Ms. CHIEW, Yi Ling (2nd year doctoral student in OSHIMA Lab of Applied Physics Area), received Best Poster Award in 10th International Conference on Materials for Advanced Technologies (ICMAT), held in Singapore (The number of participants is about 3,000). This work is collaboration between our lab and KOYANO Lab of Energy and Environment Area.

■Date Awarded
June 28, 2019

■Title
Unravelling Planar Distribution of Intercalated Fe Atoms in TiS2 Layered Structure Using Transmission Electron Diffraction

■Authors
Y. CHIEW, S. ABE, M. MIYATA, M. KOYANO, Y. OSHIMA

■Abstract
The discovery of new functions by intercalating guest atoms into host layered materials have attracted attention due to the wide possibilities of applications achievable. These intercalated 2-dimensional materials are known to form complex superlattices, which are difficult to analyze. For example, the material in this study, FexTiS2, has been reported to form 2a×2a or √3a×√3a superlattices for x = 1/4 or 1/3, respectively (a is the lattice constant of the TiS2 layer) where the Fe atoms occupy octahedral sites. However, in our study, a new, larger superlattice is proposed for FexTiS2 (grown with nominal content x = 0.33), based on the transmission electron diffraction (TED) pattern. TED is a powerful method that can be used to clarify two-dimensional atomic structures such as the Si (111) 7×7 reconstruction. Using the Patterson map constructed from TED pattern, the superlattice is observed to have P3 symmetry with unit lengths of √43 a× √43 a, rotated at an angle of 7.5888°. Further analysis of the TED pattern and its Patterson map also allowed the determination of the planar distribution of Fe atoms. Nine Fe atoms are found to be present in the unit cell and the Fe atoms occupy not only octahedral sites, as reported previously, but in tetrahedral sites as well.

■Comment
It is a great honor to receive this award from the conference. I am extremely grateful to Prof. Yoshifumi Oshima, Prof. Mikio Koyano and Assistant Prof. Masanobu Miyata for the constant guidance. I would also like to thank the staff of Nanotechnology Platform in JAIST for their support with my sample preparation and characterization. And last by not least, I would like to thank all my lab members and friends for always being there for me.

3,July 2019