| 1. |
- Brunatova, Ereza, et al.
(författare)
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Thermal stability of titanate nanorods and titania nanowires formed from titanate nanotubes by heating
- 2014
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Ingår i: Materials Characterization. - : Elsevier BV. - 1044-5803 .- 1873-4189. ; 98, s. 26-36
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Tidskriftsartikel (refereegranskat)abstract
- The structure of titanate nanowires was studied by a combination of powder X-ray diffraction (XRD) and 3D precession electron diffraction. Titania nanowires and titanate nanorods were prepared by heating of titanate nanotubes. The structure of final product depended on heating conditions. Titanium nanotubes heated in air at a temperature of 850 degrees C decomposed into three phases Na2Ti6O13 (nanorods) and two phases of TiO2 anatase and rutile. At higher temperatures the anatase form of TiO2 transforms into rutile and the nanorods change into rutile nanoparticles. By contrast, in the vacuum only anatase phases of TiO2 were obtained by heating at 900 degrees C. The anatase transformation into ruffle began only after a longer time of heating at 1000 degrees C. For the description of anisotropic XRD line broadening in the total powder pattern fitting by the program MSTRUCT a model of nanorods with elliptical base was included in the software. The model parameters rod length, axis size of the elliptical base, the ellipse flattening parameter and twist of the base could be refined. Variation of particle shapes with temperature was found.
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| 2. |
- Carbone, Dina, et al.
(författare)
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Design and performance of a dedicated coherent X-ray scanning diffraction instrument at beamline NanoMAX of MAX IV
- 2022
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Ingår i: Journal of Synchrotron Radiation. - 1600-5775. ; 29, s. 876-887
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Tidskriftsartikel (refereegranskat)abstract
- The diffraction endstation of the NanoMAX beamline is designed to provide high-flux coherent X-ray nano-beams for experiments requiring many degrees of freedom for sample and detector. The endstation is equipped with high-efficiency Kirkpatrick-Baez mirror focusing optics and a two-circle goniometer supporting a positioning and scanning device, designed to carry a compact sample environment. A robot is used as a detector arm. The endstation, in continued development, has been in user operation since summer 2017.
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| 3. |
- Cedervall, Johan, et al.
(författare)
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Magnetostructural transition in Fe5SiB2 observed with neutron diffraction
- 2016
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Ingår i: Journal of Solid State Chemistry. - : Elsevier BV. - 0022-4596 .- 1095-726X. ; 235, s. 113-118
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Tidskriftsartikel (refereegranskat)abstract
- The crystal and magnetic structure of Fe5SiB2 has been studied by a combination of X-ray and neutron diffraction. Also, the magnetocrystalline anisotropy energy constant has been estimated from magnetisation measurements. High quality samples have been prepared using high temperature synthesis and subsequent heat treatment protocols. The crystal structure is tetragonal within the space group I4/mcm and the compound behaves ferromagnetically with a Curie temperature of 760 K. At 172 K a spin reorientation occurs in the compound and the magnetic moments go from aligning along the c-axis (high T) down to the ab-plane (low T). The magnetocrystalline anisotropy energy constant has been estimated to 0.3 MJ/m3 at 300 K.
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| 4. |
- Clemens, Anna, 1986, et al.
(författare)
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Reaction-driven Ion Exchange of Copper into Zeolite SSZ-13
- 2015
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Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 5:10, s. 6209-6218
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Tidskriftsartikel (refereegranskat)abstract
- We have used several techniques to characterize Cu-SSZ-13 before and after exposure to reaction conditions relevant for NO reduction by NH3-SCR to address the increase in NH3-SCR activity observed as a function of time on stream. Specifically, we focus on characterizing copper species in samples prepared with solid state ion exchange (SSIE) having varying Cu loadings from 0.7 to 5.2 wt %. X-ray diffraction shows that CuO species that likely remain from the SSIE synthesis on the outside of the zeolite crystallites are significantly reduced by exposure to reaction conditions. High-resolution X-ray diffraction (HR-XRD) further reveals a corresponding increase of Cu2O species. X-ray photoelectron, Auger electron, and ultraviolet -visible spectroscopy show an increase in both Cu(II) and Cu(I) species inside the zeolite pores, with a preserved long-range order of the zeolite structure as revealed by HR-XRD.
