DQMP Forum - Unusual Polarization Textures at Crossings of Ferroelastic Twin Domains in Pb(Zr0.2Ti0.8)O3 Thin Films - Enhanced Electrochemical Stability of Na Solid Electrolytes: Amorphous NaCB11H12 by High-energy Ball Milling

19.01.2021 13:00 – 14:00

Unusual Polarization Textures at Crossings of Ferroelastic Twin Domains in Pb(Zr0.2Ti0.8)O3 Thin Films
Philippe Tückmantel(group of Prof. Paruch)

Ferroelectric materials have been shown to exhibit a wide variety of domain configurations such as flux-closure and bubble domains, polar vortices and ferroelectric skyrmions. These configurations typically arise from an interplay between the strain applied by the substrate and electrostatic boundary conditions. Large strains and strain gradients, such as those found around ferroelastic twin domains can help stabilize polarization rotations and provide a promising avenue for locally emerging functional properties. Here, we report on rotational polarization textures observed at the crossings of twin domains, using piezoresponse force microscopy and second harmonic generation in Pb(Zr0.2Ti0.8)O3 thin films grown by pulsed laser deposition on DyScO3 substrates. We show that peculiar polarization structures can be created reproducibly at the crossings using either mechanical pressure or electric fields applied via a biased scanning probe microscopy tip.


Enhanced Electrochemical Stability of Na Solid Electrolytes: Amorphous NaCB11H12 by High-energy Ball Milling
Fabrizio Murgia (group of prof. Cerny)

Seeking better performing solid-state electrolytes for post-Li batteries, complex hydrides have recently drawn attention thanks to their chemical robustness, superior oxidative stability and low
density.1,2 Such materials display order-disorder phase transitions that boosts the ionic conductivity.3
However, such rearrangement generally occurs far from room temperature, limiting practical applications. Elevate ionic conductivity should also be coupled with a wide electrochemical stability:
although CB11H12- is one of the most stable anion among hydroborates,4 its use as stand-alone material is hampered by its poor conductivity at 20◦C.5 On this basis, via high-energy ball milling, we obtained a strain-induced NaCB11H12. T-dependent EIS reveals a non-Arrhenius behavior of the DC conductivity, suppressing the order/disorder transition. The oxidative stability is up to 4.35 V vs.
Na+/Na, in agreement with a recent report.6 Such improvement opens the gate to the use of
high-voltage positive electrodes, targeting competitive post-Li solid-state batteries.

Lieu

ZOOM MEETING

Please join us on Zoom, Meeting ID: 799 1837 469
https://unige.zoom.us/j/7991837469

entrée libre