Synchrotron Studies Research Articles

Imaging Zn and Ni distributions in leaves of different ages of the hyperaccumulator Noccaea caerulescens by synchrotron-based X-ray fluorescence

Mapping of leaves of hyperaccumulators can provide insights into the mechanisms these species utilize to accumulate high metal concentrations. We used synchrotron-based X-ray fluorescence (SXRF) to perform Zn and Ni imaging in leaves of different ages of Noccaea caerulescens. A mature leaf of the related non-hyperaccumulator Thlaspi arvense was also imaged. The concentrations of Zn, Ni, Co, and Cr in N. caerulescens grown on an ultramafic soil were 9-, 10-, 12-, and 3-fold higher than T. arvense. N. caerulescens showed an exceptional ability to accumulate Zn from the soil, posing a bioconcentration factor of 6.7. T. arvense had Zn and Ni distributed uniformly in the leaf blade with doubling fluorescence counts in the tip and margins, suggesting a strategy to excrete metals and avoid toxicity. On the other hand, N. caerulescens displayed distinctly different Zn and Ni accumulation patterns, regardless of the age or metal concentration in the leaves. Zinc was mainly distributed in the cells surrounding the central and secondary veins. Nickel accumulated in the margins and tips of the leaf blade. Given the time required to image large leaves in synchrotron facilities, small leaves can be used to represent the leaf distribution of Zn and Ni in N. caerulescens.

In situ/operandosynchrotron x-ray studies of metal additive manufacturing

Abstract

Artefacts from Ban Chiang, Thailand: pottery with hematite-red geometric patterns

Abstract Ban Chiang () is an extensively studied archeological site in Northeast Thailand, Udon Thani Province, which became a UNESCO world heritage in 1992. Depending on their production period ceramic artefacts show characteristic patterns at the surface which may be interpreted as iconographic motifs for the site. Two ceramic samples, excavated in 2003, from different periods were re-investigated, previously studied by Tanthanuch W., Pattanasiriwisawa W., Somphon W., Srilomsak S. Synchrotron studies of Ban Chiang ancient pottery. Suranaree J. Sci Technol. 2011, 18, 15–28 who focussed on thermal firing and redox-conditions. Shards selected for this study were sample 5412-S6E15 dated from Bronze Age (ca. 1000–300 BC) with yellow-brown, paint-free surface and a younger sample 8027 from Iron Age (ca. 300 BC–200 AD) with red painted design carrying pictorial patterns typical for the Ban Chiang ceramics. The surface material and colour of both shards was studied in detail using optical reflectance, FTIR spectroscopy and X-ray powder diffraction. Thin sections were used to determine the thickness of the red paint and the elemental composition of the surface using an electron microprobe. Chemical composition of sample 5412-S6E15 consists as oxides of elements mainly of SiO2 and Al2O3 (representing ca. 59 and 20 wt. %) and that of the red colour of the youngest sample 8027 consists mainly of SiO2, Al2O3 and Fe2O3 (representing ca. 52, 13 and 13 wt. %), the average composition adjacent to the red painted area has ca. 72 wt. % SiO2, ca. 10 wt. % Al2O3 and only 2 wt. % Fe2O3. X-ray powder diffraction, FTIR spectroscopy and optical reflectance measurements confirm hematite in the mineralogical composition of the red pigment of shard 8027.

L-Lysine Amino Acid Adsorption on Zeolite L: a Combined Synchrotron, X-Ray and Neutron Diffraction Study.

Invited for this month's cover are the groups of Annalisa Martucci and Luisa Pasti at the University of Ferrara (Italy). The cover picture shows L-lysine amino acid adsorption on zeolite L. The role of zeolite channels in the stabilization of the lysine absorbed and the effect of water on protein structure are elucidated at atomistic level. The stabilization of the L α-helical conformation is related to strong H-bonds between the tail aminogroups of lysine molecules and the Brønsted acid site as well as to complex intermolecular H-bond system between water molecules, zeolite and amino acid. Read the full text of their Full Paper at 10.1002/open.202000183.

