Boron Oxide Research Articles

Afterglow of Dual‐Confined Carbon Dots Ranging from Blue to Near‐Infrared

AbstractComprehensive research into afterglow emission in the near‐infrared (NIR) region of carbon dots (CDs) is currently lacking. In this study, highly efficient multicolor CDs are synthesized with fluorescence from blue to NIR using Rhodamine 6G. Boron oxide (B2O3) is employed as a matrix for encapsulating and confining the CDs, inhibiting triplet exciton quenching. Furthermore, structural rigidity is enhanced due to the formation of carbon‐boron (C─B) covalent bonds between CDs and B2O3, achieving tunable afterglow emission ranging from 463 to 722 nm with lifetimes up to 801 ms. The green–yellow afterglow composite exhibits an impressive quantum yield up to 37.67% while demonstrating thermally activated delayed fluorescence (TADF). Thus, this composite is coated onto a blue alternating‐current light‐emitting diode (BAC‐LED) to fabricate a white AC‐LED, which is successfully prepared with Commission Internationale de L'Eclairage (CIE) at coordinates of (0.32, 0.34), accompanied by the color rendering index (CRI) reaching 81.1. The bright afterglow compensates for zero‐point flickering in the BAC‐LED, resulting in stable and gentle emission. The potential applications of these luminescent materials in optoelectronic devices are undoubtedly widened by this remarkable advancement.

Structural and spectroscopic correlation in barium-boro-tellurite glass hosts: effects of Dy2O3 doping

In this study, a series of barium-boro-tellurite glass hosts with varying concentration of Dy2O3 doping (0 to 1.25 mol%) were made by melt-quenching method. A study was conducted to investigate how Dy2O3 dopants affect the physical and spectroscopic traits of glasses. Raw materials including barium oxide (BaO), tellurium dioxide (TeO2), boron oxide (B2O3), and dysprosium oxide (Dy2O3) were used to produce these glasses. XRD patterns of the samples showed a broad hump and absence of long-range periodic lattice arrangements, indicating their amorphous nature. The Raman spectral analyses displayed the various vibration modes where the most intense band caused by BaO vibrations at 300 cm-1 and 450 cm-1 corresponding to the symmetric stretching vibration mode of Te–O–Te intra-chain bridges. The peak at 750 cm-1 was due to TeO4 and Te-O-Te vibration modes. The value of optical band gap energy was decreased from 3.155 to 2.1894 eV and then increase at higher Dy2O3 level (0.75 to 1.25 mol%). At Dy3+ contents between 0.25 to 1.25 mol% seven absorption bands were observed at 390, 424, 452, 750, 797, 895 and 1092 nm due to the electronic transitions in Dy3+. The glass refractive indices were raised from 2.3563 to 2.6584 and then decreased at higher Dy2O3 contents which was mainly because of the generation of more bridging oxygen (BO) in the glass matrix. The value of glass electronic polarizability and oxide ions polarizability calculated using LorentzLorenz equation showed a decrease with the rise of Dy2O3 contents, which was ascribed to the presence of fewer non-bridging oxygen (NBO). The optical basicity of the proposed glass hosts was calculated using Duffy and Ingram equation which was decreased with the increase of doping contents. In addition, the optical transmission was increased and reflection loss was reduced with increasing Dy+3 levels. The value of metallization parameter below 1 proved the true amorphous nature of the prepared samples. All the glasses revealed blue and yellow photoluminescence emission peaks due to 4F9/2→ 6H15/2, and 4F9/2 →6H13/2 transitions in Dy3+, respectively. The proposed glass compositions may be beneficial for the advancement of solid-state lasers.

The Synthesis of Three-Dimensional Hexagonal Boron Nitride as the Reinforcing Phase of Polymer-Based Electrolyte for All-Solid-State Li Metal Batteries.

Powdery hexagonal boron nitride (h-BN), as an important material for electrochemical energy storage, has been typically synthesized in bulk and one/two-dimensional (1/2D) nanostructured morphologies. However, until now, no method has been developed to synthesize powdery three-dimensional (3D) h-BN. This work introduces a novel NaCl-glucose-assisted strategy to synthesize micron-sized 3D h-BN with a honeycomb-like structure and its proposed formation mechanism. We propose that NaCl acts as the template of 3D structure and promotes the nitridation reaction by adsorbing NH3 . Glucose facilitates the homogeneous coating of boric acid onto the NaCl surface via functionalizing the NaCl surface. During the nitridation reaction, boron oxides (BO4 and BO3 ) form from a dehydration reaction of boric acid, which is then reduced to O2 -B-N and O-B-N2 intermediates before finally being reduced to BN3 by NH3 . When incorporated into polyethylene oxide-based electrolytes for Li metal batteries, 5 wt % of 3D h-BN significantly enhances ionic conductivity and mechanical strength. Consequently, this composite electrolyte demonstrates superior electrochemical stability. It delivers 300 h of stable cycles in the Li//Li cell at 0.1 mA cm-2 and retains 89 % of discharge capacity (138.9 mAh g-1 ) after 100 cycles at 1 C in the LFP//Li full cell.

