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Showing papers by "University of Science and Technology Beijing published in 2006"


Journal ArticleDOI
TL;DR: In this paper, highly dense Niobate ceramics were prepared using spark plasma sintering (SPS). Although the SPS temperature was as low as 920 C, the density of the Na 0.5 K 0.5 NbO 3 solid solution was raised to 4.47 g/cm 3 (>99% of the theoretical density).
Abstract: Lead-free piezoelectric ceramics have received attention because of increasing interest in environmental protection. Niobate ceramics such as NaNbO 3 and KNbO 3 have been studied as promising Pb-free piezoelectric ceramics, but their sintering densification is fairly difficult. In the present study, highly dense Na 0.5 K 0.5 NbO 3 ceramics were prepared using spark plasma sintering (SPS). Although the SPS temperature was as low as 920 C, the density of the Na 0.5 K 0.5 NbO 3 solid solution ceramics was raised to 4.47 g/cm 3 (>99% of the theoretical density). After post-annealing in air, reasonably good ferroelectric and piezoelectric properties were obtained in the Na 0.5 K 0.5 NbO 3 ceramics with submicron grains. The crystal phase of the Na 0.5 K 0.5 NbO 3 has an orthorhombic structure. The Curie temperature is 395°C and the piezoelectric parameter (d 33 ) of the Na 0.5 K 0.5 NbO 3 ceramics reached 148 pC/N.

422 citations


Journal ArticleDOI
TL;DR: In this article, lead-free piezoelectric NaxK1−xNbO3 (x=20−80 mol%) ceramics were fabricated using spark plasma sintering at a low temperature (920°C).
Abstract: Lead-free piezoelectric NaxK1−xNbO3 (x=20–80 mol%) ceramics were fabricated using spark plasma sintering at a low temperature (920°C). All the NaxK1−xNbO3 ceramics showed a similar orthorhombic phase structure, while the corresponding lattice parameters decreased from the KNbO3 side to the NaNbO3 side with increasing Na content. A discontinuous change in lattice parameter close to composition of 60 mol% Na indicated the presence of a transitional area that is similar to the morphotropic phase boundary (MPB) in NaxK1−xNbO3 ceramics. The sintered density of the NaxK1−xNbO3 ceramics decreased with increasing Na content, from a relative density of 99% for the K-rich side to 92% for the Na-rich side. The piezoelectric constant d33 and planar mode electromechanical coupling coefficient kp showed a maximum value of 148 pC/N and 38.9%, respectively, due to the similar MPB effects in the PZT system.

250 citations


Journal ArticleDOI
15 Feb 2006-Talanta
TL;DR: Good analytical performance was achieved from real-world water samples such as river water, reservoir water, tap water and wastewater after primary pretreatment with proposed method, indicating that the developed method could be used as an alternative for the routine analysis of atrazine and simazine in many real water samples

210 citations


Journal ArticleDOI
TL;DR: The electron backscatter diffraction technique and Schmid factor analysis revealed that deformation twinning was influenced both by grain rotation due to slip and by the Schmid Factor as discussed by the authors.

206 citations


Journal ArticleDOI
TL;DR: The results suggested that the selection of suitable size of CNTs as a kind of adsorbent is very important in the efficient eliminating MCs from drinking water in future.

183 citations


Journal ArticleDOI
TL;DR: In this article, major and trace element compositions, and O-C isotope data for Cenozoic carbonatites (WSC) in western Sichuan, east Tibet, China are presented.

163 citations


Journal ArticleDOI
TL;DR: The goal of this work was to investigate the feasibility of MWNTs used as SPE adsorbents to enrich dichlorodiphenyltrichloroethane (DDT) and its metabolites at trace level which are typical persistent organic pollutants in environment.

160 citations


Journal ArticleDOI
TL;DR: A waveguide-based retrieval method for measuring complex permittivity and permeability tensors of metamaterials is presented and shows its effectiveness in the effective parameters extraction.
Abstract: A waveguide-based retrieval method for measuring complex permittivity and permeability tensors of metamaterials is presented. In the proposed scheme, multiple independent sets of scattering data for the material under test with different orientations are measured in the frequency range corresponding to the dominant TE(10) mode. The method is applied to various metamaterials and shows its effectiveness in the effective parameters extraction.

