bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of Co2W Type Hexagonal Ferrite Used in the Load Side of Isolator
Authors: Gong Jian , Xu Guang Liang , Li Yang Xing , Peng Cheng Min
Published: June 2011

The BaCo2Fe16O27 ferrite particles have been prepared by sol-gel combustion technique. The products have been characterized by TG/SDTA, XRD, SEM and LPSA. The Microwave absorbing composite used in the load side of isolator with BaCo2-xZnxFe16O27 (x=0.0, 0.6, 1.0, 1.4, 2.0)as absorber have been prepared. The thermal degradation temperature of this kind of absorbing materials is 350 °C. When the average density is 2.62 g/cm3, the breakdown voltage is 1.4kV/mm. In the frequency range of 2 GHz-16 GHz, the absorption effects of BaZnxCo2-xFe16O27 (x=0.6, 1.4) are better than that of the single Co2-W or Zn2-W. In the frequency range of 9 GHz-16 GHz, the absorption loss of x=0.6 is better than others, which is in the range of 9.7~15.0 dB.
Resistive Switching Characteristics of Cu/SiO2/Pt Structure
Authors: Liu Chih Yi , Sung Po Wei , Lai Chun Hung , Wang Hung Yu
Published: June 2011

SiO2thin films were fabricated as resistive layers of Cu/SiO2/Pt devices to investigate resistive switching properties. A thermal annealing was performed to allow for the diffusion of Cu ions into the SiO2thin films, leading to the formation of Cu-doped SiO2layers. Occurrence probabilities of the resistive switching and initial resistance-states of the devices were influenced by SiO2thickness, which was dependent on the Cu diffusion status within the SiO2layer. The resistive switching behaviors were characterized by the voltage sweeping mode and the current sweeping mode. The current sweeping mode provided a desired compliance current to well control the resistive switching from the high resistance-state to the low resistance-state (SET). Therefore, the large RESET (from the low resistance-state to the high resistance-state) current was not inherent in the device, due to poor control of the compliance current by the voltage sweeping mode. The current sweeping mode is a simple method to characterize the RESET current.
The Band Structure and Electronic Density of States of Thermoelectric Co-Doped Magnesium Silicide
Authors: Fu Chun Lin , Liao Huan , Cai Wei , Zhang Chao Yang
Published: June 2011

Magnesium silicide (Mg2Si) has been identified a promising advanced thermoelectric material in temperature range from 300 to 700K. In order to understand thermoelectric properties of Co-doped magnesium silicide, the band structure and electronic density of states have been calculated using a first-principle pseudopotential method. It is shown that the band gap gradually decreases, at the same time degeneracy of the band and the density of states at the fermi level increase as the content of cobalt increases. It was properly predicted that the Seebeck coefficient and electrical conductivity increase, and thermal conductivity decreases as the content of cobalt increases.
The Effect CuO Additive on the Microwave Dielectric Properties of Mg(Zr0.05Ti0.95)O3 Ceramics
Authors: Tseng Ching Fang
Published: June 2011

The microwave dielectric properties of the Mg(Zr0.05Ti0.95)O3ceramics with CuO addition were investigated. All specimens were prepared by solid-state reaction method and sintered at 1270-1420°C for 4 h. When CuO was added, the second phases of MgTi2O5, TiO2and liquid phase were produced. For specimens with 1.5 wt% CuO sintered at 1300°C, the dielectric constant,Q´fand tfvalues are 18.2, 223000 GHz and -2 ppm/°C, respectively.
Unification of the Charge Transport in Field-Effect Transistors and Light-Emitting Diodes Based on Organic Semiconductors
Authors: Wang L. G. , Zhang Huai Wu , Tang Xiao Li , Song Yuan Qiang
Published: June 2011

A physically based mathematical model for the charge transport in field-effect transistors and lighting-emitting diodes based on disordered organic semiconductors has been presented. It is developed basing on the Gaussian disorder model and extends the pioneering work of Pasveer et al. [Phys. Rev. Lett. 94, 206601 (2005)] to higher carrier densities and large electric field. The experimental current voltage characteristics in devices based on semiconducting polymers are excellently reproduced with this model. Furthermore, we calculate and analyze some electrical properties for the relevant polymers in detail using this model.
Application of Sol-Gel Derived Conductive Oxide LaNiO3 in Pyroelectric Detector
Authors: Wang Jing , Zang Chuan Wei , Zhang Liang Ying , Yao Xi
Published: June 2011

Conductive LaNiO3(LNO) thin films are grown on Si(100) substrates by a sol-gel method and their application as the bottom electrode for the growth of sol-gel derived Pb(Zr,Ti)O3(PZT) thin films are studied. Morphology and electrical properties of the multilayer films are characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), electrical measurements. Experiment results show LNO thin films get highly (110)-oriented perovskite-type structure. Smooth and dense surfaces are observed on LNO thin films. The dielectric properties of PZT films show that PZT/LNO films exhibit worse dielectric properties than those of the PZT/Pt thin films. And LNO thin films prepared by sol-gel methods are not suitable as bottom electrode to deposit PZT thin films. On the other hand, FTIR spectrum and pyroelectric results of LNO thin films reveal that LNO can be used as absorber layer of PT thin films infrared detector with multi-layer thin film thermal insulation structure. At 10Hz, the detectivity (D*) and the voltage response (Rv) of PT thin films are 1.11×107cm·Hz1/2/W, 1.46×103V/W respectively.
Dielectric and Ferroelectric Properties of (Pb0.9Ba0.1) ZrO3 Ceramics
Authors: Wu Jun Bo , Tang Xin Gui , Liu Qiu Xiang , Jiang Yan Ping
Published: June 2011

