Ferroelectrics
Mostrando 1-8 de 8 artigos, teses e dissertações.
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1. Piezoelectricity from Elastic and Dielectric Measurements on Unpoled Ferroelectrics
A method is described to assess the piezoelectric response of ferroelectric materials from the temperature dependence of the elastic moduli and dielectric constant of unpoled samples. The limits and advantages over the traditional methods on poled samples are discussed. A quantitative check is made by comparing the piezoelectric softening measured below the
Mat. Res.. Publicado em: 07/06/2018
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2. Peculiar Properties of Phase Transitions in Na0.5Bi0.5TiO3-xBaTiO3 (0
Na0.5Bi0.5TiO3-xBaTiO3 (0
Mat. Res.. Publicado em: 26/02/2018
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3. Efeito de metais de transição sobre a polarização espontânea na estrutura cristalina de nanopós da família tungstênio bronze
This work aimed the study of the effect of transition metals (Ni, Fe, Co) on the spontaneous polarization of the ferroelectric oxides of tetragonal tungsten bronze (TTB)-type structure of potassium strontium niobate (KSr2Nb5O15) and of the KSr2(FeNb4)O15-d, KSr2(NiNb4)O15-d and KSr2(CoNb4)O15-d solid solutions. All systems investigated were prepared by mecha
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 28/02/2011
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4. Electrophoretic deposition of Ba(Ti0.85Zr0.15)O3 nanoparticles to fabrication of laser sintered ferroelectrics thick films / Deposição de nanopartículas de Ba(Ti0.85Zr0.15)O3 pela técnica de eletroforese para fabricação de filmes espessos ferroelétricos sinterizados a laser
The goals of this work were the implantation and optimization of the technique of sintering by laser scan of thick films, the kinetic study of the process and the evaluation of the physical properties of the laser sintered compound BaTi0.85Zr0.15O3 (BTZ), compared to thick films sintered in conventional furnace. Nanocrystalline powders of BTZ were for the fi
Publicado em: 2008
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5. Uso da técnica do pulso eletroacústico para o estudo de polietilenos e titanato zirconato de chumbo (PZT). / Use of the pulsed electroacoustic technique for the study polyethilens and lead zirconate titanate (PZT).
The purpose this work was using to PEA method for investigation of the ferroelectrics response in PZT and space charge formation in polymeric materials (PE, XLPE) used as electrical insulation for high voltage devices. The PEA method is based on propagation acoustic signal generated by the application of a short electric field pulse, typically 5 ns in durati
Publicado em: 2003
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6. Laser sintering and characterization of the compounds Bi4Ti3O12 and Bi4Ge3O12 / "Sinterização a laser e caracterização física dos compostos Bi4Ti3O12 e Bi4Ge3O12"
The goals of this work were the implantation and optimization of the laser sintering technique for ceramic bodies, the kinetic study of the process and the evaluation of the physical properties of the laser sintered compounds Bi4Ti3O12 and Bi4Ge3O12, compared to ceramics sintered in conventional furnace. The choice of the materials was based on their potenti
Publicado em: 2003
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7. Ferrroelectric phase transitions and the Ising model
The Ising model has been an important theoretical tool in the understanding of phase transitions in ferroelectric materials. We first review how it relates to the underlying physics of order-disorder phase transitions in these systems, as well as mean-field results for the spontaneous polarization and the dielectric constant near the critical temperature. Fo
Brazilian Journal of Physics. Publicado em: 2000-12
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8. Relaxation dynamics near ferroelectric phase transitions and the central-peak phenomenon
The instability of the paraelectric phase in ferroelectrics, driven by thermal fluctuations, is discussed on the basis of the quantum three-dimensional spin-1/2 transverse-field Ising model (TIM) within the framework of the Green function method. The two-step critical dynamics of the TIM is analyzed through the ferroelectric order-parameter fluctuation spect
Brazilian Journal of Physics. Publicado em: 2000-12