Synchrotron Powder Diffraction Research Articles

UoC‐2: A Fluorinated Derivative of the Robust Metal‐Organic Framework MFM‐300

By solvothermal reactions of fluoro substituted biphenyl‐3,3’,5,5’‐tetracarboxylic acids (H4BPTC) with the respective metal salts, four new MOFs with the MFM‐300 topology were synthesized, namely [MIII2(OH)2(L)] with MIII = Ga3+, In3+ and L = 4‐mF‐BPTC4‐ and 4,4’‐dF‐BPTC4‐. Three of them were refined from X‐ray single crystal diffraction data (I4122, Z = 4), [Ga2(OH)2(4,4’‐dF‐BPTC)] was confirmed by Le Bail fits based on synchrotron powder diffraction data. To the best of our knowledge, these four compounds represent the very first examples of MFM‐300 type MOFs with a substituted BPTC4‐ linker. With increasing fluorination of the linker, the thermal stability decreases, as the decarboxylation of the linker is facilitated. On the other hand, the gas uptake is enhanced significantly. E.g. the CO2 uptake (273 K, 1 bar) increases from 124 cm3/g for [Ga2(OH)2(4‐mF‐BPTC)] to 136 cm3/g for [Ga2(OH)2(4,4’‐dF‐BPTC)]. Surprisingly, the exact determination of specific surface areas (SBET) turned out to be difficult. It is supposed that due to transient open metal sites, complete removal of solvent molecules (DMF, acetone) is not always possible before degradation of the framework starts.

Black TiO2 and Oxygen Vacancies: Unraveling the Role in the Thermal Anatase-to-Rutile Transformation

Understanding the role of oxygen vacancies in the phase transformation of metal oxide nanomaterials is fundamental to design more efficient opto-electronic devices for a variety of applications, including sensing, spintronics, photocatalysis, and photo-electrochemistry. However, the structural mechanisms behind the phase transformation in reducible oxides remain poorly described. Here, we compare P25 and black TiO2 during the thermal anatase-to-rutile transformation using in situ synchrotron powder diffraction. The precise measurement of the phase fractions, unit cell parameters, and Ti-O bond sheds light on the phase transformation dynamics. Notably, we observe distinct temperature-dependent shifts in the relative phase fractions of anatase and rutile in both materials highlighting the role of the oxygen vacancy in promoting the phase transformation. We employ bond valence concepts for structural modeling, revealing unique trends in temperature evolution of Ti-O distances of black rutile, confirming that this TiO2 phase is preferentially reduced over anatase. These findings not only enhance our understanding of phase transitions in TiO2 but also open new ways for the design of advanced photocatalytic materials through targeted phase control.

Na2C3O2: Die erste kristalline Verbindung mit dem ungewöhnlichen −C≡C−COO−‐Anion

AbstractDurch die Reaktion von Natrium‐Elektrid oder NaC2H in flüssigem Ammoniak mit dem wasserfreien Natriumsalz der Propargylsäure, Na(OOC−C≡C−H), konnten kristalline Pulver von Na2C3O2 erhalten werden. Die Strukturanalyse, basierend auf Synchrotronpulverdiffraktionsdaten, zeigte, dass Na2C3O2 in einer monoklinen Elementarzelle (I2/a, Z=4) kristallisiert. Diese weist das ungewöhnliche Y‐förmige −C≡C−COO− Anion auf, welches bis zu diesem Zeitpunkt nicht in einer kristallinen Verbindung bekannt war. IR‐/Raman‐ sowie Festkörper‐NMR‐spektroskopische Untersuchungen, unterstützt durch DFT‐basierte ab initio Rechnungen, bestätigen diese Ergebnisse. Die Reaktion mit Natrium‐Elektrid führte zu einem Produkt mit höherer Kristallinität. Zusätzlich erfolgte jedoch aufgrund von Zersetzung und Polymerisation des Na2C3O2 die Bildung eines Nebenprodukts. In der Umsetzung mit NaC2H wurde dieses Nebenprodukt nicht beobachtet, sodass diese Reaktion die mildere Metallierungsroute darstellt. Das Produkt dieser Reaktion weist jedoch eine geringere Kristallinität auf.

