A5056005798- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Crystallography and molecular interactions
- Solid-state spectroscopy and crystallography
- Advanced Condensed Matter Physics
- Crystal structures of chemical compounds
- Rare-earth and actinide compounds
- Crystal Structures and Properties
- Inorganic Chemistry and Materials
- Metal-Organic Frameworks: Synthesis and Applications
- Magnetic and transport properties of perovskites and related materials
- Organic and Molecular Conductors Research
- Iron-based superconductors research
- Nonlinear Optical Materials Research
- Advanced Chemical Physics Studies
- Inorganic Fluorides and Related Compounds
- Boron and Carbon Nanomaterials Research
- Molecular Sensors and Ion Detection
- Boron Compounds in Chemistry
- Bone Tissue Engineering Materials
- Catalytic Processes in Materials Science
- Laser-Ablation Synthesis of Nanoparticles
- Electronic and Structural Properties of Oxides
- Organometallic Compounds Synthesis and Characterization
- Nanoparticles: synthesis and applications
University of Bayreuth
2014-2023
Institute of Crystallography
2001-2019
A.V. Shubnikov Institute of Crystallography
2011
Université de Lorraine
2011
Centre National de la Recherche Scientifique
2011
Ludwig-Maximilians-Universität München
2009
LMU Klinikum
2009
Universität Hamburg
2009
University of Lausanne
2000-2006
University of the Basque Country
2004-2006
We report a systematic investigation on the role of excess PbI2 content in CH3NH3PbI3 perovskite film properties, solar cell parameters and device storage stability. used CH3NH3I vapor assisted method for preparation PbI2-free films under N2 atmosphere. These pristine were annealed at 165 °C different time intervals atmosphere to generate additional these films. From XRD measurements, was quantified. Detailed characterization using scanning electron microscopy, X-ray diffraction, UV-Visible...
Excess PbI<sub>2</sub> in MAPbI<sub>3</sub> thin films has no direct impact on the electronic structure but changes temperature dependence of exciton binding energy and phase transition behaviour.
The X-ray analysis of (6R,7aS)-6-(tert-butyl-dimethylsilanyloxy)-1-hydroxy-2-phenyl-5,6,7,7a-tetrahydropyrrolizin-3-one, C19H27NO3Si, revealed a diffraction pattern which is typical for modulated structures: strong Bragg peaks surrounded by weaker reflections cannot be indexed with the same three reciprocal lattice vectors that are used to describe peaks. For this class crystal structures concept superspace has been developed which, however, many crystallographers still constitutes Gordian...
The peculiar bonding situation in γ boron is characterized on the basis of an experimental electron-density distribution which obtained by multipole refinement against low-temperature single-crystal x-ray diffraction data. A topological analysis reveals one-electron-two-center bonds connecting neighboring icosahedral B(12) clusters. unique polar-covalent two-electron-three-center bond between a pair atoms cluster and one atom interstitial dumbbell explains observed charge separation this...
Microbial biosynthesis of metal nanoparticles as needed in catalysis has shown its theoretical ability an extremely environmentally friendly production method the last few years, even though separation is challenging. Biosynthesis, summing up biosorption and bioreduction diluted ions to zero valent metals, especially ecofriendly, when bioreactor itself harmless needs no further harmful reagents. The cyanobacterium Anabaena cylindrica (SAG 1403.2) able form crystalline Au 0 -nanoparticles...
The phase transition of CrOCl toward a state antiferromagnetic order below ${T}_{N}=13.5\text{ }\text{K}$ has been identified as first-order transition. is accompanied by lattice and structural distortion twofold, $2\mathbf{b}$ nuclear superstructure with $\mathbf{a}$-axis unique monoclinic symmetry, evidenced temperature-dependent x-ray diffraction experiments. Magnetic-susceptibility magnetization measurements indicate strong magnetoelastic coupling to uniaxial antiferromagnet ordered...
