International Guest Program
Every year through an international guest programm we will invite internationally recognized researchers in the field of energy materials and systems to FAU. for research visits and to give a colloquium on various research topics related to the IRTG.
Invited Speakers 2022
Electronic transport properties of ferroelectric domain walls – from fundamental physics to nanoelectronic applications
Jan Schultheiß, Norwegian University of Science and Technology, Norway (Mar 17)
Ferroelectric domain walls are natural interfaces separating volumes with different orientation of the spontaneous polarization. Because of their low symmetry, local electrostatics and confinement effects, the domain walls exhibit unusual electronic transport properties, ranging from highly insulating to metallic-like behavior. These unique properties, combined with their spatial mobility, make the walls attractive as ultra-small components for future nanoelectronics. In my talk, I will discuss the intriguing physics of ferroelectric domain walls and their emergent electronic properties with a focus on the response to alternating voltages. As an example for their technological potential, I will present how ferroelectric domain walls allow to control ac signal and enable completely new types of capacitors.
Yang Bai, University of Oulu, Finland (April 13)
Ferroelectric materials, after being poled, show piezoelectric and pyroelectric effects which can be used in self-powered kinetic and thermal sensors. Meanwhile, most ferroelectrics exhibit photovoltaic effect when being exposed to lights with photon energy above the band gaps of the ferroelectric materials in question. Photoferroelectrics take advantage of the simultaneous photovoltaic and ferroelectric effects in a single material and thus are beneficial for multi-source energy harvesting and multifunctional sensing devices. This talk will overview topical issues of self-sustainable microelectronics built on photoferroelectrics as well as scientific challenges of engineering photoferroelectric materials, including band gap engineering, trade-offs between strong ferroelectricity and narrow band gap, photo-stimulated domain wall motion, and improvement of photovoltaic energy conversion efficiencies compared to conventional solar cells. Perspectives will be given for further development of photoferroelectrics towards becoming core functional components in self-sustainable microelectronics.
Clive Randall, Materials Research Institute of Penn State University, USA (May 5)
Cold Sintering involves a transient phase that permits the densification of particulate materials at low temperatures 300°C and below. Sintering at such low temperature offers so many new opportunities. It permits the integration of metastable materials that would typically decompose at high temperatures. So cold sinter enables a platform for better unification of material science. Now ceramics, metal and polymers can be processed under a common platform in one step processes. With controlling the forming process new nanocomposites can be fabricated. Polymers, gels and nanoparticulates can be dispersed, interconnected and sintered in the grain boundaries of a ceramic matrix phase. With the ability to sinter metal phases, multilayer devices can be co-sintered with electrodes made from metals such as Al, Ag, Fe and Cu. With appropriate binder selection, polypropylene carbonate and its de-binding at 130°C we can remove organic binders and leave metals and other more stable polymers within the layers that then can be co-sintered under the cold sintering process and form unique combinations of materials in multilayers. This talk will cover some of the fundamentals of cold sintering, as well as some new examples of this technology across different material systems, ranging from ferroelectrics, semiconductors, and battery materials.
Madoka Ono, Research Institute for Electronic Science (RIES) at Hokkaido University, Japan (Jul 4)
Silica glass (SiO2) is widely used as the core material for optical communication fibers. The optical attenuation of the fiber is about 0.2 dB/km at the communication wavelength, but further reduction of the loss is required, due not only to reduce the number of amplifiers for optical signals, but also for the spread of quantum telecommunications, where amplification of quantum cryptography is impossible in principle. We have found that application of high pressure (200 MPa) at high temperature induce reduction of loss significantly down to less than 0.1 dB/km. Molecular dynamics calculations predict further reduction of the loss is expected. The mechanism and the effect of glass topology to such ultralow optical loss will be discussed.
Nanoelectronic Phenomena in Low-Dimensional Ferroelectrics
Alexei Gruverman, University of Nebraska, USA (Jul 21)
The last decade has seen an emergence of two-dimensional variants of ferroelectric materials. In the first part of my lecture, I will discuss a nanoscale insight into the electronic and electromechanical properties of one of the most exciting groups of emerging ferroelectrics – HfO2 family of simple oxides. In the second part, I will discuss the emerging electronic phenomena in the hybrid 2D structures comprised of 2D TMD and ferroelectric films.
Anna Grühnebohm, Ruhr-Universität Bochum, Germany (Oct 20)
Invited Speakers 2021
Katherine Faber, Caltech, USA (Feb 11)
Some zirconia-based compositions are known to exhibit shape-memory and superelastic effects. This was documented more than 30 years ago for possible use in actuation and energy damping. However, these effects were not successfully realized until the last decade when studies with micron- and sub-micron scale pillars and particles demonstrated that tetragonal-to-monoclinic transformation-induced fracture could be avoided. Inspired by micropillar studies, Prof. Faber will describe a strategy to produce bulk zirconia-based ceramics in which the transformation-generated fracture can be averted.
