Achievement: A multi-university team first reported a unique lead-free ferroelectric compound - (Ca,Sr)3Mn2O7, which belongs to a class of materials described as hybrid improper ferroelectrics.
Significance and Impact: While it has long been hypothesized that polar and no-polar phases coexist inside ferroelectric materials, nobody has conclusively demonstrated the phenomena before experimentally. It has also been speculated that such co-existence explains the behavior of relaxor ferroelectrics, with such a model being known as the slush-and-ice model, where the slush is the non-polar matrix, in which ice (polar regions) are embedded. This was the first time experimentally this model was validated.
Research Details: Aberration corrected STEM using in-situ holders were used for imaging the atomic structure at multiple temperatures, and the images were then quantized for polar distortions through the open-source software EASY-STEM, developed by the authors. EASY-STEM was published previously in JoVE.
Facility: The work depended on using the transmission electron microscopy facilities at CNMS, ORNL
Sponsor/Funding: INTERSECT LDRD
PI and affiliation: Debangshu Mukherjee, Multimodal Data Analytics Group, Advanced Computing for Health Sciences (ACHS) Section, Computational Sciences & Engineering Division (CSED), ORNL
Team: Debangshu Mukherjee
Citation and DOI: Miao, L., et al. Double-Bilayer polar nanoregions and Mn antisites in (Ca,Sr)3Mn2O7. Nat Commun. 13, 4927 (2022). DOI: 10.1038/s41467-022-32090-w
