accelerometers. In the last part of the dissertation, we show the experimental results and the measurements performed on actual devices. As this work shows analytically and experimentally, there are some fundamental constraints that limit the ultimate sensitivity

  14. Grain refinement by boron nitride; Gefuegemodifizierung durch Bornitrid

    Energy Technology Data Exchange (ETDEWEB)

    Bach, F.W.; Guenther, A.; Phan-Tan, T.; Kruessel, T.; Wilk, P. [Institut fuer Werkstoffkunde der Universitaet Hannover, Struktur- und Biomedizinwerkstoffe, Garbsen (Germany)

    2005-01-01

    Grain refinement of magnesium alloys aims at better deformation behaviour, higher strength and improved corrosion resistance. Besides mechanical treatment like pressing, it is possible to refine the grainsize by using nucleation materials. Whereas calcium and rare earth elements are already widely used, the use of boron nitride offers a cheap alternative to refine grains of magnesium aluminum alloys. The effect is achieved by the reaction of boron nitride with aluminum which cracks the chemical compound to form aluminum nitride with the nitrogen while boron is forming different magnesium borides. These two compounds both exhibit very high melting points and are stable in this environment so that they can act as seed crystals. Because boron nitride shows a bad wettability to metal molds, it would float on top of the mold. Therefore, it is necessary to produce pellets out of boron nitride and aluminum powder to improve contact to the mold and enhance reaction velocity. (Abstract Copyright [2005], Wiley Periodicals, Inc.) [German] Durch die Kornfeinung von Magnesiumlegierungen wird das Ziel einer Festigkeitssteigerung, einer verbesserten Umformbarkeit und einer erhoehten Korrosionsbestaendigkeit verfolgt. Neben mechanischen Loesungswegen (Strangpressen etc.) besteht die Moeglichkeit legierungstechnisch durch den Einsatz keimbildender Stoffe eine Kornfeinung zu erzielen. Neben dem Einsatz von Kalzium oder Seltenen Erden bietet Bornitrid eine kostenguenstige Moeglichkeit eine Kornfeinung fuer aluminiumhaltige Magnesiumlegierungen zu erzeugen. Die Kornfeinung beruht dabei auf der Reaktion des Bornitrids mit dem Aluminium in der Schmelze, durch welche das Bornitrid zersetzt wird und mit dem freiwerdenden Stickstoff zu Aluminiumnitrid reagiert, waehrend sich das Bor mit Magnesium zu Magnesiumboriden verbindet. Bei beiden Produkten handelt es sich um hochschmelzende, in dieser Umgebung stabile Verbindungen, die als Kristallisationskeime wirken koennen. Die Zugabe des

  15. Ionic nitriding of high chromium martensitic stainless steels

    International Nuclear Information System (INIS)

    Martensitic stainless steels are used in industrial applications where resistance to corrosion and mechanical resistance are needed simultaneously. These steels are normally used in tempering and annealing condition which gives them hardnesses of 500 and 600 HV (about 54 HRC). Ionic nitriding is an assisted diffusion technique that has recently been successfully applied to harden austenitic stainless steels without reducing their resistance to corrosion. The application with AISI 420 martensitic steels has not given good results yet, because in most cases, it affects their corrosion resistance. This work presents the results of the pulsed nitriding of martensitic steels with a higher chrome content, such as the M340 and M333 Boehler steels and they are compared with the same materials after tempering and annealing, without nitriding. The influence of the variations in the parameters of the process, such as the percentage of active time in the pulsed wave, partial nitrogen pressure, current density and effective tension in the microstructure, hardness and wear and corrosion resistance was studied. The microstructure was studied with an optic microscope; the wear resistance with abrasion tests following ASTM G-65 and corrosion with 100 hour long saline haze tests, in a device built according to ASTM B117. Hardness was found to rise to values of 1000 to 1350 HV in all the steels after ionic nitriding, the modified layers oscillated from 3 to 15 microns. As a result, wear resistance also increased, with differences depending on the microstructure and the thickness of the modified layer. However, corrosion resistance was not good, except in the case of the M333 steel test piece with less hardness and a less thick nitrided layer without a noticeable interphase (au)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-01

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

  17. Wear and isothermal oxidation kinetics of nitrided TiAl based alloys

    Institute of Scientific and Technical Information of China (English)

    赵斌; 吴建生; 孙坚

    2002-01-01

    Gas nitridation of TiAl based alloys in an ammonia atmosphere was c arried out. The evaluation of the surface wear resistance was performed to compare with those of the non-nitrided alloys. It is concluded that high temperature nitridation raised wear resistance of TiAl based alloys markedly. The tribol ogical behaviors of the nitrided alloys were also discussed. The oxidation kinetics of the nitrided TiAl based alloys were investigated at 800~1000 ℃ in hot air. It is concluded that nitridation is detrimental to the oxidation resistance of TiAl based alloys under the present conditions. The nitrided alloys exhibit increased oxidizing rate with the prolongation of nitridation time at 800 ℃. However, alloys nitrided at 940 ℃ for 50 hdisplay a sign of better oxidat ion resistance than the other nitrided alloys at more severe oxidizing conditions. The parabolic rate law is considered as the basis of the data processing and interpretation of the mass gainvs time data. As a comparison with it, attempts were made to fit the data with the power law. The oxidation kinetic parameter kn, kp and n were measured and the trends were discussed.

  18. Structure and properties of nitrided surface layer produced on NiTi shape memory alloy by low temperature plasma nitriding

    Science.gov (United States)

    Czarnowska, Elżbieta; Borowski, Tomasz; Sowińska, Agnieszka; Lelątko, Józef; Oleksiak, Justyna; Kamiński, Janusz; Tarnowski, Michał; Wierzchoń, Tadeusz

    2015-04-01

    NiTi shape memory alloys are used for bone and cardiological implants. However, on account of the metallosis effect, i.e. the release of the alloy elements into surrounding tissues, they are subjected to various surface treatment processes in order to improve their corrosion resistance and biocompatibility without influencing the required shape memory properties. In this paper, the microstructure, topography and morphology of TiN surface layer on NiTi alloy, and corrosion resistance, both before and after nitriding in low-temperature plasma at 290 °C, are presented. Examinations with the use of the potentiodynamic and electrochemical impedance spectroscopy methods were carried out and show an increase of corrosion resistance in Ringer's solution after glow-discharge nitriding. This surface titanium nitride layer also improved the adhesion of platelets and the proliferation of osteoblasts, which was investigated in in vitro experiments with human cells. Experimental data revealed that nitriding NiTi shape memory alloy under low-temperature plasma improves its properties for bone implant applications.

  19. Aluminum Nitride Formation From Aluminum Oxide/Phenol Resin Solid-Gel Mixture By Carbothermal Reduction Nitridation Method

    Directory of Open Access Journals (Sweden)

    Mylinh Dang Thy

    2015-06-01

    Full Text Available Hexagonal and cubic crystalline aluminum nitride (AlN particles were successfully synthesized using phenol resin and alpha aluminum oxide (α-Al2O3 as precursors through new solid-gel mixture and carbothermal reduction nitridaton (CRN process with molar ratio of C/Al2O3 = 3. The effect of reaction temperature on the decomposition of phenol resin and synthesis of hexagonal and cubic AlN were investigated and the reaction mechanism was also discussed. The results showed that α-Al2O3 powder in homogeneous solid-gel precursor was easily nitrided to yield AlN powder during the carbothermal reduction nitridation process. The reaction temperature needed for a complete conversion for the precursor was about 1700°C, which much lower than that when using α-Al2O3 and carbon black as starting materials. To our knowledge, phenol resin is the first time to be used for synthesizing AlN powder via carbothermal reduction and nitridation method, which would be an efficient, economical, cheap assistant reagent for large scale synthesis of AlN powder.

  20. Reprocessing of spent nitride fuel by chemical dissolution in molten salt: Results on plutonium nitride containing inert matrix materials

    International Nuclear Information System (INIS)

    Solid solutions of actinide mono-nitrides have been proposed as a candidate fuel of the accelerator-driven system (ADS) for transmutation of minor actinides (MA). The pyrochemical process has several advantages over the wet process such as PUREX in the case of treating spent nitride fuel with large decay heat and fast neutron emission, and recovering highly enriched 15N. In the present study, the chemical dissolution of PuN, (PuxZr1-x)N and PuN+TiN, with CdCl2 in LiCl-KCl eutectic melt were investigated to confirm the possibility of the chemical dissolution process of spent nitride fuel. The plutonium nitrides, PuN, (PuxZr1-x)N and PuN+TiN, were dissolved by the reaction with CdCl2 in LiCl- KCl eutectic melt at 823 K and most of Pu was recovered into the molten salt. On the other hand, most of ZrN and TiN were not dissolved and remained as undissolved residues. (authors)

  1. Synthesis of high purity gallium nitride powders and growth and characterization of aluminum nitride and gallium nitride bulk single crystals

    Science.gov (United States)

    Balkas, Cengiz Mustafa

    Single crystalline platelets of aluminum nitride (AlN) ≤ 1 mm thick have been grown within the range 1950-2250sp°C on silicon carbide (SiC) substrates via sublimation-recondensation in a resistively heated graphite furnace. The source material was sintered AlN. A maximum growth rate of 500 mum/hr was achieved at 2150sp°C and a source-to-seed separation of 4 mm. Crystals grown at high temperatures ranged in color from blue to green due to the incorporation of Si and C from the SiC substrates; those grown at lower temperatures were colorless and transparent. Secondary-ion mass spectroscopy (SIMS) results showed approximately a two order of magnitude decrease in the concentrations of these two impurities in the transparent crystals. X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy studies revealed low densities of line and planar defects and a strain free material. The synthesis of high purity, single phase GaN powders was accomplished in a hot wall tube furnace via (1) the reaction of Ga(l) with ammonia (NHsb3) and (2) the conversion of Gasb2Osb3(s). Polyhedra of various shapes were obtained from both processes; some rod-shaped crystals were also observed in the material derived from Gasb2Osb3. The GaN powders produced via the first route were characterized via XRD technique. The diffraction data revealed the material to be single phase with a = 3.1891 A, c = 5.1855 A, in space group P6sb3mc, Z = 2 and Dsb{x} = 6.0886 gr/cmsp3. Scanning electron microscopy revealed a particle size distribution in the ground material between 1 and 5 mum with most of the particles being {≈}1{mu}m. The data obtained in this study was chosen to be the new standard for the powder diffraction pattern for this material by the International Center for Diffraction Data. Single crystals of GaN up to 3 mm in length were grown by sublimation of pellets of this material under an NHsb3 flow. Typical green densities were 50 to 60% of theoretical density

  2. Microscopic investigation of pitting corrosion in plasma nitrided austenitic stainless steel; Mikroskopische Untersuchung von Lochkorrosion an plasmanitriertem austenitischem rostfreiem Stahl

    Energy Technology Data Exchange (ETDEWEB)

    Escalada, Lisandro; Simison, Silvia N. [Univ. of Mar del Plata (Argentina). Faculty of Engineering; Bruehl, Sonia P. [National Univ. of Technology, Concepcion del Uruguay (Argentina). Surface Engineering Group

    2014-10-01

    UNS 31603 austenitic stainless steel was nitrided using different techniques, and pitting corrosion resistance was analysed in a chloride solution. All nitriding techniques, LEII, PI. and convectional DC nitriding produced a nitrided layer called S phase which is corrosion resistant. Pits morphology and layer structure was investigated using optical and electronic microscopy, SEM-FIB, EDS, and a 3D reconstruction of a pit was assessed using FIB tomography. It was concluded that pits are initiated in MnS inclusions and a channel was generated passing through the nitrided layer, connecting the steel with the electrolyte. Base alloy dissolution was observed beneath the nitrided layer.

  3. Nitriding treatment of reduced activation ferritic steel as functional layer for liquid breeder blanket

    International Nuclear Information System (INIS)

    The development of functional layers such as a tritium permeation barrier and an anti-corrosion layer is the essential technology for the development of a molten salt type self cooled fusion blanket. In the present study, the characteristics of a nitriding treatment on a reduced activation ferritic steel, JLF-1 (Fe-9Cr-2W-0.1C) as the functional layer were investigated. The steel surface was nitrided by an ion nitriding treatment or a radical nitriding treatment. The nitridation characteristic of the steel surface was made clear based on the thermodynamic stability. The thermal diffusivity, the hydrogen permeability and the chemical stability in the molten salt Flinak were investigated. The results indicated that the nitriding treatment can improve the compatibility in the Flinak without the decrease of the thermal diffusivity, though there was little improvement as the hydrogen permeation barrier. (author)

  4. Effect of Nitridation on Morphology, Structural Properties and Stress of A1N Films

    Institute of Scientific and Technical Information of China (English)

    HU Wei-Guo; JIAO Chun-Mei; WEI Hong-Yuan; ZHANG Pan-Feng; KANG Wing-Ting; ZHANG Ri-Qing; LIU Xiang-Lin

    2008-01-01

    @@ We investigate effects of nitridation on A1N morphology, structural properties and stress.It is found that 3 min nitridation can prominently improve A1N crystal structure, and slightly smooth the surface morphology.However, 10min nitridation degrades out-of-plane crystal structure and surface morphology instead.Additionally, 3-min nitridation introduces more tensile stress (1.5 GPa) in A1N films, which can be attributed to the weaker islands 2D coalescent.Nitridation for 10 rain can introduce more defects, or even forms polycrystallinity interlayer, which relaxes the stress.Thus, the stress in A1N with 10 min nitridation decreases to -0.2 GPa compressive stress.

  5. Reaction Mechanism of O‘—sialon—ZrO2 Composite by Using Reaction Nitridation Mathod

    Institute of Scientific and Technical Information of China (English)

    LIHongxia; JIBaokun; 等

    1997-01-01

    O'-sialon-ZrO2 composite based on the cheap commercial available zircon and silicon as raw materials can be achieved by using reac-tion nitridation method,More attention was given to the nitriding process and the effect of additives on it .The experimental results show that there are two nitridation paths:one is the direct nitridation of silicon powder and the other is through the reaction between the medi-um compound ZrSi2 and the nitrogen.The effects of addition of calcia and the incorpora-tion of BN on the nitriding reaction were also investigated,the primitive experimental results demonstrated that both of calcia and BN could deteriorate the nitriding degree.

  6. NITROGEN POTENTIAL DURING ION NITRIDING PROCESS IN GLOW-DISCHARGE PLASMA

    Directory of Open Access Journals (Sweden)

    A. A. Kozlov

    2015-01-01

    Full Text Available The paper considers problems on regulation of phase composition of a nitrided layer during gas and ion nitriding process in a glow-discharge. It has been established that  available models for control of nitrided layer structure with the help of nitriding index (nitrogen potential can not be applied for nitriding process in the glow-discharge. Principal difference of the ion nitriding from the gas one is in the fact that chemically active nitrogen is formed in the discharge zone (cathode layer and its mass-transfer is carried out in the form of an active particle flow (ions, atoms, molecules which directed to the metal surface.Interrelation of chemical discharge activity with such characteristics of nitriding steel as nitrogen solubility in  α-solid solution and  coefficient diffusion during ion nitriding in low-discharge plasma. It has been shown that regulation of the nitride layer structure during ion nitriding is reached due to changes in nitrogen flow density in plasma. While supporting the flow at the level of nitrogen solubility in  one phase or another (α, γ′  it is possible to obtain the nitrided layer consisting only of α-solid solution or γ′-nitride layer and diffusion sub-layer. Moreover a specific range of nitrogen flow density values exists for every steel grade where it is possible to ensure a limiting nitrogen concentration in α-solid solution and the γ′-layer characterized by low diffusion  mobility is not formed on the surface.

  7. Laser Nitrided and TiN Coated Ti-6Al-4V Alloy surfaces

    OpenAIRE

    Al-Mana , Omar

    2011-01-01

    Titanium alloys are widely used in aerospace industry due to their low density and high toughness to mass ratios. However, the wear resistance of the titanium alloys is poor and requires surface treatment for the effective usage. One of the methods to improve the surface properties is to nitride the surface forming the nitride rich compounds in the surface region. Titanium nitrides provide the hard surfaces and improve the tribological properties of the surface. The gas assisted laser nitridi...

  8. Cathodic cage nitriding of AISI 409 ferritic stainless steel with the addition of CH4

    OpenAIRE

    Rômulo Ribeiro Magalhães de Sousa; Francisco Odolberto de Araújo; José Alzamir Pereira da Costa; Antonio Maia de Oliveira; Mineia Sampaio Melo; Clodomiro Alves Junior

    2012-01-01

    AISI 409 ferritic stainless steel samples were nitrided using the cathodic cage plasma nitriding technique (CCPN), with the addition of methane to reduce chromium precipitation, increase hardness and wear resistance and reduce the presence of nitrides when compared to plasma carbonitriding. Microhardness profiles and X-Ray analysis confirm the formation of a very hard layer containing mainly ε-Fe3N and expanded ferrite phases.

  9. On the effect of pre-oxidation on the kinetics of gaseous nitriding of iron

    DEFF Research Database (Denmark)

    Friehling, Peter B.; Somers, Marcel A.J.

    2000-01-01

    Preheating in an oxidising atmosphere is frequently used prior to gaseous nitriding. The effects of this preoxidation have been investigated and it is found that a preoxidation decrease the incubation time for the nucleation of iron nitrides. This results in a more homogeneous nucleation of iron...... nitrides, which leads to a more uniform thickness of the compound layer. A second effect is a thicker compound layer, which may stem from a higher surface concentration....

  10. Cathodic cage nitriding of AISI 409 ferritic stainless steel with the addition of CH4

    Directory of Open Access Journals (Sweden)

    Rômulo Ribeiro Magalhães de Sousa

    2012-04-01

    Full Text Available AISI 409 ferritic stainless steel samples were nitrided using the cathodic cage plasma nitriding technique (CCPN, with the addition of methane to reduce chromium precipitation, increase hardness and wear resistance and reduce the presence of nitrides when compared to plasma carbonitriding. Microhardness profiles and X-Ray analysis confirm the formation of a very hard layer containing mainly ε-Fe3N and expanded ferrite phases.

  11. Research on Abrasives in the Chemical Mechanical Polishing Process for Silicon Nitride Balls

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Silicon nitride (Si 3N 4) has been the main material for balls in ceramic ball bearings, for its lower density, high strength, high hardness, fine thermal stability and anticorrosive, and is widely used in various fields, such as high speed and high temperature areojet engines, precision machine tools and chemical engineer machines. Silicon nitride ceramics is a kind of brittle and hard material that is difficult to machining. In the traditional finishing process of silicon nitride balls, balls are lapped...

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

    OpenAIRE

    Ghali, Saeed

    2014-01-01

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

  13. Elasticity and inelasticity of silicon nitride/boron nitride fibrous monoliths.

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, B. I.; Burenkov, Yu. A.; Kardashev, B. K.; Singh, D.; Goretta, K. C.; de Arellano-Lopez, A. R.; Energy Technology; Russian Academy of Sciences; Univer. de Sevilla

    2001-01-01

    A study is reported on the effect of temperature and elastic vibration amplitude on Young's modulus E and internal friction in Si{sub 3}N{sub 4} and BN ceramic samples and Si{sub 3}N{sub 4}/BN monoliths obtained by hot pressing of BN-coated Si{sub 3}N{sub 4} fibers. The fibers were arranged along, across, or both along and across the specimen axis. The E measurements were carried out under thermal cycling within the 20-600 C range. It was found that high-modulus silicon-nitride specimens possess a high thermal stability; the E(T) dependences obtained under heating and cooling coincide well with one another. The low-modulus BN ceramic exhibits a considerable hysteresis, thus indicating evolution of the defect structure under the action of thermoelastic (internal) stresses. Monoliths demonstrate a qualitatively similar behavior (with hysteresis). This behavior of the elastic modulus is possible under microplastic deformation initiated by internal stresses. The presence of microplastic shear in all the materials studied is supported by the character of the amplitude dependences of internal friction and the Young's modulus. The experimental data obtained are discussed in terms of a model in which the temperature dependences of the elastic modulus and their features are accounted for by both microplastic deformation and nonlinear lattice-atom vibrations, which depend on internal stresses.

  14. Preparation of high-pressure phase boron nitride films by physical vapor deposition

    CERN Document Server

    Zhu, P W; Zhao, Y N; Li, D M; Liu, H W; Zou Guang Tian

    2002-01-01

    The high-pressure phases boron nitride films together with cubic, wurtzic, and explosive high-pressure phases, were successfully deposited on the metal alloy substrates by tuned substrate radio frequency magnetron sputtering. The percentage of cubic boron nitride phase in the film was about 50% as calculated by Fourier transform infrared measurements. Infrared peak position of cubic boron nitride at 1006.3 cm sup - sup 1 , which is close to the stressless state, indicates that the film has very low internal stress. Transition electron microscope micrograph shows that pure cubic boron nitride phase exits on the surface of the film. The growth mechanism of the BN films was also discussed.

  15. Titanium nitride as a plasmonic material for visible and near-infrared wavelengths

    DEFF Research Database (Denmark)

    Naik, Gururaj V.; Schroeder, Jeremy L.; Ni, Xingjie;

    2012-01-01

    that titanium nitride could perform as an alternative plasmonic material in the visible and near-infrared regions. We demonstrate the excitation of surface-plasmon-polaritons on titanium nitride thin films and discuss the performance of various plasmonic and metamaterial structures with titanium nitride...... as the plasmonic component. We also show that titanium nitride could provide performance that is comparable to that of gold for plasmonic applications and can significantly outperform gold and silver for transformation-optics and some metamaterial applications in the visible and near-infrared regions....

  16. The denitridation of nitrides of iron, cobalt and rhenium under hydrogen

    OpenAIRE

    Alexander, A.-M.; Hargreaves, J.S.J.; Mitchell, C.

    2013-01-01

    The denitridation behaviour of binary iron, cobalt and rehnium nitrides under H2 /Ar has been investigated. The iron nitride was found to lose over 70 % of its as prepared nitrogen content at 400 °C. The cobalt nitride was completely denitrided at 250 °C. Rhenium nitride lost close to 90 % of its nitrogen at 350 °C. In addition, Co-Re4 prepared by ammonolyis was investigated, whilst only traces of NH3 were lost from this material under H2/Ar at 400 °C, with H2/N2 it proved to be an active amb...

  17. Evaluation of plasma nitriding efficiency of titanium alloys for medical applications

    Directory of Open Access Journals (Sweden)

    T. Frączek

    2009-04-01

    Full Text Available The surface layers obtained on selected titanium alloys, used in medicine, by the nitriding under glow discharge condition were investigated. The results concern of: α- titanium alloy Grade 2 and α + β alloys Grade 5 and Grade 5 ELI nitrided in temperature below 873 K. The nitriding experiments were performed in a current glow-discharge furnace JON-600 with assisting of unconventional methods. After nitriding surface layers were characterised by surface microhardness measurements, chemical depth profiles, microhardness depth profiles and wear resistance tests.

  18. Gas nitriding and subsequent oxidation of Ti-6Al-4V alloys

    OpenAIRE

    Lee, Dong Bok; Pohrelyuk, Iryna; Yaskiv, Oleh; Lee, Jae Chun

    2012-01-01

    Ti-6Al-4V alloys consisting of α-Ti grains and intergranular β-Ti islands were nitrided at 850°C for 1 to 12 h under a nitrogen pressure of 1 Pa. With increasing nitriding time, the Ti-N compound layer became thicker, and the α-Ti diffusion zone containing dissolved nitrogen became wider. In the Ti-N compound layer, the initially formed Ti2N became TiN as the nitriding progressed. The nitride layers were oxidized to rutile-TiO2 after oxidation at 700°C for 10 h in air.

  19. Tribology of nitriding layer, TiN coatings and their complex on AISI D2 steel

    Institute of Scientific and Technical Information of China (English)

    WANG Ke-sheng; ZHANG De-yuan; DONG Ding-fu

    2004-01-01

    The sliding wear and impact wear resistances of D2 steel with nitriding layer, PVD titanium nitride coating and their duplex treatment were investigated. The experimental results suggest that the duplex treatment has the best sliding and impact wear resistances under experimental conditions. And the wear resistance of PVD titanium nitride is better than that of nitriding. The impact wear resistance and wear mechanism of all three surface layers remain unchanged under impact load of 0.2 J or 1 J. All samples end with the same symptom of flaking.

  20. Influence of Plastic Deformation on Low Temperature Surface Hardening of Austenitic Stainless Steel by Gaseous Nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin;

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of two commercial austenitic stainless steels: AISI 304 and EN 1.4369. The materials were plastically deformed to different equivalent strains by uniaxial...... tension. Gaseous nitriding of the strained material was performed in ammonia gas at atmospheric pressure at 703 K. Microstructural characterization of the as-deformed states and the nitrided case produced included X-ray diffraction analysis, reflected light microscopy, microhardness testing. The results...... demonstrate that a case of expanded austenite develops and that, in particular, strain-induced martensite has a large influence on the nitrided zone....

  1. Explosion of lithium-thionyl-chloride battery due to presence of lithium nitride

    DEFF Research Database (Denmark)

    Hennesø, E.; Hedlund, Frank Huess

    2015-01-01

    with atmospheric nitrogen to produce lithium nitride. Nodules of lithium nitride were found to be present on the lithium foil in other cells of the accident batch. The investigation attributed the explosion to the formation of porous lithium nitride during intermediate storage and a violent exothermal...... decomposition with the SOCl2–LiAlCl4 electrolyte triggered by welding. The literature is silent on hazards of explosion of Li–SOCl2 cells associated with the presence of lithium nitride. The silence is intriguing. Possible causes may be that such explosions are very rare, that explosions go unpublished...

