Autothermal Gelation Synthesis of Uniform Titania Nanoparticles

2010 ◽  
Vol 148-149 ◽  
pp. 1188-1191
Author(s):  
Xi Xin Wang ◽  
Jian Ling Zhao ◽  
Zhao Hui Meng ◽  
Jia Wei Yan
Keyword(s):  
Grain Size ◽  
Tio2 Nanoparticles ◽  
Anatase Phase ◽  
Xrd Analysis ◽  
Rutile Phase ◽  
Titania Nanoparticles ◽  
Gelation Process ◽  
Average Grain Size ◽  
Process Effects ◽  
20 Nm

Titania nanoparticles were successfully synthesized through an easily controlled and simple autothermal gelation process. Effects of H2O2 concentrations, solvent quantity and dissolving temperature were investigated in detail. DSC–TGA and XRD analysis showed that the synthesized TiO2 nanoparticles were in anatase phase at 400°C and in rutile phase at 650°C. TEM image indicated that the titania nanoparticles were uniform and approximately spherical, the average grain size of the product was about 20 nm.

ATOMIC FORCE MICROSCOPY AND XRD ANALYSIS OF SILVER FILMS DEPOSITED BY THERMAL EVAPORATION

2006 ◽  
Vol 20 (02) ◽  
pp. 217-231 ◽  
Author(s):  
MUHAMMAD MAQBOOL ◽  
TAHIRZEB KHAN
Keyword(s):  
Atomic Force Microscopy ◽  
Grain Size ◽  
Surface Characterization ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Xrd Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Average Grain Size ◽  
20 Nm

Thin films of pure silver were deposited on glass substrate by thermal evaporation process at room temperature. Surface characterization of the films was performed using X-ray diffraction (XRD) and atomic force microscopy (AFM). Thickness of the films varied between 20 nm and 72.8 nm. XRD analysis provided a sharp peak at 38.75° from silver. These results indicated that the films deposited on glass substrates at room temperature are crystalline. Three-dimension and top view pictures of the films were obtained by AFM to study the grain size and its dependency on various factors. Average grain size increased with the thickness of the deposited films. A minimum grain size of 8 nm was obtained for 20 nm thick films, reaching 41.9 nm when the film size reaches 60 nm. Grain size was calculated from the information provided by the XRD spectrum and averaging method. We could not find any sequential variation in the grain size with the growth rate.

SURFACE CHARACTERIZATION AND GRAIN SIZE CALCULATION OF SILVER FILMS DEPOSITED BY THERMAL EVAPORATION

2005 ◽  
Vol 12 (05n06) ◽  
pp. 759-766 ◽  
Author(s):  
MUHAMMAD MAQBOOL ◽  
TAHIRZEB KHAN
Keyword(s):  
Grain Size ◽  
Surface Characterization ◽  
Room Temperature ◽  
Thermal Evaporation ◽  
Xrd Analysis ◽  
Force Microscopy ◽  
Glass Substrates ◽  
Atomic Force ◽  
Average Grain Size ◽  
20 Nm

Thin films of pure silver were deposited on glass substrate by thermal evaporation process at room temperature. Surface characterization of the films was performed using X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). Thickness of the films varied between 20 nm and 60 nm. XRD analysis provided a sharp peak at 38.75° from silver. These results indicated that the films deposited on glass substrates at room temperature are crystalline. 3D and top view pictures of the films were obtained by AFM to study the grain size and its dependency on various factors. Grain sizes were calculated using the XRD results and Scherer's formula. Average grain size increased with the thickness of the deposited films. A minimum grain size of 8 nm was obtained for 20 nm thick films, reaching a maximum value of 41.9 nm when the film size reaches 60 nm. We could not find any sequential variation in the grain size with the growth rate.

Transport Properties of B-, P-Doped and Undoped 50 kHz PECVD Microcrystalline Silicon

1989 ◽  
Vol 164 ◽  
Author(s):  
M.A. Hachicha ◽  
Etienne Bustarret
Keyword(s):  
Grain Size ◽  
Hall Mobility ◽  
Solid Phase ◽  
Grazing Angle ◽  
Dc Conductivity ◽  
X Ray Diffraction ◽  
Crystalline Fraction ◽  
Average Grain Size ◽  
20 Nm ◽  
Solid Phase Density

AbstractUndoped 500 nm-thick silicon layers with a crystalline fraction around 95% and an average grain size of 20 nm have been deposited at 350°C by 50 kHz triode PECVD in a H2/SiH4 mixture, in the presence of a magnetic field. Their room temperature (rt) dc conductivity μrt is 0.03 Δ−1cm−1 for a Hall mobility of 0.8 cm 2V−1s−1.The study by SIMS, infrared absorption, grazing angle x-ray diffraction and Raman scattering spectroscopies of the doped samples shows how the crystalline fraction and the grain size drop as the B2H6/SiH4 and PH3/SiH4 volumic ratios increase from 10 ppm to 1%.The rt dc conductivity reaches 2 Δ−1 cm−1 (Hall mobility: 15 cm2V−ls−1) for a solid phase density of 1019 cm−3 boron atoms, and 30 Δ−1cm−1 (Hall mobility: 55 cm2V−ls−1) at the maximum P incorporation of 8 × 1020cm−3.

