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

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.

Download Full-text

In Situ Synchrotron X-Ray Diffraction Study of a Deformed Cu-Fe-P Alloy during Heating

Materials Science Forum ◽

10.4028/www.scientific.net/msf.850.191 ◽

2016 ◽

Vol 850 ◽

pp. 191-196 ◽

Cited By ~ 1

Author(s):

Wei Wang ◽

Cun Lei Zou ◽

Ren Geng Li ◽

Wen Wen ◽

Hui Jun Kang ◽

...

Keyword(s):

Room Temperature ◽

Lattice Distortion ◽

Copper Matrix ◽

Heating Process ◽

Recrystallization Process ◽

Full Width ◽

X Ray Diffraction ◽

Dramatic Decrease ◽

X Ray

In situ synchrotron X-ray diffraction was used to study a deformed Cu-0.88 Fe-0.24 P alloy during heating process. The measurements were performed at room temperature and also at high temperatures up to 893 K in order to determine the recovery, ageing and recrystallization process. With the increase of temperature, the angles of copper matrix peaks moved left and the FWHM (full width at half maximum) decreased slightly. Fe3P precipitates were first detected at 533 K, reached the maximum at 673 K, and re-dissolved into matrix at 853 K. A dramatic decrease in FWHM was observed accompanied by the precipitation of Fe3P phases, indicating the reduction of lattice distortion of copper matrix.

Download Full-text

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

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314099057 ◽

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.

Download Full-text

A Study on the Growth of Cubic GaN Films Using an AlGaAs Buffer Layer Grown on GaAs (100) by Plasma-Assisted Molecular Beam Epitaxy

MRS Proceedings ◽

10.1557/proc-639-g3.46 ◽

2000 ◽

Vol 639 ◽

Author(s):

Ryuhei Kimura ◽

Kiyoshi Takahashi ◽

H. T. Grahn

Keyword(s):

Molecular Beam Epitaxy ◽

Buffer Layer ◽

Molecular Beam ◽

High Energy ◽

Rf Plasma ◽

Cubic Phase ◽

X Ray Diffraction ◽

X Ray ◽

Cubic Gan

ABSTRACTAn investigation of the growth mechanism for RF-plasma assisted molecular beam epitaxy of cubic GaN films using a nitrided AlGaAs buffer layer was carried out by in-situ reflection high energy electron diffraction (RHEED) and high resolution X-ray diffraction (HRXRD). It was found that hexagonal GaN nuclei grow on (1, 1, 1) facets during nitridation of the AlGaAs buffer layer, but a highly pure, cubic-phase GaN epilayer was grown on the nitrided AlGaAs buffer layer.

Download Full-text

Electric-field-induced lattice distortion in epitaxial BiFeO3 thin films as determined by in situ time-resolved x-ray diffraction

Applied Physics Letters ◽

10.1063/1.5000495 ◽

2017 ◽

Vol 111 (8) ◽

pp. 082907 ◽

Cited By ~ 2

Author(s):

Seiji Nakashima ◽

Osami Sakata ◽

Hiroshi Funakubo ◽

Takao Shimizu ◽

Daichi Ichinose ◽

...

Keyword(s):

Thin Films ◽

Electric Field ◽

Lattice Distortion ◽

X Ray Diffraction ◽

Time Resolved ◽

X Ray ◽

Bifeo3 Thin Films

Download Full-text

Temperature‐Dependent Local Structural Changes of Amorphous Thin Ge 20 Te 80 Film Revealed by In Situ Resistance, X‐Ray Diffraction, and Raman Spectroscopy Studies

physica status solidi (b) ◽

10.1002/pssb.202000451 ◽

2020 ◽

Vol 257 (12) ◽

pp. 2000451

Author(s):

Rathinavelu Sengottaiyan ◽

Anbarasu Manivannan

Keyword(s):

Raman Spectroscopy ◽

Structural Changes ◽

X Ray Diffraction ◽

Temperature Dependent ◽

X Ray ◽

Spectroscopy Studies

Download Full-text

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

Physical Chemistry Chemical Physics ◽

10.1039/c7cp03312e ◽

2017 ◽

Vol 19 (31) ◽

pp. 20867-20880 ◽

Cited By ~ 27

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.

Download Full-text

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

Physical Chemistry Chemical Physics ◽

10.1039/d0cp02144j ◽

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.

Download Full-text