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Phase Equilibria in the System CuO-NiO-P4O10 and Synthesis, Crystal Structure, and Characterization of the New Copper Nickel Oxide Phosphate Cu3NiO(PO4)(2)



Druh Článek v odborném periodiku
Časopis / Zdroj Zeitschrift für anorganische und allgemeine Chemie
Fakulta / Pracoviště MU

Přírodovědecká fakulta

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Klíčová slova Copper nickel phosphate; Single crystal structure; Phase diagrams; Solid state reaction; Open circuit voltage
Popis The system CuO-NiO-P4O10 was investigated using a solid state reaction between CuO, NiO, and (NH4)(2)HPO4 in quartz crucibles at 900 degrees C. The powder samples were characterized by X-ray diffraction, TG/DTA, electrochemical measurements, IR, and UV/Vis spectroscopy. Single crystals of a new quaternary phase Cu3NiO(PO4)(2) were achieved by cooling the melted compound in a sealed, evacuated quartz ampoule. Cu3NiO(PO4)(2) crystallizes in the monoclinic space group P2(1)/n (no 14) with a = 8.2288(2) angstrom, b = 9.8773(2) angstrom, c = 8.2777(3) angstrom, = 107.82(2)degrees, Z = 4. The three-dimensional framework consists of distorted tetragonal pyramides [Cu1O(5)], distorted planar squares [Cu2O(4)], octahedra [Cu3O(6)], and [NiO6] and [PO4] tetrahedra. The TG-DTA of the new phase showed an incongruent melting at 1055 degrees C. The open circuit voltage of this material was measured to determine the electrochemical properties. The measurement revealed an initial capacity of 236 Ahg(-1) and a voltage plateau at 2.05 V. Furthermore, it was possible to identify the phase equilibria and to obtain the phase diagram at 900 degrees C.
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