Effect of Nb and Sc Doping on the Phase Transformation of Sol–Gel Processed TiO2 Nanoparticles

2008 ◽  
Vol 8 (5) ◽  
pp. 2410-2418 ◽  
Author(s):  
A. Ahmad ◽  
S. Buzby ◽  
C. Ni ◽  
S. Ismat Shah
Keyword(s):  
Activation Energy ◽  
Phase Transformation ◽  
Metal Ion ◽  
Dopant Concentration ◽  
Anatase Phase ◽  
Sol Gel ◽  
Rutile Phase ◽  
Phase Transformation Temperature ◽  
Rutile Structure ◽  
X Ray

Nb and Sc doped TiO2 nanoparticles were synthesized via sol–gel technique. Dopant concentration of each element was varied from 0.5 to 1.5 atomic%. The effect of metal ion doping and calcination temperatures on anatase to rutile phase transformation has been investigated. Samples were analyzed by various analytical methods such as X-ray diffraction (XRD), Transmission Electron Microscope (TEM), X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Spectroscopy (EDS). XRD analyses showed that Nb and Sc doped samples calcined at 300 °C and 350 °C, respectively, were crystalline and had an anatase structure. Results showed that anatase was stable up to 700 °C annealing temperature for samples doped with 0.5 atomic% Nb. There was a sharp transition from anatase to rutile phase above 700 °C and complete rutile structure was obtained at 750 °C. However, the transformation from anatase to rutile was not so sharp in samples doped with 1.0 atomic% and 1.5 atomic% Nb. Results indicated that higher concentration of Nb helps to stabilize the anatase phase. For samples doped with 0.5 atomic% Sc, anatase phase is stable up to 650 °C. Transformation from anatase to rutile starts at temperature above 650 °C and 100% rutile phase was obtained at 800 °C while for samples doped with 1.0 atomic% and 1.5 atomic% Sc, the complete transformation from anatase to rutile takes place at an even higher temperature. Results indicate that increasing the calcination time from 0.5 to 2.0 hours at 500 °C does not affect the stability of anatase phase. However, TEM and XRD data showed that the increase in the annealing time leads to an increase in particles size. The rutile to anatase concentration ratio increased with temperature above the phase transformation temperature. The activation energy for the phase transformation from anatase to rutile for doped and undoped samples was also measured. There was a general rise in the activation energy with increasing dopant concentration.

scholarly journals Study on the Phase Transformation Kinetics of Sol-Gel DrivedTiO2Nanoparticles

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
H. Mehranpour ◽  
M. Askari ◽  
M. Sasani Ghamsari ◽  
H. Farzalibeik
Keyword(s):  
Activation Energy ◽  
Phase Transformation ◽  
Sol Gel ◽  
Rutile Phase ◽  
Transformation Kinetics ◽  
X Ray ◽  
Prepared Nanoparticles ◽  
Phase Transformation Kinetics ◽  
Diffusion Controlled ◽  
Kinetics Of

Titanium dioxide nanopowders were synthesized by the diffusion controlled sol-gel process (LaMer model) and characterized by DTA-TG, XRD, and SEM. The preparedTiO2nanoparticles have uniform size and morphology, and the phase transformation kinetics of obtained material was studied by interpretation of the X-ray diffraction patterns peaks on the base of Avrami equation. The stating point of anatase-rutile phase transformation temperature in the prepared nanoparticles was found between 100 and200°C. A decreasing trend on the intensity of X-ray peaks of anatase phase was observed up to600°Cwhen the presence of the rutile phase became predominant. Results indicated that the transition kinetics of the diffusion controlled prepared nanoparticles was begun at low temperature, and it can be concluded that the nucleation and growth sites in these particles were more than other. However, it has been found that the nucleation activation energy of rutile phase was 20 kj/mol, and it is the lowest reported activation energy.

scholarly journals Photocatalytic Degradation of Remazol Brilliant Blue R and Remazol Yellow FG using TiO2 doped Cd, Co, Mn

