June 29 – July 3, 2020, Moscow, Russia
Institute of Materials, Swiss Federal Institute of Technology in Lausanne, Switzerland
Dragan Damjanovic received diploma in physics (BSc) from the Faculty of Natural Sciences and Mathematics at the University of Sarajevo (1980) and a PhD in Ceramics Science from the Pennsylvania State University (PSU) in 1987. He carried out postdoctoral work at the PSU (1988-1991) and moved to EPFL in 1991. He became professor titulaire in 2009.
He has published over 240 scientific papers (H=65, Scopus, April 2019 ) and has received several awards including IEEE Robert E. Newnham Ferroelectrics Award, International Award of the Japanese Conference on Ferroelectric Materials and Their Applications and Ferroelectrics Recognition Award of the IEEE Ultrasonics, Ferroelectrics and Frequency Control Society (UFFC-S). He was Distinguished Lecturer for the UFFC-S in 2010/11, and is a Fellow of IEEE and Fellow of the American Ceramics Society. He served as the Vice President for Ferroelectrics of the IEEE UFFC-S in the period 2015-2017.
In piezoelectric and ferroelectric materials elastic and dielectric responses are coupled. This elasto-electric coupling extends to relaxation mechanisms, the most intriguing being emergence of relaxation in piezoelectric properties. The piezoelectric relaxation may exhibit behavior that is not possible in purely dielectric and elastic counterparts, such as clockwise hysteresis between pressure and charge or electric field and strain. Evidence of such behavior in perovskite oxides, BiFeO3 and modified-PbTiO3 will be discussed.
The large dielectric relaxation in complex disordered perovskites, such as Pb(Mg1/3Nb2/3)O3, is thought to be due to presence of dynamic polar nano regions that evolve with temperature and the temperature dependent, broad distribution of relaxation times. Using dynamic mechanical analysis we have shown recently that polar nano regions in relaxor materials are also elastically active, exhibiting the same type of elastic relaxation as has been reported for the dielectric properties. Implication of this result on interpretation of origins of relaxor behavior in this canonical relaxor and on large piezoelectric properties in this class of materials will be discussed.
Displacement of non-180° domain walls in ferroelectric phases and polar entities in paraelectric phases of ferroelectrics contribute or even dominate dielectric and elastic properties. Often, ensuing anelastic relaxation reveals itself much more clearly than dielectric relaxation and is essential for interpreting some delicate emergent phenomena, such as dynamics of precursors of the ferroelectric phase. Finally, light-induced anelastic relaxation in nominally centrosymmetric methylammonium lead halides will be presented.
Laboratory MATEIS, an Engineering School INSA-Lyon, France
His research concerns the mechanical response of amorphous materials, especially bulk metallic glasses. Zr-, Ti-, La-based materials are for instance investigated. One of the main topics is the influence of thermo-mechanical treatments on these mechanical properties, both at room temperature or at elevated temperature. Mechanical relaxations are investigated in detail in order to understand the influence of chemical composition and atomic arrangement on the atomic mobility in these disordered materials. Prof. Jean-Marc Pelletier has published more than 170 SCI journal papers and presented more than 100 contributions in International Conferences, with the citation of more than 2000 and H-index of 26 (April 2019). Before studying the mechanical response of amorphous materials he was interested in the phase transformation, especially precipitation and ordering, high power laser engineering and various topics. He developed international collaboration, especially with groups in China (Prof. W.H. Wang in Beijing) and in Japan (Prof. A. Inoue and Prof. H. Kato, in Sendai).
J. M. PELLETIER1, J.C. QIAO2
1MATEIS, INSA-Lyon, Université de Lyon, France
2NPWU, Xi’an, China.
Amorphous materials exhibit a specific mechanical behavior due to the absence of long range order. Therefore, the concepts of point defects, dislocations or grain boundaries are no longer available. Amorphous materials may concern either polymers, oxide glasses or amorphous metals and thus either covalent, Van des Waals, ionic or metallic bonding are involved. Atomic mobility in these materials can be investigated using mechanical spectroscopy. Various relaxations can be observed either as a function of frequency or temperature. This point will be addressed in the presentation. A more detailed insight will be done in bulk metallic glasses. These materials are the topic of many researches because they possess excellent mechanical properties, in particular their yield strength. We will briefly review the main results obtained in various bulk metallic glasses. A physical analysis of the mechanical response will be presented. Similarities and differences with the other amorphous materials will be discussed.
Departament de Física, Universitat de les Illes Balears, Palma de Mallorca, Spain
Sergey Kustov graduated from Electrophysics faculty of Electrotechnical Insitute in 1977, and got PhD degree in Physics and Mathematics from A.F. Ioffe Physico- Technical Institute in 1989, USSR Academy of Sciences, Leningrad.
1981-2004: A.F. Ioffe Physico-Technical Institute, USSR Academy of Sciences, Leningrad
1994-2004: Research fellow and senior fellow at Catholic University of Leuven, Leuven; Invited professor, Swiss Federal University of Technology, Lausanne; Visiting professor, University of Balearic Islands, Palma de Mallorca.
2004-2019 Ramón y Cajal fellow, profesor contratado doctor, associate professor, department of Physics, University of Balearic Islands, Palma de Mallorca, Spain.
Magnetomechanical damping (MMD) in ferromagnets includes three canonical contributions - microeddy and macroeddy linear non-thermally activated relaxations and non-linear hysteretic damping. The first and the last of these three categories are due to the oscillatory motion of magnetic domain walls (DW), whereas the macroeddy component is derived from the net macroscopic magnetization of a sample. The concepts of these MMD components date back to 1930-1950-1960 and no fundamentally new observations have been done since then.
During the last few years, using resonant technique, operating around 105 Hz - the frequency range of the maximum sensitivity to DW related magnetomechanical effects - two new MMD categories have been uncovered:
The number of MMD categories thus increases from three to five. The disclosed MMD components offer new interpretations for a number of physical phenomena still being intensively discussed, like spin and re-entrant spin glass transitions, formation of tweed in ferromagnetic materials, etc.