Synthesis and characterization of the crystal structure, the magnetic and the electrochemical properties of the new fluorophosphate LiNaFe[PO4]F

The new compound LiNaFe[PO4]F was synthesized by a solid state reaction route, and its crystal structure was determined using neutron powder diffraction data. LiNaFe[PO4]F was characterized by 57Fe Mossbauer spectroscopy, magnetic susceptibility, specific heat capacity, and electrochemical measurements. LiNaFe[PO4]F crystallizes with orthorhombic symmetry, space group Pnma, with a = 10.9568(6) A, b = 6.3959(3) A, c = 11.4400(7) A, V = 801.7(1) A3 and Z = 8. The structure consists of edge-sharing FeO4F2 octahedra forming FeFO3 chains running along the b axis. These chains are interlinked by PO4 tetrahedra forming a three-dimensional framework with the tunnels and the cavities filled by the well-ordered sodium and lithium atoms, respectively. The specific heat and magnetization measurements show that LiNaFe[PO4]F undergoes a three-dimensional antiferromagnetic ordering at TN = 20 K. The neutron powder diffraction measurements at 3 K show that each FeFO3 chain along the b-direction is ferromagnetic (FM), while these FM chains are antiferromagnetically coupled along the a and c-directions with a non-collinear spin arrangement. The galvanometric cycling showed that without any optimization, one mole of alkali metal is extractable between 1.0 V and 5.0 V vs. Li+/Li with a discharge capacity between 135 and 145 mAh g-1. © 2012, Royal Society of Chemistry.

Keywords

Solid state physics, Bonding, Valence, Lithium, Cathodes, Antiferromagnetism

Citation

Ben Yahia, H., Shikano, M., Sakaebe, H., Koike, S., Tabuchi, M., Kobayashi, H., Kawaji, H., Avdeev, M., Miiller, W., & Ling, C., D. (2012). Synthesis and characterization of the crystal structure, the magnetic and the electrochemical properties of the new fluorophosphate LiNaFe[PO4]F. Dalton Transactions, 41(38), 11692-11699. doi:10.1039/c2dt30739a