Structural and magnetic characterization of MnxZn1-xFe2O4 (x=0.2; 0.35; 0.65; 0.8; 1.0) ferrites obtained by the citrate precursor method

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Y2O3:Eu3+ (5 mol%) with Ag nanoparticles prepared by citrate precursor

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

TiO2/CuO films obtained by citrate precursor method for photocatalytic application

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

The effect of Eu3+ concentration on the Y2O3 host lattice obtained from citrate precursors

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

Desenvolvimento de recobrimento submicrométrico de óxido de nióbio para aplicação em tubulações de prospecção de petróleo

Pós-graduação em Engenharia Mecânica - FEG

Polymeric precursor method to the synthesis of XWO(4) (X = Ca and Sr) thin films-Structural, microstructural and spectroscopic investigations

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

Influência do oxalato de amônio na formação do precursor columbita obtido pelo método Pechini

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

Epitaxially grown LiNbO3 thin films by polymeric precursor method

LiNbO3 thin films were grown on (0001) sapphire substrates by a chemical route, using the polymeric precursor method. The overall process consists of preparing a coating solution from the Pechini process, based on metallic citrate polymerization, the precursor films, deposited by dip coating, are then heat treated to eliminate the organic material and to synthesize the phase. In this work, we studied the influence of the heat treatment on the structural and optical properties of single-layered films. Two routes were also investigated to increase the film thickness: increasing the viscosity of the coating solution and/or increasing the number of successively deposited layers. The x-ray diffraction theta -2 theta scans revealed the c-axis orientation of the single- and multilayered films and showed that efficient crystallization can be obtained at temperatures as low as 400 degreesC, the phi-scan diffraction evidenced the epitaxial growth with two in-plane variants, A microstructural study revealed that the films were crack free, homogeneous, and relatively dense. Finally, the investigation of the optical properties (optical transmittance and refractive index) confirmed the good quality of the films. These results indicate that the polymeric precursor method is a promising process to develop lithium niobate waveguides.

Thermal and structural investigation of SnO2/Sb2O3 obtained by the polymeric precursor method

SnO2-based materials are used as sensors, catalysts and in electro-optical devices. This work aims to synthesize and characterize the SnO2/Sb2O3-based inorganic pigments, obtained by the polymeric precursor method, also known as Pechini method (based on the metallic citrate polymerization by means of ethylene glycol). The precursors were characterized by thermogravimetry (TG) and differential thermal analysis (DTA). After characterization, the precursors were heat-treated at different temperatures and characterized by X-ray diffraction. According to the TG/DTA curves basically two-step mass loss process was observed: the first one is related to the dehydration of the system; and the second one is representative to the combustion of the organic matter. Increase of the heat treatment temperature from 500 to 600 degrees C and 700 degrees C resulted higher crystallinity of the formed product.

Heterogeneous Fenton reactants: a study of the behavior of iron oxide nanoparticles obtained by the polymeric precursor method

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Preparation and properties of ferroelectric BaTiO3 thin films produced by the polymeric precursor method

Ferroelectric barium titanate thin films were produced by the polymeric precursor method. In this technique, the desired metal cations are chelated in a solution using a hydroxycarboxylic acid as the chelating agent. Barium carbonate and titanium IV isopropoxide were used as precursors for the citrate solution. Ethylene glycol and citric acid were used as polymerization/complexation agents for the process. The crystalline structure of the film annealed at 700 °C had a single perovskite phase with a tetragonal structure. The BaTiO3 film showed good P-E hysteresis loops and C-V characteristics due to the switched ferroelectric domains.

Effect of Nb on barium titanate prepared from citrate solutions

The influence of the addition of dopants on the microstructure development and electrical properties of BaTiO3 doped with 0.2, 0.4, 0.6, 0.8 mol% of Nb and 0.01 mol% of Mn based compounds was studied. Doped barium titanate was prepared using the polymeric precursor method from citrate solutions. The powders calcined at 700°C for 4 hours were analysed by infrared (IR) spectroscopy to verify the presence of carbonates, and by X-ray diffraction (XRD) for phase formation. The phase composition, microstructure and dielectric properties show a strong dependence on the amount of added niobium.

Structure and Physical Properties of EVA/Starch Precursor Materials for Foaming Applications

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

Development on polymeric precursor routes to produce superconducting nanoparticles

The well-known polymeric precursor route is a simple and low-cost sol-gel method based on the preparation of an aqueous precursor solution of metals followed by the addition of a water-soluble polymer. This method consists of a polyesterification process between a metal chelate complex by using a hydroxycarboxylic acid and a polyhydroxy alcohol. In this work, citric acid (CA), tartaric acid (TA) and ethylenediaminetetraacetic acid (EDTA) are used as the hydroxycarboxylic acid and ethylene glycol (EG) is used as the polyhydroxy alcohol. The effects of the precursor pH solution, time and temperature of polymerization step as well as the combination of different chelating agents in order to obtain nanoscopic YBa2Cu3Oy samples were traced. (c) 2007 Elsevier B.V. All rights reserved.

Structural and morphological characteristics of (Pb1-x Sr (x) )TiO3 powders obtained by polymeric precursor method

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)