bluuebunny/crossref_metadata_2025 huggingface dataset:
La Doped Layered Structure Low-Voltage ZnO Varistor
Authors: Gao Xing , Gan Guo You , Wang Li Hui , Yan Ji Kang , Yi Jian Hong , Du Jing Hong , Zhang Jia Min
Published: June 2012

A novel fabricated technique, by feeding two sets of different ZnO formulations powder in a die by parts, molded only once to produce layered structure(including layer A and layer B) low-voltage ZnO varistor. The samples are examined by using energy dispersive X-ray spectroscopy (EDS), electron probe microanalysis (EPMA), scanning electron microscope (SEM) and DC electrical measurements. EDS and EPMA data indicate that doped elements only exists in layer A, The results of SEM indicate that secondary phases are formed at grain boundaries in layer A, not found in layer B. It is found that the electrical properties of low-voltage varistor are improved without reducing thickness and changing energy absorption capabilities. The higher nonlinearity coefficients, lower breakdown fields and leakage currents of layered structure low-voltage ZnO varistor, as compared to those of ZnO varistor fabricated from the conventional route. The improved current-voltage properties are attributed to the band structure difference in both sides grains, due to the different ion concentration and species in both sides of grain boundary. Layered structure varistor also has more simpler prepared technology than multilayer chip varistor.
B2O3-Doped ZnO-Pr6O11 Based Varistor Ceramics
Authors: Wang Yue Ping , Peng Zhi Jian , Feng Hai , Wang Cheng Biao , Fu Zhi Qiang , Qi Long Hao , Miao He Zhuo
Published: June 2012

B2O3-doped ZnO-Pr6O11 based varistor ceramics were fabricated by sintering samples at 1350 °Cfor 2h with conventional ceramic processing method. The microstructure and electrical properties of the as-prepared samples were investigated. X-ray diffraction analysis showed that after the addition of B2O3 with the amount designed in this study, no new phase was examined in the detection limit. Through scanning electron microscopy it was found that the doping of B2O3 can promote the growth of ZnO grains, and the sintering of the samples. The result of electrical properties indicated that the nonlinear coefficient and varistor voltage of the samples could be improved to some extent with appropriate doping amount of B2O3, resulting in the highest nonlinear coefficient 6.7, lowest leakage current 329 μA/cm2, and highest varistor voltage 92.4 V/mm, respectively.
Fabrication and Electrical Properties of Vanadium Pentoxide Fibres
Authors: Zhang Wei , Li He Ping , Pan Wei
Published: June 2012

In this work, orthorhombic vanadium pentoxide (V2O5) fibres have been prepared by electrospinning from a sol-gel precursor and the following calcination at 723 K. Structure, composition and morphology of the obtained V2O5 fibres are characterized. The Raman results show that the obtained V2O5 fibres don’t undergo a semiconductor-metal transition. And their high temperature electrical properties are discussed according to a thermally activated small-polaron hopping process.
Electrical and Physical Properties of the Bi3.25La0.75Ti3O12 Ferroelectric Thin Films Prepared by Conventional Temperature Annealing Process
Authors: Yang Fann Wei , Chen Kai Huang , Cheng Chien Min
Published: June 2012

We have investigated the structure and ferroelectric properties of the Bi3.25La0.75Ti3O12 (BLT) thin films on SiO2/Si substrate fabricated by sol-gel method. We used the BLT films were annealed at various temperatures of 600, 650, and 700°C for one hour by conventional furnace annealing (CTA). The temperature dependence of leakage currents densities of ferroelectric BLT thin films. The crystalline structure of the prepared BLT thin films was analyzed by X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) was used to observe the film thickness and the surface morphology including grain size and porosity. The leakage current density and capacitance of thin film were measured by HP4156C.
Synthesis of Cubic Ni Nanoparticles by Electric Current Heating Method Using Ni Wire
Authors: Tada Ikuhisa , Okamoto Tomoichiro , Kuroki Yuichiro , Hagizawa Takumi , Oh-Ishi Keiichiro , Takata Masasuke
Published: June 2012

Nickel wire was used as a starting material to fabricate Ni nanoparticles. A glass substrate was placed above the wire to deposit the particles. The wire was heated by applying a d. c. voltage in the range of 2.2 ~ 4.0 V in oxygen atmosphere until the wire broke. White deposits were observed on the substrate after the heating. The TEM observation revealed that the deposits consisted of cubic nanoparticles with the edge lengths of 2 ~ 200 nm. The size of the particle tended to decrease with decreasing voltage. The particles were covered with films of approximately 4 nm in thickness. After reducing in hydrogen at 250°C for 30 min, the thickness of the films on the cubic particles decreased and the XRD peak intensity attributed to NiO decreased. Consequently the particles were found to be cubic Ni nanoparticles covered with NiO thin films.
Ferroelectric Properties and Microstructures of Tb4O7-Doped Bi4Ti3O12 Thin Films
Authors: Liu R.F. , Mei X.A. , Chen M. , Huang C.Q. , Liu J.
Published: June 2012

Tb-doped bismuth titanate (BixTbyTi3O12 BTT) thin films were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique, and the microstructures and ferroelectric properties of the films were investigated. Microstructure studies indicate that all of BTT films with well-developed rod-like grains consist of single phase of a bismuth-layered structure without preferred orientation. The experimental results indicate that Tb doping into Bi4Ti3O12 results in a remarkable improvement in ferroelectric properties. The remanent polarization ( Pr ) and coercive field ( Ec ) of the BTT film with y=0.6 were 22 μC/cm2 and 85 kV/cm, respectively. After 3 × 1010 switching cycles, 20% degradation of Pr is observed in the film.
Ferroelectric Properties of Bismuth Titanate Ceramics by Sm3+/V5+ Substitution
Authors: Huang Chong Qing , Chen Min , Liu R.F. , Mei X.A. , Liu J.
Published: June 2012

