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Anatase TiO2 (anatase + tio2)
Terms modified by Anatase TiO2 Selected AbstractsLow-Temperature Preparation and Magnetic Properties of Nanoparticle Iron-Doped Anatase TiO2JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2007Khaled Melghit Nanoparticle iron (Fe)-doped anatase TiO2 was prepared at a low temperature (100°C) and at room pressure. The product was obtained from a boiling solution of an amorphous TiO2 gel mixed with an iron nitrate solution and stirred for 5 h. An amorphous TiO2 gel was obtained from TiCl3 solution and NH4OH as a precipitating agent stirred at room temperature for 1 day. EDAX results on different selected areas of as-prepared Fe-doped anatase TiO2 revealed a homogeneous composition of 17 at.% Fe. Fe,TiO2 has a superparamagnetic state with a possibility of antiferromagnetism at low temperatures. Fe seems to substitute titanium ions without any evidence of other impurities such as Fe nanoclusters or Fe-based oxides. [source] Anatase Titanium Dioxide Crystallization by a Hydrolysis Reaction of Titanium Alkoxide without AnnealingJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2006Kunio Funakoshi The crystallization of anatase titanium dioxide (TiO2) was achieved by a hydrolysis reaction of titanium alkoxide without annealing. The hydrolysis reaction rates of tetraethyl orthotitanate were indicated by a function of the concentration of acetylacetone added. The degree of crystallinity of the product particles was influenced by the amounts of acetylacetone and seed crystals. Anatase TiO2 was crystallized by restraining the rapid increase in supersaturation of TiO2 and the consequent nucleation of amorphous TiO2. The degree of crystallinity of the product particles also changed with the types of seed crystals used, and was strongly influenced by the specific surface areas of the seed crystals. [source] Atmospheric Cold Plasmas for Synthesizing Nanocrystalline Anatase TiO2 using Dielectric Barrier DischargesPLASMA PROCESSES AND POLYMERS, Issue 5 2007Long-Hui Nie Abstract Nanocrystalline anatase TiO2 has been successfully synthesized using TiCl4 and O2 as precursors by atmospheric cold plasmas generated by dielectric barrier discharges (DBD) without extra heating or thermal treatment. For the TiO2 powders synthesized by DBD plasma at an energy density of 5.9 kJ,·,L,1, XRD and TEM analyses revealed that the nanocrystallite size is about 10,15 nm. Only a single crystalline structure of anatase was observed performing XRD, HRTEM and SAED measurements. It was found that the particle size decreased with increasing the discharge power, and that the chlorine contamination dramatically decreased when using high discharge power levels. [source] Photocatalytic Activity and Electronic Structure Analysis of N-doped Anatase TiO2: A Combined Experimental and Theoretical StudyCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2009H. Gao Abstract N-Doped TiO2 photocatalysts were prepared by a hydrothermal method with tetra- n -butyl titanate (TTNB) and triethanolamine as precursors. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-visible diffuse reflectance spectra (DRS), respectively. Photocatalytic activities of the anatase products were investigated on the degradation of methyl orange (MO). The incorporation of nitrogen impurity in anatase TiO2 was studied by the first-principles calculations based on the density functional theory (DFT). The calculated electronic band structures for substitutional and interstitial N-doped TiO2 indicated the formation of localized states in the band gap, which lied above the valence band. Excitation from the impurity states of N 2p to the conduction band could account for the optical absorption edge shift toward the lower energies. It was consistent with the experimentally observed absorption of N-doped samples in the visible region. [source] Syntheses, Li Insertion, and Photoactivity of Mesoporous Crystalline TiO2ADVANCED FUNCTIONAL MATERIALS, Issue 17 2009Wenbo Yue Abstract Ordered mesoporous rutile and anatase TiO2 samples are prepared using mesoporous silica SBA-15 as template and freshly synthesized titanium nitrate and titanium chloride solutions as precursors. The rutile material formed from the nitrate solution is monocrystalline and contains minimal amounts of Si with a Si:Ti ratio of 0.031(4), whereas the anatase material formed from the chloride solution comprises nanocrystals and contains a higher content of Si with a Si:Ti ratio of 0.18(3). It is found that control of temperature and selection of Ti-containing precursor