TU Graz
Graz University of Technology

Advanced Materials Science

The Field-of-Expertise Advanced Materials Science is an interdisciplinary network of researchers at the TU Graz in chemistry, physics, architecture, mechanical engineering, civil engineering, electrical engineering and geodesy who discover, characterize and model materials, functional coatings and components. Thirty-one institutes from six faculties are presently involved.

Advanced Materials Day is the yearly meeting where the members of the FOE present their latest results. In 2018, the meeting will be held on September 21 at the Neue Technik campus in the Biomedical Technology building.

 

Talks

09:00 - 09:10

Introduction
Peter Hadley


09:10 - 09:30

Real-time tracking of electron and spin dynamics
Martin Schultze, Inst. f. Experimentalphysik

Abstract: By means of attosecond spectroscopy we can explore electron and spin dynamics in real time. This information can be crucial to understand the microscopic origin of a functional material’s interaction with light. As examples I will show how quickly silicon can absorb a photon and introduce an experiment that recorded the fastest magnetic switching ever achieved.

09:30 - 09:50

Porous Materials @ Work
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09:50 - 10:10

Design of sustainable hybrid electrochemical capacitors
Qamar Abbas, Institute for Chemistry and Technology of Materials

Abstract: Hybrid electrochemical capacitors display higher power than batteries and higher energy than electrical double-layer capacitors (EDLCs). Generally, in these devices, high surface area activated carbon is used as electrode materials. To enhance energy, we have implemented redox active aqueous electrolyte which transforms the charging mechanism of positive electrode to a battery-like, and it is then internally hybridized with an electrical double-layer (EDL) negative electrode. Thereby, a hybrid cell displays twice higher capacitance than its symmetric counterpart. This construction is advantageous owing to the low assembling cost, no toxicity issues and high cycling performance. The presentation will include data related with investigation of carbon/redox specie interface by thermogravimetry coupled with mass spectrometry (TG-MS) and Raman spectroscopy.


10:10 - 10:30

Studies of ionizing radiation effects in nanoscale CMOS technology nodes
Alicja Michalowska-Forsyth , Institute of Electronics

Abstract: X-ray radiation damage of semiconductor devices originates from radiation-induced fixed charge in the insulating regions and interface traps [1]. Device arrays fabricated in 28 nm bulk CMOS with pMOSFET and nMOSFET transistors of different dimensions have been studied. Stress tests have been performed with X-rays of energies in range 10 to 40 keV. Transfer and output characteristics have been measured before irradiation as well as after 12 steps of total ionizing dose (TID) to track evolution of device parameters. These steps start with 100 krad and 500 krad, corresponding to TID levels close to those experienced by instruments in space missions or medical imaging and reach ultrahigh levels of 900 Mrad, which is of interest for high energy physics experiments. Similarly to older technology nodes the effect of radiation induced narrow channel effect (RINCE) [2] related to traps within the shallow trench isolation (STI) is observed on device characteristics. Transistors in the 28 nm process, in contrast to technology nodes down to 65 nm already widely studied for TID effects, are equipped with high-K/metal gate. Therefore material properties and formation of traps might have to be reconsidered when interpreting the post-irradiation measurement results. TCAD device model including HfO2 - SiO2 gate stack and strained channel is adapted to measurement results. In this talk the 28nm CMOS process will be introduced and selected device parameters will be analysed with respect to radiation damage. Finally the approach of employing the model to examine various radiation damage effects observed after TID stress will be discussed.



[1] Oldham, Timothy R., and F. B. McLean. "Total ionizing dose effects in MOS oxides and devices." IEEE transactions on nuclear science 50.3 (2003): 483-499.
[2] Faccio, F., et al. "Radiation-induced short channel (RISCE) and narrow channel (RINCE) effects in 65 and 130 nm MOSFETs." IEEE Transactions on Nuclear Science 62.6 (2015): 2933-2940.

