Synthesis and Characterization of Sm_xGd_yCe_(1-x-y)O_(2-δ) Nanopowders

SmxGdyCe1-x-yO2-δ (x+y=0.2 and x=0, 0.04, 0.08, 0.12, 0.16, 0.2) nanopowders were prepared by a copre-cipitation method. The zeta potential and sedimentation volume of Ce(OH)4 aqueous dispersions at different pH values were measured. The isoelectric point (IEP) of Ce(OH)4 suspensions is 7.0. The maximum potential value of -18.5 mV and maximum sedimentation volume of 19 ml are reached at pH=10. The evolution behaviors of the xSm(OH)3·yGd(OH)3·(1-x-y)Ce(OH)4 dried powders in the heating process was characterized by DTA/TG and XRO. The powders decompose to ceria based solid solution at a temperature below 300℃ and forms cubic fluorite structure ceria at about 650℃. The properties of SmxGdyCe1-x-yO2-δ solid solutions were characterized by XRD, TEM and BET. The lattice parameter of doped Ce02 increases linearly with increasing Sm3+ substitution (or decreasing Gd3+ substitution). The particle size of the doped ceria powders is from 5 nm to 10 nm.     

自组装法合成介孔铝酸锌尖晶石陶瓷纳米粉

采用硝酸铝和硝酸锌为无机原料,以嵌段聚合物P123为表面活性剂,自组装法合成了介孔结构的铝酸锌尖晶石纳米粉体。利用X射线衍射、透射电镜、氮气吸附-脱附比表面测定仪对铝酸锌样品进行表征,样品为单一尖晶石相,而且具有介孔结构,500℃焙烧的铝酸锌样品比表面积最大,比表面积为98.4m2·g-1。     

Grain growth and crystallinity of ultrafine barium titanate particles prepared by various routes

Variations in tetragonal distortion and the degree of crystallinity of ultrafine BaTiO₃ particles—both industrially applied criteria qualifying their polar characteristics—upon growth during annealing were studied on powders, prepared by the hydrothermal synthesis and by the oxalate route respectively. Regardless of the synthetic route both these properties were found to develop approximately to the same extent with increasing primary particle size. The degree of crystallinity was detectable only above a critical value of c/a=1.007 at an average particle size of around 120 nm. Intragranular porosity in hydrothermal powders and the stoichiometric Ba/Ti-ratio are of minor influence. However, distinct differences in particle growth behavior for both powders were observed. This discrepancy is ascribed to a special morphology of the hydrothermal product, where enhanced particle growth was found to be governed by oriented attachment of individual crystallites and by the motion of solid–solid interfaces.     

Synthesis of AlN nanopowder coated with a thin layer of C,using a thermal plasma reactor

High-purity nanocrystalline aluminum nitride powders were synthesized by using a 12?kW non-transferred arc plasma. The synthesis was conducted in a versatile, new designed, one-chamber thermal plasma reactor (TPR). The novel experimental assembly incorporated better working conditions like: high temperature gradient between the crucible and reactor's wall, and high super-saturation of the system by nitrogen and carbon. Thermodynamic modelling of the synthesis was conducted in order to achieve the best conditions for AlN formation. In this study, aluminum discs of Al 1100 were used as precursor material and pure nitrogen was the only gas used as reagent and plasmogenic gas.Nanopowders collected from reactor's wall were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-Ray diffraction (XRD). Synthesized h-AlN nano-powders were found to be free of oxides and aluminum metal. A thin carbon-layer around the particles was detected. TEM results indicated that the carbon-layer was around 5 and 10?nm. This outcome could make a significant difference with other synthesis reported in the literature since the occurrence of the carbon-layer, could delay AlN oxidation, prevent hydration, and could avoid the agglomeration of the particles.     

Dielectric properties of barium titanate ceramics with different materials powder size

The dielectric properties of barium titanium ceramics fabricated with nano-size fine powders (about 40 nm) are compared with that fabricated with micro-size coarse powders (about 2 μm). Three kinds of ceramics were fabricated; one using pure nano-size fine powders, the other using pure micro-size coarse powders, and the third using the combination of both. The sintering temperature of the ceramics with pure nano-size fine powders is 150 °C lower than that with pure micro-size coarse powders. For the same sintering conditions, the relative density of the ceramics is increases with the amount of nano-size fine powders. The grain size of the ceramics body with pure micro-size coarse powder is about 5 μm, but that of pure nano-size fine powder is about 1 μm. The room temperature dielectric constant of the ceramics increases with the increasing of the amount of nano-size fine powder. For pure nano-size fine powders, the room temperature dielectric constant is about 5000, and that of micro-size coarse powders is about 2200.     

