| dc.description |
The fine details of the crystal structure of have been determined from a high-resolution neutron diffraction study at room temperature. The powder sample, showing an excellent crystallinity, was prepared by topotactic reduction of in the presence of Zr. The unit cell can be described as a monoclinic superstructure of perovskite ( is the edge of the ideal perovskite), and contains one-dimensionally infinite chains of flattened octahedra running parallel to the c axis, with square planar units connecting the octahedra chains. Bond valence calculations are consistent with divalent Ni cations in both coordination polyhedra. Neutron diffraction experiments reveal 3D magnetic ordering below K. A magnetic structure with S = 1 moments antiferromagnetically coupled along the chains parallel to the c axis is proposed, and the absence of magnetic moments at the units is also discussed. |