10:30 - 11:00

Coffee Break

11:00 - 11:20

Silica-based nanostructured particles/ SOMAPP Lab
Angela Chemelli, Institute of Inorganic Chemistry

Abstract: Lipid based liquid crystalline systems form various structures depending on the lipid composition, their hydrophilic head group as well as their lipophilic tail. These self-assembled structures formed are affected by temperature and additives[1–4]. Additionally, they can also be dispersed to form nanostructured particles.
Analogous tuning of the self-assembled structure of amphiphilic precursors for silica based materials is performed. An amphiphilic trialkoxy silane precursor is synthesized by the condensation of (3-aminopropyl)trialkoxysilane with a fatty acid. The amide group of the product stabilizes the self-assembled structure by the formation of hydrogen bonding between the monomers. The self-associated structure is subsequently polycondensed by acidic conditions, resulting in nanostructured silica based material.
The control over the nanostructure of the formed materials and particles is of great interest for the design of functional materials. By adjusting the synthesis conditions, choice of fatty acid residue as well as the use of hydrophilic and hydrophobic additives the structure of the silica based material and particles can be controlled.



[1] A. Chemelli, B. Conde-Valentín, F. Uhlig, O. Glatter, Langmuir 31 (2015) 10377–10381.
[2] A. Chemelli, M. Maurer, R. Geier, O. Glatter, Langmuir 28 (2012) 16788–16797.
[3] A. Yaghmur, L. De Campo, L. Sagalowicz, M.E. Leser, O. Glatter, Langmuir 22 (2006) 9919–9927.
[4] S. Guillot, S. Salentinig, A. Chemelli, L. Sagalowicz, M.E. Leser, O. Glatter, Langmuir 26 (2010) 6222–6229.

SOMAPP Lab - Soft Matter Application Lab

The SOMAPP Lab is a core facility for the comprehensive analysis of materials especially soft matter. This joint project, in cooperation with Anton Paar GmbH and the Karl-Franzens University, is supported by the Austrian Federal Ministry of Education, Science and Research.

11:20 - 11:40

Formation processes of dolomite at low temperature
Bettina Purgstaller, Institute of Applied Geosciences

Abstract: Dolomite is a Ca-Mg-carbonate mineral that is abundant in ancient carbonate platforms and is an important component of petroleum reservoir rocks. In its ideal state dolomite has the stoichiometric composition CaMg(CO3)2 (i.e. molar Ca:Mg = 1:1) and consists of an ordered arrangement of alternating layers of Ca2+ and Mg2+ cations interspersed with CO32- anion layers normal to the c-axis. The formation conditions of dolomite are not clearly understood as so far dolomite synthesis from an aqueous fluid under laboratory conditions and at ambient temperatures has not been established. Recent synthesis experiments at >140°C indicate that dolomite forms through a series of intermediate phases starting with an amorphous calcium magnesium carbonate (ACMC) precursor being replaced by very high Mg-calcite (VHMC). The VHMC products are subsequently replaced by a stoichiometric dolomite. However, a large gap of knowledge exists with respect to this reaction pathway at low temperature.
In the present study, the transformation of ACMC to Ca-Mg-carbonates was experimentally studied by dispersion of synthesized ACMC standard material with 48 ±1 mol% MgCO3 into a NaHCO3-MgCl2 solution (T = 10 to 80°C; pH = 7.6 ±0.2). X-ray diffraction patterns showed that the reaction products in experiments performed at 10 to 40°C consist of high Mg-calcite with 15 to 30 mol% MgCO3, while at 60 and 80°C VHMC with near-dolomite stoichiometry (40 mol% MgCO3) was found. Our results show that the transformation of ACMC into HMC takes place via a dissolution-reprecipitation process and is strongly controlled by the Mg/Ca ratio of the reactive solution rather than by the precursor material. The incorporation of Mg in calcite is favored at higher temperatures most likely due to the faster dehydration kinetics of the aqueous Mg2+ ion at high versus low temperature.




11:40 - 12:00

Eduardo Machado Charry

12:00 - 12:20

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Posters 15:30 - 17:30

Influence of Molecule Size on Surface Polymorph Formation
Andreas Jeindl, Institute of Solid State Physics

Auxiliary master equation approach to the single-impurity Anderson model out of equilibrium
Delia Fugger, Institute of Theoretical and Computational Physics

Thermomechanical Simulations of Microelectronics Packaging
Fabian Huber, Institute of Solid State Physics, Graz University of Technology

Describing complex intramolecular interactions with Bayesian Learning: Pushing the Feature Vector to the limit
Fabian Weißenbacher, Institute of Solid State Physics, Graz University of Technology

Raman microscopy of inorganic materials – A stone is a stone! Is a stone?
Harald Fitzek, Institute of Electron Microscopy and Nanoanalysis

Abstract: “In our current laboratory exercise research project we are investigating the composition of common inorganic materials (such as rocks, dirt, crystals, and building materials) and the microscopic imaging of their components. A selection of samples from interested hobby geologist will be available, but students are also encouraged to bring their own samples (anything you are interested in from the soil in your back yard, to a weird looking rock you found while hiking). Our goal is to demonstrate that even in the limited time available during a lab exercise it is possible to produce a good quality analysis of a complex real world sample.”

