Boron Oxide Powders Research Articles

Recent Theoretical Advancement of Boron-Rich Compounds for Applications in High-Density Energy Conversion Devices

Boron-rich compounds (IBCs) such as boron suboxide (B6O) and boron subphosphide (B12P2) are derived from the α-rhombohedral boron lattice with extreme hardness and unusual electrical properties. These compounds display an extraordinary self-healing ability to repair the lattice defects generated from exposure to high-energy irradiation. This unique ability will enable these boron-rich compounds to be deployed in nuclear battery devices for space or deep-sea exploration applications when coupled with their high hole mobility.Synthesis and control of the stoichiometry of IBCs are the key technical challenge. For instance, the electrical properties of B6O are susceptible to specific B:O ratios. Thus far, the highest quality B6O crystals were obtained from high-pressure, high-temperature (HP-HT) experiments using mixed boron and boron oxide powders. Nevertheless, a mature synthesis protocol yielding consistent, high-quality B6O crystals has not been established.In this talk, density functional theory (DFT) was used to understand how the structural, electronic, and thermodynamic stabilities of B6O (and other IBCs) are influenced by the interstitial elements and point defects at the icosahedral sites. Using the hybrid HSE functional, we confirmed that the perfect B6O bulk is a p-type semiconductor with a direct band gap of 2.8 eV. Furthermore, by screening the α-boron compounds systematically, we found that a simple octet rule may offer a consistent explanation for the variations in the computed electronic structures. Then, the thermodynamic calculations based on the DFT method predict that formations of interstitial defects become favorable only at higher temperatures.To understand the self-healing property, the nudged elastic band (NEB) method was employed to identify the minimum energy pathways for the diffusions of dislocated B and O atoms. The diffusion of icosahedral B atoms has an energy barrier of 0.16 eV, confirming that the boron vacancies can be repaired with little kinetic limitation. Nevertheless, a substantially perturbed lattice requires more complex structural reorganization and thus incurs higher barriers (> 1 eV).Lastly, reactive molecular dynamics simulations with a frozen core were performed to gain insights into the initial crystal nucleation process using a newly developed ReaxFF force field. For the first time, we can gain a molecular perspective on the formations of the boron icosahedra (B12) motif and the energetic profile. Such knowledge will aid the experimental design of IBC synthesis.

Transfer-free synthesis of large-area 2D boron films on non-wetting liquid gallium substrate

Two-dimensional (2D) boron films have been studied for their attractive physical and chemical properties in diverse technologies. However, the synthesis of large scale and high-quality boron films is still challenging, which limit its applications in high-performance devices. In this work, thin 2D boron films have been synthesized by chemical vapor deposition (CVD) on non-wetting liquid gallium (Ga) spheres by using boron and boron oxide powders as solid sources. The thin films were directly exfoliated onto SiO2/Si substrates to prepare smooth and uniform boron films by means of mechanical exfoliation method. The peak of boron at 618 cm−1 wave number is obtained by Raman characterization and the boron peak at 188.8 eV is obtained by XPS, which indicates that the film is elemental boron film. By controlling the intercalation chemistry, we obtained large-area 2D polycrystalline boron films with a thickness of 0.8 nm by using transfer-free Synthesis, which avoids the introduction of impurities. The research promotes the application of 2D boron thin film materials in electrical and optical devices.

Au nanospheres modified boron-doped diamond microelectrode grown via hydrogen plasma etching solid doping source for dopamine detection

Boron doped diamond (BDD) electrode is a promising electrochemical material for detecting dopamine level in the human’s body. In this work, we developed a new doping source - graphite and solid boron oxide powders to synthesize BDD film with microwave plasma chemical vapor deposition, so as to avoid using toxic or corrosive dopants, such as boroethane and trimethylborate. The synthesized BDD film is pinhole free and with high doping density of 8.44 × 1020 cm−3 calculated from the Raman spectroscopy. Subsequently, Au nanospheres were decorated on the surface of BDD film to improve electrochemical performance of the BDD film. The Au nanoparticles modified BDD electrode demonstrates an excellent electrochemical response, a high sensitivity (in the range of 5 μM-1 mM), and a low detection limit (∼ 0.8 μM) for detecting dopamine.

