bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Oxygen Annealing on the Resistance Switching Properties of the La0.7Ca0.3MnO3 Films
Authors: Yang Rui , Li Xiao Min , Yu Wei Dong , Liu Xin Jun , Wang Q.
Published: September 2009

A series of La0.7Ca0.3MnO3 films are fabricated by pulsed laser deposition under controlling the oxygen partial pressure or adding an oxygen post-annealing process. The film after oxygen post-annealing shows an orientation change and has more non-lattice oxygen near the surface than those of the films without annealing. Moreover, only the structure of Ag/La0.7Ca0.3MnO3/Pt with the oxygen annealed film behaves a big current-voltage hysteresis and stable resistance switching properties by applying voltage pulse. Experimental results indicate that the increase of non-lattice oxygen content induced by oxygen annealing in the vicinity of the Ag/La0.7Ca0.3MnO3 interface contributes to the occurrence of resistance switching. And with the accurate controlling of the oxygen annealing parameters, the improvement of resistance switching property of the La0.7Ca0.3MnO3 film can be expected.
Synthesis and Characterization of Silver Nanowires by Solvothermal
Authors: Song Ming Xia , Feng Jin Yang , Li Wei , Hu Qi , Zhang Zhen Zhong , Liu Ben Feng , Zhao Xiu Jian
Published: September 2009

Noble metal nanoparticles have been a source of immense interest due to their novel properties and the uniqueness in properties due to high aspect ratio and quantum size effect resulting from their reduced size. In this paper, silver nanowires with an uniform diameter of 50nm were simply and successfully synthesized by solvothermal method using ethylene glycol as reducer in the presence of anodic alumina oxide (AAO) template. The experiment process is repeatable and the condition is moderate. The results of the field emission scanning electron microscope (FE-SEM) and the transmission electron microscope (TEM) show that there are more Ag nanowires with high aspect ratio produced on the surface of AAO and they are formed by many short nanowires connecting with each other from beginning to end. X-ray diffraction (XRD) and High-resolution transmission electron microscope (HRTEM) reveal that the prepared product is made of pure silver with face centered cubic structure. The optical properties were characterized by UV–Vis spectroscopy. The results reveal that Ag nanowires have a strong absorption band at about 378nm and 715nm which can be attributed to the transverse surface plasmon response(SPR) and the longitudinal surface plasmon response of the long silver nanowires.
Structure and Up-Conversion Luminescence Properties of Er3+-Yb3+Co-Doped TiO2 Nanocrystals Prepared by Sol-Gel Method
Authors: Zhang Zhen Zhong , Zhang Ji Hong , Zhou Wei , Song Ming Xia , Li Wei , Hu Qi , Zhao Xiu Jian
Published: September 2009

Er3+/Yb3+ co-doped TiO2 nanocrystals were prepared by Sol-gel method in which titanium tetrachloride was adopted as the precursor. The structure, particle size, and optical properties of samples were characterized by X-ray diffraction(XRD), Field emission-Scanning Electron Microscopy(FE-SEM) and photoluminescence(PL) spectra. Er3+ concentration was fixed at 1.0mol%, and Yb3+ concentration was changed from 3 to 10mol%. Intense upconversion luminescence was observed when the samples were excited by 980nm laser. The dependence of upconversion luminescence on Yb3+ concentration was presented. The results show that the upconversion luminescence increases with the Yb3+ concentration and gets its peak at 5%. The ratio of red emission to green emission(R/G) was strikingly enhanced with the increase of Yb3+ concentration. Under the excitation of 980nm, the green emission in the range of 520-570nm (2H11/2, 4S3/2→4I15/2) and the red emission in the range of 640~690nm (4F9/2 →4I15/2) are both due to two photons process. The possible upconversion mechanism was discussed.
Graphitic N-Free/N-Doped Nanostructured Carbon Molecular Sieves via CVD Method and their Hydrogen Storage
Authors: Zhao Chun Xia , Yang Yun Xia , Chen Wen , Zhao Dong Yuan , Wang Huan Ting , Webley Paul
Published: September 2009

Graphitic N-free and N-doped carbon molecular sieves were prepared using zeolite NaY as a template via one-step chemical vapor deposition method (CVD) with propylene and acetonitrile as N-free and N-doped carbon precursors, respectively. The morphology, structure and properties of the carbons prepared were characterized via XRD, SEM, TEM and adsorption measurements. A large proportion of pore volume is associated with micropores in the carbons prepared. A high hydrogen uptake capacity is observed.
Synthesis and Performance of Nanocrystalline 5083 Aluminum Alloy Powders by Cryomilling
Authors: Ma Xiu Hua , Wang Wei Min , Wang Hao , Wang Yu Cheng , Fu Zheng Yi
Published: September 2009

In this text, 5083 aluminum alloy was prepared with the method of the liquid nitrogen cryogenic milling (cryomilling). The microstructure,microstructural evolution and thermal stability of sample powder was investigated by XRD,SEM and DSC. The experimental results show that the particles size of 5083 aluminum alloy power during cryomilling was gradually reduced; milling time and milling speed are the main factors of affected alloy structure and performance, and high speed cryomilling could result in more uniform nanometer grains. The microstructure of the cryomilling 5083 aluminum alloy for 5 hours is micron-sized agglomerates with an average grain size of 45 nm.
(TiB2)pNi/Ni3Al/Metals Graded Materials Prepared by the Field-Activated and Pressure-Assisted Combustion Process
Authors: Meng Qing Sen , Chen Shao Ping , Wang Q.L. , Munir Z.A.
Published: September 2009

