bluuebunny/crossref_metadata_2025 huggingface dataset:
Piezoceramic Stack Actuators for Micropositioning Stage
Authors: Xu Ya Nan , Chu Xiang Cheng
Published: June 2012

Based on piezoceramic stack actuators, a stage (dimension of 50mm×50mm×11mm) with a symmetric displacement magnifying mechanism is studied in this paper. FEM simulations are carried out to reveal the performance of the micropositioning stage and the amplification radio of the flexure hinge is 4.76. The working mode of the flexure hinge of the stage is also simulated by finite element method, and its natural frequency is 3291Hz. A series of tests about piezoceramic stack actuators have been done, including static, dynamic and temperature tests. The experimental results are identical to the theoretical analysis and give help to the application of piezoceramic stack actuators. It can also help the precise micropositioning stage driven by PZT to achieve higher positioning accuracy and resolution.
Damping Properties of Epoxy-Embedded Piezoelectric Composites
Authors: Hong Xuan Qing , Wang Xu Sheng , Li Xiang Ming , Chen Rui , Yao Xi , Sun Zhao Jin , Guo Jian Qiang
Published: June 2012

The 0-3 and 1-3 composites have been widely used to produce various kinds of piezoelectric devices. This article focuses on the damping properties of the epoxy/piezoelectric composites. Due to the piezoelectric effect, the composites are expected to improve the damping properties and can be used in the field of vibration reduction and noise control. Two piezoelectric materials were embedded into the epoxy resin to make specimens, T-ZnOw/epoxy resin as 0-3 and PZT fibers/epoxy resin as 1-3 composite. With the method of dynamic mechanical analysis, the temperature dependence of the mechanical storage modulus and the loss factor (tanδ) were measured at different frequencies. The experimental results clearly show that the loss factor increases when testing frequency is higher. In this study, the piezoelectric damping and the viscoelastic effect are discussed and both of them contribute to the damping property of the composite system.
Sol-Gel Derived Li2O Doped BNT-BKT-BT Ceramics: Microstructure and Piezoelectric Properties
Authors: Sun Tao , Dai Ye Jing , Wang Hong Qiang
Published: June 2012

The introduction of lithium ion into BNT-BKT-BT ceramics with sol-gel method allows the development of high-performance lead-free piezoelectric ceramics. Nanoscale precursor powders were synthesized through calcination of amorphous gels, and densified ceramics with single perovskite structure were prepared at a relatively low sintering temperature 1110 °C. Crystal grain growth was fully developed with the Li+ addition through scanning electron microscope observation. Enhanced electrical properties, piezoelectric constant d33~184 pC/N and planar electromechanical coupling factor kp~0.30, were obtained for the ceramics.
Effects of Different Reducing Agents and Protective Agents on the Preparation of Nano-Silver Powder
Authors: Zhai Feng Rui , Liu Yi Ming , Yi Zhong Zhou , Zhang Hong Wei , Lu Min
Published: June 2012

Solution chemical reduction method is a means which used reducing agent in aqueous or organic systems to deoxidize silver ions. Its essence is an integrated process of the electrochemistry, thermodynamics, kinetics and fluid dynamics and so on. The process determines the physical and chemical properties such as the size distribution of powder, purity and reunion situations, etc. Nano-silver powder has high surface activity and catalytic properties, and is widely used to a lot of fields. So it has very important realistic significance to study the preparation method. In this paper, nano-silver powder was prepared with industrial AgNO3 as raw materials, sodium borohydride or hydrazine hydrate as reducing agent, polyvinyl alcohol, SDBS or polyvinylpyrrolidone(PVP) as the surface protective agent by solution chemical reduction method. The influences of different reducing agents and protective agents on the preparation of nano-silver were analyzed. The results from the XRD diffraction analysis and TEM show that it can be obtained high purity flake nano-silver in the reaction temperature range of 50-60°C.
Influence of Sintering Conditions on Electric Performance of Textured 92BNT-6BT-2KNN Ceramics
Authors: Ye Cheng Gen , Fu Fang , Shen Bo , Zhai Ji Wei
Published: June 2012

0.92(Bi0.5Na0.5)TiO3-0.06BaTiO3-0.02(K0.5Na0.5)NbO3(92BNT-6BT-2KNN) is a high-stain material due to the volume change which come from antiferroelectric-ferroelectric (AFE-FE) phase transformation. Textured 92BNT-6BT-2KNN with a Lotgering factor of 67% was obtained by templated grain growth (TGG) method using plate-like (Bi0.5Na0.5)TiO3（BNT）particles as templates. The influences of sintering process on Lotgering factor and strain were investigated. It was found that the Lotgering factor increased as sintering temperature increase and then decreased with further temperature increase. The changing tendency of polar and unipolar strain did not keep the same accordance with that of Lotgering factor. The maximum of Lotgering factor (79%) and polar strain (0.36%) was obtained when the sintering temperature was 1240°C and 1220°C, respectively, due to the decrease of density when high sintering temperature was employed. Also it was found that the lotgering factor and polar strain reached its highest values when the soaking time was 4h. All these proved that the density and grain orientation codetermined the strain of 92BNT-6BT-2KNN ceramics.
Piezoelectric and Strain Properties of Strontium-Doped BZT-BCT Lead-Free Ceramics
Authors: Bai Wang Feng , Li Wei , Shen Bo , Zhai Ji Wei
Published: June 2012

