Zr 50 Sc 12 O 43 N 50 and Zr 3 Sc 4 N 8 – Synthesis, Neutron Powder Diffraction and Raman Spectroscopy

The nitridation of Zr 50 Sc 12 O 118 (Zr 0.807 Sc 0.193 O 1.90 ), an anion deficient fluorite related compound, with ammonia yields at 1100 °C a green product with composition Zr 1.613 Sc 0.387 O 1.387 N 1.613 . This compound crystallizes cubic in space group $Ia{\bar 3}$ ( a = 1007.8(5) pm) and is isostructural to Bixbyite with statistical distribution of Zr/Sc at the cation and of O/N at the anion sites. These are the results of Rietveld refinements from a powder neutron diffraction experiment. If Zr 3 Sc 4 O 12 (Zr 0.429 Sc 0.571 O 1.714 ), an educt with another Zr/Sc ratio, is nitridated with ammonia the reaction path shows again the formation of a compound with a bixbyite structure, but finally at 1200 °C a red nitride with the composition Zr 3 Sc 4 N 8 (Zr 0.375 Sc 0.5 N) is formed. This compound has a cation deficient NaCl type structure (space group is $Fm{\bar 3}m$ ) with a = 452.8(1) pm. Neutron diffraction revealed again no ordering on the cation sites. Both compounds show an unperturbed N≡N stretching frequency in their Raman spectrum at 2327 cm −1 . Zr 3 Sc 4 N 8 exhibits at 1552 cm −1 a second sharp line which was assigned to a N 2 2− moiety.