Gene

Vacancy defect

Spectroscopy

Quantum mechanics

Chemical physics

Metallurgy

Materials science

Radiation damage

Nuclear physics

Tungsten

Atomic physics

Biochemistry

Geology

Oceanography

Positron annihilation

Physics

Irradiation

Frenkel defect

Recombination

Annihilation

Molecular physics

Positron annihilation spectroscopy

Positron

Particle (ecology)

Kinetics

Crystallography

Chemistry

Electron

Crystallographic defect

APL Materials

Reliable and accurate knowledge of the physical properties of elementary point defects is crucial for predictive modeling of the evolution of radiation damage in materials employed in harsh conditions. We have applied positron annihilation spectroscopy to directly detect mono-vacancy defects created in tungsten through particle irradiation at cryogenic temperatures, as well as their recovery kinetics. We find that efficient self-healing of the primary damage takes place through Frenkel pair recombination already at 35 K, in line with an upper bound of 0.1 eV for the migration barrier of self-interstitials. Further self-interstitial migration is observed above 50 K with activation energies in the range of 0.12–0.42 eV through the release of the self-interstitial atoms from impurities and structural defects and following recombination with mono-vacancies. Mono-vacancy migration is activated at around 550 K with a migration barrier of EmV=1.85±0.05 eV.

Direct observation of mono-vacancy and self-interstitial recovery in tungsten