Seeking borophene on Ni3Al(111): an experimental characterization of boron segregation and oxidation

Synthesis of a stable, well ordered honeycomb borophene (hB) phase has been achieved to date by exploiting Al(111) as a growth substrate, which provides the necessary charge doping to compensate the high hexagonal-holes density. However, B/Al(111) is governed by a strong B–Al interaction so to yield the actual formation of an AlB2 hB phase. Dilution of aluminum by alloying could then in principle weaken the boron-support bonding. By means of a combined spectroscopy and microscopy experimental approach, we find instead that the growth of boron layers on the Ni3Al(111) alloy termination is driven by B dissolution into the bulk and surface segregation mechanisms. While no long-range ordered boron-induced phase is observed, locally ordered superstructural units with triangular appearance are stabilized by substrate pinning, following the chemical p(2 × 2) surface order. Oxidation involves both boron and aluminum, inducing surface segregation of B, while nickel remains in its metallic form.

Enhanced ignition and combustion performance of boron-based energetic materials through surface modification and titanium dioxides coating

The present study focuses on the removal of ineffective hydroxyl surface (B–OH) of the shell of pristine boron (B) particles, followed by its modification using a low-cost, eco-friendly, and non-hazardous ethylene glycol (EG). Subsequently, very small-sized titanium dioxide (TiO2) particles are coated onto the boron surface by adding titanium tetraisopropoxide (TTIP) precursors at room temperature. Characterization techniques were employed to investigate the structure and morphology of these materials. FTIR, XPS, and TEM analysis reveal that EG effectively removes ineffective boron hydroxyl surfaces and modifies the surface through passivation by its surface functionalities. Furthermore, EG assists in the coating very small-sized TiO2 particles on the boron surface. Thermal stability tests show that the modified boron surface and TiO2-coated boron surface exhibit earlier oxidation of the core boron compared to pristine boron. This enhanced capability for earlier oxidation of core boron was further investigated in the shock tube and bomb calorimeter for measurement of ignition delay time and heat of combustion. The findings demonstrate that room temperature synthesized TiO2-coated B particles (ignition delay time of ∼181 μs and heat of combustion of ∼17.3 kJ/g) outperform pristine B particles (ignition delay time of ∼284 μs and heat of combustion of ∼13.2 kJ/g). This improvement is attributed to the removal of ineffective boron hydroxyl surfaces, surface modification, uniform coating with very small TiO2 particles, the catalytic effect of TiO2 on oxygen diffusion, and effective oxidation of core boron. This study suggests that efficient energetic material can be achieved at room temperature with no potential harm to the environment.

Mechanical properties and microstructure evolution of KD‐SA SiCf/BN/SiC CMCs oxidized at different temperatures

AbstractSilicon carbide fiber‐reinforced SiC ceramic matrix composites (SiCf/SiC CMCs) based on a domestic KD‐SA SiC fiber were exposed to a wet oxygen atmosphere for 135 h at 800, 1100, and 1300°C. The evolution of the microstructure and mechanical properties of SiCf/SiC CMCs have been systematically investigated following oxidation. For weight change, CMC‐1300 showed the greatest gain (0.394%), followed by CMC‐1100 (0.356%) and CMC‐800 (0.149%). The volatilization of boron oxide (B2O3) combined with the slight oxidation of the SiC matrix at 800°C caused crack deflection and fiber pull‐out. The complete dissipation of the interphase could be found when the oxidation temperature increases to 1100°C, generated a fracture surface with brittle fracture characteristics. At 1300°C, crystalline SiO2 hindered oxygen diffusion, with evidence of fiber pull‐out. Based on thermodynamic calculations and microscopic observations, we propose a mechanism to explain the thermal degradation of SiCf/SiC CMCs. This work offers valuable guidance for the fabrication of SiCf/SiC CMCs that are suitable for high‐temperature applications.