(Pb1-xBax)ZrO3(PBZ) ceramics forx= 0.10 were synthesized by the mixed oxide solid state reaction method. Phase transition was investigated by dielectric measurements in the temperature range from 27 to 350 °C at various frequencies. The permittivity of the solids corresponding to (Pb1-xBax) ZrO3showed the maximum value of 10220 atx= 0.10 at the phase transition temperature. The maximum permittivity gradually increasing concentration up tox= 0.10. The ferroelectric hysteresis loop of the PBZ ceramics forx= 0.10 is displayed at room temperature and 0.2 Hz.
Effects of Forming Gas Annealing on Ba4Nb2O9 Ceramics
Authors: Meng Yuan , Chen Wan Ping
Published: June 2011

Ba4Nb2O9 ceramics were synthesized via solid state reaction and sintered in air. Annealing in 5%H2 + 95%N2 at 900°C for 2 h resulted in an increase in leakage current by several orders of magnitude, and obvious increases in low-frequency capacitance and dielectric loss, while re-oxidation in air at 900°C for 2 h led to a partial recovery. It is proposed that oxygen vacancies and Nb4+ were formed through annealing in the reducing atmosphere while inverse process occurred in the re-oxidation treatment. Re-oxidation is helpful to improve the properties of barium niobates ceramics sintered or heat-treated in reducing atmospheres and further investigations are desirable.
Integration between LiNbO3 Ferroelectric Film and AlGaN/GaN System
Authors: Hao L. Z. , Zhu Jun , Li Y. R.
Published: June 2011

LiNbO3 film (LNO)/AlGaN/GaN heterostructure was fabricated epitaxially. The preferable C+ oriented domains in LNO film lead to the formation of the spontaneous ferroelectric polarization. As a result, the sheet electron concentration of the 2DEG (ns) decreased from 1.13×1013 cm-2 to 1.04×1013 cm-2 when a LNO film deposited on the AlGaN/GaN. The ns decreased nonlinearly with decreasing the temperature. Additionally, the electron mobility for the LNO/AlGaN/GaN heterostructure decreased greatly compared with that for AlGaN/GaN heterostructure, which was caused by the non-uniform domain structure in the LNO film. By external bias switching the ferroelectric polarization, the relative enhancement of the 2DEG, about 7.68×1011/cm2, could be accessible from capacitance-voltage measurement. These results indicated that ferroelectric films combined with AlGaN/GaN would hold promise for next-generation GaN-based memory devices.
Low-Loss Z-Type Hexaferrite for Microwave Antenna Miniaturization Application
Authors: Xiang C. C. , Nie Yan , Feng Ze Kun , Gong Rong Zhou , Yuan Zhou
Published: June 2011

Magnetic and dielectric properties of conventional ceramics processed Ba3Co2Fe24O41 hexaferrite were investigated for microwave antenna miniaturization. Iron deficiency and optimizations of technology conditions have been used to control the high frequency properties of Co2Z materials. The properties of the materials were characterized by SEM, XRD, Vector Network Analyzer, and so on. The experimental results showed that Z-phase was the main phase with traces of Y-phases for all the tested samples and the resonance frequencies were above 2GHz. 3BaO·2CoO·10.4Fe2O3 samples sintered at 1050°C had a loss tanδμ of 0.07 with the permeability of 7.28 at 1GHz and the miniaturization factor n reached a value up to 10 under 2GHz. It was found that Z-type hexaferrites with iron deficiency and low sintering temperatures met the demands of low-loss tanδμ for microwave antenna applications.
Sintering and Electrical Properties of Tungsten Doped Pb(Zr0.95Ti0.05)O3 Ferroelectric Ceramics
Authors: Wang Jun Xia , Zhen Xu Lan , Yang Shi Yuan , Wang Jin , Tang Ke
Published: June 2011

The effect of WO3 additions on the sintering ability and electrical properties of Pb(Zr0.95Ti0.05)O3 ferroelectric ceramics (PZT 95/5) was investigated. Pure and W-doped PZT 95/5 ceramics were prepared by the usual ceramic technique from raw oxides. The bulk density, microstructure, electrical properties of ceramics as a function of WO3 content were characterized. The results showed that the WO3 addition was benefit for the sintering densification of PZT, and the ceramics with 2.0 mol% WO3 addition exhibited the maximum value for the density (7.8 g/cm3) at a sintering temperature of 1250 °C. Moreover, piezoelectric constant (d33), relative dielectric constant (εr), dielectric loss (tanδ) and ferroelectric hysteresis loop of PZT 95/5 ceramics at the sintering temperature of 1250 °C all altered regularly with the change of WO3 doping level, whose optimum values were all obtained by doping 2.0 mol% WO3. The best values obtained for these parameters were: d33 = 65 pC/N, εr =314, tanδ = 0.028, Pr = 24.80 µC/cm2 and Ec = 1890 V/mm, respectively. These results show that tungsten doped Pb(Zr0.95Ti0.05)O3 ferroelectric ceramics can be hopefully used for the pulsed power devices.
Structural, Magnetic, and Ferroelectric Properties in Ion-Doped BiFeO3 Ceramics
Authors: Zhang Shu Xia , Ma Yan Wei
Published: June 2011

Rare-earth ion La is doped at the bismuth site in BiFeO3 to produce Bi0.8La0.2FeO3 polycrystalline ceramics via a sol-gel auto-combustion synthesis method. For comparison, the similar experiments are also carried out for the non-doped BiFeO3 at the same time. It is found that both non-doped and La doped BiFeO3 are composed of nanoscale crystallites (~50 nm). Furthermore, La doping suppresses the formation of the secondary phase and leads to a structural phase transition from a rhombohedral to an orthorhombic or a pseudotetragonal structure. More importantly, the magnetic and ferroelectric properties in La doped ceramics were both enhanced, as evidenced by the typical electric and magnetic hysteresis loops. These property evolutions can be attributed to the elimination of the secondary phase and the structural distortion caused by La doping.
Study of Energy Harvesting Using Piezoelectric Cymbal Transducers
Authors: Li Si Zhe , Zheng Li , Li Dan , Ai Lin , Zhang Zheng , Guo Shi Shang , Zhao Xing Zhong
Published: June 2011