  2. On the effect of pre-oxidation on the nitriding kinetics

    DEFF Research Database (Denmark)

    Friehling, Peter Bernhard; Somers, Marcel A. J.

    2000-01-01

    The oxidation of ferritic surfaces prior to gaseous nitriding has been reported to lead to improved uniformity of the compound layer thickness and enhanced nitriding kinetics. The present work considers the nucleation and growth of a model compound layer on pure iron and, using previous...... experimental and theoretical work reported in the literature, puts forward two hypotheses to explain the effects of pre-oxidation on compound layer formation. It is proposed that the nucleation of iron nitrides is enhanced by the presence of an iron-oxide layer and that the growth of an iron-nitride layer...

  3. Scanning tunneling microscopy of initial nitridation processes on oxidized Si(100) surface with radical nitrogen

    CERN Document Server

    Takahashi, R; Ikeda, H; Sakashita, M; Sakai, A; Yasuda, Y; Nakatsuka, O; Zaima, S

    2003-01-01

    We have investigated the initial nitridation processes on oxidized Si(100) with radical nitrogen at a substrate temperature of 850degC using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). It is found that the thin oxide layer suppresses the changes of original Si step structures during nitridation, and this effect critically depends on the growth conditions of the oxide layer. Comparison of the nitride island morphology to the case of the clean surface suggests that the migration of the precursor during nitridation is suppressed by the oxygen in the layer. (author)

  4. Tunable Band Gap of Boron Nitride Interfaces under Uniaxial Pressure

    Science.gov (United States)

    Moraes, Elizane; Manhabosco, Taise; de Oliveira, Alan; Batista, Ronaldo

    2013-03-01

    In this work we show, by means of a density functional theory formalism, that the interaction between hydrogen terminated boron nitride surfaces gives rise to a metallic interface with free carries of opposite sign at each surface. A band gap can be induced by decreasing the surface separation. The size of the band gap changes continuously from zero up to 4.4 eV with decreasing separation, which is understood in terms of the interaction between surface states.Due to the high thermal conductivity of cubic boron nitride and the coupling between band gap and applied pressure, such tunable band gap interfaces may be used in high stable electronic and electromechanical devices. In addition, the spacial separation of charge carries at the interface may lead to photovoltaic applications. The authors thank tha brazilian agencies Fapemig, CNPq and Capes

  5. Formation and characterization of DNA microarrays at silicon nitride substrates.

    Science.gov (United States)

    Manning, Mary; Redmond, Gareth

    2005-01-01

    A versatile method for direct, covalent attachment of DNA microarrays at silicon nitride layers, previously deposited by chemical vapor deposition at silicon wafer substrates, is reported. Each microarray fabrication process step, from silicon nitride substrate deposition, surface cleaning, amino-silanation, and attachment of a homobifunctional cross-linking molecule to covalent immobilization of probe oligonucleotides, is defined, characterized, and optimized to yield consistent probe microarray quality, homogeneity, and probe-target hybridization performance. The developed microarray fabrication methodology provides excellent (high signal-to-background ratio) and reproducible responsivity to target oligonucleotide hybridization with a rugged chemical stability that permits exposure of arrays to stringent pre- and posthybridization wash conditions through many sustained cycles of reuse. Overall, the achieved performance features compare very favorably with those of more mature glass based microarrays. It is proposed that this DNA microarray fabrication strategy has the potential to provide a viable route toward the successful realization of future integrated DNA biochips.

  6. Theoretical treatment of nitriding and nitrocarburizing of iron

    Science.gov (United States)

    Du, Hong; Ågren, John

    1996-04-01

    Mathematical models are developed for both nitriding and nitrocarburizing of iron taking into account the diffusion of N or C and N through various phases and the thermodynamic properties of the ternary Fe-C-N system. Analytical solutions are obtained for the ɛ/γ' bilayer growth of the compound layer assuming constant diffusion coefficients, and the results are compared with those obtained from numerical simulations taking into account the concentration-dependent diffusivities. No significant difference was found between these two methods for nitriding of iron. For nitrocarburizing of iron, it was found that the off-diagonal diffusivities of the ɛ and γ' phases must be taken into account in the analytical solution in order to obtain reasonable results. In addition, it is shown that the phase constitution of the compound layer produced during nitrocarburizing of iron can be predicted by the numerical simulation.

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

    Directory of Open Access Journals (Sweden)

    B. Fényi

    2007-12-01

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

  8. Radio frequency plasma nitriding of aluminium at higher power levels

    International Nuclear Information System (INIS)

    Nitriding of aluminium 2011 using a radio frequency plasma at higher power levels (500 and 700 W) and lower substrate temperature (500 deg. C) resulted in higher AlN/Al2O3 ratios than obtained at 100 W and 575 deg. C. AlN/Al2O3 ratios derived from X-ray photoelectron spectroscopic analysis (and corroborated by heavy ion elastic recoil time of flight spectrometry) for treatments preformed at 100 (575 deg. C), 500 (500 deg. C) and 700 W (500 deg. C) were 1.0, 1.5 and 3.3, respectively. Scanning electron microscopy revealed that plasma nitrided surfaces obtained at higher power levels exhibited much finer nodular morphology than obtained at 100 W

  9. Valence electronic structure of tantalum carbide and nitride

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ The valence electronic structures of tantalum carbide (TaC) and tantalum nitride (TaN) are studied by using the empirical electronic theory (EET). The results reveal that the bonds of these compounds have covalent, metallic and ionic characters. For a quantitative analysis of the relative strength of these components, their ionicities have been calculated by implanting the results of EET to the PVL model. It has been found that the ionicity of tantalum carbide is smaller than that of tantalum nitride. The EET results also reveal that the covalent electronic number of the strongest bond in the former is larger than that of the latter. All these suggest that the covalent bond of TaC is stronger than that of TaN, which coincides to that deduced from the first-principles method.

  10. Optical stability of silicon nitride MIS inversion layer solar cells

    Science.gov (United States)

    Jaeger, K.; Hezel, R.

    1985-09-01

    For MIS inversion layer solar cells with silicon nitride as an AR coating, accelerated optical stress tests were performed. Degradation of the cell characteristics occurred which was found to be caused by photons with energies equal to or greater than 3.7 eV (wavelength of 335 nm or less). Generation of interface states at the silicon-insulator interface by UV light is shown to be the mechanism responsible. The original cell data could be completely restored by heat treatment (activation energy 0.5 eV) and partially by illumination with short-wavelength light. As the most striking result, however, it is demonstrated that the UV light-induced instability can be drastically improved by incorporation of cesium ions into the silicon nitride layer. An interpretation is given for this effect.

  11. Quantum oscillations of nitrogen atoms in uranium nitride

    Science.gov (United States)

    Aczel, A. A.; Granroth, G. E.; MacDougall, G. J.; Buyers, W. J. L.; Abernathy, D. L.; Samolyuk, G. D.; Stocks, G. M.; Nagler, S. E.

    2012-10-01

    The vibrational excitations of crystalline solids corresponding to acoustic or optic one-phonon modes appear as sharp features in measurements such as neutron spectroscopy. In contrast, many-phonon excitations generally produce a complicated, weak and featureless response. Here we present time-of-flight neutron scattering measurements for the binary solid uranium nitride, showing well-defined, equally spaced, high-energy vibrational modes in addition to the usual phonons. The spectrum is that of a single atom, isotropic quantum harmonic oscillator and characterizes independent motions of light nitrogen atoms, each found in an octahedral cage of heavy uranium atoms. This is an unexpected and beautiful experimental realization of one of the fundamental, exactly solvable problems in quantum mechanics. There are also practical implications, as the oscillator modes must be accounted for in the design of generation IV nuclear reactors that plan to use uranium nitride as a fuel.

  12. Investigations on the characterization of ion implanted hexagonal boron nitride

    Science.gov (United States)

    Aradi, E.; Naidoo, S. R.; Erasmus, R. M.; Julies, B.; Derry, T. E.

    2013-07-01

    The effect of ion implantation on hexagonal boron nitride (h-BN) is studied herein. We use boron as an ion of choice to introduce radiation damage into h-BN, at fluences ranging from 1 × 1014-1 × 1016 ions/cm2 and implantation energy ranges from 40 to 160 keV. The thermal dependence is also investigated by varying the annealing temperature from room temperature to 400 °C after implantation. Raman spectroscopy showed Raman active defects one of which is possibly related to the formation of cubic boron nitride nanocrystals (nc-BN) within the implanted range. The relationship of these defect induced Raman active peaks was investigated by varying the implantation parameters. The preliminary Transmission Electron Microscopy (TEM) results also are reported briefly.

  13. Double Sided Si(Ge)/Sapphire/III-Nitride Hybrid Structure

    Science.gov (United States)

    Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor)

    2016-01-01

    One aspect of the present invention is a double sided hybrid crystal structure including a trigonal Sapphire wafer containing a (0001) C-plane and having front and rear sides. The Sapphire wafer is substantially transparent to light in the visible and infrared spectra, and also provides insulation with respect to electromagnetic radio frequency noise. A layer of crystalline Si material having a cubic diamond structure aligned with the cubic direction on the (0001) C-plane and strained as rhombohedron to thereby enable continuous integration of a selected (SiGe) device onto the rear side of the Sapphire wafer. The double sided hybrid crystal structure further includes an integrated III-Nitride crystalline layer on the front side of the Sapphire wafer that enables continuous integration of a selected III-Nitride device on the front side of the Sapphire wafer.

  14. Silicon Nitride: A Synthetic Mineral for Vertebrate Biology

    Science.gov (United States)

    Pezzotti, Giuseppe; McEntire, Bryan J.; Bock, Ryan; Boffelli, Marco; Zhu, Wenliang; Vitale, Eleonora; Puppulin, Leonardo; Adachi, Tetsuya; Yamamoto, Toshiro; Kanamura, Narisato; Bal, B. Sonny

    2016-08-01

    The remarkable stoichiometric flexibility of hydroxyapatite (HAp) enables the formation of a variety of charged structural sites at the material’s surface which facilitates bone remodeling due to binding of biomolecule moieties in zwitterionic fashion. In this paper, we report for the first time that an optimized biomedical grade silicon nitride (Si3N4) demonstrated cell adhesion and improved osteoconductivity comparable to highly defective, non-stoichiometric natural hydroxyapatite. Si3N4’s zwitterionic-like behavior is a function of the dualism between positive and negative charged off-stoichiometric sites (i.e., N-vacancies versus silanols groups, respectively). Lattice defects at the biomaterial’s surface greatly promote interaction with positively- and negatively-charged functional groups in biomolecules, and result in the biologically effective characteristics of silicon nitride. These findings are anticipated to be a starting point for further discoveries of therapeutic bone-graft substitute materials.

  15. Silicon Nitride Waveguides for Plasmon Optical Trapping and Sensing Applications

    CERN Document Server

    Zhao, Qiancheng; Huang, Yuewang; Capolino, Filippo; Boyraz, Ozdal

    2015-01-01

    We demonstrate a silicon nitride trench waveguide deposited with bowtie antennas for plasmonic enhanced optical trapping. The sub-micron silicon nitride trench waveguides were fabricated with conventional optical lithography in a low cost manner. The waveguides embrace not only low propagation loss and high nonlinearity, but also the inborn merits of combining micro-fluidic channel and waveguide together. Analyte contained in the trapezoidal trench channel can interact with the evanescent field from the waveguide beneath. The evanescent field can be further enhanced by plasmonic nanostructures. With the help of gold nano bowtie antennas, the studied waveguide shows outstanding trapping capability on 10 nm polystyrene nanoparticles. We show that the bowtie antennas can lead to 60-fold enhancement of electric field in the antenna gap. The optical trapping force on a nanoparticle is boosted by three orders of magnitude. A strong tendency shows the nanoparticle is likely to move to the high field strength region,...

  16. Preferential orientation in metal nitride deposited by the UBM system

    Directory of Open Access Journals (Sweden)

    Jhon Jairo Olaya

    2010-05-01

    Full Text Available This work was aimed at studying the influence of ion bombardment on the preferred orientation (OP of transition metal nitrides (TMN produced by the reactive sputtering technique with a variable unbalanced magnetron through permanent magnets. Tita- nium nitride (TiN coatings were thus studied by varying two parameters: ion-atom ratio on the substrate (Ji/Ja and nitrogen flux. Deposition conditions were as follows: 7 mTorr working pressure, ~ 380ºC substrate temperature, 2 and 8.5 sccm nitrogen flux and 245-265 discharge power. The results showed that preferred orientation (111 and the crystalline behaviour of the produced coatings depended more on nitrogen flux than on ion bombardment. Similarly, micro-hardness measured on films deposited on steel AISI-M2 substrates increased from 1600 to 2000 HV0.025 when nitrogen flux was increased.

  17. Magnetism induced by electrochemical nitriding on an austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Takashi Watanabe

    2015-04-01

    Full Text Available The surface of a Fe-Ni-Cr Alloy (SUS316L plate was electrochemically nitrided in molten LiF-KF salt including Li3N at 873K. The crystal structure changed from fcc structure to bct structure with nitrogen introduction. The Nitrogen diffusion layers were predominately formed at nitrogen concentration of 23 at%. The nitriding process drastically also changed its magnetic property from non-magnetic to ferromagnetic. The magnetic field of 20 kOe saturated the magnetic moment with its magnetization of 81 emu/g at 10K. The anisotropic magnetization is ascertained. Based on CrN formation and Cr extraction from the original Fe-Ni-Cr system, the induced ferromagnetism was discussed.

  18. Valence electronic structure of tantalum carbide and nitride

    Institute of Scientific and Technical Information of China (English)

    FAN; ChangZeng

    2007-01-01

    The valence electronic structures of tantalum carbide (TaC) and tantalum nitride (TaN) are studied by using the empirical electronic theory (EET). The results reveal that the bonds of these compounds have covalent, metallic and ionic characters. For a quantitative analysis of the relative strength of these components, their ionicities have been calculated by implanting the results of EET to the PVL model. It has been found that the ionicity of tantalum carbide is smaller than that of tantalum nitride. The EET results also reveal that the covalent electronic number of the strongest bond in the former is larger than that of the latter. All these suggest that the covalent bond of TaC is stronger than that of TaN, which coincides to that deduced from the first-principles method.……

  19. A new interlayer potential for hexagonal boron nitride

    Science.gov (United States)

    Akıner, Tolga; Mason, Jeremy K.; Ertürk, Hakan

    2016-09-01

    A new interlayer potential is developed for interlayer interactions of hexagonal boron nitride sheets, and its performance is compared with other potentials in the literature using molecular dynamics simulations. The proposed potential contains Coulombic and Lennard-Jones 6–12 terms, and is calibrated with recent experimental data including the hexagonal boron nitride interlayer distance and elastic constants. The potentials are evaluated by comparing the experimental and simulated values of interlayer distance, density, elastic constants, and thermal conductivity using non-equilibrium molecular dynamics. The proposed potential is found to be in reasonable agreement with experiments, and improves on earlier potentials in several respects. Simulated thermal conductivity values as a function of the number of layers and of temperature suggest that the proposed LJ 6–12 potential has the ability to predict some phonon behaviour during heat transport in the out-of-plane direction.

  20. Point defects in thorium nitride: A first-principles study

    Science.gov (United States)

    Pérez Daroca, D.; Llois, A. M.; Mosca, H. O.

    2016-11-01

    Thorium and its compounds (carbides and nitrides) are being investigated as possible materials to be used as nuclear fuels for Generation-IV reactors. As a first step in the research of these materials under irradiation, we study the formation energies and stability of point defects in thorium nitride by means of first-principles calculations within the framework of density functional theory. We focus on vacancies, interstitials, Frenkel pairs and Schottky defects. We found that N and Th vacancies have almost the same formation energy and that the most energetically favorable defects of all studied in this work are N interstitials. These kind of results for ThN, to the best authors' knowledge, have not been obtained previously, neither experimentally, nor theoretically.

  1. Charge carrier transport properties in layer structured hexagonal boron nitride

    Science.gov (United States)

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

    2014-10-01

    Due to its large in-plane thermal conductivity, high temperature and chemical stability, large energy band gap (˜ 6.4 eV), hexagonal boron nitride (hBN) has emerged as an important material for applications in deep ultraviolet photonic devices. Among the members of the III-nitride material system, hBN is the least studied and understood. The study of the electrical transport properties of hBN is of utmost importance with a view to realizing practical device applications. Wafer-scale hBN epilayers have been successfully synthesized by metal organic chemical deposition and their electrical transport properties have been probed by variable temperature Hall effect measurements. The results demonstrate that undoped hBN is a semiconductor exhibiting weak p-type at high temperatures (> 700 °K). The measured acceptor energy level is about 0.68 eV above the valence band. In contrast to the electrical transport properties of traditional III-nitride wide bandgap semiconductors, the temperature dependence of the hole mobility in hBN can be described by the form of μ ∝ (T/T0)-α with α = 3.02, satisfying the two-dimensional (2D) carrier transport limit dominated by the polar optical phonon scattering. This behavior is a direct consequence of the fact that hBN is a layer structured material. The optical phonon energy deduced from the temperature dependence of the hole mobility is ħω = 192 meV (or 1546 cm-1), which is consistent with values previously obtained using other techniques. The present results extend our understanding of the charge carrier transport properties beyond the traditional III-nitride semiconductors.

  2. Charge carrier transport properties in layer structured hexagonal boron nitride

    Directory of Open Access Journals (Sweden)

    T. C. Doan

    2014-10-01

    Full Text Available Due to its large in-plane thermal conductivity, high temperature and chemical stability, large energy band gap (˜ 6.4 eV, hexagonal boron nitride (hBN has emerged as an important material for applications in deep ultraviolet photonic devices. Among the members of the III-nitride material system, hBN is the least studied and understood. The study of the electrical transport properties of hBN is of utmost importance with a view to realizing practical device applications. Wafer-scale hBN epilayers have been successfully synthesized by metal organic chemical deposition and their electrical transport properties have been probed by variable temperature Hall effect measurements. The results demonstrate that undoped hBN is a semiconductor exhibiting weak p-type at high temperatures (> 700 °K. The measured acceptor energy level is about 0.68 eV above the valence band. In contrast to the electrical transport properties of traditional III-nitride wide bandgap semiconductors, the temperature dependence of the hole mobility in hBN can be described by the form of μ ∝ (T/T0−α with α = 3.02, satisfying the two-dimensional (2D carrier transport limit dominated by the polar optical phonon scattering. This behavior is a direct consequence of the fact that hBN is a layer structured material. The optical phonon energy deduced from the temperature dependence of the hole mobility is ħω = 192 meV (or 1546 cm-1, which is consistent with values previously obtained using other techniques. The present results extend our understanding of the charge carrier transport properties beyond the traditional III-nitride semiconductors.

  3. Photoluminescence and Raman Spectroscopy Studies of Carbon Nitride Films

    OpenAIRE

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

    2016-01-01

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

  4. Observation of viscoelasticity in boron nitride nanosheet aerogel.

    Science.gov (United States)

    Zeng, Xiaoliang; Ye, Lei; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2015-07-14

    The viscoelasticity of boron nitride nanosheet (BNNS) aerogel has been observed and investigated. It is found that the BNNS aerogel has a high damping ratio (0.2), while it exhibits lightweight and negligible temperature dependence below 180 °C. The creep behavior of the BNNS aerogel markedly demonstrates its strain dependence on stress magnitude and temperature, and can be well simulated by the classical models.

  5. Method for forming monolayer graphene-boron nitride heterostructures

    Science.gov (United States)

    Sutter, Peter Werner; Sutter, Eli Anguelova

    2016-08-09

    A method for fabricating monolayer graphene-boron nitride heterostructures in a single atomically thin membrane that limits intermixing at boundaries between graphene and h-BN, so as to achieve atomically sharp interfaces between these materials. In one embodiment, the method comprises exposing a ruthenium substrate to ethylene, exposing the ruthenium substrate to oxygen after exposure to ethylene and exposing the ruthenium substrate to borazine after exposure to oxygen.

  6. Study of aluminum nitride precipitation in Fe- 3%Si steel

    OpenAIRE

    F.L. Alcântara; Barbosa, R; Cunha, M.A.

    2013-01-01

    For good performance of electrical steels it is necessary a high magnetic induction and a low power loss when submitted to cyclic magnetization. A fine dispersion of precipitates is a key requirement in the manufacturing process of Fe- 3%Si grain oriented electrical steel. In the production of high permeability grain oriented steel precipitate particles of copper and manganese sulphides and aluminium nitride delay normal grain growth during primary recrystallization, causing preferential grow...

  7. Silicon nitride gate dielectrics and bandgap engineering in graphene layers

    OpenAIRE

    Zhu, Wenjuan; Neumayer, Deborah; Perebeinos, Vasili; Avouris, Phaedon

    2010-01-01

    We show that silicon nitride can provide uniform coverage of graphene in field-effect transistors while preserving the channel mobility. This insulator allowed us to study the maximum channel resistance at the Dirac (neutrality) point as a function of the strength of a perpendicular electric field in top-gated devices with different numbers of graphene layers. Using a simple model to account for surface potential variations (electron-hole puddles) near the Dirac point we estimate the field-in...

  8. Deposition of carbon nitride films for space application

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

  9. Beryllium nitride thin film grown by reactive laser ablation

    OpenAIRE

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

    2001-01-01

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

  10. Phonon spectrum of single-walled boron nitride nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xiao Yang; Yan Xiao-Hong; Cao Jue-Xian; Mao Yu-Liang; Xiang Jun

    2004-01-01

    Based on a force constant model, we investigated the phonon spectrum and then specific heat of single-walled boron nitride nanotubes. The results show that the frequencies of Raman and infrared active modes decrease with increasing diameter in the low frequency, which is consistent with the results calculated by density functional theory.The fitting formulae for diameter and chirality dependence of specific heat at 300K are given.

  11. Effect of boron nitride coating on fiber-matrix interactions

    International Nuclear Information System (INIS)

    Coatings can modify fiber-matrix reactions and consequently interfacial bond strengths. Commercially available mullite, silicon carbide, and carbon fibers were coated with boron nitride via low pressure chemical vapor deposition and incorporated into a mullite matrix by hot-pressing. The influence of fiber-matrix interactions for uncoated fibers on fracture morphologies was studied. These observations are related to the measured values of interfacial shear strengths

  12. Polarity Control in Group-III Nitrides beyond Pragmatism

    Science.gov (United States)

    Mohn, Stefan; Stolyarchuk, Natalia; Markurt, Toni; Kirste, Ronny; Hoffmann, Marc P.; Collazo, Ramón; Courville, Aimeric; Di Felice, Rosa; Sitar, Zlatko; Vennéguès, Philippe; Albrecht, Martin

    2016-05-01

    Controlling the polarity of polar semiconductors on nonpolar substrates offers a wealth of device concepts in the form of heteropolar junctions. A key to realize such structures is an appropriate buffer-layer design that, in the past, has been developed by empiricism. GaN or ZnO on sapphire are prominent examples for that. Understanding the basic processes that mediate polarity, however, is still an unsolved problem. In this work, we study the structure of buffer layers for group-III nitrides on sapphire by transmission electron microscopy as an example. We show that it is the conversion of the sapphire surface into a rhombohedral aluminum-oxynitride layer that converts the initial N-polar surface to Al polarity. With the various AlxOyNz phases of the pseudobinary Al2O3 -AlN system and their tolerance against intrinsic defects, typical for oxides, a smooth transition between the octahedrally coordinated Al in the sapphire and the tetrahedrally coordinated Al in AlN becomes feasible. Based on these results, we discuss the consequences for achieving either polarity and shed light on widely applied concepts in the field of group-III nitrides like nitridation and low-temperature buffer layers.

  13. Tin Nitride as an Earth Abundant Photoanode for Water Splitting

    Science.gov (United States)

    Caskey, Christopher; Ma, Ming; Stephanovic, Vladan; Laney, Stephan; Ginley, David; Richards, Ryan; Smith, Wilson; Zakutayev, Andriy

    2014-03-01

    Photoelectrochemical (PEC) water splitting-the conversion of water to hydrogen and oxygen using light-is an attractive route to the chemical storage of solar energy. We demonstrate that spinel tin nitride (Sn3N4) has conduction and valence bands that straddle the redox potentials of water and we study it as a photoannode material. Sn3N4 thin films have been grown on glass at ambient temperature by reactive sputtering of tin in a nitrogen atmosphere. The resulting materials were n-type semiconductors. Carrier concentration, carrier mobility, work function, and optical properties were measured. Results indicate that tin nitride has a band gap of ~ 1.7 eV aligned around water's redox potentials. GW-corrected DFT-surface calculations that take into account water surface dipole interactions are consistent with experiment. Early PEC devices were made from Sn3N4 on fluorinated tin oxide with cobalt oxide catalysts and show a small but promising photoresponse (~ 0.1 mA/cm2 at 1.23 V vs. RHE) under AM 1.5 illumination in 0.1 M potassium phosphate (pH= 7.25). Further work will focus on increasing the photocurrent in tin nitride devices by increasing film quality and identifying the proper catalyst. This work is supported by the U.S. Department of Energy and the Netherlands Organization for Scientific Research (NWO), VENI scheme.

  14. Behaviour of nitriding layers for condition of small amplitude fretting

    Directory of Open Access Journals (Sweden)

    G.M. Drapak

    2007-01-01

    Full Text Available Purpose: It was explored fretting resistance titanic alloy VT3-1 (Ti-Al6-Cr2-Mo2,5 after low temperature ionicnitriding in unhydrogen environment.Design/methodology/approach: Small amplitude fretting was initiated by the dynamic contact of ball andflat in the regime of the partial slip on edge of spot of contact. A method differs by simplicity and expressdetermination of fretting resistance, namely areas of destruction by action of fretting for part nominally fixedcontact - how the functions of cycles of loading.Findings: As a result of fretting the central region of sticking decreasing, and the edge of areas of frettingare increasing.Practical implications: The method of initiation of small amplitude fretting within bounds of preliminarydisplacement is offered. On the offered method the destruction of titanic alloys is explored at fretting andinfluencing of ionic nitriding on fretting. By a computation method the work of forces of friction in the area ofwear, which in 5..6 times is less for nitriding titanic alloys, is appraised.Originality/value: A method allows defining reactionary power of nitriding layers for small amplitude fretting.