Na2C3O2: The First Crystalline Compound with the Elusive -C≡C-COO- Anion.

By reaction of sodium electride or NaC2H with the anhydrous sodium salt of propiolic acid, Na(OOC-C≡C-H), in liquid ammonia crystalline powders of Na2C3O2 were obtained. The structure analysis based on synchrotron powder diffraction data revealed that Na2C3O2 crystallizes in a monoclinic unit cell (I2/a, Z=4) exhibiting the elusive Y-shaped -C≡C-COO- anion, which is unprecedented in a crystalline compound up to now. IR/Raman and solid-state NMR spectroscopic investigations with assignments supported by DFT-based ab initio calculations confirm this finding. Reaction with sodium electride led to a higher crystallinity of the product, but additionally a by-product apparently due to decomposition and polymerization of Na2C3O2 was formed. No such by-product was observed in the reaction with NaC2H, which turned out to be a milder metalation route. However, the product of the latter reaction is less crystalline.

Mechanochemically-induced glass formation from two-dimensional hybrid organic-inorganic perovskites.

Hybrid organic-inorganic perovskites (HOIPs) occupy a prominent position in the field of materials chemistry due to their attractive optoelectronic properties. While extensive work has been done on the crystalline materials over the past decades, the newly reported glasses formed from HOIPs open up a new avenue for perovskite research with their unique structures and functionalities. Melt-quenching is the predominant route to glass formation; however, the absence of a stable liquid state prior to thermal decomposition precludes this method for most HOIPs. In this work, we describe the first mechanochemically-induced crystal-glass transformation of HOIPs as a rapid, green and efficient approach for producing glasses. The amorphous phase was formed from the crystalline phase within 10 minutes of ball-milling, and exhibited glass transition behaviour as evidenced by thermal analysis techniques. Time-resolved in situ ball-milling with synchrotron powder diffraction was employed to study the microstructural evolution of amorphisation, which showed that the crystallite size reaches a comminution limit before the amorphisation process is complete, indicating that energy may be further accumulated as crystal defects. Total scattering experiments revealed the limited short-range order of amorphous HOIPs, and their optical properties were studied by ultraviolet-visible (UV-vis) spectroscopy and photoluminescence (PL) spectroscopy.

Exceptional magnetic and magnetoelastic behavior of rare-earth non-centrosymmetric Sm7Pd3

Magnetic compounds possessing an intrinsic combination of near-zero magnetization with high magnetic anisotropy are highly desirable for spinronic applications and memory recording. A comprehensive study of Sm7Pd3 binary compound uncovered a unique combination of strong magnetoelastic behavior, very low net magnetization, and exceptionally high magnetic coercivity. The temperature-dependent X-ray synchrotron powder diffraction study indicates the abrupt changes in the compound's lattice parameters at the magnetic ordering temperature of TC=169 K, although the crystal structure remains non-centrosymmetric hexagonal Th7Fe3-type down to 6 K. Density functional theory calculations confirm high intrinsic magnetocrystalline anisotropy of Sm7Pd3, which explains the extremely large coercivity of the polycrystalline sample, up to Hcr = 130 kOe at 2 K. This discovery brings to life a novel class of highly anisotropic materials that are distinctly different from known spintronic materials, making them interesting future systems for magnetic memory research.

Monitoring the Synthesis of Nickel-Poor and Nickel-Rich Oxide Cathode Materials for Lithium-Ion Batteries with Synchrotron-Based XRD and Sxas

The synthesis of Ni-poor (NCM111, LiNi1/3Co1/3Mn1/3O2) and Ni-rich (NCM811 LiNi0.8Co0.1Mn0.1O2) lithium transition metal oxides (space group R-3m ) from hydroxide precursors (Ni1/3Co1/3Mn1/3(OH)2, Ni0.8Co0.1Mn0.1(OH)2) are investigated with in situ synchrotron powder diffraction (SXPD) and near edge x-ray absorption fine structure spectroscopy (NEXAFS). The development of the layered structure of these two cathode materials proceeds via two utterly different reaction mechanisms. While the synthesis of NCM811 involves a rock salt-type intermediate phase, NCM111 reveals a layered structure throughout the entire synthesis. Moreover, the necessity and the impact of a pre-annealing step and a high-temperature holding step are discussed.

