Crystal structure and thermodynamic properties of dinickel diphosphate dihydrate Ni2(H2O)2[P2O7]

Autor: Sergey V. Simonov, Olga V. Dimitrova, Yevgeniy Ovchenkov, Larisa Shvanskaya, Alexander N. Vasiliev, Anatoly S. Volkov, Galina V. Kiriukhina, Olga V. Yakubovich
Rok vydání: 2020
Předmět:
Zdroj: Dalton Transactions. 49:17368-17374
ISSN: 1477-9234
1477-9226
DOI: 10.1039/d0dt03505j
Popis: Single crystals of dinickel diphosphate dihydrate, Ni2(H2O)2[P2O7], have been synthesized by a hydrothermal method. Its structure was refined in the monoclinic P21/n space group (unit cell parameters a = 6.2517(1) A, b = 13.7892(3) A, c = 7.2894(2) A, β = 94.507(2)°, V = 626.45(2) A3, and Z = 4) based on low-temperature X-ray diffraction data until R – 0.016. Corrugated chains of NiO5(H2O) octahedra sharing edges are aligned in the [10] direction. They are linked into a three-dimensional framework through diphosphate groups and hydrogen bonds. A detailed crystal chemical analysis of the family Me2(H2O)2[X2O7] revealed correlations between the unit-cell parameters of the isotypic transition metal phosphates and arsenates, their structural features and the sizes of structure forming cations. Despite the isolation of the cis and trans edge-sharing infinite zigzag chains of Ni-centered octahedra from each other no pronounced low dimensionality is seen in the magnetic response of Ni2(H2O)2[P2O7]. The magnetic susceptibility χ evidences a short range correlation maximum at Tmax = 11.9 K accompanied by the onset of long-range magnetic order at TN = 9.4 K. Below TN, the title compound exhibits the features of an archetype three-dimensional easy-axis antiferromagnet which experiences a sequence of spin–flop and spin–flip phase transitions. Basing on specific heat Cp and magnetization M studies, the magnetic phase diagram of Ni2(H2O)2[P2O7] has been established.
Databáze: OpenAIRE
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