Advanced Materials Research Vol. 893

Abstract: Morphology-related anomaly was found in the photoluminescence (PL) of Ge/Si type-II double heterostructures with varying Ge coverage. PL Stokes shifts of 2-D Ge wetting layers functioning as a quantum well for holes switched from negative to positive under electric field as Ge coverage crossed 3.7 monolayers, which correlates well with the onset of Stranski-Krastanow growth mode transition. The origin of such shift polarity switch is discussed in terms of the linear Stark effect in an asymmetric confinement potential developing due to 3-D Ge islands.

Abstract: s. The study showed that organic alcohols with 1,2,3,5,6 hydroxyl groups can be used as reducing agents for laser-induced copper deposition from solutions (LCLD).Multiatomic alcohols, sorbitol, xylitol, and glycerol, are shown to be effective reducing agents for performing LCLD at glass-ceramic surfaces unless they are weak reductants. Hypothesis of 2-photon photoeffect during laser induced copper deposition was discussed. Using the described dechnique one can obtain high-conductivity copper micro wires on dielectric surfaces for microelectronics and sensor applications

Abstract: In the past several decades,ceramic has been serving as a kind of traditional material which is wildly used in high-tech areas such as industry,electronics,military,etc. This essay aims to study the re-design of ceramic products. It starts with the introduction of ceramic characteristics and makes a detail discussion combined with Chinese thousands of years of cultural accumulation. This essay emphasizes the significance of ceramic re-design from three main aspects: the quality of special ceramic material, cultural characteristics and economic characteristics of ceramic. Meanwhile,it makes a point through analyzing the typical re-design cases thoroughly. Ceramic product re-design can not only revitalize current ceramic industry effectively,but also greatly increase the economic benefits. Consequently,''Design in China'' is bound to infuse fresh vigor and vitality into ceramic industry.

Abstract: This study prepared hydroxyapatite powder that synthesized from natural gypsum rock and find out physicalchemical and cytotoxicity properties. The synthesis realized by reacting natural gypsum powder with 1M of (NH₄)₂HPO₄ solutions using a microwave. Characterizations of natural gypsum powder and hydroxyapatite powder were conducted by XRD, XRF and SEM. In vitro cytotoxicity testings of hydroxyapatite powder were conducted by MTT method using vero cells. XRD patterns of gypsum powder closed to JCPDF 33-0311 (gypsum standard). Characteristics of gypsum powder i.e. contained 41.72% CaO, level of purity 91,6 % and crystal size 7,147 nm. Charateristic of hydroxyapatite powder that synthesized from natural gypsum powder i.e. contained 46.91% CaO and 40.20% P₂O₅, XRD patern closed to JCPDF 09-432 (hydroxyapatite standard), level of purity 99 % and crystal size 1.243 nm. There were not significantly difference in cytotoxicity properties of hydroxyapatite powder that synthesized from natural gypsum rock and commercial hydroxyapatite powder (p= 0.086). These results indicated hydroxyapatite powder that synthesized from natural gypsum rock possible to be used as bone substitutes.

Abstract: LiFePO₄/C materials were synthesized by spray-drying using FePO₄·2H₂O, LiOH·H₂O as raw materials, glucose as reducing agent and conductive additive. The morphology, structure and electrochemical properties of the LiFePO₄/C were tested and analyzed. The morphology of the LiFePO₄/C was biconcave and round looked similar to red blood cells, the tap density of the material up to 1.45g/cm³. The electrochemical performance of the material was excellent. The LiFePO₄/C had an initial discharge specific capacity of 161.8mAh/g at rate of 0.1C and its specific capacities were 148.7, 120.9mAh/g at rates of 1, 5C rate, respectively. The discharge capacity remained at 95.8%, 81.7% after 500, 1000 cycles respectively at rate of 5C.

