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Bondlength alternation of nanoparticles Fe2O3 coated with organic surfactants probed by EXAFS 用EXAFS探测有机表面活性剂包覆纳米Fe2O3的键长变化
Nanostructured Materials Pub Date : 1999-11-01 DOI: 10.1016/S0965-9773(99)00425-0
T Liu , L Guo , Y Tao , T.D Hu , Y.N Xie , J Zhang
{"title":"Bondlength alternation of nanoparticles Fe2O3 coated with organic surfactants probed by EXAFS","authors":"T Liu ,&nbsp;L Guo ,&nbsp;Y Tao ,&nbsp;T.D Hu ,&nbsp;Y.N Xie ,&nbsp;J Zhang","doi":"10.1016/S0965-9773(99)00425-0","DOIUrl":"10.1016/S0965-9773(99)00425-0","url":null,"abstract":"<div><p><span>The nanoparticles γ-Fe</span><sub>2</sub>O<sub>3</sub><span><span> coated with surfactants, DBS, ST and CTAB, repsectively, were synthesized by microemulsion method. The coated ferric oxides, which show enhanced nonlinear optical properties compared with their bulk counterpart, were probed by EXAFS in solution forms. The x-ray </span>absorption spectra for Fe K edge were measured at room temperature by help of synchrotron radiation light source. Extended x-ray absorption fine structure analysis shows that the coating layers of organic molecules interact with surface atoms of nanoparticles, the Fe-O bond length was extended.</span></p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00425-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81990583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 25
Grain growth in nanocrystalline SnO2 prepared by sol-gel route 溶胶-凝胶法制备SnO2纳米晶的晶粒生长
Nanostructured Materials Pub Date : 1999-10-01 DOI: 10.1016/S0965-9773(99)00387-6
C.H Shek , J.K.L Lai , G.M Lin
{"title":"Grain growth in nanocrystalline SnO2 prepared by sol-gel route","authors":"C.H Shek ,&nbsp;J.K.L Lai ,&nbsp;G.M Lin","doi":"10.1016/S0965-9773(99)00387-6","DOIUrl":"10.1016/S0965-9773(99)00387-6","url":null,"abstract":"<div><p>The isothermal grain growth of nanocrystalline SnO<sub>2</sub><span>, prepared by the sol-gel route was investigated at various temperatures between 500°C and 800°C. Grain growth data were analyzed using two different models. A conventional grain growth model for polycrystalline materials yields an extremely low activation energy of 47 kJ/mol, but large grain growth exponent n from 5 to 11. These values exceed the rational region deduced from conventional theory. An alternative model is based on the assumption that the ordering of the interface regions in nanocrystalline SnO</span><sub>2</sub> occurs simultaneously with grain growth by structural relaxation. This structural relaxation model describes the grain growth kinetics satisfactorily and also yields a low activation energy of 31 kJ/mol appropriate for the rearrangement of atoms.</p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00387-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80292447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 72
Preparation of self-assembled cobalt nanocrystal arrays 自组装钴纳米晶阵列的制备
Nanostructured Materials Pub Date : 1999-10-01 DOI: 10.1016/S0965-9773(99)00375-X
J.S Yin , Z.L Wang
{"title":"Preparation of self-assembled cobalt nanocrystal arrays","authors":"J.S Yin ,&nbsp;Z.L Wang","doi":"10.1016/S0965-9773(99)00375-X","DOIUrl":"10.1016/S0965-9773(99)00375-X","url":null,"abstract":"<div><p>Processing of self-assembled magnetic nanocrystals has vitally scientific and technological interests. In this paper, three different kinds of self-assemblies of cobalt nanocrystals were processed using particles processed by thermal decomposition<span> of cobalt carbonyl in toluene. In case 1, two-dimensional self-assembly of cobalt nanocrystals with an average particle size of 9.2 nm and polydispersity of 9% has been formed. In case 2, macroscopic whisker structures composed of self assembled cobalt nanocrystals (with an average size of 8 nm) were formed during the thermal decomposition under an externally applied magnetic field. The whiskers can be aligned in the longitudinal axis direction during drying using an external magnetic field. In case 3, one-dimensionally ordered, densely packed self-assemblies have also been prepared using cobalt nanocrystals with irregular shape and larger particle sizes (10–20 nm). The formation of these different structures is attributed to the magnetic properties of cobalt particles with different sizes.</span></p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00375-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79616463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 28
Effects of helium ion implantation on the structure of nanophase and coarse-grain titanium films 氦离子注入对纳米相和粗晶钛膜结构的影响
Nanostructured Materials Pub Date : 1999-10-01 DOI: 10.1016/S0965-9773(99)00382-7
Zheng Gao , Yuzun Gao , Yonghong Li , Taisong Zhang , Yi Li
