Fast ion conductivity in strained defect-fluorite structure created by ion tracks in Gd2Ti2O7.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Ionics

Background:

• Swift heavy ion irradiation induces structural modifications in materials like Gd2Ti2O7 pyrochlore.
• Amorphous ion-tracks can lead to the formation of defect-fluorite ring structures with altered properties.

Purpose of the Study:

• To investigate the structure and ion-conducting properties of defect-fluorite rings formed around ion-tracks in Gd2Ti2O7 pyrochlore.
• To understand the role of tensile strain in stabilizing these structures and influencing ion transport.

Main Methods:

• High-angle annular dark-field imaging.
• Ion-track molecular dynamics simulations.
• Density functional theory calculations.
• Static pair-potential calculations.

Main Results:

• Disordered defect-fluorite ring structures with increased cation-cation interspacing and tensile strain were observed.
• Tensile strain was found to stabilize the non-equilibrium defect-fluorite structure.
• The pyrochlore to defect-fluorite transformation is linked to recrystallization and stabilized by tensile strain.
• Planar tensile strain reduces oxygen vacancy migration barriers.

Conclusions:

• The defect-fluorite structure formed by ion irradiation is stabilized by tensile strain.
• Strain engineering offers a pathway to control the stability and ion-conducting properties of these materials.
• This research has implications for designing materials with enhanced ionic conductivity.