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- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 6. |
- Marçal, L. A.B., et al.
(författare)
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Structural and chemical properties of anion exchanged CsPb(Br(1−x)Cl x )3 heterostructured perovskite nanowires imaged by nanofocused x-rays
- 2024
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Ingår i: Nanotechnology. - 0957-4484. ; 35:26
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Tidskriftsartikel (refereegranskat)abstract
- Over the last years metal halide perovskites have demonstrated remarkable potential for integration in light emitting devices. Heterostructures allow for tunable bandgap depending on the local anion composition, crucial for optoelectronic devices, but local structural effects of anion exchange in single crystals is not fully understood. Here, we investigate how the anion exchange of CsPbBr3 nanowires fully and locally exposed to HCl vapor affects the local crystal structure, using nanofocused x-rays. We study the nanoscale composition and crystal structure as function of HCl exposure time and demonstrate the correlation of anion exchange with changes in the lattice parameter. The local composition was measured by x-ray fluorescence and x-ray diffraction, with general agreement of both methods but with much less variation using latter. The heterostructured nanowires exhibit unintentional gradients in composition, both axially and radially. Ferroelastic domains are observed for all HCl exposure times, and the magnitude of the lattice tilt at the domain walls scales with the Cl concentration.
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| 7. |
- A. B. Marçal, L., et al.
(författare)
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Spatially resolved structural and chemical properties of the white layer in machined Inconel 718 super alloy
- 2024
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Ingår i: Materials and Design. - 0264-1275. ; 239
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Tidskriftsartikel (refereegranskat)abstract
- Inconel 718 is one type of nickel-based alloy used for a large range of applications, including gas turbines and aeroengines components. Although mechanical and thermodynamic properties of this material have been deeply studied in the past years, a method able to investigate local properties of the thin white layer formed on the alloy surface after machining remains challenging. Here, a 90 nm X-ray beam is used to probe the local strain, crystal orientation, and chemical composition of grains in the white layer. Data reveals mosaicity induced by the tool during machining. The high spatial resolution, combined with crystal lattice sensitivity, shows that the average grain size is around 30 nm throughout the white layer, while the strain is anisotropic nearest to the surface. Results provide new insights on the basic properties of the white layer in super alloys, revealing important information about the impact of finish machining which might help to explain fatigue and cracking formation on these materials during their usage phase.
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| 8. |
- Dzhigaev, D, et al.
(författare)
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Three-dimensional coherent x-ray diffraction imaging of ferroelastic domains in single CsPbBr3 perovskite nanoparticles
- 2021
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 23:6
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Tidskriftsartikel (refereegranskat)abstract
- Metal halide perovskites attract significant interest due to their remarkable performance in optoelectronic devices. However, the gap in understanding the relationship between their nanoscale structure and properties limits their application towards novel devices. In this work, twinned ferroelastic domains in single 500 nm CsPbBr3 particles are studied with 3D Bragg coherent x-ray diffraction imaging. A preferential double-domain structure is revealed in four identical particles, with one domain oriented along the [110] and the other along the [002] direction. The particles exhibit similar scattering volume ratios of 0.12 0.026 between twin phases, suggesting the possibility of a deterministic formation process. The domains exhibit a difference in lattice tilt of 0.59 degrees, in excellent agreement with calculations of the lattice mismatch at the (112) twin boundary. These results provide important insights both for the fundamental understanding of ferroelastic nanoscale materials and for the performance improvement of perovskite-based devices. Moreover, this work paves the way towards real-time imaging of the domain dynamics in ferroic systems.
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| 9. |
- Antoniazzi, Igor, et al.
(författare)
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Oxygen intercalated graphene on SiC(0001) : Multiphase SiOx layer formation and its influence on graphene electronic properties
- 2020
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 167, s. 746-759
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Tidskriftsartikel (refereegranskat)abstract
- Low-dimensionality materials are highly susceptible to interfaces. Indeed, intercalation of different chemical species in between epitaxial graphene and silicon carbide (SiC), for instance, may decouple the graphene with respect to the substrate due to the conversion of the buffer layer into a graphene layer. O-intercalation is known to release the strain of such 2D material and to lead to the formation of high structural quality AB-stacked bilayer graphene. Nonetheless, this interface transformation concomitantly degrades graphene electronic transport properties. In this work we employed different techniques in order to better understand the structure of the graphene/SiC interface generated by O-intercalation and to elucidate the origin of the poor electronic properties of graphene. Experimental results revealed the formation of a SiO2 rich layer with a defective transition layer in between it and the SiC, which is characterized by the existence of silicon oxycarbide structures. Scanning tunneling spectroscopy measurements revealed an extensive presence of electronic states just around the Fermi level all over the sample surface, which may suppress the charge carriers mobility around this region. According to theoretical calculations, such states are mainly due to the formation of silicon oxicarbides within the interfacial layer.
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| 10. |
- de Oliveira, Raphaela, et al.
(författare)
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Water Nanochannels in Ultrathin Clinochlore Phyllosilicate Mineral with Ice-like Behavior
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Ingår i: Journal of Physical Chemistry C. - 1932-7447.
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Tidskriftsartikel (refereegranskat)abstract
- Water is the matrix of life, and its confinement in nanocavities is a central topic from geophysics to nanotribology. Phyllosilicate layered minerals provide natural nanocavities for water due to their capacity to hydrate by confining water molecules in the interlamellar space. However, the hydration of phyllosilicates at the nanoscale is not a fully understood process and depends on the geological specimens. In this work, we report the formation of aqueous nanochannels in the interlamellar space of ultrathin clinochlore phyllosilicate mineral using infrared scattering-type scanning near-field optical microscopy and Kelvin probe force microscopy. We demonstrate that nanoconfinement of water in clinochlore changes the overall mechanical, optical, and dielectric properties of the system. We propose a capacitive model that describes the dielectric response of the aqueous nanochannels. Our model is endorsed by a robust crystal truncation rod analysis of synchrotron X-ray diffraction data. We found that clinochlore termination combines hydrated structures ordered along the c-axis. We also find evidence of ice-like behavior of the water nanoconfined in clinochlore by Fourier-transform infrared spectroscopy. Notably, our work introduces clinochlore as a natural platform for water confinement in two-dimensional systems that can be engineered for several applications in the frontiers of nanotechnology.
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