MnSnTeO: A Chiral Antiferromagnet Prepared by a Two-Step Topotactic Transformation.

MnSnTeO, a new chiral antiferromagnet, was prepared both by topotactic transformation of the metastable rosiaite-type polymorph and by direct synthesis from coprecipitated hydroxides. Its structure and its static and dynamic magnetic properties were studied comprehensively both experimentally (through X-ray and neutron powder diffraction, magnetization, specific heat, dielectric permittivity, and ESR techniques) and theoretically (by means of density functional theory (DFT) calculations within the spin-polarized generalized gradient approximation). MnSnTeO is isostructural with MnSbO (space group 321) and does not show any structural transition between 3 and 300 K.

PbMnTeO: a chiral quasi 2D magnet with all cations in octahedral coordination and the space group problem of trigonal layered AMTeO.

Antiferromagnetic PbMnTeO6, also known as mineral kuranakhite, has been reported recently to have all three cations in trigonal prismatic coordination, which is extremely unusual for both Mn(4+) and Te(6+). In this work, the phase was reproduced with the same lattice parameters and Néel temperature TN = 20 K. However, powder neutron diffraction unambiguously determined octahedral (trigonal antiprismatic) coordination for all cations within the chiral space group P312.

Preparation and characterization of metastable trigonal layered MSbO phases (M = Co, Ni, Cu, Zn, and Mg) and considerations on FeSbO.

MSbO compounds (M = Mg, Co, Ni, Cu, Zn) are known in the tetragonal trirutile forms, slightly distorted monoclinically with M = Cu due to the Jahn-Teller effect. In this study, using a low-temperature exchange reaction between ilmenite-type NaSbO and molten MSO-KCl (or MgCl-KCl) mixtures, these five compositions were prepared for the first time as trigonal layered rosiaite (PbSbO)-type phases. Upon heating, they irreversibly transform to the known phases via amorphous intermediates, in contrast to previously studied isostructural MnSbO, where the stable phase is structurally related to the metastable phase.

An unusual high-spin ground state of Co3+ in octahedral coordination in brownmillerite-type cobalt oxide.

The crystal and magnetic structures of brownmillerite-like Sr(2)Co(1.2)Ga(0.8)O(5) with a stable Co(3+) oxidation state at both octahedral and tetrahedral sites are refined using neutron powder diffraction data collected at 2 K (S.

Temperature evolution of sodium nitrite structure in a restricted geometry.

The NaNO2 nanocomposite ferroelectric material in porous glass was studied by neutron diffraction. For the first time, the details of the crystal structure including positions and anisotropic thermal parameters were determined for the solid material, embedded in a porous matrix, in ferro- and paraelectric phases. It is demonstrated that in the ferroelectric phase the structure is consistent with bulk data, but above transition temperature the giant growth of amplitudes of thermal vibrations is observed, resulting in the formation of a "premelted state.