Fetzer, Ann-Katrin ; Wohninsland, Andreas ; Kodumudi Venkataraman, Lalitha ; Kleebe, Hans-Joachim (2021)
In situ hot-stage TEM of the phase and domain evolution in quenched Na1/2Bi1/2TiO3–BaTiO3.
In: Journal of the American Ceramic Society
doi: 10.1111/jace.18266
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

Quenching relaxor ferroelectric 0.94(Na1/2Bi1/2)TiO3–0.06BaTiO3(NBT-6BT)enhances the depolarization temperature (Td), linked to the stabilization offerroelectric order. The thermal evolution of the domain structure and phaseassemblage provides insights about the onset of ferroelectric order in quenchedmaterials. Unpoled furnace cooled and quenched NBT-6BT ceramics were stud-ied using in situ temperature-dependent transmission electron microscopy. Therhombohedraltotetragonalstructuraltransitioninfurnacecooledandquenchedsamples occurs in a comparable temperature range of 120◦C–220◦C. While thetetragonal phase is characterized by polar nanoregions (PNRs) and no domaincontrast in the furnace cooled state, the quenched composition exhibits anincreased fraction of lamellar domains, which are partially stable up to 300◦C,thus benefiting the delayed depolarization. This is further corroborated by the dielectric data indicating earlier freezing of PNR dynamics in the quenched state.The reversibility of the phase transition is demonstrated by successive cooling,where quenched NBT-6BT features an increased grainy PNR contrast after theexperiment, followed by a kinetically delayed coalescence of PNRs back intolamellar domains. This demonstrates that the stabilized ferroelectric state uponquenching is associated with the conversion of polar units on the nanometerscale into long-range domain structures.

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