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 Ia3¯ and a=1009.254(3)pm 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 M14X26M14X26 and M7X12M7X12. 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 Zr50Sc12O43N50 to Zr50Sc12O118 on air at a heating rate of 2 K.Figure optionsDownload as PowerPoint slide