Iron valence in double-perovskite (Ba,Sr,Ca)2FeMoO6: isovalent substitution effect

Magnetic and magneto-transport properties of double perovskite Ba2−xSrxFeMoO6 system

“…This increased hybridization changes the valence state of Fe and Mo in the system. The mixed valence state of Fe and Mo in double perovskite A 2 FeMoO 6 has been already reported [10,11]. Nguyen et al [10] observed a valence state favoring majority of Fe II -Mo VI pair for double perovskite with large A-site cation (A ¼ Ba; Ba 2 FeMoO 6 ) while Fe III -Mo V pair is favorable for smaller A-site cation (A ¼ Sr; Sr 2 FeMoO 6 ).…”

Synthesis, structural and electrical characterizations of Sr2Fe1−xMxNbO6 (M=Zn and Cu) with double perovskite structure

“…Jurado and coworkers reported that Fe-containing perovskite oxides exhibited quite high oxide ionic and electronic conductivities [16], therefore many extensive researches are focused on Fe-containing perovskite compounds. Some new families of compounds based on the double perovskite structure are known, including (Ba/Sr/Ca) 2 FeMoO 6 [1,[17][18][19], Sr 2 FeReO 6 [20][21][22], Sr 2 FeSbO 6 [23], and (Ba/Sr/Ca) 2 FeNbO 6 etc [8,[23][24][25][26][27]. T. S. Irvine group reported that Sr 2 FeNbO 6 might be candidate for SOFC anode application if a film anode could be applied [8].…”

Conductivity and redox stability of new double perovskite oxide Sr1.6K0.4Fe1+x Mo1−x O6−δ (x = 0.2, 0.4, 0.6)

“…However, the presence of oxygen vacancies in the oxides may lead to enlarged lattice parameters. As the valency of these cations is known to alter with compositional modifications [29], it may be possible that the reduction in the molybdenum and iron ions could result in a modification of the valency of the B-site cations in Sr 1.6 K 0.4 Fe 1?x Mo 1-x O 6-d (x = 0.2, 0.4, 0.6) with formation of oxygen vacancies, resulting in the observed increase in the lattice parameter. Further investigation using Mössbauer spectroscopy could determine the feasibility of this supposition.…”