Search Results (142)

Solid-state studies evaluating intermolecular geometries in methylated nucleobases are not extensively explored. In the course of the present study, we have solved the crystal structures of 1-, 3- and 7-methylated adenines and guanines, including the monohydrate and sesquihydrate forms of 3-methyladenine and 3-methylguanine, respectively, by means of single-crystal X-ray diffraction and synchrotron/laboratory X-ray powder diffraction (XRPD). In situ high temperature XRPD experiments, coupled with differential thermal analysis/thermogravimetry (DTA/TG) measurements, allowed for monitoring crystallographic changes after water removal of N3-methylated compounds, and the discovery of a high temperature polymorph in the case of 3-methyladenine. Our findings indicate that H-bonding schemes describe ribbon planar motifs of molecules in the majority of cases, or linear double-bonded strands of molecules in a few cases. π-π stacking interactions were compared with existing findings of theoretical calculations and existing crystallographic data, showing how N-methylated purine bases follow the trend predicted by Hunter and Sanders, 1990. The present study provides the first systematic experimental insights into the solid state of the presented compounds. Full article

Mechanical properties of lead-free hybrid perovskites have attracted growing interest because of their significance in future eco-friendly optoelectronic applications. However, there are very limited studies about the intrinsic elastic properties and high-pressure structural evolution of hybrid perovskites, and the fundamental structure–mechanical property relationships are insufficiently understood. Here, we report the elastic behavior of a three-dimensional (3D) hybrid organic–inorganic perovskite, (DABCO)RbBr₃ (DABCO = triethylenediammonium), and confirm the processability through processing with chiral metasurfaces and the generation of circular dichroism. Our in situ high-pressure synchrotron X-ray diffraction experiments demonstrate that this crystal does not start to amorphize until 2.3 GPa. Density functional theory calculations reveal that its E, G and v range between 20.73 and 27.93 GPa, 8.21 and 11.62 GPa and 0.18–0.39, respectively. Additionally, due to the low elastic moduli and polar crystal structure, we fabricate a device of (DABCO)RbBr₃ composite film, which shows favorable performance for piezoelectric energy harvesting. This work utilizes (DABCO)RbBr₃ to open up new avenues for applications in manufacturing and energy harvesting. Full article

The effect of palladium addition to a hybrid Co/SiO₂ + HZSM-5 + Al₂O₃ catalyst on the combined Fischer–Tropsch (FT) synthesis and hydrocarbon hydroconversion process was studied. Catalysts with a Pd content of 0.075–0.3 wt.% were characterized by a complex of physicochemical methods, including synchrotron radiation X-ray diffraction (SR-XRD), temperature-programmed reduction with hydrogen (H₂-TPR), temperature-programmed desorption of hydrogen with oxygen titration (H₂-TPD/O₂ titration), IR spectroscopy of adsorbed pyridine, and STEM-EDX analysis. It was found that the addition of palladium decreases the cobalt oxide reduction temperature due to interphase hydrogen transfer. Tests in hydrocarbon synthesis at 240–250 °C, a pressure of 2 MPa, and an H₂/CO ratio of 2 showed that the sample with 0.15% Pd exhibits the highest selectivity for C₅+ hydrocarbons (66.8% at 240 °C) and stability for 150 h. Analysis of the synthesis products revealed a fivefold decrease in the proportion of alkenes and an increase in isoalkanes with increasing Pd concentration. This effect enables the in situ hydroprocessing of primary FT products in a single reactor. The results demonstrate that the targeted introduction of palladium into the hybrid system is an effective strategy for regulating its functionality, allowing for the one-stage production of high-quality fuels with a controlled hydrocarbon composition from syngas. Full article

A K-rich nepheline sample from Nephton, Canada, with a composition of (K_1.83☐_0.17)Na_6.08[Al_7.98Si_8.04O₃₂], was studied using in situ synchrotron high-temperature (T) powder X-ray diffraction (XRD) data and Rietveld structure refinement from 25 to 926 °C on heating and cooling on a fine-temperature (T) scale. The average structure was refined in space group P6₃. The sample contains satellite reflections indicative of a modulated, incommensurate superstructure. The Al and Si atoms are ordered differently in powdered samples from the same large crystal. The nepheline structure contains domains in which the Al and Si atoms are highly ordered, but the average structure of the domains gives rise to a partially disordered Al-Si distribution. On heating to 926 °C, the Al and Si atoms acquire a fully ordered Al-Si distribution, which is quenched on cooling to room T. The complete Al-Si order is deduced from the average <T-O>{4} distances. Satellite reflections associated with positional disorder of the O1 atom was not observed. A small amount (9%) of vacancies, ☐, occur on the K site. Disorder of K–☐ occurs at 320 °C where some satellite reflections disappear. Some satellite reflections associated with Al-Si order remain to 926 °C. Re-order of K–☐ occurs at 377 °C on cooling, and the associated satellite reflections reappear. Full article

