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An Ordered Alite Cement Clinker Phase (Ca3SiO5, aP162) from Flux Synthesis
Zeitschrift für anorganische und allgemeine Chemie ( IF 1.1 ) Pub Date : 2021-09-18 , DOI: 10.1002/zaac.202100202
André Utrap 1 , Markus R. P. Pielmeier 2 , Tobias Lange 3 , Torben Gädt 4 , Tom Nilges 5
Affiliation  

Calcium silicates are the main components in cement clinkers. Alite, the nesosilicate or island silicate Ca3SiO5, also named C3S in cement chemistry notation, represents the main phase in Portland cement clinkers. Due to the metastability of Alite at room temperature, quenching from high temperatures is mandatory for phase preservation and impurities are important structure directing factors. Those two aspects result in a plethora of published polymorphs. Many Alite polymorphs described in the literature are characterized by various degrees of disorder within the Si−O substructure which is a direct consequence of afore mentioned features (i. e. quenching and presence of impurities). Here we report on the CaCl2-flux mediated synthesis and structural characterization of an aP162 Alite featuring a fully-ordered [SiO4] tetrahedron substructure. The orientation of the [SiO4] tetrahedron substructure is discussed based on the Nishi and Takéuchi nomenclature and is equivalent to the Golovastikov model reported in 1975. Rietveld analyses of a synthetic clinker and three commercial CEM I clinker substantiate that the aP162 model can successfully be applied for clinker phase analysis. Besides the structural characterization, quantum chemical band structure calculations based on Density Functional Theory methods illustrate the expected electrically isolating character of Ca3SiO5.

中文翻译:

来自助熔剂合成的有序 Alite 水泥熟料相 (Ca3SiO5, aP162)

硅酸钙是水泥熟料的主要成分。Alite,即新硅酸盐或岛状硅酸盐 Ca 3 SiO 5,在水泥化学符号中也称为 C 3 S,代表波特兰水泥熟料中的主要相。由于 Alite 在室温下的亚稳态,高温淬火对于相保持是强制性的,杂质是重要的结构导向因素。这两个方面导致了大量已发表的多晶型物。文献中描述的许多 Alite 多晶型物的特征在于 Si-O 亚结构内的不同程度的无序,这是上述特征(即淬火和杂质的存在)的直接结果。在这里,我们报告了 CaCl 2具有完全有序 [SiO 4 ] 四面体亚结构的aP 162 Alite 的-flux 介导的合成和结构表征。[SiO 4 ] 四面体亚结构的取向是根据 Nishi 和 Takéuchi 命名法讨论的,相当于 1975 年报道的 Golovastikov 模型。 Rietveld 对合成熟料和三种商业 CEM I 熟料的分析证实aP 162 模型可以成功应用于熟料物相分析。除了结构表征之外,基于密度泛函理论方法的量子化学能带结构计算说明了 Ca 3 SiO 5的预期电隔离特性。
更新日期:2021-11-12
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