Crystal structure and magnetic properties of a new layered cobalt oxyselenide

✍ Scribed by Yayoi Fuwa; Makoto Wakeshima; Yukio Hinatsu

• Publisher: Elsevier Science
• Year: 2010
• Tongue: English
• Weight: 686 KB
• Volume: 150
• Category: Article
• ISSN: 0038-1098
• DOI: 10.1016/j.ssc.2010.06.016

✦ Synopsis

The crystal structure and magnetic properties of a new layered cobalt oxyselenide La 2 Co 2 O 3 Se 2 were investigated through powder X-ray diffraction, magnetic susceptibility, and specific heat measurements. This oxyselenide crystallizes in a tetragonal structure with space group I4/mmm which is isostructural with La 2 Fe 2 O 3 Se 2 . The lattice parameters were determined to be a = 4.0761 Å and c = 18.4488 Å.

The Co ion is six-coordinated by two oxide ions and four selenide ions, forming a CoO 2 Se 4 octahedron. On the other hand, the La ion is eight-coordinated by four oxide ions and four selenide ions, forming a LaO 4 Se 4 decahedron. The Co 2 OSe 2 monolayers consisting of face-sharing CoO 2 Se 4 octahedra and the La 2 O 2 bilayers consisting of edge, face-sharing LnO 4 Se 4 decahedra are stacked along the c-axis. The magnetic susceptibility and specific heat of La 2 Co 2 O 3 Se 2 indicate that the magnetic behavior of the Co 2+ ions is two-dimensional and reveal that a long-range antiferromagnetic ordering occurs below 220 K. The antiferromagnetic interaction between nearest neighbor Co 2+ ions is estimated to be J/k B ∼ -28 K.