The performance of harvesting energy using piezoelectric cymbal transducers has been studied from gentle mechanical vibration under different pre-stress conditions. The cymbal transducer was fixed at 12.9 mm diameter and evaluated the output power of harvesting energy under an AC force of 0.7 N. The maximum power output reached 3.7mW with a slight stress level of 0.17 N across 50 kohm resistor for the cymbal transducer at the 730 Hz. The resonance frequency of the cymbal was shifted to lower value and the harvesting energy was increased with the pre-stress increased. The analytical results were found to be in good agreement with the experimental results. It is suggested that great potential for cymbal transducers exists in energy harvesting applications.
Effect of Trace Cerium on the As-Cast Microstructure of Ag-Cu-Ni Alloy
Authors: Huang Fu Xiang , Li Ming , Ying Ping , Xu Yong Hong , Zhang Ying
Published: June 2011

It is well known that the rare-earth elements (RE) have exhibited favorable microalloying effects on the microstructure and properties of silver alloys. In the present investigation, a detailed description of the microstructure of a Silver-4wt.%Copper-0.3wt.% Nickle as–cast alloy containing 0.2wt. % of a cerium element was presented. Particles types occurring and their distribution in the microstructure, as well as the distribution of elements in the phases were described. The result show that the second phase in Ag-Cu-Ni Alloy is Cu-Ni-rich solution phase, some of which forms interdendritic segregation in Ag matrix as eutectic colonies. Trace additions of cerium to the alloy decrease eutectic proportion and size of the Cu-Ni-rich phase, result in finer and more uniform secondary phases distributed in the α-Ag matrix. Besides Cu-Ni-rich phase, the Ni-Cu-Ce-rich and Ag-Cu-Ce-rich phases were found in the alloy. The Ni-Cu-Ce-rich should be the (NiCu)5Ce, which is distributed as dispersive particle in the Ag matrix, and Ag-Cu-Ce-rich phases should be (AgCu)4Ce, which is distributed as fibrous particle of eutectic colonies. Some of (AgCu)4Ce phases are located at the interface between α-Ag matrix and Cu-Ni-rich phases, which indicate that Ce could be segregated at the frontier of Cu-Ni-rich phases during the growth, causing Cu-Ni-rich phase refinement.
Defect Structure and Martensitic Transformation Crystallography in Ni2MnGa Alloy
Authors: Wei Zhao Zhao , Ma Xiao , Zhang Xin Ping
Published: June 2011

Ferromagnetic shape memory alloys can produce large strains in a magnetic field by twin boundary motion. The mobility of parent-martensite inter-phase interfaces and twin-twin inter-variant boundaries is closely related to their interfacial structures and the mechanism of migration, therefore a thorough understanding of its nature is of importance. A physical model of the structure of parent-martensite interface has been developed recently based on dislocation theories and topological arguments. On the basis of the topological model, the present work performs a theoretical study of the defect structure of the martensitic interface, and the transformation crystallography in Ni2MnGa alloy. The habit plane, i.e., the parent-martensite interface plane was determined to be (-0.761, -0.054, -0.646)Pfor the parent crystal index frame, and (-0.818, 0.067, -0.571)Mfor the martensite frame. The habit plane inclination angle is 5.945° and 5.953° with respect to the terrace plane in the parent and martensite crystals, respectively.
Effect of Fe on Phase Transformation of Low Temperature Cu-Al-Mn Memory Alloy
Authors: Zhu Kun Peng , Hu Ning , Liu Fu Shun
Published: June 2011

The influence of Fe addition on the phase transformation and the microstructure of Cu67Al27-XMn6FeXshape memory alloys are investigated by means of electrical resistivity, X-ray diffraction, scanning electron microscopy and microhardness test. It was shown that the Ms (Martensitic start transformation) temperature of the 850°C heat-treated alloy exhibit a sharp increase as Fe content increases, by comparison with the alloy without heat-treatment. For example, after 850°C heat-treatment, the Ms temperature of the alloy increases from 52K to 135K when Fe is added from 0 at.% to 1.5 at.%. The microstructure of as-homogenized Cu67Al27-XMn6FeXalloys consists of Cu3Al matrix, γ2(Cu9Al4) and α (Cu) phases. Fe element was distributed in precipitates and matrix.
High Damping Capacity of a Binary TiNi Shape Memory Alloy
Authors: Yuan Zhi Shan , Feng Zhao Wei , Miao Wei Dong , Wang Jiang Bo , Zhou Jin , Zhu Ming
Published: June 2011

TiNi shape memory alloys exhibiting high damping capacity are currently expected to be used as structural materials for energy dissipation or vibration control applications. In this paper, the characterization of damping behaviour of a binary TiNi SMA was performed by dynamic mechanical analyzer (DMA) instrument and differential scanning calorimetry (DSC) equipment. Damping tests measuring Tanδ, storage modulus E' and loss modulus E" of Ti49.2Ni50.8 binary shape memory alloy were investigated at different temperature, using different frequency and strain amplitude. It shows that quenching rate has a significant effect on the damping capacity of TiNi SMA by exhibiting different phase transformation behavior. Internal friction values (Q-1) corresponding to cubic B2 parent phase to rhombohedral R phase transformation, B2-R, and R-B19' monoclinic martensite transformation are as high as 0.177 and 0.078, respectively. The occurrence of R-phase significantly softens the storage modulus and thus promotes the damping capacity of TiNi SMAs.
Influence of Nb Addition on Phase Transformation of TiNiFe Shape Memory Alloy
Authors: Lai Hang Man , Liu Fu Shun
Published: June 2011

