Synchrotron Radiation X-ray Diffraction Research Articles

Regulating Crystalline Phase/Plane of Polymer Electrolyte for Rapid Lithium Ion Transfer.

Electronic-rich functional groups and flexible segments have long been perceived to be the decisive factors influencing lithium-ion transfer in polymer electrolytes, while crystallinity is regarded as the great scourge. Actually, the research on the influence of crystalline phase and crystalline plane is still in scarcity. Herein, taking poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP) as an example, new (111/201) crystal planes (belonged to β-phase) are regulated by dissolving process and clarified by Synchrotron radiation X-ray diffraction and X-ray diffraction. Density functional theory calculation indicates that the newly exposed (111/201) crystal planes provide higher binding energy with lithium ions and are conducive to provide more ion transport channels. 7Li nuclear magnetic resonance of new crystalline planes contained PVDF-HFP based electrolyte shows lower field and sharper peak intensity, further proves the rapid lithium ion transfer. Therefore, a high ionic conductivity of 6.42×10-4 S cm-1 and a large lithium-ion transfer number of 0.7 are achieved. This study offers a new insight into the influence of crystalline phase and crystalline plane on the transfer of lithium ion for polymer electrolytes.

The effect of iron complexes−nitrilotriacetate in the bio−oxidation of sulphide minerals: Toxic metal(loid)s release and surface microstructure

Mineral exploitation and processing lead to the production of a large amount of stibnite−containing waste, which are the main sources of toxic metal(loid)s pollution in soil and water ecosystems. Bio−oxidation constitutes an essential driving force for pollution formation. However, the release of Sb in the association of stibnite and arsenopyrite in the presence of nitrilotriacetic acid (NTA) is still unclear. In this study, stibnite, stibnite−arsenopyrite and stibnite−arsenopyrite−NTA were designed to study the release characteristics of antimony (Sb). And the microstructure of elements in the reaction microinterface was analyzed by high−precision spectral characterization such as synchrotron radiation X−ray diffraction (SRXRD) and X−ray photoelectron spectroscopy (XPS). The results showed that the cell density of the microbial community in the three groups did not change much in the early stage, and began to rise and gradually stabilized in the middle and late stage of the reaction, indicating that the biological reaction basically stopped. Arsenopyrite promotes the release of antimony from stibnite, and the addition of NTA further enhanced the release of Sb and arsenic (As), increasing 17,292 and 43,130 mg/kg. However, the concentration of Fe decreased but progressively increased due to the NTA added. Meanwhile, the existence of NTA decreased leachate pH from 2.25 to 1.45 and increased Eh from 273 mV to 323 mV. The presence of NTA reduced the FeAsS in the microinterface of minerals to 30.6 %. Meanwhile, Fe2(SO4)3 and FeAsO4·2H2O decreased to 3.8 % and 0.5 %, Sb2O5 and As(Ⅲ)−O increased to 22.4 % and 21.9 %. The abovementioned facts indicated that the complexation of NTA with Fe (Ⅲ) inhibits the formation of passivates such as jarosite and scorodite, thus promoting the bio−oxidation of arsenopyrite and stibnite. The new insight of stibnite bio−oxidation contributed to the understanding of sulfide oxidation mechanism and helped to put forward the control measures of pollution source in mining area.

A comprehensive study on H2 loading/deloading with PdAg alloy thin films using in-situ synchrotron radiation X-ray diffraction

The present study gives a comprehensive picture of interaction of hydrogen with Pd0.54Ag0.46 and Pd0.88Ag0.12 alloy thin films, at RT, 50 °C, 100 °C, 150 °C and200 °C, based on the experiments reported in the present work. During hydrogenation, the diffraction peaks shifted towards a lower angle, indicating an expansion of the lattice due to hydrogen incorporation revealed by in-situ synchrotron XRD. The cycles of hydrogen absorption and desorption were fully reversible, and no hysteresis was observed in the synthesized films. Our experiments suggest that at room temperature the magnitude of peak-shift on hydrogenation is larger with lower concentrations of Ag in Pd. Additionally, the interaction of PdAg alloy with hydrogen was observed to be temperature dependent. Increased hydrogenation temperature reduces the hydrogen sticking coefficient, reducing the peak shift magnitude for both samples. Additionally, at higher temperatures, hydrogen absorption is higher in Pd54Ag46 having smaller crystallite sizes than in Pd88Ag12.

