Preparation, Structures Nano TiO_2 Particles, and the properties of TiH_2 Coated with Nano TiO_2

The surface of Titanium Hydride (TiH 2) is coated by Nano Titanium Dioxide (TiO 2) particles prepared in both of methods of hydrolysis reaction of Ti(OC 4H 9) 4 and base precipitation reaction of Ti(SO 4) 2. TiH 2 coated with nano TiO 2 particles, in which there is an oxidation film on its surface, shown in the experiments, will obviously achieve good effects on releasing hydrogen slowly in high temperature. There are different structures and properties of TiH 2 coated by nano TiO 2 particles prepared in different ways in high temperature, which can influence on releasing hydrogen.

Synthesis,characterization and gas-sensing properties of Pd-doped SnO_2 nano particles

SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surface chemistry of these nano particles were characterized by transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectroscope respectively.It was observed that Pd-doping had little effect on the grain sizes of the obtained SnO2 nano particles during the hydrothermal route.During thermal annealing,Pd-doping could restrain the growth of grain sizes below 500℃ while the grain growth was promoted when the temperature increased to above 700℃.XPS results revealed that Pd existed in three chemical states in the as-synthesized sample as Pd^0,Pd^2＋ and Pd^4＋,respectively.Pd^4＋ was the main state which was responsible for improving the gas-sensing property.The optimal Pd-doping concentration for better gas-sensing property and thermal stability was 2.0%-2.5% （mole fraction）.

Stabilizing silica nanoparticles in high saline water by using polyvinylpyrrolidone for reduction of asphaltene precipitation damage under dynamic condition

In this study, the performance of stable nanofluid containing SiO2 nanoparticles dispersed and stabilized in high salinity brine for asphaltene inhibition in dynamic condition is evaluated. In the first stage of this work, the stability of silica nanoparticles in different range of water salinity(0–100000 mg·L-1) is investigated. Next, stable nanofluid containing highest salinity is selected as asphaltene inhibitor agent to inject into the damaged core sample. The estimated values of oil recovery for base case, after damage process and after inhibition of asphaltene precipitation using nanofluid are 51.6%, 36.1% and 46.7%, respectively. The results showed the reduction in core damage after using nanofluid. In addition, the relative permeability curves are plotted for the base case, after damage process and also after inhibition of asphaltene precipitation using nanofluid. Comparison of relative permeability curves shows, relative permeability of oil phase decreased after damage process as compared with the base case. But after using nanofluid the oil relative permeability curve has shifted to the right and effective permeability of oil phase has been improved.

Creep-Recovery and Relaxation Behavior of High Density Polyethylene/Hydroxyapatite Nano Particles for Bone Substitutes: Effects of Gamma Radiation

The following article has been retracted due to the fact that it cannot be accepted by the author as a journal publication. The Editorial Board takes a very strong respect to the author’s situation on this matter. This paper published in Journal of Biosciences and Medicines Vol.2 No.2, April 2014, has been removed from this site.

STRUCTURAL DETERMINATION OF TITANIUM-OXIDE NANOPARTICLES BY X-RAY ABSORPTION SPECTROSCOPY

As a potential application of titanium-oxide nanoparticles, it is extremely important to investigate a detailed picture of the surface and interior structural properties of nanocrystalline materials, such as rutile and anatase with diameters 7.0 and 4.5nm, respectively. X-ray absorption spectroscopy has been used to identify the local Ti environment and related electronic structure. We combine the experimental results at the Ti edge in both bulk and nano-crystals to determine the lattice distortion in terms of differently characteristic preedge features and the variation in the multiple-scattering region of X-ray absorption near-edge structure (XANES) spectra. The relationship between the transition peaks and the surface-to volume ratio is also discussed.

