A furnace and environmental cell for the in situ investigation of molten salt electrolysis using high‐energy X‐ray diffraction

This paper describes the design, construction and implementation of a relatively large controlled‐atmosphere cell and furnace arrangement. The purpose of this equipment is to facilitate the in situ characterization of materials used in molten salt electrowinning cells, using high‐energy X‐ray scattering techniques such as synchrotron‐based energy‐dispersive X‐ray diffraction. The applicability of this equipment is demonstrated by quantitative measurements of the phase composition of a model inert anode material, which were taken during an in situ study of an operational Fray–Farthing–Chen Cambridge electrowinning cell, featuring molten CaCl₂ as the electrolyte. The feasibility of adapting the cell design to investigate materials in other high‐temperature environments is also discussed.     

Design and application of a high‐temperature microfurnace for an in situ X‐ray diffraction study of phase transformation

Thermal treatment of mineral ores such as ilmenite can initiate phase transformations that could affect their activation or deactivation, subsequently influencing their ability to dissolve in a leaching agent. Most laboratory‐based X‐ray diffraction (XRD) studies were carried out ex situ in which realistic diffraction patterns could not be obtained simultaneously with occurring reactions and were time‐consuming. The availability of synchrotron‐radiation‐based XRD not only allows in situ analysis, but significantly shortens the data recording time. The present study details the design of a robust high‐temperature microfurnace which allows thermal processing of mineral ore samples and the simultaneous collection of high‐resolution synchrotron XRD data. In addition, the application of the manufactured microfurnace for in situ study of phase transformations of ilmenite ore under reducing conditions is demonstrated.     

High‐temperature stability of suspended single‐layer graphene

We report in situ Joule heating on suspended single‐layer graphene in a transmission electron microscope (TEM). Thermally‐driven degradation of pre‐deposited nanoparticles on the membrane is monitored and used for local temperature estimation. By extrapolating the Joule heating power and temperature relation, we find that the suspended single‐layer graphene has exceptional thermal stability up to at least 2600 K. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Versatile vacuum chamber for in situ surface X‐ray scattering studies

A compact portable vacuum‐compatible chamber designed for surface X‐ray scattering measurements on beamline ID01 of the European Synchrotron Radiation Facility, Grenoble, is described. The chamber is versatile and can be used for in situ investigation of various systems, such as surfaces, nanostructures, thin films etc., using a variety of X‐ray‐based techniques such as reflectivity, grazing‐incidence small‐angle scattering and diffraction. It has been conceived for the study of morphology and structure of semiconductor surfaces during ion beam erosion, but it is also used for the study of surface oxidation or thin film growth under ultra‐high‐vacuum conditions. Coherent X‐ray beam experiments are also possible. The chamber is described in detail, and examples of its use are given.     

Performance of a fuel cell optimized for in situ X‐ray absorption experiments

A commercial fuel cell has been successfully modified to carry out X‐ray absorption spectroscopy (XAS) measurements under optimized in operando conditions. The design is conceived for the performance of XAS experiments in transmission mode over a wide range of X‐ray energies above 6 keV, owing to the reduced absorption of the cell. The wide angular aperture allows the collection of XAS in fluorescence mode and of X‐ray diffraction patterns when needed. Details of the design of the cell and its performances are given. The quality of the extended X‐ray absorption fine‐structure spectra under working conditions has been verified at the ESRF and ELETTRA synchrotron radiation facilities, showing that relatively fast and low‐noise transmission measurements on electrodes over a wide range of catalyst concentrations and energies are feasible.     

In situ detection of flavonoids in weld‐dyed wool and silk textiles by surface‐enhanced Raman scattering

Luteolin and apigenin flavonoid have been detected in silk and wool fibres dyed with weld (Reseda luteola L.) through surface‐enhanced Raman scattering (SERS) measurements carried out ‘on the fibre’. For such purpose, Ag nanoparticles were produced and immobilised in situ via the laser photoreduction of a silver nitrate water solution in contact with the fibre. Control SERS spectra of pure luteolin and apigenin, as well as of mixtures of them, on analogous Ag nanoparticles were also obtained. In this work flavonoids with a similar molecular structure were identified on dyed fibres for the first time without previously hydrolysing the mordant–dye complex. Copyright © 2008 John Wiley & Sons, Ltd.     

