Evolution of microstructure during the thermal processing of aluminum-modified titania and aluminum/vanadium co-modified titania gels

2004 ◽  
Vol 19 (6) ◽  
pp. 1808-1817 ◽  
Author(s):  
Francis J. Allison ◽  
David M. Grant ◽  
Karen McKinlay ◽  
Philip G. Harrison
Keyword(s):  
High Temperatures ◽  
Anatase Phase ◽  
Sol Gel ◽  
Nominal Composition ◽  
Titanium Chloride ◽  
X Ray ◽  
Transmission Electron ◽  
Aqueous Aluminum ◽  
Evolution Of Microstructure ◽  
Hydrolysis Of

Sol-gel materials of aluminum-modified TiO2 of nominal composition 5.7 wt% and 10.8 wt% aluminum and aluminum/vanadium co-modified TiO2 of nominal composition 5.7Al–3.5V wt% have been prepared by evaporation of aqueous colloidal sols obtained by the hydrolysis of aqueous solutions of titanium chloride with the appropriate amount of vanadyl oxalate and/or aqueous aluminum nitrate using aqueous ammonia followed by peptization of the resulting hydrated solids using nitric acid. The nature of the sol-gel materials and the behavior upon calcination at temperatures up to 1373 K have been investigated using x-ray fluorescence, x-ray powder diffraction, transmission electron microscopy, and electron diffraction. At 333 K, all the gels comprise small (approximately 5 ± 1 nm) particles of anatase together with traces of brookite and highly crystalline ammonium nitrate. The particle size changes little on thermal treatment at 573 K, but increases significantly at higher temperatures and is accompanied by transformation to rutile. Aluminum-modified gels stabilize the anatase phase from 923 K in unmodified TiO2 to 1023 K in the 6Al/TiO2 gel and 1173 K in the 11Al/TiO2 gel. The alumina in the co-modified gel has a dominating effect on stabilizing the anatase phase until 973 K. Only rutile is present at high temperatures, except for small amounts of phase-separated α-Al2O3 (Corundum). No substitutional incorporation of Al3+ ions in the tetragonal rutile lattice occurs at high temperatures.

Evolution of microstructure during the thermal processing of titania and vanadium-modified titania gels

2003 ◽  
Vol 18 (3) ◽  
pp. 594-603 ◽  
Author(s):  
Francis J. Allison ◽  
David M. Grant ◽  
Karen McKinlay ◽  
Craig Bailey ◽  
Philip G. Harrison
Keyword(s):  
High Temperatures ◽  
Sol Gel ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Ft Raman Spectroscopy ◽  
Evolution Of Microstructure ◽  
Hydrolysis Of ◽  
Ft Raman

Sol-gel materials of TiO2 and vanadium-modified TiO2 of nominal composition 4, 8, and 16 wt.% vanadium were prepared by evaporation of aqueous colloidal sols obtained by the hydrolysis of aqueous solutions of titanium(IV) chloride with the appropriate amount of vanadyl oxalate using aqueous ammonia followed by peptization of the resulting hydrated solids using nitric acid. The nature of the sol-gel materials and their behavior on calcinations at temperatures up to 1273 K were investigated using x-ray fluorescence, powder x-ray diffraction, transmission electron microscopy, and electron diffraction and FT-Raman spectroscopy. At 333 K, all the gels comprised small (about 5 ± 1 nm) particles of anatase together with traces of brookite. The particle size changed little on thermal treatment at 573 K, but increased significantly at higher temperatures and was accompanied by transformation to rutile. Incorporation of vanadium in the gels reduced the temperature at which rutile began to appear from 923 K in pure TiO2 to 773 K in the V/TiO2 gels. Only rutile was present at high temperatures, except for the 16 V/TiO2 gel, when small amounts of phase-separated vanadia were also observed. A 2–3% substitutional incorporation of V4+ ions in the tetragonal rutile lattice occurred at high temperatures, but the majority of the vanadium was present in an amorphous, highly dispersed fashion.

