CRYSTAL-STRUCTURE DETERMINATION OF A STRO NTIUM HYDRIDE IMIDE NITRIDE- SR-2(H)N SRNH RESP SR-2(D)N/SRND - BY X-RAY, NEUTRON, AND SYNCHROTRON-RADIATION/

Strontium reacts with nitrogen and hydrogen resp. deuterium under well defined conditions to a phase containing hydride, imide and nitride i ons. Sr is evaporated at 1000 degrees C. The Sr vapor reacts with N-2 and H-2 resp. D-2 (p(N-2) = p(H-2/D-2) = 50 mbar) in the gas phase. Th e product crystallizes as orange-yellow resp. black needles at 800 deg rees C. Neither X-ray single crystal nor X-ray and neutron powder diff raction data led to an acceptable model for the crystal structure. A h igh resolution diffraction experiment with synchrotron radiation gave the needed informations: Splitting of reflections led to a model in R3 m with a = 3.870(1) Angstrom and c = 18.958(3) Angstrom. Further split reflections indicate, that the crystals contain areas where SrNH is a second phase besides Sr-2(PI)N. Neutron diffraction data (measured at 2 K, 10 K, 300 K and 505 K) were interpreted by a two phase model wit h Sr-2(D)N/SrND: In a slightly distorted cubic close packing of Sr-ato ms hydride and nitride resp. imide ions occupy each by one third octah edral sites fully and in an ordered way.