Synthesis and temperature-dependent structure property relations of mullite-type tin(II) compounds

Abstract

Within the scope of this dissertation, precursors for O8 mullite-type phases and the phases themselves were synthesized and studied. Due to unforeseen results, an investigation of dolomite-type compounds is included in this work. As the investigation of newly synthesized mullite-type compounds was the main part of this dissertation, the remaining part concerns this structure type. To investigate the influence of the lone electron pair (LEP) of Sn2+ on the structure and the difference to the influence of the LEP of Pb2+, different SnMBO4 (M = Al, Ga, Cr, and V) are synthesized by a conventional solid-state synthesis in sealed quartz tubes (chapter 2 - 5). Rietveld refinement of X-ray powder diffraction data indicates that all compounds crystallize in the orthorhombic space group Pnam, where the edge-sharing MO6 octahedra form an infinite chain along the crystallographic c axis and are interconnected by trigonal planar BO3 groups as well as square pyramidal SnO4 groups. To measure the strength of the stereochemical activity of the LEP, Wang-Liebau eccentricity (WLE) parameter was calculated from the structural data which led to a highly influenced structure. Further investigations were done to consolidate the structural features with Sn Mössbauer, solid state NMR, Raman, IR, and UV/Vis spectroscopic measurements.