  15. Prospects of III-nitride optoelectronics grown on Si.

    Science.gov (United States)

    Zhu, D; Wallis, D J; Humphreys, C J

    2013-10-01

    The use of III-nitride-based light-emitting diodes (LEDs) is now widespread in applications such as indicator lamps, display panels, backlighting for liquid-crystal display TVs and computer screens, traffic lights, etc. To meet the huge market demand and lower the manufacturing cost, the LED industry is moving fast from 2 inch to 4 inch and recently to 6 inch wafer sizes. Although Al2O3 (sapphire) and SiC remain the dominant substrate materials for the epitaxy of nitride LEDs, the use of large Si substrates attracts great interest because Si wafers are readily available in large diameters at low cost. In addition, such wafers are compatible with existing processing lines for 6 inch and larger wafers commonly used in the electronics industry. During the last decade, much exciting progress has been achieved in improving the performance of GaN-on-Si devices. In this contribution, the status and prospects of III-nitride optoelectronics grown on Si substrates are reviewed. The issues involved in the growth of GaN-based LED structures on Si and possible solutions are outlined, together with a brief introduction to some novel in situ and ex situ monitoring/characterization tools, which are especially useful for the growth of GaN-on-Si structures. PMID:24088511

  16. Parameter Optimization of Nitriding Process Using Chemical Kinetics

    Science.gov (United States)

    Özdemir, İ. Bedii; Akar, Firat; Lippmann, Nils

    2016-09-01

    Using the dynamics of chemical kinetics, an investigation to search for an optimum condition for a gas nitriding process is performed over the solution space spanned by the initial temperature and gas composition of the furnace. For a two-component furnace atmosphere, the results are presented in temporal variations of gas concentrations and the nitrogen coverage on the surface. It seems that the exploitation of the nitriding kinetics can provide important feedback for setting the model-based control algorithms. The present work shows that when the nitrogen gas concentration is not allowed to exceed 6 pct, the Nad coverage can attain maximum values as high as 0.97. The time evolution of the Nad coverage also reveals that, as long as the temperature is above the value where nitrogen poisoning of the surface due to the low-temperature adsorption of excess nitrogen occurs, the initial ammonia content in the furnace atmosphere is much more important in the nitriding process than is the initial temperature.

  17. III-nitride semiconductors and their modern devices

    CERN Document Server

    2013-01-01

    This book is dedicated to GaN and its alloys AlGaInN (III-V nitrides), semiconductors with intrinsic properties well suited for visible and UV light emission and electronic devices working at high temperature, high frequency, and harsh environments. There has been a rapid growth in the industrial activity relating to GaN, with GaN now ranking at the second position (after Si) among all semiconductors. This is mainly thanks to LEDs, but also to the emergence of lasers and high power and high frequency electronics. GaN-related research activities are also diversifying, ranging from advanced optical sources and single electron devices to physical, chemical, and biological sensors, optical detectors, and energy converters. All recent developments of nitrides and of their technology are gathered here in a single volume, with chapters written by world leaders in the field. This third book of the series edited by B. Gil is complementary to the preceding two, and is expected to offer a modern vision of nitrides and...

  18. Hydrolysis of aluminum nitride powders in moist air

    International Nuclear Information System (INIS)

    High thermal conductivity is required for successful application of aluminum nitride (AlN) as a substrate material in electronic devices. AlN powders of low oxygen content are needed since oxygen contamination greatly reduces the thermal conductivity of AlN ceramics. High-purity AlN powders are commercially available, but can be contaminated by oxygen when contacting water/oxygen in powder processing after manufacturing. The present study investigates the hydrolysis properties of AlN powders in moist air at room temperature, so as to understand the degradation phenomena during powder handling in the normal atmospheric environment. The powders investigated were produced via three major commercial processes, namely, chemical vapor deposition from triethyl aluminum, carbothermal reduction and nitridation of alumina, and direct nitridation of aluminum. At the beginning of hydrolysis, an induction period is observed for each powder, which is attributed to slow hydrolysis of the surface oxide/oxyhydroxide layer. The length of this period is thus dependent on the composition and thickness of the surface layer, which is in turn affected by the manufacturing method. The AlN powder produced by the carbothermal process shows the longest induction period. The hydrolysis reaction produces initially amorphous AlOOH, which is further hydrolyzed to mixtures of bayerite, nordstrandite, and gibbsite, forming agglomerates around the unreacted AlN. Copyright (2003) AD-TECH - International Foundation for the Advancement of Technology Ltd

  19. Salt rejection and water transport through boron nitride nanotubes.

    Science.gov (United States)

    Hilder, Tamsyn A; Gordon, Daniel; Chung, Shin-Ho

    2009-10-01

    Nanotube-based water-purification devices have the potential to transform the field of desalination and demineralization through their ability to remove salts and heavy metals without significantly affecting the fast flow of water molecules. Boron nitride nanotubes have shown superior water flow properties compared to carbon nanotubes, and are thus expected to provide a more efficient water purification device. Using molecular dynamics simulations it is shown that a (5, 5) boron nitride nanotube embedded in a silicon nitride membrane can, in principle, obtain 100% salt rejection at concentrations as high as 1 M owing to a high energy barrier while still allowing water molecules to flow at a rate as high as 10.7 water molecules per nanosecond (or 0.9268 L m(-2) h(-1)). Furthermore, ions continue to be rejected under the influence of high hydrostatic pressures up to 612 MPa. When the nanotube radius is increased to 4.14 A the tube becomes cation-selective, and at 5.52 A the tube becomes anion-selective. PMID:19582727

  20. Tribological properties of boron nitride synthesized by ion beam deposition

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.; Spalvins, T.

    1985-01-01

    The adhesion and friction behavior of boron nitride films on 440 C bearing stainless steel substrates was examined. The thin films containing the boron nitride were synthesized using an ion beam extracted from a borazine plasma. Sliding friction experiments were conducted with BN in sliding contact with itself and various transition metals. It is indicated that the surfaces of atomically cleaned BN coating film contain a small amount of oxides and carbides, in addition to boron nitride. The coefficients of friction for the BN in contact with metals are related to the relative chemical activity of the metals. The more active the metal, the higher is the coefficient of friction. The adsorption of oxygen on clean metal and BN increases the shear strength of the metal - BN contact and increases the friction. The friction for BN-BN contact is a function of the shear strength of the elastic contacts. Clean BN surfaces exhibit relatively strong interfacial adhesion and high friction. The presence of adsorbates such as adventitious carbon contaminants on the BN surfaces reduces the shear strength of the contact area. In contrast, chemically adsorbed oxygen enhances the shear strength of the BN-BN contact and increases the friction.

  1. Stable Calcium Nitrides at Ambient and High Pressures.

    Science.gov (United States)

    Zhu, Shuangshuang; Peng, Feng; Liu, Hanyu; Majumdar, Arnab; Gao, Tao; Yao, Yansun

    2016-08-01

    The knowledge of stoichiometries of alkaline-earth metal nitrides, where nitrogen can exist in polynitrogen forms, is of significant interest for understanding nitrogen bonding and its applications in energy storage. For calcium nitrides, there were three known crystalline forms, CaN2, Ca2N, and Ca3N2, at ambient conditions. In the present study, we demonstrated that there are more stable forms of calcium nitrides than what is already known to exist at ambient and high pressures. Using a global structure searching method, we theoretically explored the phase diagram of CaNx and discovered a series of new compounds in this family. In particular, we found a new CaN phase that is thermodynamically stable at ambient conditions, which may be synthesized using CaN2 and Ca2N. Four other stoichiometries, namely, Ca2N3, CaN3, CaN4, and CaN5, were shown to be stable under high pressure. The predicted CaNx compounds contain a rich variety of polynitrogen forms ranging from small molecules (N2, N4, N5, and N6) to extended chains (N∞). Because of the large energy difference between the single and triple nitrogen bonds, dissociation of the CaNx crystals with polynitrogens is expected to be highly exothermic, making them as potential high-energy-density materials. PMID:27428707

  2. Field-effect transistors based on cubic indium nitride.

    Science.gov (United States)

    Oseki, Masaaki; Okubo, Kana; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

    2014-02-04

    Although the demand for high-speed telecommunications has increased in recent years, the performance of transistors fabricated with traditional semiconductors such as silicon, gallium arsenide, and gallium nitride have reached their physical performance limits. Therefore, new materials with high carrier velocities should be sought for the fabrication of next-generation, ultra-high-speed transistors. Indium nitride (InN) has attracted much attention for this purpose because of its high electron drift velocity under a high electric field. Thick InN films have been applied to the fabrication of field-effect transistors (FETs), but the performance of the thick InN transistors was discouraging, with no clear linear-saturation output characteristics and poor on/off current ratios. Here, we report the epitaxial deposition of ultrathin cubic InN on insulating oxide yttria-stabilized zirconia substrates and the first demonstration of ultrathin-InN-based FETs. The devices exhibit high on/off ratios and low off-current densities because of the high quality top and bottom interfaces between the ultrathin cubic InN and oxide insulators. This first demonstration of FETs using a ultrathin cubic indium nitride semiconductor will thus pave the way for the development of next-generation high-speed electronics.

  3. Development of new ferritic alloys reinforced by nano titanium nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Mathon, M.H., E-mail: marie-helene.mathon@cea.fr [Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Perrut, M., E-mail: mikael.perrut@onera.fr [Laboratoire Léon Brillouin, CEA-CNRS, CEA/Saclay, 91191 Gif-sur-Yvette (France); Poirier, L., E-mail: poirier@nitruvid.com [Bodycote France and Belgium, 9 r Jean Poulmarch, 95100 Argenteuil (France); Ratti, M., E-mail: mathieu.ratti@snecma.fr [CEA, DEN, Service de Recherches Métallurgiques Appliquées, F91191 Gif-sur-Yvette (France); Hervé, N., E-mail: nicolas.herve@cea.fr [CEA, DRT, LITEN, F38054 Grenoble (France); Carlan, Y. de, E-mail: yann.decarlan@cea.fr [CEA, DEN, Service de Recherches Métallurgiques Appliquées, F91191 Gif-sur-Yvette (France)

    2015-01-15

    Nano-reinforced steels are considered for future nuclear reactors or for application at high temperature like the heat exchangers tubes or plates. Oxide Dispersion Strengthened (ODS) alloys are the most known of the nano-reinforced alloys. They exhibit high creep strength as well as high resistance to radiation damage. This article deals with the development of new nano reinforced alloys called Nitride Dispersed Strengthened (NDS). Those are also considered for nuclear applications and could exhibit higher ductility with a simplest fabrication way. Two main fabrication routes were studied: the co-milling of Fe–18Cr1W0.008N and TiH{sub 2} powders and the plasma nitration at low temperature of a Fe–18Cr1W0.8Ti powder. The materials were studied mainly by Small Angle Neutron Scattering. The feasibility of the reinforcement by nano-nitride particles is demonstrated. The final size of the nitrides can be similar (few nanometers) to the nano-oxides observed in ODS alloys. The mechanical properties of the new NDS show an amazing ductility at high temperature for a nano-reinforced alloy.

  4. High-Frequency, Low-Noise Nitride-Based Power Transistors Grown on Bulk III-N Project

    Data.gov (United States)

    National Aeronautics and Space Administration — One of the main issues for III-nitride growth is the lack of a suitable native substrate. Growth on foreign substrates such as sapphire or SiC results in nitride...

  5. Deposition of chromium nitrides, oxy-nitrides and titanium carbides on steel substrates by DC magnetron sputtering

    International Nuclear Information System (INIS)

    The present paper deals with the deposition of chromium and titanium nitrides, oxynitrides, carbides and carbonitrides onto low carbon steel by reactive magnetron sputtering. The films were obtained by using different reactive gases (02, N2, CH4,). The process advancement and the corresponding film composition variations were investigated as a function of the specific reactivity of each gas. In addition, the cathode poisoning phenomena were studied. (author). 4 refs., 6 figs

  6. Wide-gap nitrides: from growth morphology to device behavior.

    Science.gov (United States)

    Buongiorno Nardelli, Marco

    1998-03-01

    With the aim to improve understanding of the basic mechanisms that underline growth and device behavior in nitride systems, we have carried out extensive ab initio theoretical investigations of surfaces and interfaces of wide-gap nitrides. The phenomena that we have studied include electronic and transport properties in nitride-based multiquantum wells, as influenced by band offsets and polarization-induced electric fields, and the effect of growth conditions on the surface morphology of the primary growth faces of GaN. Interface properties such as band offsets between the different epilayers in a heterojunction have a major impact on the carrier transport properties both along and across the interface. Since heterojunctions of the nitrides are lattice-mismatched, the band offset can be tuned by changing the substrate material, which introduces strain. The effects of the pyroelectric and piezoelectric fields naturally present in wurtzite nitrides have also been analyzed. They are strong enough to significantly reduce the interband recombination rate and intrinsically limit the lasing power of an ideal multiple quantum well blue laser. During the growth, the surface morphology of the substrate is important. On the Ga-terminated surface under Ga-rich (N-rich) conditions, a Ga-adatom (N-adatom) reconstruction is the most stable 2×2 reconstruction. A N atom near the N-terminated surface spontaneously forms an N2 molecule, which is weakly bound to a vacancy on the substrate. At the high temperatures under which growth takes place, this will result in N2 desorption and subsequent reconstructions. We have also investigated H and Mg adsorption on the (0001) surface. H stabilizes the ideally cleaved surface irrespective of polarity, and the surface states associated with its adsoption have been identified. Although Mg is the most important p-type dopant of GaN, its incorporation during MBE growth has been difficult. We discuss its incorporation and the behavior of

  7. Development of nitride-layer of AISI 304 austenitic stainless steel during high-temperature ammonia gas-nitriding

    International Nuclear Information System (INIS)

    Ammonia-gas nitriding of AISI 304 austenitic stainless steel was studied at temperatures higher than 800 deg. C using SEM and X-ray diffraction. The result showed that S-phase, an expanded austenite, was formed even at such high temperatures due to a high nitriding potential of ammonia gas. The equilibrium phase, CrN was formed through a decomposition of S-layer in two different modes; the one was through continuous precipitation of particles at the surface-side of S-layer due to a higher nitriding potential; the other through a discontinuous(-like) precipitation at the austenite interface-side, producing a fine lamellar structure of austenite and CrN. The γ-phase in the surface-side resulting from the precipitation of CrN particles subsequently transformed into Fe4N because of a fast enrichment of N atoms and a limited mobility of Cr atoms at the surface-side. A coarse lamellar structure made of austenite and Cr2N was developed in front of fine lamellae composed of austenite and CrN by the decomposition of supersaturated austenite through a discontinuous precipitation via grain boundary movement.

  8. Low-threshold indium gallium nitride quantum dot microcavity lasers

    Science.gov (United States)

    Woolf, Alexander J.

    Gallium nitride (GaN) microcavities with embedded optical emitters have long been sought after as visible light sources as well as platforms for cavity quantum electrodynamics (cavity QED) experiments. Specifically, materials containing indium gallium nitride (InGaN) quantum dots (QDs) offer an outstanding platform to study light matter interactions and realize practical devices, such as on-chip light emitting diodes and nanolasers. Inherent advantages of nitride-based microcavities include low surface recombination velocities, enhanced room-temperature performance (due to their high exciton binding energy, as high as 67 meV for InGaN QDs), and emission wavelengths in the blue region of the visible spectrum. In spite of these advantages, several challenges must be overcome in order to capitalize on the potential of this material system. Such diffculties include the processing of GaN into high-quality devices due to the chemical inertness of the material, low material quality as a result of strain-induced defects, reduced carrier recombination effciencies due to internal fields, and a lack of characterization of the InGaN QDs themselves due to the diffculty of their growth and therefore lack of development relative to other semiconductor QDs. In this thesis we seek to understand and address such issues by investigating the interaction of light coupled to InGaN QDs via a GaN microcavity resonator. Such coupling led us to the demonstration of the first InGaN QD microcavity laser, whose performance offers insights into the properties and current limitations of the nitride materials and their emitters. This work is organized into three main sections. Part I outlines the key advantages and challenges regarding indium gallium nitride (InGaN) emitters embedded within gallium nitride (GaN) optical microcavities. Previous work is also discussed which establishes context for the work presented here. Part II includes the fundamentals related to laser operation, including the

  9. High Temperature Characteristic in Electrical Breakdown and Electrical Conduction of Epoxy/Boron-nitride Composite

    Science.gov (United States)

    Takenaka, Yutaka; Kurimoto, Muneaki; Murakami, Yoshinobu; Nagao, Masayuki

    The power module for the electrical vehicle needs electrical insulation material with high thermal conductivity. Recently, the epoxy insulating material filled with boron-nitride particles (epoxy/boron-nitride composite) is focused as an effective solution. However, the insulation performance of epoxy/boron-nitride composite was not investigated enough especially at the high temperature in which the power module was used, i.e. more than 100°C. In this paper, we investigated high temperature characteristics in electrical breakdown and conduction current of epoxy/boron-nitride composite. Breakdown test under the application of DC lamp voltage and impulse voltage clarified that the epoxy/boron-nitride composite had the constant breakdown strength even in the high temperature. Comparison of the epoxy/boron-nitride composite with previous material, which was epoxy/alumina composite, indicated that the breakdown voltage of the epoxy/boron-nitride composite in the high temperature was found to be higher than that of epoxy/alumina composite under the same thermal-transfer quantity among them. Furthermore, conduction current measurement of epoxy/boron-nitride composite in the high temperature suggested the possibility of the ionic conduction mechanism.

  10. Study on nitridation processes of β-Ga2O3 single crystal

    Institute of Scientific and Technical Information of China (English)

    Xing Li; Changtai Xia; Xiaoli He; Guangqing Pei; Jungang Zhang; Jun Xu

    2008-01-01

    @@ Nitridated /3-Ga2Os (100) substrate was investigated as the substrate for CaN epitaxial growth.The effects of nitridation temperature and surface roughness of -Ga2O3 wafers on the formation of CaN were studied.

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

    Science.gov (United States)

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

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

    Institute of Scientific and Technical Information of China (English)

    Katerina ZAHARIEVA; Gheorghi VISSOKOV; Janis GRABIS; Slavcho RAKOVSKY

    2012-01-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

  14. Simulation of nitrogen concentration depth profiles in low temperature nitrided stainless steel

    DEFF Research Database (Denmark)

    Christiansen, Thomas; Dahl, Kristian Vinter; Somers, Marcel A. J.

    2006-01-01

    A numerical model is presented, which simulates nitrogen concentration-depth profiles as obtained with low temperature gaseous nitriding of stainless steel. The evolution of the calculated nitrogen concentration-depth profiles is compared with experimental nitriding kinetics. It is shown that the...

  15. Low noise high-Tc superconducting bolometers on silicon nitride membranes for far-infrared detection

    NARCIS (Netherlands)

    Nivelle, de M.J.M.E.; Bruijn, M.P.; Vries, de R.; Wijnbergen, J.J.; Korte, de P.A.J.; Sanchez, S.; Elwenspoek, M.; Heidenblut, T.; Schwierzi, B.; Michalke, W.; Steinbeiss, E.

    1997-01-01

    High-Tc GdBa2Cu3O7 – delta superconductor bolometers with operation temperatures near 89 K, large receiving areas of 0.95 mm2 and very high detectivity have been made. The bolometers are supported by 0.62 µm thick silicon nitride membranes. A specially developed silicon-on-nitride layer was used to

  16. Effect of nitriding treatment on corrosion behaviour of Co–Cr–Mo alloy in liquid Al

    International Nuclear Information System (INIS)

    Highlights: •Co–29Cr–6Mo alloy is nitrided in pure nitrogen. •Sample surface after nitriding is observed using transmission electron microscope. •Sample subsurface after nitriding is observed with electron backscatter diffraction. •Corrosion of nitrided samples in liquid Al is evaluated with immersion test. •Nitriding treatment is compared and discussed with oxidation treatment. -- Abstract: Effects of nitriding treatment on the corrosion behaviour of Co–29Cr–6Mo alloy in liquid Al were investigated. Because of the high solubility and high diffusion coefficient of nitrogen in Co, Cr2N and π phases formed from sample surface into alloy matrix during nitriding at 1273 K; however, the nitride layer was not continuously formed on sample surface even in a prolonged process. The Cr2N showed obviously higher resistance to liquid Al compared to alloy matrix, but owing to its discontinuous distribution, the formed Cr2N did not obviously improve the corrosion resistance of the alloy to liquid Al

  17. IMPROVEMENT OF MECHANICAL PROPERTIES OF MARTENSITIC STAINLESS STEEL BY PLASMA NITRIDING AT LOW TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    Y.T. Xi; D.X. Liu; D. Han; Z.F. Han

    2008-01-01

    A series of experiments were carried out to study the influence of low temperature plasma nitriding on the mechanical properties of AISI 420 martensitic stainless steel. Plasma nitriding ezperiments were carried out for 15 h at 350℃ by means of DC-pulsed plasma in 25%N2+ 75%H2 atmosphere. The microstructure, phase composition, and residual stresses profiles of the nitrided layers were determined by optical microscopy and X-ray diffraction. The microhardness profiles of the nitridied surfaces were also studied. The fatigue life, sliding wear, and erosion wear loss of the untreated specimens and plasma nitriding specimens were determined on the basks of a rotating bending fatigue tester, a ball-on-disc wear tester, and a solid particle erosion tester. The results show that the 350℃ nitrided surface is dominated by ε-Fe3N and αN, which is supersaturated nitrogen solid solution. They have high hardness and chemical stabilities. So the low temperature plasma nitriding not only increases the surface hardness values but also improves the wear and erosion resistance. In addition, the fatigue limit of AISI 420 steel can also be improved by plasma nitriding at 350℃ because plasma nitriding produces residual compressive stress inside the modified layer.

  18. Research on the magnetic material of Sm-Fe matrix nitrides

    Institute of Scientific and Technical Information of China (English)

    CUI Chunxiang; SUN Jibing; ZHANG Ying; WANG Ru; LI Lin; LIANG Zhimei

    2005-01-01

    In this paper, the types of Sm-Fe matrix compounds and their correlations are introduced, and progress of research on the magnetic materials of Sm-Fe matrix nitrides is also reviewed. Possible research trends of future permanent magnetic materials of SmFe matrix nitrides are briefly predicted.

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

    International Nuclear Information System (INIS)

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

  20. Preparation of uranium-plutonium mixed nitride pellets with high purity

    International Nuclear Information System (INIS)

    Uranium-plutonium mixed nitride pellets have been prepared in the gloveboxes with high purity Ar gas atmosphere. Carbothermic reduction of the oxides in N2-H2 mixed gas stream was adopted for synthesizing mixed nitride. Sintering was carried out in various conditions and the effect on the pellet characteristics was investigated. (author)

  1. Microstructure and Tribological Properties of Plasma Nitriding Cast CoCrMo Alloy

    Institute of Scientific and Technical Information of China (English)

    Qingliang Wang; Chuanhui Huan; Lei Zhang

    2012-01-01

    A medical cast CoCrMo alloy was coated by plasma nitriding process to enhance the wear resistance. The microstructures, phases and micro-hardness of nitrided layers were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and micro-hardness. Tribological prop- erties were investigated on a pin-on-disc wear tester under 25% bovine serum solutions. The experimental results showed that plasma nitriding was a promising process to produce thick, hard and wear resistant layers on the surface of CoCrMo alloy. The harder CrN and Cr2N phases formed on the plasma nitrided layer with the compact nano-crystalline structure. Compared with the untreated sample, all nitrided samples showed the lower wear rates and higher wear resistance at different applied loads and nitriding temperatures. It was concluded that the improvement of wear resistance could be ascribed to the formation of thicker and harder nitrided layers with the specific microstructures on nitrided surfaces.

  2. Nitrogen uptake and rate-limiting step in low-temperature nitriding of iron

    NARCIS (Netherlands)

    Inia, DK; Vredenberg, AM; Habraken, FHPM; Boerma, DO

    1999-01-01

    Recently, a method to nitride iron in NH3 ambients at low temperature (225-350 degrees C) has been developed. In this method, the Fe is covered with a thin (similar to 40 nm) Ni layer, which acts as a catalyst for the nitriding process. From experiments, in which the amount of nitrogen uptake is mea

  3. Thermodynamic Analysis for Carbothermal Reduction and Nitridation of TiO2

    Institute of Scientific and Technical Information of China (English)

    YU Renhong; JIANG Mingxue; SHI Xiaoqi

    2007-01-01

    The diagrams of stability relations ( namely, Predominance area phase diagram, PAPD ) of nitride , carbide and oxides in Ti-C-N-O system were plotted by thermodynamic calculation. The optimum conditions and main influence factors for the synthesis of titanium nitride and titanium carbide by carbothermal reduction in nitrogen atmosphere were discussed.

  4. The efficiency of ion nitriding of austenitic stainless steel 304 using the “active screen”

    Directory of Open Access Journals (Sweden)

    M. Ogórek

    2015-01-01

    Full Text Available The study examined layers were formed on the outer surface of austenitic stainless steel 304 under glow discharge conditions in the low-temperature and short-term ion nitriding. The outer layers analyzed in the work produced in parallel in the classical process of cathode and a novel method of “active screen”, intensifying the process of nitriding.