Synchrotron and Raman Study of the Rotator Phases and Polymorphism in Tricosane Paraffin.

A detailed study of the phase behavior of n-paraffin C23H48 has been performed by means of real-time variable-temperature experiments with synchrotron radiation. Two detectors were employed for simultaneous analysis of the small-angle (SAXS) and wide-angle X-ray-scattering (WAXS) regions. This paraffin presents a very interesting phase behavior, involving two crystal polymorphs, three rotator phases and the liquid state. The Ostwald rule of stages is invoked to find similarities of the rotator phases with the eventual transient mesomorphic structure in the multistage model of polymer crystallization. That study is complemented by variable-temperature Raman experiments covering frequencies down to 150 cm−1. It was found that the low-frequency region is the most informative regarding the phase transitions, and specifically the intensity of the first overtone. From these analyses, several parameters are evaluated as function of temperature.

High spatial resolution studies of phase transitions within organic aperiodic crystals

The understanding of the symmetry breakings within crystals that are aperiodic by construction is actually very limited. Quasicrystals and incommensurate composite crystals may potentially allow such studies. We focus on the phase transitions of the aperiodic $n$-nonadecane/urea which recovers a translational symmetry within a four-dimensional space at room temperature. High-resolution neutron and synchrotron studies are reported as a function of the temperature on this organic crystal which presents an exceptional mosaicity. They reveal the richness of such approach, showing the appearance of very long wavelength supplementary intermodulations. This work generalizes the Landau theory to incommensurate composite crystals.

Faster Activation and Slower Capacity/Voltage Fading: A Bifunctional Urea Treatment on Lithium‐Rich Cathode Materials

AbstractLi‐rich layered oxides are promising cathode materials for next‐generation Li‐ion batteries because of their extraordinary specific capacity. However, the activation process of the key active component Li2MnO3 in Li‐rich materials is kinetically slow, and the complex phase transformation with electrode/electrolyte side reactions causes fast capacity/voltage fading. Herein, a simple thermal treatment strategy is reported to simultaneously tackle these challenges. The introduction of a urea thermal treatment on Li‐rich material Li1.87Mn0.94Ni0.19O3 leads to oxygen deficiencies and partially reduced Mn ions on the oxide surface for activating the Li‐rich phase. In situ synchrotron study confirms that the urea‐treated cathode shows much faster Li extraction from both Li and transition metal layers with less oxygen evolution upon charging than that of untreated counterparts. Moreover, the decomposition products of urea during thermal treatment subsequently deposit on the surface of cathode material, leading to a unique passivation layer against side reactions between electrode and electrolyte. Soft X‐ray absorption spectroscopy reveals the structural evolution mechanism with a significantly suppressed dissolution of Mn species over cycling measurement. The urea‐treated Li1.87Mn0.94Ni0.19O3 shows accelerated activation kinetics to reach high capacity of 270 mA h g–1 and demonstrates excellent capacity retention of 98.49% over 300 cycles with slower voltage decay.

Synchrotron study on the evolution of the radial structural distribution of carbon fiber monofilaments during heat treatment process.

Evolution of the radial distribution of a micro-crystalline structure within polyacrylonitrile monofilaments at various temperatures during carbonization was investigated via the method of synchrotron wide-angle X-ray diffraction (S-WAXD) and micro-scanning Raman spectroscopy. The result indicated that in the core region of the carbon fiber monofilaments, the Lc is lower while the interplanar spacing (d002) is higher compared with those in the skin region at 1300 °C. The difference between the skin and core regions in Lc and d002 constantly decreases as the heat treatment temperature increases. The results of micro-scanning Raman indicated that the micro-crystallites grow faster along the La direction, and the graphite degree is higher in the skin region than that in the core region. This is attributed to the fact that the removal of nitrogen element is the domain factor on the growth of a pseudo-graphite crystallite at relatively lower heat treatment temperatures. As the temperature rises, Lc is developed mainly in the core region with the closed packing of a graphite layer, while the crystallites in the skin region grow in both La and Lc directions, which are mainly affected by the disordered and boundary graphite structure.

