Diffraction Radiation Research Articles

Study on Na2V0.67Mn0.33Ti(PO4)3 electrodes with ultralow voltage hysteresis for high performance sodium-ion batteries

The Na superionic conductor (NASICON) is one of the promising electrode materials used in advanced Na-based secondary batteries, but designing a low-overpotential structure is crucial for developing NASICON-type electrodes to repress voltage hysteresis and reduce energy loss. In this study, the integration of Mn3+ into a NASICON-type material (Na2VTi(PO4)3) decreases the voltage hysteresis of the redox couples due to the enlarged migration pathway for mobile Na+ ions. When using Na2V0.67Mn0.33Ti(PO4)3 as cathode material, two Na+ ions can be extracted from the structure, leading to the specific capacity of 110 mAh g−1 at the current density of 0.1 C. In operando synchrotron radiation diffraction elucidates that there is a combination of mono- and biphasic mechanisms for reversible Na+ insertion/extraction within initial two cycles. Moreover, fast sodium diffusion in the NMVTP electrode has been measured and analysed via first-principles calculation and real-time impedance spectroscopy. The results of this work indicate that Na2V0.67Mn0.33Ti(PO4)3 is a promising material for sodium-ion batteries.

Longitudinal charge distribution measurement of nonrelativistic ion beams using coherent transition radiation

Longitudinal charge profile measurements or bunch shape measurements is a challenge for temporally short non-relativistic bunches. The field profile has a larger longitudinal extent compared to the charge profile for such beams. This affects the ability of field sensing devices such as phase pick-ups or wall current monitors to measure charge distribution. Here we evaluate the feasibility for usage of coherent transition and diffraction radiation from non-relativistic beams for bunch shape measurements.

Crystallization kinetics and morphology of biochar modified bio-asphalt binder

Crystallization of biochar modified bio-asphalt binder (BMBA) directly affects their intrinsic physicochemical properties, which can significantly impact their processing and application. This research aims to maximize recycling the pyrolysis products of biomass (biochar and bio-oil) and investigate the crystallization kinetics of BMBA to inhibit the second crystallization and phase separation. Specifically, the parameters of crystallization kinetics and free volume were quantified using molecular dynamic simulations (MD). Relative crystallinity was evaluated using dynamic shear rheometer (DSR). Crystallization structure was analyzed using X-ray diffraction (XRD) and Synchrotron radiation small angle scattering (SAXS), and high-temperature-induced crystallization and low-temperature-physical hardening were quantified using hot-table polarizing microscope (HTPM). Crystallization morphology was measured by environmental scanning electron microscope (ESEM) and atomic force microscope (AFM). The parameters of crystallization kinetics show that high temperature and stress could induce the crystallization of BMBA. The low-temperature-physical hardening and aggregation of molecules indicate that the shape of BMBA crystals tends to be spherical under isothermal conditions but lamellar crystals under the non-isothermal conditions. This study provides a better understanding of the mechanism of crystallization kinetics of BMBA and a theoretical basis for the application of sustainable materials in asphalt pavement.

An alternative linear flow model and boundary integral flow representation for ship motions in regular waves

The basic issue of formulating a linear flow model for the analysis of potential flow around a ship advancing at a constant speed in regular waves is considered. Specifically, the ‘rigid-waterplane flow model’, previously considered for diffraction–radiation of regular waves by offshore structures, is applied to analyze flows around ships advancing in regular waves. A straightforward application of Green’s fundamental identity to the rigid-waterplane flow model yields a remarkable new boundary integral flow representation. Indeed, this flow representation does not involve a line integral around the mean waterline of the ship hull surface, is weakly singular, does not involve a distribution of dipoles over the ship-hull surface, and is free from irregular frequencies. In the particular case of flow around a ship steadily advancing in calm water, the boundary integral flow representation obtained in the study via an analysis based on the rigid-waterplane flow model is identical to the flow representation associated with the Neumann–Michell theory, which is based on a different linear flow model that only considers the flow region strictly outside the ship but consistently accounts for the linear contribution of the thin band of water between the wave profile along the ship hull surface and the undisturbed free surface. This result strongly suggests that the classical application of Green’s basic identity to analyze linear potential flow around a ship advancing in regular waves or in calm water, which yields a notoriously troublesome line integral around the ship waterline, may be questionable due to possible incompatibilities between the Neumann boundary condition at the ship hull surface and the linear free surface boundary condition associated with flows around ships advancing in calm water or in regular waves. This fundamental difficulty may be alleviated in the rigid-waterplane flow model, which imposes a compatibility condition between the Neumann boundary condition at the rigid lid that artificially closes the open ship hull surface and the linear boundary condition at the free surface above the waterplane-lid. The boundary integral flow representation given in the study also holds for diffraction–radiation of regular waves by offshore structures. Thus, this new flow representation provides a common mathematical basis, which fundamentally differs from the basis steadfastly adopted over the past fifty years, for the analysis of three basic classes of flows in ship and offshore hydrodynamics, and indeed can be applied more generally to other boundary-value problems such as those associated with flexural-gravity waves for ice sheets or very large floating structures.