Lead-free piezoelectric ceramics, (Ba0.85-xSrxCa0.15)(Zr0.1Ti0.9)O3 (BSCZT, x=0.01-0.07), were prepared via a solid-state reaction route. The dielectric properties, ferroelectric properties, piezoelectric and strain properties of BSCZT ceramics were studied. The phase structure and microstructure were investigated by X-ray diffraction and scanning electron microscope, respectively. Results showed that dense ceramics with pure perovskite phase were obtained. At room temperature, the samples with x=0.03 exhibited excellent properties with large piezoelectric coefficient d33=534pC/N, planar mode electromechanical coupling coefficient kp=47.7%, thickness mode electromechanical coupling coefficient kt= 42% and high strain levels of 0.34%. In addition, the study of electrical properties suggested that the Curie temperature decreased linearly from 92oc to 73oc with the increasing doping content of strontium in BCZT ceramics. The remnant polarizations, piezoelectric coefficient and strain levels were all increased as the Sr content increased and then decreased with further increased Sr doping level, giving the maximum values at the Sr content of 3mol%. These results indicated that the BSCZT system is a promising lead-free material for applications in the future.
Influence of Ta5+ Doping on the Piezoelectric Properties of KNN Ceramics
Authors: Xiong Peng , Tan Guo Qiang , Ren Hui Jun
Published: June 2012

In this study, the KNbO3, NaNbO3and NaTaO3powders were synthesized by hydrothermal method and the KNN ceramics were prepared by conventional sintering technique. The physical phase constitution and morphology were analyzed by X-ray diffraction and SEM. The KNN ceramics sintering temperature and the influence of Ta5+doping on ceramic properties were explored. The results indicate that the optimal sintering temperature of KNN ceramics is 950°C, and the main phase is orthorhombic structure. After the substitution of Ta5+, the optimal sintering temperature is increased to 975°C. As the increase of doping amount, the piezoelectric properties have been significantly enhanced. The specimen doping 0.08 mol% Ta5+exhibits the enhanced electrical properties (d33=125pC/N, Qm=131, and kp=0.24).
Study on the Pressureless Sintering and Properties of (K0.5Na0.5)1-xLixNb1-yTayO3 Lead-Free Piezoelectric Ceramics
Authors: Hao Hang Fei , Tan Guo Qiang , Xiong Peng , Qin Bo , Ren Hui Jun
Published: June 2012

Potassium sodium niobate ((K0.5Na0.5)1-xLixNb1-yTayO3) powers were prepared by solid phase synthesis and (K0.5Na0.5)1-xNb1-yTayO3 lead-free piezoelectric ceramics were fabricated by the pressuerless sintering. The relationship among the powder phase composition and electric properties was studied. The results show that when x=0.5, the sintering temperature is 1050°C,and the polarization voltage is 3 kV/mm, the (K0.5Na0.5)1-xLixNb1-yTayO3 piezoelectric ceramics with the better piezoelectric properties are prepared. (The relative density is 94%, the piezoelectric constant d33=105pC/N, the planar electro-mechanical coupling coefficient kp=0.39, the medium loss tanδ=0.29, the mechanical quality factor Qm=45, and the dielectric constant εr=720). As the increase of the polarization votage, the ceramic piezoelectric properties are increased. When the polarization voltage E=3kV/mm, the polarization tends to be saturation on the whole.
Effect of SiO2 Content on the Electromagnetic Properties of CoZn-Z Type Barium Ferrite Prepared with Ferrous Micro-Beads
Authors: Sun Yue Miao , Qun Wang , Qu Zhi Xue , Shi Mei Wu
Published: June 2012

Ferrous micro-beads from fly-ash were used as starting material to prepare CoZn-Z type barium ferrite. As the main impurity in the beads, SiO2plays an important role on the electromagnetic properties of the ferrites. To investigate the effect of SiO2content, a series of CoZn-Z type ferrites with various contents of SiO2(1 wt%, 2 wt% and 5 wt%) were prepared with analytical pure Fe2O3and SiO2. The density, phase composition, microstructure and electromagnetic properties of the sintered samples were investigated. The results show that the permeability of samples alters little at a low content of SiO2about 1 wt%, but deteriorates dramatically when the addition of SiO2is above 2 wt%. The ferrous micro-beads were then treated by alkali cleaning to reduce the content of SiO2to about 1 wt%, and the samples prepared with these treated beads show a similar performance on the electromagnetic properties with pure CoZn-Z type ferrite.
The Structure and Ferromagnetic Properties of the Single Phase Bi0.95Eu0.05Fe0.95Co0.05O3 Nanoparticles Prepared by Sol-Gel
Authors: Li Xing Ao , Li Peng , Li Yong Tao , Yang Jian Ping , Bai Qiu Fei , Liu Zhong Ru , Wang Bo Lin
Published: June 2012

Bi0.95Eu0.05Fe0.95Co0.05O3 Nanoparticles sample was prepared by sol-gel process. The microstructure of samples was analysised by X-ray diffraction(XRD), the result indicated that it was the single phase rhombohedral perovskite structure. The morphology of samples was measured by scanning electron microsopy(SEM), the SEM photograph of samples indicated that the nanoparticles of Bi0.95Eu0.05Fe0.95Co0.05O3 sample were small than that of BiFeO3. The valence states of Fe ions in the samples was analysised by the X-ray absorption spectroscopy（XAS）. The XAS of Fe2p showed that it was the mixed valence states (Fe2+ and Fe3+) of Fe ions in samples, and the binding energy of Bi0.95Eu0.05Fe0.95Co0.05O3 was bigger than that of BiFeO3.The magnetic characteristics of the samples were measured by vibrating sample magnetometer (VSM)，the results showed that the weak metamagnetism were obtained from clear hysteresis loop and the magnetic saturation reached 0.408emu/g，compared with BiFeO3 sample, the magnetic properties were signiﬁcantly enhanced.
Study on Magnetic Liquids Properties for Sensor Design
Authors: He Xin Zhi , Li De Cai , Zhang Hai Na , Zhang Zhi Li
Published: June 2012

