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Title: Crystal structure of a new polymorphic modification of niahite, NH{sub 4}MnPO{sub 4} · H{sub 2}O

The crystal structure of a new modification of the niahite mineral NH{sub 4}MnPO{sub 4} · H{sub 2}O, obtained in the form of single crystals under hydrothermal conditions in the Mn{sub 2}O{sub 3}-(NH{sub 4}){sub 3}PO{sub 4}-H{sub 2}O 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 D{sub 2h}{sup 16} = Pnam, Z = 4, D{sub x} = 2.497 g/cm{sup 3}. 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.
Authors:
; ;  [1]
  1. Moscow State University, Faculty of Geology (Russian Federation)
Publication Date:
OSTI Identifier:
22472411
Resource Type:
Journal Article
Resource Relation:
Journal Name: Crystallography Reports; Journal Volume: 60; Journal Issue: 2; Other Information: Copyright (c) 2015 Pleiades Publishing, Inc.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AMMONIUM PHOSPHATES; CHARGE-COUPLED DEVICES; CRYSTAL STRUCTURE; HYDRATES; MANGANESE OXIDES; MINERALS; MONOCRYSTALS; X-RAY DIFFRACTION