Seminar & Colloquium
[세미나: 12월 5일(목), 오후 2시] Prof. Atsutomo Nakamura, Osaka University
Title
Room-temperature plastic deformation behavior of inorganic semiconductor crystals
Speaker
Prof. Atsutomo Nakamura, Professor of school/graduate school of engineering science, Osaka University, Japan
* Biography
Prof. Atsutomo Nakamura is the director of Nanomechanics & Physics Laboratory (http://nano.me.es.osaka-u.ac.jp/) in the school of engineering science, Osaka University, Japan. Prior to joining Osaka University in 2021, he was an associate professor at Nagoya University from 2012. He holds a B.E. and an M.E. from Kyoto University, and a Ph.D. from The University of Tokyo. Prof. Nakamura's research focuses on understanding the mechanical properties of solid materials from the atomic and electronic scales, as well as on structure-property correlations on the atomic and electronic scales. His research employs state-of-the-art transmission electron microscopy and atomic force microscopy to observe and analyze the local structure and function of crystal lattice defects, including dislocations and grain boundaries. The work spans from nanoscale to macroscale mechanical testing, providing insight into the plasticity and strength properties of various materials.
| Date | Thursday, December 5th, 2024
| Time | 14:00~14:50
| Venue | 33동 125호(WCU 다목적실)
[Abstract]
Inorganic semiconductors are essential to modern technologies, such as power electronics and integrated circuits. However, their application in advanced fields has been limited due to their limited plasticity, brittleness and poor processability at room temperature. In contrast, our research has shown that the external light environment plays an important role in controlling the plastic deformation behavior of semiconductor crystals at room temperature. ZnS single crystals exhibit brittle properties under normal light environments, but in complete darkness they show surprising plasticity mediated by the glide and multiplication of dislocations [1]. Furthermore, creep deformation tests at room temperature have shown that the mobility of dislocations changes by more than three orders of magnitude depending on the presence or absence of light [2]. The cause of these phenomena is believed to be that in the presence of light, the atomic bonding state with local electronic structure at the dislocation core changes due to the electrostatic interaction between the photo-excited carriers caused by the internal photoelectric effect and the structural charge of individual dislocations, resulting in a large change in the mobility of the dislocation, thus limiting the deformability of the crystal [3-4]. These findings have broken the conventional wisdom that inorganic materials are brittle and easily fractured at room temperature, and have led to new possibilities for the processing and application of inorganic materials, as well as to a wide range of new research on the plasticity of inorganic semiconductor materials [5-7].
[1] Y. Oshima, A. Nakamura*, K. Matsunaga*, Science 360, (2018) 772–774.
[2] Y. Oshima, A. Nakamura* et al., Acta Mater. 195, (2020) 690–697.
[3] K. Matsunaga*, A. Nakamura et al., Acta Mater. 195, (2020) 645–653
[4] S. Hoshino, A. Nakamura, K. Matsunaga* et al., Phys. Rev. Mater. 7, (2023), 013603.
[5] A. Nakamura*, X. Fang* et al., Nano Lett. 21. (2021) 1962–1967.
[6] Y. Li*, A. Nakamura* et al., J. Mater. Sci. Tech. 156, (2023) 206–216.
[7] H. Oguri, Y. Li*, A. Nakamura* et al., J. Euro. Ceram. Soc. 44, (2024) 1301–1305.
| Host | 최인석 교수(02-880-1712)