The physical properties of magnetic liquids are theoretically analyzed in this paper, such as the effect of the magnetic volume force on the free surface of magnetic liquids, the density spectrum of the magnetic liquids based on horizontal component of the magnetic volume force, the first order levitation principle and the second order levitation principle, the magneto-electric principle of magnetic liquids, the fluidity of magnetic liquids used as magnetic core and the fluxgate effect of magnetic liquids. Some methods to study the properties of magnetic liquids were provided by the authors, and the effects of the magnetic volume force on the free surface of magnetic liquids and the second order levitation effect were experimentally studied in this paper. The analysis methods that provided in this paper may be applied to the design of new sensors.
Experimental Study on the Second-Order Buoyancy of Magnetic Fluid
Authors: He Xin Zhi , Li De Cai , Yang Wen Ming , Zhang Hai Na
Published: June 2012

The buoyancy principle of magnetic fluid is one of the most attractive effects of magnetic fluid statics. But it is too difficult to calculate the buoyancy directly due to the complexity of magnetic field. Moreover, numerical calculation employs too many assumptions. So in this paper the experimental method is adopted to measure the second-order buoyancy received by permanent magnet immersed in magnetic fluid, which depends on the distance between the magnet and the wall of vessel. The influence of the diameter of cylindrical vessels, the size of magnets and the saturation magnetization of magnetic fluid on the buoyancy is also analyzed qualitatively.
Synthesis and Characterization of Nanocrystalline PZT Powders by a Simple Sol-Gel Method
Authors: Zhang Shao Peng , Wang Xiao Hui , Li Long Tu
Published: June 2012

Nanocrystalline lead zirconate titanate (PZT) powders with composition at the morphotropic phase boundary (MPB) were synthesized by a simple aqueous based sol-gel method, using lead nitrate, zirconium nitrate and tetrabutyl titanate as the starting materials. The sol could be easily transformed into gel, firstly heated at 120°C for 10h, then at 180°C for 24h. The thermal decomposition process of the gel was investigated by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. The effect of citrate addition amount on the calcining temperature was discussed. The results reveal that pure perovskite phase PZT powders can be obtained at a calcining temperature as low as 600°C. The average grain size of the powders was determined by transmission electron microscope and X-ray diffraction. The influences of calcining temperature and the pH value of the solution on the grain size were investigated. The sintering temperature and electrical properties of the ceramics derived by nano-powders were compared with those prepared by the conventional ceramic processing. The result shows that using the nanopowder, the sintering temperature could be reduced by about 100°C and the ferroelectric properties were enhanced.
Photoluminescence of ZrO2-ZnO Hybrid Nanotube Arrays Produced by Electrodeposition
Authors: Guo Li Min , Wang Xiao Hui , Li Long Tu
Published: June 2012

Highly ordered ZrO2 nanotube (NT) arrays were fabricated by anodization in organic electrolyte containing NH4F. The NTs have an opened porous structure at the top end. A facile electro-deposition technique was used to prepare ZnO quantum dots (QDs) in the pores of the ZrO2 NTs. Characterizations of SEM, XRD, HR-TEM were performed on the NTs. The results confirmed the formation of single-phase wurtzite ZnO nanoparticles in the ZrO2 NTs with a size around 20 nm. Photoluminescence (PL) spectra proved that the ZnO QDs coating had strongly enhanced the PL signal for blue (366nm) and green (503nm) light emissions of the hybrid NT arrays. That maybe arose from structure-dependent defects and oxygen vacancy in the hybrid layers.
Effect of Dispersant Content on Nanograined BME MLCC Powder Prepared by Aqueous Chemical Coating Method
Authors: Zhang Yi Chi , Wang Xiao Hui , Kim Jin Yong , Li Long Tu
Published: June 2012

Dispersion plays an important role in aqueous chemical coating process for the preparation of BaTiO3 based next generation BME MLCC powder, since it affects coating coverage and layer morphology of the BaTiO3 particles as well as the microstructure and dielectric properties of the ceramics. In this paper, Poly (acrylic acid-co-maleic acid) (PAM) is used as dispersant, its content influences are carefully investigated. It is known that low content of dispersant leads to not only poor dispersion, low coverage and irregular coating layer of BaTiO3 particles, but also bad temperature coefficient of capacitances and inhomogeneous microstructure of the resultant BaTiO3 ceramics, while excessive dispersant deteriorates the microstructure and performance by reducing the density of ceramic. With proper dispersant content, the particles are dispersed and coated perfectly, finally the dense X7R-satisfied ceramic are obtained with average grain size 103nm and fine microstructure, meeting the requirement of next generation MLCCs.
Properties of Yttria-Stabilized-Zirconia Based Ceramic Composite Abradable Coatings
Authors: Zhao Meng , Zhang Li Xia , Pan Wei
Published: June 2012

Abradable coatings are used in gas turbines to reduce the clearance between rotating and stationary parts, thereby improve the efficiency and reduce the oil consumption. Besides, the abradable coatings also have to prevent the alloy blade from wearing out. Common used abradable coatings have a diphase structure with hard, strong matrix and soft, self-lubricant phase. In this work, yttria-stabilized-zirconia was used as matrix, and layer-structured LaPO4 or Ti3SiC2 was lubricant phase. The samples were prepared by both pressureless sintering and SPS. The regularity of the mechanical properties, such as hardness and modulus, influenced by the lubricant content were studied. And the abradability was also measured by SRV high temperature friction tester.
Magnetron Sputtering of Tantalum Oxide Thin Electrolyte Film for Electrochromic Applications
Authors: Liu Chien Cheng , Liu Kuang I , Lin Hao Tung , Huang Jow Lay
Published: June 2012

Electrochromism have been widely investigated due to their potential applications such as automobile and building window. In this study, tantalum oxide thin films used as ion conducting layer were deposited on WO3/ITO at room temperature by magnetron sputtering. The thickness of tantalum oxide films were varied to investigate their effects on composition, microstructure, optical properties, and electrochromic properties determined by X-ray diffraction, UV-visible spectrometer, Atomic force microscope (AFM), and field-emission scanning electron microscope (FE-SEM). Experimental results indicated Ta2O5at thickness of 300 nm with low packing density were favorable for ions transmission deposited on WO3/ITO had better electrochromic property.
Stability of Dye Sensitized Solar Cells with Glass Frit Sealant
Authors: Chen Hui Yuan , Wang Sen Rui , Lin Hong , Wang Gang , Wang Sheng Han , Yang Gui Jun
Published: June 2012