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| 5. |
- Fang, Hailiang, et al.
(författare)
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Insights into formation and stability of tau-MnAlZ(x) (Z = C and B)
- 2017
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 692, s. 198-203
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Tidskriftsartikel (refereegranskat)abstract
- The tau-phase MnAl alloys are promising candidate for rare earth free permanent magnets. In this study, In order to better understand the MnAl epsilon ->tau phase transition mechanism in a continuous cooling process and metastable MnAl tau-phase high temperature stability, Mn0.54Al0.46, Mn0.55Al0.45C0.02 and Mn0.55Al0.45B0.02 alloys were systematically studied by in situ synchrotron X-ray powder diffraction (SR-XRD). The relationship between tau-phase formation tendency and different cooling rates of Mn0.55Al0.45C0.02 was investigated. Besides, the high temperature stabilities of undoped tau-MnAl and carbon/boron doped tau-MnAl were studied. Differential thermal analysis (DTA) was also employed to study the phase transformation as well. The research results show that a high cooling rate of 600 degrees C/min leads to a 50/50 wt% mixture of epsilon- and tau-phase; almost pure tau-phase was obtained when cooled at a moderate cooling rate of 10 degrees C/min; while for a slow cooling rate of 2 degrees C/min, the tau-phase partially decomposed into beta and gamma(2) phases. No intermediate epsilon'-phase was observed during the epsilon ->tau phase transition during the experiments. For the boron and carbon doped tau-MnAl, the 800 degrees C high temperature stability experiments reveal that C stabilizes the tau-MnAl while doped B destabilises the tetragonal structure and it decomposes into beta- and gamma(2)-phases.
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| 6. |
- Havela, Ladislav, et al.
(författare)
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Strong 5f Ferromagnetism in UH3-Based Materials
- 2016
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Ingår i: MRS Advances. - : Springer Science and Business Media LLC. - 2059-8521. ; 1:44, s. 2987-2992
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Tidskriftsartikel (refereegranskat)abstract
- Several diverse types of UH3-based hydrides can be prepared by hydrogenation of bcc U-based alloys. Pair Distribution Function (PDF) analysis using high-energy X-rays identified that the (UH3)1-xMo x hydrides are nanocrystalline, with the structure motif based mainly on the β-UH3 structure. α-UH3 represents a minority component. On the other hand, PDF of the (UH3)1-xZr x hydrides corresponds well to the α-UH3 crystal structure. All the hydrides are ferromagnetic, with the Curie temperature T C reaching up to 203 K.
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| 7. |
- Johansson, Ulf, et al.
(författare)
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NanoMAX : the hard X-ray nanoprobe beamline at the MAX IV Laboratory
- 2021
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Ingår i: Journal of Synchrotron Radiation. - : International Union of Crystallography (IUCr). - 0909-0495 .- 1600-5775. ; 28, s. 1935-1947
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Tidskriftsartikel (refereegranskat)abstract
- NanoMAX is the first hard X-ray nanoprobe beamline at the MAX IV laboratory. It utilizes the unique properties of the world's first operational multi-bend achromat storage ring to provide an intense and coherent focused beam for experiments with several methods. In this paper we present the beamline optics design in detail, show the performance figures, and give an overview of the surrounding infrastructure and the operational diffraction endstation.
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| 8. |
- Kovacs, Gabor G., et al.
