Substitution, Eigenschaften und neue Strukturen silicatverwandter nitridischer Verbindungen
The thesis is addressing different aspects of the chemistry of silicate related nitridic compounds. One main focus was the investigation of the influence of substitution (cations, O/N, Si/Al, halides) on the material properties of the compounds. For this concern known compounds (nitridosilicates, sions, sialons) as well as a new class of compounds (oxonitridosilicate halides) were investigated. Very important for these investigations was the detailed characterisation of the synthesised compounds. In this context the establishment of an especially optimised microprobe technique has to be highlighted. The new technique allows the quantitative analyses of light elements as O, N, Cl and Si, Al, Br beside elements like Sr, Ba and the lanthanides. In addition a lot of different analytical tools were used to understand the crystal chemistry of the investigated systems, e.g. single-crystal x-ray analyses, powder neutron diffraction, XAS, EDX and spectroscopic methods, some of them also performed under high pressure. The second main focus of the work was the synthesis and characterisation of compounds with new crystal structures in the area of oxonitridosilicates, sions and sialons.