Re-investigation and correct symmetry of Ca3CoAl4O10

Abstract

A re-investigation of the crystal structure of tricalcium cobalt(II) tetraaluminate, Ca3CoAl4O10, using single-crystal X-ray diffraction data, revealed orthorhombic (Pbcm) symmetry. The present contribution corrects the results of a previous X-ray powder diffraction study [Vazquez et al. (2002). J. Solid State Chem. 166, 191–196] where this phase has been described in an unnecessarily low space-group symmetry (Pbc21). The compound belongs to the group of tetrahedral framework structures. The distribution of the aluminium and cobalt ions among the centres of the four different tetrahedra within the asymmetric unit has been studied in detail. Charge compensation is achieved by the incorporation of two symmetrically independent calcium ions located in voids of the tetrahedral framework. Ca3CoAl4O10 is isotypic with Ca3MgAl4O10.

Keywords

• crystal structure
• Ca3CoAl4O10
• redetermination
• symmetry analysis