Diffusivity of Al vacancies in corundum (αAl2O3)

IF 3.8 3区材料科学 Q1 MATERIALS SCIENCE, CERAMICS Journal of the American Ceramic Society Pub Date : 2025-02-27 DOI:10.1111/jace.20460

Michael C. Jollands

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Abstract

The diffusivity of Al vacancies in corundum has been experimentally determined from 1300°C to 1500°C, by annealing high-purity single crystals in the presence of water at a high pressure (∼1.5 GPa), followed by spatially resolved Fourier transform infrared spectroscopy on slabs cut from the cores of crystals. Infrared spectra recorded from the experimental products show bands at 3263 and 3421 cm⁻¹, with the former having a shoulder at 3278 cm⁻¹. These bands are interpreted to represent H (as protons) charge-compensating vacant Al sites, likely as ${(V_{Al}^{'''} 2 H_{i}^{•})}^{'}$ , ${(V_{Al}^{'''} H_{i}^{•})}^{'}$ , and/or $H_{i}^{•}$ , although their exact assignment is unclear.

Regardless, the Arrhenius relationship derived for the diffusivity of (assumed) protonated vacancies, based on fitting profiles of band absorbance versus distance from the crystal edge from the three experiments, is:

Uncertainties are 2σ. The activation energy (equivalent to 4.4 eV) and absolute diffusivity values are consistent with previously published values representing Al vacancy diffusion in corundum, supporting the interpretation of the identities of the absorption bands.

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刚玉中Al空位的扩散系数（αAl2O3）

从1300°C到1500°C，通过实验确定了刚玉中Al空位的扩散率，方法是在高压（~ 1.5 GPa）下，在存在水的情况下对高纯度单晶进行退火，然后在从晶体核心切割的板上进行空间分辨傅立叶变换红外光谱。实验产物记录的红外光谱显示3263和3421 cm−1波段，前者在3278 cm−1处有一个肩。这些条带被解释为代表H（作为质子）电荷补偿的空Al位，可能为（V Al ' ' ' ‘ 2 H i•）’${({V}_{\ mathm {Al}}^{\prime \prime \prime}2{\ mathm {H}}_{i}^{\ensuremath{\bullet}})}^{\prime}$，（V Al ' ' ‘ H i•）’${({V}_{\mathrm{Al}}^{\prime \prime}{\mathrm{H}}_{\ensuremath{\bullet}})}^{\prime}$和/或H i•${\mathrm{H}}_{i}^{\ensuremath{\bullet}}$，尽管它们的确切赋值并不清楚。无论如何，基于三个实验的带吸光度与晶体边缘距离的拟合曲线，推导出（假设的）质子空位的扩散系数的Arrhenius关系为：不确定性为2σ。活化能（相当于4.4 eV）和绝对扩散系数值与先前发表的代表Al空位在刚玉中的扩散的值一致，支持对吸收带身份的解释。

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

Journal of the American Ceramic Society 工程技术-材料科学：硅酸盐

CiteScore

7.50

自引率

7.70%

发文量

590

审稿时长

2.1 months

期刊介绍： The Journal of the American Ceramic Society contains records of original research that provide insight into or describe the science of ceramic and glass materials and composites based on ceramics and glasses. These papers include reports on discovery, characterization, and analysis of new inorganic, non-metallic materials; synthesis methods; phase relationships; processing approaches; microstructure-property relationships; and functionalities. Of great interest are works that support understanding founded on fundamental principles using experimental, theoretical, or computational methods or combinations of those approaches. All the published papers must be of enduring value and relevant to the science of ceramics and glasses or composites based on those materials. Papers on fundamental ceramic and glass science are welcome including those in the following areas: Enabling materials for grand challenges[...] Materials design, selection, synthesis and processing methods[...] Characterization of compositions, structures, defects, and properties along with new methods [...] Mechanisms, Theory, Modeling, and Simulation[...] JACerS accepts submissions of full-length Articles reporting original research, in-depth Feature Articles, Reviews of the state-of-the-art with compelling analysis, and Rapid Communications which are short papers with sufficient novelty or impact to justify swift publication.