Preparation of Titanium Oxide Nanotube by Hydrothermal Process

2007 ◽  
Vol 124-126 ◽  
pp. 1165-1168 ◽  
Author(s):  
M. Qamar ◽  
Cho Rong Yoon ◽  
Hyo Jin Oh ◽  
Anna Czoska ◽  
K. Park ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Titanium Oxide ◽  
Sol Gel ◽  
Hydrothermal Process ◽  
Hollow Fibers ◽  
Systematic Analysis ◽  
Transmission Electron ◽  
Tio2 Sol ◽  
Naoh Solution

The TiO2 sol was prepared hydrothermally in an autoclave from aqueous TiOCl2 solutions as starting precursor. Hollow fibers were obtained when sol-gel derived TiO2 sol was treated chemically with NaOH solution and subsequently heated in autoclave under various conditions. A systematic analysis of the influence of different NaOH concentrations on the formation of nanotubes has been carried out using XRD and SEM. The phase structure of the synthesized material was determined by transmission electron microscopy and found that these materials are, infact, hollow fibers widely known as nanotubes. From the TEM images, the outer and inner diameters of the tubes were measured ca. 8 and about 4 nm, respectively, with several hundred nanometers in length.

scholarly journals Synthesis of rutile titania powders: Agglomeration, dissolution, and reprecipitation phenomena

2003 ◽  
Vol 18 (6) ◽  
pp. 1457-1464 ◽  
Author(s):  
Sascha M. Klein ◽  
Joon Hwan Choi ◽  
David J. Pine ◽  
Fred F. Lange
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Nitric Acid ◽  
Sol Gel ◽  
Hydrothermal Process ◽  
Molar Ratio ◽  
Transmission Electron ◽  
Primary Particles ◽  
Rutile Titania ◽  
Mean Size

Rutile titania powders were synthesized via a sol-gel/hydrothermal process using nitric acid as the catalyst. A molar acid to alkoxide ratio of 10 and a water to alkoxide molar ratio of 250 produced 100% rutile powders when precipitated below 45 °C. Higher temperatures yielded initially either anatase or mixtures of anatase and rutile. Spherulitic growth produced cauliflower-shaped agglomerates with a mean size of 760 nm. The agglomerates could be broken apart into approximately 100-nm large broomlike agglomerates via a dissolution and reprecipitation process when reacted with approximately 2.4 molar nitric acid. Transmission electron microscopy observations showed that the broomlike agglomerate consisted of linear clusters of rodlike agglomerates composed of crystallographically aligned, primary particles approximately 4 nm in size.

Preparation of Composite Iron Oxides via Hydrothermal Process

2012 ◽  
Vol 583 ◽  
pp. 162-166 ◽  
Author(s):  
Jian Zhen Huo
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Iron Oxides ◽  
Hydrothermal Process ◽  
Advanced Materials ◽  
Composite Oxide ◽  
X Ray ◽  
Transmission Electron ◽  
Different Types ◽  
Naoh Solution

Composite iron oxides are very important advanced materials. In this paper different types of iron oxides α-FeOOH, α-Fe2O3 and composite oxide NiFe2O4 were synthesized via a simple hydrothermal method at 180°C for 10 h. The phases and morphologies of the products were characterized by X-ray diffractometer and high-resolution transmission electron microscopy. The results indicated that α-FeOOH nanorods were prepared when mole concentration of NaOH solution was 3M. By increasing the concentration of NaOH to 5M and 8M, we obtained qusi-fusiform α-Fe2O3 single-crystallines and composite oxide NiFe2O4 nanocrystals, respectively. Our experiments showed that both the concentration of NaOH solution and existence of sulphate ions affect the formation of varying morphologies of the products.

Interfacial precipitation in titania-doped diphasic mullite gels

1998 ◽  
Vol 13 (4) ◽  
pp. 974-978 ◽  
Author(s):  
Seong-Hyeon Hong ◽  
Naesung Lee ◽  
Altaf H. Carim ◽  
Gary L. Messing
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Phase Transformations ◽  
Orientation Relationship ◽  
Sol Gel ◽  
Sintered Body ◽  
Transmission Electron

Interfacial precipitation in sol-gel derived, titania-doped diphasic mullite gels was investigated using conventional and high resolution transmission electron microscopy. Rutile, anatase, and brookite precipitated on the interface between {110} planes of mullite and glass pockets in the sintered body. The formation of brookite may be attributable to the Si- and Al-rich environment during precipitation. Each polymorph of titania has a unique morphology and orientation relationship with mullite. Brookite exhibits a truncated pill box shape, and anatase displays a vermicular morphology. Quenching experiments suggest that the precipitates grow and undergo phase transformations during cooling.

