title: La3Ni2SbO9: a relaxor ferromagnet.
abstract: A polycrystalline sample of La3Ni2SbO9 has been synthesized using a standard ceramic method and characterized by neutron diffraction and magnetometry. The compound adopts a monoclinic, perovskite-like structure with space group P2(1)/n and unit cell parameters a = 5.0675(1), b = 5.6380(1), c = 7.9379(2) Å, β = 89.999(6)° at room temperature. The two crystallographically distinct six-coordinate sites are occupied by Ni(2+) and a disordered distribution of Ni(2+)/Sb(5+), respectively; the Ni(2+) and Sb(5+) cations occupy the disordered site in a 1:2 ratio. Both ac and dc magnetometry indicate the presence of a spontaneous magnetization below 105 K. A magnetization of 1.5 μB per formula unit was measured at 2 K in a field of 40 kOe. However, no magnetic scattering was observed in neutron diffraction data collected at 5 K. It is proposed that, as a consequence of the cation disorder, La3Ni2SbO9 behaves as a relaxor ferromagnet, analogous to a relaxor ferroelectric, with magnetic domains too small to be detected by neutron diffraction forming below 105 K.
authors.affiliation: Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK. peter.battle@chem.ox.ac.uk
authors.forename: Peter D
authors.initials: PD
authors.lastname: Battle
authors.forename: Sophie I
authors.initials: SI
authors.lastname: Evers
authors.forename: Emily C
authors.initials: EC
authors.lastname: Hunter
authors.forename: Mark
authors.initials: M
authors.lastname: Westwood