Glass frit sealant was prepared under different conditions, including the ratios of each composition, grinding method of the sealants drying temperature, and sintering process. When the ratio of glass frit, terpineol and ethyl cellulose was fixed at 5:4:1, a uniform sealant film without any pore or crack was obtained. The rates of weight loss for the cells filled with water and electrolyte sealed with the glass frit films were investigated. The drying temperature of 25°C and sintering at 560°C with temperature gradients led to the smallest rate of weight loss both for water and electrolyte. Furthermore, the optimized sealant was fabricated into solar cells, which exhibited best stability by retaining 80% of their initial conversion efficiency, accompanying an electrolyte leakage rate as small as 0.12% after 800 hours tracking test at room temperature.
Synthesis of Cobalt Sulfide Nanocrystallites via an Efficient Microwave Hydrothermal Process
Authors: Li Bi , Cao Li Yun , Huang Jian Feng , Wu Jian Peng
Published: June 2012

Nanostructured cobalt sulfide(CoS) can be widely used as high energy density batteries, supercapacitors, solar photovoltaic materials and catalysts due to its excellent electronical, optical, magnetic and catalytic performance. In order to synthesize CoS crystallites in a efficient route, a facile microwave hydrothermal process was developed by using cobalt nitrate hexahydrate and thioacetamide(TAA) as source materials. The phase compositions and morphologies of the crystallites were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The influences of microwave hydrothermal temperature and time on the phase, grain size and morphology of the CoS nanocrystallites were particularly investigated. Results show that CoS crystallites can be obtained at the hydrothermal temperature of 180 °C. The as-synthesized CoS nanocrystallites are hexagonal phase that with the grain size of 10~30 nm. With the increase of hydrothermal time, the increase in particle size and the (102)-oriented growth are obviously.
Manufacturing Technology for Niobium Oxide Electrolytic Capacitor and Several Correlative Mechanisms
Authors: Li Bo , Zang Tao , Zhou Ji , Guo Hai , Qi Zhao Xiong , Wang Shuai
Published: June 2012

Methods of manufacturing Niobium oxide electrolytic capacitor were studied in this work. Some phenomena were found and the reasons or mechanisms were studied by using SEM(scanning electron microscope), EDS. In experiment, comparing with the type 6.3V/47μF tantalum capacitor, NbO powder were pressed to pellet as the capacitor anode, then the NbO capacitor was manufactured through the following processes: sintering, welding, anode oxidation, MnO2 decomposition and cathode coating. Its capacitance, leakage current, ESR(equivalent series resistance) and tgδ were measured and compared with that of the simily type of tantalum capacitor, and the suitable technical parameters were chosen
Influence of Operational Parameters on Oil-Water Separation Efficiency of Titanium Oxide Modified Alpha-Alumina Microfiltration Membrane
Authors: Zhou Jian Er , Hu Xue Bing , Wang Yong Qing , Zhang Xiao Zhen , Pan Jin Tian
Published: June 2012

During oil-water separation process, the influence of the operational parameters such as transmembrane pressure, crossflow velocity and feed temperature on the oil-water separation efficiency of TiO2 modified α-alumina microfiltration membrane was studied. The results show that the permeation flux of the membrane is 371.68 L•m-2•h-1 and the oil content in the permeation is 9.63 mg•L-1 when the TMP is 0.15 MPa, the crossflow velocity is 5.89 m•s-1 and the feed temperature is 30°C.
Influence of Microwave-Hydrothermal Temperature on Synthesis of TiO2 Thin Films on PMMA Substrates from Colloidal Anatase Aqueous Solutions
Authors: Zhang Zhi Qing , Huang Jian Feng , Cao Li Yun , Wu Jian Peng
Published: June 2012

Nanocrystalline TiO2 films were deposited on polymethylmethacrylate (PMMA) substrates by dip–coating process from colloidal anatase aqueous solutions. Microwave–hydrothermal process treating TiO2 colloidal solutions was applied to enhance crystallization under a mild condition and avoid post–treatment. The as–prepared TiO2 films were characterized and analysed by X–ray diffraction (XRD), UV–visible spectroscopy and atomic force microscopy (AFM). The photocatalytic degradation of Rhodamine B (RhB) under ultraviolet radiation was explored. Results show that pure anatase TiO2 is achieved rapidly using microwave hydrothermal process. The TiO2 suspension becomes uniformly disperse, stable and deposit-free after ultrasonic dispersion. The thin films deposited on unmodified PMMA substrates from the dispersive TiO2 colloidal solution are dense, homogeneous, crack–free, without visible agglomerates and show high photocatalytic activity without post-treatment. Rhodamine B has been degraded over 99 % after 180 minutes under UV irradiation.
Load TiO2 or TiO2-N on the Porous Carbon
Authors: Chen Jie , Mei Le Fu , Liao Li Bing
Published: June 2012

In this paper, porous carbon has been used to carry TiO2 and TiO2-N by a sol-gel process. The effect of soaking time, heat treatment temperature, and heat treatment time on the carrying efficiency have been studied. XRD experiments indicated that TiO2 and TiO2-N crystallized in anatase and rutile with the ratio of 3∶2. SEM images showed that island-like TiO2 and TiO2-N particles with diameters in the range of 1-5um, the biggest size is about 10um, were evenly coated on the surface of the porous carbon.
Fabrication of Oxide Compound Nano-Films Materials by LBL Self-Assembly Technology
Authors: Li Cai Xia , Zhu Peng Fei , Jiang Dan Yu , Lv Qing , Li Qiang
Published: June 2012