Synchrotron, X-Ray, and Electron Microscopic Studies of Catalyst Systems Based on Multiwalled Carbon Nanotubes Modified by Copper Nanoparticles

The results of the studies of a composite based on multiwalled carbon nanotubes (MWCNTs), onto the outer surface of which nanosized copper particles are deposited by the pyrolysis of copper formate, via electron microscopy, X-ray diffractometry, and ultrasoft X-ray spectroscopy, are discussed. It is found that, in an inert argon atmosphere, copper nanoparticles are deposited onto the surface of MWCNTs in the form of different-size nanoparticles consisting of a metallic copper nucleus and a cuprous oxide Cu2O shell. However, after being taken out into the atmosphere, a layer of copper oxide CuO is formed on the surface of the copper nanoparticles. It is shown that the good adhesion of the copper nanoparticles on the surface of the MWCNTs is provided by the formation of a chemical bond between the carbon atoms of the outer graphene layer of the nanotube and the oxygen atoms of cuprous oxide Cu2O that initially covers the metallic nucleus of the nanoparticles.

Synchrotron in situ studies of mechanical activation treatment and γ-radiation impact on structural-phase transitions and high-temperature synthesis parameters during the formation of γ-(TiAl) compound.

In situ synchrotron studies of structure and phase formation dynamics in mechanically activated (t = 7 min, power density 40 g) and mechanically activated with subsequent irradiation by γ-quanta 60Co powder mixture (Ti64 wt% + Al) during high-temperature synthesis by the method of thermal explosion using induction heating are described. In situ high-temperature synthesis was carried out on the created experimental complex adapted for synchrotron X-ray diffraction methods. The sequence of formation and time-temperature interval of the metastable and main phases were determined. The impact of preliminary mechanical activation and of γ-irradiation on the macrokinetic parameters of the synthesis were studied experimentally in situ. It has been established that the impact of γ-irradiation on the mechanically activated powder mixture of the composition Ti 64 wt% + Al leads to a change in the thermal parameters of combustion: the maximum synthesis temperature and the burning rate decrease. The heating rate for the non-irradiated mixture is 204.8 K s-1 and that for the irradiated mixture is 81.6 K s-1. The dependences of mass fractions of the synthesized compounds on time and temperature were calculated from the stage of preheating until completion of the thermal explosion. A single-phase equilibrium product of the composition γ-(TiAl) is formed in γ-irradiated mechanically activated mixture when the system reaches maximum temperature. The synthesized product of the mechanically activated mixture without γ-irradiation contains 72% γ-(TiAl); TiAl3 (26%) and residual Ti (2%) are also observed.

Design of a containment apparatus for synchrotron XAS measurements of radioactive fluid samples under high temperatures and pressures.

The simple working principles and versatility of the hydrothermal diamond-anvil cell (HDAC) make it highly useful for synchrotron x-ray studies of aqueous and fluid samples at high pressure-temperature (P-T) conditions. However, safety concerns need to be overcome in order to use the HDAC for synchrotron studies of aqueous radioactive samples at high temperatures and pressures. For accomplishment of such hydrothermal experiments of radioactive materials at synchrotron beamlines, the samples are required to be enclosed in a containment system employing three independent layers of airtight sealing at some synchrotron facilities while enabling access to the sample using several experimental probes, including incoming and outgoing x-rays. In this article, we report the design and implementation of a complete radiological safety enclosure system for an HDAC specialized for high P-T x-ray absorption spectroscopy (XAS) measurements of aqueous solutions containing the actinides at synchrotron beamlines. The enclosure system was successfully tested for XAS experiments using the HDAC with aqueous samples containing depleted uranium at temperatures ranging from 25 to 500 °C and pressures ranging from vapor pressure to 350 MPa.

