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1.
J. del Castillo A. C. Yanes J. Méndez-Ramos J. J. Velázquez V. D. Rodríguez 《Journal of Sol-Gel Science and Technology》2011,60(2):170-176
Sol–gel derived glass–ceramics containing CeF3 nanocrystals have been developed for the first time, to the best of our knowledge, by adequate heat treatments of precursor
bulk glasses with composition 95SiO2–5CeF3 doped with 0.1 Eu3+ or 0.1 Sm3+ and co-doped with 0.3 Yb3+ and 0.1 Er3+ ions (in mol%). X-Ray Diffraction and High Resolution Transmission Electron Microscopy confirm the precipitation of CeF3 nanocrystals. Moreover, this structural analysis is completed using Eu3+ and Sm3+ as probe ions of the different local environments for rare-earth ions in the nano-structured glass–ceramics. Luminescence
measurements led us to discern the final environments for the ions, revealing the partition of a large fraction of these ions
into like-crystalline environment of the precipitated CeF3 nanocrystals. Near infrared emission at 1.5 μm was observed after excitation at 980 nm in Yb3+–Er3+ co-doped samples for potential applications in telecommunications. 相似文献
2.
Mălina Răileanu Maria Crişan Nicolae Drăgan Dorel Crişan Anouk Galtayries Ana Brăileanu Adelina Ianculescu Valentin S. Teodorescu Ines Niţoi Mihai Anastasescu 《Journal of Sol-Gel Science and Technology》2009,51(3):315-329
Among the great number of sol–gel prepared nanomaterials, TiO2 has attracted significant interest due to its high photocatalytic activity, excellent functionality, thermal stability and
non-toxicity. The photocatalytic degradation of pollutants using un-doped and doped TiO2 nanopowders or thin films is very attractive for applications in environmental protection, as a possible solution for water
purification. The present work describes a comparative structural and chemical study of un-doped TiO2 and the corresponding S- and Ag-doped materials. The photocatalytic activity was established by testing the degradation of
organic chloride compounds from aqueous solutions. Sol–gel Ag-doped TiO2 coatings, prepared by co-gelation and sol–gel Ag-doped TiO2 coatings obtained from nanopowders were also compared. Their structural evolution and crystallization behaviour (lattice
parameters, crystallite sizes, internal strains) with thermal treatment were followed by thermal analysis, X-ray diffraction,
transmission electron microscopy, atomic force microscopy and specific surface areas measurements. X-ray photoelectron spectroscopy
analyses were performed to characterize the surface composition and S or Ag speciation, which was used to interpret the catalytic
data. 相似文献
3.
V. Ya. Kavun N. F. Uvarov A. B. Slobodyuk A. S. Ulikhin I. A. Telin V. K. Goncharuk 《Russian Journal of Electrochemistry》2017,53(8):884-892
Ionic mobility and electrical conductivity of solid solutions with fluorite structure, obtained with solid-state approach in PbF2–SbF3 and PbF2–SnF2–SbF3 systems, are studied by 19F NMR and electrochemical impedance spectroscopy methods. The 19F NMR spectra parameters, types of ion motions in the fluoride sublattice, and the ionic conductivity magnitude are shown to be determined by the temperature and fluoride concentration in the solid solutions. The solid solution specific conductivity in the PbF2–SbF3 and PbF2–SnF2–SbF3 systems at 420–450 K is as high as ~10–2 S/cm, which allows accounting the solid solutions as a base for preparation of functional materials. 相似文献
4.
Thomas Hübert Brita Unger Michael Bücker 《Journal of Sol-Gel Science and Technology》2010,53(2):384-389
The sol–gel process was applied to enhance properties of pine sapwood. For this purpose wood prisms were soaked in nanoscaled
precursor solutions prepared from titanium(IV) n-butoxide and titanium(IV) iso-propoxide, respectively, using vacuum impregnation technique. The wet composites were cured
by special program with final heat treatment at 103 °C. Weight percent gains (WPG) of the wood specimen in the range of 19–25%
were obtained due to these procedures. SEM investigations show that precursor solutions penetrate into the whole wood body
and the titania formed after heat treatment in the composites is deposited in the pores (lumen) and partly in the cell walls
of the wooden matrix. The moisture sorption was investigated in long term tests for a period of some months by storage at
20–23 °C in humid air (relative humidity of 99%) and ambient atmosphere (relative humidity 40–60%), respectively. For untreated
reference samples the moisture sorption results in increasing of mass and volume according to saturation values of 24 and
13%, respectively, after about 15 days. The incorporation of titania reduces the saturation values of the moisture sorption
by up to 12% in mass and by up to 5% in volume at a relative humidity of 99%. Thus, an enhancement of the dimensional stability
of about 60% is obtained at best. The results demonstrate that modification of wood with sol–gel derived precursors can enhance
its dimensional stability, which prevents the formation of cracks. Because of that reduced moisture sorption biological attacks
should be delimited. Additionally, thermal analyses show a retarded combustion of the wood matrix due to titania infiltration. 相似文献
5.