Novel high‐temperature reactors for in situ studies of three‐way catalysts using turbo‐XAS

Two novel high‐temperature reactors for in situ X‐ray absorption spectroscopy (XAS) measurements in fluorescence are presented, each of them being optimized for a particular purpose. The powerful combination of these reactors with the turbo‐XAS technique used in a dispersive‐XAS beamline permits the study of commercial three‐way catalysts under realistic gas composition and temporal conditions.     

Multi‐use high/low‐temperature and pressure compatible portable chamber for in situ grazing‐incidence X‐ray scattering studies

The multipurpose portable ultra‐high‐vacuum‐compatible chamber described in detail in this article has been designed to carry out grazing‐incidence X‐ray scattering techniques on the BM25‐SpLine CRG beamline at the ESRF. The chamber has a cylindrical form, built on a 360° beryllium double‐ended conflate flange (CF) nipple. The main advantage of this chamber design is the wide sample temperature range, which may be varied between 60 and 1000 K. Other advantages of using a cylinder are that the wall thickness is reduced to a minimum value, keeping maximal solid angle accessibility and keeping wall absorption of the incoming X‐ray beam constant. The heat exchanger is a customized compact liquid‐nitrogen (LN2) continuous‐flow cryostat. LN2 is transferred from a storage Dewar through a vacuum‐isolated transfer line to the heat exchanger. The sample is mounted on a molybdenum support on the heat exchanger, which is equipped with a BORALECTRIC heater element. The chamber versatility extends to the operating pressure, ranging from ultra‐high vacuum (<10^?10 mbar) to high pressure (up to 3 × 10³ mbar). In addition, it is equipped with several CF ports to allocate auxiliary components such as capillary gas‐inlet, viewports, leak valves, ion gun, turbo pump, etc., responding to a large variety of experiment requirements. A movable slits set‐up has been foreseen to reduce the background and diffuse scattering produced at the beryllium wall. Diffraction data can be recorded either with a point detector or with a bi‐dimensional CCD detector, or both detectors simultaneously. The system has been designed to carry out a multitude of experiments in a large variety of environments. The system feasibility is demonstrated by showing temperature‐dependence grazing‐incidence X‐ray diffraction and conductivity measurements on a 20 nm‐thick La_0.7Ca_0.3MnO₃ thin film grown on a SrTiO₃(001) substrate.     

锐钛矿金红石的高温原位X射线衍射研究

对TiO₂粉末进行了空气和真空条件下从室温到1200℃的加热原位X射线衍射实验, 得到了空气和真空条件下微米级锐钛矿颗粒转变为金红石的起始温度分别为850℃ 和855℃; 分别修正了空气条件下锐钛矿在(27–850℃)范围和金红石在(900–1200℃) 范围内的晶胞参数和真空条件下锐钛矿在(27–850℃)范围和金红石在(950–1200℃) 范围的晶胞参数, 从而得到了晶胞参数随温度变化的关系, 得到了锐钛矿和金红石在空气中和真空中的热膨胀系数, 并总结了热膨胀系数随温度变化的规律. 室温下锐钛矿在空气条件下的热膨胀系数为 α_a=4.55063×10^-6/℃, α_c=7.7543×10^-6/℃, β=16.85836×10^-6/℃; 真空下为 α_a=4.69429×10^-6/℃, α_c=9.02850×10^-6/℃, β=18.69688×10^-6/℃. 室温下, 金红石在空气条件下的热膨胀系数为 α_a=6.81243×10^-6/℃, α_c=8.71644×10^-6/℃, β=22.22178×10^-6/℃; 真空条件下为 α_a=6.05834×10^-6/℃, α_c= 8.39280×10^-6/℃, β=20.52362×10^-6/℃. 关键词： 2')" href="#">TiO₂ 原位X射线衍射 相转变 热膨胀     

In situ removal of carbon contamination from optics in a vacuum ultraviolet and soft X‐ray undulator beamline using oxygen activated by zeroth‐order synchrotron radiation

