Gas sensor applications of zinc oxide thin film grown by the polymeric precursor method

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mechanisms of phase formation along the synthesis of Mn-Zn ferrites by the polymeric precursor method

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Synthesis and antimycobacterial activity of new pyrazolate-bridged dinuclear complexes of the type [Pd(mu-L)(N-3)(PPh3)](2) (PPh3 = triphenylphosphine; L = pyrazolates)

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

On the stability of the RuCl2(triphenylphosphine)(2)(amine) complexes: Ligand substituent effects of cyclic and acyclic amines

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

Development of organic-inorganic polymeric film formers for controlled drug release and wound care

Film forming polymeric systems represents a new and unexplored technology of systems forskin or wounds protection and for controlled drug release. The aim of this work was to study the use of polymeric organic-inorganic ureasil-polyether hybrids synthesized by the sol-gel process as film forming system containing silver sulfadiazine as model drug. The film formationtime can be controlled by changing the precursor/catalyst ratio used during the step of hydrolysis and condensations. The results showed that the precursor/catalyst proportion influences both the visual characteristics and time required to form the film. The precursor/catalyst ratio equal to 20.8 m/v was considered ideal due to promote the homogeneous and transparent film formation in less than 5 minutes. The release profile of sulfadiazine is dependent on the characteristics of the matrixes: matrix more hydrophobic as ureasil-POP provided a slowed released mainly due to the low swelling of the matrix. The more hydrophilic ureasil-POE matrix presents a large capacity to swell and favors the faster release of the drug. The set of results showed the possibility of future use of these systems for treating wounds caused by burns.

Polymeric alginate microspheres containing biochar to immobilize phosphate ions

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

Very Intense Distinct Blue and Red Photoluminescence Emission in MgTiO 3 Thin Films Prepared by the Polymeric Precursor Method: An Experimental and Theoretical Approach

MgTiO3 (MTO) thin films were prepared by the polymeric precursor method with posterior spin-coating deposition. The films were deposited on Pt(111)/Ti/SiO2/Si(100) substrates and heat treated at 350 °C for 2 h and then heat treated at 400, 450, 500, 550, 600, 650 and 700 °C for 2 h. The degree of structural order−disorder, optical properties, and morphology of the MTO thin films were investigated by X-ray diffraction (XRD), micro-Raman spectroscopy (MR), ultraviolet− visible (UV−vis) absorption spectroscopy, photoluminescence (PL) measurements, and field-emission gun scanning electron microscopy (FEG-SEM) to investigate the morphology. XRD revealed that an increase in the annealing temperature resulted in a structural organization of MTO thin films. First-principles quantum mechanical calculations based on density functional theory (B3LYP level) were employed to study the electronic structure of ordered and disordered asymmetric models. The electronic properties were analyzed, and the relevance of the present theoretical and experimental results was discussed in the light of PL behavior. The presence of localized electronic levels and a charge gradient in the band gap due to a break in the symmetry are responsible for the PL in disordered MTO lattice.

Effect of the iron doping on the thermal decomposition of the polymeric precursor for the titanium dioxide powder synthesis

The Polymeric Precursor Method has proved suitable for synthesizing reactive powders using low temperatures of calcination, especially when compared with conventional methods. However, during the thermal decomposition of the polymeric precursor the combustion event can be releases an additional heat that raises the temperature of the sample in several tens of degrees Celsius above the set temperature of the oven. This event may be detrimental to some material types, such as the titanium dioxide semiconductor. This ceramic material has a phase transition at around 600 ° C, which involves the irreversible structural rearrangement, characterized by the phase transition from anatase to rutile TiO2 phase. The control of the calcination step then becomes very important because the efficiency of the photocatalyst is dependent on the amount of anatase phase in the material. Furthermore, use of dopant in the material aims to improve various properties, such as increasing the absorption of radiation and in the time of the excited state, shifting of the absorption edge to the visible region, and increasing of the thermal stability of anatase. In this work, samples of titanium dioxide were synthesized by the Polymeric Precursor Method in order to investigate the effect of Fe (III) doping on the calcination stages. Thermal analysis has demonstrated that the Fe (III) insertion at 1 mol% anticipates the organic decomposition, reducing the combustion event in the final calcination. Furthermore, FTIR-PAS, XRD and SEM results showed that organic matter amount was reduced in the Fe (III)-doped TiO2 sample, which reduced the rutile phase amount and increased the reactivity and crystallinity of the powder samples.