Battery Thermalization for Operando Synchrotron Powder Diffraction: Application to the Ca-TiS2 System

Characterizing electrode materials and understanding its behavior during redox process is a key factor for battery improvement. In Situ techniques on Operando batteries are of particular interest since they do not only probe the material during the electrochemical process but avoid its hazardous and tedious extraction and transfer under inert atmosphere from an electrochemical cell to e.g. capillaries, to perform Ex Situ data collection. Synchrotron based techniques –absorption and diffraction – together with improved detectors, are now intensively used in such In Situ studies on Operando batteries since they allow fast and real time data acquisition during the electrochemical, ion (des-)insertion, process. So far most In Situ X-ray powder diffraction studies on Operando batteries are performed at room temperature using either coin cells or so called Leriche cells [1] (pouch cells, despite widely used for spectroscopy, are generally not favored for diffraction since the container material produce additional Bragg peaks). At ALBA we slightly modified both types of cells: Leriche type and more widespread used CR2032-type coin cells so as to perform data collection in temperature range -10° – 100° C. (see picture)Both types of cell have been used to study the intercalation of calcium in TiS2, previously determined by Ex Situ powder diffraction [2]. We managed to collect powder patterns operando at 60°C, 45°C and room temperature. (Des-)Insertion of solvated Ca2+ in TiS2 was favoured by temperature, its signature being the appearance of a new phase with a first diffraction peak at very low angles (~17.7 Å in terms of d-spacing). The process was found to be solvent dependent and reversible upon oxidation, which differs from Li cells where a similar process was observed.[3]Either of these thermalized cells can be used at CELLS-ALBA synchrotron for Power Diffraction on BL04-MSPD beamline or hard X-ray Absorption Spectroscopy (XANES/EXAFS) on BL22-CLEASS, and since 2023 also using simultaneous Powder Diffraction and hard X-ray Absorption Spectroscopy in BL16-NOTOS beamline. Moreover, the Leriche setup is also designed to fit for a use in laboratory X-ray diffractometers, in both reflection and transmission. Leriche et al. (2010). J. Electrochem. Soc., 157(5), A606-A610.Tchitchekova et al (2018). Chem. Mater 30, 847−856Houdeville et al. (2021). J. Electrochem. Soc., 168, 030514 Figure 1

Experimental electron density distribution of KZnB3O6 constructed by maximum-entropy method

The dynamic charge density of KZnB3O6, which contains edge-sharing BO4 units, has been characterized using laboratory and synchrotron X-ray diffraction techniques. The experimental electron density distribution (EDD) was constructed using the maximum-entropy method (MEM) from single crystal diffraction data obtained at 81 and 298 K. Additionally, MEM-based pattern fitting (MPF) method was employed to refine the synchrotron powder diffraction data obtained at 100 K. Both the room-temperature single crystal diffraction data and the cryogenic synchrotron powder diffraction data reveal an intriguing phenomenon: the edge-shared B2O2 ring exhibits a significant charge density accumulation between the O atoms. Further analysis of high-quality single crystal diffraction data collected at 81 K, with both high resolution and large signal-to-noise ratio, reveals no direct O–O bonding within the B2O2 ring. The experimental EDD of KZnB3O6 obtained aligns with the results obtained from ab-initio calculations. Our work underscores the importance of obtaining high-quality experimental data to accurately determine EDDs.

