Advanced Materials Research Vols. 1120-1121

Abstract: PC film has some shortcomings such as low surface energy and strong rigidity. In order to improve the impact strength and adhesive properties of PC film, UV curing coating which was used on the surface of the PC film achieved good results. However, the combination between the UV curing paint-PC composite membrane had not been explained clearly. In this paper, we analyzed the structure of UV curing varnish oligomers. Fourier Transform Infrared Spectroscopy (FTIR) 、X-ray Photoelectron Spectroscopy (XPS) and Liquid Chromatograph Mass Spectrometer (LC-MS) were used to characterize. Through the experiment, we had achieved 4, 4’ -Isopropyliden-edicyclohexanol(HBPA) and Phthalic acid . The existence of the two substances explained the reason why the lacquer had good adhesion, and the result also laid the foundation for the the characterization of the molecular structure about the film later.

Abstract: Novel ordered Ultra thin Films (UTFs) based on the hybrid assembly of exfoliated Zn-Cr Layered double hydroxide (LDH) monolayers and typical dawson-type polyoxometalate (POM) anions α-P₂W₁₈O₆₂^6- (P₂W₁₈) were prepared by utilizing a layer by layer (LBL) technique. The structural integrity of the UTFs were characterized by ICP-AES, XRD, IR, UV/DRS, indicating that the Dawson structures remained intact in the hybrid compositions. The morphology and the thickness of the UTFs were evaluated via SEM. The visible light photocatalytic performances of the UTFs were tested in the degradation of aqueous azo dye Congo red (CR). The UTFs showed much higher photocatalytic activity than pure Zn-Cr-NO₃^- LDH, mainly attributed to the improved absorbance and response ability to the visible light.

Abstract: The aim of this work is to show the effect of the iron ion doping in LaCoO₃ perovskite, both in powders and in sintered samples obtained from combustion reaction and solid state route. The phase formation and particle morphology and particle size distribution of the powders were analysed by XRD, SEM and sedimentation techniques, respectively. Relative density, microstructure (secondary phases and grain size) and pore size distribution of LaCo_1-xFe_xO₃ sintered ceramics were investigated by SEM/EDS and Hg porosimetry analysis. Although LaCo_1-xFe_xO₃ powders obtained from the combustion reaction exhibited smaller grain sizes when sintered at high temperatures, they showed a higher volume fraction of secondary phases. The presence of these crystalline phases in addition to the desired perovskite affected the microstructure acting as grain growth inhibitors by grain boundary pinning. It is believed that by observing three grain junction pores that the LaFeO₃ phase has a smaller dihedral angle than LaCoO₃. This fact would explain why LaFeO₃ presented a smaller driving force for sintering with a higher tendency of pore and inclusion coarsening at higher temperatures (1400°C).

Abstract: In this paper, we present a new approachcalled hyperthermal hydrogen induced cross-linking (HHIC) technology,which can successfully enhance the surface wettability of Parylene C (PC) film via cross-linking hydrophilic polyacrylic acid（PAA）on its surface. Water Contact Angle Meter and Fourier Transform Infrared Spectroscopy (FTIR) were used to characterize wetting property, surface chemical structureof PC film before or after HHIC treatment,respectively. The results show that PAA with polar functional groups can be successfully grafted onto the PC film. As a result, the water contact angle of the modified PC membrane surface decreased from 84° to 23°,PC membrane surface wettability is improved effectively.

Abstract: The deformation and mechanical properties of Zr-based bulk metallic glasses (BMGs) under a nanoindenter and the effect of cooling rate, the effect of cooling rate, tungsten fiber addition and annealing on them have been studied by means of a nanoindentation instrument and a scanning electron microscope (SEM). The results indicate that the deformation of Zr-based BMGs under a nanoindenter is characterized by multiple shear bands and viscous flow which confirms the existence of a amount of plastic deformation. For pure quenched Zr-based BMGs, the larger the size of samples or the nearer the location away from the surface of a same sample, the smaller the values of microhardness (Hv) and elastic modulus (E); Annealing and tungsten fiber addition enhance the values of Hv and E; meanwhile, they also significantly change morphology around a nanoindenter and the amount of plastic deformation. The mechanism of plastic deformation is preliminarily analyzed.

