Estudo das propriedades dielétricas do Niobato de Bismuto e Titânio dopado com PbO e Bi2O3 para aplicações em antenas

• Ano de defesa: 2009
• Autor(a) principal: Silva, Roger Ribeiro
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Difração de raios X; Fatores de qualidade; Constante dielétrica; Ressoadores; Hakki-Coleman
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/12890

Dielectric resonators based on type structure compound Bi3TiNbO9 show singular characteristics for microwave applications, including high dielectric constants, low dissipation losses and low temperature coefficients. Single phase of the Bi3TiNbO9 powder was obtained by x-ray diffraction technique. The ceramics doped during manufacture, with lead oxide and bismuth oxide, were synthesized by solid state reaction at 950°C for two hours. Samples were analysed by Archimedes method and exhibited good levels of density for doped ceramics with bismuth and lead oxide. Grain morphology and stoichiometry of ceramics were investigated by scanning electron microscopy and energy dispersive spectroscopy technique. Far infrared spectroscopy identified large bands on the Bi3TiNbO9 structure by attenuated total reflection technique. Radiofrequency measurements showed that doped ceramics exhibited higher dielectric constants than pure phase. Microwave measurements were investigated by Hakki-Coleman and resonant cylindrical cavity. The ceramics called as BTNO3BiP, BTNO5BiP, BTNO10BiP, BTNO3PbG e BTNO5PbG, showed high dielectric constants and high quality factors demonstrating that they can be applied in dielectric antennas on microwave range.