Reply to “Comment on ‘Nonlinear quantum effects in electromagnetic radiation of a vortex electron' ”

We argue that although the experiment of Remez et al. [Phys. Rev. Lett. 123, 060401 (2019)] is interesting, and its conclusions may well be correct, the observed lack of dependence of the measured angular distributions on the electron's transverse coherence length could have been expected for the parameters chosen. This is because for Smith-Purcell radiation it is the coherence length of a virtual photon ${\ensuremath{\sigma}}_{\ensuremath{\perp}}^{(\ensuremath{\gamma})}\ensuremath{\approx}\ensuremath{\beta}\ensuremath{\gamma}\ensuremath{\lambda}\ensuremath{\lesssim}\ensuremath{\lambda}$ that plays a role of the radiation formation width and not the entire electron's coherence length that can well be orders of magnitude larger than the former. This is a common feature for all the radiation processes in which a photon is emitted not directly by the electron packet, which can be delocalized in space, but rather by a much better localized atom or a conduction electron on a surface. Therefore, in our opinion the results of Remez et al. cannot rule out the alternative hypothesis of the delocalized charge. The question, mainly addressed in the Comment by Karnieli et al., of whether the measurements were performed in the wave zone or not is interesting but somewhat secondary. We emphasize that the measured azimuthal distributions are unusually wide and there exists a family of classical effects that could also have resulted in the measured distributions. Such alternative classical hypotheses include: (i) effects of the beam sizes, of its angular divergence, of the temporal coherence of the radiation process, which is also related to how the wave zone is defined, and (ii) influence of the grating shape and of its material---the effects that are known to be of crucial importance for Smith-Purcell radiation from nonrelativistic electrons. Finally, we propose to repeat the experiment and to measure diffraction radiation from a thin metallic semiplane (or a strip) in which case the aforementioned classical effects play a much smaller role.

On the Crystal Chemistry of Photochromic Yttrium Oxyhydride

Yttrium oxyhydride exhibits photochromic properties at ambient temperature and pressures. Although oxygen plays an important role in determining the optoelectronic properties of the material, the question remains open regarding the site that it occupies in the crystal structure. In this paper, we address the issue by synchrotron radiation and neutron powder diffraction measurements. We report that the oxide anions occupy tetrahedral sites together with hydride anions in the face-centered cubic structure.

Structural aspects and magnetoelectric behavior of hexagonal Sr1-xBaxMnO3 (x=0, 0.4) manganites: Effect of leakage currents

Structural, morphological, magnetic, and electrical properties of the challenging Sr1-xBaxMnO3 (x=0, 0.4) manganite are discussed. Polycrystalline Sr1-xBaxMnO3 samples were prepared via the standard solid-state reaction. Conventional X-ray diffraction and synchrotron radiation measurements showed the hexagonal structure (space group P63/mmc) of the samples. The stability of the hexagonal symmetry of Sr0.6Ba0.4MnO3 persisted up to 120 K. This result, along with the fact that the space group P63/mmc is centrosymmetric, discounted the possibility of having a long-range ferroelectric ordering. Pristine SrMnO3 samples exhibited an antiferromagnetic transition at a Néel temperature ∼280 K. In turn, Sr0.6Ba0.4MnO3 showed two transitions at ∼325 K and ∼270 K. Measurements of the electrical polarization versus the electric field showed closed loops, although visually distinct from those of a true ferroelectric material. Hence it was evident that spurious effects caused the polarization curves that resembled ferroelectric loops. Resistivity measurements on Sr0.6Ba0.4MnO3 showed the insulating nature of these samples.

