Threshold displacement energies and defect formation energies in Y2Ti2O7

Area of Science:

• Materials Science
• Computational Materials Science
• Solid State Physics

Background:

• Yttrium titanate (Y2Ti2O7) is a pyrochlore material with potential applications in nuclear waste immobilization.
• Understanding radiation damage mechanisms is crucial for assessing material stability under irradiation.

Purpose of the Study:

• To determine the threshold displacement energies (Ed) for Y, Ti, and O atoms in Y2Ti2O7.
• To investigate defect configurations and formation energies resulting from irradiation.
• To explore the role of defects in irradiation-induced amorphization.

Main Methods:

• Ab initio molecular dynamics simulations were employed to calculate Ed.
• Ab initio methods were used to determine defect formation energies.
• Analysis of atomic configurations after low-energy recoil events.

Main Results:

• Minimum Ed values were found to be 27 eV (Y), 31.5 eV (Ti), 14.5 eV (O(48f)), and 13 eV (O(8b)).
• Stable cation interstitial configurations were identified at 8a sites and bridge sites.
• The stability of cation interstitials is proposed as a mechanism for amorphization.

Conclusions:

• The calculated Ed values provide insights into the radiation resistance of Y2Ti2O7.
• Identified stable defect structures are key to understanding irradiation effects.
• The findings suggest a potential pathway for amorphization in Y2Ti2O7 under irradiation.