Effect of Iron Doping on Photocatalytic Activity of Boron Oxide Processed Using Polyvinyl Borate Precursor

In this study, boron oxide (B 2 O 3 ) powder has been synthesized by the pyrolysis of polyvinyl borate precursor in air. For this purpose, polyvinyl borate precursor was synthesized through the condensation reaction of polyvinyl alcohol and boric acid, and then the polymeric precursor was pyrolyzed at 500°C. The as-prepared B 2 O 3 particles were doped with iron (Fe) ions using the wet impregnation method. The photocatalytic activity of both undoped B 2 O 3 and iron doped B 2 O 3 (Fe-B 2 O 3 ) powders was studied by investigating the degradation of the model dye, methylene blue, under UV light irradiation. It was pointed out that iron doped B 2 O 3 powder exhibited enhanced photocatalytic activity compared to undoped one. In addition, various techniques of characterization such as FTIR, XRD, FESEM, EDX and UV–Vis spectroscopy were performed to confirm the synthesis of B 2 O 3 particles and the presence of iron ions in the crystal structure of the prepared photocatalyst. The novelty of this study was to research the photocatalytic performance of both B 2 O 3 and Fe-B 2 O 3 photocatalysts.

Coating of B2O3 and Al2O3 containing Hydroxyapatite on Ti6Al4V by HVOF Technique

Calcium phosphate (Ca-P) based bioceramics has proved to be alluring materials for biomedical applications. Among these, particular attention has been given to hydroxyapatite (HA), Ca10(PO4)6(OH)2. Due to its favorable some physical, mechanical, chemical properties and biocompatibility, HA-coated Ti6Al4V alloy has been approved as one of the most interesting implant materials for orthopedic and dental applications. High Velocity Oxy Fuel (HVOF) is a method used to coat hydroxyapatite (HA) on metallic implants such as titanium (Ti) and its alloy (Ti6Al4V). In this work decreasing the crack occurrence and increasing adhesion strength were investigated. For this purpose, sol-gel synthesized nano sized HA, alumina (Al2O3) and Boron oxide (B2O3) powders were produced. First, a series of HA/Al2O3 HA/B2O3 coatings have been deposited on Ti6Al4V substrate by HVOF method. All specimens’ surfaces were used to characterize by using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM-EDS) and X-ray Diffraction (XRD). Adhesion strength of the samples was found to affect with increasing amount of Al2O3 and B2O3 in HA. Furthermore, water contact angles of coating layer were decreased with increasing amount of Al2O3 and B2O3 in HA. This coating surface was expected to combine the advantages of Ca-P (osseointegration) and adhesion strength.

Preparation of Cast Mo2B5 by Self-Propagating High-Temperature Synthesis Metallurgy Methods

This paper reports the preparation of cast dimolybdenum pentaboride by a self-propagating high-temperature synthesis (SHS) metallurgy method. Experiments were carried out in SHS reactors at an initial excess gas (Ar) pressure p0 = 5 MPa. In the experiments, we used thermite-type starting mixtures consisting of molybdenum oxide, aluminum, boron oxide, and elemental boron powders. The combustion of such mixtures yields two types of final product: Mo2B5 and Al2O3. The combustion temperatures of the starting mixtures used in our experiments have been shown to exceed the melting points of the final products, which are thus formed in a liquid (cast) state. Under the effect of gravity, the heavier phase Mo2B5 settles down to form a lower ingot, whereas the lighter phase Al2O3 forms an upper ingot. The synthesis products have been characterized by X-ray diffraction and local microstructural analysis. The results demonstrate that the composition and amount of the starting mixture have a significant effect on the synthesis parameters and the composition and microstructure of the Mo2B5. We have optimized conditions for the preparation of single-phase cast dimolybdenum pentaboride.

