K-paracelsian (KAlSi3O8·H2O) and identification of a simple building scheme of dense double-crankshaft zeolite topologies

• Main Authors: Cristian-R. Boruntea, Peter N. R. Vennestrøm, Lars F. Lundegaard
• Format: Article
• Language: English
• Published: International Union of Crystallography 2019-01-01
• Series: IUCrJ
• Subjects: K-paracelsian; dense double-crankshaft zeolite topologies; structure refinement; crystal engineering; inorganic porous solids; microporous materials
• Online Access: http://scripts.iucr.org/cgi-bin/paper?S2052252518016111

During screening of the phase space using KOH and 1-methyl-4-aza-1-azoniabicyclo[2.2.2]octane hydroxide (1-methyl-DABCO) under hydrothermal zeolite synthesis conditions, K-paracelsian was synthesized. Scanning electron microscopy, energy dispersive X-ray spectroscopy and ex situ powder X-ray diffraction analysis revealed a material that is compositionally closely related to the mineral microcline and structurally closely related to the mineral paracelsian, both of which are feldspars. In contrast to the feldspars, K-paracelsian contains intrazeolitic water corresponding to one molecule per cage. In the case of K-paracelsian it might be useful to consider it a link between feldspars and zeolites. It was also shown that K-paracelsian can be described as the simplest endmember of a family of dense double-crankshaft zeolite topologies. By applying the identified building principle, a number of known zeolite topologies can be constructed. Furthermore, it facilitates the construction of a range of hypothetical small-pore structures that are crystallo-chemically healthy, but which have not yet been realized experimentally.