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The amorphous-to-crystalline transition in TiO2 films upon annealing in air yields different polymorphs, depending on the oxygen partial pressure during the deposition of the amorphous precursor film. We further manipulate the resulting polymorph by introducing Sn into the system. By depositing a few nanometer-thick layer of metallic Sn between two layers of amorphous TiO2 prepared to yield the anatase polymorph of TiO2, we find that it results in the rutile polymorph if the content of Sn is high enough. If Sn is introduced as an oxide, no rutile is formed; anatase is by far the predominant phase (with a very small amount of brookite). This observation is consistent with scavenging of oxygen by elemental Sn at the Sn/TiO2 interfaces, stabilizing the rutile structure that can accommodate oxygen vacancies.
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In situ ion irradiation of amorphous TiO2 nanotubes
Understanding of structural and morphological evolution in nanomaterials is critical in tailoring their functionality for applications such as energy conversion and storage. Here, we examine irradiation effects on the morphology and structure of amorphous TiO2 nanotubes in comparison with their crystalline counterpart, anatase TiO2 nanotubes, using high-resolution transmission electron microscopy (TEM), in situ ion irradiation TEM, and molecular dynamics (MD) simulations. Anatase TiO2 nanotubes exhibit morphological and structural stability under irradiation due to their high concentration of grain boundaries and surfaces as defect sinks. On the other hand, amorphous TiO2 nanotubes undergo irradiation-induced crystallization, with some tubes remaining only partially crystallized. The partially crystalline tubes bend due to internal stresses associated with densification during crystallization as suggested by MD calculations. These results present a novel irradiation-based pathway for potentially tuning structure and morphology of energy storage materials.
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- PAR ID:
- 10319023
- Date Published:
- Journal Name:
- Journal of Materials Research
- ISSN:
- 0884-2914
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1557/s43578-022-00516-2
