Synthesis and Crystal Structure of SrC2

Polycrystalline SrC2 of high purity was prepared by the reaction of elemental strontium with graphite at temperatures of about 970 K. The known tetragonal room-temperature modification (I4/mmm, Z=2) was confirmed by synchrotron powder investigations, which revealed a strong anisotropic peak broadening. Temperature-dependent X-ray powder investigations resulted in a first-order phase transition to a cubic high-temperature modification (Fm m, Z=4) at about 700 K. Below room temperature a monoclinic modification (C2/c, Z=4), which is isotypic to the crystal structure of ThC2 at room temperature, was found.