Symposium CJ
Advances in Electroceramics: Processing, Structure, Properties, and Applications

Session CJ-1 - Dielectrics and Microwave Materials

CJ-1:IL01  Ultra-Low Temperature Co-fired Ceramics (ULTCC) – Current Situation and What is Needed for Industrial Applications
J. VARGHESE, M.Y. CHEN, N. JOSEPH, M. SOBOCINSKI, H. JANTUNEN, Microelectronics Research Unit, University of Oulu, Faculty of Information Technology and Electrical Engineering, Oulu, Finland

The progress in the field of ultra-low sintering temperature ceramics has made it possible to fabricate multilayer and multimaterial ceramic modules with embedded electronics at temperatures even as low as 350 oC. This enable the mitigation of the diffusion and thermal expansion problems normally faced during the sintering process. In addition, many passive and active components embedded to these co-fired ceramic modules can survive. This paper presents the most recent advancements including the feasible ceramic compositions, tape casting procedure, embedding of electronics and the applications introduced so far. The results are also compared to the Low Temperature Co-fired Ceramics (LTCC) technology in the means of what is still missing, what advantages are available for industry and how to proceed?


CJ-1:IL02  Microwave and THz Characterization of Electroceramics
D. JABLONSKAS, M. IVANOV, J. MACUTKEVIC, S. RUDYS, R. GRIGALAITIS, S. LAPINSKAS, S. SVIRSKAS, J. BANYS, Vilnius University, Vilnius, Lithuania

The dielectric response of materials provides information about the orientational adjustment of dipoles present in a dielectric medium in response to an applied electric field. Microwave and terahertz dielectric spectroscopy of electroceramics enables the independent determination of the dielectric permittivity and loss in the dispersion region, as well as the parameters of the soft modes related to phase transitions. Computer controlled spectrometers are now the norm in dielectric spectroscopy. Computers allow the computation of electromagnetic fields in entirely new measurement geometries and the use of numerical analysis in the direct measurement process. The use of such spectrometers is now one of the most fruitful factors in new approaches to microwave dielectric spectroscopy. The most important problem now is the rigorous mathematical solution of the microwave interaction with the samples in various geometries. Although there is now complete overlap and coverage of the radio frequency to the infrared band, the different experimental methods based on coaxial and waveguide techniques, is still divided and will be presented. Examples of NBT-ST-PT ceramics will be presented.


CJ-1:L04  Electrical Resistivity of Silicon Nitride Produced by Various Methods
O. LUKIANOVA, Belgorod State National Research University, Belgorod, Russia

Silicon nitride ceramics are frequently used as structural and engine components for high-temperature applications and high-temperature dielectrics. In this case, the electrophysical properties are key and most important for reported ceramics. These properties directly depend on the microstructure, the amount of impurities dissolved in the lattice or on the grain boundary in the form of other phases, and the nature of their distribution. The type of the conductivity was determined and its mechanism was described. The activation energy and the band gap of the reported silicon nitride ceramics were calculated for materials obtained by such sintering methods as sparkling plasma sintering and pressureless sintering. It was shown that the obtained results and dependencies are in a good agreement with the literary data. Thus, in our work the influence of the most widely used types of additives and production regimes on the electrical resistivity of silicon nitride ceramics has been investigated by the example of the pressureless sintering and spark plasma sintering.


CJ-1:L05  Aluminiumoxide and Hafniumoxide as Nonlinear Dielectrics
L. KANKATE, H. KLIEM, Institute of Electrical Engineering Physics, Saarland University Campus A5, Saarbruecken, Germany

The AC capacitance C versus DC electric bias field E of metal-insulator-metal (MIM) devices comprising thin films of Al2O3 and HfO2 ceramic shows a nonlinear behavior i.e. C increases quadratically with increasing E in high fields. There exists also a frequency f dispersion of C(E, f). The capacitance is found to be decreased linearly with increasing log(f) revealing a distribution of relaxation times. For the applications of metal oxides in electronics the observed nonlinearity must be suppressed. To explain the nonlinearity we have developed an asymmetric double well potential (ADWP) model where charges can fluctuate via a tunneling transition and/or a thermally activated process. This yields a change in polarization. Tunneling happens via protons whereas metal and oxygen ions may fluctuate by thermal activation. ADWPs for protons are found between negatively charged oxygens. Our ADWP model well interprets the observed C(E,f) behaviors. Evaporating Al2O3 under O2 atmosphere as well as post annealing of MIM devices to moderate temperatures leads to reduce the C(E) nonlinearity by 75%. Treating the samples with H2 gas by using Pd as an electrode, results in an increase of the nonlinearity because the density of protons in the oxide is increased by diffusion from the Pd electrode.


CJ-1:L07  Ceramics Materials and Microelectronic Energy Frontiers
V.V. MITIC^{1, 2}, V. PAUNOVIC¹, N. CVETKOVIC¹, G. LAZOVIC³, L. KOCIC¹, ¹University of Nis, Faculty of Electronic Engineering, Nis, Serbia; ²Institute of Technical Sciences of SASA, Belgrade, Serbia; ³University of Belgrade, Faculty of Mechanical Engineering, Belgrade, Serbia

World’s perennial need for energy and microelectronic miniaturization yields the whole spectra of technological challenges and scientific tasks. An important stream in finding new solutions leads over materials characterized by precise microstructural architecture based on fractal analysis covering wide size ranges down to nano scale. Having such a deep geometric hierarchy opens new possibilities in energy storage capacities and intergranular relations supported by fractal resources. These novel ideas are natural continuation of some early fractal applications have been used as a tool in energy and microelectronic miniaturization research, applying on diverse energy technologies. All three items that are essential regarding energetic questions, free energy stocks location, energy harvesting and short/ long term energy storage have their specific common points with fractal nature. Also, the concept of energy as physical objects property, share some features characteristic to fractal objects. In other words, fractal, as a crucial concept of modern theoretical-experimental physics is tightly connected with the process of cultivating the wild energy as well. Here, the above items will be discussed.


Session CJ-2 - Ferroelectric, Piezoelectric, Pyroelectric, and Ferroelastic Ceramics

CJ-2:IL02  Domain Walls in Multiferroic Bismuth Ferrite: An Ab Initio Study
O. DIEGUEZ, Department of Materials Science and Engineering, Tel Aviv University, Tel Aviv, Israel

We present a computational study of ferroelectric domain walls in multiferroic bismuth ferrite (BFO), a material in which the ferroelectric order parameter coexists with antiferrodistortive modes involving rotations of the oxygen octahedra. For neutral domain walls, we find that the energetics of the domain walls are dominated by the capability of the domains to match their octahedra rotation patterns at the plane of the wall, so that the distortion of the oxygen groups is minimized. We also report results where we analyze the possibility that the domain walls are charged, and where we take into consideration the interaction between those walls and oxygen vacancies, which are known to strongly influence the properties of perovskite oxides.


