(Bi4−xLax)Ti3O12 (abbreviated as BLT) thin films were prepared by Sol-Gel processing method with the initial materials of bismuth nitrate (Bi(NO3)3·5H2O), lanthanum nitrate (La(NO3)3·6H2O), and tetrabutyl titanate ((C4H9O)4Ti). The X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) studies were performed for determining the change of the crystal lattice constant, the surface morphology, the chemical composition of the films, and the chemical bonding energy of the ions in the films. It was found that BLT thin films have high c-axis orientation with monoclinlic structure, and the crystal lattice constants of the films are different from those reported in the literature. The a and b values of the lattice remain constant, but the c value reduces with an increasing lanthanum content x. The chemical composition of the films, and chemical bonding energy of bismuth and lanthanum ions in the near surface region are different from those in the inside region of the films. The films are bismuth enriched in the surface region, and the composition in the “bulk” region is agreement with the stoichiometry.
Abstract Lanthanum doped bismuth titanate (Bi3.5La0.5Ti3O12, BLT-5) thin films were prepared by sol-gel method. Polycrystalline BLT-5 thin films could be obtained at annealing temperatures of 600∼650 °C. The typical coercive electric field (Ec ) and remnant polarization (Pr ) for the BLT-5 thin film annealed at 650 °C were Ec =67 kV/cm, Pr =11.2 μ C/cm2, respectively. BLT-5 thin film shows good fatigue-free property.
Abstract X-ray photoelectron spectroscopy as well as Auger electron spectroscopy studies were used for determining the chemical composition, compositional depth profile, and the chemical bonding of ferroelectric (Pb, La)TiO3 thin films deposited by RF magnetron sputtering technique. It was found that the chemical composition of the films and the chemical bondings of titanium in the near surface region are different from those in the ‘‘bulk'’ region of the films. The titanium atoms exist mainly in the forms of TiO and PbTiO3 in the near surface region, whereas in the bulk region, the chemical composition is in good agreement with stoichiometry and titanium atoms exist in the form of PbTiO3. The lead atoms exists in the form of PbTiO3 near the surface and in the ‘‘bulk'’ of the films.
This paper analyzes the structure, the operating characteristics and the control strategy of microgrid. Based on the requirements of power quality and research achievements of the traditional power system, it is considered to introduce the Dynamic Voltage Restorer (DVR) in power distribution system with microgrid to improve the power quality. A method to detect voltage sags is presented, which incorporates morphological low-pass filters with the d-q transformation. A simulation model of the DVR based on PSCAD/EMTDC is proposed. Combining with the microgrid model, the simulation results prove that the topology and control strategy of DVR is correct and effective. (5 pages)
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