- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Panorama of boron nitride nanostructures via lamp ablation
摘要： A diverse range of remarkable boron nitride (BN) nanostructures subsuming nano-horns, nano-rods, nano-platelets, and clusters of hollow nanospheres (nano-onions, arguably of greatest applied and fundamental interest) have been produced exclusively from crystalline BN precursor powder via lamp ablation. The procedure is safe, devoid of toxic reagents, simple, rapid and scalable—generating some genres of nanoparticles that had previously proved elusive. Product structure and composition were unambiguously assessed by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy.
关键词： lamp ablation,non-toxic,boron nitride,nanostructures,nano-onions
更新于2025-09-23 15:23:52
-
Synthesis, characterization and optical property study of BCNO and BCN related nanopowder
摘要： Boron carbon oxynitride (BCNO) and BCN nanocompounds are successfully synthesized by a solid state sintering method using boric acid, urea and dextrose as the sources of B, N and C respectively under inert atmosphere. X-ray diffraction (XRD) and infrared spectroscopy (FTIR) analysis show that nanomaterials are synthesized at the high temperature range of 1350 oC. Sufficient amount of oxygen impurities are present in the sample, which is manifested in their photoluminescence spectra. Increase in temperature to 1350 oC under N2 atmosphere causes elimination of significant amount of O-species from the system. The presence of ample amount of carbon in the system results in the formation of high amount of polycrystalline h-BCN with minor amount of h-BN. However, some residual oxygen in the sample, which is detected in the FTIR study, leads to the formation of BCNO compound. These semiconductor BCNO compounds act as the potential luminescence centers for the blue-green emissions of the particles. Thus, these materials may find potential application as a phosphor material in various opto-electronic devices.
关键词： optical properties,carbon,boron carbon nitride,Boron carbon oxynitride,impurities
更新于2025-09-23 15:22:29
-
Structural, energetic and spectroscopic studies of new luminescent complexes based on 2-(2′-hydroxyphenyl)imidazo[1,2- <i>a</i> ]pyridines and 1,2-phenylenediboronic acid
摘要： Three new blue-luminescent complexes of selected imidazo[1,2-a]pyridine derivatives and 1,2-phenylenediboronic acid have been synthesized and structurally characterized using single-crystal X-ray diffraction. Additionally, the crystal structures of two of the (N,O)-donor compounds have been evaluated for the first time. The crystal packing and molecular motifs observed in the studied crystals have been thoroughly analysed, including computational studies, and are also discussed within the context of analogous systems reported in the literature. It appears that the new compounds form different crystal networks with regard to the asymmetric unit content and packing, although some similarities can be found. In all cases a typical centrosymmetric dimer bound via boronic acid groups is formed, characterized by an interaction energy of about -80 kJ mol-1, while the 2-(2'-hydroxyphenyl)imidazo[1,2-a]pyridine complex and its methoxy derivative form solvate structures, somewhat resembling the previously studied 8-oxyquinolinate analogues. As far as the spectroscopic properties are concerned, the lowest energy excitation observed in the studied complexes is based on the highest occupied molecular orbital–lowest unoccupied molecular orbital transition, and both these molecular orbitals are centred predominantly on the (N,O)-donor species according to the results of time-dependent density functional theory. Thus, the charge transfer observed for the 8-oxyquinolinate equivalents does not occur in these cases. Consequently, the spectroscopic behaviour of the series is very much comparable with that of the parent imidazo[1,2-a]pyridine derivatives, if the excited-state intramolecular proton-transfer process does not take place, as shown by the absorption and emission spectra collected in toluene and acetone solutions. Complexation causes a reduction in the Stokes shift compared with the respective (N,O)-donor molecules.
关键词： periodic calculations,TDDFT,UV–Vis spectroscopy,X-ray diffraction,time-dependent density functional theory,spectroscopic properties,luminescent boron complexes,transferred aspherical atom model (TAAM) refinement
更新于2025-09-23 15:22:29
-
Breakdown enhancement of diamond Schottky barrier diodes using boron implanted edge terminations
摘要： Boron implanted edge terminations have been demonstrated to enhance the breakdown voltages and stabilities of diamond Schottky barrier diodes (SBDs). The edge terminations were achieved by boron implant to form nonconductive amorphous regions under the edges of the Schottky contacts. Direct current measurements show the implanted regions did not contribute to the forward currents and high current densities of about 4000 A/cm2 were obtained at -5 V. By using boron implanted edge terminations, although an increase in leakage currents was observed, the average breakdown voltage of the devices was significantly improved from 79 V to 125 V, which is increased by more than 50%. In addition, the breakdown voltages of the devices without edge terminations degraded quickly after each repeating measurement, whereas the devices with edge terminations became much more stable and no obvious drop in breakdown voltages was observed.
关键词： Boron implant,Schottky diode,Diamond,Edge termination
更新于2025-09-23 15:22:29
-
Optical and Microstructural Investigation of Heavy B-Doping Effects in Sublimation-Grown 3C-SiC
摘要： In this work, a complementary microstructural and optical approach is used to define processing conditions favorable for the formation of deep boron-related acceptor centers that may provide a pathway for achieving an intermediate band behavior in highly B-doped 3C-SiC. The crystallinity, boron solubility and precipitation mechanisms in sublimation-grown 3C-SiC crystals implanted to 1-3 at.% B concentrations were investigated by STEM. The revealed defect formation and boron precipitation trends upon thermal treatment in the range 1100-2000oC have been cross-correlated with the optical characterization results provided by imaging PL spectroscopy. We discuss optical activity of the implanted B ions in terms of both shallow acceptors and deep D-centers, a complex formed by a boron atom and a carbon vacancy, and associate the observed spectral developments upon annealing with the strong temperature dependence of the D-center formation efficiency, which is further enhanced by the presence of implantation-induced defects.