Improving the ablation resistance of epoxy modified organosilicon resin synergistic modified with B2O3 and ZrSi2

The boron oxide and zirconium silicide synergistic modified epoxy modified organosilicon resin composites were prepared and the ablation resistance properties of the composites were analyzed. With the synergistic effect of boron oxide and zirconium silicide, the properties, such as: the residue yield, hardness, tensile strength and ablation resistance (oxyacetylene ablation and static muffle furnace ablation) of the samples are markedly enhanced. The oxyacetylene linear ablation rate of the modified composite was observed to the minimum (0.04 mm s−1), when the contents of resin, boron oxide and zirconium silicide are 100 g, 50 g, and 150 g, respectively. The skeleton-like compact structure formed in the surface of composites after oxyacetylene ablation, which results in the best ablation resistance.

Magnesium cations as templates for the self-assembly of supramolecular luminescent {Mg@[B18φ34-35]}-clusters.

Solvothermal reaction of magnesium nitrate and boron oxide in N,N-dimethylformamide produced a number of particularly complex supramolecular magnesium borates. Five topologically different types of negatively charged {Mg@[B18φ34-35]}-clusters, φ = O, OH, were observed with the magnesium cation as a core and octadecaborate anions as shells. The clusters assemble via common borate polyhedra forming 1D chains, a 2D mesoporous layer, and 3D mesoporous frameworks with an effective channel width of up to 16 Å. Topological analysis of the clusters in combination with the modular crystallography approach indicates that numerous new functional materials can be obtained by varying their assembly mode. At least one compound containing such clusters exhibits a very strong luminescence.

EFFECT OF MAGNESIUM ON IGNITION AND COMBUSTION OF BORON-LOADED GELLED JET A-1 FUEL

Boron (B) is a desirable fuel for explosives and propellants due to its high-energy density. However, the combustion of B particles is difficult because its native oxide layers serve as inhibitors and cover the particles. This oxide layer makes the combustion process more difficult. However, using B as an additive in gelled fuel has significant potential use in ramjets. The present study used magnesium (Mg) with B-loaded gel-based fuel as a burning promotor. Different combustion parameters were evaluated for four different fuel compositions. The present investigation employed a droplet combustion setup and high-speed imaging technique to examine the impact of Mg on B particles in gel fuel. The influences of Mg addition on the droplet combustion flame, B ignition delay time, boron oxide (BO<sub>2</sub>) intensity, and post-combustion particles were studied. The addition of Mg significantly influenced B in reducing the ignition delay time, where the reduction was almost 70.58% at higher Mg loadings (GBMg30). The combustion of B-based samples resulted in the emission of BO<sub>2</sub>, which was characterized by a greenish appearance. The findings were corroborated by spectroscopic analysis. The analysis of the burning events was conducted utilizing a combination of color and high-speed camera techniques in conjunction with a 546 nm BO<sub>2</sub> filter. Post-combustion particles were analyzed with the help of scanning electron microscopy images and thermogravimetric analysis.

Melt-casted Li1.5Al0.3Mg0.1Ge1.6(PO4)3 glass ceramic electrolytes: A comparative study on the effect of different oxide doping

The development of Li-ion conducting solid-state electrolytes (SSEs) is crucial to achieve increased energy density, operative reliability, and unprecedented safety to replace the state-of-the-art Li-ion battery (LIB). In this regard, we here present the successful melt-casting synthesis of a MgO-added NASICON-type LAGP glass-ceramic electrolyte with composition Li1.5Al0.3Mg0.1Ge1.6(PO4)3, namely LAMGP. The effects of three different additional oxides are investigated, with the aim to improve grain cohesion and consequently enhance Li-ion conductivity. Specifically, yttrium oxide (Y2O3, 5 mol%), boron oxide (B2O3, 0.7 mol%) and silicon oxide (SiO2, 2.4 %mol) are added, yielding LAMGP-Y, LAMGP-B and LAMGP-Si, respectively. Their effects are exhaustively compared in terms of thermal, crystalline, structural/morphological and ion conducting features. Among the three oxides, B2O3 is able to positively act on grain boundaries without bringing along grains deformation and insulating secondary phases formation, achieving enhanced ionic conductivity of 0.21 mS cm−1 at 20 °C as compared to 0.08 mS cm−1 for a commercial LAGP subjected to the same thermal treatment. A remarkable anodic oxidation stability up to 4.8 V vs Li+/Li is assessed by LAMGP-B system, which accounts for promising prospects for its use in combination with high-energy (high-V) cathodes.

