Research Highlights

2017

11.08.2017

The cubic-to-hexagonal phase transition of cerium oxide particles: dynamics and structure

Authors:

Jan Höcker, Jon-Olaf Krisponeit, Thomas Schmidt, Jens Falta and Jan Ingo Flege.

Journal:

Nanoscale (2017) 9, 9352-9358

http://dx.doi.org/10.1039/C6NR09760J

Abstract:

Cerium oxide is often applied in today's catalysts due to its remarkable oxygen storage capacity. The changes in stoichiometry during reaction are linked to structural modifications, which in turn affect its catalytic activity. We present a real-time in situ study of the structural transformations of cerium...

mehr »
12.06.2017

Simultaneous Acquisition of the Polarized and Depolarized Raman Signal with a Single Detector

Authors:

Johannes Kiefer.

Journal:

Analytical Chemistry (2017) 89 (11), 5725-5728

http://dx.doi.org/10.1021/acs.analchem.7b01106

Abstract:

Polarization-resolved Raman spectroscopy provides much more information than its conventional counterpart. However, it usually either requires a complicated setup with two spectrographs and detectors or two measurements must be performed sequentially. This study presents a simple and straightforward approach to recording both polarization components...

mehr »
30.05.2017

Time resolved impedance spectroscopy analysis of lithium phosphorous oxynitride - LiPON layers under mechanical stress

Authors:

Jens Glenneberg, Ingo Bardenhagen, Frederieke Langer, Matthias Busse and Robert Kun.

Journal:

Journal of Power Sources (2017) 359, 157-165

http://dx.doi.org/10.1016/j.jpowsout.2017.05.037

Abstract:

 

In this paper we present investigations on the morphological and electrochemical changes of lithium phosphorous oxynitride (LiPON) under mechanically bent conditions. Therefore, two types of electrochemical cells with LiPON thin films were prepared by physical vapor...

mehr »
20.04.2017

Tunable Bragg polaritons and nonlinear emission from a hybrid metal-unfolded ZnSe-based microcavity

Authors:

SK. Shaid-Ur Rahman, Thorsten Klein, Jürgen Gutowski, Sebastian Klembt and Kathrin Sebald.

Journal:

Scientific Reports (2017) 7, Article number: 767

http://dx.doi.org/10.1038/s41598-017-00878-2

Abstract:

Strong light-matter interaction in Bragg structures possesses several advantages over conventional microcavity system. These structures provide an opportunity to incorporate a large number of quantum wells without increasing the mode volume. Further, it is expected that...

mehr »
01.03.2017

Colloidal capsules: nano- and microcapsules with colloidal particle shells

Authors:

Tobias Bollhorst, Kurosch Rezwan and Michael Maas.

Journal:

Chemical Society Reviews (2017) 46, 2091-2126

http://dx.doi.org/10.1039/c6cs00632a

Abstract:

Utilizing colloidal particles for the assembly of the shell of nano- and microcapsules holds great promise for the tailor-made design of new functional materials. Increasing research efforts are devoted to the synthesis of such colloidal capsules, by which the integration of modular building blocks with distinct physical,...

mehr »
04.02.2017

Growth and structure of ultrathin praseodymium oxide layers on ruthenium(0001)

Authors:

Jan Höcker, Jon-Olaf Krisponeit, Julian Cambeis, Alexei Zakharov, Yuran Niu, Gang Wei, Lucio Colombi Ciacchi, Jens Falta, Andreas Schaefer and Jan Ingo Flege.

Journal:

Physical Chemistry Chemical Physics (2017) 19, 3480-3485

http://dx.doi.org/10.1039/c6cp06853g

Abstract:

The growth, morphology, structure, and stoichiometry of ultrathin praseodymium oxide layers on
Ru(0001) were studied using low-energy electron microscopy and diffraction, photoemission electron
microscopy, atomic...

mehr »
18.01.2017

Nanoparticles for radiooncology: Mission, vision, challenges

Authors:

Leoni A. Kunz-Schughart, Anna Dubrovska, Claudia Peitzsch, Alexander Ewe, Achim Aigner, Samuel Schellenburg, Michael H. Muders, Silke Hampel, Giuseppe Cirillo, Francesca Iemma, Rainer Tietze, Christoph Alexiou, Holger Stephan, Kristof Zarschler, Orazio Vittorio, Maria Kavallaris, Wolfgang J. Parak, Lutz Mädler and Suman Pokhrel.