Structure and magnetism of AlCoCrCuFeNi high-entropy alloy

We report on the investigation of magnetic and structural properties of AlCoCrCuFeNi, which is known to crystallize in a dual phase solid solution: the face-centred cubic (FCC) or the body-centred cubic (BCC). The results of neutron (NPD) and synchrotron powder diffraction (SXRD) allow to partially resolve magnetic information coming from BCC and FCC phases, which is impossible in the bulk magnetic measurements. Electron diffraction (PED) revealed that AlCoCrCuFeNi forms dendritic microstructure with the Cu-rich FCC phase and the Ni-rich BCC phase. Lattice parameters obtained from PED method are in good agreement with parameters obtained after refinement on the basis of powder X-ray diffraction measurements. The local crystal and electronic structure around Co was studied using Co K X-ray Absorption Spectroscopy (XAS). The magnetic measurements show that AlCoCrCuFeNi reveal a ferromagnetic transition at about 330 K and displays magnetic hysteresis loop at the room temperature. Results from NPD suggest that the magnetic moment is mostly located in the BCC subsystem. The alloy shows soft magnetic properties. Saturated magnetizations (Ms), remanence ratio (Mr/Ms) and coercivity (Hc) of the cast are estimated to be 45.10 emu/g, 5.1 % and 56 Oe at 300 K, respectively. Finally, the BCC-FCC phase transformation up to 673 K (400 °C) was investigated using temperature dependent NPD, where a possible second BCC phase was identified.

Hydrogen bonding patterns and C-H...π interactions in the structure of the antiparkinsonian drug (R)-rasagiline mesylate determined using laboratory and synchrotron X-ray powder diffraction data.

The structure of (R)-rasagiline mesylate [(R)-RasH+·Mes-], an active pharmaceutical ingredient used to treat Parkinson's disease, is presented. The structure was determined from laboratory and synchrotron powder diffraction data, refined using the Rietveld method, and validated and optimized using dispersion-corrected DFT calculations. The unit-cell parameters obtained in both experiments are in good agreement and the refinement with both datasets converged to good agreement factors. The final parameters obtained from laboratory data were a = 5.4905 (8), b = 6.536 (2), c = 38.953 (3) Å, V = 1398.0 (4) Å3 and from synchrotron powder data were a = 5.487530 (10) Å, b = 6.528939 (12) Å, c = 38.94313 (9) Å, V = 1395.245 (5) Å3 with Z = 4 and space group P212121. Preferred orientation was properly accounted for using the synchrotron radiation data, leading to a March-Dollase parameter of 1.140 (1) instead of the 0.642 (1) value obtained from laboratory data. In the structure, (R)-RasH+ moieties form layers parallel to the ab plane connected by mesylate ions through N-H...O and C-H...O hydrogen bonds. These layers stack along the c axis and are further connected by C-H...π interactions. Hirshfeld surface analysis and fingerprint plot calculations indicate that the main interactions are: H...H (50.9%), H...C/C...H (27.1%) and H...O/O...H (21.1%).

Cesium Oxo-fluoro-aluminates in the CsF-Al2O3 System: Synthesis and Structural Characterization.

In an experiment combining various approaches, a precise examination of a portion of the phase diagram of a CsF-Al2O3 system was carried out up to 40 mol% Al2O3. CsF-Al2O3 solidified mixtures have been investigated using high-field solid-state NMR (133Cs, 27Al, and 19F) spectroscopy and X-ray powder diffraction over a broad range of compositions with synchrotron powder diffraction and Rietveld analysis. A new cesium oxo-fluoro-aluminate, Cs2Al2O3F2, was discovered, prepared, and structurally analyzed by synchrotron diffraction analysis. In addition to Cs2Al2O3F2, we have synthesized the following pure compounds in order to aid in the interpretation of NMR spectra of the solidified samples: CsAlF4, Cs3AlF6, and CsAlO2.

