Author
Jesús M. Siqueiros
Bio: Jesús M. Siqueiros is an academic researcher from National Autonomous University of Mexico. The author has contributed to research in topics: Dielectric & Ferroelectricity. The author has an hindex of 21, co-authored 158 publications receiving 1808 citations.
Topics: Dielectric, Ferroelectricity, Thin film, Ceramic, Permittivity
Papers published on a yearly basis
Papers
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TL;DR: In this paper, the presence of Fe2+, detrimental to the ferroelectric and magnetic performance, was evaluated by x-ray photoelectron spectroscopy, showing no structural differences, uniformly distributed grains, a ferro-paraelectric transition temperature at 110°C and a normal diffuse phase transition (nonrelaxor behavior).
Abstract: With the purpose of fabricating ceramics where ferroelectric and magnetic order coexist, ceramics of Pb(Fe1∕2Nb1∕2)O3 have been prepared using the traditional ceramic method following three different routes. The first is a direct via starting from oxide reagents and the other two use different kinds of FeNbO4 precursors with either monoclinic or orthorhombic structures. Crystallographic and surface morphological studies were carried out by the powder x-ray diffraction and scanning microscopy techniques. The presence of Fe2+, detrimental to the ferroelectric and magnetic performance, was evaluated by x-ray photoelectron spectroscopy. The samples showed no structural differences, uniformly distributed grains, a ferro-paraelectric transition temperature at 110°C and a normal diffuse phase transition (nonrelaxor behavior). Differences in the degree of diffuseness, densities and grain size were observed depending on the kind of precursor. Measurements of dc and ac electrical resistivity, dielectric constant an...
229 citations
TL;DR: In this article, the gallium-doped zinc oxide (ZnO:Ga) transparent-conducting thin films were grown on glass at different substrate temperatures, and a widening in the optical bandgap was observed in the films when the substrate temperature was raised from 150 °C to 300 °C, as determined from optical and electrical measurements.
147 citations
TL;DR: In this article, the dielectric behavior of ferroelectromagnetic Pb(Fe1∕2Nb1 ∕2)O3 ceramics obtained using the traditional ceramic method employing three different precursors was investigated by impedance spectroscopy in the temperature range of 200-300°C.
Abstract: The dielectric behavior of ferroelectromagnetic Pb(Fe1∕2Nb1∕2)O3 ceramics obtained using the traditional ceramic method employing three different precursors was investigated by impedance spectroscopy in the temperature range of 200–300°C. This study was carried out by means of the simultaneous analysis of the complex impedance Z, electric modulus M, and admittance Y functions from the measurements in the frequency range of 20Hz–1MHz. In correspondence to a previous structural, morphological, and temperature response study, appropriate microstructural and equivalent circuit models were established. Based on the brick layer model, three series of interconnected electrically distinct regions are considered: a conductive grain boundary layer, a capacitive grain boundary surface layer, and a resistive-ferroelectric bulk layer. Two conduction mechanisms were identified: a dielectric relaxation process due to localized conduction associated with the presence of oxygen vacancies and the nonlocalized conduction...
142 citations
TL;DR: In this paper, the authors used metallorganic chemical vapor deposition (MOCVD) and laser ablation to obtain a red fluorescence spectrum of Y2O3:Eu with the main peak centered about 611 nm wavelength.
124 citations
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TL;DR: Transparent conductors (TCs) have a multitude of applications for solar energy utilization and for energy savings, especially in buildings as discussed by the authors, which leads naturally to considerations of spectral selectivity, angular selectivity, and temporal variability of TCs, as covered in three subsequent sections.
1,471 citations
TL;DR: In the paragraph following eq 28, the average bond valence was incorrectly referred to as V/R, and this has been corrected to V/N.
Abstract: In the paragraph following eq 28, the average bond valence was incorrectly referred to as V/R. It has been corrected to V/N. The paper originally posted to the web on September 3, 2009, and was reposted on September 24, 2009.
878 citations
TL;DR: The electrocaloric effect (EC) is an adiabatic and reversible temperature change that occurs in a polar material upon application of an electric field as mentioned in this paper, and the current intensive research in EC materials has been driven by the quest for new energy efficient and environmentally friendly cooling technologies.
574 citations
TL;DR: In this paper, the structural, electrical, and optical properties of aluminum doped zinc oxide (AZO) films are investigated in terms of the preparation conditions, such as the Al2O3 content in the target, rf power, substrate temperature and working pressure.
Abstract: Aluminum doped zinc oxide (AZO) films are prepared by rf magnetron sputtering on glass or Si substrates using specifically designed ZnO targets containing different amount of Al2O3 powder as the Al doping source. The structural, electrical, and optical properties of the AZO films are investigated in terms of the preparation conditions, such as the Al2O3 content in the target, rf power, substrate temperature and working pressure. The crystal structure of the AZO films is hexagonal wurtzite. The orientation, regardless of the Al content, is along the c axis perpendicular to the substrate. The doping concentration in the film is 1.9 at. % for 1 wt % Al2O3 target, 4.0 at. % for 3 wt % Al2O3 target, and 6.2 at. % for 5 wt % Al2O3 target. The resistivity of the AZO film prepared with the 3 wt % Al2O3 target is ∼4.7×10−4 Ω cm, and depends mainly on the carrier concentration. The optical transmittance of a 1500-A-thick film at 550 nm is ∼90%. The optical band gap depends on the Al doping level and on the microstr...
563 citations
477 citations