Publication list of the Group of Materials in Electrical Engineering

Anzahl der Treffer: 685
Erstellt: Wed, 27 Mar 2024 23:02:58 +0100 in 0.0607 sec


Wang, Honglei; Jiao, Yunfei; Wu, Bing; Wang, Dong; Hu, Yueqi; Liang, Fei; Shen, Chen; Knauer, Andrea; Ren, Dan; Wang, Hongguang; Aken, Peter Antonie van; Zhang, Hongbin; Sofer, Zdenek; Grätzel, Michael; Schaaf, Peter
Exfoliated 2D layered and nonlayered metal phosphorous trichalcogenides nanosheets as promising electrocatalysts for CO2 reduction. - In: Angewandte Chemie, ISSN 1521-3773, Bd. 62 (2023), 17, e202217253, S. 1-8

Two-dimensional (2D) materials catalysts provide an atomic-scale view on a fascinating arena for understanding the mechanism of electrocatalytic carbon dioxide reduction (CO2 ECR). Here, we successfully exfoliated both layered and nonlayered ultra-thin metal phosphorous trichalcogenides (MPCh3) nanosheets via wet grinding exfoliation (WGE), and systematically investigated the mechanism of MPCh3 as catalysts for CO2 ECR. Unlike the layered CoPS3 and NiPS3 nanosheets, the active Sn atoms tend to be exposed on the surfaces of nonlayered SnPS3 nanosheets. Correspondingly, the nonlayered SnPS3 nanosheets exhibit clearly improved catalytic activity, showing formic acid selectivity up to 31.6 % with -7.51 mA cm^-2 at -0.65 V vs. RHE. The enhanced catalytic performance can be attributed to the formation of HCOO* via the first proton-electron pair addition on the SnPS3 surface. These results provide a new avenue to understand the novel CO2 ECR mechanism of Sn-based and MPCh3-based catalysts.



https://doi.org/10.1002/anie.202217253
Tan, Xinu; Liu, Yushun; Li, Feitao; Qiu, Risheng; Liu, Qing
Formation of nanocrystalline γ-ZrH in Zr-Nb alloy: crystal structure and twinning. - In: Micron, ISSN 1878-4291, Bd. 167 (2023), 103414

In the present work, the lattice parameter and the twins of γ-ZrH hydride in Zr-2.5Nb-1Si were characterized using high resolution electron microscopy. The lattice parameters of γ-ZrH (P42/mmc, Zr2H2 unit cell) is determined to be a= 0.336nm, c=0.508nm. Twinning γ-ZrH hydride ({011}<0̅11> type) is for the first time reported in zirconium alloys, whose orientation relationship with α-Zr is [100]γ-twins // [1̅210]α and (011)γ-twins // (0002)α. The formation process of γ-ZrH twins is also discussed based on a ‘grow-in’ mechanism during the transformation from α-Zr to γ-ZrH hydride.



https://doi.org/10.1016/j.micron.2023.103414
Hähnlein, Bernd; Honig, Hauke; Schaaf, Peter; Krischok, Stefan; Tonisch, Katja
Effect of poly-crystallinity on the magnetoelectric behavior of TiN/AlN/Ni MEMS cantilevers investigated by finite element methods. - In: Physica status solidi, ISSN 1862-6319, Bd. 220 (2023), 16, 2200839, S. 1-6

Herein, magnetoelectric microelectromechanical system (MEMS) cantilevers are investigated on basis of a TiN/AlN/Ni laminate derived from experimental sensors using finite-element simulations. With the anisotropic ΔE effect as an implication of the magnetocrystalline anisotropy, the lateral sensitivity of the sensor is studied for different nickel layer thicknesses and boundary conditions. It is found that above 60% of the cantilever length, the nickel is effectively not contributing to the sensor sensitivity anymore which is supported by the investigation of sensors with partial nickel coverage. The boundary condition of the magnetostrictive layer is found to affect the sensitivity of thick layers while it is negligible for thinning layers. Further investigations on basis of polycrystalline untextured nickel with slightly preferred orientations reveal a stronger effect on thin layers than on thicker ones. It is found to arise from relatively large crystals in the high-sensitivity region near the clamping of the sensor. For thicker polycrystalline layers, the ΔE effect reproduces a characteristic based mainly on the (110) and (111) orientations while the (100) orientation appears to be underrepresented.



