Increased Synthetic Control-Gaining Access to Predicted Mg sub(2)Si sub(5)N sub(8) and beta -Ca sub(2)Si sub(5)N sub(8)

Nitridosilicates represent an intriguing class of materials and are typically made up of highly condensed tetrahedral network structures. Alkaline-earth nitridosilicates emerged as unique host materials for Eu super(2+) doped luminophores which found broad application in phosphor-converted (pc)-LEDs. In contrast to common strategies of preparing nitridosilicates by bottom-up syntheses, we have now succeeded to post-synthetically design nitridosilicates by ion exchange in metal halide melts. We describe the syntheses of hitherto unknown but predicted alkaline-earth nitridosilicates, Mg sub(2)Si sub(5)N sub(8) and beta -Ca sub(2)Si sub(5)N sub(8). Both compounds were obtained by ion exchange starting from pre-synthesized nitridosilicates. Insitu investigations of the ion-exchange process show that the Si-N network topology remains preserved. Therefore the reaction offers a significant increase of synthetic control with respect to classical bottom-up syntheses.Original Abstract: Gezielter Austausch: In Nitridosilicat-Festkorpern sind Kationen in hoch kondensierten anionischen Tetraedernetzwerken eingebettet. Durch eine neue Synthesemethode gelingt der Austausch dieser Kationen unter Geruesterhaltung, was eine kontrollierte Syntheseplanung in der Nitridosilicatchemie ermoglicht. Die vorhergesagten Verbindungen Mg sub(2)Si sub(5)N sub(8) und [beta]-Ca sub(2)Si sub(5)N sub(8) waren auf diese Weise zugaenglich.