Crystal structures of Sr-diphylloaluminosilicates synthesized from LTA and FAU zeolites

Abstract

Crystal structures of stoichiometric and non-stoichiometric Sr-diphylloaluminosilicate phases are solved and refined using X-ray powder diffraction (XRPD) data by Rietveld method in trigonal space group P over(3, -) c 1 (No. 165) and hexagonal space group P63/mcm (No. 193), respectively. The stoichiometric phase is synthesized from the Sr-LTA zeolite, whereas the non-stoichiometric phase is prepared from the Sr-FAU zeolite by thermal treatment. Structural models described in the space group P over(3, -) c 1 are refined to the agreement factors: Rexp = 3.32, Rp = 6.63, Rwp = 9.27, RB = 3.70 for Sr-diphylloaluminosilicateLTA and Rexp = 3.64, Rp = 7.06, Rwp = 10.1, RB = 3.76 for Sr-diphylloaluminosilicateFAU. Structural models described in the space group P63/mcm are refined to the agreement factors: Rexp = 3.32, Rp = 6.50, Rwp = 9.10, RB = 3.40 for Sr-diphylloaluminosilicateLTA and Rexp = 3.64, Rp = 6.92, Rwp = 9.90, RB = 3.55 for Sr-diphylloaluminosilicateFAU. Vacancies in the positions occupied by the Sr2+ ions are characteristic of the Sr-diphylloaluminosilicateFAU structure. © 2007 Elsevier Masson SAS. All rights reserved.