Anomalous Kinetics of Diffusion-Controlled Defect Annealing in Irradiated Ionic Solids

Area of Science:

• Materials Science
• Solid State Physics
• Radiation Damage

Background:

• F-type color centers, such as oxygen vacancies with trapped electrons, are crucial defects in ionic materials.
• Understanding their annealing kinetics is vital for predicting material behavior under irradiation.

Purpose of the Study:

• To analyze the annealing kinetics of F-type color centers in Al2O3, MgO, and MgF2.
• To extract migration energies and diffusion pre-exponential factors of interstitial ions.
• To investigate the influence of radiation fluence on defect migration parameters.

Main Methods:

• Experimental analysis of annealing kinetics for irradiated ionic materials (Al2O3, MgO, MgF2).
• Application of phenomenological theory for diffusion-controlled recombination.
• Comparison of experimental data with first-principles calculations.

Main Results:

• Migration energy and pre-exponential factor of interstitials decrease with increasing radiation fluence.
• This correlation follows the Meyer-Neldel rule, observed in various disordered materials.
• The effect is independent of the irradiation type (electrons, neutrons, heavy ions).

Conclusions:

• The dependence of defect migration parameters on radiation fluence is significant and cannot be ignored in radiation damage analysis.
• The observed Meyer-Neldel rule provides insights into the origin of this fluence dependence.
• This research highlights the importance of considering dynamic defect properties in irradiated materials.