Comprehensive characterization and structural modelling of lithium ferrites

The character and magnitude of the properties of lithium ferrites depend on the specific polymorph stabilized. Reliable polymorph identification and quantitative analysis have been realized by complementary structural characterization techniques (synchrotron X-ray diffraction, 57 Fe Mössbauer and X-ray absorption spectroscopies), through fitting/modelling of the experimental datasets to appropriate mathematical models. Calculated sample compositions show a maximum offset of 7 wt% between techniques, and cation distribution on the spinel-like LiFe 5 O 8 material has yielded values ranging from 60 to 67 at% Fe 3+ in octahedral sites with respect to the total number of Fe 3+ cations in the spinel phase. Magnetic transition temperatures (i.e., Néel/Curie) in the order of 91–93 K and 893–898 K have been measured for LiFeO 2 and LiFe 5 O 8 , respectively. The combined characterization presented here is brought forward as a reliable method to establish the relative concentrations of polymorphs in ferrites, a strategy which can be expanded to other families of Fe-based materials.