Formation and Local Structure Analysis of High-valence Chromium Ion in Dicalcium Silicate
Formation and Local Structure Analysis of High-valence Chromium Ion in Dicalcium Silicate
复制标题
硅酸二钙中高价铬离子的形成及局部结构分析
DOI：
10.1111/jace.14337
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发表时间：
2016
影响因子：
3.9
通讯作者：
Toshihiro Tanaka
中科院分区：
文献类型：
--
作者：
Masanori Suzuki;Norimasa Umesaki;Toshihiro Okajima;Toshihiro Tanaka
硅酸二钙（2CaO·SiO2）是一种典型的硅酸盐化合物，即使在高温下也存在。不同类型的元素可以分散在硅酸二钙中以形成固溶体相。然而，可以显示不同离子价态的过渡元素的分散行为还没有得到很好的理解。在此，我们研究了分散在不同相态的硅酸二钙中的铬离子在惰性和空气气氛下的局部结构，使用Cr K边X射线吸收近边结构（XANES）光谱和第一性原理计算。测量的XANES光谱表明，Cr离子在空气气氛中分散在硅酸二钙中时以高价态存在。在973 K的空气气氛中，通过对2CaO·SiO2和Cr2 O3的混合物进行退火处理，在γ-硅酸二钙中检测到Cr 6+离子。此外，通过第一性原理计算获得的XANES光谱显示，在硅酸二钙中具有Cr 4+和Cr 6+之间的高价态的Cr离子占据四面体Si 4+位置。
Dicalcium silicate (2CaO·SiO2) is a typical silicate compound that exists even at elevated temperatures. Different types of elements can be dispersed in dicalcium silicate to form a solid solution phase. However, the dispersion behavior of transition elements that can display different ionic valences is not well understood. Herein, we investigate the local structure of chromium ions dispersed in dicalcium silicate of different phase states under inert and air atmospheres using Cr K‐edge X‐ray absorption near‐edge structure (XANES) spectroscopy and first‐principle calculations. The measured XANES spectra indicated that Cr ions exist as high‐valence states when dispersed in dicalcium silicate in air atmosphere. Specifically, Cr6+ions were detected in γ‐dicalcium silicate, which was prepared by annealing a mixture of 2CaO·SiO2and Cr2O3at 973 K in air atmosphere. In addition, the XANES spectra obtained via first‐principle calculations revealed that Cr ions, with high‐valence states between Cr4+and Cr6+, in dicalcium silicate, occupy the tetrahedral Si4+sites.