Materials Science Forum Vols. 809-810

Abstract: Al-doped ZnO (AZO) powers with a novel rice-like morphology have been successfully synthesized through a simple and efficient hydrothermal approach, the products have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) with an energy-dispersive X-ray analyzer and transmission electron microscopy (TEM). It showed that all the samples presented an hexagonal wurtzite structure of high crystallinity, and the microstructure was composed of numerous dumbbells. Furthermore, the heater gas sensors were fabricated and an investigation of gas sensing properties has been conducted. The sensors showed good selectivity to ethanol comparing with NH₃, SO₂, CO and HCHO and possible mechanism was discussed. The Sensors based AZO powers exhibited high response values, reproducible response-recovery to ethanol 50-1800 ppm at 332°C.

Abstract: A new gas sensor with high response and selectivity was fabricated by using molecularly imprinted powders (MIPs) which provide special recognition sites to methanol. The MIPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fourier transform infrared spectrometer (FT-IR), respectively. The gas sensing properties of MIPs to methanol were investigated. The experimental results indicate that the sensors based on the MIPs show excellent gas sensing properties to methanol vapor, and the properties of the sensor with x=6:10 (x= methyl acrylic acid: LaFeO₃, molar ratio) are the best. At the optimal operating temperature of 130°C, the response of the sensor (x=6:10) to 1 ppm methanol is 21, and the response and recovery times are 57 s and 67 s, respectively.

Abstract: Stimuli responsive electrospun fibers are obtained considerable attention as excellent functions and properties. An overview is given on recent advances made in the development from component to structure of electrospun fiber and applications in the aspects of physical and chemical stimuli. The specific features for these electrospun fibers are highlighted and applications are discussed as regeneration medical engineering and drug-releasing implants materials. Furthermore, the development of multi-component and multi-stimuli functions electrospun fiber is proposed in the future perspective

Abstract: Tungsten was considered a promising plasma facing material in fusion device due to its high sputtering threshold, the high melting point,and so on. Several technologies fabricated tungsten armor on copper substrate were introduced, which included plasma sprayed tungsten coating, W/Cu functionally gradient material and the dispersiion strengtheded W alloys (W-TiC, W-La₂O₃). Meanwhile, W-Cu mock-up with the different compliant interlayers was optimizated by means of ANSYS code.

Abstract: In this paper, the correlation between the particle size and rheological properties of MRE was discussed through both experimental results and theoretical analysis. It shows that the particle size can significantly influence the magnetorheological effect by changing the initial shear modulus and the saturated magnetic-induced shear modulus . With an increase in the particle size, the initial shear modulus gets lower, and the saturated magnetic-induced shear modulus increases to the maximum and then decreases. The larger the particle size is, the longer the distance between neighbor particles along the magnetic field is. Based on the relationship between the particle size and shear modulus, there exists an optimum size for added particles. Moreover, the performance of MRE can be improved by optimizing the particle size based on those rules.

Abstract: Lead-free piezoelectric ceramics (1-x)Na_0.5Bi_0.5TiO₃-xBaTiO₃(x=0.04, 0.06, 0.08) was synthesized via sol–gel combustion method. Structural analysis was performed by using X-ray diffraction (XRD). The structural morphology of the nanoparticles was studied using scanning electron microscopy (SEM). The ceramics show a rhombohedral-tetragonal morphotropic phase boundary (MPB) in the range of x =0.04-0.08, which makes ceramics having superior dielectric and piezoelectric properties. There is a decrease of the grain size with increasing BT concentration, suggesting that dissolving BT into NBT inhibits the grain growth. And the multi-peak fitting result shows lattice constants of NBT have increased with the BT doped into NBT. Belong to the ionic polarization relaxation type, the low temperature dielectric anomalous peak shift towards a high temperature and the high temperature dielectric anomalous peak shift towards a lower temperature showed by the dielectric-temperature spectrum. Dielectric-temperature spectrum further determines that (1-x)NBT-xBT ceramics are relaxation ferroelectrics, and join BT makes the Curie temperature decreasing about 21 to 24°C. High piezoelectric properties with d₃₃=148pC/N are observed in NBT-BT_0.06.

Abstract: Bismuth-based pyrochlore dielectrics with the formula (Bi_1.5Zn_0.5)(Ti_1.5M_0.5)O7 (M = Nb, Ta and Sb) have been synthesized to investigate the influence of M between the dielectric properties and crystal structure. The XRD patterns show that all of the three samples give single phase. The refined data by GSAS program and the bond valence theory were used to analyze the differences in dielectric properties with occupation of different ions in B site. The dielectric constant of BZTS is the smallest in the BZTM, which is due to the polarizability and the contribution of BO₆ octahedra which has weak correlation when Sb placed into the center of the octahedra would also result in small αε. When it comes to the moderate temperature range, oxygen vacancies migration was thermally activated as the carriers mechanism, and the different activation energies is related to the association and the disassociation of massive complex defects. The Rietveld refinement data pointed that with the respectively change of B ions, more oxygen vacancies and free oxygen ions are provided by structural defects to participate in the conduction which can lead to the σ increase gradually.

Abstract: As lithium-ion battery anode materials, silicon has the highest specific capacity. In order to restrain pure silicon’s serious volume change and enhance its electrochemical performance, Si/SiO₂ composites were prepared by using a convenient high energy ball-milling technique. The characteristics of the composites as anode material for rechargeable lithium-ion batteries were investigated by X-ray diffraction and scanning electron microscopy methods. The electrochemical performance of the anode material was studied, and it was found the composite anode had a high capacity of 1333 mAhg^-1 in the first cycle and 400 mAhg^-1 could still be obtained after 46 cycles. Such prepared materials displayed improved cycle life.

Abstract: The thermal physical properties, thermal stability and corrosion resistance of the ternary nitrate salts 55%NaNO₃-35% KNO₃-10% LiNO₃ have been studied by the thermal analysis TG-DSC, weight method and so on. The results show that the melting point of mixed molten salt is 380 °C and the maximum operating temperature is 750 °C. Compared with the binary system, this molten salt system has a higher operating temperature upper limit and a wider operating temperature range of 400 ~ 750 °C, which could meet the temperature requirement of solar power generation and be a solar high-temperature heat transfer and thermal storage medium material of better comprehensive performance.

Abstract: Dye-sensitized solar cells (DSSCs) have attracted extensive attention owning to their simple preparation prcess, low cost, and relatively high energy conversion efficiency. At present, most researches are focused on TiO₂-based DSSC and high powder conversion efficiency of over 12.3% has been obtained. As a potential candidate, Zn₂SnO₄ has drawn increasing attention for DSSCs due to its attractive electrical and optical properties (Eg = 3.6 eV, electron mobility of 10–15 cm²V^-1s^-1). In this article, we maily reviewed the recent progress of Zn₂SnO₄-based DSSCs and put forward ideas for designing new Zn₂SnO₄ materials in future application for DSSCs.