CJ-2:IL03  Niobate Based Lead-free Ceramics for Piezoelectric and Energy Storage Applications
JING-FENG LI, School of Materials Science and Engineering, Tsinghua University, Beijing, China

There is a strong societal demand to develop eco-friendly lead-free materials for green applications. In particular, research and development on lead-free piezoelectric ceramics have continued for more than one decade, and extensive studies have been concentrated on sodium potassium niobate (K,Na)NbO3 (KNN), whose piezoelectricity has been pushed to a high level close to that of PZT family. One of the remaining challenges is that highly enhanced piezoelectricity of KNN based ceramics usually lacks a temperature stability, which has been recognized or even overemphasized as its distinct shortcoming as compared with PZT. In this talk, several approaches to overcome this problem will be presented with an emphasis on a simultaneous enhancement of piezoelectricity and thermal stability. In association with niobate lead-free piezoceramic research, our recent studies revealed the potential of AgNbO3 as a promising lead-free ceramic for energy storage applications. Enhanced energy storage performance, with recoverable energy density of 4.2 J cm-3 and high thermal stability of the energy storage density (with minimal variation of < ±5%) over 20-120 oC, could be achieved in Ta-modified AgNbO3 ceramics.


CJ-2:IL05  Nanoscale Susceptibilities in Ferroelectric Thin Films: Insights from Multidimensional Spectroscopy and Machine Learning
L. MARTIN, J. AGAR, University of California at Berkeley, USA

Large susceptibilities in ferroelectrics depends on our ability to drive reconfiguration of the ferroic order parameter with externally-applied stimuli. Consequently, there is interest in understanding how ferroelectric order, at multiple length scales, responds under applied fields; and what this means for macroscopic properties. In recent years, in operando (e.g., piezoresponse force microscopy (PFM), transmission electron microscopy, etc.) capable of probing stimuli-driven changes in ferroelectric order at the appropriate length and time scales have become available. These approaches, however, have led to an orders-of-magnitude increase in the volume, variety, veracity, and velocity of the experimentally-generated data; rendering conventional analysis approaches untenable. Here, using multidimensional PFM spectroscopies we show how machine learning can bring physically-important phenomena concealed within “big” hyperspectral data into focus for interpretation. Specifically, we highlight how physically-guided featurization protocols in conjunction with machine learning and deep-learning neural networks can be applied to glean new insights regarding how nanoscale, 3d domain geometry can be exploited to enhance piezoelectric responses and electromechanical energy conversion.


CJ-2:IL09  Iron’s Valence Control of BiFeO3-based Piezoelectric Ceramics for Property Enhancement
SATOSHI WADA¹, T. AIZAWA¹, S. UENO¹, I. FUJII¹, N. KUMADA¹, C. MORIYOSHI², Y. KUROIWA², ¹Material Science and Technology, University of Yamanashi, Yamanashi, Japan; ²Department of Physical Science, Hiroshima University, Hiroshima, Japan

It is well known that for relaxor-based ferroelectrics, the domain configuration is dependent on chemical composition and orientation.  This means that if relaxor-based lead-free ferroelectrics are prepared, it can be expected that they might have high piezoelectric performances.  Recently, we reported that BT-Bi(Zn_1/2Ti_1/2)O₃ (BT-BZT) and BT-Bi(Mg_1/2Ti_1/2)O₃ (BT-BMT) were relaxor ferroelectrics with high T_max (temperature with maximum dielectric constant) over 250 ˚C.  Thus, it is possible to control domain configurations by solid solution system between the above relaxors and normal ferroelectric such as BiFeO₃ (BF) with high T_c of 830 ˚C.  In this study, the BT-BMT-BF and BT-BZT-BF system ceramics were prepared using a conventional solid–state reaction and their crystal structure and electrical properties were investigated.  A single phase of perovskite was prepared for these ceramics with various compositions except for a few.  TEM observation revealed that BT-BMT had no domain configuration while BF-rich ceramics had normal rhombohedral domain configurations.  Moreover, the ceramic with the intermediate composition between relaxor and BF had nanodomain configuration with domain sizes less than 50 nm.  For the ceramics, the temperature dependences of dielectric constants were measured at various frequencies, and the T_max was determined.  As the results, the T_max increased with increasing BF content, while T_max decreased with increasing BT content.  Finally, their strain vs. electric-field behaviors were measured, and the relaxors showed typical electrostrictive behavior while BF-rich ceramics showed typical butterfly-like ferroelectric strain behavior.  For the ceramics with nanodomain configuration, the strain curve with hysteresis was clearly observed and the apparent d₃₃^* (=S_max/E_max) from the slope was over 850 pC/N.


CJ-2:IL10  Deposition of Epitaxial and Composite Ferroelectrics Directly on Silicon
C. DUBOURDIEU, Helmholtz Zentrum Berlin für Materialien und Energie, Berlin, Germany; L. MAZET, Institut des Nanotechnologies de Lyon, CNRS, ECL, Ecully, France; M.M. FRANK, E. CARTIER, J. BRULEY, V. NARAYANAN, IBM T.J. Watson Research Center, Yorktown Heights, NY, USA; S.M. YANG, Department of Physics, Sookmyung Women’s University, Seoul, South Korea; R.K. VASUDEVAN, S.V. KALININ, CNMS, Oak Ridge National Laboratory, Oak Ridge, TN, USA; C. MAGEN, LMA-INA, Universidad de Zaragoza, Zaragoza, Spain; S. SCHAMM-CHARDON, CEMES-CNRS, Université de Toulouse, Toulouse, France

Ferroelectrics on silicon have attracted attention for their potential integration in future nanoelectronics and integrated photonics for energy-efficient switches, modulators or tuning components. In this talk, we will discuss the growth by molecular beam epitaxy of ferroelectric epitaxial BaTiO3 thin films and composite materials on silicon substrates. In a first part, the route to precisely construct the epitaxial oxide/semiconductor interface will be presented. A detailed study of the crystalline tetragonal structure and composition at the nanoscale will be exposed based on HAADF-STEM imaging and EELS analyses. We will show that two distinct switchable polarization states are observed in ultrathin films deposited on silicon, down to 1.6 nm. As recently reported, the ferroelectric state is fundamentally inseparable from the electrochemical state of the surface for nanoscale systems. In a second part, we will present another material approach to growing a ferroelectric material on silicon. A composite ferroelectric consisting of amorphous and nanocrystalline BaTiO3 has been integrated into capacitors that exhibit ferroelectric behavior, together with a medium effective permittivity and low leakage currents. Implications for ferroelectric devices will be discussed.


