Estudo dos efeitos da adição de ZnO e Nb2O5 nas propriedades dielétricas da matriz cerâmica BaBi4Ti4O15 (BBT) e suas aplicações em antenas

• Autor(a) principal: Silva, Paulo Maria de Oliveira
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/7884
• topic: Teleinformática; Material cerâmico; Microondas; Rádio - Transmissão

With the rapid growth of the telecommunications industry created a strong need for ceramic materials for applications in microwave. These materials should exhibit high dielectric permittivity (εr), high quality factor (Q), good thermal stability (τf ±10 ppm/ºC) and low cost. With the invention of mobile phones, the field of wireless communication has undergone a revolutionary growth in recent decades. The success of the third generation (3G) services in mobile communication, motivates the development of broadband fourth generation (4G) of mobile phones and other wireless products and services, such as Bluetooth. Nowadays it is well known the use of tablets, which are increasingly gaining market and encouraging the development of new technologies to improve the flow of information. This work involves the development and characterization of the barium bismuth titanate ceramic, (BaBi4Ti4O15) with addition of niobium oxide (Nb2O5) or zinc oxide (ZnO) in order to decrease the sintering temperature and possibly improve the densification and subsequently check the modifications on material properties, such as the temperature coefficient of resonant frequency (τf). The series ceramics were produced using the solid state reaction with the use of high energy mechanical milling and heat treatment. The structural characterization was performed based on Scanning Electron Microscopy (SEM) and Measurement by Pycnometer. The relative densities of the samples with added (ZnO) had the highest concentration value of 77% pure BBT while the value was 56%. The relative densities of the samples spiked with (Nb2O5) had the highest concentration value of 61% compared to pure BBT. Experiments were conducted to evaluate the electrical and dielectric behavior of the samples in the range of Microwave and Radio Frequency (temperature and temperature variation). Finally, the material was tested as a DRA, and then the results were simulated using the HFSS program. The characteristics of the pure ceramic DRA are 1,12dBi gain and 32,51% efficiency. The DRA added with 2% (ZnO ) showed 1.16dBi gain with 33,96% efficiency , while the one that was added with 5% (Nb2O5) showed gain of 1.41dBi with 42,21% efficiency.