Ni3TeO6--a collinear antiferromagnet with ferromagnetic honeycomb planes.

We report a comprehensive study of magnetic properties of Ni(3)TeO(6). The system crystallizes in a noncentrosymmetric rhombohedral lattice, space group R3. There are three differently coordinated Ni atoms in the unit cell. Two of them form an almost planar honeycomb lattice, while the third one is placed between the layers. Magnetization and specific heat measurements revealed a single magnetic ordering at T(N) = 52 K. Below T(N) the susceptibility with the magnetic field parallel to the c axis drops towards zero while the perpendicular susceptibility remains constant, a characteristic of antiferromagnetic materials. Neutron diffraction confirmed that the system is antiferromagnet below T(N) with ferromagnetic ab planes stacked antiferromagnetically along the c axis. All Ni moments are in the S = 1 spin state and point along the c axis.