Manabu ISHIMARU - Electron Diffraction Study of Short-Range Ordered Structures in Ion- Irradiated Ceramics

When crystalline materials with long-range order are exposed to radiation
environments, their structure changes to a short-range ordered state with damage
accumulation. Knowledge of radiation-induced structural changes is of technological
importance for realizing desirable material properties and for predicting the fate of
materials under radiation environments. Information on short-range ordered structures
appears as diffuse scattering in diffraction patterns, but its intensity is so weak that the
diffuse scattering associated with disordering has not been well investigated. Electron
diffraction has the advantage of detecting weak scattering intensities, because of the
strong interaction between the matter and electrons. Furthermore, the short
wavelength of high-energy electrons enables us to obtain diffraction intensity profiles
up to high scattering angles in the reciprocal lattice space, which is useful for precise
amorphous structure analysis. We have been analyzing the structures of radiation-induced metastable
crystalline and amorphous phases using transmission electron microscopy. In this seminar, we will report (1)
radiation-induced amorphous structures studied by a quantitative analysis of halo intensities [1] and (2) shortrange
ordered metastable crystalline phase formed during disordering processes [2-4].

[1] M. Ishimaru, R. Nakamura, Y. Zhang, W. J. Weber, G. G. Peterson, N. J. Ianno, and M. Nastasi, J. Eur. Ceram. Soc. 42, 376 (2022).
[2] M. Iwasaki, Y. Kanazawa, D. Manago, M. K. Patel, G. Baldinozzi, K. E. Sickafus, and M. Ishimaru, J. Appl. Phys. 132, 075901
(2022).
[3] M. Iwasaki, M. K. Patel, G. Baldinozzi, K. E. Sickafus, and M. Ishimaru, J. Eur. Ceram. Soc. 44, 3131-3138 (2024).
[4] T. Izumi, M. Iwasaki, M. K. Patel, G. Baldinozzi, C. Grygiel, and M. Ishimaru, Acta Mater. 284, 120581 (2025).