Thickness dependence of structure and piezoelectric properties at nanoscale of polycrystalline lead zirconate titanate thin films

Lead zirconate titanate Pb(Zr0.50Ti0.50)O3 (PZT) thin films were deposited by a polymeric chemical method on Pt(111)/Ti/SiO2/Si substrates to understand the mechanisms of phase transformations and the effect of film thickness on the structure, dielectric, and piezoelectric properties in these films. PZT films pyrolyzed at temperatures higher than 350 °C present a coexistence of pyrochlore and perovskite phases, while only perovskite phase grows in films pyrolyzed at temperatures lower than 300 °C. For pyrochlore-free PZT thin films, a small (100)-orientation tendency near the film-substrate interface was observed. Finally, we demonstrate the existence of a self-polarization effect in the studied PZT thin films. The increase of self-polarization with the film thickness increasing from 200 nm to 710 nm suggests that Schottky barriers and/or mechanical coupling near the film-substrate interface are not primarily responsible for the observed self-polarization effect in our films. © 2013 AIP Publishing LLC.

Variabilidade genética para o teor de óleo entre progênies autofecundadas de mamona (Ricinus cummunis L.) da cultivar guarani

Pós-graduação em Agronomia (Agricultura) - FCA

Estudos de materiais ferroelétricos por espectroscopia no infravermelho

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo da estabilização da fase perovskita PMN em filmes ultrafinos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Síntese e caracterização estrutural de filmes finos Bi4Ti3O12

Pós-graduação em Ciência dos Materiais - FEIS

Cerâmica condutora à base de 'SN''O IND.2' obtida pelo método dos precursores poliméricos e sinterização por micro-ondas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Resistência de genótipos de feijão-caupi Vigna unguiculata a Bemisia tabaci Biótipo B (Hemiptera: Aleyrodidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência de diferentes tratamentos de superfície em uma cerâmica policristalina de zircônia tetragonal (ytzp), na resistência de união com cimento resinoso

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da metodologia de síntese nas propriedades elétricas da cerâmica PMN-PT

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fases nanoscópicas de manganitas magnéticas

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Effect of Composition on the Physical Properties at Nanoscale of PZT Thin Films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Bioremediation of direct dyes in simulated textile effluents by paramorphogenic form of Aspergillus oryzae

Azo dyes are extensively used for coloring textiles, paper, food, leather, drink, pharmaceutical products, cosmetics and inks. The textile industry consumes the largest amount of azo dyes, and it is estimated that approximately 10 - 15% of dyes used for coloring textiles might be lost in waste streams. Almost all azo dyes are synthetic and resist biodegradation, however, they can be readly reduced by a number of chemical and biological reducing systems. Biological treatment is advantageous over physical and chemical method as result of its low cost and little disturbance to the environment. This research focuses on the utilization of Aspergillus oryzae, to remove some kinds of azo dyes from aqueous solutions. The fungi, physically induced in its paramorphogenic form (called, pellets), were used in the dyes biosorption studies with both non autoclave and autoclaved hyphas, at differents pH values. Thus the goals are the removal of dyes by biosorption and the decrease of its toxicity.

Thickness-dependent piezoelectric behaviour and dielectric properties of lanthanum modified BiFeO3 thin films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dielectric properties of Sr0.75Ba0.25Nb 2O6 thin films: Bias field, frequency and temperature dependence

Ferroelectric strontium barium niobate solid solutions had received great attention due to their excellent pyroelectric, electrooptic and photorefractive properties. Furthermore, they usually also present very interesting phase transition characteristics. In this work, polycrystalline single phase Sr 0.75 Ba 0.25 Nb 2 O 6 thin films were prepared by a hybrid chemical method and deposited on Pt/Ti/SiO 2 /Si substrates. The temperature dependence of dielectric constant was measured at different frequencies and bias field levels. The presence of two dielectric dispersion regions with relaxor characteristics was observed at distinct temperature ranges, corresponding to the ferro-paraelectric and to a structural phase transition at low temperatures, respectively. A specific dielectric dispersion region, associated with an incommensurate superstructure frequently observed in bulk samples, was not observed in this films probably due to their small grain sizes. © 2002 Taylor & Francis.

Non-centrosymmetric crystals of new N-benzylideneaniline derivatives as potential materials for non-linear optics

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)