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Photoluminescence features of new Eu <sup>3+</sup> -doped Gd <sub/>4</sub> Mo <sub/>7</sub> O <sub/>27</sub> phosphors synthesized using glass crystallization technique
摘要： New Eu3+-doped Gd4Mo7O27 crystals (the molar ratio of Gd2O3/MoO3 = 1/3.5) with a monoclinic structure C2/c (an inversion symmetry) were synthesized through the crystallization of xEu2O3-(18.89-x)Gd2O3-66.11MoO3-15B2O3-1Al2O3 glasses (x = 0.0472 and 1.889) and photoluminescence (PL) emissions of Eu3+ ions were measured for the first time. The crystallized glass with no Eu2O3 addition (x = 0) showed a blue color under the irradiation of ultra-violet light with a wavelength of λ = 254 nm, the emitting color of the crystallized glass with x = 0.0472 was pink, and that of the crystallized glass with x = 1.889 was orange. The charge transfer (CT) of O2-→Mo6+ providing broad peaks centered at around 325 nm was observed in the crystallized glasses. The peak intensity at 591 nm for the 5D0→7F1 transition of Eu3+ ions in the crystallized glasses with x = 0.0472 and 1.889 was very close to that at 615 nm for the 5D0→7F2 transition for the excitation of λex = 394.5 nm. We propose potential of Gd4Mo7O27 as a new host crystal for rare-earth-doped phosphors.
关键词： Eu3+-doping,Glass crystallization,Photoluminescence,Phosphor,Gd4Mo7O27
更新于2025-09-04 15:30:14
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Investigation of Improvement of Electronic Properties and Ductility of RuAl2 Semiconducting Material by Boron Doping Using First-Principles Calculations
摘要： The occupation mechanism and influence of B doping on the electronic and mechanical properties of RuAl2 semiconducting compound have been investigated using first-principles calculations. Four possible B doping sites are considered. The results show that B-doped RuAl2 is thermodynamically stable. In particular, B element prefers to occupy B(4) site in comparison with other sites. Importantly, B doping improves the electronic properties of RuAl2 by shifting the Al 3p and Ru 4d states from the Fermi level (EF) to the valence band. Although B doping weakens the resistance to volume and shear deformation as well as the elastic stiffness of RuAl2, it improves the ductility due to the formation of Ru-B and Al-B bonds. Therefore, it can be concluded that B is a favorable doping element to improve the electronic properties and ductility of RuAl2 semiconducting compound.
关键词： Boron doping,RuAl2,First-principles calculations,Ductility,Electronic properties
更新于2025-09-04 15:30:14
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Tuning of Graphene Work Function by Alkyl Chain Length in Amine-Based Compounds
摘要： In this study, the effect of alkyl chain length in amine-based compounds on the work function of graphene was investigated. The graphene was synthesized by the chemical vapor deposition method. The graphene layers were functionalized by amine-based groups using a simple spin-coating method. The amine-based compounds were composed of phenyl amine and methyl-, ethyl-, propyl-, n/t-butyl-, and octyl-phenyl amine groups. Materials were confirmed by X-ray photoelectron spectroscopy to show the C and N bonding. The work function of the doped graphene layers decreased because of the effect of the doping agents. Among the doped graphene samples, t-butyl-phenyl amine functionalized graphene achieved the lowest work function of 3.89 eV (compared with 4.43 eV for pristine graphene). Further, the sheet resistance of n-doped graphene increased, confirming the high concentration of n-doping agents on the graphene layers. These results suggest the best alkyl chain is the t-butyl group to reduce the work function of graphene, and promise the use of these materials as cathodes for opto-electronic applications.
