Hydrogen Interaction with Defects in Nanocrystalline, Polycrystalline and Epitaxial Pd Films

2013 ◽  
Vol 26 ◽  
pp. 123-133 ◽  
Author(s):  
Jakub Čížek ◽  
Oksana Melikhova ◽  
Marián Vlček ◽  
František Lukáč ◽  
Martin Vlach ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Structural Changes ◽  
High Stress ◽  
Positron Annihilation Spectroscopy ◽  
Structural Development ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Interaction

Hydrogen interaction with defects and structural development of Pd films with various microstructures were investigated. Nanocrystalline, polycrystalline and epitaxial Pd films were prepared and electrochemically loaded with hydrogen. Structural changes of Pd films caused by absorbed hydrogen were studied by in-situ X-ray diffraction combined with acoustic emission and measurement of electromotorical force. Development of defects during hydrogen loading was investigated by positron annihilation spectroscopy. It was found that hydrogen firstly fills open volume defects existing already in the films and subsequently it occupies also interstitial sites in Pd lattice. Absorbed hydrogen causes volume expansion, which is strongly anisotropic in thin films. This introduces high stress into the films loaded with hydrogen. Acoustic emission measurements revealed that when hydrogen-induced stress achieves a certain critical level rearrangement of misfit dislocations takes place. The stress which grows with increasing hydrogen concentration can be further released by plastic deformation and also by detachment of the film from the substrate.

scholarly journals High temperature structural study of decagonal Al-Cu-Rh quasicrystal.

2014 ◽  
Vol 70 (a1) ◽  
pp. C94-C94
Author(s):  
Pawel Kuczera ◽  
Walter Steurer
Keyword(s):  
Structural Changes ◽  
Configurational Entropy ◽  
Lattice Vibrations ◽  
X Ray Diffraction ◽  
Stabilization Mechanism ◽  
X Ray ◽  
Comparative Structure ◽  
The Stability

The structure of d(ecagonal)-Al-Cu-Rh has been studied as a function of temperature by in-situ single-crystal X-ray diffraction in order to contribute to the discussion on energy or entropy stabilization of quasicrystals (QC) [1]. The experiments were performed at 293 K, 1223 K, 1153 K, 1083 K, and 1013 K. A common subset of 1460 unique reflections was used for the comparative structure refinements at each temperature. The results obtained for the HT structure refinements of d-Al-Cu-Rh QC seem to contradict a pure phasonic-entropy-based stabilization mechanism [2] for this QC. The trends observed for the ln func(I(T1 )/I(T2 )) vs.|k⊥ |^2 plots indicate that the best on-average quasiperiodic order exists between 1083 K and 1153 K, however, what that actually means is unclear. It could indicate towards a small phasonic contribution to entropy, but such contribution is not seen in the structure refinements. A rough estimation of the hypothetic phason instability temperature shows that it would be kinetically inaccessible and thus the phase transition to a 12 Å low T structure (at ~800 K) is most likely not phason-driven. Except for the obvious increase in the amplitude of the thermal motion, no other significant structural changes, in particular no sources of additional phason-related configurational entropy, were found. All structures are refined to very similar R-values, which proves that the quality of the refinement at each temperature is the same. This suggests, that concerning the stability factors, some QCs could be similar to other HT complex intermetallic phases. The experimental results clearly show that at least the ~4 Å structure of d-Al-Cu-Rh is a HT phase therefore entropy plays an important role in its stabilisation mechanism lowering the free energy. However, the main source of this entropy is probably not related to phason flips, but rather to lattice vibrations, occupational disorder unrelated to phason flips like split positions along the periodic axis.

Size dependent behavior of Fe3O4crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

2017 ◽  
Vol 19 (31) ◽  
pp. 20867-20880 ◽  
Author(s):  
David C. Bock ◽  
Christopher J. Pelliccione ◽  
Wei Zhang ◽  
Janis Timoshenko ◽  
K. W. Knehr ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Dependent Behavior ◽  
X Ray Absorption

Crystal and atomic structural changes of Fe3O4upon electrochemical (de)lithiation were determined.

Hydrogen Interaction with Defects in ZnO

2012 ◽  
Vol 733 ◽  
pp. 228-231 ◽  
Author(s):  
František Lukáč ◽  
Jakub Čížek ◽  
Marián Vlček ◽  
Ivan Procházka ◽  
Martin Vlach ◽  
...  
Keyword(s):  
Subsurface Layer ◽  
Positron Annihilation Spectroscopy ◽  
Nuclear Reaction Analysis ◽  
X Ray Diffraction ◽  
High Concentration ◽  
X Ray ◽  
Low Concentrations ◽  
Hydrogen Interaction ◽  
Induced Stresses ◽  
Zno Crystal

In the present work hydrothermally grown ZnO single crystals were electrochemically charged with hydrogen. The influence of hydrogen on ZnO microstructure was investigated by positron annihilation spectroscopy (PAS) combined with X-ray diffraction (XRD) using synchrotron radiation. Hydrogen concentration in the samples was determined by nuclear reaction analysis (NRA). It was found that a high concentration of hydrogen can be introduced into ZnO by electrochemical loading. At low concentrations, absorbed hydrogen causes elastic volume expansion of ZnO crystal. At higher concentration, hydrogen-induced stresses exceed the yield stress in ZnO and plastic deformation of the crystal takes place leading to formation of a defected subsurface layer in the crystals.