2021 ◽  
Vol 16 (4) ◽  
pp. 804-815
Author(s):  
Candra Purnawan ◽  
Sayekti Wahyuningsih ◽  
Oktaviani Nur Aniza ◽  
Octaria Priwidya Sari
Keyword(s):  
Photocatalytic Activity ◽  
Metal Ion ◽  
Anatase Phase ◽  
Sol Gel ◽  
Rutile Phase ◽  
Brilliant Blue ◽  
Bandgap Energy ◽  
X Ray ◽  
Remazol Brilliant Blue R ◽  
Metal Doped

TiO2 and TiO2 doped Cd, Co, Mn (TiO2-M) were synthesized with a sol-gel method, and the photocatalytic activity of Remazol Brilliant Blue R and Remazol Yellow FG has been conducted. TiO2-M (Cd, Co, Mn) was synthesized with the mol Ti:M ratio of 3:1, and the materials were calcined at 300, 400, and 500 °C. The materials were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), and UV-Vis Reflectance. The XRD result shows that at the temperature of 300 °C TiO2 and TiO2-M formed tend to be amorphous. At 400 °C the anatase phase is formed, while at 500 °C the rutile phase begins to form. And overall, the crystallinity of TiO2 is higher than metal-doped TiO2. The UV-Vis Reflectance result showed that the bandgap energy of all doping materials (TiO2-M) decreased. The larger the metal ion radius of dopant, the larger the crystal size obtained  and then the higher the bandgap obtained. The results of SEM-EDX showed that the morphology of TiO2 was spherical and regular, whereas the morphology of TiO2-M had a smoother surface due to the influence of metal doping. Photocatalytic activity of TiO2-M on Remazol Brilliant Blue R and Remazol Yellow FG was greater than TiO2. The optimum pH of the solution was obtained at pH 5 and the optimum catalyst phase was obtained at the anatase phase. The percentages degradation for 30 min of Remazol Brilliant Blue R were 67.34% (TiO2), 92.12% (TiO2-Co), 85.47% (TiO2-Mn), and 83.91% (TiO2-Cd), while for Remazol Yellow FG they were 58.84% (TiO2), 74.61% (TiO2-Co), 67.93% (TiO2-Mn) and 64.19% (TiO2-Cd), respectively. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Structural, Optical and Magnetic Properties of Nanocrystalline Cobalt Doped TiO2 Prepared by Sol-Gel Route

2013 ◽  
Vol 24 ◽  
pp. 168-175
Author(s):  
Kirit S. Siddhapara ◽  
D.V. Shah
Keyword(s):  
Magnetic Properties ◽  
Anatase Phase ◽  
Sol Gel ◽  
Photo Luminescence ◽  
Rutile Phase ◽  
Gravimetric Analysis ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Drying Treatment

Nanocrystalline Cobalt-doped TiO2was prepared by Sol-Gel technique, followed by freeze-drying treatment at-30°C temperature for 12hrs. The obtained Gel was thermally treated at 200,400,600, 800°C. 1%, 2% and 4% Cobalt doped TiO2nanopowder has been prepared X-ray Powder Diffraction (XRD), Scanning Electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), was used to study its structural properties. The XRD pattern shows the coexistence of anatase phase and rutile phase. Thermal gravimetric analysis shows Cobalt concentration affects thermal decomposition. UV-Vis Spectroscopy, Photo luminescence (PL), was used to study its Optical properties. Optical Bandgap were calculated with the incorporation of different concentration of cobalt. UV-Visible spectroscopy show variation in band gap for the sample treated at different temperature for same concentration. All Cobalt doped TiO2nanostructures shows an appearance of Red shift relative to the bulk TiO2. The determination of magnetic properties was also carried out by Vibrating Sample Magnetometer.

