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Novel method exploration of monitoring neutron beam using Cherenkov photons in BNCT
摘要： Ensuring the stability of the neutron beam during boron neutron capture therapy (BNCT) is essential. The goal of this work was to explore a novel method using Cherenkov photons for real-time monitoring of neutron beam in BNCT. The Monte Carlo toolkit Geant4, was used to calculate the Cherenkov photons and dose based on a cubic phantom and Chinese hybrid radiation phantom under di?erent conditions. Based on the study on the cubic phantom, the change of neutron beam characteristics indeed have an impact on dose, which needs quality assurance. The relationship between Cherenkov photons and gamma dose was favorable. The maximum relative variation of the generation of Cherenkov photons is approximately 3.51%, even when the relative change of boron concentration reaching 60%. However, comparing the results of the neutron beam with the original characteristics, the maximum relative variation of Cherenkov photons reaches 14.75% and 14.68% for the usage of Neuboron- spectrum and 5-degree rotation of neutron beam ?eld orientation, respectively. Therefore, the intensity and distribution of Cherenkov photons can only be observably changed by neutron beam characteristics. Based on the Chinese hybrid radiation phantom, the changes in the intensity and distribution of Cherenkov photons can also be observed inside the phantom, and these changes are evident by a detector outside the phantom. Thus, Cherenkov photons has the potential application for neutron beam monitoring.
关键词： Neutron beam,Boron neutron capture therapy,Cherenkov photons,Monitoring
更新于2025-09-23 15:21:21
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Structure, morphology and dielectric properties of hexagonal boron nitride nanoparticles reinforced biopolymer nanocomposites
摘要： Hexagonal boron nitride nanoparticles (h-BNNPs)/Chitosan (CS)/Hydroxypropyl methylcellulose (HPMC) based ternary nanocomposites were prepared using solution casting method and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analyses (TGA), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM). The dielectric properties of CS/HPMC/h-BNNP nanocomposite films were also investigated as a function of frequency and temperature and a maximum dielectric constant of ~1200 was achieved at 5 wt % of h-BNNP loading in CS/HPMC blend matrix. The results from the structural, morphological and thermal studies revealed good interactions between h-BNNPs, CS and HPMC.
关键词： Hexagonal boron nitride,dielectric studies,solution casting,biopolymers
更新于2025-09-23 15:21:21
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Self-assembled CdS@BN core-shell photocatalysts for efficient visible-light-driven photocatalytic hydrogen evolution
摘要： CdS@BN NRs core-shell photocatalysts for hydrogen evolution were synthesized by a solvothermal and chemical adsorption method. CdS NRs coated by 5 wt% boron nitride (BN) shell exhibited remarkably visible-light photocatalytic hydrogen evolution activity of up to 30.68 mmol g?1 h?1, nearly 6.79 times higher than that of pure CdS NRs, and the apparent quantum efficiency at 420 nm was 7.5%. Transmission electron microscopy showed the CdS NRs were coated with a thin (~5 nm) BN layer, which together with the hydrogen evolution results proved the photocatalytic ability of CdS NRs was significantly improved. The hydrogen evolution rate of CdS NRs coated by 5 wt% BN remained at 91.4% after four cycles, indicating the photocorrosion of CdS NRs was effectively alleviated. Moreover, the large and close coaxial interfacial contact between the CdS core and the BN shell was beneficial to the separation and transfer of photogenerated electron-hole pairs.
关键词： Core-shell structure,Photocatalytic hydrogen evolution,CdS Nanorods,Boron nitride
更新于2025-09-23 15:21:01
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Synergic effect of pore size engineering and an applied electric field on the controlled permeation of alkali metal atoms and ions across pristine and defect-containing h-BN sheets
摘要： The permeation and selectivity of alkali metal atoms and ions through normal and defected hexagonal boron nitride was studied in the presence and absence of water and an electric field. The defects include one (VB & VN), two (VBN) and three atom (VN2B) vacancies. The morphology and size of the pore (defect) in the h-BN sheet significantly affect the energy barriers. These results indicate that an h-BN sheet with appropriate pore size possesses good Li/Li+ selectivity. The permeation of lithium atoms through VN2B-h-BN is almost a barrierless process (1.75 kcal mol?1). Moreover, the VBN h-BN nanosheet selectively allows the passage of Li atoms at room temperature with the highest selectivity ratio of 1.58 × 1013. The presence of water molecules increases the barrier of alkali metal atom permeation. The effect of water molecules is more pronounced for alkali metal atom permeation through a defected h-BN nanosheet as compared to alkali metal ions. An applied electric field perpendicular to the h-BN sheet further decreases the permeation barriers. For example, the energy barrier is reduced to 31 kcal mol?1 (from 34 kcal mol?1) in the presence of an electric field for the permeation of lithium through H2O–VB h-BN–H2O. These studies can be extended to investigate the separation capability of porous hexagonal boron nitride nanosheets for other metal atoms and ions.
