Synthesis, structural, magnetic and thermal properties of Mn₂As₂O₅, the first pyro-arsenite of a first-row transition metal

Author(s)

Magdalena Priestner, Gerald Singer, Matthias Weil, Reinhard Karl Kremer, Eugen Libowitzky

Abstract

Single crystals of manganese pyro-arsenite [systematic name: dimanganese(II) pentaoxidodiarsenate(III)], Mn2As2O5, were grown under hydrothermal conditions. Mn2As2O5 adopts a novel structure type as revealed by single crystal X-ray diffraction from a crystal twinned by pseudo-merohedry. The crystal structure comprises of five independent MnII sites (two located on inversion centres, three in general sites) and two pairs of [As2O5]4- pyro-anions made up from corner-sharing trigonal-pyramidal [AsO3] units in general positions. Four of the five MnII sites exhibit distorted octahedral [MnO6] coordination polyhedra whereas one has five oxygen ligands in a distorted square-pyramidal environment. The manganese-oxygen polyhedra and [As2O5]4- pyro-anions share corners and edges under formation of a three-dimensional network with channels extending along [001]. The 4s2 electron lone pairs at the AsIII atoms are stereochemically active and point into the centre of the channels. Results of Raman spectroscopic studies are in agreement with the structural features of the pyro-arsenite anion. Magnetic susceptibility measurements on a powder sample confirm all Mn atoms to be in oxidation state þ II. An antiferromagnetic ordering below 14.3 K occurs that most likely points to a magnetic structure supporting a weak ferromagnetic component (‘weak ferromagnetism’).

Organisation(s)

Department of Mineralogy and Crystallography

External organisation(s)

Technische Universität Wien, University of Natural Resources and Life Sciences, Max-Planck-Institut für Festkörperforschung

Journal

Journal of Solid State Chemistry

Volume

277

Pages

209-215

No. of pages

7

ISSN

0022-4596

DOI

https://doi.org/10.1016/j.jssc.2019.06.005

Publication date

09-2019

Peer reviewed

Yes

Austrian Fields of Science 2012

104026 Spectroscopy, 104011 Materials chemistry, 105113 Crystallography

Keywords

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Condensed Matter Physics, Ceramics and Composites, Materials Chemistry, Inorganic Chemistry, Physical and Theoretical Chemistry

Portal url

https://ucrisportal.univie.ac.at/en/publications/9089a607-d712-49e0-a1ad-62e00d94ae93