New flexible and transparent solution-based germanium-sulfide polymeric materials

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Vegetal fibers in polymeric composites: a review

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

Thermal analysis of coordination compounds. Part 1. Thermodecomposition of nickel(II) triphenylphosphine complexes with halides, nitrate, and thiocyanate

The compounds [NiX 2(PPh 3) 2] (where X is Cl -, Br -, I -, NO - 3, NCS -; and PPh 3 is triphenylphosphine) were prepared and characterized by infrared and atomic absorption spectroscopies and by carbon and hydrogen analyses. Simultaneous thermogravimetric (TG) and derivative thermogravimetric (DTG) curves of these complexes were recorded in air. The decrease in mass observed indicates conversion of the complexes to oxides. The thermal decomposition of the halogen and nitrate complexes occurred in a number of steps; the thiocyanate complex decomposed in a single step. © 1994.

Ferroelectric and dielectric characteristics of Bi3.25La0.75Ti3O12 thin films prepared by the polymeric precursor method

The ferroelectric properties and leakage current mechanisms of preferred oriented Bi3.25La0.75 Ti3O12 (BLT) thin films deposited on La0.5Sr0.5CoO3 (LSCO) by the polymeric precursor method were investigated. Atomic force microscopy indicates that the deposited films exhibit a dense microstructure with a rather smooth surface morphology. The improved ferroelectric and leakage current characteristics can be ascribed to the plate-like grains of the BLT films. © 2006 Trans Tech Publications, Switzerland.

Polymeric and solid lipid nanoparticles for sustained release of carbendazim and tebuconazole in agricultural applications

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

Thermal analysis of coordination compounds. Part 3. Thermal decomposition of platinum complexes containing triphenylphosphine, triphenylarsine and triphenylstibine

Studies by thermogravimetric analysis (TG) and differential thermal analysis (DTA) of the complexes [PtCl2L2] (L is PPh3, AsPh3, SbPh3), [PtLn] (n = 3, L is SbPh3; n = 4, L is PPh3, AsPh3); [(PtL3)2N2]; [(PtL3)2C2] and [Pt(CO)2L2] (L is SbPh3) are described. Analysis of the TG and DTA curves showed that Pt(II) complexes of the type [PtCl2L2] have a higher thermal stability than the corresponding Pt(0) complexes of the type [PtLn], with the exception of [Pt(SbPh3)3], which is more stable than [PtCl2(SbPh3)2]. Thermal stabilities of each of the complexes are compared with those of the others in the series. Mechanisms of thermal decomposition of complexes of the types [PtCl2L2] and [PtLn] are proposed. Residues of the samples were characterized by chemical tests and IR spectroscopy. The residue from the thermal decomposition of [PtCl2L2] (L is PPh3, AsPh3) and [Pt(PPh3)4] is metallic platinum. For [Pt(AsPh3)4] the residue is a mixture of Pt and As, whereas for the complexes containing SbPh3 the residues are mixtures of Pt and Sb. In these cases, the proportional contents of Pt and As or Pt and Sb correspond to the stoichiometry of these elements in the respective complexes. The complexes {[Pt(SbPh3)3]2N2}, {[Pt(SbPh3)3]2C2} lose N2 or the ethynediyl group at 130-150°C and are transformed into [Pt(SbPh3)3]. © 1995.

Influence of Mg on the structural and optical properties of LiNbO3 thin films grown by polymeric precursor method

A polymeric precursor solution was used to deposit pure and Mg doped LiNbO3 thin films on sapphire substrates by spin-coating. The effects of magnesium addition on crystallinity, morphology and optical properties of the annealed films were investigated. X-ray diffraction patterns indicate the oriented growth of the films. Phi-scan diffraction evidenced the epitaxial growth with two in-plane variants. AFM studies show that the films are very homogeneous, dense and present smooth surfaces. The refractive index and optical losses obtained by the prism coupling method were influenced by the magnesium addition.