Journal:

Biomaterials (2017) 120, 155-184

 

mehr »
18.01.2017

Safe-by-Design CuO Nanoparticles via Fe-Doping, Cu–O Bond Length Variation, and Biological Assessment in Cells and Zebrafish Embryos

Authors:

 

Hendrik Naatz, Sijie Lin, Ruibin Li, Wen Jiang, Zhaoxia Ji, Chong Hyun Chang, Jan Köser, Jorg Thöming, Tian Xia, Andre E. Nel, Lutz Mädler and Suman Pokhrel.

Journal:

ACS nano (2017) 11, 501–515

http://dx.doi.org/10.1021/acsnano.6b06495

Abstract:

The safe implementation of nanotechnology requires nanomaterial hazard assessment in accordance with the material physicochemical properties...

mehr »

2016

03.11.2016

Observation of a hybrid state of Tamm plasmons and microcavity exciton polaritons

Authors:

SK. Shaid-Ur Rahman, Thorsten Klein, Sebastian Klembt, Jürgen Gutowski, Detlef Hommel and Kathrin Sebald.

Journal:

Scientific Reports (2016) 6, Article number 34392

http://dx.doi.org/10.1038/srep34392

Abstract:

We present evidence for the existence of a hybrid state of Tamm plasmons and microcavity exciton polaritons in a II-VI material based microcavity sample covered with an Ag metal layer. The bare cavity mode shows a characteristic anticrossing with the Tamm-plasmon mode, when...

mehr »
31.08.2016

Repetitive Dosing of Fumed Silica Leads to Profibrogenic Effects through Unique Structure−Activity Relationships and Biopersistence in the Lung

Authors:

Bingbing Sun, Xiang Wang, Yu-Pei Liao, Zhaoxia Ji, Chong Hyun Chang, Suman Pokhrel, Justine Ku, Xiangsheng Liu, Meiying Wang, Darren R. Dunphy, Ruibin Li, Huan Meng, Lutz Mädler, C. Jeffrey Brinker, André E. Nel, and Tian Xia

Journal:

ACS Nano (2016) 10, 8054-8066

http://dx.doi.org/10.1021/acsnano.6b04143

Abstract:

Contrary to the notion that the use of fumed silica in consumer products can “generally (be) regarded as safe” (GRAS), the high surface reactivity of...

mehr »
20.07.2016

Self-Assembly and Shape Control of Hybrid Nanocarriers Based on Calcium Carbonate and Carbon Nanodots

Authors:

Victor Lauth, Brigitta Loretz, Claus-Michael Lehr, Michael Maas, Kurosch Rezwan

Journal:

Chemistry of Materials (2016) 28, 3796-3803

http://dx.doi.org/10.1021/acs.chemmater.6b0076

Abstract:

We describe a platform for the synthesis of functional hybrid nanoparticles in the submicrometer range with tailorable anisotropic morphology. Fluorescent carbon dots (CDs) and poly(acrylic acid) (PAA) are used to modify the crystallization and assembly of calcium carbonate (CaCO3)....

mehr »
30.06.2016

Directed percolation phase transition to sustained turbulence in Couette flow

Authors:

Grégoire Lemoult, Liang Shi, Kerstin Avila, Shreyas V. Jalikop, Marc Avila and Björn Hof

Journal:

Nature Physics (2016) 12, 254-258

http://dx.doi.org/10.1038/NPHYS3675

Abstract:

Turbulence is one of the most frequently encountered nonequilibriumphenomena in nature, yet characterizing thetransition that gives rise to turbulence in basic shear flowshas remained an elusive task. Although, in recent studies,critical points marking the onset of sustained turbulence1–3have...

mehr »
23.06.2016

A concept for direct deposition of thin film batteries on flexible polymer substrate

Authors:

Jens Glenneberg, Felix Andre, Ingo Bardenhagen, Frederieke Langer, Julian Schwenzel, Robert Kun.