Carbon contamination of optics is a serious issue in all soft X‐ray beamlines because it decreases the quality of experimental data, such as near‐edge X‐ray absorption fine structure, resonant photoemission and resonant soft X‐ray emission spectra in the carbon K‐edge region. Here an in situ method involving the use of oxygen activated by zeroth‐order synchrotron radiation was used to clean the optics in a vacuum ultraviolet and soft X‐ray undulator beamline, BL‐13A at the Photon Factory in Tsukuba, Japan. The carbon contamination of the optics was removed by exposing them to oxygen at a pressure of 10^?1–10^?4 Pa for 17–20 h and simultaneously irradiating them with zeroth‐order synchrotron radiation. After the cleaning, the decrease in the photon intensity in the carbon K‐edge region reduced to 2–5%. The base pressure of the beamline recovered to 10^?7–10^?8 Pa in one day without baking. The beamline can be used without additional commissioning.     

X‐ray spectroscopic approaches to the investigation and characterization of photochemical processes

Despite a wealth of studies exemplifying the utility of the 2–5 keV X‐ray range in speciation and electronic structure elucidation, the exploitation of this energy regime for the study of photochemical processes has not been forthcoming. Herein, a new endstation set‐up for in situ photochemical soft X‐ray spectroscopy in the 2–5 keV energy region at the Stanford Synchrotron Radiation Lightsource is described for continuous photolysis under anaerobic conditions at both cryogenic and ambient temperatures. Representative examples of this approach are used to demonstrate the potential information content in several fields of study, including organometallic chemistry, biochemistry and materials chemistry.     

A flow‐through reaction cell for in situ X‐ray diffraction and absorption studies of heterogeneous powder–liquid reactions and phase transformations

A portable powder–liquid high‐corrosion‐resistant reaction cell has been designed to follow in situ reactions by X‐ray powder diffraction (XRD) and X‐ray absorption spectroscopy (XAS) techniques. The cell has been conceived to be mounted on the experimental stations for diffraction and absorption of the Spanish CRG SpLine‐BM25 beamline at the European Synchrotron Radiation Facility. Powder reactants and/or products are kept at a fixed position in a vertical geometry in the X‐ray pathway by a porous membrane, under forced liquid reflux circulation. Owing to the short pathway of the X‐ray beam through the cell, XRD and XAS measurements can be carried out in transmission configuration/mode. In the case of the diffraction technique, data can be collected with either a point detector or a two‐dimensional CCD detector, depending on specific experimental requirements in terms of space or time resolution. Crystallization processes, heterogeneous catalytic processes and several varieties of experiments can be followed by these techniques with this cell. Two experiments were carried out to demonstrate the cell feasibility: the phase transformations of layered titanium phosphates in boiling aqueous solutions of phosphoric acid, and the reaction of copper carbonate and l ‐isoleucine amino acid powders in boiling aqueous solution. In this last case the shrinking of the solid reactants and the formation of Cu(isoleucine)₂ is observed. The crystallization processes and several phase transitions have been observed during the experiments, as well as an unexpected reaction pathway.     

A curved image‐plate detector system for high‐resolution synchrotron X‐ray diffraction

The developed curved image plate (CIP) is a one‐dimensional detector which simultaneously records high‐resolution X‐ray diffraction (XRD) patterns over a 38.7° 2θ range. In addition, an on‐site reader enables rapid extraction, transfer and storage of X‐ray intensity information in ≤30 s, and further qualifies this detector to study kinetic processes in materials science. The CIP detector can detect and store X‐ray intensity information linearly proportional to the incident photon flux over a dynamical range of about five orders of magnitude. The linearity and uniformity of the CIP detector response is not compromised in the unsaturated regions of the image plate, regardless of saturation in another region. The speed of XRD data acquisition together with excellent resolution afforded by the CIP detector is unique and opens up wide possibilities in materials research accessible through X‐ray diffraction. This article presents details of the basic features, operation and performance of the CIP detector along with some examples of applications, including high‐temperature XRD.     

A facile heating cell for in situ transmittance and fluorescence X‐ray absorption spectroscopy investigations

A facile heating cell has been designed for in situ transmittance and fluorescence X‐ray absorption spectroscopy (XAS) measurements up to 1273 K under vacuum or an inert atmosphere. These high temperatures are achieved using a tantalum heating element by ohmic heating. Because of the small specific heat capacity, the temperature can be changed in a matter of minutes from room temperature to high temperature. Furthermore, a commercial power controller was adapted to provide stable temperature control. The construction of the heat shielding system provides a novel approach to reducing the beam's path length and the cell's size. The cell is inexpensive and easy to build. Its performance was evaluated by in situ XAS measurements of the temperature‐dependent structure of ceria nanocrystals. Some preliminary results for the structural mechanism in ceria nanocrystal redox applications are given.     