https://doi.org/10.1002/pssa.202200839
Glaser, Marcus; Matthes, Sebastian; Hildebrand, Jörg; Bergmann, Jean Pierre; Schaaf, Peter
Hybrid thermoplastic-metal joining based on Al/Ni multilayer foils - analysis of the joining zone. - In: Materials and design, ISSN 1873-4197, Bd. 226 (2023), 111561, insges. 16 S.

Multi material pairings like metal-plastic hybrid compounds are becoming increasingly important across all industrial sectors. However, the substitution of metals by plastics leads to a multitude of challenges based on the combination of dissimilar materials. The variations in the chemical and physical properties of the used materials require innovative joining processes. The application of reactive multilayers represents an advanced joining method for flexible and low-distortion joining of dissimilar joining partners by means of a short-term and localized application of thermal energy. In the context of this publication, the joining process between semi-crystalline polyamide 6 and austenitic stainless steel X5CrNi18-10(EN 1.4301 / AlSI304) based on reactive Al/Ni multilayers is investigated. In addition to evaluation of resulting joint strength, the focus of the work is in particular the characterization of the resulting failure behavior at the fracture interface under tensile load and the deriving binding mechanisms in the joint. From the results obtained, it is estimated that a direct bond can be generated between plastic and metal despite the presence of a residual reacted foil in the joining area. The structures present in the metal surface have a particularly positive influence on crack initiation and the resulting increased bond strength.



https://doi.org/10.1016/j.matdes.2022.111561
Cheng, Pengfei; Döll, Joachim; Romanus, Henry; Wang, Hongguang; Aken, Peter Antonie van; Wang, Dong; Schaaf, Peter
Reactive magnetron sputtering of large-scale 3D aluminum-based plasmonic nanostructure for both light-induced thermal imaging and photo-thermoelectric conversion. - In: Advanced optical materials, ISSN 2195-1071, Bd. 11 (2023), 6, 2202664, S. 1-7

Plasmonic nanostructures have attracted tremendous interest due to their special capability to trap light, which is of great significance for many applications such as solar steam generation and desalination, electric power generation, photodetection, sensing, catalysis, cancer therapy, and photoacoustic imaging. However, the noble metal-based (Au, Ag, Pd) plasmonic nanostructures with expensive costs and limitations to large-scale fabrication restrict their practical applications. Here, a novel and noble-metal-free Al/AlN plasmonic nanostructure fabricated by a reactive magnetron sputtering at the elevated temperature of 200 &ring;C is presented. The unique 3D Al/AlN plasmonic nanostructures show a highly efficient (96.8%) and broadband (full solar spectrum) absorption and a strong photothermal conversion effect on its surface, demonstrating the potential in applications in light-induced thermal imaging and photo-thermoelectric power generation. This simple fabrication method and the developed Al/AlN plasmonic nanostructure combine excellent light trapping performance, abundant and low-cost Al and N elements, good heat localization effect, and scalable fabrication method, suggesting a promising alternative to noble-metal plasmonic nanostructures for photonic applications.



https://doi.org/10.1002/adom.202202664
Li, Feitao; Tan, Xinu; Flock, Dominik; Qiu, Risheng; Wang, Dong; Schaaf, Peter
Formation of CuO whiskers and facet-controlled oxidation during the oxidation of Au-Cu nanoparticles fabricated by solid-state dewetting. - In: Applied surface science, Bd. 610 (2023), 155547