Synthesis and Characterization of Organic/Inorganic Interpenetrating Polymer Networks

1995 ◽  
Vol 385 ◽  
Author(s):  
Barry J. Bauer ◽  
Catheryn L. Jackson ◽  
Da-Wei Liu
Keyword(s):  
Sol Gel ◽  
Polymer Networks ◽  
Interpenetrating Polymer Networks ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Pure Phases ◽  
Hydrolysis Of ◽  
Polymerization Conditions

ABSTRACTInterpenetrating polymer networks have been synthesized by performing sol-gel chemistry and conventional organic polymerizations in mixtures of the monomers. The organic polymers were acrylates, and the inorganic phase was SiO2 formed by hydrolysis of orthosilicates. Polymerizations were conducted at a variety of relative rates, and the chemistry was designed to allow different amounts of grafting between the components. The morphology was characterized by transmission electron microscopy and small angle neutron and x-ray scattering. Wide variations in morphology were observed depending on the polymerization conditions, ranging from grossly phase separated to dendritic to finely divided structures (at a 100Å size scale). The phases ranged from mixtures of the two components to relatively pure phases. The interface between the phases ranged from very narrow to relatively broad.

HRTEM Study of nano-TiO2 Powder

2008 ◽  
Vol 59 (4) ◽  
Author(s):  
Ionela Carazeanu Popovici ◽  
Mihai Girtu ◽  
Elisabeta Chirila ◽  
Victor Ciupina ◽  
Gabriel Prodan
Keyword(s):  
Electron Microscopy ◽  
Anatase Phase ◽  
Thermal Hydrolysis ◽  
Tio2 Powder ◽  
X Ray Diffraction ◽  
Nano Tio2 ◽  
X Ray ◽  
Transmission Electron ◽  
Hydrolysis Of ◽  
Photovoltaic Material

Titanium dioxide (TiO2) has been one of the most attractive photo electrochemical and photovoltaic material during the last decades due to its scientific and technological importance. The TiO2 powder was synthesized by thermal hydrolysis of TiCl4. The crystalline structures and morphologies of the powder have been characterized by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The crystals dimensions varied from 15 nm to 23 nm and it have been established that the studied nanopowder is stable in the anatase phase.

Study on the Dispersion of Nanometer TiO2 Powder by Sol-Gel Method

2012 ◽  
Vol 599 ◽  
pp. 104-107
Author(s):  
Fang Zhao ◽  
Ya Qiong Zhao ◽  
Yuan Yuan Li ◽  
Gang Ni
Keyword(s):  
Photocatalytic Activity ◽  
Nonionic Surfactants ◽  
Anatase Phase ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Tem Analysis ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Transmission Electron

This study investigated the effect of cationic, anionic, and nonionic surfactants on the formation, morphology, and surface properties of TiO2 nanoparticles synthesized by modified sol-gel method. The crystalline structures and morphologies of the powder have been characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD results showed TiO2 nanoparticles synthesized with different surfactants only include anatase phase. The TEM analysis revealed the surfactants can enhance dispersion of TiO2 nanoparticles. In contrast, the anionic surfactants showed hightly effects. The photocatalytic activity of samples was tested for degradation of methyl orange (MO) solutions. The results showed photocatalytic activity of the catalyst with surfactants was higher than pure TiO2 under ultraviolet.

Size-controlled synthesis of nanocrystalline BaTiO3 by a sol-gel type hydrolysis in microemulsion-provided nanoreactors

1998 ◽  
Vol 13 (11) ◽  
pp. 3174-3180 ◽  
Author(s):  
Ch. Beck ◽  
W. Härtl ◽  
R. Hempelmann
Keyword(s):  
Particle Size ◽  
Room Temperature ◽  
Sol Gel ◽  
Controlled Synthesis ◽  
Sintering Process ◽  
Line Broadening ◽  
X Ray ◽  
Transmission Electron ◽  
Hydrolysis Of ◽  
Size Controlled

Using the hydrolysis of appropriate alkoxide mixtures in water-in-oil microemulsions, nanocrystalline BaTiO3 has been prepared in the form of nonaggregated, cube-shaped crystals at room temperature without any sintering process as is demonstrated by means of x-ray diffractograms and transmission electron micrographs. By variation of the length of the hydrophilic part of the surfactant molecules, the diameter of the water droplets in the microemulsions could be tuned to values between 8 and 55 nm as determined by dynamic light scattering. The size of the resulting nano-BaTiO3 (6 nm ≤ 〈d〉vol ≤ 17 nm) was evaluated from the line broadening of x-ray reflections and correlates to the droplet size. The particle size distribution is very narrow, and in some cases nearly monodisperse.