149 citations


Journal ArticleDOI
TL;DR: A hybrid intelligent algorithm integrating fuzzy simulation and genetic algorithm is designed in the paper to provide a general method to solve the new models of credibility-based portfolio selection model.

148 citations


Journal ArticleDOI
TL;DR: A new e-maintenance system is proposed that is dependent upon coordination, co-operation and negotiation through the use of Internet and tether-free communication technologies that enables manufacturing operations to achieve near-zero-downtime performance on a sharable, quick and convenient platform.

138 citations


Journal ArticleDOI
TL;DR: In this article, the monosodium glutamate wastewater after diluted was well treated as a cheap fermentation broth for Rhodotorula glutinis to biosynthesize lipid as the raw material for the production of biodiesel.

Journal ArticleDOI
TL;DR: In this article, the mechanical properties of individual zinc oxide (ZnO) nanowires, grown by a solid-vapour phase thermal sublimation process, were studied in situ by transmission electron microscopy (TEM) using a home-made TEM specimen holder.
Abstract: The mechanical properties of individual zinc oxide (ZnO) nanowires, grown by a solid–vapour phase thermal sublimation process, were studied in situ by transmission electron microscopy (TEM) using a home-made TEM specimen holder. The mechanical resonance is electrically induced by applying an oscillating voltage, and in situ imaging has been achieved simultaneously. The results indicate that the elastic bending modulus of individual ZnO nanowires were measured to be ~58 GPa and the damping time constant of the resonance in a vacuum of 10−8 Torr was ~14 ms. A nanobalance was built and the mass of the nanoparticle attached at the tip of a nanowire was measured. The ZnO nanowires are promising in potential applications as nanocantilevers and nanoresonators.

Journal ArticleDOI
TL;DR: In this paper, a new procedure was described with multiwalled carbon nanotubes as solid phase extraction packing material for the trace analysis of nicosulfuron, thifensulfuron and metsulfuron-methyl in water samples.

Journal ArticleDOI
TL;DR: A novel method for sensitive determination of thiamethoxam, imidacloprid and acetamiprid based on solid-phase extraction with multiwalled carbon nanotubes as the packed materials and satisfactory achievements were obtained.
Abstract: This paper describes a novel method for sensitive determination of thiamethoxam, imidacloprid and acetamiprid based on solid-phase extraction with multiwalled carbon nanotubes as the packed materials. Factors that maybe influence the enrichment efficiency, such as sample flow rate, sample pH, and sample volume, were investigated in detail. Under the optimized conditions, the detection limits of thiamethoxam, imidacloprid and acetamiprid were 6.1, 5.4 and 6.7 ng L−1, respectively. The experimental results indicated that there was good linearity (R 2>0.9993) over the range of 0.08~100 ng mL−1 and good reproducibility with the relative standard deviations over the range of 0.7~1.1% (n=6). The proposed method has been applied to the analysis of real-world water samples, and satisfactory achievements were obtained. The average spiked recoveries were in the range of 87.5~109.8%. All the results indicated that the proposed method could be used for the simultaneous determination of the three pesticides in environmental water samples at trace levels.

Journal ArticleDOI
TL;DR: In this paper, a consumable anode composed of a solid solution of titanium carbide and titanium monoxide was prepared via carbothermic reduction of TiO2, and the anode fed Ti2+ into solution and carbon monoxide generated; no excess carbon remained to contaminate the melt.
Abstract: In this work, a consumable anode composed of a solid solution of titanium carbide and titanium monoxide was prepared via carbothermic reduction of TiO2. Upon electrolysis, the anode fed Ti2+ into solution and carbon monoxide was generated; no excess carbon remained to contaminate the melt. On the cathode, high-purity titanium (>99.9%) was produced. Our results suggest anode and cathode current efficiencies of 93.5% and 89% respectively, indicating that the method is viable and extremely cost-effective, potentially dropping the cost of titanium to near that of aluminum.

Journal ArticleDOI
TL;DR: Wang et al. as mentioned in this paper showed that double-sided ZnO nanocombs with doublesided teeth have been observed and that the Znterminated (0 0 0 0 1) surface is responsible for the formation of the teeth.