Simultaneous machining and surface alloying of AISI 1040 steel by electrical discharge machining with boron oxide powders

In PM/EDM, it is known that when used electrically conductive powders, highly homogeneous alloyed layers can be formed where the gap extends slightly more than using non-conductive powders and regulates spark discharge and machining voltage more uniform. Boron element is non-conductive but when alloyed with steel, materials with high abrasion and corrosion resistance are obtained. In this study, the effects of boron oxide powders addition into dielectric fluid on microstructure and hardness of steel workpiece in electrical discharge machining (EDM) were investigated. For this purpose, by using a prismatic steel workpiece and a copper electrode in kerosene mixed with boron oxide (B2O3) powders, the morphology of the machined specimens at different powder concentrations and pulse duration settings were observed and investigated. In addition, the micro hardness of the layers occurred as a result of EDM was measured and discussed. The highest surface hardness value of 941 HV is measured over machined specimen with B2O3 powder addition, whereas the lowest surface hardness value of 413 HV is measured.

Bor oksit tozunun fren balatalarının tribolojik özelliklerine etkisi

Bu çalışmada, Renault Clio otomobilin fren balatası, bor oksit tozu katkısı ile sıcak presleme yöntemiyle üretilerek, bor oksit tozunun balatanın tribolojik özellikleri üzerine etkisi deneysel olarak araştırılmıştır. Son yıllarda çevre dostu malzemelerin kullanılmasının önem kazanmasından dolayı fren balatasının içeriğinde bor oksit kullanılmıştır. Ayrıca bu malzemenin seçilmesinde ülke ekonomisine fayda sağlamakta amaçlanmıştır. Karşılaştırma yapmak için ticari Clio balatası kullanılmıştır. Balata numunelerinin aşınma sürtünme deneyleri Chase tipi cihazda yapılmıştır. Bor oksit katkısının fren balatasının aşınma sürtünme performansına etkisi ticari fren balatasının sonuçlarıyla kıyaslanarak incelenmiştir. Sonuçta bor oksit katkısının sürtünme katsayısına olumlu etki yaptığı gözlenmiştir.

Boron Doped Graphene 3-Dimensi untuk Superkapasitor Kapasitas Tinggi

Chemical doping is an effective approach to improve the property of carbon material. In this study boron doped graphene with 3D structure used as the electrode was investigated. Boron doped graphene was prepared through freeze-dried process followed by pyrolysis of graphene oxide (GO) with three types of chemical substances; boron oxide, boric acid, and boron powder in an argon and hydrogen atmosphere at 1000 C for 3 hours. The difference of chemical composition generated a different percentage of boron bond with GO. The results shows that the highest electrochemical performance was found in graphene samples with the addition of boric acid (BA) 86 F/g, followed by boron oxide (BO) 59.2 F/g, and boron powder (BP) 2 F/g. It can be caused by boron concentration bound with graphene. The higher concentration of boron could be increased the electrochemical performance due to better of ion movement.

Microstructure and Mechanical Properties of ZrB2/Alumina/Mullite Composite Synthesized by Combined SHS and Direct Consolidation

ABSTRACTA highly dense object of ZrB2/alumina/mullite composite was synthesized via combustion synthesis combined with a direct consolidation technique from a blend of zircon, aluminum, and boron oxide powders. The influences of preheating temperature; Al particle size; and compaction load on porosity, microstructures, and mechanical properties of final products were investigated. Heating the sample prior to ignition led to development of cracks and coarser particle sizes, while increasing or decreasing the particle size of Al more or less than 37 µm led to inhomogeneous microstructure and cracks formation. Immediate application of 292 MPa contributed to a crack-free product of 1040 HV hardness and less than 1.0 vol% porosity with uniform microstructure. Detailed thermodynamic study of the combustion reaction is discussed.

Reactions in Ternary System Al-B<sub>2</sub>O<sub>3</sub>-C during Mechanical Alloying

One possible route for producing the fine and homogenous distribution of hard particles in composite microstructure is the mechanochemical processing in which high-energy ball milling promotes the reaction in a mixture of reactive powders. This investigation aims to produce Al – B4C nanocomposite by reaction between aluminum, boron (III) oxide and graphite powder via a mechanochemical process. The effect of milling time and the ratio the balls to powder on this process were investigated. The face transformation ans structural evaluation were investigated means of X – Ray diffractometry (XRD) and scanning electron microscopy (SEM).