M. G. B. Nunes L. S. Cavalcante V. Santos J. C. Sczancoski M. R. M. C. Santos L. S. Santos-Júnior E. Longo 《Journal of Sol-Gel Science and Technology》2008,47(1):38-43
Undoped x · α-Fe2O3
y · CeO2 and doped with praseodymium ceramic pigments were obtained by the sol–gel method after heat treatment at 800 °C for 2 h.
These pigments were characterized by XRD, nitrogen adsorption, scanning electron microscopy, ultraviolet-visible absorption
spectroscopy and colorimetrical measurements. Red and brown colors with several tonalities were observed after changes with
Ce and Pr concentration. 相似文献
6.
Titania was prepared by the sol–gel method from titanium isopropoxide with ultrasound influence (USI) by different pH (acetic
acid (AA) or diethyl amine (DEA). Samples were represented in powder and films forms. The TiO2 was characterized by X-ray diffraction (XRD), FTIR. XRD shows that TiO2 prepared with diethyl amine has only the anatase phase, however the samples prepared with acetic acid–anatase and rutile
phases both could be detected. Ultrasound influence increases the anatase content in comparison with its missing. Photo electromotive
force (Photo EMF) datas of TiO2 films were received in a three-electrode wet cell. It was found that the photo activity depended on the conditions of synthesis
crystalline phases. Photo EMF for the TiO2 films on the nickel electrode is 1.5 mV (TiO2 with acetic acid conditions), 6.8 mV (TiO2 with diethyl amine conditions) 8.0 mV (TiO2 with acetic acid + USI conditions), 22.0 mV (TiO2 with diethyl amine +USI conditions). 相似文献
7.
Al2O3–TiO2 nanocrystalline powders were synthesized by sol–gel process. Aluminum sec-butoxide and titanium isopropoxide chemicals were
used as precursors and ethyl acetoacetate was used as chelating agent. Thermal and crystallization behaviors of the precursor
powders were investigated by thermal gravimetric-differential thermal analysis, Fourier-transform infrared spectrum and X-ray
diffraction. The average crystalline size of heat treated Al2O3–TiO2 powders at 1,100 °C is ~100 nm. 相似文献
8.
In this work we prepared the hybrid material (SG) by the sol–gel method through the reaction between tetraethylortosilicate
(TEOS) and acetylacetonatepropyltrimethoxysilane (ACACSIL). We also immobilized the acetylacetonate on silica surface (GR)
by the grafting method through the reaction between a commercial silica and ACACSIL. Infrared thermal analysis showed that
these materials were thermally stable until 200 °C. SG is a microporous material and has surface area of 500 m2 g−1, average porous volume of 0.09 cm3 g−1 and organic content of 1 mmol g−1. GR is a mesoporous material and has surface area of 300 m2 g−1, average porous volume of 0.7 cm3 g−1 and organic content of 0.4 mmol g−1. Iron(III) was coordinated to SG and GR resulting in the SG–Fe and GR–Fe silicas which were tested as catalysts on the aerobic
epoxidation of cis-cyclooctene. SG–Fe yielded 100% of conversion and 94% of selectivity in epoxide whereas GR–Fe silica led
to a maximum conversion of 50% and 100% of selectivity. 相似文献
9.
P. P. Fedorov V. K. Goncharuk I. G. Maslennikova I. A. Telin T. Yu. Glazunova 《Russian Journal of Inorganic Chemistry》2016,61(2):239-242
A phase diagram of the PbF2–SnF2 system has been studied by differential thermal analysis and X-ray powder diffraction. The system forms Pb1–хSnхF2 (х ≤ 0.33) solid solution and three compounds. Pb2SnF6 decomposes in solid state by a peritectoid reaction at 350°С; Pb3Sn2F10 and PbSnF4 melt by peritectic reactions at 565 and 380°С, respectively. The eutectic coordinates are 180°С, 90 mol % SnF2. 相似文献
10.
