A three-dimensional uranium-fluorine spin-frustrated CaB6-type lattice as potential conductive and quantum spin liquid candidate

• Published in: Ionics 2023-07, Vol.29 (7), p.2679-2685
• Main Authors: Wang, Li, Qin, Jie, Ran, Youyuan, Chen, Lan
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Cation exchanging; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrochemistry; Energy Storage; Fluorine; Fluorine compounds; Freezing; Hydrogen bonds; Lattices; Lithium ions; Magnetic permeability; Optical and Electronic Materials; Original Paper; Renewable and Green Energy; Spin liquid; Uranium
• ISSN: 0947-7047; 1862-0760
• DOI: 10.1007/s11581-023-05033-8

A case showing quantum spin liquid (QSL) behavior remains extremely scarce until now. To this end, it is suggested that the geometrical spin-frustrated lattices may be a potential platform for the study of QSL phenomena. In this work, we present an unprecedented geometrical spin-frustrated lattice with a three-dimensional five-connected CaB 6 -type topological matrix for the U(IV) centers in a novel uranium-fluorine compound, [U 6 F 31 ] [NH 4 ] 7 . Impressively, as evidenced by both the magnetic susceptibility and heat capacity measurements, this uranium-fluorine compound performs strong antiferromagnetic interactions without magnetic ordering, or spin freezing, or nonmagnetic singlet ground state down to 2 K, however appearing to be a QSL candidate. Moreover, [U 6 F 31 ][NH 4 ] 7 also enables remarkable proton conductivity of 1.87 × 10 −4 S/cm rather than electrical insulator as observed in the literature for all reported uranium-fluorine compounds, mainly resulted from the long-range hydrogen bond pathway between NH 4 + and F − . More importantly, [U 6 F 31 ][NH 4 ] 7 can be also used as ionic channel through solid–liquid reaction of cation exchange between NH 4 + and Li + , leading to high lithium-ion conduction of 2.48 × 10 −3 S/cm.