Hsin-Yun Chao1,2,3,Adelaide Mei-Chun Nolan2,Dmitri Golberg4,Cheol Park5,Yifei Mo2,Renu Sharma3,John Cumings2
Oak Ridge National Laboratory1,University of Maryland2,National Institute of Standards and Technology3,Queensland University of Technology4,NASA Langley Research Center5
Hsin-Yun Chao1,2,3,Adelaide Mei-Chun Nolan2,Dmitri Golberg4,Cheol Park5,Yifei Mo2,Renu Sharma3,John Cumings2
Oak Ridge National Laboratory1,University of Maryland2,National Institute of Standards and Technology3,Queensland University of Technology4,NASA Langley Research Center5
Nanotubes have the potential to be a light-weight alternative for radiation resistance applications. Multi-walled carbon nanotubes (CNTs) are shown to reduce secondary radiation when incorporated in a matrix while providing similar protection as conventional shielding materials [1]. Promising properties of boron-nitride nanotubes (BNNTs) for radiation resistance applications are also reported [2]. This project aims to explore the degradation mechanism of BNNT under electron irradiation. To modulate the electron-beam induced degradation, we employ the environmental transmission electron microscope (ETEM) to explore oxygen-assisted damage by varying O<sub>2</sub> pressure in the specimen chamber, accompanied by heating experiments above the desorption energy of O<sub>2</sub>. In particular, we find that BNNTs are less susceptible to damage with increasing O<sub>2</sub> pressure compared to CNTs. Molecular dynamics (MD) simulations are also utilized to calculate the knock-on energy threshold. The combination of experimental and computational work allows us to evaluate the resistance to electron-induced irradiation of BNNTs compared to CNTs, discover the fluctuation in electron displacement threshold with surface-adsorbed O<sub>2</sub>, and formulate a knock-on damage pathway for nanotubes through O<sub>2</sub> physisorption.<br/>[1] S. A. Thibeault, J. H. Kang, G. Sauti, C. Park, C. C. Fay, and G. C. King, “Nanomaterials for radiation shielding,” <i>MRS Bull.</i>, vol. 40, no. 10, pp. 836–841, Oct. 2015, doi: 10.1557/mrs.2015.225.<br/>[2] S. A. Thibeault <i>et al.</i>, “Radiation shielding materials containing hydrogen, boron and nitrogen: systematic computational and experimental study - phase I,” <i>NIAC Final Rep.</i>, vol. 1, no. 19, pp. 1–29, 2012.