The influence of Nb addition on phase transformation, especially the intermediate R phase transformation and microstructure of TiNiFe shape memory alloys were investigated by means of electrical resistivity, optical microscope, energy dispersive spectroscopy and X-ray diffraction. The results showed that the R phase transformation was inhibited with the increase of Nb content. The martensite start transformation temperature decreased from 227K to 158K when the Nb content increased from 0.5 at.% to 2 at.%. The microstructure of the alloys were mainly characterized by TiNi matrix phase in which Fe and Nb resolved.
Effects of Sintering Temperature on the Barium Hexaferrite Thick Films Prepared by Screen Printing Method
Authors: Huang Zhao Lin , Peng Bin , Tan Ke , Zhang Wen Xu , Zhang Wan Li
Published: June 2011

In this paper, barium hexaferrite thick films with thickness of 80 microns were prepared on alumina substrates by screen printing method for applications in self-biased planar microwave devices. The influences of sintering temperature on the microstructures and magnetic properties of barium ferrite (BaM) thick films were investigated. The results show that with the increase of sintering temperature, the grain size increases and the porosity of the BaM thick films decreases. When the sintering temperature is below 1200 °C, the BaM thick films show magnetic properties with coercive force of about 3.5 kOe and magnetization at 20 KOe (4πM20kOe) of about 1750 Gs. When the sintering temperature is greater than 1200 °C, the magnetic properties deteriorate remarkably and exhibit a coercive force of 0.4 kOe and 4πM20kOe of about 480 Gs due to the over-sintering and diffusion of Al atoms into the BaM thick films. A new non-ferromagnetic phase Al13Ba7 is formed, which is detected by XRD.
Numerical Investigations of Thermally Induced Transformation, Reorientation of Martensite Variants and Shape Memory Effect Using Constitutive Model for Accommodation of Transformation Strain
Authors: Cho Hiroki , Suzuki Akihiko , Yamamoto Takaei , Takeda Yuji , Sakuma Toshio
Published: June 2011

To confirm the constitutive model developed by the present authors, example calculations are conducted for the transformation behavior of shape memory alloys. The constitutive model describes the transformation behavior of the material by calculating the transformation stress and strain of transformation systems of micro structures in the material. In the calculating, the accommodation mechanism acting on microstructures of the material is also taken into consideration. Computational results by the constitutive model for these loading paths are revealed to be reasonable in comparing with experimental observations.
Effects of SnO2 Doping on the Performance of ZnO Porous Thick Film Gas Sensors
Authors: Xu Hong Yan , Song Yun Tao , Cui De Liang
Published: June 2011

By using a unique hydrothermal hot-press (HHP) technique, ZnO and ZnO/SnO2composite porous nanosolids (the content of SnO2is 0, 1, 5 and 10 wt.%, respectively) were prepared. Furthermore, four kinds of gas sensors were fabricated by using ZnO (the sensor denoted as ZS0) and ZnO/SnO2composite (denoted as ZS1, ZS5 and ZS10 respectively) porous nanosolids. The intrinsic resistance and gas sensing performance of sensors ZS0, ZS1, ZS5 and ZS10 to ethanol and acetone were tested. By comparing with that of ZS0, the sensors ZS1, ZS5 and ZS10 have obviously lower intrinsic resistance and working temperature, and their selectivity to ethanol was also improved. The reason for above results has been analyzed on the basis of micro-morphology observations.
Anisotropic Hydrogel Formation: Effect of Boundary Condition
Authors: Tomita Naoko , Rokugawa Isamu , Toyama Hiromi , Yamamoto Takao , Dobashi Toshiaki
Published: June 2011

Anisotropic gelation has been studied by immersing chitosan in aqueous acetic acid sandwiched by a pair of square cover glasses into aqueous sodium hydroxide. The shape of the gel front line initially remained a square, whereas it approached a circle with immersion time. The time course of the distance between the side of the cover glasses and the gel front line xs was expressed initially as scaled proportional relationship (xs/L)2 =2K(t/L2), where t is the immersion time, L; the length of the side of the cover glasses and K; a constant. The characteristic behavior was independent of chitosan concentration.
Analysis of ZAO Thin Films by DC Reaction Magnetron Sputtereing
Authors: Lu Feng , Xu Cheng Hai , Wen Li Shi
Published: June 2011

The high quality ZAO thin films were produced by DC reaction magnetron sputtering technology. The XRD, electrical and optical properties of ZAO thin films were particularly investigated. The results show that ZAO films are polycrystalline hexagonal wurtzite structure，and Al2O3 crystal phase are not found. At the same time，the high quality ZAO films with the minimum resistivity of 4.5x×10-4Ω·㎝, the transmittance in visible region above 80% and the reflectivity in IR region above 70% are gained.
Effect of Rapid Thermal Annealing Condition on the Structure and Conductivity Properties of Polycrystalline Silicon Films on Glass
Authors: Wang Wei Yan , Huang Jin Hua , Zhang Xian Peng , Song Wei Jie , Tan Rui Qin
Published: June 2011

The effect of rapid thermal annealing (RTA) temperature (700~1200 °C) and time (1~8 min) on the structure and conductivity properties of polycrystalline silicon (Si) films on glass, grown by RTA crystallization of magnetron sputtering (MS) deposited amorphous Si (a-Si) films, was investigated by means of X-ray diffraction (XRD) and UV reflectance. It was observed the critical temperature for crystallizing a-Si films was ~750 °C and ~700 °C based on XRD and reflectance measurements, respectively. As soon as RTA temperature reached and exceeded the critical value, the structural property of polycrystalline Si films increased with RTA temperature or time. The above results were related to the thermal and photon effects induced by RTA. Moreover, it was revealed that the resistivity of polycrystalline Si films decreased with RTA temperature, however, even the resistivity of the polycrystalline Si films annealed at 1200 °C was 2 orders of magnitude higher than that of Si target, attributed to the carrier scattering by grain boundaries or defects. The polycrystalline Si films on glass fabricated by MS deposition combined with RTA crystallization may endow them with great application potentials in Si thin-film solar cells.
Fretting Wear and Microstructure of Plasma Carburized TiAl Alloy
Authors: Liu Xiao Ping , Zhang Hai Jun , Ce Pei Lin , Wang Zhen Xia , He Zhi Yong , Liu Yan Ping
Published: June 2011

