scholarly journals New approach of modifying the anatase to rutile transition temperature in TiO2 photocatalysts

RSC Advances ◽  
2016 ◽  
Vol 6 (97) ◽  
pp. 95232-95238 ◽  
Author(s):  
Ciara Byrne ◽  
Rachel Fagan ◽  
Steven Hinder ◽  
Declan E. McCormack ◽  
Suresh C. Pillai
Keyword(s):  
Phase Transition ◽  
Titanium Dioxide ◽  
Transition Temperature ◽  
Rutile Phase ◽  
Tio2 Photocatalysts ◽  
New Approach

In pure synthetic titanium dioxide, the anatase to rutile phase transition usually occurs between the temperatures of 600 °C and 700 °C.

Study of the Zirconium and Silicon Homovalent Dopants Insertion on the Structure and Bandgap Energy of Titanium Dioxide Powders

2018 ◽  
Vol 930 ◽  
pp. 67-72
Author(s):  
Hiana Muniz Garcia ◽  
Eduardo Felipe de Carli ◽  
Natali Amarante da Cruz ◽  
Jusinei Meireles Stropa ◽  
Lis Regiane Vizolli Favarin ◽  
...  
Keyword(s):  
Phase Transition ◽  
Titanium Dioxide ◽  
Performance Enhancement ◽  
Thermal Analyses ◽  
Rutile Phase ◽  
Bandgap Energy ◽  
Structural Effects ◽  
Structural Refinement ◽  
Anatase Structure ◽  
Atomic Coordinates

The reconstructive transformation occurring during the anatase-to-rutile phase transition can be observed through adequate techniques such as Thermal Analyses and Z-ray diffractometry followed by structural refinement. The typical photonic properties of titanium dioxide photocatalysts depend on the anatase structure and how the modifiers can provide their performance enhancement. In the present work, we investigate the structural effects caused by the simultaneous homovalent modification on the anatase structure in order to understand the mechanisms of the anatase-to-rutile phase transition in terms of the atomic coordinates and the lattice parameters. The refined structures along the calcination temperature from 500 to 900 oC suggest the oxygen bonds are strongly affected in unmodified anatase in order to destroy and rebuilt the crystal structure and lead to the rutile phase formation above 700 oC, unless some modifier pairs stabilize them.

scholarly journals Tuning Anatase-Rutile Phase Transition Temperature: TiO2/SiO2 Nanoparticles Applied in Dye-Sensitized Solar Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Billy N. Cardoso ◽  
Emerson C. Kohlrausch ◽  
Marina T. Laranjo ◽  
Edilson V. Benvenutti ◽  
Naira M. Balzaretti ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Surface Area ◽  
Phase Transition Temperature ◽  
Dye Sensitized Solar Cells ◽  
Rutile Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Molar Percent

TiO2/SiO2 nanoparticles with 3, 5, and 10 molar percent of silica, were synthesized by hydrothermal method and characterized by SEM, TEM, N2 adsorption-desorption isotherms, X-ray diffraction, and Raman and UV-Vis spectroscopy. While pristine TiO2 thermally treated at 500°C presents a surface area of 36 m2 g-1 (±10 m2 g-1), TiO2/SiO2 containing 3, 5, and 10 molar percent of silica present surface areas of 93, 124, and 150 m2 g-1 (±10 m2 g-1), respectively. SiO2 is found to form very small amorphous domains well dispersed in the TiO2 matrix. X-ray diffraction and Raman spectroscopy data show that anatase-to-rutile phase transition temperature is delayed by the presence of SiO2, enabling single-anatase phase photoanodes for DSSCs. According to the I×V measurements, photoanodes with 3% of SiO2 result in improved efficiency, which is mainly related to increased surface area and dye loading. In addition, the results suggest a gain in photocurrent related to the passivation of defects by SiO2.

Identifying thermal phase transitions of lignin–solvent mixtures using electrochemical impedance spectroscopy

2016 ◽  
Vol 18 (7) ◽  
pp. 1892-1897 ◽  
Author(s):  
Adam S. Klett ◽  
Jordan A. Gamble ◽  
Mark C. Thies ◽  
Mark E. Roberts
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Solvent Mixtures ◽  
New Approach ◽  
Thermal Phase ◽  
Solvent Systems ◽  
Thermal Phase Transitions

A new approach to measuring the phase-transition temperature of lignin–solvent systems using electrochemical impedance spectroscopy is reported.

New Approach to Determine the Phase Transition Temperature, Cloud Point, of Thermoresponsive Polymers

2013 ◽  
Vol 50 (6) ◽  
pp. 581-587 ◽  
Author(s):  
Marli L. Tebaldi ◽  
Luana A. Fiel ◽  
Amilton M. Santos ◽  
Silvia S. Guterres ◽  
Adriana R. Pohlmann
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Cloud Point ◽  
Phase Transition Temperature ◽  
Thermoresponsive Polymers ◽  
New Approach

Effect of Iron and Vanadium on the Phase Transition of Titanium Dioxide Obtained by Polymeric Precursor Method

2016 ◽  
Vol 881 ◽  
pp. 18-23
Author(s):  
Eduardo Felipe de Carli ◽  
Maycon dos Santos ◽  
Natali Amarante da Cruz ◽  
Daniela Cristina Manfroi ◽  
Jusinei Meireles Stropa ◽  
...  
Keyword(s):  
Phase Transition ◽  
Titanium Dioxide ◽  
Phase Formation ◽  
Anatase Phase ◽  
Synthesis Method ◽  
Rutile Phase ◽  
Polymeric Precursor Method ◽  
Polymeric Precursor ◽  
Precursor Method ◽  
Powder Samples