Preparation and characterization of single-phase α-Fe2O3 nano-powders by Pechini sol-gel method

In this work, single-phase α-Fe₂O₃ nano-particles were first synthesized via Pechini sol-gel method using citric acid and polyethylene glycol-6000 as chelating agents. The structural coordination of as-prepared polymeric intermediates was investigated by FTIR analysis. Thermal behavior of the polymeric intermediates was studied by TG-DTG-DSC thermograms. The structure of the powders calcined at different temperatures was characterized by XRD and FESEM. The single-phase α-Fe₂O₃ nano-powders with uniform size were prepared when the polymeric intermediate calcined at 600 °C, and the lowest particle size was found to be 30 nm.     

Optimizing the dispersion of calcium phosphate nanoparticles for cellular studies using statistical design of experiments

The in vitro experimentation of ceramic nanoparticles often requires their dispersion in liquid media without causing particle clumps or deteriorating sample integrity. However, the dispersion of nanoparticles using the available protocols rarely leads to stable and uniform dispersions which, in turn, raises concerns about the validity, repeatability and comparability of the findings observed in vitro. Moreover, the ability to control the final dispersion quality of ceramic nanoparticles is an essential step to obtaining optimized nanoceramic materials with desired functionality and to enhancing their performance in subsequent applications. While the need to have a comprehensive guideline for the dispersion of nanoparticles has led to several published documents and protocols, the dispersion methodology of ceramic nanoparticles and the relative contribution of the experimental parameters to the quality of resulting dispersion are still not clear. Here, we employed the statistical design of experiment (DoE) approach to systematically assess the magnitude and source of variation in dispersion quality of two different ceramic nanoparticles, hydroxyapatite and tricalcium phosphate. Using the first-order Plackett-Burman Design (PBD), nanoparticle concentration, pH and the presence of an additive were identified as the most critical factors influencing the resulting hydrodynamic size and zeta potential of the ceramic nanoparticles. Optimization using a second-order Central Composite Design (CCD) yielded a set of quadratic regression equations that were used to predict the hydrodynamic size or zeta potential of ceramic nanoparticles with high accuracy (R², 0.88–0.92). The results of PBD screening and CCD optimization experiments were employed to prepare nanoparticle dispersions of different quality, which were then used to compare the effect of aggregation on the viability of human osteosarcoma (SaOS-2) cells. Overall, the results of this study provided insight into the role that various experimental parameters play in the colloidal stability and dispersion of ceramic nanoparticles.     

高产率低成本激光合成硅基纳米陶瓷粉

本文采用激光诱导大分子有机硅熔（ＨＭＤＳ）气相反应，通过加入附加反应气和工艺参数的优化控制，在不同合成条件下制得单相非晶Ｓｉ３Ｎ４，β—ＳｉＣ纳米粉和宽组份变化范围的ＳｉＮＸＣＹ纳米复合粉（平均粒径：１０－３０ｎｍ）。与通常采用的硅烷相比，采用此有机硅烷激光合成在等同实验条件下粉产率可提高３－５倍．成本降低１倍，且具有粉体组成，结构易于控制等优点，是一种具有商业化应用前景的高性能硅基纳米陶瓷粉制备技术。     

纳米SnO2粉体及其掺杂体系液相化学法的研究进展

概述了近年来SnO2粉体及SnO2掺杂体系粉体的液相制备的研究近况。利用化学液相法能够制备出晶体结构完整、粒径分布范围窄、团聚少、粉体分散性能良好的纳米SnO2粉体以及SnO2掺杂体系粉体。     

Cuprum and Cobalt Nano-Particles Influence on Bull-Calves＇ Growth and Development

They have conducted the research to identify the possibility of increasing the abiotic polymerization intensity and efficiency both in the organism and in animals＇ muscular tissue. These tasks can be partially solved in a case of biogenous nano-metals usage such as cuprum and cobalt when adding them to the fodder. To estimate the meat productivity indexes they have formed black and white bull-calves groups. The nano-crystal cobalt ration additive for experimental bull-calves has led to live weight increase in 2 months per 6%, in 4 months per 4.8%, in 8 months per 11.7% and in 12 months per 19% in comparison with the controlled group. Amino-transferases content depending on the nano-metal has increased by the end of the experiment from 2.4% to 8.8% on retention of de Rittis index within the physiological norm. Essential amino acids content in blood has increased per 8%-13% One can also see mineral substances increase in animals＇ muscular tissue. Estimation of meat chemical content and some quantitative indexes of meat productivity prove the conclusion about the positive influence of cuprum and cobalt nano-powders fodder additives.