scholarly journals Pengaruh Ethanolamina (MEA) dalam Pembentukan TiO2 dari Bahan Awal Ti Butoksida

2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Rika Rahayu ◽  
◽  
Posman Manurung ◽  
Yanti Yulianti ◽  
◽  
...  
Keyword(s):  
Anatase Phase ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tem Characterization ◽  
Transmission Electron ◽  
Imagej Software ◽  
Uv Lamps ◽  
Brookite Phase

Titanium dioxide has been prepared through the sol gel method using the addition of ethanolamine. The research was conducted to study the effect of MEA on the formation of TiO2. The amount of MEA was varied to 0; 0.5; 1; 1.5; and 2 ml respectively. The samples were calcined at a temperature of 500 ºC. TiO2was characterized using X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and photocatalyst tests using UV lamps. The XRD characterization results showed that in the A sample an anatase phase was formed whereas in the Csample an anatase phase and a brookite phase were formed. The resultof TEM characterization using ImageJ software show that the particle size of TiO2 is26,1 nm, respectively. The results of the characterization of the fastest photocatalyst catalyst test occurred in sample C which the variation of MEA is 1 ml.

scholarly journals Synthesis of TiO2/SnO2 core shell nanocomposite via sol-gel method

2012 ◽  
Vol 05 ◽  
pp. 251-256 ◽  
Author(s):  
SORAIA KHOBY-SHENDY ◽  
MOHAMMAD REZA VAEZI ◽  
TORAJ EBADZADEH
Keyword(s):  
Sol Gel ◽  
Titanium Isopropoxide ◽  
Core Shell ◽  
Hydrothermal Processing ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Core ◽  
Transmission Electron ◽  
Diffraction Peaks ◽  
Hydrolysis Of

The particles of TiO 2 core/ SnO 2 shell nanocomposite were prepared by hydrolysis of SnCl 4.5 H 2 O in the presence of titania nanoparticle after drying and calcinations treatments. TiO 2 particle were produced from titanium isopropoxide sol by hydrothermal processing. X-ray diffraction (XRD), Fourier transformed infrared (FTIR), and transmission electron microscopy (TEM) were used to characterize the TiO 2/ SnO 2 core shell nanocomposites. The obtained results from XRD show that the SnO 2 nanoparticles coated on TiO 2 yields diffraction peaks correspond to the crystalline SnO 2 phase. Also, TEM results show that the nanocomposite particles have a spherical morphology and a narrow size distribution. The thickness of SnO 2 shell on the surface of TiO 2 particles were about 8 nm. Moreover, the results obtained from EDX analysis show that the core-shell structured nanocomposites have crystalline structure.

SYNTHESIS AND CHARACTERIZATION OF TITANIUM DIOXIDE DOPED WITH Sc3+ IONS

2006 ◽  
Vol 05 (02n03) ◽  
pp. 351-357 ◽  
Author(s):  
YOUNG SOO KANG ◽  
DONG RI ZHANG
Keyword(s):  
Titanium Dioxide ◽  
Anatase Phase ◽  
Sol Gel ◽  
Average Particle Size ◽  
Average Particle ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Ft Ir ◽  
Xrd Patterns

Nanoparticles of titanium dioxide ( TiO 2) doped with 5 at.% Sc 3+ ions were synthesized using the sol–gel method and calcined at 500°C to obtain better anatase phase. The crystal structures of the doped TiO 2 nanoparticles were characterized by X-ray powder diffraction (XRD), Raman, UV-vis, FT-IR spectroscopy, high resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED). XRD patterns and Raman spectra of TiO 2 + 5 at.% Sc -500°C show the anatase phase and the average particle size of the sample calculated from XRD patterns was determined as 5.9 nm. Well-resolved rings of SAED of TiO 2 doped with Sc 3+ ions are easily indexed to those from XRD pattern. HRTEM shows the well-defined lattice fringes and the lattice spacing measured from HRTEM is 0.33 nm, which is in well agreement with the distance between the (101) planes in anatase TiO 2. Energy-dispersive X-ray (EDX) spectrum of the doped TiO 2 confirms the presence of Sc element in the TiO 2 matrix.

