Crystal structure of R3Si1.75Se7 (R - 1.5 YÂ + 1.5 La)

The existence of the new quaternary compound R3Si1.75Se7 (R - 1.5 Y + 1.5 La) was established. Its crystal structure was studied by X-ray powder method (space group P63, Pearson symbol hР24-1.44, a = 1.05968(2) nm, c = 0.59995(2) nm, RI = 0.0414). Rare-earth atoms in the structure of this compound are localized in trigonal prisms with two additional atoms, SiIV atoms center tetrahedra, and SiII atoms lie in octahedra. Quantum chemical simulation of separate fragments of the structure of this mixed selenosilicate (II, IV) was performed.