(författare)
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Multisite Assessment of Aging-Related Tau Astrogliopathy (ARTAG)
- 2017
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Ingår i: Journal of Neuropathology and Experimental Neurology. - : Oxford University Press (OUP). - 0022-3069 .- 1554-6578. ; 76:7, s. 605-619
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Tidskriftsartikel (refereegranskat)abstract
- Aging-related tau astrogliopathy (ARTAG) is a recently introduced terminology. To facilitate the consistent identification of ARTAG and to distinguish it from astroglial tau pathologies observed in the primary frontotemporal lobar degeneration tauopathies we evaluated how consistently neuropathologists recognize (1) different astroglial tau immunoreactivities, including those of ARTAG and those associated with primary tauopathies (Study 1); (2) ARTAG types (Study 2A); and (3) ARTAG severity (Study 2B). Microphotographs and scanned sections immunostained for phosphorylated tau (AT8) were made available for download and preview. Percentage of agreement and kappa values with 95% confidence interval (CI) were calculated for each evaluation. The overall agreement for Study 1 was > 60% with a kappa value of 0.55 (95% CI 0.433-0.645). Moderate agreement (> 90%, kappa 0.48, 95% CI 0.457-0.900) was reached in Study 2A for the identification of ARTAG pathology for each ARTAG subtype (kappa 0.37-0.72), whereas fair agreement (kappa 0.40, 95% CI 0.341-0.445) was reached for the evaluation of ARTAG severity. The overall assessment of ARTAG showed moderate agreement (kappa 0.60, 95% CI 0.534-0.653) among raters. Our study supports the application of the current harmonized evaluation strategy for ARTAG with a slight modification of the evaluation of its severity.
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| 9. |
- Kriegner, Dominik, et al.
(författare)
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Powder diffraction in Bragg-Brentano geometry with straight linear detectors.
- 2015
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Ingår i: Journal of Applied Crystallography. - 1600-5767. ; 48:Pt 2, s. 613-618
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Tidskriftsartikel (refereegranskat)abstract
- A common way of speeding up powder diffraction measurements is the use of one- or two-dimensional detectors. This usually goes hand in hand with worse resolution and asymmetric peak profiles. In this work the influence of a straight linear detector on the resolution function in the Bragg-Brentano focusing geometry is discussed. Because of the straight nature of most modern detectors geometrical defocusing occurs, which heavily influences the line shape of diffraction lines at low angles. An easy approach to limit the resolution-degrading effects is presented. The presented algorithm selects an adaptive range of channels of the linear detector at low angles, resulting in increased resolution. At higher angles the whole linear detector is used and the data collection remains fast. Using this algorithm a well behaved resolution function is obtained in the full angular range, whereas using the full linear detector the resolution function varies within one pattern, which hinders line-shape and Rietveld analysis.
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| 10. |
- Lang, Jaroslav, et al.
(författare)
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Crystallization of Zr0.1Ti0.9On mixed oxide by pressurized hot water and its effect on microstructural properties and photoactivity
- 2018
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Ingår i: Journal of Supercritical Fluids. - : Elsevier BV. - 0896-8446. ; 141, s. 39-48
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Tidskriftsartikel (refereegranskat)abstract
- Pressurized hot water crystallization was applied and optimized for preparation of photoactive Zr0.1Ti0.9On mixed oxide. The effect of individual processing conditions (temperature, pressure and water amount) on (micro)structure, textural, optical, electronic and photocatalytic properties in Acid orange 7 photodegradation of prepared Zr0.1Ti0.9On mixed oxide was examined. It was revealed that while the processing temperature had crucial effect on crystallization of Zr0.1Ti0.9On mixed oxide and anatase crystallites growth, the volume of water and pressure did not show any effect. Nevertheless, it was found that pressure as well as temperature had strong influence on formation of anatase lattice defects of different type and amount and led to changes in mixed oxide photoactivity. The optimal processing conditions leading to the most photoactive Zr0.1Ti0.9On mixed oxide were determined to be 2L of water, 250 °C and 10 MPa.
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