A carburized layer is fabricated in the surface of TiAl alloy using plasma carburization at 975 °C. Fretting wear test at ambient temperature was carried out to evaluate wear resistance of carburized TiAl. Glow discharge spectrum, X-ray diffraction and scanning electron microscopy equipped with energy dispersive spectrometry were used to characterize the microstructure of carburized TiAl and its property capability. The experimental results show that the carburized layer with about 5 μm in thickness is mainly composed of Ti2AlC and possesses better fretting wear resistances at ambient temperature. Precipitation of carbides in surface layer leads to a higher surface hardness and compressive stress, causing a surface strengthening of TiAl. Strengthening mechanism of carburized TiAl is also considered in this investigation.
Hydrophobic Modification of PVDF
Authors: Shen Xiao Xing , Yang Wen Fang , Zhang Qing Fu
Published: June 2011

For preparation of an architecture membrane with hydrophobic properties, a method combining supercritical carbon dioxide (scCO2 ) and low temperature plasma treatment was used. The effects of treating time, pressure and temperature in scCO2 fluid on surface hydrophobic property were studied. The results showed that the contact angle of the membrane that was firstly modified by low temperature plasma and then treated in scCO2 fluid was up to 141°from 80°. In addition, the optimal hydrophobic modification conditions in scCO2 were 100°C、25MPa and 6h, and the hydrophobic property of the membrane that treated by plasma improved, the most suitable time was 300s.
Influence of Annealing and Europium-Doping on the Structure and Optical Properties of ZnO Thin Films Grown on Quartz Substrate by Magnetron Sputtering
Authors: Dai Q. Q. , Luo L. , Huang F. Y. , Xiong D. P. , Tang X.G. , Chen J.
Published: June 2011

ZnO and Eu-doped ZnO thin films were deposited on quartz substrates by reactive radio-frequency magnetron sputtering from a ZnO and Eu-doped ZnO ceramic target respectively. The properties of thin films were characterized by atom force microscope (AFM), X-ray diffraction (XRD), and photoluminescence spectra (PL). XRD reveals that the prepared thin films possess a single crystalline hexagonal wurtzite crystal structure with preferential c-axis orientation. Under above-bandgap excitation at room temperature, PL shows that ZnO films exhibit strong UV near-band-edge excitonic emission and Eu-doped ZnO thin films present UV emission and red emission from Eu3+ions, demonstrating efficient energy transfer from the host to Eu3+ions. The influence of annealing on the structure and optical properties of ZnO and Eu-doped ZnO thin films is studied. The efficient energy transfer from the host to Eu3+and high luminous efficiency indicates that the prepared Eu-doped ZnO thin films are very promising materials for lighting and flat panel display application.
Microstructure and Mechanical Properties of CrAlTiCN Multilayer Films by Magnetron Sputtering Ion Plating
Authors: Chen Di Chun , Jiang Bai Ling , Li Ming Zhi
Published: June 2011

CrAlTiCN multilayer films have been prepared by closed-field unbalanced magnetron sputtering technology using graphite target as the C supplier. TEM observation results show that the CrAlTiCN films have a clear multilayer structure with the modulate periods changed with the current of graphite target. The higher the current of graphite target, the thicker the periodical thickness of multilayer film. The microstructure of CrAlTiCN films is that the (Cr,Al,Ti)N/amorphous carbon multilayer where (Cr,Al,Ti)N layer and amorphous carbon layer appeared interval, the volume fraction of the amorphous carbon increased with the increasing current of graphite target. Measurement results showed that the CrAlTiCN multilayer films have high microhardness and low friction coefficient. Based on the relationship of the microstructure and properties of films, the multilayer structure and fine grain size of (Cr,Al,Ti)N phase are responsible for their excellent mechanical properties. The good tribological properties are attributed to the amorphous carbon phase (sp2C-C).
Postdeposition Thermal Annealing Influence on the Activation of the Cosputtered AlN-ZnO Films
Authors: Yao Shiau Lu , Hong Jhen Dong , Ho Chung Yen , Lee Ching Ting , Liu Day Shan
Published: June 2011

Cosputtered aluminum nitride-zinc oxide (AlN-ZnO) films at a theoretical atomic ratio of 10% [Al / (Al + Zn) at.%] were postannealed at 450°C for 30 min under ambient nitrogen and vacuum, respectively. The activated impurities in these annealed samples were investigated through the room-temperature (RT) and low-temperature (LT) photoluminescence (PL) spectra as well as their temperature-dependent Hall-effect measurements. It was found that the donor-acceptor-pair (DAP) emission related to VZn-AlZn transition at 2.86 eV predominated over the defect-transition luminescence in the RTPL spectrum of the vacuum-annealed sample, for which possessed a high electron carrier concentration. With the help of the temperature-dependent Hall measurement, the shallow donor level corresponded to Al on Zn site (AlZn) was derived as EC – (51±4) meV. By contrast, the RTPL spectrum of the nitrogen-annealed AlN-ZnO cosputtered film, showing p-type conduction with a hole concentration of 1018 cm-3, was dominated by the VO-NO deep level emission approximately at 1.87 eV. The estimated acceptor level corresponded to the N on O site (NO) was EV + (149±6) meV. The binding energy and activation energy associated with the NO acceptor were also determined by the LTPL and temperature-dependent PL spectra.
Preparation and Electrochemical Properties of NiO Thin Films by Sol-Gel
Authors: Zhao Shen Li , Zhu Ji Ne , Wen J.B. , Wu Zhao Yang
Published: June 2011