Oscillating Structural Transformations in the Electrochemical Synthesis of Graphene Oxide from Graphite.

Electrochemical synthesis of graphene oxide (GO) is known to occur with potential oscillations, but the structural changes underlying these oscillations have remained unclear. In situ time-resolved synchrotron radiation X-ray diffraction demonstrates that the electrochemical synthesis of GO in aqueous H2SO4 can be described as an oscillating reaction. The transformation from graphite to GO proceeds through periodic structural oscillations that correlate with potential cycles. Stage-1 graphite intercalation compound (GIC) is found only at the peak of the potential cycle, but not at the bottom of the cycle. Stage-1 GIC is formed in the first half-cycle from stage-2 GIC and then transforms into "pristine graphite oxide" (PGO) on the lower side of the potential cycle, after which the cycle restarts with the formation of a new portion of stage-1 GIC. Water-washing results in the transformation of PGO into water-swollen GO with d(001) ~11 Å. These periodic structural changes can be considered a new type of oscillating reaction. The presented results provide broad insights into the oscillating structural changes occurring during the anodic graphite oxidation in aqueous H2SO4 and allow to update of the mechanism of GO electrochemical formation.

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.

Observation of ferroelectric domains in BaTiO3 by synchrotron radiation X-ray diffraction topography

X-ray diffraction topography was used to observe two distinct ferroelectric domains in BaTiO3. The use of highly-parallel X-rays and a high-resolution detector with approximately 200 nm resolution enabled us to successfully characterize two distinct domains, each with sizes of the order of 10 μm. Along with the local rocking curve of the bulk crystal, we generated width maps corresponding to crystal properties including defects and, strain. This information is beneficial for understanding domain behavior, and the measurement system can be expected to become a powerful tool for in situ measurements of processes requiring domain control.

Two types of cubic components coexisting in the paraelectric phase of relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 revealed by synchrotron radiation X-ray diffraction

The crystal structures of relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 (PMN) have been investigated using synchrotron radiation X-ray powder diffraction. Two different types of cubic components coexist in the paraelectric phase at 600 K. The first is Cubic-I, in which the Pb ion is isotropically off-centered from the corner of the perovskite-type unit cell. The other, Cubic-II, has the Pb ion preferentially off-centered in the <111> directions from the corner. The volume fractions of Cubic-I and Cubic-II are approximately 83% and 17%, respectively. Previous studies have shown that only approximately 20% of PMN transitions to a rhombohedral structure at 100 K. This observation suggests a close relationship between Cubic-II and the rhombohedral structure at low temperatures. The intrinsic structural inhomogeneity observed in the paraelectric phase, such as variations in the disordering behavior of Pb ions, is potentially linked to the relaxor characteristics of PMN.

Metal-organic framework-derived carbon-supported high-entropy alloy nanoparticles applied in ammonia borane hydrolytic dehydrogenation