The ferroelectricity of Bi3.25Sm0.75Ti3O12 (BST), and Bi3.25Sm0.75Ti2.97V0.03O12 (BSTV) ceramics prepared at 1100°C by a conventional ceramic technique was investigated. These ceramics possess random-oriented polycrystalline structure. The remanent polarization (Pr) and coercive field (Ec) of the BST ceramics are 16 µC/cm2 and 64kV/cm, respectively. Furthermore, V substitution improves the Pr value of the BST ceramics up to 25 μC/cm2, which is much larger than that of the BST ceramics. Therefore, co-sustitution of Sm and V in is effective for the improvement of the ferroelectricity of Bi4Ti3O12 ceramic.
Enhanced Piezoelectric Properties of (Na0.535K0.485)0.905Li0.095(Nb0.94Ta0.06)O3 –(Na0.5Bi0.5)TiO3 Lead-Free Piezoelectric Ceramics in the MPB Composition
Authors: Shen Zong Yang , Xiao Zu Gui , Li Yue Ming , Wang Zhu Mei , Hong Yan
Published: June 2012

In this paper, end members of tetragonal phase (Na0.535K0.485)0.905Li0.095(Nb0.94Ta0.06)O3(abbreviated as NKLN) and rhombohedral phase (Na0.5Bi0.5)TiO3(abbreviated as NBT) were used to fabricate dense (1-x)NKLN-xNBT (x=0, 0.005, 0.01, 0.02, 0.03, 0.04) lead-free piezoelectric ceramics. By increasing the NBT content x value, the crystalline structure changes from tetragonal phase to rhombohedral one across a morphotropic phase boundary (MPB) composition of x=0.02. In this MPB composition, enhanced electrical properties were obtained as follows: piezoelectric constant d33=202 pC/N, planar electromechanical coupling coefficient kp=39.6%, relative dielectric constant εr=1020 and dielectric loss tgδ=2.67%, indicating that this ceramic was a promising lead-free piezoelectric material for practical applications.
Molten Salt Synthesis of Ni0.5Zn0.5Fe2O4 Ferrites
Authors: Jiang Hong Tao , Wang Xiu Feng , Wang Li Li , Yu Cheng Long
Published: June 2012

In this paper, Ni0.5Zn0.5Fe2O4ferrite ceramics were produced with Ni0.5Zn0.5Fe2O4powders prepared by reaction in a molten salt using Fe2O3, NiO and ZnO powders as raw materials. Ni-Zn powders were characterized by X-ray diffraction (XRD). Density and shrinkage in diameter of Ni0.5Zn0.5Fe2O4ceramics were measured. MicroSubscript text structures were observed using field emission scanning electron microscopy (FESEM), and magnetic properties were examined by HP4291B impedance analyzer. XRD pattern indicated that the powders synthesized at 900°C for 1h were pure spinel Ni0.5Zn0.5Fe2O4phase. Via the measurement of density and shrink in diameter, optimal temperature was 1200°C and holding time was 2h, which was in accord with the results concluded from micrographs. FESEM images illustrated that the average grain size increased with increasing holding time, which followed the Ostwald liquid growth mechanism. At lower frequencies, the initial permeability (μi) increased from 86.65 to 183.48 with increasing holding time, while the threshold frequency decreased from 13.3MHz to 8.52MHz, which implied the initial permeability (μi) variation complied with the Snoek law to some extent.
Fabrication of Iron Carbide and Nitride Ceramics with Controlled Magnetic Properties by the Non-Oxide Sol-Gel Process
Authors: Lao Xun , Yan Xiao , Xie Jiao , Li Ya Li
Published: June 2012

The carbodiimide-based non-oxide sol-gel process is a novel route to non-oxide nitride and carbide ceramics. This process has been applied to fabricate ternary or binary silicon based nitride and carbide ceramics. Based on this non-oxide sol-gel process, iron carbide and nitride have been fabricated by reaction of iron trichloride with bis(trimethylsilyl)carbodiimide to form FeCN gel followed by pyrolysis in argon flow at different temperatures. The iron carbide material obtained at 700 °C exhibits hard ferromagnetic properties whereas α-iron along with iron nitride formed at 1300 °C shows soft ferromagnetic properties. Therefore, iron carbide and nitride ceramics with controlled magnetic properties can be obtained along this novel non-oxygen sol-gel process by controlled pyrolysis. The pyrolysis behavior was investigated based on thermal gravimetric analysis coupled with differential scanning calorimetry. The phase structures of the iron carbide and nitride are identified by X-ray diffraction and the magnetic properties of the materials are measured by magnetometer.
Study on Magnetic Fluid Static Seal of Large Gap
Authors: Li De Cai , Zhang Hai Na , Zhang Zhi Li
Published: June 2012

Researchers have been studying the magnetic fluid seal of small gap in the past. In order to meet the static seal requirements of large gap in aviation, aerospace, metallurgy, and so on. We set up the experimental rig of magnetic fluid static seal and designed the static seal of magnetic fluid. In the experimental rig, we studied the static seal of magnetic fluid and obtained the relationships among the burst pressure and the amount of injection of magnetic fluid, seal gap, temperature and magnetization in the experimental rig. In theory, we calculated the distribution of magnetic field under the seal gap and reasoned sustained pressure and temperature and calculated the burst pressure in different gaps and different saturation magnetization. We analyzed the experimental and theoretical results in detail. The theoretical analysis and tests indicated that magnetic fluid seal of large gap and large diameter can sustain a definite pressure and meet the requirements of practical problems.
Structure Design of Magnetic Fluid Static Seal at Large Diameter Flange
Authors: He Xin Zhi , Li De Cai , Zhang Hai Na , Zhang Zhi Li
Published: June 2012

