First-Principles Calculations and Optical Absorption Spectrum of a Light-Colored Aluminum-Substituted ε-Iron Oxide Magnet

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• 作者：Tomomichi Nasu ; Marie Yoshikiyo ; Hiroko Tokoro ; Asuka Namai and Shin-ichi Ohkoshi
• 刊名：European Journal of Inorganic Chemistry
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：2017
• 期：3
• 页码：531-534
• 全文大小：1138K
• ISSN：1099-0682c

文摘

In this paper, we report the electronic structure and optical properties of Al-substituted ε-Fe₂O₃. First-principles calculations of the periodic structure of ε-Al_0.5Fe_1.5O₃ reveal that the band gaps (E_g) are 2.6 (480 nm) and 2.5 eV (500 nm) for the up-spin and down-spin transitions, respectively. To investigate the electronic structure, a highly dispersed polymer solution composed of ε-Al_0.66Fe_1.34O₃ nanoparticles was prepared. This solution is light orange in color; the absorption coefficients (ε) are small with values of 810 and 260 dm³ mol^–1 cm^–1 at 3.1 (400 nm) and 2.6 eV (480 nm), respectively. The reason why Al-substituted ε-Fe₂O₃ is so light in color can be understood by the disappearance of the energy states in the conduction and valence bands, which originates from the tetrahedral D site. Such a light-colored magnetic material should be useful for colored magnetic toners for color printing.