In this paper, the synthesis of four-layered functionally graded materials (FGMs) samples of (TiB2)pNi/(TiB2)p(Ni+Ni3Al)/ Ni3Al with different metallic substrate (Ni, Cu and Cr-Ni steel) by field-activated and pressure-assisted synthesis process (FAPAS) was investigated. It was shown that the imposition of the electric field and the combustion reaction of Ni3Al is the key for the successful synthesis of the FGMs during process. The exothermal reaction of the powder of nickel and aluminum during combustion enhanced the diffusion bonding in the interfaces subsequently. The microstructure, phase composition of the interfaces and mechanical properties of the graded materials were characterized, which showed indicative formation of firm bonds by the combustion reactive process. The samples have an excellent thermal shock resistance ability and gradient distribution of micro-hardness across the substrate layers and the surface layer.
A New Process for Highly Effective Utilization of Industrial Solid Wastes — Sialite Technology
Authors: Yi Zhong Lai , Sun Heng Hu , Wan Jian Hua , Li Chao
Published: September 2009

With the benefits of rapid industrialization, there are inevitable problems such as energy depletion, resource exhaustion, and severe pollution of the environment - all roadblocks to continued social development. Discovering sustainable production techniques has become a top priority. It was under these circumstances that Sialite was born. Sialite is a new kind of silica-alumina-base cementious material. This paper introduces the simulation of rock formation theory and Sialite’s high performance.
Synthesis of Carboxylic Acids Intercalated Mg-Al Layered Double Hydroxides by a Modified Reconstruction Method
Authors: Yang Wei Dong , Li Sheng , Wu Dong Yang , Spicer Mark , Gutowski Voytek , Shen Shirley Zhiqi
Published: September 2009

A series of saturated and unsaturated fatty acids (i.e. sorbic acid, octanoic acid, lauric acid, stearic acid and oleic acid) were successfully intercalated into Mg-Al layered double hydroxides (LDHs) using a modified reconstruction method, as confirmed by X-ray diffraction (XRD), Fourier transformed infrared (FTIR) and thermal gravimetric analysis (TGA). The fatty acid intercalated LDHs thus prepared exhibit much better well-defined hexagonal platelet structure than samples prepared by the conventional reconstruction method.
Preparation and Characterization of Polyaniline/PMN Composite by In Situ Polymerization Method
Authors: Wei Tao , Huang Zhi Xiong , Yang Guo Rui , Shi Min Xian
Published: September 2009

The PANI/PMN composite was prepared by one-step in-situ polymerization method and was characterized via FT-IR, XRD, SEM and TG. The results indicate that the best reaction conditions of in-situ polymerization are 0°C/24h.The PMN powder are entirely coated with PANI, when composite contains more than 60% PANI by volume. The steric hindrance effect of PMN powder decreases the crystallization degree of PANI which polymerizes on the surface of PMN powder in the process of in-situ polymerization. The main weight loss occurring between 300 and 480°C corresponds to the degradation of the PANI polymer chain.
Stoichiometric Controlling of Spark Plasma Sintered Boron-Carbon Ceramics
Authors: Zhang Song , Wang Chuan Bin , Shen Qiang , Zhang Lian Meng
Published: September 2009

A group of boron-carbon ceramic material was in-situ synthesized and densified simultaneously via Spark Plasma Sintering (SPS) technique from carbon and boron element powders with different molar ratio. The phase structures of samples with different B/C molar ratio were characterized by X-ray Diffraction (XRD). The B/C atomic ratio of the sintered materials was calculated from X-ray photoelectron spectroscopy (XPS) measurement data. Meanwhile, the chemical analysis (CA) method had also been taken to verify the B/C atomic ratio. Finally, the experience equation had been obtained to control the B/C atomic ratio of sintered samples.
Influence of Buffer Layers on the Structure and Optical Properties of Na-Doped ZnO Thin Films Prepared by Sol–Gel Method
Authors: Wang De Yi , Zhou Jian , Liu Gui Zhen
Published: September 2009

Na-doped ZnO thin films on Si (100) substrates and on pure ZnO buffer layers prepared by sol-gel method, with the pure ZnO buffer layer annealing at 1073K for 90 min. X-ray diffraction (XRD) analyses revealed that all the films had a polycrystalline wurtzite structure and high c-axis preferred orientation. Photoluminescence(PL) spectra showed that the thin films produced strong emissions near ultraviolet(UV) and weak defect-related deep-level emission in visible regions. In addition, the effects of pure ZnO buffer layers on the structural and optical properties are discussed.
Preparation of ZrC Powder by Self-Propagating High-Temperature Synthesis
Authors: Li Jing , Fu Zheng Yi , Zhang Jin Yong , Wang Hao , Wang Wei Min , Wang Yu Cheng , Cheng Yi Bing
Published: September 2009

ZrC fine powder has been prepared by self-propagating high-temperature synthesis (SHS) using exothermic reaction of ZrO2-C-Mg system. By theoretical calculating, the adiabatic temperature (Tad) for the system is about 2235K enough to react as SHS process. The Tad observed during experiment is 1850K. The results show that high pure ZrC powder is obtained with appropriate Mg contents. The scanning electron micrograph shows that the average size of ZrC particles is about 2μm.
The Effect of Surface Hydroxyl Groups on the Properties of SR/Al2O3 Composites
Authors: Xiong Yuan Lu , Shen Qiang , Chen Fei , Zheng Jin , Zhang Lian Meng
Published: September 2009