Formation of nanocrystalline surface of a Cu–Zn alloy under electropulsing surface treatment

2007 ◽  
Vol 22 (7) ◽  
pp. 1947-1953 ◽  
Author(s):  
X.N. Du ◽  
B.Q. Wang ◽  
J.D. Guo
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Surface Layer ◽  
Surface Treatment ◽  
Skin Effect ◽  
Structure And Property ◽  
Average Grain Size ◽  
Solid State Phase Transformation ◽  
20 Nm ◽  
Zn Alloy

A nanocrystalline surface layer of a Cu–Zn alloy was developed by electropulsing (ECP) surface treatment. The average grain size was about 20 nm on the top surface layer and was gradually augmented with the increase in depth from the top surface. Nanoindentation measurements showed that the hardness was significantly enhanced on the top surface layer compared with the as-annealed Cu–Zn sample. The mechanism for the evolution of this structure and property was related not only to a solid-state phase transformation, but also to the effect of the enhancement of the nucleation rate and the skin effect during the ECP treatment. Therefore, the ECP surface treatment provides a promising method for obtaining surface self-nanocrystallization materials.

scholarly journals Controlled Synthesis and Microstructural Properties of Sol-Gel TiO2 Nanoparticles for Photocatalytic Cement Composites

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 26 ◽  
Author(s):  
Elena Cerro-Prada ◽  
Sara García-Salgado ◽  
M.Angeles Quijano ◽  
Fernando Varela
Keyword(s):  
Particle Size ◽  
Phase Transformation ◽  
Tio2 Nanoparticles ◽  
Anatase Phase ◽  
Sol Gel ◽  
Titanium Isopropoxide ◽  
Titania Nanoparticles ◽  
Structural Defects ◽  
Microstructural Properties ◽  
Anatase Nanoparticles

Titania nanoparticles are intensely studied for photodegradation applications. Control of nanoscale morphology and microstructural properties of these materials is critical for photocatalytic performance. Uniform anatase-type TiO2 nanoparticles were prepared by the sol-gel process using titanium isopropoxide as precursor. Controlled annealing up to 400 ℃ established crystallization and particle size ranging between 20 and 30 nm. Detailed thermal examination reveals that anatase phase transformation into rutile is affected by the annealing temperature and by the initial particle size. The anatase to rutile phase transformation occurs in the nanoparticles at 550 ℃. The Total Reflection X-ray Fluorescence (TXRF) study of the anatase nanoparticles shows a shift towards higher energy in the Ka Ti line of 10 eV, related to structural defects. These features were discussed in the photocatalytic behavior of several cement-based materials modified with the so-prepared anatase nanoparticles. The photocatalytic activity of the anatase-type TiO2/cement mortar system is evaluated from the degradation of Methylene Blue (MB) under UV irradiation, monitored through the absorbance at 665 nm. The results show that the photocatalytic composites exhibit up to 76.6% degradation efficiency. Mechanical testing of the nano-TiO2 modified cementitious composites evinces a moderate reinforcement of the strength properties at long ages.

Preparation and Microstructure Evolution of Both Freestanding and Supported TiO2 Thin Films

2002 ◽  
Vol 17 (6) ◽  
pp. 1520-1528 ◽  
Author(s):  
Chen-Lung Fan ◽  
Daniel Ciardullo ◽  
Jay Paladino ◽  
Wayne Huebner
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Grain Size ◽  
Grain Growth ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Tio2 Thin Films ◽  
Cover Glass ◽  
Citrate Complex ◽  
Phase Development

Thin films of TiO2 were fabricated by spin-coating silicon wafers and cover glass with a titanium citrate complex precursor. The grain growth and phase development of both freestanding and supported films were studied using a combination of atomic force microscopy, x-ray diffraction, and transmission electron microscopy. Freestanding films prepared at 400 °C possess only the anatase phase, while supported films treated under the same conditions formed a small amount of the rutile phase. After heat treatment at various temperatures, results indicated that porosity was introduced into the films when the grain size grew close to the film thickness. Grain growth studies show that the grain size of the freestanding film underwent a drastic increase during the transformation from anatase to rutile. The grain size of the supported films did not show an abrupt change upon heat treatment. The grain size of the freestanding films treated at 900 °C was approximately three times larger than that of the supported films.

