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The Microstructure, Morphology, and Mechanical Properties of Sol–Gel-Derived Amorphous Aluminum Oxide Films

Year: 2024
Type: article
Abstract: Amorphous alumina films are isotropic and have no grain boundaries, which make them have smooth surfaces, excellent properties, and wide applications in protective coatings, catalysis, and microelectronics. However, high-quality alumina films were usually prepared by vapor-phase approaches which need expensive equipment and long production time. Additionally, amorphous films are long-range disordered, which makes the study of structure–property relationships challenging. Here, a simple sol–gel method is employed to obtain high-quality amorphous Al 2 O 3 thin films. The microstructure, morphology, and mechanical properties of amorphous Al 2 O 3 thin films were systematically investigated. All the Al 2 O 3 thin films heat-treated at 600–800 ∘ C are in amorphous state with ultrasmooth surface (Ra values about 0.29–0.43 nm) and high mechanical properties (elastic modulus ∼170[Formula: see text]GPa, hardness ∼20[Formula: see text]GPa). The mechanical properties (E and H) of Al 2 O 3 films gradually increase with the increase of heat-treating temperature. Additionally, the Al coordination of the amorphous alumina films are analyzed by solid-state NMR and correlated with the mechanical properties. The results show that in amorphous alumina, the presence of tetrahedral Al ([4]Al) and octahedral Al ([6]Al) is helpful to improve the mechanical properties, while the five-coordinated Al ([5]Al) is not conducive to improve the mechanical properties. The results demonstrate that sol–gel method is an attractive alternative to time-consuming and expensive vapor-phase approaches and are useful for scale-up to applications and research of amorphous alumina films.
DOI: 10.1142/s2811086224500067
Institution: Zhejiang University
Language: English
Open Access status: diamond
OpenAlex ID: W4402323884
FWCI:
Cites: 34
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Related to: 10