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首页> 外文期刊>Nature >STRUCTURAL CHARACTERIZATION OF PENTACOORDINATE SILICON IN A CALCIUM SILICATE
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STRUCTURAL CHARACTERIZATION OF PENTACOORDINATE SILICON IN A CALCIUM SILICATE

机译：硅酸钙中五配位硅的结构表征

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摘要

IN silicate minerals formed at pressures typical of the Earth's crust, the silicon is usually coordinated by four oxygen atoms. In contrast, silicates formed at higher pressures, typical of the Earth's transition zone and lower mantle, contain predominantly six-coordinated silicon. Silicon coordinated by five oxygen atoms is not normally found as a structural element in crystalline phases, but is nevertheless believed to play a central role in many dynamic processes that occur in silicates. For example, pentacoordinate silicon is probably a component of aluminosilicate melts and glasses at mantle temperatures and pressures(1,2), where it will dominate their transport properties(3-6); it is also believe to act as an intermediate activated state during oxygen diffusion in silicate minerals(7,8). Here we report the complete structure determination of an inorganic crystalline silicate-CaSi2O5-containing SiO5 groups. Our results confirm the previous attribution(1,2,9) of peaks in the Si-29 NMR spectrum of this material to the presence of pentacoordinate silicon, and the detailed geometry that we determine for the SiO5 group should provide a firm basis for characterizing and quantifying the role of pentacoordinate silicon in silicate melts and glasses. [References: 24]
机译：在地壳典型压力下形成的硅酸盐矿物中，硅通常由四个氧原子配位。相反，在较高的压力下形成的硅酸盐通常是六配位硅，这是地球过渡区和下地幔的典型特征。由五个氧原子配位的硅通常不会在晶相中被发现是结构元素，但据信在硅酸盐中发生的许多动力学过程中起着核心作用。例如，五配位硅可能是地幔温度和压力下铝硅酸盐熔体和玻璃的组成部分（1,2），它将主导其传输性能（3-6）。它也被认为在硅酸盐矿物中的氧扩散过程中起中间活化态的作用（7,8）。在这里，我们报告了含有无机结晶硅酸盐-CaSi2O5的SiO5基团的完整结构测定。我们的结果证实了该材料在Si-29 NMR光谱中峰的先前归属（1,2,9）与五配位硅的存在有关，并且我们确定的SiO5基团的详细几何形状应为表征提供坚实的基础并量化五配位硅在硅酸盐熔体和玻璃中的作用。 [参考：24]

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