Next Article in Journal
Assessment of Effects of Si-Ca-P Biphasic Ceramic on the Osteogenic Differentiation of a Population of Multipotent Adult Human Stem Cells
Previous Article in Journal
Origin of Activity and Stability Enhancement for Ag3PO4 Photocatalyst after Calcination
Open AccessArticle

On the Sr1−xBaxFeO2F Oxyfluoride Perovskites: Structure and Magnetism from Neutron Diffraction and Mössbauer Spectroscopy

1
Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (C.S.I.C.), Cantoblanco, E-28049 Madrid, Spain
2
Institute for Nuclear Research and Nuclear Energy (I.N.R.N.E.), Tsarigradsko Chaussee 72, BG-1784 Sofía, Bulgaria
3
Instituto de Catálisis y Petroleoquímica, Consejo Superior de Investigaciones Científicas (C.S.I.C.), Cantoblanco, E-28049 Madrid, Spain
*
Author to whom correspondence should be addressed.
Academic Editor: Lioz Etgar
Materials 2016, 9(12), 970; https://doi.org/10.3390/ma9120970
Received: 3 October 2016 / Revised: 18 November 2016 / Accepted: 22 November 2016 / Published: 29 November 2016
Four oxyfluorides of the title series (x = 0.00, 0.25, 0.50, 0.75) have been stabilized by topotactic treatment of perovskite precursors Sr1−xBaxFeO3−δ prepared by soft-chemistry procedures, yielding reactive materials that can easily incorporate a substantial amount of F atoms at moderate temperatures, thus avoiding the stabilization of competitive SrF2 and BaF2 parasitic phases. XRD and Neutron Powder Diffraction (NPD) measurements assess the phase purity and yield distinct features concerning the unit cell parameters’ variation, the Sr and Ba distribution, the stoichiometry of the anionic sublattice and the anisotropic displacement factors for O and F atoms. The four oxyfluorides are confirmed to be cubic in all of the compositional range, the unit cell parameters displaying Vergard’s law. All of the samples are magnetically ordered above room temperature; the magnetic structure is always G-type antiferromagnetic, as shown from NPD data. The ordered magnetic moments are substantially high, around 3.5 μB, even at room temperature (RT). Temperature-dependent Mössbauer data allow identifying Fe3+ in all of the samples, thus confirming the Sr1−xBaxFeO2F stoichiometry. The fit of the magnetic hyperfine field vs. temperature curve yields magnetic ordering TN temperatures between 740 K (x = 0.00) and 683 K (x = 0.75). These temperatures are substantially higher than those reported before for some of the samples, assessing for stronger Fe-Fe superexchange interactions for these specimens prepared by fluorination of citrate precursors in mild conditions. View Full-Text
Keywords: SrFeO3−δ; oxyfluoride; SrFeO2F; Sr0.5Ba0.5O2F; BaFeO2F; neutron diffraction; Mossbauer spectroscopy; antiferromagnetic structure SrFeO3−δ; oxyfluoride; SrFeO2F; Sr0.5Ba0.5O2F; BaFeO2F; neutron diffraction; Mossbauer spectroscopy; antiferromagnetic structure
Show Figures

Graphical abstract

MDPI and ACS Style

García-Ramos, C.A.; Retuerto, M.; Alonso, J.A. On the Sr1−xBaxFeO2F Oxyfluoride Perovskites: Structure and Magnetism from Neutron Diffraction and Mössbauer Spectroscopy. Materials 2016, 9, 970.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop