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Jiang W.,Jilin Institute of Chemical Technology | Jin F.-L.,Jilin Institute of Chemical Technology | Park S.-J.,Inha University
Journal of Industrial and Engineering Chemistry | Year: 2012

This study examined the thermo-mechanical behavior of epoxy resins/nano-Al 2O 3 composites including the curing behavior, thermal stability, dynamic mechanical properties and thermal mechanical properties. The DSC curve peak temperature of the composites was decreased by the addition of nano-Al 2O 3. The thermal stability of the composites was similar to that of the neat epoxy resins. Dynamic mechanical analysis (DMA) indicated the glass transition temperature of the composites to be approximately 11°C higher than that of the neat epoxy resins. The coefficient of thermal expansion (CTE) of the composites decreased with increasing nano-Al 2O 3 content. © 2011 The Korean Society of Industrial and Engineering Chemistry.

Lu D.-Y.,Jilin Institute of Chemical Technology | Yue Y.,Jilin Institute of Chemical Technology | Sun X.-Y.,Jilin Institute of Chemical Technology
Journal of Alloys and Compounds | Year: 2014

(Ba1-xLax)(Ti1- x/2Cax/2)O3 (0.03 ≤ x ≤ 0.06) (BLTC) ceramics were prepared using a mixed oxides method. The structure, microstructure, and dielectric properties of BLTC were investigated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscope, and dielectric measurements. Both symmetric (2 0 0) XRD peak indicative of cubicity and sharp 308 cm-1 Raman band indicative of tetragonality are characteristics of pseudo-cubic symmetry of BLTC. The unit cell volume of BLTC increased linearly with x, satisfying Vegard's law. A strong "Raman charge effect" appeared at 836 cm-1 because of the aliovalent double substitution in BLTC. The x = 0.03 sample because of its higher permittivity (ε' = ∼2000) and lower loss (tan δ < 0.04) is a novel dielectric for X7R applications. The formation of LaBa-CaTi″-LaBa defect complexes was responsible for the dielectric-temperature stability of BLTC. © 2013 Elsevier B.V. All rights reserved.

Lu D.-Y.,Jilin Institute of Chemical Technology
Solid State Ionics | Year: 2015

Abstract Incorporation of Tb ions into the BaTiO3 lattice was studied on ceramic samples with 5% Tb and Ba/Ti ratios of 0.987-1.053, using electron paramagnetic resonance (EPR) in combination with X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), and dielectric measurements. The EPR results provided direct evidence of the existence of Tb ions at Ti sites as Tb4 +, which was characterized by a broad signal with g = ~ 6.5 and an increased concentration of Ti-site Tb4 + ions and a corresponding increase in the Ba/Ti ratio. The Raman charge effect at 805-833 cm- 1 and an EPR signal at g = 2.004 associated with ionized Ti-vacancy defects provided the evidence for the existence of Tb ions at Ba sites as Tb3 +. Because of the change in the Ba/Ti ratio, Tb ions in BaTiO3 exhibited a self-adjustable amphoteric behavior with the mixed valence states of Ba-site Tb3 + and Ti-site Tb4 + utilized to preserve lattice electroneutrality. The ceramic density, morphology of grains, dielectric properties, and Raman charge effect were sensitive to the Ba/Ti ratio. The sample with a Ba/Ti ratio of 0.987 has evident advantages: a higher density, smooth-surfaced grains, lower dielectric loss, and low-temperature dielectric stability approaching to an X5R specification. Defect chemistry of Tb-doped BaTiO3 is discussed. © 2015 Elsevier B.V. All rights reserved.

Jin F.-L.,Jilin Institute of Chemical Technology | Yop Rhee K.,Kyung Hee University | Park S.-J.,Inha University
Journal of Solid State Chemistry | Year: 2011

In this study, covalent functionalization of carbon nanotubes (CNTs) was accomplished by surface-initiated epoxide ring-opening polymerization. FT-IR spectra showed that polyether and epoxide group covalently attached to the sidewalls of CNTs. TGA results indicated that the polyether was successfully grown from the CNT surface, with the final products having a polymer weight percentage of ca. 1474 wt%. The O/C ratio of CNTs increased significantly from 5.1% to 29.8% after surface functionalization of CNTs. SEM and TEM images of functionalized CNTs exhibited that the tubes were enwrapped by polymer chains with thickness of several nanometers, forming coreshell structures with CNTs at the center. © 2011 Elsevier Inc. All rights reserved.

Yu J.,Jilin Institute of Chemical Technology
Proceedings - International Conference on Electrical and Control Engineering, ICECE 2010 | Year: 2010

The series resonant converter is a kind of DC to DC converter. The paper introduces the principle of the half bridge series resonant converter and the application of the half bridge series resonant converter in laser power supply. The series resonant converter has the high converting frequency and its output waveform comes near to the sine wave. Like the constant current resource, the series resonant converter also has the feature of high charging efficiency so that it is used as the charging circuit widely in the laser power supply. © 2010 IEEE.