In several lab exercises, we have look at two collection of stones, one purchased by a student and another one collected by a student during a hiking trip. Additionally, building materials from a private home construction side were analyzed.

Feature Selection for Functional Properties: Predicting Surface Rearrangements
Johannes J. Cartus, Graz University of Technology


Smart-Data Machine Learning for Surface Polymorph Prediction
Lukas Hörmann

Abstract: In this contribution we introduce the SAMPLE approach[1,2], a structure search tool for commensurate organic monolayers on inorganic substrates. The major challenge hereby is the large number of possible polymorphs such monolayers can form. To overcome this challenge, SAMPLE employs physically motivated coarse-grained modeling in combination with Bayesian linear regression to efficiently explore the potential energy surface.

SAMPLE works as follows: First, we determine the adsorption geometries isolated molecules adopt on the substrate. Then, we arrange these geometries in a large number of different ways to generate possible polymorphs. Experimental design theory allows us to select a subset of these polymorphs, for which we determine the adsorption energies using dispersion-corrected density functional theory. These data serve as training set for an energy model, consisting of inter-molecule and molecule-substrate interactions. Bayesian linear regression enables determining these interactions and thereby allows to not only gain meaningful physical insight but also predict the adsorption energies for millions of possible polymorphs and find the energetically most favorable one.

The capabilities of our approach are shown using three complementary molecules on coinage metals.

[1] Hörmann et al., Computer Physics Communications (2019)

[2] Scherbela et al., Phys. Rev. Materials 2, 043803 (2018)

Simulating Charge Transport Through Metal-Organic Semiconductor Interfaces: Bulk or Contact Limited?
Markus Krammer, Institute of Solid State Physics

Abstract: The performance of organic electronic devices crucially relies on an efficient charge injection. This efficiency is governed by a complex interplay of experimentally tunable properties like level alignment and disorder. The impact of this interplay on the bulk current is only poorly understood from a theoretical point of view. To overcome this lack of knowledge, we utilize mesoscopic simulations to predict the current density across the contact interface. In these simulations, charges are viewed to migrate through disordered organic semiconductors due to hopping between localised states. Parameters like injection barrier, energetic disorder, electric field, Coulomb interactions and temperature can be directly considered. This intuitive method holds the promise to understand the effects and interactions that govern the interplay between interfacial and bulk properties. We analyse the current density for instructive combinations of interface and bulk properties. This analysis yields two distinct regimes, a bulk limited regime and a contact limited regime. The evolution of the current density with respect to injection barrier, energetic disorder and electric field strength is investigated and the origin of bulk vs. contact limitation is analysed.

On the unexpected behaviour of Ni-Au and Co-Au core-shell nanoparticles
Martin Schnedlitz, Institute of Experimental Physics

Abstract: We present molecular dynamics simulations, static basin hopping calculations as well as comparisons with transmission electron microscopy (TEM) studies of 5 nm Ni-Au and Co-Au core-shell particles upon heating. The bimetallic nanoparticles are monitored through a heating cycle up to 1300 K and their structural rearrangement is observed. Via static basin hopping calculations we show that decentralised cores represent for both model systems the energetically most stable configuration. Heating can trigger a rearrangement of an initially centralised cores, however, as temperature increases entropy becomes more dominant, which finally can result in an alloying of the cluster. We show that this fascinating behaviour is an interplay between atomistic and bulk characteristics deduced from surface size effects and bimetallic phase diagrams.

Particularly interesting are also studies of oxidation effects and structural rearrangements in core-shell systems where a reactive metal (e.g. Ni) is covered by protective layers of a Au shell. The mere presence of of oxygen species enhances the process of Ni diffusion through the Au shell.footnote{M.~Schnedlitz, M.~Lasserus, R.~Meyer, D.~Knez, F.~Hofer, W.E.~Ernst and A.W.~Hauser, emph{Chem. Mat.}, 2018} The structural integrity of ferromagnetic cores under gas atmosphere plays an important role for future applications of these novel bimetallic nanoparticles.

