Synchrotron Radiation Diffraction Research Articles

Interactions of CaO with pure Mg and Mg-Ca alloys—an in situ synchrotron radiation diffraction study

CaO additions are used as an inexpensive replacement for Ca in Mg alloys. CaO dissociation in Mg has been reported in literature without a clear mechanism as to why this occurs. In situ synchrotron radiation diffraction investigation of the melting and solidification of Mg with CaO shows, that the stability of CaO was overestimated in Mg melts compared with MgO. The experiments that were performed on the Mg-20CaO and Mg-xCa-6CaO (x = 6 and 16 wt.%) alloys, show the dissociation and formation of various phases during melting and solidification. The results indicate that Mg can reduce CaO even in the solid state, which is the opposite of that proposed by the Ellingham diagrams for stoichiometric reaction. Phase formations during the in situ experiment are compared with published thermodynamic calculations for the interaction between Mg-Ca alloys and oxides.

The synthesis of the rare earth A2Zr2O7 single crystals by simplified laser-heated floating hot zone and pedestal methods

The condensed matter community is in constant search for efficient and feasible methods for the synthesis of diverse compounds, especially in the single-crystalline form. We present a recipe for the simplified synthesis of high-quality single crystals of rare-earth zirconates A2Zr2O7, important from both the fundamental and technical application viewpoints,. The developed preparation route allows to effectively, repeatedly, and reliably synthesise the high-quality precursors and single crystals of desired compositions, avoiding contamination and difficulties connected with standard polycrystalline-precursor preparation. Simultaneously, the method is straightforward, saving time, energy, and personnel. In addition to previously reported single crystals, several new single crystals from the A2Zr2O7 series were prepared, including the previously unreported compound Tm2Zr2O7. The high quality of the synthesised samples was proven employing electron microscopy, X-ray diffraction, laboratory and synchrotron radiation diffraction, and neutron powder and Laue diffraction techniques. The crystal structures and structural parameters of the individual compounds were determined and discussed in view of previous reports on A2Zr2O7 and other A2B2O7 series (B stands for d- or p-elements). The introduced synthesis route is proposed to serve well not only for several other A2B2O7 series, but also for a variety of unrelated compounds.

Microstructure and texture control of Ni-Mn-Ga magnetic shape memory alloys manufactured by laser powder bed fusion

The Laser Powder Bed Fusion (LPBF) process was used to manufacture Ni-Mn-Ga polycrystalline samples. The initial powders with a fine particle size of about 20 µm were firstly prepared by a ball milling from melt-spun ribbons. The microstructure and texture evolution of Ni-Mn-Ga alloy manufactured by LPBF were investigated employing SEM, TEM, and synchrotron radiation diffraction. Using two different scanning strategies, optimization of laser parameters and post-processing heat treatment, a homogeneous microstructure with a strong crystallographic texture was obtained. The localized heating/cooling conditions allow obtaining a layered structure with preferred <100> fiber orientations along the growth direction. The crystal structure and crystallographic texture drastically change when the laser oscillation mode is chosen. The strong crystalline anisotropy and layered-type microstructure have a significant impact on twining flow behavior giving rise to an anisotropic mechanical response. The variant reorientation during mechanical training is realized by the so-called orthogonal shearing. It is also shown that the resulting crystal structure and characteristic transformation temperatures are strongly dependent on chemical composition related to Mn losses and internal stresses along with chemical order creating metastable phases due to the extremely high cooling rate upon the 3D printing. Therefore, all the above parameters are thoroughly monitored during the three-stage fabrication process.