α-Fe2O3 films as inorganic red color filter were synthesized through a simple procedure, epoxide assisted sol–gel route. The sol
was prepared through reaction of FeCl2 in boiling ethanol solution with propylene oxide. The films were formed by the dip-coating of sol on substrate, drying and
the following annealing steps. The obtained α-Fe2O3 films were composed of homogeneous distributed α-Fe2O3 nanoparticles with size of 30–50 nm. The film shows strong absorption to the light below 600 nm and high transparency to
the red light (87% at 630 nm). As inorganic red color filter, the optic behavior of this film is nearly as same as the organic
color filter made of dye. 相似文献
11.
Z. Zhuang X. P. Wang A. H. Sun Y. Li Q. F. Fang 《Journal of Sol-Gel Science and Technology》2008,48(3):315-321
La2Mo2O9 films were successfully synthesized on silicon (100) and poly-alumina substrates via modified sol–gel method with inorganic
salts of La(NO3)3 and (NH4)6Mo7O24 as precursors. Pure La2Mo2O9 phase was confirmed by XRD if the annealing temperature was higher than 500 °C. Energy dispersive spectrometry (EDS) of TEM
revealed that the molar ratio of La to Mo was nearly 1:1. Field-emission SEM characterization showed that the films were dense,
crack-free and uniform. The grain size of the films ranged from 30 to 400 nm depending upon the calcination temperature and
duration time. The roughness calculated from AFM topography varied in the range between 10 and 35 nm. The thickness of the
films was more than 200 nm for single-layered films. The electrical conductivity of the films reaches 0.06 S/cm at 600 °C
that was almost more than one order of magnitude higher than that of the corresponding bulk material. 相似文献
12.
M. Kamal I. K. Battisha M. A. Salem A. M. S. El Nahrawy 《Journal of Sol-Gel Science and Technology》2011,58(2):507-517
A sol–gel process for producing monolithic silica–phosphate (SiO2–P2O5) system different concentrations of P2O5, starting with tetra-ethoxysilane TEOS, and triethyl-phosphate as sources of SiO2 and P2O5 was performed. The gels were heat-treated at temperatures ranging from 100 up to 900 °C. The structural and chemical analyses
of the samples were determined by using X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). It was
found from the XRD that the existence of phosphorus enhances the crystallization of silica gel, while the FTIR indicated the
main functional groups of silica–phosphate. It is important to study the effect of hydroxyl in silica–phosphate glass. The
results obtained are promising to use the prepared samples in a variety of applications, ranging from traditional application
such as lighting products) to the modern application (such as optical fibers. Optical studies were measured by using the spectrophotometer
in wavelength range 0.2–2.5 μm. The refractive index (n) was calculated for the prepared samples, it was found to be strongly affected by structural rearrangement resulting from
the elimination of the solvent and the Si–OH, Si–O–Si and Si–O–OH bonding by phosphate and aluminum and it increases by increasing
phosphate concentrations. The weight losses have investigated for prepared samples. 相似文献
13.
Aiju Zhang Zhihong Li Zicheng Li Yumei Zhu 《Journal of Sol-Gel Science and Technology》2009,49(1):6-11
SiO2–Al2O3–Na2O glass coated cubic boron nitride (cBN) abrasive particles were prepared by sol–gel technique. The results indicated that
SiO2–Al2O3–Na2O glass was excellent material for oxidation protection of cBN abrasive grains because coefficient of thermal expansion of
this glass closely matched that of cBN materials. The single particle compressive strength and impact toughness of this glass
coated cBN abrasive particles were significantly increased. For the application of glass coated cBN abrasives to vitrified
grinding wheels, it was evident that the glass coating provided high bonding strength between cBN abrasive grains and vitrified
bond system. 相似文献
14.
A. K. Vasilevskaya O. V. Almjasheva V. V. Gusarov 《Russian Journal of General Chemistry》2015,85(12):2673-2676
Formation of zirconia nanocrystals in the course of thermal treatment of an X-ray amorphous zirconium oxyhydroxide was studied. It was shown that the formation of tetragonal and monoclinic polymorphs of ZrO2 in the temperature range from 500 to 700°C occurs owing to dehydration and crystallization of amorphous hydroxide. An increase of the temperature up to 800°C and higher activates mass transfer processes and, as a result, activates the nanoparticle growth and increases the fraction of the phase based on monoclinic modification of ZrO2 due to mass transfer from the nanoparticles with the non-equilibrium tetragonal structure. Herewith, formed ZrO2 nanocrystals with monoclinic structure have a broad size distribution of crystallites, and the average crystallite size after thermal treatment at 1200°C for 20 min is about 42 nm. 相似文献
15.
