Name of the laboratory: IM2NP (UMR 7334) CNRS, https://www.im2np.fr
Thesis advisor: Dr. Thomas W. Cornelius, Dr. Michaël Texier
Email and address:
email@example.com, Tel.: +33 (0)4 13 94 53 72
firstname.lastname@example.org, Tel.: +33 (0)4 91 28 80 98
IM2NP, Case 262, Av. Escadrille Normandie-Niemen, F-13397 Marseille
Subject’s title: Domain dynamics in ferroelectric thin films studied by time-resolved X-ray diffraction
The MNO group of IM2NP at Aix-Marseille Université offers a PhD thesis focusing on the piezoelectric properties of ferroelectric thin films. The most widely used piezoelectric material since the 1960s is ferroelectric lead zirconate titanate [Pb(Zr1-xTix)O3]. Its success is associated with the morphotropic phase boundary between rhombohedral (Zr-rich) and tetragonal (Ti-rich) compositions, where dielectric and piezoelectric properties exhibit extremes. Besides the intrinsic piezoelectric effect, extrinsic mechanisms related to the presence of domains contribute to the piezoelectric effect in ferroelectrics. In polycrystalline materials, neighboring grains interact elastically, piezoelectrically, and electrically. The total macroscopic response of a piezoelectric therefore emerges from complex interactions of intrinsic and extrinsic mechanisms.
Considering the toxicity of the heavy metal Pb, legislation of the European Union restricts the use of lead in piezoelectric devices unless exempted under specific conditions. Promising lead-free candidates are bismuth layer structured ferroelectrics like bismuth titanate (Bi4Ti3O12) and perovskites such as barium titanate (BaTiO3), bismuth sodium titanate ((Bi1/2Na1/2)TiO3), and sodium potassium niobate (K0.5Na0.5NbO3). The families of sodium potassium niobate, bismuth sodium titanate have the advantages of low dielectric constants, high coupling coefficient, and higher mechanical strength, in general, than lead containing ceramics that make them suitable for high frequency transducers. Apart from being nontoxic, their lower acoustic impedance makes them suitable for medical imaging. Bismuth layer structured ferroelectrics ceramics, on the other hand, seem to be suitable candidates as piezoelectric sensors for high temperature. In order to better model the properties and improve the understanding of (lead-free) ferroelectric piezoelectric thin films, it is mandatory to understand the extrinsic mechanisms that are related to domains, domain walls, and their interaction in between each other but also with defects present in the material.
Within this thesis, the successful candidate will study the piezoelectric behavior and domain kinetics in ferroelectric thin films using unique experimental techniques: (i) time-resolved X-ray diffraction during electrical actuation at 3rd generation synchrotrons (ESRF, SOLEIL, …) [1-2] and (ii) in situ electrical actuation during TEM imaging using a novel TEM sample holder in an aberration corrected FEI TITAN . The experiments are accompanied by finite element method simulations.
Competences: The candidate should hold a Master degree in physics, materials science, or another closely related field. He/she should have a profound knowledge in solid state physics and a vivid interest in working experimentally. Experience in programming languages is appreciable.
Applications should include a CV, two letters of recommendation, a statement of research interests, and the last transcript of grades.
Application deadline: March 20th, 2021
Funding: ministerial bursary of doctoral school 352
Keywords: piezoelectricity, ferroelectric, domains, in situ synchrotron X-ray diffraction, in situ TEM analyses
 T.W Cornelius, C. Mocuta, S. Escoubas, A. Merabet, M. Texier, E.C. Lima, E.B. Araùjo, A.L. Kholkin, O. Thomas, Piezoelectric response and electrical properties of PZT thin films: The role of imprint and composition, J. Appl. Phys. 122 (2017) 164104
 T.W. Cornelius, C. Moctua, S. Escoubas, L.R.M. Lima, E.B. Araújo, A.L. Kholkin, O. Thomas, Piezoelectric properties of Pb1-xLax(Zr0.52Ti0.48)O3 thin films studied by in situ X-ray diffraction, Materials 13 (2020) 3338
 M. Texier, J. Thibault-Penisson, Optimum correction conditions for aberration-corrected HRTEM SiC dumbbells chemical imaging, Micron, 43 (2011) 516Mehr
|Titel||PhD - Domain dynamics in ferroelectric thin films studied by time-resolved X-ray diffraction|
|Employer||Institut Matériaux Microélectronique Nanosciences de Provence (IM2NP)|
|Job location||Faculté des Sciences de Saint Jérôme - Case 142, Avenue Escadrille Normandie Niemen, F-13397 Marseille Cedex 20, 13397 Marseille|
|Veröffentlicht||Januar 21, 2021|
|Bewerbungsschluss||März 20, 2021|
|Jobart||PhD/ Doktorand/in  |
|Fachbereiche||Experimentalphysik,   Materialphysik,   Solid-state Physics,   Elektrotechnik,   Angewandte Physik,   Elektronik,   Bildverarbeitung  |