Short-range order of liquid Ti72.3Fe27.7 investigated by a combination of neutron scattering and X-ray diffraction

Abstract In this work we report on investigations into the topological and chemical short-range order of binary Ti72.3Fe27.7 alloy melts. In order to analyse the structure, the melts were investigated by means of neutron scattering and energy dispersive diffraction of synchrotron radiation. The combination of both diffraction techniques allowed the determination of the partial Bhatia Thornton structure factors S NN(Q) and S CC(Q). The experimental results provide evidence of an icosahedral topological short-range order prevailing in the liquid that is accompanied by a pronounced chemical short-range order such that Ti –Fe nearest neighbours are preferentially formed.

Elucidation of the redox activity of Ca2MnO3.5 and CaV2O4 in calcium batteries using operando XRD: charge compensation mechanism and reversibility

Ca2MnO3.5 and CaV2O4 were found to be potentially interesting as positive electrode materials for calcium metal-based high-energy density batteries with DFT-predicted average voltages of 3.7 V and 2.5 V and energy barriers for Ca migration of 1.1 eV and 0.6 eV, respectively. Both compounds were prepared by solid state reaction under reducing atmospheres. Optimum conditions to achieve Ca2MnO3.5 comprised the reduction of Ca2MnO4 under NH3 gas at 420⁰C with a flow rate of 1200 ml/min while CaV2O4 was achieved by reduction of CaV2O6 at 700 ⁰C under H2 flow. Electrochemical oxidation of Ca2MnO3.5 in lithium or calcium cells resulted in the formation of an orthorhombic phase with cell parameter (a= 5.2891(1), b= 10.551(2), c= 12.1422(1)). Operando synchrotron radiation diffraction experiments indicate that the charge compensation mechanism is not related to Ca2+ extraction but to intercalation of F− (originated from electrolyte salt decomposition) into the anion vacancy position, as confirmed by EELS and EDS. This process was found to be irreversible. In the case of CaV2O4, oxidation induces the electrochemical extraction of calcium with the formation of an orthorhombic phase (space group Pbnm) with cell parameters a = 10.72008(9) Å, b = 9.20213(2) Å and c = 2.89418(3) Å. The process was also investigated via operando synchrotron radiation diffraction, with the oxidized phase being found to reintercalate Ca2+ ions upon reduction, with the formation of a solid solution. Preliminary cycling tests reveals a decrease in the polarization after the first cycle and call for further investigation of this system.

Microstructural and Mechanical Properties of Nitrogen Ion Irradiated 316 Stainless Steel

Nitrogen ion implantation can be used to improve the surface mechanical properties of austenitic stainless steel (ASS). In this study, ASS was irradiated with 1.1 MeV N ions at room temperature up to 15 displacements per atom. Then the microstructural and mechanical properties were studied by grazing incidence X-ray diffraction and nano-indenter. A finer synchrotron radiation diffraction pattern is obtained compared with traditional X-ray diffraction, indicating an expanded austenite phase γN and CrN phase after being irradiated to several damage levels. An irradiation-induced martensite phase appears first and then disappears with increased damage. The enrichment of the nitrogen supply in ASS can explain this phenomenon. The hardness data show an irradiation hardening phenomenon. Two different inflexion points hc1 and hc2 in H2 versus 1/h curves are observed, and the real hardness of the irradiation damaged layer can be obtained from the H2 versus 1/h curve between hc1 and hc2.

Adsorption and reaction of an alkyne molecule on diverse oxygen-reconstructed Cu(110) surfaces

Studying the adsorption and reaction behaviors of organic molecules on solid surfaces holds great significance for producing high-performance organic films. Alkynes recently gain increasing popularity in on-surface self-assembly and reaction due to the peculiar nature of alkynyl groups. Here, we deposited 4-ethynyl-1,1′-biphenyl molecules (EBPs) on various oxygen-reconstructed Cu(110) surfaces derived from controllable oxidations. Both the structures of reconstructed surfaces and the adsorption/reaction properties of EBPs were investigated by scanning tunneling microscopy (STM), complemented with low energy electron diffraction (LEED) and synchrotron radiation photoelectron spectroscopy (SRPES). It is revealed that on the striped Cu-O nanotemplate surface, dehydrogenated EBPs prefer to decorate Cu region and form V-shaped dimers in large proportion. At the Cu/Cu-O interface, EBPs are aligned with their long axis along the Cu-O chain growth direction. Annealing to elevated temperatures merely induces intermolecular reactions among a few monomers. On the complete Cu(110)-(2 × 1)O surface, intact EBPs self-assemble into ordered and well-defined islands, where EBPs are confined by channels between Cu-O chains. On Cu(110)-c(6 × 2)O structure, non-covalent EBP dimers are dominant species. The orientation of these dimers is found to be dictated by corrugation between super Cu atom rows. Moreover, a Cu(110)-p(2 × 3)O surface is attained for the first time in this work, which, however, hardly anchor EBPs. In general, this work serves a model system for the research on adsorption and reaction of alkyne molecules on metal oxide surfaces.

