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Phase Equilibria in the System CuO‐NiO‐P 4 O 10 and Synthesis, Crystal Structure, and Characterization of the New Copper Nickel Oxide Phosphate Cu 3 NiO(PO 4 ) 2
Author(s) -
Weimann Iren,
Feller Jörg,
Žák Zdirad
Publication year - 2017
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201600403
Subject(s) - non blocking i/o , tetragonal crystal system , monoclinic crystal system , materials science , analytical chemistry (journal) , crystallography , crystal structure , phase diagram , nickel oxide , copper oxide , phase (matter) , copper , nickel , chemistry , metallurgy , biochemistry , organic chemistry , chromatography , catalysis
The system CuO‐NiO‐P 4 O 10 was investigated using a solid state reaction between CuO, NiO, and (NH 4 ) 2 HPO 4 in quartz crucibles at 900 °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 Cu 3 NiO(PO 4 ) 2 were achieved by cooling the melted compound in a sealed, evacuated quartz ampoule. Cu 3 NiO(PO 4 ) 2 crystallizes in the monoclinic space group P 2 1 / n (no 14) with a = 8.2288(2) Å, b = 9.8773(2) Å, c = 8.2777(3) Å, β = 107.82(2)°, Z = 4. The three‐dimensional framework consists of distorted tetragonal pyramides [Cu1O 5 ], distorted planar squares [Cu2O 4 ], octahedra [Cu3O 6 ], and [NiO 6 ] and [PO 4 ] tetrahedra. The TG‐DTA of the new phase showed an incongruent melting at 1055 °C. The open circuit voltage of this material was measured to determine the electrochemical properties. The measurement revealed an initial capacity of 236 Ah · g –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 °C.