title: (237)Np Mössbauer effect study on NpFeAsO.
abstract: We report (237)Np Mössbauer measurements on NpFeAsO. The Np atoms were found to occupy only one crystallographic site. The value of the isomer shift (δ ∼ 9.1 mm s(-1) versus NpAl2) indicates a 5f(4) electronic configuration (Np(3+) ions). The magnetic ordering of the Np sublattice below 60 K is established and the saturated ordered magnetic moment is determined to be 1.73μB at 3.6 K. The unique set of hyperfine parameters exclude a modulated magnetic structure or spin waves on the Np site. The neptunium magnetic moments μNp are found to lie along the tetragonal c-axis.
authors.affiliation: European Commission, JRC, Institute for Transuranium Elements, Postfach 2340, 76125 Karlsruhe, Germany. Institute of Physical and Theoretical Chemistry, Technische Universität Braunschweig, Hans-Sommer-Str. 10, D-38106 Braunschweig, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Gaczyński
authors.forename: T
authors.initials: T
authors.lastname: Klimczuk
authors.forename: H
authors.initials: H
authors.lastname: Walker
authors.forename: R
authors.initials: R
authors.lastname: Springell
authors.forename: E
authors.initials: E
authors.lastname: Colineau
authors.forename: R
authors.initials: R
authors.lastname: Eloirdi
authors.forename: J-C
authors.initials: JC
authors.lastname: Griveau
authors.forename: R
authors.initials: R
authors.lastname: Caciuffo
mesh_terms: D001152:Arsenicals / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005290:Ferric Compounds / Q000737:chemistry*; D008280:Magnetics; D009405:Neptunium / Q000032:analysis* / Q000737:chemistry*; D015204:Spectroscopy, Mossbauer; D013696:Temperature
chemical_list: D001152:Arsenicals; D005290:Ferric Compounds; C000499:ferric oxide; D009405:Neptunium