Cu Doped TiO2: Visible Light Assisted Photocatalytic Antimicrobial Activity and High Temperature Anatase Stability

2018 ◽  
Author(s):  
Snehamol Mathew ◽  
Priyanka Ganguly ◽  
Stephen Rhatigan ◽  
Vignesh Kumaravel ◽  
Ciara Byrne ◽  
...  
Keyword(s):  
Visible Light ◽  
Visible Light Irradiation ◽  
Density Functional ◽  
Anatase Phase ◽  
Sol Gel ◽  
Chemical Properties ◽  
Light Irradiation ◽  
Health Concern ◽  
Bacterial Inactivation ◽  
X Ray

Indoor surface contamination by microbes is a major public health concern. A damp environment is one potential sources for microbe proliferation. Smart photocatalytic coatings on building surfaces using semiconductors like titania (TiO<sub>2</sub>) can effectively curb this growing threat.<b> </b>Metal-doped titania in anatase phase has been proved as a promising candidate for energy and environmental applications. In this present work, the antimicrobial efficacy of copper (Cu) doped TiO<sub>2 </sub>(Cu-TiO<sub>2</sub>) was evaluated against <i>Escherichia coli</i> (Gram-negative) and <i>Staphylococcus aureus</i> (Gram-positive) under visible light irradiation. Doping of a minute fraction of Cu (0.5 mol %) in TiO<sub>2 </sub>was carried out <i>via</i> sol-gel technique. Cu-TiO<sub>2</sub> further calcined at various temperatures (in the range of 500 °C – 700 °C) to evaluate the thermal stability of TiO<sub>2</sub> anatase phase. The physico-chemical properties of the samples were characterised through X-ray diffraction (XRD), Raman spectroscopy, X-ray photo-electron spectroscopy (XPS) and UV-visible spectroscopy techniques. XRD results revealed that the anatase phase of TiO<sub>2</sub> was maintained well, up to 650 °C, by the Cu dopant. UV-DRS results suggested that the visible light absorption property of Cu-TiO<sub>2 </sub>was enhanced and the band gap is reduced to 2.8 eV. Density functional theory (DFT) studies emphasises the introduction of Cu<sup>+</sup> and Cu<sup>2+</sup> ions by replacing Ti<sup>4+</sup> ions in the TiO<sub>2</sub> lattice, creating oxygen vacancies. These further promoted the photocatalytic efficiency. A significantly high bacterial inactivation (99.9%) was attained in 30 mins of visible light irradiation by Cu-TiO<sub>2</sub>.

scholarly journals The impact of point defects in n-type GaN layers on thermal decomposition of InGaN/GaN QWs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mikolaj Grabowski ◽  
Ewa Grzanka ◽  
Szymon Grzanka ◽  
Artur Lachowski ◽  
Julita Smalc-Koziorowska ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Temperatures ◽  
Point Defects ◽  
X Ray Diffraction ◽  
Helium Ions ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
The Impact ◽  
Ingan Quantum Wells

AbstractThe aim of this paper is to give an experimental evidence that point defects (most probably gallium vacancies) induce decomposition of InGaN quantum wells (QWs) at high temperatures. In the experiment performed, we implanted GaN:Si/sapphire substrates with helium ions in order to introduce a high density of point defects. Then, we grew InGaN QWs on such substrates at temperature of 730 °C, what caused elimination of most (but not all) of the implantation-induced point defects expanding the crystal lattice. The InGaN QWs were almost identical to those grown on unimplanted GaN substrates. In the next step of the experiment, we annealed samples grown on unimplanted and implanted GaN at temperatures of 900 °C, 920 °C and 940 °C for half an hour. The samples were examined using Photoluminescence, X-ray Diffraction and Transmission Electron Microscopy. We found out that the decomposition of InGaN QWs started at lower temperatures for the samples grown on the implanted GaN substrates what provides a strong experimental support that point defects play important role in InGaN decomposition at high temperatures.

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