Characterization of Electronic States of TiO2 Powders by Photoacoustic Spectroscopy
Characterization of Electronic States of TiO2 Powders by Photoacoustic Spectroscopy
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光声光谱表征 TiO2 粉末的电子态
DOI：
10.1143/jjap.39.3160
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发表时间：
2000
影响因子：
1.5
通讯作者：
M. Ohmori
中科院分区：
文献类型：
--
作者：
T. Toyoda;H. Kawano;Q. Shen;A. Kotera;M. Ohmori
我们用光声（PA）光谱测量了TiO2粉末的光吸收，这对于检测少量强散射材料是很有用的。颗粒半径为40 nm的金红石型和锐钛矿型TiO2粉末的带隙能Eg分别为3.06 eV和3.20 eV，说明了PA光谱的实用性。PA强度和相光谱结果表明，粒径为11 nm的锐钛矿型TiO2粉体的Eg值在实验精度范围内为3.25 eV（蓝移），表明随着粒径的减小，可能出现了量子尺寸效应。根据乌尔巴赫规则（指数尾），在带隙下方，与光子能量呈半对数线性变化。金红石型TiO2粉体的指数吸收斜率大于锐钛矿型TiO2粉体的指数吸收斜率，说明锐钛矿型TiO2粉体在生产过程中由于氧空位和/或氯杂质导致的原子位移使能量增加。
We have measured the optical absorption of TiO2 powders by photoacoustic (PA) spectroscopy, which is powerful for detecting small amounts of strongly scattering materials. The band-gap energies Eg of rutile and anatase types of TiO2 powders with particle radii of 40 nm are 3.06 eV and 3.20 eV, respectively, from PA intensity and PA phase spectra, indicating the usefulness of PA spectroscopy. The PA intensity and phase spectra show that the Eg of anatase-type TiO2 powders with a particle radius of 11 nm is 3.25 eV (blue shift) within the experimental accuracy, indicating the possible onset of a quantum size effect with decreasing particle size. The PA intensities plotted semilogarithmically vary linearly with photon energy immediately below the band-gap, in accordance with Urbach's rule (exponential tail). The slope of the exponential absorption of rutile-type TiO2 powders is larger than that of the anatase, indicating that the anatase-type has increasing energy from the displacement of atoms specifically due to oxygen vacancies and/or chlorine impurities in the production processes of the powders.