LBL (layer by layer) fabrication was based on the electrostatic attraction between the nanosheets host partial with electric charges and external object with opposite charges. By changing the property of the object, level defects can also be introduced, so that the nano-films with remarkable physica-chemical properties can be prepared. Tantalum oxide and cobalt oxide nano-films materials were made via LBL self-assembly technology in this work
Synthesis of n-Hexadecylphosphonic Acid-Coated Monodisperse Fe3O4 Superparamagnetic Nanoparticles
Authors: Tang Xue Song , Li Ming
Published: June 2012

Monodisperse Fe3O4 Superparamagnetic Nanoparticles Were Synthesized in N-Hexadecylphosphonic Acid/ Cyclohexane/ Water/ Ethanol Microemulsion under Solvothermal Conditions at 100°C. the Crystal Structure and Particle Size of Synthesized Fe3O4 Were Observed by X-Ray Diffraction (XRD) as Well as Transmission Electron Microscopy (TEM). the Results Show that the Nanoparticles Have a Cubic Crystal System and a Average Particle Size of about 10nm. each Nanoparticle Has a Single Crystal Structure. the Surface Chemistry of Synthesized Fe3O4 Nanoparticles Was Characterized by Fourier Transform Infrared Spectroscopy (FTIR), Indicating that the Nanoparticles Were Covered by a Layer of N-Hexadecylphosphonic Acid, which Made the Nanoparticles Totally Lipophilic. Magnetic Properties of the Nanoparticles Were Investigated by Using Vibrating Sample Magnetometer (VSM). the Result Reveals that the Saturation Magnetization (Ms) of the Nanoparticles Is Higher than 40 Emu/G and the Coercive Force Is near to 0. the Monodisperse Fe3O4 Nanoparticles Have Superparamagnetic Property and May Find Potential Applications in many Fields, such as Ferrofluids, Drug Loading and Release, Selective Biomolecular Separation and MRI.
Enhanced Visible Light Activity of Ag-Loaded TiO2 Nanotube Arrays by AC Electrodeposition
Authors: Zhao Jing , Zhao Jian Ling , Wang Xi Xin , Jia Yu Ying , Tang Cheng Chun
Published: June 2012

In this work, highly-ordered TiO2 nanotube arrays were prepared by constant-voltage anodization, followed by electrodeposition of Ag to obtain Ag-loaded TiO2 (Ag-TiO2) nanotube arrays via alternating current (AC) process. The results of SEM and XRD show that the morphology and crystal structure of Ag-TiO2 layer depend greatly on the electrodeposition parameters. Ag-TiO2 nanotube arrays prepared in 2.5 mmol/L AgNO3 solution by electrodeposition with applied voltage of 12 V for 1 minute performed the best photoelectrochemical current response and photocatalystic activity. The photocurrent density of Ag-TiO2 is 43.32 μA/cm2 under sunlight irradiation (70 mW/cm2), which is 4.2 times as that of unloaded TiO2 nanotube arrays. Methyl orange (MO) degradation rate with the Ag-TiO2 nanotube arrays achieves 52.13% after 90 min sunlight irradiation which is obvious higher than that of TiO2 nanotube arrays. The mechanism of enhancing photoelectrochemical activity of decorating titania with Ag has also been discussed in the view of energy band theory.
Biomimic Enamel Remineralization by Hybridization Calcium- and Phosphate-Loaded Liposomes with Amelogenin-Inspired Peptide
Authors: Luo Jing Jing , Ning Tian Yun , Cao Ying , Zhu Xiao Peng , Xu Xiao Hua , Tang Xu Yan , Chu Chun Hung , Li Quan Li
Published: June 2012

We here report a novel biomimetic mineralization strategy for enamel remineralization by intergration of calcium phosphate loaded and thermally triggered liposomes and a self-assembly amelogenin-inspired peptide. Firstly, calcium and phosphate loaded temperature sensitive liposomes were synthesized by Interdigitation-fusion method with 1,2-bis(palmitoyl)-sn-glycero-3-phosphor- choline (DPPC) and 1,2-bis(myristoyl)-sn-glycero- 3-phosphocholine (DMPC) at mass ratio of 9:1 . The liposomes were stable at room temperature, but slowly released calcium and phosphate ions if heated to 37 °C. Secondly, a novel polyanion amelogenin-inspired oligropeptide (Gln-Pro-Ala)4-Thr-Lys-Arg-Glu-Glu-Val-Asp ) was synthesized by standard solid-phase. Lastly, the mixture of peptide and liposomes solution was exposed to enamel surface at 37 °C. The results showed oriented enamel-like hydroxylapatite evenly deposited on enamel surface.
Preparation of Mineralized Electrospun PCL/Gelatin Scaffolds via Double Diffusion System
Authors: Guo Zhen Zhao , Li Hong , Guan Wei Cheng , Xue Bo , Zhou Chang Ren
Published: June 2012

For successful reconstruction of skeletal defects, a range of materials including ceramics, polymers and their composites have been developed. The goal of our work is to prepare mineralized PCL/gelatin composite scaffolds in a double diffusion system as implants for bone tissue engineering application. Fibrous PCL/gelatin scaffold fabricated via electrospinning followed by immersing into disodium-β-glycerophosphate(β-GP) (10 mg/ml) for 12h were used as substrates for calcium phosphate (CaP) mineralization. The precipitation reaction was biomimetically carried out in a double diffusion system for a week. The CaP minerals precipitated on the scaffold were characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and high-resolution transmission electron microscopy. The results show that apatite aggregates are combination of HAP, DCPD and ACP. β-GP can effectively promote the formation of CaP crystals. The composite scaffold fabricated in this paper hold promise for use in bone tissue engineering.
Effect of Zirconia Surface Roughness on Shear Bond Strength to Resin Cements
Authors: Hu Chen , Shao Long Quan , Yi Yuan Fu , Liu Qi , Deng Bin , Wen Ning
Published: June 2012