Jin F.-L.,Jilin Institute of Chemical Technology | Park S.-J.,Inha University
Polymer Degradation and Stability | Year: 2012

Epoxy resin/filler hybrid composites were prepared by the melt blending of diglycidylether of bisphenol- A (DGEBA), as the epoxy resin, with nano-Al 2O3 or nano-SiC particles, as the nanoscaled fillers. The thermal properties, such as the curing behavior, thermal stability, dynamic mechanical properties, and thermal mechanical properties of the DGEBA/nano-Al2O3 and DGEBA/nano-SiC composites were examined using a range of techniques. As a result, the DSC curve peak temperature of both composites decreased with increasing filler content. The integral procedure decomposition temperature increased from 630 °C to 853 °C for DGEBA/nano-Al2O3 composite and 858 °C for DGEBA/nano-SiC composite. The char yield at 800 °C increased from 14.3% to 26.2-26.6% for both composites. Both composites had a 10 °C higher glass transition temperature than the neat epoxy resin. The coefficient of thermal expansion of both composites at the glassy and rubbery regions decreased with increasing filler content. © 2012 Elsevier Ltd. All rights reserved.

Gao X.,Jilin Institute of Chemical Technology
Proceedings - International Conference on Artificial Intelligence and Computational Intelligence, AICI 2010 | Year: 2010

In this paper, a constrained robust guaranteed cost tracking scheme for Wheeled Moving Robot (WMR) with actuator saturations is proposed. First, tracking error dynamics of WMR is represented by uncertain Tagaki-Sugeno (T-S) fuzzy model, where varying velocity in desired trajectory is look as uncertain parameter, so we can represent the T-S subsystem via Then constrained robust guaranteed controller in the form of state feedback is derived for each subsystem by solving LMI based semi-definite programming problems. Finally, The overall controller then is constructed in the framework of PDC and the Lyapunov stability of the closed-loop system is tested finally. Simulation results are given and discussed to validate the proposed scheme. © 2010 IEEE.

Shi J.Y.,Korea University | Shi J.Y.,Jilin Institute of Chemical Technology | Yi C.-W.,Sungshin Women's University | Kim K.,Korea University
Journal of Power Sources | Year: 2010

LiMn1.5Ni0.5O4 materials coated with AlPO4 are prepared by a sol-gel method with citric acid to improve their electrochemical performance; the physical and electrochemical properties are characterized by various analytical techniques. The coated AlPO4 layer completely covers the surfaces of the LiMn1.5Ni0.5O4 particles and the thickness of the coated layer is ∼15 nm. 1 wt.% AlPO4-coated LiMn1.5Ni0.5O4 has much lower surface and charge-transfer resistances and shows a higher lithium diffusion rate in comparison with the pristine sample. The modified material demonstrates dramatically enhanced electrochemical reversibility and stability under elevated temperature conditions. This is because the coated AlPO4 layer reduces the contact area between the electrode and electrolyte and suppresses the formation of undesirable solid electrolyte interface films. © 2010 Elsevier B.V. All rights reserved.

Han G.,Jilin Institute of Chemical Technology
Proceedings of 2010 International Conference on Intelligent Control and Information Processing, ICICIP 2010 | Year: 2010

This paper studies the discontinuous stabilization control of wheeled mobile robots with the actuator dynamics being considered. On the basis of polar coordinate representation and backstepping technique, control law designed for the kinematic model is backstepped into dynamic model and furthermore actuator dynamics is involved, asymptotic convergence of the closed-loop system is guaranteed by the Lyanpunov's stability theory. Finally simulation results for point-to-point stabilization control task are presented. © 2010 IEEE.

Lu D.-Y.,Jilin Institute of Chemical Technology | Cui S.-Z.,Jilin Institute of Chemical Technology | Cui S.-Z.,Northeast Normal University
Journal of the European Ceramic Society | Year: 2014

The point defects and the structural and dielectric properties of Dy-doped BaTiO3 ceramics prepared at 1400°C were investigated. The solubility of Dy in the self-compensation mode was determined to be x=0.07 for (Ba1-xDyx)(Ti1-xDyx)O3, and no EPR signals associated with the Dy3+ Kramers ion or the Ba and Ti vacancies were detected using the electron paramagnetic resonance (EPR) technique. As x increases, the dielectric behavior changed from a first-order phase transition to a diffuse phase transition to a Y7R dielectric-temperature stability. A strong EPR signal at g=1.974, which is rare among rare-earth-doped BaTiO3 ceramics appeared unexpectedly in the single-phase (Ba1-xDyx)Ti1-x/4O3 ceramics with deliberately designed Ti vacancies. This signal was attributed to ionized Ba vacancy defects. A preference for the self-compensation mode of Dy3+ ions is responsible for the appearance of Ba vacancies. The real formula of the nominal (Ba1-xDyx)Ti1-x/4O3 is expressed as (Ba1-xDy3x/4)(Ti1-x/4Dyx/4)O3. In addition, the defect chemistry is discussed. © 2014 Elsevier Ltd.

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