Enhanced thermoelectric performance through homogenously dispersed MnTe nanoparticles in p-type Bi_(0.52)Sb_(1.48)Te_3 nanocomposites

In this work,we report that the thermoelectric properties of Bi（0.52）Sb（1.48）Te3alloy can be enhanced by being composited with Mn Te nano particles（NPs）through a combined ball milling and spark plasma sintering（SPS）process.The addition of Mn Te into the host can synergistically reduce the lattice thermal conductivity by increasing the interface phononscattering between Bi（0.52）Sb（1.48）Te3 and MnTe NPs,and enhance the electrical transport properties by optimizing the hole concentration through partial Mn^2＋ acceptor doping on the Bi^3＋ sites of the host lattice.It is observed that the lattice thermal conductivity decreases with increasing the percentage of Mn Te and milling time in a temperature range from 300 Kto 500 K,which is consistent with the increasing of interfaces.Meanwhile,the bipolar effect is constrained to high temperatures,which results in the figure of merit z T peak shifting toward higher temperature and broadening the z T curves.The engineering z T is obtained to be 20%higher than that of the pristine sample for the 2-mol%Mn Te-added composite at a temperature gradient of 200 K when the cold end temperature is set to be 300 K.This result indicates that the thermoelectric performance of Bi0.52Sb1.48Te3 can be considerably enhanced by being composited with Mn Te NPs.

Effect of Zn Substitution on the Magnetic Properties of Cobalt Ferrite Nano Particles Prepared Via Sol-Gel Route

Zinc substituted cobalt ferrite nanoparticles (CoxZn1-xFe2O4, with x = 0.0, 0.2, 0.4, 0.8 and 1.0) were prepared via sol-gel route and the effect of zinc concentration on saturation magnetization and lattice parameter were investigated. The particle sizes of the as obtained samples were found to be ~10 nm which increases upto ~92 nm on annealing at 1000oC. The frequency bands near 564-588 cm-1 and 425-442 cm-1 are assigned to the tetrahedral and octahedral clusters which confirm the presence of M-O stretching band in ferrites. The unit cell parameter ‘a’ increases linearly with increasing concentration of zinc due to larger ionic radii of Zn2+ ion . It was found that this substitution allows tunable changes in the magnetic properties of cobalt ferrite. Interestingly, saturation magnetization first increases upto x = 0.4 and then decreases for higher Zn substitution, thus tunable changes in magnetic properties of cobalt ferrite are possible. Source of such behaviour could be the variation of exchange interaction between the tetrahedral and the octahedral sites.

Microstructure and Oxidation Behaviors of Nano-particles Strengthened NiCoCrAlY Cladded Coatings on Superalloys

Nano-particles which can largely improve the microstructure and oxidation resistance of materials are often used as a strengthening component in metal matrix composites. However, few studies were reported on its application in the bond coat of duplex structure thermal barrier coating（TBC）. Three kinds of NiCoCrAlY coatings strengthened by different nano-particles with the same addition （1%, mass fraction） were prepared by the laser cladding technique on Ni-based superalloy substrates, aiming to study the effects of the nano-particles on microstructure and oxidation resistance of NiCoCrAlY coatings （the bond coat of the duplex structure thermal barrier coatings）. Scanning electron microscope （SEM）, X-ray diffractometer（XRD） and thermogravimetry were employed to investigate their morphologies, phases and cyclic oxidation behaviors in atmosphere at 1 050℃, compared with the coating without nano-particles. With the addition of nano-particles, the growth pattern of the grains at the interface changed from epitaxial growth to non-epitaxial growth or part-epitaxial growth; slender dendrites were broken and cellularized; cracks and pores were restrained; and the oxidation weight-gain and the stripping resistance of the oxide scale were improved as well. Among the three kinds of nano-particles, the SiC nano-particles showed the most improvement on microstructure, while the CeO2 nano-particles were insufficient, but its effects on the oxidation resistance are the same as those of the SiC nano-particles. Based on the discussions of the influence mechanism, it is believed that CeO2 nano-particles would show better improvement than SiC nano-particles if the proper amount is added and the proper preparation technique of micro-nanometer composite powders is adopted, with the synergistic action of nanometer effect and reactive element effect.

Research on anti-contact fatigue performance of grease containing nano SbSbS_4 particles

Effects of nano SbSbS4particles on contact fatigue life of a steel ball were evaluated on a self-made ball-rod contact fatigue tester. The anti-fatigue mechanisms of SbSbS4 additive were analyzed by means of SEM and EDAX. It was shown that, when the grease contained SbSbS4, contact fatigue life was improved compared with that of base grease. Nanoparticle absorption action, nanoparticle infiltration action, and extreme pressure and anti-friction performance, explained why SbSbS4 increased the contact fatigue life of the steel ball tested.

