LiNbO3 thin films prepared through polymeric precursor method

Thin films of lithium niobate were deposited on (100) silicon by the polymeric precursor method (Pechini method). Annealing in static air was performed at 500degreesC for 3 h. The films obtained were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Electrical characterization of the films pointed to ferroelectricity via hysteresis loop. The dielectric constant, dissipation factor and resistance were measured in the frequency region from 10 Hz to 10 MHz. At 1 MHz, the dielectric constant was 46 and the dissipation factor was 0.043. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Ferroelectric characteristics of SrBi4Ti4O15 thin films grown on Pt/Ti/SiO2/Si substrates by the soft chemical method

Ferroelectric SrBi4Ti4O15 thin films were successfully prepared on a Pt(111)/Ti/SiO2/Si(100) substrate for the first time by spin coating, using the polymeric precursor method. X-ray diffraction patterns of the films indicate that they are polycrystalline in nature. Atomic force microscopy (AFM) analyses showed that the surface of these films is smooth, dense and crack-free with low surface roughness (6.4 nm). At room temperature and at a frequency of 1 MHz, the dielectric constant and the dissipation factor were, respectively, 150 and 0.022. The C-V characteristics of perovskite thin film prepared at low temperature show normal ferrolectric behaviour. The remanent polarization and coercive field for the films deposited were 5.4 mu C/cm(2) and 8 5 kV/cm, respectively. All the capacitors showed good polarization fatigue characteristics at least up to 1 x 10(10) bipolar pulse cycles indicating that SrBi4Ti4O15 thin films can be a promising material for use in nonvolatile memories. (c) 2005 Elsevier B.V. All rights reserved.

Ferroelectric and dielectric properties of Ba0.5Sr0.5(Ti0.80Sn0.20)O-3 thin films grown by the soft chemical method

Polycrystalline Ba0.5Sr0.5(Ti0.80Sn0.20)O-3 (BST:Sn) thin films with a perovskite structure were prepared by the soft chemical method on a platinum-coated silicon substrate from spin-coating technique. The resulting thin films showed a dense structure with uniform grain size distribution. The dielectric constant of the films estimated from C-V curve is around 1134 and can be ascribed to a reduction in the oxygen vacancy concentration. The ferroelectric nature of the film indicated by butterfly-shaped C-V curves and confirmed by the hysteresis curve, showed remnant polarization of 14 mu C/cm(2) and coercive field of 74 kV/cm at frequency of 1 MHz. At the same frequency, the leakage current density at 1.0 V is equal to 1.5 x 10(-7) A/cm(2). This work clearly reveals the highly promising potential of BST:Sn for application in memory devices. (c) 2006 Elsevier B.V. All rights reserved.

Structural and spectroscopic characterization of Al2-xCrxO3 powders obtained by polymeric precursor method

Al2O3 and Al2-x Cr (x) O-3 (x = 0.01, 0.02 and 0.04) powders have been synthesized by the polymeric precursors method. A study of the structural evolution of crystalline phases corresponding to the obtained powders was accomplished through X-Ray Diffraction and UV-vis spectroscopy (reflectance spectra and CIEL* a*b* color data). The obtained results allow to identify the gamma-Al2O3 to alpha-Al2O3 phase transition. The single-phase alpha-Al2O3 powder was obtained after heat treatment at 1050 degrees C for 2 h. The results show that the green to red color transition and ruby luminescence lines observed for the powders of Al2-x Cr (x) O-3 are related to the gamma to alpha-Al2O3 phase transition and the temperature and time range for such transition depends on the chromium content.

Characterization of lanthanum-doped bismuth titanate thin films prepared by polymeric precursor method

Lanthanum-modified bismuth titanate, Bi4-xLaxTi3O12 (BLT), with x ranging from 0 to 0.75 was grown on Pt/Ti/SiO2/Si substrates using a polymeric precursor solution and spin-coating method. The dielectric constant of highly doped bismuth titanate was equal to 148 while dielectric losses remained low (tan delta = 0.0018), and the films showed well-saturated polarization-electric field curves (2P(r) = 40.6 muC/cm(2) and V-c = 0.99 V). The leakage current densities improve for the lanthanum-doped system. For five-layered BLT films with x = 0.75, a charge storage density of 35 fC/mum(2) and a thickness of 320 nm were found. (C) 2004 Elsevier B.V. All rights reserved.

NiTiO3 powders obtained by polymeric precursor method: Synthesis and characterization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Room temperature photoluminescence of BCT prepared by Complex Polymerization Method

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Dielectric investigations of vanadium modified barium zirconium titanate ceramics obtained from mixed oxide method

Vanadium modified barium zirconium titanate ceramics Ba(Zr(0.10)Ti(0.90))O(3):2V (BZT:2V) were prepared from the mixed oxide method. According to X-ray diffraction analysis, addition of vanadium leads to ceramics free of secondary phases. Electrical characteristics reveal a dielectric permittivity at around 15,000 with low dielectric loss with a remnant polarization (P(r))of 8 mu C/cm(2) at 2 kV/cm. From the obtained results, we assume that vanadium substitution in the BZT lattice affects dielectric characteristics due to the electron-relaxation-mode in which carriers (polarons, protons, and so on) are coupled with existing dielectric modes. (C) 2009 Published by Elsevier B.V.

Piezoresponse behavior of niobium doped bismuth ferrite thin films grown by chemical method

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

ZnO architectures synthesized by a microwave-assisted hydrothermal method and their photoluminescence properties

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

CuO urchin-nanostructures synthesized from a domestic hydrothermal microwave method

This letter reports the synthesis of CuO urchin-nanostructures by a simple and novel hydrothermal microwave method. The formation and growth of urchin-nanostructures is mainly affected by the addition of polyethylene glycol (PEG). The hierarchical malachite particles are uniform spheres with a diameter of 0.7-1.9 mu m. CuO urchin-nano structures were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FEG-SEM) and nitrogen adsorption (BET). The specific surface area of the CuO nanostructured microspheres was about 170.5 m(2)/g. A possible mechanism for the formation of such CuO urchin-nanostructures is proposed. (c) 2007 Elsevier Ltd. All rights reserved.

Synthesis and characterization of mesoporous TiO2 nanostructured films prepared by a modified sol-gel method for application in dye solar cells

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

A simple and green analytical method for determination of glyphosate in commercial formulations and water by diffuse reflectance spectroscopy

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

An environmentally friendly reflectometric method for ranitidine determination in pharmaceuticals and human urine

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Development of an HPLC-UV/Vis method for the determination of dyes in a gasoline sample employing different pre-treatments

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