Xi Sun Jingtao Ma Xiaotong Chen Ziqiang Li Changsheng Deng Bing Liu 《Journal of Sol-Gel Science and Technology》2018,85(2):431-435
ZrC–ZrO2 composite ceramic microspheres were prepared by internal gelation combined with carbothermic reduction using fructose as a chelating agent and carbon source. Fructose in the precursor solution formed complex with zirconium ions, which was conducive to the refining of the microstructure of the sintered composite. ZrC–ZrO2 composite with ZrC content as high as 60?wt% could be prepared. 相似文献
16.
Wang Shu-Yu He Wen-Zhi Liu Chang Li Guang-Ming Zhang Fei-Er 《Research on Chemical Intermediates》2016,42(5):4135-4145
Magnesium hydroxide [Mg(OH)2] nanocrystals with excellent dispersity and good crystallinity were efficiently synthesized through the ultrasonic and hydrothermal synergetic effect. The morphology, structure, and thermochemistry of Mg(OH)2 nanocrystals were researched by TEM, XRD, FT-IR, and DTA, respectively. The mechanism of ultrasonic–hydrothermal synergistic effect was discussed. In addition, Mg(OH)2 nanocrystals were added into polypropylene (PP) to form composite materials, and the mechanical properties of Mg(OH)2–PP composites were investigated. Compared with the other two Mg(OH)2 PP composites, the Mg(OH)2–PP composite had the best mechanical property when the Mg(OH)2 was synthesized by ultrasonic–hydrothermal route. 相似文献
17.
18.
Quan Chen Chris Boothroyd Andrew Mcintosh Soutar Xian Ting Zeng 《Journal of Sol-Gel Science and Technology》2010,53(1):115-120
The surface of commercial titania particles was coated by a layer of silica by a two-step process which involved a power ultrasound initiated sol–gel reaction. In the first step of this solution process, aminosilane, i.e. organosilane with amino functional group, was used to modify the surface of pristine nanoparticles. Subsequent silica nanocoating was initiated and sustained under power ultrasound agitation in a mixture of surface modified particles and epoxysilane. As a result, a homogenous coverage of silica on the nanoparticles’ surface, with thickness controllable from one to several nanometers, was obtained. Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and particle surface zeta potential measurements were employed to follow steps in the process and to confirm the reaction mechanism. 相似文献
19.
Fredrik Söderlind Linnéa Selegård Per Nordblad Kajsa Uvdal Per-Olov Käll 《Journal of Sol-Gel Science and Technology》2009,49(2):253-259
Thin films of the perovskite and garnet structured gadolinium ferrites GdFeO3 and Gd3Fe5O12 have been synthesized by a sol–gel method, based on stoichiometric mixtures of acetyl acetone chelated Gd3+ and Fe3+ dissolved in 2-methoxy ethanol. After spin coating onto Si wafers, and heating in air at 700 °C for 20 h, neatly grown essentially
single phase films were obtained. From X-ray photoelectron spectroscopy an iron deficiency is observed in the uppermost layer
of both films, implying that the crystallites preferably end in planes rich in Gd and O but not in Fe. The films were also
characterized by X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, and magnetic measurements. 相似文献
20.
Petr Brázda Daniel Nižňanský Jean-Luc Rehspringer Jana Poltierová Vejpravová 《Journal of Sol-Gel Science and Technology》2009,51(1):78-83
ε-Fe2O3/SiO2 nanocomposite was prepared by novel solgel method using single precursor for both nanoparticles and matrix. This method allows to prepare the samples free of α-Fe2O3 with 40% of Fe2O3 in SiO2. Nanoparticles of 12 nm diameter were obtained by annealing at 1,000 °C. The samples were characterized by powder X-ray diffraction and transmission electron microscopy. Mössbauer spectroscopy identified ε-Fe2O3 as the only magnetically ordered phase at room temperature. Magnetic measurements revealed progressive necking of hysteresis loops measured at 300 and 2 K. In both cases the intrinsic coercivity reaches only 0.25 T. Measurements up to 14 T shows monotonous decreasing trend of saturated magnetization with increasing temperature. 相似文献