Jing-Feng Li, Toyota Research Center Tsinghua University, China (Apr 22)
This talk will introduce lead-free niobate-based perovskites including (K,Na)NbO3 and AgNbO3, both of which have been lying at the forefront of functional oxide research. (K,Na)NbO3 (abbreviated as KNN）is a promising lead-free ferroelectric/piezoelectric system, centering on which this talk will give a review about how high-performance piezoceramics have been developed. Based on our recent research about AgNbO3, I will also introduce antiferroelectricity and discuss its underlying connections with high piezoelectricity and dielectric energy storage performance.
Barbara Malic, Jozef Stefan Institute, Ljubljana, Slovenia (May 6)
Sodium potassium niobate (K0.5Na0.5NbO3, KNN) based ceramics are one of the groups of lead-free piezoelectrics, which have been intensively studied as possible replacements for highly efficient lead-based perovskite-oxide piezoelectrics. The enhancement of piezoelectric properties is mainly designed by phase boundary engineering. From the chemistry viewpoint such approach results in formulations which contain different cations occupying the same lattice sites, consequently reaching a homogeneous distribution of constituent ions may be difficult. In the lecture solid-state synthesis and sintering of KNN-based ceramics are reviewed and supported by selected case-studies.
Zero-Power ” Flexible Wireless Modules & Inkjet/3D/4D printed electronics for IoT, SmartAg and Smart Cities Ultrabroadband Applications
Manos M. Tentzeris, Georgia Institute of Technology, USA (Sep 9)
In this talk, inkjet-/3D printed antennas, interconnects, “smart” encapsulation and packages, RF electronics, microfluidics and sensors fabricated on glass, PET, paper and other flexible substrates are introduced as a system-level solution for ultra- low-cost mass production of Millimeter-Wave Modules for Communication, Energy Harvesting and Sensing applications. Prof. Tentzeris will touch up the state-of-the-art area of fully-integrated printable broadband wireless modules covering characterization of 3D printed materials up to E-band, novel printable “ramp” interconnects and cavities for IC embedding as well as printable structures forself-diagnostic and anti-counterfeiting packages. Prof. Tentzeris will discuss issues concerning the power sources of „near- perpetual“ RF modules, including state-of-the-artflexible miniaturized enhanced-output and enhanced-range ambient energy harvesters up to above 5G mmW frequencies.
Zoya Popovic, University of Colorado (Oct 7)
This talk will overview wireless power transfer for power levels from mW to kW. The ultra-low power density application is in far-field harvesting at GHz frequencies for unattended wireless sensors. In this case, efficiency and power management are challenging, as well as miniaturization and energy storage. Several examples will be shown, including harvesting sidelo bes from a 4.3GHz altimeter radar antenna on a Boeing 737 aircraft for powering health-monitoring aircraft sensors. At the high power levels, near-field capacitive power transfer is chosen in the 6 MHz range for powering stationary vehicles and vehicles in motion. In this case, over 85% efficiency is achieved for 1kW of capacitive power transfer while meeting safety standards in the vicinity of the vehicle through a near-field phased array approach. Other approaches, such as power beaming and multi-mode shielded wireless powering will also be discussed.
Piezoelectric energy harvesting leveraging concepts from nonlinear dynamics, metamaterials, and phononic crystals
Alper Erturk, Georgia Tech (Nov 11)
This talk will review our efforts on piezoelectric energy harvesting from vibrations and elastic/acoustic waves for low-power electricity generation. Following a brief introduction to linearized piezoelectric energy harvesting, we will discuss how to leverage designed (intentionally introduced) monostable/bistable nonlinearities (of Duffing type) for frequency bandwidth enhancement via experimental case studies, approximate analytical modeling, and numerical simulations. We will also address the modeling and analysis of inherent piezoelectric material and internal/external dissipative nonlinearities (and their interaction with designed nonlinearities), as well as circuit nonlinearities, along with experimental validations. Multifunctional concepts will also be discussed, such as the combination of piezoelectric energy harvesting with locally resonant bandgap formation in metastructures (i.e. metamaterial-based finite structures) for concurrent vibration attenuation and electricity generation. Nonlinearities are exploited in that context as well, in order to achieve amplitude-dependent broadband attenuation (and harvesting) beyond linear metamaterial-based bandgap formation, by employing unit cells with bistable piezoelectric energy-harvesting attachments. If time permits, we will switch from vibrations and standing waves to propagating waves, with demonstrations of using 2D/3D phononic crystal-based lens designs for the enhanced harvesting of elastic/acoustic waves.
