Synchrotron X-ray Diffraction Research Articles

Investigating the Structural, Linear/Nonlinear Optical, and Photoluminescence Characteristics of CuO/ZnMn2O4 Nanocomposite for Physicochemical Applications

The structural, optical, and photoluminescence performance of CuO/ZnMn2O4 nanocomposites was investigated for optical applications. Nanocomposites of xCuO/(1-x)ZnMn2O4 (x; 0 to 0.7) were equipped using the sol-gel route. Synchrotron X-ray diffraction data were collected to examine the structural parameters. Rietveld refinement analysis reveals that the crystallite size decreases upon raising x from 0 to 0.7. High-resolution transmission electron microscopy revealed that the distribution of particle sizes demonstrates a relatively broad spectrum within the nanometer range. Raman spectroscopy investigations were applied to examine the structure’s vibrations. Scanning electron microscopy was used to examine the morphology of the formed samples. UV–vis spectrophotometry was applied to collect optical absorbance and reflectance measurements of the samples. Optical energy gap E g was determined utilizing the Kubelka-Munk method. The refractive index investigations were explored based on seven empirical formulas. The nonlinear optical parameters were explored as a function of CuO contents. The influence of CuO amount on the photoluminescence spectra was investigated. CIE chromaticity diagrams showed that all samples have various degrees of blue-violet colors. A significant improvement was achieved in the linear/nonlinear optical performance of nano ZnMn2O4 by forming CuO/ZnMn2O4 heterojunction, supporting the possible use of CuO/ZnMn2O4 nanocomposites in various optical applications.

Mechanochemically assisted synthesis, inversion degree and magnetization of spinel compounds across the (Zn,Mg)Fe2O4 system for flexible smart devices

Magnetic spinel oxides are multifunctional materials used or under consideration for a range of applications across electronics, communication technologies, remediation and health. They can also present high magnetostriction coefficients, and are being investigated as active inorganic fillers in polymer matrix composites for flexible sensors and actuators. However, state-of-the-art materials for these later applications are NiFe2O4- and CoFe2O4-based compositions, and it is necessary to find environmentally-friendly alternatives free of toxic elements that provide comparable responses, ideally biocompatible. This work presents a study of the spinel phases across the (Zn,Mg)Fe2O4 system and of their suitability to be used as magnetic component in hybrid composites. Spinel single phase materials with variable particle size across the submicron range, down to the verge of the nanoscale, have been obtained by mechanochemically assisted synthesis for five selected compositions spanning the whole ZnFe2O4-MgFe2O4 system. Evolution of the crystal lattice and inversion degree (amount of Fe3+ at tetrahedral site) has been obtained from Rietveld refinement of synchrotron X-ray diffraction data, and correlated with the development of magnetic ordering. Ferrimagnetic compositions are identified, among which Zn0.25Mg0.75Fe2O4 stands out for its magnetization characteristics comparable to NiFe2O4. This spinel compound is thus a promising environmentally-friendly candidate for flexible devices, in principle also biocompatible.

Structural phase transition in NH₄F under extreme pressure conditions.

Ammonium fluoride (NH₄F) exhibits a variety of crystalline phases depending on temperature and pressure. By employing Raman spectroscopy and synchrotron X-ray diffraction beyond megabar pressures (up to 140 GPa), we have here observed a novel dense solid phase of NH₄F, characterised by the tetragonal P4/nmm structure also observed in other ammonium halides under less extreme pressure conditions, typically a few GPa. Using detailed ab-initio calculations and reevaluating earlier theoretical models pertaining to other ammonium halides, we examine the microscopic mechanisms underlying the transition from the low-pressure cubic phase (P-43m) to the newly identified high-pressure tetragonal phase (P4/nmm). Notably, NH₄F exhibits distinctive properties compared to its counterparts, resulting in a significantly broader pressure range over which this transition unfolds, facilitating the identification of its various stages. Our analysis points to a synergistic interplay driving the transition to the P4/nmm phase, which we name phase VIII. At intermediate pressures (around 40 GPa), a displacive transition of fluorine ions initiates a tetragonal distortion of the cubic phase. Subsequently, at higher pressures (around 115 GPa), every second ammonium ion undergoes a rotational shift, adopting an anti-tetrahedral arrangement. This coupled effect orchestrates the transition process, leading to the formation of the tetragonal phase.

