Synthesis and Characterization of Ba[CoSO]: Magnetic Complexity in the Presence of Chalcogen Ordering

Martin Valldor*, Ulrich K. Rößler, Yurii Prots, Chang Yang Kuo, Jen Che Chiang, Zhiwei Hu, Tun Wen Pi, Rüdiger Kniep, Liu Hao Tjeng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Barium thio-oxocobaltate(II), Ba[CoS2/2O2/2], was synthesized by the reaction of equimolar amounts of BaO, Co, and S in closed silica ampoules. The title compound (Cmcm, a=3.98808(3), b=12.75518(9), c=6.10697(4)Å) is isostructural to Ba[ZnSO]. The use of soft X-ray absorption spectroscopy confirmed that cobalt is in the oxidation state +2 and tetrahedrally coordinated. Its coordination consists of two sulfur and two oxygen atoms in an ordered fashion. High-temperature magnetic susceptibility data indicate strong low-dimensional spin-spin interactions, which are suggested to be closely related to the layer-type crystal structure and perhaps the ordered distribution of sulfur and oxygen. Antiferromagnetic ordering below TN=222K is observed as an anomaly in the specific heat, coinciding with a significant lowering of the magnetic susceptibility. Density functional theory calculations within a generalized-gradient approximation (GGA)+U approach identify an antiferromagnetic ground state within the square-like two-dimensional layers of Co, and antiferromagnetic correlations for nearest and next nearest neighbors along bonds mediated by oxygen or sulfur. However, this magnetic state is subject to frustration by relatively strong interlayer couplings. Anionic superstructure: An ordered distribution of chalcogen atoms is found in the crystal structure of Ba[CoSO] (see figure). Strong magnetic couplings between the high-spin Co2+ are observed far above the antiferromagnetic ordering temperature, at about 222K.

Original languageEnglish
Pages (from-to)10821-10828
Number of pages8
JournalChemistry - A European Journal
Volume21
Issue number30
DOIs
StatePublished - 1 Jul 2015

Keywords

  • anions
  • chalcogens
  • cobalt
  • density functional calculations
  • magnetic properties
  • X-ray absorption spectroscopy

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