Rietveld analyses and piezoelectric properties of niobium doped bismuth titanate systems

Bi 4Ti 3- xNbxO 12 (BITNb) samples, with × ranging from 0 to 0.40 were obtained using a polymeric precursor solution. Rietveld analyses confirmed that the powders crystallize in an orthorhombic structure free of secondary phases with space group Fmmm. Raman analysis evidenced a sharp increase in the bands intensity located at 129 cm -1 and 190 cm -1 due the lattice distortion in BIT02Nb and BIT04Nb compositions. UV-vis spectra indicated that addition of niobium causes a reduction of defects in the BIT lattice due the suppression of oxygen vacancies located at BO-6 octahedral. Size and morphology of particles as well as electrical behavior of BIT ceramics were affected by addition of donor dopant. Polarization reversal was investigated by applying dc voltage through a conductive tip during the area scanning and was investigated by piezoresponse force microscopy (PFM). PFM measurements revealed a decrease in piezoelectric response with increasing Nb concentration originating from a reduced polarizability along the a-axis. High spontaneous polarization is noted for the less doped sample due the reduction of strain energy and pin charged defects after niobium addition. Copyright © 2010 American Scientific Publishers.

A novel LTCC electrochemical cell construction and characterization: A detection compartment for portable devices

In this work we described for the first time the construction of a 25 μL electrochemical cell from low temperature co-fired ceramic (LTCC) material and carbon screen-printed electrode applicable in portable devices. Firstly, a carbon screen-printed electrode was prepared and characterized by cyclic voltammetry and scanning electron microscopy. Afterwards carbon polymeric film and metal pastes were dropped into the LTCC cell cavities in order to determine the device electrodes, and this arrangement was also electrochemically characterized. The great advantage of this promising device is the simple construction method and its widespread applicability in reusable portable devices. © 2013 The Royal Society of Chemistry.

Structural and electrical properties of LaNiO3 thin films grown on (100) and (001) oriented SrLaAlO4 substrates by chemical solution deposition method

LaNiO3 thin films were deposited on SrLaAlO4 (1 0 0) and SrLaAlO4 (0 0 1) single crystal substrates by a chemical solution deposition method and heat-treated in oxygen atmosphere at 700° C in tube oven. Structural, morphological, and electrical properties of the LaNiO 3 thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and electrical resistivity as temperature function (Hall measurements). The X-ray diffraction data indicated good crystallinity and a structural preferential orientation. The LaNiO3 thin films have a very flat surface and no droplet was found on their surfaces. Samples of LaNiO3 grown onto (1 0 0) and (0 0 1) oriented SrLaAlO4 single crystal substrates reveled average grain size by AFM approximately 15-30 nm and 20-35 nm, respectively. Transport characteristics observed were clearly dependent upon the substrate orientation which exhibited a metal-to-insulator transition. The underlying mechanism is a result of competition between the mobility edge and the Fermi energy through the occupation of electron states which in turn is controlled by the disorder level induced by different growth surfaces. © 2013 Elsevier Ltd and Techna Group S.r.l.

Fases magnéticas em compostos Er'Co IND. x''Mn IND. 1-x''O IND> 3+ou - δ'

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Preparação e caracterização de filmes finos do tipo 'Pb IND. 1-x-yCa IND. xSr IND.yTiO IND. 3'

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

Production and characterization of natural rubber-Ca/P blends for biomedical purposes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A simple and fast method for assessment of the nitrogen-phosphorus-potassium rating of fertilizers using high-resolution continuum source atomic and molecular absorption spectrometry

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

A simple method based on ICP-MS for estimation of background levels of arsenic, cadmium, copper, manganese, nickel, lead, and selenium in blood of the Brazillian population

Throughout the world, biomonitoring has become the standard for assessing exposure of individuals to toxic elements as well as for responding to serious environmental public health problems. However, extensive biomonitoring surveys require rapid and simple analytical methods. Thus, a simple and high-throughput method is proposed for the determination of arsenic (As), cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and selenium (Se) in blood samples by using inductively coupled plasma–mass spectrometry (ICPMS). Prior to analysis, 200 ml of blood samples was mixed with 500 ml of 10% v/v tetramethylammonium hydroxide (TMAH) solution, incubated for 10 min, and subsequently diluted to 10 ml with a solution containing 0.05% w/v ethylenediamine tetraacetic acid (EDTA) + 0.005% v/v Triton X-100. After that, samples were directly analyzed by ICP-MS (ELAN DRC II). Rhodium was selected as an internal standard with matrix-matching calibration. Method detection limits were 0.08, 0.04, 0.5, 0.09, 0.12, 0.04, and 0.1 mg//L for As, Cd, Cu, Mn, Ni, Pb, and Se, respectively. Validation data are provided based on the analysis of blood samples from the trace elements inter-\comparison program operated by the Institut National de Santé Publique du Quebec, Canada. Additional validation was provided by the analysis of human blood samples by the proposed method and by using electrothermal atomic absorption spectrometry (ETAAS). The method was subsequently applied for the estimation of background metal blood values in the Brazilian population. In general, the mean concentrations of As, Cd, Cu, Mn, Ni, Pb, and Se in blood were 1.1, 0.4, 890, 9.6, 2.1, 65.4, and 89.3 mg/L, respectively, and are in agreement with other global populations. Influences of age, gender, smoking habits, alcohol consumption, and geographical variation on the values were also considered. Smoking habits influenced the levels of Cd in blood. The levels of Cu, Mn, and Pb were significantly correlated with gender, whereas Cu and Pb were significantly correlated with age. There were also interesting differences in Mn and Se levels in the population living in the north of Brazil compared to the south.

Chitosan nanoparticles loaded the herbicide paraquat: The influence of the aquatic humic substances on the colloidal stability and toxicity

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

Maize leaf phytotoxicity and grain yield are affected by nitrogen source and application method

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Rietveld refinement and optical properties of SrWO4:Eu3+ powders prepared by the non-hydrolytic sol-gel method

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Synthesis and characterization of polyarylacetylene for use in the monolithic vitreous carbon processing

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