In order to meet the requirements of the static seal at large diameter in chemical industry, aerospace industry and military industry, we designed a magnetic fluid static seal at large diameter flange and set up a test rig. We studied the effect of magnetic fluid static seal on the test rig. Finally, we obtained the relationship between the anti-pressure capacity and the number of the seal stages. We also calculated the distribution of the magnetic field in the seal gap and the anti-pressure capacity in theory. The theoretical analysis and the experiment result indicate that the design of the magnetic fluid static seal at large diameter flange is feasible and can be used to meet the practical problems.
Properties of Fluorinated Surfactant and Wetting Effect on Fe3O4 Nanoparticles
Authors: Cui Hong Chao , Li De Cai , Wang Cui
Published: June 2012

In this paper, we briefly introduce the magnetic fluid; then investigate the distinctive properties of F element; further, describe the exceptional properties of fluorinated surfactant in five aspects; at last, we through formed contact angle analysis the wetting effect of fluorinated surfactant coated on Fe3O4 nanoparticles preliminary.
Effects of Sm3+ Doping on the Photoluminescence Properties of Ca9Eu1-xSmx(VO4)7 Red-Emitting Phosphors
Authors: Liu Li Hong , Xie Rong Jun , Sun Xu Dong , Huang Qing , Hirosaki Naoto
Published: June 2012

This paper reports the photoluminescence properties of Ca9Eu1-xSmx(VO4)7 (x=0.2-0.4) synthesized at 1250 oC in air for 12 h using traditional solid-state reaction method. With the increase of Sm3+ substitution amount, purity Ca9Eu1-xSmx(VO4)7 phase was obtained even when the Eu3+ ions were totally substituted by Sm3+. The experimental results showed that when Sm3+ was codoped with Eu3+ into Ca9Eu1-xSmx(VO4)7 crystal structure, Sm3+ would act as a sensitizer and transfer the excitation energy to Eu3+ ions and finally enhance the emission intensity of Ca9Eu1-xSmx(VO4)7 under 405 nm excitation, which leads to more favorite of this kind of phosphor used in UV LED based white LEDs.
Effects of PEG on Properties of SrAl2O4:Eu2+, Dy3+ Long Afterglow Phosphors Prepared by Combustion Synthesis
Authors: Liu Xiao Xia , Liang Min , Peng Gui Hua , Liang Zhen Hua
Published: June 2012

SrAl2O4:Eu2+, Dy3+ long afterglow phosphors were prepared by combustion synthesis and the influence of PEG dosages of the long afterglow phosphor on the luminescent properties was studied. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectroscopy (PL) and screen luminance meter. The main phase of the combustion products is SrAl2O4 with monoclinic crystal structure and the impurity phase content is reduced by adding PEG. Compared to the phosphor without PEG additive, the emission wavelength of the phosphor does not change, while the intensity of them is obviously enhanced. The optimum content of PEG was 0.4 mol% of the Sr2+, and the maximum initial brightness is 19110 mcd/m2.
The h-BN Protective Method Used for the Synthesis of Highly Uniform Spherical Si-Based Oxynitride Phosphors
Authors: Tang Jia Ye , Zhang Wen Hua , Xu Xin
Published: June 2012

The highly uniform spherical Si-based oxynitride core-shell structured phosphors with narrow size distribution and non-aggregation were successfully fabricated by the h-BN protective method for the first time. Firstly, the raw metallic ions (rare earth and alkaline earth ions) were coated on the surface of SiO2 templates via the urea homogeneous precipitation method. Then the core-shell precursor particles were coated with a H3BO3 layer, which was transformed to a h-BN protective film in the reduction condition. At last, the spherical core-shell structured oxynitride phosphors were synthesized through a gas reduction and nitridation method. The as-received phosphors show excellent luminescence properties due to the 4f65d-4f7 transition of Eu2+ under the excitation of UV and blue lights. The homogeneous spherical phosphors are expected to have excellent dispersing and coating properties, which are very important for LED and PDP applications.
Zinc Oxide Films Doped with Aluminum, Gallium or Tin Prepared by Dip Coating Process Using Ethanol Solution
Authors: Sawada Yutaka , Ohkubo Hayato , Seki Yoshiyuki , Lin Keh Moh , Sano Kazuyuki , Seki Shigeyuki , Uchida Takayuki , Hoshi Yoichi
Published: June 2012

Transparent conducting films of aluminum-, gallium or tin-doped and undoped zinc oxide were fabricated by dip coating process and post-deposition annealing in reducing gas atmosphere. Films were fabricated using zinc acetate and diethanolamine (stabilizer) with aluminum chloride hexahydrate, gallium chloride or tin (IV) chloride dissolved in ethanol. Dip coating and heating at 600°C in air were repeated ten times before annealing at 600°C in N2-0.1%H2. The average film thickness was 240 nm. The average visible transmittance exceeded 80%. Approximately 1 at.% of aluminum- or gallium-doping remarkably increased the carrier electron concentration and lowered the mobility. The lowest resistivity (6.57×10-3 Ω∙cm) was achieved by doping of 0.8 at.%Al; the carrier electron concentration, the movility and the average visible transmittance were, 3.6×1019 cm-3, 28 cm2∙V-1∙s-1 and 85%, respectively. Gallium-doping resulted in the lowest resistivity (8.09×10-3 Ω∙cm) at 1 at.%Ga with the carrier concentration of 2.9×1019 cm-3 and the mobility of 25 cm2 V-1 s-1. Tin doping increased the resistivity. The resistivities, carrier electron concentrations and mobilities were compared with reported values deposited by other deposition process.
The Synthesis of TiO2 Nanoarray Films on Glass Substrate by Anodic Oxidation Method
Authors: Zhu Xiao Yan , Wang Xiao Qiang , Guo Jing , Li Yue Liu
Published: June 2012

