Simple synthesis and characterization of SrSnO3 nanoparticles with enhanced photocatalytic activity

SrSnO₃ nanoparticles with peanut-like morphologies were synthesized by a simple wet chemical reaction. These peanut-shaped SrSnO₃ were formed by the fusion of two or more nanoparticles with an average size of 45 nm. The resulting powders were characterized in detail using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Moreover, the photocatalytic activity for hydrogen evolution from pure water was investigated under UV light irradiation. The peanut-shaped nanoparticles exhibited a much higher photocatalytic activity compared to SrSnO₃ powder synthesized by a solid-state reaction. This was attributed to their higher structural order, caused by the formation of a carbonate-free pure phase, as well as their higher surface area resulting from the decrease in the particle size.     

Impact of two circular plates one of which is floating on a thin layer of liquid

The paper deals with the axisymmetric unsteady problem of the collision of two circular plates, one of which is located initially on the surface of a shallow liquid layer and another is falling down on it. The presence of air between the colliding plates is taken into account. Both the air and the liquid are assumed ideal and incompressible and their flows potential. The flows in the liquid layer and between the plates are assumed one-dimensional with corrections for three-dimensional effects close to the plate edges. The present study is focused on the stage of strong interaction between the plates, during which the floating plate is accelerated and the hydrodynamic pressure in the liquid layer takes its maximum value. A simplified model of this interaction is suggested. Velocities of the plates and the hydrodynamic pressure on the bottom of the liquid layer are analytically estimated and compared with experimental results. The model provides the maximum of the hydrodynamic pressure, which can be used at the design stage. It is shown that the air flow between the moving plates is of major importance to explain the low amplitude of the measured hydrodynamic pressures.     

Relationship between exciton recombination zone and applied voltage in organic light-emitting diodes

In this paper, the relationship between exciton recombination zone and applied voltage in organic light-emitting diodes (OLEDs) ITO/NPB (40 nm)/Alq₃(w nm)/rubrene(3 nm)/Alq₃(50−w)/Al, in which a 3 nm rubrene as sensing layer is inserted in Alq₃ layer at different depth, is studied. By comparing the electroluminescence (EL) spectra of device driven under different applied voltages, a conclusion can be drawn that the recombination zone shifts logarithmically with increasing applied voltages.     

Measurement of hydrogen permeation due to atomic flux using permeation probe in the spherical tokamak QUEST

Particle retention and recycling in plasma fusion devices are generally associated with the diffusion of atomic hydrogen into the materials. The resulted permeation of atomic hydrogen is known as plasma driven permeation (PDP). This permeation may also be significant, even in the walls, which are not directly exposed to the plasma. Under similar conditions, the permeation flux (Γ_perm) of hydrogen through a 30 μm thick Ni membrane heated at 412-575 K has been measured in the spherical tokamak QUEST. Γ_perm is being measured during the scans of different operating parameters like RF power (P_RF), chamber pressure (P_chamber), discharge widths (τ_dis) and vertical magnetic field (B_Z). Simultaneously edge plasma density and spectral intensities of atomic (Balmer) lines and molecular (Fulcher) bands have been compared with the permeation measurements. A linear relationship has been established between the time integrated Γ_perm i.e. permeation fluence (Q_perm) and the time integrated H_α intensity i.e. H_α fluence (Q_α). Q_perm also shows a strong relationship with the edge plasma density and various spectral fluences. The obtained results are discussed for exploring the applicability of the permeation probes in measuring the atomic flux near the first walls.     

Effect of alloying chemistry on the lattice constant of austenitic Fe-Mn-Al-C alloys

In summary, the lattice constant of austenitic Fe-Mn-Al-C alloys as a function of composition has been determined. The addition of manganese, aluminum, or carbon increases the lattice constant of austenitic Fe-Mn-C alloys, but the addition of silicon decreases the lattice constant. The effect of aluminum and carbon on the increase in lattice constant are similar, while that of manganese is about one order of magnitude smaller.     