Phase transitions of a Ca–valproic acid complex followed by single-crystal and synchrotron powder diffraction techniques

Phase transitions of a Ca–valproic acid complex followed by single-crystal and synchrotron powder diffraction techniques

Evidence of structural modulations induced by a charge density wave transition in orthorhombic Sm2Ru3Ge5

We present the electrical resistivity and x-ray diffraction characterization of ternary Sm2Ru3Ge5 compound with orthorhombic U2Co3Si5-type structure. In agreement with the earlier observations, our electrical resistivity measurements revealed the presence of three anomalies, viz. 239.3, 27.8 and 7 K. The first one is connected to a charge density wave (CDW) transition, while the last one is connected to an antiferromagnetic (AFM) transition. Our systematic synchrotron powder diffraction data in the temperature range 390 to 160 K revealed that the system remains in the orthorhombic symmetry in this temperature range. The data however revealed a clear discontinuity in the lattice parameters below ∼233 K. This observation indicates a close connection between the CDW transition and structural modulation in this system.

Impedance-Based Detection of NO2 Using Ni-MOF-74: Influence of Competitive Gas Adsorption.

Chemically robust, low-power sensors are needed for the direct electrical detection of toxic gases. Metal-organic frameworks (MOFs) offer exceptional chemical and structural tunability to meet this challenge, though further understanding is needed regarding how coadsorbed gases influence or interfere with the electrical response. To probe the influence of competitive gases on trace NO2 detection in a simulated flue gas stream, a combined structure-property study integrating synchrotron powder diffraction and pair distribution function analyses was undertaken, to elucidate how structural changes associated with gas binding inside Ni-MOF-74 pores correlate with the electrical response from Ni-MOF-74-based sensors. Data were evaluated for 16 gas combinations of N2, NO2, SO2, CO2, and H2O at 50 °C. Fourier difference maps from a rigid-body Rietveld analysis showed that additional electron density localized around the Ni-MOF-74 lattice correlated with large decreases in Ni-MOF-74 film resistance of up to a factor of 6 × 103, observed only when NO2 was present. These changes in resistance were significantly amplified by the presence of competing gases, except for CO2. Without NO2, H2O rapidly (<120 s) produced small (1-3×) decreases in resistance, though this effect could be differentiated from the slower adsorption of NO2 by the evaluation of the MOF's capacitance. Furthermore, samples exposed to H2O displayed a significant shift in lattice parameters toward a larger lattice and more diffuse charge density in the MOF pore. Evaluating the Ni-MOF-74 impedance in real time, NO2 adsorption was associated with two electrically distinct processes, the faster of which was inhibited by competitive adsorption of CO2. Together, this work points to the unique interaction of NO2 and other specific gases (e.g., H2O, SO2) with the MOF's surface, leading to orders of magnitude decrease in MOF resistance and enhanced NO2 detection. Understanding and leveraging these coadsorbed gases will further improve the gas detection properties of MOF materials.

Synchrotron powder diffraction data for some smectite clay mineral standards

Synchrotron powder diffraction data is presented for a series of relatively phase-pure smectite clay mineral standards obtained from the Clay Minerals Society. Rietveld refinement using a model for turbostratic disorder was performed to estimate the lattice parameters and mineral impurities in the smectite standards. Bragg reflection lists and raw data have been provided for inclusion in the Powder Diffraction File.

Role of the thermal treatment on the microstructure of YAGG nanopowders prepared by urea glass route

Yttrium aluminium gallium garnet (YAGG, Y3Al2Ga3O12) doped with rare-earth ions has drawn large attention owing to its optical properties with applications ranging from persistent luminescent phosphors to nanothermometers. Herein, three different YAGG materials were synthesized via the urea glass route followed by thermal treatment, relatively undoped; doped with Ce3+, Cr3+, and Nd3+; and doped with Ce3+, Cr3+, and Yb3+. The garnet formation was studied in situ upon thermal treatment from 300 to 1000 °C using synchrotron powder diffraction. Our results show that with this method, the onset of formation of the garnet is about 860 °C, with comparable cell parameters for both undoped and doped YAGG. A possible growth mechanism of YAGG is therefore discussed on the basis of observed microstructural parameters such as occupancy, microstrain, and crystallite size.

Structural, Electric and Dynamic Properties of (Pyrrolidinium)3[Bi2I9] and (Pyrrolidinium)3[Sb2I9]: New Lead-Free, Organic-Inorganic Hybrids with Narrow Band Gaps.