In this work, titanium films , 500nm thick, are rf sputtered onto glass substrates held at 500°C. The resulting films are then anodized at a constant potential in an electrolyte using a platinum counter electrode. Ti films were synthesized by RF magnetron sputtering on glass substrates. The anodizaton process resulted in the formation of titania nanoarrays. The samples are annealed at different temperature to induce crystallinity. XRD results indicated that the optimal annealing temperature is 500°C, the film is anastasia phases. Atomic force microscope (AFM) show that the microstructure is nanoporous pillar array. The AFM depth is about 21nm. The roughness average (Ra) of films is about 1~3nm. Then the TiO2 nanoarry film is integrated into DSCs structure, and I-V Characteristic of cell is studied preliminarily.
Fabrication of ZnO Nanospheres and Application to Dye-Sensitized Solar Cells
Authors: Wang Yan Xiang , Zhao Bing Xin , Sun Jian
Published: June 2012

In this paper, pure ZnO nanospheres and IO3- ions doped ZnO nanospheres were prepared by heating under reflux with zinc acetate and diethylene glycol as raw materials, and the ZnO dye-sensitized solar cells (DSCs) were prepared. The influences of reaction time and IO3--ions dope on ZnO properties were studied. DSCs properties prepared with obtained ZnO nanospheres were investied. ZnO nanospheres were characterized by XRD, SEM and infrared absorption spectrogram. The results showed that when the temperature was 160°C, ZnO nanospheres with diameter 100-800nm were obtained. When reaction time was 2h, ZnO diameter was about 500nm. When the reaction time was 24h, the diameter of ZnO was about 800nm with wider distribution. The ZnO DSCs were prepared by using ZnO nanopowders with different reaction time as photoanode. The photoelectric conversion efficiency of 24h-ZnO DSCs was the highest. The photoelectric conversion efficiency, open circuit voltage, short-circuit current and fill factor were 2.15%, 0.64V, 6.47 mA•cm-2, 0.52, respectively.
Preparation and Performance of Ni-YSZ/YSZ Co-Ceramic Using Multiple Gel-Tape Casting
Authors: Yi Zhong Zhou , Zhai Feng Rui , Tian Hong , Xie Zhi Peng
Published: June 2012

Use starch, corn meal and activated carbon as pore-making agent, Ni-YSZ/YSZ composite ceramic green body was prepared by multiple gel-tape casting with acryloyl ammonium-polyvinyl alcohol. The specimen was sintered at 1450°C for 4h, then reduced in hydrogen atmosphere at 800°C for 4h, Ni-YSZ/YSZ composite ceramic disk was obtained, the porosity, thermal expansion coefficient, electrical properties and microstructures of the specimen was tested. The results showed that the porosity of Ni-YSZ/YSZ composite ceramic disk reaches about 30% when use starch as pore-making agent, expansion coefficient is proportional to porosity, both of them reduced with the temperature increased. The YSZ is continued and compact with network structure, Ni particulates are well distributed in it, suitable for intermediate temperature solid oxide fuel cell anode materials. Image analysis of SEM micrograph showed that the structure is loose, porous, uniform and compact in Ni/YSZ/YSZ multi-layer composite ceramics, which meet the requirement of intermediate temperature SOFC.
Electrical Conductivity and Characterization of CeO2 Doped 8YSZ Electrolyte with 2%wt CuO Doping
Authors: Zhang Jia Song , Wu Ye Fan , Luo Ling Hong , Shen Guo Yang , Su Hui
Published: June 2012

Nano-sized electrolyte of CeO2 doped 8YSZ with 2%mol CuO (YSZDC)powders were synthesized by solid state reaction method. Powder characteristics and electrical properties was characterized by XRD,SEM and Electrochemical workstation.The results demonstrate that the as-synthesized Y0.08Zr0.72Ce0.2O1.6 (YSZDC) and Y0.08Zr0.72Ce0.18Cu 0.02O1.6-δ(YSZDC-Cu0.02) possessed similar powder characteristics, including cubic ﬂuorite crystalline structure.About 150 °C reduction in densiﬁcation temperature of Y0.08Zr0.72Ce0.18Cu0.02O1.6-δ was obtained when compared with Y0.08Zr0.72Ce0.2O1.6.The YSZDC-Cu0.02 pellets sintered at 1300 °C and the YSZDC sintered at 1450 °C exhibited relative densities of 95.66% and 94.73%,respectively.Electrolyte matrixs were prepared for electrolyte-supported SOFCs(ES-SOFC) , the suspension of NiO-YSZ anode was sprayed on the electrolyte, after co-sintering at 1300°C,electrolyte matrixs and anode were well adhered each othert, without connecting pores and cracks observed. Moerover, well electricity performance were showed by YSZDC and YSZDC-Cu0.02 at a testing temperature of 750°C,And the electrolyte conductivity didn’t decrease obviously with dopping CuO.
Effects of Surfactants on the Synthesis of Silica Aerogels Prepared by Ambient Pressure Drying
Authors: Sai Hua Zheng , Xing Li , Xiang Jun Hui , Zhang Fu Shi , Cui Li Jie , Liang Xiao Hong , Song Bo , Zhao Chun Lin , Li Zhen You
Published: June 2012

In this research, aerogels were synthesized by a two-step sol-gel process without supercritical conditions. During the process, tetraethoxysilane (TEOS) was used as precursor, and different surfactants, i.e. cetyltrimethyl ammonium bromide (CTAB) and polyethylene glycol–600 (PEG–600), were used as dopants respectively. In order to minimize the drying shrinkage and preserve the high porosity structure, the surface of the gels was modified by trimethylchlorosilane (TMCS) before the ambient pressure drying (APD). The effect of surfactent on the structure of the resulting aerogels was investigated. The aerogels which involved surfactants exhibited resistance to cracking during the APD of the alcogels. The modification by TMCS has been confirmed using Infrared (IR) spectroscopy. The porous structure of aerogels was investigated by Brunauer-Emmett- Teller (BET) instrument, differential scanning calorimeter (DSC) and scanning electron micrograph (SEM). The results indicated that surfactants as dopants could significantly affect the structure and optical property of aerogels and be beneficial for obtaining crack-free silica aerogels via ambient pressure drying process.
Facile Synthesis of Hierarchically Macro/Mesoporous Carbons by Polymerization-Induced Phase Separation Combined with Starch Template
Authors: Xiao Ze Wen , Zhang Gang , Qiao Guan Jun
Published: June 2012