CJ-2:L11  Accurate Determination of Material Coefficients from Electromechanical Resonances of Lead-free Ba1-xCaxTi0.9Zr0.1O3 (x=0.10-0.18) Mixed Oxide Ceramics
A. REYES¹, M.E. VILLAFUERTE-CASTREJÓN¹, A. GARCÍA², A.M. GONZALEZ³, L. PARDO², ¹Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, D.F. Mexico; ²Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Cantoblanco, Madrid, Spain; ³CEMDATIC, ETSIS, Campus Sur, Universidad Politécnica de Madrid, Madrid, Spain

Ceramics of the pseudo-binary Ba1-xCaxTi1-yZryO3 (x=0.10-0.18) solid-solution system attracts high interest as lead-free piezoelectrics to replace the commercial lead zirconate-titanate compositions. Homogeneous and dense ceramics with good performance at moderate synthesis and sintering temperatures were prepared by mixed oxides route [1]. As they are anisotropic materials, their properties must be determined in matriz form and accounting with all the material losses [2]. A number of methods of characterization from the analysis of the complex impedance curves have been developed [3]. The automatic iterative method (Spanish CSIC) was implemented for all the resonances and resonator shapes needed, namely: radial and thickness extensional resonances of thin disk, thickness poled; shear resonance of a plate, thickness poled; and length extensional resonance of a long bar resonator, length poled. 3-D modeling carried out by Finite Element Analysis (FEA), was used as quality criteria of this data[3]. Measurements of material were performed and results were discussed in terms of the loss mechanisms of the ceramic.
References: 1. Smart Materials and Structures 24, 065033 (2015); 2. Materials, 9(2), 72(18pp) (2016); 3.IEEE Trans. UFFC,. 58 (3), 646-657 (2011).


CJ-2:L12  Polarization in Ferroelectric Tungsten Bronzes
G.H. OLSEN, S. STUBMO AAMLID, S.M. SELBACH, T. GRANDE, Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim, Norway

Despite the importance of ferroelectric tetragonal tungsten-bronzes (TTB), the underlying mechanism(s) for the polarization in TTBs has not received much attention. We have performed first principles density functional theory (DFT) investigations of polarization and cation/vacancy ordering in PbNb2O6 (PN) and the SrxBa1-xNb2O6 (SBN) where Sr, Ba or a cation vacancy occupy the A1 and A2 crystallographic sites. The energy landscape of the cation configurations in SBN and PN was determined, and cation/cation vacancy order/disorder was addressed with particular attention to the thermal history and the effect on polarization. The ferroelectricity in SBN is driven by a conventional second-order Jahn-Teller mechanism caused by the d0 Nb5+ cations, and the size of Sr and Ba is demonstrated to possess a strong influence on the lattice distortions associated with polarization and octahedral tilting. In-plane polarization perpendicular to the polarization found in SBN is caused in PN by the lone pair cation Pb2+ located in the perovskite-like A1 sites. Finally, the influence of the thermal history on the ferroelectric phase transition in SBN will be presented and discussed in relation to cation order/disorder in SBN and other TTBs.


CJ-2:L13  Enhanced Piezoelectric Properties in PNZT-ZrO2 Composites at Low Frequencies
M. ACUAUTLA, S. DAMERIO, V. OCELIK, B. NOHEDA, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands

Piezoelectric materials attract a lot of interest due to their multifunctional character, which allows applications in different fields. Among these, Pb(Zrx-1Tix)O3 (PZT) has been widely used due to its high piezoelectric coefficients and its easy processing. Due to its polycrystalline nature, internal stresses generated during the sintering process are crucial to determine its properties. Nevertheless, the exact mechanisms behind this fact are still poorly understood. In this project, a highly responsive piezoelectric composite has been synthesized. It consists of Nb-doped-PZT ceramics, of a composition close to the so-called Morphotropic Phase Boundary (MPB), mixed with ZrO2 micro-particles. Although x-ray diffraction showed a single tetragonal perovskite phase, typically associated to lower electromechanical performance, high piezoelectric coefficients d33 ~ 1000 pm/V were observed at low frequencies up to 1 Hz. To understand the high piezoelectric properties of the material we have performed Electron Backscatter Diffraction (EBSD) to image the grain orientation distribution and investigate its effect on the performance. This material can be a promising candidate for low frequency applications such as energy harvesting.


CJ-2:L14  Structure-bandgap Relationship in Ba(M,Ti)O3 Ferroelectric Solid Solutions
H. VOLKOVA¹, P. GEMEINER¹, J. GUILLOT², D. LENOBLE², N. CHAUVIN³, F. KAROLAK¹, C. BOGICEVIC¹, B. DKHIL¹, I.C. INFANTE³, ¹Laboratoire SPMS, CentraleSupelec, CNRS-UMR8580, Universite Paris-Saclay, Gif-sur-Yvette, France; ²Luxembourg Institute of Science and Technology (LIST), Materials Research and Technology (MRT) Department, Belvaux, Luxembourg; ³Institut des Nanotechnologies de Lyon (INL), CNRS-UMR5270 ECL INSA UCBL CPE, Villeurbanne Cedex, France

Understanding photo-absorption properties in ferroelectric solid solutions and gaining control over them could enable creation of new, more efficient photovoltaic or photocatalytic devices. In our work we focus first on optical properties of Ba(SnxTi1-x)O3 solid solutions based on ferroelectric BaTiO3 and paraelectric BaSnO3, the latter chosen to increase electron mobility due to Sn 5s 5p orbitals in its conduction band. In addition to X-ray diffraction and dielectric measurements, we use a wide set of spectroscopy tools including UV-visible-NIR, Raman, X-ray Photoelectron and Photoluminescence spectroscopies to study this system. We found a significant increase of the direct band gap (>0.3 eV) for xSn = 0.8 compared to that of pure BaTiO3, with a weak absorption appearing below the band gap. We compared Ba(SnxTi1-x)O3 solid solutions to Ba(ZrxTi1-x)O3 ones having different electronic properties but similar structure, and showed in the latter ones similar absorption features with increased intensity. We propose to explain the band gap evolution and other absorption effects of these BaTiO3-based systems through a detailed analysis of the spectroscopy data and in view of the changes in the local chemistry and polar disorder existing in these solid solutions.


