Synthesis of nanocrystalline LaMn0.5Fe0.5O3 powders via a PVA sol–gel route

LaMn0.5Fe0.5O3 powders were synthesized via a sol–gel route based on polyvinyl alcohol (PVA). Differential thermal (DTA) and thermogravimetric (TG) analysis, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM) techniques were used to characterize precursors and derived oxide powders. The effect of the molar ratios of hydroxyl groups of PVA to metal ions (OH/M) on the formation of LaMn0.5Fe0.5O3 was investigated. XRD analysis showed single-phase and well-crystallized LaMn0.5Fe0.5O3 of around 25 nm diameters was synthesized from the OH/M=1.5 precursor at 600 °C. For the precursor with OH/M=0.75, phase pure LaMn0.5Fe0.5O3 was not obtained even at 1000 °C and La(OH)3 was observed as impurity phase. LaMn0.5Fe0.5O3 ceramics sintered at 1300 °C showed a dielectric constant of 4300 at room temperature and 100 kHz.