Journal:

Journal of Power Sources  (2016) 324, 722-728.

dx.doi.org/10.1016/j.jpowsour.2016.06.007

Abstract:

In this paper, the preparation and characteristics of all-solid-state thin film batteries (TFB) are described. In contrast to the state-of-the-art TFB preparation processes, only room temperature processes are used. The cathode is based on amorphous molybdenum(VI) oxide...

mehr »
13.06.2016

Hydrogen atoms can be located accurately and precisely by x-ray crystallography

Authors:

Magdalena Woinska, Simon Grabowsky, Paulina M. Dominiak, Krzysztof Wozniak, Dylan Jayatilaka

Journal:

Science Advances (2016) 2, e1600192

http://dx.doi.org/10.1126/sciadv.1600192

Abstract:

Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms...

mehr »
30.05.2016

Novel Excitonic Solar Cells in Phosphorene-TiO2 Heterostructures with Extraordinary Charge Separation Efficiency

Authors:

Liujiang Zhou, Jin Zhang, Zhiwen Zhuo, Liangzhi Kou, Wei Ma, Bin Shao, Aijun Du, Sheng Meng, and Thomas Frauenheim

Journal:

Journal of Physical Chemistry Letters (2016) 7, 1880-1887

http://dx.doi.org/10.1021/acs.jpclett.6b0047

Abstract:

Kurzfassung Constructing van der Waals heterostructures is an efficient approach to modulate the electronic structure, to advance the charge separation efficiency, and thus to optimize the optoelectronic property. Here, we theoretically...

mehr »
16.05.2016

Giant photon bunching, superradiant pulse emission and excitation trapping in quantum-dot nanolasers

Authors:

Frank Jahnke, Christopher Gies, Marc Assmann, Manfred Bayer, H.A.M. Leymann, Alexander Foerster,  Jan Wiersig, Christian Schneider, MartinKamp, Sven Hoefling

Journal:

Nature Communications (2016) 7, 11540

http://dx.doi.org/10.1038/ncomms11540

Abstract:

Light is often characterized only by its classical properties, like intensity or coherence. Whenlooking at its quantum properties, described by photon correlations, new information aboutthe state of the matter generating...

mehr »
12.05.2016

Growth and characterization of epitaxially stabilized ceria(001) nanostructures on Ru(0001)

Authors:

Jan Ingo Flege, Jan Höcker, Björn Kaemena, T. Onur Mentes, Alessandro Sala, Andrea Locatelli, Subhashis Gangopadhyay, Jerzy T. Sadowski, Sanjaya D. Senanayake and Jens Falta.

Journal:

Nanoscale (2016) 8, 10849-10856.

doi:10.1039/C6NR02393B

Abstract:

We have studied (001) surface terminated cerium oxide nanoparticles grown on a ruthenium substrate using physical vapor deposition. Their morphology, shape, crystal structure, and chemical state are determined by low-energy electron...

mehr »
07.04.2016

Decrease of the required dopant concentration for δ-Bi2O3 crystal stabilization through thermal quenching during single-step flame spray pyrolysis

Authors:

Jochen A. H. Dreyer, Suman Pokhrel, Johannes Birkenstock, Miguel G. Hevia, Marco Schowalter, Andreas Rosenauer, Atsushi Urakawa, Wey Yang Teoh and Lutz Mädler.  

Journal:

CrystEngComm (2016) 18, 2046-2056.

doi:10.1039/C5CE02430G

Abstract:

δ-Bi2O3 is one of the best oxygen ion conductors known. However, due to its limited thermal stability and complicated synthesis techniques, its applications are limited. Here, the synthesis of stable nano-sized δ-Bi2O3 using versatile and rapid...

mehr »
31.03.2016

Controlling Heteroepitaxy by Oxygen Chemical Potential: Exclusive Growth of (100) Oriented Ceria Nanostructures on Cu(111)

 

Authors:

Jan Höcker, Tomáš Duchoň, Kateřina Veltruská, Vladimír Matolín, Jens Falta, Sanjaya D. Senanayake and J. Ingo Flege.

