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Letteratura scientifica selezionata sul tema "Hexagonal-boron nitride (h-BN)"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 7 febbraio 2022

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Articoli di riviste sul tema "Hexagonal-boron nitride (h-BN)"

Li, Yunfang. "Boron-nitride nanotube triggered self-assembly of hexagonal boron-nitride nanostructure". Phys. Chem. Chem. Phys. 16, n. 38 (2014): 20689–96. http://dx.doi.org/10.1039/c4cp02578d.

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Molecular mechanics results show that a hexagonal boron nitride (h-BN) membrane can spontaneously assemble on the single-walled boron nitride nanotube (BNNT) in a scroll or helical manner, showing an interesting dependence on h-BN width.

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Xu, N., J. F. Li, B. L. Huang e B. L. Wang. "Polycrystalline boron nitride constructed from hexagonal boron nitride". RSC Adv. 4, n. 73 (2014): 38589–93. http://dx.doi.org/10.1039/c4ra05485g.

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Lee, Jae-Kap, Jin-Gyu Kim, K. P. S. S. Hembram, Seunggun Yu e Sang-Gil Lee. "AB-stacked nanosheet-based hexagonal boron nitride". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 77, n. 2 (17 marzo 2021): 260–65. http://dx.doi.org/10.1107/s2052520621000317.

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Hexagonal boron nitride (h-BN) has been generally interpreted as having an AA stacking sequence. Evidence is presented in this article indicating that typical commercial h-BN platelets (∼10–500 nm in thickness) exhibit stacks of parallel nanosheets (∼10 nm in thickness) predominantly in the AB sequence. The AB-stacked nanosheet occurs as a metastable phase of h-BN resulting from the preferred texture and lateral growth of armchair (110) planes. It appears as an independent nanosheet or unit for h-BN platelets. The analysis is supported by simulation of thin AB films (2–20 layers), which explains the unique X-ray diffraction pattern of h-BN. With this analysis and the role of pressure in commercial high-pressure high-temperature sintering (driving nucleation and parallelizing the in-plane crystalline growth of the nuclei), a growth mechanism is proposed for 2D h-BN (on a substrate) as `substrate-induced 2D growth', where the substrate plays the role of pressure.

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Tang, Yongzhe, Peng Zhang, Mingxiao Zhu, Jiacai Li, Yuxia Li, Ziguo Wang e Liangsong Huang. "Temperature Effects on the Dielectric Properties and Breakdown Performance of h-BN/Epoxy Composites". Materials 12, n. 24 (9 dicembre 2019): 4112. http://dx.doi.org/10.3390/ma12244112.

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Epoxy–boron nitride composites are promising insulating materials, and it is highly important to understand their insulating performances at different temperatures with different nano-doping amounts. In this study, we investigated the effects of different mass fractions of epoxy–micron hexagonal boron nitride composites on their thermal conductivity, as well as the effects of temperature and mass fraction on their insulating performances. The results demonstrated that the thermal conductivity of epoxy–micron hexagonal boron nitride composites was superior to that of neat epoxy. The thermal conductivity of epoxy–micron hexagonal boron nitride composites increased with the mass fraction of hexagonal boron nitride, and their dielectric constant and dielectric loss increased with temperature. The dielectric constant of epoxy–micron hexagonal boron nitride composites decreased as the mass fraction of hexagonal boron nitride increased, while their dielectric losses decreased and then increased as the mass fraction of hexagonal boron nitride increased. Due to internal heat accumulation, the alternating current breakdown strength of epoxy–micron hexagonal boron nitride composites increased and then decreased as the mass fraction of hexagonal boron nitride increased. Additionally, as the temperature increased, the composites transitioned from the glassy state to the rubbery or viscous state, and the breakdown strength significantly degraded.

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Корте, Ш., М. К. Кутжанов, А. М. Ковальский, А. С. Конопацкий, Д. Г. Квашнин, Е. М. Приходько, П. Б. Сорокин, Д. В. Штанский e А. Т. Матвеев. "Получение гетерогенных наночастиц Al/BN в микроволновой плазме". Письма в журнал технической физики 46, n. 10 (2020): 25. http://dx.doi.org/10.21883/pjtf.2020.10.49427.18154.