Three-dimensional geometric integrator for charged particle orbits in toroidal fusion devices
Michael Eder, Fusion@ÖAW, Institut für Theoretische Physik - Computational Physics, Technische Universität Graz, Petersgasse 16, A–8010 Graz, Austria

Abstract: A three-dimensional integrator for guiding center orbits of charged particles in toroidal fusion devices with 3D field geometry is described. The integrator uses a representation of the electro- magnetic field by low order polynomials on a 3D tetrahedal grid and is intrinsically designed to preserve the total energy, perpendicular adiabatic invariant, and the phase space volume accu- rately for any grid size. Thus, it belongs to the class of geometric integrators.
The integrator is designed for usage in Monte Carlo (MC) procedures to simulate particle distri- bution functions where a box counting method (calculation of dwell time within spatial cells) is used for the evaluation of macroscopic plasma parameters. Such a computation is needed, e.g., for the evaluation of plasma response currents and charges caused by external non-axisymmetric electromagnetic perturbations in tokamaks as well as for kinetic modeling of edge transport in devices with 3D field geometry.
This geometric integrator is more efficient in evaluation of dwell times than a solution of guid- ing center equations with a high order adaptive ODE integrator, while keeping roughly the same speed for orbit computations, because dwell times and the particle’s coordinates and velocities at boundaries of spatial cells are intrinsically available without additional efforts for tracing the intersections with cell boundaries. Similar to the 2D geometric integrator of Ref. [1] also the 3D geometric integrator is less sensitive to inaccurate representation of the electromagnetic field resulting from statistical noise in plasma response currents and charges computed by a MC method within a feedback loop.
Artificial numerical diffusion which can arise in presence of perturbations is extensively dis- cussed. It can be shown that the use of field aligned coordinates is beneficial and that such a diffusion scales inversely with the grid size and thus can be kept well below neoclassical values.
References
[1] S.V.Kasilov,A.M.Runov,W.Kernbichler,ComputerPhysicsCommunications207,(2016),282–286

Simulating the Oxidation of AlGaAs in Semiconductor Devices
Michael Pusterhofer, Institute of Solid State Physics, Graz University of Technology

Towards new plasmonic materials: Synthesis of K and K-Au nanoparticles with helium droplets
Roman Messner, Institute of Experimental Physics

Abstract: We report on experiments on K and bimetallic K-Au nanoparticles produced under UHV conditions by synthesis in helium nanodroplets. Bimetallic K-Au nanoparticles are promising candidates as building blocks for future meta-materials due to their excellent plasmonic properties. Considering the growing importance of plasmonic technology with diverse applications, for example, in photovoltaics, medical diagnostics, catalysis and surface enhanced Raman spectroscopy, the search for better plasmonic materials constitutes an important task for both science and industry.
The investigated particles were fabricated by coagulation of metal atoms after pickup by cold helium nanodroplets. The employed experimental techniques encompass in-situ in-flight spectroscopy, as well as ex-situ examinations via transmission electron microscopy. Beam depletion spectroscopy reveals a strong resonance in plain K clusters isolated in HeN at about 600 nm, in agreement with experiments on free K clusters. The position of the resonance depends on the K partial pressure in the pickup region, i.e. the size of the nanoparticles. After adding a Au pickup zone subsequently to the K pickup region, a blue shift of the resonance is observed, towards the well-known localized plasmon resonance of plain Au nanoparticles. A very important aspect of our current research is to test the possibility of passivating the highly reactive K clusters with a Au shell, which may be possible with the helium droplet technique. First TEM investigations show promising results, opening up new perspectives for the production of novel materials and material combinations for plasmonics with helium droplet based nanoparticle synthesis.

Development of site-specific arrays of pressure, temperature and humidity multi-responsive nanorods
Taher Abu Ali, Institute of Solid State Physics

Understanding Phonon Properties in Metal-Organic Frameworks From First Principles
Tomas Kamencek, Institute of Solid State Physics, Graz University of Technology

Surface Crystallization Studies of 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10)
Wolfgang Rao Bodlos