The spontaneous formation and stability of a protective passive film on a metal surface are crucial for the metal material’s corrosion resistance during its service life. Passive films have been extensively studied, and our understanding of passive films has been significantly improved with the development of advanced analytical techniques. Modern synchrotron X-ray sources offer unprecedented possibilities for detailed analyses of passive films and for in situ and operando studies of passive films in both gaseous/aqueous environments, as well as in electrochemical environments. This mini review presents a short summary of recent studies on passive films, mainly focusing on stainless steels and nickel-base alloys, which utilize state-of-the-art synchrotron X-ray techniques, particularly X-ray photoelectron spectroscopy (XPS), often in combination with other synchrotron techniques such as X-ray adsorption, diffraction, reflectivity, and fluorescence. These reports demonstrate that synchrotron-based techniques greatly improve probing sensitivity and spatial resolution, enabling in situ and operando studies of passive films at solid–liquid interfaces. These studies reveal changes in the passive film and underlying alloy layer, highlighting the important role of hydroxides, as well as the inhomogeneity in passive films associated with the complex microstructures in advanced industrial alloys. Full article

Objective: The aim of this work is to improve the understanding of the mechanisms underlying the polymorphic transformations of pharmaceutical materials during milling. Elucidating these mechanisms is essential for controlling the polymorphism of active pharmaceutical ingredients and thereby improving their performance. Method: The structural evolution of various pharmaceutical compounds (sulfamerazine, glycine, mannitol, and famotidine) upon milling was followed using ex situ laboratory X-ray diffraction and in situ synchrotron measurements, complemented by DSC analyses. Results: For each compound, the kinetics of the polymorphic transformation was found to be sigmoidal and the presence of an intermediate amorphous phase during the transition from the initial to the final polymorphic form was also identified. Conclusions: The kinetic data obtained for sulfamerazine and glycine, together with the detection of an amorphous intermediate during the transformations of mannitol and famotidine, support the conclusion that milling-induced polymorphic transformations in pharmaceutical materials generally proceed via an amorphization–recrystallization mechanism. Full article

Decarbonizing the steel industry relies on a transition from carbon-intensive blast furnace technology to scrap-based secondary steelmaking using electric arc furnaces. This transition introduces tramp elements and leads to their gradual accumulation, which can significantly influence the functional properties of chemically sensitive steel grades. In this study, the combined impact of several tramp element contents on the phase transformations, microstructure and mechanical properties of a 0.3 wt.% C low-alloyed steel was investigated. To achieve this, a reference alloy was produced using the conventional blast furnace production route. It was then compared with two trial alloys, which contained intentionally elevated levels of tramp elements and were produced through an experimental melting route designed to simulate scrap-based electric arc furnace production. The experimental characterization included light optical and electron microscopy, electron back-scatter diffraction, in situ synchrotron high-energy X-ray diffraction coupled with dilatometry, and Vickers hardness testing. The results revealed the formation of displacive transformation products such as martensite and showed that austenite was retained in the tramp element-enriched trial alloys. The combination of solid solution strengthening and martensitic transformation led to a gradual increase in hardness. These findings underscore the critical role of tramp elements in determining the microstructural and mechanical response of steels produced from scrap-based feedstock. Full article

A fine-grained nepheline sample from Egan Chutes, Ontario, with the chemical composition (K_1.32▯_0.68)(Na_6.05Ca_0.22)[Al_7.77Si_8.21O₃₂], where ▯ represents vacancies, was studied through in situ synchrotron powder X-ray diffraction (XRD) data and Rietveld structure refinement from 26 to 900 °C on heating and cooling. The average structure was refined in the space group P6₃. The satellite reflections in nepheline give rise to order–disorder transitions. The average <Al,Si-O>{4} distances in nepheline indicate a partially ordered Al-Si distribution, especially in the Al2 and Si2 sites at room T before heating. The nepheline structure shows that except for the positional disorder of the O1 oxygen atom, the other atoms are well defined and contain no unusual features. Vacancies, ▯, occur at the K site. Different satellite (s) reflections arise from (1) positional order of the O1 atoms to 299 °C (s1 disappears), (2) K-▯ order to 486 °C (s2 and s3 disappear), and (3) some Al-Si order 900 °C, where some satellite reflections are present. Complete Al-Si order is obtained at room T on cooling. Full article