scholarly journals In situ X-ray diffraction computed tomography studies examining the thermal and chemical stabilities of working Ba0.5Sr0.5Co0.8Fe0.2O3−δ membranes during oxidative coupling of methane

2020 ◽  
Vol 22 (34) ◽  
pp. 18964-18975
Author(s):  
Dorota Matras ◽  
Antonis Vamvakeros ◽  
Simon D. M. Jacques ◽  
Vesna Middelkoop ◽  
Gavin Vaughan ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Solid State ◽  
Oxidative Coupling ◽  
Structural Changes ◽  
Oxidative Coupling Of Methane ◽  
Membrane Reactors ◽  
Solid State Chemistry ◽  
X Ray Diffraction ◽  
X Ray

In situ XRD-CT and post-reaction SEM/EDX were used to study the solid-state chemistry and structural changes of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane reactors during the oxidative coupling of methane reaction.

Study of Structural Changes in LiNi0.8Co0.1Mn0.1O2 Cathode Material for Lithium-Ion Batteries by X-Ray Diffraction Analysis in the In Situ Mode

2019 ◽  
Vol 92 (7) ◽  
pp. 1013-1019 ◽  
Author(s):  
P. A. Novikov ◽  
A. E. Kim ◽  
K. A. Pushnitsa ◽  
Wang Quingsheng ◽  
M. Yu. Maksimov ◽  
...  
Keyword(s):  
Cathode Material ◽  
Diffraction Analysis ◽  
Lithium Ion Batteries ◽  
Structural Changes ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
X Ray

Structural changes of Ce–Pr–O oxides in hydrogen: a study by in situ X-ray diffraction and Raman spectroscopy

2003 ◽  
Vol 13 (12) ◽  
pp. 3017-3020 ◽  
Author(s):  
Sylvie Rossignol ◽  
Francois Gérard ◽  
Danielle Mesnard ◽  
Charles Kappenstein ◽  
Daniel Duprez
Keyword(s):  
Raman Spectroscopy ◽  
Structural Changes ◽  
X Ray Diffraction ◽  
X Ray

Structural changes during tensile testing of an all-cellulose composite by in situ synchrotron X-ray diffraction

2006 ◽  
Vol 66 (15) ◽  
pp. 2639-2647 ◽  
Author(s):  
Wolfgang Gindl ◽  
Klaus J. Martinschitz ◽  
Peter Boesecke ◽  
Jozef Keckes
Keyword(s):  
Tensile Testing ◽  
Structural Changes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cellulose Composite

Investigating temperature-induced structural changes of lead halide perovskites by in situ X-ray powder diffraction

2019 ◽  
Vol 52 (5) ◽  
pp. 1104-1118
Author(s):  
Rocco Caliandro ◽  
Davide Altamura ◽  
Benny Danilo Belviso ◽  
Aurora Rizzo ◽  
Sofia Masi ◽  
...  
Keyword(s):  
Multivariate Analysis ◽  
Structural Changes ◽  
Lattice Distortion ◽  
Data Matrix ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Temperature Variations ◽  
Temperature Changes ◽  
X Ray

In situ X-ray diffraction experiments offer a unique opportunity to investigate structural dynamics at atomic resolution, by collecting several patterns in an appropriate time sequence (data matrix) while varying the applied stimulus (e.g. temperature changes). Individual measurements can be processed independently by refinement procedures that are based on prior knowledge of the average structure of each crystal phase present in the sample. If the refinement converges, parameters of the average structural model can be assessed and studied as a function of the stimulus variations. An alternative approach consists in applying a multivariate analysis to the data matrix as a whole. Methods such as principal component analysis (PCA) and phase-sensitive detection perform fast, blind and model-independent calculations that can be used for on-site analysis to identify trends in data actually related to the applied stimulus. Both classical and multivariate approaches are here applied to the in situ X-ray diffraction pair distribution function (PDF) setup on two samples of the hybrid perovskite methylammonium (MA) lead iodide obtained by different synthetic routes, subjected to temperature variations. The PDF refinement allows assessing the occurrence of temperature-induced rotations of the PbI6 octahedra and variations in the relative amount of MAPbI3 and intermediate PbI2–MAI–DMSO (dimethyl sulfoxide) crystal phases. A change in the orientation of the methylammonium molecule with temperature is also characterized. Results of the multivariate analysis tools, which include a newly introduced space-dependent variant of PCA, are described, interpreted and validated against simulated data, and their specificity and relation to refinement results are highlighted. The interaction between nearby octahedra is identified as the driving force for the tetragonal-to-cubic phase transition, and three fundamental trends in data having different temperature behaviours are unveiled: (i) irreversible weight-fraction variations of the MAPbI3 and PbI2–MAI–DMSO phases; (ii) reversible structural changes related to the MAPbI3 crystalline phase and its lattice distortion in the ab plane, having the same frequency as the temperature variations; (iii) reversible lattice distortion along the c axis, occurring at twice the frequency of the temperature changes.

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