Consideration of basic equations,and their application,in the forming of metal powders and porous metals

Yield criteria and stress—incremental strain relations for compressible materials, such as metal powders and sintered porous metals, are described and experimental verification of these basic equations is then given. The application of slip-line field theory, upper-bound theory, the finite-element method and the visio-plasticity method based on the above equations is described and some results are presented.When powders are compacted, or sintered metals are plastically deformed, they undergo a change in density and also density variations occur within the product. Since the change in density and the density variation have a great effect upon the properties of the product, it is important to be able to evaluate them. Loads to cause densification or plastic deformation, and pressures exerted on the die-walls, are also important in tool design. Using the above theories or methods, it is possible to predict the working load, the pressures exerted on the die walls and the density variation within the product. Whereas these important factors have not been treated theoretically in the past, a rational basis can now be introduced into the forming of metal powders and sintered metals.     

Simulation of grain coarsening in two dimensions by cellular-automaton

This paper presents a computer simulation model, namely Cellular Automaton (CA), which aims at investigating the behaviour of normal grain coarsening in 2D that corresponds well to the described physical model. The CA model takes into account the following: the energy barrier of cellular transition depends on the energy of the grain boundary; the energy of boundaries depends on the misorientation of the grains and the energy of the cells follows the Maxwell–Boltzmann distribution. The model was tested on both simple geometrical configurations and on real structures. The effect of temperature, orientation difference, activation energy, and boundary energy for the kinetics of grain coarsening were analysed and discussed. The optimal orientation value, q_max, was greater than 64, and at smaller q_max values non-real structures develop. The rate and kinetics of coarsening depend on a q_max value up to 64, the energy barrier and the boundary energy. The rate of coarsening cannot be described by only one exponential function over a wide temperature range.     

Engineering Solid Electrolyte Interphase for Pseudocapacitive Anatase TiO2 Anodes in Sodium‐Ion Batteries

Anatase TiO₂ is considered as one of the promising anodes for sodium‐ion batteries because of its large sodium storage capacities with potentially low cost. However, the precise reaction mechanisms and the interplay between surface properties and electrochemical performance are still not elucidated. Using multimethod analyses, it is herein demonstrated that the TiO₂ electrode undergoes amorphization during the first sodiation and the amorphous phase exhibits pseudocapacitive sodium storage behaviors in subsequent cycles. It is also shown that the pseudocapacitive sodium storage performance is sensitive to the nature of solid electrolyte interphase (SEI) layers. For the first time, it is found that ether‐based electrolytes enable the formation of thin (≈2.5 nm) and robust SEI layers, in contrast to the thick (≈10 nm) and growing SEI from conventional carbonate‐based electrolytes. First principle calculations suggest that the higher lowest unoccupied molecular orbital energies of ether solvents/ion complexes are responsible for the difference. TiO₂ electrodes in ether‐based electrolyte present an impressive capacity of 192 mAh g^?1 at 0.1 A g^?1 after 500 cycles, much higher than that in carbonate‐based electrolyte. This work offers the clarified picture of electrochemical sodiation mechanisms of anatase TiO₂ and guides on strategies about interfacial control for high performance anodes.     

Sulfur‐Modified Graphitic Carbon Nitride Nanostructures as an Efficient Electrocatalyst for Water Oxidation

There is an urgent need to develop metal‐free, low cost, durable, and highly efficient catalysts for industrially important oxygen evolution reactions. Inspired by natural geodes, unique melamine nanogeodes are successfully synthesized using hydrothermal process. Sulfur‐modified graphitic carbon nitride (S‐modified g‐CN _x ) electrocatalysts are obtained by annealing these melamine nanogeodes in situ with sulfur. The sulfur modification in the g‐CN _x structure leads to excellent oxygen evolution reaction activity by lowering the overpotential. Compared with the previously reported nonmetallic systems and well‐established metallic catalysts, the S‐modified g‐CN _x nanostructures show superior performance, requiring a lower overpotential (290 mV) to achieve a current density of 10 mA cm^?2 and a Tafel slope of 120 mV dec^?1 with long‐term durability of 91.2% retention for 18 h. These inexpensive, environmentally friendly, and easy‐to‐synthesize catalysts with extraordinary performance will have a high impact in the field of oxygen evolution reaction electrocatalysis.