  5. Analytical and Experimental Evaluation of Joining Silicon Carbide to Silicon Carbide and Silicon Nitride to Silicon Nitride for Advanced Heat Engine Applications Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Sundberg, G.J.

    1994-01-01

    Techniques were developed to produce reliable silicon nitride to silicon nitride (NCX-5101) curved joins which were used to manufacture spin test specimens as a proof of concept to simulate parts such as a simple rotor. Specimens were machined from the curved joins to measure the following properties of the join interlayer: tensile strength, shear strength, 22 C flexure strength and 1370 C flexure strength. In parallel, extensive silicon nitride tensile creep evaluation of planar butt joins provided a sufficient data base to develop models with accurate predictive capability for different geometries. Analytical models applied satisfactorily to the silicon nitride joins were Norton's Law for creep strain, a modified Norton's Law internal variable model and the Monkman-Grant relationship for failure modeling. The Theta Projection method was less successful. Attempts were also made to develop planar butt joins of siliconized silicon carbide (NT230).

  6. Nitridation Behaviour,Microstructure and Proerties of Si—SiC Compostites Seeded with Morphologically Regulated β—Silicon Nitride Crystals

    Institute of Scientific and Technical Information of China (English)

    K.Amoako-Appiagyei; SooYoungLee; 等

    1999-01-01

    Nitridation of Si-SiC compacts ,containing β-Si3N4 single crystals as seed ,showed a higher yield of nitride with increase of the seed content,Samples containing seed with the largest aspect-ratio gave the best nitridation results.The evolution of the large epitaxially-grown grains,from the seed( as nucleus),during the subsequent liquid phase sintering process,gave ,rise to a bi-modal microstructure,The population of large grains was found to inrease with the volume of added seed.Samples containing 3 volume % exhibited the best mechanical properties,Fracture toughness of the sintered reaction bonded silicon nitride showed improvement in excess of 35% compared to the baselince Si3N4.

  7. Ultrathin high-temperature oxidation-resistant coatings of hexagonal boron nitride

    Science.gov (United States)

    Liu, Zheng; Gong, Yongji; Zhou, Wu; Ma, Lulu; Yu, Jingjiang; Idrobo, Juan Carlos; Jung, Jeil; MacDonald, Allan H.; Vajtai, Robert; Lou, Jun; Ajayan, Pulickel M.

    2013-10-01

    Hexagonal boron nitride is a two-dimensional layered material that can be stable at 1,500 °C in air and will not react with most chemicals. Here we demonstrate large-scale, ultrathin, oxidation-resistant coatings of high-quality hexagonal boron nitride layers with controlled thicknesses from double layers to bulk. We show that such ultrathin hexagonal boron nitride films are impervious to oxygen diffusion even at high temperatures and can serve as high-performance oxidation-resistant coatings for nickel up to 1,100 °C in oxidizing atmospheres. Furthermore, graphene layers coated with a few hexagonal boron nitride layers are also protected at similarly high temperatures. These hexagonal boron nitride atomic layer coatings, which can be synthesized via scalable chemical vapour deposition method down to only two layers, could be the thinnest coating ever shown to withstand such extreme environments and find applications as chemically stable high-temperature coatings.

  8. First stages of surface steel nitriding: X-ray photoelectron spectroscopy and electrical measurements

    Science.gov (United States)

    Flori, M.; Gruzza, B.; Bideux, L.; Monier, G.; Robert-Goumet, C.; Benamara, Z.

    2009-08-01

    Quantitative and qualitative analysis techniques were employed to study the first stages of ultra-high vacuum plasma nitriding of the 42CrMo4 steel. At constant treatment temperature, maintained for all samples at about 360 °C, we have established the influence of treatment time on the chemical composition, thickness and electrical properties of the nitrided layer. In this purpose it was used a stacking atomic layer model describing the sample surface, which takes into account the attenuation depth of photoelectrons by the atomic monolayers. So, we have found that after 2 h of nitriding in laboratory conditions, 70% of the nitrided layer was composed of iron oxide. Also, I- V measurements indicate an influence of the nitride overlayer with increasing treatment time.

  9. First stages of surface steel nitriding: X-ray photoelectron spectroscopy and electrical measurements

    Energy Technology Data Exchange (ETDEWEB)

    Flori, M., E-mail: flori.mihaela@fih.upt.ro [' Politehnica' University of Timisoara, Faculty of Engineering of Hunedoara, 331128 Hunedoara (Romania); Gruzza, B.; Bideux, L.; Monier, G.; Robert-Goumet, C. [LASMEA, UMR CNRS 6602, Blaise Pascal University, 63177 Aubiere Cedex (France); Benamara, Z. [Laboratoire de Microelectronique Appliquee, Sidi Bel Abbes University, 22000 Sidi Bel Abbes (Algeria)

    2009-08-30

    Quantitative and qualitative analysis techniques were employed to study the first stages of ultra-high vacuum plasma nitriding of the 42CrMo4 steel. At constant treatment temperature, maintained for all samples at about 360 deg. C, we have established the influence of treatment time on the chemical composition, thickness and electrical properties of the nitrided layer. In this purpose it was used a stacking atomic layer model describing the sample surface, which takes into account the attenuation depth of photoelectrons by the atomic monolayers. So, we have found that after 2 h of nitriding in laboratory conditions, 70% of the nitrided layer was composed of iron oxide. Also, I-V measurements indicate an influence of the nitride overlayer with increasing treatment time.

  10. Study on Nitride Fuel Fabrication Process and Irradiation Test Results in Japan

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Ho Jin; Song, Kee Chan; Lee, Jung Won; Kang, Kweon Ho; Jung, In Ha; Park, Chang Je; Lee, Jae Won; Lee, Young Woo

    2004-12-15

    Research on nitride fuels such as fabrication process and irradiation test proceeds actively in Japan by JAERI and JNC recently. To develop 'double strata' fuel cycle suggested by JAERI, fabrication of minor actinide containing nitride fuels and irradiation test in JOYO experimental fast reactor have been carried out for the development of future ADS target. Fabrication process and irradiation test on the nitride fuels in Japan is considered as the most advanced experimental achievement in the world. This state-of-the-art report summarizes research results of nitride fuels in Japan in order to obtain in-depth knowledge about fabrication process and in-pile behavior of nitride fuels.

  11. Nitriding of Hard Fe Electrodeposition and Its Effects on Wear Resistance

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nitriding is employed for the hard Fe electrodeposition toproduce a hard-facing and antiwear coating. It only takes 1 h for the hard Fe coating, which is much shorter than nitriding the Fe and steel. The results showed that the nitriding can increase the microhardness, wear resistance of the coating, as well as the bonding strength of the coating with the substrate. Additionally it can eliminate the brittleness, turn the internal stress of the coating from tension to compression.The wear resistance of the nitrided Fe coating is 4.6 times as high as that of Cr coating. It is simple and economic to combine hard Fe electroplating and nitriding, which is a good technology of the tribological surface modification.

  12. IMPROVING THE SURFACE PROPERTY OF TC4 ALLOY BY LASER NITRIDING AND ITS MECHANISM

    Institute of Scientific and Technical Information of China (English)

    Y.L. Yang; G.J. Zhao; D. Zhang; C.S. Liu

    2006-01-01

    The mixing technology of laser and heated nitrogen was applied to improve the surface hardaccelerate the nitriding process. Some interested samples were tested with XRD method (X-ray diffraction) to analyze the composition of nitrides, and the surface hardness of HV was measured.The results show that TiN and Ti2N were formed on the surface of Ti alloy with proper nitriding parameters, but TiN is the main composition. The surface hardness increased by three times, which sidered mainly of the activation of nitrogen by laser power and the pre-heated process which accelerated the nitriding process. The nitridation process can be considered as six steps given in detail. The result by analyzing the mechanism of improving the surface property of TiAl alloy shows the improvement of surface property due to two factors: the first reason is the result of laser annealing, and the second one is the formation of TiN.

  13. A model for unconventional glow discharge nitriding of grade 2 titanium

    Directory of Open Access Journals (Sweden)

    T. Frączek

    2013-01-01

    Full Text Available An analysis of the influence of different parameters of the ion nitriding process conducted in a H2 + N2 atmosphere on the properties of the surface layer of Grade 2 titanium was carried out in the study. This allowed a model for ion nitriding of technical titanium to be developed. The equipment used in the experimental work included a JON-600 current glow-discharge furnace. It was found that the process of cathode nitriding with the use of the active screen led to an increase in the concentration of nitrogen in the surface layer and in the relative volume of nitrides. A factor which determines the qualitative and quantitative characteristics of phenomena that occur in the presence of the active screen is the high concentration and high energy level of nitrogen ions which interact with base material during nitriding.

  14. Effect of plasma nitriding time on surface properties of hard chromium electroplated AISI 1010 steel

    Energy Technology Data Exchange (ETDEWEB)

    Kocabas, Mustafa [Yildiz Technical Univ., Istanbul (Turkey). Metallurgical and Materials Engineering Dept.; Danisman, Murat [Gedik Univ., Istanbul (Turkey). Electrical and Electronic Engineering Dept.; Cansever, Nurhan [Yildiz Technical Univ., Istanbul (Turkey); Uelker, Suekrue [Afyon Kocatepe Univ. (Turkey). Dept. of Mechanical Engineering

    2015-06-01

    Properties of steel can be enhanced by surface treatments such as coating. In some cases, further treatments such as nitriding can also be used in order to get even better results. In order to investigate the properties of nitride layer on hard Cr coated AISI 1010 steel, substrates were electroplated to form hard Cr coatings. Then hard Cr coatings were plasma nitrided at 700 C for 3 h, 5 h and 7 h and nitride phases on the coatings were investigated by X-ray diffraction analysis. The layer thickness and surface properties of nitride films were investigated by scanning electron microscopy. The hardness and adhesion properties of Cr-N phases were examined using nano indentation and Daimler-Benz Rockwell C adhesion tests. The highest measured hardness was 24.1 GPa and all the three samples exhibited poor adhesion.

  15. Homoepitaxial growth of gallium nitride and aluminum nitride and its effects on device properties

    Science.gov (United States)

    Grandusky, James R.

    Lattice and thermal mismatch between epitaxial layers and substrates have long been the major challenge in obtaining high quality devices in the III-Nitride material system due to the lack of availability of native substrates. Recently methods for obtaining high quality free standing native substrates have been achieved and these products are beginning to enter the commercial market. However the quality of these substrates is significantly lower than those in traditional substrates such as Si and GaAs and the high cost and low availability makes it difficult to study the homoepitaxial growth. In order to use these substrates for epitaxial growth, one first must understand what features are needed for the substrates to be epi ready. In addition, one must understand what features in the substrates impact optoelectronic device performances most significantly. Initial homoepitaxial growth was carried out on both AIN and GaN substrates. On AIN substrates it was found that annealing the sample prior to growth was very important to obtain improved surface morphologies for the homoepitaxial layers. Similar annealing steps were attempted on GaN substrates, however annealing under hydrogen left large Ga droplets on the surface. For homoepitaxy on HVPE GaN substrates, the substrate characteristics, such as bowing, surface morphology, structural properties, and optical properties were found to have a large influence on growth and device performance. Even with a reduced dislocation density, substrates with poor characteristics performed worse than devices on GaN/sapphire. The effect of polishing process on the substrates was found to be very important and substrates with subsurface damage led to poor growth, even though the starting surface was very smooth. Optimization of a thin GaN layer and a multiple quantum well structure revealed very different optimum growth conditions for the HVPE substrates and the GaN/sapphire templates. Theoretical modeling using density functional

  16. Tensile creep behavior in an advanced silicon nitride

    International Nuclear Information System (INIS)

    Tensile creep behavior and changes in the microstructure of the advanced silicon nitride, SN 88M, were studied at temperatures from 1250 to 1400 C to reveal the creep resistance and lifetime-controlling processes. Assuming power law dependence of the minimum strain rate on stress, stress exponents from 6 to 8 and an apparent activation energy of 780 kJ/mol were obtained. Extensive electron microscopy observations revealed significant changes in the crystalline secondary phases and creep damage development. Creep damage was classified in two groups: 'inter-granular' defects in the amorphous boundary phases, and 'intra-granular' defects in silicon nitride grains. The inter-granular defects involved multigrain junction cavities, two-grain junction cavities, microcracks and cracks. The intra-granular defects included broken large grains, small symmetrical and asymmetrical cavities, and crack-like intragranular cavities. Cavities are generated continuously during the whole deformation starting from the threshold strain of ∝0.1%, and they contribute linearly to the tensile strain. Cavities produce more than 90% of the total tensile strain, and it is concluded that cavitation is the main creep mechanism in silicon nitride ceramics. The multigrain junction cavities are considered to be the most important for generating new volume and producing tensile strain. The Luecke and Wiederhorn (L and W) creep model, based on cavitation at multigrain junctions according to an exponential law, was proven to correspond to the stress dependence of the minimum strain rate. A qualitative model based on the L and W model was suggested and expanded to include intragranular cavitation. The basic mechanisms involve a repeating of the sequence grain boundary sliding (GBS) => cavitation at multigrain junctions => viscous flow and dissolution-precipitation. (orig.)

  17. Nanostructured silicon nitride from wheat and rice husks

    Science.gov (United States)

    Qadri, S. B.; Rath, B. B.; Gorzkowski, E. P.; Wollmershauser, J. A.; Feng, C. R.

    2016-04-01

    Nanoparticles, submicron-diameter tubes, and rods of Si3N4 were synthesized from the thermal treatment of wheat and rice husks at temperatures at and above 1300 °C in a nitrogen atmosphere. The whole pattern Rietveld analysis of the observed diffraction data from treatments at 1300 °C showed the formation of only hexagonal α-phase of Si3N4 with an R-factor of 1%, whereas samples treated at 1400 °C and above showed both α- and β-phases with an R-factor of 2%. Transmission electron microscopy showed the presence of tubes, rods, and nanoparticles of Si3N4. In a two-step process, where pure SiC was produced first from rice or wheat husk in an argon atmosphere and subsequently treated in a nitrogen atmosphere at 1450 °C, a nanostructured composite material having α- and β-phases of Si3N4 combined with cubic phase of SiC was formed. The thermodynamics of the formation of silicon nitride is discussed in terms of the solid state reaction between organic matter (silica content), which is inherently present in the wheat and rice husks, with the nitrogen from the furnace atmosphere. Nanostructures of silicon nitride formed by a single direct reaction or their composites with SiC formed in a two-step process of agricultural byproducts provide an uncomplicated sustainable synthesis route for silicon nitride used in mechanical, biotechnology, and electro-optic nanotechnology applications.

  18. Magnetovolume effects in manganese nitrides with antiperovskite structure

    Directory of Open Access Journals (Sweden)

    Koshi Takenaka

    2014-01-01

    Full Text Available Magnetostructural correlations in antiperovskite manganese nitrides were investigated systematically for stoichiometric and solid solution Mn3Cu1−xAxN (A = Co, Ni, Zn, Ga, Ge, Rh, Pd, Ag, In, Sn or Sb. This class of nitrides is attracting great attention because of their giant negative thermal expansion, which is achieved by doping Ge or Sn into the A site as a relaxant of the sharp volume contraction on heating (spontaneous volume magnetostriction ωs because of the magnetovolume effects. The physical background of large ωs and mechanism of how the volume contraction becomes gradual with temperature are central concerns for the physics and applications of these nitrides. An entire dataset of thermal expansion, crystal structure and magnetization demonstrates that the cubic triangular antiferromagnetic state is crucial for large ωs. The intimate relationship between ωs and the magnetic structure is discussed in terms of geometrical frustration related to the Mn6N octahedron and magnetic stress concept. The results presented herein also show that ωs depends on the number of d electrons in the A atom, suggesting the important role of the d orbitals of the A atom. Not all the dopants in the A site, but the elements that disturb the cubic triangular antiferromagnetic state, are effective in broadening the volume change. This fact suggests that instability neighboring the phase boundary is related to the broadening. The relation between the gradual volume change and the local structure anomaly is suggested by recent microprobe studies.

  19. Substrate-induced bandgap in graphene on hexagonal boron nitride

    OpenAIRE

    Giovannetti, Gianluca; Khomyakov, Petr A.; Brocks, Geert; Paul J. Kelly; Brink, Jeroen van den

    2007-01-01

    We determine the electronic structure of a graphene sheet on top of a lattice-matched hexagonal boron nitride (h-BN) substrate using ab initio density functional calculations. The most stable configuration has one carbon atom on top of a boron atom, the other centered above a BN ring. The resulting inequivalence of the two carbon sites leads to the opening of a gap of 53 meV at the Dirac points of graphene and to finite masses for the Dirac fermions. Alternative orientations of the graphene s...

  20. Engineering property data on selected ceramics. Volume I. Nitrides

    International Nuclear Information System (INIS)

    This publication constitutes completion of the first phase in a program to update and upgrade the 1966 Databook, ''Engineering Properties of Ceramics'', (AFML-TR-66-52). The data are presented in the International System (SI) of units as well as in the engineering units used in the 1966 edition. Most data are referenced to the original source. Also, material and testing factors influencing each reported property are specified insofar as possible. The nitrides covered include these of alkaline earth metals, Al, B, Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, rare earths, U, Pu, and Th. 1373 references

  1. Cellulose nanofibrils (CNF) filled boron nitride (BN) nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Sulaiman, Hanisah Syed; Hua, Chia Chin; Zakaria, Sarani [School of Applied Physic, Faculty of Science and Technology, Universiti Kebangsaan Malaysia.43600 Bangi, Selangor (Malaysia)

    2015-09-25

    In this study, nanocomposite using cellulose nanofibrils filled with different percentage of boron nitride (CNF-BN) were prepared. The objective of this research is to study the effect of different percentage of BN to the thermal conductivity of the nanocomposite produced. The CNF-BN nanocomposite were characterization by FT-IR, SEM and thermal conductivity. The FT-IR analysis of the CNF-BN nanocomposite shows all the characteristic peaks of cellulose and BN present in all samples. The dispersion of BN in CNF were seen through SEM analysis. The effect of different loading percentage of BN to the thermal conductivity of the nanocomposite were also investigated.

  2. Pressure effects on dynamics behavior of multiwall boron nitride nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Talebian, Taha [Faculty of Engineering, Neyshabur Branch, Islamic Azad University, Neyshabur (Iran, Islamic Republic of)

    2016-01-15

    The dynamic behavior of Multiwall boron nitride nanotubes (MWBNNTs) is investigated by employing multiple elastic shells model. The influences of van der Waals interactions on layers are shown as nonlinear functions of the interlayer distance of MWBNNTs. Governing equations are solved by using the developed finite element method and by employing time history diagrams. The radial wave speed from the outermost layer to the innermost layer is computed. The effects of geometrical factors such as diameter-to-thickness ratio on dynamic behavior of MWBNNTs are determined. The magnification aspects of MWBNNTs are computed, and the effects of surrounding pressures on wave speed and magnification aspect of MWBNNTs are discussed.

  3. Aluminum nitride nanophotonic circuits operating at ultraviolet wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Stegmaier, M.; Ebert, J.; Pernice, W. H. P., E-mail: wolfram.pernice@kit.edu [Institute of Nanotechnology, Karlsruhe Institute of Technology, 76133 Karlsruhe (Germany); Meckbach, J. M.; Ilin, K.; Siegel, M. [Institute of Micro- und Nanoelectronic Systems, Karlsruhe Institute of Technology, 76187 Karlsruhe (Germany)

    2014-03-03

    Aluminum nitride (AlN) has recently emerged as a promising material for integrated photonics due to a large bandgap and attractive optical properties. Exploiting the wideband transparency, we demonstrate waveguiding in AlN-on-Insulator circuits from near-infrared to ultraviolet wavelengths using nanophotonic components with dimensions down to 40 nm. By measuring the propagation loss over a wide spectral range, we conclude that both scattering and absorption of AlN-intrinsic defects contribute to strong attenuation at short wavelengths, thus providing guidelines for future improvements in thin-film deposition and circuit fabrication.

  4. Investigation of titanium nitride coating by broadband laser ultrasonic spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Gao Wei-Min(高伟民); Christ Glorieux; Walter Lauriks; Jan Then

    2002-01-01

    We present a laser ultrasonic method to investigate a titanium nitride (TiN) coating specimen. The techniqueis based on the principle of surface acoustic wave (SAW) dispersion during acoustic propagation on a half-space withthe presence of a thin layer. Due to the high efficiency of laser line-source excitation, we have been able to generateand detect a SAW with an excellent signal-to-noise ratio in a wide frequency band. An inverse fitting algorithm wasemployed to extract simultaneously the thickness and the elastic parameters of the TiN coating from the experimentalSAW velocity dispersion curve.

  5. Carbon nanotube quantum dots on hexagonal boron nitride

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-14

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

  6. Atomistic models of hydrogenated amorphous silicon nitride from first principles

    OpenAIRE

    Jarolimek, K.; de Groot, R. A.; de Wijs, G. A.; Zeman, M.

    2010-01-01

    We present a theoretical study of hydrogenated amorphous silicon nitride (a-SiNx:H), with equal concentrations of Si and N atoms (x=1), for two considerably different densities (2.0 and 3.0 g/cm3). Densities and hydrogen concentration were chosen according to experimental data. Using first-principles molecular-dynamics within density-functional theory the models were generated by cooling from the liquid. Where both models have a short-range order resembling that of crystalline Si3N4 because o...

  7. Research on the Cutting Performance of Cubic Boron Nitride Tools

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    There were only two kinds of superhard tool material at the past, i.e. diamond and cubic boron nitride (CBN). Manmade diamond and CBN are manufactured by the middle of 20th century. Various manufacturing methods and manmade superhard materials were developed later. They were widely used in different industry and science areas. Recently, a new kind of superhard tool material, C 3N 4 coating film, had been developed. American physical scientists, A. M. Liu and M. L. Cohen, designed a new kind of inorganic c...

  8. Eigenmode Splitting in all Hydrogenated Amorphous Silicon Nitride Coupled Microcavity

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xian-Gao; HUANG Xin-Fan; CHEN Kun-Ji; QIAN Bo; CHEN San; DING Hong-Lin; LIU Sui; WANG Xiang; XU Jun; LI Wei

    2008-01-01

    Hydrogenated amorphous silicon nitride based coupled optical microcavity is investigated theoretically and experimentally. The theoretical calculation of the transmittance spectra of optical microcavity with one cavity and coupled microcavity with two-cavity is performed.The optical eigenmode splitting for coupled microcavity is found due to the interaction between the neighbouring localized cavities.Experimentally,the coupled cavity samples are prepared by plasma enhanced chemical vapour deposition and characterized by photoluminescence measurements.It is found that the photoluminescence peak wavelength agrees well with the cavity mode in the calculated transmittance spectra.This eigenmode splitting is analogous to the electron state energy splitting in diatom molecules.

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

    CERN Document Server

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

    2015-01-01

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

  10. Melon: A carbon-nitride analog to graphene

    Science.gov (United States)

    Therrien, Joel; Li, Yancen; Schmidt, Daniel

    2012-02-01

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

  11. Advances and prospects in nitrides based light-emitting-diodes

    Science.gov (United States)

    Jinmin, Li; Zhe, Liu; Zhiqiang, Liu; Jianchang, Yan; Tongbo, Wei; Xiaoyan, Yi; Junxi, Wang

    2016-06-01

    Due to their low power consumption, long lifetime and high efficiency, nitrides based white light-emitting-diodes (LEDs) have long been considered to be a promising technology for next generation illumination. In this work, we provide a brief review of the development of GaN based LEDs. Some pioneering and significant experiment results of our group and the overview of the recent progress in this field are presented. We hope it can provide some meaningful information for the development of high efficiency GaN based LEDs and solid-state-lighting. Project supported by the National High Technology Research and Development Program of China (No. 2013AA03A101).

  12. Exciton optical transitions in a hexagonal boron nitride single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Museur, L. [Laboratoire de Physique des Lasers - LPL, CNRS UMR 7538, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Brasse, G.; Maine, S.; Ducastelle, F.; Loiseau, A. [ONERA - Laboratoire d' Etude des Microstructures - LEM, ONERA-CNRS, UMR 104, BP 72, 92322 Chatillon Cedex (France); Pierret, A. [ONERA - Laboratoire d' Etude des Microstructures - LEM, ONERA-CNRS, UMR 104, BP 72, 92322 Chatillon Cedex (France); CEA-CNRS, Institut Neel/CNRS, Universite J. Fourier, CEA/INAC/SP2M, 17 rue des Martyrs, 38 054 Grenoble Cedex 9 (France); Attal-Tretout, B. [ONERA - Departement Mesures Physiques - DMPh, 27 Chemin de la Huniere, 91761 Palaiseau Cedex (France); Barjon, J. [GEMaC, Universite de Versailles St Quentin, CNRS Bellevue, 1 Place Aristide Briand, 92195 Meudon Cedex (France); Watanabe, K.; Taniguchi, T. [National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan); Kanaev, A. [Laboratoire des Sciences des Procedes et des Materiaux - LSPM, CNRS UPR 3407, Universite Paris 13, 93430 Villetaneuse (France)

    2011-06-15

    Near band gap photoluminescence (PL) of a hexagonal boron nitride single crystal has been studied at cryogenic temperatures with synchrotron radiation excitation. The PL signal is dominated by trapped-exciton optical transitions, while the photoluminescence excitation (PLE) spectra show features assigned to free excitons. Complementary photoconductivity and PLE measurements set the band gap transition energy to 6.4 eV and the Frenkel exciton binding energy larger than 380 meV. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Glow Discharge Plasma Nitriding of AISI 304 Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    A.QAYYUM; M.A.NAVEED; S.ZEB; G.MURTAZA; M.ZAKAULLAH

    2007-01-01

    Glow discharge plasma nitriding of AISI 304 austenitic stainless steel has been carried out for different processing time under optimum discharge conditions established by spectroscopic analysis.The treated samples were analysed by X-ray diffraction(XRD)to explore the changes induced in the crystallographic structure.The XRD pattern confirmed the formation of an expanded austenite phase(γN)owing to incorporation of nitrogen as an interstitial solid solution in the iron lattice.A Vickers microhardness tester was used to evaluate the surface hardness as a function of indentation depth(μm).The results showed clear evidence of surface changes with substantial increase in surface hardness.