SR/Al2O3 composites were fabricated from different heat treatment temperatures of alumina. The results show that the relative density is over 94% and flexural strength is 66.5MPa when silicone content is 33wt.%. The flexural strength of the obtained SR/Al2O3 composites is decreased when increasing the heat treatment temperature of sandy alumina, indicating that the surface hydroxyl groups directly influence the flexural strength of SR/Al2O3 composites.
Reinforcement of B4C Ceramics with Multi-Walled Carbon Nanotubes
Authors: Zhang Fan , Fu Zheng Yi , Zhang Jin Yong , Wang Hao , Wang Wei Min , Wang Yu Cheng
Published: September 2009

Here we have prepared B4C/CNTs composites using the spark-plasma sintering (SPS) method. Mechanical property measurements reveal obvious enhancement confirming the fabrication of true B4C/CNTs composite materials with improved toughness properties.The addition of 1wt% CNTs in the B4C increased the fracture toughness by about 1.6 times from 2.5 to 4 MPa.m1/2 because the CNTs presented at the B4C grain boundaries, made the length of cracks shorten.
Field-Assisted Isothermal Oriented Crystallization of SrO-TiO2-SiO2 Polar Glass-Ceramics
Authors: Wang Hong Cheng , Liu Qi Ming , Cheng Jin Shu
Published: September 2009

The polar glass-ceramics of 2.0SrO-1.0TiO2-2.9SiO2 system were prepared by the process of recrystallization with additional applied isothermal and electric field. The results showed that the glass-ceramics piezoelectric constant d33 was 12×10-12 C/N. The study of its oriented crystallization by SEM and XRD indicated that Sr2TiSi2O8 crystal performed oriented growth, which was perpendicular to the glass surface and made it be orientally crystallized with the assisted the isothermal and electric field. The further experimental results showed that the additional electric field reduced the crystallization activation energy, which provided a force for the isothermal orientating crystallization process.
Synthesis of SiC Based Fibers with Continuous Pore Structure by Melt- Spinning and Controlled Curing Method
Authors: Kita Kenichiro , Narisawa Masaki , Mabuchi Hiroshi , Itoh Masayoshi , Sugimoto Masaki , Yoshikawa Masahito
Published: September 2009

Silicon carbide (SiC) based fibers with continuous pore structures were synthesized by the precursor method using a polycarbosilane (PCS) and polymethylhydrosiloxane (PMHS) polymer blends. The pore formation process can be explained by hydrogen gas dissolution in the polymer melt and desaturation process of the dissolved gas during the fiber spinning. We investigated the effect of PMHS additives with different chemical and physical natures on the obtained pore structures, because PMHS decomposition process played a role of hydrogen gas source. The individual polymer melts were characterized by viscosity measurement, gas chromatograph analysis and thermogravimetric (TG) analysis in order to obtain details of pore structure control.
Oxidation of ZrB2/ZrO2 and ZrB2/ZrO2/SiC Ceramics
Authors: Yuan Hui Ping , Song Jian Rong , Li Jun Guo , Shen Qiang , Zhang Lian Meng
Published: September 2009

The purpose of this study was to investigate the oxidation of ZrB2/ZrO2 (ZZ) and ZrB2/ZrO2/SiC (ZZS) ceramics. The ceramics were fabricated by spark plasma sintering (SPS) at 1900°C and exposed to ten-minute oxidation cycles in stagnant air at 1200°C in a box furnace with molybdenum disilicide heating elements. Results of relative density, surface phase change and the rate of weight growth show that the addition of ZrO2 improved the sintering properties of ZrB2 ceramics. While the resistance to oxidation declined with the increase content of ZrO2. And the addition of SiC improved the resistance to oxidation of ZrB2/ZrO2 composites significantly.
Synthesis, Characterization and Electromagnetic Wave Absorption Properties of Z-Type Hexaferrites Prepared by Molten Salt Method
Authors: Li Hai Feng , Gong Rong Zhou , Fan Li Ren , He Gang , Shen Xiang
Published: September 2009

The Co2Z hexaferrites powders, Ba3Co2Fe24O41, were synthesized by the molten salt method. The results indicated that the ferrite powders possess hexagonal shape and are well separated from one another. The composite with 40vol% Co2Z content has shown a minimum reflection loss of -24dB at 9.5GHz with a -20dB bandwidth over the extended frequency range from 8.3 to 10.2GHz in a quite thin sample with a thickness of 3.0mm. The molten salt method could be a potential way to enhance the properties of the composites filled with hexagonal ferrite powders for electromagnetic applications.
Effects of Coated Nano-BN Particles on Microstructure and Properties of BN-AlN Composite
Authors: Li Mei Juan , Shen Qiang , Chen Fei , Zhang Lian Meng , Yao L.F.
Published: September 2009

Surface coating has been used to prepare nano-particle BN-AlN composite powder. Nano-BN was synthesized via in-situ reaction, coating on the surface of AlN particles. The effects of coated nano-BN on the microstructure and properties of BN-AlN composites have been investigated. Results indicate that the microstructure and properties of BN-AlN composites are very different from the origin composite powders. Nano-BN particles cause the homogeneous microstructure and reinforce the grain boundary of BN-AlN composites. They exhibit similar regularity of reinforce effect of ceramic nano-particle and enhances remarkably the composites’ mechanical strength. But nano-BN will introduce more grain interfaces, more oxygen-related defects in grain lattice to increase phonon scattering and reduce the thermal conductivity of BN-AlN composites.
Fabrication of Indium Tin Oxide Targets by Spark Plasma Sintering and Hot-Pressing Sintering
Authors: Guo Wei , Wang Wei Min , Wang Hao , Wang Yu Cheng , Fu Zheng Yi
Published: September 2009