Journal:

The Journal of Physical Chemistry C (2016) 120, 4895−4901.

doi:10.1021/acs.jpcc.5b11066

Abstract:

A novel and simple method is presented for the preparationof a well-defined CeO2(100) model system on Cu(111) based on theadjustment of the Ce/O ratio during growth. The method yieldsmicrometer-sized, several nanometers high, single-phase CeO2...

mehr »
29.02.2016

Hierarchical Porous Zeolite Structures for Pressure Swing Adsorption Applications

Authors:

Benjamin Besser, Henrique Akira Tajiri, Gerd Mikolajczyk, Jens Moellmer, Thomas C. Schumacher, Stefan Odenbach, Roger Glaeser, Stephen Kroll and Kurosch Rezwan.

Journal:

ACS Applied Materials & Interfaces (2016) 8, 3277-3286.

doi:10.1021/acsami.5b11120

Abstract:

Porous adsorbents with hierarchical structured macropores ranging from 1 to 100 mu m are prepared using a combination of freeze casting and additional sacrificial templating of polyurethane foams, with a zeolite...

mehr »
29.02.2016

Two-Dimensional Heterojunctions from Nonlocal Manipulations of the Interactions

Authors:

M. Rösner, C. Steinke, M. Lorke, C. Gies, F. Jahnke, and T. O. Wehling

Journal:

Nano Letters (2016) 16, 2322-2327

http://dx.doi.org/10.1021/acs.nanolett.5b05009

Abstract:

We propose to create lateral heterojunctions in twodimensionalmaterials based on nonlocal manipulations of the Coulombinteraction using structured dielectric environments. By means of ab initiocalculations for MoS2 as well as generic semiconductor models, we showthat the Coulomb interaction-induced...

mehr »
27.01.2016

Thermodynamically consistent continuum dislocation dynamics

Authors:

Thomas Hochrainer.

Journal:

Journal of the Mechanics and Physics of Solids (2016) 88, 12-22.

doi:10.1016/j.jmps.2015.12.015

Abstract:

Dislocation based modeling of plasticity is one of the central challenges at the crossover of materials science and continuum mechanics. Developing a continuum theory of dislocations requires the solution of two long standing problems: (i) to represent dislocation kinematics in terms of a reasonable number of variables and (ii) to derive...

mehr »

2015

30.11.2015

Unraveling the Dynamic Nanoscale Reducibility (Ce4+ → Ce3+) of CeOx–Ru in Hydrogen Activation

Authors:

Jan Höcker, Tevfik Onur Mentes, Alessandro Sala, Andrea Locatelli, Thomas Schmidt, Jens Falta, Sanjaya D. Senanayake and Jan Ingo Flege.

Journal:

Advanced Materials Interfaces (2015) 2, 1500314.

doi:10.1002/admi.201500314

Abstract:

The interaction of molecular hydrogen with ceria is of important relevance for heterogeneous catalysis related to green chemistry and renewable energy. Here, the complex structural transformations of a well-defined cerium oxide model catalyst...

mehr »
23.10.2015

Tetrahedral Tetraphosphonic Acids. New Building Blocks in Supramolecular Chemistry

Authors:

Alexandra Schütrumpf, Erdoğan Kirpi, Aysun Bulut, Flavien L. Morel, Marco Ranocchiari,
Enno Lork, Yunus Zorlu, Simon Grabowsky, Gündoğ Yücesan, and Jens Beckmann.

Journal:

ACS Crystal Growth and Design (2015) 15, 4925-4931.

doi:10.1021/acs.cgd.5b00811

Abstract:

The structural characterization of tetraphenylmethane tetrakis- 4-phosphonic acid (4a) and its closely related Si-analogue tetraphenylsilane tetrakis-4-phosphonic acid (4b) is reported. Crystals of 4a,...

mehr »
25.09.2015

Water adsorption in SAPO-34: elucidating the role of local heterogeneities and defects using dispersion-corrected DFT calculations

Authors:

Michael Fischer.