关键词： n-doping,Graphene,Work function,Amine-based compounds
更新于2025-09-04 15:30:14
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Adsorption properties of O2 on the unequal amounts of binary co-doped graphene by B/N and P/N: A density functional theory study
摘要： Graphene acts as an advanced substrate material, and it has been used as an electrode in fuel cells because it can efficiently adsorb oxygen molecules. In this study, density functional theory (DFT) calculation has been performed to exactly simulate the adsorption and dissociation of oxygen molecules on the XY3-co-doped graphene. The results show that the positively charged P and B atoms act as active sites for oxygen adsorption on the surface of graphene. In addition, PN3-G and NP3-G exhibit higher catalytic activity than the other samples because of the facile transfer of electrons from the highest occupied molecular orbital (HOMO) of O2 to the orbital above the Fermi level in the samples. More interestingly, excessive adsorption leads to the direct dissociation of oxygen molecules and making further dissociation difficult. In conclusion, the adsorption of oxygen molecules at the hollow sites on the PN3-G and NP3-G occurs via the formation of a triangular ring or trans-formation into O2? is proposed as the optimal strategy because these routes are thermodynamically favorable and the associated energy barrier is low. Furthermore, after dissociation, it was found that the oxygen atoms preferably approach the P atom. This work may be useful as a reference for future experimental studies to develop effective metal-free catalysts for fuel-cell cathodes.
关键词： Density functional theory (DFT),XY3 co-doping,Graphene,Electron transfer,Adsorption
更新于2025-09-04 15:30:14
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Molecular Doping of Electrochemically Prepared Triazine-Based Carbon Nitride by 2,4,6-Triaminopyrimidine for Improved Photocatalytic Properties
摘要： Copolymerization of melamine with 2,4,6-triaminopyrimidine (TAP) in an electrochemically induced polymerization process leads to the formation of molecular doped poly(triazine imide) (PTI). The polymerization is based on the electrolysis of water and evolving radicals during this process. The incorporation of TAP is shown by techniques such as elemental analysis, Fourier transform infrared and NMR spectroscopies, and powder X-ray diffraction, and it is shown that the carbon content can be tuned by the variation of the molar ratio of the two precursors. This incorporation of TAP directly influences the electronic structure of PTI and as a result, a red shift can be observed in UV?vis spectroscopy. The smaller band gap and the increased absorption in the visible range lead to improved photocatalytic properties. In dye degradation experiments, it was possible to observe an increase of the rate of the degradation of methylene blue by a factor of 4 in comparison to undoped PTI or 7 if compared to melon.
关键词： 2,4,6-triaminopyrimidine,photocatalysis,electrochemical synthesis,molecular doping,poly(triazine imide)
更新于2025-09-04 15:30:14
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XPS investigation of F-doped MnO <sub/>2</sub> nanosystems fabricated by plasma assisted-CVD
摘要： Supported Mn(IV) oxide nanomaterials were prepared by plasma assisted-chemical vapor deposition from Ar/O2 plasmas starting from a fluorinated Mn(II) β-diketonate diamine adduct. Under the adopted conditions, the target compound served as a single-source molecular precursor for the obtainment of MnO2 nanosystems uniformly doped with fluorine. The overall F content in the target materials, composed of phase-pure β-MnO2, could be tailored as a function of the deposition temperature from 100 to 400 °C, a result of particular importance in view of photocatalytic and gas sensing applications. In the present study, attention is specifically devoted to the investigation of a representative specimen by means of x-ray photoelectron spectroscopy. Besides the wide scan spectrum, a detailed analysis of C 1s, O 1s, Mn 2p, Mn 3s, and F 1s photoelectron peaks is presented and discussed. The analyses reveal the formation of MnO2 free from other manganese oxides, with fluorine present in different chemical states, i.e., lattice F plus traces of precursor residuals at the system surface.