Microstructure gradients across the white etching and transition layers of a heavy haul pearlitic steel

This study delves into the frequent surface cracking observed in severely damaged pearlitic carbon steel rails, a phenomenon often attributed to the challenging characteristics of the white etching layer (WEL) formed during railway operations. To explore this issue, a severely damaged rail cross-section featuring a substantial WEL layer measuring 600 μm in depth was analyzed. The WEL's size was initially determined through optical microscopy and characterized via nano-hardness testing, which revealed an impressive hardness of up to 12 GPa. High-energy synchrotron X-ray diffraction (HESXRD) analysis was employed to uncover the crystalline structure diversity gradient that resulted from railway use. The results unveiled that cumulative high-temperature surface damage leads to the formation of both the WEL and a transitional layer. Within this transitional layer, a gradual reduction in retained austenite is observed, coupled with an increase in the presence of cementite and ferrite as one approaches the base metal. Remarkably, very shallow depths from the surface display tempered martensite characteristics, characterized by high nanohardness, lower dislocation density, and an initially smaller, then increasing austenite fraction. The use of site-resolved synchrotron radiation diffraction at different depths from the surface to the interior of the damaged rail cross-section allowed a unique insight into the phase transformations, microstrain developments, and compositional evolution.

Grazing-incidence synchrotron radiation diffraction studies on irradiated Ce-doped and pristine Y-stabilized ZrO2 at the Rossendorf beamline.

In this work, Ce-doped yttria-stabilized zirconia (YSZ) and pure YSZ phases were subjected to irradiation with 14 MeV Au ions. Irradiation studies were performed to simulate long-term structural and microstructural damage due to self-irradiation in YSZ phases hosting alpha-active radioactive species. It was found that both the Ce-doped YSZ and the YSZ phases had a reasonable tolerance to irradiation at high ion fluences and the bulk crystallinity was well preserved. Nevertheless, local microstrain increased in all compounds under study after irradiation, with the Ce-doped phases being less affected than pure YSZ. Doping with cerium ions increased the microstructural stability of YSZ phases through a possible reduction in the mobility of oxygen atoms, which limits the formation of structural defects. Doping of YSZ with tetravalent actinide elements is expected to have a similar effect. Thus, YSZ phases are promising for the safe long-term storage of radioactive elements. Using synchrotron radiation diffraction, measurements of the thin irradiated layers of the Ce-YSZ and YSZ samples were performed in grazing incidence (GI) mode. A corresponding module for measurements in GI mode was developed at the Rossendorf Beamline and relevant technical details for sample alignment and data collection are also presented.

Study of the micro-yielding behavior in a SiCp/Mg–Zn–Ca composite using synchrotron radiation diffraction

Study of the micro-yielding behavior in a SiCp/Mg–Zn–Ca composite using synchrotron radiation diffraction

Multi-scale investigation of microstructure and texture evolution during equal channel angular pressing of silver

A multi-scale investigation was carried out on pure silver subjected to equal channel angular pressing up to 3 passes. Microstructure and texture were examined using scanning and transmission electron microscopy as well as diffraction of neutron and high-energy synchrotron radiation. The evolution of the deformation substructure in the material is in accordance with its low stacking fault energy followed by restoration mechanisms leading to overall microstructural refinement. The restoration mechanism sets in as early as after 3 passes. Twinning involved in the deformation process supports grain refinement through mechanisms of dynamic recrystallization involving strain-induced boundary migration contributing to a steady-state grain size. The global texture, as measured by neutron diffraction, forms through a twin-assisted deformation mechanism. The texture is found heterogeneous through thickness.Graphical abstract

Insights into the Phase Purity and Storage Mechanism of Nonstoichiometric Na3.4Fe2.4(PO4)1.4P2O7 Cathode for High‐Mass‐Loading and High‐Power‐Density Sodium‐Ion Batteries

