with Radiolysis-Driven Rolling of Octahedral Units

Radiolysis in transmission electron microscopy (TEM) is known to either amorphize or crystalize materials and limit the accuracy of the measurements. However, the precise atomistic mechanisms of these transformations are still under debate.  Here, we use scanning TEM (STEM) imaging and electron energy loss spectroscopy (EELS) to study the bond-breakage, atomic movements and crystallization mechanisms in rutile-TiO₂ driven by radiolysis. The sample was prepared by growing rutile IrO₂ on top of rutile TiO₂, introducing nano-meter width cracks due to epitaxial strain. With the accumulation of electron doses, the crack undergoes a self-healing restructuring process. Based on these observations and quantitative EELS analysis, we propose a “2-step rolling” model for the TiO₆ octahedral building blocks located at the crack’s edge of rutile-TiO₂ as a possible mechanism for radiolysis-driven atomic migration. These observations point to new possibilities to engineer novel nanostructures atom-by-atom [1].

 

[1] S. Guo, H. Yun, S. Nair, B. Jalan and K. A. Mkhoyan, Nat Commun 14, 6005 (2023).