The Indium Tin Oxide(ITO) is known as a poorly sinterable material. The Spark Plasma Sintering(SPS) and the hot-pressing sintering(HP) were used to fabricate Indium Tin Oxide Ceramics from ITO nanoparticles. The maximum bulk density of 7.02 g/cm2(relative density; 98.2% TD)was obtained when sintered in Ar at 1000oC for 1min by SPS sintering. While the bulk density of 7.08 g/cm2(relative density; 99% TD) was obtained when sintered in Ar at 1050 oC for 4h by HP sintering.
Heavy Ion Tracks Route to Nanotechnology
Authors: Virk Hardev Singh
Published: September 2009

Heavy ion tracks recorded in dielectric materials were found to have a width of 5-10 nm using SEM. Heavy ion beams were used for irradiation of Polymers and Muscovite mica to create Ion Track Filters (ITFs) using UNILAC facility at Darmstadt, Germany. The electrochemically etched pores of ITFs used would act as a template. The simple principle of electroplating is used to create heterostructures. The rate of deposition of metallic film depends upon current density, inter-electrode distance, cell voltage, electrolyte concentration and temperature etc. The use of ITFs looks quite promising in the fabrication of micro and nanostructures. The morphology of such structures produced through electrochemical methods and replicas of etched tracks in ITFs have been investigated in detail. The efficacy of the technique was tested for growth of quantum dots, fibers, cones, whiskers, micro and nano wires. A 3-dimensional ensemble of Cu-Se was grown electrochemically using ITF of Makrofol-KG. Replication of etched pores in ITFs has been used to develop microtubules. Presently, we are engaged to develop quantum dots, nanorods and nanowires of copper, iron and bismuth using Anodic Alumina Membranes (AAM), Polycarbonate ITFs and Reverse Micelle technique. The preliminary results of our investigations will be presented at NADPA-2008.
Study on Carbon Nano-Tube Spun Thread as Piezoresistive Sensor Element
Authors: Mallik Nilanjan , Schulz Mark J. , Shanov Vesselin N. , Hurd Douglas , Chakraborty Supriya , Jayasinghe Chaminda , Abot Jandro , Song Albert
Published: September 2009

Carbon nanotube spun threads are becoming growingly important for various technological and medical applications. Threads can be spun directly from carbon nanotube arrays using age old method of spinning. The process involves two rotations about two mutually perpendicular axes viz. spinning nanotubes into thread from array and winding the spun thread on spool. It is found that an array with properties of high uniform density, low amorphous carbon content and highly aligned nano-tubes are better spinnable. Piezoresistive property of spun thread is investigated through experiments. The change in resistivity of spun carbon nanotube thread with change in load will enable its use as force sensors. In a structural neural network system a network of sensors can pinpoint the location of damage in structure. If such network can be made of very small dimension it can detect crack initiation and crack propagation. Linearity of resistivity increase with increase in strain is observed for fine spun carbon nanotube threads. Upon unloading also this linearity is preserved with same slope.
Preparation and Characterization of Biodegradable and Compatible Ethylene Vinyl Acetate (EVA)/Thermoplastic Starch (TPS) Blend Nanocomposites
Authors: Patel Vivek
Published: September 2009

Ethylene vinyl acetate (EVA)/thermoplastic starch (TPS) clay nanocomposites were prepared through melt intercalation technique using Haake Rheocord 9000 batch mixer with two different organically modified clays (Cloisite 30B & Cloisite 20A) at different weight percentages (1-7 wt %).The EVA/TPS ratio of 70: 30 was taken as optimum blend ratio as evidenced from the mechanical strength and chosen for the nanocomposites preparation in the presence of MA-g-PE as a compatibilizer. The maize starch was plasticized and gelatinized by adding glycerol and water in the ratio of 70:20:10.The blend nanocomposites have been examined by various techniques for characterization. Differential scanning calorimeter (DSC) result shows that the crystallization temperature of the nanocomposite blends is significantly lower than the base blend. Addition of 30 wt % of modified starch to make EVA/TPS blend; there is deterioration of impact strength, tensile strength, tensile modulus and elongation at break which was significantly increased after incorporation of small quantity (1-7 wt %) of nanoclay. Thermo gravimetric analysis (TGA) showed that the thermal stability of blend nanocomposites were better than those of EVA/TPS blend.
Synthesis and Characterization of Carbon Nanotubes by Using Catalyst LiNi0.5Co0.5O2 on Anodized Alumina Substrate
Authors: Rana Kuldeep , Sil Anjan , Ray Subrata
Published: September 2009

Carbon nanotubes (CNTs) have been synthesized by chemical decomposition of acetylene gas at 580°C and 650°C using catalyst of LiNi0.5Co0.5O2. The effect of decomposition temperature on structure of the CNTs is that, CNTs grown at 650°C have lower defects concentration and higher crystallinity as compared to that grown at 580°C. The porous anodized aluminum oxide (AAO) template (as substrate), catalyst particles and the CNTs grown were analyzed by FE-SEM. The pore diameter in the template lies in range of 30 - 80 nm. The CNTs have been analyzed by using Raman spectroscopy and X-ray diffraction techniques. The up-shift in G-band of graphitic sheet and larger full width at half maximum of the peak in the Raman spectra of the CNT in comparison to those observed for graphite are indicative of the structural modification. XRD results also indicate the structural modification in CNT based on the fact that d-value becomes 3.42 Å, which is larger than 3.35 Å for graphite. The tube diameters lie in the range of 12 - 50 nm.
Thermal and Mechanical Characterization of PMMA TiO2 Nanocomposites
Authors: Patra Niranjan , Barone Alberto C. , Salerno Marco , Caputo Gianvito , Cozzoli Davide , Athanassiou Athanassia
Published: September 2009

