Ammonia nitridation synthesis and structural change of strontium cyanamide polymorphs

Abstract

Two strontium cyanamide polymorphs (trigonal low temperature phase and orthorhombic high temperature phase) were prepared by firing strontium acetate in ammonia flowing at 600-850°C. Trigonal low temperature phase irreversibly changed to orthorhombic high temperature phase by post annealing. The two structures differed in SrN6 octahedon linkage and (NCN)2- arrangement. The structural change was discussed in relation to repulsion between strontium cations and SrN6 octahedron linkage by corner or edge sharing.