CJ-2:L15  Soft Mode and Microwave Dielectric Relaxation in Low-lead BT-PMN Ceramics
V. BOVTUN, D. NUZHNYY, M. KEMPA, T. OSTAPCHUK, J. PETZELT, S. KAMBA, Institute of Physics CAS, Prague, Czech Rep.; J. SUCHANICZ, K. KONIECZNY, Pedagogical University, Cracow, Poland

High-density perovskite 0.9BaTiO3-0.1PbMg1/3Nb2/3O3 (BT-0.1PMN) ceramics prepared by a two-step conventional solid phase sintering [1,2] were studied by the infrared reflectivity, THz and microwave spectroscopies (1 MHz – 20 THz). Microwave dielectric dispersion is essential below 500 K. In contrast to relaxor ferroelectric PMN [3], the temperature maximum of permittivity does not shift remarkably with increasing frequency up to 1 GHz and no PMN-like freezing is observed. THz and infrared spectra show presence of the split soft phonon mode, similar to that observed in the tetragonal BT [4] and PMN [3,5]. The main dielectric dispersion takes place in the 1 MHz – 1 THz range, similar to that in the BT ceramics, and can be described by three excitations: THz central mode attributed to the lower frequency component of the split soft mode and two Cole-Cole microwave relaxations tentatively attributed to the ferroelectric domain wall (or polar nanodomain wall) dynamics and piezoelectric resonances in grains.
[1] J. Suchanicz, et al. J. Eur. Ceram. Soc. 35, 1777 (2015); [2] J. Suchanicz, et al. Ferroelectrics 497, 100 (2016); [3] V. Bovtun, et al. J. Eur. Ceram. Soc. 26, 2867 (2006); [4] J. Hlinka, et al. Phys. Rev. Lett. 101, 167402 (2008); [5] V. Bovtun, et al. Ferroelectrics 298, 23


CJ-2:L18  Simultaneous Characterization of Charge and Structural Motion during Ferroelectric Polarization Reversal
C. KWAMEN¹, M. RÖSSLE², M. REINAARDT¹, W. LEITENBERGER², F. ZAMPONI², M. ALEXE³, M.BARGHEER^{1, 2}, ¹Helmholtz Zentrum Berlin, Berlin, Germany; ²Institute of Physics University of Potsdam, Germany; ³Department of Physics, University of Warwick, UK

The reversal of spontaneous polarization via the application of external stimuli is one of the basic properties of ferroelectric materials. The mechanisms associated with this phenomenon are still under investigations because it is not yet fully understood. Most often, the electrical signature of the switching on one side and the structural signature on the other have been investigated independently. We present here a simultaneous study of the electrical and structural responses of a lead-zirconate-titanate-based capacitor heterostructure during charging, discharging, and polarization reversal, using time-resolved X-ray diffraction. The switching is characterized by a transient disorder, concomitant with the ferroelectric current peak, evidenced by a decrease of the Bragg peak intensity, while the peak width suggests the domains dynamics during the process. Our investigations show how the incomplete screening of the depolarization charges affect the piezoelectric response, measured via the Bragg peak position. We examine the interplay between charge flow and atomic motion in real time during device operation.


CJ-2:L19  Processing and Properties of Lead-free BiFeO3-SrTiO3 Piezoceramics
M. MAKAROVIC^{1, 2}, A. BENCAN^{1, 2}, B. MALIC^{1, 2}, T. ROJAC^{1, 2}, ¹Electronic Ceramics Department, Jozef Stefan Institute, Ljubljana, Slovenia; ²Jozef Stefan International Postgraduate School, Ljubljana, Slovenia

BiFeO3 (BFO), has received a considerable attention for high-temperature piezoelectric applications due to its extremely high Curie temperature (Tc) of ~830 °C. In addition, many BFO-based solid solutions have been investigated due to the possibility to exhibit morphotropic phase boundary (MPB), where the piezoelectric properties are enhanced. Here, we studied the incorporation of SrTiO3 (ST) into solid solution with BFO in order to explore the possibility of exhibiting polar-to-non polar MPB, which is much less investigated compared to the conventional polar-to-polar MPBs (e.g., in Pb(Zr,Ti)O3 system) In order to prepare homogeneous and dense BFO-ST ceramics, we found that an alternative processing route, i.e., mechanochemical activation assisted synthesis, has to be applied. The whole (x)BFO-(1-x)ST compositional series (0.7≥x≥0.575) has been characterized from the viewpoint of structural, microstructural and functional properties. All compositions exhibited typical ferroelectric hysteresis loops with high remanent polarization, i.e., 30-50 μC/cm2. Moreover, we found a weak compositional enhancement of the piezoelectric d33 coefficient with a value of 69 pC/N, which is 75% higher than that determined for unmodified BFO (~40 pC/N).


CJ-2:IL22  Morphotropic Phase Boundaries in Polycrystalline Relaxor-ferroelectrics
M. OTONICAR, H. URSIC, B. JANCAR, A, BENCAN, B. MALIC, T. ROJAC, Jozef Stefan Institute, Ljubljana, Slovenia; G. ESTEVES, J.L. JONES, Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, USA

Relaxor-ferroelectric solid solutions, such as (1-x)Pb(Mg_1/3Nb_2/3)O₃–xPbTiO₃ (PMN-PT) and (Na_1-xK_x)_0.5Bi_0.5TiO₃ (NBT-KBT), exhibit enhanced electromechanical (EM) properties, making them attractive for actuating and sensing applications. The increased EM response is observed at the so-called morphotropic phase boundaries (MPBs), with the coexistence of two (or more) degenerate ferroelectric phases. Residual strains from elastically non-matching crystal lattices of the coexisting phases contribute to lattice distortions that are compensated by the formation of complex domain structures. At the MPBs, domains are often observed at the nanoscale, as short-range distortions deviating from an average long-range symmetry. Such ‘adaptive domain states’ promote domain-wall movement with applied external fields, enabling the release of field-induced strains, which further contributes to the EM response.
Multiscale description of the resulting complex structural arrangement at the MPBs after electric-field application remains poorly studied and understood. In this work, using complementary microscopy and diffraction techniques, we investigate the field-induced structural changes of polycrystalline relaxor-ferroelectric systems at their MPBs. Such a combined characterisation approach allowed us to reveal the crystal and domain structures of PMN-PT and NBT-KBT systems at different length scales. These results will be presented and the dominant composition-dependent field-induced effects will be discussed.


