Low temperature synthesis of nanocrystalline lithium ferrite by a modified citrate gel precursor method

Single phase nanocrystalline lithium ferrite is synthesized by a modified citrate gel precursor technique. Ferrite nanoparticles of average size of 8 nm, obtained after calcination of the citrate gel made by the usual method at 450 °C, show superparamagnetic behavior. However, small amounts of -Fe₂O₃ is formed as an impurity phase due to the initial formation of some -Fe₂O₃ phase. On the other hand, when the pH of the mixed solution is increased to 7 after the addition of ammonia solution, a lower calcination temperature of 200 °C is sufficient for the formation of single phase lithium ferrite nanoparticles of size 30 nm. No impurity phases are detected when the nanocrystalline powders are calcined at higher temperatures. The magnetic properties of the ferrite nanoparticles of different sizes obtained by calcining the powders at different temperatures are studied.