Motta, Fabiana Villela daAssis, Raimison Bezerra de2021-12-162021-12-162017-06-29ASSIS, Raimison Bezerra de. Síntese de niobato de sódio e potássio (K1-xNaxNbO3) com propriedades fotocatalíticas e fotoluminescentes. 2017. 161f. Tese (Doutorado em Ciência e Engenharia de Materiais) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2017.https://repositorio.ufrn.br/handle/123456789/45428In recent years, photoluminescence and photocatalysis have shown a comprehensive field for research and development of materials technology. The development of new materials has opened new perspectives for the production of devices with photoluminescent properties and highly efficient photocatalytic. Promising materials of technological interest include sodium niobates and potassium (KNN) semiconductor, which perform well in optical and photocatalytic properties. In this work, perovskite structures sodium niobates and potassium (K1-xNaxNbO3) for x = 0; 30; 50; 70; 100% (mol) were synthesized by the polymeric precursor and thermally treated at 600°C, 700°C, 800°C and 900°C, in order to investigate their photocatalytic and photoluminescent properties. The samples were characterized by thermal analysis (TG/ DSC), X-ray diffraction (XRD), Raman spectroscopy, absorption in the infrared (FTIR) spectroscopy, optical absorption UV-vis, scanning electron microscopy (SEM), spectroscopy energy dispersive X-ray (EDS), photoluminescence (PL) and photocatalytic tests in the degradation of methylene blue. The results of X-ray diffraction confirmed the formation of the orthorhombic phase of perovskite KNN, K1-xNaxNbO3, presenting long range organization. FTIR spectra confirmed the data of X-ray diffraction to present reduction regarding the short bands of vibrations associated to the Nb = O double bonds. The SEM images showed that the sample had niobates KNN morphology in the form of cubes with different particle sizes, the presence of agglomerated and partially sintered regions. The optical absorption spectra of UV-vis characterized the semiconductor niobates as indicating "optical gap" between 2.59 eV and 3.35 eV, and reveal that the increase in heat treatment as well as the concentration of sodium promoted increasing gap band. The photoluminescence spectra showed decreased FL emission intensity with increasing sodium concentration in the KNbO3 matrix having emission at room temperature to the violet region (433 nm) to red (642 nm). The samples niobates KN, KNN30, KNN50, KNN70 and NN showed satisfactory rates of degradation, presented excellent results for NaNbO3 (NN) heat treated at 600°C with 95.95% degradation of the dye. The increased sodium concentration improved photocatalytic performance of KNN system, being efficient for photocatalytic applications. The results indicate the potential application of potassium sodium niobate in photocatalysis and photoluminescence.Acesso AbertoNiobato KNNPerovskitaPrecursores poliméricosFotocatáliseFotoluminescênciadoctoralThesis