Deposition and photo-induced electrical resistivity of dip-coated NiO thin films from a precipitation process

Thin films of the semiconductor NiO are deposited using a straightforward combination of simple and versatile techniques: the co-precipitation in aqueous media along with the dip- coating process. The obtained material is characterized by gravimetric/differential thermal analysis (TG-DTA) and X-ray diffraction technique. TG curve shows 30 % of total mass loss, whereas DTA indicates the formation of the NiO phase about 578 K (305 C). X-ray diffraction (XRD) data confirms the FCC crystalline phase of NiO, whose crystallinity increases with thermal annealing temperature. UV-Vis optical absorption measurements are carried out for films deposited on quartz substrate in order to avoid the masking of bandgap evaluation by substrate spectra overlapping. The evaluated bandgap is about 3.0 eV. Current-voltage (I-V) curves measured for different temperatures as well as the temperature-dependent resistivity data show typical semiconductor behavior with the resistivity increasing with the decreasing of temperature. The Arrhenius plot reveals a level 233 meV above the conduction band top, which was attributed to Ni2+ vacancy level, responsible for the p-type electrical nature of NiO, even in undoped samples. Light irradiation on the films leads to a remarkable behavior, because above bandgap light induced a resistivity increase, despite the electron-hole generation. This performance was associated with excitation of the Ni 2+ vacancy level, due to the proximity between energy levels. © 2012 Springer Science+Business Media New York.

Local order of Pb1-xLaxZr0.40Ti 0.60O3 ferroelectric ceramic materials probed by X-ray absorption and Raman spectroscopies

This paper reports on the structural characterization of Pb 1-xLaxZr0.40Ti0.60O3 (PLZT) ferroelectric ceramic compositions prepared by the conventional solid state reaction method. X-ray absorption spectroscopy (XAS) and Raman spectroscopy were used to probe the local structure of PLZT samples that exhibits a normal and relaxor ferroelectric behavior. From the Zr K-edge and Pb LIII-edge EXAFS spectra, a considerable dissymmetry of Zr and Pb sites was observed in all samples, including those showing a long-range order cubic symmetry and a relaxor behavior. The Raman spectroscopy results confirmed the existence of a local disorder in all PLZT samples through the observation of Raman active vibrational modes. The variation in the intensity of the E(TO 3) mode in the PLZT relaxor samples indicates that the process of correlation between nanodomains stabilizes at temperatures lower than T m. © 2013 Elsevier B.V. All rights reserved.

Surfactant-cosurfactant interactions and process parameters involved in the formulation of stable and small droplet-sized benznidazole-loaded soybean O/W emulsions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Incorporation of hydrogen production process in a sugar cane industry: Steam reforming of ethanol

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Combined photoelectrocatalytic/electro-Fenton process using a Pt/TiO2NTs photoanode for enhanced degradation of an azo dye: A mechanistic study

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Alteração da fertilidade do solo como indicador do processo de antropização e presença de atividades não agrícolas no assentamento rural Horto Aimorés, municípios de Bauru e Pederneiras/SP =: Change of soil fertility as an indicator of the anthropization process and presence of non agricultural activities at the rural settlement Horto Aimorés, cities of Bauru and Pederneiras/ SP

Pós-graduação em Geografia - FCT

Grinding process monitoring based on electromechanical impedance measurements

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A relationship between structural and electronic order-disorder effects and optical properties in crystalline TiO2 nanomaterials

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

Biossorção & biodegradação de azo corante: desenvolvimento de processos utilizando resíduos como fonte de microorganismos = Azo dye biosorption & biodegradation : process development with residues as source of microorganisms

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A sewage sludge co-composting process using respirometric monitoring method in hermetic rotary reactor

This paper has the objective of monitoring the biological activity of composting process of sewage sludge, sugarcane bagasse and ground coffee in a hermetic rotary reactor using the respirometric method in laboratory scale, in order to obtain parameters and system design for large scale projects. Another particularity of this study is the use of a hermetic reactor with gas purging cycles. Purging was performed when the percentage of oxygen reached less than 5%, thus eliminating the gaseous mixture (with elevated CO2 ratio) and the introduction of environmental air with around 21% of O2, successively until the compost was stabilized. The average purge intervals obtained were 29 h and 2 min with reactor rotation frequency of 15 min. The time of the compost stabilization was optimized in 60% if compared to the 90 days in the traditional method. The results obtained can be used to design the process in industrial scale using a simple O2 gas analyzer.