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Chinese Physics B 2012年第11期21卷 459-466页

作者： M.Hakimi P.Kameli H.Salamati Department of Physics Isfahan University of Technology

Mechanical alloying has been used to produce nanocrystallite Co2Crl-xFexAl （x = 0, 0.4, 0.6, 1） Heusler alloys. The formation of the L21 phase of Co2Cr1-xFexAl by the mechanical alloying method was investigated. The effect of Fe doping on the structural and magnetic properties of the samples was also studied. The results were compared with the Slater Pauling prediction. A comparison between these samples and those prepared by the arc-melting method in the literature was made. An increase of the coercivity Hc with the increasing Fe doping level was observed. This phenomenon was explained by the increases of lattice strain and magnetic anisotropy with the increasing Fe content.

关键词： magnetic property X-ray diffraction nanocrystallite mechanical property

Growth kinetics of MgH2 nanocrystallites prepared by ball milling

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Journal of Materials Science & Technology 2020年第15期47卷 178-183页

作者： Caiqin Zhou Yayu Peng Qingan Zhang School of Materials Science and Engineering Anhui University of TechnologyMa'anshan 243002China

MgH2 is one of promising hydrogen storage materials due to its high hydrogen capacity of 7.6 wt%.However,MgH2 nanocrystallites easilygrow up during hydrogen absorption-desorption cycling,leading to deterioration of hydrogen storage *** clarify the growth kinetics of MgH2 crystallites,the growth characteristics of MgH2 nanocrystallites are investigated in this *** growth exponents of MgH2 nanocrystallites in pure MgH2 and MgH2-10 wt% Pr3 Al11 samples are evaluated to be n=5 and n=6,***,their activation energies for crystallite growth are also determined to be109.2 and 144.2 kJ/mol,*** increase of growth exponent and rise of activation energy for crystallite growth in MgH2-10 wt% Pr3 Al11 composite are ascribed to the presence of nano-sized Pr3 Al11phase.

关键词： Magnesium hydride Crystallite growth kinetics nanocrystallite Pinning effect

Predicting nanocrystallites Development in Cement Pastes

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Open Journal of Civil Engineering 2018年第1期8卷 27-40页

作者： A. Feylessoufi UnivEvry University of Paris Saclay F-91025 Evry France

Cement nanocrystallites constitute the binding phase in concrete, a material that has been around for more than two thousand years and remains the most widely used of manufactured materials. Thanks to their size, their disordered nature, their reprecipitation after combination with water, and their rapid evolution when the concrete sets, these nanostructures have only been subjected to careful investigation quite recently. Nanotechnology is now able to control their formation and exploit their evolution (shrinking and swelling) during the setting phase to produce a concrete with a strength and ductility close to those of steels. Furthermore, the analysis of basic nanoscopic reactions occurring during setting, and their modification by polymer additives acting at the interfaces, numerical modelling techniques are potentially able to predict big evolutions and properties of nanocrystallites. Here we discuss the future of these nanocrystallites in new applications.

关键词： Concrete Cement Hydration nanocrystallite Nanomaterial

Effect of Ni^(+2)-substituted Fe_2TiO_5 on the H_2-reduction and CO_2 Catalytic Decomposition Reactions at 500℃

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Journal of Materials Science & Technology 2006年第6期22卷 846-850页

