Lanthanum ferrite ferromagnetic nanocrystallites by a polymeric precursor route

Reactive lanthanum orthoferrite nanoparticles were obtained by a polymeric precursor route. Nanoparticle growth and crystallization from amorphous precursor, as well as the formation of a grain boundary network in polycrystalline aggregates at different calcination temperatures were studied by conventional and high-resolution electron microscopy; electron and X-ray diffraction analysis; Raman; IR; and UV–vis spectroscopy. Microstructure measurements were compared to X-ray diffraction and chemical analysis results. Electron diffraction, combined with electron microscopy results were used to determine the content of amorphous phase. The coherent crystalline domain size and the particle size have been monitored by XRD and electron microscopy in order to determine the evolution of both crystal size and the onset temperature for crystallites formation. The results demonstrate that at 550 °C we obtain pure single-phase nanocrystalline LaFeO3, sized ∼40 nm, without the presence of amorphous phase. The magnetization curves in the 5–350 K range indicate weak ferromagnetism of the LaFeO3 powders.

Research highlights▶ Synthesis and magnetic properties of ferromagnetic LaFeO3 orthoferrite nanopowder. ▶ Low crystallization temperature with a homogeneous single-phase microstructure. ▶ Weak ferromagnetism maintained after calcination at 900 ̊C.