关键词： fluorine doping,x-ray photoelectron spectroscopy,PA-CVD,manganese oxide
更新于2025-09-04 15:30:14
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Effect of doping Fe/Cu/Ti on WO <sub/>3</sub> on furfural degradation
摘要： This research improved tungsten oxide catalysts to increase efficiency in photocatalytic degradation of furfural under visible light. The aim of this research was to compare the efficiency of modified tungsten oxide with undoped and commercial tungsten oxide. Tungsten oxide nanoparticles were doped with 3 single metals, which were Fe/Cu/Ti at 1%wt, 2%wt, and 3%wt, synthesized by flame spray pyrolysis technique (FSP) and then characterization by X-Ray Diffraction (XRD), N2 adsorption/desorption (BET surface area analysis), UV-Vis Spectroscopy (UV-Vis). Photocatalytic degradation experiments using doped WO3 were carried out with 5 ppm initial concentration of furfural solution using 0.6 M catalyst concentration under visible light. From the results, FSP-synthesized WO3 has better efficiency in furfural degradation than the commercial WO3. All catalysts have mesoporous structure because an average pore size is in the range of 6-10 nm. Among all synthesized and doped WO3, it can be concluded that 3%wt Fe-doped tungsten oxide provides the highest acceleration rate in photocatalytic degradation of furfural.
关键词： furfural,photocatalytic degradation,flame spray pyrolysis,tungsten oxide,doping
更新于2025-09-04 15:30:14
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Effective doublon and hole temperatures in the photo-doped dynamic Hubbard model
摘要： Hirsch’s dynamic Hubbard model describes the effect of orbital expansion with occupancy by coupling the doublon operator to an auxiliary boson. In the Mott insulating phase, empty sites (holes) and doubly occupied orbitals (doublons) become charge carriers on top of the half-filled background. We use the nonequilibrium dynamical mean field method to study the properties of photo-doped doublons and holes in this model in the strongly correlated regime. In particular, we discuss how photodoping leads to doublon and hole populations with different effective temperatures, and we analyze the relaxation behavior as a function of the boson coupling and boson energy. In the polaronic regime, the nontrivial energy exchange between doublons, holes, and bosons can result in a negative temperature distribution for the holes.
关键词： effective temperatures,doublons,holes,photo-doping,dynamic Hubbard model,nonequilibrium dynamical mean field theory
更新于2025-09-04 15:30:14
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Magnetic Properties of Pure and Doped Gallium Nitride Nanocrystals
摘要： In the present paper, Ga1?xCoxN, Ga1?xNixN and Ga1?xTbxN (0 ≤ x ≤ 0.1) nanocrystals have been synthesized by a facile solvothermal method. Crystallographic characterization of synthesized materials has been done using powder X-ray diffraction technique. Recorded diffraction patterns reveal the formation of wurtzite (hexagonal) structured GaN nanocrystals. Electron microscopic studies have been carried for the detailed topographical and morphological analyses of synthesized nanomaterials. Recorded electron micrographs indicate the formation of nearly mono-disperse nanoparticles, having average size ～4 nm. Magnetic measurements of doped nanocrystals revealed ferromagnetic behavior at room temperature however pure GaN is diamagnetic at room temperature.
关键词： Crystallography,Doping,Gallium Nitride Nanocrystals,Magnetic Properties
更新于2025-09-04 15:30:14
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Low-temperature homoepitaxial growth of two-dimensional antimony superlattices in silicon
摘要： The authors present a low-temperature process for the homoepitaxial growth of antimony superlattices in silicon. The all low-temperature superlattice doping process is compatible as a postfabrication step for device passivation. The authors have used low-temperature molecular beam epitaxy to embed atomically thin (2D), highly concentrated layers of dopant atoms within nanometers of the surface. This process allows for dopant densities on the order of 1013–1014 cm?2 (1020–1021 cm?3); higher than can be achieved with three-dimensional doping techniques. This effort builds on prior work with n-type delta doping; the authors have optimized the growth processes to achieve delta layers with sharp dopant profiles. By transitioning from a standard effusion cell to a valved cracker cell for antimony evaporation, the authors have achieved carrier densities approaching 1021 cm?3 with peak distribution at ～10 ? FWHM for single delta layers. Even at the highest dopant concentrations studied, no deterioration in carrier mobility is observed, suggesting the upper limit for dopant incorporation and activation has not yet been met. The authors will discuss the details related to growth optimization and show results from in situ monitoring by electron diffraction. They will also report on elemental and electrical characterization of the films.
关键词： silicon,molecular beam epitaxy,surface passivation,homoepitaxial growth,delta doping,low-temperature,antimony superlattices
更新于2025-09-04 15:30:14