Session CJ-3 - Multiferroics and Magnetoelectric Ceramics

CJ-3:IL01  Charged Defects and Domain Walls in Polycrystalline BiFeO3
T. ROJAC, A. BENCAN, H. URSIC, B. JANCAR, M. MAKAROVIC, A. BRADESKO, B. MALIC, Jozef Stefan Institute, Ljubljana, Slovenia; G. DRAZIC, National Institute of Chemistry, Ljubljana, Slovenia; L. LIU, J.E. DANIELS, University of New South Wales, Sydney, NSW, Australia; D. DAMJANOVIC, Swiss Federal Institute of Technology, Lausanne, Switzerland

Due to their inherently small thicknesses of a few unit cells, domain walls (DWs) in ferroelectrics tend to interact with charged point defects, resulting in pinning effects. An important example is acceptor doping in Pb(Zr,Ti)O3 (PZT) where the compensating oxygen vacancies act as pinning sites for DWs, restricting their mobility and thus shaping the piezoelectric response of this material for, e.g., high-precision and high-power applications. Owing to the accepted view in PZT, it has been proposed that similar defects, namely Fe2+ and oxygen vacancies, are responsible for the electrical conductivity and DW pinning in multiferroic BiFeO3. We show in this contribution that, unlike Fe2+, it is Fe4+ ions (electron holes) that are responsible for the conductive behavior of BiFeO3 ceramics. Using atomic-resolution microscopy we further find that the Fe4+ defects, along with Bi vacancies, tend segregate at DWs, resulting in localized p-type conduction. Domain switching and piezoelectric response in combination with in-situ X-ray diffraction reveal that the p-type DW conductivity has a marking effect on the electromechanical properties of BiFeO3 through at least two microscopic mechanisms: i) coupling between domain wall conductivity and their dynamics and ii) Maxwell-Wagner effects.


CJ-3:IL02  Magnetoelectricity at the Antiperovskite/Perovskite Interface
DING-FU SHAO, T.R. PAUDEL, E.Y. TSYMBAL, Department of Physics and Astronomy, University of Nebraska, Lincoln, NE, USA

Complex oxide materials with the perovskite crystal structure (ABO3) are known for their interesting macroscopic physical properties. Much less explored are the antiperovskite compounds (AXM3) where the atomic positions of cations and anions are inverted creating unique properties different from perovskites. Due to the structural similarity, interfaces combining perovskite and antiperovskite compounds can be fabricated, forming a new playground for materials design. Here, based on density-functional calculations, we explore the magnetoelectric effect at the (001) interface between antiperovskite GaNMn3 and perovskite ATiO3 (A = Sr and Ba). Different from the Γ5g non-collinear magnetism of the bulk GaNMn3, strong magnetic moment enhancement and reorientation emerge at the GaNMn3/ATiO3 (001) interface, resulting in a sizable net magnetization pointing along the [110] direction. Moreover, we find that switching of the ferroelectric polarization of BaTiO3 drives the reversal of the net magnetization of GaNMn3. This phenomenon occurs due to the effect of ferroelectric polarization on the interfacial antiferromagnetic exchange coupling and paves a new for voltage controlled spintronics.


CJ-3:IL03  Magnetic Energy Harvesting by Magnetoelectric Composite Structure for Ubiquitous Self-powered Autonomous IoT Systems
DAE-YONG JEONG¹, GEON-TAE HWANG², WOON-HA YOON², SHASHANK PRIYA³, JUNGHO RYU², ¹Inha University, Incheon, South Korea; ²Korea Institute of Materials Science, South Korea; ³Pennsylvania State University, USA

The deployment of wireless sensor networks (WSNs) for the internet of things (IoT) and remote monitoring devices has made tremendous progress in the last few years. At the same time, energy harvesters are also being developed to satisfy the power requirement of WSNs and other low power consumption electronics. Among various resources for energy harvesting, the magnetic noise produced by power transmission infrastructures and associated mechanical vibrations are ubiquitous energy sources that could be converted into electricity by energy conversion materials or devices. Herein we have revealed an effective way to get an improved electric power density using a simple magneto-mechano-electric (MME) generator with magnetoelectric (ME) composite composed of piezoelectric single crystal and magnetostrictive shim. Since the piezoelectric phase in the MME generator also responds to mechanical vibration directly, an ME-based energy harvester can harness energy from both mechanical vibrations and magnetic fields simultaneously. The MME generator can be a ubiquitous power source for WSNs and low power electronic devices by harvesting energy from the tiny magnetic fields present as parasitic magnetic noise in an ambient environment.


CJ-3:IL04  Cool - Spark Plasma Sintering: Exploring Fragile Ferroic Ceramics and Beyonds
T. HERISSON DE BEAUVOIR, A. SANGREGORIO, I. CORNU, V. VILLEMOT, C. ELISSALDE, D. MICHAU, U-C. CHUNG-SEU, M. JOSSE, ICMCB-CNRS, Université de Bordeaux, UPR 9048 CNRS, Pessac, France

Spark Plasma Sintering (SPS) is a versatile sintering method, which allows for the processing of nanostructured, transparent ceramics (...) and can be used at low temperature for biomaterials or nuclear waste materials. We will present the use of SPS at low temperature (Cool-SPS, T≤600°C) for exploratory research on Fragile Ferroic Materials. Fragile materials have a limited thermodynamic stability, which forbids their sintering at high temperature (T>1000°C). However, the characterization and use of ferroelectrics (among ferroics) requires dense samples, preferably in ceramic form for exploratory researches. Through the elaboration of ceramics of candidate Fragile Ferroics, and the investigation of their ferroic properties, we established a firm proof of concept for Cool-SPS. We found an enhanced stability in SPS conditions, which expand Cool-SPS potentialities. We are now exploring known and new phases using Cool-SPS, in an exploratory approach, and collected unexpected results. We will attempt at illustrate how Cool-SPS, easily transferable, can open wide fields for exploratory researches, turn fragile materials into relevant alternatives as functional materials, help bridging gaps in materials research and represents an opportunity for sustainable functional materials.


CJ-3:IL05  Multiferroic (Nd,Fe)-doped PbTiO3 Ceramics with Coexistent Ferroelectricity and Magnetism at Room Temperature
F. CRACIUN, CNR Istituto dei Sistemi Complessi, Area della Ricerca di Roma-Tor Vergata, Rome, Italy

Since many decades, the field of multiferroics has been intensively investigated due to the high interest in materials which would allow the simultaneous control of multiple order parameters. The number of naturally occurring single-phase multiferroic materials with coexistent ferroelectricity and magnetism is very small. The general practice to obtain these materials was by doping magnetic materials in order to induce ferroelectric properties. This talk will attempt to give a diverse vision and route, which we contributed to develop in the last years, namely by doping a good ferroelectric, like PbTiO3, with magnetic elements. Co-doping of lead titanate with rare earth Nd3+ and transition (Fe3+, Mn4+) elements has been adopted as strategy. In particular we will dwell on the novel (Pb1-3x/2Ndx)(Ti0.98-yFeyMn0.02)O3 perovskite ceramics with room temperature ferroelectric polarization and ferromagnetism for higher amount of iron ions (y > 0.04). Our research into these materials combines XRD, XPS, Mössbauer spectroscopy and transmission electron microscopy analyses with dielectric, anelastic, ferroelectric and magnetic measurements to understand the properties dependence on processing parameters and doping elements concentration.


