  The complex perovskite Ba2CoTeO6 (BCTO) has been synthesised, and the crystal
structure and magnetic properties have been investigated using a combination of
X-ray and neutron powder diffraction, electron microscopy and dielectric,
calorimetric and magnetic measurements. It was shown that at room temperature
this compound adopts the 6L-trigonal perovskite structure, space group P-3m (N
164) (a= 5.7996(1){\AA}, c=14.2658(3){\AA}). The structure comprises dimers of
face-sharing octahedra as well as octahedra which share only vertices with
their neighbours. A long-range antiferromagnetically ordered state has been
identified from neutron diffraction and magnetic studies. The magnetic
diffraction peaks were registered below the magnetic transition at about 15 K
and a possible model for the magnetic structure is proposed. The structural and
magnetic features of this compound are discussed and compared with those of
other Co-based quaternary oxides adopting the perovskite structure.

Materials Science