While high-entropy alloy nanoparticle (HEA NP) catalysts from a sacrificial high-entropy-MOF (HE-MOF) have been attractive, their conventional characterizations may be misleading. Here, we report HEA NPs on HE-MOF-derived carbon (HE-MDC) via direct pyrolysis of MnFeCoNiCu HE-MOF in Ar and H2 at different temperatures and durations with a fast-ramping rate. With the profound investigations of the metal NPs on HE-MDCs by synchrotron radiation X-ray diffraction and absorption, we revealed that the Ar-treated HE-MDCs had either Cu-dominant solid solution or phase-segregated metal NPs, whereas H2 pyrolysis yielded well-dispersed HEA NPs on HE-MDCs. For ammonia borane hydrolysis, although the metal NP size in H2-treated HE-MDC was not the smallest, it showed the fastest dehydrogenation rate (TOF=5.76 molH₂∙min−1∙molcat-1), 2 ∼ 4 times faster than the Ar-treated HE-MDCs. It emphasized the crucial role of elemental uniformity in the HEA NPs over the traditionally reported catalyst size.

Mechanical, Thermal Properties, and Extreme Phase Stability of High-Entropy Diborides (V0.2Nb0.2Ta0.2Cr0.2W0.2)B2.

High-entropy diborides (HEDBs) have gained significant attention in industrial applications due to their vast composition space and tunable properties. We propose a solid solution reaction at high temperatures and pressures that successfully synthesized and sintered a novel, dense, and phase-pure HEDB (V0.2Nb0.2Ta0.2Cr0.2W0.2)B2. A high asymptotic Vickers hardness of 26.3 ± 0.6 GPa and a bulk modulus of 320.5 ± 10.6 GPa were obtained. Additionally, we investigated the thermal oxidation process using TG-DSC from room temperature to 1500 °C and explored the phase stability of HEDBs under high-pressure conditions through in situ high-pressure synchrotron radiation X-ray diffraction. We analyzed the formation of lattice distortion, chemical bonding, and band structure in (V0.2Nb0.2Ta0.2Cr0.2W0.2)B2 using first-principles calculations. Surprisingly, we found that the predominant distortion in diborides occurs in the boron layer, supported by ELF. This may be due to uneven electron transfer rather than a straightforward correlation with the atomic radius. These results provide a novel synthesis process and additional experimental data on the mechanical and thermal properties and high-pressure phase stability of HEDBs. Our study offers further insights into the microscopic structure of lattice distortion in HEDBs, which could prove crucial for the selection and design of engineering advanced HEDBs.

In-situ observation of solidification behaviors of Fe-Mn-Cr-Ni-Si alloy during TIG melt-run welding using synchrotron radiation X-ray

The solidification behaviors, including the solidification cracking and solidification mode of the Fe-Mn-Cr-Ni-Si alloys at the weld bead during tungsten inert gas (TIG) melt-run welding, were examined by time-resolved in-situ observations using synchrotron radiation X-ray imaging and X-ray diffraction. The dynamics of initiation and propagation of solidification cracking at the weld bead could be observed at the dendrite scale. For the specimen solidified in the austenite mode at a welding speed of 10 mm/s, solidification cracking with a zigzag interface developed via the coalescence of many small pores at the centerline, where the columnar dendrite tips impinged. Quantitative image analysis indicated that the local tensile strain was highly localized at the centerline, and the critical local tensile strain for the initiation of solidification cracking was approximately 0.04. For the specimen solidifying in the ferrite-austenite mode at the welding speed of 10 mm/s, the centerline solidification cracking was suppressed by the formation of many equiaxed γ-Fe dendrites ahead of the growing columnar δ-Fe dendrites. Grain refinement at the centerline can be achieved at a welding speed of more than 7 mm/s without requiring inoculants.

Combinatorial processing and evaluation of the phase evolution and oxidation behavior of Hf-Al-Si refractory complex concentrated alloys

