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Here, we report a study of white-ochre powders with targeted composition MnWO4 prepared via a coprecipitation method. Through X-ray total scattering combined with pair distribution function analysi...

Here, we report a study of white-ochre powders with targeted composition MnWO

The members of the CuMo1 - xWxO4 series (0 ≤ x < 0.1) undergo a first-order phase transition at normal pressure, which can be induced by temperature. The two allotropic forms exhibit two distinguishable colors, green for the high-temperature form (α) and brownish-red for the low temperature one (γ), which opens up a new market for user-friendly temperature indicators. From X-ray diffraction and microprobe analyses as from optical properties, the tungsten substitution rate for molybdenum is limited to 12%. Beyond, a third, parasitic wolframite-type phase, CuMo0.6W0.4O6, systematically crystallizes besides the α/γCuMo0.9W0.1O4 compounds. Within the CuMo1 - xWxO4 solid-solution domain, the dependence of the transition temperatures was followed by calorimetry, optical reflectivity, and magnetism. On the basis of these measurements, the transition is characterized for all of the chemical compositions by a hysteresis loop of about 90 K in width with a temperature transition strongly dependent on the tungsten co...

The compounds Ba2CoSi2O7, 1, and BaCo2Si2O7, 2, were obtained by heating mixtures of BaCO3, CoCO3, and SiO2 in the proper stoichiometries to 1300 °C for 48 h. Both materials were characterized by single-crystal X-ray diffraction and magnetization measurements on powder and partially oriented single crystals. Each cobalt ion in 1 is surrounded by four oxygen atoms derived from the [Si2O7]6- groups in the form of a distorted tetrahedron. The cobalt ions are bridged by O−Si−O and O−Si−O−Si−O groups from the [Si2O7]6- ions in an extended two-dimensional arrangement. The barium ions are arranged in layers that run parallel to the Co[Si2O7] layers. In 2 each cobalt ion is also surrounded by an arrangement of four oxygen atoms derived from the Si2O7 groups in a distorted tetrahedral shape. These tetrahedra are linked into chains through the sharing of one of the oxygen atoms from the Si2O7 groups. The CoO4 chains are crosslinked via O−Si−O−Si−O bridges from the Si2O7 groups. The barium ions occupy channels that ...