Despite the expanded application for zirconia in restoration dentistry, there is less clear recommendation in the literature regarding the relation between zirconia surface roughness and its shear bond strength to resin cements. The aim of this study was to assess the effect of surface roughness of Cercon zirconia on its shear bond strength to resin cements. 66 Zirconia rectangular specimens (10 mm×10 mm×3 mm) were prepared from Cercon zirconia blocks, finished using a diamond rotary cutting instrument, sintered, and then assigned into 6 groups. The specimens in the first group without polishing were used as control. Other groups were polished against 120#, 240#, 360#, 500# and 600# sand paper after sintered, respectively. Ceramic surface were analyzed by scanning electron microscopy (SEM) and Surface profilometer. 10 samples of each group were bonded with Variolink N resin cements respectively and submitted to shear bond strength test. Shear bond strength was measured and statistically analyzed. The results showed that the population means of 6 groups of samples were not equal. There was no significant difference between control group and 600# sand paper treated group, 500#, 360# and 240# sand paper treated groups (P>0.05), but a significant difference among the other groups (P<0.05). Findings of this study revealed that the shear bond strength might be raised by increasing the surface roughness of Cercon zirconia. Therefore, the surface roughness of Cercon zirconia has an effect on the shear bond strength, but is not the determining factor in clinical use.
Effects of Alveolar Bone Loss and Post-Core Design on Stress Distribution of Severely Damaged Canine
Authors: Gao Ya , Shao Long Quan , Deng Bang Lian , Zhou Shan Yu , Yi Yuan Fu , Deng Bin , Wen Ning
Published: June 2012

To investigate the influence of alveolar bone loss and post design on stress distribution of a severely damaged canine. The residual canal dentin wall in the cervical region was standardized at 0.5mm in thickness. Twelve two-dimensional finite element models were created. The models were varied in their alveolar bone loss. The post systems include computer-aided design/computer-aided manufacturing zirconium post, prefabricated glass fiber post, cast stainless steel post, and cast gold post. The numerical models were considered to be restored with an all-ceramic crown. A load of 100N was applied to the crown at an angle of 45 degree on the lingual surface, and Mises stresses were calculated. Finite element analysis revealed that cast stainless steel post system showed the lowest maximum Mises stress in the dentine at 86.46 MPa, while, glass fiber post resulted in the highest stress concentration in the dentin at 174.3 MPa. Stresses were reduced by increasing alveolar height. Loss of alveolar bone loss may lead to an increased risk of failure.
Inﬂuence of Thickness on Residual Stress Proﬁle in Veneering Ceramic Layered: Measurement by Hole-Drilling
Authors: Wang Lin Lin , Shao Long Quan , Yi Yuan Fu , Liu Qi , Deng Bin , Wen Ning
Published: June 2012

To compare thickness of veneering ceramics dependence of the stress profile in veneering ceramic layered on zirconia and metal frameworks. Cylindrical core materials dentine ceramic specimens whose diameter is 20.0mm, thickness is 0.5mm were made with customized method, and then Upcera zirconia and metal plate were veneered, the thickness of the veneering ceramics respectively were 1.25mm, 1.50mm and 1.75mm, a total of six groups (n=10). An CAD-CAM machine was used for the drilling procedure and residual stress proﬁle of all-ceramic crowns and metal-ceramic crowns was calculated. The mean residual stress of zirconia all-ceramic restorations were: respecitively, 60.15±5.54MPa for 1.25mm thickness of veneering; 53.37±5.12MPa for 1.50mm thickness of veneering; 45.64±4.53MPa for 1.75mm thickness of veneering. The mean residual stress of glass infiltrated alumina all-ceramic restorations were: respectively, 61.32± 5.76MPa for 1.25mm thickness of veneering; 52.45±5.35MPa for 1.50mm thickness of veneering; 45.89±4.26MPa for 1.75mm thickness of veneering. Residual stress proﬁle of all-ceramic restorations was significantly different among specimen groups of Y-TZP and Metal plate (P>0.05). There was also significantly different among specimen groups which had same thickness of the veneering ceramics but not belonged to same frameworks (P<0.01). As the depth increases, the stress gradually increases, reaching the maximum at the interface of MV or CV. The residual stress of frameworks was tensile stress, but the residual stress of veneering porcelain interior was compress. With the veneer porcelain thickness, the residual stress of the interface gradually reduce.
The Influence of Background Color to 3 All-Ceramic System Core Materials
Authors: Deng Bin , Liu Hong Chen , Yi Yuan Fu , Shao Long Quan , Wen Ning , Gu Bin , Liu Yi Han , Lu Rong Jian , Chen Ji Hua
Published: June 2012

To study the influence of background color to 3 all-ceramic system core materials.The chromaticity value of all samples that were put on noble metal, Ni-Cr alloy, Hg-Ag alloy and resign background were measured with chromatism instrument, and chromatic aberration among groups were calculated. The chromatic aberration of Empress II samples on different background color could be distinguished by human eyes, but those of Alumina and Zirconium were unable to being distinguished. In conclusion, the influence of background color to Empress II and In-Ceram Alumina of AL1 were lager. When chosen as core material, noble metals should be covered to keep prosthesis from clinical color-transform. As background to In-Ceram Alumina of AL2, it was unnecessary for resin to be covered. In-Ceram Alumina of AL3, AL4 and In-Ceram Zirconium weren’t affected by background color.
The Transmittance Test of 3 All-Ceramic System Core Materials
Authors: Lu Rong Jian , Liu Hong Chen , Yi Yuan Fu , Shao Long Quan , Wen Ning , Gu Bin , Liu Yi Han , Deng Bin
Published: June 2012