Numerical and experimental crack-tip cohesive zone laws with physics-informed neural networks

The cohesive zone law represents the constitutive traction versus separation response along the crack-tip process zone of a material, which bridges the microscopic fracture process to the macroscopic failure behavior. Elucidating the exact functional form of the cohesive zone law is a challenging inverse problem since it can only be inferred indirectly from the far-field in experiments. Here, we construct the full functional form of the cohesive traction and separation relationship along the fracture process zone from far-field stresses and displacements using a physics-informed neural network (PINN), which is constrained to satisfy the Maxwell-Betti's reciprocal theorem with a reciprocity gap to account for the plastically deforming background material. Our numerical studies simulating crack growth under small-scale yielding, mode I loading, show that the PINN is robust in inversely extracting the cohesive traction and separation distributions across a wide range of simulated cohesive zone shapes, even for those with sharp transitions in the traction-separation relationships. Using the far-field elastic strain and residual elastic strain measurements associated with a fatigue crack for a ZK60 magnesium alloy specimen from synchrotron X-ray diffraction experiments, we reconstruct the cohesive traction-separation relationship and observe distinct regimes corresponding to transitions in the micromechanical damage mechanisms.

In Situ Observation of Topotactic Linker Reorganization in the Aperiodic Metal-Organic Framework TRUMOF-1.

We use in situ synchrotron X-ray diffraction measurements to monitor the solvothermal crystallization mechanism of the aperiodic metal-organic framework TRUMOF-1. Following an initial incubation period, TRUMOF-1 forms as a metastable intermediate that subsequently transforms into an ordered product with triclinic crystal symmetry. We determine the structure of this ordered phase, which we call msw-TRUMOF-1, and show that it is related to TRUMOF-1 through topotactic reorganization of linker occupancies. Our results imply that the connectivity of TRUMOF-1 can be reorganized, as required for data storage and manipulation applications.

Ni4Nb1.8W0.1Ti0.1O9: Stabilization of the I-Type Ni4Nb2O9 Structure and First Magnetic Study of This Corundum-like Compound.

For the first time, we report on the structural and magnetic properties of a polycrystalline sample of Ni4Nb2O9 from I-type (Fdd2), obtained by the partial cosubstitution of Nb5+ by Ti4+ and W6+. The crystal structure is investigated by combining synchrotron X-ray, neutron, and electron diffraction at room temperature. This I-type structure is derived from the corundum-like Ni4Nb2O9 II-type (Pbcn) and is noncentrosymmetric and polar. The Ni-lattice is composed of the stacking of distorted honeycomb layers with double zigzag ribbons 60° disoriented from each other in two successive double layers. The connection between layers is ensured by the sharing of octahedra faces building (Nb,W,Ti)2O9, Ni2O9, and Ni3O12 units. This study shows how the disruption of the Nb2O6 units by smaller d0 cations impacts the structure, significantly modifying the Ni network and, thus, the magnetic properties. The latter were studied by dc- and ac-magnetic susceptibility, and the magnetic structure was solved by neutron powder diffraction. A ferrimagnetic behavior occurs below 68 K, followed by a re-entrant spin-glass-like behavior below ≈50 K.

Impact of Mn/Ni and Li/(Mn+Ni) ratios on phase equilibrium and electrochemical performance of the high voltage spinel LiNi0.5Mn1.5O4

LiNi0.5Mn1.5O4 (LNMO) emerges as a promising spinel-type positive electrode material for lithium-ion batteries (LIBs) due to its low cost and high operating voltage (4.8 V vs. Li+/Li), attributed to the Ni4+/Ni3+/Ni2+ redox couples, which contribute to high energy density, a crucial requirement for next-generation LIBs. In this study, we investigate the influence of Mn/Ni and Li/(Mn + Ni) ratios on the phase equilibrium and electrochemical performance of LNMO positive electrode materials. A series of 18 samples were synthesized using a two-stage solid-state method with varying Mn/Ni and Li/(Mn + Ni) ratios and annealing under different atmospheres. These synthesis conditions have major impact on the composition and level of purity of LNMO phases, as well as on the nature of the impurities themselves. Mn excess significantly enhances the electrochemical performance, with superior discharge capacity, coulombic efficiency, and capacity retention for the Mn-rich sample with Li/(Mn + Ni) = 0.50. A comprehensive structural analysis combining synchrotron X-ray and neutron powder diffraction gives an in-depth characterization of these samples with a clear differentiation between the global Mn content within samples and that within the LNMO phase.