Investigation on surface plasmon polaritons and localized surface plasmon production mechanism in micro-nano structures

The simulation mechanism of surface plasmon polaritons (SPPs) and localized surface plasmon (LSP) in different structures was studied, including the Au reflection grating (Au grating), Au substrate with dielectric ribbons grating (Au substrate grating), and pure electric conductor (PEC) substrate with Au ribbons grating (Au ribbons grating). And the characteristics of the Smith-Purcell radiation in these structures were presented. Simulation results show that SPPs are excited on the bottom surface of Au substrate grating grooves and LSP is stimulated on the upper surface both of Au ribbons grating grooves and Au grating grooves. Owing to the irreconcilable contradiction between optimizing the grating diffraction radiation efficiency and optimizing the SPPs excitation efficiency in the Au substrate grating, only 40-times enhancement of the radiation intensity was obtained by excited SPPs. However, the LSP enhanced structure overcomes the above problem and gains much better radiation enhancement ability, with about 200-times enhancement obtained in the Au ribbons grating and more than 500-times enhancement obtained in the Au grating. The results presented here provide a way of developing miniature, integratable, tunable, high-power-density radiation sources from visible light to ultraviolet rays at room temperature.

Temperature dependence of lattice mismatch and γ′ volume fraction of a fourth-generation monocrystalline nickel-based superalloy

AbstractThe strain distribution in a new generation nickel-based single crystal superalloy has been determined in the temperature range 293 K– 1598 K. Measurements have been performed using diffraction of high energy synchrotron radiation (150 keV,λ= 0.008 nm) to determine the variations with temperature of the γ/γ′ lattice mismatch and of the γ′ volume fraction. The chemical segregation at the dendrite scale and the internal stress induce a large range of values for the lattice mismatch. The measurements of the γ′ volume fraction determined by X-ray diffraction are in agreement with those obtained by atom probe tomography, image analysis or computation.

Electron beam chiral diffraction radiation in isosceles right triangle light-well

<sec>Electron beam diffraction radiation source has the advantages of small size, wavelength tunability, and polarization controllability, showing great potential applications in nanophotonic circuits. However, studies of optical chirality of electron beam diffraction radiation are relatively scarce. The optical chirality of electron beam diffraction radiation in isosceles right triangle light-well is realized and demonstrated in this work. The light-well consists of twelve alternating layers of gold and silicon dioxide, and the electron beam diffraction radiation originates from oscillating dipole sources within the light-well. In the case of the electron beam injected at the geometrically asymmetric position within the structure, the diffraction radiation signal with a maximum chirality of more than 40% can be obtained. By changing the injection position of the electron beam, the state of the optical chirality can be effectively controlled, and even the inversion of the chirality can be realized.</sec><sec>By analyzing the vacuum electromagnetic mode in the system and the dynamic evolution of charge distribution in the gold layer, a reasonable theoretical explanation is provided for the generation of the chiral optical effect. A semi-analytical model for explaining the optical chirality of electron beam diffraction radiation is given by solving the incident electromagnetic field and the waveguide modes in the light-well. The observed difference between left-handed circularly polarized and right-handed circularly polarized signals originates from the asymmetry between left-handed and right-handed electromagnetic modes in the light-well caused by the geometrically asymmetric positional excitation, which ultimately leads to far-field chiral radiation determined by the electromagnetic field within the light-well. In addition, the simulation results of the surface charge distribution of the top gold film of the light-well reveal the correlation between the dynamic evolution of the surface charge distribution and the radiation chirality.</sec><sec>The advantages of nanoscale focusing and moving of electron beam excitation source make the optical chirality of electron beam diffraction radiation have more flexible adjustment potential. The proposed physical mechanism and unique experimental platform not only provide new ideas for manipulating optical chirality on a nanoscale, but also lay the foundation for binary information processing and integration in nanophotonic circuits and chiral nano-light-sources in the future.</sec>

Electron beam chiral diffraction radiation in an isosceles right triangle light-well