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In this work, the interaction of a mixture of Al and BN nanopowder with hydrogen microwave plasma was studied. Using X-ray diffraction analysis, scanning and transmission electron microscopy, the formation of AlN and AlB2 nanocrystals as a result of short-term (~ 30 ms) interaction of Al vapor with h-BN was established. Obtained results also indicate the formation of hydrogenated hexagonal boron nitride h-BN-H. The critical shear stresses were calculated for the interfaces between BN and Al, AlB2, and AlN. Approaches for increasing the strength of the composite materials based on hexagonal boron nitride and aluminum are discussed.

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Jin, Moon-Seog, e Nam-Oh Kim. "Photoluminescence of Hexagonal Boron Nitride (h-BN) Film". Journal of Electrical Engineering and Technology 5, n. 4 (1 novembre 2010): 637–39. http://dx.doi.org/10.5370/jeet.2010.5.4.637.

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Cataldo, Franco, e Susana Iglesias-Groth. "Neutron damage of hexagonal boron nitride: h-BN". Journal of Radioanalytical and Nuclear Chemistry 313, n. 1 (18 maggio 2017): 261–71. http://dx.doi.org/10.1007/s10967-017-5289-8.

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Eichler, Jens, Krishna Uibel e Christoph Lesniak. "Boron Nitride (BN) and Boron Nitride Composites for Applications under Extreme Conditions". Advances in Science and Technology 65 (ottobre 2010): 61–69. http://dx.doi.org/10.4028/www.scientific.net/ast.65.61.

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Hexagonal boron nitride (h-BN) is a very versatile material that is used in a number of applications due to its unique combination of properties. This paper reviews typical h-BN qualities and their applications as functional particle in coatings and as sintered parts. As an example, the EKamold® coating family is presented in detail for a variety of substrate types and applications. Furthermore a general overview is given of the effect of the binder phase for hot-pressed h-BN qualities. And finally the use of h-BN as a composite with a) zirconium oxide for side dams in steel thin-strip casting and b) with titanium diboride as evaporation boats is described in more detail.

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Harrison, Haley, Jason T. Lamb, Kyle S. Nowlin, Andrew J. Guenthner, Kamran B. Ghiassi, Ajit D. Kelkar e Jeffrey R. Alston. "Quantification of hexagonal boron nitride impurities in boron nitride nanotubes via FTIR spectroscopy". Nanoscale Advances 1, n. 5 (2019): 1693–701. http://dx.doi.org/10.1039/c8na00251g.

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The peak ratio of in-plane versus out-of-plane FTIR absorbance is proportional to weight% of hexagonal boron nitride (h-BN) in boron nitride nanotubes (BNNTs) and can be used to quantify the purity of synthesized BNNTs.

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Snure, Michael, e Qing S. Paduano. "Growth of Hexagonal Boron Nitride on Microelectronic Compatible Substrates". MRS Proceedings 1781 (2015): 1–10. http://dx.doi.org/10.1557/opl.2015.562.

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ABSTRACTBoron nitride has attracted a great deal of attention as a two dimensional (2D) insulator for substrate and gate dielectric applications in 2D electronics. Development of a scalable technique to grow mono- to few-layer h-BN on microelectronics compatible substrates is desirable. Work on the growth of atomically smooth BN and graphene on sapphire and Si is presented in this paper. Two approaches are described: i) growth of h-BN and graphene on Si and sapphire substrates using a catalyzing Cu thin film, and ii) low pressure metal organic chemical vapor deposition (MOCVD) growth on sapphire. In approach i) we discuss problems associated with the thermal instability of Cu at the interface with the substrate and show how the stability may be improved through the use of a thin Ni buffer layer or careful substrate selection. The correlation between Cu film morphology and h-BN (and graphene) quality is shown. In approach ii) we find two different growth modes, 3D island growth at low V/III ratios and self-terminating growth at high V/III ratios. Under self-terminating growth atomically smooth few-layer h-BN films are produced. Nitridation of the sapphire surface is found to promote this self-terminating growth by improving nucleation of BN on the substrate. Finally, we present results from the growth of graphene/h-BN on sapphire in a single process.

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Più fonti

Tesi sul tema "Hexagonal-boron nitride (h-BN)"

Alharbi, Abdulaziz. "Deformation of hexagonal boron nitride". Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/deformation-of-hexagonal-boron-nitride(6c6013c4-8c17-4dec-b250-ed3f0baea7ed).html.

