High-Temperature High-Pressure Synthesis of the Highly Condensed Nitridophosphates NaP4N7, KP4N7, RbP4N7, and CsP4N7 and Their Crystal-Structure Determinations by X-ray Powder Diffraction

Novel highly condensed nitridophosphates MP4N7 have been obtained by the reaction of the respective azides MN3 (M = Na, K, Rb, or Cs) with P3N5 under high-temperature high-pressure conditions in a belt apparatus (structure of NaP4N7 depicted). Under normal pressure nitridophosphates as well as P3N5 decompose above 900 °C under evolution of N2. However under these specific reaction conditions the thermal stability of the PN compounds has been raised by more than 1000 °C, thus yielding a good crystallization of the products.