Niedrigkondensierte Nitrido- und Oxonitridosilicate (English shop)

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The aim of this work was to synthesise new nitrido- and oxonitridosilicates. The main focus was on the synthesis of pure nitridosilicates and of compounds with a high molar N : O ratio. In addition, the starting materials were weighed in such a way that the molar Ln : Si ratio was in most cases between 1 : 1 and 2 : 1. This made it possible to prepare mainly compounds with a low degree of condensation.

The compounds were usually synthesised from the corresponding metals or metal nitrides and “silicon diimide” (Si4N7H5), in some cases with the addition of metal oxides or Aerosil® (SiO2).

All reaction mixtures were prepared in a glovebox and consistently handled with exclusion of oxygen. The reactions were carried out in a radio-frequency furnace operated under a nitrogen atmosphere at temperatures of about 1600 °C. These were classical solid-state reactions, some of which required long reaction times of more than 50 h.

The products were analysed and characterised by X-ray diffraction methods. Lanthanum-containing compounds were additionally investigated by NMR spectroscopy, and magnetic measurements were performed on cerium-containing compounds. Finally, MAPLE calculations were usually carried out in order to verify the results obtained.