Solid-state lithium batteries (SSLBs) have emerged as a promising alternative to conventional lithium-ion systems due to their superior safety profile, higher energy density, and potential compatibility with lithium metal anodes. However, a major challenge hindering their widespread deployment is the formation and growth of lithium dendrites, which compromise both performance and safety. This review provides a comprehensive and structured overview of recent advances in dendrite suppression strategies, with special emphasis on the role played by the nature of the solid electrolyte. In particular, we examine suppression mechanisms and material innovations within the three main classes of solid electrolytes: sulfide-based, oxide-based, and polymer-based systems. Each electrolyte class presents distinct advantages and challenges in relation to dendrite behavior. Sulfide electrolytes, known for their high ionic conductivity and good interfacial wettability, suffer from poor mechanical strength and chemical instability. Oxide electrolytes exhibit excellent electrochemical stability and mechanical rigidity but often face high interfacial resistance. Polymer electrolytes, while mechanically flexible and easy to process, generally have lower ionic conductivity and limited thermal stability. This review discusses how these intrinsic properties influence dendrite nucleation and propagation, including the role of interfacial stress, grain boundaries, void formation, and electrochemical heterogeneity. To mitigate dendrite formation, we explore a variety of strategies including interfacial engineering (e.g., the use of artificial interlayers, surface coatings, and chemical additives), mechanical reinforcement (e.g., incorporation of nanostructured or gradient architectures, pressure modulation, and self-healing materials), and modifications of the solid electrolyte and electrode structure. Additionally, we highlight the critical role of advanced characterization techniques—such as in situ electron microscopy, synchrotron-based X-ray diffraction, vibrational spectroscopy, and nuclear magnetic resonance (NMR)—for elucidating dendrite formation mechanisms and evaluating the effectiveness of suppression strategies in real time. By integrating recent experimental and theoretical insights across multiple disciplines, this review identifies key limitations in current approaches and outlines emerging research directions. These include the design of multifunctional interphases, hybrid electrolytes, and real-time diagnostic tools aimed at enabling the development of reliable, scalable, and dendrite-free SSLBs suitable for practical applications in next-generation energy storage. Full article

Post-processing plays a vital role in the determination of the final structures and properties of oriented materials. As a sustainable candidate of oil-based poly(ethylene terephthalate), biobased poly(ethylene 2,5-furandicarboxylate) (PEF) reflects great promise in green fiber, film, and packaging applications, but it undergoes poor stress-induced crystallization (SIC) under tensile deformation, necessitating a post-processing technique to improve its crystallinity and stability. Here, the structural evolution of pre-stretched PEF under post heating after uniaxial deformation was monitored by online synchrotron X-ray diffraction/scattering, differential scanning calorimetry, and ex situ infrared spectroscopy. The results delineate the significantly enhanced crystallization of pre-deformed PEF that happened far below its cold crystallization temperature. Through the isochronous analyses of the temperature-dependent evolution of mechanical response, the mesophase, crystal structure, orientation factor, chain conformation, and interchain ═C−H···O═C hydrogen bonding, the molecular mechanisms of microstructural transition and oriented crystallization of pre-drawn PEF under post heating were clarified. This research can enhance the understanding of PEF crystallization in an oriented state and provide guidelines on the structural design and technical control for processing high-performance PEF-based materials. Full article

A common route for the synthesis of molybdenum nitrides is through the temperature-programmed reaction of molybdenum oxides with NH₃, or ammonolysis. In this work, the role of precursor phase, gas phase chemistry (impact of H₂O), and temperature profile on the reaction outcome (700 °C) was examined, which resulted in varying amounts of MoO₂, H₂MoO₅, and the nitride phases—cubic γ (nominally Mo₂N) and hexagonal δ (nominally MoN). The phase fraction of the δ phase increased with precursor in the sequence MoO₂ > MoO₃ > H₂MoO₅. Steam in the reaction gas also favored the production of δ over γ, but with too much steam, MoO₂ was obtained in the product. Synthesis conditions for obtaining nearly phase-pure δ were identified: MoO₂ as the precursor, 2% H₂O in the gas stream, and a moderate heating rate (3 °C/min). In situ X-ray diffraction provided insights into the reaction pathway. Extensive physico-chemical analysis of the δ phase, including synchrotron X-ray and neutron diffraction, electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and prompt gamma activation analysis, revealed its stoichiometry to be MoO_0.108(8)N_0.892(8)H_0.012(5), indicating non-trivial oxygen incorporation. The presence of N/O ordering and an impurity phase Mo₅N₆ were also revealed, detectable only by neutron diffraction. Notably, a computationally predicted MoON phase (doi: 10.1103/PhysRevLett.123.236402), of interest due to its potential to display a metal-insulator transition, did not appear under any reaction condition examined. Full article