In situ synthesis of NbB2–Al2O3 nanocomposite powder by mechanochemical processing

ABSTRACTThis research is based on the production of NbB2–Al2O3 nanocomposite powder using mechanochemical processing. For this purpose, a mixture of niobium, aluminium and boron oxide powders was subjected to high-energy ball milling. The structural evaluation of powder particles after different milling times was conducted by the X-ray diffractometry (XRD), scanning electron microscopy, and transmission electron microscopy. The results showed that during ball milling the Nb/Al/B2O3 reacted with a combustion mode producing NbB2–Al2O3 nanocomposite. The XRD analyses exhibited that the NbB2–Al2O3 nanocomposite was formed after 10 h milling time and increasing milling time up to 30 h had no significant effect other than refining the crystallite size. In the final stage of milling, the crystallite sizes of NbB2 and Al2O3 were estimated to be less than 50 nm.

Synthesis of hexagonal boron nitride fibers within two hour annealing at 500 °C and two hour growth duration at 1000 °C

Several advantageous features like low density, large surface area, high porosity and tight pore size make the nanofiber suitable for a wide range of applications from medical to consumer products and industrial to high-tech applications. Present study concerns the synthesis of hexagonal boron nitride fibers (Ø=70–350nm) from a mixture of Boron, Magnesium oxide and Iron oxide powders via a simple CVD technique. A relatively long annealing and growth duration of two hours at 500°C and 1000°C, respectively were utilized in this synthesis. The synthesized samples seem to have the BNFs of irregular curved human hair-like morphologies in lower resolution and solid cylinder-like structures in high resolution transmission electron microscopy. The presence of Boron and Nitrogen in the synthesized BNF's sample were confirmed via the B 1s peak at 190.7eV and N 1s peak at 398.3eV in the XPS survey whereas a major peak at 1370 (cm−1) in the Raman spectrum corresponds to the vibration of E2g mode in h-BN. The sharp peaks in the XRD pattern verify the h-BN phase and highly crystalline nature of the synthesized BNFs.

RETRACTED ARTICLE: Increase of the Surface Mobility of Carbon Molecular Crystals (CMCs) Using the PECVD Technique

Large-area boron doped multi-layer carbon is synthesized by the plasma enhanced chemical vapour deposition (PECVD) using boron oxide powder and ethanol vapor. We have reviewed the carbon molecular crystals preparation by the PECVD method. The three main synthesis methods of carbon nanocrystals (CNCs) are the arc discharge, the laser ablation and the chemical vapour deposition with a special regard to the later one. By two different methods, ZnO layers were coated on the tubes. RF sputtering was one of the ways to directly deposit ZnO thin layer on the MWCNCs. On the other hand, we used thermally physical vapour deposition for making thin Zn film to oxidize it later. Scanning electron microscopy and also Raman spectroscopy measurements of the prepared samples confirmed the presence of ZnO nanolayers on the CNC bodies.

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

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

Synthesis of Atomically Thin Boron Films on Copper Foils.

Two-dimensional boron materials have recently attracted extensive theoretical interest because of their exceptional structural complexity and remarkable physical and chemical properties. However, such 2D boron monolayers have still not been synthesized. In this report, the synthesis of atomically thin 2D γ-boron films on copper foils is achieved by chemical vapor deposition using a mixture of pure boron and boron oxide powders as the boron source and hydrogen gas as the carrier gas. Strikingly, the optical band gap of the boron film was measured to be around 2.25 eV, which is close to the value (2.07 eV) determined by first-principles calculations, suggesting that the γ-B28 monolayer is a fascinating direct band gap semiconductor. Furthermore, a strong photoluminescence emission band was observed at approximately 626 nm, which is again due to the direct band gap. This study could pave the way for applications of two-dimensional boron materials in electronic and photonic devices.

