Synthesis and characterization of lithium ferrite by oxalate precursor route

Abstract

Nanocrystalline lithium ferrite (LiFe 5O 8) powders have been synthesized by oxalate precursor route. The effects of Fe 3+/Li + mole ratio, and annealing temperature on the formation, crystalline size, morphology and magnetic properties were systematically studied. The Fe 3+/Li + mole ratio was controlled from 5 to 3.33 while the annealing temperature was controlled from 600 to 1100 °C. The resultant powders were investigated by differential thermal analyzer (DTA), X-ray diffractometer (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). DTA results showed that LiFe 5O 8 phase started to form at around 520 °C. XRD indicated that LiFe 5O 8 phase always contained α-Fe 2O 3 impurity and the hematite phase formation increased by increasing the annealing temperature ⩾850 °C for different Fe 3+/Li + mole ratios 5, 4.55 and 3.85. Moreover, lithium ferrite phase was formed with high conversion percentage at critical annealing temperature 750–800 °C. Single well crystalline LiFe 5O 8 phase was obtained at Fe 3+/Li + mole ratio 3.33 and annealing temperatures from 800 to 1000 °C. Maximum saturation magnetization (68.7 emu/g) was achieved for the formed lithium ferrite phase at Fe 3+/Li + mole ratio 3.33 and annealing temperature 1000 °C.