The titanium dioxide phase formation is dependent on the synthesis method, temperature of calcination and modifiers insertion. By using chemical methods, such as Polymeric Precursor Method, the organic impurities or extrinsic defects caused by doping play an important rule on the formation of precursor structure before the phase crystallization above 500 oC. Some dopants can change the decomposition mechanism of the precursor, which affects the anatase-rutile phase transition. In this work, the Polymeric Precursor Method was used to synthesize titanium dioxide powder samples in order to investigate the effects of iron (III) and vanadium (V) dopants on the phase formation. Through thermal analysis of polymeric precursors and X-ray diffractometry for calcined powder samples it was possible to show the existence of antagonistic effects for both investigated dopants. While the iron doping reduces the anatase phase tetragonality and delays the rutile phase conversion, the vanadium one changes the mechanism of decomposition of polymeric precursor and leads to more amount of rutile phase.

Liquid–solid transition of water confined in nanoporous titanium dioxide

2016 ◽  
Vol 30 (19) ◽  
pp. 1650250
Author(s):  
Xin Gao ◽  
Qiang Wang ◽  
Gang Sun ◽  
Chenxi Li ◽  
Lin Hu
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Titanium Dioxide ◽  
Transition Temperature ◽  
Pore Size ◽  
Phase Transition Temperature ◽  
Porous Titanium ◽  
Molar Enthalpy ◽  
Scanning Calorimetry ◽  
Filling Fraction

In this work, we performed differential scanning calorimetry (DSC) experiments to investigate the phase transition temperature and the molar enthalpy of the absorbed water confined in porous titanium dioxide. The porous titanium dioxide with three different pore size distribution and different filling fraction of the absorbed water were examined. We found that both the pore size of the examined samples and the filling fraction of the absorbed water affected the water’s phase transition temperature and its molar enthalpy.

scholarly journals Effect of Cu doping on the anatase-to-rutile phase transition in TiO2 photocatalysts: Theory and experiments

2019 ◽  
Vol 246 ◽  
pp. 266-276 ◽  
Author(s):  
Ciara Byrne ◽  
Lorraine Moran ◽  
Daphne Hermosilla ◽  
Noemí Merayo ◽  
Ángeles Blanco ◽  
...  
Keyword(s):  
Phase Transition ◽  
Rutile Phase ◽  
Cu Doping ◽  
Tio2 Photocatalysts ◽  
Theory And Experiments

scholarly journals Effect of Zr Doping on the Magnetic and Phase Transition Properties of VO2 Powder

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 113
Author(s):  
Jing Xu ◽  
Haiying Wang ◽  
Zhihong Lu ◽  
Zhenhua Zhang ◽  
Zhaorui Zou ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Magnetic Measurements ◽  
Measurement Techniques ◽  
Rutile Phase ◽  
Saturation Magnetic Moment ◽  
Doping Effects ◽  
Powder Samples

In this work, V1−xZrxO2 powder (x = 0, 0.01, 0.02, 0.04) was synthesized by two step hydrothermal method. The micro-topography, magnetic and phase transition properties have been investigated using various measurement techniques. All prepared V1−xZrxO2 powder samples exhibit monoclinic structure at room temperature. With the Zr4+ ions doping concentration increased, the shapes of VO2 particles change from spherical to rectangular slice. Besides, the saturation magnetic moment of the samples decrease with the increase of doped Zr4+ ions concentration, while their phase transition temperature increase gradually with Zr ions doping at a rate of around 2 °C/at% on average. We investigated the Zr doping effects on V-V dimers and confirmed the role of V-V dimers in phase transition. We speculate that more V-V dimers form with Zr doping by magnetic measurements, which result in the monoclinic phase of Zr-doped VO2 sample is more stable than rutile phase. Therefore the phase transition temperature is elevated by Zr doping in our experiment. We further consider that the VO2 phase transition should be ascribed to Peierls transition caused by the changing of V-V dimers.

Preparation of Nano-Sized TiO2 Photocatalysts by a Multi-Gelation Method and Their Application to the Degradation of 2-Propanol Diluted in Water

2005 ◽  
Vol 486-487 ◽  
pp. 93-96
Author(s):  
B. Neppolian ◽  
Hiromi Yamashita ◽  
Yusuke Okada ◽  
H. Nishijima ◽  
Masakazu Anpo
Keyword(s):  
Phase Transition ◽  
Particle Size ◽  
Photocatalytic Activity ◽  
Phase Composition ◽  
Pore Diameter ◽  
Rutile Phase ◽  
Tio2 Photocatalysts ◽  
Tio2 Particles ◽  
Control Of Parameters ◽  
Ph Swing

TiO2 photocatalysts prepared by a novel multi-gelation method showed good photocatalytic activity for the degradation of 2-propanol diluted in water by the control of parameters such as particle size, surface area, crystallinity, pore-volume, pore-diameter as well as anatase and rutile phase composition by changing the number of pH swings during preparation. In particular, with this method the phase transition from anatase to rutile at higher pH swing times can be controlled and high purity and uniformity of the TiO2 particles which leads to higher photocatalytic activity of the particles can be achieved. From our experimental results, it has been observed that TiO2 catalysts prepared by this unique multi-gelation method, i.e., adopting variations in the pH swing, significantly shows higher photocatalytic activity for the degradation of 2- propanol diluted in water. It can be considered a viable alternative over existing commercial methods for the preparation of photofunctional catalysts.

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