Eu3+/Tb3+ Co-Doped Cerium Oxide Transparent Nanocomposite for Color-Tunable Emission

NANO ◽  
2018 ◽  
Vol 13 (10) ◽  
pp. 1850119
Author(s):  
Xiaoyan Li ◽  
Yunlong Yu ◽  
Xiangfeng Guan ◽  
Peihui Luo ◽  
Linqin Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Transmission Electron Microscopy ◽  
Sol Gel ◽  
Homogeneous Precipitation ◽  
Transmission Electron ◽  
Color Tunable ◽  
Co Doped ◽  
Tunable Emission

Eu[Formula: see text]/Tb[Formula: see text] co-doped nanocomposite containing CeO2 nanocrystals was successfully prepared by an in situ sol–gel polymerization approach. High-resolution transmission electron microscopy demonstrated the homogeneous precipitation of CeO2 nanocrystals among the polymethylmethacrylate (PMMA) matrix. The thermal stability and UV-shielding capability of the obtained nanocomposite were improved with increase of CeO2 content. The tuning of the emissive color from green and yellow to red can be easily achieved by varying the dopant species and concentration. These results suggested that the obtained nanocomposite could be potentially applicable in transparent solid-state luminescent devices.

SYNTHESIS OF TUBULAR Ge NANOSTRUCTURES

2010 ◽  
Vol 09 (01n02) ◽  
pp. 75-81
Author(s):  
L. Z. PEI ◽  
H. S. ZHAO ◽  
H. Y. YU ◽  
J. L. HU
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Pore Size ◽  
Formation Process ◽  
Room Temperature ◽  
Hydrothermal Process ◽  
Rolling Mechanism ◽  
Transmission Electron ◽  
Inner Pore

Hollow germanium tubular nanostructures have been obtained by a hydrothermal process at a temperature of 400°C and pressure of 7 MPa with quick cooling to room temperature. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) show that the germanium tubular nanostructures are polycrystalline and have open-end structures at the tips. The diameter of germanium tubular nanostructures is about 40–70 nm and the inner pore size is about 10 nm in average. We propose the rolling mechanism for the formation of tubular nanostructures from lamellar nanostructures to explain the possible formation process of germanium tubular nanostructures.

Combined effect of grain size and tensile stresses on the ferroelectric properties of sol-gel (Pb,La)TiO3 thin films

1999 ◽  
Vol 14 (12) ◽  
pp. 4570-4580 ◽  
Author(s):  
M. Alguerá ◽  
M. L. Calzada ◽  
L. Pardo ◽  
E. Snoeck
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Lead Titanate ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Precursor Solution ◽  
Grain Size Effect ◽  
Transmission Electron ◽  
Switchable Polarization

Transmission electron microscopy has shown that the grain size of sol-gel-prepared lanthanum-modified lead titanate films increases from ∼100 to ∼1 μm when the excess of PbO in the precursor solution is reduced from 20 to 10 mol%. Switchable polarization is higher in the films with a smaller grain size. Profilometry and the temperature dependence of the dielectric permittivity indicate that films are tensile stressed by the substrate. The grain-size effect on polarization switching is explainedby taking into account this tensile stress, which is thought to induce some a-domain orientation and 90° domain wall clamping in the grains attached to the substrate.

TiO2-Al2O3 nanocomposites

1995 ◽  
Vol 10 (5) ◽  
pp. 1264-1269 ◽  
Author(s):  
G. Pacheco-Malagon ◽  
A. Garcia-Borquez ◽  
D. Coster ◽  
A. Sklyarov ◽  
S. Petit ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Critical Radius ◽  
Sol Gel ◽  
Atomic Ratio ◽  
Mas Nmr ◽  
Band Edge ◽  
Alumina Matrix ◽  
Transmission Electron

Nanosized TiO2 is synthesized in a nanosized alumina matrix by a sol-gel procedure. The results of the study of the blueshift of the TiO2 UV band edge are compared to the information obtained from transmission electron microscopy (TEM). As long as the atomic ratio Ti/Al remains smaller than 17.5%, no individualized TiO2 particles are detected by TEM, in spite of the fact that no modification of the alumina structure occurs, as revealed by 27Al MAS NMR. The shift of the UV band edge suggests the growth of homogeneous TiO2 domains in the alumina matrix. Above a critical radius, on the order of 1.2 nm, individual and crystalline TiO2 particles become visible in the TEM picture, and the porosity of the material decreases markedly.

Sol-gel processing of nanocrystalline haematite thin films

1997 ◽  
Vol 12 (6) ◽  
pp. 1441-1444 ◽  
Author(s):  
L. Armelao ◽  
A. Armigliato ◽  
R. Bozio ◽  
P. Colombo
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Raman Spectroscopy ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
Single Particles ◽  
X Ray ◽  
Transmission Electron ◽  
Gel Processing

The microstructure of Fe2O3 sol-gel thin films, obtained from Fe(OCH2CH3)3, was investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. Samples were nanocrystalline from 400 °C to 1000 °C, and the crystallized phase was haematite. In the coatings, the α–Fe2O3 clusters were dispersed as single particles in a network of amorphous ferric oxide.

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