Abstract

Boggsite, a new zeolite from the Goble area, Oregon, has unit-cell contents Ca7.8Na2.9Al18.3Si77.5O192·70H20, an orthorhombic unit cell with a = 20.236(2), b = 23.798(1), c = 12.798(1) Å, and space group Imma (74). The four-connected 3-D net linking the tetrahedral vertices has 4-, 5-, 6-, 10- and 12-rings. Three-connected 2-D nets of the gmelinite and ferrierite types occur respectively in the bc and ac planes. The topology of the 3-D net is obtained by replacing 29 of the edges of the gmelinite net by pentasil chains found in the silicalite/ZSM-5/ZSM-11 family of synthetic microporous materials. Each 12-ring channel along a has offset 10-ring windows into left and right channels along b. Correspondingly, each 10-ring channel is connected to left and right 12-ring channels to yield 3-D access. Each 12-ring is nearly circular with a free diameter between framework oxygens (assumed radius 1.35 Å) of 7.4 by 7.2 Å. Two bifurcated 4-rings reduce the free diameter of each 10-ring (5.2 by 5.1 A) to approximately that for a near-circular 9-ring. A unique assignment of Ca, Na, and H20 to the broad irregular peaks in the channels was not achieved. A highly disordered ionic solution that lacks systematic bonding to the silica-rich framework is indicated. The good correlation between mean T-O distance and T-O-T angle indicates Si,Al disorder over all sites.

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