REFINEMENT OF THE STRUCTURE OF BOROLEUCITE, K(BSI2O6)

Potassium borosilicate, KBSi2O6, M(r) = 202.09, cubic, I43dBAR, a = 12.618 (4) angstrom, V = 2009.0 angstrom3, Z = 16, D(x) = 2.67 g cm-3, lambda(Mo Kalpha) = 0.71073 angstrom, mu = 14.7 cm -1, F(000) = 1600, T = 293 K, R = 0.038, wR = 0.051 for all 528 independent reflections. The model given by Ihara & Kamei [Yogyo Kyokai Shi (1980), 88, 32-35] and tetrahedral coordination of B atoms, have been confirmed. The structure is similar to that of cubic leucite [Peacor (1968). Z. Kristallogr. 127, 213-224] and consists of a framework of tetrahedra linked into four- and six-membered rings. The K atom is placed in a tunnel along [111]. The refinement of the occupation factors of K, Si and B atoms yields nearly ideal values corresponding to the chemical formula.