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• 作者：S. Tamilarasan ; Debajit Sarma ; S. Bhattacharjee ; U. V. Waghmare ; S. Natarajan ; J. Gopalakrishnan
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：May 20, 2013
• 年：2013
• 卷：52
• 期：10
• 页码：5757-5763
• 全文大小：523K
• 年卷期：v.52,no.10(May 20, 2013)
• ISSN：1520-510X

文摘

We describe the synthesis, crystal structures, and optical absorption spectra of transition metal-substituted spiroffite derivatives, Zn_2鈥?i>xM_xTe₃O₈ (M^II = Co, Ni, Cu; 0 < x 鈮?1.0). The oxides are readily synthesized by solid state reaction of stoichiometric mixtures of the constituent binaries at 620 掳C. Reitveld refinement of the crystal structures from powder X-ray diffraction (XRD) data shows that the Zn/MO₆ octahedra are strongly distorted, as in the parent Zn₂Te₃O₈ structure, consisting of five relatively short Zn/M^II鈥揙 bonds (1.898鈥?.236 脜) and one longer Zn/M^II鈥揙 bond (2.356鈥?.519 脜). We have interpreted the unique colors and the optical absorption/diffuse reflectance spectra of Zn_2鈥?i>xM_xTe₃O₈ in the visible, in terms of the observed/irregular coordination geometry of the Zn/M^II鈥揙 chromophores. We could not however prepare the fully substituted M₂Te₃O₈ (M^II = Co, Ni, Cu) by the direct solid state reaction method. Density Functional Theory (DFT) modeling of the electronic structure of both the parent and the transition metal substituted derivatives provides new insights into the bonding and the role of transition metals toward the origin of color in these materials. We believe that transition metal substituted spiroffites Zn_2鈥?i>xM_xTe₃O₈ reported here suggest new directions for the development of colored inorganic materials/pigments featuring irregular/distorted oxygen coordination polyhedra around transition metal ions.