Refractory complex concentrated alloys (RCCAs) are a unique group of materials defined by the shared principality between all alloying elements and the tailorable properties at high temperatures (>1000 °C). RCCA systems can be optimized using high-throughput processing which allows for simultaneous characterization and testing over a range of compositions. A compositionally-graded Hf-Al-Si coating was compositionally mapped using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) to identify relative compositions as a function of position on the wafer. High temperature CALPHAD phase diagrams and thermodynamic predictions for a Hf50Al50-xSix alloy and its (Hf50Al50-xSix)1-yOy oxide were coupled with experimental results. The RCCA wafer was heat treated at 1200 °C to observe any phase changes and oxidation behavior at elevated temperatures. Characterization of the RCCA was performed before and after heating using synchrotron radiation X-ray diffraction (SR-XRD) to identify the phases and oxidation states as a function of the compositional gradient and to determine an alloy composition range with the least oxidation. SR-XRD pre- and post-treating revealed an inherent amorphous Hf20Al7Si13 phase across the as-deposited coating, similarities in spectra pre- and post-treating for compositions containing less Hf and more Al and Si relative to the entire gradient film, and the presence of significant HfO2 and Al6Si2O13 oxide for compositions consisting of more Hf and less Al and Si relative to the entire gradient film. The SR-XRD and CALPHAD modeling suggests that compositions of 31–48 at.% Hf, 21–48 at.% Al, and 9–27 at.% Si display the greatest resistance to detrimental oxidation upon heating to 1200 ∘C.

Dissecting of Atomic Morphology of Superfine Pulverized Coal Based on X-ray Pair Distribution Function

Resolving the atomic structure information of the aromatic layers in coal plays a crucial role in understanding the generation mechanisms of NOx during coal combustion and further reducing the formation of NOx from the source. This study reveals the distribution of X-ray diffraction bands of superfine pulverized coal using a high-resolution synchrotron radiation X-ray Diffraction (HRXRD) facility, discussing the distribution of atomic distances and atomic density in aromatic layers through pair distribution function (PDF) methods. Furthermore, the influences of mechanochemistry on the evolution of atomic morphology are focused on. The results show that the PDF of coal gradually stabilizes when r &amp;gt; 8 Å, showing the short-range order of graphite-like structure. Additionally, due to the limitations of scanning angle and X-ray energy, atomic distances in aromatic layers for coal are significantly greater than that of pure graphene. Enhanced mechanochemical effects make the peaks 1, 2, and 3 of coal PDF more similar to graphene&amp;apos;s by condensing alkyl side chains into smaller, regular aromatic layers when the particle size decreases. With the enhancement of mechanochemical effects, coals with different metamorphic degrees exhibit different aromatic evolution patterns. The aromaticity of NMG coal first decreases and then increases, while the aromaticity of YQ coal shows the opposite trend. The results can provide deeper insights into the atomic structure of coal macromolecular, which can facilitate the advancement of novel ultra-low NOx combustion methods and support the construction of precise coal macromolecular models.

In-situ Synchrotron Radiation XRD Crystal Structure and Microstructure Analysis of CaO-ZrO2 solid-solution at 1100°C with Prolonged Heating

Abstract The structural analysis of the CaO-ZrO2 solid-solutions was carried out using in-situ synchrotron radiation X-ray diffraction (SR-XRD). CaO-ZrO2 solid-solutions with 0, 2.5, and 5 at.% CaO contents were synthesized via a solid-solid ball milling technique. The amorphous ZrO2 powder was synthesized via co-precipitation using ZrCl4 and NH4OH as precursors, while the CaO powder was purified from a local limestone. In-situ SR-XRD measurements were conducted on the CaO-ZrO2 mixtures by independently heating them to 1100°C for different holding times of 0, 12, 24, and 36 minutes using a DHS furnace. Qualitative analysis of all SR-XRD patterns showed that only tetragonal zirconia (t-ZrO2) was present. The crystallite size of tetragonal zirconia ranged from 17 to 22 nm, depending on calcination holding time and CaO addition. Further analysis showed that the tetragonality (c/a) parameter remained relatively constant over the 36-minute holding time. However, the introduction of CaO led to an insignificant reduction in tetragonality, averaging 0.292%.

