High pressure synthesis of polar and non-polar cation-ordered polymorphs of Mn2ScSbO6

摘要

Two new cation-ordered polymorphs of Mn2ScSbO6 have been synthesised at high-pressure. At 5.5 GPa and 1523 K Mn2ScSbO6 crystallizes in the Ni3TeO6-type structure with the polar R3 space group and cell parameters a = 5.3419 (5) angstrom and c = 14.0603 (2) angstrom. Below T-C = 42.0 K it exhibits ferrimagnetic order with a net magnetization of 0.6 mu(B) arising from unusual site-selective Mn/Sc disorder and is thus a potential multiferroic material. A double perovskite phase obtained at 12 GPa and 1473 K crystallizes in the nonpolar P2(1) monoclinic space group with cell parameters a = 5.2909 (3)angstrom, b = 5.4698 (3)angstrom, c = 7.7349 (5) angstrom and beta = 90.165 (6)degrees. Magnetization and neutron diffraction experiments reveal antiferromagnetic order below T-N = 22.3 K with the spins lying in the ac plane.