Journal ArticleDOI
TL;DR: The experimental results indicated that the field emission characteristics of the devices fitted well to the Fowler-Nordheim model of emission.
Abstract: Polypyrrole nanowires have been electrosynthesized by direct oxidation of 0.1 mol l(-1) pyrrole in a medium of 75% isopropyl alcohol + 20% boron trifluoride diethyl etherate + 5% poly (ethylene glycol) (by volume) using porous alumina membranes as the templates. The as-prepared nanowires had a smooth surface and uniform diameter and were arranged in an orderly manner in a high density. The conductivity of a single nanowire was measured by the four-electrode technique to be 23.4 S cm(-1) at room temperature. The field emission devices based on the nanowire array were fabricated and their operations were explored. The experimental results indicated that the field emission characteristics of the devices fitted well to the Fowler-Nordheim model of emission. The turn-on electric field was only 1.2 V microm(-1) and the current density reached 200 microA cm(-2) at 2.6 V microm(-1).

Journal ArticleDOI
TL;DR: In this article, a new model has been proposed to describe the oxidation of Si-Al-O-N materials in both isothermal and non-isothermal conditions in the form of powders and pellets.
Abstract: In this paper a new model has been proposed to describe the oxidation of Si-Al-O-N materials in both isothermal and non-isothermal conditions in the form of powders and pellets. All these formulae are analytic with a form of explicit function; therefore, they are not only easy to use but also enable the easy performance of a theoretical analysis. The application of these formulae to practical systems shows that this model is feasible; moreover, these formulae can not only be used to treat the oxidation for Si-Al-O-N materials but also be applied to treat reactions in other fields of materials.

Journal ArticleDOI
TL;DR: In this paper, a newly developed Ni-Cr-CoCo-Mo-Nb-Ti-Al superalloy was developed for ultra-supercritical boilers with steam temperatures up to 700°C.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the correlation of thermodynamics and grain growth kinetics of nanocrystalline metals both theoretically and experimentally, and proposed a model to describe the thermodynamic properties of nanograin boundaries.

Journal ArticleDOI
TL;DR: In this paper, a novel technique has been developed to produce Fe-Al intermetallic coatings on steel, which applied mechanical vibration to a retort, which is loaded with Al powder, alumina filler, ammonium chloride activator and FeCrAl alloy balls.

Journal ArticleDOI
TL;DR: In this paper, the deformation of an electroformed polycrystalline pure copper with both nano- and uf-sized twins was studied using the Kocks-Mecking plot approach.
Abstract: The diminishing of strain hardening effect has been an important issue in understanding the special deformation mechanism in the nano- and ultrafine- (uf-)grained materials. The deformation of an electroformed polycrystalline pure copper with both nano- and uf-sized twins was performed by uniaxial tension. Strain hardening rate was studied using the Kocks–Mecking plot approach. Microstructure evolutions of the two-scale sized twins at different strain conditions were observed and compared by means of transmission electron microscopy. A link between the abnormal hardening rate and the deformation mode inside nano- and uf-sized twins was established, and the diminishing of the hardening rate is attributed to the enhanced creep tendency and premature recovery of the special microstructures.

Journal ArticleDOI
TL;DR: In this article, microstructure and tensile properties of high Nb containing TiAl alloy, with nominal composition of Ti-45Al-(8-9)Nb-(W, B, Y) (at.%), were investigated.

Journal ArticleDOI
TL;DR: In this paper, the effect of rare earth metals in steels is discussed, which are modification of inclusions, deep purifying steel, and alloying, and the mechanism of abrasion resistance and the life of fatigue enhanced in RE-heavy rails steel.

Journal ArticleDOI
TL;DR: Two types of models are proposed using credibility to measure confidence level and a fuzzy simulation-based genetic algorithm is applied to solve the problem of capital budgeting in a fuzzy environment.