Hybrid organic-inorganic iodides based on Bi(III) and Sb(III) provide integrated functionalities through the combination of high dielectric constants, semiconducting properties and ferroic phases. Here, we report a pyrrolidinium-based bismuth (1) and antimony (2) iodides of (NC4H10)3[M2I9] (M: Bi(III), Sb(III)) formula which are ferroelastic at room temperature. The narrow band gaps (~2.12 eV for 1 and 2.19 eV for 2) and DOS calculations indicate the semiconducting characteristics of both materials. The crystal structure consists of discrete, face-sharing bioctahedra [M2I9]3- and disordered pyrrolidinium amines providing charge balance and acting as spacers between inorganic moieties. At room temperature, 1 and 2 accommodate orthorhombic Cmcm symmetry. 1 displays a complex temperature-induced polymorphism. It is stable up to 525 K and undergoes a sequence of low-temperature phase transitions (PTs) at 221/222 K (I ↔ II) and 189/190 K (II ↔ III) and at 131 K (IV→III), associated with the ordering of pyrrolidinium cations and resulting in Cmcm symmetry breaking. 2 undergoes only one PT at T = 215 K. The dielectric studies disclose a relaxation process in the kilohertz frequency region, assigned to the dynamics of organic cations, described well by the Cole-Cole relation. A combination of single-crystal X-ray diffraction, synchrotron powder diffraction, spin-lattice relaxation time of 1H NMR, dielectric and calorimetric studies is used to determine the structural phase diagram, cation dynamics and electric properties of (NC4H10)3[M2I9].

Structure Determination and Analysis of the Ceramic Material La0.987Ti1.627Nb3.307O13 by Synchrotron and Neutron Powder Diffraction and DFT Calculations

In this paper, the ternary system La2O3-TiO2-Nb2O5 is studied to find new ternary phases with useful electrical properties. The solid solution La3−xTi5−3xNb10−2xO39.5−12.5x was recently identified, and this study focuses on the structural characterization of this solid solution with x = 0.04. The crystal structure, representing a new structural type, was determined from synchrotron and neutron powder diffraction data. The unit cell parameters are a = 7.332 Å, b = 7.421 Å, c = 10.673 Å, α = 84.15°, ß = 80.16°, γ = 60.37°, and space group P1¯. The titanium and niobium atoms are disordered in five different crystallographic sites coordinated octahedrally by oxygen atoms. The eight-coordinated La atoms are embedded in the octahedral framework. Ti and Nb preferentially occupy different sites, and this feature was studied using periodic density functional theory methods. Energies of possible Ti/Nb distributions were calculated and the results agree well with the site occupancies obtained by combined Rietveld refinement of synchrotron and neutron powder diffraction patterns. The geometries optimized by DFT also agree well with the structural parameters determined by diffraction. The general agreement between the theoretical calculations and the experimental data justifies the quantum chemical methods as reliable complementary tools for the structural investigation of ceramic materials.

Specimen-displacement correction for powder X-ray diffraction in Debye-Scherrer geometry with a flat area detector.

The effect of small changes in the speci-men-to-detector distance on the unit-cell parameters is examined for synchrotron powder diffraction in Debye-Scherrer (transmission) geometry with a flat area detector. An analytical correction equationis proposed to fix the shift in 2θ values due to speci-men capillary displacement. This equationdoes not require the use of an internal reference material, is applied during the Rietveld refinement step, and is analogous to the speci-men-displacement correction equations for Bragg-Brentano and curved-detector Debye-Scherrer geometry experiments, but has a different functional form. The 2θ correction equationis compared with another speci-men-displacement correction based on the use of an internal reference material in which new integration and calibration parameters of area-detector images are determined. Example data sets showing the effect of a 3.3 mm speci-men displacement on the unit-cell parameters for 25°C CeO2, including both types of displacement correction, are described. These experiments were performed at powder X-ray diffraction beamlines at the National Synchrotron Light Source II at Brookhaven National Laboratory and the Advanced Photon Source at Argonne National Laboratory.