The Na2−nHn[Zr(Si2O7)]∙mH2O Minerals and Related Compounds (n = 0–0.5; m = 0.1): Structure Refinement, Framework Topology, and Possible Na+-Ion Migration Paths

摘要: The Na2−nHn[Zr(Si2O7)]∙mH2O family of minerals and related compounds (n = 0–0.5; m 0.1) consist keldyshite, Na3H[Zr2(Si2O7)2], parakeldyshite, Na2[Zr(Si2O7)], synthetic Na2[Zr(Si2O7)]∙H2O. crystal structures these materials are based upon microporous heteropolyhedral frameworks formed by linkage Si2O7 groups ZrO6 octahedra with internal channels occupied Na+ cations H2O molecules. members the have been studied combination theoretical (geometrical–topological analysis, Voronoi migration map calculation, structural complexity calculation), empirical methods (single-crystal X-ray diffraction, microprobe Raman spectroscopy for parakeldyshite). It was found that keldyshite parakeldyshite same fsh topology, while Na2ZrSi2O7∙H2O is different has xat topology. in a 2-D system suitable Na+-ion migration. structure can be derived from + O2− ↔ OH− □ substitution mechanism, widespread postcrystallization processes hyperagpaitic rocks.