Structure solution from powder data of the hydrous layer silicate kanemite, a precursor of the industrial ion exchanger SKS-6
Vortmann, Sllke; Rius, Jordi; Marler, Bernd; Gies, Hermann
European Journal of Mineralogy Volume 11 Number 1 (1999), p. 125 - 134
published: Feb 11, 1999
manuscript accepted: Sep 21, 1998
manuscript received: May 14, 1998
ArtNo. ESP147051101014, Price: 29.00 €
Abstract The crystal structure of the mineral kanemite, NaH[Si2O5]*3H2O, has been solved by direct methods from integrated intensities of X-ray powder diffraction data and subsequently refined with the Rietveld technique. The layer silicate used for the structure solution was a highly ordered synthetic sample. Kanemite crystallizes in the orthorhombic space group Pbcn with cell parameters a = 4.946(1) Å, b = 20.510(1) Å, and c = 7.277(1) Å. The Rietveld refinement of the data set converged at χ2 = 1.06. The silicate anion in the structure is a single layer of Q3-[SiO4] tetrahedra building 6-membered rings (6MR) in chair conformation. The [Si-O]-groups of the layer point up and down alternately. The negative charge of the layer is compensated partially with protons and partially with an intercalated layer of octahedrally hydrated sodium cations. Although the interlayer bonding is constituted only by delocalized Coulombs interaction and weak hydrogen bridge bonds between the silanol end groups of the silicate layer and the hydrated sodium cations, the crystallinity of the material is good enough for a detailed cry stall ographic analysis.