CJ-3:IL06  Real-space Imaging of the Spin Cycloid in BiFeO3 Thin Films
V. GARCIA, K. GARCIA, C. CARRETERO, A. BARTHELEMY, M. BIBES, S. FUSIL, Unite Mixte de Physique, CNRS, Thales, Univ. Paris Sud, Universite Paris-Saclay, Palaiseau, France; I. GROSS, W. AKHTAR, L.J. MARTINEZ, S. CHOUAIEB, V. JACQUES, Laboratoire Charles Coulomb, Universite de Montpellier and CNRS, Montpellier, France; J.-Y. CHAULEAU, M. VIRET, SPEC, CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France; P. APPEL, P. MALETINSKY, Department of Physics, University of Basel, Basel, Switzerland

While ferromagnets are at the heart of daily life applications, the large magnetization and energy costs for switching bring into question their suitability for low-power spintronics. Non-collinear antiferromagnetic systems do not suffer from this problem and often possess remarkable functionalities: non-collinear spin order may break space-inversion symmetry and allow electric-field control of magnetism, or produce emergent spin-orbit effects which enable efficient spin-charge interconversion. To harness these unique features, the equivalent nanoscale control and imaging capabilities, now routine for ferromagnets, must be developed for antiferromagnetic systems. Here, using a non-invasive scanning magnetometer based on a single nitrogen-vacancy (NV) defect in diamond, we demonstrate the first real-space visualization of non-collinear antiferromagnetic order in a magnetic thin film, at room temperature. We image the spin cycloid of a multiferroic BiFeO3 thin film and use the magnetoelectric coupling to manipulate the cycloid propagation direction with an electric field. These results highlight the unique potential of NV magnetometry for imaging complex antiferromagnetic order at the nanoscale.


CJ-3:L07  Ferroelectric Properties of Bi(Fe,Sc)O3 Ceramics Addressed by Piezoresponse Force Microscopy
V.V. SHVARTSMAN, Institute for Material Science, University of Duisburg-Essen, Essen, Germany; A.N. SALAK, Department of Materials and Ceramic Engineering/CICECO, University of Aveiro, Aveiro, Portugal; D.D. KHALYAVIN, ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, UK

Bismuth ferrite (BFO) has attracted an immense attention as a rare room-temperature single-phase multiferroics. The magnetic and ferroelectric structure of BFO can be tuned by cationic substitutions, however the single phase existence range is limited. It can be extended using the high-pressure synthesis method. In particular, this method was applied to sinter BiFe1-xScxO3 ceramics. The material appears in different polymorphs. The phase obtained by quenching under pressure is antipolar. However, thermal cycling at normal pressure irreversibly turns this phase into a polar one. Relatively large conductivity and complications to sinter dense ceramics make difficult study and even verification of macroscopic ferroelectric properties. These obstacles can be overcome implementing piezoresponse force microscopy (PFM). The post-annealed Bi(Fe0.5Sc0.5)O3 ceramics show a strong PFM signal and posses a well-developed domain pattern typical of a ferroelectric state. The quenched ceramics, however, demonstrate no piezoresponse that is in line with its antiferroelectric state. We found that this state can be transferred to a ferroelectric one by application of a strong enough electric field. The temporal and temperature stability of the induced states was studied.


Session CJ-4 - Semiconducting Ceramics

CJ-4:IL01  Gas Sensing with Semiconducting Metal Oxide Nanostructures
TETSUYA KIDA, Division of Materials Science, Faculty of Advanced Science and Technology, Kumamoto University, Kumamoto, Japan

It is well known that the gas sensitivity of metal oxides is dependent on their morphology such as particle size, pore size, thickness, and surface states. We have been studying the effects of the particle- and pore-sizes of sensing films on gas sensitivity. In order to quantitatively analyze such effects, we fabricate SnO2-based films with different morphologies, particle-, and pore-sizes and study the sensor responses to three different gases, including H2, CO, and H2S with the different Knudsen diffusion coefficients. To fabricate SnO2-based films with different particle- and pore-sizes, we developed a seed-mediated growth approach using 4 nm SnO2 nanocrystals as seed crystals. The developed method successfully produced nanocrystals ranging from 9.5 to 17 nm in average diameter under hydrothermal conditions at 250°C. Using the SnO2 nanocrystals, pore size of gas sensing films was successfully controlled from 2.8 to 5.5 nm in radius. We found that controlling the pore size of sensing films is very effective to produce highly sensitive films toward larger weight gas molecules. In the presentation, our recent approaches to develop highly-sensitive sensors using oxide nanocrystals will also be given.


CJ-4:IL02  Mechanically Tuned Conductivity in Piezoelectric Semiconductors
N. NOVAK^{1, 2}, T. FRÖMLING¹, J. RÖDEL¹, ¹Institute of Materials Science, Technische Universität Darmstadt, Darmstadt, Germany; ²Institute Jožef Stefan, Ljubljana, Slovenia

Utilizing mechanical strain to modulate electronic transport processes across electrostatic potential barriers is an encouraging concept for the design of multifunctional electronic devices. Therefore, semiconductors belonging to the wurtzite family recently attained great interest. This fundamental mechanism has led to novel device applications and opened a new field called “piezotronics”. This presentation describes the interplay between stress induced piezoelectric charges and the electronic band structure at semiconductor interfaces. In our work three different piezotronic systems were investigated: metal-ZnO single crystal, polycrystalline varistor ceramics, and bicrystal. The experimentally evaluated reduction of the Schottky barrier height reveals a moderate change of about 9meV at 70 MPa and is contrasted with theoretical calculations based on the imperfect screening model if a thickness of the interface layer. Polycrystalline varistors exhibit huge changes of resistivity upon applied electrical and mechanical fields and therefore offer descriptive model systems to study the piezotronic effect. Furthermore we demonstrate the potential of doped ZnO bicrystals to gain insight into the physical mechanisms of the piezotronic modulation of individual double Schottky barrier.