Numerical simulation of wave-like nucleation events

The Interdependence model [1] predicted that nucleation would occur in waves of events with regions of no nucleation in between each wave. The waves continue to form until nucleation covers the sample. The cause of this phenomenon was attributed to the formation of a nucleation-free zone which incorporates solute suppressed nucleation and inhibited nucleation zones. Recent real-time synchrotron x-ray studies by Prasad et al [2], Liotti et al [3] and Xu et al [4] have confirmed this hypothesis showing nucleation occurs in a step-wise fashion with a number of events occurring followed by little or no nucleation for a short period before another set of events occurs. A microscale solidification model that predicts diffusion-controlled dendritic growth has successfully shown the effect of the developing constitutional supercooling on the selection of nucleation events. In this study, we use this model to predict the solidification behaviour under the conditions experienced during these real-time synchrotron studies.

A kinetic and mechanistic study into the transformation of calcium sulfate hemihydrate to dihydrate.

The conversion of CaSO4·0.5H2O to CaSO4·2H2O is of great importance industrially, being the reaction behind plasterboard production and the setting of medical plasters. A detailed kinetic and mechanistic study of this process was conducted using time-resolved synchrotron X-ray diffraction in this work. The CaSO4·2H2O product is very similar regardless of whether the α- or β-form of CaSO4·0.5H2O is used as the starting material, but the reaction process is very different. The induction time is usually shorter for α-CaSO4·0.5H2O than β-CaSO4·0.5H2O, and a greater conversion percentage is observed with the former (although in neither case does the reaction proceed to 100% completion). The temperature of the system, widely used in industry as an indirect measure of the extent of the hydration process, is found to be a poor proxy for this, with the maximum temperature reached well before the reaction is complete. The Avrami-Erofe'ev and Gualtieri models could both be fitted to the experimental data, with the fits being substantially closer in the case of α-CaSO4·0.5H2O. The rate of reaction in the Avrami model tends to increase with the amount of gypsum seeds added to accelerate the process, and the importance of nucleation declines. The Gualtieri analysis suggested that the rate of nucleation increases substantially with the amount of seeds added, while there are less distinct changes in the rate of crystal growth. At low seed concentrations (<0.5% w/w) the rate of crystal growth is greater than the rate of nucleation, but at concentrations above 0.5% w/w nucleation is faster. These findings represent the first synchrotron study of the conversion of CaSO4·0.5H2O to CaSO4·2H2O, and will be of importance to gypsum producers globally.

Adjustment of induction high-temperature synthesis to in situ synchrotron study of SHS-mixtures on the example of Ti-Al system

The paper discusses experimental complex, which allowing to carry out high-temperature synthesis of mechanically activated powder reagents by a method of induction heating in vacuum and inert environment. On the basis of this complex conducted in situ synchrotron research of the specific features of phase formation dynamics in mechanically activated 3Ti + Al powder composition. High temperature synthesis carried out under conditions of high volume inflammation by means of inductive heating. The developed complex is adapted to the method of dynamic diffractometry in synchrotron radiation beams to register the kinetics of phase transformations in the solid-phase reaction of the components of the powder mixture.