Activation energy and crystal growth coefficient determination of t-ZrO2 using high-temperature synchrotron X-ray diffraction

Abstract Activation energy and crystal growth coefficient of t-ZrO2 (tetragonal zirconia) were determined through an in-situ synchrotron radiation X-ray diffraction (SR-XRD) experiment. The t-ZrO2 precursor was synthesized through (a) purification of zircon sand from Kereng Pangi, Kalimantan to zircon powder, (b) alkali fusion, and (c) co-precipitation. High-temperature SR-XRD experiments were carried out with varying holding times of 1, 2, and 3 hours at 900, 950, and 1000 °C, respectively, where the formation and crystal growth of t-ZrO2 were observed. The diffraction patterns show that t-ZrO2 has formed at 900°C for 1 hour and it grows accordingly. The effect of the heating temperature and holding time on the crystal growth shows that the size of hot crystals increases with increasing temperature and holding time. It is found that the activation energy of t-ZrO2, in general, decreases with holding time, i.e. from 75.3 kJ/mol (3 h) to 57.3 (1h). Meanwhile, Beck’s crystal growth coefficient value is between 0.3 at 900 °C and 0.2 at 1000 °C.

High-Pressure Induced Continuous Structural Evolution of Kagome Antiferromagnet MgMn3(OH)6Cl2: A Structural Analogue to Quantum Spin Liquid Herbertsmithite.

MgMn3(OH)6Cl2 serves readily as the classical Heisenberg kagome antiferromagnet lattice spin frustration material, due to its similarity to herbertsmithite in composition and crystal structure. In this work, nanosheets of MgMn3(OH)6Cl2 are synthesized through a solid-phase reaction. Low-temperature magnetic measurements revealed two antiferromagnetic transitions, occurring at ∼8 and 55 K, respectively. Utilizing high-pressure synchrotron radiation X-ray diffraction techniques, the topological structural evolution of MgMn3(OH)6Cl2 under pressures up to 24.8 GPa was investigated. The sample undergoes a second-order structural phase transition from the rhombohedral phase to the monoclinic phase at pressures exceeding 7.8 GPa. Accompanying the disappearance of the Fano-like line shape in the high-pressure Raman spectra were the emergence of new Raman active modes and discontinuities in the variations of Raman shifts in the high-frequency region. The phase transition to a structure with lower symmetry was attributed to the pressure-induced enhancement of cooperative Jahn-Teller distortion, which is caused by the mutual substitution of Mn2+ ions from the kagome layer and Mg2+ ions from the triangular interlayer. High-pressure ultraviolet-visible absorption measurements support the structural evolution. This research provides a robust experimental approach and physical insights for further exploration of classical geometrical frustration materials with kagome lattice.

In situ analyses of crystallization behavior of 1,2,3-tripalmitoyl glycerol under static and dynamic thermal conditions

The crystallization behavior of 1,2,3-tripalmitoyl glycerol or PPP using differential scanning calorimetry (DSC), thermo-optical polarized light microscopy and in situ synchrotron radiation X-ray diffraction (SR-XRD) techniques was precisely examined under static isothermal and dynamic thermal treatments, and the results were compared with preceding studies. PPP was rapidly (15 °C min−1) cooled to target temperatures (from 40 to 59 °C) to determine the precise moment at which crystallization was initiated. Once crystallization ceased, polymorphic transformation and melting were analyzed during subsequent heating. α form was crystallized during isotherms from 40 to 46 °C, temperature at which it coexisted with β′ phase. The latter was solely formed from 47 to 53 °C, and polymorphic crystallization was directed to obtain exclusively most stable β at 54 °C and higher temperatures. Nucleation time values for the α, β′ and β polymorphs exhibited exponential growth type, and a good correlation was found between data obtained by DSC and SR-XRD. Dynamic experiments were based on the use of high (15 °C min−1), intermediate (2 °C min−1) and low (0.5 and 0.1 °C min−1) cooling and heating rates. Thermo-optical polarized light microscopy experiments also provided valuable information on microstructural changes occurring during polymorphic modifications. Less stable forms predominated at high cooling rates, whereas lower velocities leaded the polymorphic crystallization to obtain more stable forms.