CJ-4:IL03  Highly Sensitive and Selective Hydrogen Sensing Utilizing an Interface between Noble Metal and Anodized Titania
TAKEO HYODO, Y. SHIMIZU, Graduate School of Engineering, Nagasaki University, Nagasaki, Japan

Most of H2 sensors cannot operate under oxygen-free atmosphere, because H2 is essential to react with oxygen adsorbates on the sensor surface. On the other hand, diode-type H2 sensors using noble-metal (N) sensing electrodes and an anodized titania film (N/TiO2 sensors), which have excellent gas-sensitive interface between N and TiO2, show large H2 responses even under oxygen-free atmosphere. Use of pristine Pd or Pd-Pt as the sensing-electrode material especially shows quite large H2 responses, but these responses largely depend on the oxygen concentration in target gas. A Pt/TiO2 sensor shows lower H2 responses than the Pd/TiO2 and Pd-Pt/TiO2 sensors, but the surface modification of the Pt-sensing electrode with a suitable amount of Au drastically enhances the H2 response in air. For example, the response of the Pt/TiO2 sensor to 8000 ppm H2 in air is three orders of magnitude smaller than that in N2, but the optimal Au modification drastically enhances the H2 responses and the response of the Au-modified Pt/TiO2 sensor in air is comparable to that in N2. In addition, the Au-modified Pt/TiO2 sensor shows excellent H2 selectivity against hydrocarbons such as propane. We will discuss their detailed gas-sensing properties and mechanism in our presentation.


CJ-4:IL04  Nanostructural Metal Oxide and Chalcogenide Semiconductor Gas Sensors
CHONG-YUN KANG, Korea Institute of Science and Technology, Seoul, South Korea

In the presentation, we show our research efforts to fabricate well-ordered metal-oxide nanostructures using physical vapor deposition methods for high performance gas sensors. Without any nano-template and chemical additives, the nanocolumnar metal oxides (NMO) thin films were fabricated by glancing angle deposition process using the e-beam evaporator. To optimize the morphologies and electrical properties of NMO thin films, we tried to control the various deposition conditions such as rate, angle, and pre-surface treatment. Highly-ordered NMO sensors have obtained an excellent response to minute amounts of volatile gases. Moreover, optimizing the electrical properties of NMO sensors to fit on the type of gases, the selectivity to target gases was also obtained. Consequently, highly sensitive and selective sensing properties of our NMO sensors suggest the great potential for use in various practical applications with high reproducibility, simplicity in fabrication, and high-yield mass production. Based on the results of the NMO sensors, we also successfully made the 2 x 2 and 2 x 4 array gas sensor combining the various NMO and novel metal catalysts with MEMS fabrication process.


CJ-4:IL05  MEMS Gas Sensors Based on Metal Oxide Nano Particles
KENGO SHIMANOE¹, W. HARANO², T. OHYAMA², K. SUEMATSU¹, K. WATANABE¹, M. NISHIBORI¹, ¹Faculty of Engineering Sciences, Kyushu University, Fukuoka, Japan; ²Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka, Japan

For materials design of the semiconductor gas sensors, my group reported three important key factors, receptor function, transducer function and utility factor [1]. Such material designs are useful for devices in operating constant-heating. On the other hand, however, MEMS-type gas sensors in operating pulse-heating, which is one of the candidates for IoT sensors, need additional designs. So, we report new idea of materials and operation for MEMS-type gas sensors. SnO2 is typical sensor material, but the sensor in operating pulse-heating gives interesting sensing properties different from that of constant-heating. By pulse-heating in inflammable gas, the gas response was high at first 100ms and gradually reached to value obtained by constant-heating. The magnitude of first response was dependent on the concentration of inflammable gas (toluene). Furthermore, special additives to the sensing film gave enhancement in gas response [2].
References: [1] N. Yamazoe, K. Shimanoe (2007), Overview of gas sensor technology, In D. K. Aswal and S. K. Gupta (Eds.) Science and Technology of Chemiresistor Gas Sensors, Nova Science Publishers, Inc., pp. 1-31. [2] K. Shimanoe, N. Ma, T. Oyama, M. Nishibori, K. Watanabe, ECS Trans., 75 (16), 31-37 (2016).


CJ-4:IL06  Sol-gel Coatings for Sensing Devices and Electronics Applications
O.A. SHILOVA, Institute of Silicate Chemistry, Russian Academy of Sciences, Saint-Petersburg, Russia

Sol-gel silica coatings doped by various chemical elements are successfully used for electronic applications. They can be used in several technological operations for obtaining semiconductor gas sensors. They carry out the functions of diffusion sources of dopants (Sb, Gd) into the gas-sensitive SnO_2-x layer and composite catalyst layers (SiO₂/Pt, Pd; SiO₂/Mn) deposited over the SnO_2-x layer. As a result, the sensitivity to reducing gases increases in 2-3 times, the ability to selectively determine the gas concentration in mixtures and the sensitivity to CO₂ acceptable for practical use are achieved. This effect is associated with a special structure of sol-gel coatings, which is a silica matrix with uniformly distributed dopant nanoparticles. The thickness of coatings can be varied within from 30 to 300 nm. Moreover, the sol-gel coating can be deposited on a powder surface. For example, the surface of a BaTiO₃ powder is modified by CoFe₂O₄ or SiO₂/CoFe₂O₄ layers to obtain multiferroics with a ‘core-shell’ structure. These powders are used as fillers for the manufacture of film capacitors with improved characteristics. BaTiO₃//TiO₂ composite powders are used in the manufacture of electroluminescent light sources to improve their brightness.
The author thanks the Russian Science Foundation for financial support (Project No. 17-13-01382).


Session CJ-5 - Fast Ion-conducting Ceramics

CJ-5:IL02  Material Design for an Electrode of an Oxygen Pump Based on Oxide-ion Conductors
KEN WATANABE, Kyushu University, Kasuga, Japan

Heterojunction between an ion conductor and an electrode is very important, when we design the electrochemical devices like solid state fuel cell, solid electrolyte-type gas sensor, all solid state Li-ion battery, oxygen pump and so on. In other words, in order to achieve high electrochemical performance, the charged-carrier (O2-, Li+, H+) should be transported well between the electrolyte and electrode. For instance, in the case of the oxygen pump with an oxide ion conductor, mixed oxide-ionic and electronic conductor like perovskite-typed oxide are widely used as the electrode materials, because of their high oxygen reduction/evolution activity and high oxygen diffusivity. However, from the view point of formation of heterojunction with low interfacial resistance, we should pay attention to not only to mixed conductivity but also reactivity with solid electrolyte. In this talk, I’ll present how we designed the mixed conductive electrode for oxygen pump.


