Speakers: Rüdiger-A. Eichel (Universität Freiburg)
Place: Na Slovance, přednáškový sál v přízemí
Presented in English
Organisers:
Department of Dielectrics
Piezoelectric materials offer a wider range of applications ranging from actuators over sensors to novel concepts for piezoelectric energy harvesting involving transducers. In that respect, the pseudo-binary solid-solution system Pb[Zr1-xTix]O3 (PZT) is the material-of-choice, where the desired materials properties for a given device can be tailored by controlling the defect structure in terms of aliovalent doping with transition-metal and rare-earth ions. By using multi-frequency electron paramagnetic resonance (EPR) spectroscopy, local information at the (paramagnetic) dopant sites can be gathered, including information about the dopant site with respect to domain walls or grain boundaries. Recent results allow to monitor the formation of defect complexes between acceptor-type dopants and charge-compensating oxygen vacancies. Furthermore, the defect chemistry emerges from the EPR results and is described for acceptor-doped PZT, as well as for ‘lead-free’ alternatives, such as [Ka0.5Na0.5]NbO3 (KNN) and [Bi0.5Na0.5]TiO3 (BNT). Finally, dynamic properties that include the switching upon external poling and the degradation as function of cyclic loading (electrical fatigue), as well as constant thermodynamic boundary conditions (aging) are studied.
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