AbstractMixed‐anion‐group Fe‐based phosphate materials, such as Na4Fe3(PO4)2P2O7, have emerged as promising cathode materials for sodium‐ion batteries (SIBs). However, the synthesis of pure‐phase material has remained a challenge, and the phase evolution during sodium (de)intercalation is debating as well. Herein, a solid‐solution strategy is proposed to partition Na4Fe3(PO4)2P2O7 into 2NaFePO4 ⋅ Na2FeP2O7 from the angle of molecular composition. Via regulating the starting ratio of NaFePO4 and Na2FeP2O7 during the synthesis process, the nonstoichiometric pure‐phase material could be successfully synthesized within a narrow NaFePO4 content between 1.6 and 1.2. Furthermore, the proposed synthesis strategy demonstrates strong applicability that helps to address the impurity issue of Na4Co3(PO4)2P2O7 and nonstoichiometric Na3.4Co2.4(PO4)1.4P2O7 are evidenced to be the pure phase. The model Na3.4Fe2.4(PO4)1.4P2O7 cathode (the content of NaFePO4 equals 1.4) demonstrates exceptional sodium storage performances, including ultrahigh rate capability under 100 C and ultralong cycle life over 14000 cycles. Furthermore, combined measurements of ex situ nuclear magnetic resonance, in situ synchrotron radiation diffraction and X‐ray absorption spectroscopy clearly reveal a two‐phase transition during Na+ extraction/insertion, which provides a new insight into the ionic storage process for such kind of mixed‐anion‐group Fe‐based phosphate materials and pave the way for the development of high‐power sodium‐ion batteries.

Insights into the Phase Purity and Storage Mechanism of Nonstoichiometric Na3.4 Fe2.4 (PO4 )1.4 P2 O7 Cathode for High-Mass-Loading and High-Power-Density Sodium-Ion Batteries.

Mixed-anion-group Fe-based phosphate materials, such as Na4 Fe3 (PO4 )2 P2 O7 , have emerged as promising cathode materials for sodium-ion batteries (SIBs). However, the synthesis of pure-phase material has remained a challenge, and the phase evolution during sodium (de)intercalation is debating as well. Herein, a solid-solution strategy is proposed to partition Na4 Fe3 (PO4 )2 P2 O7 into 2NaFePO4 ⋅ Na2 FeP2 O7 from the angle of molecular composition. Via regulating the starting ratio of NaFePO4 and Na2 FeP2 O7 during the synthesis process, the nonstoichiometric pure-phase material could be successfully synthesized within a narrow NaFePO4 content between 1.6 and 1.2. Furthermore, the proposed synthesis strategy demonstrates strong applicability that helps to address the impurity issue of Na4 Co3 (PO4 )2 P2 O7 and nonstoichiometric Na3.4 Co2.4 (PO4 )1.4 P2 O7 are evidenced to be the pure phase. The model Na3.4 Fe2.4 (PO4 )1.4 P2 O7 cathode (the content of NaFePO4 equals 1.4) demonstrates exceptional sodium storage performances, including ultrahigh rate capability under 100 C and ultralong cycle life over 14000 cycles. Furthermore, combined measurements of ex situ nuclear magnetic resonance, in situ synchrotron radiation diffraction and X-ray absorption spectroscopy clearly reveal a two-phase transition during Na+ extraction/insertion, which provides a new insight into the ionic storage process for such kind of mixed-anion-group Fe-based phosphate materials and pave the way for the development of high-power sodium-ion batteries.

Surface structure of BaTiO&lt;sub&gt;3&lt;/sub&gt; single crystal and the influence of pH value of liquid on its surface structure

Ferroelectric material is a kind of material with spontaneous polarization, and water is a common polar solvent. Due to polarity, there are complex interactions at the interface between ferroelectric materials and water/aqueous solutions. Understanding these physical processes and mechanisms is of great significance for both theoretical research and practical applications. Herein, the surface structure of (001) orientated BaTiO&lt;sub&gt;3&lt;/sub&gt; with (001) direction polarization single crystal is studied by synchrotron radiation diffraction technology, and the effects of liquids with different pH values on surface structure of BaTiO&lt;sub&gt;3&lt;/sub&gt; single crystal was also investigated. The results show that BaTiO&lt;sub&gt;3&lt;/sub&gt; single crystal contains a surface layer with a low electron density, and due to the effect of polarity, a 2.6 nm-thick water layer is adsorbed on the surface of BaTiO&lt;sub&gt;3&lt;/sub&gt; single crystal. After adding deionized water on the surface, there is no significant change in the surface layer structure of BaTiO&lt;sub&gt;3&lt;/sub&gt;. Low temperature &lt;i&gt;in-situ&lt;/i&gt; grazing incidence X-ray diffraction experiments indicate the presence of ice on the surface, further confirming the existence of adsorbed water layers on the surface. A hydrochloric acid solution with pH = 1 has no significant effect on the surface structure of BaTiO&lt;sub&gt;3&lt;/sub&gt;, either, which is possibly due to the ability of acidic solutions to stabilize the original polarization direction. However, an NaOH solution with a pH = 13 can thicken the surface layer, which possibly results from the weakening of surface polarization caused by alkaline solutions, thereby changing the surface depolarization field and surface layer thickness.