作者： M.H.Khedr Chemistry Department Faculty of ScienceBenisuef UniversityEgypt

CO2 is a major component of the greenhouse gases, which causes the global warming. To reduce CO2 gas, high activity nanosized Ni＋2 substituted Fe2TiO5 samples were synthesized by conventional ceramic method. The effect of the composition of the synthesized ferrite on the H2-reduction and CO2-catalytic decomposition was investigated. Fe2TiO5 （iron titanate） phase that has a nanocrystallite size of -80 nm is formed as a result of heating Fe2O3 and TiO2 while the addition of NiO leads to the formation of new phases （-80 nm） NiTiO3 and NiFe2O4, but the mixed solid of NiO and Fe2O3 results in the formation of NiFe2O4 only. Samples with Ni^＋2=0 shows the lowest reduction extent （20%）; as the extent of Ni＋2 increases, the extent of reduction increases. The increase in the reduction percent is attributed to the presence of NiTiO3 and NiFe2O4 phases, which are more reducible phases than Fe2TiO5. The CO2 decomposition reactions were monitored by thermogravimetric analysis （TGA） experiments. The oxidation of the H2-reduced Ni＋2 substituted Fe2TiO5 at 500℃ was investigated. As Ni^＋2 increases, the rate of reoxidation increases. Samples with the highest reduction extents gave the highest reoxidation extent, which is attributed to the highly porous nature and deficiency in oxygen due to the presence of metallic Fe, Ni and/or FeNi alloy. X-ray diffraction （XRD） and transmission electron microscopy （TEM） of oxidized samples show also the presence of carbon in the sample containing Ni＋2〉0, which appears in the form of nanotubes （25 nm）.

关键词： nanocrystallite Ferrite Titanate Reduction CO2 decomposition Carbon nanotubes

Y3Al5O12 nanocrystallites Prepared from a Novel Crystalline Precursor

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Y3Al5O12 Nanocrystallites Prepared from a Novel Crystalline ...

Thermal and Structural Characterization of Transparent Rare-Earth Doped Lead Fluoride Glass-Ceramics

The 1st International Congress on Advanced Materials 2011

作者： Rongjiang Han Dan Gao Kezheng Chen College of Materials Science and Engineering Qingdao University of Science and Technology

A novel crystalline precursor for preparing Y3Al5O12（YAG） nanocrystallite was synthesized via a co-precipitation method using（NH4）2CO3 solution as the *** precursor was characterized by means of powder X-ray diffraction（XRD）,Fourier transform infrared spectra（FTIR）,thermal gravimetry（TG）,differential thermal gravimetry（DTG） and differential scanning calorimetry（DSC）,*** empirical chemical formula of the crystalline precursor can be expressed as 5[（NH4）2Al6（CO3）3（OH）14]9[Y2（CO3）33H2O] according to the test *** measured weight loss of 46.7% of the precursor without consideration of the absorbed water is in accord with the calculated value of 47.5% according to theabove empirical *** phase-pure YAG nanocrystallites were obtained by calcining the above precursors at 900 ℃ for 2 hours in air *** electronic microscopy（TEM） result showed that the particle size of YAG nanocrystallites is 40-80 *** mechanism of themal decomposition of the crystalline precursor was also presented.

关键词： Y3Al5O12 co-precipitation method crystalline precursor nanocrystallite

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New Journal of Glass and Ceramics 2012年第2期2卷 65-74页

作者： Chaouki Bensalem Michel Mortier Daniel Vivien Patrick Gredin Gilles Patriarche Madjid Diaf Département de Physique Université d’Annaba Annaba Algérie Laboratoire de Chimie de la Matière Condensée de Paris UPMC Chimie ParisTech Paris France Laboratoire de Photonique et Nanostructures Marcoussis France

The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE3+: β-PbF2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE3++: β-PbF2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF2 solid solution results from a combined effect of Pb2+-RE3+ substitution and interstitial F– introduction. In the glass ceramics, RE3+: β-PbF2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.

关键词： Glass-Ceramic Rare-Earth Thermal Analysis Devitrification nanocrystallite X-Ray Diffraction

Electron-Irradiation Induced Nanocrystallization of Pb（ll） in Silica Gels Prepared in High Magnetic Field

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Journal of Chemistry and Chemical Engineering 2015年第1期9卷 61-66页

作者： Takamasa Kaito Atsushi Mori Chihiro Kaito Graduate School of Engineering Tokushima University Tokushima 770-8506 Japan Institute of Technology and Science Tokushima University Tokushima 770-8506 Japan Department of Nanophysics in Frontier Project Ritsumeikan University Shiga 535-8577 Japan