In this work, a facile approach combining polymerization-induced phase separation and starch-templating is presented to synthesize hierarchically macro/mesoporous carbons. The obtained porous carbons have bimodal macropores with pore diameters of 10~60 μm and 3~5 μm and 3D interconnected mesopores with pore diameters of 5~40 nm. The large macropores and the small macropores are obtained by the thermal decomposition and the closely stacking of starch particles, respectively. The 3D interconnected mesopores are developed through polymerization-induced phase separation between ethylene glycol and phenolic resin via spinodal decomposition mechanism. These as-prepared hierarchically macro/mesoporous carbons may have great potential for applications as electrodes materials for batteries, fuel cells, and supercapacitors due to their facile synthesis, unique hierarchical porous structure, and large BET surface areas (~ 610 m2/g).
The Influence of RuO2 Addition on the Thermoelectric Properties of BiSbTe Alloys
Authors: Xiao Yu Kun , Li Zhi Xiang , Jiang Jun , Yang Sheng Hui , Zhang Ting , Zhai Yong Biao , Xu Gao Jie
Published: June 2012

P-type BiSbTe/RuO2 composite was fabricated using a combined process of melting and spark plasma sintering. The XRD patterns showed that RuO2 reacted with the matrix for the RuO2 content of 1.0 wt% and 4.0 wt% samples. The measured thermoelectric properties showed that the highest electrical conductivity was obtained for the sample with 2.0 wt% RuO2. The power factor (α2σ/κ) decreased with the increase of RuO2 below 450 K. The lattice thermal conductivity was lower than that of BiSbTe over the whole temperature range for BiSbTe/2.0 wt% RuO2.
The Effect of Sintering Temperature on Microstructure and Electrocatalytic Capability of RuO2-IrO2-TiO2/Ti Anode
Authors: Qu Dong , Hu Jin , Shen Li , Zhang Wei Jun , Tang Hua
Published: June 2012

The anodes of RuO2-IrO2-TiO2/Ti were prepared by Pechini method. The surface morphology and electrocatalytic capability of anodes were studied by SEM, EDX, XRD, polarization curve, cyclic voltammetry curve and accelerated life test. It has been shown that the anodes have uniform surface composition, and the surface density of the anodes were increased as the sintering temperature increased, some active elements were crystallization grains at the surface of the anode when sintering temperature ≥500°C. The chlorine evolution capability of anode had a tendency to increase firstly then fall down afterwards as the sintering temperature increased. But the electrocatalytic capability of anodes showed an opposite tendency. The RuO2-IrO2-TiO2/Ti anode prepared at 500°C presents the longest service life.
Synthesis of Nano-Sized SrTiO3 Photocatalyst by Sol-Gel Method
Authors: Zhao Wei , Yao Jian Jun , Ya Jing , E Lei , Liu Zhi Feng , Zhou He Ping
Published: June 2012

A sol-gel processing technology was employed to synthesize fine SrTiO3 powder by using strontium nitrate (Sr(NO3)2) , butyl titanate (Ti(OC4H9)4) as precursors, citric acid (C6H8O6) as complexing agent and (ethylene) glycol (C2H6O2) as stabilizer. Prepared the precursors in liquid phase and then calcined the precursors to achieve nano-sized SrTiO3 powders. The microstructure and composition of the as-synthesized samples were characterized by X-ray diffraction (XRD), Scan Electron Microscopy (SEM), and the photocatalytic activity was studied. The results showed that all the SrTiO3 particles were identified as perovskite phase. The pH values, the content of the acetic acid, the heat treat temperature play important roles on the synthesis of the SrTiO3 photocatalyst. When the pH=1, n(Sr(NO3)2 ) : n(Ti(OC4H9)4) = 1 : 1, n(Sr(NO3)2 ) : n(C6H8O6)=1:1.7, the product has better rate of photodegradation for the Methylene Blue under the ultraviolet condition.
Preparation of Both Reactive α-Si3N4 and SiC Mixed Powder in Flame-Isolation Nitridation Shuttle Kiln
Authors: Zhu Xiao Yan , Li Yong , Wang Jia Ping , Zhai Ya Wei , Bo Jun , Zhang Jian Fang
Published: June 2012

α-Si3N4possesses excellent sintering activity, which is used to prepare high performance Si3N4-based ceramics and composite refractory. Si3N4powder is always synthesized by nitriding silicon in controlled-atmosphere furnace whose furnace volume is very small(effective volume: 1840×1420×1660mm), the extreme reaction heat is difficult to diffuse, which leads to high reaction temperature and conversion of α-Si3N4to β-Si3N4, thus α-Si3N4is difficult to be obtained in controlled-atmosphere furnace. While flame-isolation nitridation shuttle kiln has much larger furnace volume to conduct reaction heat (effective volume: 11500×4190×1684mm), so it owns homogeneous temperature field and stable low-temperature environment which benefits the preparation of α-Si3N4. Thermodynamic analysis of Si-N system is shown that Si3N4can be formed by two formats: direct nitridation of Si(s) and indirect nitridation of SiO(g); to ensure completely nitridation, the particle size of silicon powder should be less than 88μm. With reclaimed powder from polysilicon cutting slurry as starting materials, both reactive α-Si3N4and SiC mixed powder were successfully prepared in flame-isolation nitridation shuttle kiln. Because of the gas-gas reaction between SiO(g) and N2(g), α-Si3N4is fiber-like and in favor of processing high quality Si3N4-based materials.
Preparation of Nano-ZnFe2O4 Doped TiO2 Photocatalytic Films on Porous Hayddites
Authors: Xu Ke Jing , Guo Yan Qing , Liu Xi Kai , Sun Qing Wen , Dong Shu Hua
Published: June 2012