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Boron nitride (BN) materials have unique properties, which has led to interest in them in the last few years. The deformation of boron nitride materials including hexagonal boron nitride, boron nitride nanosheets (BNNSs) and boron nitride nanotubes have been studied by Raman spectroscopy. Both mechanical and liquid exfoliations were employed to obtain boron nitride nanostructures. Boron nitride glass composites were synthesised and prepared in thin films to be deformed by bending test in-situ Raman spectroscopy. Hexagonal boron nitride in the form of an individual flake and as flakes dispersed in glass matrices has been deformed and Raman measurement shows its response to strain. The shift rates were, -4.2 cm-1/%, -6.5 cm-1/% for exfoliated h-BN flake with thick and thin regions and -7.0 cm-1/%, -2.8 cm-1/% for the h-BN flakes in the h-BN/ glass (I) and glass (II) composites. Boron nitride nanosheets (BNNSs) shows a G band Raman peak at 1367.5 cm-1, and the deformation process of BNNSs/ glass composites gives a shift rate of -7.65 cm-1/% for G band. Boron nitride nanotubes (BNNTs) have a Raman peak with position at 1368 cm-1, and their deformation individually and in composites gives Raman band shift rates of -25.7 cm-1/% and -23.6 cm-1/%. Glass matrices shows compressive stresses on boron nitride fillers and this was found as an upshift in the frequencies of G band peak of boron nitride materials. GrÃ¼neisen parameters of boron nitride (BN) were used to calculate the residual strains in glass matrices of BNNSs nanocomposites as well as to estimate the band shift rates which found to be in agreement with the experimental shift rate of bulk BN and BNNTs.

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Elias, Christine. "Optical spectroscopy of hexagonal boron nitride : from bulk to monolayer". Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTS054.

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Le nitrure de bore hexagonal (h-BN) ou « graphite blanc » est un semiconducteur qui possède une large bande interdite (~ 6 eV) et dont la structure cristalline est proche de celle du graphite : elle est formée par des plans d’atomes arrangés en nid d’abeilles. La liaison entre les plans est de type Van-der-Waals. En 2004, h-BN a démontré sa capacité d’émettre de manière efficace de la lumière dans l’UV profond (~200 nm) et cela sur des cristaux massifs synthétisés au Japon (NIMS). Ces résultats ont attiré l’attention de la communauté scientifique des semiconducteurs pour la possibilité de pouvoir utiliser ce matériau comme une source de lumière pour des applications dans l’UV profond.La nature de la bande interdite dans h-BN massif a été un sujet de débat pendant plus de 12 ans et elle a été étudiée à la fois par des calculs théoriques et par des expériences. En 2016, le gap a été démontré de nature indirecte par des expériences de spectroscopie optique à 2-photons. Un exciton indirect et des recombinaisons assistées par phonons ont été observés par photoluminescence dans h-BN.Dans h-BN, comme dans d’autres matériaux 2D, en passant d’un système 3D (massif) à un système 2D (monocouche), la nature du gap change. Les calculs montrent un changement d’un gap indirect (massif) vers un gap direct (monocouche). Cette transition de gap indirect-direct n’a jamais été observée dans h-BN, et en conséquence les propriétés opto-électroniques de la monocouche n’ont jamais été étudiées. Durant cette thèse, nous avons étudié pour la première fois les propriétés optiques de la monocouche de BN (mBN) par spectroscopie optique (macro-PL et réflectivité) sur des échantillons de mBN épitaxiés par MBE à haute température sur des substrats de graphite (HOPG). Nos résultats ont démontré pour la première fois la possibilité de fabriquer une monocouche de BN (3.5 Å) par MBE. Nos mesures de spectroscopie optique ont démontré la présence d’une transition optique à 6.1 eV associée à un gap direct dans la mBN
Hexagonal boron nitride (h-BN) or “white graphite” is a semiconductor which has a wide bandgap (~ 6 eV) and whose crystalline structure is close to that of graphite: it is formed by planes of atoms arranged in a hexagonal form. The interaction between the planes is of Van-der-Waals type. In 2004, h-BN demonstrated its ability to efficiently emit light in the deep UV (~ 200 nm) in crystals synthesized in NIMS laboratory in JAPAN. These results have attracted the attention of the community of semiconductors to the possibility of being used as a source of light for deep UV applications.The nature of the band gap in bulk h-BN has been the subject of a debate for over 12 years and it has been studied by theoretical calculations and by experiments. In 2016, the gap was demonstrated to be indirect based on 2-photon spectroscopy measurements. Indirect exciton and phonon-assisted recombination were observed by photoluminescence in h-BN.In h-BN, like in other 2D materials, when changing from a 3D system (massive) to a 2D system (monolayer), the nature of the gap changes. The calculations show a change from an indirect gap (bulk) to a direct gap (monolayer). This indirect-direct gap transition has never been observed in h-BN, and consequently the opto-electronic properties of the monolayer have never been studied. During this thesis, we studied for the first time the optical properties of the BN monolayer (mBN) by performing optical spectroscopy (macro-PL and reflectivity) in mBN samples grown by MBE at high temperature on graphite substrates (HOPG).Our results demonstrated for the first time the possibility to grow mBN (3.5 Å) by MBE technique. Our optical measurements demonstrated the presence of an optical transition at 6.1 eV associated to the direct gap in the mBN

