Crystal structure of a new polymorphic modification of niahite, NH4MnPO4 ⋅ H2Oстатья
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Дата последнего поиска статьи во внешних источниках: 5 мая 2015 г.
Аннотация:The crystal structure of a new modification of the niahite mineral NH4MnPO4 · H2O, obtained in
the form of single crystals under hydrothermal conditions in the Mn2O3–(NH4)3PO4–H2O system, is determined by X-ray diffraction (Xcalibur-S-CCD diffractometer, R = 0.0259): a = 17.582, b = 4.909, and c = 5.731 Å; space group = Pnam, Z = 4, Dx = 2.497 g/cm3. It is shown that the new compound is a polymorphic modification of niahite; it has a layered structure, which differs from the structure of the mineral by the presence of the center of inversion and the doubled a unit cell parameter. It is proposed to consider the minerals and synthetic analogues of the niahite and triphylite groups as members of the common polysomatic
series.