Chao Hsin-Yun, Nolan Adelaide M, Hall Alex T, Golberg Dmitri, Park Cheol, Yang Wei-Chang David, Mo Yifei, Sharma Renu, Cumings John
Department of Materials Science and Engineering, University of Maryland at College Park, College Park, Maryland 20742, United States.
Material Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States.
J Phys Chem C Nanomater Interfaces. 2024 Oct 22;128(43):18328-18337. doi: 10.1021/acs.jpcc.4c03814. eCollection 2024 Oct 31.
We present unprecedented results on the damage thresholds and pathways for boron nitride nanotubes (BNNT) under the influence of energetic electrons in an oxidative gas environment, using an environmental aberration-corrected electron microscope over a range of oxygen pressures. We observe a damage cascade process that resists damage until a higher electron dose, compared with carbon nanotubes, initiating at defect-free BNNT sidewalls and proceeding through the conversion from crystalline nanotubes to amorphous boron nitride (BN), resisting oxidation throughout. We compare with prior results on the oxidation of carbon nanotubes and present a model that attributes the onset of damage in both cases to a physisorbed oxygen layer that reduces the threshold for damage onset. Surprisingly, increased temperatures offer protection against damage, as do electron dose rates that significantly exceed the oxygen dose rates, and our model attributes both effects to a physisorbed oxygen population.
我们使用环境像差校正电子显微镜，在一系列氧气压力下，展示了在氧化气体环境中高能电子影响下氮化硼纳米管（BNNT）的损伤阈值和损伤途径方面前所未有的结果。我们观察到一个损伤级联过程，与碳纳米管相比，该过程在更高的电子剂量之前能够抵抗损伤，始于无缺陷的BNNT侧壁，并通过从结晶纳米管向非晶态氮化硼（BN）的转变而持续进行，全程抵抗氧化。我们将其与先前关于碳纳米管氧化的结果进行比较，并提出一个模型，该模型将两种情况下损伤的起始归因于一个物理吸附的氧层，该氧层降低了损伤起始的阈值。令人惊讶的是，升高的温度以及显著超过氧气剂量率的电子剂量率都能提供抗损伤保护，我们的模型将这两种效应都归因于物理吸附的氧群体。