Implications on spatial models of interstellar gamma-ray inverse-Compton emission from synchrotron emission studies in radio and microwaves

Cosmic rays interacting with gas and photon fields in the Galaxy produce interstellar gamma-ray emission (IGE), which accounts for almost 50% of the photons detected at gamma-ray energies. Models of this IGE have to be very accurate for interpreting the high-quality observations by present gamma-ray telescopes, such as Fermi Large Area Telescope (LAT). Standard models of IGE, used as reference models for analyses of the Fermi LAT data, show spatial discrepancies with respect to the data, underlining the necessity of more realistic models. The same CR electrons that produce the inverse-Compton component of the IGE produce also interstellar synchrotron emission observed in radio and microwave. However, present standard models do not take advantage of results coming from studies of this interstellar synchrotron emission. Accounting for such results, in this work we show how they affect the calculated spatial maps of the large-scale inverse-Compton component of the IGE, which are usually used in studies of Fermi LAT data. It is found that these results significantly affect these spatial model maps even at a 60% level. In particular, propagation models based on synchrotron studies produce a more peaked inverse-Compton emission in the inner Galaxy region with respect to the standard models used to analyze Fermi LAT data. The conclusion is that radio and microwave observations can be included in a multifrequency self-consistent approach for a more accurate modeling of the IGE finalized to a physical comprehensive interpretation of gamma-ray data and its present unexplained features. Model parameters are provided, which supply a more realistic basis for high-energy gamma-ray studies.

In situ synchrotron research of phase formation in mechanically activated 3Ti + Al powder composition during high-temperature synthesis under the condition of heating with high-frequency electromagnetic fields.

An in situ synchrotron study of the specific features of the phase formation dynamics in mechanically activated 16 wt% Al + Ti powder composition is described, the high-temperature synthesis being carried out under the condition of high volume inflammation by means of inductive heating. The kinetics of the phase formation were registered with an experimental complex, especially designed, constructed and adjusted for the method of dynamic diffraction analysis in synchrotron radiation beams. It has been experimentally in situ shown that increasing the time of mechanical activation of the initial powder mixture reduces the temperature at which components start to react and the time of realization of the high-temperature synthesis. With the latter set at 1 min of mechanical activation, the temperature of the reaction in the mixture is T = 603°C; at 3 min of mechanical activation, T = 442°C; and at 7 min, T = 359°C. The maximum burning temperatures are: for 1 min of mechanical activation, Tmax = 1080°C; for 3 min, Tmax = 1003°C; and for 7 min, Tmax = 820°C. It was found that formation of both stable compounds Ti3Al, TiAl3, TiAl2, TiAl and metastable phases Ti9Al23, Ti5Al11, Ti2Al5, Ti3Al5 occurs at the stage of primary structure formation, before the system goes to thermal explosion. High-temperature synthesis of a mixture of the studied composition takes place without formation of a liquid phase, in the solid-phase combustion mode. It was found that the increase in the time of mechanical activation of the initial powder mixture contributes to the formation of a product with a dominant content of intermetallic compound Ti3Al. By synthesis of the powder mixture of composition 16 wt% Al + Ti, mechanically activated for 7 min, the content of Ti3Al in the final product was found to be 68%.

Three-dimensional imaging of the human internal acoustic canal and arachnoid cistern: a synchrotron study with clinical implications.

A thorough knowledge of the gross and micro‐anatomy of the human internal acoustic canal (IAC) is essential in vestibular schwannoma removal, cochlear implantation (CI) surgery, vestibular nerve section, and decompression procedures. Here, we analyzed the acoustic‐facial cistern of the human IAC, including nerves and anastomoses using synchrotron phase contrast imaging (SR‐PCI). A total of 26 fresh human temporal bones underwent SR‐PCI. Data were processed using volume‐rendering software to create three‐dimensional (3D) reconstructions allowing soft tissue analyses, orthogonal sectioning, and cropping. A scalar opacity mapping tool was used to enhance tissue surface borders, and anatomical structures were color‐labeled for improved 3D comprehension of the soft tissues. SR‐PCI reproduced, for the first time, the variable 3D anatomy of the human IAC, including cranial nerve complexes, anastomoses, and arachnoid membrane invagination (acoustic‐facial cistern; an extension of the cerebellopontine cistern) in unprocessed, un‐decalcified specimens. An unrecognized system of arachnoid pillars and trabeculae was found to extend between the arachnoid and cranial nerves. We confirmed earlier findings that intra‐meatal vestibular schwannoma may grow unseparated from adjacent nerves without duplication of the arachnoid layers. The arachnoid pillars may support and stabilize cranial nerves in the IAC and could also play a role in local fluid hydrodynamics.

