Raman characterization of α- and β-LiFe5O8 prepared through a solid-state reaction pathway

Lithium ferrite, a mixed-inverse spinel of type AxBy[A1−xB1−y]O4 was produced through solid state synthesis by calcining a Li2CO3/Fe2O3 mixture at 900 °C. The presence of both the ordered α-phase and disordered β-phase of LiFe5O8 was confirmed by XRD analysis, while formation of the latter was achieved by air quenching from high temperature. Laser Raman analysis was performed on both the α-LiFe5O8 and β-LiFe5O8 powders in order to achieve a reference set of Raman shifts for the spinel. The strongest, characteristic Raman peaks were determined to be 493, 382, 358, 300, and 263 cm−1 for both phases while smaller peaks at 202 and 236 cm−1 present in the α-phase were diminishing in intensity when the β-phase was present, thus providing unique identifiers for the presence of the disordered ferrite structure. SEM images taken of the synthesized LiFe5O8 powders showed particle sizes of less than 300 nm and an even particle size distribution.

The disordered, β-phase of lithium ferrite is sustained by air quenching from 900 °C. Shown is a SEM image of β-LiFe5O8 exhibiting even particle sizes less than 300 nm.Figure optionsDownload as PowerPoint slide