The NiO thin film was deposited on the stainless steel substrate by spin-coating compared with thermal treatment technique. Thermal decomposition behavior of gel precursor, the structure, morphology and electrochemical properties of NiO thin film were characterized by thermogravimetric/differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and constant current charge-discharge techniques. The results show that the stable sol is synthesized by nickel acetate and PAA. The gel precursor completely decomposes and gradually forms the nanocrystalline NiO at 450°C during the sintering. The crystal structure of NiO films become more integrity and particles large with the increasing of sintering temperature. The morphology and structure of the NiO thin film sintered at 500°C for 2h is perfect and exhibits high discharge specific capacity and well cycle performance whose initial and stable discharge capacity after 20 cycles are 1147.5mAh/g and 741mAh/g , respectively.
Preparation and Properties of Water-Based Solar-Reflective Coatings with Color Hollow Ceramic Microsphere
Authors: Wang Pei , Zhang Xia Zhen , Wei Zhi Yong , Lv Wen Yan , Liu Lian , Zhang Wan Xi
Published: June 2011

We have developed a system of solar reflective coatings that can reflect the sunlight then reduce the temperature of coated surface. The base layer material, fluorinated polystyrene-acrylate copolymers water-based emulsion was firstly prepared with hexafluoro butyl methacrylate(HFBA), styrene(St), butyl acrylate(BA), methyl methacrylate (MMA) by pre-emulsion copolymerization method. The effect on copolymerization and emulsion properties were investigated, and the polymerization condition was optimized. A hollow ceramic micro-sphere was used as the main reflective functional fillers in the system. We had a test on the practical heat-insulating properties on a prototype device. The result showed that temperature difference of the surface was reached as 6.5 °C. The new type of reflective coatings also has good stability and durability.
Structural and Optical Properties of Zn1-XCrXO Thin Films Deposited by Magnetron Sputtering
Authors: Fu Chang Feng , Han Lian Fu , Liu Chao , Chen Xi Ming
Published: June 2011

In this study, Zn1-xCrxO thin films were successfully fabricated on glass substrates by magnetron sputtering technique. The relationship between Cr doping concentration and the structural and optical characteristics of the produced samples was investigated by X-ray diffraction (XRD), optical transmittance and photoluminescence(PL). EDS results demonstrate that Cr ions are substitutionally incorporated into ZnO. XRD analysis reveals that all the prepared films with a preferential c-axis orientation exhibit the wurtzite structure of ZnO. The spectrometer transmittance data indicates that the band gap energies of the Zn1-xCrxO films are calculated by a linear fitting method. The band gap is found to be large with the increasing dopant concentration. The PL spectra suggest that all the samples have an ultraviolet emission peak centered at 370 nm. With the improved Cr-doped concentration, the peaks of ultraviolet emission have a blue shift to the region of higher photon energy, which is coincident with those values calculated by the linear fitting from the transmittance data. It is also found that the intensity of ultraviolet emission has been remarkably improved when Cr content is approximately 2.0at.%, but it is decreased when doping concentration of Cr is excessively high.
Transparency of Hybrid Films Based on (γ-Methacrylpropyl)- Trimethoxysilane and its Validation by Computing Energy-Band Structure
Authors: Wang Hai Yan , Wang Di , Zhu Peng , Hu Li Jiang
Published: June 2011

Using (γ-methacrylpropyl)-trimethoxysilane (MPMS) modified with various amounts of tetraethoxysilane (TEOS) and titanium tetrabutoxide (TTB), two kinds of hybrid films, film-MPMS-silsesquioxane (SSO)-TEOS (f-MSTE) and film-MPMS-SSO-TTB (f-MSTT), were prepared. The average transparency (AT) of the modified films, about 90-94%, was measured in the ranges of the VIS light region (400-750 nm) and in the NIR region (750-2500 nm), indicating that these high-AT films can provide crops with growth energy and improvement of the photosynthetic process efficiency. Both TEOS and TTB adequate additions resulted in a hybrid structure (containing SiO2and TiO2), and an addition can cause an increase in the AT radiation from sunlight. However, the AT of f-MSTE is higher than that of f-MSTT, which was validated using molecular dynamic simulation and calculation of the states density and the energy-band structure of MPMS-SSO, SiO2and TiO2building blocks.
A Study on Characteristics of TiH2-Al-Nb Alloyed Powder During High Energy Ball Milling
Authors: Chen Hua , Zhang Tian Yu , Lu X.Y , Jia Su Qiu , Chai Zhi Long
Published: June 2011

In this paper, TiH2-47Al-5Nb (at.%) and TiH2-47Al-7Nb(at.%) alloys were mixed and synthesized using TiH2, Al and Nb powders. The composition and morphology evolution of the mixed powder were systematically investigated during high energy ball milling. The results show obvious that structure change of the particle during milling, and amorphous, TiAl, Ti3Al and Ti2Al phases at nanoscale are formed. The addition of Nb shows an active influence on the decomposition of TiH2and formation of TiAl-intermetallics. Compare with Ti-Al system alloy, the forming process of TiAl-intermetallics for TiH2-Al-Nb system alloy is different and slower. Ti2Al metastable phase formed after ball milling for 15 h in our experiments.
Mg(OH)2 Crystals Synthesized by CHM Method
Authors: Cao Lin Hong , Zhi Shun Hua , Wang Ning Hui
Published: June 2011

