Symmetry, Vol. 16, Pages 477: Determination of Na+ Cation Locations in Nanozeolite ECR-1 Using a 3D ED Method

1 month ago 21

Symmetry, Vol. 16, Pages 477: Determination of Na+ Cation Locations in Nanozeolite ECR-1 Using a 3D ED Method

Symmetry doi: 10.3390/sym16040477

Authors: Taylan Örs Irena Deroche Corentin Chatelard Mathias Dodin Raquel Martinez-Franco Alain Tuel Jean-Louis Paillaud

Until now, the comprehensive structural analysis of single crystals of zeolite ECR-1, an aluminosilicate with the EON topology, has been hindered owing to the submicron dimensions of the obtained crystals. Additionally, this zeolite, which is characterized by a topology comprising alternating periodic building units of MAZ and MOR layers, exhibits stacking faults that impede accurate refinement through the Rietveld method. In this report, we present, for the first time, the structure of ECR-1 elucidated by studying a nanocrystal with a significantly reduced number of stacking faults. The sample used was synthesized hydrothermally using trioxane as the organic structure-directing agent. The structure determination was conducted using precession electron diffraction (PED) at 103 K. Partial dehydration occurred owing to the high vacuum conditions in the TEM sample chamber. From the dynamical refinement (Robs = 0.097), 8.16 Na+ compensating cations were localized on six distinct crystallographic sites, along with approximately four water molecules per unit cell. Furthermore, a canonical Monte Carlo computational study was conducted to compare the experimental cationic distribution and location of water molecules with the simulation.

Read Entire Article