Síntese e caracterização do La2Ce2O7 puro e com adição de ferro a partir do método de complexação combinado EDTA-Citrato

Abstract

This work had as objective to synthesis of La2Ce2O7 pure and Fe-doped (LaFeCe2O7) from the EDTA-Citrate combined complexation method. For the synthesis of powders used pH equal to 9 and reagents with oxidation state Ce3+ and Ce4+ . Calcination temperatures taken in getting the La2Ce2O7 and phases LaFeCe2O7 were 550, 725, 900 and 1000° C, and 500, 675 and 850 ºc, respectively. The materials obtained have been characterized by x-ray diffraction (DRX), Rietveld refinement, scanning electron microscopy (SEM) and diffuse reflectance spectroscopy. There was the formation of two phases (LaFeO3 e CeO2) when the Fe was added to pure La2Ce2O7, the LaFeO3 phase present in smaller quantities (34,65%), and CeO2 in greater quantity (65,35%). All samples showed strong State of agglomeration, spherical irregular formats and different sizes, however, the LaFeCe2O7 exhibited a heterogeneous surface, due to the presence of distinct phases in your structure. The synthesis of LaFeCe2O7 with the Ce4+ and calcination temperature equal to 850° C produced powders with smaller average crystallite size (18,28 nm para LaFeO3 e 21,69 nm para o CeO2 nm) and lower band gap energy (1,83 e 1,90 eV).