The critical size mechanism for the anatase to rutile transformation in TiO2 and doped-TiO2

Reidy, D.J.; Holmes, Justin D.; Morris, Michael A.

doi:10.1016/j.jeurceramsoc.2005.03.246

Cited by 169 publications

(106 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The presence of unintentional impurities or intentional dopants has a strong effect on the kinetics of the anatase to rutile transition [170]. Variable results have been reported in the sense that dopants can have the effect of hindering or enhancing the transition to rutile.…”

Section: Dopant Effectsmentioning

confidence: 99%

“…However, the lower surface energy of the anatase planes relative to those of rutile [76] cause the former to be more stable for crystallites of extremely small sizes and correspondingly high surface areas. In these cases, surface energy considerations outweigh those of bulk thermodynamics and so, for crystallites below a critical size (45 nm [170], 14 nm [76], and 11 nm [207]), anatase has a lower total (bulk and surface) free energy [73,76,206]. Further, the size above which rutile becomes more stable depends on stresses [76].…”

Section: Morphological Effectsmentioning

confidence: 99%

“…Significant rutile grain growth is exhibited as the anatase to rutile transition proceeds [67,73,108,158,170,176,177,208]. Rutile grains coarsen at the expense of neighbouring anatase during coalescence until the large rutile grains begin to impinge on each other [111,114].…”

Section: Morphological Effectsmentioning

confidence: 99%

See 2 more Smart Citations

Review of the anatase to rutile phase transformation

2010

View full text Add to dashboard Cite

Titanium dioxide, TiO 2 , is an important photocatalytic material that exists as two main polymorphs, anatase and rutile. The presence of either or both of these phases impacts on the photocatalytic performance of the material. The present work reviews the anatase to rutile phase transformation. The synthesis and properties of anatase and rutile are examined, followed by a discussion of the thermodynamics of the phase transformation and the factors affecting its observation. A comprehensive analysis of the reported effects of dopants on the anatase to rutile phase transformation and the mechanisms by which these effects are brought about is presented in this review, yielding a plot of the cationic radius versus the valence characterised by a distinct boundary between inhibitors and promoters of the phase transformation. Further, the likely effects of dopant elements, including those for which experimental data are unavailable, on the phase transformation are deduced and presented on the basis of this analysis.

show abstract

Section: Dopant Effectsmentioning

confidence: 99%

Section: Morphological Effectsmentioning

confidence: 99%

See 1 more Smart Citation

Review of the anatase to rutile phase transformation

2010

View full text Add to dashboard Cite

show abstract

“…8 The grain size of the initial powder is one of most important parameters in determining the phase stability of TiO 2 , especially in the nanometre scale region. 9 Li et al 10 studied the polymorphic phase transformation via enthalpy calculations and pointed out that the stability of the TiO 2 polymorphs is crystallite-sizedependent; anatase is the most stable phase at <11 nm, brookite is the preferable phase at sizes between 11 and 35 nm, while rutile is favored at sizes larger than 35 nm. The grain size of the final product is of interest in different applications.…”

Section: Introductionmentioning

confidence: 99%

The role of brookite in mechanical activation of anatase-to-rutile transformation of nanocrystalline TiO2: An XRD and Raman spectroscopy investigation

2011

View full text Add to dashboard Cite

The mechanism of phase transformation in nanocrystalline TiO 2 powders at ambient temperature during high energy ball milling and the role of brookite phase in anatase-to-rutile phase transformation were investigated by the use of Rietveld analysis of X-ray diffraction patterns and Raman spectroscopy methods. The milling process was performed on a fully anatase phase nanocrystalline TiO 2 powder via a high energy planetary ball mill with different ball-to-powder weight ratios followed by annealing of the as-milled samples. Some transformation from anatase-to-brookite was observed in all as-milled powders by high resolution transmission electron microscopy. It was proposed that brookite occurs at the {112} twin surfaces of anatase phase and therefore promotes anatase-to-rutile phase transformation. Based on the XRD and Raman results, it was proposed that brookite appears as an essential intermediate phase in mechanically induced anatase-to-rutile phase transformation which facilitates the phase transformation at ambient temperatures and also at higher temperatures during the post-annealing step.