Hybrid composite films made of an organic polymeric matrix and an inorganic nanosized filler, namely titania prolate nanoparticles, have been prepared and characterized both thermally and mechanically. The filler content has been varied, while still being kept in the regime of unsaturated, homogeneous nanocomposites. On increasing, the filler content there is an abrupt increase in hardness at an intermediate load, while the elastic modulus increases almost linearly. The glass transition temperature is also increased, with a tendency to saturation. The morphological characterization of the films confirms a lack of phase separation, with only a continuous, slight increase in surface roughness, and no major effects on the top film features.
Synthesis of Iron Oxide Nanoparticles by Thermal Decomposition Approach
Authors: Dixit Shuchi , Jeevanandam P.
Published: September 2009

An easy onepot reaction for the synthesis of iron oxide nanoparticles is reported. Thermal decomposition of iron acetyl acetonate (Fe(acac)3) in diphenyl ether, in the presence of oleic acid and oleyl amine followed by calcination, leads to the formation of iron oxide nanoparticles. Variation of concentration of the oleyl amine during the synthesis affects the morphology of the iron oxide nanoparticles produced.
Synthesis and Characterization of LiMn2O4 Nanoparticles Using Citric Acid as Chelating Agent
Authors: Singh Gurpreet , Panwar Amrish , Sil Anjan , Ghosh Sudipto
Published: September 2009

Nanocrystalline LiMn2O4 powder was synthesized by sol-gel method using citric acid as a chelating agent. The powders were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Differential scanning calorimetry (DSC), Differential thermal analysis (DTA), Impedance spectroscopy (IS) and Electrochemical measurements. The powder particles having slight agglomeration characteristics were found to have prismatic morphology and a wider size distribution from 50 nm to 200 nm, which provides good packing density of the material. The electrical conductivity of the powder at room temperature is in the order of ~10-5 S/cm. The structural stability of LiMn2O4 cubic spinel over the temperature range of battery operation was assessed. Electrochemical performance of the material shows a discharge capacity of ~130 mAh/gm.
Preparation and Characterization of Li [Mn2-xFex]O4 (x = 0.0-0.6) Spinel Nanoparticles as Cathode Materials for Lithium Ion Battery
Authors: Singh Priti , Sil Anjan , Nath Mala , Ray Subrata
Published: September 2009

Nanosized powders in the system LiMn2−xFexO4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) have been synthesized by sol-gel technique using citric acid as chelating agent. The effect of Fe substitution on the structure and surface morphology of spinel LiMn2O4 has been examined by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and Electrochemical characteristics. The materials for all the compositions except x = 0.6 exhibit a phase pure cubic spinel structure as evident from the XRD analyses. Doping with Fe increases the crystallinity in the materials and decreases the average particle size. The surface morphology of the synthesized particles is spherical and polygonal type. Average particle size lies in the range of 60 to 400 nm. Improved capacity retention in rechargeable 4 V Li/LiMn2-xFexO4 cells has been observed when a small amount of manganese in the spinel cathode is replaced with iron. The first discharge capacities of LiMn2−xFexO4 (x = 0.0, 0.1, 0.2, 0.3) in a voltage range of 3 V to 4.3 V decreases as the x increases, however, the cyclic performance improves.
Influence of Iron Dopant on Structure, Surface Morphology and Optical Properties of ZnO Nanoparticles
Authors: Elizabeth Esther , Yogamalar Rajeswari , Ramasamy Srinivasan , Bose Arumugam Chandra
Published: September 2009

Pure and two different concentration of Iron (Fe) doped Zinc Oxide (ZnO) nanoparticles (Zn(1-x)FexO) with x = 0.03 and 0.05 were synthesized by chemical co-precipitation method. The structural characterizations of the samples were done by X-ray powder Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD data indicate that the replacement of Zn2+ ion by Fe3+ ion does not influence the wurtzite structure of ZnO samples. With increase in annealing temperature the intensity of the Zn(1-x)FexO (0 0 2) diffraction peak increases, indicating that the crystallinity quality of the particle improves. Using Scherrer equation the average particle sizes of Zn(1-x)FexO are calculated. The strain-induced broadening at Full Width Half Maximum (FWHM) of the XRD profile of Zn(1-x)FexO were estimated from Williamson Hall (W-H) plot. The results of SEM apparently show that the sample comprises of highly agglomerated particles with no definite shape. Optical absorption Ultraviolet-visible (UV-vis) and Photo Luminescence (PL) properties have been characterized and the effect of Fe addition on optical properties of ZnO has been discussed.
Controlled Synthesis of Lead Telluride Nanocrystals
Authors: Paul Biplab , Banerji P.
Published: September 2009

Nanocrystalline PbTe particles of controlled size and shape are synthesized via chemical route at different growth temperatures. The size of the nanoparticles is in the range ~ 20 to 35 nm. The size and shape of the particles have been controlled by controlling temperature, using proper surfactant and maintaining the atomic ratio between Pb and Te. The intrinsic properties of surface energy of different crystallographic planes involve in growth process are studied. The crystallinity and phase of PbTe nanocrystals are analyzed by X-ray diffraction (XRD). The shape and size of the nanocrystals have been characterized by transmission electron microscopy (TEM). The optical band gap of nanocrystals is determined by FTIR photo-absorption spectra.
Controlled Synthesis of ZnO Nanoflowers and Nanorods by Sonochemical Method
Authors: Singh Prashant Kumar , Mittal Ankit , Agarwala Vijaya
Published: September 2009