{"title":"Effects of helium ion implantation on the structure of nanophase and coarse-grain titanium films","authors":"Zheng Gao ,&nbsp;Yuzun Gao ,&nbsp;Yonghong Li ,&nbsp;Taisong Zhang ,&nbsp;Yi Li","doi":"10.1016/S0965-9773(99)00382-7","DOIUrl":"10.1016/S0965-9773(99)00382-7","url":null,"abstract":"<div><p><span><span>Nanophase and coarse-grain titanium films were prepared on Mo substrates by Ion Beam Assisted Deposition. </span>Ion implantation<span> of helium was used to simulate the behavior of helium in titanium films. Helium ions (100 keV) were implanted into the titanium films with a dose of 5 × 10</span></span><sup>17</sup>/cm<sup>2</sup><span><span>. The retained helium in the titanium films after implantation was detected by Enhanced Proton Back Scattering (EPBS). The microstructure of titanium films and the distribution of helium bubbles were studied by </span>Transmission Electron Microscopy (TEM). It was found that helium bubbles were formed in the coarse-grain titanium films with a size distribution of 1 to 10 nm and a numerical density of 5 to 25 × 10</span><sup>22</sup>/m<sup>3</sup>. No helium bubble was observed in the nanophase titanium films. A discussion is presented for helium bubble formation.</p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00382-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75880876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 6
Structure, strength and toughness of nanocrystalline FeAl 纳米晶FeAl的结构、强度和韧性
Nanostructured Materials Pub Date : 1999-10-01 DOI: 10.1016/S0965-9773(99)00385-2
M.A Morris-Muñoz , A Dodge , D.G Morris
{"title":"Structure, strength and toughness of nanocrystalline FeAl","authors":"M.A Morris-Muñoz ,&nbsp;A Dodge ,&nbsp;D.G Morris","doi":"10.1016/S0965-9773(99)00385-2","DOIUrl":"10.1016/S0965-9773(99)00385-2","url":null,"abstract":"<div><p>Refining grain size to the nanocrystalline level has been suggested as a way of improving strength while enhancing ductility and toughness. In the present study, nanocrystalline bulk FeAl has been prepared by mechanical alloying and hot forging<span><span>. Powders quickly reach a state of partial order during milling, and low temperature annealing is sufficient to chemically homogenise and give full order. Contamination during milling leads to the formation of carbide and oxide particles, which stabilise fine grains during heating. Bulk materials show grain sizes of 20nm to 100nm depending on the consolidation temperature. Hardness and compression strength show little change over this grain size range. </span>Fracture toughness stays high down to moderately small grain sizes, falling only for consolidation at the lowest temperatures. There appears to be a reasonable range of fine grain sizes (40–100nm) where good interparticle bonding and high densities can be achieved leading to good strength and toughness.</span></p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00385-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81202260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 85
Effect of oxygen deficiency on the Raman spectra and hyperfine interactions of nanometer SnO2 氧缺乏对纳米SnO2拉曼光谱和超精细相互作用的影响
Nanostructured Materials Pub Date : 1999-10-01 DOI: 10.1016/S0965-9773(99)00373-6
C.H Shek , G.M Lin , J.K.L Lai
{"title":"Effect of oxygen deficiency on the Raman spectra and hyperfine interactions of nanometer SnO2","authors":"C.H Shek ,&nbsp;G.M Lin ,&nbsp;J.K.L Lai","doi":"10.1016/S0965-9773(99)00373-6","DOIUrl":"10.1016/S0965-9773(99)00373-6","url":null,"abstract":"<div><p><span>The Raman and Mössbauer spectra of nano-SnO</span><sub>2</sub><span><span> specimens with crystallite size 3–16 nm were measured at room temperature. Specimens were annealed at different temperatures in oxygen atmosphere and vacuum respectively. Both the Raman and Mössbauer spectra of the specimens consist of crystalline and interface (or surface) components. The effects of oxygen deficiency on the </span>Raman spectra are presented and correlated with the changes of the Sn-O bond properties, which were obtained from the corresponding Mössbauer spectra.</span></p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00373-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86640401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 87
Characterization of barium titanate ceramic/ceramic nanocomposite films prepared by a sol-gel process 溶胶-凝胶法制备钛酸钡陶瓷/陶瓷纳米复合膜的表征
Nanostructured Materials Pub Date : 1999-10-01 DOI: 10.1016/S0965-9773(99)00374-8
M.C Cheung , H.L.W Chan , Q.F Zhou , C.L Choy
{"title":"Characterization of barium titanate ceramic/ceramic nanocomposite films prepared by a sol-gel process","authors":"M.C Cheung ,&nbsp;H.L.W Chan ,&nbsp;Q.F Zhou ,&nbsp;C.L Choy","doi":"10.1016/S0965-9773(99)00374-8","DOIUrl":"10.1016/S0965-9773(99)00374-8","url":null,"abstract":"<div><p>Barium titanate (BaTiO<sub>3</sub><span>) ceramic/ceramic nanocomposite thick films (∼16μm) for ultrasonic transducer applications were prepared by a modified sol-gel process. Nano-sized BaTiO</span><sub>3</sub> powder was dispersed in a sol-gel matrix of BaTiO<sub>3</sub><span><span> to form a composite solution. Films were prepared by spin coating and then annealed at various temperatures. The crystallization of the </span>composite film was studied by X-ray diffraction. The dielectric permittivity and the ferroelectric properties of the film were also measured.</span></p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00374-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91126905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 40
A two step SPD processing of ultrafine-grained titanium 超细晶钛的两步SPD加工