Synthesis of Atomically Thin Boron Films on Copper Foils

AbstractTwo‐dimensional boron materials have recently attracted extensive theoretical interest because of their exceptional structural complexity and remarkable physical and chemical properties. However, such 2D boron monolayers have still not been synthesized. In this report, the synthesis of atomically thin 2D γ‐boron films on copper foils is achieved by chemical vapor deposition using a mixture of pure boron and boron oxide powders as the boron source and hydrogen gas as the carrier gas. Strikingly, the optical band gap of the boron film was measured to be around 2.25 eV, which is close to the value (2.07 eV) determined by first‐principles calculations, suggesting that the γ‐B28 monolayer is a fascinating direct band gap semiconductor. Furthermore, a strong photoluminescence emission band was observed at approximately 626 nm, which is again due to the direct band gap. This study could pave the way for applications of two‐dimensional boron materials in electronic and photonic devices.

Characterization of neutron flux spectra in the irradiation sites of a 37 GBq 241Am-Be isotopic source

For the applicability of instrumental neutron activation analysis (NAA) technique, an irradiation unit with a 37GBq 241Am-Be neutron source was installed at Institute of Nuclear Sciences of Ankara University. Design and configuration properties of the irradiation unit are described. It has two different sample irradiation positions, one is called site #1 having a pneumatic sample transfer system and the other is site #2 having a location for manual use. In order to characterize neutron flux spectra in the irradiation sites, the measurement results were obtained for thermal (Фth) and epithermal neutron fluxes (Фepi), thermal to epithermal flux ratio (f) and epithermal spectrum shaping factors (α) by employing cadmium ratios of gold (Au) and molybdenum (Mo) monitors. The activities produced in these foils were measured by using a p-type, 44.8% relative efficiency HPGe well detector. For the measured γ-rays, self-absorption and true coincidence summing effects were taken into account. Additionally, thermal neutron self-shielding and resonance neutron self-shielding effects were taken into account in the measured results. For characterization of site #1, the required parameters were found to be Фth=(2.11±0.05)×103ncm−2s−1, Фepi=(3.32±0.17)×101ncm−2s−1, f=63.6±1.5, α=0.045±0.009, respectively. Similarly, those parameters were measured in site #2 as Фth=(1.49±0.04)×103ncm−2s−1, Фepi=(2.93±0.15)×101ncm−2s−1, f=50.9±1.3 and α=0.038±0.008. The results for f-values indicate that good thermalization of fast neutrons on the order of 98% was achieved in both sample irradiation sites. This is because an optimum combination of water and paraffin moderator is used in the present configuration. In addition, the shielding requirements are met by using natural boron oxide powder (5.5cm) and boron loaded paraffin layers against neutrons, and a 15cm thick lead bricks against gamma-rays from source and its surrounding materials.

Production of Nanosized Boron Oxide Powder by High-Energy Ball Milling

In this research, an attempt has been made to modify the microsized B2O3 powder into nanosized B2O3 powder using ball mill. The sample was taken out after various hours of milling and it was characterized for the crystallite size. The crystallite size was >100, 30, and 19 nm in 0, 1, and 5 h of milling time, respectively. The experimental results showed that the size of the nanostructure of particles for the total duration of 5 h was in the range of 24–95 nm. The shape of the 5 h milled particles was round and the surface morphology is rough.

One-dimensional nickel borate nanowhiskers: characterization, properties, and a novel application in materials bonding

The growth of nickel borate [Ni3(BO3)2] nanowhiskers was successfully achieved by simply heating a mixture of nickel and boron oxide (B2O3) powders at 950 °C in air. The products were characterized using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The synthesized nanowhiskers, with diameters of 150–500 nm and lengths of 10–30 μm, possessed high aspect ratio, and were found to grow along the [012] crystallographic direction. Stacking faults, hollow interiors, and high-energy facets were found occasionally. The high-temperature stability of Ni3(BO3)2 nanowhiskers was investigated. The nanowhiskers partially decomposed after being treated at 1200 °C. Based on the solid–liquid–solid mechanism, the possible growth process of Ni3(BO3)2 nanowhiskers was discussed. Ni3(BO3)2 nanowhiskers were successfully used for bonding nickel in air. The nickel/nanowhisker/nickel joint was characterized in detail by scanning electron microscopy and laser scanning confocal microscopy.