关键词： electric field,permeation,water molecules,alkali metal atoms,hexagonal boron nitride,defects,ions,selectivity
更新于2025-09-23 15:21:01
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Galliuma??Borona??Phosphide ($$\hbox {GaBP}_{2}$$): a new IIIa??V semiconductor for photovoltaics
摘要： Using machine learning (ML) approach, we unearthed a new III–V semiconducting material having an optimal bandgap for high-efficient photovoltaics with the chemical composition of Gallium–Boron–Phosphide (GaBP2, space group: Pna21). ML predictions are further validated by state-of-the-art ab initio density functional theory simulations. The stoichiometric Heyd–Scuseria–Ernzerhof bandgap of GaBP2 is noted to be 1.65 eV, a close ideal value (1.4–1.5 eV) to reach the theoretical Queisser–Shockley limit. The calculated electron mobility is similar to that of silicon. Unlike perovskites, the newly discovered material is thermally, dynamically and mechanically stable. Above all the chemical composition of GaBP2 is non-toxic and relatively earth abundant, making it a new generation of PV material. Using ML, we showed that with a minimal set of features, the bandgap of III–III–V and II–IV–V semiconductor can be predicted up to an RMSE of less than 0.4 eV. We have presented a set of scaling laws, which can be used to estimate the bandgap of new III–III–V and II–IV–V semiconductor, with three different crystal phases, within an RMSE of 0.4 eV.
关键词： Gallium–Boron–Phosphide,photovoltaics,GaBP2,III–V semiconductor,density functional theory,machine learning
更新于2025-09-23 15:21:01
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Influence of boron doping amount on properties of ZnO:B films grown by LPCVD technique and its correlation to a-Si:H/??c-Si:H tandem solar cells
摘要： Boron-doped ZnO:B (BZO) films with various doping levels have been prepared on large-area substrates by low pressured chemical vapor deposition technique. The influence of doping amount on electrical and optical properties of BZO films has been investigated. It is found that ZnO phase synthesis is hardly affected when the doping gas flow varies from 25 to 100 sccm, but the preferential orientation of grain growth is influenced progressively. It is interesting that there should be a threshold value of doping gas flow of 75 sccm that will cause an abrupt reduction in grain size of BZO and therefore dramatically weakens the light-scattering capacity of the film. It is also noted that the boron atoms doped in BZO films are partly electrically active, and moreover, the heavier doping level, the more inactive B atoms, which not only reduces carrier mobility, but also boosts a stronger light absorption due to enhanced impurity scattering. When the doping gas flow is 75 sccm, the BZO film can achieve a proper comprehensive property with a Rsq of 15.2 Ω/□, an average haze of 21.3% and an average TT of 80.2%. Using this film as the front electrode of a-Si:H/μc-Si:H solar cell, the optimum performance of the solar cell with a Jsc of 12.68 mA/cm2, a Voc of 1.385 mV, and an initial efficiency (η) of 11.83% was obtained.
关键词： a-Si:H/μc-Si:H tandem solar cells,Boron-doped ZnO:B films,doping amount,LPCVD technique,electrical and optical properties
更新于2025-09-23 15:21:01
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Multi-cycle Growth of Boron Doped ZnO Films as Photoanode for Dye-Sensitized Solar Cell (DSSC)
摘要： The work is concerned with the fabrication of dye sensitized solar cell (DSSC) utilizing multi-layer boron doped ZnO nanorods films. The B-doped ZnO films were prepared on FTO glass substrate via seed mediated hydrothermal method. Multi-layer B-doped ZnO nanorods were obtained by immersing the sample into a growth solution and repeated the growth process at 90 oC for 30 minutes. The structure of the B-doped ZnO film has been found to exhibit the hexagonal wurtzite structure. The length and diameter of the nanorods increase with the number of the growth cycle. The performance of the DSSC fabricated using the multi-layer B-doped ZnO nanorod was found to be significantly higher than that of the DSSC based on the single layer ZnO nanorod arrays. The best photovoltaic parameters with the JSC of 3.5 mA cm-2, FF of 0.38 and η of 0.67%, respectively was obtained for the device utilizing the layer with 3 cycles since it possesses the lowest photoluminescence in visible region and lowest Rct.