Insights into P-Type Iron- and Manganese-Based Layered Sodium Cathodes

Sodium-ion batteries are a low-cost alternative to lithium-ion batteries in large-scale electric energy storage applications due to the natural-abundant sodium resources and similar working principle to LIBs during cycling [1]. Until now, many different cathodes for SIBs have been studied, including layered transition metal oxides (NaxTMO2, x<1), Prussian blue-type compounds, polyanionic and organic compounds [2]. Among them, NaxTMO2 has been extensively reported, due to its layered structure, easy synthesis, promising electrochemical properties, and feasibility for commercial production [3]. According to the occupation of Na ions and oxygen stacking, NaxTMO2 can be classified into P2 and O3 types, where P2 structure contasins trigonal prismatic sites of sodium ions and ABBA oxygen stacking sequence and O3 structure represents octahedral sites of sodium ions and ABCABC oxygen stacking sequence [4]. At low potentials (<2.0V), there is a phase transition P2-P2’ connected with the manganese redox activity and the Jahn-Teller distortion [5]. Compared with O3-type structure, P2-type NaxTMO2 provides higher specific capacity and better structural stability due to the lower diffusion barriers through Na-ion prismatic sites [6].Iron- and manganese-based layered oxides for sodium-ion batteries have attracted renewed interest due to their low cost and environmental friendliness. However, the phase change at high voltage and the Jahn-Teller effect lead to shortening cycle life and poor rate capability. We design a structure optimization of the Na2/3Mn1/2Fe1/2O2 cathode through a partial substitution of Fe3+ to explore the mechanism of redox activity of P2-type Mn/Fe-based layered cathodes. We present the investigation of the effect of simultaneous cationic substitution on the electrochemical performance and structural stability of P2-Na2/3Mn1/2Fe1/2O2. The obtained material exhibits a solid solution mechanism during desodiation/resodiation process and delivers an initial discharge capacity of 168 mA h g-1 at 0.1C and a capacity retention of 80% after 50 cycles. The modified P2 composition has stable cycle performance in the potential window from 1.5V to 4.5V. The main focus here is to understand the fundamental electrochemical mechanism of this layered cathode material by exploring the redox processes of transition metal cations and oxygen anions upon cycling. In situ X-ray synchrotron radiation diffraction is used to explore the structural changes during cycling. In situ X-ray Absorption Near Edge Spectroscopy is used to elucidate the local electronic structure of Fe and Mn atoms as it evolves throughout this electrochemical process. 23Na solid-state nuclear magnetic resonance spectroscopy is used to investigate Na coordination environments during desodiation/resodiation. Ex situ soft X-ray absorption spectroscopy results reveal the participation of oxygen anions in the electrochemical reactions. Thus, we explore the redox reactions of transition metals and oxygen to explain the mechanism and the electrochemical performance for the P2-type Mn/Fe-based layered cathodes.

Impact of Bi doping on the structural, optical, and dielectric features of nano ZnMn2O4

