Short-range nanoregions and nanosized defects in LiFeO₂ compound deduced from Mössbauer spectroscopy and Rietveld analysis

We examined the crystal and magnetic properties of the polymorphic LiFeO ₂ 2 compound using Mössbauer spectra (MS), X-ray diffraction data (XRD), and magnetic measurements. X-ray diffraction analysis of α α -LiFeO ₂ 2 and β ' β ′ -LiFeO ₂ 2 phases reveals that short-range ordering observed in the α α -LiFeO ₂ 2 phase is potentially linked to the β ' β ′ -LiFeO ₂ 2 phase nanoregions. Low-temperature MS of the α α -LiFeO ₂ 2 phase reveal a complicated disordered magnetic state below 90 K. Rietveld analysis of the XRD data of the γ γ -LiFeO ₂ 2 phase reveals a defect microstructure. These defects produce a complicated distribution of the hyperfine magnetic field estimated from MS. While it is not possible to produce the β ' β ′ -LiFeO ₂ 2 phase in pure form, extended annealing of the α α -LiFeO ₂ 2 phase at 400 ^∘ ∘ C yields a nanocomposite material comprising nanoregions of both β ' β ′ -LiFeO ₂ 2 and γ γ -LiFeO ₂ 2 phases.