The Incorporation of Field Portable Instrumentation Into Human Planetary Surface Exploration

AbstractField portable instrumentation, such as in situ geochemical analyzers or broader field of view instruments like multispectral imagers or other imaging capabilities, has the potential to dramatically increase the science return of a planetary surface exploration mission. However, more work is needed to determine how emerging portable technologies should be designed and implemented into evolving mission architectures. This work summarizes the efforts of the RIS4E (Remote, In Situ and Synchrotron Studies for Science and Exploration) SSERVI (Solar System Exploration Research Virtual Institute) team in investigating how field portable instruments should be including into planning for future exploration EVAs (extravehicular activities). EVA crews of geologists and astronauts tested a variety of portable and handheld technologies at both the December 1974 lava flow, Kilauea Volcano, Hawai'i, and Kilbourne Hole, New Mexico, both of which are planetary analog sites. The timeline data gathered during instrument deployment were then mapped onto EVA timelines used in large‐scale NASA planetary surface exploration analog missions. Results and recommendations for future instrument hardware and software development are discussed, as is the operational framework necessary for incorporating in situ analytical capabilities into future planetary surface exploration.

Effect of low Zn doping on the Verwey transition in magnetite single crystals: Mössbauer spectroscopy and x-ray diffraction

To observe, by microscopic probe, how low Zn doping in $\mathrm{F}{\mathrm{e}}_{3\ensuremath{-}x}\mathrm{Z}{\mathrm{n}}_{x}{\mathrm{O}}_{4}$ ($x$ is below 1%) changes the Verwey transition, we have performed M\"ossbauer spectroscopy measurements on three single crystalline samples with various Zn doping. In spectra analysis we used the recently published model of M\"ossbauer data treatment formulated as a result of ab initio calculations for a low-temperature monoclinic structure (of Cc symmetry) of magnetite. It was suggested there that the hyperfine parameters for all 24 Fe distinct positions in the lattice can be grouped into four major components with very similar hyperfine parameters within each set. Using these parameters as starting values, very good fits were obtained for magnetite with low doping level, while for higher doping, $x=0.03$, where the Verwey transition changes its character, one component is significantly different. In particular, low hyperfine field ${B}_{\mathrm{eff}}=36\phantom{\rule{0.16em}{0ex}}\mathrm{T}$, considered as a characteristic feature of the Cc phase spectrum, is absent here. Also, in this case, the high-temperature spectra are different from those for lower doped magnetite showing more pronounced continuous alteration with temperature. This might be due to crystal structure of lower than Fd-3m symmetry, a fact suggested by our x-ray synchrotron studies. All this triggered a discussion about an experimental fingerprint for the difference between these two classes of magnetite, frequently referred to as magnetite of first- and second-order Verwey transition, and about the electronic structure of both kinds of systems.

Synchrotron studies of novel Tb2Ni5C3: Crystal and electronic structure

New ternary phase Tb2Ni5C3 was gained in the three-phases sample of nominal composition after 90 d annealing at 800 °C. Crystal structure of Tb2Ni5C3 was determined using synchrotron powder diffraction: structure type La2Ni5C3, space group P4/mbm, a = 8.2372(1) Å, c = 3.83402(6) Å, RB = 5.0%; Rp = 1.8%. Crystallographic analysis and electronic structure calculations confirm the La2Ni5C3-isotypes including Tb2Ni5C3 refer to carbometalates. Metallic bonding is predominant in the R2Ni5C3 compounds. Novel La2Ni5C3-isotypic compounds were synthesized with rare earths Sm and Gd. Their unit cell parameters have been determined from X-ray powder diffraction data.