  14. Field emission characteristics from graphene on hexagonal boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Takatoshi, E-mail: takatoshi-yamada@aist.go.jp [National Institute of Advanced Industrial Science and Technology, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565 (Japan); Masuzawa, Tomoaki; Ebisudani, Taishi; Okano, Ken [International Christian University, 3-10-2 Osawa, Mitaka, Tokyo 181-8585 (Japan); Taniguchi, Takashi [National Institute for Material Science (NIMS), 1-1-1 Namiki, Tsukuba 305-0044 (Japan)

    2014-06-02

    An attempt has been made to utilize uniquely high electron mobility of graphene on hexagonal boron nitride (h-BN) to electron emitter. The field emission property of graphene/h-BN/Si structure has shown enhanced threshold voltage and emission current, both of which are key to develop novel vacuum nanoelectronics devices. The field emission property was discussed along with the electronic structure of graphene investigated by Fowler-Nordheim plot and ultraviolet photoelectron spectroscopy. The result suggested that transferring graphene on h-BN modified its work function, which changed field emission mechanism. Our report opens up a possibility of graphene-based vacuum nanoelectronics devices with tuned work function.

  15. Nitrogen incorporation in sputter deposited molybdenum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-03-15

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

  16. Sorption J-T refrigeration utilizing manganese nitride chemisorption

    Science.gov (United States)

    Jones, Jack; Lund, Alan

    1990-01-01

    The equilibrium pressures and compositions have been measured for a system of finely powdered manganese nitride and nitrogen gas at 650, 700, 800, and 850 C for various nitrogen loadings. Pressures ranged from less than 0.02 MPa at 650 C to 6.38 MPa at 850 C. Analysis of the test results has shown that under certain conditions Mn(x)N(y) could potentially be used in a triple regenerative sorption compressor refrigeration system, but the potential power savings are small compared to the increased complexity and reliability problems associated with very high temperature (above 950 C) pressurized systems.

  17. Visible light metasurfaces based on gallium nitride high contrast gratings

    Science.gov (United States)

    Wang, Zhenhai; He, Shumin; Liu, Qifa; Wang, Wei

    2016-05-01

    We propose visible-light metasurfaces (VLMs) capable of serving as lens and beam deflecting element based on gallium nitride (GaN) high contrast gratings (HCGs). By precisely manipulating the wavefront of the transmitted light, we theoretically demonstrate an HCG focusing lens with transmissivity of 86.3%, and a VLM with beam deflection angle of 6.09° and transmissivity as high as 91.4%. The proposed all-dielectric metasurfaces are promising for GaN-based visible light-emitting diodes (LEDs), which would be robust and versatile for controlling the output light propagation and polarization, as well as enhancing the extraction efficiency of the LEDs.

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

    KAUST Repository

    Mokkath, Junais Habeeb

    2014-09-04

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

  19. Frequency conversion in free-standing periodically oriented gallium nitride

    Science.gov (United States)

    Brown, Christopher G.; Bowman, Steven R.; Hite, Jennifer K.; Freitas, Jaime A.; Kub, Francis J.; Eddy, Charles R.; Vurgaftman, Igor; Meyer, Jerry R.; Leach, Jacob H.; Udwary, Kevin

    2016-03-01

    Gallium nitride's (GaN) material properties of broadband transparency, high thermal conductivity, and wide-band gap make it a promising candidate for high-power frequency conversion devices. The strong internal polarization of GaN leads to large second-order nonlinearity, but conventional phase matching is prevented due to weak birefringence. To obtain efficient nonlinear optic frequency conversion, patterned inversion growth has been developed to induce quasiphase matching (QPM). We have fabricated and tested periodically oriented GaN (PO-GaN) devices to obtain QPM frequency conversion. This report discusses our recent measurements of second harmonic generation resonances for these devices.

  20. Superior thermal conductivity in suspended bilayer hexagonal boron nitride

    Science.gov (United States)

    Wang, Chengru; Guo, Jie; Dong, Lan; Aiyiti, Adili; Xu, Xiangfan; Li, Baowen

    2016-05-01

    We reported the basal-plane thermal conductivity in exfoliated bilayer hexagonal boron nitride h-BN that was measured using suspended prepatterned microstructures. The h-BN sample suitable for thermal measurements was fabricated by dry-transfer method, whose sample quality, due to less polymer residues on surfaces, is believed to be superior to that of PMMA-mediated samples. The measured room temperature thermal conductivity is around 484 Wm‑1K‑1(+141 Wm‑1K‑1/ ‑24 Wm‑1K‑1) which exceeds that in bulk h-BN, providing experimental observation of the thickness-dependent thermal conductivity in suspended few-layer h-BN.

  1. Cellulose nanofibrils (CNF) filled boron nitride (BN) nanocomposites

    Science.gov (United States)

    Sulaiman, Hanisah Syed; Hua, Chia Chin; Zakaria, Sarani

    2015-09-01

    In this study, nanocomposite using cellulose nanofibrils filled with different percentage of boron nitride (CNF-BN) were prepared. The objective of this research is to study the effect of different percentage of BN to the thermal conductivity of the nanocomposite produced. The CNF-BN nanocomposite were characterization by FT-IR, SEM and thermal conductivity. The FT-IR analysis of the CNF-BN nanocomposite shows all the characteristic peaks of cellulose and BN present in all samples. The dispersion of BN in CNF were seen through SEM analysis. The effect of different loading percentage of BN to the thermal conductivity of the nanocomposite were also investigated.

  2. Hydrogenated dilute nitride semiconductors theory, properties, and applications

    CERN Document Server

    Ciatto, Gianluca

    2015-01-01

    ""The electrical and optical properties of the technologically and scientifically important dilute nitride semiconductors are strongly influenced by the introduction of atomic hydrogen. This volume is an excellent summary and resource for the most recent understanding of experimental results and state-of-the-art theoretical studies of the formation, reversibility, and microscopic structure of nitrogen-hydrogen complexes in these materials. The book details how a wide variety of experimental techniques have provided a detailed understanding of the role of hydrogen. It is the premier sourc

  3. Van der Waals interaction in a boron nitride bilayer

    International Nuclear Information System (INIS)

    We have carried out quantum Monte Carlo (QMC) calculations to study the interlayer interaction in a boron nitride (BN) bilayer. The binding energy, 81 meV/2BN after finite-size corrections, was found to be larger than that obtained by density functional theory (DFT) with local density approximation, and smaller than those using van der Waals density functionals, both by considerable amounts. The QMC calculated interaction beyond the equilibrium interlayer separation was found to have a longer-range behavior than all the available DFT schemes. (paper)

  4. Synthesis of boron nitride nanotubes and their applications

    Directory of Open Access Journals (Sweden)

    Saban Kalay

    2015-01-01

    Full Text Available Boron nitride nanotubes (BNNTs have been increasingly investigated for use in a wide range of applications due to their unique physicochemical properties including high hydrophobicity, heat and electrical insulation, resistance to oxidation, and hydrogen storage capacity. They are also valued for their possible medical and biomedical applications including drug delivery, use in biomaterials, and neutron capture therapy. In this review, BNNT synthesis methods and the surface modification strategies are first discussed, and then their toxicity and application studies are summarized. Finally, a perspective for the future use of these novel materials is discussed.

  5. Compressibility and thermal expansion of cubic silicon nitride

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lindelov, H.; Gerward, Leif;

    2002-01-01

    The compressibility and thermal expansion of the cubic silicon nitride (c-Si3N4) phase have been investigated by performing in situ x-ray powder-diffraction measurements using synchrotron radiation, complemented with computer simulations by means of first-principles calculations. The bulk...... compressibility of the c-Si3N4 phase originates from the average of both Si-N tetrahedral and octahedral compressibilities where the octahedral polyhedra are less compressible than the tetrahedral ones. The origin of the unit cell expansion is revealed to be due to the increase of the octahedral Si-N and N-N bond...

  6. Electronic structure of superlattices of graphene and hexagonal boron nitride

    KAUST Repository

    Kaloni, Thaneshwor P.

    2011-11-14

    We study the electronic structure of superlattices consisting of graphene and hexagonal boron nitride slabs, using ab initio density functional theory. We find that the system favors a short C–B bond length at the interface between the two component materials. A sizeable band gap at the Dirac point is opened for superlattices with single graphene layers but not for superlattices with graphene bilayers. The system is promising for applications in electronic devices such as field effect transistors and metal-oxide semiconductors.

  7. Method of nitriding niobium to form a superconducting surface

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Michael J.; Klopf, John Michael; Singaravelu, Senthilaraja

    2014-08-19

    A method of forming a delta niobium nitride .delta.-NbN layer on the surface of a niobium object including cleaning the surface of the niobium object; providing a treatment chamber; placing the niobium object in the treatment chamber; evacuating the chamber; passing pure nitrogen into the treatment chamber; focusing a laser spot on the niobium object; delivering laser fluences at the laser spot until the surface of the niobium object reaches above its boiling temperature; and rastering the laser spot over the surface of the niobium object.

  8. Molecular dynamics of halogenated graphene - hexagonal boron nitride nanoribbons

    Science.gov (United States)

    Nemnes, G. A.; Visan, Camelia; Anghel, D. V.; Manolescu, A.

    2016-08-01

    The hybrid graphene - hexagonal boron nitride (G-hBN) systems offer new routes in the design of nanoscale electronic devices. Using ab initio density functional theory calculations we investigate the dynamics of zig-zag nanoribbons a few interatomic distances wide. Several structures are analyzed, namely pristine graphene, hBN and G-hBN systems. By passivating the nanoribbon edges with hydrogen and different halogen atoms, one may tune the electronic and mechanical properties, like the band gap energies and the natural frequencies of vibration.

  9. Optimization of time–temperature schedule for nitridation of silicon compact on the basis of silicon and nitrogen reaction kinetics

    Indian Academy of Sciences (India)

    J Rakshit; P K Das

    2000-08-01

    A time–temperature schedule for formation of silicon–nitride by direct nitridation of silicon compact was optimized by kinetic study of the reaction, 3Si + 2N2 = Si3N4 at four different temperatures (1250°C, 1300°C, 1350°C and 1400°C). From kinetic study, three different temperature schedules were selected each of duration 20 h in the temperature range 1250°–1450°C, for complete nitridation. Theoretically full nitridation (100% i.e. 66.7% weight gain) was not achieved in the product having no unreacted silicon in the matrix, because impurities in Si powder and loss of material during nitridation would result in 5–10% reduction of weight gain. Green compact of density < 66% was fully nitrided by any one of the three schedules. For compact of density > 66%, the nitridation schedule was maneuvered for complete nitridation. Iron promotes nitridation reaction. Higher weight loss during nitridation of iron doped compact is the main cause of lower nitridation gain compared to undoped compact in the same firing schedule. Iron also enhances the amount of -Si3N4 phase by formation of low melting FeSi phase.

  10. The preparation of high-adsorption, spherical, hexagonal boron nitride by template method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ning, E-mail: zhangning5832@163.com; Liu, Huan; Kan, Hongmin; Wang, Xiaoyang; Long, Haibo; Zhou, Yonghui

    2014-11-15

    Highlights: • The high-adsorption, spherical, hexagonal boron nitride powders were prepared. • The influence mechanism of template content on the micro-morphology and adsorption was explored. • At appropriate synthesis temperature, higher adsorption mesoporous spheres h-BN began to form. - Abstract: This research used low-cost boric acid and borax as a source of boron, urea as a nitrogen source, dodecyl-trimethyl ammonium chloride (DTAC) as a template, and thus prepared different micro-morphology hexagonal boron nitride powders under a flowing ammonia atmosphere at different nitriding temperatures. The effects of the template content and nitriding temperature on the micro-morphology of hexagonal boron nitride were studied and the formation mechanism analysed. The influences of the template content and nitriding temperature on adsorption performance were also explored. The results showed that at a nitriding temperature of 675 °C, the micro-morphologies of h-BN powder were orderly, inhomogeneous spherical, uniform spherical, beam, and pie-like with increasing template content. The micro-morphology was inhomogeneous spherical at a DTAC dose of 7.5%. The micro-morphology was uniform spherical at a DTAC dose of 10%. At a DTAC dose of 12%, the micro-morphology was a mixture of beam and pie-like shapes. At a certain template content (DTAC at 10%) and at lower nitriding temperatures (625 °C and 650 °C), spherical shell structures with surface subsidence began to form. The porous spheres would appear at a nitriding temperature of 675 °C, and the ball diameter thus formed was approximately 500–600 nm. The ball diameter was about 600–700 nm when the nitriding temperature was 700 °C. At a nitriding temperature of 725 °C, the ball diameter was between 800 and 1000 nm and sintering necking started to form. When the relative pressure was higher, previously closed pores opened and connected with the outside world: the adsorption then increased significantly. The

  11. Wafer-Scale and Wrinkle-Free Epitaxial Growth of Single-Orientated Multilayer Hexagonal Boron Nitride on Sapphire.

    Science.gov (United States)

    Jang, A-Rang; Hong, Seokmo; Hyun, Chohee; Yoon, Seong In; Kim, Gwangwoo; Jeong, Hu Young; Shin, Tae Joo; Park, Sung O; Wong, Kester; Kwak, Sang Kyu; Park, Noejung; Yu, Kwangnam; Choi, Eunjip; Mishchenko, Artem; Withers, Freddie; Novoselov, Kostya S; Lim, Hyunseob; Shin, Hyeon Suk

    2016-05-11

    Large-scale growth of high-quality hexagonal boron nitride has been a challenge in two-dimensional-material-based electronics. Herein, we present wafer-scale and wrinkle-free epitaxial growth of multilayer hexagonal boron nitride on a sapphire substrate by using high-temperature and low-pressure chemical vapor deposition. Microscopic and spectroscopic investigations and theoretical calculations reveal that synthesized hexagonal boron nitride has a single rotational orientation with AA' stacking order. A facile method for transferring hexagonal boron nitride onto other target substrates was developed, which provides the opportunity for using hexagonal boron nitride as a substrate in practical electronic circuits. A graphene field effect transistor fabricated on our hexagonal boron nitride sheets shows clear quantum oscillation and highly improved carrier mobility because the ultraflatness of the hexagonal boron nitride surface can reduce the substrate-induced degradation of the carrier mobility of two-dimensional materials. PMID:27120101

  12. Effect of PostNitride Annealing on Wear and Corrosion Behavior of Titanium Alloy Ti-6Al-4V

    Science.gov (United States)

    Anandan, C.; Mohan, L.

    2016-08-01

    Titanium alloy, Ti-6Al-4V, was plasma nitrided using RF plasma with 100% N at 800 °C and annealed at 850 °C in vacuum. XRD and XPS studies show the formation of titanium nitrides after nitriding and redistribution of nitrogen after annealing. Potentiodynamic polarization and electrochemical impedance spectroscopy studies in Hank's solution show that nitriding decreases the corrosion resistance of the substrate and postnitride annealing improves the corrosion resistance of the nitrided samples. After nitriding, wear rate has decreased by an order of magnitude in reciprocating wear experiments and decreased further in annealed samples in comparison with that of substrate. Thus, postnitride annealing improves both corrosion and wear resistance of the nitrided sample. These improvements are attributed to redistribution of nitrogen and formation of a thin oxide layer on the sample due to annealing.

  13. Effect of strontium nitride on the properties of Sr2SisNs:Eu2+ red phosphor

    Institute of Scientific and Technical Information of China (English)

    Teng Xiaoming; Liang Chao; He Jinhua

    2011-01-01

    The nitride phosphor Sr2SisNs :Eu2+ was synthesized by the high temperature solid-state method. The properties of Sr2 Si5Ns:Eu2+ were discussed by X-ray diffraction (XRD) scanning electron microscope (SEM) and spectra analysis. The XRD pattern shows that the single phase produces when strontium nitride is a bit excessive.The SEM photo implies that the excessive strontium nitride works as a flux in the reaction system. The position of emission peak is also located at about 612 nm as strontium nitride is excessive. The luminescent intensity of the phosphor adding excessive strontium nitride is higher than that of the phosphor introducing stoichiometric strontium nitride. The optimized content of nitride strontium was 2.05 mol/mol for the obtained phosphor with excellent properties.

  14. Effect of PostNitride Annealing on Wear and Corrosion Behavior of Titanium Alloy Ti-6Al-4V

    Science.gov (United States)

    Anandan, C.; Mohan, L.

    2016-10-01

    Titanium alloy, Ti-6Al-4V, was plasma nitrided using RF plasma with 100% N at 800 °C and annealed at 850 °C in vacuum. XRD and XPS studies show the formation of titanium nitrides after nitriding and redistribution of nitrogen after annealing. Potentiodynamic polarization and electrochemical impedance spectroscopy studies in Hank's solution show that nitriding decreases the corrosion resistance of the substrate and postnitride annealing improves the corrosion resistance of the nitrided samples. After nitriding, wear rate has decreased by an order of magnitude in reciprocating wear experiments and decreased further in annealed samples in comparison with that of substrate. Thus, postnitride annealing improves both corrosion and wear resistance of the nitrided sample. These improvements are attributed to redistribution of nitrogen and formation of a thin oxide layer on the sample due to annealing.

  15. INFLUENCE OF ANNEALING TEMPERATURE ON SOME PHYSICAL PROPERTIES OF CUBIC BORON NITRIDES OBTAINED FROM PYROLITIC BORON NITRIDE

    Directory of Open Access Journals (Sweden)

    N. D. Bayluk

    2010-01-01

    Full Text Available The paper presents results of investigations on dependence of dielectric, electromechanical and elastic properties of BNпсф  polycrystals (sphalerite with texture axis [111]сф, obtained from pyrolitic boron nitride  BNпг on annealing temperature up to 2173 К. Peculiar features concerning changes of the given properties in the zone of low-temperature annealing 700–773 К and phase transformation BNпг — BNпсф  are shown in the paper.

  16. Silver Nanoparticle-Deposited Boron Nitride Nanosheets as Fillers for Polymeric Composites with High Thermal Conductivity.

    Science.gov (United States)

    Wang, Fangfang; Zeng, Xiaoliang; Yao, Yimin; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2016-01-01

    Polymer composites with high thermal conductivity have recently attracted much attention, along with the rapid development of the electronic devices toward higher speed and performance. However, a common method to enhance polymer thermal conductivity through an addition of high thermally conductive fillers usually cannot provide an expected value, especially for composites requiring electrical insulation. Here, we show that polymeric composites with silver nanoparticle-deposited boron nitride nanosheets as fillers could effectively enhance the thermal conductivity of polymer, thanks to the bridging connections of silver nanoparticles among boron nitride nanosheets. The thermal conductivity of the composite is significantly increased from 1.63 W/m-K for the composite filled with the silver nanoparticle-deposited boron nitride nanosheets to 3.06 W/m-K at the boron nitride nanosheets loading of 25.1 vol %. In addition, the electrically insulating properties of the composite are well preserved. Fitting the measured thermal conductivity of epoxy composite with one physical model indicates that the composite with silver nanoparticle-deposited boron nitride nanosheets outperforms the one with boron nitride nanosheets, owning to the lower thermal contact resistance among boron nitride nanosheets' interfaces. The finding sheds new light on enhancement of thermal conductivity of the polymeric composites which concurrently require the electrical insulation. PMID:26783258

  17. Effect of plasma nitrided layers on low- alloy steel on its hydrogen degradation

    Directory of Open Access Journals (Sweden)

    A. Zieliński

    2006-04-01

    Full Text Available Purpose: Purpose of this paper is evaluation of susceptibility to hydrogen degradation of structural low-alloy steel, plasma nitrided in the atmosphere with various contents of N2 and H2.Design/methodology/approach: Susceptibility of 34CrAlNi7-10 steel and samples with various plasma nitrided layers have been evaluated under monotonically increasing load in 0.005 M H2SO4 solution. Slow-strain rate tensile test (SSRT test was carried out under cathodic polarisation. Elongation, reduction in area, fracture energy and tensile strength were chosen as measures of susceptibility to hydrogen embrittlement. Fracture modes of failed samples were examined with the use of scanning electron microscope (SEM.Findings: All tested samples revealed susceptibility to hydrogen degradation under hydrogenation. Samples with nitrided layer have lower lost of reduction in are than base metal samples. The nitrided layer established in standard atmosphere 30% H2 and 70% N2 has the highest resistance to hydrogen degradation.Research limitations/implications: Further research should be taken to reveal the exact mechanism of increased plasticity of nitided layer with absorbed hydrogen.Practical implications: Plasma nitriding may prevent hydrogen charging of machines and vehicles parts in hydrogen generating environments, and thus decreasing susceptibility to hydrogen embrittlement.Originality/value: Under the increasing load and hydrogen generating environments plasma nitrided layers are effective barriers to hydrogen entry into a bulk of steel, and additionally increased plasticity of nitrided layers with absorbed hydrogen was observed.

  18. Improving electrochemical properties of AISI 1045 steels by duplex surface treatment of plasma nitriding and aluminizing

    Energy Technology Data Exchange (ETDEWEB)

    Haftlang, Farahnaz, E-mail: f.haftlang@students.semnan.ac.ir [Department of Metallurgy and Materials Engineering, Faculty of Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Habibolahzadeh, Ali [Department of Metallurgy and Materials Engineering, Faculty of Engineering, Semnan University, Semnan (Iran, Islamic Republic of); Sohi, Mahmoud Heydarzadeh [School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-02-28

    Highlights: • AlN coating was applied on AISI 1045 steel via plasma nitriding and aluminizing. • Plasma nitriding and post-aluminizing result in AlN single phase layer on the steel. • PN–Al coated steel had better corrosion resistance than Al–PN one. • Formation of oxide layer provided protection of PN–Al coated steel against corrosion. • Pitting and surface defects was the dominant corrosion mechanism in Al–PN coated steel. - Abstract: Improvement in electrochemical behavior of AISI 1045 steel after applying aluminum nitride coating was investigated in 3.5% NaCl solution, using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analyses. Aluminum nitride coating was applied on the steel surface by duplex treatment of pack aluminizing and plasma nitriding. Some specimens were plasma nitrided followed by aluminizing (PN–Al), while the others were pack aluminized followed by plasma nitriding (Al–PN). Topological and structural studies of the modified surfaces were conducted using scanning electron microscope (SEM) equipped by energy dispersive X-ray spectroscope (EDS), and X-ray diffractometer (XRD). The electrochemical measurements showed that the highest corrosion and polarization (R{sub p}) resistances were obtained in PN–Al specimens, having single phase superficial layer of AlN. Pitting mechanism was dominant reason of lower corrosion resistance in the Al–PN specimens.

  19. Early stages of plasma induced nitridation of Si (111) surface and study of interfacial band alignment

    Energy Technology Data Exchange (ETDEWEB)

    Shetty, Satish; Shivaprasad, S. M., E-mail: smsprasad@jncasr.ac.in [International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)

    2016-02-07

    We report here a systematic study of the nitridation of the Si (111) surface by nitrogen plasma exposure. The surface and interface chemical composition and surface morphology are investigated by using RHEED, X-ray photoelectron spectroscopy, and atomic force microscopy (AFM). At the initial stage of nitridation two superstructures—“8 × 8” and “8/3 × 8/3”—form, and further nitridation leads to 1 × 1 stoichiometric silicon nitride. The interface is seen to have the Si{sup 1+} and Si{sup 3+} states of silicon bonding with nitrogen, which suggests an atomically abrupt and defect-free interface. The initial single crystalline silicon nitride layers are seen to become amorphous at higher thicknesses. The AFM image shows that the nitride nucleates at interfacial dislocations that are connected by sub-stoichiometric 2D-nitride layers, which agglomerate to form thick overlayers. The electrical properties of the interface yield a valence band offset that saturates at 1.9 eV and conduction band offset at 2.3 eV due to the evolution of the sub-stoichiometric interface and band bending.

  20. Effect of plasma nitriding treatment on structural, tribological and electrochemical properties of commercially pure titanium.

    Science.gov (United States)

    Çelik, İlhan; Karakan, Mehmet

    2016-02-01

    In this study, plasma nitriding treatment was applied to commercially pure titanium (Grade 2). Structural properties, electrochemical and tribological behaviours of the nitrided pure titanium specimens were comparatively investigated. Microstructure and morphology of the plasma nitrided specimens were analysed by X-ray diffraction and scanning electron microscopy. Furthermore, corrosion tests were conducted in Ringer's solution, which represents a human body environment, to determine electrochemical properties. Then, tribological and frictional properties were investigated using pin-on-disc tribometer, and a micro-hardness tester was used to measure the hardness of the coatings. The results showed that plasma nitrided specimens exhibited higher surface hardness than the untreated specimens did. In addition, the plasma nitrided specimens at 700 °C presented significantly better performance than the other plasma nitrided specimens (at 500 °C and 600 °C) under dry wear conditions. Moreover, corrosion test results showed that corrosion behaviours of untreated and nitrided samples had similar characteristic. PMID:26666885

  1. Silver Nanoparticle-Deposited Boron Nitride Nanosheets as Fillers for Polymeric Composites with High Thermal Conductivity

    Science.gov (United States)

    Wang, Fangfang; Zeng, Xiaoliang; Yao, Yimin; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2016-01-01

    Polymer composites with high thermal conductivity have recently attracted much attention, along with the rapid development of the electronic devices toward higher speed and performance. However, a common method to enhance polymer thermal conductivity through an addition of high thermally conductive fillers usually cannot provide an expected value, especially for composites requiring electrical insulation. Here, we show that polymeric composites with silver nanoparticle-deposited boron nitride nanosheets as fillers could effectively enhance the thermal conductivity of polymer, thanks to the bridging connections of silver nanoparticles among boron nitride nanosheets. The thermal conductivity of the composite is significantly increased from 1.63 W/m-K for the composite filled with the silver nanoparticle-deposited boron nitride nanosheets to 3.06 W/m-K at the boron nitride nanosheets loading of 25.1 vol %. In addition, the electrically insulating properties of the composite are well preserved. Fitting the measured thermal conductivity of epoxy composite with one physical model indicates that the composite with silver nanoparticle-deposited boron nitride nanosheets outperforms the one with boron nitride nanosheets, owning to the lower thermal contact resistance among boron nitride nanosheets’ interfaces. The finding sheds new light on enhancement of thermal conductivity of the polymeric composites which concurrently require the electrical insulation.

