11 Result(s)
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Article
J. DE FRUTOS
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Article
Effects of grain boundary width and crystallite size on conductivity and magnetic properties of magnetite nanoparticles
The structural, electrical, and magnetic properties of magnetite nanoparticles, with crystallite sizes 30, 40, and 50 nm, are studied. These crystallite sizes correspond to average particle sizes of 33, 87, an...
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Sequential Characterization of the Hydration Products of Cements with Additions by a Combination of Destructive and Non-Destructive Techniques: Calorimetry, XRD, AFM and EIS
In this paper a comparative study of the hydration process in a very early age, first 20 hours, between a conventional cement paste and its equivalent with a replacement of fly ash of about 7.9%, is done. The ...
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Phase transitions in PbTixHf1-xO3 determined by thermal analysis and impedance spectroscopy
The objective of this study is to determine the influence of partial substitutions of Ti4+ by isovalent Hf4+ in the perovskite-type crystalline structure of PbTiO3. Different samples over the whole composition ra...
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The influence of area/volume ratio on microstructure and non-Ohmic properties of SnO2-based varistor ceramic blocks
This work deals with the electrical properties of SnO2-based varistor systems with different area–volume (A/V) ratio of the green compact. The influence of A/V ratio specially on microstructural homogeneity and d...
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Bulk Grain Resistivity of ZnO-Based Varistors
We study the temperature dependence of grain resistivity in ZnO ceramic varistors (300–430 K), finding a positive temperature coefficient (PTC). We devise a high-frequency procedure that allow us to obtain the...
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Non-uniform distribution of polarization in Pb0.76Ca0.24(Co0.5W0.5)0.05Ti0.95O3 ceramics produced by defects
Polarization distribution of calcium-modified lead titanate ceramics with a nominal composition of Pb0.76Ca0.24(Co0.5W0.5)0.05Ti0.95O3 was measured from the thermocurrents stimulated in these materials by a sinus...
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Accuracy and conservation properties in numerical integration: the case of the Korteweg-de Vries equation
When numerically integrating time-dependent differential equations, it is often recommended to employ methods that preserve some of the invariant quantities (mass, energy, etc.) of the problem being considered...
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Thermal expansion anomalies at the antiferroelectric-- ferroelectric (FRL), ferroelectric (FRL)--ferroelectric (FRH) and ferroelectric (FRH)--paraelectric transitions in PbZr1−xTixO3 (0) < x < 0.35
Abstracts are not published in this journal
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A study of ionic defects in modified lead titanate ceramics
Pb1−xCax[(Co0.5W0.5)0·05Ti0.95]O3 ceramics with x = 0.24, 0.30 and 0.35, are prepared by a solid state reaction of oxides. Deviations from nominal chemical compositions and formation of segregated phases differen...
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Non-stoichiometric lead titanate ceramics prepared by a wet-chemical processing
A wet-chemical method with an initial 1:1 molar ratio of lead to titanium was used for the preparation of non-stoichiometric lead titanate ceramics. Studies were made of the physicochemical evolution of this s...
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Chemical processing and microstructure of piezoelectric lead titanate ceramics
Lead titanate-based ceramics with different microstructures were prepared from PbO-TiO2 gels with equimolar and non-equimolar mixtures of the oxides. Deviations from the initial compositions were found in the sin...