In situ monitoring of styrene polymerization using Raman spectroscopy. Multi‐scale approach of homogeneous and heterogeneous polymerization processes

Free radical polymerization of styrene was monitored in situ by combining Raman spectroscopy to other experimental techniques (gravimetry and rheology). Three different processes were investigated: bulk, emulsion and miniemulsion polymerization. A complete analysis of the evolution of Raman spectrum during the course of reaction showed that a lot of information about molecular dynamics could be extracted and related to chemical phenomena. In addition, we report for the first time the coupling of Raman spectroscopy to a rheometer in order to monitor styrene bulk polymerization both at the scale of chemical bonds and at the scale of macroscopic phenomena (viscosity variation). Copyright © 2013 John Wiley & Sons, Ltd.     

High temperature Raman study of UO2: A possible tool for in situ estimation of irradiation‐induced heating

Recently, in situ Raman setups under irradiation become available, and uranium dioxide is one of the most studied compounds. This paper reports the temperature dependence of the only Raman‐active mode in fluorine UO₂. Besides the interest in terms of phonon anharmonicity knowledge, this can be used to estimate the heating induced by irradiation: The frequency shift and width of the T_2g peak can be used as an internal indirect probe of the local temperature in the 20–590 °C range. Copyright © 2015 John Wiley & Sons, Ltd.     

Design and development of a controlled pressure/temperature set‐up for in situ studies of solid–gas processes and reactions in a synchrotron X‐ray powder diffraction station

A novel set‐up has been designed and used for synchrotron radiation X‐ray high‐resolution powder diffraction (SR‐HRPD) in transmission geometry (spinning capillary) for in situ solid–gas reactions and processes in an isobaric and isothermal environment. The pressure and temperature of the sample are controlled from 10^?3 to 1000 mbar and from 80 to 1000 K, respectively. To test the capacities of this novel experimental set‐up, structure deformation in the porous material zeolitic imidazole framework (ZIF‐8) by gas adsorption at cryogenic temperature has been studied under isothermal and isobaric conditions. Direct structure deformations by the adsorption of Ar and N₂ gases have been observed in situ, demonstrating that this set‐up is perfectly suitable for direct structural analysis under in operando conditions. The presented results prove the feasibility of this novel experimental station for the characterization in real time of solid–gas reactions and other solid–gas processes by SR‐HRPD.     

In situ three‐dimensional reciprocal‐space mapping during mechanical deformation

Mechanical deformation of a SiGe island epitaxically grown on Si(001) was studied by a specially adapted atomic force microscope and nanofocused X‐ray diffraction. The deformation was monitored during in situ mechanical loading by recording three‐dimensional reciprocal‐space maps around a selected Bragg peak. Scanning the energy of the incident beam instead of rocking the sample allowed the safe and reliable measurement of the reciprocal‐space maps without removal of the mechanical load. The crystal truncation rods originating from the island side facets rotate to steeper angles with increasing mechanical load. Simulations of the displacement field and the intensity distribution, based on the finite‐element method, reveal that the change in orientation of the side facets of about 25° corresponds to an applied pressure of 2–3 GPa on the island top plane.     

Evolution of the Raman backscattered intensity used to analyze the micromechanisms of deformation of various polypropylene blends in situ during a uniaxial tensile test

This paper presents a study of the evolution of the Raman backscattered intensity used to follow the modifications of polymer microstructure in real time during a tensile test. The context of this study is the coupling of the VideoTraction™ system with a Raman spectrometer, which has already led to in‐situ measurements of molecular chains orientation and crystallinity. The polypropylene blends will be characterized optically at the same probing wavelength by incoherent light scattering to understand phenomena enlightened by Raman spectroscopy. Then, a discussion on the Raman intensity evolution is conducted, with the possible contribution of Raman spectroscopy to describe stages of the volume damage micromechanism. Copyright © 2014 John Wiley & Sons, Ltd.