Direct Observation of Off-Stoichiometry-Induced Phase Transformation of 2D CdSe Quantum Nanosheetsopen access
- Authors
- Ma, Hyeonjong; Kim, Dongjun; Park, Soo Ik; Choi, Back Kyu; Park, Gisang; Baek, Hayeon; Lee, Hyocheol; Kim, Hyeongseoung; Yu, Jong-Sung; Lee, Won Chul; Park, Jungwon; Yang, Jiwoong
- Issue Date
- Mar-2023
- Publisher
- Wiley-VCH Verlag
- Keywords
- in situ transmission electron microscopy; phase transformation; quantum nanosheets; stoichiometry; two-dimensional nanocrystals
- Citation
- Advanced Science, v.10, no.7, pp 1 - 10
- Pages
- 10
- Indexed
- SCIE
SCOPUS
- Journal Title
- Advanced Science
- Volume
- 10
- Number
- 7
- Start Page
- 1
- End Page
- 10
- URI
- https://scholarworks.bwise.kr/erica/handle/2021.sw.erica/111595
- DOI
- 10.1002/advs.202205690
- ISSN
- 2198-3844
2198-3844
- Abstract
- Crystal structures determine material properties, suggesting that crystal phase transformations have the potential for application in a variety of systems and devices. Phase transitions are more likely to occur in smaller crystals; however, in quantum-sized semiconductor nanocrystals, the microscopic mechanisms by which phase transitions occur are not well understood. Herein, the phase transformation of 2D CdSe quantum nanosheets caused by off-stoichiometry is revealed, and the progress of the transformation is directly observed by in situ transmission electron microscopy. The initial hexagonal wurtzite-CdSe nanosheets with atomically uniform thickness are transformed into cubic zinc blende-CdSe nanosheets. A combined experimental and theoretical study reveals that electron-beam irradiation can change the stoichiometry of the nanosheets, thereby triggering phase transformation. The loss of Se atoms induces the reconstruction of surface atoms, driving the transformation from wurtzite-CdSe(112 over bar $\bar{2}$0) to zinc blende-CdSe(001) 2D nanocrystals. Furthermore, during the phase transformation, unconventional dynamic phenomena occur, including domain separation. This study contributes to the fundamental understanding of the phase transformations in 2D quantum-sized semiconductor nanocrystals.
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