598 research outputs found
The effects of composition gradients of BaxSr1-xTiO3 thin films on their microstructures, dielectric and optical properties
No full textFerroelectric thin films of BaxSr1-xTiO3 (BST) with artificial gradients in composition normal to the growth surface were prepared on Si and fused quartz substrates by a sol-gel technique. Auger electronic spectroscopy observation shows that composition gradients of Ba and Sr are gradual and uniform without obvious interfaces between the different layers. X-ray diffraction analysis reveals that polycrystalline and perovskite formed at 730degreesC. Annealing at higher temperature enhanced grain growth, the lattice parameter decreases with increasing annealing temperatures. The small signal dielectric constant and dielectric loss at 100 kHz were found to be 300 and 0.02. The graded thin film shows a relatively high tunability of 35% at an applied field of 240 kV cm(-1). The optical properties were determined at room temperature in the wavelength range of 200-2000 nm from spectrophotometer measurements of the transmittance. The transmittance of the graded thin films increased, and a much weaker and flatter absorption band was found in the absorption spectra. (C) 2003 Elsevier Science B.V. All rights reserved
Study of solid-state reaction of CaCO3 and RuO2 and fabrication of pseudocubic epitaxial thin films by e-beam evaporation
No full textPure CaRuO3 powders were prepared from solid-state reaction using stoichiometric RuO2 (99.9%) and CaCO3 (99.99%) powders. The process of the reaction was investigated employing thermogravimetry analysis and differential scanning calorimetry (TGA and DSC). The solid-state reaction rate increased when the compounds were heated in flowing air/oxygen, as it acted as a catalyst. The phase variations in samples heated at different temperatures were analyzed by X-ray diffraction (XRD) and the alignments of the films studied by XRD-rocking curves and pole-figures. The microstructures of powders were measured by scanning electron microscopy. Biaxially textured CaRuO3 thin films were formed at 700°C by e-beam evaporation, and they showed strong (0 0 1) orientation on SrTiO 3 (1 0 0) substrates.Department of Applied Physic
Metallorganic chemical vapor deposition of metallic Ru thin films on biaxially textured Ni substrates using a Ru(EtCp)2 precursor
No full textRuthenium (Ru) films on rolling-assisted biaxially textured Ni substrates (RABiTs) were deposited by liquid source chemical vapor deposition using bis-(ethyl-π-cyclopentadienyl)ruthenium (Ru(C2H5C 5H4)2). The thermal decomposition process of the precursor was investigated by Fourier transform infrared spectroscopy (FTIR), mass spectroscopy, and differential scanning calorimetry/ thermogravimetric analyses (DSC/TGA). The crystalline structure and resistivity of Ru thin films were investigated. The Ru films were polycrystalline and had a grainy structure. Although the thermal decomposition of the precursor required a sufficient amount of oxygen, the experimental results showed that up to a certain concentration of oxygen (i.e. O2/Ar ∼ 30/10), Ru metal film was deposited without any detectable RuO2 impurities. A higher deposition temperature and a higher ratio of O2/Ar will be beneficial to the growth of (0 0 2) orientation. They showed a low resistivity of about 10-20 μΩ cm, which is sufficiently low for them to be used as a buffer layer in superconductor tapes or electrode materials in dielectric capacitors.Department of Applied Physic
Structural and electrical characteristics of highly textured oxidation-free Ru thin films by DC magnetron sputtering
No full textTextured Ru thin films (∼120 nm) were deposited on Si and rolling-assisted biaxially textured Ni substrates by a DC magnetron sputtering technique with a two-step process. The biaxially textured pure Ni substrates with a thickness of 80 μm were fabricated by rolling followed by recrystallization. The alignments and the crystallinity of Ru films were analyzed by pole figures, as well as X-ray diffraction (θ - 2θ) analysis. The highly (0 0 2) oriented Ru films were fabricated on Si substrates, and four-fold symmetric Ru films on Ni(2 0 0) substrates. The resistivities of pure metallic Ru films were 20-80 μΩ cm for Ru on Si and 16-40 μΩ cm on Ni, respectively, which is sufficiently low to be used as a buffer layer in superconductor tapes or electrode materials in capacitor dielectrics.Department of Applied Physic
Magnetoelectric devices and methods of using same
No full textInventor name used in this publication: Siu Wing OrInventor name used in this publication: Helen Lai Wa Chan-WongUS7199495; US7199495 B2; US7199495B2; US7,199,495; US 7,199,495 B2; 7199495; Appl. No. 10/814,265USVersion of Recor
磁场增强压电悬臂梁震动发电装置
No full textAuthor name used in this publication: 韩权威Author name used in this publication: 严玲Author name used in this publication: 周金龙Author name used in this publication: 陈王丽华, Chan Helen Lam wahTitle in Traditional Chinese: 磁場增強壓電懸臂梁震動發電裝置Journal title in Traditional Chinese: 壓電與聲光2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishedVoR allowe
Driver for an ultrasonic transducer and an ultrasonic transducer
No full textUS7462960; US7462960 B2; US7462960B2; US7,462,960; US 7,462,960 B2; 7462960; Application No. 10/751,718Inventor name used in this publication: Siu Wing OrInventor name used in this publication: Helen Lai Wa Chan-WongUSVersion of Recor
相扩散阻挡法制备铁酸钴/改性钛酸铋钠0-3复合多铁性陶瓷
No full textAuthor name used in this publication: 韩权威, HAN Quan-WeiAuthor name used in this publication: PENG SongAuthor name used in this publication: 陈王丽华, Chan Helen Lai-WaTitle in Traditional Chinese: 相擴散阻擋法制備鐵酸鈷/改性鈦酸鉍鈉0-3複合多鐵性陶瓷Journal title in Traditional Chinese: 無機材料學報2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishedPublisher permissio
General study on piezoelectric transformer
No full textAuthor name used in this publication: Cheng K. W. E.Author name used in this publication: Kwok K. W.Power Electronics Research Center, Department of Electrical EngineeringAuthor name used in this publication: Chan H.Refereed conference paper2004-2005 > Academic research: refereed > Refereed conference paperVersion of RecordPublishedPublisher permissio
Mode coupling in lead zirconate titanate/epoxy 1-3 piezocomposite rings
No full textAuthor name used in this publication: S. W. OrAuthor name used in this publication: H. L. W. Chan2001-2002 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishedVoR allowe
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