In Situ Cryogenic HAADF-STEM Observation of Spontaneous Transition of Ferroelectric Polarization Domain Structures at Low Temperatures.
basic_science · Level V
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- Record sourced from PubMed, PMID 34644077.
- Also identified by DOI 10.1021/acs.nanolett.1c02729.
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Abstract
Precise determination of atomic structures in ferroelectric thin films and their evolution with temperature is crucial for fundamental study and design of functional materials. However, this has been impeded by the lack of techniques applicable to a thin-film geometry. Here we use cryogenic scanning transmission electron microscopy (STEM) to observe the atomic structure of a BaTiO<sub>3</sub> film on a (111)-SrTiO<sub>3</sub> substrate under varying temperatures. Our study explicitly proves a structure transition from a complex polymorphic nanodomain configuration at room temperature transitioning to a homogeneous ground-state rhombohedral structure of BaTiO<sub>3</sub> below ∼250 K, which was predicted by phase-field simulation. More importantly, another unexpected transition is revealed, a transition to complex nanodomains below ∼105 K caused by an altered mechanical boundary condition due to the antiferrodistortive phase transition of the SrTiO<sub>3</sub> substrate. This study demonstrates the power of cryogenic STEM in elucidating structure-property relationships in numerous functional materials at low temperatures.