Applied nano-ZnFe2O4/TiO2 photocatlytic films are prepared by template sol-gel method on porous haydites. The effects of ZnFe2O4-doping on TiO2 crystallization, sintering temperature, light absorption and photocatalysis are mainly studied, simultaneously, effect of template, amphiphilic block copolymer P(styrene-b-acrylic acid) (PS-b-PAA) on the phtocatalytic activity of ZnFe2O4/TiO2 films are also studied. The results show that right amount of ZnFe2O4-doping reduces TiO2 sintering temperature and particle size, and increases TiO2 absorbency in ultraviolet region, and a right amount of template (PS-b-PAA) forms orient arranged ZnFe2O4/TiO2 films with the high photocatalytic activity and decomposes fully methyl orange in water after light irradiating 2h.
Preparation of Patterned BiFeO3 Thin Films on the Functional Silicon Substrates Surface
Authors: Tan Guo Qiang , Cheng Meng , Wang Yan , Cheng Lei , Xia Ao
Published: June 2012

Patterned octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) was fabricated on silicon substrates, utilizing short wave UV irradiation meter (λ=184.9nm) as the photolithograph apparatus under the cover of the photomask. The patterned BiFeO3 were prepared on the functional OTS-SAMs by sol-gel method. The characterization of the samples patterns was carried out by various techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and energy disperse spectroscopy (EDS). The results indicate that the pattern BiFeO3 thin films were successfully prepared on the functional OTS-SAMs by sol-gel method and the thin films were BiFeO3 thin films with hexagonal perovskite distorted structure which has clear boundaries and 200µm deposited lines width.
Structure and Luminescence Characteristics of Terbium Hydroxide Nanosheets Doped with Eu3+
Authors: Zhang Lin , Li Cai Xia , Jiang Dan Yu , Su Lei , Li Qiang
Published: June 2012

Eu3+ doped terbium hydroxide nanosheets were successfully synthesized from layer compound of Tb2(OH)5NO3·1.5H2O doped by Eu3+. Firstly layer compound of Tb2(OH)5NO3·1.5H2O doped by Eu3+ was obtained by hydrothermal reaction at 1200 . After ion exchange reaction with SDS under the microwave condition, the layer space of the compound increases from 0.907 nm to 2.34 nm. Furthermore stable nanosheet sol was obtained after exfoliation under ultrasonic condition. At the mean time we discovered that microwave and ultrasonic method can greatly shorten the preparation time. The structure of layer compound and the morphology of nanosheets were determined by XRD and TEM. The luminescence properties of terbium hydroxide nanosheets doped with Eu3+ were examined; the relationship between structure and spectra was discussed
Matching Ability of Dental Shaded Zirconia Ceramics and Veneering Porcelain
Authors: Dong Li Min , Wang Chen , Wen Ning , Yi Yuan Fu , Zan Qing Feng , Tian Jie Mo
Published: June 2012

The matching properties of ceramics and veneering porcelain play an important role for the overall color and mechanical properties of dental crowns. The Vita VM9 veneering porcelain was coated on the surfaces of two zirconia, three-point flexural strength, heat shock resistance and the overall color after veneered with porcelain were tested. The results showed that the interlayer cracks, radial cracks or porcelain body cracks were not appeared in all samples during thermal shock experiments at 60~220°C. Their flexural strength was all above 700MPa and the overall color covered the common color of VITA-3D Master shade guide. There is good thermal compatibility between the two dental shaded zirconia ceramics and Vita VM9 veneering porcelain. The mechanical properties are suitable for clinical posterior teeth area restorative, and the overall color is also suitable for the requirements on the color and brightness of clinical dental restoration.
Influence of Low Temperature Aging on the Flexural Strength of Y-TZP Ceramics
Authors: Wang Chen , Dong Li Min , Yi Yuan Fu , Wen Ning , Zan Qing Feng , Tian Jie Mo
Published: June 2012

Low temperature aging (LTD) is an important factor of Y-TZP ceramic as artificial joint femoral head and dental restorative materials in vivo for long-term application. In this paper, the accelerated aging experiments on Y-TZP ceramics were conducted. The t-m phase transition is occurring from the surface to the inside during low temperature aging of Y-TZP ceramics. As content of phase transformation increases, thickness of phase transformation layer increases. While the content of surface monoclinic phase is less, the volume expansion and surface stress caused by phase transformation can make cracks and holes shrink or even close, then the flexural strength increase. As a large number of surface monoclinic phase was generated, due to there are a lot of microscopic defects in the phase transition layer, crystals loose, strength of grain boundary lower than that of not aging area and phase transformation layers fracture in the intergranular mode, that damages the flexural strength. Therefore, the flexural strength increase firstly and then decrease with the increase of surface monoclinic content.
Corrosion Behavior of Mesoporous Hydroxyapatite Coated AZ31 Magnesium Alloys
Authors: Ye Xin Yu , Cai Shu , Dou Ying
Published: June 2012

Recently magnesium (Mg) alloys were widely studied as biodegradable implants for orthopedic applications duo to their suitable mechanical and biological properties. However, too fast degradation rate of Mg alloys would cause potential harm to human body. With the aim to promote the corrosion resistance of Mg alloys, mesoporous hydroxyapatite (meso-HA) coatings were synthesized on the AZ31 Mg alloys by dipped into meso-HA sol for different times (1, 3, 5 times, respectively) and subsequently heat treated. The morphologies of naked and coated samples were investigated by scanning electron microscopy (SEM). The whole surface of AZ31 Mg alloys was fully covered by a uniform coating consisted of spherical meso-HA particles sized in ~50 nm after being dipped into the meso-HA sol for 5 times. To evaluate the corrosion properties of naked and coated samples, immersion tests and electrochemistry measurement were carried out in phosphate buffer solution (PBS) at 37 °C. After the immersion of 3 days, the average corrosion rate of coated samples was calculated to be 8.7×10-3 mm/d, suggesting a greater corrosion resistance than the naked ones (8.1×10-2 mm/d). All the results indicated that it is a potential approach to improve the corrosion resistance Mg alloys with meso-HA coatings.
Preparation and Luminescence of ZnAl2O4:Mn Phosphors
Authors: Tsai Mu Tsun , Pan Bo Yu , Liang Fu Yuan
Published: June 2012