MORPHOLOGY EVOLUTION OF POLY(St-co-BuA)/SILICA NANOCOMPOSITE PARTICLES SYNTHESIZED BY EMULSION POLYMERIZATION

Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.

Surface tension of lithium bromide aqueous solution/ammonia with additives and nano-particles

In order to investigate the effect of additives and nano-particle on the surface tensions of lithium bromide(Li Br) aqueous solution/ammonia, many experiments were carried out based on Wilhelmy plate method. Firstly, the surface tension of Li Br aqueous solution with 1-octanol was measured and then the comparison between the measured results and previous experimental results was given to verify the measuring accuracy. Some new additives, such as cationic surfactants cetyltrimethyl ammonium chloride(CTAC), and cetyltrimethyl ammonium bromide(CTAB) were chosen in the experiments. The experimental results show that CTAC and CTAB can obviously reduce the surface tension of Li Br aqueous solution/ammonia. In addition, it is found that nano-particles cannot remarkably decrease the surface tension of Li Br aqueous solution/ammonia. However, the mixed addition of additives and nano-particles can remarkably affect the surface tension of Li Br aqueous solution/ammonia. That is to say, additives play more important role in reducing the surface tension of Li Br aqueous solution/ammonia. But nano-particles may enhance the heat transfer in the absorption refrigeration process.

Preparation and drug releasing property of magnetic chitosan-5-fluorouracil nano-particles

In order to synthesize the targeting drug carrier system,magnetic chitosan-5-fluorouracil nano-particles were prepared by using 5-fluorouracil(5-Fu)as model drug,Fe3O4 nano-particles as kernel,chitosan as enveloping material and glutaraldehyde as cross linking agent through ultrasonic technique.The morphology of the magnetic chitosan-5-Fu nano-particles was observed with a transmission electron microscope(TEM).The results showed that magnetic chitosan-5-Fu nano-particles were prepared in spherical structure with a size range of 50-60 nm.The delivering capacity and drug releasing properties of magnetic chitosan-5-Fu nano-particles were investigated by UV-vis spectrum analysis.The results showed that the loading capacity was 13.4%and the cumulative release percentage in the phosphate buffer(pH=7.2)solutions was 68%in 30 h.These data indicate that the wrapped drug of magnetic chitosan-5-Fu nano-particles was slowly-released.The magnetic response of magnetic chitosan-5-Fu nano-particles was studied by UV-vis spectrometer to detect the changes of solution absorbance.Without external magnetic field,the nano-particle deposition rate was slow.When being subjected to 8 mT magnetic field,the particle sedimentation rate was increased rapidly.The results showed that magnetic chitosan-5-Fu nano-particles have a magnetic stability and strong targeting characteristics.

Graphene oxide assisted facile hydrothermal synthesis of LiMn_(0.6)Fe_(0.4)PO_4 nanoparticles as cathode material for lithium ion battery

Assisted by graphene oxide（GO）,nano-sized LiMn0.6Fe0.4PO4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn0.6Fe0.4PO4（S2）was about 80 nm in diameter.The discharge capacity of LiMn0.6Fe0.4PO4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn0.6Fe0.4PO4 and it in situ reduction of GO could improve the electrical conductivity of LiMn0.6Fe0.4PO4 material.

Tribological characteristics of micro or nano particles between the gear pairs

将4种分别含有微米或纳米固体粒子的磨合油应用在45号钢齿轮副磨合试验中，研究这2类粒子对齿轮磨合的影响及行为．研究中使用的2种微米粒子分别是平均粒径为10μm的碳酸钙和100μm的石英砂，2种纳米粒子分别是平均粒径为5nm的金刚石和30nm的导电炭黑，大齿轮和小齿轮未磨合前的齿面三维粗糙度分别是24．00μm和32．97μm．试验结果表明：微米粒子对磨合磨损的主要影响表现为磨粒磨损，且微粒的粒径越大，磨粒磨损越剧烈；纳米粒子对磨合磨损影响不大，但纳米粒子能够吸附、填充和渗入齿面，从而改观齿面形貌和改善齿面摩擦学性能．另外，在含有这2类粒子的磨合磨损中，摩擦副间都有不同程度的“负电阻”现象发生，且两齿轮的磨损率蒡越大，该电现象越明显．

Preparation and Characterization of Fe3O4 Magnetic Nano-particles by ^（60）Co γ-ray Irradiation

