  Ni2SiO4, Liebenbergite, is an example of a quasi-one-dimensional magnet made
up of frustrated corner sharing triangles of Ni2+ (S = 1) ions that propagate
parallel to the b axis. Ni2SiO4 is isostructural with olivine, a common mineral
of varying composition Fe2-xMgxSiO4, and is described in the orthorhombic space
group Pnma. A synthetic polycrystalline sample of Ni2SiO4 was studied using
constant wavelength powder neutron diffraction. Diffraction spectra were
collected above and below the antiferromagnetic ordering transition (TN ~ 34 K)
and were used to refine the atomic and magnetic structures of Ni2SiO4.
Corepresentational theory was used to determine the symmetry-allowed magnetic
structures after the Neel transition and the refned magnetic structure
evidences both ferromagnetic and antiferromagnetic inter-chain interactions,
and ferromagnetic intra-chain coupling. The competition between the magnetic
interactions can be seen in the canting of the moments away from a collinear
arrangement.
