Research Data Repository of Saxon Universities
OPARA is the Open Access Repository and Archive for Research Data of Saxon Universities.
Researchers of Saxon Universities can either publish their research data on OPARA, or archive it here to comply with requirements of funding acencies and good scientic practice, without public access.
You can find the documentation of this service at the ZIH Data Compendium websites. If you need suppourt using OPARA please contact the Servicedesk of TU Dresden.
Please note: The OPARA service was recently upgraded to a new technical platform (this site). Previously stored data will not be available here immediately. It can be found at the still active old version of OPARA. These stock data will be migrated in near future and then the old version of OPARA will finally be shut down. Existing DOIs for data publications remain valid.
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Recent Submissions
Data corresponding to paper: "Triaxial Compression of Sand‑Fines Mixtures at Low Confining Pressures" by Ullmann et al. (2025)
(Technische Universität Dresden, 2026-01-21) Ullmann, Sebastian Pierre; Schmidt, Selma; Hartung, Felix; Herle, Ivo
This data publication contains the data related to the scientific contribution "Triaxial Compression of Sand‑Fines Mixtures at Low Confining Pressures" by Ullmann et al. (2025)
Abstract of the corresponding paper:
A series of triaxial compression tests was performed on a natural sand-fines mixture under both drained and undrained conditions at initial confining pressures ranging from 20 to 300 kPa. The tests aimed to better understand the mechanical behaviour of the soil at low stress levels. Additionally, images of the soil fabric were taken using a μCT device, revealing that the fabric was characterised by the sand grains being fully embedded within the fine-grained matrix and that only few direct contacts between the sand grains existed. The results of the triaxial tests showed that the fabric of the sand-fines mixture significantly influenced the macroscopic properties of the specimens when compared to clean sands. In the drained triaxial tests, the dilatancy and friction angles showed minimal dependence on the confining pressure, even at pressures below 60 kPa. The undrained triaxial tests showed different response patterns in the development of excess pore water pressure. Tests starting from lower confining pressures resulted in a greater build-up of pore water pressure after reaching the phase transition line, whereas at higher confining pressures the soil exhibited lower excess pore water pressures.
Simultaneous Measurement of Flow in Open Flow Channel with Pulsed-Wave-Doppler-Velocimetry and Particle-Image-Velocimetry
(Technische Universität Bergakademie Freiberg, 2026-01-13) Schierling, Lennart; Kunz, Robert
Simultaneous measurement of flow velocity in an open flow channel via ultrasound (Pulsed-Wave-Doppler principle) and optical methods (Particle-Image-Velocimetry).
The dataset contains the unprocessed ultrasound signals as well as the images taken by a high speed camera for a set of flow states
GRK 2802: Dislocation-induced local symmetry reduction in single-crystal KNbO3 observed by Raman spectroscopy
(Technische Universität Bergakademie Freiberg, 2026-01-12) Drechsler, Felix; Himcinschi, Cameliu; Preuß, Oliver; Fang, Xufei; Kortus, Jens
In recent years, dislocation-tuned functionalized ceramics have become one of the focal points of modern materials research due to their outstanding properties. These range from improved electrical conductivity and ferroelectric properties to dislocation-enhanced toughening and superconductivity, caused by local strain fields. The aim of this work is to investigate the dislocation-induced structural changes in single-crystal KNbO3 by micro-Raman spectroscopy. Dislocation-rich regions with tailored densities have been generated using the Brinell indenter scratching method. The influence of the dislocations on the single-crystal structure can be observed in the Raman spectra. The activation of additional Raman modes is observed, which does not occur in regions of low dislocation density. This observation is confirmed by DFT calculations of vibrational modes and is attributed to a reduction in the crystal symmetry due to increased defect densities in plastically deformed KNbO3. In addition, an increase in compressive stress at higher dislocation densities can be demonstrated by a blueshift in Raman mode positions.
BaFe11TiO19 Vortex EMCD
(Technische Universität Dresden, 2026-01-08) Pohl, Darius; Makino, Hitoshi; Ernst, Arthur; Negi, Devendra; Schneider, Sebastian; Erni, Rolf; Rusz, Jan
We demonstrate atomic-scale mapping of local magnetic moments and doping effects in Ti-doped barium hexaferrite (BaFe11TiO19) using atom-sized electron vortex beams (EVBs) with controlled orbital angular momentum (OAM) in a scanning transmission electron microscope. By measuring electron energy loss magnetic circular dichroism (EMCD) at the Fe − L2,3 edges, we directly resolve the spatial distribution of antiparallel-aligned magnetic sublattices and quantify the impact of non-magnetic Ti4+ substitution. The EMCD signal, detected from single atomic Fe columns, reveals a marked reduction and sign reversal in the magnetic moment at Ti-rich 4f2 sites, corroborated by inelastic scattering simulations and density functional theory calculations that indicate induced Fe2+ formation and modified exchange interactions. Our results show that EVBs enable direct, element-specific, and atomically resolved magnetic characterization, opening new avenues for investigating local magnetic phenomena and dopant effects in nano-structured magnetic materials, such as those used in spintronic devices. This method paves the way for detailed studies of complex spin textures, magnetic interfaces, and dynamic processes at the atomic scale.
Dataset includes raw data, DFT simulation of the DOS (BaFe12O19, BaFe11TiO19) and inelastic scattering simulation data.
Controlling structural instability in the Cu$_{12-x}$Ni$_x$Sb$_4$S$_{13}$ ($x$\,=\,0, 0.05, 0.2, 0.5) tetrahedrites
(Technische Universität Bergakademie Freiberg, 2026-01-08) Bolielyi, Oleksandr; Dobrozhan, Oleksandr; Levytskyi, Volodymyr; Tsirlin, Alexander A.; Pshenychnyi, Roman; Leithe-Jasper, Andreas; Gumeniuk, Roman
Cu$_{12-x}$Ni$_x$Sb$_4$S$_{13}$ ($x\,=\,0, 0.05, 0.2, 0.5$) tetrahedrites were synthesized by the polyol method. Measurements of magnetic susceptibility, specific heat capacity as well as electrical and thermal transport properties indicated a structural phase transition (SPT) of 1$^{\mathrm{st}}$ order at $T_k\,=\,75-85$\,K, which is accompanied by strong changes in electronic density of states (EDOS) and entropy for $x\,=\,0, 0.05, 0.2$ whereas only weak changes were observed at $x\,=\,0.5$. However, further temperature dependent synchrotron high-resolution powder X-ray diffraction (HR PXRD) studies indicated compounds with Ni-content $x\,=\,0$ and 0.5 to remain body-centered cubic [space group (SG) $I\bar{4}3m$, $a\,\approx\,10.4(1)$\,\AA] down to 10\,K, whereas crystal structures of $x\,=\,0, 0.05$ and 0.2 became tetragonal, (SG $P\bar{4}c2$, $a_\mathrm{tetr}\,\approx\,a_\mathrm{cub}\sqrt{2}$, $c_\mathrm{tetr}\,\approx\,a_\mathrm{cub}$) below $T_k$. Comparing changes of EDOS at the Fermi level [$\Delta N^{(E_\mathrm{F})}$] deduced from magnetic and thermodynamic data with those calculated from density functional theory (DFT) assuming the validity of the rigid-band approximation, we found $\Delta N^{(E_\mathrm{F})}_\mathrm{theor}\,\approx\,0$ when compared with cubic and tetragonal arragements for Cu$_{11.5x}$Ni$_{0.5}$Sb$_4$S$_{13}$, which indicate the latter to be unstable. This study shows that SPT in tetrahedites is facilitated by the presence of minor amount of a dopant.