ZnO nanostructures of different morphologies were grown in a controlled manner by a novel sonication assisted sol gel process. Variation in the alcoholic medium resulted in nanorods and flower like ZnO nanostructures. Flower like ZnO nanostructures with a root size of 1m and a tip of 150nm were synthesized using ethanol as solvent, while ZnO nanorods with diameter less than 60 nm and length greater than 1m were synthesized using methanol as solvent. The samples were characterized by X-ray diffraction and Scanning Electron Microscopy. The XRD results show the formation of highly crystalline ZnO with no detectable level of impurity. In this paper, a possible mechanism for the variation of morphology with the change in solvent has been discussed. The effect of solvent vapour pressure on the sonication process has been explained. The solvent vapour pressure has an effect on the intensity of sonication which affects various chemical reactions taking place during the formation of ZnO. The effect of ethylenediamine on the chemical reactions leading to formation of ZnO nanostructures has also been analyzed.
Preparation and Characterization of Organoclay Reinforced Polylactic Acid Biocomposite Films
Authors: Das Kunal , Ray Dipa , Bandyopadhyay N.R. , Sengupta Suparna , Sengupta S.P. , Mohanty Amar K. , Misra Manjusri
Published: September 2009

Polylactic acid (PLA) based biocomposite films, reinforced with different loadings of organoclay, were prepared by solution casting method. Four different loadings of clay was done, 2, 5, 10 and 15 weight% with respect to the matrix. These biocomposite films were characterized by mechanical characterization, scanning electron microscopy (SEM) moisture diffusivity property at 93% RH. Both the mechanical and the visco-elastic property of these films were measured by nano indentation technique. Mechanical property by nano indentation analysis revealed an idea about the extent of clay dispersion in the matrix. The amount of clay loading and its dispersion significantly affected the mechanical as well as the Visco-elastic behavior of the biocomposite films. The morphology of the films were observed with the help of SEM.
A Comparative Study on Process-Properties Correlation of Nano Radar Absorbing Heat Treated Materials
Authors: Sharma Rahul , Agarwala Ramesh Chandra , Agarwala Vijaya
Published: September 2009

Single phase M-type barium hexaferrite nano radar absorbing material (NRAM) i.e., BaFe12O19 were synthesized by modified flux method that combines the controlled chemical co-precipitation process for nucleation and complete uniform growth during annealing with NaCl flux under microwave annealing (MWA) and vacuum annealing (VA). Uniform morphological transformation of nano crystals from spherical (~ 10 nm) to prism faces (~ 35 nm) were observed under TEM during annealing. The effect of such systematic nano morphological transformation of NRAM was observed on magnetic and reflection loss (RL) properties. Maximum reflection loss (RL) was improved to 37.15 dB at 16.00 GHz for MWA at 760 watt and 27.56 dB at 15.75 GHz for VA at 1200 oC with continuous increasing absorption range under −10 dB for 2 mm thick coating layer in the Ku Band (12.4-18.0 GHz).. Excellent microwave absorption properties are a consequence of accurate EM match in the nano morphological planes, a strong natural resonance, as well as multipolarization. This process of crystal growth, morphology evolution and RL enhancement with respect to the heat treatments were also explained in terms of Ostwald ripening and quantum size effect.
Study on Generation of Fine Grained Titanium Aluminide Through Ball Milling of Ti, Al and Ni-P Coated Graphite Powder
Authors: Gupta Rohit Kumar , Agarwala Vijaya , Thakur Sunayan , Agarwala Ramesh Chandra , Pant Bhanu
Published: September 2009

High energy ball milling (HEBM) had been carried out to produce submicron size titanium aluminide intermetallics (TiAl) using elemental powders of Ti and Al alongwith Ni-P coated graphite. 1% graphite powders was added to stoichiometric composition of Ti48Al and ball milling was conducted for different milling time at varying rpm. The effect of milling time and rpm on particle size has been studied. The prepared samples have been characterized using X-ray diffraction, differential scanning calorimetry (DSC) and scaning elecron microscopy (SEM). Grain size as low as 500 nm could be achieved. Formation of Ti3Al, TiAl and carbon containing intermetallic compounds had been confirmed through X-ray diffraction. Milling time and rpm of mill is found to be important factors which control the final particle size.
Development of Electroless Ni-P/NRAM Nanocomposite Powder with Enhanced Microwave Absorption Properties
Authors: Sharma Rahul , Agarwala Ramesh Chandra , Agarwala Vijaya
Published: September 2009

Nano radar absorbing material (NRAM) i.e. BaMe2Fe16O27 (Me2+=Fe2+) powder (10 nm) is coated with amorphous Ni-P nano layer (5-10 nm) by using electroless (EL) technology to develop EL Ni-P/NRAM nanocomposite powder. The experimental processes parameters and EL Ni-P bath composition were optimized to obtain the deposition. As-deposited nanocomposite powder was microwave annealed (MWA) with increasing radiation power from 160 to 760 watts for 5 minutes. The surface morphology, elemental contents, phase transformation and magnetic properties of NRAM powders were examined under field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) respectively. Maximum reflection loss (RL) 33.75 dB at 15.80 GHz for nanocomposite powder MWA at 760 watt was obtained the absorption range under −15 dB is from 13.76 to 16.77 GHz with 2 mm thickness layer in Ku Band. Excellent microwave absorption properties due to accurate electromagnetic (EM) match in the nanocomposite microstructure, a strong natural resonance and multipolarization. Such (Ni+ Ni3P)/NRAM nanocomposite powders may be attractive candidates for EM absorption.
Aqueous Synthesis towards Vertically-Aligned and Selective Pattern of ZnO Nanostructures Arrays
Authors: Ho Ghim Wei , Wong Andrew See Weng
Published: September 2009

