Materials Design Division

Irradiation Effects in Nuclear and Their Related Materials

Yasuyoshi NAGAI

Prof.Yasuyoshi NAGAI

  • Assoc. Prof. Koji INOUE
  • Assist. Prof. Yasuo SHIMIZU
  • Assist. Prof. Kazuaki NAGUMO

Towards Revealing Irradiation-Induced Defects and Controlling Their Function

We are studying defects, sub-nanoscale precipitates and interface segregations of impurity/solute atoms in materials. Our target extends from nuclear materials such as reactor pressure vessel steels and shroud stainless steels to semiconductors such as silicon and germanium. We employ positron annihilation, atom probe tomography, electron microscope, etc. By combining various theoretical calculations with the above experiments, we are clarifying the formation and microscopic structures of these defects, precipitates and interface segregations.

nuclear materials, semiconductors, positron, atom probe tomography, electron microscopy
Three-dimensional elemental map of surveillance test specimen of European- type PWR reactor pressure vessels (Doel-2, Belgium).

3D structural – chemical analyses by combining electron tomography by STEM with atom probe tomography and positron annihilation spectroscopy enable to directly reveal relationship between formation of irradiation induced fi ne defects and impurity segregation/clustering.

Dopant distributions in semiconductor devices obtained by atom probe tomography.

Dopant distributions in semiconductor devices obtained by atom probe tomography. Dopant segregation on grain boundaries and polycrystalline-Si/SiO2 interfaces were observed.

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