Some piezoelectric properties of lead zirconate titanate PbZr0.53Ti0.47O3 ceramic samples sintered at 1100oC for 3 hours has been investigated in this work and compared to the strontium modification at 0.2, 0.4, and 0.6 mol%. Polarization versus Electric Field curve and d33 and Kp piezoelectric parameters was taken at room temperature in order to investigate the correlation with phase amount and lattice parameters of crystalline phases calculated through Rietveld refinement. The results indicated the lead substitution with 0.4 mol% of strontium enhances the d33 and Kp piezoelectric parameters, but there is no systematic variation of the piezoelectric properties with strontium content. By the other hand, tetragonal phase seems plays an important rule on piezoelectric devices operating near the room temperature and some correlations could be found.
Lead zirconate titanate, with Zr/Ti ratio of 53/47 was prepared by the polymeric precursor method. The powders were doped with 0, 0.2, 0.4 end 0.6 mol% of Ca2+and characterized by XRD. The percentages of tetragonal and rhombohedral phases were calculated through Rietveld refinement. A systematic study of the effect of dopant on the ferroelectric and piezoelectric properties of PZT was carried out. The remanent polarization, planar coupling factor and piezoelectric charge constant, increase with dopant concentration.
Many synthesis methods are available to obtain a set of specific characteristics for lead zirconate titanate (PZT) piezoelectric ceramic powders. In this work, we have successfully prepared PZT powder samples through the Polymeric Precursor Method with x = 0.6, according the general formula Pb (ZrxTi1-x)O3. The powders were thermally treated from 380 to 550 oC and characterized by Raman spectroscopy and X-ray diffraction (DRX) in order to evaluate the effects of thermal treatment on the phase formation and the crystallization processes. The results obtained by Raman spectroscopy were compared to refined crystal data obtained by Rietveld method, leading to coherent conclusions about the structural effects occurring along the temperature of calcination. It was possible to characterize the tetragonal perovskite phase as predominant phase occurs only after 500 oC, but its crystallinity is already determined by synthesis method. Thus, no ordering process is verified for perovskite as a function of the temperature increasing during thermal treatment, in spite of the continuous pyrochlore-to-perovskite phase transition. The pyrochlore secondary phase starts to vanish before its proper crystallization process, changing the tetragonality of previously formed perovskite phase.
Este trabalho tem como objetivo a análise da pontualidade das linhas de ônibus Interbairros II e Santa Cândida/Capão Raso de Curitiba por serem de diferentes tipos de linhas e possuírem diferentes extensões de itinerário. Para isso, são adaptados os algoritmos para detecção da direção de deslocamento dos ônibus, mapeamento dos horários de passagem dos veículos em sua rota e pontualidade das linhas. Os resultados obtidos mostraram que a metodologia pode ser generalizada outros tipos de linhas de ônibus, com pontos de ônibus e veículos diferenciados.
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