Response to reply on “Structural and magnetic behavior of the cubic oxyfluoride SrFeO2F studied by neutron diffraction”

AgFeOF2: A Fluorine-Rich Perovskite Oxyfluoride

“…The origin of the superstructure is not clear, but could be a partial anion order (to be discussed later) or a subtle but coherent octahedral tilting. Regarding the latter, SrFeO 2 F adopts an orthorhombic √2 × 2 × √2 unit cell, which is confirmed by both powder X-ray and neutron diffraction. ,, Note that unindexed small peaks observed in the SXRD pattern could not be described reasonably by superstructure peaks.…”

“…Numerous AB O 2 F perovskites ( A = K, Sr, Pb, etc., B = Ti, Mn, Fe, etc.) have been reported to date. − In contrast, Tl I Tl III OF 2 is the only example of AB OF 2 . AgFeOF 2 represents the first transition-metal oxyfluoride with F/O = 2.…”

“…Regarding the latter, SrFeO 2 F adopts an orthorhombic √2 × 2 × √2 unit cell, which is confirmed by both powder X-ray and neutron diffraction. 11,13,14 Note that unindexed small peaks observed in the SXRD pattern could not be described reasonably by superstructure peaks.…”

“…These features are partly related to the more ionic character of the F – anion, compared with the oxide anion. The perovskite structure affords the formation of several oxyfluorides with transition metals at the B -site, as found in KTiO 2 F, A NbO 2 F ( A = Na, K), Pb M O 2 F ( M = Sc, Mn), and A FeO 2 F ( A = Sr, − Pb, − Ba , ), and they are accessible via conventional solid-state reactions (e.g., A NbO 2 F), high-pressure reactions (e.g., KTiO 2 F and Pb M O 2 F), and topochemical fluorination reactions (e.g., A FeO 2 F).…”

Two-Dimensional Fluorine Distribution in a Heavily Distorted Perovskite Nickel Oxyfluoride Revealed by First-Principles Calculation

“…Many oxyfluorides (BaScO 2 F, KTiO 2 F, [Ba, Pb]­FeO 2 F, , AgFeOF 2 , and KNbO 2 F) are classified into cubic crystal systems. The displacement of oxygen atoms from the ideal cubic structure in orthorhombic SrFeO 2 F is small (0.2 Å), which raised doubts about SrFeO 2 F being cubic or orthorhombic. − Since the anion sites in cubic and nearly cubic perovskite structures have similar chemical properties and O 2– and F – own close ionic radii (140 and 133 pm, respectively), oxygen and fluorine atoms have no preference to orderings or inhomogeneous distributions.…”