show abstract

“…The phase composition has significant effect on the properties and performance of nano TiO 2 and therefore it is desirable to control the transformation to develop a particular phase or phase mixture subsequent to thermal treatment. The phase transformation depends on the growth process affected by defect concentration, grain boundary concentration and particle packing as well [7][8][9]. The final properties of the nano TiO 2 are naturally dependent on the method of synthesis, the experimental conditions and the structure of the polymorph.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Investigation on Sol Gel Derived TiO<sub>2</sub> Nanoparticles

Singh¹,

Mukherjee²,

Ghosh³

et al. 2017

JAN

View full text Add to dashboard Cite

Abstract. TiO 2 nanoparticles were synthesized by sol-gel method from titanium tetra isopropoxide. Influence of heat treatment on structural and morphological properties of TiO 2 nanoparticles was investigated by XRD and SEM. Spectral properties of the nanoparticles were investigated using FTIR, Raman spectroscopy, PL spectroscopy and UV-visible absorption spectroscopy. XRD analysis revealed the formation of mixed anatase and ruitle phase in the synthesized powder at 550 o C and existence of only rutile phase at 750 and 900 o C. The lattice parameters, crystallite sizes, volume of the unit cell, density and surface area of TiO 2 nanoparticles were determined from XRD analysis. SEM analysis showed that the prepared nanoparticles were in the nano regime, nearly spherical and larger agglomerated at lower temperature. EDX analysis showed that the TiO 2 composition obtained was near stoichiometric at lower temperature and the proportion of oxygen vacancy increased with the increase in temperature. The presence of Ti-O and Ti-O-Ti bonds was confirmed by FTIR spectra. PL spectroscopy showed that the change in surface states and presence of anatase and rutile phases of TiO 2 were also responsible for exhibiting the change in PL intensity. UV-visible absorption spectra showed the shifting of absorption edge towards the higher wavelength with the increase in temperature while the corresponding energy band gap of semiconductor nanoparticles decreased. Change in Raman spectra with the increase in temperature was observed due to anatase to rutile phase transformation and with the increase in the particle size.Keywords: TiO 2 nanopowder, sol-gel, annealing, spectroscopic properties. IntroductionTitania nanoparticles have important applications in the field of optical devices, sensor and photocatalysis [1,2]. These nanoparticles have different electrical, optical and magnetic properties compared to their bulk counterparts due to large surface to volume ratios and quantum size effect [3]. There are several factors in determining the important properties like, particle size, crystallinity and morphology that affect the performance of TiO 2 in applications [4][5][6]. TiO 2 as a wide indirect band gap n-type semiconductor and generally exist in the three polymorphs of TiO 2 are anatase (I4/amd), rutile (P42/mnm) and brookite (Pcab). Brookite exists in an orthorhombic structure while anatase and rutile both possess tetragonal unit cells. Among these, anatase is metastable at lower temperature and has excellent chemical and physical properties for environmental purification, although rutile is the more stable phase from thermodynamic point of view. The phase composition has significant effect on the properties and performance of nano TiO 2 and therefore it is desirable to control the transformation to develop a particular phase or phase mixture subsequent to thermal treatment. The phase transformation depends on the growth process affected by defect concentration, grain boundary concentration and particle packing as well [7][8][9]. ...

show abstract

The critical size mechanism for the anatase to rutile transformation in TiO2 and doped-TiO2

Cited by 169 publications

References 26 publications

Review of the anatase to rutile phase transformation

Review of the anatase to rutile phase transformation

The role of brookite in mechanical activation of anatase-to-rutile transformation of nanocrystalline TiO2: An XRD and Raman spectroscopy investigation

Spectroscopic Investigation on Sol Gel Derived TiO<sub>2</sub> Nanoparticles

Contact Info

Product

Resources

About