Strength and Ductility in Electrodeposited Nanocrystalline Nickel

2009 ◽  
Vol 633-634 ◽  
pp. 411-420 ◽  
Author(s):  
Heather W. Yang ◽  
Farghalli A. Mohamed
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Annealing Treatment ◽  
Average Grain Size ◽  
Annealing Twins ◽  
Grain Distribution ◽  
Small Grains ◽  
20 Nm ◽  
Strength And Ductility

Electrodeposited nanocrystalline (nc) Ni having an average grain size of 20 nm was annealed at 443 K for different holding times. An examination of the microstructure following annealing showed three important features. First, all annealed samples exhibited abnormal grain growth, which was manifested by the presence of large grains that were surrounded by regions of small grains (bimodal grain distributions). Second, annealing twins existed in the large grains of the samples that showed a bimodal grain distribution. Third, by estimating the density of annealing twin, it was found that annealing nc-Ni at 443 K resulted in a maximum twin density after 5h. Following annealing treatment, specimens with different volume fractions of twins were tested under uniaxial tension at 393 K and a strain rate of 10-4 s-1. The results showed that both strength and ductility in nc-Ni attained maximum values after annealing for 5h. The role of both bimodal grain distributions and annealing twins in enhancing ductility and strength was discussed.

scholarly journals Studies on Electric and Dielectric Properties of Porous Sm0.5Sr0.5CoO3−δ

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
S. S. Pawar ◽  
K. P. Shinde ◽  
A. G. Bhosale ◽  
S. H. Pawar
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Grain Size ◽  
Dielectric Properties ◽  
Xrd Analysis ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Space Group ◽  
Average Grain Size ◽  
Scanning Electron

Frequency-dependent electric and dielectric properties of the porous Sm0.5Sr0.5CoO3−δ cathode prepared through conventional combustion synthesis technique were studied in the temperature range 298 K–973 K. The crystal symmetry, space group, and unit cell dimensions were confirmed by analyzing XRD pattern. XRD analysis indicates the formation of a single-phase orthorhombic structure with space group Pnma 62. Scanning electron microscopy technique was used to examine the morphology of the sample. Scanning electron microscopy study showed the formation of porous structure with an average grain size about 850 nm. From the electrical study, it is observed that the conduction in Sm0.5Sr0.5CoO3−δ sample takes place through the hopping mechanism and follows the inverse universal power law. The correlated barrier hopping model was employed successfully to explain the mechanism of charge transport in Sm0.5Sr0.5CoO3−δ. Further, the ac conductivity data was used to evaluate the minimum hopping length and apparent activation energy. The minimum hopping length was found to be ~10−4 times smaller than the grain size of Sm0.5Sr0.5CoO3−δ. The peaking behaviour of the real part of dielectric constant with frequency was explained using the Rezlescu model. This study helps to confirm that the charge transportation in Sm0.5Sr0.5CoO3−δ is due to two types of charge carriers.

Effects of Annealing Temperature on the Structure and Properties of TiO2 Nanofilm Materials

2012 ◽  
Vol 531 ◽  
pp. 203-206
Author(s):  
Han Shui Wu ◽  
Ying Lian Wang
Keyword(s):  
Grain Size ◽  
Annealing Temperature ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Amorphous Structure ◽  
Annealing Process ◽  
Structure And Properties ◽  
Glass Substrates ◽  
Quantum Size ◽  
Uv Absorption Spectrum

TiO2 thin films with good performance have been prepared by R.F. magnetron sputtering method on glass substrates. Surface morphology and UV absorption spectrum have been studied by XRD, SEM and UV-Vis scanning spectrophotometer. The influence of annealing temperature has also been discussed. The results show that, the films without annealing process present amorphous structure, the defects density of interior fiber is high and the structure is loose. With the rise of annealing temperature, the grain size increases, porosity decreases, and compactness is enhanced, at the same time, the film turns from anatase phase to rutile phase, quantum size effect is significant, surface energy reduces and absorb edge has red shift.

Agglomeration Eliminating Antimony Doped Tin Oxide (ATO) Nanoparticles by Different Drying Methods

2011 ◽  
Vol 399-401 ◽  
pp. 543-547
Author(s):  
Zi Li Liu ◽  
Qian Wen Dai ◽  
Sheng Zhou Chen ◽  
Zhe Guo
Keyword(s):  
Grain Size ◽  
Tin Oxide ◽  
Azeotropic Distillation ◽  
Rutile Phase ◽  
Microwave Drying ◽  
Drying Methods ◽  
Infrared Drying ◽  
Average Grain Size ◽  
Bet Method ◽  
Colour Changes

Antimony doped tin oxide (ATO) nanoparticles were synthesized via complex-homogeneous coprecipitation. Then different drying methods (such as azeotropic distillation, infrared drying and microwave drying, etc.) were used to eliminate the agglomeration. The nanoparticles were characterized by thermal analysis, X-ray diffraction (XRD), and Brunauer-Emmett-Teller measurements (BET). The result shows that ATO nanopaticles with tetragonal rutile phase structure are all well crystallized after the drying processes above, and the average grain size is between 29.30 nm and 71.52 nm. The grain size estimated by BET method is similar to the result of Scherrer equation, and the nanoparticles prepared by azeotropic distillation have better crystallinity comparing to other methods. With the extension of the distillation time, the grain size increases, and the colour changes from grey blue to light grey. Moreover, the combination of azeotropic distillation and infrared drying can prepare smaller and better crystalline ATO nanoparticles.

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