Monoclinic honeycomb-layered compound Li3Ni2SbO6: preparation, crystal structure and magnetic properties

Abstract

Two synthetic routes-ion-exchange preparation from layered Na(3)Ni(2)SbO(6) at 300 °C and direct solid-state synthesis at 1150 °C resulted in layered Li(3)Ni(2)SbO(6), a cation-ordered derivative from the rocksalt type. The Fddd form reported earlier could not be reproduced. According to the XRD Rietveld analysis, Li(3)Ni(2)SbO(6) is a pseudohexagonal monoclinic structure, C2/m, with a = 5.1828(2) Å, b = 8.9677(3) Å, c = 5.1577(2) Å, β = 109.696(2)°. No Li/Ni mixed occupancy was detected. At high temperatures, the magnetic susceptibility follows the Curie-Weiss law with a positive value of Weiss temperature, ∼8 K, indicating a predominance of ferromagnetic interactions. However, Li(3)Ni(2)SbO(6) orders antiferromagnetically at T(N)∼ 15 K. The effective magnetic moment is 4.3 μ(B)/f.u. which satisfactorily agrees with theoretical estimations assuming high-spin configuration of Ni(2+) (S = 1). Electron spin resonance (ESR) spectra show single Lorentzian shape line attributed to Ni(2+) ion in octahedral coordination. The absorption is characterized by isotropic temperature independent effective g-factor g = 2.150 ± 0.005. In accordance with the layered honeycomb crystal structure determined for Li(3)Ni(2)SbO(6), the superexchange interaction between Ni(2+) ions through Ni-O-Ni pathways within Ni(2)SbO(6) layers are assumed to be ferromagnetic, while the dominant interaction between layers is antiferromagnetic.

Zigzag antiferromagnetic quantum ground state in monoclinic honeycomb lattice antimonatesA3Ni2SbO6(A=<

“…NiO 6 octahedra in Na 3 Ni 2 SbO 6 have rather regular Ni-O distances but a spread of angles between 82.1 and 95.8 [39]. NiO 6 octahedra are only slightly more regular for Li 3 Ni 2 SbO 6 , with the angles between 83.4 and 94.9 [20]. The general view of the crystal structure and honeycomb network of octahedrally coordinated nickel ions in Na 3 Ni 2 SbO 6 are shown in Fig.…”

“…No long-range magnetic order was found for honeycomb Na 3 LiFeSbO 6 and Na 4 FeSbO 6 and Li 4 MnSbO 6 probably due to disorder and frustration effects [34,36]. At the same time, honeycomb-ordered O3-derived phases Na 3 M 2 SbO 6 (M=Cu, Ni, Co) [17,19,31], Li 3 Ni 2 SbO 6 [20], Li 3 Ni 2 BiO 6 [21], Na 3 Ni 2 BiO 6 [33], as well as P2-derived Na 2 M 2 TeO 6 (M=Co, Ni) [18,19], were found to order antiferromagnetically at low temperatures but their real quantum ground state remains unknown and requires joint experimental and theoretical efforts to be determined. The influence of the interlayer coupling and of the anisotropy on the ground state in such systems is largely unexplored at present.…”

“…Basic magnetic properties of Li 3 Ni 2 SbO 6 and Na 3 Ni 2 SbO 6 have been reported recently [17,20,22], but a systematic analysis of their electronic and magnetic behavior is missing. Ordered structure of Li 3 Ni 2 SbO 6 was refined in the space group C2/m [20].…”

“…20,22. Their phase purity was verified by powder X-ray diffraction (ICDD PDF 00-53-0344 and 00-63-566).…”

“…Ordered structure of Li 3 Ni 2 SbO 6 was refined in the space group C2/m [20]. For Na 3 Ni 2 SbO 6 , the initial structure determination was complicated by multiple stacking faults.…”