The crystal chemistry of syngenite K₂Ca(SO₄)₂·H₂O and its lattice dynamics under low and high temperatures and high pressure were studied. The research facilities used include in situ temperature variable single-crystal (SCXRD) and powder X-ray diffraction (PXRD), in situ PXRD under high pressure (HP), thermal analysis (DSC and TGA), and Raman spectroscopy. For the first time, a detailed study of syngenite in the range of negative temperatures down to −180 °C was performed. It indicates the absence of phase transitions in the range from −180 °C to 240 °C. The largest expansion of the structure is observed along the α₁₁, which is consistent with the layered architecture. The minor thermal expansion along the α₂₂ is observed in the plane of the [Ca(SO₄)₂]²⁻ layer, formed by the bassanite-type chains. The study of powder samples at HP up to 20 GPa was carried out using synchrotron radiation and a diamond anvil cell. The phase transition is registered at 10 GPa. After the decompression, the syngenite post-phase becomes partially amorphized. Full article

A 3D-printable, ARDUINO-based multipurpose X-ray stage of compact dimensions enabling in situ electric field and temperature-dependent measurements is put into practice and tested here. It can be routinely applied in combination with a technique of structural characterization of materials. Using high-performance X-ray laboratory equipment, two investigations were conducted to illustrate the device’s performance. The lattice characteristics and microstructure evolution of piezoelectric ceramics of barium titanate, BaTiO₃ (BT), and barium calcium zirconate titanate, with compositions of (Ba_0.92Ca_0.08) (Ti_0.95Zr_0.05)O₃ (BC8TZ5), were studied as a function of the applied electric field and temperature. The X-ray stage is amenable as an off-the-shelf device for a diffraction line in a synchrotron. It provides valuable information for poling piezoceramics and subsequent optimization of their performance. Full article

A concept of a high throughput, user-friendly, versatile bending magnet beamline at the fourth-generation synchrotron radiation facility SKIF, currently being constructed in Koltsovo (a science town near Novosibirsk, Russia), is proposed. The beamline is designed to implement the conventional and most demanded synchrotron techniques: XAS (X-ray absorption spectroscopy); XRD (X-ray diffraction), both powder and single-crystal, including the in situ mode; and XRF (X-ray fluorescence analysis). The beamline is conceived to be as simple as possible, but it is multifunctional, being a base beamline for the education and training of students, future synchrotron users, and beamline scientists. A number of potential beamline optical layouts are modeled in the XRT (XRayTracer) program package. The resulting beam characteristics at the sample position are discussed. A monochromator model is proposed. Surface distortions and their influence on the rocking curve of the Si111 crystal due to incoming heat loads are realistically modeled. The optimum design of the station is defined. The range of crystalline objects that are possible to be studied at the proposed station is emphasized, and future perspectives are outlined. Full article

The Plasma Immersion Ion Implantation (PIII) nitriding was used to form a modified layer rich in expanded austenite (γ_N) and expanded ferrite (α_N) phases in super duplex steel. The thermal stability of these phases was investigated through the in situ synchrotron X-ray diffraction. All the surfaces were analyzed by SEM, EDS, and nanoindentation. During the heating stage of the thermal treatments, the crystalline structure of the γ_N phase expanded thermally up to a temperature of 350 °C and, above this temperature, a reduction in the lattice parameter was observed due to the diffusion of nitrogen into the substrate. During the isothermal heating, the gradual diffusion of nitrogen continued and the lattice parameter of the γ_N phase decreased. Increasing the treatment temperature from 450 °C to 550 °C, a greater reduction in the lattice parameter of the γ_N phase occured and the peaks related to the CrN, α, and α_N phases became more evident in the diffractograms. This phenomenon is associated with the decomposition of the γ_N phase into CrN + α + α_N. After the heat treatments, the thickness of the modified layers increased and the hardness values close to the surface decreased, according to the diffusion of the nitrogen to the substrate. Full article