The fabrication of cupric oxide (CuO) nanowires from Cu particles via thermal oxidation provides a simple and scalable method to produce hierarchical structures. A stress-induced growth mechanism is believed to account for the nanowire formation while a slow oxidation rate is favored to sustain the driving force. Here, CuO whiskers are grown from Au-Cu nanoparticles because the formation of Au-Cu phases decreases the Cu diffusion rate and in turn slows down the oxidation rate. The driving force for the whisker growth is attributed to the compressive stress imposed by the CuO shell on the Au-Cu core, which is induced by the significantdifference in their linear thermal expansion coefficients. The contribution of the compressive stress is proved by the calculation. Moreover, preferred oxidation is observed and it is related to the crystalline structures of different facets existing on the surface of Au-Cu nanoparticles. The more compact the plane, the slower the diffusion rate through the plane, resulting in the formation of thinner CuO on the relevant facet. The results open a cost-effect way to fabricate hybrid nanostructures consisting of Cu-based core-shell nanoparticles attached with CuO whiskers and bring new insights into the oxidation behaviors of Cu on different crystal planes.



https://doi.org/10.1016/j.apsusc.2022.155547
Wöste, Andreas; Hergert, Germann; Silies, Martin; Wang, Dong; Groß, Petra; Lienau, Christoph
Photon-induced near-field interaction in ultrafast low energy electron microscopy. - [Washington, D.C., USA] : Optica Publishing Group. - 1 Online-Ressource (Paper Tu3A.5)

We report the first observation of optical near-field coupling to an ultrafast wavepacket of free, low-energy electrons. Transient optical near-fields, highly spatially confined around a nanometer-sized Yagi-Uda-antenna are probed in a point-projection-microscope with 30-fs resolution.



https://doi.org/10.1364/UP.2022.Tu3A.5
Schaaf, Peter; Zyabkin, Dmitry
Mössbauer spectroscopy. - In: Reference module in materials science and materials engineering, (2022), insges. 14 S.

The current chapter provides the reader with a general introduction of Mössbauer effect following by its unique utilization, which became known as Mössbauer spectroscopy. Mössbauer spectroscopy is based on the recoilless emission and following resonant absorption of gamma radiation by atomic nuclei and has been at the scientific forefront of physics, chemistry, biology, mineralogy for more than 60 years. Soon after the discovery of the Mössbauer effect, it became obvious that this effect can be used to study various properties of materials on a microscopic scale via hyperfine interactions with an unprecedented resolution. This was the beginning of a new analytical tool - Mössbauer spectroscopy. Today, it has developed into a standard analytical technique used in many laboratories and big research facilities. The current chapter provides the reader with a general introduction, explains the underlying hyperfine interactions and gives examples of the possible application of the method.



https://doi.org/10.1016/B978-0-323-90800-9.00137-2
Gunnlaugsson, Haraldur P.; Mokhles Gerami, Adeleh; Masenda, Hilary; Ólafsson, Sveinn; Adhikari, Rajdeep; Johnston, Karl; Naicker, Kimara; Peters, Gerrard; Schell, Juliana; Zyabkin, Dmitry; Bharuth-Ram, Krish; Krastev, Petko; Mantovan, Roberto; Naidoo, Deena; Unzueta, Iraultza
Charge and spin state of dilute Fe in NaCl and LiF. - In: Physical review, ISSN 2469-9969, Bd. 106 (2022), 17, 174108, S. 174108-1-174108-10

There is an apparent mismatch between electron paramagnetic resonance and Mössbauer spectroscopy results on the charge and spin states of dilute Fe impurities in NaCl; Mössbauer spectroscopy data have been interpreted in terms of high-spin Fe2+, while electron paramagnetic resonance studies suggest low-spin Fe1+. In the present study, the charge and spin states of dilute substitutional Fe impurities in NaCl and LiF have been investigated with 57Mn&flech;57Fe emission Mössbauer spectroscopy. A scheme is proposed which takes into account the effects of nearest-neighbor distances and electronegativity difference of the host atoms on the Mössbauer isomer shift and allows for the unequivocal differentiation between high-spin Fe2+ and high/low-spin Fe1+ in Mössbauer spectroscopy. From these considerations, the Mössbauer results are found to be consistent with dilute Fe impurities in NaCl and LiF in a low-spin Fe1+ state. These conclusions are supported by theoretical calculations of isomer shifts and formation energies based on the density-functional theory. The experimental results furthermore suggest that charge compensation of dilute Mn2+ dopants in NaCl and LiF is achieved by Na vacancies and F− interstitials, respectively.



https://doi.org/10.1103/PhysRevB.106.174108