  2. Mechanical Properties of Metal Nitrides for Radiation Resistant Coating Applications: A DFT Study

    Science.gov (United States)

    Mota, Oscar U. Ojeda; Araujo, Roy A.; Wang, Haiyan; Çağın, Tahir

    Metal nitrides compounds like aluminum nitride (AlN), titanium nitride (TiN), tantalum nitride (TaN), hafnium nitride (HfN) and zirconium nitride (ZrN) are of great interesting because of their chemical and physical properties such as: high melting point, resistivity, thermal conductivity and extremely high hardness. They are the materials of choice for various applications like protective coating for tools, diffusion barriers or metal gate contact in microelectronics, and lately their potential applications as radiation-resistive shields. In order to assess their use for radiation tolerance we have studied the structural, mechanical and electronic properties. We have evaluated the anisotropic elastic constants and their pressure dependence for three different crystalline phases: B1-NaCl, B2-CsCl, and B3-ZnS crystal structures. In addition to these cubic polymorphs, we also have studied potential hexagonal structures of some of the same metal nitrides. All computations are carried out using first principles Density Functional Theory (DFT) approach.

  3. Cathodic Cage Plasma Nitriding of Ti6Al4V Alloy

    Directory of Open Access Journals (Sweden)

    Maciej OSSOWSKI

    2016-05-01

    Full Text Available Glow discharge nitriding is being used increasingly more often for modifying the properties of titanium and its alloys with the aim to increase their frictional wear resistance, fatigue strength, and, in the case of medical applications, to eliminate the metallosis effect. Unlike PVD methods, ion nitriding ensures the formation of diffusive layers with very good adhesion to the substrate, but which still have some disadvanteges such as the “edge effect” or “hollow cathode effect” which hinders treatment of complex workpieces. The paper compares nitrided layers produced on Ti6Al4V alloy using two different types of nitriding processes. The first process is conventional dc plasma nitriding (DCPN where the samples were placed at the cathode potential, while the second one is a new method of cathodic cage plasma nitriding (CCPN process, where the substrate is insulated from the cathode and anode. The experiments have shown that the treatment conducted in a cathodic cage can be alternative for conventional ion nitriding, especially when used for small parts with complicated shapes used in the space or medical industry. DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7343

  4. Effect of plasma nitriding treatment on structural, tribological and electrochemical properties of commercially pure titanium.

    Science.gov (United States)

    Çelik, İlhan; Karakan, Mehmet

    2016-02-01

    In this study, plasma nitriding treatment was applied to commercially pure titanium (Grade 2). Structural properties, electrochemical and tribological behaviours of the nitrided pure titanium specimens were comparatively investigated. Microstructure and morphology of the plasma nitrided specimens were analysed by X-ray diffraction and scanning electron microscopy. Furthermore, corrosion tests were conducted in Ringer's solution, which represents a human body environment, to determine electrochemical properties. Then, tribological and frictional properties were investigated using pin-on-disc tribometer, and a micro-hardness tester was used to measure the hardness of the coatings. The results showed that plasma nitrided specimens exhibited higher surface hardness than the untreated specimens did. In addition, the plasma nitrided specimens at 700 °C presented significantly better performance than the other plasma nitrided specimens (at 500 °C and 600 °C) under dry wear conditions. Moreover, corrosion test results showed that corrosion behaviours of untreated and nitrided samples had similar characteristic.

  5. Precipitation of Chromium Nitrides in the Super Duplex Stainless Steel 2507

    Science.gov (United States)

    Pettersson, Niklas; Pettersson, Rachel F. A.; Wessman, Sten

    2015-03-01

    Precipitation of chromium nitrides during cooling from temperatures in the range 1373 K to 1523 K (1100 °C to 1250 °C) has been studied for the super duplex stainless steel 2507 (UNS S32750). Characterization with optical, scanning and transmission electron microscopy was combined to quantify the precipitation process. Primarily Cr2N nitrides were found to precipitate with a high density in the interior of ferrite grains. An increased cooling rate and/or an increased austenite spacing clearly promoted nitride formation, resulting in precipitation within a higher fraction of the ferrite grains, and lager nitride particles. Furthermore, formation of the meta-stable CrN was induced by higher cooling rates. The toughness seemed unaffected by nitrides. A slight decrease in pitting resistance was, however, noticed for quenched samples with large amounts of precipitates. The limited adverse effect on pitting resistance is attributed to the small size (~200 nm) of most nitrides. Slower cooling of duplex stainless steels to allow nitrogen partitioning is suggested in order to avoid large nitrides, and thereby produce a size distribution with a smaller detrimental effect on pitting resistance.

  6. Research on the Fe-silicon nitride material self-producing N2 at high temperature

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The Fe-silicon nitride synthesized by flashing combustion process was studied to determine the reaction temperature between Fe and silicon nitride, the account of N2 given out in the course of the reaction, and the change of the microstructure during calcination. The results showed that at 1127.2℃ the Fe-silicon nitride self-reacts and releases N2 and under 101.3 kPa the volume of N2 given out in the course of the reaction is 20 times more than that of the starting material. N2 is produced quickly, and completes in several decade seconds. With the producing of N2, the structure of Silicon Nitride around Fe becomes loose and porous, or cracks are formed by the reaction between Fe and silicon nitride. So if it is made use of that Fe-silicon nitride self-producing N2 at the high temperature, the performance of the material on a base of Fe-silicon nitride could be greatly improved.

  7. Metallurgical response of an AISI 4140 steel to different plasma nitriding gas mixtures

    Directory of Open Access Journals (Sweden)

    Adão Felipe Oliveira Skonieski

    2013-01-01

    Full Text Available Plasma nitriding is a surface modification process that uses glow discharge to diffuse nitrogen atoms into the metallic matrix of different materials. Among the many possible parameters of the process, the gas mixture composition plays an important role, as it impacts directly the formed layer's microstructure. In this work an AISI 4140 steel was plasma nitrided under five different gas compositions. The plasma nitriding samples were characterized using optical and scanning electron microscopy, microhardness test, X-ray diffraction and GDOES. The results showed that there are significant microstructural and morphological differences on the formed layers depending on the quantity of nitrogen and methane added to the plasma nitriding atmosphere. Thicknesses of 10, 5 and 2.5 µm were obtained when the nitrogen content of the gas mixtures were varied. The possibility to obtain a compound layer formed mainly by γ'-Fe4N nitrides was also shown. For all studied plasma nitriding conditions, the presence of a compound layer was recognized as being the responsible to hinder the decarburization on the steel surface. The highest value of surface hardness - 1277HV - were measured in the sample which were nitrided with 3vol.% of CH4.

  8. Plasma Nitriding of 722M24 Steel with Pure Lanthanum, Cerium and Neodymium as Sputter Sources

    Institute of Scientific and Technical Information of China (English)

    张津; 孙勇

    2001-01-01

    A series of experiments were carried out to investigate the influence of pure rare earth addition on the plasma nitriding response of low alloy steel. For this purpose, pure rare earth metals (La, Ce and Nd) were put into the plasma nitriding furnace as sputter sources during nitriding of 722M24 steel. A variety of experimental and analytical techniques were employed to evaluate the structures and hardening response of the nitrided layers which included metallography for structural examination, glow discharge spectrometry and secondary ion mass spectrometry for chemical composition profile analysis, X-ray diffraction for phase identification and microhardness testing for hardness profile measurements. The results show that the incorporation of rare earth metals in the glow discharge during plasma nitriding not only influences the discharge characteristics but also results in the deposition of rare earth atoms and their compounds onto the specimen surface. These significantly affect the response of the investigated steel to plasma nitriding. The extent of the influence on plasma nitriding varies with different rare earth metals.

  9. Synthesis and Characterization of an Iron Nitride Constructed by a Novel Template of Metal Organic Framework

    Directory of Open Access Journals (Sweden)

    Suyan Liu

    2015-01-01

    Full Text Available An iron nitride with high surface area was synthesized from an iron-based metal organic framework (Fe-MOF in this work. During the synthesis process, the Fe-MOF of MIL-53 served as a hard template, a template to impart a certain degree of morphology for iron oxide products and to form porosities for iron nitride products. Moreover, it played the roles of iron sources for the synthesis of the final iron oxides and the iron nitrides. The physicochemical properties of the materials were characterized by a series of technologies including XRD, SEM, and N2-adsorption/desorption. The results showed that the iron nitride synthesized from MIL-53 was α-Fe2-3N. And, the α-Fe2-3N showed the morphology with loosely aggregated particles which favored the formation of rich interparticle porosities. As a result, the surface area of the α-Fe2-3N was larger than those of samples using α-Fe2O3 as precursors and its value was 41 m2/g. In addition, the results agreed that both raw material properties (such as crystallinity and surface areas and nitriding approaches had significant effects on the surface areas of iron nitrides. Also the results were proved by the iron oxide synthesized with different methods. This new synthetic strategy could be a general approach for the preparation of late transition metal nitrides with peculiar properties.

  10. Sulfide Stress Cracking and Electrochemical Corrosion of Precipitation Hardening Steel After Plasma Oxy-Nitriding

    Science.gov (United States)

    Granda-Gutiérrez, E. E.; Díaz-Guillén, J. C.; Díaz-Guillén, J. A.; González, M. A.; García-Vázquez, F.; Muñóz, R.

    2014-11-01

    In this paper, we present the results of a duplex plasma nitriding followed by an oxidizing stage process (which is also referred as oxy-nitriding) on the corrosion behavior of a 17-4PH precipitation hardening stainless steel. The formation of both, expanded martensite (b.c.t. α'N-phase) and chromium oxide (type Cr2O3) in the subsurface of oxy-nitrided samples at specific controlled conditions, leads in a noticeable increasing in the time-to-rupture during the sulfide stress cracking test, in comparison with an untreated reference sample. Oxy-nitriding improves the corrosion performance of the alloy when it is immersed in solutions saturated by sour gas, which extends the application potential of this type of steel in the oil and gas extraction and processing industry. The presence of the oxy-nitrided layer inhibits the corrosion process that occurs in the near-surface region, where hydrogen is liberated after the formation of iron sulfides, which finally produces a fragile fracture by micro-crack propagation; the obtained results suggest that oxy-nitriding slows this process, thus delaying the rupture of the specimen. Moreover, oxy-nitriding produces a hard, sour gas-resistant surface, but do not significantly affect the original chloride ion solution resistance of the material.

  11. Silver Nanoparticle-Deposited Boron Nitride Nanosheets as Fillers for Polymeric Composites with High Thermal Conductivity

    Science.gov (United States)

    Wang, Fangfang; Zeng, Xiaoliang; Yao, Yimin; Sun, Rong; Xu, Jianbin; Wong, Ching-Ping

    2016-01-01

    Polymer composites with high thermal conductivity have recently attracted much attention, along with the rapid development of the electronic devices toward higher speed and performance. However, a common method to enhance polymer thermal conductivity through an addition of high thermally conductive fillers usually cannot provide an expected value, especially for composites requiring electrical insulation. Here, we show that polymeric composites with silver nanoparticle-deposited boron nitride nanosheets as fillers could effectively enhance the thermal conductivity of polymer, thanks to the bridging connections of silver nanoparticles among boron nitride nanosheets. The thermal conductivity of the composite is significantly increased from 1.63 W/m-K for the composite filled with the silver nanoparticle-deposited boron nitride nanosheets to 3.06 W/m-K at the boron nitride nanosheets loading of 25.1 vol %. In addition, the electrically insulating properties of the composite are well preserved. Fitting the measured thermal conductivity of epoxy composite with one physical model indicates that the composite with silver nanoparticle-deposited boron nitride nanosheets outperforms the one with boron nitride nanosheets, owning to the lower thermal contact resistance among boron nitride nanosheets’ interfaces. The finding sheds new light on enhancement of thermal conductivity of the polymeric composites which concurrently require the electrical insulation. PMID:26783258

  12. Titanium Matrix Composite Ti/TiN Produced by Diode Laser Gas Nitriding

    Directory of Open Access Journals (Sweden)

    Aleksander Lisiecki

    2015-01-01

    Full Text Available A high power direct diode laser, emitting in the range of near infrared radiation at wavelength 808–940 nm, was applied to produce a titanium matrix composite on a surface layer of titanium alloy Ti6Al4V by laser surface gas nitriding. The nitrided surface layers were produced as single stringer beads at different heat inputs, different scanning speeds, and different powers of laser beam. The influence of laser nitriding parameters on the quality, shape, and morphology of the surface layers was investigated. It was found that the nitrided surface layers consist of titanium nitride precipitations mainly in the form of dendrites embedded in the titanium alloy matrix. The titanium nitrides are produced as a result of the reaction between molten Ti and gaseous nitrogen. Solidification and subsequent growth of the TiN dendrites takes place to a large extent at the interface of the molten Ti and the nitrogen gas atmosphere. The direction of TiN dendrites growth is perpendicular to the surface of molten Ti. The roughness of the surface layers depends strongly on the heat input of laser nitriding and can be precisely controlled. In spite of high microhardness up to 2400 HV0.2, the surface layers are crack free.

  13. Facile preparation and multifunctional applications of boron nitride quantum dots

    Science.gov (United States)

    Lei, Zhouyue; Xu, Shengjie; Wan, Jiaxun; Wu, Peiyi

    2015-11-01

    Boron nitride quantum dots are obtained by a facile sonication-solvothermal technique. They are proven to be promising fluorescent bioimaging probes for bioimaging with remarkably low cytotoxicity and easily integrated into high-performance proton exchange membranes. This work will probably trigger research interest in BN and its new applications in a variety of fields.Boron nitride quantum dots are obtained by a facile sonication-solvothermal technique. They are proven to be promising fluorescent bioimaging probes for bioimaging with remarkably low cytotoxicity and easily integrated into high-performance proton exchange membranes. This work will probably trigger research interest in BN and its new applications in a variety of fields. Electronic supplementary information (ESI) available: AFM images of BN nanosheets, TEM, HRTEM and AFM images of BN QDs prepared in DMSO, digital photographs of DMF, DMSO, DMF with the addition of BN raw materials and DMSO with the addition of BN raw materials, UV-vis and FTIR spectra of the BN QDs, cell viability of the BN QDs, a summary of cell viabilities of different fluorescent QDs, digital photographs and CLSM images of the as-prepared PEMs, TGA and DSC curves of the PEMs, and AFM images of the PEMs. See DOI: 10.1039/c5nr05960g

  14. Titanium Nitride and Nitrogen Ion Implanted Coated Dental Materials

    Directory of Open Access Journals (Sweden)

    David W. Berzins

    2012-07-01

    Full Text Available Titanium nitride and/or nitrogen ion implanted coated dental materials have been investigated since the mid-1980s and considered in various applications in dentistry such as implants, abutments, orthodontic wires, endodontic files, periodontal/oral hygiene instruments, and casting alloys for fixed restorations. Multiple methodologies have been employed to create the coatings, but detailed structural analysis of the coatings is generally lacking in the dental literature. Depending on application, the purpose of the coating is to provide increased surface hardness, abrasion/wear resistance, esthetics, and corrosion resistance, lower friction, as well as greater beneficial interaction with adjacent biological and material substrates. While many studies have reported on the achievement of these properties, a consensus is not always clear. Additionally, few studies have been conducted to assess the efficacy of the coatings in a clinical setting. Overall, titanium nitride and/or nitrogen ion implanted coated dental materials potentially offer advantages over uncoated counterparts, but more investigation is needed to document the structure of the coatings and their clinical effectiveness.

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

    Science.gov (United States)

    Alizadeh, Zhila

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

  16. Advanced optical modelling of dynamically deposited silicon nitride layers

    Science.gov (United States)

    Borojevic, N.; Hameiri, Z.; Winderbaum, S.

    2016-07-01

    Dynamic deposition of silicon nitrides using in-line plasma enhanced chemical vapor deposition systems results in non-uniform structure of the dielectric layer. Appropriate analysis of such layers requires the optical characterization to be performed as a function of the layer's depth. This work presents a method to characterize dynamically deposited silicon nitride layers. The method is based on the fitting of experimental spectroscopic ellipsometry data via grading of Tauc-Lorentz optical parameters through the depth of the layer. When compared with the standard Tauc-Lorentz fitting procedure, used in previous studies, the improved method is demonstrating better quality fits to the experimental data and revealing more accurate optical properties of the dielectric layers. The most significant advantage of the method is the ability to extract the depth profile of the optical properties along the direction of the layer normal. This is enabling a better understanding of layers deposited using dynamic plasma enhanced chemical vapor deposition systems frequently used in the photovoltaic industry.

  17. Kinetics and thermodynamics of Si(111) surface nitridation in ammonia

    Science.gov (United States)

    Mansurov, Vladimir G.; Malin, Timur V.; Galitsyn, Yurij G.; Shklyaev, Alexander A.; Zhuravlev, Konstantin S.

    2016-05-01

    Kinetics and thermodynamics of Si(111) surface nitridation under an ammonia flux at different substrate temperatures are investigated by reflection high-energy electron diffraction. Two different stages of the nitridation process were revealed. The initial stage is the fast (within few seconds) formation of ordered two-dimensional SiN phase, occuring due to the topmost active surface Si atom (Sisurf) interaction with ammonia molecules. It is followed by the late stage consisting in the slow (within few minutes) amorphous Si3N4 phase formation as a result of the interaction of Si atoms in the lattice site (Siinc) with chemisorbed ammonia molecules. It was found that the ordered SiN phase formation rate decreases, as the temperature increases. The kinetic model of the initial stage was developed, in which the ordered SiN phase formation is the two-dimensional phase transition in the lattice gas with SiN cells. The enthalpy of the active surface Si atom generation on the clean Si(111) surface was estimated to be about 1.5 eV. In contrast, the amorphous Si3N4 phase formation is the normal (thermally activated) chemical process with the first-order kinetics, whose activation energy and pre-exponential factor are 2.4 eV and 108 1/s, respectively.

  18. Synthesis of amorphous carbon nitride by ion implantation

    Institute of Scientific and Technical Information of China (English)

    ChenZ.; OlofinjanaA.; BellJ

    2001-01-01

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

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

    Science.gov (United States)

    Hankel, Marlies; Searles, Debra J

    2016-06-01

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

  20. Mechanochemical route to the synthesis of nanostructured Aluminium nitride

    Science.gov (United States)

    Rounaghi, S. A.; Eshghi, H.; Scudino, S.; Vyalikh, A.; Vanpoucke, D. E. P.; Gruner, W.; Oswald, S.; Kiani Rashid, A. R.; Samadi Khoshkhoo, M.; Scheler, U.; Eckert, J.

    2016-01-01

    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN. PMID:27650956

  1. The precipitation and effect of nano nitrides in HSLC steel

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The existing forms of N and Al in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process), the precipitation thermodynamics and kinetics of AlN, and its effects on structure and mechanical property are studied. The experimental results show that only a small quantity of nitrogen is com- bined into AlN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen. Aluminum-nitride is mainly precipitated during the period of slow air cooling after coiling, but not during rolling and water cooling. The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005%―0.043%. The precipitation of AlN is not the main cause of grain refinement of HSLC steel produced by TSCR, nor is AlN the dominating precipitate that has precipitation strengthening effect. The nano nitrides are not pure AlN, but have complex compositions.

  2. The precipitation and effect of nano nitrides in HSLC steel

    Institute of Scientific and Technical Information of China (English)

    FU Jiei; LIU YangChun; WU HuaJie

    2008-01-01

    The existing forms of N and AI in HSLC (high strength low carbon) steel produced by TSCR (thin slab casting and rolling process),the precipitation thermodynamics and kinetics of AIN,and its effects on structure and mechanical property are stud-ied.The experimental results show that only a small quantity of nitrogen is com-bined into AIN in HSLC steel produced by TSCR and most of the nitrogen in steel is still free nitrogen.AIuminum-nitride is mainly precipitated during the period of slow air cooling after coiling,but not during rolling and water cooling.The acid-soluble aluminum has no obvious effect on the grain size and mechanical property of HSLC steel produced by TSCR whose acid-soluble aluminum content is 0.005%-0.043%.The precipitation of AIN is not the main cause of grain refinement of HSLC steel produced by TSCR,nor is AIN the dominating precipitate that has precipitation strengthening effect.The nano nitrides are not pure AIN,but have complex compositions.

  3. Dimensional Crossover of Thermal Transport in Hybrid Boron Nitride Nanostructures.

    Science.gov (United States)

    Sakhavand, Navid; Shahsavari, Rouzbeh

    2015-08-26

    Although boron nitride nanotubes (BNNT) and hexagonal-BN (hBN) are superb one-dimensional (1D) and 2D thermal conductors respectively, bringing this quality into 3D remains elusive. Here, we focus on pillared boron nitride (PBN) as a class of 3D BN allotropes and demonstrate how the junctions, pillar length and pillar distance control phonon scattering in PBN and impart tailorable thermal conductivity in 3D. Using reverse nonequilibrium molecular dynamics simulations, our results indicate that although a clear phonon scattering at the junctions accounts for the lower thermal conductivity of PBN compared to its parent BNNT and hBN allotropes, it acts as an effective design tool and provides 3D thermo-mutable features that are absent in the parent structures. Propelled by the junction spacing, while one geometrical parameter, e.g., pillar length, controls the thermal transport along the out-of-plane direction of PBN, the other parameter, e.g., pillar distance, dictates the gross cross-sectional area, which is key for design of 3D thermal management systems. Furthermore, the junctions have a more pronounced effect in creating a Kapitza effect in the out-of-plane direction, due to the change in dimensionality of the phonon transport. This work is the first report on thermo-mutable properties of hybrid BN allotropes and can potentially impact thermal management of other hybrid 3D BN architectures. PMID:26158661

  4. Mechanochemical route to the synthesis of nanostructured Aluminium nitride

    Science.gov (United States)

    Rounaghi, S. A.; Eshghi, H.; Scudino, S.; Vyalikh, A.; Vanpoucke, D. E. P.; Gruner, W.; Oswald, S.; Kiani Rashid, A. R.; Samadi Khoshkhoo, M.; Scheler, U.; Eckert, J.

    2016-09-01

    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN.

  5. Study of aluminum nitride precipitation in Fe- 3%Si steel

    Directory of Open Access Journals (Sweden)

    F.L. Alcântara

    2013-01-01

    Full Text Available For good performance of electrical steels it is necessary a high magnetic induction and a low power loss when submitted to cyclic magnetization. A fine dispersion of precipitates is a key requirement in the manufacturing process of Fe- 3%Si grain oriented electrical steel. In the production of high permeability grain oriented steel precipitate particles of copper and manganese sulphides and aluminium nitride delay normal grain growth during primary recrystallization, causing preferential growth of grains with Goss orientation during secondary recrystallization. The sulphides precipitate during the hot rolling process. The aluminium nitride particles are formed during hot rolling and the hot band annealing process. In this work AlN precipitation during hot deformation of a high permeability grain oriented 3%Si steel is examined. In the study, transfer bar samples were submitted to controlled heating, compression and cooling treatments in order to simulate a reversible hot rolling finishing. The samples were analyzed using the transmission electron microscope (TEM in order to identify the precipitates and characterize size distribution. Precipitate extraction by dissolution method and analyses by inductively coupled plasma optical emission spectrometry (ICP-OES were used to quantify the precipitation. The results allowed to describe the precipitation kinetics by a precipitation-time-temperature (PTT diagram for AlN formation during hot rolling.

  6. Mechanochemical route to the synthesis of nanostructured Aluminium nitride.

    Science.gov (United States)

    Rounaghi, S A; Eshghi, H; Scudino, S; Vyalikh, A; Vanpoucke, D E P; Gruner, W; Oswald, S; Kiani Rashid, A R; Samadi Khoshkhoo, M; Scheler, U; Eckert, J

    2016-09-21

    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN.

  7. Progress in Group Ⅲ nitride semiconductor electronic devices

    Institute of Scientific and Technical Information of China (English)

    Hao Yue; Zhang Jinfeng; Shen Bo; Liu Xinyu

    2012-01-01

    Recently there has been a rapid domestic development in group Ⅲ nitride semiconductor electronic materials and devices.This paper reviews the important progress in GaN-based wide bandgap microelectronic materials and devices in the Key Program of the National Natural Science Foundation of China,which focuses on the research of the fundamental physical mechanisms of group Ⅲ nitride semiconductor electronic materials and devices with the aim to enhance the crystal quality and electric performance of GaN-based electronic materials,develop new GaN heterostructures,and eventually achieve high performance GaN microwave power devices.Some remarkable progresses achieved in the program will be introduced,including those in GaN high electron mobility transistors (HEMTs) and metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with novel high-k gate insulators,and material growth,defect analysis and material properties of InAlN/GaN heterostructures and HEMT fabrication,and quantum transport and spintronic properties ofGaN-based heterostructures,and highelectric-field electron transport properties of GaN material and GaN Gunn devices used in terahertz sources.