This experiment was to study the transmittance of 3 all-Ceramic system core materials, including 4 colors of Vita In-ceram Alumina,4 colors of Vita In-Ceram Zirconium and 3 colors of Empress II,and to provide basis for clinical choice of core materials.With Vita alpha veneer porcelain as control,the transmittance of all samples was determined with spectrophotometer under D65 standard source.The transmittance of materials was 1.434%~3.843% for Vita In-Ceram Alumina,0~0.587% for Vita In-Ceram Zirconium,5.620%~6.665% for Empress II.As a whole,the transmittance of Empress IIwas the best of 3 core materials,that of In-Ceram Alumina was the worse,that of Vita In-Ceram Zirconium was the worst.
Preparation and Photo-Catalysis Properties of Fe3O4/TiO2 Nanocomposite
Authors: Shi Dan , Zhang Zhi Li , Li De Cai , Han Qi , Xing Tie Peng
Published: June 2012

As a Kind of Most Common Used Photocatalyst, TiO2 Nanomaterials Existing Disadvantages on Low Light Energy Utilization in Visible Light Range and Difficulty on Recycle. in Our Study, Different Proportions of Fe3+ and Fe2+ Ion Were Doped with Nano-Ti02 Particles in Structure of Rutile Type through Method of Chemical Precipitation. the Result Showed that Nano-Composites Formed by TiO2 Coexist with Fe3O4, with the Average Size of the Composite Particles Nearly 20 Nm. the Photo-Catalyst Performances of the Composite Have Improved Largely, and so the Relatively Optimized Preparation Conditions Were Presented.
Hydrothermal Synthesis and Characterization of LiZr2(PO4)3
Authors: Niu Jin Ye , Chen Zhi Wei , Sun Cheng Gong , Feng Liu , Li Zheng Min , Li Jie
Published: June 2012

Lithium dizirconium phosphate (LiZr2(PO4)3) possesses good ionic conductivity owing to its unique framework structure and can be used as favorable anode material in Li-ion battery. LiZr2(PO4)3 is commonly prepared by solid phase reaction in which higher temperature is needed and pure LiZr2(PO4)3 without other phases is difficult to obtain in the final products. In this paper, low cost hydrothermal synthesis of pure (LiZr2(PO4)3) was studied. Effects of the hydrothermal conditions (molar ratios of Li+ to ZrOCl2, addition of HF, pH values of reaction system and hydrothermal temperatures) on the phase composition of the products were investigated. The results showed that pure LiZr2(PO4)3 was successfully prepared at lower temperature of 80°C for 24h with the addition of HF when the pH value was adjusted to 5.0 and the molar ratio of Li+ to ZrOCl2 was 0.5 with the concentration of ZrOCl2 as 0.6mol/L. The phases and purity of the final products were characterized by XRD analysis.
Synthesis and Characterization the Intercalation Compound of SnS2-Ethylenediamine by Hydrothermal Reaction
Authors: Lv Qing , Li Cai Xia , Jiang Dan Yu , Li Qiang
Published: June 2012

The intercalation of ethylenediamine (en) into SnS2 was synthesised by hydrothermal reaction at the temperature of 180 °C.And then dispersed the intercalation compounds in N, N-dimethylformamide (DMF) by stirring 48h,getting a light yellow sol ,with the nature of uniform ,transparent and stable.Analysised the structural of the product by means of X-ray powder diffraction (XRD) .The morphology of sol was characterized by using of transmission electron microscopy (TEM).The UV-Vis spectrophotometer was utilized for the absorbance of the colloidal.The results show that en has been successfully inserted into the layer of tin disulphide,and the target products is of high purity and good crystal.The sol is of high stability and homogeneity, and have the strongest absorption at the Wavelength of 270nm.
Synthesis of AlN Powder from Precipitation Precursor by Carbon Thermal Reduction in Flowing Nitrogen
Authors: Lu Hui Feng , Qin Ming Li , Jiang Sui He , Chu Ai Min , Zhang Yan , Qu Xuan Hui
Published: June 2012

Abstract. Aluminum nitride(AlN) powders were synthesized by carbonthermal reduction of Ammonium aluminum carbonate hydroxide(AACH). The AACH were prepared from ammonium alum and ammonium hydrogen carbonate by precipitation method and AACH adhere to carbon black during precipitation. The precursor has a high reaction activity (near 100% of nitridation ratio after heated in flow nitrogen at 1400°C, 2h). After carbon remove in muffle furnace at 700 °C, white color Aluminum nitride (AlN) powder attained and mean size is 100 nm. The specific surface area of the powders decreased with increasing of concentration of ammonium alum and ammonium hydrogen carbonate, which range from 22 m2/g to 7 m2/g, particle size vary from 58 to 120 nm. Phase presents in the products during heating in flowed nitrogen were observed by X-ray diffraction. The -Al2O3 formed when the precursor heated to 1200°C, AlN was founded at 1300°C and the reaction ended at 1400°C, the reaction temperature and annealing time were much lower than nitridate the mixture of Al2O3 and carbon black. Particle size was increased when reaction temperature increased from 1400°C to 1550°C.
Preparation of Nanometer Carbon Spheres by Hydrothermal Synthesis Method
Authors: Zhang Ning , Cui Xing Yu , Zhao Xiao Jun , Zhou Yong Hui , Kan Hong Min
Published: June 2012

The present work used hydrothermal synthesis method utilizing glucose as carbon source to obtain homogeneous nano-sized carbon spheres. The holding time and the concentration of glucose have a remarkable effect on the microstructure of nanometer carbon spheres. When synthesized at a constant temperature and kept the same in the productivity, the lower concentration of glucose or the shorter holding time, the easier to acquired homogeneous and tiny nanometer carbon spheres
Controlled Synthesis of Hierarchical Flower-Like CuS Spheres by a Facile Microwave Hydrothermal Method
Authors: Qi Hui , Huang Jian Feng , Cao Li Yun , Wu Jian Peng
Published: June 2012

