Papers by Author: Liang Sheng Qiang

Abstract: Water-based Polyaniline(PANI) emulsion and Fluorocarbon(FC) emulsion were synthesized by emulsion polymerization method. The doped polyanline were characterized by Transmission electron microscope(TEM) and X-ray diffraction(XRD). The results showed the PANI has bar-like shape and local crystallinity. The composite anticorrosion coatings of PANI emulsion and FC emulsion were prepared by mixture in aqueous medium and used for corrosion protection of mild steel. The corrosion protection property of PANI/FC coatings on mild steel was investigated by electrochemical impedance spectroscopy(EIS) and open circuit potential(OCP) technique in 3.5wt%NaCl aqueous solution. The results indicated that the water-based PANI/FC coatings could offer high protection because the impedance values and corrosion potential remained at higher. Scanning electron microscope(SEM) showed that the oxidation film formed on the metal surface and prevent corrosion effectively due to the passive effect of PANI pigment. The anticorrosion coatings are environmental friendly because of water dispersion medium.

Abstract: Lithium niobate thin films have been deposited on Pt/Ti/SiO2/Si substrates by the Pechini method from metal carboxylate gels and heat-treated at temperatures ranging from 400 to 600°C. The thermal decomposition of the metal carboxylate precursor gels has been studied by differential thermal analysis and thermogravimetry. The products derived from calcination of the gels at different temperatures have been characterized by Fourier transform infrared, Roman spectrum and X-ray diffraction. Scanning electron microscopy analysis shows the surface of the films to be smooth, dense and crack-free. Electric properties measurement indicates that the LiNbO3 films demonstrate a ferroelectric hysteresis loop. The remanent polarization (Pr) and coercive field (Ec) are 17.89 μC/cm2 and 35.23 kV/cm, respectively.

Abstract: (PU/UP IPNs)-BaTiO3 nanocomposites with different amounts of BaTiO3 nanopowder are prepared and polarized. The ferroelectric and dielectric properties are detected and the relationship between electric properties and damping properties are discussed in detail. Results indicate that the synergistic effects can be created successfully by elastic damping of polymer, frictional damping of BaTiO3, and piezoelectric damping of nanocomposites after poling. The nanocomposites increase the damping property evidently and sustain mostly ferroelectric and dielectric characters of inorganic phase. The introduction of BaTiO3 into IPNs decreases the resistivity, and this has advantages to enlarge the damping loss factor (tanδ).

Abstract: In present work, sol-gel process is used to direct the organization of high quality and pore-free parasite PZT thin films with a composition near the morphotropic phase boundary (Zr/Ti = 52/48). The PZT transparent sol can be obtained by dissolving the zirconium oxynitrate, butyl titanate and lead acetate in ethylene glycol with the molar ratio of 0.52:0.48:1 and the PZT gel can be gained by spin-coating. In such process, PZT thin films can be readily prepared by hydrolysis on hot plate at 350°C for 20min and annealing in RTA at 650°C for 1 minute. The structural and electric characteristics of the films have been carried out by XRD, AFM and the C-V measurements, etc. Experimental results have indicated that by treating film RTA at 6508 for 1 minute film with perfect crystallization and good surface morphology with a RMS roughness of 2.0nm can be obtained, and the remnant polarization Pr (28.5 μC/cm2) and coercive field Ec (39.8kV/cm) are obtained in the P-E hysteresis loops. The films have a dielectric constant ε of 1080 and a dielectric loss tanδ of 0.01 at 1 kHz. Ferroelectric polarization fatigue test of the films has shown that high fatigue resistance up to 3 × 1010 cycles before Pr is decreased by 50%.

Abstract: Rare earth complex Eu(phen)2Cl3·2H2O synthesized by precipitation method was incorporated into MCM-41 mesoporous molecular sieves which were synthesized via a hydrothermal method. Hybrid inorganic/organic mesoporous luminescent material Eu(phen)2/MCM-41 has been characterized by XRD, TEM, IR, UV-visible spectra and fluorescence spectra. Results indicated that the hybrid mesoporous material has typical structure of MCM-41 and retains the same pore structure as MCM-41 after the assembly process. The fluorescence spectra of these materials present a series of narrow lines assigned to 5D0 → 7F0,1,2,3,4 transitions. The high emission intensity observed is a promising property for application of the rare earth complex in technological luminescent devices.

Abstract: In this work, PZT (Zr/Ti=52/48) thin films have been prepared using aqueous organic gel method. The desired metal cations are chelated in a solution using citric acid and ethylenediaminetertraacetic acid (EDTA) as the chelating agents. The thermal decompostion of the metal carboxylate precursors gels have been studied by TG/DTA and the products derived from calcinations of the gels at different temperatures have been characterized by XRD and SEM. By heat-treatment at 650°C for 2h, PZT thin films with smooth and crack-free surface could be achieved. The thickness of each layer was 50nm. Electric properties measurement indicated that the PZT films demonstrated a ferroelectric hysteresis loop. The remanent polarization(Pr) and coercive field (Ec) were 20.7μC/cm2 and 75.5kV/cm, respectively. The dielectric constant and the dielectric loss at 100 kHz of the films were 930 and 0.045, respectively.

Abstract: By adding methyl alcohol/water solution with certain concentration into sol to hydrolysis directly and sintering the fresh sol directly, lead titanate(PbTiO3) ceramics doped with magnesium are prepared by using magnesium acetate as doper to prohibit the disadvantages contained in conventional sol-gel method, such as low hydrolytic rate, high sintering temperature, long preparation period. The changes of structure, microstructure, synthesis process and electric properties of modified ceramics are studied in detail. The sizes and morphology of high purely and high density magnesium doped lead titanate nanocrystals thus obtained are observed by TEM photographs and the structures and affection of sintering temperature of to lattice constant and sizes of nanocrystals are detected by XRD. Electric properties detection results show that doped lead titanate ceramics exhibite excellent dielectric, ferroelectric and pyroelectric properties compare with pure lead titanate.