Nanostructured Materials Pub Date : 1999-10-01 DOI: 10.1016/S0965-9773(99)00384-0
V.V Stolyarov , Y.T Zhu , T.C Lowe , R.K Islamgaliev , R.Z Valiev
{"title":"A two step SPD processing of ultrafine-grained titanium","authors":"V.V Stolyarov ,&nbsp;Y.T Zhu ,&nbsp;T.C Lowe ,&nbsp;R.K Islamgaliev ,&nbsp;R.Z Valiev","doi":"10.1016/S0965-9773(99)00384-0","DOIUrl":"10.1016/S0965-9773(99)00384-0","url":null,"abstract":"<div><p><span><span>Equal channel angular pressing (ECAP) and high pressure torsion (HPT) are two severe </span>plastic deformation<span> (SPD) processes that have been used to process ultrafine-grained (UFG) materials. In this investigation, we have attempted to combine these two processes to refine the grain size of coarse-grained pure titanium. ECAP processing was first carried out at 500–450 °C to refine the grain size to about 300 nm. Further processing by HPT resulted in finer grain size and higher dislocation density. The second step, HPT processing, also increased the </span></span>microhardness, ultimate strength, yielding strength and ductility of the UFG pure titanium.</p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00384-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83910617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 212
Correlation between microstructure and electrical properties of tungsten-silica nanocomposites 钨-二氧化硅纳米复合材料微观结构与电性能的关系
Nanostructured Materials Pub Date : 1999-10-01 DOI: 10.1016/S0965-9773(99)00388-8
Tamar Tepper , Shlomo Berger
{"title":"Correlation between microstructure and electrical properties of tungsten-silica nanocomposites","authors":"Tamar Tepper ,&nbsp;Shlomo Berger","doi":"10.1016/S0965-9773(99)00388-8","DOIUrl":"10.1016/S0965-9773(99)00388-8","url":null,"abstract":"<div><p>The electrical properties and the microstructure of nanocomposite materials composed of nano-sized amorphous silica powder and micron-sized tungsten powder were studied as a function of composition and heat treatment temperature. The dielectric constant and the electrical conductivity of the nanocomposites are higher than those of pure silica powder at all compositions. The percolation threshold of this system is about 20% vol. W. Above this composition a sharp increase in the dielectric constant and in the electrical conductivity occurs. This increase becomes even sharper after the nanocomposites are heat treated at 950°C for 1 hour. No changes in the microstructure are observed up to this temperature. It is suggested that the electrical properties of the nanocomposites are dominated mainly by dangling bonds at the W/SiO<sub>2</sub> interfaces. Further research should be undertaken to investigate the factors controlling the dielectric constant and the electrical conductivity in order to obtain high capacitance materials with high dielectric constant and low electrical conductivity.</p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00388-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89810436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 9
Demonstration of gas-phase combustion synthesis of nanosized particles using a hybrid burner 混合燃烧器气相燃烧合成纳米颗粒的实验研究
Nanostructured Materials Pub Date : 1999-10-01 DOI: 10.1016/S0965-9773(99)00376-1
Margaret S Wooldridge , Stephen A Danczyk , Jianfan Wu
{"title":"Demonstration of gas-phase combustion synthesis of nanosized particles using a hybrid burner","authors":"Margaret S Wooldridge ,&nbsp;Stephen A Danczyk ,&nbsp;Jianfan Wu","doi":"10.1016/S0965-9773(99)00376-1","DOIUrl":"10.1016/S0965-9773(99)00376-1","url":null,"abstract":"<div><p><span>A new approach for gas-phase combustion synthesis<span><span> of nanosized particles using a novel hybrid burner facility is demonstrated. The basis of the synthesis technique is to use both a premixed flame and a </span>diffusion flame to control the synthesis environment. Specific experimental results for silica (SiO</span></span><sub>2</sub>) production from silane/hydrogen/oxygen/argon (SiH<sub>4</sub>/H<sub>2</sub>/O<sub>2</sub><span><span><span><span>/Ar) flames are presented. A parametric study of several burner conditions was conducted, and the subsequent effects on the particles produced were determined. Particle morphology was examined using </span>transmission electron microscopy (TEM). The results indicated a broad variation in particle size and structure as a function of the burner operating conditions (in particular, reactant </span>stoichiometry<span> and flame geometry). Particle structures were aggregated with primary particles varying from 6–8 nm in size (high oxygen concentration conditions) to larger more continuous structures with primary particles 18–20 nm in size (low oxygen concentration conditions). Bulk material properties were examined using Fourier transform infrared spectroscopy (FTIR), </span></span>thermal gravimetric analysis<span> (TGA), nitrogen adsorption (BET) and x-ray diffraction (XRD).</span></span></p></div>","PeriodicalId":18878,"journal":{"name":"Nanostructured Materials","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0965-9773(99)00376-1","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79849993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 14
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