A new multipurpose diffractometer PILATUS@SNBL Dyadkin, Vadim; Pattison, Philip; Dmitriev, Vladimir ...
Journal of synchrotron radiation,
20/May , Letnik:
23, Številka:
3
Journal Article
Recenzirano
The diffraction beamline BM01A at the European Synchrotron Radiation Facility (CRG Swiss–Norwegian beamlines) has been successfully operational for 20 years. Recently, a new multifunctional ...diffractometer based on the Dectris Pilatus 2M detector has been constructed, commissioned and offered to users. The diffractometer combines a fast and low‐noise area detector, which can be tilted and moved horizontally and vertically, together with flexible goniometry for sample positioning and orientation. The diffractometer is controlled by a user‐friendly and GUI‐based software Pylatus which is also used to control various auxiliary equipment. The latter includes several heating and cooling devices, in situ cells and complimentary spectroscopic tools.
A new multifunctional diffractometer based on the Dectris Pilatus 2M detector has been constructed, commissioned and offered to users. The diffractometer combines a fast and low‐noise area detector together with flexible goniometry for sample and detector positioning and orientation.
The ability to tune thin oxide coatings by wet-chemistry is desirable for many applications, yet it remains a key synthetic challenge. In this work, we introduce a general colloidal atomic layer ...deposition (c-ALD) synthesis to grow an alumina shell with tunable thickness around nanocrystalline cores of various compositions spanning from ionic semiconductors (i.e., CsPbX3, with X = Br, I, Cl) to metal oxides and metals (i.e., CeO2 and Ag). The distinctive characteristics of each core (i.e., emission, facile surface functionalization, stability) allowed us to optimize and to elucidate the chemistry of the c-ALD process. Compared to gas-phase ALD, this newly developed synthesis has the advantage of preserving the colloidal stability of the nanocrystalline core while controlling the shell thickness from 1 to 6 nm. As one example of the opportunities offered by the growth of a thin oxide shell, we study the anion exchange reaction in the CsPbX3 perovskites nanocrystals by in situ X-ray diffraction, which had been impeded so far by the instability of this class of materials and by the fast exchange kinetics.
This article discusses the received signal reception algorithm under conditions of multipath propagation of radio waves. As well as an analytical expression of the effectiveness of this algorithm is ...derived from the point of view of SNR.
The Al-substituted LiTi2(PO4)3 powders Li1+x Al x Ti2–x (PO4)3 (LATP) were successfully prepared by a water-based sol–gel process with subsequent calcination and sintering. The crystal structure of ...obtained samples was characterized at different temperatures using high-resolution synchrotron-based X-ray and neutron powder diffraction. Possible lithium diffusion pathways were initially evaluated using the difference bond-valence approach. Experimental 3D lithium diffusion pathway in LATP was extracted from the negative nuclear density maps reconstructed by the maximum entropy method. Evaluation of the energy landscape determining the lithium diffusion process in NASICON-type superionic conductor is shown for the first time.
Crystallization from amorphous phases is an emerging pathway for making advanced materials. Biology has made use of amorphous precursor phases for eons and used them to produce structures with ...remarkable properties. Herein, we show how the design of the amorphous phase greatly influences the nanocrystals formed therefrom. We investigate the transformation of mixed amorphous calcium phosphate/amorphous calcium carbonate phases into bone‐like nanocrystalline apatite using in situ synchrotron X‐ray diffraction and IR spectroscopy. The speciation of phosphate was controlled by pH to favor HPO42−. In a carbonate free system, the reaction produces anisotropic apatite crystallites with large aspect ratios. The first formed crystallites are highly calcium deficient and hydrogen phosphate rich, consistent with thin octacalcium phosphate (OCP)‐like needles. During growth, the crystallites become increasingly stoichiometric, which indicates that the crystallites grow through addition of near‐stoichiometric apatite to the OCP‐like initial crystals through a process that involves either crystallite fusion/aggregation or Ostwald ripening. The mixed amorphous phases were found to be more stable against phase transformations, hence, the crystallization was inhibited. The resulting crystallites were smaller and less anisotropic. This is rationalized by the idea that a local phosphate‐depletion zone formed around the growing crystal until it was surrounded by amorphous calcium carbonate, which stopped the crystallization.