Journal:

Physical Chemistry Chemical Physics (2015) 17, 25260-25271.

doi:10.1039/C5CP04189A

Abstract:

The chabazite-type silicoaluminophosphate SAPO-34 is a promising adsorbent for applications in thermal energy storage using water adsorption–desorption cycles. In order to develop a microscopic understanding of the impact of local heterogeneities and defects on the water adsorption properties, the interaction of different models of SAPO-34 with water...

mehr »
07.09.2015

Tuning emergent magnetism in a Hund's impurity

Authors:

A. A. Khajetoorians, M. Valentyuk, M. Steinbrecher, T. Schlenk, A. Shick, J. Kolorenc, A. I. Lichtenstein, T. O. Wehling, R. Wiesendanger and J. Wiebe.

Journal:

Nature Nanotechnology (2015) 10, 958–964.

doi:10.1038/nnano.2015.193

Abstract:

The recently proposed concept of a Hund's metal—a metal in which electron correlations are driven by Hund's rule coupling—can be used to...

mehr »
30.08.2015

Nanoscale Origin of Mesoscale Roughening: Real-Time Tracking and Identification of Three Distinct Ruthenium Oxide Phases in Ruthenium Oxidation

Authors:

Jan Ingo Flege, Benjamin Herd, Jan Goritzka, Herbert Over, Eugene E. Krasovskii and Jens Falta.

Journal:

ACS Nano (2015) 9, 8468-8473.

doi:10.1021/acsnano.5b03393

Abstract:

The structural modification of the Ru(0001) surface is followed in real-time using low-energy electron microscopy at elevated temperatures during exposure to molecular oxygen. We observe the nucleation and growth of three different RuO2 facets, which are unambiguously identified by single-domain microspot...

mehr »
30.07.2015

Modulation of Silica Nanoparticle Uptake into Human Osteoblast Cells by Variation of the Ratio of Amino and Sulfonate Surface Groups: Effects of Serum

Authors:

Shakiba Shahabi, Laura Treccani, Ralf Dringen and Kurosch Rezwan.

Journal:

ACS Applied Materials & Interfaces (2015) 7, 13821–13833.

doi:10.1021/acsami.5b01900

Abstract:

To study the importance of the surface charge for cellular uptake of silica nanoparticles (NPs), we synthesized five different single- or multifunctionalized fluorescent silica NPs (FFSNPs) by introducing various ratios of amino and sulfonate groups into their surface. The zeta potential values of these FFSNPs...

mehr »
30.06.2015

Proximity enhanced quantum spin Hall state in graphene

Authors:

Liangzhi Kou, Feiming Hu, Binghai Yan,Tim Wehling, Claudia Felser, Thomas Frauenheim and Changfeng Chen.

Journal:

Carbon (2015) 87, 418-423.

doi:10.1016/j.carbon.2015.02.057

Abstract:

Graphene is the first model system of two-dimensional topological insulator (TI), also known as quantum spin Hall (QSH) insulator. The QSH effect in graphene, however, has eluded direct experimental detection because of its extremely small energy gap due to the weak spin–orbit coupling. Here we...

mehr »
30.05.2015

Dinuclear Face-Sharing Bi-octahedral Tungsten(VI) Core and Unusual Thermal Behavior in Complex Th Tungstates

Authors:

Bin Xiao, Thorsten M. Gesing, Lars Robben, Dirk Bosbach and Evgeny V. Alekseev.

Journal:

Chemistry – A European Journal (2015) 21, 7746-7754.

doi:10.1002/chem.201500500

Abstract:

Two new thorium tungstates A6Th6(WO4)14O (A=K and Rb) were synthesized by high-temperature solid-state reactions. The structures of both phases are based on a rare dinuclear confacial bi-octahedral [W2O9]6− core, encapsulated in a [Th6W7O46(W2O9)]32− cage showing a cross-section geometry similar...

mehr »
30.04.2015

Phonon-pump extreme-ultraviolet-photoemission probe in graphene: Anomalous heating of dirac carriers by lattice deformation

Authors:

Isabella Gierz, Matteo Mitrano, Hubertus Bromberger, Cephise Cacho, Richard Chapman, Emma Springate, Stefan Link, Ulrich Starke, Burkhard Sachs, Martin Eckstein, Tim O. Wehling, Mikhail I. Katsnelson, Alexander Lichtenstein and Andrea Cavalleri.