关键词： photoluminescence,defects,3C-SiC,STEM,implantation,boron doping
更新于2025-09-23 15:22:29
-
Novel Porous Boron Nitride Nanosheet with Carbon Doping: Potential Metal-Free Photocatalyst for Visible-Light-Driven Overall Water Splitting
摘要： The band gap of hexagonal boron nitride (h-BN) is far too wide for efficiently utilizing visible light, limiting its application in photocatalysis. The present study employs first principles calculations to demonstrate that the band gap energies of porous h-BN (p-BN) can be tuned by carbon doping to levels appropriate for the absorption of visible-light, and that the conduction band and valence band match well with the potentials of both hydrogen and oxygen evolution reactions. Importantly, a strategy of carbon doping to improve the energy level of valence band maximum is also proposed. Moreover, the carbon-doped p-BN exhibits good separation between photogenerated electrons/holes and structural stability at high temperatures. The DFT results help the design of high-performance two-dimensional photocatalysts that avoid the use of metals.
关键词： metal-free catalysts,photocatalyst,porous boron nitride nanosheets,overall water splitting,band structure engineering
更新于2025-09-23 15:22:29
-
Enhanced electron field emission from nanocrystalline orthorhombic boron nitride films
摘要： Nanocrystalline orthorhombic boron nitride (oBN) thin films with an island-in-honeycomb morphology were prepared on graphite substrate by radio frequency (r.f.) magnetron sputtering. The Field emission (FE) measurement results indicated that the FE properties are significantly enhanced in oBN films compared to high quality cBN films, the turn-on electric field of oBN films is decreased from 17.0 V/μm to 6 V/μm, and the highest emission current density is increased from 2.8 × 10?? to 3 × 10?? A/cm2. The enhanced FE properties of the oBN films can be attributed to significant reduction in effective potential barrier caused by both protruded island-in-honeycomb morphology and honeycomb-like interconnected internal structure.
关键词： Semiconductors,Thin films,Electron field emission,Boron nitride,Physical vapour deposition
更新于2025-09-23 15:22:29
-
Doping-induced giant rectification and negative differential conductance (NDC) behaviors in zigzag graphene nano-ribbon junction
摘要： By p-type and n-type doping on the electrode edges of V-notched zigzag graphene nano-ribbons (ZGNRs), four V-notched ZGNR-based PN-junctions are designed theoretically. The electronic transport properties of the doped and un-doped V-notched ZGNRs are studied applying non-equilibrium Green’s function method combined with the density functional theory. The numerical results show that, the doped systems are less conductive than the un-doped system, because after doping the transition states become localized. To our surprise, the ZGNR-based PN-junctions do not show obvious rectification by purely doping the boron atoms and nitrogen atoms on the edges of two ZGNR electrodes respectively. However, after hydrogenated the doped boron atoms and nitrogen atoms, the ZGNR systems present giant rectifications with the maximum rectification ratios up to 106 ～ 107, which attributed to the vanishing of overlap between left-electrode sub-band and right-electrode sub-band in the negative bias regime after the doped boron and nitrogen atoms being hydrogenated. Due to the same reason, the hydrogenated doping systems also show large negative differential conductance behaviors.
关键词： Giant rectification,Negative differential conductance,Graphene nano-ribbon junction,Boron and nitrogen doping
更新于2025-09-23 15:22:29
-
Magnetic-field-dependent quantum emission in hexagonal boron nitride at room temperature
摘要： Optically addressable spins associated with defects in wide-bandgap semiconductors are versatile platforms for quantum information processing and nanoscale sensing, where spin-dependent inter-system crossing transitions facilitate optical spin initialization and readout. Recently, the van der Waals material hexagonal boron nitride (h-BN) has emerged as a robust host for quantum emitters, promising efficient photon extraction and atom-scale engineering, but observations of spin-related effects have remained thus far elusive. Here, we report room-temperature observations of strongly anisotropic photoluminescence patterns as a function of applied magnetic field for select quantum emitters in h-BN. Field-dependent variations in the steady-state photoluminescence and photon emission statistics are consistent with a spin-dependent inter-system crossing between triplet and singlet manifolds, indicating that optically-addressable spin defects are present in h-BN.
关键词： photoluminescence,room temperature,quantum emitters,magnetic field,hexagonal boron nitride,spin defects
更新于2025-09-23 15:22:29
-
Semiconducting B<sub>13</sub>C<sub>2</sub> system: Structure search and DFT-based analysis
摘要： DFT calculation on Boron Carbide in B13C2 stoichiometry using a 15-atom unit cell necessarily results in metallic ground state regardless of the crystal structure. This is because such a unit cell consists of odd number of electrons, and hence complete filling of the top most band(s) of nonzero occupancy is impossible. This is in contrast to the observed semiconducting nature. If the crystal structure of B13C2 is made of a 30-atom unit cell which cannot be reduced to a 15 atom cell, there is a possibility of obtaining either a metallic or a semiconducting state as such a cell consists of an even number of electrons. In this work the evolutionary algorithm based structure search using 30-atom unit cells has yielded a previously unreported semiconducting system of B13C2 with unique bonding pattern. The mechanical and dynamical stability of the system have been properly established through the computation of elastic constants and phonon spectra. Its bond lengths, elastic moduli, hardness and infrared spectrum are in good agreement with experimental data.
关键词： Boron Carbide,elastic constants,evolutionary algorithm,DFT,phonon spectra,semiconducting,structure search,B13C2
更新于2025-09-23 15:22:29