Feature extraction and spatial imaging of synchrotron radiation X-ray diffraction patterns using unsupervised machine learning

Feature extraction and spatial imaging of synchrotron radiation X-ray diffraction patterns using unsupervised machine learning

Effect of pressure on the structural properties of tantalum carbide

In this study, tantalum carbide (TaC) samples were placed in a diamond anvil cell to study the equation of state at room temperature and high pressure using synchrotron radiation X-ray diffraction. By fitting the data at ambient pressure and up to the highest pressure of 38.5[Formula: see text]GPa, we obtained the bulk modulus and first derivative of TaC as [Formula: see text] (6.8) GPa and [Formula: see text] (0.49), respectively. In addition, we calculated the bulk modulus and band structure of TaC under high pressure using density functional theory. The obtained bulk modulus is 267 (3)[Formula: see text]GPa. TaC is metallic in nature throughout the entire pressure range. We studied the high-pressure deviatoric stress of TaC using linewidth analysis method. We found that TaC can support a maximum differential stress of up to 18.6[Formula: see text]GPa at the highest pressure of 38.5[Formula: see text]GPa.

Mesophase induced by alternating-current poling in relaxor ferroelectric single crystals

Alternating-current poling (AC-Poling) has attracted wide interests in enhancing piezoelectric performance of ferroelectric single crystals. However, the mechanism of phase transformations and domain morphology underlying AC-Poling has not been thoroughly investigated. In this work, we have systematically studied the AC-poling effect on domain structures and piezoelectric properties in the relaxor ferroelectric single crystals of 0.24Pb(In1/2Nb1/2)O3–0.44Pb(Mg1/3Nb2/3)O3–0.32PbTiO3. It is shown that the piezoelectric constant (d33) and permittivity (ε33) are greatly enhanced via [001]-AC-poling compared to DC-poling, related to the presence of modified domain configurations as indicated previously. For [110]-oriented specimens, the piezoelectricity through AC-poling is only half as that for the DC-poled single crystals. We attribute this to the transition from the monoclinic-B phase to an orthorhombic phase under AC-poling, confirmed by synchrotron radiation X-ray diffraction and piezo-response force microscopy. The transition to the orthorhombic phase is likely a consequence of lower Gibbs energy. This study on orientation-dependent characteristics of AC-poling for PIN-PMN-PT single crystals will guide the development of AC-poling technology in applications.

In-situ study on piezoelectric responses of sol-gel derived epitaxial Pb[Zr,Ti]O3 thin films on Si substrate

Pb[Zr,Ti]O3 (PZT) thin films with the Zr/Ti ratio of 45/55, 52/48, and 60/40 (PZT(45/55), PZT(52/48), and PZT(60/40), respectively) are deposited on (001)SrRuO3/(001)Pt/ZrO2/Si by sol-gel method. We confirm that the epitaxial (001)Pt electrode facilitate the epitaxial growth of the PZT thin films along the c-axis direction. Basic characteristics such as structural, dielectric, and ferroelectric properties are examined. Furthermore, direct and converse piezoelectric properties are evaluated using effective transverse piezoelectric coefficients, |e31,f|. In particular, the epitaxial PZT thin films manifest a dependence of the converse |e31,f| on applied voltages with the values as follows; 9.7–11.5 C/m2, 11.2–12.5 C/m2, and 11.7–12.3 C/m2 for the epitaxial PZT(45/55), PZT(52/48), and PZT(60/40), respectively. Moreover, by analyzing bias-resolved in-situ reciprocal space map (RSM) obtained from synchrotron radiation X-ray diffraction (SR-XRD) which allows for the understanding on the transition of crystal structures, we explore the voltage-induced contributions for the converse |e31,f|.