Charge states of Ca atoms in β-dicalcium silicate
Charge states of Ca atoms in β-dicalcium silicate
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DOI：
10.1016/j.jssc.2006.06.018
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发表时间：
2006-11
影响因子：
3.3
通讯作者：
K. Mori;R. Kiyanagi;M. Yonemura;K. Iwase;Takashi Sato;K. Itoh;M. Sugiyama;T. Kamiyama;T. Fukunaga
中科院分区：
文献类型：
--
作者：
K. Mori;R. Kiyanagi;M. Yonemura;K. Iwase;Takashi Sato;K. Itoh;M. Sugiyama;T. Kamiyama;T. Fukunaga
为了研究β-Ca 2SiO 4的晶体结构，在室温（RT）和600°C之间的温度下进行了飞行时间中子粉末衍射实验。RT下的Rietveld精修表明，基于P21/n对称性和两种不同类型的Ca位点Ca（1）和Ca（2），β-Ca 2SiO 4是单斜晶系。计算了所有原子间距离在3 π以内的原子间距离，用Zachariasen-Brown-Altermatt公式（键价和）估算了Ca（1）与7个CaO键和Ca（2）与8个CaO键的价态分别为1.87+和2+。应用电中性，β-Ca 2SiO 4中Ca的两种电荷状态分别为[Ca（1）SiO 4]2−和Ca（2）2+。此外，[Ca（1）SiO 4]2−单元具有最短的Ca-O距离，其长度在所有温度下都保持恒定，为2.23 Ω。在室温下的短程结构分析中，在径向分布函数中也观察到最短的Ca-O键。这些结果意味着[Ca（1）SiO 4]2−单元除了与Si-O共价外，还与最短的Ca-O共价。
In order to study the crystal structure of β‐Ca2SiO4, time-of-flight neutron powder diffraction experiments were carried out at temperatures between room temperature (RT) and 600°C. Rietveld refinement at RT has shown that β‐Ca2SiO4is monoclinic based on P21/n symmetry and two different types of Ca sites, Ca(1) and Ca(2). All interatomic distances within 3Å were calculated, with the valences of Ca(1) with seven CaO bonds and Ca(2) with eight were estimated to be 1.87+ and 2+ by the Zachariasen–Brown–Altermatt formula (bond valence sum). Applying charge neutrality the two charge states of Ca in β‐Ca2SiO4are [Ca(1)SiO4]2−and Ca(2)2+, respectively. Furthermore, the [Ca(1)SiO4]2−unit has the shortest Ca–O distance, and its length kept constant at 2.23Å at all temperatures. In the short-range structure analysis at RT, the shortest Ca–O bond was also observed in a radial distribution function. These results imply that the [Ca(1)SiO4]2−unit has covalency on the shortest Ca–O in addition to Si–O.