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Nakhaie, Siamak. "Growth of graphene/hexagonal boron nitride heterostructures using molecular beam epitaxy". Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19190.

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Zweidimensionale (2D) Materialien bieten eine Vielzahl von neuartigen Eigenschaften und sind aussichtsreich Kandidaten für ein breites Spektrum an Anwendungen. Da hexagonales Bornitrid (h-BN) für eine Integration in Heterostrukturen mit anderen 2D Materialien geeignet ist, erweckte dieses in letzter Zeit großes Interesse. Insbesondere van-der-Waals-Heterostrukturen, welche h-BN und Graphen verbinden, weisen viele potenzielle Vorteile auf, verbleiben in ihrer großflächigen Herstellung von kontinuierlichen Filmen allerdings problematisch. Diese Dissertation stellt eine Untersuchung betreffend des Wachstums von h-BN und vertikalen Heterostrukturen von Graphen und h-BN auf Ni-Substraten durch Molekularstrahlepitaxie (MBE) vor. Zuerst wurde das Wachstum von h-BN mittels elementarer B- und N-Quellen auf Ni als Wachstumssubstrat untersucht. Kristalline h-BN-Schichten konnten durch Raman-spektroskopie nachgewiesen werden. Wachstumsparameter für kontinuierliche und atomar dünne Schichten wurden erlangt. Das Keimbildungs- und Wachstumsverhalten so wie die strukturelle Güte von h-BN wurden mittels einer systemischen Veränderung der Wachstumstemperatur und -dauer untersucht. Die entsprechenden Beobachtungen wie der Änderungen der bevorzugten Keimbildungszentren, der Kristallgröße und der Bedeckung des h-BN wurden diskutiert. Ein Wachstum von großflächigen vertikalen h-BN/Graphen Heterostrukturen (h-BN auf Graphen) konnte mittels einem neuartigen, MBE-basierenden Verfahren demonstriert werden, welche es h-BN und Graphen jeweils erlaubt sich in der vorteilhaften Wachstumsumgebung, welche von Ni bereitgestellt wird, zu formen. In diesem Verfahren formt sich Graphen an der Schnittstelle von h-BN und Ni durch Präzipitation von zuvor in der Ni-Schicht eingebrachten C-Atomen. Schließlich konnte noch ein großflächiges Wachstum von Graphen/h-BN-Heterostrukturen (Graphen auf h-BN) durch das direkte abscheiden von C auf MBE-gewachsenen h-BN gezeigt werden.
Two-dimensional (2D) materials offer a variety of novel properties and have shown great promise to be used in a wide range of applications. Recently, hexagonal boron nitride (h-BN) has attracted significant attention due to its suitability for integration into heterostructures with other 2D materials. In particular, van der Waals heterostructures combining h-BN and graphene offer many potential advantages, but remain difficult to produce as continuous films over large areas. This thesis presents an investigation regarding the growth of h-BN and vertical heterostructures of graphene and h-BN on Ni substrates using molecular beam epitaxy (MBE). The growth of h-BN from elemental sources of B and N was investigated initially by using Ni as the growth substrate. The presence of crystalline h-BN was confirmed using Raman spectroscopy. Growth parameters resulting in continuous and atomically thin h-BN films were obtained. By systematically varying the growth temperature and time the structural quality as well as the nucleation and growth behavior of h-BN was studied. Corresponding observations such as changes in preferred nucleation site, crystallite size, and coverage of h-BN were discussed. Growth of h-BN/graphene vertical heterostructures (h-BN on graphene) over large areas was demonstrated by employing a novel MBE-based technique, which allows both h-BN and graphene to form in the favorable growth environment provided by Ni. In this technique, graphene forms at the interface of h-BN/Ni via the precipitation of C atoms previously dissolved in the thin Ni film. No evidence for the formation of BCN alloy could be found. Additionally, the suitability of ultraviolet Raman spectroscopy for characterization of h-BN/graphene heterostructures was demonstrated. Finally, growth of large-area graphene/h-BN heterostructures (graphene on h-BN) was demonstrated via the direct deposition of C on top of MBE-grown h-BN.