–Hierarchical flower–like CuS spheres have been synthesized by a facile microwave hydrothermal (MH) method using cetyltrimethylammonium bromide (CTAB) as the surfactant. The as–prepared CuS crystallites under different CTAB contents were characterized by X–ray diffraction (XRD), field–emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Results show that the CTAB–assisted CuS particles have hierarchical flower–like microstructures that were assembled by thin nanoflakes with thickness of 10~20 nm. The corresponding HRTEM images reveal that these nanoflakes are composed of many nanoparticles with average size of about 7 nm. Moreover, when increasing the CTAB contents from 0 g⁄mL to 0.02 g⁄mL, the as–prepared CuS particles were found to have better dispersion stability with decreased average sizes of the hierarchical ﬂower–like spheres. Comparing with the bulk CuS particles, the related UV–vis absorption spectrum of the as–prepared crystallites exhibits an obvious red shift with the absorption peak at 739 nm.
Synthesis of Carbon Nanotubes from Silicalite-1-Coated Substrates
Authors: Zhao Wei , Pokhrel Ashish , Kim Hyun Sung , Kim Hyung Tae , Kim Ik Jin
Published: June 2012

Assembled monolayer of silicalite-1 (AMS) microcrystals on Si wafer for carbon nanotube (CNT) growth has been prepared by the rubbing method. Iron oxide (α-Fe2O3, hematite) catalyst films were deposited onto silicate-1 monolayers from a Fe2O3 target by radio frequency (rf)-sputtering. This approach has the potential for producing well-aligned CNTs with controlled diameter from predesigned silicalite-1 templates by catalytic chemical vapor deposition (CCVD). Silicalite-1 monolayer oriented with faces parallel to Si wafer showed only the planes in the forms {0 k 0} lines at (020), (040), (060), (080) and (0100) by XRD. The formation and growth of CNTs by CCVD were achieved on the pores of silicate-1 crystals whereby the pores can be defined as confined spaces (channels, 5.60 Å) in nanometer dimensions acting as a template for a fine dispersion of well-defined Fe2O3 (10-15 nm) particles.
Single Phase Ti2AlC Powder Synthesized from Ti-Al-0.6~0.9TiC-0.1Sn Mixture
Authors: Li Meng Qi , Zhai Hong Xiang , Huang Zhen Ying
Published: June 2012

A high purity of Ti2AlC powder has been synthesized by pressureless sintering a mixture of Ti-Al-TiC-Sn (Sn as an additive) powders. Four recipes with different mole ratios of Ti-Al-TiC-Sn were examined at sintering temperature from 1400°C to 1480°C. A high purity of Ti2AlC powder can be obtained by sintering all these four recipes at temperature 1450°C for 10 min in an Ar atmosphere. The synthesis of Ti2AlC on this large mole ratio scale of starting materials is associated with the evaporation of Al at high temperature and the structure stability of Ti2AlC. From the X-ray diffraction analysis, a reaction path for the Ti2AlC formation is proposed. Scanning electron microscopy was also used to characterize the samples.
Wet Foam Stabilized by Amphiphiles to Tailor the Microstructure of Porous Ceramics
Authors: Pokhrel Ashish , Zhao Wei , Kim Ik Jin
Published: June 2012

Wet foams formed through direct foaming were stabilized using various concentrations of amphiphilic particles that could control pore size and porosity. Microstructures and wet foam stability were tailored by amphiphile concentration, particle concentration, contact angle and pH of the suspension to obtain crack-free porous solid after sintering. The influence of these parameters on the porosity was satisfactorily described in terms of combined effects of the contact angle and particle concentration of the initial suspensions, directly affected by amphiphile concentration. Pores were obtained with sizes of c. a 30 - 300 µm and porosities of over 80%.
Preparation of M-AlN Suspensions for Aqueous Gelcasting
Authors: Guo Jian , Qiu Tai , Yang Jian , Feng Yong Bao
Published: June 2012

M-AlN (surface modified aluminum nitride powder) suspensions for aqueous gelcasting were prepared Using NH4PAA as dispersant. The effects of pH value, NH4PAA amount and solid content on the rheological behavior of M-AlN suspensions were investigated. The results showed that low viscosity M-AlN aqueous suspensions with high solid content up to 55vol.% were obtained under the condition that the amount of NH4PAA was 0.9 wt. % of M-AlN powder, and pH value was about at 6.8. In spite of this, these suspensions still show a viscosity lower than 0.12 Pa•s at 100s-1, suggesting a good fluidity which can satisfy the requirement of gelcasting.
Synthesis of Si-N-C Ceramic Composites by Pyrolysis of Polysilazane and Polycarbosilane
Authors: Bao X.Y. , Li Song , Tang Xiao Xia , Zhang Yue
Published: June 2012

Non-oxide ceramics derived from organo-elemental precursors in the system Si-N-C has attracted much attention for its excellent properties. Typically, the Si-N-C ceramic shows homogeneous elemental distribution, better high-temperature stability and oxidation resistance which making them attractive for applying in various branches of technology. A novel amorphous ceramic is fabricated from precursors mixed by polysilazane (PSZ) and polycarbosilane (PCS). The Si-N-C ceramics (PSZ/PCS=2 (w/w)) are heat-treated between 1200°C and 1500°C in nitrogen to crystallization of microcrystalline α-Si3N4 and nanocrystalline SiC. The obtained Si-N-C ceramics are characterized by density, ceramic yield, porosity, X-ray diffraction and Scanning electron microscope to analyze the crystallization and microstructure. The experimental results indicate that the ratio of PSZ/PCS and the annealing temperature have a big influence on the crystallization behavior.
Influence of the Dispersant on the Bead Milling of Alumina
Authors: Yuan Ling , Qi Long Hao , Pan Wei
Published: June 2012

The high-pure alpha-alumina powders with some agglomerate were treated by bead milling and their sintering behaviors were studied in this paper. During the treatment, the effect of different types and different amounts of dispersants was also investigated. It was shown that optimum dispersant content was 0.5% citric acid and optimum milling time is 6 hours. The sintering property of alumina powder after bead milling was significantly improved. Their relative density after sintering at 1500 degrees can reach 99.3% while the raw powders’ can only reach 90% at same condition.