Nano-sized manganese-doped zinc aluminate spinel (Zn1−xMnxAl2O4; x = 0–6.0 mol%) powder phosphors were prepared by the sol–gel process. Zinc chloride, aluminum isopropoxide, and manganese chloride were employed as precursors. The influences of manganese concentration and heat treatment conditions on the crystallization and photoluminescence of the phosphors were investigated. The dried powders were amorphous to X-ray powder diffraction (XRD) and the single-phase ZnAl2O4 spinel crystallite started to form at temperatures as low as 600oC. The crystallization of powder did not significantly affected by various manganese concentrations. On heating at 1000oC, the resulting powder phosphors had the average crystallite and primary particle sizes of around 20–25 and 20–30 nm, respectively, depending on the dopant content and heating time. Photoluminescence spectra exhibited strong green emission bands centered at 512 nm under an excitation wavelength of 458 nm. The luminescence efficiency has been investigated as a function of dopant content, heating temperature, heating time, and specific surface area of the powders.
Preparation, Characterization and In Vitro Release Kinetics of Vancomycin Carried β-TCP/Chitosan Composite Microspheres Used as Bone Tissue Engineering Scaffolds
Authors: Zhang Lin , Cui Xue Min , Zan Qing Feng , Dong Li Min , Wang Chen , Yang Qiang
Published: June 2012

A novel microsphere scaffolds composed of chitosan and β-TCP containing vancomycin was designed and prepared. The β-TCP/chitosan composite microspheres were prepared by solid-in-water-in-oil (s/w/o) emulsion cross-linking method with or without pre-cross-linking process. The mode of vancomycin maintaining in the β-TCP/chitosan composite microspheres was detected by Fourier transform infrared spectroscopy (FTIR). The in vitro release curve of vancomycin in simulated body fluid (SBF) was estimated. The results revealed that the pre-cross-linking prepared microspheres possessed higher loading efficiency (LE) and encapsulation efficiency (EE) especially decreasing the previous burst mass of vancomycin in incipient release. These composite microspheres got excellent sphere and well surface roughness in morphology. Vancomycin was encapsulated in composite microspheres through absorption and cross-linking. While in-vitro release curves illustrated that vancomycin release depond on diffusing firstly and then on the degradation ratio later. The microspheres loading with vancomycin would be to restore bone defect, meanwhile to inhibit bacterium proliferation. These bioactive, degradable composite microspheres have potential applications in 3D tissue engineering of bone and other tissues in vitro and in vivo.
Synthesis of V2O5 Powders by EDTA Assistance Ultrasound Sol-Gel Process
Authors: Wen Quan , Huang Jian Feng , Cao Li Yun , Wu Jian Peng
Published: June 2012

V2O5 powders were successfully synthesized by the EDTA assistanced ultrasound sol-gel process using NH4VO3 and EDTA, NH3•H2O as raw materials. The synthesized activation energy and the influence of pH values and the calcination temperatures on the phases and microstructures of powders were particularly investigated. The precursor powders and the V2O5 powders were characterized by X-ray diffraction (XRD), fourier transform inelectron microscopy (FT-IR), scanning electron microscopy (SEM) and differential scanning calorimetry-thermal gravimetric (DSC-TG). Results show that the obtained products exhibit good crystallization under the conditions of pH=4, calcination temperature 400~500 °C and calcination time 0.5 h during the synthesizing process. The as-prepared V2O5 powders show preferred growth orientation along (001) plane at the pH=4. By DSC analysis, the ultrasonic cavitation result in the decrease in synthesized activation energy obviously than that was prepared without ultrasonic irradiation.
Phase Control of Nanosized NaYF4 Upconversion Particles
Authors: Guo Jing , Ma Fei Zhong , Shi Ying , Xie Jian Jun
Published: June 2012

The hexagonal phase NaYF4 (Na(Y1.5Na0.5)F6, β-NaYF4 type) is a kind of ideal host materials for upconversion luminescence with high efficiency. The synthesis of monophase hexagonal NaYF4:Yb3+/Er3+ nanoparticles has been investigated by solvothermal processing under 200° for 24hrs. It was found that solvents adopted had a great impact on formation of β-NaYF4. X-ray diffraction patterns indicated that monophase α-NaYF4 and β-NaYF4 nanosized grains could be synthesized successfully under environment of ethanol and oleic acid respectively, whereas the mixture of α-NaYF4 and Na5Y9F32 phases were obtained when water was used as solvent. The synthesized pure β-NaYF4 nanoparticles were uniformly monodispersed in hexagonal shape with typical length of 150~200nm and diameter of 50~100nm. Selected area electron diffraction observation revealed that the as-prepared nanorods are of single crystalline nature. By co-doping (20%)Yb-(2%)Er, the β-NaYF4 nanosized grains exhibited bright green upconversion luminescence centered at 538nm under the radiation of near-infrared (NIR) laser(nm). The FTIR spectrum shows theβ-NaYF4 have the potential of water-solubility for the strong bands at around 3444 and 1634 cm-1.
Preparation and Property Characterization of Talc/Phthalocyanine Blue Composite Powder
Authors: Zheng Yun Xing , Ding Hao , Mei Le Fu , Zhu Xi Yao , Wang Meng Meng
Published: June 2012

