Synthesis of slightly < 111 >-oriented 0.65Pb(Mg1/3Nb2/3)O-3-0.35PbTiO(3) ceramic prepared from fine powders

Slightly < 111 >-oriented 0.65Pb(Mg1/3Nb2/3)03-0.35PbTiO(3) ceramic was prepared using fine powders obtained by means of an alternative and promising chemical oxide precursor method. High quality samples with improved structural, microstructural, dielectric and ferroelectric properties were obtained. The dielectric constant value (epsilon similar to 2577) measured at 1 kHz is compared to unpoled < 112 > grain-oriented ceramics while the remanent polarization (P-r similar to 19-1 mu cm(-2)) is compared with random grain-oriented ceramics. These results point out the viability to produce ferroelectric PMN-PT ceramics of very good quality using powder precursors prepared from this chemical method. (c) 2007 Elsevier B.V. All rights reserved.

The interaction between atoms of Au and Cu with clean Si(111) surface: A study combining synchrotron radiation grazing incidence X-ray fluorescence analysis and theoretical calculations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Microstructural and transport properties of LaNiO3-delta films grown on Si(111) by chemical solution deposition

Electrically conductive LaNiO3-delta (LNO) thin films with typical thickness of 200 nm were deposited on Si (111) substrates by a chemical solution deposition method and heat-treated in air at 700 degreesC. Structural, morphological, and electrical properties of the LNO thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field-emission scanning electron microscopy (FEG-SEM), and electrical resistivity rho(T). The thin films have a very flat surface and no droplet was found on their surfaces. The average grain size observed by AFM and FEG-SEM was approximately 100 nm in excellent agreement with XRD data. The rho(T) data showed that these thin films display a good metallic character in a large range of temperature. These results suggest the use of this conductive layer as electrode in the integration of microelectronic devices. (C) 2003 Elsevier B.V. All rights reserved.

Influence of heat treatment on LiNbO3 thin films prepared on Si(111) by the polymeric precursor method

The effects of heat-treatment temperature on LiNbO3 thin films prepared by the polymeric precursor method were investigated. The precursor solution was deposited on Si(111) substrates by dip coating. X-ray diffraction and thermal analyses revealed that the crystallization process occurred at a low temperature (420 °C) and led to films with no preferential orientation. High-temperature treatments promoted formation of the LiNb3O8 phase. Scanning electron microscopy, coupled with energy dispersive spectroscopy analyses, showed that the treatment temperature also affected the film microstructure. The surface texture - homogeneous, smooth, and pore-free at low temperature - turned into an `islandlike' microstructure for high-temperature treatments.

O valor mágico do olhar no capítulo 35 do livro I do 'Opus agriculturae' de Paládio

Blood is one of the most important and powerful elements in magical and religious symbology. As it is an essential substance for animal survival, it does not sound strange that through the ages blood has been given many significant symbolic values (both positive and negative). It can provide life, protection and prosperity in the same proportion that it can cause calamities, destruction and even death. In Opus agriculturae, a farming treatise written by Palladius (V AD), more specifically in Book I, Chapter 35, the author presents prescriptions to protect farms against scourges and climatic phenomena. He mentions some procedures in which blood is a fundamental component in the success of the prescriptions. The aim of the present article is to identify any magic power associated with these practices, their specific symbolic value, especially when related to menstrual blood and to other feminine elements with some magical or religious value. An evaluation is also made of the extent of these symbologies in the context of other practices and situations linked not only to agricultural magic, but to religion and to the ritual practices of other communities, whether in ancient times or not.

A magia em um texto técnico agronômico da antiguidade romana: o 'Opus agriculturae', de Paládio

This work analyses the chapter 35, book I, of the agricultural treatise Opus agriculturæ, written by Rutilius Taurus Aemilianus Palladius (V C.E.). In that chapter the author presents some recipes, called remedia, to protect the farm and the garden against weeds and weather phenomena, as blight and fogs. The magical practices are identified according to both the fundamental principles of magic (similarity, contiguity, contrariety), which rule magical thought, and some elements of magical symbology. As the author seems not to distinguish magic and science, for he brings together both kinds of recipes, the analysis of some remedia emphasizes a specific study on the materials and substances employed in those recipes and their value in Science today. This leads to the discussions of how magical thought works, what are the limits (if they actually exist) between Magic and Science and between Magic and Religion. This work covers the subjects above and it has the following pourposes: demonstrate the characteristics that authorize the remedia described by Palladius to be classified as folk magic; identify the relations between this kind of practice with more complex forms of magic, as with religion, with science; demonstrate the contribution of the folk magic in ancient Rome farming for the formulation of more apropriated criteria of evaluating magic in comparison to religious and scientific thought.

O valor mágico do sangue no capítulo 35 do livro I do 'Opus Agriculturae' , de Paládio

Blood is one of the most important and powerful elements in magical and religious symbology. As it is an essential substance for animal survival, it does not sound strange that through the ages blood has been given many significant symbolic values (both positive and negative). It can provide life, protection and prosperity in the same proportion that it can cause calamities, destruction and even death. In Opus agriculturae, a farming treatise written by Palladius (V AD), more specifically in Book I, Chapter 35, the author presents prescriptions to protect farms against scourges and climatic phenomena. He mentions some procedures in which blood is a fundamental component in the success of the prescriptions. The aim of the present article is to identify any magic power associated with these practices, their specific symbolic value, especially when related to menstrual blood and to other feminine elements with some magical or religious value. An evaluation is also made of the extent of these symbologies in the context of other practices and situations linked not only to agricultural magic, but to religion and to the ritual practices of other communities, whether in ancient times or not.

Oxidation of ethanol and its derivatives on well defined pt single crystal electrodes vicinal to pt(111): a comparative study

The oxidation of ethanol (EtOH) at Pt(111) electrodes is dominated by the 4e path leading to acetic acid. The inclusion of surface defects such as those present on stepped surfaces leads to an increase of the reactivity towards the most desirable 12e path leading to CO2 as final product. This path is also favored when the methyl group is more oxidized, as in the case of ethylene glycol (EG) that spontaneously decomposes to CO on Pt(111) electrodes, thus showing a more effective breaking of the C-C bond. Some trends in reactivity can be envisaged when other derivative molecules are compared at well-ordered electrodes. This strategy was used in the past, but the improvement in the electrode pretreatment and the overall information available on the subject suggest that relevant information is still missing.