Let it grow! The kinetics of the apatite formation from hydrogen‐phosphate‐rich amorphous calcium phosphate with and without added carbonate is studied by a range of in situ techniques. Seeds of hydrogen‐phosphate‐rich apatite, akin to a few layers of octacalcium phosphate, form first and are overgrown by more stoichiometric apatite (see figure).
Materials science of metal open frameworks is a state‐of‐the‐art field for numerous applications, such as gas storage, sensors, and medicine. Two nanoporous frameworks, γ‐Mg(BH4)2 and MIL‐91(Ti), ...with different levels of structural flexibility, were examined with in situ X‐ray diffraction guest adsorption–desorption experiments. Both frameworks exhibit a cooperative guest adsorption correlated with a lattice deformation. This cooperativity originates from the long‐range interactions between guest molecules, mediated by elastic response of the host porous structure. The observed experimental scenarios are rationalized with a mean field Gorsky–Bragg–Williams (GBW) approach for the lattice‐gas Ising model. The adjusted GBW model, in combination with in situ synchrotron powder diffraction, demonstrates an efficient experimental and phenomenological approach to characterize thermodynamics of the adsorption in MOFs not only for the total uptake but also for every specific guest site.
Cooperate! The elastic response of guest adsorption into γ‐Mg(BH4)2 and MIL‐91(Ti) nanoporous frameworks were examined with in situ synchrotron X‐ray diffraction and analyzed with an adjusted mean field Gorsky–Bragg–Williams (GBW) approach for the lattice‐gas Ising model. The applied methods allow the determination of the thermodynamics of the guest adsorption in MOFs, not only for the total uptake but also for every specific guest site.
Performing under pressure: The BH4 group in the high‐pressure modification of LiBH4 has an unprecedented square‐planar coordination by four Li atoms (see picture). This structure exhibits a ...strikingly short H⋅⋅⋅H contact between adjacent BH4 anions and thus may show completely different hydrogen‐storage properties if stabilized by chemical substitution at ambient pressure.
We suggest a new alternative model of positron origin in the Galaxy. It is shown in our model that interactions of the electromagnetic fields of colliding ions (ultraperipheral ion collisions) can ...contribute to the total production of Galactic positrons. The corresponding cross-section is estimated by using the Born approximation and the equivalent photon method. This process of ion collisions dominates in the range of subrelativistic energies and produces positrons with energies of several MeV. Despite its low efficiency, as it requires more than 0.1 erg to produce a single positron, this process may be an effective source of positrons in the Galactic medium.
The prototype piezoelectric material BaTiO
3
is widely used in e.g., capacitators. Chemical solution deposition (CSD) of BaTiO
3
films is a simple and environmentally friendly processing route, but ...insight in the crystallization process is crucial to tailor the film properties. In this work, the influence of the annealing conditions on the crystallization behavior of BaTiO
3
thin films from
aqueous
chemical solution deposition is presented. In situ synchrotron X-ray diffraction was used to reveal the phase evolution, crystallization of the films, and to study how the degree of crystallographic texture in the polycrystalline films evolved. Our results revealed that the formation of an intermediate metastable oxycarbonate phase is critical for the formation of BaTiO
3
thin films prepared by aqueous CSD. The pyrolysis products present in the film before crystallization determine the degree of preferential orientation and by tuning the heating program, especially the heating rate through nucleation (<0.2 °C/s), control of the microstructure and degree of preferential orientation in the films was demonstrated.
In situ X-ray diffraction patterns of a BaTiO
3
film, prepared by spin coating of an aqueous chemical solution, as a function of time and temperature, showing the phase evolution and crystallization of BaTiO
3
.
Highlights
In situ synchrotron X-ray diffraction revealed the phase evolution and crystallization of BaTiO
3
films prepared by aqueous CSD.
An intermediate metastable oxycarbonate phase is critical for the formation of BaTiO
3
thin films.
The pyrolysis process determines the degree of preferential orientation in the films.
The microstructure and preferential orientation of the BaTiO
3
films can be tailored by the new insight.
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