Fe2Si5N8: Access to Open-Shell Transition-Metal Nitridosilicates

Highly condensed nitridosilicates doped with Eu2+ or Ce3+ play an important role in saving energy by converting the blue light of (In,Ga)N-LEDs. Although nitridosilicates are known for great structural variety based on covalent anionic Si-N networks, elemental variety is restricted. Presenting a significant extension of the latter, this work describes a general access to open-shell transition-metal nitridosilicates. As a proof-of-principle, the first iron nitridosilicate, namely Fe2Si5N8, was prepared by exchanging Ca2+ in alpha-Ca2Si5N8 applying a FeCl2 melt (salt metathesis). The title compound was analyzed by powder X-ray diffraction, EDX, ICP-OES, combustion analysis, TG/DSC, Mossbauer spectroscopy and magnetic susceptibility measurements. Furthermore, the structure of alpha-Ca2Si5N8 was determined at 1073 and 1173 K confirming the anionic network of alpha-Ca2Si5N8 providing possible migration pathways for the ion-exchange reaction.