关键词： nanorod,boron,dye-sensitized solar cell,ZnO,hydrothermal
更新于2025-09-23 15:21:01
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Influence of pore size of Ti substrate on structural and capacitive properties of Ti/boron doped diamond electrode
摘要： This work is aimed at understanding the influence of pore size of titanium (Ti) substrate on the capacitive properties of boron doped diamond (BDD) electrode. BDD films were deposited on Ti substrates with five different pore sizes - 2.5, 5.0, 20.0, 30.0, 50.0 mm - using hot filament chemical vapor deposition (HFCVD). The pore size of substrate was found to cause significant variations in surface structure and capacitive properties of the Ti/BDD electrodes. The optimum pore size that resulted in best surface structure and capacitive properties was found to be 30.0 mm. The Ti30.0/BDD electrode was found to possess higher sp2-C bonds content, sp3-C bond with doped boron atom, more closely interlaced grains and bigger specific surface area than other electrodes. The maximum capacitance obtained for Ti30.0/BDD electrode was 53.3 mF cm-2, with minimum impedance value Rct of 4.8 U. The minimum capacitance of 1.07 mF cm-2 was obtained for the Ti50/BDD electrode, and the maximum impedance value Rct of 290 U was obtained by the Ti20.0/BDD electrode. Furthermore, the Ti30/BDD electrode possessed a favorable electrochemical stability of capacitance retention of 89.3% after 2070 cycles. A mechanism by which pore size affects the capacitance properties of the Ti/BDD electrode is proposed and discussed in this paper.
关键词： Capacitive property,Porous titanium substrate,Boron doped diamond,Surface structure
更新于2025-09-23 15:21:01
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Synthesis and Photovoltaic Properties of Boron ?2a??Ketoiminate Dyes Forming A Linear Donora????a??Acceptor Structure
摘要： Organoboron complexes are of interest as chromophores for dye sensitizers owing to their light-harvesting and carrier-transporting properties. In this study, compounds containing boron β-ketoiminate (BKI) as a chromophore were synthesized and used as dye sensitizers in dye-sensitized solar cells. The new dyes were orange or red crystals and showed maximum absorptions in the 410–450 nm wavelength region on titanium dioxide substrates. These electrodes exhibited maximum efficiencies of over 80% in incident photon-to-current conversion efficiency spectra, suggesting that the continuous process of light absorption–excitation–electron injection was effectively performed. Open-circuit photovoltages were relatively high owing to the large dipole moments of the BKI dyes with a linear molecular structure. Thus, a maximum power conversion efficiency of 5.3% was successfully observed. Comparison of BKI dyes with boron β-diketonate dyes revealed certain differences in solution stability, spectral properties, and photovoltaic characteristics.
关键词： chelates,boron,donor-acceptor systems,dyes/pigments,energy conversion
更新于2025-09-23 15:21:01
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Dependence of h-BN film thickness as grown on nickel single crystal substrates of different orientation
摘要： Chemical vapor deposition of 2D materials has been an active area of research in recent years because it is a scalable process for obtaining thin films that can be used to fabricate devices. The growth mechanism for hexagonal boron nitride (h-BN) on metal catalyst substrates has been described to be either surface energy driven or diffusion driven. In this work, h-BN is grown in a CVD system on Ni single crystal substrates as a function of Ni crystallographic orientation to clarify the competing forces acting on the growth mechanism. We observed that the thickness of the h-BN film depends on the Ni substrate orientation, with the growth rate increasing from the (100) surface to the (111) surface, and the highest on the (110) surface. We associate the observed results with surface reactivity and diffusivity differences for different Ni orientations. Boron and nitrogen diffuse and precipitate from the Ni bulk to form thin multilayer h-BN. Our results serve to clarify the h-BN CVD growth mechanism which has been previously ascribed to a surface energy-driven growth mechanism.
关键词： surface diffusion,electron backscatter diffraction,growth mechanism,hexagonal boron nitride
更新于2025-09-23 15:21:01