Polytypism of incommensurately modulated structures of crystalline bromine upon molecular dissociation under high pressure

Polytypism of incommensurately modulated structures was hitherto unobserved. Here, it was found in solid bromine and iodine upon molecular dissociation under pressure up to 112 GPa. Single-crystal synchrotron x-ray diffraction in laser-heated diamond anvil cells revealed a number of allotropes of bromine and iodine, including polytypes of Br-IIIγ (Fmmm(00γ)s00) with γ varying within 0.18 to 0.3, coexisting at a given pressure. This finding opens a research area in the field of solid-solid phase transitions, disordered states of solid matter, and high-pressure structural studies. Published by the American Physical Society 2024

Reexamination of the structure of nanomineral opal-CT using synchrotron X-ray diffraction, transmission electron microscopy, X-ray scattering structure factor and pair distribution function analyses

Reexamination of the structure of nanomineral opal-CT using synchrotron X-ray diffraction, transmission electron microscopy, X-ray scattering structure factor and pair distribution function analyses

Monoclinic distortion and magnetic transitions in FeO under pressure and temperature

Fe1-xO, although chemically simple, possesses a complex structural and magnetic phase diagram. The crystal structures of Fe1-xO and its magnetic properties at extreme conditions are still a matter of debate. Here, we performed a systematic investigation on Fe0.94O up to 94 GPa and 1700 K using synchrotron X-ray diffraction and synchrotron Mössbauer source spectroscopy. We observe a transition of Fe0.94O to the monoclinic phases above 40 GPa and at high temperatures and use the group theory analysis of the observed phases to discuss their properties and their relation to the ambient pressure phases. The Mössbauer spectra of the rhombohedral and the room temperature monoclinic phase contain a component attributed to Fe2.5+, caused by the electron exchange between the Fe3+ defect and neighboring Fe2+ atoms. Our results present a structural and magnetic transitional pressure-temperature diagram of Fe1-xO and show the complex physicochemical properties of simple Fe1-xO binary oxide under extreme conditions.

Phosphorous and Nitrogen Dual-Doped Carbon as a Highly Efficient Electrocatalyst for Sodium-Oxygen Batteries.

Sodium-oxygen batteries have been regarded as promising energy storage devices due to their low overpotential and high energy density. Its applications, however, still face formidable challenges due to the lack of understanding about the influence of electrocatalysts on the discharge products. Here, a phosphorous and nitrogen dual-doped carbon (PNDC) based cathode is synthesized to increase the electrocatalytic activity and to stabilize the NaO2 superoxide nanoparticle discharge products, leading to enhanced cycling stability when compared to the nitrogen-doped carbon (NDC). The PNDC air cathode exhibits a low overpotential (0.36 V) and long cycling stability (120 cycles). The reversible formation/decomposition and stabilization of the NaO2 discharge products are clearly proven by in-situ synchrotron X-ray diffraction and ex-situ X-ray diffraction. Based on the density functional theory calculation, the PNDC has much stronger adsorption (-2.85 eV) for NaO2 than that of NDC (-1.80 eV), which could efficiently stabilize the NaO2 discharge products.

Polymorphism of pyrene on compression to 35 GPa in a diamond anvil cell

Structural studies of pyrene have been limited to below 2 GPa. Here, we report on investigations of pyrene up to ~35 GPa using in situ single-crystal synchrotron X-ray diffraction in diamond anvil cells and ab initio calculations. They reveal the phase transitions from pyrene-I to pyrene-II (0.7 GPa), and to the previously unreported pyrene-IV (2.7 GPa), and pyrene-V (7.3 GPa). The structure and bonding analysis shows that gradual compression results in continuous compaction of molecular packing, eventually leading to curvature of molecules, which has never been observed before. Large organic molecules exhibit unexpectedly high conformational flexibility preserving pyrene-V up to 35 GPa. Ab initio calculations suggest that the phases we found are thermodynamically metastable compared to pyrene-III previously reported at 0.3 and 0.5 GPa. Our study contributes to the fundamental understanding of the polymorphism of polycyclic aromatic hydrocarbons and calls for further theoretical exploration of their structure–property relationships.