Ho2Ir3Si5 belongs to the family of three-dimensional (3D) R2Ir3Si5 (R = Lu, Er and Ho) compounds that exhibit a colossal first-order charge density wave (CDW) transition where there is strong orthorhombic-to-triclinic distortion lattice accompanied by superlattice reflections. The analysis single-crystal X-ray diffraction (SXRD) has revealed Ir-Ir zigzag chains along c are responsible for CDW in all three compounds. replacement rare earth element from non-magnetic Lu magnetic or Ho lowers...
The first-order charge density wave (CDW) phase transition of ${\mathrm{Er}}_{2}{\mathrm{Ir}}_{3}{\mathrm{Si}}_{5}$ is characterized by a crystal structure analysis, and electrical resistivity, magnetic susceptibility specific heat measurements. incommensurate CDW accompanied strong lattice distortion, from which it shown that the resides on zigzag chains iridium atoms. affects magnitude local moments ${\mathrm{Er}}^{3+}$, implying coupling between magnetism. This could account for...
Temperature-dependent x-ray diffraction of the low-dimensional spin-$1∕2$ quantum magnet TiOBr shows that phase transition at ${T}_{c2}=47.1(4)\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ corresponds to development an incommensurate superstructure. Below ${T}_{c1}=26.8\ifmmode\pm\else\textpm\fi{}0.3\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ modulation locks in into a twofold superstructure similar low-temperature spin-Peierls state TiOCl. Frustration between intra- and interchain interations within...
Efficient biosorption and intracellular accumulation of selected rare earth elements from aqueous solutions by cyanobacteria type <italic>Anabaena</italic>.
The incommensurately modulated structure is reported for the low-dimensional spin-$1∕2$ quantum magnet TiOCl. On basis of an analysis structural distortions in spin-Peierls state (stable below ${T}_{c1}=67\phantom{\rule{0.3em}{0ex}}\mathrm{K}$) and incommensurate phase between ${T}_{c1}$ ${T}_{c2}=90\phantom{\rule{0.3em}{0ex}}\mathrm{K}$), it argued that both incommensurability twofold superstructure at low temperatures are result frustration a pairing on chains Ti atoms as driving force...
VOCl develops magnetic order below ${T}_{\text{N}}=80.3(3)\text{ }\text{K}$. Employing single-crystal x-ray diffraction and powder neutron it is shown that the phase transition accompanied by a small, temperature-dependent monoclinic lattice distortion with $\ensuremath{\gamma}=90.212(2)\ifmmode^\circ\else\textdegree\fi{}$ at $T=3.2\text{ The presumably of second critical exponent $\ensuremath{\beta}=0.099(12)$. lifts frustration interchain interactions along...
On the basis of single-crystal x-ray diffraction we show that TiPO${}_{4}$ undergoes a spin-Peierls distortion below 74.5(5) K, with dimerization Ti chains along $\mathbf{c}$ axis. Between and 111.6(3) develops an incommensurate (IC) phase temperature-dependent $\mathbf{q}$ vector (${\ensuremath{\sigma}}_{1}$,0,0). Density functional calculations strongly suggest IC results from frustration lock-in transition due to competition three energetically almost degenerate crystal structures elastic...
Pressure-dependent transmittance and reflectance spectra of TiOBr TiOCl single crystals at room temperature suggest the closure Mott-Hubbard gap, i.e., gap is filled with additional electronic states extending down to far-infrared range. According pressure-dependent x-ray powder diffraction data coincides a structural phase transition. The transition in occurs slightly lower pressure ($p$=14 GPa) compared ($p$=16 under hydrostatic conditions, which discussed terms chemical effect. results...
The three-dimensional charge density wave (CDW) compound ${\mathrm{CuV}}_{2}{\mathrm{S}}_{4}$ is known to undergo phase transitions at $\ensuremath{\sim}91$ and $\ensuremath{\sim}50\phantom{\rule{4pt}{0ex}}\mathrm{K}$. Employing single-crystal x-ray diffraction on an annealed crystal, we confirm the formation of incommensurate CDW ${T}_{\text{CDW}}\ensuremath{\approx}91\phantom{\rule{4pt}{0ex}}\mathrm{K}$, establish nature transition...
