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

The dark green powder of Zr₅₀Sc₁₂O₄₃N₅₀ was produced from Zr₅₀Sc₁₂O₁₁₈ under a constant flow of ammonia. Zr₅₀Sc₁₂O₄₃N₅₀ crystallizes cubic with space group and in the C-M₂O₃ structure (bixbyite structure). The reaction path was followed by in situ X-ray diffraction and showed that the substitution of 3O²⁻ by 2N³⁻ 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 M₁₄X₂₆ and M₇X₁₂. 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 .