Phase diagram of ruthenium characterized In Situ by synchrotron X-ray diffraction and Ab Initio simulations

In this work, an in situ characterization of the high-pressure and high-temperature phase diagram of ruthenium was carried out. This experiment was performed using a combination of laser-heated diamond anvil cell (LH-DAC) and X-ray diffraction (XRD) techniques at the beamline ID27 of the European Synchrotron Radiation Facility (ESRF). XRD patterns were collected in the range of 15 GPa to 110 GPa and from ambient temperature up to 6600 K. While the hcp-fcc transition, predicted to occur at elevated temperatures was not observed, this study has produced the first experimental observation of a solid–liquid phase transition of Ru at HP conditions. A P-V-T equation of state valid up to 100 GPa and 3000 K is reported.

In situ Synchrotron X-ray Metrology Boosted by Automated Data Analysis for Real-time Monitoring of Cathode Calcination.

Synchrotron X-ray-based in situ metrology is advantageous for monitoring the synthesis of battery materials, offering high throughput, high spatial and temporal resolution, and chemical sensitivity. However, the rapid generation of massive data poses a challenge to on-site, on-the-fly analysis needed for real-time process monitoring. Here, a weighted lagged cross-correlation (WLCC) similarity approach is presented for automated data analysis, which merges with in situ synchrotron X-ray diffraction metrology to monitor the calcination process of the archetypal nickel-based cathode, LiNiO2. The WLCC approach, incorporating variables that account for peak shifts and width changes associated with structural transformations, enables rapid extraction of phase progression within 10 seconds from tens of diffraction patterns. Details are captured, from initial precursors to intermediates and the final layered LiNiO2, providing information for agile on-site adjustments during experiments and complementing post hoc diffraction analysis by offering insights into early-stage phase nucleation and growth. Expanding this data-powered platform paves the way for real time calcination process monitoring and control, which is pivotal to quality control in battery cathode manufacturing.

Optical tunning of high-luminescent iodine-substituted CsPb2(Br0.84I0.16)5 under pressure

Metal halide compounds hold significant interest for optoelectronics, given their substantial potential for solar cells and light-emitting applications. Low-dimensional (0D, 1D, and 2D) metal halide perovskites or perovskite-like compounds exhibit various compositions with soft lattices and modular optical properties. Thus, the finding of new strategies to further improve such properties is a current research challenge. In this scenario, the 2D perovskite-like compound CsPb2Br5 has attracted attention due to its structural stability and favorable optical properties. This study presents the pressure-induced structural phase transitions of the iodine substituted CsPb2(Br0.84I0.16)5. This substitution induces strong green photoluminescence in single crystals at ambient conditions. High-pressure optical and synchrotron X-ray diffraction experiments reveal a tetragonal-tetragonal structural phase transitions around 1 GPa, while the photoluminescence emission is quenched around 2.7 GPa. Additionally, a new high-pressure orthorhombic phase is identified in the iodine-doped compound beyond 4.5 GPa. Further analysis of structural features prove that the pressure dependent photoluminescence behavior is directly related to structural distortions observed upon pressure increase.

Comprehensive analysis of ordering in CoCrNi and CrNi2 alloys

Chemical Short-Range Order (CSRO) has attracted recent attention from many researchers, creating intense debates about its impact on material properties. The challenges lie in confirming and quantifying CSRO, as its detection proves exceptionally demanding, contributing to conflicting data in the literature regarding its true effects on mechanical properties. Our work uses high-precision calorimetric data to unambiguously prove the existence and, coupled with atomistic simulations, quantify the type of CSRO. This methodology allows us to propose a mechanism for its formation and destruction based on the heat evolution during thermal analysis and facilitates a precise identification of local ordering in CoCrNi alloys. Samples of CoCrNi (Co33Cr33Ni33) and CrNi2 (Cr33Ni66) alloys are fabricated in varying ordered states, extensively characterized via synchrotron X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy. Samples with considerably different ordered states are submitted to tensile tests with in-situ synchrotron X-ray diffraction. We demonstrate, despite inducing varied CSRO levels in CoCrNi, no significant alterations in overall mechanical behavior emerge. However, the CrNi2 alloy, which undergoes long-range ordering, experiences significant shifts in yield strength, ultimate tensile stress and ductility.

The Non-Centrosymmetric Borate Hydride Sr4Ba3(BO3)3.83H2.5.