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Vinogradov, Nikolay. "Controlling Electronic and Geometrical Structure of Honeycomb-Lattice Materials Supported on Metal Substrates : Graphene and Hexagonal Boron Nitride". Doctoral thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-194089.

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The present thesis is focused on various methods of controlling electronic and geometrical structure of two-dimensional overlayers adsorbed on metal surfaces exemplified by graphene and hexagonal boron nitride (h-BN) grown on transition metal (TM) substrates. Combining synchrotron-radiation-based spectroscopic and various microscopic techniques with in situ sample preparation, we are able to trace the evolution of overlayer electronic and geometrical properties in overlayer/substrate systems, as well as changes of interfacial interaction in the latter.It is shown that hydrogen uptake by graphene/TM substrate strongly depends on the interfacial interaction between substrate and graphene, and on the geometrical structure of graphene. An energy gap opening in the electronic structure of graphene on TM substrates upon patterned adsorption of atomic species is demonstrated for the case of atomic oxygen adsorption on graphene/TM’s (≥0.35 eV for graphene/Ir(111)). A non-uniform character of adsorption in this case – patterned adsorption of atomic oxygen on graphene/Ir(111) due to the graphene height modulation is verified. A moderate oxidation of graphene/Ir(111) is found largely reversible. Contrary, oxidation of h-BN/Ir(111) results in replacing nitrogen atoms in the h-BN lattice with oxygen and irreversible formation of the B2O3 oxide-like structure. Pronounced hole doping (p-doping) of graphene upon intercalation with active agents – halogens or halides – is demonstrated, the level of the doping is dependent on the agent electronegativity. Hole concentration in graphene on Ir(111) intercalated with Cl and Br/AlBr3 is as high as ~2×1013 cm-2 and ~9×1012 cm-2, respectively. Unusual periodic wavy structures are reported for h-BN and graphene grown on Fe(110) surface. The h-BN monolayer on Fe(110) is periodically corrugated in a wavy fashion with an astonishing degree of long-range order, periodicity of 2.6 nm, and the corrugation amplitude of ~0.8 Å. The wavy pattern results from a strong chemical bonding between h-BN and Fe in combination with a lattice mismatch in either [11 ̅1] or [111 ̅] direction of the Fe(110) surface. Two primary orientations of h-BN on Fe(110) can be observed corresponding to the possible directions of lattice match between h-BN and Fe(110). Chemical vapor deposition (CVD) formation of graphene on iron is a formidable task because of high carbon solubility in iron and pronounced reactivity of the latter, favoring iron carbide formation. However, growth of graphene on epitaxial iron films can be realized by CVD at relatively low temperatures, and the formation of carbides can be avoided in excess of the carbon-containing precursors. The resulting graphene monolayer creates a periodically corrugated pattern on Fe(110): it is modulated in one dimension forming long waves with a period of ~4 nm parallel to the [001] direction of the substrate, with an additional height modulation along the wave crests. The novel 1D templates based on h-BN and graphene adsorbed on iron can possibly find an application in 1D nanopatterning. The possibility for growing high-quality graphene on iron substrate can be useful for the low-cost industrial-scale graphene production.

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Kasri, Salima. "Développement de sources microplasma en mélange N₂/Ar pour la production d’azote atomique en vue d’une application aux procédés de dépôt de nitrures". Thesis, Sorbonne Paris Cité, 2019. https://tel.archives-ouvertes.fr/tel-03180054.