play important roles in determining the crystal phase and crystallinity. A possible formation mechanism of porous crystalline TiO2 is suggested. Characterization of these porous materials is performed by XRD, HRTEM, and nitrogen adsorption/desorption. SBA-15-templated mesoporous rutile TiO2 exhibits a higher Li ion insertion capability than KIT-6-templated TiO2 due to its larger surface area. Likewise mesoporous anatase TiO2:SiO2 composite has a better photoactivity than bulk TiO2 or TiO2 -loaded SBA-15 for bleaching methylene blue. [source] Effect of Nano-Packing on Preservation Quality of Fresh Strawberry (Fragaria ananassa,Duch. cv Fengxiang) during Storage at 4 °CJOURNAL OF FOOD SCIENCE, Issue 3 2010F.M. Yang ABSTRACT:, A novel nano-packing material with lower relative humidity, oxygen transmission rate and high longitudinal strength was synthesized by blending polyethylene with nano-powder (nano-Ag, kaolin, anatase TiO2, rutile TiO2), and its effect on preservation quality of strawberry fruits (Fragaria ananassa,Duch. cv Fengxiang) was investigated during storage at 4 °C. Results showed that nano-packaging was able to maintain the sensory, physicochemical, and physiological quality of strawberry fruits at a higher level compared with the normal packing (polyethylene bags). After a 12-d storage, decreases in the contents of total soluble solids, titratable acidity, and ascorbic acid of nano-packing were significantly inhibited. Meanwhile, decay rate, anthocyanin, and malondialdehyde contents were decreased to 16.7%, 26.3 mg/100g, 66.3 ,mol/g for nano-packing and 26.8%, 31.9 mg/100g, 75.4 ,mol/g for normal packing; polyphenoloxidase (PPO) and pyrogallol peroxidase (POD) activities were significantly lower in nano-packing than the control. These data indicated that the nano-packaging might provide an attractive alternative to improve preservation quality of the strawberry fruits during extended storage. Practical Application: Nano-packing exhibited identified quality benefits applicable to the preservation of fresh strawberry. Furthermore, nano-packing has the advantages of simple processing and feasibility to be industrialized in contrast with other storages. Thus, the utilization of nano-packing will likely assist commercial producers and retailers in extending the shelf life of products over a broader range in the future. [source] Low-Temperature Preparation and Magnetic Properties of Nanoparticle Iron-Doped Anatase TiO2JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2007Khaled Melghit Nanoparticle iron (Fe)-doped anatase TiO2 was prepared at a low temperature (100°C) and at room pressure. The product was obtained from a boiling solution of an amorphous TiO2 gel mixed with an iron nitrate solution and stirred for 5 h. An amorphous TiO2 gel was obtained from TiCl3 solution and NH4OH as a precipitating agent stirred at room temperature for 1 day. EDAX results on different selected areas of as-prepared Fe-doped anatase TiO2 revealed a homogeneous composition of 17 at.% Fe. Fe,TiO2 has a superparamagnetic state with a possibility of antiferromagnetism at low temperatures. Fe seems to substitute titanium ions without any evidence of other impurities such as Fe nanoclusters or Fe-based oxides. [source] Ammonium oxotrifluorotitanate: morphology control and conversion to anatase TiO2PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2008Lei Zhou Abstract Uniform ammonium oxotrifluorotitanate (NH4TiOF3) mesocrystals were synthesized from an aqueous solution containing (NH4)2TiF6 and H3BO3 in presence of nonionic surfactant. Effects of various reaction conditions on the morphology of the NH4TiOF3 mesocrystals were examined by electron microscopy techniques. Results indicate that static solution, high surfactant concentration and low reaction temperature enhance the formation of uniform NH4TiOF3 mesocrystals with regular shapes. By sintering in atmosphere, the NH4TiOF3 mesocrystals were converted to anatase TiO2, which retain the original shapes of the NH4TiOF3 precursor due to similarities on their atom structures. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Strong anharmonicity and phonon confinement on the lowest-frequency Raman mode of nanocrystalline anatase TiO2PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2007Kun Gao Abstract We calculated and analyzed the effects of temperature and crystallite size on the Raman properties of nanocrystalline anatase TiO2 by using the related models mentioned previously [Tang and Herman, Phys. Rev. B 43, 2299 (1991); Richter et al., Solid State Commun. 