Sr4Ba3(BO3)3.83H2.5, as the second compound to combine borate and hydride ions, has been synthesized by a mechanochemical synthesis route. The structure has been elucidated by synchrotron X-ray and neutron diffraction and determined to crystallize in the non-centrosymmetric space group P63mc (186) with the cell parameters a=10.87762(15) Å and c=6.98061(11) Å. A detailed investigation of the compound by vibrational spectroscopy in combination with Density Functional Theory calculations reveals the disordered nature of the structure and proves the presence of both borate and hydride ions. Electronic band structure calculations predict a large band gap of 7.1 eV. Hydride states are predicted at the topmost valence band, which agrees well with earlier reported heteroanionic hydrides. We hereby were able to successfully apply previously synthetic and analytical schemes to introduce another member of the rare compounds that contain complex oxoanions simultaneously with hydride ions.

Evaluation of molecular interaction between intercellular lipid organization in human stratum corneum and terpenes using time-resolved synchrotron X-ray diffraction

The stratum corneum (SC) presents certain limitations for topical administration of medication, which can be overcome using penetration enhancers (PEs) such as terpene (TP). The SC is also crucial for maintaining the skin barrier and consists of two lamellar structures: the short periodicity phase (SPP) and long periodicity phase (LPP). In this study, we monitored changes in the X-ray diffraction peaks of the human SC, 30 min after TP application (neroridol, 1,8-cineol, and d-limonene). With the application of nerolidol, no significant changes were observed in the small-angle diffraction peak positions for the lamellar structure of SPP, but the integrated intensity decreased. On the contrary, when applying 1,8-cineole and d-limonene, a lower angle peak shift with broadening of the peak width of SPP diffraction peaks was observed for d-limonene than for 1,8-cineole, and the degree of peak shift and width broadening was greater for d-limonene than for 1,8-cineole. The diffraction peaks of LPP disappeared when 1,8-cineole and d-limonene were applied. These results indicate that the degree of interaction between the SC and TP differs depending on the molecular species, and d-limonene and 1,8-cineole exhibit penetration-enhancing via lamellar structure disruption of both SPP and LPP, immediately after application.

In situ synchrotron X-ray diffraction study: Phase evolution in transition zone of TiAl/Ti2AlNb dual alloy fabricated by laser-directed energy deposition

The phase evolution in the transition zone (TZ) of TiAl/Ti2AlNb dual alloy during laser-directed energy deposition (L-DED) process was investigated using in situ synchrotron radiation X-ray diffraction. The as-solidified microstructure of the TZ forms through the following phase transitions: Liquid→ Liquid + β/B2 →β/B2→ β/B2 + α2. Thermal cycles promote the β/B2 to α2 phase transition with the α2 phase precipitates from the (011) plane of the β/B2 matrix during this transition. The phase transition sequence of the TZ during the first thermal cycle is: β/B2 + α2 → β/B2 → β/B2 + α2. The second thermal cycle leads to a partial transformation of β/B2 phase to α2 phase. The TZ experiences no phase transition from the third thermal cycle. This study provides a comprehensive understanding of the phase formation mechanism in the TZ of L-DEDed TiAl/Ti2AlNb dual alloys.

Effect of zirconium addition on microstructural characteristics and nano-mechanical properties of P9 steel

Micro-alloying in steels has significant effects on microstructure and its properties. The main objective of the work is to understand the influence of zirconium (Zr) addition to P9 ferritic/martensitic (F/M) steel on phase stability, microstructure, and nanomechanical properties. The alloy compositions in this study were designed using thermodynamic calculations, based on which steels with Zr concentration in the range of 0.05–2 wt.% were synthesized using vacuum arc melting. The cast alloy was subjected to thermo-mechanical treatments followed by austenitization and tempering treatments. Zr concentration of the steel was found to influence the nature of secondary phases formed, which were quantified through detailed synchrotron X-ray diffraction (XRD) analysis and also characterised extensively using electron microscopy techniques. Detailed structural analysis of the Fe23Zr6 phase using aberration corrected transmission electron microscopy is reported for the first time. The nano-mechanical properties of the heat-treated steels were evaluated using instrumented indentation tests at room temperature with a sphero-conical indenter. A systematic variation in hardness and yield strength with Zr content of P9 steel was observed, which is correlated to the microstructural changes. The P9 F/M steel with optimum concentration of Zr, with better mechanical properties is proposed through this structure-property correlation study.