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

Abstract

Two synthetic routes—ion-exchange preparation from layered Na₃Ni₂SbO₆ at 300 °C and direct solid-state synthesis at 1150 °C resulted in layered Li₃Ni₂SbO₆, a cation-ordered derivative from the rocksalt type. The Fddd form reported earlier could not be reproduced. According to the XRD Rietveld analysis, Li₃Ni₂SbO₆ 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, Li₃Ni₂SbO₆ 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 Ni²⁺ (S = 1). Electron spin resonance (ESR) spectra show single Lorentzian shape line attributed to Ni²⁺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 Li₃Ni₂SbO₆, the superexchange interaction between Ni²⁺ ions through Ni–O–Ni pathways within Ni₂SbO₆ layers are assumed to be ferromagnetic, while the dominant interaction between layers is antiferromagnetic.