39, 625 (1981)]. The temperature dependence of the Raman spectra of two different crystallite sizes of anatase TiO2 were obtained. Careful measurements of the frequency shifts of Raman modes were carried out at different temperatures. Through fitting the experimental data, pure-volume and the pure-temperature contributions to the frequency shifts of the lowest- and highest-frequency Eg modes, respectively, have been calculated. The results indicated that strongly intrinsic anharmonicity arising from optical-phonon couplings was the origin of hardening upon increasing temperature for the lowest-frequency Raman mode. The phonon-confinement effect on this mode was analyzed and anharmonic shifts of optical phonons with two different kinds of crystallite sizes were also compared. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Atmospheric Cold Plasmas for Synthesizing Nanocrystalline Anatase TiO2 using Dielectric Barrier DischargesPLASMA PROCESSES AND POLYMERS, Issue 5 2007Long-Hui Nie Abstract Nanocrystalline anatase TiO2 has been successfully synthesized using TiCl4 and O2 as precursors by atmospheric cold plasmas generated by dielectric barrier discharges (DBD) without extra heating or thermal treatment. For the TiO2 powders synthesized by DBD plasma at an energy density of 5.9 kJ,·,L,1, XRD and TEM analyses revealed that the nanocrystallite size is about 10,15 nm. Only a single crystalline structure of anatase was observed performing XRD, HRTEM and SAED measurements. It was found that the particle size decreased with increasing the discharge power, and that the chlorine contamination dramatically decreased when using high discharge power levels. [source] Photocatalytic Activity and Electronic Structure Analysis of N-doped Anatase TiO2: A Combined Experimental and Theoretical StudyCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 6 2009H. Gao Abstract N-Doped TiO2 photocatalysts were prepared by a hydrothermal method with tetra- n -butyl titanate (TTNB) and triethanolamine as precursors. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-visible diffuse reflectance spectra (DRS), respectively. Photocatalytic activities of the anatase products were investigated on the degradation of methyl orange (MO). The incorporation of nitrogen impurity in anatase TiO2 was studied by the first-principles calculations based on the density functional theory (DFT). The calculated electronic band structures for substitutional and interstitial N-doped TiO2 indicated the formation of localized states in the band gap, which lied above the valence band. Excitation from the impurity states of N 2p to the conduction band could account for the optical absorption edge shift toward the lower energies. It was consistent with the experimentally observed absorption of N-doped samples in the visible region. [source] Highly Dispersed Ruthenium Hydroxide Supported on Titanium Oxide Effective for Liquid-Phase Hydrogen-Transfer ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2008Kazuya Yamaguchi Dr. Abstract Supported ruthenium hydroxide catalysts (Ru(OH)x/support) were prepared with three different TiO2 supports (anatase TiO2 (TiO2(A), BET surface area: 316,m2,g,1), anatase TiO2 (TiO2(B), 73,m2,g,1), and rutile TiO2 (TiO2(C), 3.2,m2,g,1)), as well as an Al2O3 support (160,m2,g,1). Characterizations with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), and X-ray absorption fine structure (XAFS) showed the presence of monomeric ruthenium(III) hydroxide and polymeric ruthenium(III) hydroxide species. Judging from the coordination numbers of the nearest-neighbor Ru atoms and the intensities of the ESR signals, the amount of monomeric hydroxide species increased in the order of Ru(OH)x First-principles calculation of electronic structure of V-doped anatase TiO2CHEMPHYSCHEM, Issue 12 2010Run Long Dr. Abstract The energetic and electronic structures of V-doped anatase TiO2 have been investigated systematically by the GGA+U approach, including replacement of Ti by V in the absence and presence of oxygen vacancies and the presence of an interstitial site. It was found that V should exist as a V4+ ion in the replacement of Ti in the anatase lattice, the electron transitions of which to the conduction band from V,3d states are responsible for the experimentally observed visible light absorption. The influence of V dopant concentration on the electronic and magnetic properties is also discussed, such as the influence of the U value in systems containing oxygen vacancies and spin flip phenomena for interstitial V-doping. [source]
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