检索结果-南通市图书馆

Chinese Chemical Letters 1998年第12期9卷 0-0,0-0页

作者： Song W.B. Sun C.Q. Department of Chemistry Jilin University Changchun 130023 China

A novel chemically-modified electrode containing 1:12 phosphomolybdic anions was achieved on the surface of platinum electrode by the sol-gel technique. The electrode exhibits a high catalytic activity towards the ele... 详细信息

关键词： Chemically-modified electrode Electrocatalysis Polyoxometallates sol-gel technique

Synthesis of C_3S by sol-gel technique and Its Features

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2010年第1期25卷 138-141页

作者：何真 State Key Laboratory of Water Resources and Hydropower Engineering Science (Wuhan University)

sol-gel method is a technique to synthesize inorganic materials based on wet-chemical reaction theory. The results have shown that reactants tetraethyl orthosilicate （TEOS） and Ca（NO3）2·4H2O can form sol and gel in solution at 50-60 ℃, and the cosolvents are propyl alcohol （NPA） and H2O, the catalyst is HNO3. This sol-gel is burned for 12 hat 1 350-1 450 ℃ so that the organic matter, free water （moisture） in sol-gel system are removed and a solid reaction has taken place to form the resulting product. The product has been confirmed to be C3S by XRD, SEM and 29Si MAS NMR, as well as free lime content of the product which is less than 0.2% was determined by propanetriol-ethanol-method. The analysis determined by EDXA has indicated that the n（Ca）/n（Si） ratio in corresponding to micro-region is close to theoretical value of 3∶1. This resulting product is C3S with Si sites of Q0 polymerization, and has higher purity and hydraulic activities at earlier age of hydration.

关键词： sol-gel technique synthesization purity tricalcium silicate morphology 29Si MAS NMR

LATTICE DEFORMATION AND PHASE TRANSFORMATION FROM NANO-SCALE ANATASE TO NANO-SCALE RUTILE TiO_2 PREPARED BY A sol-gel technique

在线全文

学校读者我要写书评

暂无评论

China Particuology 2004年第3期2卷 119-123页

作者： YanqunShao DianTang JinghuaSun YekunLee WeihaoXiong StateKeyLaboratoryofDie&MouldTechnology HuazhongUniversityofScienceandTechnologyWuhan430074P.R.China InstituteforMaterialsResearch FuzhouUniversityFuzhou350002P.R.China MaterialsResearchCenter UniversityofMissouri-RollaMissouriRollaMO65401USA

Nano-scale rutile phase was transformed from nano-scale anatase upon heating, which was prepared by a sol-gel technique. The XRD data corresponding to the anatase and rutile phases were analyzed and the grain sizes of as-derived phases were calculated by Sherrer equation. The lattice parameters of the as-derived anatase and rutile unit cells were calculated and compared with those of standard lattice parameters on PDF cards. It was shown that the smaller the grain sizes, the larger the lattice deformation. The lattice parameter a has the negative deviation from the standard and the lattice parameter c has the positive deviation for both phases. The particles sizes had preferential in-fluence on the longer parameter between the lattice parameters of a and c. With increasing temperatures, the lattice parameters of a and c in both phases approached to the equilibrium state. The larger lattice deformation facilitated the nucleation process, which lowered the transformation temperature. During the transformation from nano-scale anatase to rutile, besides the mechanism involving retention of the {112} pseudo-close-packed planes of oxygen in anatase as the {100} pseudo-close-packed planes in rutile, the new phase occurred by relaxation of lattice deformation and adjustment of the atomic sites in parent phase. The orientation relationships were suggested to be anatase {101}//rutile {101} and anatase //rutile, and the habit plane was anatase (101).

关键词： nano-scale materials anatase rutile phase transformation TiO2 sol-gel technique

Synthesis and characterization of Nd^(3+)-doped Ce_(0.6)Zr_(0.4)O_(2) and its doping significance on oxygen storage capacity

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第1期40卷 231-236页

作者： Natesan Shanmuga Priya Chandramohan Somayaji S.Kanagaraj Siddaganga Institute of Technology TumkurKarnataka 572103India Indian institute of Technology Guwahati 781039India

