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Mustafa G.,Bahauddin Zakariya University | Islam M.U.,Bahauddin Zakariya University | Zhang W.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Jamil Y.,University of Agriculture at Faisalabad | And 3 more authors.
Journal of Alloys and Compounds | Year: 2014

Nanocrystalline samples of Ce3+substituted Co-Cr ferrite with chemical formula CoCr0.04CexFe1.96- xO4(0 ≤ x ≤ 0.1) have been synthesized by co-precipitation method and sintered at a temperature of 850 °C for 8 h. The samples were characterized using thermo-gravimetric and differential thermal analysis, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, atomic force microscopy and vibrating sample magnetometry. The XRD patterns and FTIR spectra confirm that the prepared samples reveal the formation of spinel ferrites. The average particle size was found to be in the range of 30.8-63.7 nm estimated by Scherer formula. The lattice constant varies in the range of 8.352-8.382 Å due to difference in the ionic radii of the substituted cations. IR studies confirm two main absorption bands in the frequency range of 400-800 cm-1arising due to the tetrahedral (A-site) and octahedral (B-site) stretching vibrations. The elemental analysis as obtained from the EDXS measurement is in close agreement with the expected composition from the stoichiometry of the reactant solutions. The M-H loops show that the saturation magnetization decreased gradually with increasing Ce content, while the coercivity is related to the microstructure of Ce-substituted samples. The obtained results suggest that the investigated materials are potential candidates for magnetic recording media, security, switching and high frequency applications. © 2014 Elsevier B.V. All rights reserved.

Zhen S.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Zhu X.,University of Electronic Science and Technology of China | Zhu X.,Texas Instruments | Luo P.,State Key Laboratory of Electronic Thin Films and Integrated Devices | And 2 more authors.
IEEE Transactions on Very Large Scale Integration (VLSI) Systems | Year: 2013

Modern low-power system on a chip needs direct current converter with dynamic voltage scaling (DVS) ability for core power supply. The converter output should be accurate voltage across the full load current and voltage scaling range. An integrated buck converter for DVS application is proposed in this brief. Voltage mode phase lead compensation is implemented in the converter, with much smaller passive components than conventional type-III compensation. To improve accuracy, the output voltage error accompanied with load current and reference voltage caused by finite loop gain in analog control loop is corrected by the digital error corrector. The output voltage is compared by two comparators whose threshold voltage is about 10 mV above and below the reference voltage, respectively. The duty cycle is slightly adjusted by finite state machine according to outputs of the two comparators. Experimental results show that the converter is well regulated over an output range of 0.7-1.8 V, with step voltage of 25 mV. When load current suddenly changes between 170 and 500 mA, the overshoot and undershoot voltage are 32 and 50 mV, respectively. Load regulation is maintained about 1% throughout the full load range. The voltage error is within ± 10 mV in the voltage scaling range. © 1993-2012 IEEE.

Tao Z.,University of Electronic Science and Technology of China | Tao Z.,State Key Laboratory of Electronic Thin Films and Integrated Devices | He W.,University of Electronic Science and Technology of China | Wang S.,University of Electronic Science and Technology of China | And 2 more authors.
Corrosion Science | Year: 2012

The nitrophenyltriazole derivative, namely 2-[1,2,4]-triazole-methyl-4-acetyl-5-nitrophenyl-[1,3,4]-oxadiazole (TMANO) was synthesized and its inhibiting action on the corrosion of mild steel in 0.5M H 2SO 4 solution was investigated by weight loss test, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and scanning electron microscopy (SEM). The selective desorption of TMANO from mild steel surface was also studied by the differential polarization curves. Both thermodynamic and kinetic parameters were calculated and discussed. The results showed that the adsorption of TMANO on steel surface obeys the Langmuir adsorption isotherm. The calculated values of ΔHads0 and ΔSads0 indicated that the adsorption process of TMANO on steel surface was exothermic and accompanied by a decrease in entropy. © 2012 Elsevier Ltd.

Che Y.-X.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Hou X.-Y.,State Key Laboratory of Electronic Thin Films and Integrated Devices
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2011

For planar periodic structure with finite thickness, the paper presents an algorithm, integral equations solved by method of moments (IE-MoM), making a quickly and effectively calculation of the electromagnetic characteristics. A detailed electromagnetic characteristics analysis is done about frequency selective surfaces (FSS) with four-legged loaded elements. The paper presents the reflection and transmission coefficients, radiation pattern, and surface electric field distribution for the FSS with different thickness. Through the analysis, it is found that the thickness of the metal screen makes a difference for the electromagnetic characteristics of the FSS in higher frequency resonant. In addition, a good agreement can be observed between the results of simulations obtained from our approach and with the commercial software HFSS. The computer time is also improved greatly. © 2011 by Editorial Department of Chinese Journal of Radio Science.

Che Y.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Hou X.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Zang P.,Shenyang Aircraft Design Institute
2010 9th International Symposium on Antennas Propagation and EM Theory, ISAPE 2010 | Year: 2010

A novel design for a multiple frequency selective surface (FSS) screens with dissimilar periodicities for directivity enhancement of a conventional dual-band patch antenna is presented. In the proposed new design, two square-loop arrays with different periodicity are placed above and below a thin dielectric layer. Using an efficient cascading procedure, several important parameters that characterize the thin FSS superstrate are investigated, and an optimal FSS array sizes was obtained. The directivity and radiation of an FSS antenna composite at two operating frequencies has been simulated. The results show that the proposed thin FSS superstrate yields 9.1 and 7.88 dB directivity enhancements at 7.9 GHz and 11.38 GHz, respectively, as compared to that of a patch antenna (5.91 dB, 4.47 dB), while its height is only one half of that of a conventional patch antenna and the thickness is only about 0.1 λ. ©2010 IEEE.

