Research Highlight

Epitaxial Strain Activates Oxygen in Complex Oxides

The schematic represents strain control of oxygen stoichiometry in a SrCoO3-δ  epitaxial thin film. Tensile strain is found to facilitate oxygen movement through oxygen vacancy channels in SrCoOx and reduces the stability of oxygen intercalation, leading to vacancy formation, whereas compressive strain preferentially immobilizes oxygen.

Researchers demonstrated that straining the crystal lattice of strontium cobaltite reduces oxygen content even under highly oxidizing conditions,

Epitaxial Strain Activates Oxygen in Complex Oxides The schematic represents strain control of oxygen stoichiometry in a SrCoO3-δ epitaxial thin film. Tensile strain is found to facilitate oxygen movement through oxygen vacancy channels in SrCoOx and reduces the stability of oxygen intercalation, leading to vacancy formation, whereas compressive strain preferentially immobilizes oxygen. (hi-res image)
enabling formation of functional oxygen defects at lower temperatures than previously possible Since the oxygen vacancies govern many technologically important functionalities, including superconductivity, ferromagnetism, and electrocatalysis, this work enables dramatic advances in vacancy-enhanced functionalization of oxide materials.  

The SrCoO3-δ thin films were grown by pulsed laser epitaxy onto substrates with different lattice spacings, in order to change the strain of the films. Strain is used to deliberately modify the oxygen vacancy content even under conditions that ordinarily fully oxidize unstrained films. While of immediate benefit for low temperature energy production and storage devices and sensors, the ability to artificially control oxygen vacancy content in any environment is crucial for variety of functional materials, such as high-temperature superconductors, colossal magnetoresistors, memristors, spintronic devices, and electrocatalysts.

J. Petrie, C. Mitra, H. Jeen, W. S. Choi, T. Meyer, F. A. Reboredo, J. W. Freeland, G. Eres, and H. N. Lee, “Strain control of oxygen vacancies in epitaxial strontium cobaltite films,” Advanced Functional Materials (2016). DOI:10.1002/adfm.201504868 

For more information, please contact Ho Nyung Lee:  hnlee@ornl.gov

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