Short-range nanoregions and nanosized defects in LiFeO$$_2$$ compound deduced from Mössbauer spectroscopy and Rietveld analysis

Abstract

AbstractWe 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 $$\alpha$$ α -LiFeO$$_2$$ 2 and $$\beta '$$ β ′ -LiFeO$$_2$$ 2 phases reveals that short-range ordering observed in the $$\alpha$$ α -LiFeO$$_2$$ 2 phase is potentially linked to the $$\beta '$$ β ′ -LiFeO$$_2$$ 2 phase nanoregions. Low-temperature MS of the $$\alpha$$ α -LiFeO$$_2$$ 2 phase reveal a complicated disordered magnetic state below 90 K. Rietveld analysis of the XRD data of the $$\gamma$$ 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 $$\beta '$$ β ′ -LiFeO$$_2$$ 2 phase in pure form, extended annealing of the $$\alpha$$ α -LiFeO$$_2$$ 2 phase at 400 $$^\circ$$ ∘ C yields a nanocomposite material comprising nanoregions of both $$\beta '$$ β ′ -LiFeO$$_2$$ 2 and $$\gamma$$ γ -LiFeO$$_2$$ 2 phases. Graphical abstract