Ab initio structure determination of a small-pore framework sodium stannosilicate

Area of Science:

• Materials Science
• Crystallography
• Solid-State Chemistry

Background:

• Sodium stannosilicates are a class of materials with potential applications in catalysis and ion exchange.
• Understanding the precise atomic arrangement is crucial for predicting and optimizing material properties.

Purpose of the Study:

• To determine the ab initio crystal structure of the small-pore framework sodium stannosilicate Na(2)SnSi(3)O(9).2H(2)O (AV-10).
• To characterize the structural, chemical, and thermal properties of AV-10.

Main Methods:

• Ab initio structure determination from powder X-ray diffraction (XRD) data.
• Comprehensive characterization including chemical analysis, SEM, various NMR spectroscopies ((29)Si, (119)Sn, (23)Na MAS NMR), TGA, and nitrogen adsorption isotherms.
• In situ studies of the dehydrated material using powder XRD, TGA, and (23)Na MAS NMR.

Main Results:

• The crystal structure of AV-10 was solved, revealing an orthorhombic unit cell (space group C222(1)).
• The framework consists of corner-sharing SnO(6) octahedra and SiO(4) tetrahedra, with SiO(4) tetrahedra forming helix chains interconnected by SnO(6) octahedra.
• Zeolitic water is reversibly lost, and the dehydrated material exhibits distinct structural and spectroscopic characteristics.

Conclusions:

• The detailed crystal structure of AV-10 provides fundamental insights into the arrangement of sodium stannosilicates.
• The reversible loss of zeolitic water suggests potential for applications requiring dynamic structural changes.
• The comprehensive characterization confirms the unique framework structure and properties of AV-10.