This work aims to upgrade the functional properties of ZnMn2O4 via doping with Bi3+. Nano ZnMn2-xBixO4 (x = 0, 0.03, 0.05, 0.07, 0.1, 0.15, 0.2) samples were prepared by the sol-gel method. The structure, microstructure, and formed phases in ZnMn2-xBixO4 samples were determined using Rietveld-calculated profile fitting of the experimental x-ray synchrotron radiation diffraction data. The tetragonal spinel ZnMn2O4 phase was formed with a tiny (∼2–4 %) hexagonal ZnO phase. The morphology and different vibration bands in ZnMn2-xBixO4 samples were investigated using scanning electron microscopy and Fourier transform infrared techniques. The diffused reflectance technique was used to explore the effect of Bi doping on the absorbance and optical band gap of ZnMn2O4. The optical band gap energy decreased from 2.42 to 1.83 eV as the percentage of Bi-doped ZMO increased from 0 to 10 %, then increased again for higher Bi content. The dielectric permittivity is affected by the Bi-doped amounts and temperature. As the amount of Bi and temperature increased, the impedance of the ZMO sample and relaxation time changed. All samples exhibited both metallic and semiconducting behaviors. All samples have a non-Debye relaxation phenomenon. Samples with x = 0.03 and 0.2 exhibited the maximum conductivity among other doped samples. These findings introduce ZnMn2-xBixO4 samples for new applications in optoelectronics and optical devices.

Application of Synchrotron-Radiation Diffraction Techniques for Optimizing the Sintering Trajectory of Al2O3–Ce:(Y,Gd)AG Composite Ceramics

Application of Synchrotron-Radiation Diffraction Techniques for Optimizing the Sintering Trajectory of Al2O3–Ce:(Y,Gd)AG Composite Ceramics

Determination of DNA architecture of bacteria under various types of stress, methodological approaches, problems, and solutions.

Actively growing cells maintain a dynamic, far from equilibrium order through metabolism. Under starvation stress or under stress of exposure to the analog of the anabiosis autoinducer (4-hexylresorcinol), cells go into a dormant state (almost complete lack of metabolism) or even into a mummified state. In a dormant state, cells are forced to use the physical mechanisms of DNA protection. The architecture of DNA in the dormant and mummified state of cells was studied by x-ray diffraction of synchrotron radiation and transmission electron microscopy (TEM). Diffraction experiments indicate the appearance of an ordered organization of DNA. TEM made it possible to visualize the type of DNA ordering. Intracellular nanocrystalline, liquid-crystalline, and folded nucleosome-like structures of DNA have been found. The structure of DNA within a cell in an anabiotic dormant state and dormant state (starvation stress) coincides (forms nanocrystalline structures). Data suggest the universality of DNA condensation by a protein Dps for a dormant state, regardless of the type of stress. The mummified state is very different in structure from the dormant state (has no ordering within a cell). It turned out that it is possible to visualize DNA conformation in toroidal and liquid crystal structures in which there is either no or a very small amount of the Dps protein. Observation of the DNA conformation in nanocrystals and folded nucleosome-like structures so far has been inconclusive. The methodological advances described will facilitate high-resolution visualization of the DNA conformation in the near future.

Quantification of side reactions in lithium-ion batteries during overcharging at elevated temperatures

Lithium-ion batteries experience complex reactions between the electrodes and the electrolyte under non-standard conditions. Investigating these reactions is crucial for ensuring battery durability and safety. In this study, we develop an electrochemical cell capable of controlled overcharging and temperature regulation between 30 and 100 °C. The charge-discharge performance of the cell is evaluated after overcharging. By utilizing synchrotron radiation for X-ray diffraction and absorption fine structure analysis, we track the electronic state of the positive electrode and the crystal structure of the negative electrode during heated overcharging. Our results reveal increased side reactions in the positive electrode at higher temperatures during overcharging, while the negative electrode displays a gradual increase in side reactions in the normal charge-discharge region with increasing temperature. Specifically, at 100 °C, side reactions in the overcharging regions consume 86.5% and 66.1% of the current at the positive and negative electrodes, respectively. These side reactions are induced by the electrolyte oxidative decomposition at the positive electrode. Moreover, they initiate Joule heating during battery overcharging, promoting side reactions and leading to exothermic reactions between the electrodes and electrolyte.

