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P2_1ca空间群的斜方辉石晶体,其可能的拓扑结构中包含了对称上不等同的4种四面体单链和4种八面体配位位置。八面体层按++--的顺序重复排布。四面体链的旋转方式可有16种不同的组合,但其中有12种违反Thompson的均势法则;另4种两两等价,构成以a轴为极轴的两对异极反取向关系的结构对。它们的O链与S链之比分别为3:1和1:3。从晶体化学角度来看,最可能的结构是3:1的结构。此结构中对称上和拓扑学上均不等同的两列Ⅰ形单元的构成为: ·O+O·O—O··O+S·O—S· 或 +O·S-O·S+ +O·O-O·O+两种M_2位置的构型分别为P·P和P·N。互为异极反取向关系的结构对之间可形成以(100)为双晶面的补足双晶,其双晶界面正好等于一个倒转界面。此外,当Mg:Fe原子比为1:1或3:1时,都有可能出现有序结构。
The possible topological structure of orthopyroxene crystals in the P2_1ca space group includes four tetrahedrally symmetric and four tetrahedrally symmetric tetrahedra and four octahedral coordination sites. The octahedral layers are arranged in the order ++. There are 16 different combinations of tetrahedral chain rotation methods, but 12 of them violate the Thompson’s law of equilibrium. The other four are equivalently two-by-two and form the structure of two pairs of antiparallel relations with the a axis as the polar axis Correct. Their O and S chain ratios are 3: 1 and 1: 3, respectively. From the crystallographic point of view, the most likely structure is a 3: 1 structure. The two symmetric and topologically I-shaped elements in this structure are: O + O.0-O-O + S-O-S or + O-SO.S + + O The configurations of OO · O + and M_2 are P · P and P · N, respectively. Complementary bimorphs whose (100) is a bimodal surface can be formed between the structural pairs that are oppositely opposite in polarity, and the bimodal interface is exactly equal to an inverted interface. In addition, when Mg: Fe atomic ratio of 1: 1 or 3: 1, there may be ordered structure.