Using Mg(NO3)2·6H2O as raw materials, Mg(OH)2crystals were synthesized by a composite-hydroxide-mediated(CHM) method at 160-200 °C for 24 h. Hexagonal plates Mg(OH)2crystal were formed at high content of magnesium nitrate. The size of the plates increased to 5-15 μm while the content of magnesium nitrate was 30 mmol. The strength of (001) plane became stronger than (101) plane with the high content of magnesium nitrate, and this tendency became more obvious at high magnesium nitrate concentration. It is explained that the more Mg2+ion fill the polar plane. The strength of (001) plane became stronger than (101) plane at high temperature. It can be explained Mg(OH)2crystal become more steady with more non-polar plane at high temperature, and the shape of the sample showed a change from irregular to cubic shape with heated temperature increase. It indicates that the Mg(OH)2crystal growth benefits from high temperature. It is conjectured that the connecting of the [Mg(OH)6]4+basic units with the common edges change into common vertex angle.
Nano-Montmorillonite/SBS Composite Modified Asphalt: Preparation and Aging Property
Authors: Tang Xin De , Kong Xiang Li , He Zhong Guo , Li Jun
Published: June 2011

Nano-montmorillonite (Nano-MMT)/SBS composite modified asphalts were prepared by melt blending, the aging property of which was detected by rolling thin film oven test (RTFOT) method. The microstructure of Nano-MMT/SBS modified asphalts was characterized by X-ray diffraction (XRD). The results demonstrated that nano-composite structures formed by the intercalation effect of SBS and asphalt into the MMT lamellae, which led to improvement in terms of toughness, strength, and thermal stability. In comparison with SBS modified asphalt, Nano-MMT impact on the properties of the modified asphalt appeared as a decreasing penetration, an increasing softening point, and a decreasing ductility. The anti-deformation ability under high temperature of Nano-MMT/SBS modified asphalt improved significantly. The softening point of the Nano-MMT/SBS modified asphalt decreased after aging, in contrast with that of the base asphalt, which could be attributed to the different rheological properties between the Nano-MMT/SBS modified asphalt and the base asphalt. Compared with that of SBS modified asphalt, the anti-aging property of Nano-MMT/SBS modified asphalt improved dramatically. This indicated that the lamellar structure of montomorillonite in modified asphalt could prevent oxygen from diffusing and permeating in matrix and the thermo-oxidative aging of base asphalt and SBS weakens.
Phase and Shape Evolution of CdS Nanocrystallites under Solvothermal Conditions
Authors: Xu Gang , Zhang Yan Fang , Zhao Yan Gang , Wang Qing Qing , Han Gao Rong
Published: June 2011

CdS nanocrystallites with different morphologies have solvothermally prepared with ethylenediamine (en) and glycol as solvents. Solvent-dependent experiments were carried out by adjusting the ratios of en/glycol to investigate the effects of the solvents on the product phase formation and morphology. It was found that the morphology of CdS nanocrystallite develops from a rough spherical nanoparticle to a rod-, twinrod-, and tetrapod-shaped nanoparticle by increasing the ratio of en/glycol, meanwhile the phase composition changes from coexistence of tetragonal zinc blende CdS and hexagonal wurtzite CdS to pure hexagonal wurtzite CdS. Based on the experimental results, a possible shape evolution mechanism of CdS nanocrystallites is simply discussed.
Fabrication and Characterization of Ni-TiO2 Nanocomposite Coatings and Their Corrosion Resistance Behaviors
Authors: Hao Jian Jun , Bai Yan An , Wang Chong Rui , Liu Xin Yuan
Published: June 2011

Ni-TiO2 nanocomposite coatings have been successfully fabricated via a route electrodeposition from nickel Watts bath containing nano-TiO2 particles, and characterized by scanning electron microscopy (SEM),X-ray diffraction(XRD), energy dispersive X-ray spectroscopy (EDS)and electrochemical techniques. The influence of preparation parameters on the properties of the coatings were investigated. The obtained results indicated that nano-TiO2 particles were distributed uniformly in the Ni matrix. It was found that the Ni-TiO2 nanocomposite coatings exhibited more excellent corrosion resistance and microhardness in comparison with pure nickel coating.
Preparation and Characterization of Graphene Oxide-ZnO Nanocomposites
Authors: Zou Wen Bin , Zhu Jun Wu , Wang Xin
Published: June 2011

A composite of graphene oxide supported by ZnO nanoparticles (GO-ZnO nanocomposites) was prepared through a simple chemical approach. The lamellar graphite oxide sheets in this composite were exfoliated and decorated randomly by ZnO nanoparticles with a mean size of 20 nm. In addition, the photocatalytic experiments exhibit that the GO-ZnO nanocomposites have a good photocatalytic activity on degradation of methylene blue under UV light irradiation. This method provides a facile and straightforward approach to deposit ZnO nanoparticles onto the graphene oxide sheets and may be readily extended to the preparation of other classes of hybrids based on GO sheets for technological applications.
Controlled Morphology of One-Dimensional Manganese Dioxide with Dramatic Enhancing Removal Efficiency to Heavy Metal Ions in Aqueous Solution
Authors: Ma Xing Fa , Gao Ming Jun , He Xiao Chun , Li Guang
Published: June 2011

To examine the effects of morphologies of one-dimentional metal oxides on their surface properties, two typical morphologies of manganese dioxide (one is nanorod, the other is nanofiber) as a model of metal oxide were prepared with hydrothermal approach under similar conditions. The adsorption properties of Pb2+ in aqueous solution were carried out by using surface active group of MnO2 with different morphologies. The results indicated that the sorption capacities for Pb2+ were dramaticly increased via tailoring the morphology of MnO2. The products were characterized with SEM (Scanning Electron Microscopy), XRD (X-ray Diffraction), FTIR (Fourier-Transform Infrared), atomic absorption spectrophotometer, and so on. These results illustrated that it was feasible to improve the removal efficiency of heavy metal ions dramatically in aqueous solution by tailoring the morphology of nanostructured MnO2.
Research on Properties of Ca-Co-O Thermoelectric Material with Adding Sm
Authors: Mu Jie Chen , Wei Xiu Ting , Zhang Li Peng
Published: June 2011

