K_8Gd_3Si_(12)O_(32)Cl ? 2H_2O, a New Member of the Family of Porous Silicates with K and RE Elements

摘要

Crystals of K_8Gd_3Si_(12)O_(32)Cl ? 2H_2O (space group P1), a new member of the family of porous silicates containing rare earths, are obtained under hydrothermal conditions. The structure retains the main features of the family in which original one-story layers of Si-tetrahedra formed by 6-membered rings of two types and large-in-diameter 8-membered and 12-membered rings are bound by Gd-octahedra to form a framework. Large pores in the interlayer space of the mixed framework are filled with K~+ ions. The penetration of Cl~– ions from a concentrated mineralizing solution into the centers of the eight-membered rings of the layer corroborates the ion-exchanging properties of the crystals of this structural type. The filling of rings and pores of different types in different members of the family by K~+ and Cl~– ions, hydroxyl groups, and water molecules is analyzed.