Abstract: The effect of annealing heat treatment on the properties of high-density tantalum coating layer produced by the kinetic spray process was investigated. Pure Ta powder with an average particle size of 24.35μm and irregular shape was used to produce the coating layer through kinetic spray process. The annealing heat treatments of tantalum coating layers were applied for an hour in an Ar gas atmosphere under temperatures of 800°C, 900°C, 1000°C, and 1100°C. The manufactured coating layers have hardness and porosity of 270 Hv and 0.28%, respectively, showing even higher density levels than the kinetic-sprayed Ta coating layers reported to date. As the annealing temperature increased, the hardness value of the coating layer reduced from 270 Hv to 183 Hv and the porosity was verified to have decreased from 0.28% to 0.18%. The result of the additional XPS analysis confirmed that the phase generated between particle interfaces with heat treatment was Ta₂O₅ oxide. Based on these results, improving methods to dense the Tantalum coating layer with kinetic spray process was considered.

Abstract: Transition metal oxide-doped CCTO (CaCu₃Ti₄O₁₂) ceramics were prepared by a conventional solgel synthesis method and the effects of pure CCTO and CCTO doped with Mn, Fe, Co, Ni to the crystal structure, microstructures and dielectrical properties of samples were investigated. The phase composition and microstructure were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD analysis reveals that all samples exhibited multiphases with the pseudo-perovskite cubic CCTO phase with space group Im-3 as the main phase in undoped and doped CCTO samples. Peaks of monoclinic CuO and peroveskite CaTiO₃ could also be seen in all samples which indicate that solid solution of CuO in CaTiO₃ lattice was incomplete.SEM results show that doping effectively enhanced densification. SEM micrographs also suggested that the morphologies of doped CCTO ceramics had showed a matrix consisting of large grains wherein the small grains were embedded between the larger grains. Dielectric properties of pure and doped CCTO were investigated in a broad frequency range of the dielectric constant reached a value as high as ε_r = 29.4 at room temperature for CCTO doped with Ni at frequency (1000 Hz). Besides the sintering conditions, the microstructure and the dielectric properties of the CCTO are strongly influenced by type of doping elements.

Abstract: This work predicts the Thermal class of glass net for transformer. The rapid thermal ageing test method was applied to estimate thermal class of glass net.

Abstract: In order to investigate the density anomaly of vitreous silica in the medium-or long-range order, different models were made to study the atomic configuration revolution in thermal history by molecular dynamics. The void structures have been studied through analyzing the best model that is carefully selected. The principle of void size distribution revolution at elevated temperatures was used to explain the density anomaly of the vitreous silica. The simulation results showed that when the temperature is low, the void radius increases with the temperature rising. After 2000 K, large void structures are destroyed, filled, or separated into small radius voids. In the range from 2000 K to 2400 K, large void structures decrease faster exceeding the bond extension on thermal expansion contribution, this should be the root cause of negative thermal expansion behavior for vitreous silica. When the temperature is greater than 2400 K, with the temperature rising, the normal thermal expansion is recovered gradually because number of large voids has been reduced and their destroying cannot eliminate the contribution to expansion of bond extension. Therefore, the negative thermal expansion of vitreous silica could be described by the revolution of void structures in the medium-or long-range clearly, and is mainly influenced by the existence and change of larger voids.

Abstract: Melt blowing is one of the important methods for producing ultrafine fibers. The production of melt blowing is the nonwoven. Fiber diameter has crucial effect on the property of the nonwovens. In the melt-blowing process, many achievements have been published on the fiber diameter distribution along the spinning line. Note that all the results were obtained by methods of mechanical analysis, online measurements through high-speed photography and offline measurements from the production of nonwoven. In this study, a new method for calculating the fiber diameter distribution along the spinning line near the die face was revealed. This method was based on the geometry of the fiber path in the melt-blowing process. The fiber diameter reduction was calculated by this method and then compared with the experimental results obtained by other researchers. The results show that the proposed method is feasible.