SÍNTESE E CARACTERIZAÇÃO DE ÓXIDO DE BISMUTO, FERRO E TITANATO DE CHUMBO DOPADO COM ÍONS La3+

Abstract

The Oxide and Bismuth and Lead Titanate (BiFeO3 – PbTiO3) have gained space in academia because they have optical properties that can be used in devices such as sensors and photovoltaic cells. To enhance or provide the appearance of new properties, Lanthanium ion doping (La3+) is used in the compound to effect structural changes. The aim of this study was the Pechini method in order to obtain BiFeO3 – PbTiO3 powders, pure and doped with 5% and 8% La3+. The powders were characterized by thermal analysis, X-ray diffraction (XRD) and photoacoustic spectroscopy (PAS). The thermoanalytical techniques verified events of water evaporation, decomposition of ethylene glycol and combustion reactions of the organic matter. The XRD measurements indicated the formation of the rhombohedral phase for the pure and doped samples with 5% of La and with the increase of the doping to 8% the phase observed was tetrahedral. The results showed that with 5% La it favors the formation of the BiFeO3 oxide. Therefore, with a higher concentration of La3+ in the oxide, the change in structure was observed. The pure BiFeO3 – PbTiO3 samples, with 5% and 8% of La treated thermally at 600°C, were characterized by PAS in the range of 250 nm to 1600 nm, and optical absorptions were evidenced throughout the analyzed spectral range. he spectra obtained showed that there was no significant difference in the intensity of the photoacoustic signal between the pure and doped samples. The band gap value for BiFeO3-PbTiO3 is 2.1 eV, for the sample with 5% La, it is 2.1 eV and for the sample doped with 8% La is 2.08 eV, according to the results obtained via UV-VIS absorption. Considering a low band gap material with absorption in the UV-VIS region, there is a possible candidate for application in devices such as sensors and photovoltaic cells.