By using a new method, ^60Co γ-ray irradiation, Fe3O4 magnetic nano-particles were successfully synthesized at room temperature under ambient pressure. The structure, morphology and magnetic properties of these nanoparticles were characterized by X-ray diffraction （XRD）, transmission electron microscope （TEM） and vibrating sample magnetometer （VSM）, respectively. The radiation formation mechanism was also discussed. The results show that the absorbed dose can greatly influence the structure, morphology and magnetic properties of the products. XRD and TEM studies show that the product prepared by γ-ray irradiation （10 kGy） is pure FesO4 phase and the mean diameter of these nano-particles is about 21 nm. The Fe3O4 nano-particles synthesized by γ-ray irradiation （10 kGy） are mainly in small cubic shape and the size uniformity of these particles is good.

Pressure-Induced Structural Transitions of the Zinc Sulfide Nano-particles with Different Sizes

ZnS nano-particles with average sizes of 10 nm and 5 nm were fabricated by sol-gel method, and their pressure-induced phase transformations were in-situ examined in a diamond anvil cell by energy dispersive X-ray diffraction （EDXD） from ambient pressure to 35.0 GPa. From the obtained interplanar spacing data,the volume compression ratios were derived at different pressures, and then the bulk modulus and its pressure derivative were obtained by fitting to the Murnaghan equation. It is found that both ZnS nano-particles initially in the zinc-blende phase transformed to cubic NaCl structure in the presence of pressure and the transition was reversible when the pressure was released. Moreover, it is suggested that a smaller particle size will induce a larger transition pressure.

Preparation of nanoparticles of magnesium hydroxide from bittern

Mg(OH)2 nano-particles with fiber-like morphology were prepared by chemical precipitation process,with the bittern from Qinghai Salt Lakes used as Mg2+ raw material and ammonia water as precipitator. The influence of aging procedure on the Mg(OH)2 crystal was investigated by TEM and crystalline size calculation. The Mg(OH)2 nano-particles were characterized by XRD,SEM,TEM and TG-DTA methods. The results indicate that the Mg(OH)2 nano-particles with perfect crystal are obtained after aging procedure above 50 ℃,and the grain size increases with increasing aging temperature and prolonging aging time. Mg(OH)2 particles with fiber-like morphology,20-60 nm in diameter and 300-500 nm in length are observed,Mg(OH)2 will decompose into MgO at temperature range 347-623 ℃.

Synthesis of nano-CaCO_3 composite particles and their application

Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS （acrylonitrile-butadiene-styrene copolymer） composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate （BA） and styrene （St）. The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment. 2008 University of Science and Technology Beijing. All rights reserved.

Friction and Wear of Polymer Composites Filled by Nano-Particles: A Review

Composites formed by adding nano-scale particles to a polymer matrix results in improving electrical, mechanical, and thermal properties of the composite. Good tribological properties can be obtained for polymers filled with nano-scale fillers compared to that filled with micro-scale particles. The friction and wear resistance of these composites is found to increase with increasing filler concentration. It is also possible to use multi-functional fillers to develop high performance composites which cannot be achieved by using a single filler.

Factors Affecting the Reductive Properties of the Core-Shell SiO2-Coated Iron Nanoparticles

In this study, novel core-shell SiO2-coated iron nanoparticles (SiO2-nZVI) were synthesized using a one-step Stoeber method. The Malachite green degradation abilities of the nanoparticles were investigated. The effects of ethanol/distilled water volume ratio, presence and absence of PEG, tetraethyl orthosilicate (TEOS) dosage, and hydrolysis time used in the nanoparticles preparation process were investigated. The results indicated that the SiO2-coated iron nanoparticles had the highest reduction activity when the particles synthesized with ethanol/H2O ratio of 2:1, PEG of 0.15 ml, TEOS of 0.5 ml and the reaction time was 4 h. The SiO2-nZVI nanoparticles were characterized using Transmission Electron Microscopy (TEM), Energy Dispersive Spectrometry (EDS) and powder X-Ray Diffraction (XRD). The results showed that the average particles diameter of the SiO2-nZVI was 20 - 30 nm. The thickness of the outside SiO2 film is consistent and approximately 10 nm. The results indicated that the nanoparticles coated completely with a transparent SiO2-film. Such nanoparticles could have wide applications in dye decolorization.