The Effects of Doping Micro Palladium on the Structure and Performance of TiO2 Powder

2012 ◽  
Vol 550-553 ◽  
pp. 340-346 ◽  
Author(s):  
Xiu Hua Liu ◽  
Dan Meng ◽  
He Yi Wang ◽  
Yi Deng ◽  
Bing Deng ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Pure Tio2 ◽  
Phase Transformation Temperature ◽  
Excitation Wavelength ◽  
Tio2 Powder ◽  
Rutile Structure ◽  
Crystal Forms ◽  
Anatase Structure ◽  
X Ray

The Pd-doped TiO2 powder was prepared by the sol-gel method and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis absorption spectroscopy and X-ray diffraction. The results show that palladium exists as PdO and that the PdO crystal forms in the Pd/TiO2 powder calcined at 973 K. When the Pd/TiO2 powder is calcined at a temperature between 573K and 973 K, TiO2 mainly exists in the anatase structure, and the average diameters of the anatase TiO2 and PdO particles are less than 45 nm. The crystal lattice constant a decreases while c increases with the increasing of the calcination temperature. Compared with the pure TiO2 powder prepared under the same conditions, the phase transformation temperature from the anatase structure to the rutile structure for TiO2 in the Pd/TiO2 powder increases, the excitation wavelength of Pd/TiO2 powder is broadened to the visible light region and the visible photocatalytic activity increases obviously.

Influence of ligand groups in Ti precursors on phase transformation and microstructural evolution of TiO2 thin films prepared by the wet chemical process

2001 ◽  
Vol 16 (6) ◽  
pp. 1712-1719 ◽  
Author(s):  
Chu-Chi Ting ◽  
San-Yuan Chen
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Phase Transformation ◽  
Microstructural Evolution ◽  
Chemical Reactivity ◽  
Sol Gel ◽  
Decisive Role ◽  
Rutile Phase ◽  
Film Structure ◽  
Tio2 Thin Films

TiO2 thin films prepared by metalorganic decomposition (MOD-TiO2) and sol-gel processes (SG-TiO2) were investigated in terms of the anatase-to-rutile phase transformation and microstructural evolution. It was found that the chemical reactivity of the ligand groups initially coordinated on the titanium precursor plays a decisive role in the structure development of as-deposited SG- and MOD-TiO2 films. MOD-TiO2 films consist of small aggregated particles and therefore, tend to coalesce together to form an inhomogeneous microstructure during the anatase-to-rutile phase transformation. On the other hand, SG-TiO2 films consist of uniform large particles that tend to grow homogeneously. MOD-TiO2 films showed a higher crystallization temperature than the SG-TiO2 films but the temperature of the anatase-to-rutile phase transformation is much lower in MOD- (approximately 775 °C) as compared to SG-TiO2 films (approximately 930 °C). The activation energy (Q) was estimated as 524 and 882 kJ/mol for the MOD- and SG-TiO2 films, respectively. The lower transformation temperature and activation energy in MOD-TiO2 films were due to smaller grain size and more potential nucleation sites existing in the un-transformed MOD-TiO2 film structure, which can accelerate the rate of anatase-to-rutile transformation.

Structural and Thermal Studies of Titanium Dioxide Gel Modified with Anatase Isostructural Zircon Silicate

2018 ◽  
Vol 930 ◽  
pp. 73-78
Author(s):  
Eduardo Felipe de Carli ◽  
Natali Amarante da Cruz ◽  
Hiana Muniz Garcia ◽  
Jusinei Meireles Stropa ◽  
Lis Regiane Vizolli Favarin ◽  
...  
Keyword(s):  
Phase Transition ◽  
Titanium Dioxide ◽  
Rietveld Method ◽  
Anatase Phase ◽  
Sol Gel ◽  
Thermal Studies ◽  
Rutile Phase ◽  
Structural Rearrangements ◽  
X Ray Diffraction ◽  
X Ray

