Degree of order and redox balance in B-site ordered double-perovskite oxides, Sr2MMoO6−δ (M=Mg, Mn, Fe, Co, Ni, Zn)

We have investigated a series of double-perovskite oxides Sr2MMoO6−δ (M=Mg, Mn, Fe, Co, Ni, Zn) for redox stability, oxygen content and crystal structure. Phases with M=Co, Ni and Zn were found to be oxygen-stoichiometric and stable under oxidizing conditions, whereas those with M=Mn and Fe were oxygen-deficient and stable under reducing conditions. The M=Mg phase is stable both under reducing and oxidizing conditions, showing variable oxygen contents within 0.00≤δ≤0.04 depending on the annealing conditions. Structural data indicate somewhat depressed values for the degree of M/Mo cation order and also evidence of electron transfer from MII to MoVI for M=Mn, Fe and Co.

Graphical abstractA series of Sr2MMoO6-δ compounds with M=Mg, Mn, Fe, Co, Ni and Zn is investigated for their crystal structure, redox stability and precise oxygen content in order to address systematically the questions concerning the cation (dis)order, oxygen (non)stoichiometry and valence mixing in B-site ordered double-perovskite oxides.Figure optionsDownload full-size imageDownload as PowerPoint slide