BaSnO3:Fe,N na forma de pós e filmes para fotodegradação de corantes

• Ano de defesa: 2017
• Autor(a) principal: Moura, Kleber Figueiredo de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraíba; Brasil; Química; Programa de Pós-Graduação em Química; UFPB
• Palavras-chave em Português: BaSnO3; Fe3+; Filmes finos; Oxinitretos; Fotocatálise; Thin films; Oxynitrides; Photocatalysis; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/123456789/11876

Compounds with ABO3 perovskite crystalline structure are widely used due to their electric and magnetic properties. Among these materials, BaSnO3 has been highlighted due to its semiconductor properties, with a bandgap adequate for photocatalytic applications in the UV region. This work aims at synthesing and characterizing BaSnO3:Fe perovskites obtained in powder form by the polymeric precursor method (modified-Pechini) and also BaSnO3:N,Fe thin films obtained by the pulsed laser deposition method followed by thermal ammonolysis. A high photocatalytic efficiency was observed for doped powders, which may be related to the disorder introduced by shallow defects and also to the electron trap which decreases recombination rate improving the formation of hydroxyl radicals in solution. Thin films in oxide form were deposited on substrates such as SiO2, Safira – R, LAO (100) and STO (100)(110), while oxynitride films were obtained on SiO2, Safira – R and LAO (100). Structure, morphology and optical properties were evaluated by X ray diffraction, scanning electronic microscopy and UVvis spectroscopy. Results showed that oxide thin films are polycrystalline on SiO2 and R-saphire substrates and epitaxial when deposited on LAO and STO. A meaningful decrease of the band gap values were detected by UV-vis spectroscopy in comparison to the respective oxides. BSO and BSO-10Fe deposited on SiO2 presented the highest photocatalytic efficiency for the RNL discoloration when compared to filmes deposited on R-saphire, LAO (100) and STO (100) e (110), in oxide form or in oxynitride form. In relation to the thin films deposited on STO, it was observed that the (100) plan is more active in photodegradation reaction than the (110) one, indicating the presence of active sites in these planes.