Ca3Co4O9 and Ca3-xSmxCo4O9 powders were prepared by sol-gel process. The Ca-Co-O thermoelectric material ceramics were prepared. The ceramics materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microstructure and thermoelectric properties of ceramics were researched. The results indicate that the crystal of Ca3-xSmxCo4O9 with Sm adding growth ideally, the material had high density and low pore rate. The Ca3-xSmxCo4O9 ceramics contain directional array plate-shaped grains with layered structure. The thermoelectric properties of Ca3-xSmxCo4O ceramics were excellent. There were high Seebeck coefficient and high electrical conductivity for Ca3-xSmxCo4O9 ceramics. The power factor increased with temperature increasing.
Synthesis and Cathodoluminescence of CdS Nanowires
Authors: Hu Xiao Dan , Zhang Hai Qian
Published: June 2011

CdS nanowires were synthesized with tetramethyl thiuram disulfide (TMTD) as a new sulphur source by a solvothermal method in ethylenediamine at 180°C for 24 h. The crystallinity, morphology and probable formation mechanism of CdS nanocrystals were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The optical properties were investigated by ultraviolet-visible spectroscopy (UV-vis) and cathodoluminescence (CL). The results indicated that CdS nanocrystals were hexagonal and had a wire-like morphology with a diameter of 20 to 50 nm. There were blue shifts at the onset of absorption of the CdS nanowire, compared with the absorption of the bulk CdS. The cathodoluminescence (CL) implied that CdS nanowires possessed potential optical property in the visible region.
A Fe-Based Amorphous Composite Coating on Al Plate by Electrothermal Explosion Spraying
Authors: Wang Yong Tian , Hu Wei Qiang , Liu Zong De
Published: June 2011

A Fe-based amorphous composite coating with different thickness on the Al thin plate is prepared by the electrothermal explosion spraying. Compared with other thermal spraying techniques, the electrothermal explosion spraying method can obtain a very high spraying velocity up to 4000m/s. The coating consists of the amorphous matrix and nanocrystal phases (α-Fe)，no laminar phenomenon is observed. The diffusion occurs between the substrate and the coating, showing a diffusion-metallurgical bond. The average hardness of coatings is 8 times larger than that of the Al substrate. The unique hierarchical microstructure at multiple length scales leads to the superior micro-hardness and wear resistance of the coating. The Fe-based composite coatings on Al thin plate have great potential as the promising lightweight wear-resistance structural materials used in the aero technical industry.
Influence of the Melting Temperature on the Fabrication of a Ti-Cu-Zr-Ni-Sn Bulk Metallic Glass
Authors: Xie Ke Fei , Yao Ke Fu , Huang Tian You
Published: June 2011

The successful fabrication of bulk glassy alloys depends on the chemical composition and fabricating process. To prepare bulk metallic glasses (BMGs) by casting with copper mould, the cooling ability of the mould and the melting temperature are considered. In this work the influence of the melting temperature on the fabrication of the BMGs is studied by varying the suction casting temperature of the Ti44.10Cu.37.04Zr9.80Ni7.06Sn2.00alloy by varying the current density employed in melting process. The results show that there is an optimum melting temperature range for fabricating the Ti-Cu-Zr-Ni-Sn BMG by suction casting. When the temperature is outside this range, the crystalline phases occur within the glassy matrix. The influence of the melting temperature on the fabrication of the Ti-Cu-Zr-Ni-Sn BMG is discussed.
Microstructural Characteristics and Mechanical Behaviors of AlCoCrFeNi High-Entropy Alloys at Ambient and Cryogenic Temperatures
Authors: Qiao Jun Wei , Ma S.G. , Huang E.W. , Chuang C.P. , Liaw P.K. , Zhang Yong
Published: June 2011

The phase-formation rule of high-entropy alloys (HEAs) with different microstructures is discussed, based on the atom-size difference in multicomponent alloys. For the single-phase HEA with the composition of AlCoCrFeNi, the yielding strengths and fracture strengths at cryogenic temperatures increase distinguishingly, compared to the corresponding mechanical properties at ambient temperature. However, the plasticity at 298 and 77 K changes very gently, while the fracture modes are intergranular and transgranular, respectively.
Rare Earth Elements on Glass-Forming Ability and Thermal Stability of Cu-Zr-Al Metallic Glass
Authors: Wang Yan Fang , Li Li , Sun Chuan , Lu Qing Long , Shi Zhi Qiang
Published: June 2011

The rare earth elements (RE= Y, Sm, La, Ce) were used as alloying materials in Cu50Zr45Al5BMG, and their influences on the glass-forming ability and thermal stability were studied in this paper. All the samples remained in full metallic glass state with minor additions of Y, Sm and La. Increasing the amount of RE additions, the Cu10Zr7and Zr2Cu phases precipitated and glass transition temperatureTgand crystallization temperatureTxsignificantly decreased. The reduced glass transition temperature Trg=Tg/Tlranged from 0.592 to 0.611 and the γ parameter ranged from 0.393 to 0.409.
The Nanocrystal and Its Thermal Stability in Ti40Zr25Ni8Cu9Be18 Metallic Glass during Homogeneous Deformation
Authors: Zhou X. , Kou H. C. , Wang J. , Li Y. , Li J.S. , Zhou L.
Published: June 2011

For Ti40Zr25Ni8Cu9Be18 metallic glass, nanocrystal forms in the as-cast amorphous matrix during fast cooling from supercooled liquid, and precipitates from amorphous matrix during heating process. The thermal stability of the nanocrystals during homogeneous temperature is influenced by deformation temperature. At relative low deformation temperature (below Tx-40K), the nanocrystal is very stable. Contrarily, nanocrystal exhibits low thermal stability at relative high deformation temperature (above Tx-40K). Moreover, nanocrystal precipitated during heating process possesses better thermal stability than nanocrystal existed in as cast condition at the same deformation temperature.