Antiferroelectrics are dielectric materials composed of an antipolar array of dipoles, which display no macroscopic polarisation. They can be switched to a polar ferroelectric phase by application of an electric field: this field-induced phase transition is called switching, which induces a so-called “double hysteresis loop” in its polarisation vslectric field curve. The shape of this double hysteresis loop allows for efficient storage of electrical energy and a very fast discharge, useful for high-power applications [1, 2].

In particular, the development of sustainable alternatives to traditional lead-based ferroelectrics and antiferroelectrics is a crucial step towards creating environmentally friendly energy storage solutions.

On a more fundamental side, layering antiferroelectric and ferroelectric materials could also induce extremely rich topological physics, such as ferroelectric skyrmions [3, 4], which could be further energy storage properties of multilayers [5, 6, 7], but also in other applications (e.g. extremely low-power computing). Investigating how such antiferro/ferroelectric multilayers behave under an electric field (including the underlying mechanisms of electric field-induced phase transitions) is also a very important topic in the ferroic community.

This PhD research project will focus on the synthesis and characterization of novel materials that can replace toxic lead-based compounds in energy storage devices, such as supercapacitors.

Materials of interest are lead-free inorganic perovskites such as NaNbO3, AgNbO3, BiFeO3, (Nb0.5Bi0.5)TiO3, which are (anti)ferroelectric materials.

During this PhD, the candidate will:

• Design and synthesise eco-friendly alternatives to standard lead-based (anti)ferroelectrics in the shape of multilayers
• Analyse in-depth the electrical, structural, and chemical properties of these multilayers
• Investigate the suitability of these materials for energy storage devices, particularly supercapacitors, and optimise their performance for enhanced energy density and power density.
• Study in-situ (anti)ferroelectric multilayers under the influence of electric fields and temperature change to elucidate their underlying mechanisms of their phase transitions

The first step of this PhD project is to synthesise lead-free antiferroelectric multilayers [7] by chemical solution deposition (CSD) and pulsed laser deposition (PLD) and to optimise their density of storable energy. The second step of this project is to shed light on the electric-field induced switching mechanisms of these multilayers to further improve our knowledge of these materials.

Main experimental techniques:

Chemical solution deposition (CSD) and pulsed laser deposition (PLD) for depositing multilayer thin film materials; x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) for (micro)structural characterisation; x-ray photoelectron spectroscopy (XPS), electron diffraction spectroscopy (EDS) for chemical analysis; electrical measurements (polarisation, capacitance, permittivity).

Bibliography:

[1] B. Xu, J. Íñiguez, and L. Bellaiche, ‘Designing lead-free antiferroelectrics for energy storage’, Nat Commun, vol. 8 (2017)

[2] Z. Liu et al., ‘Antiferroelectrics for Energy Storage Applications: a Review’, Adv Mater Technol, vol. 3, no. 9, p. 1800111 (2018)

[3] Yadav, A. K. et al., Observation of polar vortices in oxide superlattices. Nature 530, 198–201 (2016).

[4] Das, S. et al., Observation of room-temperature polar skyrmions. Nature 568, 368–372 (2019).

[5] H. Aramberri, N. S. Fedorova, and J. Iniguez, ‘Ferroelectric/paraelectric superlattices for energy storage’, Sci Adv, vol. 8, no. 31, p. 4880 (2022)

[6] T. Zhang et al., ‘Superior Energy Storage Performance in Antiferroelectric Epitaxial Thin Films via Structural Heterogeneity and Orientation Control’, Adv Funct Mater, vol. 34, no. 4, p. 2311160 (2024)

[7] Y. Zhang et al., ‘High Energy Storage Performance of PZO/PTO Multilayers via Interface Engineering’, ACS Appl Mater Interfaces, vol. 15, no. 5, pp. 7157–7164 (2023)

Funding category: Contrat doctoral

Ecole Doctorale INTERFACES Université Paris-Saclay

PHD title: Doctorat de Physique

PHD Country: France