Important changes in anatase crystal structure are responsible for the consequent anatase-to-rutile phase transition in titanium dioxide powders. In order to investigate several structural rearrangements occurring in anatase phase obtained by hydrolysis-based method such as Sol-Gel method the X-ray diffraction techniques followed by Rietveld method seems to better approach. Several alterations in anatase lattice parameters can occur by doping insertion and the investigation of isostructural zircon silicate can provide interesting ones. In the present paper, the monitoring of anatase structure reordering and the consequent anatase-to-rutile phase transition along the thermal treatment up to higher temperatures were monitored carrying out DSC and XRD characterizations. The insertion of 6 mol% of zircon silicate leads to the fully anatase stabilization up to 900 °C due the control of ordering process, even that a continuous increasing in anatase tetragonality is present during the entire process. We can conclude the reconstructive anatase-to-rutile phase transition is delayed to very higher temperatures can consequence of more stable cross-linked metal oxide bond in anatase phase.

Synthesis and Antimicrobial Activity of Fe:TiO2 Particles

2019 ◽  
Vol 56 ◽  
pp. 28-38 ◽  
Author(s):  
Uraiwan Werapun ◽  
Jaraslak Pechwang
Keyword(s):  
Anatase Phase ◽  
Sol Gel ◽  
Rutile Phase ◽  
Antibacterial Activities ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Xrd Patterns ◽  
Increasing Temperature ◽  
Scanning Electron

TiO2 and iron-doped TiO2 were synthesized by sol-gel method. TiO2 and 0.5 %mol Fe:TiO2 were calcined at 500 and 800 °C for 3 h. The synthesized particles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-VIS diffuse reflectance spectrophotometry (UV/DRS), scanning electron microscopy (SEM) and scanning electron microscope-energy dispersive X-Ray analysis (SEM-EDX). The XRD patterns of all samples that were calcined at 500 °C showed only anatase phase. On increasing temperature from 500 to 800 °C, the anatase phase transformed to rutile phase. For 0.5 %mol Fe:TiO2, pseudobrookite (Fe2TiO5) phase was observed at 800 °C. The particles that contained rutile showed higher antibacterial activities against E.coli, B. subtilis, and S. aureus than anatase phase, under fluorescent irradiation.

Modification of the phase transition temperatures in titania doped with various cations

1997 ◽  
Vol 12 (2) ◽  
pp. 439-443 ◽  
Author(s):  
R. Rodríguez-Talavera ◽  
S. Vargas ◽  
R. Arroyo-Murillo ◽  
R. Montiel-Campos ◽  
E. Haro-Poniatowski
Keyword(s):  
Phase Transition ◽  
Anatase Phase ◽  
Sol Gel ◽  
Rutile Phase ◽  
Transition Temperatures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Transition Temperatures ◽  
Gel Technique ◽  
Almost All

Titania matrices prepared by a sol-gel technique were doped with several cations (La, Zn, Al, K, Na, Ca, Ba, and Co). The effect of the dopants on the thermal and structural properties of the materials is analyzed. The dopant concentration was 2% mol with respect to titanium, and in all cases the same anion (nitrate) was used. The transition temperatures from amorphous to anatase and from anatase to rutile were measured using x-ray diffraction. The amorphous-anatase transition is independent, for almost all samples, of the type of dopant used; however, the anatase-to-rutile phase transition depends strongly on the kind of cation. This means that the temperature range where the anatase phase exists can be controlled by choosing the appropriate dopant. We have found a correlation between the anatase-rutile phase transition temperature and the radius of the cations and their electric charge.