  8. Mechanochemical route to the synthesis of nanostructured Aluminium nitride.

    Science.gov (United States)

    Rounaghi, S A; Eshghi, H; Scudino, S; Vyalikh, A; Vanpoucke, D E P; Gruner, W; Oswald, S; Kiani Rashid, A R; Samadi Khoshkhoo, M; Scheler, U; Eckert, J

    2016-01-01

    Hexagonal Aluminium nitride (h-AlN) is an important wide-bandgap semiconductor material which is conventionally fabricated by high temperature carbothermal reduction of alumina under toxic ammonia atmosphere. Here we report a simple, low cost and potentially scalable mechanochemical procedure for the green synthesis of nanostructured h-AlN from a powder mixture of Aluminium and melamine precursors. A combination of experimental and theoretical techniques has been employed to provide comprehensive mechanistic insights on the reactivity of melamine, solid state metal-organic interactions and the structural transformation of Al to h-AlN under non-equilibrium ball milling conditions. The results reveal that melamine is adsorbed through the amine groups on the Aluminium surface due to the long-range van der Waals forces. The high energy provided by milling leads to the deammoniation of melamine at the initial stages followed by the polymerization and formation of a carbon nitride network, by the decomposition of the amine groups and, finally, by the subsequent diffusion of nitrogen into the Aluminium structure to form h-AlN. PMID:27650956

  9. Diverse ruthenium nitrides stabilized under pressure: a theoretical prediction.

    Science.gov (United States)

    Zhang, Yunkun; Wu, Lailei; Wan, Biao; Lin, Yangzheng; Hu, Qingyang; Zhao, Yan; Gao, Rui; Li, Zhiping; Zhang, Jingwu; Gou, Huiyang

    2016-01-01

    First-principles calculations were performed to understand the structural stability, synthesis routes, mechanical and electronic properties of diverse ruthenium nitrides. RuN with a new I-4m2 symmetry stabilized by pressure is found to be energetically preferred over the experimental NaCl-type and ZnS-type ones. The Pnnm-RuN2 is found to be stable above 1.1 GPa, in agreement with the experimental results. Specifically, new stoichiometries like RuN3 and RuN4 are proposed firstly to be thermodynamically stable, and the dynamical and mechanical stabilities of the newly predicted structures have been verified by checking their phonon spectra and elastic constants. A phase transition from P4/mmm-RuN4 to C2/c-RuN4 is also uncovered at 23.0 GPa. Drawn from bonding and band structure analysis, P4/mmm-RuN4 exhibits semi-metal-like behavior and becomes a semiconductor for the high-pressure C2/c-RuN4 phase. Meanwhile the P21/c-RuN3 shows metallic feature. Highly directional covalent N-N and Ru-N bonds are formed and dominating in N-enriched Ru nitrides, making them promising hard materials. PMID:27627856

  10. Chemical Sharpening, Shortening, and Unzipping of Boron Nitride Nanotubes

    Science.gov (United States)

    Liao, Yunlong; Chen, Zhongfang; Connell, John W.; Fay, Catharine C.; Park, Cheol; Kim, Jae-Woo; Lin, Yi

    2014-01-01

    Boron nitride nanotubes (BNNTs), the one-dimensional member of the boron nitride nanostructure family, are generally accepted to be highly inert to oxidative treatments and can only be covalently modifi ed by highly reactive species. Conversely, it is discovered that the BNNTs can be chemically dispersed and their morphology modifi ed by a relatively mild method: simply sonicating the nanotubes in aqueous ammonia solution. The dispersed nanotubes are significantly corroded, with end-caps removed, tips sharpened, and walls thinned. The sonication treatment in aqueous ammonia solution also removes amorphous BN impurities and shortened BNNTs, resembling various oxidative treatments of carbon nanotubes. Importantly, the majority of BNNTs are at least partially longitudinally cut, or "unzipped". Entangled and freestanding BN nanoribbons (BNNRs), resulting from the unzipping, are found to be approximately 5-20 nm in width and up to a few hundred nanometers in length. This is the fi rst chemical method to obtain BNNRs from BNNT unzipping. This method is not derived from known carbon nanotube unzipping strategies, but is unique to BNNTs because the use of aqueous ammonia solutions specifi cally targets the B-N bond network. This study may pave the way for convenient processing of BNNTs, previously thought to be highly inert, toward controlling their dispersion, purity, lengths, and electronic properties.

  11. Vertical transport in graphene-hexagonal boron nitride heterostructure devices

    Science.gov (United States)

    Bruzzone, Samantha; Logoteta, Demetrio; Fiori, Gianluca; Iannaccone, Giuseppe

    2015-09-01

    Research in graphene-based electronics is recently focusing on devices based on vertical heterostructures of two-dimensional materials. Here we use density functional theory and multiscale simulations to investigate the tunneling properties of single- and double-barrier structures with graphene and few-layer hexagonal boron nitride (h-BN) or hexagonal boron carbon nitride (h-BC2N). We find that tunneling through a single barrier exhibit a weak dependence on energy. We also show that in double barriers separated by a graphene layer we do not observe resonant tunneling, but a significant increase of the tunneling probability with respect to a single barrier of thickness equal to the sum of the two barriers. This is due to the fact that the graphene layer acts as an effective phase randomizer, suppressing resonant tunneling and effectively letting a double-barrier structure behave as two single-barriers in series. Finally, we use multiscale simulations to reproduce a current-voltage characteristics resembling that of a resonant tunneling diode, that has been experimentally observed in single barrier structure. The peak current is obtained when there is perfect matching between the densities of states of the cathode and anode graphene regions.

  12. The interaction between nitride uranium and stainless steel

    Science.gov (United States)

    Shornikov, D. P.; Nikitin, S. N.; Tarasov, B. A.; Baranov, V. G.; Yurlova, M. S.

    2016-04-01

    Uranium nitride is most popular nuclear fuel for Fast Breeder Reactor New Generation. In-pile experiments at reactor BOR-60 was shown an interaction between nitride fuel and stainless steel in the range of 8-11% burn up (HA). In order to investigate this interaction has been done diffusion tests of 200 h and has been shown that the reaction occurs in the temperature range 1000-1100 ° C. UN interacted with steel in case of high pollution oxygen (1000-2000 ppm). Also has been shown to increase interaction UN with EP-823 steel in the presence of cesium. In this case the interaction layer had a thickness about 2-3 μm. Has been shown minimal interaction with new ODS steel EP-450. The interaction layer had a thickness less then 2 μm. Did not reveal the influence of tellurium and iodine increased interaction. It was show compatibility at 1000 °C between UN and EP-450 ODS steel, chrome steel, alloying aluminium and silicium.

  13. Diverse ruthenium nitrides stabilized under pressure: a theoretical prediction

    Science.gov (United States)

    Zhang, Yunkun; Wu, Lailei; Wan, Biao; Lin, Yangzheng; Hu, Qingyang; Zhao, Yan; Gao, Rui; Li, Zhiping; Zhang, Jingwu; Gou, Huiyang

    2016-09-01

    First-principles calculations were performed to understand the structural stability, synthesis routes, mechanical and electronic properties of diverse ruthenium nitrides. RuN with a new I-4m2 symmetry stabilized by pressure is found to be energetically preferred over the experimental NaCl-type and ZnS-type ones. The Pnnm-RuN2 is found to be stable above 1.1 GPa, in agreement with the experimental results. Specifically, new stoichiometries like RuN3 and RuN4 are proposed firstly to be thermodynamically stable, and the dynamical and mechanical stabilities of the newly predicted structures have been verified by checking their phonon spectra and elastic constants. A phase transition from P4/mmm-RuN4 to C2/c-RuN4 is also uncovered at 23.0 GPa. Drawn from bonding and band structure analysis, P4/mmm-RuN4 exhibits semi-metal-like behavior and becomes a semiconductor for the high-pressure C2/c-RuN4 phase. Meanwhile the P21/c-RuN3 shows metallic feature. Highly directional covalent N-N and Ru-N bonds are formed and dominating in N-enriched Ru nitrides, making them promising hard materials.

  14. Band gap effects of hexagonal boron nitride using oxygen plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sevak Singh, Ram; Leong Chow, Wai [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Yingjie Tay, Roland [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Temasek Laboratories-NTU, 50 Nanyang Avenue, Singapore 639798 (Singapore); Hon Tsang, Siu [Temasek Laboratories-NTU, 50 Nanyang Avenue, Singapore 639798 (Singapore); Mallick, Govind [Temasek Laboratories-NTU, 50 Nanyang Avenue, Singapore 639798 (Singapore); Weapons and Materials Research Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005 (United States); Tong Teo, Edwin Hang, E-mail: htteo@ntu.edu.sg [School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2014-04-21

    Tuning of band gap of hexagonal boron nitride (h-BN) has been a challenging problem due to its inherent chemical stability and inertness. In this work, we report the changes in band gaps in a few layers of chemical vapor deposition processed as-grown h-BN using a simple oxygen plasma treatment. Optical absorption spectra show a trend of band gap narrowing monotonically from 6 eV of pristine h-BN to 4.31 eV when exposed to oxygen plasma for 12 s. The narrowing of band gap causes the reduction in electrical resistance by ∼100 fold. The x-ray photoelectron spectroscopy results of plasma treated hexagonal boron nitride surface show the predominant doping of oxygen for the nitrogen vacancy. Energy sub-band formations inside the band gap of h-BN, due to the incorporation of oxygen dopants, cause a red shift in absorption edge corresponding to the band gap narrowing.

  15. Nitride capacity of refining glass for high-nitrogen steels

    International Nuclear Information System (INIS)

    The solubility of nitrogen in molten oxides has important implications for a knowledge of the role of nitrogen in slags for refining high nitrogen stainless steels. The nitride capacity, C/sub n/, measured by gas-slag equilibration technique is determined as a function of composition. C/sub N/ is constant with increasing basicity for different basicity parameters. The nitrogen partition ratio between stainless steel and the slag using slag metal equilibration was measured in N/sub 2/-CO at 1600 deg. C. By comparing the partition ratios with the corresponding nitride capacities measured by gas slag experiments, it was concluded that the oxygen potential at the slag-metal interface was controlled by the Fe-FeO and Mn-MnO reaction. Existing knowledge on interaction parameters is utilized to predict nitrogen solubility in laboratory alloys, and activities of SiO/sub 2/ and Al/sub 2/O/sub 3/ are also discussed along with the refining characteristics of the oxide systems investigated. (author)

  16. Plasma nitriding as a prevention method against hydrogen degradation of steel

    Directory of Open Access Journals (Sweden)

    J. Ćwiek

    2009-09-01

    Full Text Available Purpose: of this paper is evaluation of susceptibility to hydrogen degradation of structural low-alloy steel, plasma nitrided in the atmosphere with various contents of N2 and H2.Design/methodology/approach: Susceptibility of 34CrAlNi7-10 steel and samples with various plasma nitrided layers have been evaluated under monotonically increasing load in 0.005 M H2SO4 solution. The nitrided layers were investigated with the use of an X-ray Photoelectron Spectroscopy (XPS and Auger Electrons Spectroscopy (AES. Slow-Strain Rate Tensile (SSRT test was carried out under cathodic polarisation. Elongation, reduction in area, fracture energy and tensile strength were chosen as measures of susceptibility to hydrogen embrittlement. Fracture modes of failed samples were examined with the use of Scanning Electron Microscope (SEM.Findings: All tested samples revealed susceptibility to hydrogen degradation under hydrogenation. Samples with nitrided layer have lower lost of reduction in area than base metal samples. The nitrided layer established in standard atmosphere 30% H2 and 70% N2 has the highest resistance to hydrogen degradation.Research limitations/implications: Further research should be taken to reveal the exact mechanism of increased plasticity of nitrided layer with absorbed hydrogen.Practical implications: Plasma nitriding may prevent hydrogen charging of machines and vehicles parts in hydrogen generating environments, and thus decreasing susceptibility to hydrogen embrittlement.Originality/value: Under the increasing load and hydrogen generating environments plasma nitrided layers are effective barriers to hydrogen entry into a bulk of steel, and additionally increased plasticity of nitrided layers with absorbed hydrogen has been observed.

  17. Effect of SPD surface layer on plasma nitriding of Ti–6Al–4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Farokhzadeh, K.; Qian, J.; Edrisy, A., E-mail: edrisy@uwindsor.ca

    2014-01-01

    A severe plastic deformation (SPD) surface layer was introduced by shot peening to enhance the nitriding kinetics in low-temperature (600 °C) plasma nitriding of Ti–6Al–4V alloy. The effect of this pretreatment on the nitrided microstructures and phase compositions was investigated by analytical microscopy techniques e.g. scanning and transmission electron microscopy (SEM, TEM) and X-ray diffraction (XRD) analysis. Microstructural investigations revealed the formation of a compound layer consisting of a 0.6 µm thick nanocrystalline TiN layer followed by a 0.5 µm thick layer of Ti{sub 2}N with a larger grain size (0.1–0.5 µm). The development of TiN nanograins was attributed to accelerated nitriding kinetics due to the increased preferential nucleation sites in the SPD layer. Furthermore, the thickness of nitrogen diffusion zone (DZ) increased by 50% in the pretreated plasma nitrided alloy when compared with that of the untreated one. This is likely promoted by an increase in density of subsurface microstructural defects, such as twins and grain boundaries. The sliding behaviour and interfacial adhesion of the nitrided surfaces were evaluated by micro-scratch tests within a load range of 1–20 N. Compared with untreated-plasma-nitrided alloy, the pretreated nitrided surfaces exhibited a higher load bearing capacity and better interfacial bonding. They exhibited no chipping or spallation, even after multiple sliding passes at the highest applied load of 20 N in contrary to the untreated plasma nitrided surfaces.

  18. Optical frequency comb generation from aluminum nitride micro-ring resonator

    CERN Document Server

    Jung, Hojoong; Fong, King Y; Zhang, Xufeng; Tang, Hong X

    2013-01-01

    Aluminum nitride is an appealing nonlinear optical material for on-chip wavelength conversion. Here we report optical frequency comb generation from high quality factor aluminum nitride micro-ring resonators integrated on silicon substrates. By engineering the waveguide structure to achieve near-zero dispersion at telecommunication wavelengths and optimizing the phase matching for four-wave mixing, frequency combs are generated with a single wavelength continuous-wave pump laser. The Kerr coefficient (n2) of aluminum nitride is further extracted from our experimental results.

  19. Use of high-thermal conductive aluminum nitride based ceramics in vacuum UHF electronic devices

    Directory of Open Access Journals (Sweden)

    Chasnyk V. I.

    2013-06-01

    Full Text Available Analysis of properties and characteristics of the alumina, beryllium oxide and aluminum nitride based ceramic materials used in UHF electronic devices has been made. It was shown that the complex of parameters including structural and functional characteristics of the high-thermal conductive aluminum nitride ceramics prevail over all types of alumina ceramics and is not lower than the same characteristics of the beryllium oxide ceramics especially at the temperatures higher than 450 °C. The examples of the prevailing use of the aluminum nitride ceramics inside vacuum UHF-region devices: TWT’s and klystrons.

  20. Rapid Microwave Synthesis, Characterization and Reactivity of Lithium Nitride Hydride, Li4NH

    OpenAIRE

    Nuria Tapia-Ruiz; Natalie Sorbie; Nicolas Vaché; Hoang, Tuan K. A.; Gregory, Duncan H.

    2013-01-01

    Lithium nitride hydride, Li4NH, was synthesised from lithium nitride and lithium hydride over minute timescales, using microwave synthesis methods in the solid state for the first time. The structure of the microwave-synthesised powders was confirmed by powder X-ray diffraction [tetragonal space group I41/a; a = 4.8864(1) Å, c = 9.9183(2) Å] and the nitride hydride reacts with moist air under ambient conditions to produce lithium hydroxide and subsequently lithium carbonate. Li4NH undergoes n...

  1. Analysis of the growth of concomitant nitride layers produced by a post-discharge assisted process

    Energy Technology Data Exchange (ETDEWEB)

    Oseguera, J. [ITESM-CEM, Carretera al Lago de Guadalupe km. 3.5 Atizapan, 52926 (Mexico)]. E-mail: joseguer@itesm.mx; Castillo, F. [ITESM-CEM, Carretera al Lago de Guadalupe km. 3.5 Atizapan, 52926 (Mexico); Gomez, A. [UFRO, Av. Francisco Salazar 01145, Temuco, Casilla 54-d (Chile); Fraguela, A. [BUAP, Rio Verde y Ave. San Claudio, San Manuel, Puebla, 72570 (Mexico)

    2006-11-23

    In the present work, the growth of concomitant nitride layers during a post-discharge process is studied. The analysis takes into account the similarities and differences between nitriding post-discharge processes and other nitriding processes, employing a mathematical simulation of nitrogen diffusion. The considered differences are related to the thermodynamic standard states, the nitrogen concentration on the surface and the sputtering of the surface (this one for plasma processes). Nitrogen diffusion and layer formation are described from the beginning of the process by means of a mathematical model.

  2. Titanium Matrix Composite Ti/TiN Produced by Diode Laser Gas Nitriding

    OpenAIRE

    Aleksander Lisiecki

    2015-01-01

    A high power direct diode laser, emitting in the range of near infrared radiation at wavelength 808–940 nm, was applied to produce a titanium matrix composite on a surface layer of titanium alloy Ti6Al4V by laser surface gas nitriding. The nitrided surface layers were produced as single stringer beads at different heat inputs, different scanning speeds, and different powers of laser beam. The influence of laser nitriding parameters on the quality, shape, and morphology of the surface layers w...

  3. Effect of Nitriding on Fatigue Characteristics of Cr-Mo Alloy Steel

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Kwang Keun; Kim, Jae Hoon; Choi, Hoon Seok [Chungnam National University, Daejeon (Korea, Republic of)

    2015-06-15

    CrMo alloy steel was nitrided using two types of processing methods, ion-nitriding processing and nitrocarburizing. Both processes were conducted for a duration of 30 min. To compare the surface hardness of the alloys created by the different processes , microhardness tests were conducted, and fatigue tests of each material were performed by a cantilever rotary bending fatigue test machine (Yamamoto, YRB 200) in the very high cycle regime (N > 10{sup 7}cycle). Fractography of the fractured surfaces was conducted by scanning electron microscopy - to observe the fracture mechanisms of very high cycle fatigue and the effect of the nitriding process on the fatigue characteristics.

  4. Experimental Research on Residual Stress in Surface of Silicon Nitride Ceramic Balls

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The influence of the residual stress in surface of ceramic balls on the fatigue life is large, because the life of silicon nitride ball bearings is more sensitive to the load acted on the bearings than the life of all-steel ball bearings. In this paper, the influence of thermal stress produced in sintering and mechanical stress formed in lapping process on residual stress in surface of silicon nitride ceramic balls was discussed. The residual compress stress will be formed in the surface of silicon nitride ...

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

    Science.gov (United States)

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

    2015-04-13

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

  6. Nitridation process effect on crystal structure and magnetic properties of TbCu7-type SmFe9 alloys

    Institute of Scientific and Technical Information of China (English)

    吕彬彬; 于敦波; 张世荣; 罗阳; 靳金玲; 闫文龙; 李红卫

    2013-01-01

    The effect of nitridation process, i.e. temperature and time, on crystal structure and magnetic properties of SmFe9Nx inter-stitial compounds was systematically investigated. After nitridation treatment, nitrogen atoms were incorporated into SmFe9 alloys to form SmFe9Nx interstitial compounds, which increased the distance of Fe-Fe and enhanced Fe-Fe interaction. As a result, SmFe9Nx interstitial compounds had a higher Curie temperature and more excellent magnetic properties than SmFe9 alloys. The relationships between nitridation temperature, nitridation time, nitriding efficiency, magnetic properties and phase transition were researched. It could be concluded that nitriding efficiency was strongly associated with magnetic properties and phase transition at different tem-peratures. The nitriding efficiency also had a connection with magnetic properties under different time, while no obvious phase transi-tion was found during that process. By studying nitridation process under a series of temperatures and time in this experiment, a suit-able nitridation temperature (713 K) and an ideal length of nitridation time (8 h) was decided, which would produce the optimal mag-netic behavior of SmFe9Nx interstitial compounds.

  7. Effects of Temperature on Microstructure and Wear of Salt Bath Nitrided 17-4PH Stainless Steel

    Science.gov (United States)

    Wang, Jun; Lin, Yuanhua; Fan, Hongyuan; Zeng, Dezhi; Peng, Qian; Shen, Baoluo

    2012-08-01

    Salt bath nitriding of 17-4 PH martensitic precipitation hardening stainless steels was conducted at 610, 630, and 650 °C for 2 h using a complex salt bath heat-treatment, and the properties of the nitrided surface were systematically evaluated. Experimental results revealed that the microstructure and phase constituents of the nitrided surface alloy are highly process condition dependent. When 17-4PH stainless steel was subjected to complex salt bathing nitriding, the main phase of the nitrided layer was expanded martensite (α'), expanded austenite (γN), CrN, Fe4N, and (Fe,Cr) x O y . In the sample nitrided above 610 °C, the expanded martensite transformed into expanded austenite. But in the sample nitrided at 650 °C, the expanded austenite decomposed into αN and CrN. The decomposed αN then disassembled into CrN and alpha again. The nitrided layer depth thickened intensively with the increasing nitriding temperature. The activation energy of nitriding in this salt bath was 125 ± 5 kJ/mol.

  8. Micro and nano-structured green gallium indium nitride/gallium nitride light-emitting diodes

    Science.gov (United States)

    Stark, Christoph J. M.

    Light-emitting diodes (LEDs) are commonly designed and studied based on bulk material properties. In this thesis different approaches based on patterns in the nano and micrometer length scale range are used to tackle low efficiency in the green spectral region, which is known as “green gap”. Since light generation and extraction are governed by microscopic processes, it is instructive to study LEDs with lateral mesa sizes scaled to the nanometer range. Besides the well-known case of the quantum size effect along the growth direction, a continuous lateral scaling could reveal the mechanisms behind the purported absence of a green gap in nanowire LEDs and the role of their extraction enhancement. Furthermore the possibility to modulate strain and piezoelectric polarization by post growth patterning is of practical interest, because the internal electric fields in conventional wurtzite GaN LEDs cause performance problems. A possible alternative is cubic phase GaN, which is free of built-in polarization fields. LEDs on cubic GaN could show the link between strong polarization fields and efficiency roll-off at high current densities, also known as droop. An additional problem for all nitride-based LEDs is efficient light extraction. For a planar GaN LED only roughly 8% of the generated light can be extracted. Novel lightextraction structures with extraction-favoring geometry can yield significant increase in light output power. To investigate the effect of scaling the mesa dimension, micro and nano-sized LED arrays of variable structure size were fabricated. The nano-LEDs were patterned by electron beam lithography and dry etching. They contained up to 100 parallel nano-stripe LEDs connected to one common contact area. The mesa width was varied over 1 μm, 200 nm, and 50 nm. These LEDs were characterized electrically and optically, and the peak emission wavelength was found to depend on the lateral structure size. An electroluminescence (EL) wavelength shift of 3 nm

  9. Plasma nitriding of AISI 304L and AISI 316L stainless steels: effect of time in the formation of S phase and the chromium nitrides; Nitretacao a plasma dos acos inoxidaveis AISI 304L e AISI 316L: efeito do tempo na formacao da fase S e dos nitretos de cromo

    Energy Technology Data Exchange (ETDEWEB)

    Souza, D.A. de; Barbosa, G.C.; Pinto, F.A.M.; Gontijo, L.C. [Instituto Federal de Educacao, Ciencia e Tecnologia do Espirito Santo - IFES, Vitoria, ES (Brazil); Canal, G.P.; Cunha, A.G., E-mail: disouzam@yahoo.com.br [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Dept. de Fisica

    2009-07-01

    Plasma nitriding can improve hardness and wear resistance of austenitic stainless steels without losses in corrosion resistance. This fact relies on a nitrided layer constituted only by S phase, without chromium nitrides precipitation. In this work, the effect of nitriding time on phases formed on nitrided layer was investigated in two austenitic stainless steels: AISI 304L e AISI 316L. The samples were nitrided at 420 deg C, using a mixture of 60 % N{sub 2} and 40% H{sub 2}, during 5, 7 and 9 hours. It was noted that chromium nitrides were formed on samples of AISI 304L, nitrided for 7 e 9 hours, while all nitrided samples of AISI 316L showed only formation of S phase. The nitrided layers were characterized using optical microscope and x-ray diffraction. (author)

  10. An experimental study on the aluminum nitride flux detector

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Byung Soo; Hwang, In Koo; Chung, Chong Eun; Kwon, Kee Choon

    2004-06-01

    The result of a study on the 'development of a solid state flux monitor' performed as a part of the I-NERI project 'development of enhanced reactor operation through improved sensing and control at nuclear power pants' is described in this report. Dozens of aluminum nitride based flux sensors have been fabricated with different sizes 3mm x 3mm x 0.635mm and 3mm x 3mm x 0.381mm by ORNL and were packaged with MGO insulation by KAERI for a feasibility study to use them as the in-core flux monitor in the nuclear power plants. In chapter 1, we describe the basic properties of the aluminum nitride and the geometric shape of the fabricated detectors with the signal cables attached. In chapter 2, we describe the calculation results based on the EGS4 and MCNP4B code to determine the neutron sensitivity of the aluminum nitride and the optimal thickness for the gamma rejection for the case of the detectors being used in the pulse mode operation. In chapter 3, we describe the results of measurements for the insulation resistance and of the experiments to determine the optimum operating voltage of the sensors after the packaging with long cables attached. In chapter 4, we describe the results of experiments to measure the high gamma flux from the 187Ci Co60, 77,000Ci Co60, and the 200,000Ci Co60 at the high level irradiation facility at KAERI at various distances and compared the results with the EGS4 based calculation results. In chapter 5, we describe the results of pulse counts at the IR beam port of the Hanaro reactor, the low flux measurements in the current mode at the Pohang accelerator, and the high flux measurements in the current mode inside the cold neutron source hole of the Hanaro reacter. Finally, in chapter 6, we analyze the results of the above experiments and describe the necessary future work.

