Distribution of phosphorus and arsenic atoms in the solid solution Sn_(24)As_xP_(19.3-x)I8 with thestructure of clathrate-I

摘要

The solid solution Sn_(24)As_xP_(19.3-x)I8 in the range of compositions x from 0 to 16 wassynthesized. The crystal structure was refined for seven compositions of the solid solution at -100°C.All samples crystallize in the cubic space group Pm3n with the unit cell parameters a = 10.9358(2)—11.1495(2) A and belong to the clathrate-I structure type. The distribution of the phosphorus andarsenic atoms over two independent crystallographic positions within the clathrate framework wasanalyzed. The difference in the structure of the substituted clathrates with the cationic and anionicclathrate frameworks is considered.