Boron removal by iron-aluminum combined anodes from fracturing flowback fluid: Advantages and mechanisms

During the process of oilfield wastewater reuse, residual Boron in fracturing flowback fluid will lead to premature crosslinking with gelling agents, resulting in excessive viscosity at the front end of the fracturing fluid configuration. This phenomenon has heavily influenced the reuse of wastewater. Electrocoagulation (EC), as an effective approach to decreasing Boron concentration, has been widely studied, while further research of Boron removal from complicated wastewater is required to optimize. EC parameters were investigated to explore the optimal Boron removal effect of Fe, Al and Fe-Al three combined anodes. Under 46.3–57.2 mA/cm2, 90 min and pH of 9, Fe-Al anodes exhibit the best effect of Boron removal (84% ± 1.5%). Furthermore, high adaptive capacity of low current density and suitable pH confirm the best choice of Fe-Al combined anodes. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) demonstrate the complexation between Boron and metallic oxide. Finally, the common removal of various pollutants including Ca, Cl, K and Na further conduces to the reuse of oil wastewater.

DFT-based 11B solid-state NMR calculations for guiding fine local structure identification and phase-property modulation in ZnxY1-xBO3-0.5x borate oxide ion conductors.

Solid-state nuclear magnetic resonance (NMR) spectroscopy serves as a powerful technique for probing local structures. However, the interpretation of NMR signals mainly based on empirical knowledge could lead to imprecise local structural determinations. To address this, density functional theory (DFT)-based theoretical NMR calculations, aided by experimental three-dimensional continuous rotation electronic diffraction (3D cRED) technique, were performed for ZnxY1-xBO3-0.5x borate oxide ion conductors. The calculations provided fine local structure identification for the experimental 11B NMR spectra of ZnxY1-xBO3-0.5x, providing rich information on multiple experimental 11B NMR signals towards the complex boron oxide anions associated with bridging oxygen vacancies and the coexistence of the monoclinic (C2/c), hexagonal (P63/m), and trigonal (R32) phases in ZnxY1-xBO3-0.5x. Owing to the advantages of solid-state NMR in identifying closely related phases compared to X-ray/neutron diffraction technique, along with the advanced 3D cRED technique that allows for rapid phase identification and structure determination, we provide a fine local structure identification and a more inclusive insight into the coexistence of multiple phases in borate with the same composition. More importantly, this work provides guidance for phase and property modulation. Phase modulation in ZnxY1-xBO3-0.5x was carried out with thermodynamic and kinetic modulation and eventually realized the tuning of the local structures and the resultant oxide ion conductivity of ZnxY1-xBO3-0.5x. This work provides a theoretical and experimental platform to access the flexible structural assignment of boron oxide anions and therefore offers new guidance and insights into the defect structures and the phase-property modulation of inorganic solid functional materials beyond borate oxide ion conductors.

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.

Hour-Level Persistent Multicolor Phosphorescence Enabled by Carbon Dot-Based Nanocomposites Through a Multi-Confinement-Based Approach.

Hour-level persistent room temperature phosphorescence (RTP) phenomena based on multi-confinement carbon dots (CDs) are reported. The CDs-based system reported here (named Si-CDs@B2O3) can be efficiently synthesized by a simple pyrolysis method compared to the established persistent RTP systems. The binding modes of CDs, silica (SiO2), and boron oxide (B2O3) are deduced from a series of characterizations including XRD, FT-IR, and TEM characterization. Further studies show that the formation of covalent bonds between B2O3, SiO2, and CDs play a key role in activating the persistent RTP and preventing its quenching. This is a rare example of a persistent RTP system that exhibits hourly persistent RTP under environmental conditions. Finally, the applications of Si-CDs@B2O3 are demonstrated for anti-counterfeiting, long-duration phosphorescence imaging, and fingerprinting. This synthetic strategy is expected to provide strong technical support for the preparation of persistent RTP CDs and pave the way for the synthesis of persistent RTP CDs in the future.

Nano Boron Oxide and Zinc Oxide Doped Lignin Containing Cellulose Nanocrystals Improve the Thermal, Mechanical and Flammability Properties of High-Density Poly(ethylene).

The widely used high-density polyethylene (HDPE) polymer has inadequate mechanical and thermal properties for structural applications. To overcome this challenge, nano zinc oxide (ZnO) and nano boron oxide (B2O3) doped lignin-containing cellulose nanocrystals (L-CNC) were blended in the polymer matrix. The working hypothesis is that lignin will prevent CNC aggregation, and metal oxides will reduce the flammability of polymers by modifying their degradation pathways. This research prepared and incorporated safe, effective, and eco-friendly hybrid systems of nano ZnO/L-CNC and nano B2O3/L-CNC into the HDPE matrix to improve their physio-mechanical and fire-retardant properties. The composites were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis, thermo-gravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, horizontal burning test, and microcalorimetry test. The results demonstrated a substantial increase in mechanical properties and a reduction in flammability. The scanning electron microscope (SEM) images showed some agglomeration and irregular distribution of the inorganic oxides.

