Crystal Structures and Low-Dimensional Ferromagnetism of Sodium Nickel Phosphates Na5Ni2(PO4)3·H2O and Na6Ni2(PO4)3OH

Maria A Kirsanova; Dmitry A Aksyonov; Olga V Maximova; Larisa V Shvanskaya; Alexander N Vasiliev; Alexander A Tsirlin; Artem M Abakumov

doi:10.1021/acs.inorgchem.8b02791

Crystal Structures and Low-Dimensional Ferromagnetism of Sodium Nickel Phosphates Na₅Ni₂(PO₄)₃·H₂O and Na₆Ni₂(PO₄)₃OH

Inorg Chem. 2019 Jan 7;58(1):610-621. doi: 10.1021/acs.inorgchem.8b02791. Epub 2018 Dec 19.

Authors

Maria A Kirsanova¹, Dmitry A Aksyonov¹, Olga V Maximova^{2

3}, Larisa V Shvanskaya^{2

3}, Alexander N Vasiliev^{2

3

4}, Alexander A Tsirlin⁵, Artem M Abakumov¹

Affiliations

¹ Skolkovo Institute of Science and Technology , Moscow 143026 , Russia.
² Lomonosov Moscow State University , Moscow 119991 , Russia.
³ National University of Science and Technology "MISiS" , Moscow 119049 , Russia.
⁴ National Research South Ural State University , Chelyabinsk 454080 , Russia.
⁵ Experimental Physics VI, Center for Electronic Correlations and Magnetism , University of Augsburg , 86135 Augsburg , Germany.

PMID: 30565920
DOI: 10.1021/acs.inorgchem.8b02791

Abstract

Two new sodium nickel phosphates, Na₅Ni₂(PO₄)₃·H₂O (I) and Na₆Ni₂(PO₄)₃OH (II), have been synthesized hydrothermally and characterized by synchrotron X-ray diffraction, electron diffraction, low-temperature thermodynamic and magnetic measurements, and ab initio calculations. Unlike the majority of Ni²⁺ compounds, I and II show predominant ferromagnetic exchange couplings. I crystallizes in the monoclinic space group P2₁/ n ( a = 14.0395(4) Å, b = 5.1847(14) Å, c = 16.4739(4) Å, β = 110.4186(14)°) and features chains of ferromagnetically coupled Ni²⁺ ions. In II with the orthorhombic space group Pcmb ( a = 7.5007(15) Å, b = 21.4661(4) Å, c = 7.1732(15) Å), the ferromagnetically coupled Ni²⁺ ions form dimers arranged on a spin ladder. Both compounds represent rare examples of quasi-one-dimensional ferromagnets. Structural features behind this unusual magnetic behavior are discussed.