Deng X.-R.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Deng H.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Wei M.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Chen J.-J.,State Key Laboratory of Electronic Thin Films and Integrated Devices
Journal of Materials Science: Materials in Electronics | Year: 2012

Aluminum-doped ZnO (ZAO) thin films were deposited on fused quartz substrates by radio frequency sputtering in pure argon ambient at 450 °C. Effects of in situ annealing temperature and annealing atmosphere on microstructure, electrical and optical properties of ZAO films have been investigated. Results showed that as-grown film without annealing treatments attained lowest resistivity of 1.1 × 10 -4Ω cm. And all films performed high average transmittance greater than 90% in visible region. X-Ray diffraction (XRD), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS) were utilized to characterize the microstructure properties of films. XRD results indicated that as-grown film had higher crystalline quality and larger grain size than annealed films. Al atoms replaced Zn efficiently to provide electrons stable in all samples. PL spectra revealed that high annealing temperature and oxygen atmosphere would generate more Zn vacancy (V Zn) and oxide antisite defect (O Zn), respectively and composition content results from XPS provided supports to this. © 2011 Springer Science+Business Media, LLC.

Lin Z.,Chongqing University of Science and Technology | Cai W.,Chongqing University of Science and Technology | Jiang W.,Chongqing University of Science and Technology | Fu C.,Chongqing University of Science and Technology | And 3 more authors.
Ceramics International | Year: 2013

Bismuth ferrite thin films were prepared via sol-gel spin-coating method and the effects of annealing temperature on microstructure, optical, ferroelectric and photovoltaic properties have been investigated. The results show that the bismuth ferrite thin films annealed at 550 C is single phase and the grain size increases with the rise of annealing temperature. The band gap of bismuth ferrite thin films annealed at 550-650 C is between 2.306 eV and 2.453 eV. With the rise of the annealing temperature, the remnant polarization gradually decreases and the coercive electric field increases. The short circuit photocurrent density decreases with the rise of annealing temperature, and the open circuit photovoltage and the power conversion efficiency of bismuth ferrite thin films annealed at 550 C are higher than the thin films annealed at higher temperature. © 2013 Elsevier Ltd and Techna Group S.r.l.

Guo B.,China Electronics Technology Group Corporation | Zhang Q.,State Key Laboratory of Electronic Thin Films and Integrated Devices
Frequenz | Year: 2013

To improve thermal stability and relieve current convergence in rf power bjts, an embedded active CMOS ballast circuit is proposed. By detecting the inhomogeneous temperature through distributed temperature sensors, the adjacent ballast circuit is triggered to shunt the base convergence current of the power BJT cell, performing the ballast protection for the device. Simulations and measurements validate the effectiveness of the proposed ballast circuit. Compared to conventional ballast resistor methods, the improved device integrated with ballast circuits exhibits superior electrical performance. The single ballast circuit only consumes 6.5 mW with additional occupied area of 2530 um2.

Deng X.,State Key Laboratory of Electronic Thin Films and Integrated Devices | Deng H.,State Key Laboratory of Electronic Thin Films and Integrated Devices
Advanced Materials Research | Year: 2013

A simple solar-blind ultraviolet (UV) detector was fabricated by using Al0.3Zn0.7O alloy thin films as photocathode and ZnO:Al (AZO) thin film as transparent electrode. Transmission spectra of Al0.3Zn0.7O alloy thin film was characterized through spectrometer and result showed significant enlargement of its optical band gap value. This alloy film only absorbed illumination whose wavelength is below 280nm, and the UV on/off characteristics of this detector presented very clearly. Scanning electron microscope (SEM) image revealed fine structure of both layers and the interface of these two layers performed clear and uniform. © (2013) Trans Tech Publications, Switzerland.

Li C.,Liaocheng University | Wang M.,Liaocheng University | Wang M.,The Central Laboratory of Liaocheng Hospital | Cui C.,Liaocheng University | And 3 more authors.
International Journal of Electrochemical Science | Year: 2012

1,4-Bis(2-thienyl)-naphthalene (BTN) monomer is successfully synthesized via coupling reaction. Direct anodic oxidation of BTN monomer leads to the formation of a novel poly(1,4-bis(2-thienyl)-naphthalene) (PBTN) on a platinum wire in acetonitrile (ACN). The resultant polymer is investigated by cyclic voltammetry (CV) and characterized by FT-IR, 1H NMR, and UV-vis spectra. The oligomer of resultant polymer is soluble in N, N-dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). Fluorescence spectra studies reveal that PBNT is a green-light emitter (emission at 514 nm) and the photoluminescence (PL) quantum yield (Ø) is 0.235 in DMF solution. According to the spectroelectrochemical analyses, PBTN film presents multielectrochromic property and shows four different colors under various potentials. Electrochromic switching of PBTN film is performed and the polymer film shows a maximum optical contrast (ΔT %) of 24% at 700 nm in visible region with a response time of 1.78 s. The coloration efficiency (CE) of PBTN is calculated to be 124.8 cm 2 C -1. The multichromic polymer is thermally stable up to 496 °C. SEM images illustrate that the polymer film presents a porous structure.

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