Electron beam diffraction radiation sources have the advantages of small size, wavelength tunability, and polarization controllability, showing great application potential in nanophotonic circuits. However, studies on optical chirality of electron beam diffraction radiation are relatively scarce. The optical chirality of electron beam diffraction radiation in isosceles right triangle light-well is realized and demonstrated in this work. The light-well consists of twelve alternating layers of gold and silicon dioxide, and the electron beam diffraction radiation originates from oscillating dipole sources within the light-well. In the case of the electron beam injecting at the geometrically asymmetric position within the structure, the diffraction radiation signal with a maximum chirality of more than 40% can be obtained. By changing the injection position of the electron beam, the state of the optical chirality can be effectively controlled, and even the inversion of the chirality can be realized.<br>By analyzing the vacuum electromagnetic mode in the system and the dynamic evolution of charge distribution in the gold layer, a reasonable theoretical explanation is provided for the generation of the chiral optical effect. A semi-analytical model for explaining the optical chirality of electron beam diffraction radiation is given by solving the incident electromagnetic field and the waveguide modes in the light-well. The observed difference between left-handed circularly polarized and right-handed circularly polarized signals originates from the asymmetry between left-handed and right-handed electromagnetic modes in the light-well caused by the geometrically asymmetric positional excitation, which ultimately leads to far-field chiral radiation determined by the electromagnetic field within the light-well. In addition, the simulation results of the surface charge distribution of the top gold film of the light-well reveal the correlation between the dynamic evolution of the surface charge distribution and the radiation chirality.<br>The advantages of nanoscale focusing and moving of electron beam excitation source make the optical chirality of electron beam diffraction radiation have more flexible adjustment potential. The proposed physical mechanism and unique experimental platform not only provide new ideas for manipulating optical chirality at the nanoscale, but also lay the foundation for binary information processing and integration in nanophotonic circuits and chiral nano-light-sources in the future.

Structural transition and temperature dependencies of thermal expansion coefficients of NaNO-=SUB=-3-=/SUB=- embedded into the nanoporous glass

The temperature evolution of the crystal structure of a nanocomposite material obtained by introducing sodium nitrate NaNO3 from a melt under pressure into a nanoporous alkali borosilicate glass with an average pore diameter of 7 nm has been studied by the method of diffraction of synchrotron radiation in a wide temperature range upon heating. Analysis of the experimental diffraction patterns revealed a significant decrease in the temperature of the structural (orientational) transition by more than 50 K (up to 496 K) compared to bulk sodium nitrate. From the temperature dependence of the intensity of the superstructure peak (113), the dependence of the critical exponent β(T) for this transition was obtained and a significant difference from the critical exponent for a bulk material was found in the temperature range from 455 K to the transition temperature. Analysis of the broadening of Bragg reflections made it possible to estimate the average size (~40 nm) of sodium nitrate nanoparticles into the pores. An increase in the linear coefficient of thermal expansion in the [001] direction was found in NaNO3 nanoparticles in comparison with bulk material at temperatures above 450 K. Keywords: porous glasses, phase transitions, nanocomposite materials, synchrotron radiation diffraction, sodium nitrate, restricted geometry, structure, size effects.

Структурный переход и температурные зависимости коэффициентов теплового расширения NaNO-=SUB=-3-=/SUB=-, внедренного в нанопористое стекло

The temperature evolution of the crystal structure of a nanocomposite material obtained by introducing sodium nitrate NaNO3 from a melt under pressure into a nanoporous alkali borosilicate glass with an average pore diameter of 7 nm has been studied by the method of diffraction of synchrotron radiation in a wide temperature range upon heating. Analysis of the experimental diffraction patterns revealed a significant decrease in the temperature of the structural (orientational) transition by more than 50 K (up to 496 K) compared to bulk sodium nitrate. From the temperature dependence of the intensity of the superstructure peak (113), the dependence of the critical exponent β (T) for this transition was obtained and a significant difference from the critical exponent for a bulk material was found in the temperature range from 455 K to the transition temperature. Analysis of the broadening of Bragg reflections made it possible to estimate the average size (~ 40 nm) of sodium nitrate nanoparticles into the pores. An increase in the linear coefficient of thermal expansion in the [001] direction was found in NaNO3 nanoparticles in comparison with bulk material at temperatures above 450 K.

X-Ray Diffraction Line Broadening and Radiation Damage

X-Ray Diffraction Line Broadening and Radiation Damage

Approaches to variation of the profile of the radiating opening of a diffractive antenna radiation to improve directional characteristics

Approaches to variation of the profile of the radiating opening of a diffractive antenna radiation to improve directional characteristics

Application of Synchrotron Radiation and Neutron Diffraction Technologies in Additive Manufacturing

Application of Synchrotron Radiation and Neutron Diffraction Technologies in Additive Manufacturing