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Cette thèse a pour but de développer et d’optimiser un nouveau réacteur de dépôt de nitrure de bore hexagonal (h-BN) sur grandes surfaces en utilisant une matrice de micro-décharges à cathode creuse (MHCD) dans un mélange azote/argon. h-BN est un matériau stratégique pour des applications à forte valeur ajoutée telles que la photonique et l’électronique. Une étude fondamentale d’une MHCD DC, réalisée à l’aide de diagnostics électriques et optiques ainsi que d’un modèle global (0D), nous a permis de déterminer les caractéristiques électriques de la décharge, de mettre en évidence la production d’azote atomique dans la MHCD, espèce clé pour le dépôt de nitrure, ainsi que de déterminer la densité électronique. Par ailleurs, un réacteur matriciel fonctionnant en régime impulsionnel a été caractérisé expérimentalement à l’aide de diagnostics électriques et optiques. Les diagnostics électriques nous ont permis d’étudier l’effet de la dilution et de la fréquence sur les paramètres électriques de la décharge. La spectroscopie d’émission optique et l’imagerie rapide nous ont quant à elles permis d’identifier les espèces radiatives, de déterminer les températures dans le plasma ainsi que d’identifier les différentes phases de l’évolution spatio-temporelle de la décharge. Enfin, les premiers tests de dépôts réalisés dans un réacteur dédié nous ont permis de mettre en évidence la faisabilité d’un dépôt de h-BN sur des substrats de 5 cm de diamètre grâce au procédé développé dans le cadre de cette thèse
The aim of this thesis is to develop and optimize a new hexagonal boron nitride (h-BN) deposition reactor on large surfaces using an array of micro hollow cathode discharges (MHCD) in a nitrogen/argon mixture. h-BN is a strategic material for strong added value applications, such as photonics and electronics. A fundamental study of one DC MHCD, carried out using electrical and optical diagnostics as well as a global model (0D), has allowed the electrical characteristics of the discharge to be measured, the production of atomic nitrogen in the MHCD to be highlighted, a key species for nitride deposition, as well as the electron density to be determined. Moreover, a matrix reactor operating under a ns-pulsed excitation has been experimentally characterized using electrical and optical diagnostics. Electrical diagnostics have been used to study the effect of dilution and frequency on the electrical parameters of the discharge. Optical emission spectroscopy and fast imaging have allowed the identification of radiative species, the determination of the temperatures in the plasma as well as the identification of the different phases of the spatio-temporal evolution of the discharge. Finally, the first deposition experiments, carried out in a dedicated reactor, have demonstrated the feasibility of h-BN deposition on 5 cm in diameter substrates thanks to the process developed in the frame of this thesis

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Benadé, Howard P. "Evaluating the repeatability of friction and wear testing on a lubricant with dispersed hexagonal-boron nitride nanoparticles". Diss., 2015. http://hdl.handle.net/2263/46239.

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The SRV test rig was used to evaluate the friction and wear properties of a lubricant in a laboratory setup. Normally, the coefficient of friction and the amount of wear that occurred are measured while the wear scar surface is also evaluated. Special attention was paid to factors that affect the repeatability. The test fluid was subjected to a friction and wear test on the SRV test rig in order to determine what factors affect the repeatability of the coefficient of friction, the amount of wear that occurred and the wear scar appearance. The test fluid used was based on rapeseed oil and white mineral oil. The fluid also contained an extreme pressure additive in the form of sulphurised ester. This was also compared for the same test fluid with dispersed hexagonal-boron nitride (h-BN) nanoparticles. The standard test method as described by ASTM D 6425, was used as test method. Instead of the standard temperature, the block temperature was increased to 100 °C in order to simulate harsher operating environments. The load was set at 200 N It was found that:  The rapid load increase from 50 to 200 N at the end of the running-in period (as described in the standard test method) caused poor repeatability. The test was modified with a more gradual load application for the duration of the running-in period (30 N/min), which resulted in improvement in the repeatability of the tests conducted.  The moisture content in the atmosphere also affected the repeatability of the friction and wear tests. This was most likely due to the formation of a corrosion layer that involves water and by keeping the relative humidity constant, a further improvement in the repeatability was observed. The addition of the h-BN nanoparticles resulted in an improvement of the repeatability of the coefficient of friction (COF), wear scar surface (WSS) and wear scar volume (WSV), since the wear scar surfaces indicated that the particles remove the corrosion layers. This could have led to more consistent wear surfaces for the duration of the test.  The particles also influenced the corrosion layer formation. For both fluids, Raman spectroscopy indicated that greigite (Fe3S4) and goethite (α-FeOOH) were found on the surface, while additional corrosion products were found on the wear scar surface for the test fluid with dispersed particles. These compounds were melanterite (FeSO4.7H2O) and rozenite (FeSO4.4H2O). All these corrosion products were most likely formed due to the reaction of iron from the specimens with sulphurised esters in the test fluid.
Dissertation (MEng)--University of Pretoria, 2015.
tm2015
Chemical Engineering
MEng
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Capitoli di libri sul tema "Hexagonal-boron nitride (h-BN)"

Adachi, Sadao. "Hexagonal Boron Nitride (h-BN)". In Optical Constants of Crystalline and Amorphous Semiconductors, 127–36. Boston, MA: Springer US, 1999. http://dx.doi.org/10.1007/978-1-4615-5247-5_12.

