Electromechanically active pair dynamics in a Gd-doped ceria single crystal.

Area of Science:

• Materials Science
• Solid State Physics
• Ceramics

Background:

• Oxygen-defective ceria, such as Gadolinium-doped ceria, displays significant electromechanical properties.
• These properties are linked to cation-oxygen vacancy (Ce-VO) pairs and local lattice distortions, though mechanisms are not fully understood.

Purpose of the Study:

• To investigate the geometry and behavior of Ce-VO pairs in a single-crystal Gadolinium-doped ceria under an AC electric field.
• To understand the temperature dependence of electrostriction and its relation to the population of electrically active pairs.

Main Methods:

• X-ray absorption spectroscopy (XAS) at the Ce L-III edge was used to analyze the material.
• Density Functional Theory (DFT) calculations were employed to study the effects of strain on electronic states.

Main Results:

• Electrostriction was found to increase substantially at lower temperatures.
• Electromechanical strain rose by an order of magnitude from room temperature to -193 °C.
• This increase is attributed to a higher population of electrically active Ce-VO pairs.

Conclusions:

• The electromechanical strain in oxygen-defective ceria is structural and highly temperature-dependent.
• Materials can form heterogeneous pairs and elastic nanodomains with varying mechanical responsiveness.
• Understanding these mechanisms is crucial for advanced functional materials.