Abstract: The effect of impurity Ce on the mechanical and thermal properties of tetragonal ZrO2 stabilized by rare earth element Y (YSZ) have been studied using first principles density functional theory within generalized gradient approximation (GGA) for the exchange correlation potential. The predicted elastic constants indicate that YSZ and Ce doped YSZ (CeYSZ) are mechanically stable structures. And then the numerical estimates of bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, sound velocity and minimum thermal conductivity were performed using the calculated elastic constants and analyzed for the first time. The values of sound velocity from different orientations are also reported. The agreement between the results of the available experiments and our calculations was satisfactory. Our calculated results indicate that Young’s modulus, hardness, mean sound velocity and minimum thermal conductivity of YSZ can be decreased by Ce substitution. The reasons are from the “softened” Ce-O bond strength using bond population and relative volume change under external hydrostatic pressure. Chemical bonding nature was also analyzed from the density of states and electron density difference.

Abstract: In order to achieve better understanding of the effect of dopant (Sc, Y, Yb, Hf and Ce) on elastic stiffness and thermal properties of La2Zr2O7. The related calculations were performed using the first principles methods. The predicted elastic constants indicate that La2Zr2O7 and oxidations-La2Zr2O7 (oxidations refer to Sc2O3, Y2O3, Yb2O3, HfO2 and CeO2) are mechanically stable structures. And then the numerical estimates of bulk modulus, shear modulus, Young’s modulus were performed using the calculated elastic constants. After these mechanical properties are obtained, sound velocity, Debye temperature and theoretical minimum thermal conductivity of La2Zr2O7 and oxidations-La2Zr2O7 are calculated and analyzed in detail. The available experimental results and our calculations are basically satisfactory. The calculated results indicate that Young’s modulus, mean sound velocity, Debye temperature and minimum thermal conductivity of La2Zr2O7 can be decreased by dopants. CeO2 has extraordinary ability to decrease thermal conductivity in these dopant oxidations.

Abstract: 0.998[(0.95(K0.5Na0.5)NbO₃-0.05LiSbO₃]-0.002BiFe_1-xCo_xO₃ (KNN-LS-BF_1-xC_x, x=0-0.8) piezoelectric ceramics were prepared by solid-state reaction method. The influences of Co content on piezoelectric and ferroelectric properties were investigated. The results reveal that the substitution of Co significantly affects the piezoelectric and ferroelectric properties of KNN-LS-BF_1-xC_x ceramics. All samples with various Co contents show a pure perovskite structure. With increasing x from 0 to 0.8, the depolarization temperature T_d of KNN-LS-BF_1-xC_x ceramics increase with increasing x, and the piezoelectric constant d₃₃ of KNN-LS-BF_1-xC_x specimen with x=0.2 is larger than those of other KNN-LS-BF_1-xC_x specimens in the investigated range when the temperature is lower than T_d. The remnant polarization P_r decrease with x in the investigated range, but the coercive field E_c increase to 1.78kV/mm with x up to 0.6, and then decrease with further increase of Co contents x.

Abstract: CO(NH₂)₂ as pore-former used to prepare porous Ca_2.5La_0.5Co₄O₉ thermoelectric materials by solid-state reaction technique.Microstructure,density and thermoelectric properties (temperature dependence of electrical resistivity,Seebeck coefficient) of the samples were studied in details.The results have shown that the porosity increases and the pore structure is improved with the pore-former content increasing,and electrical resistivity and density decrease while Seebeck coefficient raise.The improvement in electrical resistivity and Seebeck coefficient leads to higher power factor values at 913 K (around 1.32 mW/cm·K²) than undoped samples.

Abstract: In this paper, the influencing factors in the process of alkali leaching of refractory zinc oxidize ores were studied. The influence of the particle size, reaction temperature, leaching time, alkali concentration and liquid-solid ratio on the leaching efficiency of zinc were investigated via leaching tests. The results indicate that the particle size has little influence on the leaching efficiency of zinc while the influences of other factors are larger. The optimal leaching condition is: the reaction temperature is 80 °C, the alkali concentration is 4.5 mol/L, and the leaching time is 1.5 h as well as the liquid- solid ratio is 10:1. In such conditions, the leaching efficiency can reach 82.22%.