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Majidi, Sima, Siamak Pakdel, Jafar Azamat e Hamid Erfan-Niya. "Hexagonal Boron Nitride (h-BN) in Solutes Separation". In Two-Dimensional (2D) Nanomaterials in Separation Science, 163–91. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-72457-3_7.

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Tay, Roland Yingjie. "A New Single-Source Precursor for Monolayer h-BN and h-BCN Thin Films". In Chemical Vapor Deposition Growth and Characterization of Two-Dimensional Hexagonal Boron Nitride, 99–115. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-8809-4_7.

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Wang, Q. W., J. Li, J. Y. Lin e H. X. Jiang. "Growth and properties of hexagonal boron nitride (h-BN) based alloys and quantum wells". In Wide Bandgap Semiconductor-Based Electronics. IOP Publishing, 2020. http://dx.doi.org/10.1088/978-0-7503-2516-5ch20.

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Atti di convegni sul tema "Hexagonal-boron nitride (h-BN)"

Wang, Yanan, Jaesung Lee, Yong Xie, Xu-Qian Zheng e Philip X. L. Feng. "High-Frequency Hexagonal Boron Nitride (h-BN) Phononic Waveguides". In 2019 IEEE 32nd International Conference on Micro Electro Mechanical Systems (MEMS). IEEE, 2019. http://dx.doi.org/10.1109/memsys.2019.8870808.

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Rah, Yoonhyuk, Yeonghoon Jin, Sejeong Kim e Kyoungsik Yu. "Birefringence and Dispersion Analysis of Hexagonal Boron Nitride (h-BN)". In CLEO: Science and Innovations. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/cleo_si.2019.sth3o.2.

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Wang, Yanan, Vivian Zhou, Jesse Berezovsky e Philip X. L. Feng. "Photophysical Characterization of Quantum Emitters in Hexagonal Boron Nitride (h-BN)". In Frontiers in Optics. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/fio.2019.jw4a.53.

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He, Qinyue, e Xun Yu. "Effect of Boron Nitride on the Mechanical and Electrochemical Properties of Cement Composite". In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53113.

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Hexagonal boron nitride (h-BN) is well known for its unique properties, such as high thermal conductivity, excellent mechanical strength, high electrical insulating, and high chemical stability. This paper studies the effect of h-BN to the mechanical and electrochemical properties of cement concrete. Sodium cholate is used as an ionic surfactant to exfoliate h-BN and subsequently stabilize them in water solution. Different cement concrete samples with different doping levels of h-BN and different sizes of h-BN were prepared for comparisons. Also, steel fiber reinforced h-BN/cement concrete samples were also prepared. The results show that the addition of h-BN can improve the strength of cement composites, and the degree of reinforcement are influenced by the doping levels and feature size of h-BN. The corrosion resistance of h-BN/cement composites were also tested. Experiments results show that h-BN can enhance the corrosion resistance of cement composites.

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Zheng, Xu-Qian, Jaesung Lee e Philip X. L. Feng. "Hexagonal boron nitride (h-BN) nanomechanical resonators with temperature-dependent multimode operations". In TRANSDUCERS 2015 - 2015 18th International Solid-State Sensors, Actuators and Microsystems Conference. IEEE, 2015. http://dx.doi.org/10.1109/transducers.2015.7181193.

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Gutierrez-Mora, F., A. Erdemir, K. C. Goretta, A. Domi´nguez-Rodri´guez e J. L. Routbort. "Water Lubricated Sliding Wear of Si3N4/BN Fibrous Monoliths". In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63897.

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Water-lubricated friction and wear of silicon nitride (Si3N4) and Si3N4/hexagonal boron nitride (H-BN) fibrous monoliths (FM) were investigated using a ball-on-flat tribometer. The effect of the BN matrix on the overall sample tribological behavior is discussed and correlated to microstructural observations. Experimental data are compared to dry and oil-lubricated wear and friction in the same materials.

