Análise experimental e numérica das características elétricas da matriz FeNbO4, sob a adição de TiO2, para aplicações na engenharia de micro-ondas e radiofrequência

• Ano de defesa: 2021
• Autor(a) principal: Bezerra Júnior, Manoel Henrique
• Orientador(a): Mota, João César Moura
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Niobato de Ferro; Micro-ondas; Radiofrequência; Propriedades dielétricas
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/64487

Over time, advanced ceramics have shown a large number of applications in different fields of science. In this work, the dielectric and structural properties of Iron Niobate (FNO) with addition of Titanium Oxide in proportions of 20, 40, 60 and 80% by mass were analyzed for applications in devices operating in the microwave and radiofrequency range. The solid state reaction method, with subsequent association of a sintering process at 1200°C, was used to obtain the desired samples. The structural characterization of the samples was performed using the X-Ray diffraction technique with the aid of the Rietveld refinement method. The results obtained in X-ray diffraction prove the formation of the ceramic matrix FNO, in addition to the phases of Iron and Niobium Titanate Ti1- 2x(FexNbx)O2 (TFNO) from the addition of TiO2. The analysis of the densification of the samples, carried out through Picnometry, showed results above 85%. The dielectric properties of the composites in the microwave region were obtained through experimental measurements and numerical simulations using DRs (Dielectric Resonators). Desirable stability was achieved with the addition of approximately 50% TiO2. The analysis in the radiofrequency region was carried out through the technique of impedance spectroscopy with temperature variation. At room temperature, at the frequency of 100Hz, the samples have high dielectric permittivity values reaching the order of 105. The values of the tangent of dielectric losses (tg δ) reached the order of magnitude of 10-1. With the increase in temperature, it was observed that there is greater mobility of charge carriers, increased conductivity and decreased impedance of samples. The activation energy values of the pure sample and the composites showed similar values.