  11. Modelling structure and properties of amorphous silicon boron nitride ceramics

    Directory of Open Access Journals (Sweden)

    Johann Christian Schön

    2011-06-01

    Full Text Available Silicon boron nitride is the parent compound of a new class of high-temperature stable amorphous ceramics constituted of silicon, boron, nitrogen, and carbon, featuring a set of properties that is without precedent, and represents a prototypical random network based on chemical bonds of predominantly covalent character. In contrast to many other amorphous materials of technological interest, a-Si3B3N7 is not produced via glass formation, i.e. by quenching from a melt, the reason being that the binary components, BN and Si3N4, melt incongruently under standard conditions. Neither has it been possible to employ sintering of μm-size powders consisting of binary nitrides BN and Si3N4. Instead, one employs the so-called sol-gel route starting from single component precursors such as TADB ((SiCl3NH(BCl2. In order to determine the atomic structure of this material, it has proven necessary to simulate the actual synthesis route.Many of the exciting properties of these ceramics are closely connected to the details of their amorphous structure. To clarify this structure, it is necessary to employ not only experimental probes on many length scales (X-ray, neutron- and electron scattering; complex NMR experiments; IR- and Raman scattering, but also theoretical approaches. These address the actual synthesis route to a-Si3B3N7, the structural properties, the elastic and vibrational properties, aging and coarsening behaviour, thermal conductivity and the metastable phase diagram both for a-Si3B3N7 and possible silicon boron nitride phases with compositions different from Si3N4: BN = 1 : 3. Here, we present a short comprehensive overview over the insights gained using molecular dynamics and Monte Carlo simulations to explore the energy landscape of a-Si3B3N7, model the actual synthesis route and compute static and transport properties of a-Si3BN7.

  12. Porous carbon nitride nanosheets for enhanced photocatalytic activities

    Science.gov (United States)

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

    2014-11-01

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

  13. Electron field emission from boron nitride thin films

    Science.gov (United States)

    Encarnacion, Pedro Aron

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

  14. Radiation Damage and Fission Product Release in Zirconium Nitride

    Energy Technology Data Exchange (ETDEWEB)

    Egeland, Gerald W. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

    2005-08-29

    Zirconium nitride is a material of interest to the AFCI program due to some of its particular properties, such as its high melting point, strength and thermal conductivity. It is to be used as an inert matrix or diluent with a nuclear fuel based on transuranics. As such, it must sustain not only high temperatures, but also continuous irradiation from fission and decay products. This study addresses the issues of irradiation damage and fission product retention in zirconium nitride through an assessment of defects that are produced, how they react, and how predictions can be made as to the overall lifespan of the complete nuclear fuel package. Ion irradiation experiments are a standard method for producing radiation damage to a surface for observation. Cryogenic irradiations are performed to produce the maximum accumulation of defects, while elevated temperature irradiations may be used to allow defects to migrate and react to form clusters and loops. Cross-sectional transmission electron microscopy and grazing-incidence x-ray diffractometry were used in evaluating the effects that irradiation has on the crystal structure and microstructure of the material. Other techniques were employed to evaluate physical effects, such as nanoindentation and helium release measurements. Results of the irradiations showed that, at cryogenic temperatures, ZrN withstood over 200 displacements per atom without amorphization. No significant change to the lattice or microstructure was observed. At elevated temperatures, the large amount of damage showed mobility, but did not anneal significantly. Defect clustering was possibly observed, yet the size was too small to evaluate, and bubble formation was not observed. Defects, specifically nitrogen vacancies, affect the mechanical behavior of ZrN dramatically. Current and previous work on dislocations shows a distinct change in slip plane, which is evidence of the bonding characteristics. The stacking-fault energy changes dramatically with

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

    Science.gov (United States)

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

    2016-03-01

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

  16. Evaluation of the corrosion resistance of plasma nitrided austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Mareci, Daniel; Bolat, Georgiana [Technical Univ. Iasi (Romania). Faculty of Chemical Engineering and Environmental Protection; Strugaru, Sorin Iacob; Munteanu, Corneliu [Technical Univ. Iasi (Romania). Faculty of Mechanical Engineering; Souto, Ricardo M. [Univ. of La Laguna, Tenerife (Spain). Dept. of Chemistry

    2015-03-15

    Plasma nitriding at 500 C for 14 h was applied to austenitic 304 stainless steel for surface hardening. The effect of surface treatment on the corrosion resistance of the material was investigated in naturally-aerated 0.5 M NaCl solution for 30 days using linear potentiodynamic polarization and electrochemical impedance spectroscopy methods. Both as-cast and plasma nitrided stainless steel samples underwent spontaneous passivation, though the nitrided sample exhibited more positive zero current potential, higher breakdown potential, and lower anodic current densities than the as-cast material. Impedance spectra were interpreted in terms of a duplex passive film, corrosion resistance mainly arising from a thin inner compact layer, whereas the outer layer was more porous and less sealing. Capacitive behaviour and high corrosion resistance were observed in the low and medium frequency ranges for the nitrided samples.

  17. Creep behavior and surface characterization of a laser surface nitrided Ti–6Al–4V alloy

    International Nuclear Information System (INIS)

    Laser surface nitriding of a Ti–6Al–4V alloy is studied with the aim of increasing creep resistance. A detailed characterization of the surface and cross section of the nitrided laser surface was carried out by optical/scanning electron microscopy and X-ray diffraction techniques. The microstructure of the surface-nitrided Ti–6Al–4V consists of TiN dendrites distributed in a martensitic titanium matrix. Finally, the mechanical properties in terms of microindentation hardness and creep resistance were evaluated. Constant load creep tests were conducted on a standard creep machine at different stress levels at 500 °C, 600 °C and 700 °C. Results indicated that the creep rates of the laser nitrided alloy were lower than those of the untreated material and the microhardness of the surface was improved to 1100 VHN compared with the 340 VHN of the substrate

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

    Science.gov (United States)

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

    2016-03-01

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

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

    Science.gov (United States)

    Lin, Zhenzhen; Wang, Xinchen

    2014-06-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2003-01-01

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

  1. Nitride Bonded Refractory Products and Their Matching Mortars GB/T 23293-2009

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiaohui

    2009-01-01

    @@ 1 Scope This standard specifies the definition, classification, brand, shape, dimension, technical requirements, test methods, quality appraisal procedures, packing, marking, storage, transportation and quality certificate of nitride bonded refractory products and their matching mortars.

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

    Science.gov (United States)

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

    2007-12-01

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

  3. Synthesis and characterization of Ni-Mo bimetallic nitride from the mixture of nitrogen and hydrogen

    International Nuclear Information System (INIS)

    A new method for the synthesis of Ni-Mo bimetallic nitrides was reported in the present paper. The bimetallic nitrides were successfully prepared by a temperature-programmed reaction between bimetallic oxide precursors and the mixed gases of N2 and H2 instead of NH3. By adjusting pH values of the solution in the process of co-precipitation, pure NiMoO4 or NiMoO4 with excess MoO3 was obtained, and then pure Ni3Mo3N or Ni3Mo3N with γ-Mo2N was synthesized by nitriding the precursors. The structural properties of the precursors and their corresponding nitrides were investigated by means of X-ray diffraction (XRD), ultraviolet laser Raman spectroscopy, thermogravimetric (TG) analysis and chemical analysis of total nitrogen content

  4. Lattice-parameter change induced by accommodation of precipitate/matrix misfit; misfitting nitrides in ferrite

    International Nuclear Information System (INIS)

    Upon nitriding of iron-based alloys, development of misfitting coherent nitride precipitates in a ferrite matrix induces an overall expansion of the ferrite lattice. This lattice expansion was quantitatively determined by X-ray diffraction from the change of the lattice parameter of ferrite of homogenously nitrided Fe−Cr and Fe−V alloys. Adopting the experimentally verified (by X-ray diffraction and transmission electron microscopy) notion that the misfitting precipitates diffract coherently with the matrix, the extent of this hydrostatic lattice-strain component could be calculated, in general, as function of the precipitate/matrix misfit, the volume fraction of precipitates and the elastic properties of the matrix and precipitates. The experimentally observed and the predicted dependencies of lattice dilatation agree very well for both nitrided Fe−Cr and Fe−V alloys. This is the first time that this type of lattice expansion was experimentally identified and quantitatively explained

  5. Nitride passivation of the interface between high-k dielectrics and SiGe

    Energy Technology Data Exchange (ETDEWEB)

    Sardashti, Kasra [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358 (United States); Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093-0411 (United States); Hu, Kai-Ting [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358 (United States); Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093-0411 (United States); Tang, Kechao; McIntyre, Paul [Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); Madisetti, Shailesh; Oktyabrsky, Serge [Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York 12222 (United States); Siddiqui, Shariq; Sahu, Bhagawan [TD Research, GLOBALFOUNDRIES US, Inc., Albany, New York 12203 (United States); Yoshida, Naomi; Kachian, Jessica; Dong, Lin [Applied Materials, Inc., Santa Clara, California 95054 (United States); Fruhberger, Bernd [California Institute for Telecommunications and Information Technology, University of California San Diego, La Jolla, California 92093-0436 (United States); Kummel, Andrew C., E-mail: akummel@ucsd.edu [Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093-0358 (United States)

    2016-01-04

    In-situ direct ammonia (NH{sub 3}) plasma nitridation has been used to passivate the Al{sub 2}O{sub 3}/SiGe interfaces with Si nitride and oxynitride. X-ray photoelectron spectroscopy of the buried Al{sub 2}O{sub 3}/SiGe interface shows that NH{sub 3} plasma pre-treatment should be performed at high temperatures (300 °C) to fully prevent Ge nitride and oxynitride formation at the interface and Ge out-diffusion into the oxide. C-V and I-V spectroscopy results show a lower density of interface traps and smaller gate leakage for samples with plasma nitridation at 300 °C.

  6. Structural interconnections and the role of heptagonal rings in endohedral trimetallic nitride template fullerenes.

    Science.gov (United States)

    Gan, Li-Hua; Lei, Dan; Fowler, Patrick W

    2016-07-01

    Recent experiments indicate that fullerene isomers outside the classical definition can also encapsulate metallic atoms or clusters to form endohedral metallofullerenes. Our systematic study using DFT calculations, suggests that many heptagon-including nonclassical trimetallic nitride template fullerenes are similar in stability to their classical counterparts, and that conversion between low-energy nonclassical and classical parent cages via Endo-Kroto insertion/extrusion of C2 units and Stone-Wales isomerization may facilitate the formation of endohedral trimetallic nitride fullerenes. Close structural connections are found between favored isomers of trimetallic nitride template fullerenes from C78 to C82 . It appears that the lower symmetry and local deformations associated with introduction of a heptagonal ring favor encapsulation of intrinsically less symmetrical mixed metal nitride clusters. © 2016 Wiley Periodicals, Inc. PMID:27282122

  7. Effect of Plasma Nitriding Temperatures on Characteristics of Aisi 201 Austenitic Stainless Steel

    Science.gov (United States)

    Gao, Yuxin; Zheng, Shaomei

    2016-10-01

    Samples of AISI 201 austenitic stainless steel were produced by plasma nitriding at 350∘C, 390∘C, 420∘C, 450∘C and 480∘C for 5h. Systematic characterization of the nitrided layer was carried out in terms of micrograph observations, phase identification, chemical composition depth profiling, surface microhardness measurements and electrochemical corrosion tests. The results show that the surface hardness and the layer thickness increased with increasing temperature. XRD indicated that a single S-phase layer was formed during low temperature (≤420∘C), while Cr2N or CrN phase was formed besides S-phase when nitrided at 450∘C and 480∘C. The specimen treated at 390∘C presents a much enhanced corrosion resistance compared to the untreated substrate. The corrosion resistance deteriorated for samples treated above 450∘C due to the formation of chromium nitrides.

  8. Diffusion of nitrogen in austenitic phase: Application to nitriding of stainless steels

    Directory of Open Access Journals (Sweden)

    Torchane Lazhar

    2014-04-01

    Full Text Available The nitriding treatment of the martensitic stainless steels aims to harden and to introduce compressive stresses on the surface of steel. Hardening is resulting of the martensitic transformation of the austenitic matrix enriched into nitrogen during cooling and of the germination and the nitride growth. In order to preserve the stainless character of the nitrided layer, it is imperative to control precipitation within the zone affected by the treatment. Our task consists in showing that is possible to control the composition of the gas atmosphere containing ammonia and argon and to carry out on the surface of nitrided samples at 1050°C two types of configuration of layers : a single phase layer made up by martensite enriched in nitrogen α’N and or a two phase layer made up by austenite γN and martensite α’N enriched in nitrogen.

  9. Microstructure and Mechanical Properties of a Nitride-Strengthened Reduced Activation Ferritic/Martensitic Steel

    Science.gov (United States)

    Zhou, Qiangguo; Zhang, Wenfeng; Yan, Wei; Wang, Wei; Sha, Wei; Shan, Yiyin; Yang, Ke

    2012-12-01

    Nitride-strengthened reduced activation ferritic/martensitic (RAFM) steels are developed taking advantage of the high thermal stability of nitrides. In the current study, the microstructure and mechanical properties of a nitride-strengthened RAFM steel with improved composition were investigated. Fully martensitic microstructure with fine nitrides dispersion was achieved in the steel. In all, 1.4 pct Mn is sufficient to suppress delta ferrite and assure the steel of the full martensitic microstructure. Compared to Eurofer97, the steel showed similar strength at room temperature but higher strength at 873 K (600 °C). The steel exhibited very high impact toughness and a low ductile-to-brittle transition temperature (DBTT) of 243 K (-30 °C), which could be further reduced by purification.

  10. Effects of Nitridation on Properties of SiC Fiber and Interface of Ti Matrix Composite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Prenitridation of the TiBx coating surface of the Sigma SM1240 SiC fiber can form more stable compounds at the surface and obstruct the release of boron atoms into the Ti-based alloy matrix. The effect of nitridation on the tensile strength of the fiber was investigated in this work. Nitridation could degrade the tensile strength of the SiC fiber if the treating temperature and time are not optimized. The chemical reaction between the W core and SiC and the modification of fiber microstructure during the nitridation are responsible for the degradation in strength. The strength can be maintained by further optimization of the treating temperature and time. Therefore, stabilizing the surface of TiBx coating and hence the interface of the SiCf/Ti composite by the nitridation of the SiC fiber is a feasible technique for practical applications.

  11. Diffusion characteristics of plasma nitrided hard chromium on AISI 1010 steel

    Energy Technology Data Exchange (ETDEWEB)

    Danisman, Murat [Gedik Univ., Istanbul (Turkey). Electronic Engineering Dept.; Kocabas, Mustafa; Cansever, Nurhan [Yildiz Technical Univ., Istanbul (Turkey)

    2015-06-01

    In order to investigate the different Cr-N formation characteristics of plasma nitrided hard Cr coatings, Cr was electrodeposited on AISI 1010 steel and plasma nitrided at 600, 700 and 800 C for 3 h, 5 h and 7 h, respectively. Phase analyses of resulting Cr-N phases and grain size of Cr layer before and after nitriding process were calculated by X-ray diffraction analysis. Structure of nitride layer and its thickness were analyzed using scanning electron microscopy micrographs. The micrographs indicated that samples consisted of three distinctive layers. In order to distinguish these layers, scanning electron microscopy and energy dispersive spectroscopy (EDX) analysis were used as well as elemental distribution versus depth was plotted. The Cr-N diffusion was investigated by layer thickness measurements, and diffusion coefficient as well as activation energies were calculated.

  12. Creep behavior and surface characterization of a laser surface nitrided Ti–6Al–4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Adriano Gonçalves dos, E-mail: areis@ita.br [Instituto Tecnológico de Aeronáutica—ITA/DCTA, Pr. M. Eduardo Gomes, 50, São José dos Campos—SP 12228-900 (Brazil); Reis, Danieli Aparecida Pereira [Universidade Federal de São Paulo—UNIFESP, R. Talim, 330, São José dos Campos—SP 12231-280 (Brazil); Moura Neto, Carlos de [Instituto Tecnológico de Aeronáutica—ITA/DCTA, Pr. M. Eduardo Gomes, 50, São José dos Campos—SP 12228-900 (Brazil); Barboza, Miguel Justino Ribeiro [Escola de Engenharia de Lorena—EEL/DEMAR/USP, Polo Urbo-Industrial Gleba AI-6 Caixa Postal 116, Lorena–SP 12600-970 (Brazil); Oñoro, Javier [Universidad Politécnica de Madrid—UPM, Plaza Cardenal Cisneros, 3, Madrid 28040 (Spain)

    2013-08-10

    Laser surface nitriding of a Ti–6Al–4V alloy is studied with the aim of increasing creep resistance. A detailed characterization of the surface and cross section of the nitrided laser surface was carried out by optical/scanning electron microscopy and X-ray diffraction techniques. The microstructure of the surface-nitrided Ti–6Al–4V consists of TiN dendrites distributed in a martensitic titanium matrix. Finally, the mechanical properties in terms of microindentation hardness and creep resistance were evaluated. Constant load creep tests were conducted on a standard creep machine at different stress levels at 500 °C, 600 °C and 700 °C. Results indicated that the creep rates of the laser nitrided alloy were lower than those of the untreated material and the microhardness of the surface was improved to 1100 VHN compared with the 340 VHN of the substrate.

  13. Influence of plastic deformation on low temperature surface hardening of stainless steel by gaseous nitriding

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas Lundin;

    2015-01-01

    This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of three commercial austenitic stainless steels: AISI 304, EN 1.4369 and Sandvik Nanoflex® with various degrees of austenite stability. The materials were...... plastically deformed to different equivalent strains by uniaxial tension. Gaseous nitriding of the strained material was performed in ammonia at atmospheric pressure in the temperature range 693-703 K. Microstructural characterization of the as-deformed states and the nitrided case included X-ray diffraction...... analysis, reflected light microscopy and microhardness indentation. The results demonstrate that a case of expanded austenite develops and that, in particular, the presence of strain-induced martensite in the initial (deformed) microstructure has a large influence on the nitrided zone....

  14. Microplasma Processed Ultrathin Boron Nitride Nanosheets for Polymer Nanocomposites with Enhanced Thermal Transport Performance.

    Science.gov (United States)

    Zhang, Ri-Chao; Sun, Dan; Lu, Ai; Askari, Sadegh; Macias-Montero, Manuel; Joseph, Paul; Dixon, Dorian; Ostrikov, Kostya; Maguire, Paul; Mariotti, Davide

    2016-06-01

    This Research Article reports on the enhancement of the thermal transport properties of nanocomposite materials containing hexagonal boron nitride in poly(vinyl alcohol) through room-temperature atmospheric pressure direct-current microplasma processing. Results show that the microplasma treatment leads to exfoliation of the hexagonal boron nitride in isopropyl alcohol, reducing the number of stacks from >30 to a few or single layers. The thermal diffusivity of the resulting nanocomposites reaches 8.5 mm(2) s(-1), 50 times greater than blank poly(vinyl alcohol) and twice that of nanocomposites containing nonplasma treated boron nitride nanosheets. From TEM analysis, we observe much less aggregation of the nanosheets after plasma processing along with indications of an amorphous carbon interfacial layer, which may contribute to stable dispersion of boron nitride nanosheets in the resulting plasma treated colloids. PMID:27153343

  15. Structural properties of iron nitride on Cu(100): An ab-initio molecular dynamics study

    KAUST Repository

    Heryadi, Dodi

    2011-01-01

    Due to their potential applications in magnetic storage devices, iron nitrides have been a subject of numerous experimental and theoretical investigations. Thin films of iron nitride have been successfully grown on different substrates. To study the structural properties of a single monolayer film of FeN we have performed an ab-initio molecular dynamics simulation of its formation on a Cu(100) substrate. The iron nitride layer formed in our simulation shows a p4gm(2x2) reconstructed surface, in agreement with experimental results. In addition to its structural properties, we are also able to determine the magnetization of this thin film. Our results show that one monolayer of iron nitride on Cu(100) is ferromagnetic with a magnetic moment of 1.67 μ B. © 2011 Materials Research Society.

  16. Surface modification of austenitic steel by various glow-discharge nitriding methods

    Directory of Open Access Journals (Sweden)

    Tomasz Borowski

    2015-09-01

    Full Text Available Recent years have seen intensive research on modifying glow-discharge nitriding processes. One of the most commonly used glow-discharge methods includes cathodic potential nitriding (conventional method, and active screen plasma nitriding. Each of these methods has a number of advantages. One very important, common feature of these techniques is full control of the microstructure, chemical and phase composition, thickness and the surface topography of the layers formed. Another advantage includes the possibility of nitriding such materials as: austenitic steels or nickel alloys, i.e. metallic materials which do not diffuse nitrogen as effectively as ferritic or martensitic steels. However, these methods have some disadvantages as well. In the case of conventional plasma nitriding, engineers have to deal with the edge effect, which makes it difficult to use this method for complexly shaped components. In turn, in the case of active screen plasma nitriding, the problem disappears. A uniform, smooth layer forms, but is thinner, softer and is not as resistant to friction compared to layers formed using the conventional method. Research is also underway to combine these methods, i.e. use an active screen in conventional plasma nitriding at cathodic potential. However, there is a lack of comprehensive data presenting a comparison between these three nitriding processes and the impact of pulsating current on the formation of the microstructure and functional properties of austenitic steel surfaces. The article presents a characterisation of nitrided layers produced on austenitic X2CrNiMo17-12-2 (AISI 316L stainless steel in the course of glow-discharge nitriding at cathodic potential, at plasma potential and at cathodic potential incorporating an active screen. All processes were carried out at 440 °C under DC glow-discharge conditions and in 100 kHz frequency pulsating current. The layers were examined in terms of their microstructure, phase and

  17. Reduced stability of copper interconnects due to wrinkles and steps on hexagonal boron nitride substrates

    Science.gov (United States)

    Gao, Jian; Chow, Philippe K.; Thomas, Abhay V.; Lu, Toh-Ming; Borca-Tasciuc, Theodorian; Koratkar, Nikhil

    2014-09-01

    There is great scientific and technological interest in the use of chemical-vapor-deposition grown hexagonal boron nitride dielectric substrates for microelectronics applications. This interest stems from its superior heat spreading capability compared to silicon dioxide as well as the lack of surface dangling bonds or charge traps in hexagonal boron nitride which results in superior performance for graphene based electronics devices. However, surface heterogeneities, such as wrinkles or steps, are ubiquitous in such devices due to the fabrication and processing of chemical vapor deposition grown hexagonal boron nitride. In this study, we characterize the effect of such surface heterogeneities on the stability of copper interconnects used in microelectronics devices. Based on the theoretical thermo-physical properties of the constituent thin film layers, our simulations predict that copper interconnects deposited on hexagonal boron nitride can withstand ˜1.9 times more power than on a silicon dioxide substrate, due to its superior in-plane thermal conductivity. However, our electrical measurements reveal that copper wires melt and fail at consistently lower current densities on hexagonal boron nitride than on silicon dioxide. This was verified by testing in air as well as under vacuum. Scanning electron microscopy and atomic force microscopy characterization of the hexagonal boron nitride surface indicates that this contradictory result is due to nanoscale surface non-uniformities (i.e., wrinkles and steps) which are omnipresent in chemical-vapor-deposition grown and transferred hexagonal boron nitride films. Our results highlight the critical need for improved processing methods before large-scale microelectronics applications of chemical vapor deposition grown hexagonal boron nitride can be realized.

  18. Computer-aided analytical control of diamond and cubic boron nitride grits

    International Nuclear Information System (INIS)

    Methodical and information aspects of the superhard materials powder uniformity as a characteristics of the powder quality are discussed. Computer-aided analytical methods of the rapid diagnostics of the sieve granulometric composition and the external specific surface of diamond and cubic boron nitride grits are described. The results of the application of the developed methods and software to standard powders of synthetic diamond and cubic boron nitride are given

  19. Advanced Lightweight Silicide and Nitride Based Materials for Turbo-Engine Applications.

    OpenAIRE

    Drawin, S.; Justin, J.F.

    2011-01-01

    International audience Refractory metal silicides and nitride-based ceramics combine two properties that may lead to substantial reductions in aircraft fuel consumption : compared to the most advanced nickel-based superalloys presently used in aeronautical turbines, they can withstand higher temperatures and may have lower densities. Niobium silicide-based alloys and silicon nitride / molybdenum disilicide composites are currently being developed for turbine hot section components for both...

  20. Optical frequency comb generation from aluminum nitride micro-ring resonator

    OpenAIRE

    Jung, Hojoong; Xiong, Chi; Fong, King Y.; Zhang, Xufeng; Hong X. Tang

    2013-01-01

    Aluminum nitride is an appealing nonlinear optical material for on-chip wavelength conversion. Here we report optical frequency comb generation from high quality factor aluminum nitride micro-ring resonators integrated on silicon substrates. By engineering the waveguide structure to achieve near-zero dispersion at telecommunication wavelengths and optimizing the phase matching for four-wave mixing, frequency combs are generated with a single wavelength continuous-wave pump laser. The Kerr coe...