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Wang, Yanan, e Philip Feng. "Hexagonal boron nitride (h-BN) 2D nanoscale devices for classical and quantum signal transduction". In Active Photonic Platforms XI, a cura di Ganapathi S. Subramania e Stavroula Foteinopoulou. SPIE, 2019. http://dx.doi.org/10.1117/12.2529858.

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Ito, H., K. Kazama e T. Kikutani. "Surface Replication and Structural Development in Micromolding for Micro/Nanocomposites". In ASME 2007 International Manufacturing Science and Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/msec2007-31035.

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Micromolding with micro-scale surface features of hexagonal boron nitride (h-BN) / polypropylene (PP) composites with different h-BN component was performed to improve molded parts’ heat diffusivity and processability. Effects of h-BN content and process parameters on processability, higher-order structure, and microscale surface patterns of molded parts were analyzed using SEM, WAXD, SPM, and confocal laser scanning microscopy. The replication ratio of the microscale surface pattern and flow length of composite molded parts was improved by compounding the h-BN filler. The replication ratio of the microscale surface pattern near the flow end became greater than 1.0 because of deformation of surface patterns during de-molding. The replication ratio and shape of surface patterns of molded parts were improved with the increase of the h-BN component. The h-BN platelet oriented inside surface micro-features; skin-shear-core structures were well observed in the molded parts.

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Elapolu, Mohan S. R., e Alireza Tabarraei. "Impact of Grain Boundaries on the Heat Conductivity of Mono-Layer Hexagonal Boron Nitride". In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71415.

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Reverse nonequilibrium molecular dynamics modeling is used to study the influence of grain boundaries on thermal properties of mono–layer hexagonal boron nitride (h–BN) nanoribbons. We consider symmetric grain boundaries consisting of series of pentagon–heptagon ring defects. Our results show a jump in the temperature profile at the location of grain boundary. The jump is consistently increasing with increase in the mis-orientation angle of nanoribbons with grain boundaries. This is attributed to an increase in the pentagon–heptagon defect density along the grain boundary. The temperature profile is used to calculate the Kapitza (interface) conductance of grain boundaries as a function of the misorientation angle of grain boundaries. Our results show that Kapitza conductance of the grain boundaries decreases with increase in the misorientation angle. Zigzag nanoribbons show slightly higher Kapitza conductance than armchair nanoribbons.

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Liang, Ting, Ping Zhang, Peng Yuan, Man Zhou e Siping Zhai. "Interfacial Thermal Conductance and Thermal Rectification Across In-Plane Graphene/h-BN Heterostructures With Different Bonding Types". In ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/mnhmt2019-4159.

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Abstract The in-plane graphene/hexagonal boron nitride (Gr/h-BN) heterostructures have received extensive attention in recent years due to their excellent physical properties and the development potential of next-generation nanoelectronic devices. Generally, different bonding types between Gr and h-BN are considered in different non-equilibrium molecular dynamics (NEMD) simulations studies. However, which type of bonding is most conducive to interface thermal transport is still very confusing. In this work, we investigate the interfacial thermal conductance (ITC) and the thermal rectification (TR) in five different bonding types of in-plane Gr/h-BN heterostructures by using NEMD simulations. It is found that the ITC depends strongly on the bonding strength and arrangement of different atoms across the boundary. Among the five different bonding types of heterostructures, the C-N bonded heterojunction exhibits the highest ITC due to its stronger interfacial bonding. The analyses on the strain distribution indicated that a low interfacial stress level at the interface junction, may facilitate the heat conduction, thus leading to a higher ITC. In addition, we found that TR occurs in all five bonded heterostructures, and the C-B bonded heterojunction possesses the highest TR factor. The present study is of significance for understanding the thermal transport behavior of Gr/h-BN heterostructures and promoting their future applications in thermal management and thermoelectric devices.

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Rapporti di organizzazioni sul tema "Hexagonal-boron nitride (h-BN)"

Ismach, Ariel, Harry Chao, Rodney S. Ruoff e Sanjay Banerjee. Synthesis and Characterization of Hexagonal Boron Nitride (h- BN) Films. Fort Belvoir, VA: Defense Technical Information Center, gennaio 2014. http://dx.doi.org/10.21236/ada616097.

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