For any future cost-effective applications of inorganic nanostructures in particular hybrid photovoltaic cell, solution processable and selective printable of inorganic nanomaterials is essential. The patterning and growth of highly ordered arrays of crystalline ZnO inorganic nanostructures use simple soft lithography technique and mild reaction conditions; both low in temperature and free from harmful organic additives. Variable yet controllable anisotropic growth of ZnO nanowires has been demonstrated on the transferred patterns of ZnO nanocystals.
Structural and Ferroelectric Properties of NaNO2: PVF Composite Film
Authors: Sekhar K.C. , Nautiyal Arvind , Nath R.
Published: September 2009

The structural and ferroelectric properties of NaNO2: PVF composite film prepared by hot press method have been studied and analyzed. The x-ray diffraction study revealed that the strain is reduced in the composite film. The image of field emission scanning electron microscope shows uniform distribution of NaNO2 grains of 150 nm size in the composite film. The differential scanning calorimetric curve supports the presence of ferroelectric phase. The polarization reversal characteristics were studied with the bipolar square pulse. The application of Ishibashi and Shur’s theory to the experimental switching transients supports needle like domain growth (1D) during switching process. The remanent polarization obtained from the polarization reversal is in agreement with the hysteresis loop value. The composite film shows faster switching time compared to pure NaNO2 film and may be attributed to the reduced strain.
Enhanced Photoelectrochemical Activity of 120 MeV Ag9+ Irradiated Nanostructured Thin Films of ZnO for Solar-Hydrogen Generation via Splitting of Water
Authors: Gupta Monika , Shrivastava Jaya , Sharma Vidhika , Solanki Anjana , Singh Ananad Pal , Satsangi V.R. , Dass S. , Shrivastav Rohit
Published: September 2009

This paper deals with a study on 120 MeV Ag9+ irradiated thin films of zinc oxide (ZnO), obtained by sol-gel – spin coating onto TCO glass plates. Films irradiated at fluence 5×1011, 3×1012, 5×1012 and 2×1013 ions cm-2, were optically characterized for band gap determination. XRD analysis revealed polytypism as both wurtzite and zincblend phases co-evolved. Scherrer’s calculations indicated grain size in nanodimensions, while SEM analysis indicated smooth surface morphology of films. Flat band potentials and donor densities were evaluated by Mott-schottky calculations. For PEC studies, thin films of ZnO were employed as working electrode in conjunction with Platinum Counter electrode, Saturated Calomel Reference electrode, 13 pH aqueous solution of NaOH as electrolyte and 150W Xenon Arc light source for illumination. A significant gain in photoelectrochemical current was recorded on SHI irradiation. The films irradiated at fluence 3×1012 ions cm-2 yielded maximum increase in photocurrent that was nearly five times compared to unirradiated samples.
Internal Deterioration of Mortars in Freeze-Thawing: Non-Destructive Evaluation by Means of Electrical Impedance
Authors: Menéndez Esperanza , de Frutos José , Andrade Carmen
Published: September 2009

In this work, different mortars with different degrees of damage brought about by the action of the freeze-thawing cycles are evaluated. Analysis of its state is carried out by different usual evaluation methods. Results obtained through these methods are compared with the electrical impedance spectroscopy. Moreover, this non-destructive technique is employed to evaluate the state of mortars and the amount of internal damage.
Structural Transformations of Boron Nitride Powders Obtained by Mechanical Milling Process
Authors: Esparza Rodrigo A. , Ayala J. , Ángeles-Chávez C. , Rosas Trejo Gerardo Antonio , Pérez Ramiro
Published: September 2009

Mechanical milled powders of boron nitride were obtained. The microstructural characterization of these milled powders was carried out using X-ray diffraction technique. Insights on the nature of the crystalline phases obtained in these milled powders were obtained between comparisons of theoretical and experimental X-ray diffraction patterns. Observations on the phase transformations have been carried out using calorimetry and thermogravity experiments. Morphological and microstructural characteristics of nanocrystals are obtained using SEM and HRTEM instruments.
Friction Stir Linear Welding of an Aluminum Alloy
Authors: Wong Jerry , del C. Zambrano Patricia , Escamilla Indira , Gonzalez Bernardo , Mucino Victor , Colás Rafael
Published: September 2009

The joining process by friction linear stir welding of aluminum strips was implemented in a machining center. The trials were conducted on 1 mm thick strips from a 6061T6 aluminum alloys that were welded together by the action of the rotating tool; the parameters that were varied in these tests were the rotating and advancing speeds. The specimens were sectioned to evaluate the joint strength. Metallographic analyses and Vickers micro hardness indentations were carried out.
A New Measuring System for Determining the Magnetic Viscosity in Permanent Magnets
Authors: Espina-Hernández J.H. , Grössinger Roland , Sato Turtelli Reiko , Hallen J.M.
Published: September 2009

A new system for measuring magnetic viscosity in bulk hard magnetic materials base on a pulsed field method is presented. After the magnetizing field pulse, the stray field of the sample, which is proportional to the magnetic moment, is measured with a compensated set of two Hall probes. The set of Hall probes is driven with an AC voltage source and the Hall voltage is detected using a lock-in amplifier. By this method the system is able to measure the time dependence of the magnetization (viscosity). The magnetic viscosity coefficient (S) is obtained through a linear fitting of the magnetization decay versus ln t. Two typical Nd-Fe-B samples were measured and good agreement with the results from the traditional viscosity experiment was obtained.
Joining of WC-Co to Ni by Direct Diffusion Bonding
Authors: Lemus-Ruiz José , Salas-Villaseñor Ana L. , Flores Osvaldo
Published: September 2009

