New isoformula potassium borosilicates with different zeolite frameworks: Monoclinic centrosymmetric boroleucite K(BSi)O and chiral KBSiO.

Belokoneva, E. L.; Dimitrova, O. V.; Stefanovich, S. Yu.

The structures of new isoformula potassium borosilicates, obtained under hydrothermal conditions, namely, the monoclinic modification of the cubic boroleucite K(BSi)O (space group P2/ a), which was previously unknown, and chiral KBSiO (space group P222)) are studied. A framework is formed both in the monoclinic and orthorhombic new structure in which each two tetrahedra share a vertex, as is typical of silicate frameworks. Since the two compounds have the same chemical formula, they could be spoken of as polymorphic modifications, but they are essentially different in structure: in the orthorhombic phase, the B and Si atoms are distributed over the tetrahedra in an ordered fashion, whereas B together with Si occupy statistically all tetrahedra in the monoclinic modification of boroleucite. The frameworks of both compounds are similar, although the framework is slightly denser in the orthorhombic borosilicate. Large rings consisting of six, seven, or eight tetrahedra determine the zeolite type of the frameworks, whose voids accommodate K atoms.

ZEOLITES; SILICATE minerals; ATOMS; PHYSICAL & theoretical chemistry; TETRAHEDRA

Crystallography Reports, 2010, Vol 55, Issue 4, p575

1063-7745

Academic Journal

10.1134/S1063774510040073