• Shikano, Masahiro
• Kobayashi, Hironori
• Yahia, Hamdi Ben

Abstract

<jats:title>Abstract</jats:title><jats:p>The new polymorph of Co<jats:sub>2</jats:sub>[PO<jats:sub>4</jats:sub>]F has been synthesized by a hydrothermal route. Its crystal structure was determined from single-crystal X-ray diffraction data. Co<jats:sub>2</jats:sub>[PO<jats:sub>4</jats:sub>]F crystallizes with the triplite-type structure, space group <jats:italic>C</jats:italic>2<jats:italic>/c</jats:italic>, <jats:italic>a</jats:italic>=12.856(2), <jats:italic>b</jats:italic>=6.4369(10), <jats:italic>c</jats:italic>=9.6742(16) Å, <jats:italic>β</jats:italic>=117.40(1)°, <jats:italic>V</jats:italic>=710.7(2) Å<jats:sup>3</jats:sup> and <jats:italic>Z</jats:italic>=8. The structure consists of a 3D-framework buildup of condensed PO<jats:sub>4</jats:sub> tetrahedra, and cobalt(II) polyhedra which form chains running along the [101] and [010] directions. The coordination of the cobalt cations and the connectivity between the cobalt polyhedra are not well defined due to the disorder of the fluoride anions which form zigzag chains along [001]. The theoretical ordering of the fluoride anions led to two different structural models, very similar to the triplite <jats:italic>Cc-</jats:italic>CoFe[PO<jats:sub>4</jats:sub>]F and the triploidite <jats:italic>P</jats:italic>2<jats:sub>1</jats:sub>/<jats:italic>c</jats:italic>-Co<jats:sub>2</jats:sub>[PO<jats:sub>4</jats:sub>]F, and in which the cobalt atoms are five and six coordinated.</jats:p>

Topics

• x-ray diffraction
• cobalt
• space group