Synthesis, Structure, and Properties of Anti-perovskite Nitrides Ca3MN, M=P,As,Sb,Bi,Ge,Sn, and Pb

A family of anti-perovskite nitrides of the formula Ca3MN, where M is a Group IV or a Group V element, is reported. Ca3BiN, synthesized by mixing and pressing powders of Ca3N2 and Bi into a pellet and subsequently heating the pellet at 1000 deg C in flowing, dry N2 gas, is prototypical of this family of compounds. The bismuth in Ca3BiN has an uncommon oxidation state of 3- as suggested by the properties (semiconducting and diamagnetic) of the compound. The anionic bismuth can be substituted for by other trivalent anions Sb3-, As3-, and P3- as expected. The structure of Ca3AsN and Ca3PN are distorted from the simple cubic anti-perovskite cell at room temperature because of the small size of As3- and P3-. More interestingly, Ca3N2 also reacts with Ge, Sn, and Pb at 1300 deg C to form similar anti-perovskites, resulting in metallic phases and the unusual open shell oxidation state of 3- for the Group IV elements.