In a previous study, structure of silica gels prepared in a high magnetic field was investigated. While a direct application of such anisotropic silica gels is for an optical anisotropic medium possessing chemical resistance, we show here their possibility of medium in materials processing. In this direction, for example, silica hydrogels have so far been used as media of crystal growth. In this paper, as opposed to the soft-wet state, dried silica gels have been investigated. We have found that lead （II） nanocrystallites were formed induced by electron irradiation to lead （ll）-doped dried Hydrogels made from a sodium metasilicate solution doped with silica gels prepared in a high magnetic field such as B = 10 T. lead （II） acetate were prepared. The dried specimens were irradiated by electrons in a transmission electron microscope environment. Electron diffraction patterns indicated the crystallinity of lead （II） nanocrystallites depending on B. An advantage of this processing technique is that the crystallinity can be controlled through the strength of magnetic field B applied during gel preparation. Specific skills are not required to control the strength of magnetic field.

关键词： Silica gel magnetic field nanocrystallite electron irradiation.

TiO<sub>2</sub>-Polysulfone Beads for Use in Photo Oxidation of Rhodamine B

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Soft Nanoscience Letters 2012年第4期2卷 67-70页

作者： Sanjay V. Ingale Pratap B. Wagh Arvind K. Tripathi Rohit Srivastav Srivastav Imejinary K. Singh Ramesh C. Bindal Satish C. Gupta Applied Physics Division Bhabha Atomic Research Centre Mumbai India Chemistry Division Bhabha Atomic Research Centre Mumbai India Desalination Division Bhabha Atomic Research Centre Mumbai India

The nano sized TiO2 has been synthesized by sol gel process. The titaniumisopropaxide diluted in propanol hydrolyzed under acidic condition to form a gel. The solvent from gel pores has been extracted at ambient pressure resulting in nano sized TiO2 crystallites. The crystalline phase of TiO2 could be assigned to anatase structure. An average crystallite size is about 12 nm. The surface area of TiO2 found to be 235 m2/g. The TiO2 nanocrystallites thus produced were blended with polysulphone to form its beads for ease of operation. These beads of TiO2 were used as photo catalyst in conjunction with H2O2 oxidizer in presence of UV light (254 nm) for treating the 50 ppm Rhodamine B aqueous solution. The solution decolorized within 10 minutes resulting in disappearance of absorption peak at around 600 nm in UV spectrometry. The organic entities degrade in about 60 minutes. The beads of nano sized TiO2 could be easily recovered from the treated effluent for further use.

关键词： Photo Oxidation Rhodamine B TiO2 Beads Polysulphone nanocrystallite

Photoluminescence of Por-Si with High-ordered Mosaic Structure Received at Long Anodic Etching p-Si (100) in the Electrolyte with an Internal Current Source

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Optics and Photonics Journal 2013年第2期3卷 217-221页

作者： K. B. Tynyshtykbaev V. B. Glazman M. A. Yeleuov A. T. Isova B. A. Rakymetov D. Muratov S. Z.Tokmoldin Institute of Physics and Technology Almaty Kazakhstan

Photoluminescence spectra and nature of light-emitting centers of a porous silicon (por-Si) samples are given. The por- Si samples had high-ordered mosaic structure, which was received under long anodic etching p-Si(100) in electrolyte with an internal current source. The photoluminescence spectra were monitored at room temperature before and after annealing in air and vacuum. Comparative analysis of photoluminescence spectra of the por-Si samples annealed at different temperatures in air and vacuum shows that the thermal annealing conditions has significant effect on the intensity and spectral content of the photoluminescence spectra. The nature of the luminescence emission centers at different temperatures and annealing conditions was discussed.

关键词： Photoluminescence Spectra Thermal Annealing Emitting Centershydrides Oxides Mosaic Structure nanocrystallite Por-Si

The Preparation of Nanosized Iron Oxide Using Hydrolysis Enhanced by CuO and Their Characterization

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The Preparation of Nanosized Iron Oxide Using Hydrolysis Enh...