Journal:

Physical Review Letters (2015) 114, 125503. doi:10.1103/PhysRevLett.114.125503

Abstract:

We modulate the atomic structure of bilayer graphene by driving its lattice at resonance with the in-plane E-1u lattice vibration at 6.3 mu...

mehr »
31.03.2015

Electron-Induced Hydration of an Alkene: Alternative Reaction Pathways

Authors:

Jonas Warneke, Ziyan Wang, Petra Swiderek and Jan Hendrik Bredehöft.

Journal:

Angewandte Chemie International Edition (2015) 54, 4397-4400. doi:10.1002/anie.201412147

Abstract:

Electron-induced reactions in condensed mixtures of ethylene and water lead to the synthesis of ethanol, as shown by post-irradiation thermal desorption spectrometry (TDS). Interestingly, this synthesis is not only induced by soft electron impact ionization similar to a previously observed electron-induced...

mehr »
28.02.2015

Robust Two-Dimensional Topological Insulators in Methyl-Functionalized Bismuth, Antimony, and Lead Bilayer Films

Authors:

Yandong Ma, Ying Dai, Liangzhi Kou, Thomas Frauenheim and Thomas Heine.

Journal:

Nano Letters (2015) 15, 1083-1089. doi:10.1021/nl504037u

Abstract:

One of the major obstacles to a wide application range of the quantum spin Hall (QSH) effect is the lack of suitable QSH insulators with a large bulk gap. By means of first-principles calculations including relativistic effects, we predict that methyl-functionalized bismuth, antimony, and lead bilayers (Me-Bi, Me-Sb, and Me-Pb) are 2D...

mehr »
28.02.2015

Electronic structures and optical properties of partially and fully fluorinated graphene

Authors:

S. Yuan, M. Roesner, A. Schulz, T. O. Wehling and M. I. Katsnelson.

Journal:

Physical Review Letters (2015) 114, 047403.  doi:10.1103/PhysRevLett.114.047403

Abstract:

In this Letter, we study the electronic structures and optical properties of partially and fully fluorinated graphene by a combination of ab initio G(0)W(0) calculations and large-scale multiorbital tight-binding simulations. We find that, for partially fluorinated graphene, the appearance of paired fluorine atoms...

mehr »
28.02.2015

Two-dimensional Cu2Si monolayer with planar hexacoordinate copper and silicon bonding

Authors:

L. Yang, V. Bacic, I. A. Popov, A. I. Boldyrev, T. Heine, T. Frauenheim and E. Ganz.

Journal:

Journal of the American Chemical Society (2015) 137, 2757-2762. doi:10.1021/ja513209c

Abstract:

Two-dimensional (2D) materials with planar hypercoordinate motifs are extremely rare due to the difficulty in stabilizing the planar hypercoordinate configurations in extended systems. Furthermore, such exotic motifs are often unstable. We predict a novel Cu2Si 2D monolayer featuring planar...

mehr »
31.01.2015

Bifunctional Submicron Colloidosomes Coassembled from Fluorescent and Superparamagnetic Nanoparticles

Authors:

T. Bollhorst, S. Shahabi, K. Wörz, C. Petters, R. Dringen, M. Maas and K. Rezwan.

Journal:

Angewandte Chemie International Edition (2015) 54, 118–123. doi:10.1002/anie.201408515

Abstract:

Colloidosomes are microcapsules consisting of nanoparticle shells. These microcarriers can be self-assembled from a wide range of colloidal particles with selective chemical, physical, and morphological properties and show promise for application in the field of theranostic nanomedicine. Previous...

mehr »
01.01.2015

Atomic electric fields revealed by a quantum mechanical approach to electron picodiffraction

Authors:

Knut Müller, Florian F. Krause, Armand Béché, Marco Schowalter, Vincent Galioit, Stefan Löffler, Johan Verbeeck, Josef Zweck, Peter Schattschneider and Andreas Rosenauer.

Journal:

Nature Communications (2014) 5, 5653.

doi:10.1038/ncomms6653

Abstract:

By focusing electrons on probes with a diameter of 50 pm, aberration-corrected scanning transmission electron microscopy (STEM) is currently crossing the border...

mehr »