Nanoscale structural oscillations in perovskite oxides induced by oxygen evolution

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Interactions between water and oxides are crucial for applications like energy storage, photocatalysis, and sensors.
• Understanding these interactions under irradiation is key to developing advanced materials.

Purpose of the Study:

• To investigate the structural response of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) to water vapor and electron irradiation.
• To elucidate the mechanisms behind observed structural changes and gas formation.

Main Methods:

• Environmental transmission electron microscopy (ETEM) was used to observe structural changes.
• Electron energy-loss spectroscopy (EELS) was employed to analyze the chemical composition of formed bubbles.

Main Results:

• BSCF displayed strong structural oscillations, characterized by the formation and collapse of gaseous bubbles under H₂O vapor and electron irradiation.
• EELS confirmed the presence of O₂ within these bubbles, resulting from H₂O incorporation into BSCF.
• Other oxides like SrCoO_3-δ showed minor oscillations, while La_0.5Sr_0.5CoO_3-δ and LaCoO₃ did not exhibit oscillations.

Conclusions:

• The unique structural oscillations in BSCF are attributed to its oxygen 2p-band center proximity to the Fermi level, facilitating oxygen vacancy formation, ion mobility, and water uptake.
• This study reveals novel insights into water-oxide interactions under electron-beam irradiation, particularly concerning gas bubble dynamics.