Imaging microstructural dynamics and strain fields in electro-active materials in situ with dark field x-ray...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Crystallography

Background:

• Ferroelectric and piezoelectric materials' functional response depends on electric-field and temperature-induced dynamics of domains, defects, and phases.
• Quantifying these phenomena is challenging, hindering understanding of structure-property relationships.

Purpose of the Study:

• To develop and demonstrate an in situ dark field x-ray microscopy apparatus for studying structural dynamics in ferroelectric materials.
• To investigate the electric-field and temperature-induced phase transitions in barium titanate (BaTiO3) single crystals.

Main Methods:

• Utilized a novel in situ dark field x-ray microscopy setup for real-space mapping of lattice strain and orientation.
• Employed a stable temperature and electric field apparatus with precise control (up to 2 kV/mm, 200 °C, ΔT = ±0.01 K, 0.5 K/min ramp rate).
• Observed microstructural changes during the electric-field-induced cubic to tetragonal phase transition in BaTiO3.

Main Results:

• Demonstrated simultaneous control of electric fields and temperatures for studying structural dynamics.
• Observed unexpected growth directions of polar phase fronts and ferroelastic domains during phase transitions.
• Documented non-reversible lattice strain at the electrode-crystal interface after multiple electric field cycles.

Conclusions:

• The developed apparatus enables detailed studies of temperature and electric field dependent electromechanical transitions.
• Revealed critical influences of defects and interfaces on material behavior.
• Provides new insights into the complex dynamics governing ferroelectric and piezoelectric materials.