Zirconium scandium oxide nitrides: Formation and decomposition followed in situ by XRD and thermal analysis

The dark green powder of Zr 50Sc 12O 43N 50 was produced from Zr 50Sc 12O 118 under a constant flow of ammonia. Zr 50Sc 12O 43N 50 crystallizes cubic with space group Ia 3 ¯ and a = 1009.254 ( 3 ) pm in the C– M 2O 3 structure (bixbyite structure). The reaction path was followed by in situ X-ray diffraction and showed that the substitution of 3O 2− by 2N 3− generates additional vacancies on the anion sites in the fluorite basis structure. On the way to the bixbyite structure time- and temperature-controlled X-ray diffractograms revealed the known fluorite-related superstructures (i.e. the vacancy distribution) for the compositions M 14 X 26 and M 7 X 12 . The reverse process, i.e. the oxidation of the oxide nitride was followed in DTA/TG experiments exhibiting the different vacancy orderings at 420, 500 and 520 ∘ C . TG and DTA for the reoxidation of Zr 50Sc 12O 43N 50 to Zr 50Sc 12O 118 on air at a heating rate of 2 K.