放射光回折システムの高機能化と機能性材料の開発研究

Driven by improvement of the computer speed and tremendous efforts of crystallographers and equipment manufacturers, X-ray structure analysis has recently become relatively easy and requires no specialized knowledge. On the other hand, synchrotron radiation diffraction experiments have mainly aimed at advanced structural analysis, including electron density analysis, taking advantage of stable and intense X-rays. In recent years, demand for the use of the facility in the materials field has increased, but researchers unfamiliar with synchrotron radiation experiments have felt difficulty in use. Based on my experience in developing conventional diffractometers and software at the equipment manufacturer where I worked after obtaining my degree, I have promoted the development of advanced synchrotron radiation X-ray diffraction systems at SPring-8, a large synchrotron radiation facility. In particular, I have been responsible for the single crystal structure analysis beamline（BL02B1）and the powder diffraction beamline（BL02B2）, which have a wide range of user groups and diverse requirements for instrumental performance, and engaged in instrument development. In addition, I have also worked on structural analysis of functional materials and clarified their structure-function relationships. Among them, I introduce fruitful results on generation process of magnesia cement and design of spin crossover Fe（II）complexes. I believe that such upgrading of synchrotron radiation diffraction systems and development research of functional materials could not be performed without hardware and software knowledge which I learned at the equipment manufacturer.

Computer Simulation of the Effect of Coherent Dynamical Diffraction of Synchrotron Radiation in Crystals of Arbitrary Shape and Structure

Computer Simulation of the Effect of Coherent Dynamical Diffraction of Synchrotron Radiation in Crystals of Arbitrary Shape and Structure

Local variations of the piezoelectric properties of an LiNb(1−x)Ta x O3 crystal

An in situ study of the spatial distribution of the piezoelectric properties of an LiNb(1−x)Ta x O3 crystal (〈x〉 = 0.088) in an external DC electric field was performed by the method of X-ray diffraction of synchrotron radiation at angles close to 180°. The variation of the d 22 piezoelectric coefficient was determined with high accuracy (up to 2%) in local areas by the angular shift of the diffraction maximum under the action of the electric field (E = 1582 V mm−1) applied on the crystal along the Y axis, during scanning along the X and Z directions. A correlation between the piezoelectric strain amplitude and the concentration of tantalum obtained by X-ray fluorescence mapping has been established.

Revealing the weak work-hardening behavior in aged Mg–RE alloys: A synchrotron radiation diffraction study

Magnesium (Mg) alloys with rare-earth (RE) elements have received increasing attention as the lightest structural materials. However, they often present a weak work-hardening behavior after aging treatment, with the reason behind remaining unclear. In this work, in situ tensile tests combined with synchrotron radiation diffraction technique were utilized to investigate the evolution of basal and non-basal dislocations in two aged Mg alloys with different volume fractions of β1 precipitates. The results of standard Williamson–Hall (W–H) analysis indicated that more basal dislocations were activated at higher stress. This work emphasized that the underwhelming work-hardening was correlated to the synergy of high-density basal dislocations and relatively low-density non-basal dislocations during deformation.

Monoclinic symmetry of the hcp-type ordered areas in bulk cobalt

The gradual ferromagnetic spin reorientation in hexagonal close packed cobalt (hcp-Co) phase between $230{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$ and $330{\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}\mathrm{C}$ reported for a Co single crystal [Bertaut et al., Solid State Commun. 1, 81 (1963)] suggests that this phase could not have a hexagonal symmetry. This hypothesis is verified positively by synchrotron radiation diffraction and neutron diffraction on polycrystalline powder cobalt. The analysis of diffraction data has been done by using a specific set of Bragg peaks, which are not sensitive to the stacking faults present in abundance in hcp-Co. The crystal structure of the hcp-type ordered areas of cobalt is described by the monoclinic symmetry with the magnetic space group $C{2}^{\ensuremath{'}}/{m}^{\ensuremath{'}}$. In this monoclinic crystal structure the former hexagonal [001] axis is no longer perpendicular to the hexagonal layers. The hexagonal [001] and [010] axes make an angle equal $\ensuremath{\alpha}\ensuremath{\approx}$ 90.10(1)${\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}$, while the angle between in-plane [100] and [010] axes equals $\ensuremath{\gamma}\ensuremath{\approx}$ 120.11(1)${\phantom{\rule{0.16em}{0ex}}}^{\ensuremath{\circ}}$. The monoclinic symmetry provides an approximate description of the crystal structure of the stacking faulted hcp-Co areas coexisting with fcc-Co areas.