To improve the dispersion of phthalocyanine blue powder, decrease its consumption and increase the use value of talc, TPBCP (Talc / Phthalocyanine Blue Composite Powder) was prepared by liquid phase mechanochemical method. By means of paint performance test, scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FT-IR), the properties and microstructure of composite powder were characterized. The hiding power and oil absorption value of talc/phthalocyanine blue composite powder were 12.88 g/m2 and 32.50 g/100g respectively, and the International Commission on Illumination (CIE) colorimetric data L, a, and b were 44.95, 1.65 and -17.18 respectively. It was equivalent for the hiding power of composite powder to 77.6% of that of pure phthalocyanine blue with a equivalent CIE. The formation of TPBCP was marked by phthalocyanine blue particles uniformly coated on talc surface. The results showed that TPBCP had similar performances with phthalocyanine blue and could instead of phthalocyanine blue to be applied in several fields.
High-Strength Porous YSZ Ceramics Fabricated by TBA-Based Gelcasting with High Solid Loading Slurry
Authors: Zhou Jun , Wang Chan Gan , Yao Sheng Lian , Dong Yan Hao , Huang Yong
Published: June 2012

Porous yttria-stabilized zirconia (YSZ) ceramics were fabricated by tert-butyl alcohol (TBA)-based gelcasting method using high solid loading slurry. Micron pores were generated by using low-cost carbon powder as the pore-forming agent. The TBA-based slurries of 50% solid loading appropriate for gelcasting were successfully prepared by using commercial dispersant BYK-163. The rheological behavior of the slurries were measured and discussed. The porosity, microstructure, compressive strength and thermal conductivity of the porous ceramics were tested and analyzed. The results show that this low-cost technology is significant for fabricating porous ceramics with both high compressive strength and low thermal conductivity.
Making Nano-Porous SiO2 Insulation through Filter-Pressing of Foamed Slurry
Authors: Shi Xing , Ouyang Shi Xi , Chen Yu Feng , Li Mao Qiang , Zhang Shi Chao , Wu Wei , Sun Hao Ran , Wang Guang Hai
Published: June 2012

Nano-porous SiO2 insulation material was made from foamed aqueous slurry of nano-silica powder by filter-pressing. The foamed aqueous slurry mainly consists of hydrophobic SiO2 nano-particles, xonotlite whiskers and glass fiber. The latter two will enhance strength of the insulation material. Rheological properties of the foamed slurry with varying solid mass concentration were studied. The effect of forming pressure on the density and pore size distribution of the nano-porous silica material was investigated. It was found that the foamed slurry with solid concentration less than 17% behaves pseudoplastic as decreasing its apparent viscosity with increasing of shear rate during rheological testing. Homogeneous foamed slurry can be obtained when solid concentration in it is below 7%. Such slurry should be dewatered into solid concentration being of 10-15% before filter-pressing. Rigorously stirring of the concentrated slurry is required before pouring it into a mould, which leads to reducing the viscosity of the slurry and helps uniformly filling mould. During pressing the loading speed should be strictly controlled in order to reaching designed pore size distribution in SiO2 insulation material. The SiO2 insulation material with apparent density about 0.45g/cm3 and pore size mainly ranging from 10 to 50nm was obtained.
Alumina Ceramic Texturing Induced by High Magnetic Field and its Microstructure
Authors: Xu Lin Feng , Li Yun Feng , Shui An Ze , Wang Yan Min
Published: June 2012

Various textured alumina ceramics were prepared by colloidal processing in high magnetic field and heating from alumina powder as raw material in this study. The effects of the magnetic field strength, heating time and heating temperature on the particle orientation were systematically examined for these samples with scanning electron microscope (SEM) and X-ray diffraction (XRD) etc. The experimental results showed that alumina grains are polyhedral ball shape of, no textured structure exists in the sintered bodies without magnetic field treatment; the alumina grains align with the c-axis parallel the magnetic field direction under high magnetic field, the grains present strip shape in the sintered alumina bodies with the magnetic field treatment; the particle orientation degree increases with increasing the heating time and heating temperature; when the sintering temperature achieves about 1823K, the textured microstructure can be obviously observed in the sintered alumina bodies.
Influence of pH Value on the Phases, Morphologies and Optical Properties of Sm2S3 Thin Films
Authors: Hou Yan Chao , Huang Jian Feng , Cao Li Yun , Wu Jian Peng
Published: June 2012

Sm2S3 thin films were prepared on Si (100) substrates by liquid phase self–assemble method. The influences of solution pH value on the phases, surface morphologies and optical properties of the as deposited films were investigated. The as–deposited Sm2S3 thin films were characterized by X–ray diffraction (XRD), atomic force microscopy (AFM) and ultraviolet-visible (UV–Vis). Results indicate that Sm2S3 thin film with oriented growth along (105) direction can be obtained at pH value of 3.0, deposition temperature of 80 °C, following deposition for 24 h. The grain sizes of the Sm2S3 first increase and then decrease with increasing pH value. The as–deposited thin films exhibit a dense and crystallinized surface morphology. The film shows good transmittance in visible spectrum and excellent absorbency of ultraviolet light, and the bandgap of the thin films at pH of 3.0 is calculated to be 4.06 eV.
Microwave Sintered Porous Mullite Composite
Authors: Li Xu Qin , Zhang Xin , Zhang Rui , Fan Bing Bing
Published: June 2012

In order to aviod much high energy and CO2 generation. Microwave sintering (MS) is always carried out to prepare refractory. In this work，MS was proposed to sinter mullite composite. An insulation structure based on hybrid heating mode was well designed with the wall of high-aluminum refractory and the aided heaters of SiC. The sintered samples under different sintering processing were characterized by appearent porosity detection and volume density. Phase composition was investigated by X-ray Diffraction (XRD) analysis. Surface and fracture Flied Emission Scanning Electron Microscopy (FESEM) was applied to observe pore distribution and grain growth. Sintering profile was provided in this work. It was found that mullite composite could be prepared within 1h at relative lower temperature around 1300°C. Compared with samples prepared by convitional sintering (CS), MS samples presented better densification and more uniform grain growth. Microwave plasma phenomena was explored inside MS samples, however, not found in CS ones.