title: Triangular exchange interaction patterns in K3Fe6F19: an iron potassium fluoride with a complex tungsten bronze related structure.
abstract: The synthesis and structural and magnetic characterizations of K3Fe6F19, a new iron potassium fluoride with a complex tungsten bronze related structure, are presented. This phase was found during the investigation of relatively low-temperature (600 °C) synthesis conditions of classical tetragonal tungsten bronze (TTB) fluorides and can be considered an intermediate that forms at this temperature owing to faster crystallization kinetics. The K3Fe6F19 compound has an orthorhombic structure (space group Cmcm (63), a = 7.6975(3) Å, b = 18.2843(7) Å, c = 22.0603(9) Å) related to the TTB one, where the perovskite cage is substituted by a large S-shaped channel simultaneously occupied by two potassium atoms. The magnetic structure, characterized by magnetization measurements on an oriented single crystal and powder neutron diffraction, is dominated by the presence of interconnected double stripes of antiferromagnetic triangular exchange interaction patterns alternately rotated in clock- and anticlockwise fashion. The magnetic order takes place in a wide temperature range, by increasing progressively the interaction dimensionality.
authors.affiliation: Dipartimento di Chimica, Università di Parma , Parco Area delle Scienze 17/A, 43124 Parma, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Mezzadri
authors.forename: Gianluca
authors.initials: G
authors.lastname: Calestani
authors.forename: Lara
authors.initials: L
authors.lastname: Righi
authors.forename: Chiara
authors.initials: C
authors.lastname: Pernechele
authors.forename: Massimo
authors.initials: M
authors.lastname: Solzi
authors.forename: Clemens
authors.initials: C
authors.lastname: Ritter