Pycnometric-Additive Determining of the Degree of Coating of High-Strength Synthetic Diamond Grinding Powders using the Actual 3D Morphology of their Grains

The methodological components of direct and indirect analytical determining of the degree of coating of synthetic diamond grinding powders are analyzed. It has been established that the weight method most used in practice for determining this technological property of grinding powder is not universal for different methods of applying the coating. More universal in this regard, as the review of publications showed, is the well-known indirect-analytical method based on the pycnometric-additive approach. An improved variant of this method is proposed, aimed at application to high-strength synthetic diamond grinding powders. The method takes into account the peculiarities of the 3D morphology of the grains of such powders. Using the example of grinding powder AC300 500/400, the grains of which were coated with a solution of a mixture of boron oxide, sodium silicate, and titanium carbide, the advantages of using the proposed method are illustrated. The results of a comparison of determining the degree of coating by a known method and its improved variant are presented.

One-step preparation of bi-layer foamed glass-ceramics using asynchronous oxidization of SiC and B4C

Bi-layer foamed glass-ceramic has the advantages of both dense and foamed structure which lead to low bulk density and high mechanical strength. We propose a new one-step method to produce bi-layer foamed glass-ceramic using the asynchronous oxidization of B4C and SiC. The parent glass is prepared by melting-quenching method, followed by foaming through powder sintering route with addition of B4C and SiC. The bi-layer structure and formation of bi-layers are investigated by scanning electron microscope (SEM), X-ray computed tomography, 11B NMR, and high temperature melting observation system (HTMOS). The results show that during the sintering process, the oxidization of B4C in top layer at low temperature forms boron oxide and helps the formation of glass melt in the top layer. The oxidization of SiC at high temperature leads to foaming in the top layer. The prepared bi-layer foamed glass-ceramic has low bulk density of 1.06 g·cm−3 and high flexural strength of 26.15 MPa.

Unveiling the Potential of B3O3 Nanoflake as Effective Transporter for the Antiviral Drug Favipiravir: Density Functional Theory Analysis.

In this study, for the first time, boron oxide nanoflake is analyzed as drug carrier for favipiravir using computational studies. The thermodynamic stability of the boron oxide and favipiravir justifies the strong interaction between both species. Four orientations are investigated for the interaction between the favipiravir and the B3O3 nanoflake. The Eint of the most stable orientation is -26.98 kcal/mol, whereas the counterpoise-corrected energy is -22.59 kcal/mol. Noncovalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses are performed to obtain insights about the behavior and the types of interactions that occur between B3O3 nanoflake and favipiravir. The results indicate the presence of hydrogen bonding between the hydrogen in the favipiravir and the oxygen in the B3O3 nanoflake in the most stable complex (FAV@B3O3-C1). The electronic properties are investigated through frontier molecular orbital analysis, dipole moments and chemical reactivity descriptors. These parameters showed the significant activity of B3O3 for favipiravir. NBO charge analysis transfer illustrated the charge transfer between the two species, and UV-VIS analysis confirmed the electronic excitation. Our work suggested a suitable drug carrier system for the antiviral drug favipiravir, which can be considered by the experimentalist for better drug delivery systems.

Enhancing gamma-ray shielding with bismuth oxide-infused boron oxides

Enhancing gamma-ray shielding with bismuth oxide-infused boron oxides

Unveiling the temporal evolution of boron oxide exciplex species in laser-induced plasma: A detailed analysis of ro-vibrational spectra

The temporal evolution of boron oxide (BO) exciplex species in ambient air atmosphere was analyzed spectroscopically. The ro-vibrational bands (RVB) corresponding to BO:B2Σ+ → X2Σ+, BO:A2Πi → X2Σ+, and BO2: A2Πu → X 2Πg transitions were identified from experimentally recorded emission spectra of boric acid pellets. Temporal evolution and temporal intensity decay investigations were conducted on selected RVBs for each transition. The intensity decay rate of electronic transition was found to remain constant, regardless of the vibrational levels in the excited and ground electronic state. The type of the intensity decay profile and the decay rate contents were utilized to understand the extent of the spectral interference from BO: A2Πi - X2Σ+ transition by BO:B2Σ+- X2Σ+and BO2:A2Πu- X 2Πg transitions. By utilizing the Signal-to-envelope ratio, an optimum acquisition delay time was determined for the spectroscopic analysis of various transitions. This research study sheds light on the spectral interferences present in the optical emission spectra of RVBs and provides a comprehensive understanding of the spectral purity of these bands associated with BO exciplex species.