Band Gap Energy and Lattice Distortion in Anatase TiO₂ Thin Films Prepared by Reactive Sputtering with Different Thicknesses.

IF 3.1 3区材料科学 Q3 CHEMISTRY, PHYSICAL

Materials Pub Date : 2025-05-18 DOI:10.3390/ma18102346

Cecilia Guillén

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引用次数: 0

Abstract

TiO₂ is an abundant material on Earth, essential for the sustainable and cost-effective development of various technologies, with anatase being the most effective polymorph for photocatalytic and photovoltaic applications. Bulk crystalline anatase TiO₂ exhibits a band gap energy E_gA = 3.2 eV, for tetragonal lattice parameters a_A = 0.3785 nm and c_A = 0.9514 nm, but these characteristics vary for amorphous or polycrystalline thin films. Reactive magnetron sputtering has proven suitable for the preparation of TiO₂ coatings on glass fiber substrates, with structural and optical characteristics that change during growth. Below a minimum thickness (t < 0.2 μm), the films have an amorphous nature or extremely small crystallite sizes not observable by X-ray diffraction. Afterwards, compressed quasi-randomly orientated crystallites are detected (volume strain ΔV = -0.02 and stress σ_V = -3.5 GPa for t = 0.2 μm) that evolve into relaxed and preferentially (004) orientated crystallites, reaching the standard anatase values at t ~ 1.4 μm with σ_V = 0.0 GPa. The band gap energy increases with lattice distortion according to the relation ∆E_g (eV) = -6∆V, and a further increase is observed for the thinnest coatings (∆E_g = 0.24 eV for t = 0.05 μm).

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反应溅射制备不同厚度锐钛矿型TiO2薄膜的能带能和晶格畸变

TiO2是地球上丰富的材料，对各种技术的可持续和经济发展至关重要，锐钛矿是光催化和光伏应用中最有效的多晶型。在正方晶格参数aA = 0.3785 nm和cA = 0.9514 nm时，TiO2的带隙能EgA = 3.2 eV，但这些特性在非晶和多晶薄膜中有所不同。反应磁控溅射已被证明适合在玻璃纤维衬底上制备TiO2涂层，其结构和光学特性在生长过程中会发生变化。在最小厚度（t < 0.2 μm）以下，薄膜具有非晶性质或极小的晶体尺寸，这是x射线衍射无法观察到的。在t = 0.2 μm时，压缩后的准随机取向晶体（体积应变ΔV = -0.02，应力σV = -3.5 GPa）演化为松弛的、优先取向的（004）取向晶体，在t ~ 1.4 μm时，σV = 0.0 GPa时达到锐钛矿的标准取向。根据∆Eg (eV) = -6∆V的关系，带隙能量随晶格畸变的增加而增加，并且对于最薄的涂层（t = 0.05 μm时∆Eg = 0.24 eV），带隙能量进一步增加。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Materials MATERIALS SCIENCE, MULTIDISCIPLINARY-

CiteScore

5.80

自引率

14.70%

发文量

7753

审稿时长

1.2 months

期刊介绍： Materials (ISSN 1996-1944) is an open access journal of related scientific research and technology development. It publishes reviews, regular research papers (articles) and short communications. Our aim is to encourage scientists to publish their experimental and theoretical results in as much detail as possible. Therefore, there is no restriction on the length of the papers. The full experimental details must be provided so that the results can be reproduced. Materials provides a forum for publishing papers which advance the in-depth understanding of the relationship between the structure, the properties or the functions of all kinds of materials. Chemical syntheses, chemical structures and mechanical, chemical, electronic, magnetic and optical properties and various applications will be considered.