Journal ArticleDOI
TL;DR: Anatase-type TiO2 (titania) doped with cerium up to 5% was directly formed as nanometer-sized particles from TiO(NO3)2-Ce(NO 3)2−NH4NO3-citric acid complex compound system by sol-gel auto-igniting synthesis process.
Abstract: Anatase-type TiO2 (titania) doped with cerium up to 5 mol% was directly formed as nanometer-sized particles from TiO(NO3)2–Ce(NO3)2–NH4NO3–citric acid complex compound system by sol–gel auto-igniting synthesis process. The precursor gel was characterized by infrared spectroscopy and TG/DSC analysis. The XPS measurement showed that Ce(III) was easily oxidized to Ce(IV) at 550 °C and above. The XRD data, XPS spectra, and TEM selected-area diffraction patterns confirmed that cerium(IV) formed a solid solution in the anatase-type TiO2 powders. Doping of CeO2 into TiO2 shifted the phase transformation from anatase- to rutile-type structure to a high temperature. On the other hand, CeO2 was segregated on the surface of TiO2 and the rutile formation was accelerated during phase transformation from anatase to rutile at elevated temperature. When the cerium content was increased in the anatase phase, onset of optical absorption shifted to longer wavelengths, and absorption in the UV-light region and in the visible-light region over 400–500 nm clearly appeared in the diffuse reflectance spectra of the as-prepared Ce-doped TiO2.

Journal ArticleDOI
TL;DR: In this paper, the authors discussed the Y and Nd doped barium cerate perovskites prepared by a modified Pechini method and the series prepared is described by the formula BaCe 0.80 Y x Nd 0.2− x O 3− δ.

Journal ArticleDOI
TL;DR: In this article, the fine structure of martensite/austenite (M/A) islands in pipeline steel X70 was investigated using transmission electron microscopy, and it was shown that the microstructure of the steel undergoing thermo-mechanical controlled processing, comprises a majority of irregular blocky ferrite and acicular ferritic constituents and a small amount of so-called M/A islands which in turn consisted of retained austenite and martensites plates different in size and orientation.
Abstract: The fine structure of martensite/austenite (M/A) islands in pipeline steel X70 was investigated using transmission electron microscopy. It was shown that the microstructure of the steel undergoing thermo-mechanical controlled processing, comprises a majority of irregular blocky ferrite and acicular ferritic constituents and a small amount of so-called M/A islands which in turn consisted of retained austenite and martensite plates different in size and orientation. Microtwins and midrib are usually formed within a martensite plate, which is an indication of the occurrence of high-carbon martensite. It was in addition found that the amount of the M/A islands decreased slightly with increasing the cooling rate after the hot deformation, and the morphology of the M/A islands changed from thick, irregular long strip to thin, short rods. The holding temperature after the fast cooling had no evident effect on the amount of the M/A islands, though lowering the holding temperature could yield a finer and more dispersive M/A islands.

Journal Article
TL;DR: In this paper, a three-step search method for selecting the parameters of least squares support vector machines is presented, and the steel's hardenability is predicted using this method.
Abstract: Three step search method for selecting the parameters of least squares support vector machines is presented Theoretical analysis indicates that this method is effective and superior for selecting the optimized parameters of least squares support vector machines The steel’s harden-ability is predicted using this method for selecting the parameters of least squares support vector machines The simulation result shows that this method can get optimized parameters and precise modeling effect

Journal ArticleDOI
TL;DR: In this article, the growth of ZnO nanobelts is controlled by vapor-solid and screw dislocation mechanisms, and the growth is around the dislocations in the toothed-nanobels.
Abstract: Uniform ZnO normal nanobelts and toothed-nanobelts have been successfully synthesized respectively through pure zinc powder evaporation without catalyst at 600°C. Experimental results indicate that the key to the fabricating method is to control the gas flow rates and the partial pressures of argon, oxygen and zinc vapor. Scanning electron microscopy and high-resolution transmission electron microscopy observations show that the ZnO nanobelts have several types of single crystalline morphology. HRTEM images reveal that there are numerous screw dislocations and the growth is around the dislocations in the toothed-nanobelts. The growth of ZnO nanobelts is controlled by vapor-solid and screw dislocation mechanisms. Room temperature photoluminescence spectra of the toothed-nanobelts showed a UV emission at ∼390 nm and a broad green emission with 4 subordinate peaks at 455–495 nm.