Solid-state direct diffusion bonding between commercially pure nickel and tungsten carbide (with 6%Cobalt) has been carried out in the temperature of 980°C and 1100°C using different holding times in argon atmosphere. Samples were successfully joined without defects or cracks on the joining interface with the exception of the one joined at 980°C for 5 min. The results showed that joining occurred by the formation of a reaction zone. Scanning electron micrographs show that different intermediate layers are formed in the reaction zone, and the width of these layers increases with an increase in bonding temperature and time. Electron probe microanalysis revealed that at any particular bonding temperature, cobalt travel into the nickel side, whereas nickel travel comparatively larger distances in the tungsten carbide side.
Magnetic and Electronic Properties of the Compound Y(Co,Fe)5 Calculated by the Augmented Spherical Wave Method
Authors: Grijalva Castillo María Cristina , Matutes-Aquino José Andrés
Published: September 2009

Energy band structure and density of states of the compound Y(Co,Fe)5 were obtained by the augmented spherical wave method. Also the localization of the magnetic moment inside the unit cell, the effect of pressure and the substitution of Co atoms by Fe atoms were studied at the temperature of 0 K. Metallic Co showed a magnetic moment of 1.5 B while metallic Y showed its non magnetic behavior. Inside the compound YCo5 the Y atom had a contribution of –0.3 B to the total magnetization of the unit cell. A negative pressure caused the change of the Fermi energy and the modification of the magnetic moment. With a big enough positive pressure the total magnetic moment dropped to zero. The substitution of Co by Fe caused a change in the compound from strong ferromagnetic to soft ferromagnetic.
Comparative Study of Corrosion in Physiological Serum of Ceramic Coatings Applied on 316L Stainless Steel Substrate
Authors: Espitia-Cabrera M.I. , Orozco-Hernández H.D. , Espinosa-Medina M.A. , Martínez L. , Contreras-García M.E.
Published: September 2009

In recent years the use of ceramic coatings to reduce metallic corrosion has been greatly improved. It has been proved by several studies that coating of TiO2, ZrO2, SiO2, and other oxides or mixed oxides provide efficient protection against the corrosion of stainless steel in different media. In this work, alumina and zirconia films were obtained by electrophoretic deposition to investigate their use as protective coatings of 316L-Stainless steel for prostheses and dental implants. These were characterized by scanning electron microscopy (SEM), grazing incidence X-ray diffraction (GID), and atomic force microscopy (AFM). The corrosion behaviour in Hank’s solution at room temperature was studied using a potentiodynamic polarization technique. The electrochemical measurements showed a high corrosion resistance of 316L-SS coated by both types of ceramic film. The best behaviour was presented by the alumina coating. The morphologies of the corroded films showed that the alumina and zirconia films presented low damage with little pitting corrosion compared with the uncoated 316L-SS.
Characterization of Galvannealed HSLA Steels
Authors: de la Garza Maribel , Moreno Mayra , Guerrero-Mata Martha Patrizia , del C. Zambrano Patricia , Colás Rafael , Houbaert Yvan
Published: September 2009

Galvannealed coatings are obtained by heat treating galvanized steel strips and are widely used in the automotive industry due to their improved properties. The variables influencing coating formation on high strength low alloy steel (HSLA) were analyzed. The study was carried out on samples obtained from an industrial plant and on samples coated in a hot dip process simulator. The mechanical properties of the steel substrate were evaluated, and the morphology and Fe content in the various phases of the coating and its characteristics were analyzed and compared. It was found that the Fe-Zn phases can be controlled and performed varying the temperature and holding time during the annealing cycles, avoiding the formation of undesirable phases.
Characterization of Magnetic Particles Using a Wavelet Function
Authors: Ochoa Domínguez Humberto J. , Garcia Casillas Perla E. , Martínez Pérez Carlos A. , Elizalde Galindo José Trinidad , Camacho Montes Hector , Vergara Villegas Osslan O. , Gutiérrez Casas Efren , Ortega Maynez Leticia
Published: September 2009

The second derivative of the remission function of several magnetic materials is calculated for the parameterization of the position and intensity of the absorption bands of diffuse reflectance spectroscopy. The reflectance spectra are obtained by ultraviolet-visible spectroscopy (UV-VIS) from 400 to 1100 nm at increments of 1nm. The noise of the remission function results on errors after calculating the second derivative. Therefore, filtering of the remission function is needed before taking any action on this signal. Several methods are tested in order to calculate the second derivative. The best polynomial resulted on a second order wavelet function which is applied to the filtered remission function. Light scattering Mie theory is used to prove the behaviour of the reflected light. This research provides a method to identify and quantify magnetic particles, as well as the crystal size.
Microstructure Formation of Al-Fe-Mn-Si Aluminides by Pressure-Assisted Reactive Sintering of Elemental Powder Mixtures
Authors: Flores Alfredo , Toscano J.A. , Rodríguez S. , Salinas R. A. , Nava-Vázquez Enrique
Published: September 2009

This paper presents the results of an investigation aimed at understanding microstructure formation of Al-Fe-Mn-Si intermetallics during pressure-assisted reactive sintering of elemental powders. The proportion of elements was selected such that the composition of the product was 55 wt % Al, 17 wt % Si, 14 wt % Mn, and 14 wt % Fe. Experiments were conducted at temperatures between 600 and 800°C, using compaction stresses of up to 20 MPa. Rietveld analysis of x-ray diffraction patterns of fully processed samples showed that the powders were transformed into a mixture of Al9FeMnSi and Al9FeMn2Si phases. However, as temperature and pressure were increased, the Al9FeMnSi phase was transformed into the Al9FeMn2Si phase. Differential Thermal Analysis, as well as microstructural characterization by scanning electron microscopy and x-ray diffraction, showed that these intermetallics do not form directly from the powder mixtures. Rather, they are the result of metallurgical reactions between a molten Al-Si solution and various intermediate phases formed during reactive sintering.