We present the temperature dependence of electrical resistivity, magnetic susceptibility, and specific heat a high-quality single crystal ${\mathrm{La}}_{3}{\mathrm{Co}}_{4}{\mathrm{Sn}}_{13}$. As opposed to earlier reports on this system, these bulk properties exhibit clear anomalies at phase transition ${T}^{*}=151(1)$ K, while data confirm second-order character transition. X-ray diffraction with synchrotron radiation is used solve fourfold superstructure in space group $I{2}_{1}3$ as it...
NADA is a computer program for the simultaneous refinement of components orientation matrix and up to three modulation vectors by method least squares. Using spatial peak positions main reflections from single-crystal diffraction experiment rough estimates vector(s) components, re-indexes peaks (main satellite reflections) with integers in higher dimensions ( hklm 1 , m 2 or 3 respectively) refines observed positions. Standard uncertainties on all refined parameters are calculated analytically.
The incommensurately modulated structure of a natural nepheline composition K(0.54)Na(3.24)Ca(0.03)Al(3.84)Si(4.16)O(16) has been determined in superspace. compound crystallizes the trigonal centered superspace group X3(00γ)0 with γ = 0.2048 (10), X (0, 0, 0), (1/3, 2/3, 2/3), (2/3, 1/3, 1/3), 17.2889 (8) and c 8.3622 (10) Å. is characterized by framework corner-connected (Al,Si)O(4) tetrahedra. additional cations are incorporated two different types channels framework. All atoms...
The co-crystal of phenazine (Phz) and chloranilic acid (H2ca) becomes ferroelectric upon cooling through the loss inversion symmetry. Further results in development an incommensurate phase, followed by a lock-in transition towards twofold superstructure. Here we present incommensurately modulated crystal structure Phz-H2ca at T = 139 K with symmetry given superspace group P2(1)(½ σ(2) ½)0 0.5139. modulation mainly affects positions protons within half intermolecular hydrogen bonds that are...
The three-dimensional charge density wave (CDW) compound ${\mathrm{Lu}}_{2}{\mathrm{Ir}}_{3}{\mathrm{Si}}_{5}$ undergoes a first-order CDW phase transition at around 200 K. An atypical state is found, that characterized by an incommensurate with $\mathbf{q}=[0.2499(3),0.4843(4),0.2386(2)]$ 60 K, and large orthorhombic-to-triclinic lattice distortion $\ensuremath{\beta}=91.945{(2)}^{\ensuremath{\circ}}$. We present the modulated crystal structure of state. Structural analysis shows resides on...
Abstract The room temperature structure ( α -form) of the organic compound p -chlorobenzamide, C 7 H 6 ClNO, can be described as a classical three-dimensional periodic superstructure S ) and also commensurately modulated M in (3 + 1)-dimensional superspace. diffraction pattern is characterized by clear difference intensity between main satellite reflections. All reflections indexed with four indices hklm triclinic unit cell one modulation vector superspace group P 1̅( αβγ q⃗ = 1/3· a⃗ *....
The low-temperature (T = 17.5 K) structure of titanium(III) oxybromide, TiOBr, is reported as a twofold superstructure the crystal at room temperature. Weak superlattice reflections were measured with synchrotron radiation X-rays and analyzed by refinements employing superspace techniques. Both room-temperature structures TiOBr are isostructural corresponding TiOCl. results indicate that low temperatures in spin-Peierls state, similar to TiOCl, but modulations relevant interactions smaller...
We investigated the pressure-dependent optical response of low-dimensional Mott-Hubbard insulator TiOBr by transmittance and reflectance measurements in infrared visible frequency range. A suppression above a critical pressure concomitant increase are observed, suggesting pressure-induced metallization TiOBr. The metallic phase at high is confirmed presence additional excitations extending down to far-infrared coincides with structural transition, according results x-ray powder diffraction...