Síntesis y caracterización estructural, morfológica y óptica de nanopartículas de ferrita de bismuto dopada con lantano : síntesis y caracterización de nanoestructuras de ferrita de bismuto dopada.

Abstract

Monodisperse lanthanum-doped bismuth ferrite nanoparticles were synthesized by the nanocasting method using the silicon oxide mold SBA-15. Structural characterization of SBA-15, BLFO@SBA-15 and BLFO was performed by low-angle X-ray diffraction. Wide-angle X-ray diffraction evidenced the crystalline phase of BLFO@SBA-15 and BLFO samples. Semiquantitative analysis of crystallinity and phases was performed using the DIFFRAC.EVA software finding the optimum parameters of 15$\%$ doping concentration to reduce secondary impurities and evaporation temperature of 120$^\circ$C for obtaining high crystallinity. Rietveld refinement was performed finding that lattice parameters increase as the doping does. In addition, the chemical composition of the samples was verified. The morphology was characterized by transmission electron microscopy measurements where the nanoparticles sizes ranged from 3.47 nm to 8.35 nm. The particles were accompanied by irregularly shaped structures. By UV-Vis spectroscopy, band gap values between 2.49 eV and 2.56 eV for direct transitions and between 2.2 eV and 2.22 eV for indirect transitions were found. The potential of nanocasting for controlling nanoparticle size, maintaining sample crystallinity while increasing lanthanum doping and stabilizing the pure BFO phase was evidenced.