Freestanding Perovskite and Brownmillerite SrCoO Membranes for Direct Imaging of Topotactic Phase Transitions
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Updated: May 20, 2025
Epitaxial Growth of Perovskite Strontium Titanate on Germanium via Atomic Layer Deposition
Published on: July 26, 2016
Hudson Alex Shih1, Jieyang Zhou1, Izoah Leone Snowden1
1Department of Materials Science & Engineering, University of California, Davis, One Shields Ave., Davis, California 95616, United States.
Abstract:
Topotactic phase transitions between perovskite SrCoO3 and brownmillerite SrCoO2.5 have garnered attention for application in energy-efficient neuromorphic computing systems. However, the evolution of local microstructures, crucial for designing topotactic devices and improving switching performance, remains underexplored due to the limitations of epitaxial thin films bound to bulk substrates. Here, we report the synthesis and characterization of topotactic oxide SrCoO as a freestanding membrane, successfully stabilizing both perovskite and brownmillerite phases. Plan-view transmission electron microscopy identifies the extraordinary formation of filamentary one-dimensional (1D) domains of SrCoO2.5 phases during the topotactic phase transition, correlated with the 1D oxygen vacancy channels that facilitate rapid oxygen ion diffusion. These 1D domains serve as direct evidence of the anisotropic nature of the topotactic phase transition, dictated by oxygen diffusion. These findings also underscore the advantages of freestanding membrane geometries for developing a fundamental understanding of phase transitions in complex oxides.
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