Influence of Mass Ratio of Aquadest and TTIP on the Synthesis of TiO2 Nanoparticles to Improve the Performance of DSSC with Beta-Carotene as Sensitizer

2014 ◽  
Vol 896 ◽  
pp. 481-484 ◽  
Author(s):  
Nafi'ah Ardhani ◽  
Agus Supriyanto ◽  
Akhmad Herman Yuwono ◽  
Risa Suryana
Keyword(s):  
Crystal Size ◽  
Anatase Phase ◽  
Sol Gel ◽  
Beta Carotene ◽  
Rutile Phase ◽  
Bandgap Energy ◽  
Mass Ratio ◽  
Titanium Tetraisopropoxide ◽  
X Ray Diffraction ◽  
X Ray

TiO2 nanoparticles have been successfully synthesized using the sol-gel method with main materials of titanium tetraisopropoxide (TTIP) and HClO4 solutions. Mass ratios (Rw) of aquadest and TTIP were 0.85, 2.00, and 3.50 which were going to be investigated in crystallization of TiO2 phases. Pre-heating was performed on TiO2 at 60°C for one day then it was annealed at 150°C for 3 hours. The DSSC structure was formed by using the synthesized-TiO2 as semiconductor material and beta-carotene as dye sensitizer. The x-ray diffraction (XRD) spectrum indicated that TiO2 peaks had anatase phases on crystal orientation of (101), (004), and (200) while TiO2 of rutile phase only appeared on orientation of (211). The highest intensity for all Rw was dominated by (101) anatase phase. From XRD spectrum data of (101) peak, the Scherrer’s method predicted that crystal size of TiO2 was 3.48 nm, 4.36 nm, and 4.47 nm for Rw of 0.85, 2.00, and 3.50, respectively. The Tauc’s method was applied on the UV-Vis data that predicted the bandgap energy (Eg) of TiO2 for Rw of 2.00 (Eg=3.14 eV) was higher than Rw of 0.85 (Eg=3.02 eV) and 3.50 (Eg=3.04 eV). The I-V characteristic calculation of DSSC structures were obtained that the efficiency optimum is 0.01% for Rw of 2.00. It is considered that bandgap energy value correlated to stability of Ti-OH bonds that caused the exited-electrons are easily injected to conduction band of TiO2. The performance of DSSC using the synthesized-TiO2 which consists of anatase and rutile can be improved about ten times compared to that using the pure-TiO2 rutile.

Preparation and Photocatalytic Activity of TiO2/Tourmaline Composite Catalyst

2013 ◽  
Vol 800 ◽  
pp. 464-470 ◽  
Author(s):  
Wei Chao Liu ◽  
Huan Yan Xu ◽  
Tian Nuo Shi ◽  
Li Cheng Wu ◽  
Ping Li
Keyword(s):  
Photocatalytic Activity ◽  
Sintering Temperature ◽  
Anatase Phase ◽  
Sol Gel ◽  
Rutile Phase ◽  
Composite Catalyst ◽  
Nanosized Particles ◽  
X Ray Diffraction ◽  
Composite Photocatalyst ◽  
X Ray

TiO2/tourmaline composite photocatalyst was prepared by sol-gel method using tetrabutyl orthotitanate (Ti (OC4H9)4) as a precursor. As a comparison, pure TiO2 was prepared at the same experimental conditons without the addition of tourmaline. The obtained composite photocatalyst was characterized by X-Ray diffraction (XRD) and scanning electron microscope (SEM) and its photocatalytic activity was also investigated through the photodiscoloration of methyl orange (MO) under UV irradiation. The XRD results indicated that, in the composite photocatalyst, TiO2 existed in the form of anatase and rutile, with the sintering temperature and tourmaline content increasing, the anatase phase trended to the transformation to rutile phase. The SEM results revealed that the nanosized particles of TiO2 were well dispersed and immobilized on the surface of tourmaline, especially for the sample with 2% tourmaline content. Compared with pure TiO2, the composite photocatalyst exhibited a higher photocatalytic activity. When the pure TiO2 was used as the photocatalyst, the MO discoloration ratio only reached 55%. However, the MO discoloration ratio could approach 100% in presence of TiO2/tourmaline composit photocatalyst under the same conditions. The effects of tourmaline content and sintering temperature on the photocatalytic activity of the composite were studied in this work and the results suggested that the sample with 2% tourmaline content and sintered at the temperature of 550°C exhibited the best photocatalytic activity. Finally, the possible mechanism for the photodiscoloration of MO was put forward.

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