Ternary eutectic growth of Ag-Cu-Sb alloy within ultrasonic field

The liquid to solid transformation of ternary Ag42.4Cu21.6Sb36 eutectic alloy was accomplished in an ultrasonic field with a frequency of 35 kHz, and the growth mechanism of this ternary eutectic was examined. Theoretical calculations predict that the sound intensity in the liquid phase at the solidification interface increases gradually as the interface moves up from the sample bottom to its top. The growth mode of (ε θ Sb) ternary eutectic exhibits a transition of "divorced eutectic- mixture of anomalous and regular structures-regular eutectic" along the sample axis due to the inhomogeneity of sound field distribution. In the top zone with the highest sound intensity, the cavitation effect promotes the three eutectic phases to nucleate independently, while the acoustic streaming efficiently suppresses the coupled growth of eutectic phases. In the meantime, the ultrasonic field accelerates the solute transportation at the solid-liquid interface, which reduces the solute solubility of eutectic phases.     

Electro-hydrodynamic fabrication of ZnO-based dye sensitized solar cells

The electro-hydrodynamic (EHD) technique has been successfully applied for manufacturing ZnO photoanode in dye sensitized solar cells (DSSCs). Porous structure of ZnO film after calcinations was beneficial to the absorption of dye and infiltration of electrolyte. By using ionic liquid as an electrolyte, a high short-circuit photocurrent density of 12.1 mA/cm² was attained and the overall photo-to-electric energy conversion efficiency (η) was 3.4% under an AM-1.5 illumination at 100 mW/cm². At the same time, the influence factors on the solar cell performance, such as the concentrations of polyvinyl alcohol (PVA) during EHD process and light intensity were discussed. PACS 81.07.Bc; 84.60.Jt; 81.15.Rs     

Efficient generation of a photon pair in a bulk periodically poled potassium titanyl phosphate

In this report, we demonstrate the efficient generation of collinearly propagating photon pairs in a bulk periodically poled potassium titanyl phosphate pumped by a cw laser. The detected coincidence counts are more than 7400/s with 3.58 mW pump power in a Hanbury-Brown-Twiss-type experiment. The estimated photon pair production rate is about 0.73 MHz/mW. This is very promising for some applications, such as quantum key distribution, proof of the Bell-inequality, preparation of single photon states in broadband wave packets, Franson-type interference and so on.     

Study of photoconductivity and photoluminescence of organic/porous silicon complexes

In this paper, time-varying photoconductivity (PC) and the photoluminescence (PL) of different complexes were studied. Due to thick polymer layer hindering light penetrating into porous silicon (PS) layer, intrinsic PS luminescence in polymer/PS system disappeared. The physical origin of PL may be related to the recombination mechanisms involving surface defect states such as silicon oxide, siloxene. Due to carrier transfer controlled by different energy barrier, different devices prepared from different doped Si wafer showed opposite current-voltage characteristic.     

Facile Assembly of Dispersed ZrMCM‐41 Nanoparticles Promoted in‐situ by Zirconium Salt

Mesoporous ZrMCM‐41 nanoparticles were synthesized by a usual way where tetraethyl‐orthosilicate (TEOS) and zirconium nitrate were used as the inorganic precursors. The obtained nanoscale ZrMCM‐41 was characterized by X‐ray diffraction, N₂ physis‐sorption, scanning electron microscopy and transmission electron microscopy. Characterization results revealed that zirconium salt added in the synthesis had a crucial effect on the assembly of nanoscale ZrMCM‐41 with relatively uniform particle size, which was rarely observed in reported studies for ZrMCM‐41 synthesized using the similar method. Meanwhile, the possible mechanism behind the synthesis was discussed based on the character of hydrolysis and condensation of TEOS and the mild acidic environment induced by the hydrolysable zirconium salt under aqueous conditions. Thus obtained nanoscale ZrMCM‐41 with developed pore structures may be advantageous to general applications in catalysis or adsorption host‐guest chemistry in terms of efficient mass transport of guest molecules.     

Polyvinylidene fluoride/polystyrene hybrid fibers with high ionic conductivity and enhanced mechanical strength as lithium-ion battery separators

Journal of Solid State Electrochemistry - Ionic conductivity is an important separator parameter influencing the cycle life and rate capability of lithium-ion batteries (LIBs). To improve the ionic...     

Acid‐treated g‐C3N4‐Cu2O composite catalyst with enhanced photocatalytic activity under visible‐light irradiation

Acid‐treated g‐C₃N₄‐Cu₂O was prepared by hydrothermal reduction followed by high temperature calcination and acid exfoliation. The structures and properties of as‐synthesized samples were characterized using a range of techniques, such as X‐ray photoelectron spectroscopy, scanning electron microscopy, Photoluminescence Spectroscopy and the Brunauer–Emmett–Teller (BET) theory. The photocatalytic activity was evaluated by measuring the photodegradation of methyl orange under visible‐light irradiation. Based on the results of TEM, XPS, EPR and other techniques, it was verified that a heterojunction was formed. The acid treatment process can increase the specific surface area to form abundant heterojunction interfaces as channels for photo‐generated carrier separation, thereby enhancing its light utilization and quantum efficiency. Results indicate that acid‐treated g‐C₃N₄‐Cu₂O possesses a large specific surface area, which provides plentiful activated sites for heterojunctions to form; in addition, it showed a high visible light effect and the minimum charge‐transfer resistance. Furthermore, the g‐C₃N₄‐Cu₂O material exhibits high levels of effectiveness and stability. Electron paramagnetic resonance and a series of radical trapping experiments demonstrate that the holes and ?O₂^? could be the main active species in methyl orange photodegradation. This work could provide new insights into the fabrication of composite materials as high‐performance photocatalysts, and facilitate their application in addressing environmental protection issues.     

Nitrogen doping effects on the structure of graphene

Graphene and nitrogen doped graphene have been prepared by modified Hummers’ method and the following ammonia heat-treatment process, respectively. The effects of N-doping on the structure of graphene have been systematically investigated by various characterization techniques. SEM, TEM, BET, Raman and XRD analysis were used to distinguish the difference of the microstructures; and FT-IR, XPS, especially XANES were performed to elucidate the bonding information such as C-N. The effect of nitrogen doping on the structure of graphene has been obtained. More defects are present on nitrogen doped graphene as elucidated by BET, XRD, Raman, and XANES characterizations. XANES analysis also indicates that the N-doping decreases the surface oxygen-containing groups.     

On the conformal mappings in the unit disk fixing arbitrarily many boundary points

In this paper, we give a method of constructing conformal mappings defined in the unit disk which can fix arbitrarily many points on the unit circle.