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多型性是结构化学和晶体学的一个极重要的现象和研究领域.许多密堆积或层状结构的无机化合物、页硅酸盐和矿物,例如SiC,ZnS,CdI_2,PbI_2,二硫族化合物、钙钛矿型结构化合物、粘土、云母,等等,都呈现广泛的多型性,可形成众多的结构变体或多型体.某些化合物多型体的堆积周期可达数千埃.出现如此巨大的结构周期确是结构化学领域中很值得研究的问题.碳化硅是最典型的多型性化合物,到目前为止,已发现有157种多型体.其中,我们发现了共84种SiC的多型体,占总数的一半以上.我们用倒易点阵点间关系法发现两种新的碳化硅长周期六方多型体240H和294H.
Polymorphism is a very important phenomenon and research field in structural chemistry and crystallography.Many close-packed or lamellar structures of inorganic compounds, phyllosilicates and minerals such as SiC, ZnS, CdI 2, PbI 2, dichalcogenides , Perovskite type compounds, clays, micas, etc., exhibit a wide range of polymorphisms that can form numerous structural variants or polymorphs, and the accumulation period of certain compound polytypes can reach several thousand angstroms. The emergence of such a huge structural cycle is indeed a problem worthy of study in the field of structural chemistry.Crystalline silicon carbide is the most typical polymorphic compounds, so far, 157 polytype has been found, of which we found a total of 84 species SiC polytype, accounting for more than half of the total.We used reciprocal lattice point correlation method to discover two new silicon carbide long-period hexagonal polymorphs 240H and 294H.