CJ-5:IL03  Electrochemical Membranes in Energy Conversion
F. MARQUES, Dept. of Materials and Ceramic Eng./CICECO, University of Aveiro, Aveiro, Portugal

Ceria-based composites, including alkaline carbonates, are promising electrolytes for fuel cells and CO2 separation membranes. Multiple ionic charge carriers and a conductivity exceeding 0.1 S/cm at 500 °C, are of great interest for such applications. In this work composites with a wide range of microstructural characteristics are scrutinized with respect to their performance. While the high temperature conductivity is fully dominated by the molten carbonates, distinct oxide backbone characteristics could be easily perceived from low temperature impedance spectroscopy data and SEM. This information was used to determine the conductivity of both phases and screen the ideal microstructural characteristics for fuel cells or CO2 separation membranes, applications imposing distinct figures of merit.
Acknowledgments: Work performed with funding from Projects CO2Zero (016654, PTDC/CTM-CER/6732/2014), MOCO3 (M-ERA-NET2/0009/2016) and CICECO‐Aveiro Institute of Materials (FCT UID/CTM/50011/ 2013), financed by Portuguese funds (FCT/MEC) and FEDER under the PT2020 Partnership Agreement.


CJ-5:L05  Development and Electrical Discharge Machining of Electrical Conductive Pressure-less Sintered TiC/Al2O3 Composites
S. CONZE, S. HILDEBRANDT, T. HUTZLER, L.-M. BERGER, A. MICHAELIS, Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Dresden, Germany

TiC/Al2O3 composites are extensively investigated the last 30 years. In various fields their mechanical, electrical or thermal properties have been exploited. Especially, the increase of hardness and fracture toughness were intensively discussed in the literature. A main application area is tool manufacturing in particular for cutting ceramics/indexable inserts. Accordingly, in this work we systematically examine the microstructure, density and mechanical properties of pressure-less-sintered 30 wt. % TiC/Al2O3 composites depend on type and amount of sintering additives. Thereby, improved composite properties can be expected by specifically tailoring the microstructure to sub-micro via additives for inhibition of grain growth and support of the solid phase sintering process. A subsequent electrical discharge machining of sub-micro TiC/Al2O3 ceramic can be formed smooth surfaces and smaller structures compared to conventional TiC/Al2O3 composites.


CJ-5:L07  Properties of Shape-controlled Gadolinia-doped Ceria Nanoparticles
M.F.S. MACHADO, L.P.R. MORAES, L.N. RODRIGUES, T. RODRIGUES, F. CORAL FONSECA, Nuclear and Energy Research Institute - IPEN, Sao Paulo, SP, Brazil

A hydrothermal method was developed for the synthesis of gadolinia-doped (10 mol%) ceria nanoparticles with controlled morphology. By controlling the synthesis parameters it is possible to obtain homogenous single-phase nanocubes or nanorods with narrow size distribution, as inferred by X-rays diffraction and scanning electron microscopy. Such nanostructures were investigated for different applications, such as oxygen ion conductors and catalysts supports. For catalysis, the high surface area nanorods were impregnated with Ni and tested for ethanol steam reforming. High selectivity for hydrogen production with good stability evidenced the enhanced performance of the nanorods support as compared to commercial catalysts. Sintering of ceria compacts were studied by dilatometry showing important differences in the retraction profile depending on the initial powder morphology. Different sintering additives were added aiming at both enhanced and inhibited sintering activity. It was possible to obtain ceria nanorod powders with high sintering activity, achieving apparent densities close to the theoretical density at T~1200C. On the other hand, applications relying on porous materials are favored in nanocubes that showed almost no retraction and remaining highly porous up to 1400C.


CJ-5:IL08  Interfacial Contributions to Mixed Ionic and Electronic Conducting (MIEC) Materials in Solid Oxide Fuel Cells, Membrane Separations and Solid-State Battery Applications
K.S. BRINKMAN,  Materials Science and Engineering, Clemson University, Clemson, SC, USA

The emergent properties arising from the interactions of phases including interfacial contributions (surfaces) and phase evolution at the mesoscale present new opportunities, as well as challenges, for materials performance and functionality. This presentation will highlight interfacial contributions to system level performance in mixed ionic and electronic conducting (MIEC) materials in solid oxide fuel cells, membranes and solid state batteries. Mixed ionic-electronic conductors are widely used in devices for energy conversion and storage. Compositional tailoring through doping strategies, fabrication of composite systems that preferentially form “emergent” phases to enhance the grain boundary ionic conductivity, as well as addition of surface coatings have been used to improve performance. Studies at the interface between disciplines provide unique case studies for understanding materials behavior; knowledge in application areas focused on immobilization of alkali elements such as cesium in nuclear waste can be used to develop strategies to enhance mobility for Li, and Na in battery applications.


CJ-5:IL09  Effects of Remnant Metastability in Nanoscaled Oxygen Ionic Conductors
V. ESPOSITO, Technical University of Denmark, Department of Energy Conversion and Storage, Roskilde, Denmark

Since the formulation of materials thermodynamics in 1878 by J.W. Gibbs, the paradigm in materials science has been firmly founded on thermodynamically stable materials, i.e. phases with the lowest Gibbs energy at their thermodynamic conditions. Such phases are persistent, reliable, easy to predict and their properties are usually those expected from their chemistry. In nature, however, complexity rules and so in modern technology the growing demands of functional materials far beyond their limitations. Metastable materials are kinetically trapped unstable that possess an energetic “excitement” above their thermodynamical stability. Such a special status leads to properties as well as to energetic mechanisms, cycles and transformations that often translate into advanced functionalities applicable in mechanics, electronics, catalysis, energy, etc. In this paper, we show how to activate metastable compounds with new properties, not achievable by conventional process of Gibbs ‘phases. Particularly, referring to the concept of “remnant metastability”, we show how to activate metastable oxygen ion conductors via controlled thermochemical procedures on nanoscaled materials confined at the interface. The resulting nanoscaled materials open to new scenarios in energy applications.


CJ-5:IL10  Design, Synthesis and Electrochemical Characterizations of Electrode Materials for Rechargeable Li-sulfur Batteriess
DO KYUNG KIM, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea

Among the various rechargeable energy storage devices, lithium-sulfur (Li-S) battery has been widely recognized as one of the major rechargeable energy storage systems due to its high theoretical specific capacity (1675 mAhg-1) and energy density (2600 Whkg-1). Despite the several considerable merits of Li-S, the commercialization of Li-S technology has not been fully realized due to the low electrical conductivity of sulfur, high solubility of polysulfide intermediates, and large volume expansion. The related side reaction caused by the shuttle effect causing poor materials utilization and loss of active material from the electrode. Our research focus includes the rational design and development of low cost, high efficient materials that can facilitate commercialization of Li-S and Li-polysulfide batteries. The present talk covers the recently demonstrated encapsulated monoclinic sulphur, cross-linked polyaniline-coated graphene oxide-sulfur electrodes, glass fiber-based polysulfide electrode, and synergistic effect of polysulfide additive and MnO2 hollow spheres for stable cycling performance of Li-S/polysulfide batteries. The effective suppression of polysulfide dissolution by uniformly transfer-printed conducting polymer will also be outlined in detail.