Crystal structure and magnetism in MnSb2O6: Incommensurate long-range order

MnSb2O6 was investigated by neutron diffraction and magnetic susceptibility techniques. The structure was trigonal, space group P321, a = 8.8011(3) Å, c = 4.7241(1)Å. Low-temperature neutron data gave no evidence of structural change down to 14 K. Inverse susceptibility data show a deviation from Curie-Weiss behavior below 200 K and the magnetization shows a maximum at 12 K associated with the onset of three-dimensional order. A Curie-Weiss law fit of the susceptibility data above 200 K gave an Mn2+ moment of 5.76(1) μB. The ordered magnetic structure as determined by neutron diffraction was incommensurate with the nuclear lattice and could be described by a propagation vector τ = (0.013, 0.013, 0.179) in reciprocal lattice units. Measured magnetic moments below Tc gave an extrapolated zero point moment of 4.6 μB for Mn2+ and critical parameters β = 0.31(2) and Tc = 11.92(5) K.