Cerium and cerium-based oxides are found to be an important element in three-way catalytic converter(TWC).The effective utilization of TWC is found to be reduced due to thermal loading which results in structural deformation of ceria,Doping Zr^(4+)into the rare earth element can increase the oxygen storage capacity and thermal ***,an attempt was made to study the oxygen storage capacity and thermal stability of ceria by doping Zr^(4+)and Nd^(3+).Cerium-based nanocrystallite in the composition of Ce_(0.6)Zr_(0.4-x)Nd_(1.3)xO_(2)(0≤x≤0.4)was prepared by sol-gel synthesize technique with citric acid as a gel-forming agent.X-ray diffraction(XRD)result shows that doping Nd^(3+)into ceria lattice forms homogenous solid solution of cubic fluorite structure up to 25%of substitute *** higher amount of Nd^(3+)into ceria lattice leads to the formation of Nd_(2)O_(3).Raman spectrum study confirms that oxygen storage capacity band is present in Ce_(0.6)Zr_(0.4)O2 and Ce_(0.6)Zr_(0.3)Nd_(0.13)O_(2).The oxygen storage capacity was calculated through weight loss of the sample during the second heating cycle with cyclic heating from30 to 800℃in thermogravimetric analysis(TGA).The TGA study reveals that the oxygen storage capacity of Ce_(0.6)Zr_(0.4)O2 decreases after the substitution of Nd^(3+),which is due to the larger ionic radius of Nd^(3+)compared with that of Zr4+and CeO2.

关键词： Cerium oxide sol-gel technique Thermogravimetric analysis Ionic radius Homogeneous solid solution Oxygen storage capacity

Preparation and application of highly porous aerogel-based bioactive materials in dentistry

在线全文

学校读者我要写书评

暂无评论

Frontiers of Materials Science 2014年第1期8卷 46-52页

作者： Andrea KUTTOR Melinda SZALOKI TLinde RENTE Farkas KERENYI Jozsef BAKO Istvan FABIAN Istvan LAZAR Attila JENEI Csaba HEGEDUES Department of Prosthetic Dentistry and Biomaterials Faculty of Dentistry University of Debrecen 4012 Debrecen Hungary Aerogel Research Group Department of Inorganic and Analytical Chemistry Faculty of Science University of Debrecen 4010 Debrecen Hungary Department of Dental Biochemistry Faculty of Dentistry University of Debrecen 4012 Debrecen Hungary Department of Biophysics and Cell Biology Faculty of Medicine University of Debrecen 4012 Debrecen Hungary

In this study, the possibility of preparation and application of highly porous silica aerogel-based bioactive materials are presented. The aerogel was combined with hydroxyapatite and *** phosphate as bioactive and osteoinductive agents. The porosity of aerogels was in themesoporous region with a maximum pore diameter of 7,4 and 12.7 nm for the composite materials. The newly developed bioactive materials were characterized by scant electron microscopy. The in vitro biological effect of these modified surfaces was also tested on SAOS-2 osteogenic sarcoma cells by confocal laser scanning microscopy.

关键词： aerogel sol-gel technique bioactive matedal SAOS-2 cell

Abrupt change of dielectric properties in mullite due to titanium and strontium incorporation by sol-gel method

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2014年第4期3卷 278-286页

作者： Biplab Kumar PAUL Kumaresh HALDAR Debasis ROY Biswajoy BAGCHI Alakananda BHATTACHARYA Sukhen DAS Physics Department Jadavpur UniversityKolkata-700032India

Highly crystallized mullite has been achieved at temperatures of 1100℃and 1400℃by sol-gel technique in presence of titanium and strontium ions of different concentrations:G_(0)=0 M,G_(1)=0.002 M,G_(2)=0.01 M,G_(3)=0.02 M,G_(4)=0.1 M,G_(5)=0.2 M and G6=0.5 M.X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),field emission scanning electron microscopy(FESEM),LCR meter characterized the *** formation was found to depend on the concentration of the *** dielectric properties(dielectric constant,loss tangent and AC conductivity)of the composites have been measured,and their variation with increasing frequency and concentration of the doped metals was *** the experiments were performed at room *** composites showed maximum dielectric constants of 24.42 and 37.6 at 1400℃of 0.01 M concentration for titanium and strontium ions at 2 MHz,*** to the perfect nature of the doped mullite,it can be used for the fabrication of high charge storing capacitors and also as ceramic capacitors in the pico range.

关键词： mullite sol-gel technique X-ray diffraction(XRD) dielectric properties field emission scanning electron microscopy(FESEM)

Preparation and properties of SrBi_(2.2) Ta_2O_9 thin film

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University of Technology 2005年第4期12卷 376-379页

作者：王文贾德昌周玉 Department of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China Department

SrBi2.2 Ta2O9（SBT） thin film with thickness of 2μm was successfully prepared by sol-gel method, using strontium acetate semihydrate [Sr（CH3COO）2·1/2H2O] and bismth subnitrate [BiO（NO3）], and tantalum ethoxide [Ta（OCH2CH3）5] as source materials, glacial acetic and ethylene glycol as solvents. The X-ray diffraction（XRD） and transmission electron microscope（TEM） results indicate that SBT layer-perovskite phase obtained has to be single phase, SBT thin film is formed after being annealed at 800℃ for 1min. The typical hysteresis loop of SBT thin film on Pt/Ti/SiO2/Si is obtained, and the measured polarization value of the SBT thin film is 4.2μC/cm2.