Marc Kamlah, KIT (Dec 9)
This presentation starts with a general introduction into piezo- and ferroelectricity. We then present the general framework of the theory of electromechanics. Next, basic features of leadfree ergodic and non-ergodic relaxorceramics will be reviewed. The characteristic hysteresis properties will be introduced. In addition, the overall actuation behavior of bi-layer composites is discussed. For these types of materials, departing from previous constitutive models developed for soft PZT piezoceramics, constitutive models will be motivated. The theory has been implemented in COMSOL Multiphysics. Of special interest is the large signal d33* piezoelectric coefficient. Here, the focus will be on the question under which conditions the d33* of a bilayer composite is higher than the one of the two endmember materials, and when the d33* of the composite does not simply follow a rule of mixtures. In this respect, multiple related simulations have been carried out and will be discussed.
Invited Speakers 2020
Prof Andrew Bell, School of Chemical and Processing Engineering, University of Leeds, UK (May 19)
This tutorial provides an insight into how the intrinsic properties of piezoelectrics are interdependent and lead to well-defined trends in properties across large material data sets.
Prof Susan Trolier-McKinstry, Department of Materials Science and Engineering, Pennsylvania State University, USA (Jun 2)
A century after the discovery of ferroelectricity, this class of materials continues to be an enabling technology in a number of technological areas. This presentation discusses the history of research in ferroelectrics and related phenomena up to the present, highlighting especially important discoveries.
Prof Roger Whatmore, Imperial College London, UK (Jun 16)
This talk provides a background on pyroelectrics, including the physics of pyroelectric infra-red sensors and how to choose pyroelectric materials for a given applications. Finally, IR sensor arrays for movement sensors and thermal imaging are discussed.
Dr. Brendan Hanrahan, U.S. Army Research Laboratory (Jun 30)
This talk provides an introduction to power generation with pyroelectric materials, including a discussion of application specific considerations for enhancing the energy conversion.
Dr. Marco Deluca, Materials Center Leoben Forschung GmbH, Austria (Jul 14)
This talk gives an introduction to Raman spectroscopy and its use in characterizing ferroelectric materials in terms of phase transitions, crystalline texture, chemical bonding, and disorder and defects.
Prof. Dr. Paolo Colombo, University of Padova, Italy (Jul 28)
This talk gives an overview of additive manufacturing techniques for the production of 3D ceramic parts, including the advantages and limitations of the various techniques.
Prof. Dr. Shujun Zhang, University of Wollongong, Australia (Aug 25)
Prof. Shujun Zhang discusses the mechanisms responsible for the observed giant electromechanical response of relaxor-PT-based single crystals. The concepts of crystal anisotropy, polarization rotation, morphotropic phase boundaries, and local structure heterogeneities are discussed.
Prof. Dr. Wook Jo, Ulsan National Institute of Science and Technology, South Korea (Sep 8)
Prof. Wook Jo discusses the development of lead-free ferroelectrics as well as limitations to their future improvement and possible methods to increase the piezoelectric response.
Dr. Neus Domingo, Catalan Institute of Nanoscience and Nanotechnology, Spain (Sep 22)
This presentation introduces adsorbates on ferroelectric surfaces and redox reactions with water and contaminant organic molecules, in addition to the influence of polarization and chemically active sites. Various measurement techniques, such as ambient-pressure X-ray photoelectron spectroscopy and force microscopy methods are discussed.
Prof. Dr. Efrat Lifshitz, Israel Institute of Technology (Sep 29)
Prof. Dr. Jacob Jones, North Carolina State University, USA (Oct 6)
In this presentation, Prof. Jones discusses using diffraction techniques to determine the domain wall motion in ferroelectric materials, in particular the contribution of extrinsic effects on the macroscopic electromechanical properties.
What would it take for renewably based electrosynthesis products to substitute those obtained from petrochemical processes
Prof. Dr. Juan Morante, Institut de Recerca en Energia de Catalunya, Spain (Oct 13)
Dr. Manuel Hinterstein, Karlsruhe Institute of Technology, Germany (Oct 20)
This presentation discusses diffraction characterization and analysis techniques to determine extrinsic contributions to the macroscopic electromechanical response from both domain wall motion as well as from coexisting phases. Examples are given from lead-containing as well as lead-free ferroelectric systems.
Prof. Dr. Jürgen Rödel, Technische Universität Darmstadt, Germany (Nov 17)
Alexander Colsmann, Karlsruhe Light Technology Institute, Germany (Dec 1)
Ahmad Safari, Glenn Howatt Electroceramics Laboratories (Dec 15)
This presentation introduces the history and concept of composites for piezoelectric and dielectric applications.