关键词： SrBi2.2 Ta2O9 sol-gel technique thin film ferroelectric

Structural,magnetic,and acidic properties of cobalt ferrite nanoparticles synthesised by wet chemical methods

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2015年第3期4卷 199-205页

作者： Manju KURIAN Smitha THANKACHAN Divya S.NAIR Aswathy E.K. Aswathy BABU Arathy THOMAS Binu KRISHNA K.T. Department of Chemistry Mar Athanasius CollegeKothamangalam-686666India Department of Physics Mar Athanasius CollegeKothamangalam-686666India

A detailed investigation on the effect of preparation method on the structural,magnetic,and acidic properties of cobalt ferrite nanoparticles prepared by sol-gel and co-precipitation is *** acid and ethylene glycol were used as gelling agents,while sodium hydroxide and aqueous ammonia were used as precipitating *** resulting ferrites were calcined at 450℃ and 750℃.Sharper X-ray diffraction(XRD)peaks were observed for the samples calcined at 750℃,indicating greater crystallinity of the samples calcined at higher *** crystallite sizes fell in the ranges of 7.1-21.1 nm and 30.4-42.1 nm for the samples calcined at 450℃ and 750℃,*** infrared spectra revealed two main absorption bands,the high frequency bandν1 around 600 cm^(-1) and the low frequency bandν2 around 400 cm^(-1) arising from stretching vibrations of the oxygen bond with the metal in the tetrahedral(A)and octahedral(B)sites in the spinel *** of particles was observed in the scanning electron microscopy(SEM)*** parameters of CoFe_(2)O_(4) nanoparticles greatly depended on calcination temperature and preparation *** temperature programmed desorption(TPD)measurements indicated that weak acid sites predominate medium strength sites,while the number of strong acid sites is the *** acidity decreased for the samples calcined at higher *** results underline the effect of preparation conditions on the morphology,crystallite size,and magnetic properties of nano ferrites.

关键词： nano ferrites sol-gel technique co-precipitation magnetic property surface acidity

LiY_(1-x)Eu_x(MoO_4)_2 as a promising red-emitting phosphor of WLEDs synthesized by sol-gel process

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Rare Earths 2012年第4期30卷 315-319页

作者：周贤菊周桐辉李英茂冯乔春 Department of Mathematics and Physics Chongqing University of Posts and Telecommunications Chongqing Zhongtian Chemical In-dustry Co.Ltd.

A series of LiY1-xEux（MoO4）2 red-emitting phosphors were synthesized by sol-gel technique. The phase impurity and spectroscopic properties were characterized by X-ray diffraction （XRD） and photo-luminescence （PL） spectra respectively. The effect of Eu3＋ doping concentration, annealing temperature and the molar ratio of citric acid to the total metal cations （C：M） on the optical properties of the red phosphors were studied and optimized. It was found that all the samples could be excited efficiently by blue light （465 nm）, which was well coincident with the emission of GaN based LED chips. The luminescent intensity reached maximum when annealing temperature was 750 ℃ and Eu3＋ doping concentration was 5% with C：M=3：1.

关键词： LiY1-xEux(MoO4)2 red phosphor white LEDs sol-gel technique rare earths

Optical and Magnetic Properties of Fe_2O_3/SiO_2 Nano-composite Films

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2010年第2期25卷 206-209页

作者：关飞飞姚兰芳 College of Science University of Shanghai for Science and Technology

Fe2O3/SiO2 nano-composite films were prepared by sol-gel technique combining heat treatment in the range of 100-900 ℃. The particle size was observed by FE-SEM. Optical properties of the films were investigated by UV-visible spectra. Structural and magnetic characteristics were investigated through FT-IR and VSM. The transparency of the Fe2O3/SiO2 nano-composite films decreased with the content of the Fe2O3. Water and organic solvent in the films were evaporated with heat treatment, so the transparency of the films was enhanced under high temperature. It is also found that the saturation magnetization （Ms） of the films increases with the temperature. As the content of the Fe2O3 increases, when the content of the Fe2O3 is around 30wt%, the Ms of the films has a maximum value.

关键词： sol-gel technique Fe2O3/SiO2 nano-composite films magnetism